Long Beach Methane Zone

By April 7, 2023 No Comments

Long Beach Methane Zone

Much of the City of Long Beach includes areas with high levels of subsurface natural gas and methane gas.  Oil and gas fields known as the Wilmington, Long Beach, Seal Beach, and Long Beach Airport fields are located within and extending beyond the borders of the City of Long Beach.  These areas are now designated as the Long Beach Methane Zone. This zone presents a potential explosive hazard for buildings due to biogenic and petrogenic gases from decomposing petroleum deposits and landfills. For this reason, as of January 1, 2022, the Building and Safety Bureau is requiring methane testing and a mitigation plan for building construction projects.  This most commonly becomes a requirement when a grading, demolition, or new construction permit is requested for properties in the methane zone.

The Long Beach Methane Zone

The Long Beach Methane Zone is an area of potential high concentrations of methane zone gas. Methane soil gas infiltrate up from the subsurface and accumulate around buildings or structures, presenting a fire hazard if not maintained.   Methane gas is flammable and is an explosion hazard to the buildings or structure.

Decades of testing, research and geographic data processing lead to the Long Beach Methane Zone Map.  The city has published their Methane Zone Map here:  City of Long Beach: Methane Gas Mitigation and Oil Wells

So what can you expect when building and developing with in the Long Beach Methane Zone?

If new development falls with-in the Long Beach Methane Zone, then a methane soil gas investigation or a methane test, is required.  The results of the methane test may mean a vapor mitigation system may additionally be required, and must be approved by the City of Long Beach.  The methane testing provides the City with data about which methods of methane mitigation to use.  Testing and mitigation closely follows requirements set forth by the City of Los Angeles in the 1990s.  The sampling is relatively straightforward and is very commonly conducted by McAlister GeoScience.  The mitigation system designs are also very straightforward and the City of Long Beach and City of Los Angeles both provide detailed pre-approved design drawings.

During the permit application process, a City Development Coordinator determines if a site is located within the official Long Beach Methane Zone. If the site falls within the zone, methane testing and vapor intrusion mitigation will likely be required. Methane testing and vapor intrusion mitigation may also apply to sites that are near the official methane zone or near an oil well.  The city of Long Beach Building and Safety Bureau will inform you if testing and mitigation are required.

Methane Gas Mitigation

Methane mitigation is organized into three site design levels.  Depending on the level, a professional engineer incorporates certain passive or active mitigations. Level 1 is the least strict for sites with lower methane soil gas, and Level 3 is the most strict and comprehensive for sites with high methane soil gas.

The overall purpose for methane soil gas mitigation is to ensure the safety the building occupants.  More so, the City of Long Beach aims to eliminate the possibility of methane explosions and fires by using these methane mitigations.

Other Cities

The City of Signal Hill lies completely within the boundaries of the City of Long Beach and nearly the entire City of Signal Hill is in the Long Beach Oil and Gas Field.  The city of Signal Hill has their own requirements for testing and mitigation, these requirements are very similar to both the City of Los Angeles and City of Long Beach requirements.

The City of Los Angeles has had requirements in place for methane testing and mitigation since the 1990s associated with the development of the Los Angeles Unified School District Belmont Learning Center.  The City of Los Angeles requirements are the most strict and detailed due to the LAUSD litigation.  They also charge the highest fees and require “Certified” consultants who pay an annual fee to the planning department and have had their methods reviewed.  

Your city may be also be in a oil field or similar mitigation zone and may have their own requirements. Be sure to visit the CalGem Database to see if your property is in an area of concern. 


For more information, and or assistance determining if you property lies with in the Long Beach Methane Zone. Be sure to visit:  

For a free quote for methane testing or other technical services be sure to visit: https:


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