REVENUES (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) item	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment item	Jun. 30, 2017 USD ($)
Disaggregation of revenue
Number of primary sources for recognizing revenue | item	3		3
Number of reportable segments | segment			2
Revenue	$ 136,912		$ 256,971
Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		$ 126,057		$ 236,291
Treatment and disposal
Disaggregation of revenue
Revenue	81,144		156,182
Treatment and disposal | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		74,139		145,479
Transportation and Logistics
Disaggregation of revenue
Revenue	28,533		48,400
Transportation and Logistics | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		23,296		41,216
Industrial Cleaning
Disaggregation of revenue
Revenue	4,157		7,662
Industrial Cleaning | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		4,705		8,924
Technical Services
Disaggregation of revenue
Revenue	20,780		41,185
Technical Services | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		19,802		35,464
Remediation
Disaggregation of revenue
Revenue	1,325		1,678
Remediation | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		3,217		3,823
Other
Disaggregation of revenue
Revenue	973		1,864
Other | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		898		1,385
Operating Segment | Environmental Services
Disaggregation of revenue
Revenue	98,960		185,431
Operating Segment | Field and Industrial Services
Disaggregation of revenue
Revenue	37,952		71,540
Operating Segment | Calculated under Revenue Guidance in Effect before Topic 606 | Environmental Services
Disaggregation of revenue
Revenue		89,591		170,894
Operating Segment | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		36,466		65,397
Operating Segment | Treatment and disposal | Environmental Services
Disaggregation of revenue
Revenue	77,978		150,279
Operating Segment | Treatment and disposal | Field and Industrial Services
Disaggregation of revenue
Revenue	3,166		5,903
Operating Segment | Treatment and disposal | Calculated under Revenue Guidance in Effect before Topic 606 | Environmental Services
Disaggregation of revenue
Revenue		71,238		139,941
Operating Segment | Treatment and disposal | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		2,901		5,538
Operating Segment | Transportation and Logistics | Environmental Services
Disaggregation of revenue
Revenue	20,982		35,152
Operating Segment | Transportation and Logistics | Field and Industrial Services
Disaggregation of revenue
Revenue	7,551		13,248
Operating Segment | Transportation and Logistics | Calculated under Revenue Guidance in Effect before Topic 606 | Environmental Services
Disaggregation of revenue
Revenue		18,353		30,953
Operating Segment | Transportation and Logistics | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		4,943		10,263
Operating Segment | Industrial Cleaning | Field and Industrial Services
Disaggregation of revenue
Revenue	4,157		7,662
Operating Segment | Industrial Cleaning | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		4,705		8,924
Operating Segment | Technical Services | Field and Industrial Services
Disaggregation of revenue
Revenue	20,780		41,185
Operating Segment | Technical Services | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		19,802		35,464
Operating Segment | Remediation | Field and Industrial Services
Disaggregation of revenue
Revenue	1,325		1,678
Operating Segment | Remediation | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		3,217		3,823
Operating Segment | Other | Field and Industrial Services
Disaggregation of revenue
Revenue	$ 973		$ 1,864
Operating Segment | Other | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		$ 898		$ 1,385