CASELLA WASTE SYSTEMS INC

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS (Continued)

(in thousands, except for share and per share data)

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS

(in thousands, except for per share data)

UNAUDITED CONSOLIDATED STATEMENTS OF

COMPREHENSIVE (LOSS) INCOME

UNAUDITED CONSOLIDATED STATEMENTS OF

STOCKHOLDERS' EQUITY

UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

1. BASIS OF PRESENTATION

Casella Waste Systems, Inc. (“Parent”) and its subsidiaries (collectively, “we”, “us” or “our”), is a regional, vertically integrated solid waste services company. We provide resource management expertise and services to residential, commercial, municipal, institutional and industrial customers, primarily in the areas of solid waste collection and disposal, transfer, recycling and organics services.

We provide integrated solid waste services with operating locations ineleven states: Vermont, New Hampshire, New York, Massachusetts, Connecticut, Maine, Pennsylvania, New Jersey, Delaware, Maryland and West Virginia, with our headquarters located in Rutland, Vermont. We manage our solid waste operations on a geographic basis through three regional operating segments, the Eastern, Western and Mid-Atlantic regions, each of which provides a comprehensive range of non-hazardous solid waste services. We manage our resource renewal operations through the Resource Solutions operating segment, which leverages our core competencies in materials processing, industrial recycling, organics and resource management service offerings to deliver a comprehensive solution for our larger commercial, municipal, institutional and industrial customers that have more diverse waste and recycling needs. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities segment.

The accompanying unaudited consolidated financial statements, which include the accounts of the Parent and our wholly-owned subsidiaries, have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). All significant intercompany accounts and transactions are eliminated in consolidation. Investments in entities in which we do not have a controlling financial interest are accounted for under either the equity method or the cost method of accounting, as appropriate. Our significant accounting policies are more fully discussed in Item 8. “Financial Statements and Supplementary Data” of our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, which was filed with the SEC on February 20, 2026 (“2025 Form 10-K”).

Preparation of our consolidated financial statements in accordance with GAAP requires management to make certain estimates and assumptions. These estimates and assumptions affect the accounting for and recognition and disclosure of assets, liabilities, equity, revenues and expenses. We must make these estimates and assumptions because certain information that we use is dependent on future events, cannot be calculated with a high degree of precision given the available data, or simply cannot be readily calculated. In the opinion of management, these consolidated financial statements include all adjustments, including normal recurring and nonrecurring adjustments, as applicable, necessary for a fair statement of the financial position, results of operations and cash flows for the periods presented. The results for the three and nine months ended September 30, 2026 may not be indicative of the results for any other interim period or the entire fiscal year. The consolidated financial statements presented herein should be read in conjunction with our audited consolidated financial statements included in our 2025 Form 10-K.

Subsequent Events

We have evaluated subsequent events or transactions that have occurred after the consolidated balance sheet date of September 30, 2026 through the date of filing of the consolidated financial statements with the SEC on this Quarterly Report on Form 10-Q. Except as disclosed, no material subsequent events have occurred since September 30, 2026 through the date of this filing that would require recognition or adjustments to our disclosures in our consolidated financial statements.

2. ACCOUNTING CHANGES

The following table provides a brief description of recent Accounting Standards Updates (“ASU”) to the Accounting Standards Codification (“ASC”) issued by the Financial Accounting Standards Board (“FASB”) that are pending adoption as of September 30, 2026 and deemed to have a possible material impact on our consolidated financial statements based on current account balances and activity:

3. REVENUE RECOGNITION

Revenues associated with our solid waste operations are derived mainly from solid waste (i) collection and (ii) disposal services, which include landfill and transfer station services, as well as (iii) transportation, (iv) landfill gas-to-energy and (v) processing services. Revenues associated with our resource renewal operations are derived from processing services and our National Accounts business. See Note 13, Segment Reporting for further disclosure over our Resource Solutions revenues.

The following tables set forth revenues disaggregated by service line and timing of revenue recognition by reportable operating segment for each of the three and nine months ended September 30, 2026 and 2025:

Three Months Ended September 30, 2026

Three Months Ended September 30, 2025

Nine Months Ended September 30, 2026

Nine Months Ended September 30, 2025

(1)Prior period amounts have been moved within Resource Solutions between the National Accounts and processing service lines to conform to the current period presentation reflecting the realignment of a business unit related to organic materials brokerage operations.

Payments to customers that are not in exchange for a distinct good or service are recorded as a reduction of revenues. Rebates to certain customers associated with payments for recycled or organic materials that are received and subsequently processed and sold to other third-parties amounted to $10,995 and $29,189 in the three and nine months ended September 30, 2026, respectively, and $9,331 and $29,485 in the three and nine months ended September 30, 2025, respectively. Rebates are generally recorded as a reduction of revenues upon the sale of such materials, or upon receipt of the recycled materials at our facilities. We didnot record revenues in the three and nine months ended September 30, 2026 or September 30, 2025 from performance obligations satisfied in previous periods.

Contract receivables, which are included in accounts receivable, net in our consolidated balance sheets, are recorded when billed or when related revenue is earned, if earlier, and represent claims against third-parties that will be settled in cash. Accounts receivable, net includes receivables from contracts of $230,768 and $181,616 as of September 30, 2026 and December 31, 2025, respectively. Certain customers are billed in advance and, accordingly, recognition of the related revenues for which payment has been received is deferred as a contract liability until the services are provided and control transferred to the customer. We recognized contract liabilities of $42,405 and $45,153 as of September 30, 2026 and December 31, 2025, respectively. Due to the short term nature of advanced billings, substantially all of the deferred revenue recognized as a contract liability as of December 31, 2025 and December 31, 2024 was recognized as revenue during the nine months ended September 30, 2026 and September 30, 2025, respectively, when the services were performed.

