10-Q

UNITED STATES OF AMERICA

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

_______________________

FORM 10-Q

x	QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
FOR THE QUARTERLY PERIOD ENDED JUNE 30, 2018
OR
o	TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

FOR THE TRANSITION PERIOD FROM         TO       

Commission File Number 001-34223

_______________________

CLEAN HARBORS, INC.

(Exact name of registrant as specified in its charter)

Massachusetts	04-2997780
(State or Other Jurisdiction of Incorporation or Organization)	(IRS Employer Identification No.)
42 Longwater Drive, Norwell, MA	02061-9149
(Address of Principal Executive Offices)	(Zip Code)

(781) 792-5000

(Registrant’s Telephone Number, Including area code)

_______________________

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days. Yes x  No o

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). Yes  x  No o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and "emerging growth company" in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer x	Accelerated filer o
Non-accelerated filer o	Smaller reporting company o
(Do not check if a smaller reporting company)	Emerging growth company o

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Indicate by check mark whether the registrant is a shell company (as defined by Rule 12b-2 of the Exchange Act). Yes o  No x

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date.

Common Stock, $.01 par value	56,088,908
(Class)	(Outstanding as of July 30, 2018)

CLEAN HARBORS, INC.

QUARTERLY REPORT ON FORM 10-Q

TABLE OF CONTENTS

	Page No.
PART I: FINANCIAL INFORMATION
ITEM 1: Unaudited Financial Statements
Consolidated Balance Sheets	1
Unaudited Consolidated Statements of Operations	2
Unaudited Consolidated Statements of Comprehensive Income (Loss)	3
Unaudited Consolidated Statements of Cash Flows	4
Unaudited Consolidated Statements of Stockholders’ Equity	5
Notes to Unaudited Consolidated Financial Statements	6
ITEM 2: Management’s Discussion and Analysis of Financial Condition and Results of Operations	32
ITEM 3: Quantitative and Qualitative Disclosures About Market Risk	42
ITEM 4: Controls and Procedures	42
PART II: OTHER INFORMATION
ITEM 1: Legal Proceedings	43
ITEM 1A: Risk Factors	43
ITEM 2: Unregistered Sales of Equity Securities and Use of Proceeds	43
ITEM 3: Defaults Upon Senior Securities	43
ITEM 4: Mine Safety Disclosures	43
ITEM 5: Other Information	43
ITEM 6: Exhibits	44
Signatures	45

CLEAN HARBORS, INC. AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

(in thousands)

	June 30, 2018			December 31, 2017
ASSETS	(unaudited)
Current assets:
Cash and cash equivalents	$	197,068		$	319,399
Short-term marketable securities	36,862			38,179
Accounts receivable, net of allowances aggregating $34,033 and $27,799, respectively	590,580			528,924
Unbilled accounts receivable	62,762			35,922
Deferred costs	20,832			20,445
Inventories and supplies	193,544			176,012
Prepaid expenses and other current assets	34,834			35,175
Total current assets	1,136,482			1,154,056
Property, plant and equipment, net	1,609,382			1,587,365
Other assets:
Goodwill	497,251			478,523
Permits and other intangibles, net	455,920			469,128
Other	16,426			17,498
Total other assets	969,597			965,149
Total assets	$	3,715,461		$	3,706,570
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
Current portion of long-term obligations	$	4,000		$	4,000
Accounts payable	247,821			224,231
Deferred revenue	68,705			67,822
Accrued expenses	200,135			187,982
Current portion of closure, post-closure and remedial liabilities	23,007			19,782
Total current liabilities	543,668			503,817
Other liabilities:
Closure and post-closure liabilities, less current portion of $6,514 and $6,444, respectively	58,990			54,593
Remedial liabilities, less current portion of $16,493 and $13,338, respectively	104,782			111,130
Long-term obligations, less current portion	1,624,727			1,625,537
Deferred taxes, unrecognized tax benefits and other long-term liabilities	222,246			223,291
Total other liabilities	2,010,745			2,014,551
Commitments and contingent liabilities (See Note 16)
Stockholders’ equity:
Common stock, $.01 par value:
Authorized 80,000,000; shares issued and outstanding 56,087,256 and 56,501,190 shares, respectively	561			565
Additional paid-in capital	664,948			686,962
Accumulated other comprehensive loss	(194,095		)	(172,407		)
Accumulated earnings	689,634			673,082
Total stockholders’ equity	1,161,048			1,188,202
Total liabilities and stockholders’ equity	$	3,715,461		$	3,706,570

The accompanying notes are an integral part of these unaudited consolidated financial statements.

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CLEAN HARBORS, INC. AND SUBSIDIARIES

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS

(in thousands except per share amounts)

	Three Months Ended						Six Months Ended
	June 30,						June 30,
	2018			2017			2018			2017
Revenues:
Service revenues	$	696,779		$	610,940		$	1,316,498		$	1,171,154
Product revenues	152,361			141,848			282,420			270,575
Total revenues	849,140			752,788			1,598,918			1,441,729
Cost of revenues: (exclusive of items shown separately below)
Service revenues	473,423			412,356			921,072			803,443
Product revenues	110,161			107,447			208,937			212,945
Total cost of revenues	583,584			519,803			1,130,009			1,016,388
Selling, general and administrative expenses	125,995			112,294			241,083			224,515
Accretion of environmental liabilities	2,448			2,416			4,878			4,706
Depreciation and amortization	72,760			71,531			147,604			143,943
Income from operations	64,353			46,744			75,344			52,177
Other income (expense), net	846			(833		)	547			(2,382		)
Loss on early extinguishment of debt	—			(6,045		)	—			(6,045		)
Gain on sale of business	—			31,722			—			31,722
Interest expense, net of interest income of $587, $311, $1,350 and $520, respectively	(20,769		)	(22,492		)	(41,039		)	(45,068		)
Income before provision for income taxes	44,430			49,096			34,852			30,404
Provision for income taxes	13,683			23,216			16,736			25,917
Net income	$	30,747		$	25,880		$	18,116		$	4,487
Earnings per share:
Basic	$	0.55		$	0.45		$	0.32		$	0.08
Diluted	$	0.54		$	0.45		$	0.32		$	0.08
Shares used to compute earnings per share - Basic	56,410			57,190			56,304			57,226
Shares used to compute earnings per share - Diluted	56,505			57,336			56,399			57,349

The accompanying notes are an integral part of these unaudited consolidated financial statements.

2

CLEAN HARBORS, INC. AND SUBSIDIARIES

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)

(in thousands)

	Three Months Ended					Six Months Ended
	June 30,					June 30,
	2018			2017		2018			2017
Net income	$	30,747		$	25,880	$	18,116		$	4,487
Other comprehensive (loss) income:
Unrealized (losses) gains on available-for-sale securities (net of tax of $8, $20, $88 and $122, respectively)	(11		)	27		(206		)	159
Reclassification adjustment for losses on available-for-sale securities included in net income (net of taxes of $0, $29, $0 and $79, respectively)	—			47		—			143
Foreign currency translation adjustments (including a tax benefit of $5.6 million in 2018)	(4,931		)	15,024		(21,482		)	20,847
Other comprehensive (loss) income	(4,942		)	15,098		(21,688		)	21,149
Comprehensive income (loss)	$	25,805		$	40,978	$	(3,572	)	$	25,636

The accompanying notes are an integral part of these unaudited consolidated financial statements.

3

CLEAN HARBORS, INC. AND SUBSIDIARIES

UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS

(in thousands)

	Six Months Ended
	June 30,
	2018			2017
Cash flows from operating activities:
Net income	$	18,116		$	4,487
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	147,604			143,943
Allowance for doubtful accounts	7,389			3,580
Amortization of deferred financing costs and debt discount	1,881			1,660
Accretion of environmental liabilities	4,878			4,706
Changes in environmental liability estimates	(673		)	(129		)
Deferred income taxes	(10		)	190
Stock-based compensation	6,639			5,172
Other (income) expense, net	(547		)	2,382
Gain on sale of business	—			(31,722		)
Loss on early extinguishment of debt	—			6,045
Environmental expenditures	(4,585		)	(6,102		)
Changes in assets and liabilities, net of acquisitions
Accounts receivable and unbilled accounts receivable	(62,764		)	(31,154		)
Inventories and supplies	(18,625		)	(6,307		)
Other current assets	180			13,918
Accounts payable	23,605			(2,686		)
Other current and long-term liabilities	6,582			8,948
Net cash from operating activities	129,670			116,931
Cash flows used in investing activities:
Additions to property, plant and equipment	(94,139		)	(88,742		)
Proceeds from sale and disposal of fixed assets	2,641			2,121
Acquisitions, net of cash acquired	(123,750		)	(9,277		)
Proceeds from sale of businesses, net of transactional costs	—			46,391
Additions to intangible assets, including costs to obtain or renew permits	(2,106		)	(1,239		)
Proceeds from sale of available-for-sale securities	11,214			376
Purchases of available-for-sale securities	(10,001		)	—
Net cash used in investing activities	(216,141		)	(50,370		)
Cash flows (used in) from financing activities:
Change in uncashed checks	(2,803		)	(8,361		)
Proceeds from exercise of stock options	—			46
Tax payments related to withholdings on vested restricted stock	(2,175		)	(2,132		)
Repurchases of common stock	(26,482		)	(12,257		)
Deferred financing costs paid	(468		)	(4,727		)
Premiums paid on early extinguishment of debt	—			(4,665		)
Principal payment on debt	(2,000		)	(296,202		)
Issuance of senior secured notes, net of discount	—			399,000
Net cash (used in) from financing activities	(33,928		)	70,702
Effect of exchange rate change on cash	(1,932		)	2,106
(Decrease) increase in cash and cash equivalents	(122,331		)	139,369
Cash and cash equivalents, beginning of period	319,399			306,997
Cash and cash equivalents, end of period	$	197,068		$	446,366
Supplemental information:
Cash payments for interest and income taxes:
Interest paid	$	40,745		$	50,432
Income taxes paid	14,118			13,407
Non-cash investing activities:
Property, plant and equipment accrued	13,041			16,213
Transfer of inventory to property, plant and equipment	—			12,641

The accompanying notes are an integral part of these unaudited consolidated financial statements.

4

CLEAN HARBORS, INC. AND SUBSIDIARIES

UNAUDITED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY

(in thousands)

	Common Stock								Accumulated Other Comprehensive Loss
	Number of Shares		$ 0.01 Par Value			Additional Paid-in Capital						Accumulated Earnings			Total Stockholders’ Equity
Balance at January 1, 2018	56,501		$	565		$	686,962		$	(172,407	)	$	673,082		$	1,188,202
Cumulative effect of change in accounting principle	—		—			—			—			(1,564		)	(1,564		)
Net income	—		—			—			—			18,116			18,116
Other comprehensive loss	—		—			—			(21,688		)	—			(21,688		)
Stock-based compensation	—		—			6,639			—			—			6,639
Issuance of restricted shares, net of shares remitted and tax withholdings	118		1			(2,176		)	—			—			(2,175		)
Repurchases of common stock	(532	)	(5		)	(26,477		)	—			—			(26,482		)
Balance at June 30, 2018	56,087		$	561		$	664,948		$	(194,095	)	$	689,634		$	1,161,048

The accompanying notes are an integral part of these unaudited consolidated financial statements.

5

CLEAN HARBORS, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(1) BASIS OF PRESENTATION

The accompanying consolidated interim financial statements are unaudited and include the accounts of Clean Harbors, Inc. and its subsidiaries (collectively, “Clean Harbors,” the “Company” or "we") and have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) and, in the opinion of management, include all adjustments which are of a normal recurring nature, necessary for a fair presentation of the financial position, results of operations, and cash flows for the periods presented. Management has made estimates and assumptions affecting the amounts reported in the Company's consolidated interim financial statements and accompanying footnotes, actual results could differ from those estimates and judgments. The results for interim periods are not necessarily indicative of results for the entire year or any other interim periods. The financial statements presented herein should be read in connection with the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017.

(2) SIGNIFICANT ACCOUNTING POLICIES

The Company's significant accounting policies are described in Note 2, "Significant Accounting Policies," in the Company's Annual Report on Form 10-K for the year ended December 31, 2017. There have been no material changes in these policies or their application except for the changes described below.

Reclassifications

During the first quarter of fiscal year 2018, certain of the Company's businesses undertook a reorganization which included changes to the underlying business and management structures. The reorganization resulted in combining the Environmental Services businesses from an operational and management perspective and is expected to deepen customer relationships and allow for efficiencies across the Company's operations through the sharing of resources, namely labor and equipment which will reduce third party spend and promote the cross selling of such business offerings. In connection with this reorganization, the Company’s chief operating decision maker also requested changes in the information that he regularly reviews for purposes of allocating resources and assessing performance. These changes required a reconsideration of the Company’s operating segments in the first quarter of 2018 and resulted in a change in the Company’s assessment of its operating segments. Upon reconsideration of the identification of the Company’s operating segments, the Company concluded that there are now two operating segments for disclosure in accordance with ASC 280 Segment reporting; (i) the Environmental Services segment which consists of the Company’s historical Technical Services, Industrial Services, Field Services and Oil, Gas and Lodging businesses and (ii) the Safety-Kleen segment. See Note 18, "Segment Reporting," for more information. The amounts presented for the three and six months ended June 30, 2017 have been recast to reflect the impact of such changes. These reclassifications and adjustments had no effect on the consolidated statements of operations, consolidated statements of comprehensive loss, consolidated statements of cash flows or consolidated statements of stockholders' equity for any of the periods presented.

Recent Accounting Pronouncements

Standards implemented

In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606), which replaces numerous requirements in U.S. GAAP, including industry-specific requirements, and provides companies with a single revenue recognition model for recognizing revenue from contracts with customers. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the modified retrospective method). On January 1, 2018, the Company adopted Topic 606 using the modified retrospective method for all contracts. Results for reporting periods beginning on the date of adoption are presented under ASC 606, while prior period amounts have not been adjusted and continue to be reported in accordance with the Company's historical accounting methodology pursuant to ASC 605, Revenue Recognition (“ASC 605”). Upon adoption, a cumulative effect adjustment was not required as the majority of the Company’s contracts are recognized based on time and materials incurred and were not impacted by the new guidance. The Company has concluded that the most significant impact of the standard relates to the incremental disclosures required.

In October 2016, the FASB issued ASU 2016-16, Income Tax - Intra-Entity Transfers of Assets Other than Inventory. The amendment improves the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The

6

Company adopted the amendment on a modified retrospective basis effective January 1, 2018. As a result of adoption, the Company recorded a cumulative effect adjustment that reduced retained earnings by $1.6 million.

In March 2017, the FASB issued ASU 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendment requires an employer to report the service cost component of net benefit cost in the same line item as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. In addition, the amendment allows only the service cost component to be eligible for capitalization when applicable. The Company adopted the amendment in the first quarter of 2018. Adoption did not have a material impact on the Company's consolidated financial statements.

Standards to be implemented

The Company is evaluating the impact that the below standards to be implemented will have on the Company's consolidated financial statements.

In February 2016, FASB issued ASU 2016-02, Leases (Topic 842). The amendment increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. In February 2018, FASB issued ASU 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842. The amendment clarifies that land easements are within the scope of the new leases standard (ASC 842) and introduces a new transition practical expedient allowing a company to not assess whether existing and expired land easements that were not previously accounted for as leases under current US GAAP (ASC 840) are or contain leases under ASC 842. In July 2018, FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases. The amendment provides improvements that clarify specific aspects of the guidance in ASU 2016-02. The Company will adopt the new standard beginning on January 1, 2019. A modified retrospective transition approach is required for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. While the Company is still continuing to assess the effect of adoption, it expects that the new standard will have a material effect on its consolidated balance sheet related to the recognition of new assets and lease liabilities. In preparation for the adoption of the guidance, the Company is in the process of implementing new software and assessing changes to controls and processes to enable the preparation of financial information.

In June 2016, FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendment changes the way entities recognize impairment of many financial assets, including accounts receivable and investments in debt securities, by requiring immediate recognition of estimated credit losses expected to occur over their remaining lives. The amendment should be applied using a modified-retrospective approach and is effective for the Company for annual and interim reporting periods beginning after January 1, 2020, with early adoption permitted. The Company is currently evaluating the impact ASU 2016-13 will have on its consolidated financial statements.

In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendment better aligns an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The amendment is effective for the Company for annual and interim reporting periods beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the impact ASU 2017-12 will have on its consolidated financial statements.

(3) REVENUES

Revenue Recognition

Revenues are recognized when control of the promised goods or services is transferred to the Company’s customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services.

Nature of Goods and Services

The Company generates services and product revenues through its Environmental Services and Safety-Kleen operating segments. The majority of the Company’s contracts are for services, which are recognized based on time and materials incurred at contractually agreed-upon rates. Product revenues are recognized when the products are delivered and control transfers to the customer. The Company’s payment terms vary by the type and location of its customers and the products or services offered. The

7

term between invoicing and when payment is due is not significant. The Company excludes sales taxes that it collects from customers from its revenues.

Disaggregation of Revenue

The following table presents the Company’s revenues disaggregated by revenue source (in thousands):

	For the Three Months Ended June 30, 2018
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	408,127	$	306,059	$	363	$	714,549
Canada	111,789		22,656		146		134,591
	519,916		328,715		509		849,140
Sources of Revenue (1)
Technical Services	257,006		—		—		$	257,006
Field and Emergency Response Services	76,092		—		—		76,092
Industrial Services	161,046		—		—		161,046
Oil, Gas and Lodging Services and Other	25,772		—		509		26,281
Safety-Kleen Environmental Services	—		200,034		—		200,034
Kleen Performance Products	—		128,681		—		128,681
Total third party revenues	$	519,916	$	328,715	$	509	$	849,140

	For the Three Months Ended June 30, 2017
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	343,323	$	280,617	$	155	$	624,095
Canada	106,308		22,339		46		128,693
	449,631		302,956		201		752,788
Sources of Revenue (1)
Technical Services	254,487		—		—		254,487
Field and Emergency Response Services	70,707		—		—		70,707
Industrial Services	99,733		—		—		99,733
Oil, Gas and Lodging Services and Other	24,704		—		201		24,905
Safety-Kleen Environmental Services	—		192,817		—		192,817
Kleen Performance Products	—		110,139		—		110,139
Total third party revenues	$	449,631	$	302,956	$	201	$	752,788

	For the Six Months Ended June 30, 2018
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	752,099	$	593,701	$	508	$	1,346,308
Canada	207,505		44,932		173		252,610
	959,604		638,633		681		1,598,918
Sources of Revenue (1)
Technical Services	493,312		—		—		493,312
Field and Emergency Response Services	146,027		—		—		146,027
Industrial Services	264,809		—		—		264,809
Oil, Gas and Lodging Services and Other	55,456		—		681		56,137
Safety-Kleen Environmental Services	—		394,195		—		394,195
Kleen Performance Products	—		244,438		—		244,438
Total third party revenues	$	959,604	$	638,633	$	681	$	1,598,918

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	For the Six Months Ended June 30, 2017
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	657,106	$	552,688	$	288	$	1,210,082
Canada	188,432		43,169		46		231,647
	845,538		595,857		334		1,441,729
Sources of Revenue (1)
Technical Services	484,705		—		—		484,705
Field and Emergency Response Services	131,726		—		—		131,726
Industrial Services	174,801		—		—		174,801
Oil, Gas and Lodging Services and Other	54,306		—		334		54,640
Safety-Kleen Environmental Services	—		384,544		—		384,544
Kleen Performance Products	—		211,313		—		211,313
Total third party revenues	$	845,538	$	595,857	$	334	$	1,441,729

______________________

1. All revenue except Kleen Performance Products and product sales within Safety-Kleen Environmental Services, including allied products and direct blended oil sales, are recognized over time. Kleen Performance Products and Safety-Kleen Environmental Services product revenues are recognized at a point in time.

Technical Services. Technical Services revenues are generated from fees charged for waste material management and disposal services including onsite environmental management services, collection and transportation, packaging, recycling, treatment and disposal of waste. Revenue is primarily generated by short-term projects, most of which are governed by master service agreements that are long-term in nature. These master service agreements are typically entered into with the Company's larger customers and outline the pricing and legal frameworks for such arrangements. Services are provided based on purchase orders or agreements with the customer and include prices based upon units of volume of waste, and transportation and other fees. Collection and transportation revenues are recognized over time, as the customer receives and consumes the benefits of the service as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. Revenues for treatment and disposal of waste are recognized upon completion of treatment, final disposition in a landfill or incineration, or when the waste is shipped to a third party for processing and disposal. The Company periodically enters into bundled arrangements for the collection and transportation and disposal of waste. For such arrangements, transportation and disposal are considered distinct performance obligations and the Company allocates revenue to each based on their relative standalone selling price (i.e. the estimated price that a customer would pay for the services on a standalone basis). Revenues from waste that is not yet completely processed and disposed and the related costs are deferred. The revenue is recognized and the deferred costs are expensed when the related services are completed. The period between collection and transportation and the final processing and disposal ranges depending on location of the customer, but generally is measured in days.

Field and Emergency Response Services. Field Services revenues are generated from cleanup services at customer sites, including municipalities and utilities, or other locations on a scheduled or emergency response basis. Services include confined space entry for tank cleaning, site decontamination, large remediation projects, demolition, spill cleanup on land and water, railcar cleaning, product recovery and transfer and vacuum services. Additional services include filtration and water treatment services. Response services for environmental emergencies include any scale from man-made disasters such as oil spills, to natural disasters such as hurricanes. These services are provided based on purchase orders or agreements with customers and include prices generally based upon daily, hourly or job rates for equipment, materials and personnel. The Company recognizes revenue for these services over time, as the customer receives and consumes the benefits of the service as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. The duration of such services can be over a number of hours, several days or even months for larger scale projects.

Industrial Services. Industrial Services revenues are generated from industrial and specialty services provided to refineries, mines, upgraders, chemical plants, pulp and paper mills, manufacturing facilities, power generation facilities and other industrial customers throughout North America. Services include in-plant cleaning and maintenance services, plant outage and turnaround

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services, decoking and pigging, chemical cleaning, high and ultra-high pressure water cleaning, pipeline inspection and coating services, large tank and surface impoundment cleaning, oilfield transport, daylighting, production services and directional boring services (previously included in Oil, Gas and Lodging service offerings) supporting drilling, completions and production programs. These services are provided based on purchase orders or agreements with the customer and include prices based upon daily, hourly or job rates for equipment, materials and personnel. The Company recognizes revenue for these services over time, as the customer receives and consumes the benefits of the service as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred.

Safety-Kleen Environmental Services. Safety-Kleen Environmental Services revenues are generated from providing parts washer services, containerized waste handling and disposal services, oil collection services, direct sales of blended oil products, and other complementary services and product sales. Containerized waste services consist of profiling, collecting, transporting and recycling or disposing of a wide variety of waste. Other complementary products and services include vacuum services, sale of allied supply products and other environmental services. Revenues from parts washer services include fees charged to customers for their use of parts washer equipment, to clean and maintain parts washer equipment and to remove and replace used cleaning fluids. Parts washer services are considered a single performance obligation due to the highly integrated and interdependent nature of the arrangement. Revenue from parts washer services is recognized over the service interval as the customer receives the benefit of the service. Collection and transportation revenues are recognized over time, as the customer receives and consumes the benefits of the service as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. Product revenue is recognized upon the transfer of control. Control transfers when the products are delivered to the customer.

Kleen Performance Products. Kleen Performance Products revenues are generated from sales of high quality base and blended lubricating oils to third-party distributors, government agencies, fleets, railroads and industrial customers. The business also sells recycled fuel oil to asphalt plants, industrial plants, blenders, pulp and paper companies, vacuum gas oil producers and marine diesel oil producers. Revenue for oil products is recognized at a point in time, upon the transfer of control. Control transfers when the products are delivered to the customer.

Oil, Gas and Lodging Services and Other. Oil, Gas and Lodging Services and Other is primarily comprised of revenues generated from providing Oil and Gas Field Services that support upstream activities such as exploration and drilling for oil and gas companies and Lodging Services to customers in Western Canada. The Company recognizes Oil and Gas Field Services revenue over time, as the customer receives and consumes the benefits of the service as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. Revenue for lodging accommodation services is recognized over time based on passage of time. Revenue for manufacturing services is recognized over time using a cost-to-cost measure of progress or completed units to depict the transfer of assets to the customer.

Contract Balances

	June 30, 2018		December 31, 2017		June 30, 2017		December 31, 2016
Receivables	$	590,580	$	528,924	$	512,375	$	496,226
Contract Assets (Unbilled Receivables)	62,762		35,922		46,576		36,190
Contract Liabilities (Deferred Revenue)	68,705		67,822		72,089		64,397

The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables (contract assets), and customer advances and deposits or deferred revenue (contract liabilities) on the Consolidated Balance Sheet. Generally, billing occurs subsequent to revenue recognition, as a right to payment is not just subject to passage of time, resulting in contract assets. Contract assets are generally classified as current. The Company sometimes receives advances or deposits from its customers before revenue is recognized, resulting in contract liabilities. These assets and liabilities are reported on the Consolidated Balance Sheet on a contract-by-contract basis at the end of each reporting period. As part of the acquisition of the Veolia Business on February 23, 2018, the Company acquired receivables and contract assets of $20.5 million and $17.6 million, respectively. Changes in the contract asset and liability balances during the six-month period ended June 30, 2018 and June 30, 2017 were not materially impacted by any other factors. The contract liability balances at the beginning of each period presented were fully recognized in the subsequent three-month period.

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Remaining Performance Obligations

Remaining performance obligations represent the transaction price of orders for which work has not been performed. As of June 30, 2018, all remaining performance obligations were for contracts with an original expected length of one year or less.

Variable Consideration

The nature of the Company's contracts gives rise to certain types of variable consideration, including in limited cases volume and payment discounts. The Company estimates the amount of variable consideration to include in the estimated transaction price based on historical experience, anticipated performance and its best judgment at the time and to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Variable consideration was not material in any of the periods presented.

Contract Costs

Contract costs include direct and incremental costs to obtain or fulfill a contract. The Company’s contract costs that are subject to capitalization are comprised of costs associated with parts washer services and costs associated with the treatment and disposal of waste. Parts washer costs include costs of solvent, commissions paid relating to revenue generated from parts washer services, and transportation costs associated with transferring the product picked up from the services as it is returned to the Company’s facilities or a third party site. Costs related to the treatment of waste include costs for waste receiving, drum movement and storage, waste consolidation and transportation between facilities. Deferred costs associated with parts washer services are amortized ratably over the average service interval, which ranges between seven and 14 weeks. Deferred costs related to treatment and disposal of waste are recognized when the corresponding waste is disposed of and are included in Deferred Costs within total current assets in the Company’s consolidated balance sheets. The deferred contract cost balances at the beginning of each period presented were fully recognized in cost of revenue in the subsequent three-month period.

(4) BUSINESS COMBINATIONS

2018 Acquisition

On February 23, 2018, the Company completed the acquisition of the U.S. Industrial Cleaning Business of Veolia Environmental Services North America LLC (the "Veolia Business"). The acquisition will provide significant scale and industrial services capabilities while increasing the size of the Company's existing U.S. Industrial Services business. The Company acquired the Veolia Business for a purchase price of $120.0 million subject to certain post-closing adjustments. The acquisition was financed with cash on hand. The amount of revenue from the Veolia Business included in the Company's results of operations for the three and six months ended June 30, 2018 was $46.3 million and $63.9 million, respectively. The amount of pre-tax income for the three and six months ended June 30, 2018 was $2.1 million and $3.3 million, respectively. During the three and six months ended June 30, 2018, the Company incurred acquisition-related costs of approximately $0.4 million and $0.9 million, respectively, in connection with the transaction which are included in selling, general and administrative expenses in the consolidated statements of operations.

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The allocation of the purchase price was based on preliminary estimates of the fair value of assets acquired and liabilities assumed as of February 23, 2018, as the Company is continuing to obtain information to complete its valuation of these accounts and the associated tax accounting. The components and preliminary allocation of the purchase price consist of the following amounts (in thousands):

	At Acquisition Date			Measurement Period Adjustments			At Acquisition Date As Reported June 30, 2018
Accounts receivable, including unbilled receivables	$	40,773		$	(2,691	)	$	38,082
Inventories and supplies	1,442			(316		)	1,126
Prepaid expenses and other current assets	1,005			(80		)	925
Property, plant and equipment	72,244			—			72,244
Permits and other intangibles	5,140			—			5,140
Current liabilities	(15,908		)	(2,631		)	(18,539		)
Closure and post-closure liabilities	(604		)	—			(604		)
Total identifiable net assets	104,092			(5,718		)	98,374
Goodwill	15,908			5,718			21,626
Total purchase price	$	120,000		$	—		$	120,000

The weighted average amortization period for the intangibles acquired is 8.2 years. The excess of the total purchase price, which includes the aggregate cash consideration paid in excess of the fair value of the tangible net assets and intangible assets acquired, was recorded as goodwill. The goodwill recognized is attributable to the expected operating synergies and growth potential that the Company expects to realize from this acquisition. Goodwill generated from the acquisition is deductible for tax purposes.

Pro forma revenue and earnings amounts on a combined basis as if this acquisition had been completed on January 1, 2017 are immaterial to the consolidated financial statements of the Company since that date.

2017 Acquisitions

On July 14, 2017, the Company acquired Lonestar West Inc. ("Lonestar"), a public company headquartered in Alberta, Canada, for approximately CAD $41.8 million, ($33.1 million USD), net of cash acquired, which included an equity payout of CAD $0.72 per share to Lonestar shareholders and the assumption of approximately CAD $21.3 million ($16.8 million USD) in outstanding debt, which Clean Harbors subsequently repaid. The acquisition supports the Company's growth in the daylighting and hydro excavation services markets. In addition to increasing the size of the Company's hydro vac fleet, Lonestar's network of locations provides the Company with direct access to key geographic markets in both the United States and Canada. The acquired company is included in the Environmental Services segment. In connection with this acquisition, a goodwill amount of $2.8 million was recognized.

On January 31, 2017, the Company acquired a privately held company for a purchase price of approximately $11.9 million in cash, net of cash acquired. The acquired business produces and distributes oil products and therefore complements the Company's closed loop model as it relates to the sale of its oil products. The acquired company is included in the Safety-Kleen segment. In connection with this acquisition, a goodwill amount of $5.0 million was recognized.

Pro forma revenue and earnings amounts on a combined basis as if these acquisitions had been completed on January 1, 2017 are immaterial to the consolidated financial statements of the Company since that date.

(5) DISPOSITION OF BUSINESS

On June 30, 2017, the Company completed the sale of its Transformer Services business, as part of its continuous focus on improving or divesting certain non-core operations. The sale price was $45.5 million. The Transformer Services business was a non-core business previously included within the legacy Technical Services operating segment.

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The following table presents income attributable to the Transformer Services business included in the Company's consolidated results of operations for the three and six months ended June 30, 2017 (in thousands):

	Three Months Ended		Six Months Ended
	June 30, 2017		June 30, 2017
Income before provision for income taxes	$	1,873	$	2,771

(6) INVENTORIES AND SUPPLIES

Inventories and supplies consisted of the following (in thousands):

	June 30, 2018		December 31, 2017
Oil and oil products	$	68,125	$	58,142
Supplies and drums	100,118		94,242
Solvent and solutions	9,230		9,167
Modular camp accommodations	2,494		1,826
Other	13,577		12,635
Total inventories and supplies	$	193,544	$	176,012

As of June 30, 2018 and December 31, 2017, other inventories consisted primarily of parts washer components, cleaning fluids, absorbents and automotive fluids, such as windshield washer fluid and antifreeze. Supplies and drums consisted primarily of drums and containers as well as critical spare parts to support the Company's incinerator and re-refinery operations.

(7) PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment consisted of the following (in thousands):

	June 30, 2018		December 31, 2017
Land	$	123,984	$	121,658
Asset retirement costs (non-landfill)	14,780		14,593
Landfill assets	145,068		144,539
Buildings and improvements	429,880		414,384
Camp equipment	161,899		170,012
Vehicles	689,846		617,959
Equipment	1,675,920		1,644,102
Furniture and fixtures	5,623		5,708
Construction in progress	39,569		57,618
	3,286,569		3,190,573
Less - accumulated depreciation and amortization	1,677,187		1,603,208
Total property, plant and equipment, net	$	1,609,382	$	1,587,365

Interest in the amount of $0.1 million and $0.4 million was capitalized to property, plant and equipment during the three and six months ended June 30, 2018, respectively. Interest in the amount of $0.1 million and $0.2 million was capitalized to property, plant and equipment during the three and six months ended June 30, 2017, respectively. Depreciation expense, inclusive of landfill amortization, was $64.2 million and $129.8 million for the three and six months ended June 30, 2018, respectively. Depreciation expense, inclusive of landfill amortization, was $61.8 million and $125.2 million for the three and six months ended June 30, 2017, respectively.

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(8) GOODWILL AND OTHER INTANGIBLE ASSETS

The changes in goodwill by segment for the six months ended June 30, 2018 were as follows (in thousands):

	Environmental Services			Safety-Kleen			Totals
Balance at January 1, 2018	$	172,386		$	306,137		$	478,523
Increase from current period acquisition	21,626			—			21,626
Measurement period adjustments from prior period acquisitions	(78		)	—			(78		)
Foreign currency translation	(1,305		)	(1,515		)	(2,820		)
Balance at June 30, 2018	$	192,629		$	304,622		$	497,251

The Company assesses goodwill for impairment on an annual basis as of December 31, or at an interim date when events or changes in the business environment would more likely than not reduce the fair value of a reporting unit below its carrying value.

As discussed in Note 18, “Segment Reporting,” during the first quarter of fiscal year 2018 and as a result of operational and managerial changes in several of the Company’s businesses, the identification of operating segments in accordance with ASC 280, Segment Information, was changed. As a result of the Company's conclusions around the identification of operating segments, the Company also concluded that, for purposes of reviewing for potential goodwill impairment, it now has four reporting units, consisting of Environmental Sales and Service, Environmental Facilities, Kleen Performance Products and Safety-Kleen Environmental Services. The Company allocated goodwill to the newly identified reporting units using a relative fair value approach. In addition, the Company completed an assessment of any potential goodwill impairment for all reporting units immediately prior and subsequent to the reallocation and determined that no impairment existed.

