Segment Information - Components of Segment Revenues and Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Segment Revenues	$ 84,705	$ 57,623	$ 219,502	$ 165,978
Segment Adjusted EBITDA	16,706	8,219	36,157	21,836
Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	84,705	57,623	219,502	165,978
Segment Adjusted EBITDA	21,468	11,786	51,582	32,771
Assessment, Permitting and Response | Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	26,593	5,413	49,768	15,017
Segment Adjusted EBITDA	8,230	1,695	14,665	5,693
Measurement and Analysis | Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	39,770	35,672	113,130	98,521
Segment Adjusted EBITDA	11,226	7,691	30,422	19,761
Remediation and Reuse | Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	18,342	16,538	56,604	52,440
Segment Adjusted EBITDA	2,012	2,400	6,495	7,317
Corporate and Other
Segment Reporting Information [Line Items]
Segment Adjusted EBITDA	$ (4,762)	$ (3,567)	$ (15,425)	$ (10,935)