4. BUSINESS COMBINATIONS

In the nine months ended September 30, 2026, we completedsix acquisitions using cash on hand as well as borrowings under our revolving credit facility (“Revolving Credit Facility”). These acquisitions included: (i) the acquisition of all of the equity interests of a business and its related entities with operations in eastern Massachusetts and southern New Hampshire under our Eastern region consisting of collection operations, a construction and demolition processing facility and a transfer station, (ii) the acquisition of the assets of a business consisting of collection operations in West Virginia and a transfer station in southwestern Pennsylvania, which expanded our Mid-Atlantic region footprint into West Virginia and (iii)four tuck-in acquisitions of: one recycling operation in our Resource Solutions operating segment, one collection operation in our Western region andtwo collection operations in our Mid-Atlantic region.

In the nine months ended September 30, 2025, we acquired eight businesses, which included (i)five tuck-in collection operations in our Mid-Atlantic region, (ii) a tuck-in collection operation in our Western region, (iii) a recycling business in our Resource Solutions operating segment and (iv) a tuck-in collection operation and recycling business whose assets and liabilities are allocated between our Eastern region and Resource Solutions operating segments.

The operating results of the businesses acquired prior to September 30, 2026 have been included in the accompanying unaudited consolidated statements of operations from each date of acquisition, and each purchase price has been allocated to the net assets acquired based on fair values at the date of each acquisition with the residual amounts recorded as goodwill.

Due to the integration of certain of these businesses within our existing market areas, it is not practicable to segregate the revenues and earnings of all of the acquired businesses since their respective acquisition dates.

Purchase price allocations are based on information existing at the acquisition dates or upon closing the transactions. Acquired intangible assets other than goodwill that are subject to amortization may include customer relationships, trade names and covenants not-to-compete. Such assets are amortized over atwo-year toten-year period from the date of acquisition.

Goodwill acquired is primarily associated with the value of acquired businesses, based on current and anticipated operating performance, in excess of the specific values allocated to other assets, new growth opportunities arising from the acquisitions, and expected synergies from combining the acquired businesses with our existing operations and implementing our operating strategies. Approximately $204,936 of goodwill associated with acquisitions completed in the nine months ended September 30, 2026 is expected to be deductible for tax purposes.

Due to the uniformity of the businesses acquired, both operationally and tangibly through the nature of the assets acquired, and intangibly, through the acquisition of customer lists, covenants not-to-compete and trade names, we believe aggregated disclosure information is more relevant and useful to financial statement users than individualized disclosure of the separate acquisitions in accordance with FASB ASC 805 - Business Combinations.

A summary of the purchase price and the purchase price allocation for acquisitions follows:

(1)Includes contract receivables as of the date of the acquisitions in the nine months ended September 30, 2026 and 2025, of $12,283 and $8,070, respectively. Substantially all of the contractual amounts are expected to be collected.

Purchase price allocations for the nine months ended September 30, 2026 are preliminary and subject to revision upon finalization of third-party valuations over each respective one-year measurement period. Accordingly, the purchase price allocations for the nine months ended September 30, 2026 are subject to change. Amounts in the nine months ended September 30, 2025 are preliminary as disclosed based on information existing at the acquisition dates or upon closing the transaction and have since been updated based upon the finalization of third-party valuations, including the value of certain tangible and intangible assets acquired.

Unaudited pro forma combined information that shows our operational results prepared as though each acquisition completed since the beginning of the prior fiscal year had occurred as of January 1, 2025 is as follows:

The unaudited pro forma results set forth in the table above have been prepared for comparative purposes only and are not necessarily indicative of the actual results of operations had the acquisitions occurred as of January 1, 2025 or of the results of our future operations. Furthermore, the unaudited pro forma results do not give effect to all cost savings or incremental costs that may occur as a result of the integration and consolidation of the completed acquisitions.

See Note 11, Other Items and Charges for disclosure regarding expense from acquisition activities.

5. GOODWILL AND INTANGIBLE ASSETS

A summary of the activity and balances related to goodwill by reportable operating segment is as follows:

Summaries of intangible assets, net by type follow:

Intangible amortization expense was $21,238 and $61,644 during the three and nine months ended September 30, 2026, respectively, and $18,980 and $57,562 during the three and nine months ended September 30, 2025, respectively.

Based on the amortizable intangible assets recorded in the consolidated balance sheets at September 30, 2026, intangible amortization expense for each of the next five fiscal years and thereafter is estimated as follows:

6. ACCRUED FINAL CAPPING, CLOSURE AND POST-CLOSURE COSTS

Accrued final capping, closure and post-closure costs include the current and non-current portion of costs associated with obligations for final capping, closure and post-closure of our landfills. We estimate our future final capping, closure and post-closure costs of our landfills in order to determine the final capping, closure and post-closure expense per ton of waste placed into each landfill. The anticipated time frame for paying these costs varies based on the remaining useful life of each landfill as well as the duration of the post-closure monitoring period.

The changes to accrued final capping, closure and post-closure liabilities are as follows:

(1)Relates to a change in estimates and assumptions concerning anticipated waste flow, costs and timing of future final capping, closure and post-closure activities at our Subtitle D landfill located in Bethlehem, New Hampshire, which will stop accepting waste on December 31, 2026 rather than the end of the fiscal year ending December 31, 2027 as previously anticipated. We modified such timing after an evaluation of the remaining permitted airspace, current and projected fill rates and other operational factors.

