California Advances Landfill Methane Monitoring Ahead of 2027 Compliance

Key takeaways

• Remote methane detection technologies are entering routine compliance monitoring
• Faster leak detection and repair timelines are increasing operational pressure
• Monitoring requirements are expanding across slopes, working faces and inaccessible areas
• Early technology adoption is reducing compliance risk
  

Landfill operators across California face a new compliance challenge. Methane emissions remain a major climate priority, yet traditional monitoring methods often miss short-lived leaks or emissions in accessible areas.

Municipal solid waste landfills generate about 14% of methane emissions in the United States leading to increased regulatory attention and driving continued innovation in landfill methane monitoring.

The California Air Resources Board (CARB) updated the state’s Landfill Methane Regulation with amendments that take effect January 1, 2027. The rule introduces tighter detection thresholds, expanded monitoring expectations and stronger reporting requirements.

For landfill operators, this shift changes how methane monitoring programs must operate. Facilities will need broader detection coverage, faster response protocols and stronger emissions data management.

The draft rule lowers methane concentration thresholds for exceedances and shortens the time operators have to investigate and repair leaks.

Regulators increasingly evaluate how long emissions persist, not only the concentration recorded during a survey. A small leak that continues for weeks can produce significant methane emissions.

Operators should treat methane monitoring as a continuous operational cycle rather than a periodic inspection exercise.

An effective response process connects three steps:

• Detection:
  Routine monitoring identifies potential emissions
  
• Verification:
  Technicians confirm the source using tools such as Optical Gas Imaging (OGI)
  
• Repair:
  Maintenance crews repair the leak and document corrective action

Technologies like OGI cameras can accelerate this process. By visualizing methane plumes in real time, they allow technicians to locate emission sources quickly across complex landfill infrastructure.

Recurring leak locations such as wells, headers and surface penetrations often signal deeper infrastructure problems. Operators should investigate root causes rather than repeatedly repairing the same leak locations.

Traditional landfill monitoring relies on EPA Method 21, which requires technicians to walk landfill surfaces using handheld methane analyzers. The method remains the regulatory baseline for surface leak detection.

However, Method 21 inspections cannot safely reach every landfill location. Steep slopes, berms and sidewalls often remain difficult or dangerous for technicians to access.

The draft amendments expect operators to address these monitoring gaps by integrating mobile or remote detection tools into their monitoring programs.

Examples include:

• Optical Gas Imaging cameras
  
• Drone-mounted methane sensors
  
• Laser-based scanning technologies

These technologies allow operators to detect methane emissions across areas that routine walking surveys may miss.

Appendix A-1 of the draft rule allows operators to propose these alternative monitoring approaches if they demonstrate reliable and auditable performance. Operators adopting these tools must show that monitoring results are consistent and capable of supporting regulatory review.

Although the rule remains in draft form, operators can begin preparing now.

1. Monitor CARB rulemaking developments and participate in workshops or comment periods. Early engagement can help clarify compliance expectations.
   
2. Evaluate advanced monitoring technologies such as OGI, drone scanning or laser sensors. Pilot projects allow operators to compare detection coverage and build performance data that regulators may request during alternative method approvals.
   
3. Budget for expanded monitoring, reporting and repair requirements. New monitoring technologies and faster repair timelines may increase both capital and operational costs.
   
4. Review data management practices. Advanced monitoring systems generate larger datasets, which require reliable calibration, documentation and reporting procedures.
   
5. Plan for phased implementation. Operators that begin testing monitoring technologies now will face fewer operational disruptions when compliance deadlines arrive.

California’s proposed amendments signal a broader shift in landfill methane oversight. Monitoring expectations are expanding, detection technologies are improving and regulators are focusing more closely on how quickly operators respond to emissions. Facilities that begin adapting monitoring programs now will be better positioned to meet future compliance requirements.