As of June 30, 2018 and December 31, 2017, the Company's total finite-lived and indefinite-lived intangible assets consisted of the following (in thousands):

	June 30, 2018						December 31, 2017
	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
Permits	$	175,317	$	76,707	$	98,610	$	174,721	$	74,347	$	100,374
Customer and supplier relationships	399,012		170,866		228,146		399,224		158,972		240,252
Other intangible assets	37,431		31,107		6,324		36,766		31,592		5,174
Total amortizable permits and other intangible assets	611,760		278,680		333,080		610,711		264,911		345,800
Indefinite lived trademarks and trade names	122,840		—		122,840		123,328		—		123,328
Total permits and other intangible assets	$	734,600	$	278,680	$	455,920	$	734,039	$	264,911	$	469,128

Amortization expense of permits and other intangible assets was $8.6 million and $17.8 million in the three and six months ended June 30, 2018, respectively. Amortization expense of permits and other intangible assets was $9.7 million and $18.8 million in the three and six months ended June 30, 2017, respectively.

The expected amortization of the net carrying amount of finite-lived intangible assets at June 30, 2018 was as follows (in thousands):

Years Ending December 31,	Expected Amortization
2018 (six months)	$	16,927
2019	32,143
2020	29,850
2021	27,381
2022	27,222
Thereafter	199,557
	$	333,080

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(9) ACCRUED EXPENSES

Accrued expenses consisted of the following at June 30, 2018 and December 31, 2017 (in thousands):

	June 30, 2018		December 31, 2017
Insurance	$	68,701	$	57,889
Interest	12,693		12,660
Accrued compensation and benefits	56,073		55,861
Income, real estate, sales and other taxes	27,116		27,330
Other	35,552		34,242
	$	200,135	$	187,982

(10) CLOSURE AND POST-CLOSURE LIABILITIES

The changes to closure and post-closure liabilities (also referred to as “asset retirement obligations”) from January 1, 2018 through June 30, 2018 were as follows (in thousands):

	Landfill Retirement Liability			Non-Landfill Retirement Liability			Total
Balance at January 1, 2018	$	32,382		$	28,655		$	61,037
Liabilities assumed in acquisition	—			604			604
New asset retirement obligations	1,478			—			1,478
Accretion	1,284			1,245			2,529
Changes in estimates recorded to statement of operations	—			85			85
Changes in estimates recorded to balance sheet	430			—			430
Expenditures	(359		)	(88		)	(447		)
Currency translation and other	(127		)	(85		)	(212		)
Balance at June 30, 2018	$	35,088		$	30,416		$	65,504

All of the landfill facilities included in the above were active as of June 30, 2018. There were no significant charges (benefits) in 2018 resulting from changes in estimates for closure and post-closure liabilities.

New asset retirement obligations incurred during the first six months of 2018 were discounted at the credit-adjusted risk-free rate of 5.66%.

(11) REMEDIAL LIABILITIES

The changes to remedial liabilities for the six months ended June 30, 2018 were as follows (in thousands):

	Remedial Liabilities for Landfill Sites			Remedial Liabilities for Inactive Sites			Remedial Liabilities (Including Superfund) for Non-Landfill Operations			Total
Balance at January 1, 2018	$	1,800		$	65,342		$	57,326		$	124,468
Accretion	43			1,375			931			2,349
Changes in estimates recorded to statement of operations	—			83			(841		)	(758		)
Expenditures	(23		)	(1,939		)	(2,176		)	(4,138		)
Currency translation and other	—			882			(1,528		)	(646		)
Balance at June 30, 2018	$	1,820		$	65,743		$	53,712		$	121,275

In the six months ended June 30, 2018, there were no significant charges (benefits) resulting from changes in estimates for remedial liabilities.

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(12) FINANCING ARRANGEMENTS

The following table is a summary of the Company’s financing arrangements (in thousands):

	June 30, 2018			December 31, 2017
Senior secured Term Loan Agreement ("Term Loan Agreement")	$	4,000		$	4,000
Current portion of long-term obligations, at carrying value	$	4,000		$	4,000
Senior secured Term Loan Agreement due June 30, 2024	$	392,000		$	394,000
Senior unsecured notes, at 5.25%, due August 1, 2020 ("2020 Notes")	400,000			400,000
Senior unsecured notes, at 5.125%, due June 1, 2021 ("2021 Notes")	845,000			845,000
Long-term obligations, at par	$	1,637,000		$	1,639,000
Unamortized debt issuance costs and premium, net	(12,273		)	(13,463		)
Long-term obligations, at carrying value	$	1,624,727		$	1,625,537
Total current and long-term obligations, at carrying value	$	1,628,727		$	1,629,537

On April 17, 2018, the Company, and substantially all of the Company's domestic subsidiaries as guarantors, entered into the first amendment (“First Amendment”) of the Term Loan Agreement. The First Amendment reduced the applicable interest rate margin for the Company’s initial term loans outstanding (the "Term Loans") under the Term Loan Agreement by 25 basis points for both Eurocurrency borrowings and base rate borrowings. After giving effect to the repricing, the applicable interest rate margin for the Term Loans are 1.75% for Eurocurrency borrowings and 0.75% for base rate borrowings.

On July 19, 2018, the Company, and substantially all of the Company’s domestic subsidiaries as guarantors, entered into an Incremental Facility Amendment (the “Incremental Facility Amendment”) to the Company’s existing Term Loan Agreement. The Incremental Facility Amendment increases the principal amount of the initial term loans (the “Initial Term Loans”) outstanding under the Term Loan Agreement by $350.0 million and, as a result of such increase, an aggregate of $746.0 million of principal was outstanding at July 19, 2018. Initial Term Loans under the Term Loan Agreement will mature on June 30, 2024 and may be prepaid at any time without premium or penalty other than customary breakage costs with respect to Eurodollar based loans or if the Company engages in certain repricing transactions before January 19, 2019, in which event a 1.0% prepayment premium would be due. The Company’s obligations under the Term Loan Agreement are guaranteed by all of the Company’s domestic restricted subsidiaries and secured by liens on substantially all of the assets of the Company and the guarantors.

Concurrently with the closing on July 19, 2018 of the Incremental Facility Amendment, the Company purchased $322.0 million aggregate principal of 2020 Notes. Total amount paid in purchasing the 2020 Notes was $330.9 including $7.9 million of accrued interest.

On August 1, 2018, the Company redeemed the remaining $78.0 million outstanding 2020 Notes. In connection with the redemption of the $78.0 million of 2020 Notes, the Company borrowed $50.0 million under the Company's revolving credit facility.

At June 30, 2018 and December 31, 2017, the fair value of the Term Loans was $394.5 million and $400.5 million, respectively, based on quoted market prices or other available market data. At June 30, 2018 and December 31, 2017, the fair value of the Company's 2020 Notes was $400.9 million and $404.6 million, respectively, based on quoted market prices for the instrument. At June 30, 2018 and December 31, 2017, the fair value of the Company's 2021 Notes was $848.6 million and $855.7 million, respectively, based on quoted market prices for the instrument. The fair values of the Term Loans, 2020 Notes and 2021 Notes are considered Level 2 measures according to the fair value hierarchy.

The Company also maintains a $400.0 million revolving credit facility under which the Company had no outstanding loan balances as of June 30, 2018 and December 31, 2017. At June 30, 2018, approximately $244.3 million was available to borrow and outstanding letters of credit were $132.4 million. At December 31, 2017, $217.8 million was available to borrow and outstanding letters of credit were $134.1 million.    

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(13) EARNINGS PER SHARE

The following are computations of basic and diluted earnings per share (in thousands except for per share amounts):

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2018		2017		2018		2017
Numerator for basic and diluted earnings per share:
Net income	$	30,747	$	25,880	$	18,116	$	4,487
Denominator:
Basic shares outstanding	56,410		57,190		56,304		57,226
Dilutive effect of equity-based compensation awards	95		146		95		123
Dilutive shares outstanding	56,505		57,336		56,399		57,349
Basic income per share:	$	0.55	$	0.45	$	0.32	$	0.08
Diluted income per share:	$	0.54	$	0.45	$	0.32	$	0.08

For the three months ended June 30, 2018 and June 30, 2017, the dilutive effect of all then outstanding restricted stock and performance awards is included in the EPS calculation above except for 146,159 and 142,503 of performance stock awards for which the performance criteria were not attained at that time and 136,155 and 14,699, respectively, of restricted stock awards which were antidilutive at that time.

For the six months ended  June 30, 2018 and June 30, 2017, the dilutive effect of all then outstanding restricted stock and performance awards is included in the EPS calculation above except for 146,159 and 142,503 of performance stock awards for which the performance criteria were not attained at that time and 130,932 and 21,013, respectively, of restricted stock awards which were antidilutive at that time.

(14) ACCUMULATED OTHER COMPREHENSIVE LOSS

The changes in accumulated other comprehensive loss by component and related tax effects for the six months ended June 30, 2018 were as follows (in thousands):    

	Foreign Currency Translation			Unrealized Losses on Available-For-Sale Securities			Unfunded Pension Liability			Total
Balance at January 1, 2018	$	(170,575	)	$	(146	)	$	(1,686	)	$	(172,407	)
Other comprehensive loss before tax effects	(27,091		)	(118		)	—			(27,209		)
Tax effects	5,609			(88		)	—			5,521
Other comprehensive loss	$	(21,482	)	$	(206	)	$	—		$	(21,688	)
Balance at June 30, 2018	$	(192,057	)	$	(352	)	$	(1,686	)	$	(194,095	)

(15) STOCK-BASED COMPENSATION

Total stock-based compensation cost charged to selling, general and administrative expenses for the three and six months ended June 30, 2018 was $3.5 million and $6.6 million, respectively. Total stock-based compensation cost charged to selling, general and administrative expenses for the three and six months ended June 30, 2017 was $2.9 million and $5.2 million, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation was $0.7 million and $1.3 million for the three and six months ended June 30, 2018, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation was $0.8 million and $1.5 million for the three and six months ended June 30, 2017, respectively.

Restricted Stock Awards

The following information relates to restricted stock awards that have been granted to employees and directors under the Company's equity incentive plans (the "Plans"). The restricted stock awards are not transferable until vested and the restrictions generally lapse upon the achievement of continued employment over a three-to-five-year period or service as a director until the

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following annual meeting of shareholders. The fair value of each restricted stock grant is based on the closing price of the Company's common stock on the date of grant and is amortized to expense over its vesting period.

The following table summarizes information about restricted stock awards for the six months ended June 30, 2018:

Restricted Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2018	604,933		$	54.23
Granted	200,688		$	52.92
Vested	(152,283	)	$	54.65
Forfeited	(17,136	)	$	53.63
Balance at June 30, 2018	636,202		$	53.73

As of June 30, 2018, there was $27.1 million of total unrecognized compensation cost arising from restricted stock awards under the Company's Plans. This cost is expected to be recognized over a weighted average period of 2.7 years. The total fair value of restricted stock vested during the three and six months ended June 30, 2018 was $7.0 million and $8.3 million, respectively. The total fair value of restricted stock vested during the three and six months ended June 30, 2017 was $4.5 million and $6.0 million, respectively.

Performance Stock Awards

The following information relates to performance stock awards that have been granted to employees under the Company's Plans. Performance stock awards are subject to performance criteria established by the compensation committee of the Company's board of directors prior to or at the date of grant. The vesting of the performance stock awards is based on achieving such targets typically based on revenue, Adjusted EBITDA margin, Adjusted Free Cash Flow and Total Recordable Incident Rate. In addition, performance stock awards include continued service conditions. The fair value of each performance stock award is based on the closing price of the Company's common stock on the date of grant and is amortized to expense over the service period if achievement of performance measures is considered probable.

The following table summarizes information about performance stock awards for the six months ended June 30, 2018:

Performance Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2018	190,129		$	55.63
Vested	(8,696	)	$	54.26
Forfeited	(12,889	)	$	55.09
Balance at June 30, 2018	168,544		$	55.75

As of June 30, 2018, there was $1.3 million of total unrecognized compensation cost arising from unvested performance stock awards deemed probable of vesting under the Company's Plans. No performance awards vested during the three months ended June 30, 2018. The total fair value of performance awards vested during six months ended June 30, 2018 was $0.5 million. No performance awards vested during the three months ended June 30, 2017. The total fair value of performance awards vested during the six months ended June 30, 2017 was $1.4 million.

Common Stock Repurchases

On October 31, 2017, the Company's board of directors increased the size of the Company’s current share repurchase program from $300 million to $600 million. During the three and six months ended June 30, 2018, the Company repurchased and retired a total of 0.2 million shares and 0.5 million shares, respectively, of the Company's common stock for a total cost of $12.2 million and $26.5 million, respectively. During the three and six months ended June 30, 2017, the Company repurchased and retired a total of 0.1 million and 0.2 million, respectively, of the Company's common stock for a total cost of $5.5 million and $12.3 million, respectively. Through June 30, 2018, the Company has repurchased and retired a total of 5.3 million shares of the Company's common stock for a total cost of $275.3 million under this program. As of June 30, 2018, an additional $324.7 million remained available for repurchase of shares under the current authorized program.

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(16) COMMITMENTS AND CONTINGENCIES

Legal and Administrative Proceedings

The Company and its subsidiaries are subject to legal proceedings and claims arising in the ordinary course of business. Actions filed against the Company arise from commercial and employment-related claims including alleged class actions related to sales practices and wage and hour claims. The plaintiffs in these actions may be seeking damages or injunctive relief or both. These actions are in various jurisdictions and stages of proceedings, and some are covered in part by insurance. In addition, the Company’s waste management services operations are regulated by federal, state, provincial and local laws enacted to regulate discharge of materials into the environment, remediation of contaminated soil and groundwater or otherwise protect the environment. This ongoing regulation results in the Company frequently becoming a party to legal or administrative proceedings involving all levels of governmental authorities and other interested parties. The issues involved in such proceedings generally relate to alleged violations of existing permits and licenses or alleged responsibility under federal or state Superfund laws to remediate contamination at properties owned either by the Company or by other parties (“third party sites”) to which either the Company or the prior owners of certain of the Company’s facilities shipped wastes.

At June 30, 2018 and December 31, 2017, the Company had recorded reserves of $21.6 million and $19.3 million, respectively, in the Company's financial statements for actual or probable liabilities related to the legal and administrative proceedings in which the Company was then involved, the principal of which are described below. At June 30, 2018 and December 31, 2017, the Company also believed that it was reasonably possible that the amount of these potential liabilities could be as much as $1.7 million and $1.8 million more, respectively. The Company periodically adjusts the aggregate amount of these reserves when actual or probable liabilities are paid or otherwise discharged, new claims arise, or additional relevant information about existing or probable claims becomes available. As of June 30, 2018 and December 31, 2017, the $21.6 million and $19.3 million, respectively, of reserves consisted of (i) $17.0 million and $17.9 million, respectively, related to pending legal or administrative proceedings, including Superfund liabilities, which were included in remedial liabilities on the consolidated balance sheets, and (ii) $4.6 million and $1.4 million, respectively, primarily related to federal, state and provincial enforcement actions, which were included in accrued expenses on the consolidated balance sheets.

As of June 30, 2018, the principal legal and administrative proceedings in which the Company was involved, or which had been terminated during 2018, were as follows:

Ville Mercier.    In September 2002, the Company acquired the stock of a subsidiary (the "Mercier Subsidiary") which owns a hazardous waste incinerator in Ville Mercier, Quebec (the "Mercier Facility"). The property adjacent to the Mercier Facility, which is also owned by the Mercier Subsidiary, is now contaminated as a result of actions dating back to 1968, when the Government of Quebec issued to a company unrelated to the Mercier Subsidiary two permits to dump organic liquids into lagoons on the property. In 1999, Ville Mercier and three neighboring municipalities filed separate legal proceedings against the Mercier Subsidiary and the Government of Quebec. In 2012, the municipalities amended their existing statement of claim to seek $2.9 million (CAD) in general damages and $10.0 million (CAD) in punitive damages, plus interest and costs, as well as injunctive relief. Both the Government of Quebec and the Company have filed summary judgment motions against the municipalities. The parties are currently attempting to negotiate a resolution and hearings on the motions have been delayed. In September 2007, the Quebec Minister of Sustainable Development, Environment and Parks issued a Notice pursuant to Section 115.1 of the Environment Quality Act, superseding Notices issued in 1992, which are the subject of the pending litigation. The more recent Notice notifies the Mercier Subsidiary that, if the Mercier Subsidiary does not take certain remedial measures at the site, the Minister intends to undertake those measures at the site and claim direct and indirect costs related to such measures. The Company has accrued for costs expected to be incurred relative to the resolution of this matter and believes this matter will not have future material effect on its financial position or results of operations.

Safety-Kleen Legal Proceedings. On December 28, 2012, the Company acquired Safety-Kleen, Inc. ("Safety-Kleen") and thereby became subject to the legal proceedings in which Safety-Kleen was a party on that date. In addition to certain Superfund proceedings in which Safety-Kleen has been named as a potentially responsible party as described below under “Superfund Proceedings,” the principal such legal proceedings involving Safety-Kleen which were outstanding as of June 30, 2018 were as follows:

Product Liability Cases. Safety-Kleen has been named as a defendant in various lawsuits that are currently pending in various courts and jurisdictions throughout the United States, including approximately 60 proceedings (excluding cases which have been settled but not formally dismissed) as of June 30, 2018, wherein persons claim personal injury resulting from the use of Safety-Kleen's parts cleaning equipment or cleaning products. These proceedings typically involve allegations that the solvent used in Safety-Kleen's parts cleaning equipment contains contaminants and/or that Safety-Kleen's recycling process does not effectively remove the contaminants that become entrained in the solvent during their use. In addition, certain claimants assert that Safety-Kleen

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failed to warn adequately the product user of potential risks, including a historic failure to warn that solvent contains trace amounts of toxic or hazardous substances such as benzene.

Safety-Kleen maintains insurance that it believes will provide coverage for these product liability claims (over amounts accrued for self-insured retentions and deductibles in certain limited cases), except for punitive damages to the extent not insurable under state law or excluded from insurance coverage. Safety-Kleen also believes that these claims lack merit and has historically vigorously defended, and intends to continue to vigorously defend, itself and the safety of its products against all of these claims. Such matters are subject to many uncertainties and outcomes are not predictable with assurance. Consequently, Safety-Kleen is unable to ascertain the ultimate aggregate amount of monetary liability or financial impact with respect to these matters as of June 30, 2018. From January 1, 2018 to June 30, 2018, three product liability claims were settled or dismissed. Due to the nature of these claims and the related insurance, the Company did not incur any expense as Safety-Kleen's insurance provided coverage in full for all such claims. Safety-Kleen may be named in similar, additional lawsuits in the future, including claims for which insurance coverage may not be available.    

Superfund Proceedings

The Company has been notified that either the Company (which, since December 28, 2012, includes Safety-Kleen) or the prior owners of certain of the Company's facilities for which the Company may have indemnification obligations have been identified as potentially responsible parties ("PRPs") or potential PRPs in connection with 127 sites which are subject to or are proposed to become subject to proceedings under federal or state Superfund laws. Of the 127 sites, three (including the BR Facility described below) involve facilities that are now owned or leased by the Company and 124 involve third party sites to which either the Company or the prior owners of certain of the Company’s facilities shipped wastes. Of the 124 third party sites, 34 are now settled, 17 are currently requiring expenditures on remediation and 73 are not currently requiring expenditures on remediation.

In connection with each site, the Company has estimated the extent, if any, to which it may be subject, either directly or as a result of any indemnification obligations, for cleanup and remediation costs, related legal and consulting costs associated with PRP investigations, settlements, and related legal and administrative proceedings. The amount of such actual and potential liability is inherently difficult to estimate because of, among other relevant factors, uncertainties as to the legal liability (if any) of the Company or the prior owners of certain of the Company's facilities to contribute a portion of the cleanup costs, the assumptions that must be made in calculating the estimated cost and timing of remediation, the identification of other PRPs and their respective capability and obligation to contribute to remediation efforts, and the existence and legal standing of indemnification agreements (if any) with prior owners, which may either benefit the Company or subject the Company to potential indemnification obligations. The Company believes its potential liability could exceed $100,000 at 10 of the 124 third party sites.

BR Facility.    The Company acquired in 2002 a former hazardous waste incinerator and landfill in Baton Rouge (the "BR Facility"), for which operations had been previously discontinued by the prior owner. In September 2007, the Environmental Protection Agency (the "EPA") issued a special notice letter to the Company related to the Devil's Swamp Lake Site ("Devil's Swamp") in East Baton Rouge Parish, Louisiana. Devil's Swamp includes a lake located downstream of an outfall ditch where wastewater and storm water have been discharged, and Devil's Swamp is proposed to be included on the National Priorities List due to the presence of Contaminants of Concern ("COC") cited by the EPA. These COCs include substances of the kind found in wastewater and storm water discharged from the BR Facility in past operations. The EPA originally requested COC generators to submit a good faith offer to conduct a remedial investigation feasibility study directed towards the eventual remediation of the site. The Company is currently performing corrective actions at the BR Facility under an order issued by the Louisiana Department of Environmental Quality, and has begun conducting the remedial investigation and feasibility study under an order issued by the EPA. The Company cannot presently estimate the potential additional liability for the Devil's Swamp cleanup until a final remedy is selected by the EPA.

Third Party Sites.    Of the 124 third party sites at which the Company has been notified it is a PRP or potential PRP or may have indemnification obligations, Clean Harbors has an indemnification agreement at 11 of these sites with ChemWaste, a former subsidiary of Waste Management, Inc., and at six additional of these third party sites, Safety-Kleen has a similar indemnification agreement with McKesson Corporation. These agreements indemnify the Company (which now includes Safety-Kleen) with respect to any liability at the 17 sites for waste disposed prior to the Company's (or Safety-Kleen's) acquisition of the former subsidiaries of Waste Management and McKesson which had shipped wastes to those sites. Accordingly, Waste Management or McKesson are paying all costs of defending those subsidiaries in those 17 cases, including legal fees and settlement costs. However, there can be no guarantee that the Company's ultimate liabilities for those sites will not exceed the amount recorded or that indemnities applicable to any of these sites will be available to pay all or a portion of related costs. Except for the indemnification agreements which the Company holds from ChemWaste, McKesson and one other entity, the Company does not have an indemnity agreement with respect to any of the 124 third party sites discussed above.

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Federal, State and Provincial Enforcement Actions

From time to time, the Company pays fines or penalties in regulatory proceedings relating primarily to waste treatment, storage or disposal facilities. As of June 30, 2018 and December 31, 2017, there were six and five, respectively, proceedings for which the Company reasonably believes that the sanctions could equal or exceed $100,000. The Company believes that the fines or other penalties in these or any of the other regulatory proceedings will, individually or in the aggregate, not have a material effect on its financial condition, results of operations or cash flows.

(17) INCOME TAXES

The Company records a tax provision or benefit on an interim basis using an estimated annual effective tax rate. This rate is applied to the current period ordinary income or loss to determine the income tax provision or benefit allocated to the interim period. Losses from jurisdictions for which no benefit can be recognized and the income tax effects of unusual or infrequent items are excluded from the estimated annual effective tax rate and are recognized in the impacted interim period. The estimated annual effective tax rate may be significantly impacted by projected earnings mix by tax jurisdiction. Adjustments to the estimated annual effective income tax rate are recognized in the period when such estimates are revised.

The Company’s effective tax rate for the three and six months ended June 30, 2018 was 30.8% and 48.0% compared to 47.3% and 85.2% for the same periods in 2017. The variations in the effective income tax rates for the six months ended June 30, 2018 and the three and six months ended June 30, 2017 as compared to more customary relationships between pre-tax income and the provision for income taxes were primarily due to not recognizing income tax benefits from current operating losses related to certain Canadian entities during these periods.

On December 22, 2017, the “Tax Cuts and Jobs Act” (the “Tax Act”) was signed into law, making significant changes to the federal tax law. Changes include, but are not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial tax system, and a one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017. The Company recognized its best estimate of the income tax effects of the 2017 Tax Act in the financial statements included in its 2017 Annual Report on Form 10-K in accordance with Staff Accounting Bulletin No. 118, which provides SEC staff guidance for the application of ASC Topic 740, Income Taxes, in the reporting period in which the 2017 Tax Act was signed into law. During the three and six months ended June 30, 2018, the Company did not recognize any changes to the provisional amounts recorded in its 2017 Annual Report on Form 10-K in connection with the 2017 Tax Act. The Company is continuing to evaluate the impact of the Tax Act on its business and the consolidated financial statements and will make any adjustments to its provisional amounts in subsequent reporting periods upon obtaining, preparing or analyzing additional information affecting the income tax effects initially reported as a provisional amount. Any subsequent adjustment to these amounts will be recorded to tax expense in the quarter of 2018 when the analysis is completed.

As of June 30, 2018 and December 31, 2017, the Company had recorded $5.0 million and $5.1 million, respectively, of liabilities for unrecognized tax benefits and $1.0 million and $0.9 million of interest, respectively.

Due to expiring statute of limitation periods, the Company believes that total unrecognized tax benefits will decrease by $1.4 million within the next 12 months.

(18) SEGMENT REPORTING

Segment reporting is prepared on the same basis that the Company's chief executive officer, who is the Company's chief operating decision maker, manages the business, makes operating decisions and assesses performance. During the first quarter of fiscal year 2018, certain of the Company's businesses undertook a reorganization which included changes to the underlying business and management structures. The reorganization resulted in combining the Environmental Services businesses from an operational and management perspective and is expected to deepen customer relationships and allow for efficiencies across the Company's operations through the sharing of resources, namely labor and equipment which will reduce third party spend and promote the cross selling of such business offerings. In connection with this reorganization, the Company’s chief operating decision maker also requested changes in the information that he regularly reviews for purposes of allocating resources and assessing performance. These changes required a reconsideration of the Company’s operating segments in the first quarter of 2018 and resulted in a change in the Company’s assessment of its operating segments. Upon reconsideration of the identification of the Company’s operating segments, the Company concluded that there are now two operating segments for disclosure in accordance with ASC 280 Segment reporting; (i) the Environmental Services segment which consists of the Company’s historical Technical Services, Industrial Services, Field Services and Oil, Gas and Lodging businesses and (ii) the Safety-Kleen segment.

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Third-party revenue is revenue billed to outside customers by a particular segment. Direct revenue is revenue allocated to the segment providing the product or service. Intersegment revenues represent the sharing of third-party revenues among the segments based on products and services provided by each segment as if the products and services were sold directly to the third-party. The intersegment revenues are shown net. The negative intersegment revenues are due to more transfers out of customer revenues to other segments than transfers in of customer revenues from other segments. The operations not managed through the Company’s operating segments described above are recorded as “Corporate Items.” Corporate Items revenues consist of two different operations for which the revenues are insignificant. Corporate Items cost of revenues represents certain central services that are not allocated to the Company's operating segments for internal reporting purposes. Corporate Items selling, general and administrative expenses include typical corporate items such as legal, accounting and other items of a general corporate nature that are not allocated to the Company’s operating segments.  

The following table reconciles third party revenues to direct revenues for the three and six months ended June 30, 2018 and 2017 (in thousands):

	For the Three Months Ended June 30, 2018											For the Three Months Ended June 30, 2017
	Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Environmental Services	$	519,916	$	34,291		$	607		$	554,814		$	449,631	$	31,639		$	320		$	481,590
Safety-Kleen	328,715		(34,291		)	11			294,435			302,956		(31,639		)	(2		)	271,315
Corporate Items	509		—			(618		)	(109		)	201		—			(318		)	(117		)
Total	$	849,140	$	—		$	—		$	849,140		$	752,788	$	—		$	—		$	752,788

	For the Six Months Ended June 30, 2018											For the Six Months Ended June 30, 2017
	Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Environmental Services	$	959,604	$	66,256		$	1,401		$	1,027,261		$	845,538	$	63,708		$	1,240		$	910,486
Safety-Kleen	638,633		(66,256		)	22			572,399			595,857		(63,708		)	1			532,150
Corporate Items	681		—			(1,423		)	(742		)	334		—			(1,241		)	(907		)
Total	$	1,598,918	$	—		$	—		$	1,598,918		$	1,441,729	$	—		$	—		$	1,441,729

The primary financial measure by which the Company evaluates the performance of its segments is "Adjusted EBITDA" which consists of net income plus accretion of environmental liabilities, depreciation and amortization, interest expense, net, loss on early extinguishment of debt, provision for income taxes and excludes gain on sale of business and other income (expense), net. Transactions between the segments are accounted for at the Company’s best estimate based on similar transactions with outside customers.

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The following table presents Adjusted EBITDA information used by management by reported segment (in thousands):

	For the Three Months Ended						For the Six Months Ended
	June 30,						June 30,
	2018			2017			2018			2017
Adjusted EBITDA:
Environmental Services	$	109,199		$	94,832		$	170,616		$	155,022
Safety-Kleen	73,069			60,281			134,953			112,649
Corporate Items	(42,707		)	(34,422		)	(77,743		)	(66,845		)
Total	$	139,561		$	120,691		$	227,826		$	200,826
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	2,448			2,416			4,878			4,706
Depreciation and amortization	72,760			71,531			147,604			143,943
Income from operations	64,353			46,744			75,344			52,177
Other (income) expense, net	(846		)	833			(547		)	2,382
Loss on early extinguishment of debt	—			6,045			—			6,045
Gain on sale of business	—			(31,722		)	—			(31,722		)
Interest expense, net of interest income	20,769			22,492			41,039			45,068
Income before provision for income taxes	$	44,430		$	49,096		$	34,852		$	30,404

The following table presents certain assets by reportable segment and in the aggregate (in thousands):

	June 30, 2018
	Environmental Services		Safety-Kleen		Corporate Items		Totals
Property, plant and equipment, net	$	988,957	$	555,124	$	65,301	$	1,609,382
Goodwill	192,629		304,622		—		497,251
Permits and other intangibles, net	96,165		359,755		—		455,920
Total assets	$	1,681,627	$	1,436,014	$	597,820	$	3,715,461

	December 31, 2017
	Environmental Services		Safety-Kleen		Corporate Items		Totals
Property, plant and equipment, net	$	927,139	$	582,162	$	78,064	$	1,587,365
Goodwill	172,386		306,137		—		478,523
Permits and other intangibles, net	97,519		371,609		—		469,128
Total assets	$	1,541,241	$	1,471,291	$	694,038	$	3,706,570

The following table presents total assets by geographical area (in thousands):

	June 30, 2018		December 31, 2017
United States	$	3,041,509	$	2,985,394
Canada	673,836		721,176
Other foreign	116		—
Total	$	3,715,461	$	3,706,570

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(19) GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION

The 2020 Notes and the 2021 Notes (collectively, the "Senior Unsecured Notes") and the Company's obligations under its Term Loan Agreement are guaranteed by substantially all of the Company’s subsidiaries organized in the United States. Each guarantor is a 100% owned subsidiary of Clean Harbors, Inc. and its guarantee is both full and unconditional and joint and several. The guarantees are, however, subject to customary release provisions under which, in particular, the guarantee of any domestic restricted subsidiary will be released if the Company sells such subsidiary to an unrelated third party in accordance with the terms of the indentures which govern the Senior Unsecured Notes and of the Term Loan Agreement. The Senior Unsecured Notes and the Company's obligations under its Term Loan Agreement are not guaranteed by the Company’s subsidiaries organized outside the United States. The following supplemental condensed consolidating financial information for the parent company, the guarantor subsidiaries and the non-guarantor subsidiaries, respectively, is presented in conformity with the requirements of Rule 3-10 of SEC Regulation S-X (“Rule 3-10”).

