500 SOUTH DIVERSION, PHASE II – PUMP STATION

Project Description

The project included construction of a pump station, including the associated vaults, sewer pipeline installation, onsite excavation, dewatering, shoring, sitework improvements, and all other activities needed to complete the work. It was also been necessary to protect and maintain access to onsite buildings and facilities. The pump station building constructed is 45-feet below grade with cast-in-place concrete, with CMU block 20-feet above grade. The pump station includes two wet wells with a dry pit between them, designed for six dry pit, submersible pumps. The wet wells are trench-style and self-cleaning. Construction included installing four pumps and provides space for future installation of two additional pumps. The pump station building includes a chemical room with a 5,000-gallon ferric chloride storage tank and metering pumps for odor control. An onsite odor control scrubber system was installed that included associated blower, pumps and appurtenances. An outdoor diesel standby generator and diesel fuel storage was constructed. Offsite improvements included constructing vaults and tie-ins to connect to both of the existing 36-inch 500 South sewer mains and the 42-inch Orange Street sewer trunk main, a grinder vault, various manholes, necessary piping, and surface restoration associated with diverting flow from these sewer mains to the pump station. There was a need to depressurize an aquifer that was 90-feet below grade. COP, with the help of Fawsons Drilling and Gerhart Cole, designed and installed five depressurization wells. The shoring and excavation for the 45-feet-deep structure consisted of installing 75-feet sheets by Desert Deep Foundations (DDF). COP then began excavation and assisted DDF with installation of the concrete waler as the 30,000 CY excavation advanced downward. Almost 3,000 CY of concrete walls for the main structure were 3.5-feet thick at the base and tapered to 2-feet as they approached the surface. The offsite utility work averaged 25-feet deep in the roadway, with numerous existing utility conflicts and coordination.