REVENUES (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)
Disaggregation of revenue
Number of reportable segments | segment			2
Revenue	$ 213,918	$ 155,802	$ 454,638	$ 286,839
Environmental Services
Disaggregation of revenue
Revenue				205,177
Field and Industrial Services
Disaggregation of revenue
Revenue				81,662
Treatment and disposal
Disaggregation of revenue
Revenue	100,920	93,512	210,889	174,021
Treatment and disposal | Environmental Services
Disaggregation of revenue
Revenue				168,092
Treatment and disposal | Field and Industrial Services
Disaggregation of revenue
Revenue				5,929
Transportation and Logistics
Disaggregation of revenue
Revenue	26,361	35,225	59,394	56,937
Transportation and Logistics | Environmental Services
Disaggregation of revenue
Revenue				37,085
Transportation and Logistics | Field and Industrial Services
Disaggregation of revenue
Revenue				19,852
Industrial Services
Disaggregation of revenue
Revenue	28,566	4,963	57,064	10,980
Industrial Services | Field and Industrial Services
Disaggregation of revenue
Revenue				10,980
Small Quantity Generation
Disaggregation of revenue
Revenue	11,159	9,326	22,236	17,515
Small Quantity Generation | Field and Industrial Services
Disaggregation of revenue
Revenue				17,515
Total Waste Management
Disaggregation of revenue
Revenue	6,848	8,004	15,317	16,719
Total Waste Management | Field and Industrial Services
Disaggregation of revenue
Revenue				16,719
Remediation
Disaggregation of revenue
Revenue	3,117	889	13,349	2,616
Remediation | Field and Industrial Services
Disaggregation of revenue
Revenue				2,616
Emergency Response
Disaggregation of revenue
Revenue	23,168	3,180	48,188	6,226
Emergency Response | Field and Industrial Services
Disaggregation of revenue
Revenue				6,226
Domestic Standby Services
Disaggregation of revenue
Revenue	8,102		17,569
Other
Disaggregation of revenue
Revenue	5,677	703	10,632	1,825
Other | Field and Industrial Services
Disaggregation of revenue
Revenue				1,825
Operating Segment | Environmental Services
Disaggregation of revenue
Revenue	110,409	112,844	237,154	205,177
Operating Segment | Field and Industrial Services
Disaggregation of revenue
Revenue	103,509	42,958	217,484	$ 81,662
Operating Segment | Treatment and disposal | Environmental Services
Disaggregation of revenue
Revenue	90,955	90,379	191,005
Operating Segment | Treatment and disposal | Field and Industrial Services
Disaggregation of revenue
Revenue	9,965	3,133	19,884
Operating Segment | Transportation and Logistics | Environmental Services
Disaggregation of revenue
Revenue	19,454	22,465	46,149
Operating Segment | Transportation and Logistics | Field and Industrial Services
Disaggregation of revenue
Revenue	6,907	12,760	13,245
Operating Segment | Industrial Services | Field and Industrial Services
Disaggregation of revenue
Revenue	28,566	4,963	57,064
Operating Segment | Small Quantity Generation | Field and Industrial Services
Disaggregation of revenue
Revenue	11,159	9,326	22,236
Operating Segment | Total Waste Management | Field and Industrial Services
Disaggregation of revenue
Revenue	6,848	8,004	15,317
Operating Segment | Remediation | Field and Industrial Services
Disaggregation of revenue
Revenue	3,117	889	13,349
Operating Segment | Emergency Response | Field and Industrial Services
Disaggregation of revenue
Revenue	23,168	3,180	48,188
Operating Segment | Domestic Standby Services | Field and Industrial Services
Disaggregation of revenue
Revenue	8,102		17,569
Operating Segment | Other | Field and Industrial Services
Disaggregation of revenue
Revenue	$ 5,677	$ 703	$ 10,632