This District Capital Improvement Program project included the construction of all components of Phase 1 of the Discovery Corridor Wastewater Transmission System (DCWTS). The project included: improvements to existing pump stations, construction of new pump stations, installation of 57,000 linear feet of sanitary sewer force mains ranging from 3- to 22-inch diameter, installation of 7,000 linear feet of gravity sewer pipe ranging from 4- to 30-inch diameter, 13 air relief vaults, manholes, erosion control, dewatering, traffic control and restoration. The force main construction included five jack and bores with casings from 12- to 48-inch, three of which were underneath Interstate 5.
This project had multiple challenges, including 2.5 miles of 24-foot deep dual HDPE force main in the Interstate 5 median that had to be laid on grade. While working on the Interstate 5 median, live traffic was on both sides of the work zone. Dewatering was required, as well as positive pressure shoring for the pipe installed over 20-foot deep. Material delivery ingress and egress of the median proved to be another challenge that Tapani had to overcome to keep the project running smoothly. The project consisted of seven incentive-pay milestones, and Tapani successfully met all milestones.