Service Life of the Buried System

An EPIC cell is a sequence of layers rather than a machine, and this eight-page paper takes the service-life question one material at a time: what is buried, what could end its life, and why those mechanisms are not active in the EPIC position.

Around 99% of the installed mass is sand, gravel and water, which has no degradation mechanism. For the polymer fraction, the paper sets out five ways a polymer fails (photo-oxidation, thermo-oxidation, sustained stress, chemical attack and biological attack) and explains why burial under 175 to 200 mm of sand removes ultraviolet exposure and damps temperature, leaving temperature as the only variable.

The chamber evidence rests on the December 2014 TEPPFA study with Borealis and LyondellBasell, which excavated polyolefin sewer pipe from five European sites after 12 to 38 years in service and concluded an in-service life of at least 100 years. The liner evidence draws on the Geosynthetic Institute's lifetime predictions for covered HDPE geomembrane, Queen's University incubation work and exhumed liners, and explains why EPIC specifies 1.14 mm EPDM to ASTM D7465 and does not accept PVC as an equal.

The paper also states where the claim stops: pumps, valves, float switches and controllers have indicative lives of 5 to 15 years and sit above ground or in accessible vaults. It separates the commercial warranty from the engineering service life, names aeration with core removal as the one maintenance item that matters, and closes with seven clauses that carry the service-life conditions into a project specification.