Silicon Valley Clean Water Gravity Pipeline Project

Redwood City, CA

Silicon Valley Clean Water Gravity Pipeline Project

2023 | INSPIRED Owner | National Award — Excellence | National Award — Merit | Water / Wastewater

Silicon Valley Clean Water Gravity Pipeline Project


Best in Design (Engineering):

The Silicon Valley Clean Water Gravity Pipeline Project shines a spotlight on a process typically out of sight and out of mind: Wastewater transportation. It was a feat of engineering while also considering public safety and long-term sustainability. The project team implemented numerous innovative technical solutions that allowed construction to finish below budget and seven weeks ahead of schedule, including holistic approaches such as using a Tunnel Boring Machine to complete the project which offered financial, environmental and schedule benefits. Another engineering innovation was designing the pipeline to eliminate the entry of operations and maintenance personnel into the system for its intended 100-year lifespan. Access covers were installed in specific locations to allow for remote visual inspections using CCTV equipment or drones.

I.N.S.P.I.R.E.D. Owner (Innovative Newcomer Showcasing Preparedness, Insight, Readiness and Enduring Diligence):

This was the first design-build project for Silicon Valley Clean Water. It is the largest Fiberglass Reinforced Polymer Mortar to be used in a North American project and the first Tunnel Boring Machine project in North America completed with progressive design-build. To ensure alignment with design-build Best Practices, the team enlisted a DBIA Certified third-party risk mediator who led risk identification workshops, built the risk register, quantified the risks with time and cost impacts, and assigned responsible parties. The team prioritized collaboration from first solicitation through completion and physically co-located to the construction site. Design workshops, weekly meetings and daily task force updates cultivated a positive teaming environment and culture of mutual respect throughout the project.

Excellence in Water/Wastewater

Merit Award – Water/Wastewater

The Silicon Valley Clean Water (SVCW) Gravity Pipeline Project shines a spotlight on a process that is typically out of sight and out of mind: wastewater transportation. SVCW undertook this project as part of a $580M Regional Environmental Sewer Conveyance Upgrade (RESCU) Program to rehabilitate and convert its 50-year-old raw wastewater conveyance system at the end of its useful life from a force-main system to a gravity conveyance system.

The project consisted of the design and construction of 3.3 miles of fiberglass reinforced polymer mortar (FRPM) pipe inside a concrete-segment Tunnel Boring Machine (TBM) tunnel and three shafts. SVCW wanted a new system to serve the public, support community health and protect the environment for 100 years.

A “Boring” Solution to Minimize Community and Environmental Impacts

In June 2021, a 16-ft.-diameter TBM mined through a concrete shaft, completing its 3.3-mile journey beneath an airport taxiway, a major suburban thoroughfare, an active and aging sewer force main, and two local residences. SVCW used TBM technology to avoid disrupting surface uses along the entire alignment. By boring a tunnel and installing the large-diameter pipe underground, SVCW significantly reduced community and environmental impacts along the San Francisco Bay Margin.

One of the project’s more unique requirements involved the intricate design and construction of two vertical drop structures where existing municipal sewers connect to the new pipeline. With a drop of up to 30-ft. in elevation head, these structures act as a means of potential and kinetic energy dissipation and conveyance.

Arup used hydraulic analysis to demonstrate viability of reducing approximately one-third of the pipeline length to a 10-ft. internal diameter. This allowed for the nesting of the smaller-diameter pipe inside of the larger-diameter pipe during transportation from the fabricator in Indonesia, saving approximately $1 million in transportation costs and providing a massive reduction in carbon footprint.

The SVCW Gravity Pipeline Project became the first TBM project in North America to be completed using Progressive Design-Build (PDB) as the project delivery method. Despite challenging ground conditions and a global pandemic, the project finished on time and on budget, an outcome SVCW largely attributes to the collaboration fostered by PDB. It was also SVCW’s first design-build project, and its success paves the way for future projects at the authority as well as the tunneling and wastewater treatment industries at large.

Design-Build Team

Client/Owner: Silicon Valley Clean Water
Design-Build Firm: Barnard-Bessac Joint Venture
Engineer: Arup
Specialty Contractors: Tanner Pacific, Inc.; Future Pipe Industries, Inc.; Traylor Shea Precast, AJV; Herrenknecht Tunneling System USA, Inc.; Drill Tech Drilling and Shoring, Inc.
Owner Advisor: Kennedy Jenks Consultants
Project Cost: $228 Million
Construction Duration: 44 Months

Silicon Valley Clean Water Gravity Pipeline Project

Silicon Valley Clean Water Gravity Pipeline Project

Silicon Valley Clean Water Gravity Pipeline Project