(2)May include amounts paid and amounts that are being processed through accounts payable as a part of our disbursement cycle.

7. DEBT

A summary of debt is as follows:

Credit Facility

As of September 30, 2026, we are party to the second amended and restated credit agreement (“Credit Agreement”), which provides for a $800,000 aggregate principal amount Term Loan Facility and a $700,000 Revolving Credit Facility, with a $155,000 sublimit for letters of credit (collectively, "Credit Facility").

We have the right to request, at our discretion, an increase in the amount of loans under the Credit Facility by an aggregate amount of $200,000, subject to further increase based on the terms and conditions set forth in the Credit Agreement. The Credit Facility has a 5-year term that matures in September 2029. The Credit Facility shall bear interest, at our election, at term secured overnight financing rate (“Term SOFR”) or at a base rate, in each case plus or minus any sustainable rate adjustment of up to positive or negative 4.0 basis points per annum, plus an applicable interest rate margin based upon our consolidated net leverage ratio as follows:

A commitment fee will be charged on undrawn amounts of our Revolving Credit Facility based upon our consolidated net leverage ratio in the range of 0.200% to 0.400% per annum, plus a sustainability adjustment of up to positive or negative 1.0 basis point per annum. The Credit Agreement provides that Term SOFR is subject to azero percent floor. We are also required to pay a fronting fee for each letter of credit of 0.250% per annum. Interest under the Credit Agreement is subject to increase by 2.000% per annum during the continuance of a payment default and may be subject to increase by 2.000% per annum during the continuance of any other event of default. The Credit Facility is guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries and secured by substantially all of our assets. As of September 30, 2026, further advances were available under the Revolving Credit Facility in the amount of $450,718. The available amount is net of outstanding irrevocable letters of credit totaling $33,882. No amount has been drawn on the outstanding irrevocable letters of credit as of September 30, 2026.

The Credit Agreement requires us to maintain a minimum interest coverage ratio and a maximum consolidated net leverage ratio, to be measured at the end of each fiscal quarter. In addition to these financial covenants, the Credit Agreement contains a number of important customary affirmative and negative covenants which restrict, among other things, our ability to sell assets, incur additional debt, create liens, make investments, and pay dividends. As of September 30, 2026, we were in compliance with the covenants contained in the Credit Agreement.

An event of default under any of our debt agreements could permit some of our lenders, including the lenders under the Credit Facility, to declare all amounts borrowed from them to be immediately due and payable, together with accrued and unpaid interest, or, in the case of the Credit Facility, terminate the commitment to make further credit extensions thereunder, which could, in turn, trigger cross-defaults under other debt obligations. If we were unable to repay debt to our lenders or were otherwise in default under any provision governing our outstanding debt obligations, our secured lenders could proceed against us and against the collateral securing that debt.

Tax-Exempt Financings

Industrial revenue bonds are tax-exempt municipal debt securities issued by a government agency on our behalf and sold only to qualified institutional buyers. As of September 30, 2026, we had outstanding $273,500 aggregate principal amount of tax-exempt bonds issued by the states of New York, Vermont, Maine and New Hampshire (collectively, the “Industrial Revenue Bonds”), which are unsecured and guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries, and require interest payments semi-annually. The Industrial Revenue Bonds have fixed rate interest periods. At the end of each respective fixed rate interest period, the corresponding tax-exempt bond may be converted to a variable rate interest period or remarketed over a new fixed rate interest period. We borrowed the proceeds of the Industrial Revenue Bonds to finance or reimburse certain qualified capital projects and other costs in each respective state of issuance as defined in the related offering memorandum and indenture.

In the nine months ended September 30, 2026, we completed the remarketing of $15,000 aggregate principal amount of New York Bonds 2014R-2, which bears a fixed interest rate of 4.300% through June 2036.

In the nine months ended September 30, 2025, we completed the following transactions: (i) the drawdown of $25,000 aggregate principal amount of Vermont Bonds 2022A-2, which bears a fixed interest rate of 4.375% through May 2032, (ii) the repayment in full of Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3, which matured in January 2025, (iii) the remarketing of $29,000 aggregate principal amount of Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 and 2015R-2 into a single series FAME Bonds 2015R-3, which bears a fixed interest rate of 5.000% through August 2035 and (iv) the remarketing of $37,500 aggregate principal amount of New York Bonds 2020, which bears a fixed interest rate of 4.250% through September 2030.

Cash, Cash Equivalents and Restricted Cash, Including Non-Current

Restricted cash is included with restricted assets in our consolidated balance sheets based on the nature of the underlying restriction. Our restricted cash included with restricted assets, classified as non-current assets as of December 31, 2025, was associated with legally restricted cash held in an escrow account due to the timing of the close of an acquisition.

A reconciliation of beginning of period and end of period cash, cash equivalents and restricted cash, including non-current, for the nine months ended September 30, 2026 presented in the unaudited consolidated statements of cash flows is as follows:

Cash Flow Hedges

Our strategy to reduce exposure to interest rate risk involves entering into interest rate derivative agreements to hedge against adverse movements in interest rates related to the variable rate portion of our long-term debt. We have designated these derivative instruments as highly effective cash flow hedges, and therefore the change in their fair value is recorded in stockholders’ equity as a component of accumulated other comprehensive income (loss), net of tax and included in interest expense at the same time as interest expense is affected by the hedged transactions. Differences paid or received over the life of the agreements are recorded as additions to or reductions of interest expense on the underlying debt and included in cash flows from operating activities.

