Venice Dual Force Main

During severe wet weather, peak flows to Los Angeles County’s California Venice Pumping Plant exceed the capacity of the only force main carrying wastewater away from the plant. The resultant risk is that wastewater could spill onto city streets and surface waters. The 50-year-old sewer is in constant use and cannot be shut down for inspection or maintenance. This poses a reliability problem for the City of Los Angeles.

To address this, the City is adding a second, larger (54-inch ID [1,372 mm]) force main sewer to operate in tandem with the existing one. The combined system will meet current peak wet weather flows and add operational flexibility and reliability.

In late 2007, the Tetra Tech/Jacobs Associates design team began work on the project, with Jacobs Associates providing specialized trenchless design services for two segments along the alignment. After evaluating several options and discussions with the City, the team and the City selected microtunneling as the method of installing the second force main. One of the new segments will cross under the Marina Del Rey Channel. This segment, with a total length of nearly 1,800 feet (550 m), will be one of the longest microtunnel drives in North America.

In addition to providing recommendations for trenchless installation methods, Jacobs Associates provided recommendations for two shafts approximately 70 feet (21 m) deep and below sea level. We also developed design plans and specifications associated with microtunneling and work shaft construction.