Changes in goodwill for the years ended December 31, 2021 and 2020 were as follows:

We assess goodwill for impairment during the fourth quarter as of October 1 of each year, and also if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. The assessment consists of comparing the fair value of the reporting unit to the carrying value of the net assets assigned to the reporting unit, including goodwill.

Fair values are generally determined by an income approach, discounting projected future cash flows based on our expectations of the current and future operating environment, using a market approach, applying a multiple of earnings based on guideline for publicly traded companies, or a combination thereof. Estimating future cash flows requires significant judgment about factors such as general economic conditions and projected growth rates, and our estimates often vary from the cash flows eventually realized. The rates used to discount projected future cash flows reflect a weighted average cost of capital based on our industry, capital structure and risk premiums including those reflected in the current market capitalization. In the event the fair value of a reporting unit exceeds its carrying amount, goodwill of the reporting unit is considered not impaired. If the carrying amount of a reporting unit exceeds its fair value, goodwill of the reporting unit is considered impaired, and an impairment charge would be recognized during the period in which the determination has been made for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized will not exceed the total amount of goodwill allocated to that reporting unit.

Assessing impairment inherently involves management judgments as to the assumptions used to calculate fair value of the reporting units and the impact of market conditions on those assumptions. The key inputs that management uses in its assumptions to estimate the fair value of our reporting units under the income-based approach are as follows:

To develop the projected cash flows of our reporting units, management considers factors that may impact the revenue streams within each reporting unit. These factors include, but are not limited to, economic conditions on both a global scale and specifically in the regions in which the reporting units operate, customer relationships, strategic plans and opportunities, required returns on invested capital and competition from other service providers. With regard to operating margins, management considers its historical reporting unit operating margins on the revenue streams within each

reporting unit, adjusting historical margins for the projected impact of current market trends on both fixed and variable costs.

Expected future after-tax operating cash flows of each reporting unit are discounted to a present value using a risk-adjusted discount rate. Estimates of future cash flows require management to make significant assumptions regarding future operating performance including the projected mix of revenue streams within each reporting unit, projected operating margins, the amount and timing of capital investments and the overall probability of achieving the projected cash flows, as well as future economic conditions, which may result in actual future cash flows that are different than management’s estimates. The discount rate, which is intended to reflect the risks inherent in future cash flow projections, used in estimating the present value of future cash flows, is based on estimates of the WACC of market participants relative to the reporting units. Financial and credit market volatility can directly impact certain inputs and assumptions used to develop the WACC.

The result of the annual assessment of goodwill undertaken in the fourth quarter of 2021 indicated that the fair value of each of our reporting units was in excess of its respective carrying value.

In connection with our financial review and forecasting procedures performed during the first quarter of 2020, management determined that the projected future cash flows of our Energy Waste (“EW”) reporting unit and our International reporting unit (described below) indicated that the fair value of such reporting units may be below their respective carrying amounts. Accordingly, we performed an interim assessment of each reporting unit’s fair value as of March 31, 2020 (the “Interim Assessment”). Based on the results of the Interim Assessment, we recognized goodwill impairment charges of $283.6 million related to our EW reporting unit and $16.7 million related to our International reporting unit in the first quarter of 2020. During the fourth quarter of 2020, the Company finalized the purchase price allocation related to the NRC Merger. The finalization of fair value estimates during the fourth quarter of 2020, and resulting final determination of goodwill by reporting unit, resulted in an increase in the amount of goodwill assigned to the EW reporting unit and a decrease in the amount of goodwill assigned to the International reporting unit. $80.3 million of additional goodwill assigned to the EW reporting unit was immediately impaired in the fourth quarter of 2020 based on the fair value of the reporting unit determined in the Interim Assessment. The decrease in goodwill assigned to the International reporting unit resulted in the reversal in the fourth quarter of 2020 of $11.2 million of International reporting unit goodwill impairment charges recorded in the first quarter of 2020.