As of both September 30, 2026 and December 31, 2025, we had $515,000 notional amount of active interest rate derivative agreements outstanding. Interest rate derivative agreements outstanding as of September 30, 2026, mature between December 2026 and February 2030 and provide that we receive interest based on Term SOFR, restricted by a 0.0% floor, and pay interest at a weighted average rate of approximately 3.626%.

A summary of the effect of cash flow hedges related to derivative instruments on the consolidated balance sheets follows:

8. COMMITMENTS AND CONTINGENCIES

Legal Proceedings

In the ordinary course of our business and as the result of the extensive governmental regulation of the solid waste industry, we are subject to various judicial and administrative proceedings involving state and local agencies. In these proceedings, an agency may seek to impose fines or to revoke or deny renewal of an operating permit held by us. From time to time, we may also be subject to actions brought by special interest or other groups, adjacent landowners or residents in connection with the permitting and licensing of landfills and transfer stations, or allegations of environmental damage or violations of the permits and licenses pursuant to which we operate. In addition, we may be named defendants in various claims and suits pending for alleged damages to persons and property, alleged violations of certain laws and alleged liabilities arising out of matters occurring during the ordinary operation of a waste management business. The plaintiffs in some actions seek unspecified damages or injunctive relief, or both. These actions fall within various procedural stages at any point in time, and some are covered in part by insurance.

In accordance with FASB ASC 450 - Contingencies, we accrue for legal proceedings, inclusive of legal costs, when losses become probable and reasonably estimable. We have recorded an aggregate accrual, net of payments of $2,015 relating to our outstanding legal proceedings as of September 30, 2026 and it is at least reasonably possible that a change in estimate will occur in the near-term. As of the end of each applicable reporting period, we review each of our legal proceedings to determine whether it is probable, reasonably possible or remote that a liability has been incurred and, if it is at least reasonably possible, whether a range of loss can be reasonably estimated under the provisions of FASB ASC Subtopic 450-20. In instances where we determine that a loss is probable and we can reasonably estimate a range of loss we may incur with respect to such a matter, we record an accrual for the amount within the range that constitutes our best estimate of the possible loss. If we are able to reasonably estimate a range, but no amount within the range appears to be a better estimate than any other, we record an accrual in the amount that is the low end of such range. When a loss is reasonably possible, but not probable, we will not record an accrual, but we will disclose our estimate of the possible range of loss where such estimate can be made in accordance with FASB ASC 450-20. We disclose outstanding matters that we believe could have a material adverse effect on our financial condition, results of operations or cash flows.

North Country Environmental Services Letter of Deficiency

On June 14, 2024, our subsidiary, North Country Environmental Services, Inc. (“NCES”), received a Letter of Deficiency (the “Letter”) from the New Hampshire Department of Environmental Services (“NHDES”) concerning alleged violations related to leachate management and leachate data and reporting. The Letter required certain actions to correct the deficiencies on a prescribed timeline, and NCES has met the deadlines for information submission. On January 12, 2026, the New Hampshire Department of Justice and NCES entered into a Consent Decree resolving the alleged violations and requiring the payment of a $1,900 civil penalty, part of which may be offset through approved Supplemental Environmental Projects focused on stabilizing landfill debris impacting the Saco River, of which one such project has already been implemented. The terms of the settlement allow for us to receive a credit towards the penalty for field work costs associated with a Supplemental Environmental Project. The accrual has been reduced to account for these sums that have already been paid. The Grafton County Superior Court entered approval of the Consent Decree on January 29, 2026. The New Hampshire Attorney General notified NCES by letter dated September 23, 2026 that the Saco River stabilization project proposed by NCES is not a feasible Supplemental

Environmental Project due to cost constraints, and directed NCES to propose alternative projects within 60 days or otherwise, provide a final accounting of costs incurred in connection with the Saco River stabilization project and remit the remaining civil penalty in accordance with the Consent Decree.

Granite State Landfill Solid Waste Permit Denial

On April 3, 2025, NHDES denied the October 31, 2023 application of our subsidiary, Granite State Landfill, LLC (“GSL”), for the development of a new solid waste landfill on a greenfield site in an industrial area in Dalton, New Hampshire. The GSL project design consists of an approximately 70-acre lined landfill footprint and an estimated 18 years of disposal capacity, together with supporting infrastructure and renewable-energy projects.

On April 8, 2025, GSL filed a Petition for Declaratory Judgment in the Merrimack Superior Court (“Court”) requesting that the Court find that NHDES’s denial of GSL’s application was unlawful (“Petition”). On May 9, 2025, NHDES filed an Answer to the Petition. On June 23, 2025, North Country Alliance for Balanced Change (“NCABC”) filed a Motion to Intervene, in response to which GSL filed an Objection on June 30, 2025. On July 1, 2025, a scheduling conference was held and the Court issued a Scheduling Order of the same date providing that the issues raised in the Petition appear to be a legal dispute that can be addressed by cross-motions for summary judgment, and requiring the parties to confer and submit briefing schedule proposals to the Court on or before July 18, 2025. A Joint Proposed Briefing Schedule was filed by the parties on July 17, 2025. NCABC filed a reply to GSL’s Objection to NCABC’s Motion to Intervene on July 25, 2025. On August 5, 2025, the Court issued an order granting NCABC’s Motion to Intervene. GSL timely moved for reconsideration of that order, which was denied on September 2, 2025. GSL then filed a Motion for an Interlocutory Appeal on September 12, 2025, to challenge NCABC’s standing to intervene. NCABC objected to the Motion for an Interlocutory Appeal on September 22, 2025. On September 15, 2025, GSL and NHDES filed cross-motions for summary judgment. NCABC joined in NHDES’s motion. GSL’s and NHDES’s objections to the cross-motions for summary judgment were submitted October 15, 2025. The Court held a hearing on the cross-motions for summary judgment on May 26, 2026. On July 23, 2026, the Court issued an order granting NHDES’s Motion for Summary Judgment, which was joined by NCABC, and denying GSL’s Motion for Summary Judgment. In response, GSL filed a Motion to Reconsider on August 6, 2026, to which NHDES submitted an Objection on August 17, 2026. The Court denied GSL’s Motion to Reconsider by Order dated August 31, 2026.

