The Company tests each of its reporting units for goodwill impairment annually on October 1, or upon a triggering event, in accordance with ASC Topic 350, “Intangibles –Goodwill and Other.” Effective in the first quarter of 2026, the Company reorganized its business into two reportable segments as discussed in Note 19 – Segment Information. This changed the composition of the Company's reporting units which resulted in the combination of historical goodwill from the Assessment, Permitting and Response and Remediation and Reuse segments to its newly created Consulting and Treatment segment. Additionally, the change in composition of the Company's reporting units was considered a triggering event requiring an interim goodwill impairment test as of March 31, 2026. The Company determined that no impairment existed as the estimated fair values of its reporting units were in excess of their respective carrying values, both before and after the reorganization. Amounts related to goodwill are as follows:


	Consulting and Treatment			Measurement and Analysis			Total
Balance as of December 31, 2025	$	347,706		$	119,080		$	466,786
Foreign currency translation adjustments		(101	)		(489	)		(590	)
Balance as of September 30, 2026	$	347,605		$	118,591		$	466,196

Amounts related to finite-lived intangible assets are as follows:


September 30, 2026	Gross Balance		Accumulated Amortization		Total Intangible Assets—Net
Customer relationships	$	267,634	$	175,130	$	92,504
Covenants not to compete		42,239		37,852		4,387
Trade names		25,949		25,855		94
Proprietary software		33,647		27,720		5,927
Patent		17,479		7,695		9,784
Total other intangible assets, net	$	386,948	$	274,252	$	112,696

December 31, 2025	Gross Balance		Accumulated Amortization		Total Intangible Assets—Net
Customer relationships	$	264,564	$	160,459	$	104,105
Covenants not to compete		41,418		36,293		5,125
Trade names		25,917		25,441		476
Proprietary software		31,982		25,912		6,070
Patent		17,479		6,872		10,607
Total other intangible assets, net	$	381,360	$	254,977	$	126,383

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 $6.3 million and $19.7 million for the three and nine months ended September 30, 2026, respectively, and $7.3 million and $23.0 million for the three and nine months ended September 30, 2025, respectively.

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


December 31,
2026 (remaining)	$	6,401
2027		25,772
2028		20,089
2029		13,674
2030		9,642
Thereafter		37,118
Total	$	112,696

As described in Note 7, on September 15, 2026, the Company acquired certain assets for a purchase price of $5.1 million, paid in cash, in a transaction accounted for as an asset acquisition. Approximately $0.5 million of the purchase price was transferred to an escrow account not controlled by the Company and will be released in accordance with the terms of the escrow agreement. The purchase price was allocated to the assets acquired on a relative fair value basis, with $3.3 million allocated to customer relationships, $0.8 million allocated to covenants not to compete, and $1.0 million in the aggregate allocated to accounts receivable, property and equipment, and other current assets. No goodwill was recognized. The acquired intangible assets, totaling $4.1 million, are being amortized on a straight-line basis over a weighted-average amortization period of approximately 6.6 years, with customer relationships amortized over seven years and covenants not to compete over five years.