AB 28 directs municipal solid waste (MSW) landfill operators to monitor subsurface landfill gas temperatures under State Air Resources Board rules and establishes a three-tiered response framework when elevated temperatures persist. The bill prescribes notification windows, required reporting and corrective-action plans, public notice requirements, and the formation of a CalEPA-led multiagency coordination group for more serious events.
The statute also creates new enforcement tools: temporary permit suspension authority, emergency proclamation options, daily administrative penalties for failure to meet reporting duties, and a high-end penalty for grossly negligent operators where an event poses immediate and substantial risk. Penalties fund a new Landfill Subsurface Fire Mitigation Account to support affected communities.
At a Glance
What It Does
Requires landfill gas temperature monitoring under CARB regulations and defines a subsurface elevated temperature event that triggers escalating actions: operator notices, technical assessments, corrective-action plans, public notices, and possible permit suspension or emergency proclamations.
Who It Affects
MSW landfill operators subject to federal performance or hazardous-air-pollutant standards, CalEPA and its designated state agencies (including OEHHA and the State Air Resources Board), and certified local enforcement agencies that oversee landfill permits.
Why It Matters
It fills a regulatory gap for underground heating/subsurface fires at landfills by creating specific temperature triggers, timelines, and accountability; it also centralizes multiagency response and channels penalties to a mitigation account for impacted communities.
More articles like this one.
A weekly email with all the latest developments on this topic.
What This Bill Actually Does
AB 28 makes subsurface temperature a regulated operational metric at municipal solid waste landfills. The State Air Resources Board must adopt mandatory temperature-monitoring requirements as part of its methane rules; operators must then monitor wellhead gas temperatures and report under the timelines the statute sets.
The bill defines a "subsurface elevated temperature event" as a persistent, above-threshold condition and ties different regulatory reactions to progressively higher temperatures.
Once an elevated condition meets the statute’s criteria, the operator must notify agencies quickly and submit an initial account of actions and a root-cause analysis. For the lowest tier the bill requires expedited inspection, weekly temperature reporting for affected wells, and the filing or development of a corrective-action plan within prescribed windows.
At the next tier it steps up transparency—public postings, monthly community notices, and activation of a CalEPA-led multiagency coordination group to advise and monitor progress. The highest tier adds the possibility of permit suspensions, local or state emergency proclamations, and an intensified review of whether earlier responses failed.The bill also sets enforcement and funding mechanisms.
Specified reporting and notification failures carry an administrative penalty (the statute uses per-day amounts); for the most serious, ongoing events the department may impose a significantly larger weekly penalty when gross negligence combined with immediate and substantial risk is found. Penalty revenue flows into a new Landfill Subsurface Fire Mitigation Account that the department will use—subject to legislative appropriation—to prioritize assistance to the communities harmed by the particular landfill incident.Finally, AB 28 assigns additional procedural duties to state and local agencies: the department must issue guidance and minimum standards for corrective-action plans by a statutory deadline, adopt emergency regulations setting the event criteria, and coordinate posting and public access to operator requests to raise permitted operating temperatures.
Operators are explicitly liable for the actual and reasonable costs that agencies incur enforcing the statute, and the law specifies that certain department rulemaking for corrective actions and imposed operating conditions is exempt from standard administrative-procedure requirements.
The Five Things You Need to Know
Three temperature tiers trigger escalation: about 131°F (initial response), 146°F (heightened transparency and CalEPA multiagency review), and 162°F–170°F (highest tier that may justify permit suspension and emergency action).
Short statutory response windows: 48-hour initial notification to agencies; operator must file actions and a root-cause analysis within 14 days for the first tier; weekly wellhead temperature reports begin within 30 days and continue until resolution.
The operator must notify residents within a radius (statute specifies two to four miles at different tiers) and post weekly data online for mid- and high-tier events; OEHHA must publish health guidance adapted from federal CDC tools.
Administrative penalties: $10,000 per day for failing to meet specified reporting or notification duties; up to $1,000,000 per week where the department finds immediate substantial risk and operator gross negligence during the highest-tier events.
Deadlines and posting duties: CARB must adopt temperature-monitoring requirements consistent with the statute; the department must publish corrective-action minimum guidelines by July 1, 2027; operators with prior federal approvals must provide documentation to state agencies by July 1, 2026.
Section-by-Section Breakdown
Every bill we cover gets an analysis of its key sections.
Monitoring requirement and CARB rulemaking
The bill makes temperature monitoring mandatory by directing the State Air Resources Board to add landfill gas temperature requirements to its methane regulations. Practically, that means CARB will specify how frequently wellhead temperatures must be measured, the instruments or protocols to use, and recordkeeping standards so that data can drive the statute’s trigger logic.