Our EW reporting unit, the sole component of our Energy Waste segment, provides energy-related services including solid and liquid waste treatment and disposal, equipment cleaning and maintenance, specialty equipment rental, spill containment and site remediation for a full complement of oil and gas waste streams, predominately to upstream energy customers currently concentrated in the Eagle Ford and Permian Basins in Texas. Our International reporting unit, a component of our Field Services segment, provides industrial and emergency response services to the offshore oil and gas sector in the North Sea and land-based industries across the EMEA region. Both our EW and International reporting units are dependent on energy-related exploration and production investments and expenditures by our energy industry customers. Lower crude oil prices and the volatility of such prices affect the level of investment as it impacts the ability of energy companies to access capital on economically advantageous terms or at all. In addition, energy companies decrease investments when the projected profits are inadequate or uncertain due to lower crude oil prices or volatility in crude oil prices. Such reductions in capital spending negatively impact energy waste generation and therefore the demand for our services.

The principal factors contributing to the goodwill impairment charges for both the EW and International reporting units related to historically-low energy commodity prices reducing anticipated energy-related exploration and production investments and expenditures by our energy industry customers, which negatively impacted each reporting unit’s prospective cash flows and each reporting unit's estimated fair value. A longer-than-expected recovery in crude oil pricing and energy-related exploration and production investments became evident during the first quarter of 2020 as we assessed the projected impact of the COVID-19 pandemic and foreign oil production increases on the global demand for oil and updated the long-term projections for each reporting unit which, as a result, decreased each reporting unit’s anticipated future cash flows as compared to those estimated previously.

Consistent with our annual impairment testing methodology, we utilized a weighted average of (1) an income approach and (2) a market approach to determine the fair value of each of the reporting units for the Interim Assessment. The income approach is based on the estimated present value of future cash flows for each reporting unit. The market approach is based on assumptions about how market data relates to each reporting unit.

The rapid and sustained decline in the energy markets served by our EW and International reporting units, exacerbated by the uncertainty surrounding the impact of the COVID-19 pandemic and foreign oil production increases, has inherently increased the risk associated with the future cash flows of these reporting units. Accordingly, when performing the Interim Assessment, we increased the discount rates and decreased the projected capital investment for each reporting unit compared to the assumptions used in the initial fair value assessment in connection with the NRC Merger on November 1, 2019.

We also considered the estimated fair value of our EW and International reporting units under a market-based approach by applying industry-comparable multiples of revenues and operating earnings to reporting unit revenues and operating earnings. The lack of a broad base of publicly available market data specific to the industry in which we operate, combined with the general market volatility attributable to the COVID-19 pandemic, results in a wide range of currently observable market multiples. Accordingly, we applied less weight to the estimated fair value of our reporting units calculated under the market-based approach (10%) compared to the income approach (90%) described above.

The result of the annual assessment of goodwill undertaken in the fourth quarter of 2020 indicated that the fair value of each of our reporting units was in excess of its respective carrying value, with the exception of our Field Services reporting unit.

Our Field Services reporting unit, a component of our Field Services segment, offers specialty field services and total waste management solutions to commercial and industrial facilities and to government entities through our 10-day transfer facilities and at customer sites. Consistent with prior assessments, we utilized a weighted average of (1) an income approach and (2) a market approach to determine the fair value of each of the Field Services reporting unit. The income approach is based on the estimated present value of future cash flows for the reporting unit. The market approach is based on assumptions about how market data relates to the reporting unit. The estimated fair value of the Field Services reporting unit was then compared to the reporting unit’s carrying amount as of October 1, 2020. Based on the results of that comparison, the carrying amount of the Field Services reporting unit exceeded the estimated fair value of the reporting unit by $14.4 million and, as a result, we recognized a corresponding goodwill impairment charge in the fourth quarter of 2020. The factors contributing to the $14.4 million goodwill impairment charge principally related to an increase in the risk-adjusted rate used to discount the projected cash flows of the reporting unit as a result of the decline in our share price since the last annual assessment as well as a slower than expected recovery to cash flow levels forecasted prior to the COVID-19 pandemic, which negatively impacted the reporting unit’s prospective financial information in its discounted cash flow model and the reporting unit’s estimated fair value as compared to previous estimates.