On May 5, 2025, GSL and NCABC each filed a Notice of Appeal of NHDES’s denial of GSL’s application with the New Hampshire Waste Management Council (the “Council”) (“GSL Appeal” and “NCABC Appeal”, respectively). On May 9, 2025, GSL filed a partially assented to Motion to Intervene in the NCABC Appeal, followed by a Motion to Dismiss the NCABC Appeal on June 27, 2025. NHDES filed a Motion to Dismiss the NCABC Appeal on July 17, 2025. NCABC filed an Objection to GSL’s Motion to Dismiss on July 24, 2025 and to NHDES’s Motion to Dismiss on July 28, 2025. On August 8, 2025, NCABC filed a Motion to Intervene in the GSL Appeal. On February 23, 2026, the Council issued an Order declining to accept the NCABC Appeal. In response, NCABC submitted a Motion for Rehearing and Clarification along with a Revised Petition for Appeal, both dated March 16, 2026. The Council subsequently denied NCABC’s Motion for Rehearing by Order dated March 27, 2026. NCABC appealed this decision to the New Hampshire Supreme Court. NCABC’s appeal was declined by the New Hampshire Supreme Court by Order dated July 16, 2026.

The Council held a prehearing conference on the GSL Appeal on April 15, 2026, at which time NCABC’s Motion to Intervene was argued, and a deadline was set for NHDES to file additional motions concerning the GSL Appeal. The Council issued an Order on May 4, 2026, denying NCABC’s Motion to Intervene in the GSL Appeal, and granting NCABC permission to join the GSL Appeal, amicus curiae. On May 8, 2026, NHDES filed a Motion to Dismiss several of GSL’s claims on appeal. On June 1, 2026, GSL filed an Objection to NHDES’s Motion to Dismiss, and NCABC filed a Motion for Rehearing and Clarification of the Council’s Order on NCABC’s Motion to Intervene. On June 10, 2026, the Council issued an Order denying NCABC’s Motion for Rehearing and withdrawing NCABC’s amicus curiae status, holding that NCABC’s status would be a limited intervenor in the GSL Appeal, a holding which NCABC has appealed to the New Hampshire Supreme Court. On September 24, 2026, the Council issued an Order on NHDES’s Motion to Dismiss, granting dismissal of six out of twelve of GSL’s claims on appeal. The matter remains pending before the Council.

On July 10, 2026, HB 707 was signed into law in New Hampshire which took effect in September 2026. The law establishes a new Solid Waste Facility Site Evaluation Committee (“Site Evaluation Committee”) and creates a state-level process for reviewing, evaluating, and approving future landfill siting proposals within the state. Under this framework, proposed new landfill sites, such as GSL, will be subject to Site Evaluation Committee review and approval.

In the three and nine months ended September 30, 2026, we wrote off $13,593 of previously deferred project development costs related to the GSL greenfield landfill project that were included in other non-current assets, as we believe the denial of GSL’s Motion to Reconsider, the changes in legislation and the unsupportive political environment will prevent us from recovering these costs through future operations. See Note 11, Other Items and Charges for disclosure over the charge related to the write-off.

Juniper Ridge Landfill Public Benefit Determination Remand on Appeal

On January 7, 2026, the Penobscot Superior Court (“Superior Court”) issued a decision in the matter of Penobscot Nation & Conservation Law Foundation (“Petitioners”) v. Maine Department of Environmental Protection (“Department”), with Casella subsidiary, NEWSME Landfill Operations, LLC (“NEWSME”) as Party‑in‑Interest, addressing the Petitioners’ challenge to the Department’s public benefit determination for the proposed expansion of the Subtitle D landfill located in West Old Town, Maine (“Juniper Ridge Landfill”) that we operate. The Superior Court granted Petitioners’ motion for judicial notice and found that the Department failed to make necessary factual findings regarding both the need for on‑site sludge‑drying and the cumulative environmental burdens borne by the Penobscot Nation. The Superior Court remanded the matter for the Department to make additional findings on these issues. The Department made additional findings in a revised public benefit determination submitted by the Department to the Superior Court on March 23, 2026. On April 11, 2026, Petitioners filed a supplemental brief objecting to the revised public benefit determination. On June 10, 2026, NEWSME and the Department submitted separate filings requesting that the Superior Court affirm the revised public benefit determination issued by the Department. On June 24, 2026, Petitioners filed a reply brief responding to the briefing of NEWSME and the Department. The Superior Court heard oral argument on the revised public benefit determination on July 23, 2026. The Petitioners have filed multiple motions seeking judicial notice of information outside the administrative record, including a May 11, 2026 motion concerning a perfluorooctanesulfonic acid (commonly referred to as “PFOS”) fish consumption advisory, and a September 11, 2026 motion regarding NEWSME's plans for location of a per- and polyfluoroalkyl substances (commonly referred to as “PFAS”) treatment system. The Department and NEWSME have opposed those motions, arguing that the Superior Court's review on appeal is limited to the administrative record, to which the Petitioners submitted a Reply on October 9, 2026. The matter remains pending before the Superior Court.

