Segment Information - Components of Segment Revenues and Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Segment Revenues	$ 132,578	$ 84,705	$ 402,619	$ 219,502
Segment Adjusted EBITDA	21,487	16,706	59,249	36,157
Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	132,578	84,705	402,619	219,502
Segment Adjusted EBITDA	29,474	21,468	81,275	51,582
Assessment, Permitting and Response | Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	63,412	26,593	209,379	49,768
Segment Adjusted EBITDA	15,719	8,230	46,379	14,665
Measurement and Analysis | Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	38,752	39,770	111,309	113,130
Segment Adjusted EBITDA	8,283	11,226	22,634	30,422
Remediation and Reuse | Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	30,414	18,342	81,931	56,604
Segment Adjusted EBITDA	5,472	2,012	12,262	6,495
Corporate and Other
Segment Reporting Information [Line Items]
Segment Adjusted EBITDA	$ (7,987)	$ (4,762)	$ (22,026)	$ (15,425)