FOR IMMEDIATE RELEASE

Casella Waste Systems and Waga Energy Unveil RNG Facility at Ribbon Cutting

EYBENS (France), May 18, 2026 — Casella Waste Systems, Inc. (NASDAQ: CWST), a regional solid waste, recycling and resource management services company in the Eastern United States, and Waga Energy (EPA: WAGA), a global expert in the production of Renewable Natural Gas (RNG) from landfills, held a ribbon-cutting ceremony on May 14, 2026, to celebrate the opening of the RNG production facility at the Chemung County Landfill in Elmira, New York. The facility, which has been successfully turning landfill gas into RNG since January 2026, represents a key milestone in Casella’s efforts to create valuable resources from waste.

“We’re excited to celebrate the opening of this facility as it represents a key piece of our strategy coming to life,” said Ned Coletta, President and CEO of Casella Waste Systems, Inc. “We made the decision several years ago to find great partners to develop these RNG projects at our facilities rather than invest the capital and embark on projects that are outside the scope of our expertise. This project is a great example of the benefits of that approach as we see the collective expertise of Chemung County, Waga Energy, and our landfill operations team coming together to create value out of the waste we manage.”

The facility leverages the WAGABOX® technology developed and patented by Waga Energy to upgrade landfill gas into pipeline‑quality RNG. The RNG produced on-site is injected directly into the Valley Energy natural gas distribution network, supplying the region with a renewable alternative to fossil natural gas. The facility is designed to generate up to 610,000 MMBtu of renewable gas annually and is expected to avoid more than 47,000 tons of CO₂‑equivalent emissions each year, according to U.S. Environmental Protection Agency (EPA) standards[1]. Through its first four months, the facility has performed well through its ramp up phase, and is projected to produce 340,000 MMBtu in year one which is equivalent to 2.4 million gallons of diesel fuel.

"We are honored to celebrate this inauguration alongside Casella, a company whose commitment to sustainability and environmental stewardship is truly exemplary,” said Guénaël Prince, Chief Executive Officer of Waga Energy Inc. “The successful commissioning of the Chemung facility demonstrates the strength of our partnership and Casella's leadership in renewable energy development. This project showcases how innovative collaboration can turn waste into a valuable resource for the energy transition, benefiting both the environment and local communities."

Under the terms of the agreement, Waga Energy deployed the capital required to fully fund the construction of the facility and will own and operate the facility for 20 years, while Casella and Waga Energy share the revenue generated from RNG sales.

About Casella Waste Systems, Inc.

Casella Waste Systems, Inc., headquartered in Rutland, Vermont, provides 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 in the eastern United States. For more information, visit www.casella.com.

About Waga Energy

Waga Energy produces competitively priced Renewable Natural Gas (RNG, also known as biomethane) by upgrading landfill gas using a patented purification technology called WAGABOX®. The RNG produced is injected directly into the gas grids that supply individuals and businesses, providing a substitute for natural fossil gas. Waga Energy currently operates 36 RNG production units in France, Spain, Canada and the USA, representing an installed capacity of more than 6.5 million MMBtu (1.9 TWh) per year. To date, WagaEnergy has 19 RNG production units under construction worldwide. Each project initiated by WagaEnergy contributes to the fight against global warming and helps the energy transition. Waga Energy is listed on Euronext Paris (FR0012532810 – EPA: WAGA).

SAFE HARBOR STATEMENT

Certain matters discussed in this press release, including but not limited to, the statements regarding our intentions, beliefs or current expectations concerning, among other things, projections as to the anticipated benefits of the commercial agreement, the anticipated amounts of renewable natural gas to be produced and the anticipated impact of the commercial agreement and the renewable natural gas facilities on the Company’s business and future financial and operating results are "forward-looking statements". These forward-looking statements can generally be identified as such by the context of the statements, including words such as “believe,” “expect,” “anticipate,” “plan,” “may,” “would,” “intend,” “estimate,” “will,” “guidance” and other similar expressions, whether in the negative or affirmative. These forward-looking statements are based on current expectations, estimates, forecasts and projections about the industry and markets in which the Company operates and management’s beliefs and assumptions. The Company cannot guarantee that it actually will achieve the financial results, plans, intentions, expectations or guidance disclosed in the forward-looking statements made. Such forward-looking statements, and all phases of the Company’s operations, involve a number of risks and uncertainties, any one or more of which could cause actual results to differ materially from those described in its forward-looking statements.

Such risks and uncertainties include or relate to, among other things, the following: project development timelines may extend past anticipated schedules; the Company may not fully recognize the expected financial benefits from the RNG facilities due to operational challenges, gas production levels, market or economic factors outside its control which may impact revenues and costs, or for other reasons; and potential regulatory changes could adversely impact operations.

There are a number of other important risks and uncertainties that could cause the Company’s actual results to differ materially from those indicated by such forward-looking statements. These additional risks and uncertainties include, without limitation, those detailed in Item 1A. “Risk Factors” in the Company’s most recently filed Form 10-K for the fiscal year ended December 31, 2025, and in other filings that the Company may make with the Securities and Exchange Commission in the future.

The Company undertakes no obligation to update publicly any forward-looking statements whether as a result of new information, future events or otherwise, except as required by law.

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[1] Landfill Gas Energy Benefits Calculator | US EPA