OPERATING SEGMENTS (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) segment	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
OPERATING SEGMENTS
Number of reportable segments | segment	2
Total revenue	$ 139,732	$ 66,019	$ 276,383	$ 119,373
Depreciation, amortization & accretion	12,002	5,821	23,818	10,343
Capital expenditures	10,145	3,883	19,376	8,658
Total assets	863,071	905,385	863,071	905,385	$ 920,319
Treatment and Disposal Revenue
OPERATING SEGMENTS
Total revenue	73,949	47,813	147,928	92,760
Transportation and Logistics
OPERATING SEGMENTS
Total revenue	22,085	10,587	48,979	18,994
Industrial Cleaning
OPERATING SEGMENTS
Total revenue	23,331	4,401	42,448	4,401
Technical Services
OPERATING SEGMENTS
Total revenue	16,827	2,009	30,223	2,009
Remediation
OPERATING SEGMENTS
Total revenue	2,579	1,027	4,239	1,027
Other
OPERATING SEGMENTS
Total revenue	961	182	2,566	182
Corporate
OPERATING SEGMENTS
Depreciation, amortization & accretion	143	174	279	188
Capital expenditures	901	61	1,443	243
Total assets	64,166	80,747	64,166	80,747
Environmental Services | Operating Segment
OPERATING SEGMENTS
Total revenue	91,190	57,162	182,615	110,516
Depreciation, amortization & accretion	8,834	5,159	17,504	9,667
Capital expenditures	6,149	3,234	13,084	7,827
Total assets	599,607	626,996	599,607	626,996
Environmental Services | Operating Segment | Treatment and Disposal Revenue
OPERATING SEGMENTS
Total revenue	73,949	47,813	147,928	92,760
Environmental Services | Operating Segment | Transportation and Logistics
OPERATING SEGMENTS
Total revenue	17,241	9,349	34,687	17,756
Field & Industrial Services | Operating Segment
OPERATING SEGMENTS
Total revenue	48,542	8,857	93,768	8,857
Depreciation, amortization & accretion	3,025	488	6,035	488
Capital expenditures	3,095	588	4,849	588
Total assets	199,298	197,642	199,298	197,642
Field & Industrial Services | Operating Segment | Transportation and Logistics
OPERATING SEGMENTS
Total revenue	4,844	1,238	14,292	1,238
Field & Industrial Services | Operating Segment | Industrial Cleaning
OPERATING SEGMENTS
Total revenue	23,331	4,401	42,448	4,401
Field & Industrial Services | Operating Segment | Technical Services
OPERATING SEGMENTS
Total revenue	16,827	2,009	30,223	2,009
Field & Industrial Services | Operating Segment | Remediation
OPERATING SEGMENTS
Total revenue	2,579	1,027	4,239	1,027
Field & Industrial Services | Operating Segment | Other
OPERATING SEGMENTS
Total revenue	$ 961	$ 182	$ 2,566	$ 182