If you are considering a new home, an addition or a system change near an oil or gas well in Huntington Beach, City Specification No. 429 may affect the plans. The Huntington Beach Fire Department strongly recommends against building structures over or near abandoned wells or hydrocarbon-contaminated soil. Construction may be allowed when an abandoned well can be proven safe and affected soil conforms to City Specification No. 431-92, subject to other land development requirements.
The specification addresses proposed construction and does not say existing homes must be tested or retrofitted. This guide is general information, not legal advice.
What projects does Specification 429 cover?
Specification 429 applies to proposed construction projects with the potential for subsurface methane.
The document says compliance is required under Huntington Beach Municipal Code Sections 17.04.170, 17.56.110 and 17.56.450. Its header also refers to Huntington Beach Fire Code Sections 17.56.080, 17.56.110 and 17.56.460.
For the Huntington Beach Methane Overlay District, the specification points to page V-EH-19 of the Huntington Beach 1994 General Plan or its most current update. It does not provide a property map or identify particular streets. A buyer or seller considering construction should check the project location against the referenced city material and ask HBFD how the current specification applies.
The October 2025 document replaces the October 2022 version. Huntington Beach lists it as “Specification 429, Methane Mitigation Requirements” on the Fire Department City Specifications page.
When is mitigation required without testing?
Mitigation is required regardless of testing when a proposed building or enclosed structure falls within either of two location tiers.
The first tier covers a structure proposed within 100 feet or less of an active or abandoned oil or gas well. The exception is a “hydrocarbon-free” well when full surface-to-total-depth data has been submitted to the California Geologic Energy Management Division, known as CalGEM, for review and certification, and that certification has been provided to HBFD.
The second tier covers a structure proposed within 300 feet or less of a gas seepage zone.
Other cities set their own rules. See the guides for Long Beach methane zones and oil wells and Placentia combustible soil gas and abandoned wells.
When might methane testing be required?
Testing depends on the proposed project’s distance from wells, field boundaries, disposal sites and other locations identified by HBFD.
A building less than 100 feet from a well may require testing to determine the level of mitigation. One stated exception applies to a single-family dwelling remaining under 5,000 square feet. It does not require testing because a methane barrier is automatically required.
Testing is required when a proposed building is between 100 and 300 feet from a well and also within 100 feet of a CalGEM-defined oil or gas field administrative boundary. Both parts of that location test apply.
From 300 to 1,000 feet of a well, testing is at the discretion of the Fire Code Official based on site-specific history.
Testing is also required within 1,000 feet of the refuse footprint of an operating, closed, abandoned or inactive landfill or disposal site. For such a project, the specification directs contact with the Local Enforcement Agency, the Orange County Health Care Agency, under California Code of Regulations Title 27. HBFD may also identify another location as subject to gas migration.
How does the testing process work?
Testing starts with a work plan prepared by a California-registered Professional Engineer or Professional Geologist and submitted to HBFD for approval.
The investigation follows the Los Angeles Department of Building and Safety “Site Testing Standards for Methane,” Public/Building Code 2020-101, or its most current update. The final report must be included in the architectural plan set submitted to the Community Development Department and must also go to HBFD.
HBFD makes the final determination on compliance. The department may use city consultants, and its council-approved fee schedule allows recovery of consultant fees from the applicant. The specification gives no dollar amounts for testing, consultant review or mitigation.
Test results remain valid for five years from the testing date. That timing matters when design, review or construction may extend over several years.
What do the test results determine?
The measured methane concentration determines whether the test calls for no barrier, passive mitigation or active mitigation.
A result under 5,000 parts per million by volume, written as ppmv, does not require a barrier based on that test result. A result from 5,000 ppmv to under 12,500 ppmv calls for passive mitigation. Sensors and alarms are required when results exceed 10,000 ppmv.
A result of 12,500 ppmv or more calls for active mitigation. The exception is for single-family and two-family homes, which may use passive mitigation with sensors and alarms.
Passive mitigation consists of a gas membrane barrier and sub-slab venting. Active mitigation adds forced sub-slab air venting.
What happens when an abandoned well is nearby?
Abandoned wells within specified distances must be vented, and wells on the parcel require CalGEM and HBFD documentation before building plan approval.
Every abandoned well within 100 feet of a proposed building must be vented. Venting also applies to a well within 300 feet when it is under or within 5 feet of a paved surface located within 25 feet of the building.
If wells are on the parcel, a CalGEM Site Plan Review must be on file with HBFD. The wells must meet current CalGEM abandonment requirements, and a CalGEM closure letter must accompany the application for the HBFD well abandonment permit. That permit is required under City Specification No. 422, the Oil Well Abandonment Permit Process, before building plan approval. Every abandoned oil well on the subject parcel requires an oil well vent cone.
A Huntington Beach owner asked us about adding living space after an old oil well appeared in the property research. He assumed an abandoned well no longer affected development because it was not operating. We advised him to confirm the well’s recorded location and the city’s building requirements before placing the addition over or near it.
What does a passive system involve?
A passive system uses a specified gas membrane barrier together with sub-slab venting.
The membrane must be a manufactured geomembrane with a minimum dry thickness of 15 mils and a gas transmission rate below 40 ml/m2/day under ASTM D1434. HBFD must issue a methane barrier permit before work begins. The membrane is smoke-tested under HBFD observation before final inspection.
The vent risers include a test tee with a red hex-head plug that must remain red for the structure’s duration. A placard must read “Methane Vent Test Location.” The specification also calls for caution signs on the vent pipe and a warning sign at the main entry.
When sensors and an alarm system are required, the owner must maintain them according to the manufacturer’s recommendation and applicable NFPA 72 standards. False alarms are subject to False Call fees. An alarm in an R3 occupancy, meaning single-family and two-family homes per the building official, does not need to alert HBFD.
Do later changes to the system need a permit?
Yes. Work on methane mitigation measures can proceed only after HBFD has issued a permit.
All mitigation measures require a deferred submittal to the department. The permit rule covers new installations as well as alterations, modifications and penetrations of an existing system.
If construction is being considered before a sale, a pre-listing inspection guide can help keep a general property review separate from the city’s project-specific methane process. Transaction paperwork is a separate subject covered in the California seller disclosure guide. Specification 429 itself does not discuss seller disclosure forms.
The short version
Huntington Beach discourages building over or near abandoned oil or gas wells or hydrocarbon-contaminated soil, but Specification 429 provides a path for proposed construction when its requirements and other land development rules are met.
The key checks are the proposed structure’s location, its distance from wells or seepage zones, whether testing applies, and whether well records, venting or mitigation permits are required. HBFD approves the testing work plan, receives the final report and makes the final compliance determination.
If the project may affect a sale decision, start with city records and the proposed plans, then use the home value tool.
Common questions
Does every property near an oil or gas well require methane testing?
No. Specification 429 sets different rules by location and project. Some proposed structures require mitigation regardless of testing, while testing may be required or left to the Fire Code Official's discretion in other locations.
Does a single-family home under 5,000 square feet need testing within 100 feet of a well?
The specification says a single-family dwelling remaining under 5,000 square feet will not require testing because the home will automatically require a methane barrier.
How long are methane test results valid?
Specification 429 says test results are valid for five years from the date tested.
Can an existing methane system be altered without a permit?
No. The specification says work can take place only after a permit is issued, including alterations, modifications or penetrations of an existing system.