Following is the condensed consolidating balance sheet at June 30, 2018 (in thousands):

	Clean Harbors, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Consolidating Adjustments			Total
Assets:
Cash and cash equivalents	$	51,960	$	92,833	$	52,275	$	—		$	197,068
Short-term marketable securities	—		—		36,862		—			36,862
Intercompany receivables	250,206		651,218		61,125		(962,549		)	—
Accounts receivable, net	—		497,775		92,805		—			590,580
Other current assets	—		260,489		60,225		(8,742		)	311,972
Property, plant and equipment, net	—		1,243,171		366,211		—			1,609,382
Investments in subsidiaries	3,135,271		599,091		—		(3,734,362		)	—
Intercompany debt receivable	—		15,224		21,000		(36,224		)	—
Goodwill	—		437,229		60,022		—			497,251
Permits and other intangibles, net	—		402,096		53,824		—			455,920
Other long-term assets	2,283		12,337		1,811		(5		)	16,426
Total assets	$	3,439,720	$	4,211,463	$	806,160	$	(4,741,882	)	$	3,715,461
Liabilities and Stockholders’ Equity:
Current liabilities	$	16,627	$	406,111	$	129,672	$	(8,742	)	$	543,668
Intercompany payables	637,318		309,423		15,808		(962,549		)	—
Closure, post-closure and remedial liabilities, net	—		146,922		16,850		—			163,772
Long-term obligations, net	1,624,727		—		—		—			1,624,727
Intercompany debt payable	—		21,000		15,224		(36,224		)	—
Other long-term liabilities	—		200,999		21,252		(5		)	222,246
Total liabilities	2,278,672		1,084,455		198,806		(1,007,520		)	2,554,413
Stockholders’ equity	1,161,048		3,127,008		607,354		(3,734,362		)	1,161,048
Total liabilities and stockholders’ equity	$	3,439,720	$	4,211,463	$	806,160	$	(4,741,882	)	$	3,715,461

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Following is the condensed consolidating balance sheet at December 31, 2017 (in thousands):

	Clean Harbors, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Consolidating Adjustments			Total
Assets:
Cash and cash equivalents	$	51,638	$	207,777	$	59,984	$	—		$	319,399
Short-term marketable securities	—		—		38,179		—			38,179
Intercompany receivables	238,339		590,100		52,909		(881,348		)	—
Accounts receivable, net	—		433,042		95,882		—			528,924
Other current assets	897		233,602		52,947		(19,892		)	267,554
Property, plant and equipment, net	—		1,174,975		412,390		—			1,587,365
Investments in subsidiaries	3,112,547		569,568		—		(3,682,115		)	—
Intercompany debt receivable	—		92,530		21,000		(113,530		)	—
Goodwill	—		415,641		62,882		—			478,523
Permits and other intangibles, net	—		408,655		60,473		—			469,128
Other long-term assets	2,084		12,064		3,350		—			17,498
Total assets	$	3,405,505	$	4,137,954	$	859,996	$	(4,696,885	)	$	3,706,570
Liabilities and Stockholders’ Equity:
Current liabilities	$	16,954	$	371,135	$	135,620	$	(19,892	)	$	503,817
Intercompany payables	574,812		289,531		17,005		(881,348		)	—
Closure, post-closure and remedial liabilities, net	—		148,872		16,851		—			165,723
Long-term obligations, net	1,625,537		—		—		—			1,625,537
Intercompany debt payable	—		21,000		92,530		(113,530		)	—
Other long-term liabilities	—		201,086		22,205		—			223,291
Total liabilities	2,217,303		1,031,624		284,211		(1,014,770		)	2,518,368
Stockholders’ equity	1,188,202		3,106,330		575,785		(3,682,115		)	1,188,202
Total liabilities and stockholders’ equity	$	3,405,505	$	4,137,954	$	859,996	$	(4,696,885	)	$	3,706,570

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Following is the consolidating statement of operations for the three months ended June 30, 2018 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	544,521		$	165,435		$	(13,177	)	$	696,779
Product revenues	—			137,891			17,363			(2,893		)	152,361
Total revenues	—			682,412			182,798			(16,070		)	849,140
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			361,644			124,956			(13,177		)	473,423
Product cost of revenues	—			102,442			10,612			(2,893		)	110,161
Total cost of revenues	—			464,086			135,568			(16,070		)	583,584
Selling, general and administrative expenses	133			105,022			20,840			—			125,995
Accretion of environmental liabilities	—			2,194			254			—			2,448
Depreciation and amortization	—			52,864			19,896			—			72,760
(Loss) income from operations	(133		)	58,246			6,240			—			64,353
Other income, net	—			269			577			—			846
Interest (expense) income, net	(21,216		)	238			209			—			(20,769		)
Equity in earnings of subsidiaries, net of taxes	46,118			2,230			—			(48,348		)	—
Intercompany interest income (expense)	—			1,084			(1,084		)	—			—
Income before (benefit) provision for income taxes	24,769			62,067			5,942			(48,348		)	44,430
(Benefit) provision for income taxes	(5,978		)	18,228			1,433			—			13,683
Net income	30,747			43,839			4,509			(48,348		)	30,747
Other comprehensive loss	(4,942		)	(4,942		)	(10,435		)	15,377			(4,942		)
Comprehensive income (loss)	$	25,805		$	38,897		$	(5,926	)	$	(32,971	)	$	25,805

26

Following is the consolidating statement of operations for the three months ended June 30, 2017 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	474,801		$	147,924		$	(11,785	)	$	610,940
Product revenues	—			125,859			18,730			(2,741		)	141,848
Total revenues	—			600,660			166,654			(14,526		)	752,788
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			306,960			117,181			(11,785		)	412,356
Product cost of revenues	—			98,645			11,543			(2,741		)	107,447
Total cost of revenues	—			405,605			128,724			(14,526		)	519,803
Selling, general and administrative expenses	27			92,504			19,763			—			112,294
Accretion of environmental liabilities	—			2,181			235			—			2,416
Depreciation and amortization	—			51,937			19,594			—			71,531
(Loss) income from operations	(27		)	48,433			(1,662		)	—			46,744
Other expense, net	(76		)	(406		)	(351		)	—			(833		)
Loss on early extinguishment of debt	(6,045		)	—			—			—			(6,045		)
Gain on sale of business	—			31,722			—			—			31,722
Interest (expense) income, net	(22,614		)	240			(118		)	—			(22,492		)
Equity in earnings of subsidiaries, net of taxes	43,167			(5,332		)	—			(37,835		)	—
Intercompany interest income (expense)	—			1,268			(1,268		)	—			—
Income (loss) before (benefit) provision for income taxes	14,405			75,925			(3,399		)	(37,835		)	49,096
(Benefit) provision for income taxes	(11,475		)	31,981			2,710			—			23,216
Net income (loss)	25,880			43,944			(6,109		)	(37,835		)	25,880
Other comprehensive income	15,098			15,098			12,837			(27,935		)	15,098
Comprehensive income	$	40,978		$	59,042		$	6,728		$	(65,770	)	$	40,978

27

Following is the consolidating statement of operations for the six months ended June 30, 2018 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	1,026,004		$	317,836		$	(27,342	)	$	1,316,498
Product revenues	—			259,473			28,813			(5,866		)	282,420
Total revenues	—			1,285,477			346,649			(33,208		)	1,598,918
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			689,824			258,590			(27,342		)	921,072
Product cost of revenues	—			197,480			17,323			(5,866		)	208,937
Total cost of revenues	—			887,304			275,913			(33,208		)	1,130,009
Selling, general and administrative expenses	168			198,865			42,050			—			241,083
Accretion of environmental liabilities	—			4,370			508			—			4,878
Depreciation and amortization	—			106,568			41,036			—			147,604
(Loss) income from operations	(168		)	88,370			(12,858		)	—			75,344
Other income, net	—			184			363			—			547
Interest (expense) income, net	(42,215		)	743			433			—			(41,039		)
Equity in earnings of subsidiaries, net of taxes	48,632			(17,832		)	—			(30,800		)	—
Intercompany interest income (expense)	—			2,445			(2,445		)	—			—
Income (loss) before (benefit) provision for income taxes	6,249			73,910			(14,507		)	(30,800		)	34,852
(Benefit) provision for income taxes	(11,867		)	27,329			1,274			—			16,736
Net income (loss)	18,116			46,581			(15,781		)	(30,800		)	18,116
Other comprehensive loss	(21,688		)	(21,688		)	(24,442		)	46,130			(21,688		)
Comprehensive (loss) income	$	(3,572	)	$	24,893		$	(40,223	)	$	15,330		$	(3,572	)

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Following is the consolidating statement of operations for the six months ended June 30, 2017 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	918,106		$	278,995		$	(25,947	)	$	1,171,154
Product revenues	—			242,509			34,061			(5,995		)	270,575
Total revenues	—			1,160,615			313,056			(31,942		)	1,441,729
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			601,105			228,285			(25,947		)	803,443
Product cost of revenues	—			195,150			23,790			(5,995		)	212,945
Total cost of revenues	—			796,255			252,075			(31,942		)	1,016,388
Selling, general and administrative expenses	51			184,675			39,789			—			224,515
Accretion of environmental liabilities	—			4,236			470			—			4,706
Depreciation and amortization	—			103,837			40,106			—			143,943
(Loss) income from operations	(51		)	71,612			(19,384		)	—			52,177
Other expense, net	(222		)	(1,795		)	(365		)	—			(2,382		)
Loss on early extinguishment of debt	(6,045		)	—			—			—			(6,045		)
Gain on sale of business	—			31,722			—			—			31,722
Interest (expense) income, net	(45,273		)	359			(154		)	—			(45,068		)
Equity in earnings of subsidiaries, net of taxes	35,530			(27,156		)	—			(8,374		)	—
Intercompany interest income (expense)	—			2,565			(2,565		)	—			—
(Loss) income before (benefit) provision for income taxes	(16,061		)	77,307			(22,468		)	(8,374		)	30,404
(Benefit) provision for income taxes	(20,548		)	41,618			4,847			—			25,917
Net income (loss)	4,487			35,689			(27,315		)	(8,374		)	4,487
Other comprehensive income	21,149			21,149			17,869			(39,018		)	21,149
Comprehensive income (loss)	$	25,636		$	56,838		$	(9,446	)	$	(47,392	)	$	25,636

29

Following is the condensed consolidating statement of cash flows for the six months ended June 30, 2018 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Net cash from operating activities	$	790		$	121,021		$	7,859		$	—		$	129,670
Cash flows used in investing activities:
Additions to property, plant and equipment	—			(77,773		)	(16,366		)	—			(94,139		)
Proceeds from sale and disposal of fixed assets	—			1,035			1,606			—			2,641
Acquisitions, net of cash acquired	—			(123,750		)	—			—			(123,750		)
Additions to intangible assets, including costs to obtain or renew permits	—			(1,991		)	(115		)	—			(2,106		)
Proceeds from sale of available-for-sale securities	—			—			11,214			—			11,214
Purchases of available-for-sale securities	—			—			(10,001		)	—			(10,001		)
Intercompany	—			(30,657		)	—			30,657			—
Net cash used in investing activities	—			(233,136		)	(13,662		)	30,657			(216,141		)
Cash flows (used in) from financing activities:
Change in uncashed checks	—			(2,829		)	26			—			(2,803		)
Tax payments related to withholdings on vested restricted stock	(2,175		)	—			—			—			(2,175		)
Repurchases of common stock	(26,482		)	—			—			—			(26,482		)
Deferred financing costs paid	(468		)	—			—			—			(468		)
Principal payment on debt	(2,000		)	—			—			—			(2,000		)
Intercompany	30,657			—			—			(30,657		)	—
Net cash (used) from in financing activities	(468		)	(2,829		)	26			(30,657		)	(33,928		)
Effect of exchange rate change on cash	—			—			(1,932		)	—			(1,932		)
Increase (decrease) in cash and cash equivalents	322			(114,944		)	(7,709		)	—			(122,331		)
Cash and cash equivalents, beginning of period	51,638			207,777			59,984			—			319,399
Cash and cash equivalents, end of period	$	51,960		$	92,833		$	52,275		$	—		$	197,068

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Following is the condensed consolidating statement of cash flows for the six months ended June 30, 2017 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Net cash (used in) from operating activities	$	(93,808	)	$	206,496		$	4,243		$	—		$	116,931
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	—			(75,152		)	(13,590		)	—			(88,742		)
Proceeds from sale and disposal of fixed assets	—			984			1,137			—			2,121
Acquisitions, net of cash acquired	—			(9,277		)	—			—			(9,277		)
Proceeds from sale of businesses, net of transactional costs	—			46,210			181			—			46,391
Additions to intangible assets, including costs to obtain or renew permits	—			(888		)	(351		)	—			(1,239		)
Proceeds from sale of available-for-sale securities	376			—			—			—			376
Intercompany	—			(14,343		)	—			14,343			—
Net cash from (used in) investing activities	376			(52,466		)	(12,623		)	14,343			(50,370		)
Cash flows from (used in) financing activities:
Change in uncashed checks	—			(5,977		)	(2,384		)	—			(8,361		)
Proceeds from exercise of stock options	46			—			—			—			46
Tax payments related to withholdings on vested restricted stock	(2,132		)	—			—			—			(2,132		)
Repurchases of common stock	(12,257		)	—			—			—			(12,257		)
Deferred financing costs paid	(4,727		)	—			—			—			(4,727		)
Premium paid on early extinguishment of debt	(4,665		)	—			—			—			(4,665		)
Principal payment on debt	(296,202		)	—			—			—			(296,202		)
Issuance of senior secured notes, net of discount	399,000			—			—			—			399,000
Intercompany	14,343			—			—			(14,343		)	—
Net cash from (used) in financing activities	93,406			(5,977		)	(2,384		)	(14,343		)	70,702
Effect of exchange rate change on cash	—			—			2,106			—			2,106
(Decrease) increase in cash and cash equivalents	(26		)	148,053			(8,658		)	—			139,369
Cash and cash equivalents, beginning of period	51,417			155,943			99,637			—			306,997
Cash and cash equivalents, end of period	$	51,391		$	303,996		$	90,979		$	—		$	446,366

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ITEM 2.MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

Forward-Looking Statements

In addition to historical information, this Quarterly Report on Form 10-Q contains forward-looking statements, which are generally identifiable by use of the words “believes,” “expects,” “intends,” “anticipates,” “plans to,” “estimates,” “projects,” or similar expressions. These forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those reflected in these forward-looking statements. Factors that might cause such a difference include, but are not limited to, those discussed under Item 1A, “Risk Factors,” in our Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 28, 2018, under Item 1A, “Risk Factors,” included in Part II—Other Information in this report, and in other documents we file from time to time with the SEC.  Readers are cautioned not to place undue reliance on these forward-looking statements, which reflect management’s opinions only as of the date hereof. We undertake no obligation to revise or publicly release the results of any revision to these forward-looking statements.

Overview

We are North America’s leading provider of environmental, energy and industrial services. We believe we operate, in the aggregate, the largest number of hazardous waste incinerators, landfills and treatment, storage and disposal facilities ("TSDFs") in North America. We serve a diverse customer base, including Fortune 500 companies, across the chemical, energy, manufacturing and additional markets, as well as numerous government agencies. These customers rely on us to deliver a broad range of services including but not limited to end-to-end hazardous waste management, emergency response, industrial cleaning and maintenance, and recycling services. We are also the largest re-refiner and recycler of used oil in the world and the largest provider of parts cleaning and related environmental services to commercial, industrial and automotive customers in North America.

During the first quarter of fiscal year 2018, certain of our businesses undertook a reorganization which included changes to the underlying business and management structures. The reorganization resulted in combining the Environmental Services businesses from an operational and management perspective and is expected to deepen customer relationships and allow for efficiencies across our operations through the sharing of resources, namely labor and equipment which will reduce third party spend and promote the cross selling of such business offerings. In connection with this reorganization, our chief operating decision maker also requested changes in the information that he regularly reviews for purposes of allocating resources and assessing performance. These changes required a reconsideration of our operating segments in the first quarter of 2018 and resulted in a change in our assessment of our operating segments. We concluded that there are now two operating segments for disclosure in accordance with ASC 280 Segment reporting; (i) the Environmental Services segment which consists of our historical Technical Services, Industrial Services, Field Services and Oil, Gas and Lodging businesses, and (ii) the Safety-Kleen segment.

Performance of our segments is evaluated on several factors of which the primary financial measure is Adjusted EBITDA as described more fully below. The following is a discussion of how management evaluates its segments in regards to other factors including key performance indicators that management uses to assess the segments’ results, as well as certain macroeconomic trends and influences that impact each reportable segment:

• Environmental Services - Environmental Services segment results are predicated upon the demand by our customers for waste services directly attributable to waste volumes generated by them and project work for which waste handling and/or disposal is required. In managing the business and evaluating performance, management tracks the volumes of waste handled and disposed of through our owned incinerators and landfills as well as the utilization of such incinerators. Levels of activity and ultimate performance associated with this segment can be impacted by seasonality and weather conditions, market conditions and overall U.S. GDP and U.S. industrial production, efficiency of our operations, competition and market pricing of our services and the management of our related operating costs. Environmental Services results are also impacted by the demand for planned and unplanned industrial related cleaning and maintenance services at customer sites and the requirement for environmental cleanup services on a scheduled or emergency basis, including response to national events such as major oil spills, natural disasters or other events where immediate and specialized services are required.

• Safety-Kleen - Safety-Kleen segment results are significantly impacted by the overall market pricing and product mix associated with base and blended oil products and, more specifically, the market prices of Group II base oils, which historically have correlated with overall crude oil prices. Costs incurred in connection with the collection of used oils, which are raw materials associated with the segment’s products, can also be volatile. Starting in 2015, we began charging for collection of used oils, which has allowed us to more effectively manage the profit spreads inherent in the

32

business. The implementation of our OilPlus^TM closed loop initiative resulting in the sale of our renewable oil products directly to our end customers will also impact future operating results. In addition, this segment's results are impacted by the number of parts washers serviced by the business and the ability to attract small quantity waste producers as customers and integrate them into the Clean Harbors waste network.

Highlights

Total revenues for the three and six months ended June 30, 2018 were $849.1 million and $1,598.9 million compared with $752.8 million and $1,441.7 million for the three and six months ended June 30, 2017. In the three and six months ended June 30, 2018, our Environmental Services segment increased direct revenues 15.2% and 12.8%, respectively, from the comparable periods in 2017 primarily due to greater waste volumes disposed of in our network along with higher pricing, revenues resulting from the acquisition of the Veolia Business in the first quarter of 2018 and incremental revenues from acquisitions made in 2017 subsequent to the second quarter. In the three and six months ended June 30, 2018, our Safety-Kleen segment increased direct revenues 8.5% and 7.6%, respectively, from the comparable periods in 2017, as a result of improved pricing conditions related to our renewable oil products, continued growth related to our Safety-Kleen Environmental Services business and our OilPlus^TM closed loop initiative. The strengthening of the Canadian dollar also positively impacted our consolidated revenues by $6.3 million and $12.5 million, respectively, in the three and six months ended June 30, 2018.

We reported income from operations for the three and six months ended June 30, 2018 of $64.4 million and $75.3 million, respectively, compared with $46.7 million and $52.2 million in the three and six months ended June 30, 2017. We reported net income for the three and six months ended June 30, 2018 of $30.7 million and $18.1 million, respectively, compared with net income of $25.9 million and $4.5 million in the three and six months ended June 30, 2017. The three and six months ended June 30, 2017 included a $31.7 million pre-tax gain on the sale of a non-core line of business and a $6.0 million pre-tax loss on early extinguishment of debt.

Adjusted EBITDA, which is the primary financial measure by which our segments are evaluated, increased15.6% to $139.6 million in the three months ended June 30, 2018 from $120.7 million in the three months ended June 30, 2017 and increased13.4% to $227.8 million in the six months ended June 30, 2018 from $200.8 million in the six months ended June 30, 2017. Additional information, including a reconciliation of Adjusted EBITDA to net income, appears below under the heading "Adjusted EBITDA."

Net cash from operating activities for the six months ended June 30, 2018 was $129.7 million, an increase of $12.7 million from the comparable period in 2017. Adjusted free cash flow, which management uses to measure our financial strength and ability to generate cash, was $38.2 million in the six months ended June 30, 2018, which represents a $7.9 million increase over the comparable period of 2017. The increase in cash flows as compared to the comparable period of 2017 was most directly attributable to greater levels of operating income and lower interest payments offset by higher working capital levels. Additional information, including a reconciliation of adjusted free cash flow to net cash from operating activities, appears below under the heading "Adjusted Free Cash Flow."

33

Segment Performance

The primary financial measure by which we evaluate the performance of our segments is Adjusted EBITDA. The following table sets forth certain financial information associated with our results of operations for the three and six months ended June 30, 2018 and 2017 (in thousands).

	Summary of Operations (in thousands)
	For the Three Months Ended										For the Six Months Ended
	June 30, 2018			June 30, 2017			$ Change			% Change	June 30, 2018			June 30, 2017			$ Change			% Change
Direct Revenues(1):
Environmental Services	$	554,814		$	481,590		$	73,224		15.2%	$	1,027,261		$	910,486		$	116,775		12.8%
Safety-Kleen	294,435			271,315			23,120			8.5	572,399			532,150			40,249			7.6
Corporate Items	(109		)	(117		)	8			N/M	(742		)	(907		)	165			N/M
Total	849,140			752,788			96,352			12.8	1,598,918			1,441,729			157,189			10.9
Cost of Revenues(2):
Environmental Services	401,840			347,042			54,798			15.8	772,400			674,903			97,497			14.4
Safety-Kleen	181,494			172,684			8,810			5.1	359,231			344,432			14,799			4.3
Corporate Items	250			77			173			N/M	(1,622		)	(2,947		)	1,325			N/M
Total	583,584			519,803			63,781			12.3	1,130,009			1,016,388			113,621			11.2
Selling, General & Administrative Expenses:
Environmental Services	43,775			39,716			4,059			10.2	84,245			80,561			3,684			4.6
Safety-Kleen	39,872			38,350			1,522			4.0	78,215			75,069			3,146			4.2
Corporate Items	42,348			34,228			8,120			23.7	78,623			68,885			9,738			14.1
Total	125,995			112,294			13,701			12.2	241,083			224,515			16,568			7.4
Adjusted EBITDA:
Environmental Services	109,199			94,832			14,367			15.1	170,616			155,022			15,594			10.1
Safety-Kleen	73,069			60,281			12,788			21.2	134,953			112,649			22,304			19.8
Corporate Items	(42,707		)	(34,422		)	(8,285		)	(24.1)	(77,743		)	(66,845		)	(10,898		)	(16.3)
Total	$	139,561		$	120,691		$	18,870		15.6%	$	227,826		$	200,826		$	27,000		13.4%

_____________________

N/M = not meaningful

1. Direct revenue is revenue allocated to the segment performing the provided service.

2. Cost of revenue is shown exclusive of items presented separately on the statements of operations which consist of (i) accretion of environmental liabilities and (ii) depreciation and amortization.

34

Direct Revenues

There are many factors which have impacted and continue to impact our revenues. These factors include, but are not limited to: overall industrial activity and growth in North America, existence of large scale environmental waste and remediation projects, general conditions of the energy related industries, competitive industry pricing, the effects of fuel prices on our fuel recovery fees, acquisitions and divestitures, the level of emergency response projects and foreign currency translation. In addition, customer efforts to minimalize hazardous waste and changes in regulation can also impact our revenues.

Environmental Services

	For the Three Months Ended								For the Six Months Ended
	June 30,				2018 over 2017				June 30,				2018 over 2017
	2018		2017		$ Change		% Change		2018		2017		$ Change		% Change
Direct revenues	$	554,814	$	481,590	$	73,224	15.2	%	$	1,027,261	$	910,486	$	116,775	12.8	%

Environmental Services direct revenues for the three months ended June 30, 2018increased$73.2 million from the comparable period in 2017. Included in the three months ended June 30, 2017 was $10.7 million of direct revenues from our Transformer Services business, which we sold on June 30, 2017. Included in the three months ended June 30, 2018 was$46.3million of direct revenues from the Veolia Business, which we acquired on February 23, 2018, and $9.4 million from 2017 acquisitions which had not been consummated by June 30, 2017. Excluding these direct revenues related to recent acquisition and divestiture activities, Environmental Services direct revenue increased $28.2 million primarily due to increases in our industrial and speciality services line of business resulting from a strong turnaround season and a steady stream of smaller project across our Environmental Services business as well as higher disposal pricing and waste volumes processed in our incinerators. The utilization rate at our incinerators on a practical capacity of 561,721 tons was 89.8% for the three months ended June 30, 2018, compared with 86.9% in the comparable period of 2017. Greater levels of activity at our sales and service branches also accounted for increases to direct revenue of $16.5 million from the comparable period in 2017. Inclusive in the change within this segment was also the positive impact of foreign currency translation on our Canadian operations of $4.8 million for the three months ended June 30, 2018 from the comparable period in 2017.

Environmental Services direct revenues for the six months ended June 30, 2018increased$116.8 million from the comparable period in 2017. Included in the six months ended June 30, 2017 was $20.6 million of direct revenues from our Transformer Services business, which we sold on June 30, 2017. Included in the six months ended June 30, 2018 was$63.9million of direct revenues from the Veolia Business, which we acquired on February 23, 2018, and $18.1 million from our 2017 acquisitions. Excluding those direct revenues, Environmental Services direct revenue increased $55.4 million primarily due to higher levels of revenues associated with waste projects and higher waste volumes disposed of in our incinerators and landfills. The utilization rate at our incinerators on a practical capacity of 561,721 tons was 88.5% for the six months ended June 30, 2018, compared with 83.1% in the comparable period of 2017. The increase in utilization was impacted by higher volumes of waste processed through our incinerator network. Greater levels of activity at our sales and service branches also accounted for increases to direct revenue of $31.6 million from the comparable period in 2017. Inclusive in the change within this segment was also the positive impact of foreign currency translation on our Canadian operations of $9.3 million for the six months ended June 30, 2018 from the comparable period in 2017.

Safety-Kleen

	For the Three Months Ended								For the Six Months Ended
	June 30,				2018 over 2017				June 30,				2018 over 2017
	2018		2017		$ Change		% Change		2018		2017		$ Change		% Change
Direct revenues	$	294,435	$	271,315	$	23,120	8.5	%	$	572,399	$	532,150	$	40,249	7.6	%

Safety-Kleen direct revenues for the three months ended June 30, 2018increased$23.1 million from the comparable period in 2017 primarily due to more favorable pricing on oil products and growth in the business’ core service offerings. Increased base and blended oil pricing, volumes and direct sales of blended oil accounted for $18.5 million of incremental direct revenue from the comparable period in 2017. Revenues generated through direct sales of packaging and blending services and other core service offerings such as handling of containerized waste, vac services and sales of allied products accounted for $11.7 million of incremental revenues which more than offset a decrease in used oil collection revenues of $8.5 million. Inclusive in the change within this segment was also the positive impact of foreign currency translation on our Canadian operations of $1.4 million for the three months ended June 30, 2018 from the comparable period in 2017.

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Safety-Kleen direct revenues for the six months ended June 30, 2018increased$40.2 million from the comparable period in 2017 primarily due to more favorable pricing on oil products, increase in base oil volume and growth in the business’ core service offerings. Increased base and blended oil pricing and direct sales of blended oil accounted for $37.2 million of incremental direct revenue from the comparable period in 2017. Revenues generated through direct sales of packaging and blending services and other core service offerings such as handling of containerized waste, vac services and sales of allied products accounted for $18.5 million of incremental revenues which more than offset a decrease in used oil collection revenues of $16.6 million. Inclusive in the change within this segment was also the positive impact of foreign currency translation on our Canadian operations of $3.0 million for the six months ended June 30, 2018 from the comparable period in 2017.

Cost of Revenues

We believe that our ability to manage operating costs is important to our ability to remain price competitive. We continue to upgrade the quality and efficiency of our services through the development of new technology and continued modifications at our facilities, invest in new business opportunities and aggressively implement strategic sourcing and logistics solutions as well as other cost reduction initiatives in an effort to optimize our operating margins.

Environmental Services

	For the Three Months Ended										For the Six Months Ended
	June 30,						2018 over 2017				June 30,						2018 over 2017
	2018			2017			$ Change		% Change		2018			2017			$ Change		% Change
Cost of revenues	$	401,840		$	347,042		$	54,798	15.8	%	$	772,400		$	674,903		$	97,497	14.4%
As a % of Direct Revenue	72.4		%	72.1		%			0.3	%	75.2		%	74.1		%			1.1	%

Environmental Services cost of revenues for the three months ended June 30, 2018increased$54.8 million from the comparable period in 2017 primarily due to increases in labor related costs of $35.8 million along with equipment and supply costs of $11.4 million and transportation, disposal and fuel costs of $7.5 million. The incremental operating costs were driven by higher volumes of waste handled in our facilities and incremental costs associated with the acquisition of the Veolia Business.

Environmental Services cost of revenues for the six months ended June 30, 2018increased$97.5 million from the comparable period in 2017 primarily due to increases in labor related costs of $59.6 million along with equipment and supply costs of $28.1 million and transportation, disposal and fuel costs of $11.3 million. The incremental operating costs were driven by higher volumes of waste handled in our facilities, increased cost of certain commodity supplies such as fuel and solvents, as well as incremental costs related to repairs which needed to be made at our incinerators and our solvent recycling facility. These repair costs are the primary factor in the increase in cost of revenues as a percentage of direct revenue for the period.

Safety-Kleen

	For the Three Months Ended										For the Six Months Ended
	June 30,						2018 over 2017				June 30,						2018 over 2017
	2018			2017			$ Change		% Change		2018			2017			$ Change		% Change
Cost of revenues	$	181,494		$	172,684		$	8,810	5.1	%	$	359,231		$	344,432		$	14,799	4.3	%
As a % of Direct Revenue	61.6		%	63.6		%			(2.0	)%	62.8		%	64.7		%			(1.9	)%

Safety-Kleen cost of revenues for the three months ended June 30, 2018increased$8.8 million from the comparable period in 2017 primarily due to increased costs of oil additives and other raw materials of $4.0 million and increased transportation, disposal and fuel costs of $2.5 million. These increases were the result of overall growth of the business and increases seen in commodities pricing. Despite these increases in costs gross margin has expanded as we continue to effectively manage the spread in our re-refinery business and implement new pricing strategies.

Safety-Kleen cost of revenues for the six months ended June 30, 2018increased$14.8 million from the comparable period in 2017 primarily due to increased costs of oil additives and other raw materials of $5.8 million, increased transportation, disposal and fuel costs of $5.7 million and labor related costs of $3.7 million. These increases are in line with the overall growth of the business. Costs as a percentage of direct revenues decreased over the comparable periods of 2017 as we have been able to gain greater leverage from our cost structure.

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Selling, General and Administrative ("SG&A") Expenses

We strive to manage our selling, general and administrative expenses commensurate with the overall performance of our segments and corresponding revenue levels. We believe that our ability to properly align these costs with business performance is reflective of our strong management of the businesses and further promotes our ability to remain competitive in the marketplace.

Environmental Services

	For the Three Months Ended										For the Six Months Ended
	June 30,						2018 over 2017				June 30,						2018 over 2017
	2018			2017			$ Change		% Change		2018			2017			$ Change		% Change
SG&A	$	43,775		$	39,716		$	4,059	10.2	%	$	84,245		$	80,561		$	3,684	4.6	%
As a % of Direct Revenue	7.9		%	8.2		%			(0.3	)%	8.2		%	8.8		%			(0.6	)%

Environmental Services selling, general and administrative expenses for the three months ended June 30, 2018increased$4.1 million from the comparable period in 2017 due to increases in salary and benefit related costs of $2.4 million variable compensation of $1.2 million and increases across various other expense categories of $0.5 million. As a percentage of direct revenue, SG&A costs decreased as the additional revenues outpace incremental SG&A costs.

Environmental Services selling, general and administrative expenses for the six months ended June 30, 2018increased$3.7 million from the comparable period in 2017 due primarily to increases in salary and benefit related costs of $4.4 million offset by a decrease across various expense categories of $0.7 million. As a percentage of direct revenue Environmental Services margins improved for the six months ended June 30, 2018 as compared to the same period in prior year, thereby leveraging increased revenues.

Safety-Kleen

	For the Three Months Ended										For the Six Months Ended
	June 30,						2018 over 2017				June 30,						2018 over 2017
	2018			2017			$ Change		% Change		2018			2017			$ Change		% Change
SG&A	$	39,872		$	38,350		$	1,522	4.0	%	$	78,215		$	75,069		$	3,146	4.2	%
As a % of Direct Revenue	13.5		%	14.1		%			(0.6	)%	13.7		%	14.1		%			(0.4	)%

Safety-Kleen selling, general and administrative expenses for the three and six months ended June 30, 2018increased$1.5 million and $3.1 million, respectively, from the comparable periods in 2017 primarily due to an increase in variable compensation consistent with the increase in revenues of the business. As a percentage of direct revenue Safety-Kleen costs remained consistent for the three and six months ended June 30, 2018 with the comparable periods in 2017.

Corporate Items

	For the Three Months Ended								For the Six Months Ended
	June 30,				2018 over 2017				June 30,				2018 over 2017
	2018		2017		$ Change		% Change		2018		2017		$ Change		% Change
SG&A	$	42,348	$	34,228	$	8,120	23.7	%	$	78,623	$	68,885	$	9,738	14.1	%

Corporate Items selling, general and administrative expenses for the three and six months ended June 30, 2018 increased $8.1 million and $9.7 million, respectively, from the comparable periods in 2017 primarily due to increases in salaries, benefits and variable compensation, including costs associated with the acquired Veolia Business and our commitment to investing in our employees.

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Adjusted Earnings Before Interest, Taxes, Depreciation and Amortization (“Adjusted EBITDA”)

Management considers Adjusted EBITDA to be a measurement of performance which provides useful information to both management and investors. Adjusted EBITDA should not be considered an alternative to net income (loss) or other measurements under generally accepted accounting principles ("GAAP"). Adjusted EBITDA is not calculated identically by all companies, and therefore our measurements of Adjusted EBITDA, while defined consistently and in accordance with our existing credit agreement, may not be comparable to similarly titled measures reported by other companies.

	For the Three Months Ended										For the Six Months Ended
	June 30,						2018 over 2017				June 30,						2018 over 2017
	2018			2017			$ Change			% Change	2018			2017			$ Change			% Change
Adjusted EBITDA:
Environmental Services	$	109,199		$	94,832		$	14,367		15.1%	$	170,616		$	155,022		$	15,594		10.1%
Safety-Kleen	73,069			60,281			12,788			21.2	134,953			112,649			22,304			19.8
Corporate Items	(42,707		)	(34,422		)	(8,285		)	(24.1)	(77,743		)	(66,845		)	(10,898		)	(16.3)
Total	$	139,561		$	120,691		$	18,870		15.6%	$	227,826		$	200,826		$	27,000		13.4%

We use Adjusted EBITDA to enhance our understanding of our operating performance, which represents our views concerning our performance in the ordinary, ongoing and customary course of our operations. We historically have found it helpful, and believe that investors have found it helpful, to consider an operating measure that excludes certain expenses relating to transactions not reflective of our core operations.

The information about our operating performance provided by this financial measure is used by our management for a variety of purposes. We regularly communicate Adjusted EBITDA results to our lenders since our loan covenants are based upon levels of Adjusted EBITDA achieved and to our board of directors and we discuss with the board our interpretation of such results. We also compare our Adjusted EBITDA performance against internal targets as a key factor in determining cash and equity bonus compensation for executives and other employees, largely because we believe that this measure is indicative of how the fundamental business is performing and is being managed.

We also provide information relating to our Adjusted EBITDA so that analysts, investors and other interested persons have the same data that we use to assess our core operating performance. We believe that Adjusted EBITDA should be viewed only as a supplement to the GAAP financial information. We also believe, however, that providing this information in addition to, and together with, GAAP financial information permits the foregoing persons to obtain a better understanding of our core operating performance and evaluate the efficacy of the methodology and information used by management to evaluate and measure such performance on a standalone and a comparative basis.

The following is a reconciliation of net income to Adjusted EBITDA for the following periods (in thousands):

	For the Three Months Ended						For the Six Months Ended
	June 30,						June 30,
	2018			2017			2018			2017
Net income	$	30,747		$	25,880		$	18,116		$	4,487
Accretion of environmental liabilities	2,448			2,416			4,878			4,706
Depreciation and amortization	72,760			71,531			147,604			143,943
Other (income) expense, net	(846		)	833			(547		)	2,382
Loss on early extinguishment of debt	—			6,045			—			6,045
Gain on sale of business	—			(31,722		)	—			(31,722		)
Interest expense, net of interest income	20,769			22,492			41,039			45,068
Provision for income taxes	13,683			23,216			16,736			25,917
Adjusted EBITDA	$	139,561		$	120,691		$	227,826		$	200,826

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Depreciation and Amortization

	For the Three Months Ended									For the Six Months Ended
	June 30,				2018 over 2017					June 30,				2018 over 2017
	2018		2017		$ Change			% Change		2018		2017		$ Change			% Change
Depreciation of fixed assets and landfill amortization	$	64,191	$	61,839	$	2,352		3.8	%	$	129,791	$	125,166	$	4,625		3.7	%
Permits and other intangibles amortization	8,569		9,692		(1,123		)	(11.6	)	17,813		18,777		(964		)	(5.1	)
Total depreciation and amortization	$	72,760	$	71,531	$	1,229		1.7	%	$	147,604	$	143,943	$	3,661		2.5	%

Depreciation and amortization for the three months ended June 30, 2018increased$1.2 million from the comparable period in 2017, primarily due to incremental depreciation from acquisitions.

Depreciation and amortization for the six months ended June 30, 2018increased$3.7 million from the comparable period in 2017, primarily due to increased volumes at our landfills which drove increased landfill amortization and incremental depreciation from acquisitions.

