SBSA Pipeline Microtunneling Scheduled to Begin Monday, October 7

            South Bayside System Authority's $45.5 million pipeline improvement project initiates a major step Monday with the beginning of microtunneling under Inner Bair Island, which is part of the Don Edwards San Francisco Bay National Wildlife Refuge.

            SBSA's Jacking Shaft 2 is located on the property owned by the U.S. Fish & Wildlife Service (USFWS) near the new pedestrian bridge, approximately 150 feet east of Uccelli Boulevard. Receiving Shaft 2 is located on the Inner Bair Island levee at the southeast corner of the levee, which is managed by USFWS.

            Microtunneling is a process that uses a remotely controlled Microtunnel Boring Machine (MTBM) combined with the pipe jacking technique to directly install product pipelines underground in a single pass. This process avoids the need to have long stretches of open trench for pipe laying. This method is also ideal for installation of pipe under sensitive habitats, waterways and other important infrastructure such as highways and railroads.  Microtunneling is a method of underground construction that does not disturb the surface between the two points of "launching" and "receiving." (See this link for showing microtunneling:  https://www.youtube.com/watch?v=xO-fKEZJNtU) 

            The primary objective of the project is to construct a new 48-inch high density polyethylene (HDPE) sanitary sewer pipeline, replacing a pipe that has a history of leakage and damage because of the unstable "bay mud" ground conditions in the area. The existing 2.5 mile, 48-inch force main was constructed in 1971; its replacement with the new pipe is part of SBSA's overall $400 million, 10-year Capital Improvement Program (CIP) to replace and upgrade aging infrastructure.

            The new force main section will operate like the existing one, conveying sewage from the Redwood City Pump Station to the San Carlos Pump Station as part of the overall sewage conveyance system which runs from Menlo Park to the SBSA treatment plant in Redwood Shores. The installation of a new HDPE pipe will allow movement in the pipe to occur without leaking and will take over the conveyance functions of the problematic force main.

            By replacing the force main, SBSA will improve pipeline reliability, reduce service disruption and reduce maintenance costs associated with pipe leaks.

            Other project objectives include:

• Ensure the reliable operation of the overall sanitary sewer conveyance system in accordance with regulatory agency permit conditions.
• Reduce the likelihood of spills and discharges of untreated water to the surrounding environment, which has occurred occasionally with the existing reinforced concrete sewer force main.