Methane is a naturally occurring, odorless and colorless gas which can be released from rock and soils beneath residential homes, condominiums and apartments, commercial buildings and industrial parks that are in areas of former and active oil fields, swamps, landfills and where near-surface naturally occurring petroleum deposits are present. Methane gas is flammable and when present in high concentrations, can become an explosion hazard, especially within enclosed structures, regardless of foundation type (slab on grade, raised floor, etc.).
The City of Los Angeles Department of Building and Safety (LADBS) has developed a map of Methane Zones, which are surrounded by Methane Buffer Zones. These are areas where the potential for methane gas to be present at hazardous concentrations in the subsurface is elevated, compared to other areas of the City of Los Angeles. These areas generally surround former oil production fields, which are located throughout the city. Due to the potential for explosive gases to accumulate in structures within these mapped areas, the LADBS has established requirements for methane testing. Methane testing is required when a property within these mapped areas is redeveloped or an addition is proposed for an existing structure. This means methane testing is required and results must be presented to the LADBS before construction permits will be granted. If elevated levels of Methane are measured, the methane hazard must be mitigated by incorporating the appropriate level of mitigation measures into the design of your proposed improvements.
Andersen is an LADBS approved and certified methane testing agency utilizing methane testing procedures based on the “Site Testing Standards for Methane” document provided by the LADBS. The LADBS procedures included in this document establish the methane sampling frequency and depth based on the square footage of the site, the total depth below current grade of all proposed improvements, and the anticipated depth to groundwater at the site. The results of our soil gas testing will provide the appropriate level of methane mitigation, if required, for the proposed development. Once methane testing results are obtained at a property, methane mitigation design may be required for the project by the LADBS prior to issuance of building permits, depending on the maximum concentration and pressure of methane measured at the site. The design methane concentration and design methane pressure for the site will determine whether Level I, Level II, Level III, Level IV or Level V Mitigation Requirements will be appropriate for the property, as shown in Table 1A and Table 1B of the “Standard Plan for Methane Hazard Mitigation” provided by the LADBS. Andersen’s Civil Engineers can assist with the design of the methane mitigation system when mitigation is shown to be necessary.
LADBS standards only apply to incorporated Los Angeles; although methane risk zones, testing and mitigation standards have been established for other jurisdictions including unincorporated Los Angeles County, Huntington Beach, Santa Fe Springs, and Long Beach/Signal Hill.
For more information about LADBS requirements with respect to methane and methane mitigation design , or to find out if your property is within a Methane Zone or Methane Buffer Zone, please feel free to give Andersen a call at (310) 854-6300.
- Los Angeles Methane and Methane Buffer Zones
- Los Angeles Oil Wells, Oil Fields, and Landfill Sites
- Los Angeles Methane Code
- Los Angeles Site Testing Standards for Methane
- Los Angeles Methane Seepage Regulations (Division 71)
- Los Angeles Department of Building and Safety Methane Mitigation
Los Angeles Methane Zone Map
To learn more about methane testing today, call us at 310-854-5453.