Juniper Ridge Landfill Expansion License Application

On July 27, 2026, the Presiding Officer overseeing the Maine Department of Environmental Protection licensing proceeding for the proposed Juniper Ridge Landfill expansion issued a Second Procedural Order denying NEWSME’s request to be recognized as a co-applicant, determining that the State of Maine Bureau of General Services (“Bureau”) remains the sole applicant and licensee and that NEWSME shall participate as the State's agent. The Order also granted intervenor status to various parties. A pre-hearing conference was held on August 14, 2026, following which a scheduling order for the proceeding established licensing hearing dates of December 7 to 9, 2026. On August 20, 2026, the Penobscot Nation and other intervenors requested that procedural deadlines be amended to extend the hearing dates out to April 2027, and that the Bureau and NEWSME be required to submit additional information to supplement the licensing application. NEWSME and the Bureau submitted an Opposition on August 28, 2026, to which the Penobscot Nation and other intervenors submitted a Reply on September 3, 2026. The matter remains pending before the Maine Department of Environmental Protection.

Environmental Remediation Liabilities

We are subject to liability for environmental damage, including personal injury and property damage, that our solid waste, recycling and power generation facilities may cause to neighboring property owners, particularly as the result of the contamination of drinking water sources or soil, possibly including damage resulting from conditions that existed before we acquired the facilities. We may also be subject to liability for similar claims arising from off-site environmental contamination caused by pollutants or hazardous substances if we or our predecessors arrange or arranged to transport, treat or dispose of those materials.

We accrue for costs associated with environmental remediation obligations when such costs become both probable and reasonably estimable. Determining the method and ultimate cost of remediation requires that a number of assumptions be made. There can sometimes be a range of reasonable estimates of the costs associated with remediation of a site. In these cases, we use the amount within the range that constitutes our best estimate. In the early stages of the remediation process, particular components of the overall liability may not be reasonably estimable; in this instance we use the components of the liability that can be reasonably estimated as a surrogate for the liability. It is reasonably possible that we will need to adjust the liabilities recorded for remediation to reflect the effects of new or additional information, to the extent such information impacts the costs, timing or duration of the required actions, which could have a material adverse effect on our consolidated financial position, results of operations and cash flows. We disclose outstanding environmental remediation matters that remain unsettled or are settled in the reporting period that we believe could have a material adverse effect on our financial condition, results of operations or cash flows.

We inflate the estimated costs in current dollars to the expected time of payment and discount the total cost to present value using a risk-free interest rate when the amount and timing of cash payments for the liability are fixed or reliably determinable. The weighted-average risk-free interest rate associated with our environmental remediation liabilities as of September 30, 2026 was approximately 1.8%.

A summary of the changes to the aggregate environmental remediation liabilities for the nine months ended September 30, 2026 and 2025 follows:

(1)May include amounts that are being processed through accounts payable as a part of our disbursement cycle.

9. STOCKHOLDERS' EQUITY

Stock Based Compensation

Shares Available For Issuance

In fiscal year 2024, our stockholders approved the amendment and restatement of our 2016 Incentive Plan (“Amended 2016 Plan”). Under the Amended 2016 Plan, we may grant awards up to an aggregate amount of shares equal to the sum of: (A)4,000 shares of Class A common stock (subject to adjustment in the event of stock splits and other similar events) which is comprised of: (i)1,750 shares of Class A common stock reserved for the issuance in connection with the Amended 2016 Plan, plus (ii)2,250 shares of Class A common stock originally reserved for issuance under the 2016 Incentive Plan; plus (B) such additional number of shares of Class A common stock (up to approximately 2,723 shares) as is equal to the sum of the number of shares of Class A common stock that remained available for grant under the 2006 Stock Incentive Plan (“2006 Plan”) immediately prior to the expiration of the 2006 Plan and the number of shares of Class A common stock subject to awards granted under the 2006 Plan that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by us. As of September 30, 2026, there were 1,823 Class A common stock equivalents available for future grant under the Amended 2016 Plan.

Stock Options

Stock options are granted at a price equal to the prevailing fair value of our Class A common stock at the date of grant. Generally, stock options granted have a term not to exceedten years and vest over aone-year tofive-year period from the date of grant.

The fair value of each stock option granted is estimated using a Black-Scholes option-pricing model, which uses a risk-free interest rate, based on the U.S. Treasury yield curve for the period of the expected life of the stock option; and requires extensive use of accounting judgment and financial estimation, including estimates of: the expected term, calculated based on the weighted averaged historical life of vested stock options, giving consideration to vesting schedules and historical exercise patterns; and the expected volatility, calculated using the weekly historical volatility of our Class A common stock over the expected life of the stock option.

A summary of stock option activity follows:

Stock-based compensation expense related to stock options was $173 and $441 during the three and nine months ended September 30, 2026, respectively, as compared to $136 and $404 during the three and nine months ended September 30, 2025, respectively. As of September 30, 2026, we had $1,342 of unrecognized stock-based compensation expense related to outstanding stock options to be recognized over a weighted average period of 2.2 years.