Provision for Income Taxes

	For the Three Months Ended									For the Six Months Ended
	June 30,				2018 over 2017					June 30,				2018 over 2017
	2018		2017		$ Change			% Change		2018		2017		$ Change			% Change
Provision for income taxes	$	13,683	$	23,216	$	(9,533	)	(41.1	)%	$	16,736	$	25,917	$	(9,181	)	(35.4	)%

The income tax provision for the three and six months ended June 30, 2018decreased$9.5 million and $9.2 million as compared to the comparable periods in 2017. The decrease in the three and six months ended June 30, 2018 was primarily due to the lower US federal statutory rate for 2018 which was enacted as part of the Tax Cuts and Jobs Act signed into law in December of 2017. Our effective tax rate for the three and six months ended June 30, 2018 was 30.8% and 48.0%, respectively, compared to 47.3% and 85.2% for the same periods in 2017. The variations in the effective income tax rates for the six months ended June 30, 2018 and the three and six months ended June 30, 2017 as compared to more customary relationships between pre-tax income and the provision for income taxes were primarily due to not recognizing income tax benefits from current operating losses related to certain Canadian entities during these periods.

For the six months ended June 30, 2018, we did not record $6.1 million of income tax benefits generated from losses at certain of our Canadian entities. For the three and six months ended June 30, 2017, we did not record $2.7 million and $13.2 million, respectively, of income tax benefits.

Liquidity and Capital Resources

	Six Months Ended
(in thousands)	June 30, 2018			June 30, 2017
Net cash from operating activities	$	129,670		$	116,931
Net cash used in investing activities	(216,141		)	(50,370		)
Net cash (used in) from financing activities	(33,928		)	70,702

Net cash from operating activities

Net cash from operating activities for the six months ended June 30, 2018 was $129.7 million, an increase of $12.7 million from the comparable period in 2017. The increase in operating cash flows as compared to the comparable period of 2017 was most directly attributable to greater levels of operating income and lower interest payments offset by higher working capital levels due to growth in our business. Operating cash flows for the remainder of 2018 are expected to continue to be greater than prior year levels.

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Net cash used in investing activities

Net cash used in investing activities for the six months ended June 30, 2018 was $216.1 million, an increase of $165.8 million from the comparable period in 2017. The change was primarily driven by the use of cash to fund the acquisition of the Veolia Business on February 23, 2018and the proceeds from the Transformer Services divestiture in June 2017.

Net cash (used in) from financing activities

Net cash used in financing activities for the six months ended June 30, 2018 was $33.9 million, compared with net cash from financing activities of $70.7 million in the comparable period in 2017. In the six months ended June 30, 2017, we had net proceeds from the issuance of debt as we entered into the $400.0 million Term Loan Agreement and used the proceeds to purchase approximately $296.2 million aggregate principal amount of our previously outstanding 2020 Notes. In the six months ended June 30, 2018, we had no net proceeds from the issuance of debt and had a net cash outflow due to an increase in repurchases of common stock, which were partially offset by a change in uncashed checks which resulted from the timing of payments made.

AdjustedFree Cash Flow

Management considers adjusted free cash flow to be a measurement of liquidity which provides useful information to both management and investors about our financial strength and our ability to generate cash. Additionally, adjusted free cash flow is a metric on which management incentive compensation is based. We define adjusted free cash flow as net cash from operating activities excluding cash impacts of items derived from non-operating activities, such as taxes paid in connection with divestitures, less additions to property, plant and equipment plus proceeds from sale and disposal of fixed assets. Adjusted free cash flow should not be considered an alternative to net cash from operating activities or other measurements under GAAP. Adjusted free cash flow is not calculated identically by all companies, and therefore our measurements of adjusted free cash flow may not be comparable to similarly titled measures reported by other companies.

The following is a reconciliation of net cash from operating activities to adjusted free cash flow for the following periods (in thousands):

	Six Months Ended
	June 30,
	2018			2017
Net cash from operating activities	$	129,670		$	116,931
Additions to property, plant and equipment	(94,139		)	(88,742		)
Proceeds from sale and disposal of fixed assets	2,641			2,121
Adjusted free cash flow	$	38,172		$	30,310

Working Capital

At June 30, 2018, cash and cash equivalents totaled $197.1 million, compared to $319.4 million at December 31, 2017. At June 30, 2018, cash and cash equivalents held by our foreign subsidiaries totaled $43.2 million and were readily convertible into other foreign currencies including U.S. dollars. At June 30, 2018, the cash and cash equivalent balance for our U.S. operations was $153.9 million, and our U.S. operations had net operating cash flow of $117.0 million for the six months ended June 30, 2018. Additionally, we have a $400.0 million revolving credit facility of which approximately $244.3 million was available to borrow at June 30, 2018. Based on the above and on our current plans, we believe that our U.S. operations have and will continue to have adequate financial resources to satisfy their liquidity needs without being required to repatriate earnings from foreign subsidiaries. We also believe that cash held by our foreign subsidiaries will be required to fund those foreign operations. Accordingly, although repatriation to the U.S. of foreign earnings would generally be subject to taxation, we have not recorded any deferred tax liability related to such repatriation since we intend to permanently reinvest foreign earnings outside the U.S.

We assess our liquidity in terms of our ability to generate cash to fund our operating, investing, and financing activities. Our primary ongoing cash requirements will be to fund operations, capital expenditures, interest payments and investments in line with our business strategy. We believe our future operating cash flows will be sufficient to meet our future operating and internal investing cash needs as well as any cash needs relating to our stock repurchase program. Furthermore, our existing cash balance and the availability of additional borrowings under our revolving credit facility provide additional potential sources of liquidity should they be required.

Financing Arrangements

The financing arrangements and principal terms of our $400.0 million principal amount of 5.25% senior unsecured notes due 2020, $845.0 million principal amount of 5.125% senior unsecured notes due 2021, and $396.0 million senior secured notes due

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2024 which were outstanding at June 30, 2018, and our $400.0 million revolving credit facility, are discussed further in Note 12, “Financing Arrangements,” to our consolidated financial statements included herein. We continue to monitor our debt instruments and evaluate opportunities where it may be beneficial to refinance or reallocate the portfolio.

As of June 30, 2018, we were in compliance with the covenants of all of our debt agreements, and we believe it is reasonably likely that we will continue to meet such covenants.

As discussed in Note 12, “Financing Arrangements,” to our consolidated financial statements, we have refinanced a portion of our debt portfolio whereby the $400 million of previously outstanding 5.25% senior unsecured notes due 2020 have been replaced by $350 million of incremental term loans under our variable rate Term Loan Agreement and $50 million of borrowings under our revolving credit facility. In connection with the addition of this variable rate debt, we intend to enter into an interest rate swap instrument in order to effectively hedge the future risk of rising interest rates and effectively fix the interest rate on $350 million of our variable rate debt.

Environmental Liabilities

(in thousands)	June 30, 2018		December 31, 2017		$ Change			% Change
Closure and post-closure liabilities	$	65,504	$	61,037	$	4,467		7.3	%
Remedial liabilities	121,275		124,468		(3,193		)	(2.6	)
Total environmental liabilities	$	186,779	$	185,505	$	1,274		0.7	%

Total environmental liabilities as of June 30, 2018 were $186.8 million, an increase of $1.3 million, compared to December 31, 2017 primarily due to accretion of $4.9 million and new asset retirement obligations and liabilities assumed in acquisition of $2.1 million, partially offset by expenditures of $4.6 million and a benefit from changes in environmental liability estimates of $0.7 million.

We anticipate our environmental liabilities, substantially all of which we assumed in connection with our acquisitions, will be payable over many years and that cash flow from operations will generally be sufficient to fund the payment of such liabilities when required. However, events not anticipated (such as future changes in environmental laws and regulations) could require that such payments be made earlier or in greater amounts than currently anticipated, which could adversely affect our results of operations, cash flow and financial condition.

Capital Expenditures

We anticipate that 2018 capital spending, net of disposals, will be in the range of $170.0 million to $190.0 million. However, changes in environmental regulations or unscheduled capital needs could require us to make significant capital expenditures for our facilities and adversely affect our results of operations and cash flow.

Critical Accounting Policies and Estimates

Other than described below, there were no material changes in the first six months of 2018 to the information provided under the heading “Critical Accounting Policies and Estimates” included in our Annual Report on Form 10-K for the year ended December 31, 2017.

Goodwill. Goodwill is not amortized but is reviewed for impairment annually as of December 31 or when events or changes in the business environment indicate the carrying value of a reporting unit may exceed its fair value. This review is performed by comparing the fair value of each reporting unit to its carrying value, including goodwill. If the fair value is less than the carrying amount, a loss is recorded for the excess of the carrying value over the fair value up to the carrying amount of goodwill.

We conducted our annual impairment test of goodwill for all of our reporting units to which goodwill is allocated as of December 31, 2017 and determined that no adjustment to the carrying value of goodwill for any reporting unit was then necessary. As a result of changes in our organizational structure and resulting change in our operating segments discussed above, we concluded that, for purposes of reviewing for potential goodwill impairment, we had four reporting units, consisting of Environmental Sales and Service, Environmental Facilities, Kleen Performance Products and Safety-Kleen Environmental Services. The results of operations for our Environmental Sales and Service and Environmental Facilities reporting units are included in our Environmental Services segment, and the results of operations for our SK Environmental and Kleen Performance Products reporting units are included in our Safety-Kleen segment. We allocated goodwill to our new reporting units using a relative fair value approach. Due to the change in our reporting units, we completed an assessment of any potential goodwill impairment immediately prior to and subsequent to the reorganization, which was effective January 1, 2018, and determined that no impairment existed.

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ITEM 3.QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

There were no material changes in the first six months of 2018 to the information provided under Item 7A. “Quantitative and Qualitative Disclosures about Market Risk” in the Company's Annual Report on Form 10-K for the year ended December 31, 2017.

ITEM 4.CONTROLS AND PROCEDURES

Evaluation of Disclosure Controls and Procedures

Based on an evaluation under the supervision and with the participation of our Chief Executive Officer and Chief Financial Officer, as of the end of the period covered by this Quarterly Report on 10-Q, our Chief Executive Officer and Chief Financial Officer have concluded that our disclosure controls and procedures (as defined under Rule 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) were effective as of June 30, 2018 to ensure that information required to be disclosed by us in reports that we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in Securities and Exchange Commission rules and forms and is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate to allow timely decisions regarding required disclosure.

Changes in Internal Control over Financial Reporting

There were no changes in the Company’s internal control over financial reporting identified in connection with the evaluation required by paragraph (d) of Exchange Act Rules 13a-15 or 15d-15 that was conducted during the quarter ending June 30, 2018 that have materially affected, or are reasonably likely to materially affect, the Company’s internal control over financial reporting.

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CLEAN HARBORS, INC. AND SUBSIDIARIES

PART II—OTHER INFORMATION

ITEM 1.LEGAL PROCEEDINGS

See Note 16, “Commitments and Contingencies,” to the financial statements included in Item 1 of this report, which description is incorporated herein by reference.

ITEM 1A.RISK FACTORS

During the six months ended June 30, 2018, there were no material changes from the risk factors as previously disclosed in Item 1A in the Company's Annual Report on Form 10-K for the year ended December 31, 2017. 

ITEM 2.UNREGISTERED SALES OF EQUITY SECURITIES AND USE OF PROCEEDS

Common Stock Repurchase Program

The following table provides information with respect to the shares of common stock repurchased by us for the periods indicated.

Period	Total Number of Shares Purchased (1)	Average Price Paid Per Share (2)		Total Number of Shares Purchased as Part of Publicly Announced Plans or Programs	Approximate Dollar Value of Shares that May Yet Be Purchased Under the Plans or Programs (3)
April 1, 2018 through April 30, 2018	200,959	$	47.38	180,694	$	328,357,065
May 1, 2018 through May 31, 2018	41,067	$	50.57	40,298	$	326,315,292
June 1, 2018 through June 30, 2018	42,044	$	53.46	30,808	$	324,670,703
Total	284,070	$	48.74	251,800	$	324,670,703

______________________

(1) Includes 32,270 shares withheld by us from employees to satisfy employee tax obligations upon vesting of restricted stock units granted to our employees under our long-term equity incentive programs.

(2) The average price paid per share of common stock repurchased under the stock repurchase program includes the commissions paid to brokers.

(3) On October 31, 2017, the Company's board of directors increased the size of the Company’s current share repurchase program from $300 million to $600 million. We have funded and intend to fund the repurchases through available cash resources. The stock repurchase program authorizes us to purchase our common stock on the open market or in privately negotiated transactions periodically in a manner that complies with applicable U.S. securities laws. The number of shares purchased and the timing of the purchases has depended and will depend on a number of factors, including share price, cash required for business plans, trading volume and other conditions. During April 2018, the Company implemented a repurchase plan in accordance with Rule 10b5-1 promulgated under the Securities Exchange Act of 1934, as amended. Going forward repurchases will be made under the Rule 10b5-1 plan as well as open market or privately negotiated transactions as described above. We have no obligation to repurchase stock under this program and may suspend or terminate the repurchase program at any time.

ITEM 3.DEFAULTS UPON SENIOR SECURITIES

None

ITEM 4.MINE SAFETY DISCLOSURE

Not applicable

ITEM 5.OTHER INFORMATION

None

43

ITEM 6.EXHIBITS

Item No.	Description	Location
31.1	Rule 13a-14a/15d-14(a) Certification of the CEO Alan S. McKim	Filed herewith
31.2	Rule 13a-14a/15d-14(a) Certification of the CFO Michael L. Battles	Filed herewith
32	Section 1350 Certifications	Filed herewith
101	Interactive Data Files Pursuant to Rule 405 of Regulation S-T: Financial statements from the quarterly report on Form 10-Q of Clean Harbors, Inc. for the quarter ended June 30, 2018, formatted in XBRL: (i) Consolidated Balance Sheets, (ii) Unaudited Consolidated Statements of Operations, (iii) Unaudited Consolidated Statements of Comprehensive Income (Loss), (iv) Unaudited Consolidated Statements of Cash Flows, (v) Unaudited Consolidated Statements of Stockholders’ Equity, and (vi) Notes to Unaudited Consolidated Financial Statements.	*

_______________________

* Interactive data files are furnished and deemed not filed or part of a registration statement or prospectus for purposes of Sections 11 or 12 of the Securities Act of 1933, as amended, are deemed not filed for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, and otherwise are not subject to liability under those sections.

44

CLEAN HARBORS, INC. AND SUBSIDIARIES

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. 

		CLEAN HARBORS, INC.
		Registrant
		By:	/s/  ALAN S. MCKIM
			Alan S. McKim
			Chairman, President and Chief Executive Officer
Date:	August 1, 2018
		By:	/s/  MICHAEL L. BATTLES
			Michael L. Battles
			Executive Vice President and Chief Financial Officer
Date:	August 1, 2018

45

EX-31.1

EXHIBIT 31.1

CERTIFICATION OF CHIEF EXECUTIVE OFFICER

I, Alan S. McKim, certify that:

1.I have reviewed this Quarterly Report on Form 10-Q of Clean Harbors, Inc.;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

/s/ Alan S. McKim

Alan S. McKim

Chairman, President and Chief Executive Officer

Date: August 1, 2018

EX-31.2

Exhibit 31.2

CERTIFICATION OF CHIEF FINANCIAL OFFICER

I, Michael L. Battles, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Clean Harbors, Inc.;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

/s/ Michael L. Battles

Michael L. Battles

Executive Vice President and Chief Financial Officer

Date: August 1, 2018

EX-32

EXHIBIT 32

CLEAN HARBORS, INC. AND SUBSIDIARIES

CERTIFICATION PURSUANT TO
SECTION 1350, CHAPTER 63 OF TITLE 18, UNITED STATES CODE,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES OXLEY ACT OF 2002

Pursuant to 18 U.S.C. §1350, each of the undersigned certifies that, to his knowledge, this Quarterly Report on Form 10-Q for the period ended June 30, 2018 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and the information contained in this report fairly presents, in all material respects, the financial condition and results of operations of Clean Harbors, Inc.

		By:	/s/  ALAN S. MCKIM
			Alan S. McKim
			Chairman, President and Chief Executive Officer
Date:	August 1, 2018
		By:	/s/  MICHAEL L. BATTLES
			Michael L. Battles
			Executive Vice President and Chief Financial Officer
Date:	August 1, 2018

XML

DOCUMENT AND ENTITY INFORMATION - shares	6 Months Ended
	Jun. 30, 2018	Jul. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	CLEAN HARBORS INC
Entity Central Index Key	0000822818
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		56,088,908

XML

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 197,068	$ 319,399
Short-term marketable securities	36,862	38,179
Accounts receivable, net of allowances aggregating $34,033 and $27,799, respectively	590,580	528,924
Unbilled accounts receivable	62,762	35,922
Deferred costs	20,832	20,445
Inventories and supplies	193,544	176,012
Prepaid expenses and other current assets	34,834	35,175
Total current assets	1,136,482	1,154,056
Property, plant and equipment, net	1,609,382	1,587,365
Other assets:
Goodwill	497,251	478,523
Permits and other intangibles, net	455,920	469,128
Other	16,426	17,498
Total other assets	969,597	965,149
Total assets	3,715,461	3,706,570
Current liabilities:
Current portion of long-term obligations	4,000	4,000
Accounts payable	247,821	224,231
Deferred revenue	68,705	67,822
Accrued expenses	200,135	187,982
Current portion of closure, post-closure and remedial liabilities	23,007	19,782
Total current liabilities	543,668	503,817
Other liabilities:
Closure and post-closure liabilities, less current portion of $6,514 and $6,444, respectively	58,990	54,593
Remedial liabilities, less current portion of $16,493 and $13,338, respectively	104,782	111,130
Long-term obligations, less current portion	1,624,727	1,625,537
Deferred taxes, unrecognized tax benefits and other long-term liabilities	222,246	223,291
Total other liabilities	2,010,745	2,014,551
Commitments and contingent liabilities (See Note 16)
Stockholders’ equity:
Authorized 80,000,000; shares issued and outstanding 56,087,256 and 56,501,190 shares, respectively	561	565
Additional paid-in capital	664,948	686,962
Accumulated other comprehensive loss	(194,095)	(172,407)
Accumulated earnings	689,634	673,082
Total stockholders’ equity	1,161,048	1,188,202
Total liabilities and stockholders’ equity	$ 3,715,461	$ 3,706,570

XML

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Account receivable, allowances aggregating	$ 34,033	$ 27,799
Closure and post-closure liabilities, current portion	6,514	6,444
Remedial liabilities, current portion	$ 16,493	$ 13,338
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Common stock, authorized shares (in shares)	80,000,000	80,000,000
Common stock, issued shares (in shares)	56,087,256	56,501,190
Common stock, outstanding shares (in shares)	56,087,256	56,501,190

XML

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Total revenues	$ 849,140	$ 752,788	$ 1,598,918	$ 1,441,729
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	583,584	519,803	1,130,009	1,016,388
Selling, general and administrative expenses	125,995	112,294	241,083	224,515
Accretion of environmental liabilities	2,448	2,416	4,878	4,706
Depreciation and amortization	72,760	71,531	147,604	143,943
Income from operations	64,353	46,744	75,344	52,177
Other income (expense), net	846	(833)	547	(2,382)
Loss on early extinguishment of debt	0	(6,045)	0	(6,045)
Gain on sale of business	0	31,722	0	31,722
Interest expense, net of interest income of $587, $311, $1,350 and $520, respectively	(20,769)	(22,492)	(41,039)	(45,068)
Income before (benefit) provision for income taxes	44,430	49,096	34,852	30,404
Provision for income taxes	13,683	23,216	16,736	25,917
Net income	$ 30,747	$ 25,880	$ 18,116	$ 4,487
Earnings per share:
Basic (in USD per share)	$ 0.55	$ 0.45	$ 0.32	$ 0.08
Diluted (in USD per share)	$ 0.54	$ 0.45	$ 0.32	$ 0.08
Shares used to compute loss per share - Basic (in shares)	56,410	57,190	56,304	57,226
Shares used to compute loss per share - Diluted (in shares)	56,505	57,336	56,399	57,349
Service
Revenues:
Total revenues	$ 696,779	$ 610,940	$ 1,316,498	$ 1,171,154
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	473,423	412,356	921,072	803,443
Product
Revenues:
Total revenues	152,361	141,848	282,420	270,575
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	$ 110,161	$ 107,447	$ 208,937	$ 212,945

XML

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Interest expense	$ 587	$ 311	$ 1,350	$ 520

XML

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 30,747	$ 25,880	$ 18,116	$ 4,487
Other comprehensive (loss) income:
Unrealized (losses) gains on available-for-sale securities (net of tax of $8, $20, $88 and $122, respectively)	(11)	27	(206)	159
Reclassification adjustment for losses on available-for-sale securities included in net income (net of taxes of $0, $29, $0 and $79, respectively)	0	47	0	143
Foreign currency translation adjustments (including a tax benefit of $5.6 million in 2018)	(4,931)	15,024	(21,482)	20,847
Other comprehensive (loss) income	(4,942)	15,098	(21,688)	21,149
Comprehensive income (loss)	$ 25,805	$ 40,978	$ (3,572)	$ 25,636

XML

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Unrealized gains (losses) on available-for-sale securities, taxes	$ 8	$ 20	$ 88	$ 122
Reclassification adjustment for gains on available-for-sale securities included in net (loss) income taxes			0	$ 0
Foreign currency translation adjustments, tax benefit			$ (5,600)

XML

UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 18,116	$ 4,487
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	147,604	143,943
Allowance for doubtful accounts	7,389	3,580
Amortization of deferred financing costs and debt discount	1,881	1,660
Accretion of environmental liabilities	4,878	4,706
Changes in environmental liability estimates	(673)	(129)
Deferred income taxes	(10)	190
Stock-based compensation	6,639	5,172
Other (income) expense, net	(547)	2,382
Gain on sale of business	0	(31,722)
Loss on early extinguishment of debt	0	6,045
Environmental expenditures	(4,585)	(6,102)
Changes in assets and liabilities, net of acquisitions
Accounts receivable and unbilled accounts receivable	(62,764)	(31,154)
Inventories and supplies	(18,625)	(6,307)
Other current assets	180	13,918
Accounts payable	23,605	(2,686)
Other current and long-term liabilities	6,582	8,948
Net cash from operating activities	129,670	116,931
Cash flows used in investing activities:
Additions to property, plant and equipment	(94,139)	(88,742)
Proceeds from sale and disposal of fixed assets	2,641	2,121
Acquisitions, net of cash acquired	(123,750)	(9,277)
Proceeds from sale of businesses, net of transactional costs	0	46,391
Additions to intangible assets, including costs to obtain or renew permits	(2,106)	(1,239)
Proceeds from sale of available-for-sale securities	11,214	376
Purchases of available-for-sale securities	(10,001)	0
Net cash used in investing activities	(216,141)	(50,370)
Cash flows (used in) from financing activities:
Change in uncashed checks	(2,803)	(8,361)
Proceeds from exercise of stock options	0	46
Tax payments related to withholdings on vested restricted stock	(2,175)	(2,132)
Repurchases of common stock	(26,482)	(12,257)
Deferred financing costs paid	(468)	(4,727)
Premiums paid on early extinguishment of debt	0	(4,665)
Principal payment on debt	(2,000)	(296,202)
Issuance of senior secured notes, net of discount	0	399,000
Net cash (used in) from financing activities	(33,928)	70,702
Effect of exchange rate change on cash	(1,932)	2,106
(Decrease) increase in cash and cash equivalents	(122,331)	139,369
Cash and cash equivalents, beginning of period	319,399	306,997
Cash and cash equivalents, end of period	197,068	446,366
Cash payments for interest and income taxes:
Interest paid	40,745	50,432
Income taxes paid	14,118	13,407
Non-cash investing activities:
Property, plant and equipment accrued	13,041	16,213
Transfer of inventory to property, plant and equipment	$ 0	$ 12,641

XML

UNAUDITED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - 6 months ended Jun. 30, 2018 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Earnings
Balance at beginning of period at Dec. 31, 2017	$ 1,188,202	$ 565	$ 686,962	$ (172,407)	$ 673,082
Balance beginning of period (in shares) at Dec. 31, 2017		56,501
Increase (Decrease) in Stockholders' Equity
Net income	18,116				18,116
Other comprehensive loss	(21,688)			(21,688)
Stock-based compensation	6,639		6,639
Issuance of restricted shares, net of shares remitted and tax withholdings	(2,175)	$ 1	(2,176)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		118
Repurchases of common stock	$ (26,482)	$ (5)	(26,477)
Repurchases of common stock (in shares)	(500)	(532)
Balance at end of period at Jun. 30, 2018	$ 1,161,048	$ 561	$ 664,948	$ (194,095)	689,634
Balance ending of period (in shares) at Jun. 30, 2018		56,087
Increase (Decrease) in Stockholders' Equity
Cumulative effect of change in accounting principle	$ (1,564)
Cumulative effect of change in accounting principle | Accounting Standards Update 2016-16					$ (1,564)

XML

UNAUDITED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Common stock, par value (in USD per share)	$ 0.01	$ 0.01

XML

BASIS OF PRESENTATION

6 Months Ended

Jun. 30, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

BASIS OF PRESENTATION

BASIS OF PRESENTATION

The accompanying consolidated interim financial statements are unaudited and include the accounts of Clean Harbors, Inc. and its subsidiaries (collectively, “Clean Harbors,” the “Company” or "we") and have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) and, in the opinion of management, include all adjustments which are of a normal recurring nature, necessary for a fair presentation of the financial position, results of operations, and cash flows for the periods presented. Management has made estimates and assumptions affecting the amounts reported in the Company's consolidated interim financial statements and accompanying footnotes, actual results could differ from those estimates and judgments. The results for interim periods are not necessarily indicative of results for the entire year or any other interim periods. The financial statements presented herein should be read in connection with the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017.

XML

SIGNIFICANT ACCOUNTING POLICIES

6 Months Ended

Jun. 30, 2018

Accounting Policies [Abstract]

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES

The Company's significant accounting policies are described in Note 2, "Significant Accounting Policies," in the Company's Annual Report on Form 10-K for the year ended December 31, 2017. There have been no material changes in these policies or their application except for the changes described below.

Reclassifications

During the first quarter of fiscal year 2018, certain of the Company's businesses undertook a reorganization which included changes to the underlying business and management structures. The reorganization resulted in combining the Environmental Services businesses from an operational and management perspective and is expected to deepen customer relationships and allow for efficiencies across the Company's operations through the sharing of resources, namely labor and equipment which will reduce third party spend and promote the cross selling of such business offerings. In connection with this reorganization, the Company’s chief operating decision maker also requested changes in the information that he regularly reviews for purposes of allocating resources and assessing performance. These changes required a reconsideration of the Company’s operating segments in the first quarter of 2018 and resulted in a change in the Company’s assessment of its operating segments. Upon reconsideration of the identification of the Company’s operating segments, the Company concluded that there are now two operating segments for disclosure in accordance with ASC 280 Segment reporting; (i) the Environmental Services segment which consists of the Company’s historical Technical Services, Industrial Services, Field Services and Oil, Gas and Lodging businesses and (ii) the Safety-Kleen segment. See Note 18, "Segment Reporting," for more information. The amounts presented for the three and six months ended June 30, 2017 have been recast to reflect the impact of such changes. These reclassifications and adjustments had no effect on the consolidated statements of operations, consolidated statements of comprehensive loss, consolidated statements of cash flows or consolidated statements of stockholders' equity for any of the periods presented.

Recent Accounting Pronouncements

Standards implemented

In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606), which replaces numerous requirements in U.S. GAAP, including industry-specific requirements, and provides companies with a single revenue recognition model for recognizing revenue from contracts with customers. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the modified retrospective method). On January 1, 2018, the Company adopted Topic 606 using the modified retrospective method for all contracts. Results for reporting periods beginning on the date of adoption are presented under ASC 606, while prior period amounts have not been adjusted and continue to be reported in accordance with the Company's historical accounting methodology pursuant to ASC 605, Revenue Recognition (“ASC 605”). Upon adoption, a cumulative effect adjustment was not required as the majority of the Company’s contracts are recognized based on time and materials incurred and were not impacted by the new guidance. The Company has concluded that the most significant impact of the standard relates to the incremental disclosures required.

In October 2016, the FASB issued ASU 2016-16, Income Tax - Intra-Entity Transfers of Assets Other than Inventory. The amendment improves the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The Company adopted the amendment on a modified retrospective basis effective January 1, 2018. As a result of adoption, the Company recorded a cumulative effect adjustment that reduced retained earnings by $1.6 million.

In March 2017, the FASB issued ASU 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendment requires an employer to report the service cost component of net benefit cost in the same line item as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. In addition, the amendment allows only the service cost component to be eligible for capitalization when applicable. The Company adopted the amendment in the first quarter of 2018. Adoption did not have a material impact on the Company's consolidated financial statements.

Standards to be implemented

The Company is evaluating the impact that the below standards to be implemented will have on the Company's consolidated financial statements.

In February 2016, FASB issued ASU 2016-02, Leases (Topic 842). The amendment increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. In February 2018, FASB issued ASU 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842. The amendment clarifies that land easements are within the scope of the new leases standard (ASC 842) and introduces a new transition practical expedient allowing a company to not assess whether existing and expired land easements that were not previously accounted for as leases under current US GAAP (ASC 840) are or contain leases under ASC 842. In July 2018, FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases. The amendment provides improvements that clarify specific aspects of the guidance in ASU 2016-02. The Company will adopt the new standard beginning on January 1, 2019. A modified retrospective transition approach is required for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. While the Company is still continuing to assess the effect of adoption, it expects that the new standard will have a material effect on its consolidated balance sheet related to the recognition of new assets and lease liabilities. In preparation for the adoption of the guidance, the Company is in the process of implementing new software and assessing changes to controls and processes to enable the preparation of financial information.

In June 2016, FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendment changes the way entities recognize impairment of many financial assets, including accounts receivable and investments in debt securities, by requiring immediate recognition of estimated credit losses expected to occur over their remaining lives. The amendment should be applied using a modified-retrospective approach and is effective for the Company for annual and interim reporting periods beginning after January 1, 2020, with early adoption permitted. The Company is currently evaluating the impact ASU 2016-13 will have on its consolidated financial statements.

In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendment better aligns an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The amendment is effective for the Company for annual and interim reporting periods beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the impact ASU 2017-12 will have on its consolidated financial statements.

XML

REVENUES

6 Months Ended

Jun. 30, 2018

Revenue from Contract with Customer [Abstract]

REVENUES

REVENUES

Revenue Recognition

Revenues are recognized when control of the promised goods or services is transferred to the Company’s customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services.

Nature of Goods and Services

The Company generates services and product revenues through its Environmental Services and Safety-Kleen operating segments. The majority of the Company’s contracts are for services, which are recognized based on time and materials incurred at contractually agreed-upon rates. Product revenues are recognized when the products are delivered and control transfers to the customer. The Company’s payment terms vary by the type and location of its customers and the products or services offered. The term between invoicing and when payment is due is not significant. The Company excludes sales taxes that it collects from customers from its revenues.

Disaggregation of Revenue

The following table presents the Company’s revenues disaggregated by revenue source (in thousands):

	For the Three Months Ended June 30, 2018
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	408,127	$	306,059	$	363	$	714,549
Canada	111,789		22,656		146		134,591
	519,916		328,715		509		849,140
Sources of Revenue (1)
Technical Services	257,006		—		—		$	257,006
Field and Emergency Response Services	76,092		—		—		76,092
Industrial Services	161,046		—		—		161,046
Oil, Gas and Lodging Services and Other	25,772		—		509		26,281
Safety-Kleen Environmental Services	—		200,034		—		200,034
Kleen Performance Products	—		128,681		—		128,681
Total third party revenues	$	519,916	$	328,715	$	509	$	849,140

	For the Three Months Ended June 30, 2017
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	343,323	$	280,617	$	155	$	624,095
Canada	106,308		22,339		46		128,693
	449,631		302,956		201		752,788
Sources of Revenue (1)
Technical Services	254,487		—		—		254,487
Field and Emergency Response Services	70,707		—		—		70,707
Industrial Services	99,733		—		—		99,733
Oil, Gas and Lodging Services and Other	24,704		—		201		24,905
Safety-Kleen Environmental Services	—		192,817		—		192,817
Kleen Performance Products	—		110,139		—		110,139
Total third party revenues	$	449,631	$	302,956	$	201	$	752,788

	For the Six Months Ended June 30, 2018
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	752,099	$	593,701	$	508	$	1,346,308
Canada	207,505		44,932		173		252,610
	959,604		638,633		681		1,598,918
Sources of Revenue (1)
Technical Services	493,312		—		—		493,312
Field and Emergency Response Services	146,027		—		—		146,027
Industrial Services	264,809		—		—		264,809
Oil, Gas and Lodging Services and Other	55,456		—		681		56,137
Safety-Kleen Environmental Services	—		394,195		—		394,195
Kleen Performance Products	—		244,438		—		244,438
Total third party revenues	$	959,604	$	638,633	$	681	$	1,598,918

	For the Six Months Ended June 30, 2017
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	657,106	$	552,688	$	288	$	1,210,082
Canada	188,432		43,169		46		231,647
	845,538		595,857		334		1,441,729
Sources of Revenue (1)
Technical Services	484,705		—		—		484,705
Field and Emergency Response Services	131,726		—		—		131,726
Industrial Services	174,801		—		—		174,801
Oil, Gas and Lodging Services and Other	54,306		—		334		54,640
Safety-Kleen Environmental Services	—		384,544		—		384,544
Kleen Performance Products	—		211,313		—		211,313
Total third party revenues	$	845,538	$	595,857	$	334	$	1,441,729

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1. All revenue except Kleen Performance Products and product sales within Safety-Kleen Environmental Services, including allied products and direct blended oil sales, are recognized over time. Kleen Performance Products and Safety-Kleen Environmental Services product revenues are recognized at a point in time.

Technical Services. Technical Services revenues are generated from fees charged for waste material management and disposal services including onsite environmental management services, collection and transportation, packaging, recycling, treatment and disposal of waste. Revenue is primarily generated by short-term projects, most of which are governed by master service agreements that are long-term in nature. These master service agreements are typically entered into with the Company's larger customers and outline the pricing and legal frameworks for such arrangements. Services are provided based on purchase orders or agreements with the customer and include prices based upon units of volume of waste, and transportation and other fees. Collection and transportation revenues are recognized over time, as the customer receives and consumes the benefits of the service as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. Revenues for treatment and disposal of waste are recognized upon completion of treatment, final disposition in a landfill or incineration, or when the waste is shipped to a third party for processing and disposal. The Company periodically enters into bundled arrangements for the collection and transportation and disposal of waste. For such arrangements, transportation and disposal are considered distinct performance obligations and the Company allocates revenue to each based on their relative standalone selling price (i.e. the estimated price that a customer would pay for the services on a standalone basis). Revenues from waste that is not yet completely processed and disposed and the related costs are deferred. The revenue is recognized and the deferred costs are expensed when the related services are completed. The period between collection and transportation and the final processing and disposal ranges depending on location of the customer, but generally is measured in days.

