Effective Stress (σ’) “Effective Stress” (σ’) is a geotechnical engineering term. Effective Stress is a function of “total stress,” and is due to the solid particles of soil. Effective stress represents an excess of stress above pore-water pressure (or neutral stress). Effective Stress Formula Effective Stress = Total Stress – Pore-Water Pressure.

Maximum Soil Screening Levels (MSLs) Maximum Soil Screening Levels (MSLs): MSLs are a list of risk-based hydrocarbon concentrations for soil pollution evaluations, that is developed by the California Regional Water Quality Control Board. These screening levels are based on the Leaking Underground Fuel Tanks (LUFT) Manual, for cleaning up soil contamination from leaking USTs. However, MSLs…

Control Panel in a Methane Mitigation System Control Panel of a Methane Mitigation System: A methane mitigation control panel is the brain behind the active mitigation system. In accordance with the Los Angeles Department of Building and Safety (LADBS) Methane Code, Ordinance Number 175790, a control panel synchronizes methane alarm units with sensors and the…

Mechanical Extraction System Mechanical Extraction System: Per the Los Angeles Department of Building and Safety (LADBS) Methane Code, Ordinance Number 175790, a Mechanical Extraction System is one of the Active Methane Mitigation criteria for methane mitigation systems in buffer zones and methane zones.  A mechanical extraction system uses machines that remove methane gas from below…

Trench Dam Trench Dam: Per the Los Angeles Department of Building and Safety (LADBS) Methane Code, Ordinance Number 175790, a trench dam is part of a methane mitigation system. A trench dam is essentially a subsurface barrier that exists within a furrow or ditch, that is adjacent to the foundation of a building in a…