REVENUES (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) segment	Mar. 31, 2019 USD ($)
Disaggregation of revenue
Number of reportable segments | segment	2
Revenue	$ 240,720	$ 131,037
Treatment and disposal
Disaggregation of revenue
Revenue	110,033	80,509
Transportation and Logistics
Disaggregation of revenue
Revenue	32,850	21,712
Industrial Services
Disaggregation of revenue
Revenue	28,478	6,016
Small Quantity Generation
Disaggregation of revenue
Revenue	11,084	8,189
Total Waste Management
Disaggregation of revenue
Revenue	8,482	8,714
Remediation
Disaggregation of revenue
Revenue	10,441	1,726
Emergency Response
Disaggregation of revenue
Revenue	24,922	3,046
Domestic Standby Services
Disaggregation of revenue
Revenue	9,467
Other
Disaggregation of revenue
Revenue	4,963	1,125
Operating Segment | Environmental Services
Disaggregation of revenue
Revenue	126,745	92,332
Operating Segment | Field and Industrial Services
Disaggregation of revenue
Revenue	113,975	38,705
Operating Segment | Treatment and disposal | Environmental Services
Disaggregation of revenue
Revenue	100,049	77,713
Operating Segment | Treatment and disposal | Field and Industrial Services
Disaggregation of revenue
Revenue	9,984	2,796
Operating Segment | Transportation and Logistics | Environmental Services
Disaggregation of revenue
Revenue	26,696	14,619
Operating Segment | Transportation and Logistics | Field and Industrial Services
Disaggregation of revenue
Revenue	6,154	7,093
Operating Segment | Industrial Services | Field and Industrial Services
Disaggregation of revenue
Revenue	28,478	6,016
Operating Segment | Small Quantity Generation | Field and Industrial Services
Disaggregation of revenue
Revenue	11,084	8,189
Operating Segment | Total Waste Management | Field and Industrial Services
Disaggregation of revenue
Revenue	8,482	8,714
Operating Segment | Remediation | Field and Industrial Services
Disaggregation of revenue
Revenue	10,441	1,726
Operating Segment | Emergency Response | Field and Industrial Services
Disaggregation of revenue
Revenue	24,922	3,046
Operating Segment | Domestic Standby Services | Field and Industrial Services
Disaggregation of revenue
Revenue	9,467
Operating Segment | Other | Field and Industrial Services
Disaggregation of revenue
Revenue	$ 4,963	$ 1,125