OPERATING SEGMENTS - Reconciliation of EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Reconciliation of Net Income to Adjusted EBITDA
Net loss	$ (9,022)	$ (796)
Income tax benefit	(2,014)	(1,444)
Interest expense	6,821	7,357
Interest income	(229)	(273)
Foreign currency loss	698	371
Other income	(177)	(3,710)
Depreciation and amortization of plant and equipment	16,900	18,234
Amortization of intangibles assets	7,872	9,135
Share-based compensation	1,948	1,928
Accretion and non-cash adjustment of closure & post-closure liabilities	1,227	1,182
Business development and integration expenses	5,859	1,220
Adjusted EBITDA	29,883	33,204
Operating Segment | Environmental Services
Reconciliation of Net Income to Adjusted EBITDA
Adjusted EBITDA	41,418	40,136
Operating Segment | Field & Industrial Services
Reconciliation of Net Income to Adjusted EBITDA
Adjusted EBITDA	10,922	17,137
Operating Segment | Energy Waste
Reconciliation of Net Income to Adjusted EBITDA
Adjusted EBITDA	4,725	1,258
Corporate
Reconciliation of Net Income to Adjusted EBITDA
Adjusted EBITDA	$ (27,182)	$ (25,327)