During the three and nine months ended September 30, 2026, the aggregate intrinsic value of stock options exercised waszero dollars.

Other Stock Awards

Restricted stock awards, restricted stock units and performance stock units, with the exception of market-based performance stock units, are granted at a price equal to the fair value of our Class A common stock at the date of grant. The fair value of each market-based performance stock unit is estimated using a Monte Carlo pricing model, which requires extensive use of accounting judgment and financial estimation, including the estimated share price appreciation plus, if applicable, the value of dividends of our Class A common stock as compared to the Russell 2000 Index over the requisite service period.

Typically, restricted stock awards granted to non-employee directors vest incrementally over athree-year period beginning on the first anniversary of the date of grant. Restricted stock units granted to non-employee directors vest in full on the first anniversary of the grant date. Restricted stock units granted to employees vest incrementally over an identified service period, typically three-years, beginning on the grant date based on continued employment. Performance stock units granted to employees, including market-based performance stock units, vest at a future date following the grant date and are based on the attainment of performance targets and market achievements, as applicable.

A summary of restricted stock award, restricted stock unit and performance stock unit activity follows:

(1)Performance stock unit grants, including market-based performance stock units, are included at the 100% attainment level. Attainment of the maximum performance targets and market achievements would result in the issuance of an additional 236 shares of Class A common stock currently included in unvested.

Stock-based compensation expense related to restricted stock awards, restricted stock units and performance stock units was $2,213 and $8,304 during the three and nine months ended September 30, 2026, respectively, as compared to $3,539 and $10,676 during the three and nine months ended September 30, 2025, respectively.

During the three and nine months ended September 30, 2026, the total fair value of other stock awards vested was $437 and $4,938, respectively.

As of September 30, 2026, total unrecognized stock-based compensation expense related to outstanding restricted stock units was $8,376, which is to be recognized over a weighted average period of 1.9 years. As of September 30, 2026, total expected unrecognized stock-based compensation expense related to outstanding performance stock units was $10,482, which is to be recognized over a weighted average period of 1.8 years.

The weighted average fair value of market-based performance stock units granted during the nine months ended September 30, 2026 was $98.60 per award, which was calculated using a Monte Carlo pricing model assuming a risk-free interest rate of 3.72% and an expected volatility of 25.6% assuming no expected dividend yield. Risk-free interest rate is based on the U.S. Treasury yield curve for the expected service period of the award. Expected volatility is calculated using the daily volatility of our Class A common stock over the expected service period of the award.

The Monte Carlo pricing model requires extensive use of accounting judgment and financial estimation. Application of alternative assumptions could produce significantly different estimates of the fair value of stock-based compensation and consequently, the related amounts recognized in the unaudited consolidated statements of operations.

We also recorded $235 and $758 of stock-based compensation expense related to the Second Amended and Restated 1997 Employee Stock Purchase Plan during the three and nine months ended September 30, 2026, respectively, as compared to $196 and $568 during the three and nine months ended September 30, 2025, respectively.

Accumulated Other Comprehensive Income (Loss), Net of Tax

A summary of the changes in the balances of each component of accumulated other comprehensive income (loss), net of tax follows:

A summary of reclassifications out of accumulated other comprehensive income (loss), net of tax into earnings follows:

10.(LOSS) EARNINGS PER SHARE

Basic (loss) earnings per share attributable to common stockholders is computed by dividing net (loss) income by the weighted average common shares outstanding during the period. Diluted (loss) earnings per share attributable to common stockholders is calculated based on the combined weighted average number of common shares and potentially dilutive shares, which include the assumed exercise of employee stock options, unvested restricted stock awards, unvested restricted stock units and unvested performance stock units, including market-based performance units based on the expected achievement of performance targets. In computing diluted (loss) earnings per share attributable to common stockholders, we utilize the treasury stock method.

A summary of the numerator and denominators used in the computation of (loss) earnings per common share attributable to common stockholders follows:

11. OTHER ITEMS AND CHARGES

Expense from Acquisition Activities

In the three and nine months ended September 30, 2026, we recorded charges of $6,318 and $18,909, respectively, and in the three and nine months ended September 30, 2025, we recorded charges of $4,618 and $16,610, respectively, comprised primarily of legal, consulting, rebranding, information technology and other costs associated with the due diligence, acquisition and integration of acquired businesses.

Landfill Development Impairment Charge

In the three and nine months ended September 30, 2026, we recorded a charge of $13,593 for the complete write-off of deferred costs associated with the GSL greenfield landfill project no longer deemed viable. See Note 8, Commitments and Contingencies for further disclosure regarding the GSL greenfield landfill project.

Organics Facility Closure Charge

In the three months ended December 31, 2025, we initiated the plan to cease operations of an organic residuals composting facility that we own in Maine related to a change in state law prohibiting land application of biosolids based recycled products. In the three and nine months ended September 30, 2026, we recorded $703 and $2,719, respectively, of other costs as incurred associated with winding down the facility, and expect to incur additional costs related to ceasing operations at the facility.

Organizational Transformation Costs

In the three and nine months ended September 30, 2026, we recorded organizational transformation costs of $1,407, comprised of certain costs related to employee severance and other employee compensation associated with initiatives to optimize our organizational structure and business operations. We expect to incur additional expenses related to these initiatives, potentially including third-party consulting, employee related compensation, information technology, legal and other costs.

12. FAIR VALUE OF FINANCIAL INSTRUMENTS

We use a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. These tiers include: Level 1, defined as quoted market prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; and Level 3, defined as unobservable inputs that are not corroborated by market data.