Field and Emergency Response Services. Field Services revenues are generated from cleanup services at customer sites, including municipalities and utilities, or other locations on a scheduled or emergency response basis. Services include confined space entry for tank cleaning, site decontamination, large remediation projects, demolition, spill cleanup on land and water, railcar cleaning, product recovery and transfer and vacuum services. Additional services include filtration and water treatment services. Response services for environmental emergencies include any scale from man-made disasters such as oil spills, to natural disasters such as hurricanes. These services are provided based on purchase orders or agreements with customers and include prices generally based upon daily, hourly or job rates for equipment, materials and personnel. The Company recognizes revenue for these services over time, as the customer receives and consumes the benefits of the service as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. The duration of such services can be over a number of hours, several days or even months for larger scale projects.

Industrial Services. Industrial Services revenues are generated from industrial and specialty services provided to refineries, mines, upgraders, chemical plants, pulp and paper mills, manufacturing facilities, power generation facilities and other industrial customers throughout North America. Services include in-plant cleaning and maintenance services, plant outage and turnaround services, decoking and pigging, chemical cleaning, high and ultra-high pressure water cleaning, pipeline inspection and coating services, large tank and surface impoundment cleaning, oilfield transport, daylighting, production services and directional boring services (previously included in Oil, Gas and Lodging service offerings) supporting drilling, completions and production programs. These services are provided based on purchase orders or agreements with the customer and include prices based upon daily, hourly or job rates for equipment, materials and personnel. The Company recognizes revenue for these services over time, as the customer receives and consumes the benefits of the service as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred.

Safety-Kleen Environmental Services. Safety-Kleen Environmental Services revenues are generated from providing parts washer services, containerized waste handling and disposal services, oil collection services, direct sales of blended oil products, and other complementary services and product sales. Containerized waste services consist of profiling, collecting, transporting and recycling or disposing of a wide variety of waste. Other complementary products and services include vacuum services, sale of allied supply products and other environmental services. Revenues from parts washer services include fees charged to customers for their use of parts washer equipment, to clean and maintain parts washer equipment and to remove and replace used cleaning fluids. Parts washer services are considered a single performance obligation due to the highly integrated and interdependent nature of the arrangement. Revenue from parts washer services is recognized over the service interval as the customer receives the benefit of the service. Collection and transportation revenues are recognized over time, as the customer receives and consumes the benefits of the service as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. Product revenue is recognized upon the transfer of control. Control transfers when the products are delivered to the customer.

Kleen Performance Products. Kleen Performance Products revenues are generated from sales of high quality base and blended lubricating oils to third-party distributors, government agencies, fleets, railroads and industrial customers. The business also sells recycled fuel oil to asphalt plants, industrial plants, blenders, pulp and paper companies, vacuum gas oil producers and marine diesel oil producers. Revenue for oil products is recognized at a point in time, upon the transfer of control. Control transfers when the products are delivered to the customer.

Oil, Gas and Lodging Services and Other. Oil, Gas and Lodging Services and Other is primarily comprised of revenues generated from providing Oil and Gas Field Services that support upstream activities such as exploration and drilling for oil and gas companies and Lodging Services to customers in Western Canada. The Company recognizes Oil and Gas Field Services revenue over time, as the customer receives and consumes the benefits of the service as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. Revenue for lodging accommodation services is recognized over time based on passage of time. Revenue for manufacturing services is recognized over time using a cost-to-cost measure of progress or completed units to depict the transfer of assets to the customer.

Contract Balances

	June 30, 2018		December 31, 2017		June 30, 2017		December 31, 2016
Receivables	$	590,580	$	528,924	$	512,375	$	496,226
Contract Assets (Unbilled Receivables)	62,762		35,922		46,576		36,190
Contract Liabilities (Deferred Revenue)	68,705		67,822		72,089		64,397

The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables (contract assets), and customer advances and deposits or deferred revenue (contract liabilities) on the Consolidated Balance Sheet. Generally, billing occurs subsequent to revenue recognition, as a right to payment is not just subject to passage of time, resulting in contract assets. Contract assets are generally classified as current. The Company sometimes receives advances or deposits from its customers before revenue is recognized, resulting in contract liabilities. These assets and liabilities are reported on the Consolidated Balance Sheet on a contract-by-contract basis at the end of each reporting period. As part of the acquisition of the Veolia Business on February 23, 2018, the Company acquired receivables and contract assets of $20.5 million and $17.6 million, respectively. Changes in the contract asset and liability balances during the six-month period ended June 30, 2018 and June 30, 2017 were not materially impacted by any other factors. The contract liability balances at the beginning of each period presented were fully recognized in the subsequent three-month period.

Remaining Performance Obligations

Remaining performance obligations represent the transaction price of orders for which work has not been performed. As of June 30, 2018, all remaining performance obligations were for contracts with an original expected length of one year or less.

Variable Consideration

The nature of the Company's contracts gives rise to certain types of variable consideration, including in limited cases volume and payment discounts. The Company estimates the amount of variable consideration to include in the estimated transaction price based on historical experience, anticipated performance and its best judgment at the time and to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Variable consideration was not material in any of the periods presented.

Contract Costs

Contract costs include direct and incremental costs to obtain or fulfill a contract. The Company’s contract costs that are subject to capitalization are comprised of costs associated with parts washer services and costs associated with the treatment and disposal of waste. Parts washer costs include costs of solvent, commissions paid relating to revenue generated from parts washer services, and transportation costs associated with transferring the product picked up from the services as it is returned to the Company’s facilities or a third party site. Costs related to the treatment of waste include costs for waste receiving, drum movement and storage, waste consolidation and transportation between facilities. Deferred costs associated with parts washer services are amortized ratably over the average service interval, which ranges between seven and 14 weeks. Deferred costs related to treatment and disposal of waste are recognized when the corresponding waste is disposed of and are included in Deferred Costs within total current assets in the Company’s consolidated balance sheets. The deferred contract cost balances at the beginning of each period presented were fully recognized in cost of revenue in the subsequent three-month period.

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BUSINESS COMBINATIONS

6 Months Ended

Jun. 30, 2018

Business Combinations [Abstract]

BUSINESS COMBINATIONS

BUSINESS COMBINATIONS

2018 Acquisition

On February 23, 2018, the Company completed the acquisition of the U.S. Industrial Cleaning Business of Veolia Environmental Services North America LLC (the "Veolia Business"). The acquisition will provide significant scale and industrial services capabilities while increasing the size of the Company's existing U.S. Industrial Services business. The Company acquired the Veolia Business for a purchase price of $120.0 million subject to certain post-closing adjustments. The acquisition was financed with cash on hand. The amount of revenue from the Veolia Business included in the Company's results of operations for the three and six months ended June 30, 2018 was $46.3 million and $63.9 million, respectively. The amount of pre-tax income for the three and six months ended June 30, 2018 was $2.1 million and $3.3 million, respectively. During the three and six months ended June 30, 2018, the Company incurred acquisition-related costs of approximately $0.4 million and $0.9 million, respectively, in connection with the transaction which are included in selling, general and administrative expenses in the consolidated statements of operations.

The allocation of the purchase price was based on preliminary estimates of the fair value of assets acquired and liabilities assumed as of February 23, 2018, as the Company is continuing to obtain information to complete its valuation of these accounts and the associated tax accounting. The components and preliminary allocation of the purchase price consist of the following amounts (in thousands):

	At Acquisition Date			Measurement Period Adjustments			At Acquisition Date As Reported June 30, 2018
Accounts receivable, including unbilled receivables	$	40,773		$	(2,691	)	$	38,082
Inventories and supplies	1,442			(316		)	1,126
Prepaid expenses and other current assets	1,005			(80		)	925
Property, plant and equipment	72,244			—			72,244
Permits and other intangibles	5,140			—			5,140
Current liabilities	(15,908		)	(2,631		)	(18,539		)
Closure and post-closure liabilities	(604		)	—			(604		)
Total identifiable net assets	104,092			(5,718		)	98,374
Goodwill	15,908			5,718			21,626
Total purchase price	$	120,000		$	—		$	120,000

The weighted average amortization period for the intangibles acquired is 8.2 years. The excess of the total purchase price, which includes the aggregate cash consideration paid in excess of the fair value of the tangible net assets and intangible assets acquired, was recorded as goodwill. The goodwill recognized is attributable to the expected operating synergies and growth potential that the Company expects to realize from this acquisition. Goodwill generated from the acquisition is deductible for tax purposes.

Pro forma revenue and earnings amounts on a combined basis as if this acquisition had been completed on January 1, 2017 are immaterial to the consolidated financial statements of the Company since that date.

2017 Acquisitions

On July 14, 2017, the Company acquired Lonestar West Inc. ("Lonestar"), a public company headquartered in Alberta, Canada, for approximately CAD $41.8 million, ($33.1 million USD), net of cash acquired, which included an equity payout of CAD $0.72 per share to Lonestar shareholders and the assumption of approximately CAD $21.3 million ($16.8 million USD) in outstanding debt, which Clean Harbors subsequently repaid. The acquisition supports the Company's growth in the daylighting and hydro excavation services markets. In addition to increasing the size of the Company's hydro vac fleet, Lonestar's network of locations provides the Company with direct access to key geographic markets in both the United States and Canada. The acquired company is included in the Environmental Services segment. In connection with this acquisition, a goodwill amount of $2.8 million was recognized.

On January 31, 2017, the Company acquired a privately held company for a purchase price of approximately $11.9 million in cash, net of cash acquired. The acquired business produces and distributes oil products and therefore complements the Company's closed loop model as it relates to the sale of its oil products. The acquired company is included in the Safety-Kleen segment. In connection with this acquisition, a goodwill amount of $5.0 million was recognized.

Pro forma revenue and earnings amounts on a combined basis as if these acquisitions had been completed on January 1, 2017 are immaterial to the consolidated financial statements of the Company since that date.

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DISPOSITION OF BUSINESS

6 Months Ended

Jun. 30, 2018

Discontinued Operations and Disposal Groups [Abstract]

DISPOSITION OF BUSINESS

DISPOSITION OF BUSINESS

On June 30, 2017, the Company completed the sale of its Transformer Services business, as part of its continuous focus on improving or divesting certain non-core operations. The sale price was $45.5 million. The Transformer Services business was a non-core business previously included within the legacy Technical Services operating segment.

The following table presents income attributable to the Transformer Services business included in the Company's consolidated results of operations for the three and six months ended June 30, 2017 (in thousands):

	Three Months Ended		Six Months Ended
	June 30, 2017		June 30, 2017
Income before provision for income taxes	$	1,873	$	2,771

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INVENTORIES AND SUPPLIES

6 Months Ended

Jun. 30, 2018

Inventory Disclosure [Abstract]

INVENTORIES AND SUPPLIES

INVENTORIES AND SUPPLIES

Inventories and supplies consisted of the following (in thousands):

	June 30, 2018		December 31, 2017
Oil and oil products	$	68,125	$	58,142
Supplies and drums	100,118		94,242
Solvent and solutions	9,230		9,167
Modular camp accommodations	2,494		1,826
Other	13,577		12,635
Total inventories and supplies	$	193,544	$	176,012

As of June 30, 2018 and December 31, 2017, other inventories consisted primarily of parts washer components, cleaning fluids, absorbents and automotive fluids, such as windshield washer fluid and antifreeze. Supplies and drums consisted primarily of drums and containers as well as critical spare parts to support the Company's incinerator and re-refinery operations.

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PROPERTY, PLANT AND EQUIPMENT

6 Months Ended

Jun. 30, 2018

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment consisted of the following (in thousands):

	June 30, 2018		December 31, 2017
Land	$	123,984	$	121,658
Asset retirement costs (non-landfill)	14,780		14,593
Landfill assets	145,068		144,539
Buildings and improvements	429,880		414,384
Camp equipment	161,899		170,012
Vehicles	689,846		617,959
Equipment	1,675,920		1,644,102
Furniture and fixtures	5,623		5,708
Construction in progress	39,569		57,618
	3,286,569		3,190,573
Less - accumulated depreciation and amortization	1,677,187		1,603,208
Total property, plant and equipment, net	$	1,609,382	$	1,587,365

Interest in the amount of $0.1 million and $0.4 million was capitalized to property, plant and equipment during the three and six months ended June 30, 2018, respectively. Interest in the amount of $0.1 million and $0.2 million was capitalized to property, plant and equipment during the three and six months ended June 30, 2017, respectively. Depreciation expense, inclusive of landfill amortization, was $64.2 million and $129.8 million for the three and six months ended June 30, 2018, respectively. Depreciation expense, inclusive of landfill amortization, was $61.8 million and $125.2 million for the three and six months ended June 30, 2017, respectively.

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GOODWILL AND OTHER INTANGIBLE ASSETS

6 Months Ended

Jun. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

GOODWILL AND OTHER INTANGIBLE ASSETS

GOODWILL AND OTHER INTANGIBLE ASSETS

The changes in goodwill by segment for the six months ended June 30, 2018 were as follows (in thousands):

	Environmental Services			Safety-Kleen			Totals
Balance at January 1, 2018	$	172,386		$	306,137		$	478,523
Increase from current period acquisition	21,626			—			21,626
Measurement period adjustments from prior period acquisitions	(78		)	—			(78		)
Foreign currency translation	(1,305		)	(1,515		)	(2,820		)
Balance at June 30, 2018	$	192,629		$	304,622		$	497,251

The Company assesses goodwill for impairment on an annual basis as of December 31, or at an interim date when events or changes in the business environment would more likely than not reduce the fair value of a reporting unit below its carrying value.

As discussed in Note 18, “Segment Reporting,” during the first quarter of fiscal year 2018 and as a result of operational and managerial changes in several of the Company’s businesses, the identification of operating segments in accordance with ASC 280, Segment Information, was changed. As a result of the Company's conclusions around the identification of operating segments, the Company also concluded that, for purposes of reviewing for potential goodwill impairment, it now has four reporting units, consisting of Environmental Sales and Service, Environmental Facilities, Kleen Performance Products and Safety-Kleen Environmental Services. The Company allocated goodwill to the newly identified reporting units using a relative fair value approach. In addition, the Company completed an assessment of any potential goodwill impairment for all reporting units immediately prior and subsequent to the reallocation and determined that no impairment existed.

As of June 30, 2018 and December 31, 2017, the Company's total finite-lived and indefinite-lived intangible assets consisted of the following (in thousands):

	June 30, 2018						December 31, 2017
	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
Permits	$	175,317	$	76,707	$	98,610	$	174,721	$	74,347	$	100,374
Customer and supplier relationships	399,012		170,866		228,146		399,224		158,972		240,252
Other intangible assets	37,431		31,107		6,324		36,766		31,592		5,174
Total amortizable permits and other intangible assets	611,760		278,680		333,080		610,711		264,911		345,800
Indefinite lived trademarks and trade names	122,840		—		122,840		123,328		—		123,328
Total permits and other intangible assets	$	734,600	$	278,680	$	455,920	$	734,039	$	264,911	$	469,128

Amortization expense of permits and other intangible assets was $8.6 million and $17.8 million in the three and six months ended June 30, 2018, respectively. Amortization expense of permits and other intangible assets was $9.7 million and $18.8 million in the three and six months ended June 30, 2017, respectively.

The expected amortization of the net carrying amount of finite-lived intangible assets at June 30, 2018 was as follows (in thousands):

Years Ending December 31,	Expected Amortization
2018 (six months)	$	16,927
2019	32,143
2020	29,850
2021	27,381
2022	27,222
Thereafter	199,557
	$	333,080

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ACCRUED EXPENSES

6 Months Ended

Jun. 30, 2018

Payables and Accruals [Abstract]

ACCRUED EXPENSES

ACCRUED EXPENSES

Accrued expenses consisted of the following at June 30, 2018 and December 31, 2017 (in thousands):

	June 30, 2018		December 31, 2017
Insurance	$	68,701	$	57,889
Interest	12,693		12,660
Accrued compensation and benefits	56,073		55,861
Income, real estate, sales and other taxes	27,116		27,330
Other	35,552		34,242
	$	200,135	$	187,982

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CLOSURE AND POST-CLOSURE LIABILITIES

6 Months Ended

Jun. 30, 2018

Asset Retirement Obligation Disclosure [Abstract]

CLOSURE AND POST-CLOSURE LIABILITIES

CLOSURE AND POST-CLOSURE LIABILITIES

The changes to closure and post-closure liabilities (also referred to as “asset retirement obligations”) from January 1, 2018 through June 30, 2018 were as follows (in thousands):

	Landfill Retirement Liability			Non-Landfill Retirement Liability			Total
Balance at January 1, 2018	$	32,382		$	28,655		$	61,037
Liabilities assumed in acquisition	—			604			604
New asset retirement obligations	1,478			—			1,478
Accretion	1,284			1,245			2,529
Changes in estimates recorded to statement of operations	—			85			85
Changes in estimates recorded to balance sheet	430			—			430
Expenditures	(359		)	(88		)	(447		)
Currency translation and other	(127		)	(85		)	(212		)
Balance at June 30, 2018	$	35,088		$	30,416		$	65,504

All of the landfill facilities included in the above were active as of June 30, 2018. There were no significant charges (benefits) in 2018 resulting from changes in estimates for closure and post-closure liabilities.

New asset retirement obligations incurred during the first six months of 2018 were discounted at the credit-adjusted risk-free rate of 5.66%.

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REMEDIAL LIABILITIES

6 Months Ended

Jun. 30, 2018

Environmental Remediation Obligations [Abstract]

REMEDIAL LIABILITIES

REMEDIAL LIABILITIES

The changes to remedial liabilities for the six months ended June 30, 2018 were as follows (in thousands):

	Remedial Liabilities for Landfill Sites			Remedial Liabilities for Inactive Sites			Remedial Liabilities (Including Superfund) for Non-Landfill Operations			Total
Balance at January 1, 2018	$	1,800		$	65,342		$	57,326		$	124,468
Accretion	43			1,375			931			2,349
Changes in estimates recorded to statement of operations	—			83			(841		)	(758		)
Expenditures	(23		)	(1,939		)	(2,176		)	(4,138		)
Currency translation and other	—			882			(1,528		)	(646		)
Balance at June 30, 2018	$	1,820		$	65,743		$	53,712		$	121,275

In the six months ended June 30, 2018, there were no significant charges (benefits) resulting from changes in estimates for remedial liabilities.

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FINANCING ARRANGEMENTS

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

FINANCING ARRANGEMENTS

FINANCING ARRANGEMENTS

The following table is a summary of the Company’s financing arrangements (in thousands):

	June 30, 2018			December 31, 2017
Senior secured Term Loan Agreement ("Term Loan Agreement")	$	4,000		$	4,000
Current portion of long-term obligations, at carrying value	$	4,000		$	4,000
Senior secured Term Loan Agreement due June 30, 2024	$	392,000		$	394,000
Senior unsecured notes, at 5.25%, due August 1, 2020 ("2020 Notes")	400,000			400,000
Senior unsecured notes, at 5.125%, due June 1, 2021 ("2021 Notes")	845,000			845,000
Long-term obligations, at par	$	1,637,000		$	1,639,000
Unamortized debt issuance costs and premium, net	(12,273		)	(13,463		)
Long-term obligations, at carrying value	$	1,624,727		$	1,625,537
Total current and long-term obligations, at carrying value	$	1,628,727		$	1,629,537

On April 17, 2018, the Company, and substantially all of the Company's domestic subsidiaries as guarantors, entered into the first amendment (“First Amendment”) of the Term Loan Agreement. The First Amendment reduced the applicable interest rate margin for the Company’s initial term loans outstanding (the "Term Loans") under the Term Loan Agreement by 25 basis points for both Eurocurrency borrowings and base rate borrowings. After giving effect to the repricing, the applicable interest rate margin for the Term Loans are 1.75% for Eurocurrency borrowings and 0.75% for base rate borrowings.

On July 19, 2018, the Company, and substantially all of the Company’s domestic subsidiaries as guarantors, entered into an Incremental Facility Amendment (the “Incremental Facility Amendment”) to the Company’s existing Term Loan Agreement. The Incremental Facility Amendment increases the principal amount of the initial term loans (the “Initial Term Loans”) outstanding under the Term Loan Agreement by $350.0 million and, as a result of such increase, an aggregate of $746.0 million of principal was outstanding at July 19, 2018. Initial Term Loans under the Term Loan Agreement will mature on June 30, 2024 and may be prepaid at any time without premium or penalty other than customary breakage costs with respect to Eurodollar based loans or if the Company engages in certain repricing transactions before January 19, 2019, in which event a 1.0% prepayment premium would be due. The Company’s obligations under the Term Loan Agreement are guaranteed by all of the Company’s domestic restricted subsidiaries and secured by liens on substantially all of the assets of the Company and the guarantors.

Concurrently with the closing on July 19, 2018 of the Incremental Facility Amendment, the Company purchased $322.0 million aggregate principal of 2020 Notes. Total amount paid in purchasing the 2020 Notes was $330.9 including $7.9 million of accrued interest.

On August 1, 2018, the Company redeemed the remaining $78.0 million outstanding 2020 Notes. In connection with the redemption of the $78.0 million of 2020 Notes, the Company borrowed $50.0 million under the Company's revolving credit facility.

At June 30, 2018 and December 31, 2017, the fair value of the Term Loans was $394.5 million and $400.5 million, respectively, based on quoted market prices or other available market data. At June 30, 2018 and December 31, 2017, the fair value of the Company's 2020 Notes was $400.9 million and $404.6 million, respectively, based on quoted market prices for the instrument. At June 30, 2018 and December 31, 2017, the fair value of the Company's 2021 Notes was $848.6 million and $855.7 million, respectively, based on quoted market prices for the instrument. The fair values of the Term Loans, 2020 Notes and 2021 Notes are considered Level 2 measures according to the fair value hierarchy.

The Company also maintains a $400.0 million revolving credit facility under which the Company had no outstanding loan balances as of June 30, 2018 and December 31, 2017. At June 30, 2018, approximately $244.3 million was available to borrow and outstanding letters of credit were $132.4 million. At December 31, 2017, $217.8 million was available to borrow and outstanding letters of credit were $134.1 million.

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EARNINGS PER SHARE

6 Months Ended

Jun. 30, 2018

Earnings Per Share [Abstract]

EARNINGS PER SHARE

EARNINGS PER SHARE

The following are computations of basic and diluted earnings per share (in thousands except for per share amounts):

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2018		2017		2018		2017
Numerator for basic and diluted earnings per share:
Net income	$	30,747	$	25,880	$	18,116	$	4,487
Denominator:
Basic shares outstanding	56,410		57,190		56,304		57,226
Dilutive effect of equity-based compensation awards	95		146		95		123
Dilutive shares outstanding	56,505		57,336		56,399		57,349
Basic income per share:	$	0.55	$	0.45	$	0.32	$	0.08
Diluted income per share:	$	0.54	$	0.45	$	0.32	$	0.08

For the three months ended June 30, 2018 and June 30, 2017, the dilutive effect of all then outstanding restricted stock and performance awards is included in the EPS calculation above except for 146,159 and 142,503 of performance stock awards for which the performance criteria were not attained at that time and 136,155 and 14,699, respectively, of restricted stock awards which were antidilutive at that time.

For the six months ended  June 30, 2018 and June 30, 2017, the dilutive effect of all then outstanding restricted stock and performance awards is included in the EPS calculation above except for 146,159 and 142,503 of performance stock awards for which the performance criteria were not attained at that time and 130,932 and 21,013, respectively, of restricted stock awards which were antidilutive at that time.

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ACCUMULATED OTHER COMPREHENSIVE LOSS

6 Months Ended

Jun. 30, 2018

Equity [Abstract]

ACCUMULATED OTHER COMPREHENSIVE LOSS

ACCUMULATED OTHER COMPREHENSIVE LOSS

The changes in accumulated other comprehensive loss by component and related tax effects for the six months ended June 30, 2018 were as follows (in thousands):    

	Foreign Currency Translation			Unrealized Losses on Available-For-Sale Securities			Unfunded Pension Liability			Total
Balance at January 1, 2018	$	(170,575	)	$	(146	)	$	(1,686	)	$	(172,407	)
Other comprehensive loss before tax effects	(27,091		)	(118		)	—			(27,209		)
Tax effects	5,609			(88		)	—			5,521
Other comprehensive loss	$	(21,482	)	$	(206	)	$	—		$	(21,688	)
Balance at June 30, 2018	$	(192,057	)	$	(352	)	$	(1,686	)	$	(194,095	)

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STOCK-BASED COMPENSATION

6 Months Ended

Jun. 30, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION

Total stock-based compensation cost charged to selling, general and administrative expenses for the three and six months ended June 30, 2018 was $3.5 million and $6.6 million, respectively. Total stock-based compensation cost charged to selling, general and administrative expenses for the three and six months ended June 30, 2017 was $2.9 million and $5.2 million, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation was $0.7 million and $1.3 million for the three and six months ended June 30, 2018, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation was $0.8 million and $1.5 million for the three and six months ended June 30, 2017, respectively.

Restricted Stock Awards

The following information relates to restricted stock awards that have been granted to employees and directors under the Company's equity incentive plans (the "Plans"). The restricted stock awards are not transferable until vested and the restrictions generally lapse upon the achievement of continued employment over a three-to-five-year period or service as a director until the following annual meeting of shareholders. The fair value of each restricted stock grant is based on the closing price of the Company's common stock on the date of grant and is amortized to expense over its vesting period.

The following table summarizes information about restricted stock awards for the six months ended June 30, 2018:

Restricted Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2018	604,933		$	54.23
Granted	200,688		$	52.92
Vested	(152,283	)	$	54.65
Forfeited	(17,136	)	$	53.63
Balance at June 30, 2018	636,202		$	53.73

As of June 30, 2018, there was $27.1 million of total unrecognized compensation cost arising from restricted stock awards under the Company's Plans. This cost is expected to be recognized over a weighted average period of 2.7 years. The total fair value of restricted stock vested during the three and six months ended June 30, 2018 was $7.0 million and $8.3 million, respectively. The total fair value of restricted stock vested during the three and six months ended June 30, 2017 was $4.5 million and $6.0 million, respectively.

Performance Stock Awards

The following information relates to performance stock awards that have been granted to employees under the Company's Plans. Performance stock awards are subject to performance criteria established by the compensation committee of the Company's board of directors prior to or at the date of grant. The vesting of the performance stock awards is based on achieving such targets typically based on revenue, Adjusted EBITDA margin, Adjusted Free Cash Flow and Total Recordable Incident Rate. In addition, performance stock awards include continued service conditions. The fair value of each performance stock award is based on the closing price of the Company's common stock on the date of grant and is amortized to expense over the service period if achievement of performance measures is considered probable.

The following table summarizes information about performance stock awards for the six months ended June 30, 2018:

Performance Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2018	190,129		$	55.63
Vested	(8,696	)	$	54.26
Forfeited	(12,889	)	$	55.09
Balance at June 30, 2018	168,544		$	55.75

As of June 30, 2018, there was $1.3 million of total unrecognized compensation cost arising from unvested performance stock awards deemed probable of vesting under the Company's Plans. No performance awards vested during the three months ended June 30, 2018. The total fair value of performance awards vested during six months ended June 30, 2018 was $0.5 million. No performance awards vested during the three months ended June 30, 2017. The total fair value of performance awards vested during the six months ended June 30, 2017 was $1.4 million.

Common Stock Repurchases

On October 31, 2017, the Company's board of directors increased the size of the Company’s current share repurchase program from $300 million to $600 million. During the three and six months ended June 30, 2018, the Company repurchased and retired a total of 0.2 million shares and 0.5 million shares, respectively, of the Company's common stock for a total cost of $12.2 million and $26.5 million, respectively. During the three and six months ended June 30, 2017, the Company repurchased and retired a total of 0.1 million and 0.2 million, respectively, of the Company's common stock for a total cost of $5.5 million and $12.3 million, respectively. Through June 30, 2018, the Company has repurchased and retired a total of 5.3 million shares of the Company's common stock for a total cost of $275.3 million under this program. As of June 30, 2018, an additional $324.7 million remained available for repurchase of shares under the current authorized program.

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COMMITMENTS AND CONTINGENCIES

6 Months Ended

Jun. 30, 2018

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES

Legal and Administrative Proceedings

The Company and its subsidiaries are subject to legal proceedings and claims arising in the ordinary course of business. Actions filed against the Company arise from commercial and employment-related claims including alleged class actions related to sales practices and wage and hour claims. The plaintiffs in these actions may be seeking damages or injunctive relief or both. These actions are in various jurisdictions and stages of proceedings, and some are covered in part by insurance. In addition, the Company’s waste management services operations are regulated by federal, state, provincial and local laws enacted to regulate discharge of materials into the environment, remediation of contaminated soil and groundwater or otherwise protect the environment. This ongoing regulation results in the Company frequently becoming a party to legal or administrative proceedings involving all levels of governmental authorities and other interested parties. The issues involved in such proceedings generally relate to alleged violations of existing permits and licenses or alleged responsibility under federal or state Superfund laws to remediate contamination at properties owned either by the Company or by other parties (“third party sites”) to which either the Company or the prior owners of certain of the Company’s facilities shipped wastes.

At June 30, 2018 and December 31, 2017, the Company had recorded reserves of $21.6 million and $19.3 million, respectively, in the Company's financial statements for actual or probable liabilities related to the legal and administrative proceedings in which the Company was then involved, the principal of which are described below. At June 30, 2018 and December 31, 2017, the Company also believed that it was reasonably possible that the amount of these potential liabilities could be as much as $1.7 million and $1.8 million more, respectively. The Company periodically adjusts the aggregate amount of these reserves when actual or probable liabilities are paid or otherwise discharged, new claims arise, or additional relevant information about existing or probable claims becomes available. As of June 30, 2018 and December 31, 2017, the $21.6 million and $19.3 million, respectively, of reserves consisted of (i) $17.0 million and $17.9 million, respectively, related to pending legal or administrative proceedings, including Superfund liabilities, which were included in remedial liabilities on the consolidated balance sheets, and (ii) $4.6 million and $1.4 million, respectively, primarily related to federal, state and provincial enforcement actions, which were included in accrued expenses on the consolidated balance sheets.

As of June 30, 2018, the principal legal and administrative proceedings in which the Company was involved, or which had been terminated during 2018, were as follows:

Ville Mercier.    In September 2002, the Company acquired the stock of a subsidiary (the "Mercier Subsidiary") which owns a hazardous waste incinerator in Ville Mercier, Quebec (the "Mercier Facility"). The property adjacent to the Mercier Facility, which is also owned by the Mercier Subsidiary, is now contaminated as a result of actions dating back to 1968, when the Government of Quebec issued to a company unrelated to the Mercier Subsidiary two permits to dump organic liquids into lagoons on the property. In 1999, Ville Mercier and three neighboring municipalities filed separate legal proceedings against the Mercier Subsidiary and the Government of Quebec. In 2012, the municipalities amended their existing statement of claim to seek $2.9 million (CAD) in general damages and $10.0 million (CAD) in punitive damages, plus interest and costs, as well as injunctive relief. Both the Government of Quebec and the Company have filed summary judgment motions against the municipalities. The parties are currently attempting to negotiate a resolution and hearings on the motions have been delayed. In September 2007, the Quebec Minister of Sustainable Development, Environment and Parks issued a Notice pursuant to Section 115.1 of the Environment Quality Act, superseding Notices issued in 1992, which are the subject of the pending litigation. The more recent Notice notifies the Mercier Subsidiary that, if the Mercier Subsidiary does not take certain remedial measures at the site, the Minister intends to undertake those measures at the site and claim direct and indirect costs related to such measures. The Company has accrued for costs expected to be incurred relative to the resolution of this matter and believes this matter will not have future material effect on its financial position or results of operations.

Safety-Kleen Legal Proceedings. On December 28, 2012, the Company acquired Safety-Kleen, Inc. ("Safety-Kleen") and thereby became subject to the legal proceedings in which Safety-Kleen was a party on that date. In addition to certain Superfund proceedings in which Safety-Kleen has been named as a potentially responsible party as described below under “Superfund Proceedings,” the principal such legal proceedings involving Safety-Kleen which were outstanding as of June 30, 2018 were as follows:

Product Liability Cases. Safety-Kleen has been named as a defendant in various lawsuits that are currently pending in various courts and jurisdictions throughout the United States, including approximately 60 proceedings (excluding cases which have been settled but not formally dismissed) as of June 30, 2018, wherein persons claim personal injury resulting from the use of Safety-Kleen's parts cleaning equipment or cleaning products. These proceedings typically involve allegations that the solvent used in Safety-Kleen's parts cleaning equipment contains contaminants and/or that Safety-Kleen's recycling process does not effectively remove the contaminants that become entrained in the solvent during their use. In addition, certain claimants assert that Safety-Kleen failed to warn adequately the product user of potential risks, including a historic failure to warn that solvent contains trace amounts of toxic or hazardous substances such as benzene.

Safety-Kleen maintains insurance that it believes will provide coverage for these product liability claims (over amounts accrued for self-insured retentions and deductibles in certain limited cases), except for punitive damages to the extent not insurable under state law or excluded from insurance coverage. Safety-Kleen also believes that these claims lack merit and has historically vigorously defended, and intends to continue to vigorously defend, itself and the safety of its products against all of these claims. Such matters are subject to many uncertainties and outcomes are not predictable with assurance. Consequently, Safety-Kleen is unable to ascertain the ultimate aggregate amount of monetary liability or financial impact with respect to these matters as of June 30, 2018. From January 1, 2018 to June 30, 2018, three product liability claims were settled or dismissed. Due to the nature of these claims and the related insurance, the Company did not incur any expense as Safety-Kleen's insurance provided coverage in full for all such claims. Safety-Kleen may be named in similar, additional lawsuits in the future, including claims for which insurance coverage may not be available.    

Superfund Proceedings

The Company has been notified that either the Company (which, since December 28, 2012, includes Safety-Kleen) or the prior owners of certain of the Company's facilities for which the Company may have indemnification obligations have been identified as potentially responsible parties ("PRPs") or potential PRPs in connection with 127 sites which are subject to or are proposed to become subject to proceedings under federal or state Superfund laws. Of the 127 sites, three (including the BR Facility described below) involve facilities that are now owned or leased by the Company and 124 involve third party sites to which either the Company or the prior owners of certain of the Company’s facilities shipped wastes. Of the 124 third party sites, 34 are now settled, 17 are currently requiring expenditures on remediation and 73 are not currently requiring expenditures on remediation.

