What Colorado's new landfill methane rule means for solid waste operators

Regulation 31 breakdown

Colorado Department of Public Health and Environment’s (CDPHE) AQCC Regulation 31 establishes mandatory methane‑emission reduction requirements for subject Municipal Solid Waste (MSW) landfills. The rule is designed to directly support Colorado’s statutory greenhouse‑gas reduction objectives and to address methane, a potent greenhouse gas (GHG) and ozone precursor, across the state’s waste sector.

The regulation applies to any MSW landfills that accepted waste after November 8, 1987, with specified exceptions for tribal lands and certain low-capacity or specialized landfills. Reporting requirements begin in June 2026, with compliance deadlines including installed gas collection & control systems (GCCS) and methane monitoring starting in 2027.

What we can learn from other states

SLR is uniquely positioned to support Colorado landfill operators as they implement the new AQCC Regulation 31 requirements. We have spent many years helping landfill clients in California comply with similarly stringent methane monitoring, reporting, and gas‑collection standards. California’s Landfill Methane Regulation has required advanced emissions monitoring and robust GCCS performance since 2010, with major updates adopted in 2025 that further tightened leak detection, reporting, and technology requirements.

Colorado’s new methane rules introduce expanded monitoring, a phase‑out of open flares, more stringent corrective action thresholds, and increased reporting obligations under Regulation 31. These requirements closely align with the standards already in place in California. With years of experience helping California sites comply with these expectations, SLR brings proven, efficient, and technically sound strategies to support Colorado’s evolving regulatory landscape.

How SLR can assist

We bring to the table expertise from some of the most-regulated states for MSW landfills, with over a decade of experience supporting landfills in California, Oregon and Washington, across planning, design, permitting, regulatory compliance, and construction quality assurance (CQA).

For many landfills, SLR has become the trusted consultant for navigating regulatory expectations. We have completed more than 25 projects across eight MSW landfills in the last five years, supported by local field staff and strong relationships with contractors and regulators. Our work is routinely approved without revisions, enabling clients to operate new cells and gas systems into service sooner, avoid costly delays, and maintain fully compliant, well-constructed facilities. With offices in Colorado’s Front Range and across North America, our local teams provide responsive onsite support backed by global technical expertise.

We also have a 20+ year history and a trusted relationship with Colorado regulators in the air quality sector, including recent GHG regulations targeting the midstream and upstream oil and gas (O&G) industry. The Regulation 31 MSW leak detection, flare capacity evaluations, and performance testing requirements are very similar to those that SLR already supports for other industries. Our familiarity with Colorado regulators and with similar requirements in other industries allows SLR to provide efficient guidance and ensure compliance work is done right the first time.

Furthermore, we’ve been helping the O&G industry monitor and measure methane emissions for decades. Our experience makes SLR well-equipped to navigate the unique challenges of methane management. Whether it’s selecting the most fit-for-purpose monitoring device or determining how to reconcile your traditional inventory with your snapshot direct measurement, we can help.