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SVCW 48” Force Main Improvement

LOCATION:

San Carlos and Redwood City, CA

DESCRIPTION :

The primary objective of this $45.5 million project was to construct a new fused 48-inch diameter 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 was part an overall 10-year Capital Improvement Program (CIP) to replace and upgrade aging infrastructure.

As part of Unit 1, 3300 linear feet of new pipeline was constructed using jacking shafts and microtunneling among other intricate construction methods such as ground probing and jet grouting. To accommodate the microtunneling, jacking and receiving shafts were built.  There were two jacking shafts (800 ton thrust capacity) and two receiving shafts each ranging from 24 to 36-feet in diameter and 45 to 50-feet deep.

An additional phase, Unit 4, was the design-build of a pipeline that included temporary tie-in installations adjacent to two existing pump stations.  These tie-ins were strategically located to allow for continuous operation of the force main while each pump station underwent re-construction.

Lastly, Unit 2 was the installation of 6,390 LF of 48″ HDPE pipe by means of open cut construction.

The project was awarded “APWA Project of the Year 2016” due to the complex nature of difficult soil conditions, mitigation of difficult environmental conditions, and work with the surrounding public to keep the inconvenience to a minimum.