Underground tank sump and piping system

Claim 1

An underground storage tank and a sump and piping assembly therefor comprising an elongate, generally cylindrical tank installed underground with a longitudinal axis thereof extending generally horizontally, a manway fitting in an upper wall portion of the tank, the manway fitting including a tubular portion in communication with the inside of the tank and an upper external flange, a cylindrical sump mounted underground on the flange of the manway fitting in upwardly spaced relationship to the upper wall portion of the tank and including a bottom wall and a cylindrical sidewall, and piping in communication with the inside of the tank through the bottom wall of the sump, there being no communication between the sump and the inside of the tank except through said piping, said piping also communicating with an above-ground dispenser through the sidewall of the sump, an underground portion of the piping leading to the dispenser from the sump being provided with a double wall including an inner wall and an outer wall, and said outer wall restraining any liquid leaked from said inner wall from contaminating the environment by conducting the leaked liquid through the sidewall to the inside of the sump.