In connection with each site, the Company has estimated the extent, if any, to which it may be subject, either directly or as a result of any indemnification obligations, for cleanup and remediation costs, related legal and consulting costs associated with PRP investigations, settlements, and related legal and administrative proceedings. The amount of such actual and potential liability is inherently difficult to estimate because of, among other relevant factors, uncertainties as to the legal liability (if any) of the Company or the prior owners of certain of the Company's facilities to contribute a portion of the cleanup costs, the assumptions that must be made in calculating the estimated cost and timing of remediation, the identification of other PRPs and their respective capability and obligation to contribute to remediation efforts, and the existence and legal standing of indemnification agreements (if any) with prior owners, which may either benefit the Company or subject the Company to potential indemnification obligations. The Company believes its potential liability could exceed $100,000 at 10 of the 124 third party sites.

BR Facility.    The Company acquired in 2002 a former hazardous waste incinerator and landfill in Baton Rouge (the "BR Facility"), for which operations had been previously discontinued by the prior owner. In September 2007, the Environmental Protection Agency (the "EPA") issued a special notice letter to the Company related to the Devil's Swamp Lake Site ("Devil's Swamp") in East Baton Rouge Parish, Louisiana. Devil's Swamp includes a lake located downstream of an outfall ditch where wastewater and storm water have been discharged, and Devil's Swamp is proposed to be included on the National Priorities List due to the presence of Contaminants of Concern ("COC") cited by the EPA. These COCs include substances of the kind found in wastewater and storm water discharged from the BR Facility in past operations. The EPA originally requested COC generators to submit a good faith offer to conduct a remedial investigation feasibility study directed towards the eventual remediation of the site. The Company is currently performing corrective actions at the BR Facility under an order issued by the Louisiana Department of Environmental Quality, and has begun conducting the remedial investigation and feasibility study under an order issued by the EPA. The Company cannot presently estimate the potential additional liability for the Devil's Swamp cleanup until a final remedy is selected by the EPA.

Third Party Sites.    Of the 124 third party sites at which the Company has been notified it is a PRP or potential PRP or may have indemnification obligations, Clean Harbors has an indemnification agreement at 11 of these sites with ChemWaste, a former subsidiary of Waste Management, Inc., and at six additional of these third party sites, Safety-Kleen has a similar indemnification agreement with McKesson Corporation. These agreements indemnify the Company (which now includes Safety-Kleen) with respect to any liability at the 17 sites for waste disposed prior to the Company's (or Safety-Kleen's) acquisition of the former subsidiaries of Waste Management and McKesson which had shipped wastes to those sites. Accordingly, Waste Management or McKesson are paying all costs of defending those subsidiaries in those 17 cases, including legal fees and settlement costs. However, there can be no guarantee that the Company's ultimate liabilities for those sites will not exceed the amount recorded or that indemnities applicable to any of these sites will be available to pay all or a portion of related costs. Except for the indemnification agreements which the Company holds from ChemWaste, McKesson and one other entity, the Company does not have an indemnity agreement with respect to any of the 124 third party sites discussed above.

Federal, State and Provincial Enforcement Actions

From time to time, the Company pays fines or penalties in regulatory proceedings relating primarily to waste treatment, storage or disposal facilities. As of June 30, 2018 and December 31, 2017, there were six and five, respectively, proceedings for which the Company reasonably believes that the sanctions could equal or exceed $100,000. The Company believes that the fines or other penalties in these or any of the other regulatory proceedings will, individually or in the aggregate, not have a material effect on its financial condition, results of operations or cash flows.

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INCOME TAXES

6 Months Ended

Jun. 30, 2018

Income Tax Disclosure [Abstract]

INCOME TAXES

INCOME TAXES

The Company records a tax provision or benefit on an interim basis using an estimated annual effective tax rate. This rate is applied to the current period ordinary income or loss to determine the income tax provision or benefit allocated to the interim period. Losses from jurisdictions for which no benefit can be recognized and the income tax effects of unusual or infrequent items are excluded from the estimated annual effective tax rate and are recognized in the impacted interim period. The estimated annual effective tax rate may be significantly impacted by projected earnings mix by tax jurisdiction. Adjustments to the estimated annual effective income tax rate are recognized in the period when such estimates are revised.

The Company’s effective tax rate for the three and six months ended June 30, 2018 was 30.8% and 48.0% compared to 47.3% and 85.2% for the same periods in 2017. The variations in the effective income tax rates for the six months ended June 30, 2018 and the three and six months ended June 30, 2017 as compared to more customary relationships between pre-tax income and the provision for income taxes were primarily due to not recognizing income tax benefits from current operating losses related to certain Canadian entities during these periods.

On December 22, 2017, the “Tax Cuts and Jobs Act” (the “Tax Act”) was signed into law, making significant changes to the federal tax law. Changes include, but are not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial tax system, and a one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017. The Company recognized its best estimate of the income tax effects of the 2017 Tax Act in the financial statements included in its 2017 Annual Report on Form 10-K in accordance with Staff Accounting Bulletin No. 118, which provides SEC staff guidance for the application of ASC Topic 740, Income Taxes, in the reporting period in which the 2017 Tax Act was signed into law. During the three and six months ended June 30, 2018, the Company did not recognize any changes to the provisional amounts recorded in its 2017 Annual Report on Form 10-K in connection with the 2017 Tax Act. The Company is continuing to evaluate the impact of the Tax Act on its business and the consolidated financial statements and will make any adjustments to its provisional amounts in subsequent reporting periods upon obtaining, preparing or analyzing additional information affecting the income tax effects initially reported as a provisional amount. Any subsequent adjustment to these amounts will be recorded to tax expense in the quarter of 2018 when the analysis is completed.

As of June 30, 2018 and December 31, 2017, the Company had recorded $5.0 million and $5.1 million, respectively, of liabilities for unrecognized tax benefits and $1.0 million and $0.9 million of interest, respectively.

Due to expiring statute of limitation periods, the Company believes that total unrecognized tax benefits will decrease by $1.4 million within the next 12 months.

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SEGMENT REPORTING

6 Months Ended

Jun. 30, 2018

Segment Reporting [Abstract]

SEGMENT REPORTING

SEGMENT REPORTING

Segment reporting is prepared on the same basis that the Company's chief executive officer, who is the Company's chief operating decision maker, manages the business, makes operating decisions and assesses performance. During the first quarter of fiscal year 2018, certain of the Company's businesses undertook a reorganization which included changes to the underlying business and management structures. The reorganization resulted in combining the Environmental Services businesses from an operational and management perspective and is expected to deepen customer relationships and allow for efficiencies across the Company's operations through the sharing of resources, namely labor and equipment which will reduce third party spend and promote the cross selling of such business offerings. In connection with this reorganization, the Company’s chief operating decision maker also requested changes in the information that he regularly reviews for purposes of allocating resources and assessing performance. These changes required a reconsideration of the Company’s operating segments in the first quarter of 2018 and resulted in a change in the Company’s assessment of its operating segments. Upon reconsideration of the identification of the Company’s operating segments, the Company concluded that there are now two operating segments for disclosure in accordance with ASC 280 Segment reporting; (i) the Environmental Services segment which consists of the Company’s historical Technical Services, Industrial Services, Field Services and Oil, Gas and Lodging businesses and (ii) the Safety-Kleen segment.

Third-party revenue is revenue billed to outside customers by a particular segment. Direct revenue is revenue allocated to the segment providing the product or service. Intersegment revenues represent the sharing of third-party revenues among the segments based on products and services provided by each segment as if the products and services were sold directly to the third-party. The intersegment revenues are shown net. The negative intersegment revenues are due to more transfers out of customer revenues to other segments than transfers in of customer revenues from other segments. The operations not managed through the Company’s operating segments described above are recorded as “Corporate Items.” Corporate Items revenues consist of two different operations for which the revenues are insignificant. Corporate Items cost of revenues represents certain central services that are not allocated to the Company's operating segments for internal reporting purposes. Corporate Items selling, general and administrative expenses include typical corporate items such as legal, accounting and other items of a general corporate nature that are not allocated to the Company’s operating segments.  

The following table reconciles third party revenues to direct revenues for the three and six months ended June 30, 2018 and 2017 (in thousands):

	For the Three Months Ended June 30, 2018											For the Three Months Ended June 30, 2017
	Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Environmental Services	$	519,916	$	34,291		$	607		$	554,814		$	449,631	$	31,639		$	320		$	481,590
Safety-Kleen	328,715		(34,291		)	11			294,435			302,956		(31,639		)	(2		)	271,315
Corporate Items	509		—			(618		)	(109		)	201		—			(318		)	(117		)
Total	$	849,140	$	—		$	—		$	849,140		$	752,788	$	—		$	—		$	752,788

	For the Six Months Ended June 30, 2018											For the Six Months Ended June 30, 2017
	Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Environmental Services	$	959,604	$	66,256		$	1,401		$	1,027,261		$	845,538	$	63,708		$	1,240		$	910,486
Safety-Kleen	638,633		(66,256		)	22			572,399			595,857		(63,708		)	1			532,150
Corporate Items	681		—			(1,423		)	(742		)	334		—			(1,241		)	(907		)
Total	$	1,598,918	$	—		$	—		$	1,598,918		$	1,441,729	$	—		$	—		$	1,441,729

The primary financial measure by which the Company evaluates the performance of its segments is "Adjusted EBITDA" which consists of net income plus accretion of environmental liabilities, depreciation and amortization, interest expense, net, loss on early extinguishment of debt, provision for income taxes and excludes gain on sale of business and other income (expense), net. Transactions between the segments are accounted for at the Company’s best estimate based on similar transactions with outside customers.

The following table presents Adjusted EBITDA information used by management by reported segment (in thousands):

	For the Three Months Ended						For the Six Months Ended
	June 30,						June 30,
	2018			2017			2018			2017
Adjusted EBITDA:
Environmental Services	$	109,199		$	94,832		$	170,616		$	155,022
Safety-Kleen	73,069			60,281			134,953			112,649
Corporate Items	(42,707		)	(34,422		)	(77,743		)	(66,845		)
Total	$	139,561		$	120,691		$	227,826		$	200,826
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	2,448			2,416			4,878			4,706
Depreciation and amortization	72,760			71,531			147,604			143,943
Income from operations	64,353			46,744			75,344			52,177
Other (income) expense, net	(846		)	833			(547		)	2,382
Loss on early extinguishment of debt	—			6,045			—			6,045
Gain on sale of business	—			(31,722		)	—			(31,722		)
Interest expense, net of interest income	20,769			22,492			41,039			45,068
Income before provision for income taxes	$	44,430		$	49,096		$	34,852		$	30,404

The following table presents certain assets by reportable segment and in the aggregate (in thousands):

	June 30, 2018
	Environmental Services		Safety-Kleen		Corporate Items		Totals
Property, plant and equipment, net	$	988,957	$	555,124	$	65,301	$	1,609,382
Goodwill	192,629		304,622		—		497,251
Permits and other intangibles, net	96,165		359,755		—		455,920
Total assets	$	1,681,627	$	1,436,014	$	597,820	$	3,715,461

	December 31, 2017
	Environmental Services		Safety-Kleen		Corporate Items		Totals
Property, plant and equipment, net	$	927,139	$	582,162	$	78,064	$	1,587,365
Goodwill	172,386		306,137		—		478,523
Permits and other intangibles, net	97,519		371,609		—		469,128
Total assets	$	1,541,241	$	1,471,291	$	694,038	$	3,706,570

The following table presents total assets by geographical area (in thousands):

	June 30, 2018		December 31, 2017
United States	$	3,041,509	$	2,985,394
Canada	673,836		721,176
Other foreign	116		—
Total	$	3,715,461	$	3,706,570

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GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION

6 Months Ended

Jun. 30, 2018

Guarantor and Non-Guarantor Subsidiaries Financial Information [Abstract]

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION

The 2020 Notes and the 2021 Notes (collectively, the "Senior Unsecured Notes") and the Company's obligations under its Term Loan Agreement are guaranteed by substantially all of the Company’s subsidiaries organized in the United States. Each guarantor is a 100% owned subsidiary of Clean Harbors, Inc. and its guarantee is both full and unconditional and joint and several. The guarantees are, however, subject to customary release provisions under which, in particular, the guarantee of any domestic restricted subsidiary will be released if the Company sells such subsidiary to an unrelated third party in accordance with the terms of the indentures which govern the Senior Unsecured Notes and of the Term Loan Agreement. The Senior Unsecured Notes and the Company's obligations under its Term Loan Agreement are not guaranteed by the Company’s subsidiaries organized outside the United States. The following supplemental condensed consolidating financial information for the parent company, the guarantor subsidiaries and the non-guarantor subsidiaries, respectively, is presented in conformity with the requirements of Rule 3-10 of SEC Regulation S-X (“Rule 3-10”).

Following is the condensed consolidating balance sheet at June 30, 2018 (in thousands):

	Clean Harbors, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Consolidating Adjustments			Total
Assets:
Cash and cash equivalents	$	51,960	$	92,833	$	52,275	$	—		$	197,068
Short-term marketable securities	—		—		36,862		—			36,862
Intercompany receivables	250,206		651,218		61,125		(962,549		)	—
Accounts receivable, net	—		497,775		92,805		—			590,580
Other current assets	—		260,489		60,225		(8,742		)	311,972
Property, plant and equipment, net	—		1,243,171		366,211		—			1,609,382
Investments in subsidiaries	3,135,271		599,091		—		(3,734,362		)	—
Intercompany debt receivable	—		15,224		21,000		(36,224		)	—
Goodwill	—		437,229		60,022		—			497,251
Permits and other intangibles, net	—		402,096		53,824		—			455,920
Other long-term assets	2,283		12,337		1,811		(5		)	16,426
Total assets	$	3,439,720	$	4,211,463	$	806,160	$	(4,741,882	)	$	3,715,461
Liabilities and Stockholders’ Equity:
Current liabilities	$	16,627	$	406,111	$	129,672	$	(8,742	)	$	543,668
Intercompany payables	637,318		309,423		15,808		(962,549		)	—
Closure, post-closure and remedial liabilities, net	—		146,922		16,850		—			163,772
Long-term obligations, net	1,624,727		—		—		—			1,624,727
Intercompany debt payable	—		21,000		15,224		(36,224		)	—
Other long-term liabilities	—		200,999		21,252		(5		)	222,246
Total liabilities	2,278,672		1,084,455		198,806		(1,007,520		)	2,554,413
Stockholders’ equity	1,161,048		3,127,008		607,354		(3,734,362		)	1,161,048
Total liabilities and stockholders’ equity	$	3,439,720	$	4,211,463	$	806,160	$	(4,741,882	)	$	3,715,461

Following is the condensed consolidating balance sheet at December 31, 2017 (in thousands):

	Clean Harbors, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Consolidating Adjustments			Total
Assets:
Cash and cash equivalents	$	51,638	$	207,777	$	59,984	$	—		$	319,399
Short-term marketable securities	—		—		38,179		—			38,179
Intercompany receivables	238,339		590,100		52,909		(881,348		)	—
Accounts receivable, net	—		433,042		95,882		—			528,924
Other current assets	897		233,602		52,947		(19,892		)	267,554
Property, plant and equipment, net	—		1,174,975		412,390		—			1,587,365
Investments in subsidiaries	3,112,547		569,568		—		(3,682,115		)	—
Intercompany debt receivable	—		92,530		21,000		(113,530		)	—
Goodwill	—		415,641		62,882		—			478,523
Permits and other intangibles, net	—		408,655		60,473		—			469,128
Other long-term assets	2,084		12,064		3,350		—			17,498
Total assets	$	3,405,505	$	4,137,954	$	859,996	$	(4,696,885	)	$	3,706,570
Liabilities and Stockholders’ Equity:
Current liabilities	$	16,954	$	371,135	$	135,620	$	(19,892	)	$	503,817
Intercompany payables	574,812		289,531		17,005		(881,348		)	—
Closure, post-closure and remedial liabilities, net	—		148,872		16,851		—			165,723
Long-term obligations, net	1,625,537		—		—		—			1,625,537
Intercompany debt payable	—		21,000		92,530		(113,530		)	—
Other long-term liabilities	—		201,086		22,205		—			223,291
Total liabilities	2,217,303		1,031,624		284,211		(1,014,770		)	2,518,368
Stockholders’ equity	1,188,202		3,106,330		575,785		(3,682,115		)	1,188,202
Total liabilities and stockholders’ equity	$	3,405,505	$	4,137,954	$	859,996	$	(4,696,885	)	$	3,706,570

Following is the consolidating statement of operations for the three months ended June 30, 2018 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	544,521		$	165,435		$	(13,177	)	$	696,779
Product revenues	—			137,891			17,363			(2,893		)	152,361
Total revenues	—			682,412			182,798			(16,070		)	849,140
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			361,644			124,956			(13,177		)	473,423
Product cost of revenues	—			102,442			10,612			(2,893		)	110,161
Total cost of revenues	—			464,086			135,568			(16,070		)	583,584
Selling, general and administrative expenses	133			105,022			20,840			—			125,995
Accretion of environmental liabilities	—			2,194			254			—			2,448
Depreciation and amortization	—			52,864			19,896			—			72,760
(Loss) income from operations	(133		)	58,246			6,240			—			64,353
Other income, net	—			269			577			—			846
Interest (expense) income, net	(21,216		)	238			209			—			(20,769		)
Equity in earnings of subsidiaries, net of taxes	46,118			2,230			—			(48,348		)	—
Intercompany interest income (expense)	—			1,084			(1,084		)	—			—
Income before (benefit) provision for income taxes	24,769			62,067			5,942			(48,348		)	44,430
(Benefit) provision for income taxes	(5,978		)	18,228			1,433			—			13,683
Net income	30,747			43,839			4,509			(48,348		)	30,747
Other comprehensive loss	(4,942		)	(4,942		)	(10,435		)	15,377			(4,942		)
Comprehensive income (loss)	$	25,805		$	38,897		$	(5,926	)	$	(32,971	)	$	25,805

Following is the consolidating statement of operations for the three months ended June 30, 2017 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	474,801		$	147,924		$	(11,785	)	$	610,940
Product revenues	—			125,859			18,730			(2,741		)	141,848
Total revenues	—			600,660			166,654			(14,526		)	752,788
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			306,960			117,181			(11,785		)	412,356
Product cost of revenues	—			98,645			11,543			(2,741		)	107,447
Total cost of revenues	—			405,605			128,724			(14,526		)	519,803
Selling, general and administrative expenses	27			92,504			19,763			—			112,294
Accretion of environmental liabilities	—			2,181			235			—			2,416
Depreciation and amortization	—			51,937			19,594			—			71,531
(Loss) income from operations	(27		)	48,433			(1,662		)	—			46,744
Other expense, net	(76		)	(406		)	(351		)	—			(833		)
Loss on early extinguishment of debt	(6,045		)	—			—			—			(6,045		)
Gain on sale of business	—			31,722			—			—			31,722
Interest (expense) income, net	(22,614		)	240			(118		)	—			(22,492		)
Equity in earnings of subsidiaries, net of taxes	43,167			(5,332		)	—			(37,835		)	—
Intercompany interest income (expense)	—			1,268			(1,268		)	—			—
Income (loss) before (benefit) provision for income taxes	14,405			75,925			(3,399		)	(37,835		)	49,096
(Benefit) provision for income taxes	(11,475		)	31,981			2,710			—			23,216
Net income (loss)	25,880			43,944			(6,109		)	(37,835		)	25,880
Other comprehensive income	15,098			15,098			12,837			(27,935		)	15,098
Comprehensive income	$	40,978		$	59,042		$	6,728		$	(65,770	)	$	40,978

Following is the consolidating statement of operations for the six months ended June 30, 2018 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	1,026,004		$	317,836		$	(27,342	)	$	1,316,498
Product revenues	—			259,473			28,813			(5,866		)	282,420
Total revenues	—			1,285,477			346,649			(33,208		)	1,598,918
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			689,824			258,590			(27,342		)	921,072
Product cost of revenues	—			197,480			17,323			(5,866		)	208,937
Total cost of revenues	—			887,304			275,913			(33,208		)	1,130,009
Selling, general and administrative expenses	168			198,865			42,050			—			241,083
Accretion of environmental liabilities	—			4,370			508			—			4,878
Depreciation and amortization	—			106,568			41,036			—			147,604
(Loss) income from operations	(168		)	88,370			(12,858		)	—			75,344
Other income, net	—			184			363			—			547
Interest (expense) income, net	(42,215		)	743			433			—			(41,039		)
Equity in earnings of subsidiaries, net of taxes	48,632			(17,832		)	—			(30,800		)	—
Intercompany interest income (expense)	—			2,445			(2,445		)	—			—
Income (loss) before (benefit) provision for income taxes	6,249			73,910			(14,507		)	(30,800		)	34,852
(Benefit) provision for income taxes	(11,867		)	27,329			1,274			—			16,736
Net income (loss)	18,116			46,581			(15,781		)	(30,800		)	18,116
Other comprehensive loss	(21,688		)	(21,688		)	(24,442		)	46,130			(21,688		)
Comprehensive (loss) income	$	(3,572	)	$	24,893		$	(40,223	)	$	15,330		$	(3,572	)

Following is the consolidating statement of operations for the six months ended June 30, 2017 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	918,106		$	278,995		$	(25,947	)	$	1,171,154
Product revenues	—			242,509			34,061			(5,995		)	270,575
Total revenues	—			1,160,615			313,056			(31,942		)	1,441,729
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			601,105			228,285			(25,947		)	803,443
Product cost of revenues	—			195,150			23,790			(5,995		)	212,945
Total cost of revenues	—			796,255			252,075			(31,942		)	1,016,388
Selling, general and administrative expenses	51			184,675			39,789			—			224,515
Accretion of environmental liabilities	—			4,236			470			—			4,706
Depreciation and amortization	—			103,837			40,106			—			143,943
(Loss) income from operations	(51		)	71,612			(19,384		)	—			52,177
Other expense, net	(222		)	(1,795		)	(365		)	—			(2,382		)
Loss on early extinguishment of debt	(6,045		)	—			—			—			(6,045		)
Gain on sale of business	—			31,722			—			—			31,722
Interest (expense) income, net	(45,273		)	359			(154		)	—			(45,068		)
Equity in earnings of subsidiaries, net of taxes	35,530			(27,156		)	—			(8,374		)	—
Intercompany interest income (expense)	—			2,565			(2,565		)	—			—
(Loss) income before (benefit) provision for income taxes	(16,061		)	77,307			(22,468		)	(8,374		)	30,404
(Benefit) provision for income taxes	(20,548		)	41,618			4,847			—			25,917
Net income (loss)	4,487			35,689			(27,315		)	(8,374		)	4,487
Other comprehensive income	21,149			21,149			17,869			(39,018		)	21,149
Comprehensive income (loss)	$	25,636		$	56,838		$	(9,446	)	$	(47,392	)	$	25,636

Following is the condensed consolidating statement of cash flows for the six months ended June 30, 2018 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Net cash from operating activities	$	790		$	121,021		$	7,859		$	—		$	129,670
Cash flows used in investing activities:
Additions to property, plant and equipment	—			(77,773		)	(16,366		)	—			(94,139		)
Proceeds from sale and disposal of fixed assets	—			1,035			1,606			—			2,641
Acquisitions, net of cash acquired	—			(123,750		)	—			—			(123,750		)
Additions to intangible assets, including costs to obtain or renew permits	—			(1,991		)	(115		)	—			(2,106		)
Proceeds from sale of available-for-sale securities	—			—			11,214			—			11,214
Purchases of available-for-sale securities	—			—			(10,001		)	—			(10,001		)
Intercompany	—			(30,657		)	—			30,657			—
Net cash used in investing activities	—			(233,136		)	(13,662		)	30,657			(216,141		)
Cash flows (used in) from financing activities:
Change in uncashed checks	—			(2,829		)	26			—			(2,803		)
Tax payments related to withholdings on vested restricted stock	(2,175		)	—			—			—			(2,175		)
Repurchases of common stock	(26,482		)	—			—			—			(26,482		)
Deferred financing costs paid	(468		)	—			—			—			(468		)
Principal payment on debt	(2,000		)	—			—			—			(2,000		)
Intercompany	30,657			—			—			(30,657		)	—
Net cash (used) from in financing activities	(468		)	(2,829		)	26			(30,657		)	(33,928		)
Effect of exchange rate change on cash	—			—			(1,932		)	—			(1,932		)
Increase (decrease) in cash and cash equivalents	322			(114,944		)	(7,709		)	—			(122,331		)
Cash and cash equivalents, beginning of period	51,638			207,777			59,984			—			319,399
Cash and cash equivalents, end of period	$	51,960		$	92,833		$	52,275		$	—		$	197,068

Following is the condensed consolidating statement of cash flows for the six months ended June 30, 2017 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Net cash (used in) from operating activities	$	(93,808	)	$	206,496		$	4,243		$	—		$	116,931
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	—			(75,152		)	(13,590		)	—			(88,742		)
Proceeds from sale and disposal of fixed assets	—			984			1,137			—			2,121
Acquisitions, net of cash acquired	—			(9,277		)	—			—			(9,277		)
Proceeds from sale of businesses, net of transactional costs	—			46,210			181			—			46,391
Additions to intangible assets, including costs to obtain or renew permits	—			(888		)	(351		)	—			(1,239		)
Proceeds from sale of available-for-sale securities	376			—			—			—			376
Intercompany	—			(14,343		)	—			14,343			—
Net cash from (used in) investing activities	376			(52,466		)	(12,623		)	14,343			(50,370		)
Cash flows from (used in) financing activities:
Change in uncashed checks	—			(5,977		)	(2,384		)	—			(8,361		)
Proceeds from exercise of stock options	46			—			—			—			46
Tax payments related to withholdings on vested restricted stock	(2,132		)	—			—			—			(2,132		)
Repurchases of common stock	(12,257		)	—			—			—			(12,257		)
Deferred financing costs paid	(4,727		)	—			—			—			(4,727		)
Premium paid on early extinguishment of debt	(4,665		)	—			—			—			(4,665		)
Principal payment on debt	(296,202		)	—			—			—			(296,202		)
Issuance of senior secured notes, net of discount	399,000			—			—			—			399,000
Intercompany	14,343			—			—			(14,343		)	—
Net cash from (used) in financing activities	93,406			(5,977		)	(2,384		)	(14,343		)	70,702
Effect of exchange rate change on cash	—			—			2,106			—			2,106
(Decrease) increase in cash and cash equivalents	(26		)	148,053			(8,658		)	—			139,369
Cash and cash equivalents, beginning of period	51,417			155,943			99,637			—			306,997
Cash and cash equivalents, end of period	$	51,391		$	303,996		$	90,979		$	—		$	446,366

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SIGNIFICANT ACCOUNTING POLICIES (Policies)

6 Months Ended

Jun. 30, 2018

Accounting Policies [Abstract]

Reclassifications

Reclassifications

During the first quarter of fiscal year 2018, certain of the Company's businesses undertook a reorganization which included changes to the underlying business and management structures. The reorganization resulted in combining the Environmental Services businesses from an operational and management perspective and is expected to deepen customer relationships and allow for efficiencies across the Company's operations through the sharing of resources, namely labor and equipment which will reduce third party spend and promote the cross selling of such business offerings. In connection with this reorganization, the Company’s chief operating decision maker also requested changes in the information that he regularly reviews for purposes of allocating resources and assessing performance. These changes required a reconsideration of the Company’s operating segments in the first quarter of 2018 and resulted in a change in the Company’s assessment of its operating segments. Upon reconsideration of the identification of the Company’s operating segments, the Company concluded that there are now two operating segments for disclosure in accordance with ASC 280 Segment reporting; (i) the Environmental Services segment which consists of the Company’s historical Technical Services, Industrial Services, Field Services and Oil, Gas and Lodging businesses and (ii) the Safety-Kleen segment. See Note 18, "Segment Reporting," for more information. The amounts presented for the three and six months ended June 30, 2017 have been recast to reflect the impact of such changes. These reclassifications and adjustments had no effect on the consolidated statements of operations, consolidated statements of comprehensive loss, consolidated statements of cash flows or consolidated statements of stockholders' equity for any of the periods presented.

Recent Accounting Pronouncements

Recent Accounting Pronouncements

Standards implemented

In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606), which replaces numerous requirements in U.S. GAAP, including industry-specific requirements, and provides companies with a single revenue recognition model for recognizing revenue from contracts with customers. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the modified retrospective method). On January 1, 2018, the Company adopted Topic 606 using the modified retrospective method for all contracts. Results for reporting periods beginning on the date of adoption are presented under ASC 606, while prior period amounts have not been adjusted and continue to be reported in accordance with the Company's historical accounting methodology pursuant to ASC 605, Revenue Recognition (“ASC 605”). Upon adoption, a cumulative effect adjustment was not required as the majority of the Company’s contracts are recognized based on time and materials incurred and were not impacted by the new guidance. The Company has concluded that the most significant impact of the standard relates to the incremental disclosures required.

In October 2016, the FASB issued ASU 2016-16, Income Tax - Intra-Entity Transfers of Assets Other than Inventory. The amendment improves the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The Company adopted the amendment on a modified retrospective basis effective January 1, 2018. As a result of adoption, the Company recorded a cumulative effect adjustment that reduced retained earnings by $1.6 million.

In March 2017, the FASB issued ASU 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendment requires an employer to report the service cost component of net benefit cost in the same line item as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. In addition, the amendment allows only the service cost component to be eligible for capitalization when applicable. The Company adopted the amendment in the first quarter of 2018. Adoption did not have a material impact on the Company's consolidated financial statements.

Standards to be implemented

The Company is evaluating the impact that the below standards to be implemented will have on the Company's consolidated financial statements.

In February 2016, FASB issued ASU 2016-02, Leases (Topic 842). The amendment increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. In February 2018, FASB issued ASU 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842. The amendment clarifies that land easements are within the scope of the new leases standard (ASC 842) and introduces a new transition practical expedient allowing a company to not assess whether existing and expired land easements that were not previously accounted for as leases under current US GAAP (ASC 840) are or contain leases under ASC 842. In July 2018, FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases. The amendment provides improvements that clarify specific aspects of the guidance in ASU 2016-02. The Company will adopt the new standard beginning on January 1, 2019. A modified retrospective transition approach is required for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. While the Company is still continuing to assess the effect of adoption, it expects that the new standard will have a material effect on its consolidated balance sheet related to the recognition of new assets and lease liabilities. In preparation for the adoption of the guidance, the Company is in the process of implementing new software and assessing changes to controls and processes to enable the preparation of financial information.

In June 2016, FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendment changes the way entities recognize impairment of many financial assets, including accounts receivable and investments in debt securities, by requiring immediate recognition of estimated credit losses expected to occur over their remaining lives. The amendment should be applied using a modified-retrospective approach and is effective for the Company for annual and interim reporting periods beginning after January 1, 2020, with early adoption permitted. The Company is currently evaluating the impact ASU 2016-13 will have on its consolidated financial statements.

In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendment better aligns an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The amendment is effective for the Company for annual and interim reporting periods beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the impact ASU 2017-12 will have on its consolidated financial statements.

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REVENUES (Tables)

6 Months Ended

Jun. 30, 2018

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The following table presents the Company’s revenues disaggregated by revenue source (in thousands):

	For the Three Months Ended June 30, 2018
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	408,127	$	306,059	$	363	$	714,549
Canada	111,789		22,656		146		134,591
	519,916		328,715		509		849,140
Sources of Revenue (1)
Technical Services	257,006		—		—		$	257,006
Field and Emergency Response Services	76,092		—		—		76,092
Industrial Services	161,046		—		—		161,046
Oil, Gas and Lodging Services and Other	25,772		—		509		26,281
Safety-Kleen Environmental Services	—		200,034		—		200,034
Kleen Performance Products	—		128,681		—		128,681
Total third party revenues	$	519,916	$	328,715	$	509	$	849,140

	For the Three Months Ended June 30, 2017
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	343,323	$	280,617	$	155	$	624,095
Canada	106,308		22,339		46		128,693
	449,631		302,956		201		752,788
Sources of Revenue (1)
Technical Services	254,487		—		—		254,487
Field and Emergency Response Services	70,707		—		—		70,707
Industrial Services	99,733		—		—		99,733
Oil, Gas and Lodging Services and Other	24,704		—		201		24,905
Safety-Kleen Environmental Services	—		192,817		—		192,817
Kleen Performance Products	—		110,139		—		110,139
Total third party revenues	$	449,631	$	302,956	$	201	$	752,788

	For the Six Months Ended June 30, 2018
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	752,099	$	593,701	$	508	$	1,346,308
Canada	207,505		44,932		173		252,610
	959,604		638,633		681		1,598,918
Sources of Revenue (1)
Technical Services	493,312		—		—		493,312
Field and Emergency Response Services	146,027		—		—		146,027
Industrial Services	264,809		—		—		264,809
Oil, Gas and Lodging Services and Other	55,456		—		681		56,137
Safety-Kleen Environmental Services	—		394,195		—		394,195
Kleen Performance Products	—		244,438		—		244,438
Total third party revenues	$	959,604	$	638,633	$	681	$	1,598,918

	For the Six Months Ended June 30, 2017
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	657,106	$	552,688	$	288	$	1,210,082
Canada	188,432		43,169		46		231,647
	845,538		595,857		334		1,441,729
Sources of Revenue (1)
Technical Services	484,705		—		—		484,705
Field and Emergency Response Services	131,726		—		—		131,726
Industrial Services	174,801		—		—		174,801
Oil, Gas and Lodging Services and Other	54,306		—		334		54,640
Safety-Kleen Environmental Services	—		384,544		—		384,544
Kleen Performance Products	—		211,313		—		211,313
Total third party revenues	$	845,538	$	595,857	$	334	$	1,441,729

______________________

1. All revenue except Kleen Performance Products and product sales within Safety-Kleen Environmental Services, including allied products and direct blended oil sales, are recognized over time. Kleen Performance Products and Safety-Kleen Environmental Services product revenues are recognized at a point in time.

