Vent Riser in Methane Mitigation: As per the Los Angeles Department of Building and Safety (LADBS) Methane Code, Ordinance Number 175790, a vent riser is a cast iron or ABS pipe that runs through the building walls (vertically). A vent riser is part of a methane mitigation system and has joints and fittings that connect to the perforated horizontal pipes under the impervious membrane. This device conveys methane soil gas from under the methane barrier, and discharges it into the atmosphere.
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