Initial elevated-temperature tier (≈131°F): reporting, inspection, and corrective-action plan
When wellhead gas temperatures meet the initial threshold and other department criteria, the operator must notify CalEPA and the certified local enforcement agency within 48 hours, provide a root-cause analysis and an account of actions within 14 days, and begin weekly temperature reporting for each affected well within 30 days. Agencies are required to inspect and engage with the operator and to work toward a corrective-action plan to begin implementation within the statutory window.
Middle tier (≈146°F): multiagency involvement, public posting, and community notices
At the next temperature level the statute shortens some engagement windows and requires broader transparency: operators must post weekly well temperatures online, send monthly community updates, and support a CalEPA multiagency coordination group. The bill also directs OEHHA to produce and post community health information using CDC tools, which operators must mirror on their websites, increasing public access to technical and health information during sustained events.
Highest tier (≈162–170°F): emergency actions, permit suspension, and proclamations
For the highest sustained temperatures the statute makes available stronger tools: local agencies or the department can suspend permits for affected landfill portions if an imminent and substantial risk exists, and local entities may request or proclaim local or state emergencies. Those authorities can be exercised within statutory windows, and the statute contemplates ongoing multiagency review and corrective-action planning while emergency measures are in place.
Enforcement, penalties, and rulemaking procedures
The bill authorizes $10,000-per-day administrative penalties for specific reporting and notification failures and up to $1,000,000 per week for gross negligence that produces or prolongs a highest-tier event posing immediate risk. Penalties are deposited in a newly created Landfill Subsurface Fire Mitigation Account for use by the department to assist affected communities, with a statutory priority toward the community tied to the penalized landfill. The department must adopt emergency regulations to define event criteria and the statute carves out certain corrective-action rules from routine administrative-procedure requirements.
Interaction with federal higher-temperature approvals and public transparency
Operators that request higher operating temperatures under the applicable federal rule must notify state agencies within 48 hours of that request and later supply approvals received before set deadlines. The local enforcement agency and department must post those requests and decisions online, creating transparency around any state-level acceptance of higher temperature values at specific wells.
This bill is one of many.
Codify tracks hundreds of bills on Environment across all five countries.
Explore Environment in Codify Search →Who Benefits and Who Bears the Cost
Every bill creates winners and losers. Here's who stands to gain and who bears the cost.
Who Benefits
- Residents living within several miles of MSW landfills — receive mandated notices, monthly updates during sustained events, and access to OEHHA health guidance to inform protective actions.
- Local public-health and emergency-response agencies — gain clearer statutory triggers and interagency coordination authority to intervene earlier in subsurface heating incidents.
- Vulnerable communities adjacent to landfills — stand to benefit from the new mitigation account, which directs penalty revenues to affected communities for recovery and mitigation.
- State agencies (CalEPA, OEHHA, CARB) — obtain formal roles, authority, and information flows that centralize technical assessment and public communication during complex subsurface events.
Who Bears the Cost
- MSW landfill operators — face new monitoring, reporting, public-notice, corrective-action, and cost-recovery liabilities, plus significant exposure to daily and weekly administrative penalties.
- Local enforcement agencies — must increase inspection, oversight, and public-notice activity and coordinate constantly with the department, creating staffing and technical burdens (though the operator is liable for reasonable agency costs).
- State agencies (department and CARB) — must draft emergency regulations, publish guidance and post materials online, and coordinate a multiagency response, tasks that require staff time and technical capacity.
- Local governments and waste-management systems — may be forced to reorganize waste handling quickly if permit suspensions or emergency proclamations constrain landfill operations, shifting costs to municipal waste plans or haulers.
Key Issues
The Core Tension
The bill pits the need for rapid, protective action and transparent public notice against the technical uncertainty of subsurface temperature measurement and the operational and public-service consequences of shutting landfill operations; it forces a choice between acting quickly on imperfect data to protect communities and requiring more confirmatory analysis to avoid potentially disruptive enforcement.
AB 28 creates a practical framework for detecting and responding to underground landfill heating, but the statute leaves several important implementation choices to the department and CARB. The law repeatedly references "other criteria" (gas and liquid thresholds, number of wells over a geographic area) without specifying them; those metrics must be set in emergency regulations and guidance before actors can apply the statute consistently.
The bill also mixes numeric edits (multiple temperature figures and cadence phrases), which creates textual ambiguity that the implementing agencies will need to resolve when they write criteria and enforcement policies.
From a technical standpoint, wellhead temperature is an imperfect proxy for subsurface combustion risk: heterogeneity in waste, fluid migration, and sensor placement can produce hot or cold spots that complicate trigger determinations. That raises questions about when permit suspensions or heavy penalties are justified versus when additional sampling or diagnostic work is the right next step.
The statute attempts to balance speed (short notice windows and emergency authority) with process (root-cause analysis and corrective-action plans), but the speed of actions like permit suspension may create downstream waste-management disruptions if not carefully calibrated to technical certainty and continuity-of-service needs.
Try it yourself.
Ask a question in plain English, or pick a topic below. Results in seconds.