Contract Balances

Contract Balances

	June 30, 2018		December 31, 2017		June 30, 2017		December 31, 2016
Receivables	$	590,580	$	528,924	$	512,375	$	496,226
Contract Assets (Unbilled Receivables)	62,762		35,922		46,576		36,190
Contract Liabilities (Deferred Revenue)	68,705		67,822		72,089		64,397

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BUSINESS COMBINATIONS (Tables)

6 Months Ended

Jun. 30, 2018

Business Combinations [Abstract]

Schedule of Business Acquisitions, by Acquisition

The components and preliminary allocation of the purchase price consist of the following amounts (in thousands):

	At Acquisition Date			Measurement Period Adjustments			At Acquisition Date As Reported June 30, 2018
Accounts receivable, including unbilled receivables	$	40,773		$	(2,691	)	$	38,082
Inventories and supplies	1,442			(316		)	1,126
Prepaid expenses and other current assets	1,005			(80		)	925
Property, plant and equipment	72,244			—			72,244
Permits and other intangibles	5,140			—			5,140
Current liabilities	(15,908		)	(2,631		)	(18,539		)
Closure and post-closure liabilities	(604		)	—			(604		)
Total identifiable net assets	104,092			(5,718		)	98,374
Goodwill	15,908			5,718			21,626
Total purchase price	$	120,000		$	—		$	120,000

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DISPOSITION OF BUSINESS (Tables)

6 Months Ended

Jun. 30, 2018

Discontinued Operations and Disposal Groups [Abstract]

Disposition of Business

The following table presents income attributable to the Transformer Services business included in the Company's consolidated results of operations for the three and six months ended June 30, 2017 (in thousands):

	Three Months Ended		Six Months Ended
	June 30, 2017		June 30, 2017
Income before provision for income taxes	$	1,873	$	2,771

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INVENTORIES AND SUPPLIES (Tables)

6 Months Ended

Jun. 30, 2018

Inventory Disclosure [Abstract]

Schedule of Inventory

Inventories and supplies consisted of the following (in thousands):

	June 30, 2018		December 31, 2017
Oil and oil products	$	68,125	$	58,142
Supplies and drums	100,118		94,242
Solvent and solutions	9,230		9,167
Modular camp accommodations	2,494		1,826
Other	13,577		12,635
Total inventories and supplies	$	193,544	$	176,012

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PROPERTY, PLANT AND EQUIPMENT (Tables)

6 Months Ended

Jun. 30, 2018

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, plant and equipment consisted of the following (in thousands):

	June 30, 2018		December 31, 2017
Land	$	123,984	$	121,658
Asset retirement costs (non-landfill)	14,780		14,593
Landfill assets	145,068		144,539
Buildings and improvements	429,880		414,384
Camp equipment	161,899		170,012
Vehicles	689,846		617,959
Equipment	1,675,920		1,644,102
Furniture and fixtures	5,623		5,708
Construction in progress	39,569		57,618
	3,286,569		3,190,573
Less - accumulated depreciation and amortization	1,677,187		1,603,208
Total property, plant and equipment, net	$	1,609,382	$	1,587,365

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GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)

6 Months Ended

Jun. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of changes to goodwill

The changes in goodwill by segment for the six months ended June 30, 2018 were as follows (in thousands):

	Environmental Services			Safety-Kleen			Totals
Balance at January 1, 2018	$	172,386		$	306,137		$	478,523
Increase from current period acquisition	21,626			—			21,626
Measurement period adjustments from prior period acquisitions	(78		)	—			(78		)
Foreign currency translation	(1,305		)	(1,515		)	(2,820		)
Balance at June 30, 2018	$	192,629		$	304,622		$	497,251

Summary of indefinite-lived intangible assets

As of June 30, 2018 and December 31, 2017, the Company's total finite-lived and indefinite-lived intangible assets consisted of the following (in thousands):

	June 30, 2018						December 31, 2017
	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
Permits	$	175,317	$	76,707	$	98,610	$	174,721	$	74,347	$	100,374
Customer and supplier relationships	399,012		170,866		228,146		399,224		158,972		240,252
Other intangible assets	37,431		31,107		6,324		36,766		31,592		5,174
Total amortizable permits and other intangible assets	611,760		278,680		333,080		610,711		264,911		345,800
Indefinite lived trademarks and trade names	122,840		—		122,840		123,328		—		123,328
Total permits and other intangible assets	$	734,600	$	278,680	$	455,920	$	734,039	$	264,911	$	469,128

Schedule of finite-lived intangible assets

As of June 30, 2018 and December 31, 2017, the Company's total finite-lived and indefinite-lived intangible assets consisted of the following (in thousands):

	June 30, 2018						December 31, 2017
	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
Permits	$	175,317	$	76,707	$	98,610	$	174,721	$	74,347	$	100,374
Customer and supplier relationships	399,012		170,866		228,146		399,224		158,972		240,252
Other intangible assets	37,431		31,107		6,324		36,766		31,592		5,174
Total amortizable permits and other intangible assets	611,760		278,680		333,080		610,711		264,911		345,800
Indefinite lived trademarks and trade names	122,840		—		122,840		123,328		—		123,328
Total permits and other intangible assets	$	734,600	$	278,680	$	455,920	$	734,039	$	264,911	$	469,128

Schedule of expected amortization for the net carrying amount of finite lived intangible assets

The expected amortization of the net carrying amount of finite-lived intangible assets at June 30, 2018 was as follows (in thousands):

Years Ending December 31,	Expected Amortization
2018 (six months)	$	16,927
2019	32,143
2020	29,850
2021	27,381
2022	27,222
Thereafter	199,557
	$	333,080

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ACCRUED EXPENSES (Tables)

6 Months Ended

Jun. 30, 2018

Payables and Accruals [Abstract]

Accrued expenses

Accrued expenses consisted of the following at June 30, 2018 and December 31, 2017 (in thousands):

	June 30, 2018		December 31, 2017
Insurance	$	68,701	$	57,889
Interest	12,693		12,660
Accrued compensation and benefits	56,073		55,861
Income, real estate, sales and other taxes	27,116		27,330
Other	35,552		34,242
	$	200,135	$	187,982

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CLOSURE AND POST-CLOSURE LIABILITIES (Tables)

6 Months Ended

Jun. 30, 2018

Asset Retirement Obligation Disclosure [Abstract]

Schedule of closure and post-closure liabilities

The changes to closure and post-closure liabilities (also referred to as “asset retirement obligations”) from January 1, 2018 through June 30, 2018 were as follows (in thousands):

	Landfill Retirement Liability			Non-Landfill Retirement Liability			Total
Balance at January 1, 2018	$	32,382		$	28,655		$	61,037
Liabilities assumed in acquisition	—			604			604
New asset retirement obligations	1,478			—			1,478
Accretion	1,284			1,245			2,529
Changes in estimates recorded to statement of operations	—			85			85
Changes in estimates recorded to balance sheet	430			—			430
Expenditures	(359		)	(88		)	(447		)
Currency translation and other	(127		)	(85		)	(212		)
Balance at June 30, 2018	$	35,088		$	30,416		$	65,504

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REMEDIAL LIABILITIES (Tables)

6 Months Ended

Jun. 30, 2018

Environmental Remediation Obligations [Abstract]

Changes to remedial liabilities

The changes to remedial liabilities for the six months ended June 30, 2018 were as follows (in thousands):

	Remedial Liabilities for Landfill Sites			Remedial Liabilities for Inactive Sites			Remedial Liabilities (Including Superfund) for Non-Landfill Operations			Total
Balance at January 1, 2018	$	1,800		$	65,342		$	57,326		$	124,468
Accretion	43			1,375			931			2,349
Changes in estimates recorded to statement of operations	—			83			(841		)	(758		)
Expenditures	(23		)	(1,939		)	(2,176		)	(4,138		)
Currency translation and other	—			882			(1,528		)	(646		)
Balance at June 30, 2018	$	1,820		$	65,743		$	53,712		$	121,275

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FINANCING ARRANGEMENTS (Tables)

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

Summary of the entity's financial arrangements

The following table is a summary of the Company’s financing arrangements (in thousands):

	June 30, 2018			December 31, 2017
Senior secured Term Loan Agreement ("Term Loan Agreement")	$	4,000		$	4,000
Current portion of long-term obligations, at carrying value	$	4,000		$	4,000
Senior secured Term Loan Agreement due June 30, 2024	$	392,000		$	394,000
Senior unsecured notes, at 5.25%, due August 1, 2020 ("2020 Notes")	400,000			400,000
Senior unsecured notes, at 5.125%, due June 1, 2021 ("2021 Notes")	845,000			845,000
Long-term obligations, at par	$	1,637,000		$	1,639,000
Unamortized debt issuance costs and premium, net	(12,273		)	(13,463		)
Long-term obligations, at carrying value	$	1,624,727		$	1,625,537
Total current and long-term obligations, at carrying value	$	1,628,727		$	1,629,537

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EARNINGS PER SHARE (Tables)

6 Months Ended

Jun. 30, 2018

Earnings Per Share [Abstract]

Reconciliation of basic and diluted earnings per share computations

The following are computations of basic and diluted earnings per share (in thousands except for per share amounts):

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2018		2017		2018		2017
Numerator for basic and diluted earnings per share:
Net income	$	30,747	$	25,880	$	18,116	$	4,487
Denominator:
Basic shares outstanding	56,410		57,190		56,304		57,226
Dilutive effect of equity-based compensation awards	95		146		95		123
Dilutive shares outstanding	56,505		57,336		56,399		57,349
Basic income per share:	$	0.55	$	0.45	$	0.32	$	0.08
Diluted income per share:	$	0.54	$	0.45	$	0.32	$	0.08

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ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)

6 Months Ended

Jun. 30, 2018

Equity [Abstract]

Schedule of accumulated other comprehensive loss

The changes in accumulated other comprehensive loss by component and related tax effects for the six months ended June 30, 2018 were as follows (in thousands):    

	Foreign Currency Translation			Unrealized Losses on Available-For-Sale Securities			Unfunded Pension Liability			Total
Balance at January 1, 2018	$	(170,575	)	$	(146	)	$	(1,686	)	$	(172,407	)
Other comprehensive loss before tax effects	(27,091		)	(118		)	—			(27,209		)
Tax effects	5,609			(88		)	—			5,521
Other comprehensive loss	$	(21,482	)	$	(206	)	$	—		$	(21,688	)
Balance at June 30, 2018	$	(192,057	)	$	(352	)	$	(1,686	)	$	(194,095	)

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STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of restricted stock awards

The following table summarizes information about restricted stock awards for the six months ended June 30, 2018:

Restricted Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2018	604,933		$	54.23
Granted	200,688		$	52.92
Vested	(152,283	)	$	54.65
Forfeited	(17,136	)	$	53.63
Balance at June 30, 2018	636,202		$	53.73

Summary of performance stock awards

The following table summarizes information about performance stock awards for the six months ended June 30, 2018:

Performance Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2018	190,129		$	55.63
Vested	(8,696	)	$	54.26
Forfeited	(12,889	)	$	55.09
Balance at June 30, 2018	168,544		$	55.75

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SEGMENT REPORTING (Tables)

6 Months Ended

Jun. 30, 2018

Segment Reporting [Abstract]

Reconciliation of third party revenues to direct revenues

The following table reconciles third party revenues to direct revenues for the three and six months ended June 30, 2018 and 2017 (in thousands):

	For the Three Months Ended June 30, 2018											For the Three Months Ended June 30, 2017
	Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Environmental Services	$	519,916	$	34,291		$	607		$	554,814		$	449,631	$	31,639		$	320		$	481,590
Safety-Kleen	328,715		(34,291		)	11			294,435			302,956		(31,639		)	(2		)	271,315
Corporate Items	509		—			(618		)	(109		)	201		—			(318		)	(117		)
Total	$	849,140	$	—		$	—		$	849,140		$	752,788	$	—		$	—		$	752,788

	For the Six Months Ended June 30, 2018											For the Six Months Ended June 30, 2017
	Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Environmental Services	$	959,604	$	66,256		$	1,401		$	1,027,261		$	845,538	$	63,708		$	1,240		$	910,486
Safety-Kleen	638,633		(66,256		)	22			572,399			595,857		(63,708		)	1			532,150
Corporate Items	681		—			(1,423		)	(742		)	334		—			(1,241		)	(907		)
Total	$	1,598,918	$	—		$	—		$	1,598,918		$	1,441,729	$	—		$	—		$	1,441,729

Reconciliation to consolidated statements of income from adjusted EBITDA

The following table presents Adjusted EBITDA information used by management by reported segment (in thousands):

	For the Three Months Ended						For the Six Months Ended
	June 30,						June 30,
	2018			2017			2018			2017
Adjusted EBITDA:
Environmental Services	$	109,199		$	94,832		$	170,616		$	155,022
Safety-Kleen	73,069			60,281			134,953			112,649
Corporate Items	(42,707		)	(34,422		)	(77,743		)	(66,845		)
Total	$	139,561		$	120,691		$	227,826		$	200,826
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	2,448			2,416			4,878			4,706
Depreciation and amortization	72,760			71,531			147,604			143,943
Income from operations	64,353			46,744			75,344			52,177
Other (income) expense, net	(846		)	833			(547		)	2,382
Loss on early extinguishment of debt	—			6,045			—			6,045
Gain on sale of business	—			(31,722		)	—			(31,722		)
Interest expense, net of interest income	20,769			22,492			41,039			45,068
Income before provision for income taxes	$	44,430		$	49,096		$	34,852		$	30,404

PP&E, intangible assets and total assets by segment

The following table presents certain assets by reportable segment and in the aggregate (in thousands):

	June 30, 2018
	Environmental Services		Safety-Kleen		Corporate Items		Totals
Property, plant and equipment, net	$	988,957	$	555,124	$	65,301	$	1,609,382
Goodwill	192,629		304,622		—		497,251
Permits and other intangibles, net	96,165		359,755		—		455,920
Total assets	$	1,681,627	$	1,436,014	$	597,820	$	3,715,461

	December 31, 2017
	Environmental Services		Safety-Kleen		Corporate Items		Totals
Property, plant and equipment, net	$	927,139	$	582,162	$	78,064	$	1,587,365
Goodwill	172,386		306,137		—		478,523
Permits and other intangibles, net	97,519		371,609		—		469,128
Total assets	$	1,541,241	$	1,471,291	$	694,038	$	3,706,570

Total assets by geographical area

The following table presents total assets by geographical area (in thousands):

	June 30, 2018		December 31, 2017
United States	$	3,041,509	$	2,985,394
Canada	673,836		721,176
Other foreign	116		—
Total	$	3,715,461	$	3,706,570

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GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Tables)

6 Months Ended

Jun. 30, 2018

Guarantor and Non-Guarantor Subsidiaries Financial Information [Abstract]

Schedule of condensed consolidating balance sheet

Following is the condensed consolidating balance sheet at June 30, 2018 (in thousands):

	Clean Harbors, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Consolidating Adjustments			Total
Assets:
Cash and cash equivalents	$	51,960	$	92,833	$	52,275	$	—		$	197,068
Short-term marketable securities	—		—		36,862		—			36,862
Intercompany receivables	250,206		651,218		61,125		(962,549		)	—
Accounts receivable, net	—		497,775		92,805		—			590,580
Other current assets	—		260,489		60,225		(8,742		)	311,972
Property, plant and equipment, net	—		1,243,171		366,211		—			1,609,382
Investments in subsidiaries	3,135,271		599,091		—		(3,734,362		)	—
Intercompany debt receivable	—		15,224		21,000		(36,224		)	—
Goodwill	—		437,229		60,022		—			497,251
Permits and other intangibles, net	—		402,096		53,824		—			455,920
Other long-term assets	2,283		12,337		1,811		(5		)	16,426
Total assets	$	3,439,720	$	4,211,463	$	806,160	$	(4,741,882	)	$	3,715,461
Liabilities and Stockholders’ Equity:
Current liabilities	$	16,627	$	406,111	$	129,672	$	(8,742	)	$	543,668
Intercompany payables	637,318		309,423		15,808		(962,549		)	—
Closure, post-closure and remedial liabilities, net	—		146,922		16,850		—			163,772
Long-term obligations, net	1,624,727		—		—		—			1,624,727
Intercompany debt payable	—		21,000		15,224		(36,224		)	—
Other long-term liabilities	—		200,999		21,252		(5		)	222,246
Total liabilities	2,278,672		1,084,455		198,806		(1,007,520		)	2,554,413
Stockholders’ equity	1,161,048		3,127,008		607,354		(3,734,362		)	1,161,048
Total liabilities and stockholders’ equity	$	3,439,720	$	4,211,463	$	806,160	$	(4,741,882	)	$	3,715,461

Following is the condensed consolidating balance sheet at December 31, 2017 (in thousands):

	Clean Harbors, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Consolidating Adjustments			Total
Assets:
Cash and cash equivalents	$	51,638	$	207,777	$	59,984	$	—		$	319,399
Short-term marketable securities	—		—		38,179		—			38,179
Intercompany receivables	238,339		590,100		52,909		(881,348		)	—
Accounts receivable, net	—		433,042		95,882		—			528,924
Other current assets	897		233,602		52,947		(19,892		)	267,554
Property, plant and equipment, net	—		1,174,975		412,390		—			1,587,365
Investments in subsidiaries	3,112,547		569,568		—		(3,682,115		)	—
Intercompany debt receivable	—		92,530		21,000		(113,530		)	—
Goodwill	—		415,641		62,882		—			478,523
Permits and other intangibles, net	—		408,655		60,473		—			469,128
Other long-term assets	2,084		12,064		3,350		—			17,498
Total assets	$	3,405,505	$	4,137,954	$	859,996	$	(4,696,885	)	$	3,706,570
Liabilities and Stockholders’ Equity:
Current liabilities	$	16,954	$	371,135	$	135,620	$	(19,892	)	$	503,817
Intercompany payables	574,812		289,531		17,005		(881,348		)	—
Closure, post-closure and remedial liabilities, net	—		148,872		16,851		—			165,723
Long-term obligations, net	1,625,537		—		—		—			1,625,537
Intercompany debt payable	—		21,000		92,530		(113,530		)	—
Other long-term liabilities	—		201,086		22,205		—			223,291
Total liabilities	2,217,303		1,031,624		284,211		(1,014,770		)	2,518,368
Stockholders’ equity	1,188,202		3,106,330		575,785		(3,682,115		)	1,188,202
Total liabilities and stockholders’ equity	$	3,405,505	$	4,137,954	$	859,996	$	(4,696,885	)	$	3,706,570

Schedule of condensed consolidating statement of income

Following is the consolidating statement of operations for the three months ended June 30, 2018 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	544,521		$	165,435		$	(13,177	)	$	696,779
Product revenues	—			137,891			17,363			(2,893		)	152,361
Total revenues	—			682,412			182,798			(16,070		)	849,140
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			361,644			124,956			(13,177		)	473,423
Product cost of revenues	—			102,442			10,612			(2,893		)	110,161
Total cost of revenues	—			464,086			135,568			(16,070		)	583,584
Selling, general and administrative expenses	133			105,022			20,840			—			125,995
Accretion of environmental liabilities	—			2,194			254			—			2,448
Depreciation and amortization	—			52,864			19,896			—			72,760
(Loss) income from operations	(133		)	58,246			6,240			—			64,353
Other income, net	—			269			577			—			846
Interest (expense) income, net	(21,216		)	238			209			—			(20,769		)
Equity in earnings of subsidiaries, net of taxes	46,118			2,230			—			(48,348		)	—
Intercompany interest income (expense)	—			1,084			(1,084		)	—			—
Income before (benefit) provision for income taxes	24,769			62,067			5,942			(48,348		)	44,430
(Benefit) provision for income taxes	(5,978		)	18,228			1,433			—			13,683
Net income	30,747			43,839			4,509			(48,348		)	30,747
Other comprehensive loss	(4,942		)	(4,942		)	(10,435		)	15,377			(4,942		)
Comprehensive income (loss)	$	25,805		$	38,897		$	(5,926	)	$	(32,971	)	$	25,805

Following is the consolidating statement of operations for the three months ended June 30, 2017 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	474,801		$	147,924		$	(11,785	)	$	610,940
Product revenues	—			125,859			18,730			(2,741		)	141,848
Total revenues	—			600,660			166,654			(14,526		)	752,788
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			306,960			117,181			(11,785		)	412,356
Product cost of revenues	—			98,645			11,543			(2,741		)	107,447
Total cost of revenues	—			405,605			128,724			(14,526		)	519,803
Selling, general and administrative expenses	27			92,504			19,763			—			112,294
Accretion of environmental liabilities	—			2,181			235			—			2,416
Depreciation and amortization	—			51,937			19,594			—			71,531
(Loss) income from operations	(27		)	48,433			(1,662		)	—			46,744
Other expense, net	(76		)	(406		)	(351		)	—			(833		)
Loss on early extinguishment of debt	(6,045		)	—			—			—			(6,045		)
Gain on sale of business	—			31,722			—			—			31,722
Interest (expense) income, net	(22,614		)	240			(118		)	—			(22,492		)
Equity in earnings of subsidiaries, net of taxes	43,167			(5,332		)	—			(37,835		)	—
Intercompany interest income (expense)	—			1,268			(1,268		)	—			—
Income (loss) before (benefit) provision for income taxes	14,405			75,925			(3,399		)	(37,835		)	49,096
(Benefit) provision for income taxes	(11,475		)	31,981			2,710			—			23,216
Net income (loss)	25,880			43,944			(6,109		)	(37,835		)	25,880
Other comprehensive income	15,098			15,098			12,837			(27,935		)	15,098
Comprehensive income	$	40,978		$	59,042		$	6,728		$	(65,770	)	$	40,978

Schedule of condensed consolidating statement of cash flows

Following is the condensed consolidating statement of cash flows for the six months ended June 30, 2018 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Net cash from operating activities	$	790		$	121,021		$	7,859		$	—		$	129,670
Cash flows used in investing activities:
Additions to property, plant and equipment	—			(77,773		)	(16,366		)	—			(94,139		)
Proceeds from sale and disposal of fixed assets	—			1,035			1,606			—			2,641
Acquisitions, net of cash acquired	—			(123,750		)	—			—			(123,750		)
Additions to intangible assets, including costs to obtain or renew permits	—			(1,991		)	(115		)	—			(2,106		)
Proceeds from sale of available-for-sale securities	—			—			11,214			—			11,214
Purchases of available-for-sale securities	—			—			(10,001		)	—			(10,001		)
Intercompany	—			(30,657		)	—			30,657			—
Net cash used in investing activities	—			(233,136		)	(13,662		)	30,657			(216,141		)
Cash flows (used in) from financing activities:
Change in uncashed checks	—			(2,829		)	26			—			(2,803		)
Tax payments related to withholdings on vested restricted stock	(2,175		)	—			—			—			(2,175		)
Repurchases of common stock	(26,482		)	—			—			—			(26,482		)
Deferred financing costs paid	(468		)	—			—			—			(468		)
Principal payment on debt	(2,000		)	—			—			—			(2,000		)
Intercompany	30,657			—			—			(30,657		)	—
Net cash (used) from in financing activities	(468		)	(2,829		)	26			(30,657		)	(33,928		)
Effect of exchange rate change on cash	—			—			(1,932		)	—			(1,932		)
Increase (decrease) in cash and cash equivalents	322			(114,944		)	(7,709		)	—			(122,331		)
Cash and cash equivalents, beginning of period	51,638			207,777			59,984			—			319,399
Cash and cash equivalents, end of period	$	51,960		$	92,833		$	52,275		$	—		$	197,068

Following is the condensed consolidating statement of cash flows for the six months ended June 30, 2017 (in thousands):

	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Net cash (used in) from operating activities	$	(93,808	)	$	206,496		$	4,243		$	—		$	116,931
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	—			(75,152		)	(13,590		)	—			(88,742		)
Proceeds from sale and disposal of fixed assets	—			984			1,137			—			2,121
Acquisitions, net of cash acquired	—			(9,277		)	—			—			(9,277		)
Proceeds from sale of businesses, net of transactional costs	—			46,210			181			—			46,391
Additions to intangible assets, including costs to obtain or renew permits	—			(888		)	(351		)	—			(1,239		)
Proceeds from sale of available-for-sale securities	376			—			—			—			376
Intercompany	—			(14,343		)	—			14,343			—
Net cash from (used in) investing activities	376			(52,466		)	(12,623		)	14,343			(50,370		)
Cash flows from (used in) financing activities:
Change in uncashed checks	—			(5,977		)	(2,384		)	—			(8,361		)
Proceeds from exercise of stock options	46			—			—			—			46
Tax payments related to withholdings on vested restricted stock	(2,132		)	—			—			—			(2,132		)
Repurchases of common stock	(12,257		)	—			—			—			(12,257		)
Deferred financing costs paid	(4,727		)	—			—			—			(4,727		)
Premium paid on early extinguishment of debt	(4,665		)	—			—			—			(4,665		)
Principal payment on debt	(296,202		)	—			—			—			(296,202		)
Issuance of senior secured notes, net of discount	399,000			—			—			—			399,000
Intercompany	14,343			—			—			(14,343		)	—
Net cash from (used) in financing activities	93,406			(5,977		)	(2,384		)	(14,343		)	70,702
Effect of exchange rate change on cash	—			—			2,106			—			2,106
(Decrease) increase in cash and cash equivalents	(26		)	148,053			(8,658		)	—			139,369
Cash and cash equivalents, beginning of period	51,417			155,943			99,637			—			306,997
Cash and cash equivalents, end of period	$	51,391		$	303,996		$	90,979		$	—		$	446,366

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SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($) segment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of operating segments | segment	2
Cumulative effect of change in accounting principle	$ (1,564)
Accumulated Earnings | Accounting Standards Update 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle	$ (1,564)

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REVENUES (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 849,140	$ 752,788	$ 1,598,918	$ 1,441,729
United States
Disaggregation of Revenue [Line Items]
Revenues	714,549	624,095	1,346,308	1,210,082
Canada
Disaggregation of Revenue [Line Items]
Revenues	134,591	128,693	252,610	231,647
Technical Services
Disaggregation of Revenue [Line Items]
Revenues	257,006	254,487	493,312	484,705
Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Revenues	76,092	70,707	146,027	131,726
Industrial Services
Disaggregation of Revenue [Line Items]
Revenues	161,046	99,733	264,809	174,801
Oil, Gas and Lodging Services and Other
Disaggregation of Revenue [Line Items]
Revenues	26,281	24,905	56,137	54,640
Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Revenues	200,034	192,817	394,195	384,544
Kleen Performance Products
Disaggregation of Revenue [Line Items]
Revenues	128,681	110,139	244,438	211,313
Environmental Services
Disaggregation of Revenue [Line Items]
Revenues	519,916	449,631	959,604	845,538
Environmental Services | United States
Disaggregation of Revenue [Line Items]
Revenues	408,127	343,323	752,099	657,106
Environmental Services | Canada
Disaggregation of Revenue [Line Items]
Revenues	111,789	106,308	207,505	188,432
Environmental Services | Technical Services
Disaggregation of Revenue [Line Items]
Revenues	257,006	254,487	493,312	484,705
Environmental Services | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Revenues	76,092	70,707	146,027	131,726
Environmental Services | Industrial Services
Disaggregation of Revenue [Line Items]
Revenues	161,046	99,733	264,809	174,801
Environmental Services | Oil, Gas and Lodging Services and Other
Disaggregation of Revenue [Line Items]
Revenues	25,772	24,704	55,456	54,306
Environmental Services | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Environmental Services | Kleen Performance Products
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Safety-Kleen
Disaggregation of Revenue [Line Items]
Revenues	328,715	302,956	638,633	595,857
Safety-Kleen | United States
Disaggregation of Revenue [Line Items]
Revenues	306,059	280,617	593,701	552,688
Safety-Kleen | Canada
Disaggregation of Revenue [Line Items]
Revenues	22,656	22,339	44,932	43,169
Safety-Kleen | Technical Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Safety-Kleen | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Safety-Kleen | Industrial Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Safety-Kleen | Oil, Gas and Lodging Services and Other
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Safety-Kleen | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Revenues	200,034	192,817	394,195	384,544
Safety-Kleen | Kleen Performance Products
Disaggregation of Revenue [Line Items]
Revenues	128,681	110,139	244,438	211,313
Corporate
Disaggregation of Revenue [Line Items]
Revenues	509	201	681	334
Corporate | United States
Disaggregation of Revenue [Line Items]
Revenues	363	155	508	288
Corporate | Canada
Disaggregation of Revenue [Line Items]
Revenues	146	46	173	46
Corporate | Technical Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate | Industrial Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate | Oil, Gas and Lodging Services and Other
Disaggregation of Revenue [Line Items]
Revenues	509	201	681	334
Corporate | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate | Kleen Performance Products
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0	$ 0	$ 0

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REVENUES (Contract Balances) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Revenue from Contract with Customer [Abstract]
Receivables	$ 590,580	$ 528,924	$ 512,375	$ 496,226
Contract Assets	62,762	35,922	46,576	36,190
Contract Liabilities	$ 68,705	$ 67,822	$ 72,089	$ 64,397

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REVENUES (Narrative) (Details) - Veolia Division $ in Millions	Feb. 23, 2018 USD ($)
Business Acquisition [Line Items]
Acquired receivables	$ 20.5
Customer contracts
Business Acquisition [Line Items]
Acquired contract assets	$ 17.6

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BUSINESS COMBINATIONS (2018 Acquisition) (Details) - Veolia Division - USD ($) $ in Millions		3 Months Ended	6 Months Ended
	Feb. 23, 2018	Jun. 30, 2018	Jun. 30, 2018
Business Acquisition [Line Items]
Purchase price	$ 120.0
Revenue from acquisition included in results of operations		$ 46.3	$ 63.9
Pre-tax income		2.1	3.3
Acquisition-related costs		$ 0.4	$ 0.9
Weighted average amortization period (in years)	8 years 2 months

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BUSINESS COMBINATIONS (Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	4 Months Ended
	Jun. 30, 2018	Feb. 23, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill	$ 497,251		$ 478,523
Veolia Division
Business Acquisition [Line Items]
Accounts receivable	38,082	$ 40,773
Measurement Period Adjustments, Accounts receivable, including unbilled receivables	(2,691)
Inventories and supplies	1,126	1,442
Measurement Period Adjustments, Inventories and supplies	(316)
Prepaid and other current assets	925	1,005
Measurement Period Adjustments, Prepaid expenses and other current assets	(80)
Property, plant and equipment	72,244	72,244
Measurement Period Adjustments, Property, plant and equipment	0
Permits and other intangibles	5,140	5,140
Measurement Period Adjustments, Permits and other intangibles	0
Current liabilities	(18,539)	(15,908)
Measurement Period Adjustments, Current liabilities	(2,631)
Closure and post-closure liabilities	(604)	(604)
Measurement Period Adjustments, Closure and post-closure liabilities	0
Total identifiable net assets	98,374	104,092
Measurement Period Adjustments, Total identifiable net assets	(5,718)
Goodwill	21,626	15,908
Measurement Period Adjustments, Goodwill	5,718
Total purchase price, net of cash acquired	120,000	$ 120,000
Measurement Period Adjustments, Total purchase price, net of cash acquired	$ 0

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BUSINESS COMBINATIONS (2017 Acquisitions) (Details) $ / shares in Units, $ in Thousands, $ in Millions				6 Months Ended
	Jul. 14, 2017 CAD ($) $ / shares	Jul. 14, 2017 USD ($)	Jan. 31, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jul. 14, 2017 USD ($)
Business Acquisition [Line Items]
Goodwill recognized				$ 21,626
Lonestar
Business Acquisition [Line Items]
Cash paid to acquire Lonestar	$ 41.8	$ 33,100
Equity payout (in CAD per share) | $ / shares	$ 0.72
Debt outstanding assumed	$ 21.3				$ 16,800
Goodwill recognized		$ 2,800
2017 Acquisitions
Business Acquisition [Line Items]
Goodwill recognized			$ 5,000
Purchase price			$ 11,900

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DISPOSITION OF BUSINESS (Narrative) (Details) $ in Millions	Jun. 30, 2017 USD ($)
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Final sale proceeds	$ 45.5

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DISPOSITION OF BUSINESS (Income (Loss) Attributable to Transformer Services) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income before provision for income taxes	$ 1,873	$ 2,771

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INVENTORIES AND SUPPLIES (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Oil and oil products	$ 68,125	$ 58,142
Supplies and drums	100,118	94,242
Solvent and solutions	9,230	9,167
Modular camp accommodations	2,494	1,826
Other	13,577	12,635
Total inventories and supplies	$ 193,544	$ 176,012

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PROPERTY, PLANT AND EQUIPMENT (Schedule of Property, Plant and Equipment) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 3,286,569	$ 3,190,573
Less - accumulated depreciation and amortization	1,677,187	1,603,208
Total property, plant and equipment, net	1,609,382	1,587,365
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	123,984	121,658
Asset retirement costs (non-landfill)
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	14,780	14,593
Landfill assets
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	145,068	144,539
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	429,880	414,384
Camp equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	161,899	170,012
Vehicles
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	689,846	617,959
Equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	1,675,920	1,644,102
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	5,623	5,708
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 39,569	$ 57,618

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PROPERTY, PLANT AND EQUIPMENT (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Interest costs capitalized adjustment	$ 0.1	$ 0.1	$ 0.4	$ 0.2
Depreciation inclusive of amortization	$ 64.2	$ 61.8	$ 129.8	$ 125.2

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GOODWILL AND OTHER INTANGIBLE ASSETS (Rollforward of Goodwill) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Goodwill [Roll Forward]
Balance at beginning of year	$ 478,523
Increase from current period acquisition	21,626
Measurement period adjustments from prior period acquisitions	(78)
Foreign currency translation	(2,820)
Balance at end of year	497,251
Environmental Services
Goodwill [Roll Forward]
Balance at beginning of year	172,386
Increase from current period acquisition	21,626
Measurement period adjustments from prior period acquisitions	(78)
Foreign currency translation	(1,305)
Balance at end of year	192,629
Safety-Kleen
Goodwill [Roll Forward]
Balance at beginning of year	306,137
Increase from current period acquisition	0
Measurement period adjustments from prior period acquisitions	0
Foreign currency translation	(1,515)
Balance at end of year	$ 304,622

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GOODWILL AND OTHER INTANGIBLE ASSETS (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of permits and other intangible assets	$ 8.6	$ 9.7	$ 17.8	$ 18.8

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GOODWILL AND OTHER INTANGIBLE ASSETS (Amortizable Other Intangible Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	$ 611,760	$ 610,711
Accumulated Amortization	278,680	264,911
Net	333,080	345,800
Total permits and other intangible assets, Cost	734,600	734,039
Total permits and other intangible assets, Net	455,920	469,128
Indefinite lived trademarks and trade names
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Indefinite lived trademarks and trade names	122,840	123,328
Permits
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	175,317	174,721
Accumulated Amortization	76,707	74,347
Net	98,610	100,374
Customer and supplier relationships
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	399,012	399,224
Accumulated Amortization	170,866	158,972
Net	228,146	240,252
Other intangible assets
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	37,431	36,766
Accumulated Amortization	31,107	31,592
Net	$ 6,324	$ 5,174

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GOODWILL AND OTHER INTANGIBLE ASSETS (Expected Future Amortization) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
2018 (six months)	$ 16,927
2019	32,143
2020	29,850
2021	27,381
2022	27,222
Thereafter	199,557
Net	$ 333,080	$ 345,800

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ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Insurance	$ 68,701	$ 57,889
Interest	12,693	12,660
Accrued compensation and benefits	56,073	55,861
Income, real estate, sales and other taxes	27,116	27,330
Other	35,552	34,242
Total accrued expenses	$ 200,135	$ 187,982

