3. REVENUES AND ACCOUNTS RECEIVABLE

The Company’s main revenue sources derive from the following revenue streams:

Consulting and Treatment Revenues are generated from multidisciplinary environmental consulting services, and engineering, design, implementation and operating and maintenance (O&M) services primarily to treat contaminated water and remove contaminants from soil. The majority of the contracts are fixed-fee or time-and-material based.

Measurement and Analysis Revenues are generated from emissions sampling, testing and reporting services, leak detection services, ambient air monitoring services and laboratory testing services. The majority of the contracts are fixed-fee or time-and-materials based.

Disaggregation of Revenue—The Company disaggregates revenue by its operating segments and geographic location. The Company believes disaggregating revenue into these categories achieves the disclosure objectives to depict how the nature, amount, and uncertainty of revenue and cash flows are affected by economic factors. Disaggregated revenue disclosures are provided in Note 19.

Contract Balances—The Company presents contract balances for unbilled receivables (contract assets), as well as customer advances, and deposits and deferred revenue (contract liabilities) within contract assets and accounts payable and other accrued expenses, respectively, on the unaudited condensed consolidated statements of financial position. Amounts are generally billed at periodic intervals (e.g. weekly, bi-weekly or monthly) as work progresses in accordance with agreed-upon contractual terms. The Company utilizes the practical expedient to not adjust the promised amount of consideration for the effects of a significant financing component for arrangements in which the period between when the Company transfers services to a customer and when the customer pays for those services is one year or less. Amounts recorded as unbilled receivables generally arise when billing occurs subsequent to revenue recognition, for example for services the Company is not contractually entitled to bill based on the passage of time. The Company sometimes receives advances or deposits from customers before revenue is recognized, resulting in contract liabilities.

Revenue recognized during the three and six months ended June 30, 2026, included in the contract liabilities balance at the beginning of the year was $3.5 million and $9.2 million, respectively. The revenue recognized from the contract liabilities consisted of the Company satisfying performance obligations during the normal course of business.

Remaining Unsatisfied Performance Obligations—Remaining unsatisfied performance obligations represent the total dollar value of work to be performed on cost to cost contracts awarded and in progress. The amount of remaining unsatisfied performance obligations increases with new contracts or additions to existing contracts and decreases as revenue is recognized on existing contracts. Contracts are included in the amount of remaining unsatisfied performance obligations when an enforceable agreement has been reached. As of June 30, 2026 and December 31, 2025, the estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied was approximately $49.9 million and $68.4 million, respectively. As of June 30, 2026, the Company expected to recognize approximately $43.2 million of this amount as revenue within one year and $6.7 million the year after.

The Company had no customers that exceeded 10.0% of its gross receivables as of June 30, 2026 and one as of December 31, 2025. For the three and six months ended June 30, 2026, the Company had no customers that accounted for more than 10.0% of revenue. For the three and six months ended June 30, 2025 the Company had one customer who accounted for more than 10.0% of revenue.

The Company performs ongoing credit evaluations and based on past collection experience, the Company believes that the receivable balance from its largest customer does not represent a significant credit risk.

From time to time, the Company may sell certain accounts receivable to a financial institution on a non-recourse basis for cash, less a discount at a rate that approximates the interest rate on the Company's senior secured credit facility. The Company has no retained interests in the sold receivables and only performs collection and administrative functions for the purchaser. The Company accounts for these receivable transfers as sales under Accounting Standards Codification (ASC) 860, Transfers and Servicing. Receivables sold during the three and six months ended June 30, 2026 was $12.2 million. Receivables sold during the three and six months ended June 30, 2025 was $13.4 million. Proceeds from the sale of receivables approximated their book value and are included in operating cash flows on the Consolidated Statements of Cash Flows.