OPERATING SEGMENTS - Summarized Financial Information (Details) $ in Thousands	3 Months Ended
Mar. 31, 2020 USD ($) segment	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
OPERATING SEGMENTS
Number of reportable segments \| segment	2
Revenue	$ 240,720	$ 131,037
Depreciation, amortization and accretion	28,685	12,061
Capital expenditures	19,131	7,223
Total assets	1,978,639	933,332	$ 2,231,244
Treatment and disposal
OPERATING SEGMENTS
Revenue	110,033	80,509
Transportation and Logistics
OPERATING SEGMENTS
Revenue	32,850	21,712
Remediation
OPERATING SEGMENTS
Revenue	10,441	1,726
Other
OPERATING SEGMENTS
Revenue	4,963	1,125
Corporate
OPERATING SEGMENTS
Depreciation, amortization and accretion	628	304
Capital expenditures	2,310	333
Total assets	102,594	68,580
Environmental Services \| Operating Segment
OPERATING SEGMENTS
Revenue	126,745	92,332
Depreciation, amortization and accretion	16,042	9,625
Capital expenditures	11,532	6,712
Total assets	997,271	703,453
Environmental Services \| Operating Segment \| Treatment and disposal
OPERATING SEGMENTS
Revenue	100,049	77,713
Environmental Services \| Operating Segment \| Transportation and Logistics
OPERATING SEGMENTS
Revenue	26,696	14,619
Field and Industrial Services \| Operating Segment
OPERATING SEGMENTS
Revenue	113,975	38,705
Depreciation, amortization and accretion	12,015	2,132
Capital expenditures	5,289	178
Total assets	878,774	161,299
Field and Industrial Services \| Operating Segment \| Treatment and disposal
OPERATING SEGMENTS
Revenue	9,984	2,796
Field and Industrial Services \| Operating Segment \| Transportation and Logistics
OPERATING SEGMENTS
Revenue	6,154	7,093
Field and Industrial Services \| Operating Segment \| Remediation
OPERATING SEGMENTS
Revenue	10,441	1,726
Field and Industrial Services \| Operating Segment \| Other
OPERATING SEGMENTS
Revenue	$ 4,963	$ 1,125

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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