REVENUES (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) segment item	Mar. 31, 2017 USD ($)
Disaggregation of revenue
Number of primary sources for recognizing revenue | item	3
Number of reportable segments | segment	2
Revenue	$ 120,059
Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		$ 110,234
Treatment and disposal
Disaggregation of revenue
Revenue	75,038
Treatment and disposal | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		71,340
Transportation and Logistics
Disaggregation of revenue
Revenue	19,867
Transportation and Logistics | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		17,920
Industrial Cleaning
Disaggregation of revenue
Revenue	3,505
Industrial Cleaning | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		4,219
Technical Services
Disaggregation of revenue
Revenue	20,405
Technical Services | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		15,662
Remediation
Disaggregation of revenue
Revenue	353
Remediation | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		606
Other
Disaggregation of revenue
Revenue	891
Other | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of revenue
Revenue		487
Operating Segment | Environmental Services
Disaggregation of revenue
Revenue	86,471
Operating Segment | Field and Industrial Services
Disaggregation of revenue
Revenue	33,588
Operating Segment | Calculated under Revenue Guidance in Effect before Topic 606 | Environmental Services
Disaggregation of revenue
Revenue		81,303
Operating Segment | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		28,931
Operating Segment | Treatment and disposal | Environmental Services
Disaggregation of revenue
Revenue	72,301
Operating Segment | Treatment and disposal | Field and Industrial Services
Disaggregation of revenue
Revenue	2,737
Operating Segment | Treatment and disposal | Calculated under Revenue Guidance in Effect before Topic 606 | Environmental Services
Disaggregation of revenue
Revenue		68,703
Operating Segment | Treatment and disposal | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		2,637
Operating Segment | Transportation and Logistics | Environmental Services
Disaggregation of revenue
Revenue	14,170
Operating Segment | Transportation and Logistics | Field and Industrial Services
Disaggregation of revenue
Revenue	5,697
Operating Segment | Transportation and Logistics | Calculated under Revenue Guidance in Effect before Topic 606 | Environmental Services
Disaggregation of revenue
Revenue		12,600
Operating Segment | Transportation and Logistics | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		5,320
Operating Segment | Industrial Cleaning | Field and Industrial Services
Disaggregation of revenue
Revenue	3,505
Operating Segment | Industrial Cleaning | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		4,219
Operating Segment | Technical Services | Field and Industrial Services
Disaggregation of revenue
Revenue	20,405
Operating Segment | Technical Services | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		15,662
Operating Segment | Remediation | Field and Industrial Services
Disaggregation of revenue
Revenue	353
Operating Segment | Remediation | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		606
Operating Segment | Other | Field and Industrial Services
Disaggregation of revenue
Revenue	$ 891
Operating Segment | Other | Calculated under Revenue Guidance in Effect before Topic 606 | Field and Industrial Services
Disaggregation of revenue
Revenue		$ 487