We use valuation techniques that maximize the use of market prices and observable inputs and minimize the use of unobservable inputs. In measuring the fair value of our financial assets and liabilities, we rely on market data or assumptions that we believe market participants would use in pricing an asset or a liability.

Assets and Liabilities Accounted for at Fair Value

Our financial instruments include cash, cash equivalents and non-current restricted cash, accounts receivable, restricted investment securities held in trust on deposit with various banks as collateral for our obligations relative to our landfill final capping, closure and post-closure costs, interest rate derivatives, trade payables and debt. The carrying values of cash, cash equivalents and non-current restricted cash, accounts receivable and trade payables approximate their respective fair values due to their short-term nature. The fair value of restricted investment securities held in trust, which are valued using quoted market prices, are included as restricted assets in the Level 1 tier below. The fair value of the interest rate derivatives included in the Level 2 tier below is calculated using discounted cash flow valuation methodologies based upon Term SOFR yield curves that are observable at commonly quoted intervals for the full term of the swaps. We recognize all derivatives accounted for on the consolidated balance sheets at fair value.

Recurring Fair Value Measurements

Summaries of our financial assets and liabilities that are measured at fair value on a recurring basis follow:

Fair Value of Debt

As of September 30, 2026, the carrying value of our Term Loan Facility was $800,000 and the carrying value of our Revolving Credit Facility was $215,400. Their fair values are based on current borrowing rates for similar types of borrowing arrangements, or Level 2 inputs, and approximate their carrying values.

As of September 30, 2026, the fair value of the Industrial Revenue Bonds was approximately $270,247 and the carrying value was $273,500. The fair value of the Industrial Revenue Bonds is considered to be Level 2 within the fair value hierarchy as the fair value is determined using market approach pricing provided by a third-party that utilizes pricing models and pricing systems, mathematical tools and judgment to determine the evaluated price for the security based on the market information of each of the bonds or securities with similar characteristics.

Although we have determined the estimated fair value amounts of the Industrial Revenue Bonds using available market information and commonly accepted valuation methodologies, a change in available market information, and/or the use of different assumptions and/or estimation methodologies could have a material effect on the estimated fair values. These amounts have not been revalued, and current estimates of fair value could differ significantly from the amounts presented.

13. SEGMENT REPORTING

We report selected information about ourreportable operating segments in a manner consistent with that used for internal management reporting. We classify our solid waste operations on a geographic basis through three regional operating segments, the Eastern, Western and Mid-Atlantic regions. Revenues associated with our solid waste operations are derived mainly from solid waste (i) collection and (ii) disposal services, which include landfill and transfer station services, as well as (iii) transportation, (iv) landfill gas-to-energy and (v) processing services in the eastern United States.

Our Resource Solutions operating segment leverages our core competencies in materials processing, industrial recycling, organics and resource management service offerings to deliver a comprehensive solution for our larger commercial, municipal, institutional and industrial customers that have more diverse waste and recycling needs. Revenues associated with our Resource Solutions operations are comprised of processing services and our National Accounts business. Revenues from processing services are derived from customers in the form of processing fees, tipping fees, commodity sales, and organic material related brokerage services and sales. Revenues from our National Accounts business are derived from brokerage services and overall resource management services providing a wide range of environmental services and resource management solutions to large and complex organizations, as well as traditional collection, disposal and recycling services provided to large account multi-site customers. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities segment, which is not a reportable operating segment.

For comparative purposes, summarized financial information by segment reported in the three and nine months ended September 30, 2025 has been updated in the tables below as we have voluntarily corrected certain amounts related to an immaterial error in the prior year’s segment footnote disclosure by reclassifying certain intercompany amounts from contra-revenue recorded in our Eastern and Western regions to costs of operations for those same regions, with no impact on any measure of segment operating income (loss) or our consolidated balance sheet, earnings, or cash flows.

See Note 5, Goodwill and Intangible Assets for the breakout of goodwill by reportable operating segment.

The accounting policies of our reportable operating segments are the same as those described in Item 8. “Financial Statements and Supplementary Data” of our 2025 Form 10-K. Our President and Chief Executive Officer is our chief operating decision maker (“CODM”). Our CODM uses operating income (loss) in evaluating reportable operating segment performance in order to properly allocate resources and make key operating decisions. Intercompany revenues and expenses are eliminated in the computation of consolidated gross revenues and operating income (loss).

The CODM uses operating income (loss) for each reportable operating segment in the annual budget and forecasting process and considers budget-to-actual and forecast-to-actual variances on a monthly basis when making decisions about the allocation of operating and capital resources to each reportable operating segment.

Summarized financial information concerning our reportable segments for the three and nine months ended September 30, 2026 and 2025 follows:

Three Months Ended September 30, 2026

Three Months Ended September 30, 2025

Nine Months Ended September 30, 2026

Nine Months Ended September 30, 2025

A summary of our revenues attributable to services provided follows:

(1)In the nine months ended September 30, 2026, we revised the presentation of our service lines to remove the transportation service line from the disposal caption and present it separately. Disposal now consists of the landfill and transfer station service lines. Amounts disclosed for the three and nine months ended September 30, 2025 have been updated to conform to the current period presentation.

(2)In the nine months ended September 30, 2026, we realigned a business unit related to organic materials brokerage operations within our Resource Solutions operating segment from the National Accounts service line to the processing service line. Amounts disclosed for the three and nine months ended September 30, 2025 have been updated to conform to the current period presentation.