V-1 W Vista Way Sewer Phase 1 in Vista, CA
Prime contractor on a $6.49M city sewer upgrade, installing over 3,000 LF of trunk main using open cut and micro tunneling.
Owner: City of Vista
Location: Vista
Designer: KEH & Associates
Contractor: Orion Construction Corporation
Delivery Model: Design-Bid-Build
Contract Value: $6.5 million
Schedule: 2019-2020
Scope: The project consisted of installing 3,096 LF of 12"–15" PVC sewer trunk main, 22 new 5’ and 6’ diameter manholes, reconnecting 16 laterals, and excavating and shoring the launching and receiving pits for micro tunneling up to 35' deep. Since this was an operating system, bypass pumping systems were installed to maintain operations. All roadways were repaved with new traffic control loops, Redflex camera sensors, and median construction to the city of Vista standards.
Orion also provided design-build support to the City after identifying the need to reroute 60% of the new main away from a high-pressure gas line. This involved redesigning the pipeline and using an innovative ‘boomerang’ launching pit for micro tunneling, allowing tunnel launches from both directions in a single pit. This approach eliminated the need for an extra pit and helped keep the project on budget.
Challenges: The project faced challenges due to trench depths of 12’-25’ in narrow City streets during open-cut installations. Micro tunneling pits were excavated to depths of 35’ with beam and plate shoring. A total of 685 LF of 42”- diameter steel casing was installed using micro tunneling, with a 15” PVC pipe inside the casing. This work crossed Caltrans ROW, requiring additional coordination and permits, which Orion secured for both the pipeline installation and traffic control setup. Bypass pumping was implemented in sewer-replacement areas, and specialized groundwater treatment was required before discharge. A discharge permit was obtained from the Encina Wastewater Authority to return groundwater to the sewer system. Due to heavy traffic, visible traffic control was essential, leading to most work being done at night.
Results: The resulting system completely upgraded a section of the sewer system in Vista with a more efficient layout and less infrastructure moving forward. This will keep operational and maintenance costs lower in the future.
