LA County Methane Gas Hazard Mitigation Standards
The County of Los Angeles Department of Public Works Environmental Programs Division developed codes and standards for gas hazard mitigation. Moreover, the LA County EPD Methane Code includes landfill gas protection systems and methane gas plan protection systems.
LA County code declares that a gas protection system is necessary if a structure is within 1,000 feet of landfills. Additionally, the Environmental Programs Division flags properties within 300 feet of a methane gas hazard. EPD monitors properties with environmental reports confirming the presence of contaminated soil hazards. Similarly, an active, abandoned, or idled oil or gas well is classified as a methane gas hazard.
LA County Methane Gas Protection System
LA County defines two types of gas control systems; Passive and Active Systems. A Passive System will include sub-slab perforated pipes for purposes of ventilation and an Impervious Membrane, which shall prevent the diffusion of gas into a structure. In addition, the Code also recommends using Active System components, which can include a Gas Extraction Well System or Air Injection Well System.
Single-Family dwellings located within the LA County region must comply with the Methane Gas Control requirements. Still, significant exceptions may be applied to make the design and construction of these systems more cost-effective.
LA County Methane Gas Hazard Monitoring System
The LA County code mandates the utilization of monitoring probes, which the responsible design engineer measures and maintains according to an operation manual. Furthermore, Engineers record frequent methane gas measurements and continuously provide them to LA County as long as the structure exists. After five years of consistently low methane concentrations within the monitoring probes for a project, the maintenance program can be waived. The design engineer must submit this to LA County for approval.
Methane Gas Hazard System Design and Construction
A responsible professional engineer must prepare a gas hazard mitigation systems design. The prepared design must specify all gas mitigation requirements based on the specific plans prepared by the Architect and Structural Engineer. LA County reviews the Methane Mitigation Design, the design engineer holds responsibility for all aspects of the gas control system. The Methane Mitigation Design specifies the extent of the mitigation requirements based on the environmental and historical reports.
During the construction of the structure, the General Contractor supervises the development of the gas protection system design. Nevertheless, a licensed Methane Mitigation Contractor or Gas Protection Contractor installs the methane Gas Control System.