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CLOSURE AND POST-CLOSURE LIABILITIES (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Changes to post-closure liabilities
Beginning balance	$ 61,037
Liabilities assumed in acquisition	604
New asset retirement obligations	1,478
Accretion	2,529
Changes in estimates recorded to statement of operations	85
Changes in estimates recorded to balance sheet	430
Expenditures	(447)
Currency translation and other	(212)
Ending balance	$ 65,504
Credit-adjusted risk-free rate	5.66%
Landfill Retirement Liability
Changes to post-closure liabilities
Beginning balance	$ 32,382
Liabilities assumed in acquisition	0
New asset retirement obligations	1,478
Accretion	1,284
Changes in estimates recorded to statement of operations	0
Changes in estimates recorded to balance sheet	430
Expenditures	(359)
Currency translation and other	(127)
Ending balance	35,088
Non-Landfill Retirement Liability
Changes to post-closure liabilities
Beginning balance	28,655
Liabilities assumed in acquisition	604
New asset retirement obligations	0
Accretion	1,245
Changes in estimates recorded to statement of operations	85
Changes in estimates recorded to balance sheet	0
Expenditures	(88)
Currency translation and other	(85)
Ending balance	$ 30,416

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REMEDIAL LIABILITIES (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year	$ 124,468
Accretion	2,349
Changes in estimates recorded to statement of operations	(758)
Expenditures	(4,138)
Currency translation and other	(646)
Balance at end of year	121,275
Remedial Liabilities for Landfill Sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year	1,800
Accretion	43
Changes in estimates recorded to statement of operations	0
Expenditures	(23)
Currency translation and other	0
Balance at end of year	1,820
Remedial Liabilities for Inactive Sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year	65,342
Accretion	1,375
Changes in estimates recorded to statement of operations	83
Expenditures	(1,939)
Currency translation and other	882
Balance at end of year	65,743
Remedial Liabilities (Including Superfund) for Non-Landfill Operations
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year	57,326
Accretion	931
Changes in estimates recorded to statement of operations	(841)
Expenditures	(2,176)
Currency translation and other	(1,528)
Balance at end of year	$ 53,712

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FINANCING ARRANGEMENTS (Summary of Financing Arrangements) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Current portion of long-term obligations	$ 4,000	$ 4,000
Long-term obligations, at par	1,637,000	1,639,000
Unamortized debt issuance costs and premium, net	(12,273)	(13,463)
Long-term obligations, at carrying value	1,624,727	1,625,537
Total current and long-term obligations, at carrying value	1,628,727	1,629,537
Secured debt | Term Loan Agreement
Debt Instrument [Line Items]
Current portion of long-term obligations	4,000	4,000
Long-term obligations, at par	392,000	394,000
Unsecured debt | Senior unsecured notes, at 5.25%, due August 1, 2020 (2020 Notes)
Debt Instrument [Line Items]
Long-term obligations, at par	$ 400,000	400,000
Interest rate	5.25%
Unsecured debt | Senior unsecured notes, at 5.125%, due June 1, 2021 (2021 Notes)
Debt Instrument [Line Items]
Long-term obligations, at par	$ 845,000	$ 845,000
Interest rate	5.125%

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FINANCING ARRANGEMENTS (Narrative) (Details)	Aug. 01, 2018 USD ($)	Jul. 19, 2018 USD ($)	Jun. 30, 2018 USD ($)	Apr. 17, 2018	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Debt outstanding			$ 1,628,727,000		$ 1,629,537,000
Long-term obligations, at par			1,637,000,000		1,639,000,000
Outstanding loan balances			0		0
Available to borrow and outstanding letters of credit			244,300,000		217,800,000
Outstanding letters of credit			132,400,000		134,100,000
Secured debt | Term Loan Agreement
Debt Instrument [Line Items]
Long-term obligations, at par			392,000,000		394,000,000
Debt fair value			$ 394,500,000		400,500,000
Unsecured debt | Senior unsecured notes, at 5.25%, due August 1, 2020 (2020 Notes)
Debt Instrument [Line Items]
Interest rate			5.25%
Long-term obligations, at par			$ 400,000,000		400,000,000
Debt fair value			$ 400,900,000		404,600,000
Unsecured debt | Senior unsecured notes, at 5.125%, due June 1, 2021 (2021 Notes)
Debt Instrument [Line Items]
Interest rate			5.125%
Long-term obligations, at par			$ 845,000,000		845,000,000
Debt fair value			848,600,000		855,700,000
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Revolving credit facility maximum borrowing capacity			$ 400,000,000.0		$ 400,000,000.0
Eurodollar | Secured debt | First Amendment
Debt Instrument [Line Items]
Interest rate				1.75%
Decrease in interest rate				0.0025
Base Rate | Secured debt | First Amendment
Debt Instrument [Line Items]
Interest rate				0.75%
Decrease in interest rate				0.0025
Subsequent Event [Member] | Term Loan Agreement
Debt Instrument [Line Items]
Increase in principal amount of initial term loans		$ 350,000,000
Debt outstanding		$ 746,000,000
Debt Instrument, Prepayment Premium, Percentage		1.00%
Subsequent Event [Member] | Senior unsecured notes, at 5.25%, due August 1, 2020 (2020 Notes)
Debt Instrument [Line Items]
Debt outstanding	$ 78,000,000	$ 322,000,000
Proceeds from Lines of Credit	$ 50,000,000
Purchase price per $1,000		330,900,000
Long-term Debt, Purchase Price, Accrued Interest		$ 7,900,000

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EARNINGS PER SHARE (Computation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator for basic and diluted earnings per share:
Net income	$ 30,747	$ 25,880	$ 18,116	$ 4,487
Denominator:
Basic shares outstanding (in shares)	56,410	57,190	56,304	57,226
Dilutive effect of equity-based compensation awards (in shares)	95	146	95	123
Dilutive shares outstanding (in shares)	56,505	57,336	56,399	57,349
Basic income per share (in USD per share)	$ 0.55	$ 0.45	$ 0.32	$ 0.08
Diluted income per share (in USD per share)	$ 0.54	$ 0.45	$ 0.32	$ 0.08

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EARNINGS PER SHARE (Narrative) (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Performance stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earning per share (in shares)	146,159	142,503	146,159	142,503
Restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earning per share (in shares)	136,155	14,699	130,932	21,013

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ACCUMULATED OTHER COMPREHENSIVE LOSS (Changes in Accumulated Other Comprehensive Loss by Component) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	$ 1,188,202
Other comprehensive loss before tax effects	(27,209)
Tax effects	5,521
Other comprehensive income	(21,688)
Balance at end of period	1,161,048
Foreign Currency Translation
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(170,575)
Other comprehensive loss before tax effects	(27,091)
Tax effects	5,609
Other comprehensive income	(21,482)
Balance at end of period	(192,057)
Unrealized Losses on Available-For-Sale Securities
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(146)
Other comprehensive loss before tax effects	(118)
Tax effects	(88)
Other comprehensive income	(206)
Balance at end of period	(352)
Unfunded Pension Liability
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(1,686)
Other comprehensive loss before tax effects	0
Tax effects	0
Other comprehensive income	0
Balance at end of period	(1,686)
Total
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(172,407)
Balance at end of period	$ (194,095)

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STOCK-BASED COMPENSATION (Narrative) (Details) - USD ($) shares in Millions	3 Months Ended		6 Months Ended		52 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Oct. 31, 2017	Oct. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 3,500,000	$ 2,900,000	$ 6,600,000	$ 5,200,000
Income tax benefit	$ 700,000	$ 800,000	$ 1,300,000	$ 1,500,000
Shares authorized for repurchase						$ 600,000,000	$ 300,000,000
Repurchases of common stock (in shares)	0.2	0.1	0.5	0.2	5.3
Repurchases of common stock	$ 12,200,000	$ 5,500,000	$ 26,482,000	$ 12,300,000	$ 275,300,000
Stock repurchase program, remaining authorized repurchase amount	324,700,000		324,700,000		324,700,000
Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	27,100,000		$ 27,100,000		27,100,000
Period for recognition (in years)			2 years 8 months
Fair value restricted stock	7,000,000	$ 4,500,000	$ 8,300,000	6,000,000
Performance stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 1,300,000		1,300,000		$ 1,300,000
Fair value restricted stock			$ 500,000	$ 1,400,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)			3 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)			5 years

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STOCK-BASED COMPENSATION (Restricted Stock) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restricted stock awards
Number of Shares
Beginning balance (in shares)			604,933
Granted (in shares)			200,688
Vested (in shares)			(152,283)
Forfeited (in shares)			(17,136)
Ending balance (in shares)	636,202		636,202
Weighted Average Grant-Date Fair Value
Beginning of period (in USD per share)			$ 54.23
Granted (in USD per share)			52.92
Vested (in USD per share)			54.65
Forfeited (in USD per share)			53.63
End of period (in USD per share)	$ 53.73		$ 53.73
Unrecognized compensation cost	$ 27.1		$ 27.1
Period for recognition (in years)			2 years 8 months
Fair value restricted stock	$ 7.0	$ 4.5	$ 8.3	$ 6.0
Minimum
Weighted Average Grant-Date Fair Value
Vesting period (in years)			3 years
Maximum
Weighted Average Grant-Date Fair Value
Vesting period (in years)			5 years

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STOCK-BASED COMPENSATION (Performance Stock Awards (Details) - Performance stock awards $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2017 USD ($)
Number of Shares
Beginning balance (in shares) | shares	190,129
Vested (in shares) | shares	(8,696)
Forfeited (in shares) | shares	(12,889)
Ending balance (in shares) | shares	168,544
Weighted Average Grant-Date Fair Value
Beginning of period (in USD per share) | $ / shares	$ 55.63
Vested (in USD per share) | $ / shares	54.26
Forfeited (in USD per share) | $ / shares	55.09
End of period (in USD per share) | $ / shares	$ 55.75
Unrecognized compensation cost | $	$ 1.3
Fair value restricted stock | $	$ 0.5	$ 1.4

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COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018 USD ($) proceeding site claim	Dec. 31, 2012 CAD ($)	Dec. 31, 1999 municipality	Dec. 31, 1968 permit	Dec. 31, 2017 USD ($) proceeding
Contingencies [Line Items]
Recorded reserves for actual or probable liabilities | $	$ 21,600,000				$ 19,300,000
Number of proceedings as defendant | proceeding	60
Number of product liability claims settled or dismissed | claim	3
Legal and Administrative Proceedings
Contingencies [Line Items]
Recorded reserves for actual or probable liabilities | $	$ 17,000,000				17,900,000
Possible increase in legal and administrative proceedings | $	$ 1,700,000				1,800,000
Ville Mercier
Contingencies [Line Items]
Number of permits issued by government, for dumping organic liquid | permit				2
Number of neighboring municipalities filing separate legal proceedings against the Mercier Subsidiary and the Government of Quebec | municipality			3
General damages sought | $		$ 2.9
Punitive damages sought | $		$ 10.0
Superfund Proceedings
Contingencies [Line Items]
Number of sites owned by third party excluded from cleanup or related liabilities	127
Number of sites owned by the entity subject to proceedings under federal or state superfund laws	3
Notices received from owners of third party sites seeking indemnification from the company	124
Number of sites for which environmental remediation expense is settled	34
Third party sites requiring expenditure on remediation	17
Number of sites not currently requiring expenditures on remediation	73
Number of sites which potential liability could exceed $100,000	10
Notices received from owners of third party sites seeking indemnification from the company	17
Superfund Proceedings | Minimum
Contingencies [Line Items]
Minimum potential liability | $	$ 100,000
ChemWaste
Contingencies [Line Items]
Indemnification agreement with third party sites	11
Kleen Performance Products
Contingencies [Line Items]
Notices received from owners of third party sites seeking indemnification from the company	6
Federal and State Enforcement Actions
Contingencies [Line Items]
Recorded reserves for actual or probable liabilities | $	$ 4,600,000				$ 1,400,000
Number of proceedings as defendant | proceeding	6				5
Federal and State Enforcement Actions | Minimum
Contingencies [Line Items]
Minimum potential liability | $	$ 100,000				$ 100,000

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INCOME TAXES (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective income tax rate	30.80%	47.30%	48.00%	85.20%
Unrecognized tax benefits	$ 5.0		$ 5.0		$ 5.1
Interest on unrecognized tax benefits	$ 1.0		1.0		$ 0.9
Reduction in unrecognized tax benefits from expiring statue of limitations			$ 1.4

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SEGMENT REPORTING (Narrative) (Details)	6 Months Ended
	Jun. 30, 2018 segment
Segment Reporting [Abstract]
Number of operating segments	2

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SEGMENT REPORTING (Third Party Revenues to Direct Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 849,140	$ 752,788	$ 1,598,918	$ 1,441,729
Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	0	0	0	0
Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	0	0	0	0
Direct revenues
Segment Reporting Information [Line Items]
Total revenues	849,140	752,788	1,598,918	1,441,729
Environmental Services
Segment Reporting Information [Line Items]
Total revenues	519,916	449,631	959,604	845,538
Environmental Services | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	34,291	31,639	66,256	63,708
Environmental Services | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	607	320	1,401	1,240
Environmental Services | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	554,814	481,590	1,027,261	910,486
Safety-Kleen
Segment Reporting Information [Line Items]
Total revenues	328,715	302,956	638,633	595,857
Safety-Kleen | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	(34,291)	(31,639)	(66,256)	(63,708)
Safety-Kleen | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	11	(2)	22	1
Safety-Kleen | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	294,435	271,315	572,399	532,150
Corporate Items
Segment Reporting Information [Line Items]
Total revenues	509	201	681	334
Corporate Items | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	0	0	0	0
Corporate Items | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	(618)	(318)	(1,423)	(1,241)
Corporate Items | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	$ (109)	$ (117)	$ (742)	$ (907)

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SEGMENT REPORTING (Adjusted EBITDA Information) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 139,561	$ 120,691	$ 227,826	$ 200,826
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	2,448	2,416	4,878	4,706
Depreciation and amortization	72,760	71,531	147,604	143,943
Income from operations	64,353	46,744	75,344	52,177
Other (income) expense, net	(846)	833	(547)	2,382
Loss on early extinguishment of debt	0	6,045	0	6,045
Gain on sale of business	0	(31,722)	0	(31,722)
Interest expense, net of interest income	20,769	22,492	41,039	45,068
Income before (benefit) provision for income taxes	44,430	49,096	34,852	30,404
Environmental Services
Segment Reporting Information [Line Items]
Adjusted EBITDA	109,199	94,832	170,616	155,022
Safety-Kleen
Segment Reporting Information [Line Items]
Adjusted EBITDA	73,069	60,281	134,953	112,649
Corporate Items
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ (42,707)	$ (34,422)	$ (77,743)	$ (66,845)

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SEGMENT REPORTING (Assets by Reportable Segment) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 1,609,382	$ 1,587,365
Goodwill	497,251	478,523
Permits and other intangibles, net	455,920	469,128
Total assets	3,715,461	3,706,570
Environmental Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	988,957	927,139
Goodwill	192,629	172,386
Permits and other intangibles, net	96,165	97,519
Total assets	1,681,627	1,541,241
Safety-Kleen
Segment Reporting Information [Line Items]
Property, plant and equipment, net	555,124	582,162
Goodwill	304,622	306,137
Permits and other intangibles, net	359,755	371,609
Total assets	1,436,014	1,471,291
Corporate Items
Segment Reporting Information [Line Items]
Property, plant and equipment, net	65,301	78,064
Goodwill	0	0
Permits and other intangibles, net	0	0
Total assets	$ 597,820	$ 694,038

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SEGMENT REPORTING (Total Assets by Geographical Area) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	$ 3,715,461	$ 3,706,570
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	3,041,509	2,985,394
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	673,836	721,176
Other foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	$ 116	$ 0

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GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Narrative) (Details)	6 Months Ended
	Jun. 30, 2018
Guarantor and Non-Guarantor Subsidiaries Financial Information [Abstract]
Ownership percentage of U.S. guarantor subsidiaries	100.00%

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GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 197,068	$ 319,399	$ 446,366	$ 306,997
Short-term marketable securities	36,862	38,179
Intercompany receivables	0	0
Accounts receivable, net	590,580	528,924
Other current assets	311,972	267,554
Property, plant and equipment, net	1,609,382	1,587,365
Investments in subsidiaries	0	0
Intercompany debt receivable	0	0
Goodwill	497,251	478,523
Permits and other intangibles, net	455,920	469,128
Other long-term assets	16,426	17,498
Total assets	3,715,461	3,706,570
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	543,668	503,817
Intercompany payables	0	0
Closure, post-closure and remedial liabilities, net	163,772	165,723
Long-term obligations, less current portion	1,624,727	1,625,537
Intercompany debt payable	0	0
Other long-term liabilities	222,246	223,291
Total liabilities	2,554,413	2,518,368
Stockholders’ equity	1,161,048	1,188,202
Total liabilities and stockholders’ equity	3,715,461	3,706,570
Reportable Legal Entities | Clean Harbors, Inc.
ASSETS
Cash and cash equivalents	51,960	51,638	51,391	51,417
Short-term marketable securities	0	0
Intercompany receivables	250,206	238,339
Accounts receivable, net	0	0
Other current assets	0	897
Property, plant and equipment, net	0	0
Investments in subsidiaries	3,135,271	3,112,547
Intercompany debt receivable	0	0
Goodwill	0	0
Permits and other intangibles, net	0	0
Other long-term assets	2,283	2,084
Total assets	3,439,720	3,405,505
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	16,627	16,954
Intercompany payables	637,318	574,812
Closure, post-closure and remedial liabilities, net	0	0
Long-term obligations, less current portion	1,624,727	1,625,537
Intercompany debt payable	0	0
Other long-term liabilities	0	0
Total liabilities	2,278,672	2,217,303
Stockholders’ equity	1,161,048	1,188,202
Total liabilities and stockholders’ equity	3,439,720	3,405,505
Reportable Legal Entities | Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	92,833	207,777	303,996	155,943
Short-term marketable securities	0	0
Intercompany receivables	651,218	590,100
Accounts receivable, net	497,775	433,042
Other current assets	260,489	233,602
Property, plant and equipment, net	1,243,171	1,174,975
Investments in subsidiaries	599,091	569,568
Intercompany debt receivable	15,224	92,530
Goodwill	437,229	415,641
Permits and other intangibles, net	402,096	408,655
Other long-term assets	12,337	12,064
Total assets	4,211,463	4,137,954
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	406,111	371,135
Intercompany payables	309,423	289,531
Closure, post-closure and remedial liabilities, net	146,922	148,872
Long-term obligations, less current portion	0	0
Intercompany debt payable	21,000	21,000
Other long-term liabilities	200,999	201,086
Total liabilities	1,084,455	1,031,624
Stockholders’ equity	3,127,008	3,106,330
Total liabilities and stockholders’ equity	4,211,463	4,137,954
Reportable Legal Entities | Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	52,275	59,984	90,979	99,637
Short-term marketable securities	36,862	38,179
Intercompany receivables	61,125	52,909
Accounts receivable, net	92,805	95,882
Other current assets	60,225	52,947
Property, plant and equipment, net	366,211	412,390
Investments in subsidiaries	0	0
Intercompany debt receivable	21,000	21,000
Goodwill	60,022	62,882
Permits and other intangibles, net	53,824	60,473
Other long-term assets	1,811	3,350
Total assets	806,160	859,996
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	129,672	135,620
Intercompany payables	15,808	17,005
Closure, post-closure and remedial liabilities, net	16,850	16,851
Long-term obligations, less current portion	0	0
Intercompany debt payable	15,224	92,530
Other long-term liabilities	21,252	22,205
Total liabilities	198,806	284,211
Stockholders’ equity	607,354	575,785
Total liabilities and stockholders’ equity	806,160	859,996
Consolidating Adjustments
ASSETS
Cash and cash equivalents	0	0	$ 0	$ 0
Short-term marketable securities	0	0
Intercompany receivables	(962,549)	(881,348)
Accounts receivable, net	0	0
Other current assets	(8,742)	(19,892)
Property, plant and equipment, net	0	0
Investments in subsidiaries	(3,734,362)	(3,682,115)
Intercompany debt receivable	(36,224)	(113,530)
Goodwill	0	0
Permits and other intangibles, net	0	0
Other long-term assets	(5)	0
Total assets	(4,741,882)	(4,696,885)
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	(8,742)	(19,892)
Intercompany payables	(962,549)	(881,348)
Closure, post-closure and remedial liabilities, net	0	0
Long-term obligations, less current portion	0	0
Intercompany debt payable	(36,224)	(113,530)
Other long-term liabilities	(5)	0
Total liabilities	(1,007,520)	(1,014,770)
Stockholders’ equity	(3,734,362)	(3,682,115)
Total liabilities and stockholders’ equity	$ (4,741,882)	$ (4,696,885)

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GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Consolidating Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Total revenues	$ 849,140	$ 752,788	$ 1,598,918	$ 1,441,729
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	583,584	519,803	1,130,009	1,016,388
Selling, general and administrative expenses	125,995	112,294	241,083	224,515
Accretion of environmental liabilities	2,448	2,416	4,878	4,706
Depreciation and amortization	72,760	71,531	147,604	143,943
Income from operations	64,353	46,744	75,344	52,177
Other income (expense), net	846	(833)	547	(2,382)
Loss on early extinguishment of debt	0	(6,045)	0	(6,045)
Gain on sale of business	0	31,722	0	31,722
Interest (expense) income, net	(20,769)	(22,492)	(41,039)	(45,068)
Equity in earnings of subsidiaries, net of taxes	0	0	0	0
Intercompany interest income (expense)	0	0	0	0
Income before (benefit) provision for income taxes	44,430	49,096	34,852	30,404
(Benefit) provision for income taxes	13,683	23,216	16,736	25,917
Net income	30,747	25,880	18,116	4,487
Other comprehensive loss	(4,942)	15,098	(21,688)	21,149
Comprehensive income (loss)	25,805	40,978	(3,572)	25,636
Reportable Legal Entities | Clean Harbors, Inc.
Revenues:
Total revenues	0	0	0	0
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	0	0	0	0
Selling, general and administrative expenses	133	27	168	51
Accretion of environmental liabilities	0	0	0	0
Depreciation and amortization	0	0	0	0
Income from operations	(133)	(27)	(168)	(51)
Other income (expense), net	0	(76)	0	(222)
Loss on early extinguishment of debt		(6,045)		(6,045)
Gain on sale of business		0		0
Interest (expense) income, net	(21,216)	(22,614)	(42,215)	(45,273)
Equity in earnings of subsidiaries, net of taxes	46,118	43,167	48,632	35,530
Intercompany interest income (expense)	0	0	0	0
Income before (benefit) provision for income taxes	24,769	14,405	6,249	(16,061)
(Benefit) provision for income taxes	(5,978)	(11,475)	(11,867)	(20,548)
Net income	30,747	25,880	18,116	4,487
Other comprehensive loss	(4,942)	15,098	(21,688)	21,149
Comprehensive income (loss)	25,805	40,978	(3,572)	25,636
Reportable Legal Entities | Guarantor Subsidiaries
Revenues:
Total revenues	682,412	600,660	1,285,477	1,160,615
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	464,086	405,605	887,304	796,255
Selling, general and administrative expenses	105,022	92,504	198,865	184,675
Accretion of environmental liabilities	2,194	2,181	4,370	4,236
Depreciation and amortization	52,864	51,937	106,568	103,837
Income from operations	58,246	48,433	88,370	71,612
Other income (expense), net	269	(406)	184	(1,795)
Loss on early extinguishment of debt		0		0
Gain on sale of business		31,722		31,722
Interest (expense) income, net	238	240	743	359
Equity in earnings of subsidiaries, net of taxes	2,230	(5,332)	(17,832)	(27,156)
Intercompany interest income (expense)	1,084	1,268	2,445	2,565
Income before (benefit) provision for income taxes	62,067	75,925	73,910	77,307
(Benefit) provision for income taxes	18,228	31,981	27,329	41,618
Net income	43,839	43,944	46,581	35,689
Other comprehensive loss	(4,942)	15,098	(21,688)	21,149
Comprehensive income (loss)	38,897	59,042	24,893	56,838
Reportable Legal Entities | Non-Guarantor Subsidiaries
Revenues:
Total revenues	182,798	166,654	346,649	313,056
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	135,568	128,724	275,913	252,075
Selling, general and administrative expenses	20,840	19,763	42,050	39,789
Accretion of environmental liabilities	254	235	508	470
Depreciation and amortization	19,896	19,594	41,036	40,106
Income from operations	6,240	(1,662)	(12,858)	(19,384)
Other income (expense), net	577	(351)	363	(365)
Loss on early extinguishment of debt		0		0
Gain on sale of business		0		0
Interest (expense) income, net	209	(118)	433	(154)
Equity in earnings of subsidiaries, net of taxes	0	0	0	0
Intercompany interest income (expense)	(1,084)	(1,268)	(2,445)	(2,565)
Income before (benefit) provision for income taxes	5,942	(3,399)	(14,507)	(22,468)
(Benefit) provision for income taxes	1,433	2,710	1,274	4,847
Net income	4,509	(6,109)	(15,781)	(27,315)
Other comprehensive loss	(10,435)	12,837	(24,442)	17,869
Comprehensive income (loss)	(5,926)	6,728	(40,223)	(9,446)
Consolidating Adjustments
Revenues:
Total revenues	(16,070)	(14,526)	(33,208)	(31,942)
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	(16,070)	(14,526)	(33,208)	(31,942)
Selling, general and administrative expenses	0	0	0	0
Accretion of environmental liabilities	0	0	0	0
Depreciation and amortization	0	0	0	0
Income from operations	0	0	0	0
Other income (expense), net	0	0	0	0
Loss on early extinguishment of debt		0		0
Gain on sale of business		0		0
Interest (expense) income, net	0	0	0	0
Equity in earnings of subsidiaries, net of taxes	(48,348)	(37,835)	(30,800)	(8,374)
Intercompany interest income (expense)	0	0	0	0
Income before (benefit) provision for income taxes	(48,348)	(37,835)	(30,800)	(8,374)
(Benefit) provision for income taxes	0	0	0	0
Net income	(48,348)	(37,835)	(30,800)	(8,374)
Other comprehensive loss	15,377	(27,935)	46,130	(39,018)
Comprehensive income (loss)	(32,971)	(65,770)	15,330	(47,392)
Service
Revenues:
Total revenues	696,779	610,940	1,316,498	1,171,154
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	473,423	412,356	921,072	803,443
Service | Reportable Legal Entities | Clean Harbors, Inc.
Revenues:
Total revenues	0	0	0	0
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	0	0	0	0
Service | Reportable Legal Entities | Guarantor Subsidiaries
Revenues:
Total revenues	544,521	474,801	1,026,004	918,106
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	361,644	306,960	689,824	601,105
Service | Reportable Legal Entities | Non-Guarantor Subsidiaries
Revenues:
Total revenues	165,435	147,924	317,836	278,995
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	124,956	117,181	258,590	228,285
Service | Consolidating Adjustments
Revenues:
Total revenues	(13,177)	(11,785)	(27,342)	(25,947)
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	(13,177)	(11,785)	(27,342)	(25,947)
Product
Revenues:
Total revenues	152,361	141,848	282,420	270,575
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	110,161	107,447	208,937	212,945
Product | Reportable Legal Entities | Clean Harbors, Inc.
Revenues:
Total revenues	0	0	0	0
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	0	0	0	0
Product | Reportable Legal Entities | Guarantor Subsidiaries
Revenues:
Total revenues	137,891	125,859	259,473	242,509
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	102,442	98,645	197,480	195,150
Product | Reportable Legal Entities | Non-Guarantor Subsidiaries
Revenues:
Total revenues	17,363	18,730	28,813	34,061
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	10,612	11,543	17,323	23,790
Product | Consolidating Adjustments
Revenues:
Total revenues	(2,893)	(2,741)	(5,866)	(5,995)
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	$ (2,893)	$ (2,741)	$ (5,866)	$ (5,995)

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GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Condensed consolidating statement of cash flows
Net cash from operating activities	$ 129,670	$ 116,931
Cash flows used in investing activities:
Additions to property, plant and equipment	(94,139)	(88,742)
Proceeds from sale and disposal of fixed assets	2,641	2,121
Acquisitions, net of cash acquired	(123,750)	(9,277)
Proceeds from sale of businesses, net of transactional costs	0	46,391
Additions to intangible assets, including costs to obtain or renew permits	(2,106)	(1,239)
Proceeds from sale of available-for-sale securities	11,214
Purchases of available-for-sale securities	(10,001)	0
Proceeds from sale of available-for-sale securities		376
Intercompany	0	0
Net cash used in investing activities	(216,141)	(50,370)
Cash flows (used in) from financing activities:
Change in uncashed checks	(2,803)	(8,361)
Proceeds from exercise of stock options	0	46
Tax payments related to withholdings on vested restricted stock	(2,175)	(2,132)
Repurchases of common stock	(26,482)	(12,257)
Deferred financing costs paid	(468)	(4,727)
Premiums paid on early extinguishment of debt	0	(4,665)
Principal payment on debt	(2,000)	(296,202)
Issuance of senior secured notes, net of discount		399,000
Intercompany	0	0
Net cash (used in) from financing activities	(33,928)	70,702
Effect of exchange rate change on cash	(1,932)	2,106
Increase (decrease) in cash and cash equivalents	(122,331)	139,369
Cash and cash equivalents, beginning of period	319,399	306,997
Cash and cash equivalents, end of period	197,068	446,366
Consolidating Adjustments
Condensed consolidating statement of cash flows
Net cash from operating activities	0	0
Cash flows used in investing activities:
Additions to property, plant and equipment	0	0
Proceeds from sale and disposal of fixed assets	0	0
Acquisitions, net of cash acquired	0	0
Proceeds from sale of businesses, net of transactional costs		0
Additions to intangible assets, including costs to obtain or renew permits	0	0
Proceeds from sale of available-for-sale securities	0
Purchases of available-for-sale securities	0
Proceeds from sale of available-for-sale securities		0
Intercompany	30,657	14,343
Net cash used in investing activities	30,657	14,343
Cash flows (used in) from financing activities:
Change in uncashed checks	0	0
Proceeds from exercise of stock options		0
Tax payments related to withholdings on vested restricted stock	0	0
Repurchases of common stock	0	0
Deferred financing costs paid	0	0
Premiums paid on early extinguishment of debt		0
Principal payment on debt	0	0
Issuance of senior secured notes, net of discount		0
Intercompany	(30,657)	(14,343)
Net cash (used in) from financing activities	(30,657)	(14,343)
Effect of exchange rate change on cash	0	0
Increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	0	0
Clean Harbors, Inc. | Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash from operating activities	790	(93,808)
Cash flows used in investing activities:
Additions to property, plant and equipment	0	0
Proceeds from sale and disposal of fixed assets	0	0
Acquisitions, net of cash acquired	0	0
Proceeds from sale of businesses, net of transactional costs		0
Additions to intangible assets, including costs to obtain or renew permits	0	0
Proceeds from sale of available-for-sale securities	0
Purchases of available-for-sale securities	0
Proceeds from sale of available-for-sale securities		376
Intercompany	0	0
Net cash used in investing activities	0	376
Cash flows (used in) from financing activities:
Change in uncashed checks	0	0
Proceeds from exercise of stock options		46
Tax payments related to withholdings on vested restricted stock	(2,175)	(2,132)
Repurchases of common stock	(26,482)	(12,257)
Deferred financing costs paid	(468)	(4,727)
Premiums paid on early extinguishment of debt		(4,665)
Principal payment on debt	(2,000)	(296,202)
Issuance of senior secured notes, net of discount		399,000
Intercompany	30,657	14,343
Net cash (used in) from financing activities	(468)	93,406
Effect of exchange rate change on cash	0	0
Increase (decrease) in cash and cash equivalents	322	(26)
Cash and cash equivalents, beginning of period	51,638	51,417
Cash and cash equivalents, end of period	51,960	51,391
Guarantor Subsidiaries | Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash from operating activities	121,021	206,496
Cash flows used in investing activities:
Additions to property, plant and equipment	(77,773)	(75,152)
Proceeds from sale and disposal of fixed assets	1,035	984
Acquisitions, net of cash acquired	(123,750)	(9,277)
Proceeds from sale of businesses, net of transactional costs		46,210
Additions to intangible assets, including costs to obtain or renew permits	(1,991)	(888)
Proceeds from sale of available-for-sale securities	0
Purchases of available-for-sale securities	0
Proceeds from sale of available-for-sale securities		0
Intercompany	(30,657)	(14,343)
Net cash used in investing activities	(233,136)	(52,466)
Cash flows (used in) from financing activities:
Change in uncashed checks	(2,829)	(5,977)
Proceeds from exercise of stock options		0
Tax payments related to withholdings on vested restricted stock	0	0
Repurchases of common stock	0	0
Deferred financing costs paid	0	0
Premiums paid on early extinguishment of debt		0
Principal payment on debt	0	0
Issuance of senior secured notes, net of discount		0
Intercompany	0	0
Net cash (used in) from financing activities	(2,829)	(5,977)
Effect of exchange rate change on cash	0	0
Increase (decrease) in cash and cash equivalents	(114,944)	148,053
Cash and cash equivalents, beginning of period	207,777	155,943
Cash and cash equivalents, end of period	92,833	303,996
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash from operating activities	7,859	4,243
Cash flows used in investing activities:
Additions to property, plant and equipment	(16,366)	(13,590)
Proceeds from sale and disposal of fixed assets	1,606	1,137
Acquisitions, net of cash acquired	0	0
Proceeds from sale of businesses, net of transactional costs		181
Additions to intangible assets, including costs to obtain or renew permits	(115)	(351)
Proceeds from sale of available-for-sale securities	11,214
Purchases of available-for-sale securities	(10,001)
Proceeds from sale of available-for-sale securities		0
Intercompany	0	0
Net cash used in investing activities	(13,662)	(12,623)
Cash flows (used in) from financing activities:
Change in uncashed checks	26	(2,384)
Proceeds from exercise of stock options		0
Tax payments related to withholdings on vested restricted stock	0	0
Repurchases of common stock	0	0
Deferred financing costs paid	0	0
Premiums paid on early extinguishment of debt		0
Principal payment on debt	0	0
Issuance of senior secured notes, net of discount		0
Intercompany	0	0
Net cash (used in) from financing activities	26	(2,384)
Effect of exchange rate change on cash	(1,932)	2,106
Increase (decrease) in cash and cash equivalents	(7,709)	(8,658)
Cash and cash equivalents, beginning of period	59,984	99,637
Cash and cash equivalents, end of period	$ 52,275	$ 90,979