Intangible assets as of December 31, 2021 and 2020 consisted of the following:


	2021						2020
			Accumulated						Accumulated
$s in thousands	Cost		Amortization		Net		Cost		Amortization		Net
Amortizing intangible assets:
Permits, licenses and lease	$	174,959	$	(27,170)	$	147,789	$	174,885	$	(23,005)	$	151,880
Customer relationships		340,065		(87,952)		252,113		340,032		(61,778)		278,254
Technology - formulae and processes		7,166		(2,531)		4,635		7,142		(2,293)		4,849
Customer backlog		3,652		(2,752)		900		3,652		(2,387)		1,265
Tradename		10,390		(10,390)		—		10,390		(8,015)		2,375
Developed software		2,903		(2,475)		428		2,902		(2,182)		720
Non-compete agreements		5,573		(5,211)		362		5,571		(4,318)		1,253
Internet domain and website		536		(213)		323		536		(184)		352
Database		390		(235)		155		389		(214)		175
Total amortizing intangible assets		545,634		(138,929)		406,705		545,499		(104,376)		441,123
Non-amortizing intangible assets:
Permits and licenses		82,734		—		82,734		82,732		—		82,732
Tradename		134		—		134		133		—		133
Total intangible assets	$	628,502	$	(138,929)	$	489,573	$	628,364	$	(104,376)	$	523,988

We review non-amortizing intangible assets for impairment during the fourth quarter as of October 1 of each year. Fair value is generally determined by considering an internally developed discounted projected cash flow analysis. Estimating future cash flows requires significant judgment about factors such as general economic conditions and projected growth rates, and our estimates often vary from the cash flows eventually realized. If the fair value of an asset is determined to be less than the carrying amount of the intangible asset, an impairment in the amount of the difference is recorded in the period in which the annual assessment occurs.

The results of the annual assessment of non-amortizing intangible assets undertaken in the fourth quarter of 2021 indicated no impairment charges were required.

The results of the annual assessment of non-amortizing intangible assets undertaken in the fourth quarter of 2020 indicated no impairment charges were required, with the exception of certain non-amortizing permit intangibles within our Field Services segment.

Our Field Services segment provides government-mandated, commercial standby oil spill compliance solutions to companies that store, transport, produce or handle petroleum and certain nonpetroleum oils on or near U.S. waters. A company’s ability to provide these standby services is subject to significant regulatory certification requirements and other high barriers to entry. As such, the Company assigned $57.1 million of fair value to non-amortizing standby services permit intangible assets upon finalization of the purchase accounting allocation related to the NRC Merger. In performing the annual indefinite-lived intangible assets impairment tests, the estimated fair value of the standby services permits was determined under an income approach using discounted projected future cash flows associated with the permits and then compared to the $57.1 million carrying amount of the permits as of October 1, 2020. Based on the results of that evaluation, the carrying amount of the permits exceeded the estimated fair value of the permits and, as a result, we recognized a $21.1 million impairment charge in the fourth quarter of 2020. The factors contributing to the impairment charge principally related to a less favorable outlook on the potential for both significant oil spill events and growth opportunities, which negatively impacted the discounted projected cash flows associated with the standby services permits and their estimated fair value as compared to previous estimates.

On November 1, 2019, the Company completed the NRC Merger and recorded $577.4 million of goodwill, $252.1 million of amortizing intangible assets (consisting primarily of customer relationships) and $57.4 million of non-amortizing intangible assets (consisting of permits and licenses) as a result of the acquisition. See Note 5 for additional information.

On January 28, 2020, the Company acquired Impact Environmental Services, Inc. and recorded $300,000 of goodwill and $900,000 of amortizing intangible assets (consisting primarily of customer relationships). See Note 5 for additional information.

On August 1, 2019, the Company acquired US Ecology Sarnia and recorded $7.7 million of goodwill and $6.2 million of amortizing intangible assets (consisting primarily of customer relationships) as a result of the acquisition. See Note 5 for additional information.

Amortization expense relating to intangible assets was $34.6 million, $37.3 million and $15.5 million for the years ended December 31, 2021, 2020 and 2019, respectively.

Foreign intangible asset carrying amounts are affected by foreign currency translation. Future amortization expense of amortizing intangible assets is expected to be as follows:


	Expected
$s in thousands	Amortization
2022	$	31,403
2023		31,216
2024		30,830
2025		30,586
2026		29,767
Thereafter		252,903
	$	406,705