Methane Risks and Resolutions
April 25th, 2013Methane, a colorless, odorless, flammable “greenhouse” gas is better known as natural gas. Methane is commonly used for cooking, fueling buses and cars, and is an integral source of energy for industrial processes. Methane originates from the natural decomposition of organic materials. When sourced from natural gas reserves below the earth’s surface, methane is theoretically safe. However, there are many unmitigated sources of methane which can pose a risk to the public. Common sources of methane include municipal landfills, oil exploration activities, wetlands and swamps, and tar seeps. Methane can become trapped in an enclosed structure and overtime if there is not enough ventilation, it can become dangerous.
One disastrous case of methane build-up in a structure occurred in Los Angeles in 1985 at a Ross Dress-for-Less store at 3rd Street and Fairfax. Due to high concentrations of methane accumulated beneath the structure and not enough ventilation, the structure exploded and caught fire, resulting in extensive property damage and injuries. The source of the methane was believed to be from leaking oil wells in the vicinity of the store. This incident sparked the movement to create modern day methane safety regulations.
What ultimately resulted was the establishment of the Los Angeles Department of Building and Safety (LADBS) Methane Ordinance (2005). The LADBS ordinance established Methane Zones and Methane Buffer Zones within the city of Los Angeles to map areas where methane risk was considered highest. The zones are primarily defined by the proximity of properties to active or abandoned oil wells. LADBS established standards for testing properties for the presence of methane, as well as methods for mitigating methane risks.
The testing and mitigation requirements primarily apply to new buildings and building additions, however, we recommend consultation with a methane specialist when significant modifications to any structure are planned within a methane zone or methane buffer zone. The LADBS methane testing protocol requires a minimum of two methane test probes be established at any site within a methane zone or a methane buffer zone. The probes are set at five feet, ten feet, and 20 feet below the lowest proposed building slab elevation and each is measured for methane concentrations and methane pressure. A methane certificate is then issued by an authorized agency, signed by an architect, engineer, or geologist. Andersen Environmental is licensed by the LADBS as an authorized methane testing agency [License #TA10207].
Properties in methane buffer zones where little to no methane is detected will likely not require any methane mitigation. Properties in methane zones or properties where low concentrations of methane are detected may require passive mitigation systems. Properties where methane is detected in significant concentrations may require active mitigation systems. A passive mitigation may be something as simple as a methane barrier and passive ventilation system; however, an active mitigation system may require a sophisticated system consisting of a methane barrier, mechanical ventilation system consisting of inline fans, methane sensors, and methane alarms.
LADBS standards only apply to incorporated Los Angeles; methane risk zones, testing and mitigation standards have been established for other jurisdictions including unincorporated Los AngelesCounty, Huntington Beach, Santa Fe Springs, and Long Beach/Signal Hill.
For more information on methane, testing, mitigation design, or standards,
Please feel free to contact Dennis Ironi at 310-854-6300
Or visit Andersen Environmental’s methane information page at
property at some point in your career. Andersen Environmental would like to present our capabilities and experience to empower you to navigate through the process of evaluating said contamination and achieving site closure, if warranted.
The soils beneath the subject property and adjoining residential property were treated using a fixed vapor extraction system to reduce the chlorinated solvent concentrations in soil, soil vapor, and groundwater. The site continued to be monitored and remediation continued until the Orange County Health Care Agency (OCHCA) issued a no further action letter for the property, as remediation goals established for the protection of human health and the environment were achieved by Andersen Environmental’s efforts.
