Goodwill and Intangible Assets

6 Months Ended

Jun. 30, 2020

Goodwill And Intangible Assets Disclosure [Abstract]

7. GOODWILL AND INTANGIBLE ASSETS

Amounts related to goodwill as of June 30, 2020 and December 31, 2019 are as follows:

	Assessment, Permitting and Response		Measurements and Analysis		Remediation and Reuse		Total
Balance as of December 31, 2019	$	15,173	$	68,628	$	43,257	$	127,058
Goodwill acquired during the period		146,038		—		—		146,038
Balance as of June 30, 2020	$	161,211	$	68,628	$	43,257	$	273,096

Amounts related to finite-lived intangible assets as of June 30, 2020 and December 31, 2019 are as follows:

June 30, 2020	Estimated Useful Life	Gross Balance		Accumulated Amortization		Total Intangible Assets—Net
Finite lived intangible assets
Customer relationships	7–15 years	$	164,782	$	44,665	$	120,117
Covenants not to compete	4–5 years		29,832		19,424		10,408
Trade names	1–5 years		16,943		11,518		5,425
Proprietary software	3-5 years		19,561		2,865		16,696
Patent	16 years		17,479		851		16,628
Total other intangible assets—net		$	248,597	$	79,323	$	169,274

December 31, 2019	Estimated Useful Life	Gross Balance		Accumulated Amortization		Total Intangible Assets—Net
Finite lived intangible assets
Customer relationships	7–10 years	$	108,782	$	36,700	$	72,082
Covenants not to compete	4–5 years		25,832		17,572		8,260
Trade names	1–5 years		12,738		10,230		2,508
Proprietary software	3 years		3,885		1,359		2,526
Patent	16 years		17,479		306		17,173
Total other intangible assets—net		$	168,716	$	66,167	$	102,549

Intangible assets with finite lives are stated at cost, less accumulated amortization and impairment losses, if any. These intangible assets are amortized using the straight-line method over the estimated useful lives of the assets.

Amortization expense was $7.8 million and $13.3 million for the three and six months ended June 30, 2020, respectively and $4.5 million and $9.1 million for the three and six months ended June 30, 2019, respectively.

Future amortization expense is estimated to be as follows for each of the five following years and thereafter:

December 31,
2020 (remaining)	$	15,106
2021		28,043
2022		23,958
2023		20,005
2024		16,929
Thereafter		65,233
	$	169,274