MICROBIAL INDUCED CORROSION (MIC)has been increasingly evident in concrete manholes and related sanitary sewer structures for decades. MIC occurs when sulfuric acid, generated from raw sewage, reacts with the properties of cement to diminish the integrity of concrete manhole bases and related structures. Hydrogen sulfide (H2S), in anaerobic and aerobic forms, has the capacity to severely damage concrete manhole structures. Utility operators, civil engineers and the precast concrete industry can attest to this harm.
Since the introduction of the US Clean Water Act of 1980 eliminated certain toxic heavy metals from wastewater, effluent MIC has reached acute levels in sanitary and wastewater sewage systems and new steps must be taken to reduce MIC in sanitary sewer system. Liner material imbedded in newly poured concrete provides a dense, impervious, and continuous plastic lining for the manhole base, walls and cover to protect the concrete substrate from destructive acid attack.