Northeast Interceptor Sewer

With a $162 million construction value, the Northeast Interceptor Sewer (NEIS) is the second largest construction contract ever awarded by the City of Los Angeles. The project upgraded the City’s aging sewer infrastructure and allows for future development. NEIS was recognized as the Outstanding Government Civil Engineering Project for 2005 by the American Society of Civil Engineers, Metro Los Angeles Branch. It was also distinguished as one of the year’s outstanding achievements in public works by the Southern California Chapter of the American Public Works Association.

Jacobs Associates provided multiple services during planning, design, and construction of this deadline-driven project. As tunneling specialist prime consultant, we led a team of 25 subconsultants supplying preliminary and final design. During construction, we provided construction management and engineering services as part of an integrated consultancy team led by the City’s construction management personnel.

The NEIS is an 8-foot-diameter (2.4 m) sewer consisting of a concrete carrier pipe with a protective lining. It runs 5.3 miles (8.5 km) under the densely populated eastern portion of downtown Los Angeles. Tunneling proceeded under challenging ground conditions, with alluvial soils, weak sedimentary rock, and up to 100 feet (30 m) of groundwater pressure. Tunnels were driven from deep shafts, with some work sites having severe space limitations due to urban density. Because of the varying geology and strict project schedule, the contract required three tunnel boring machines: two earth pressure balance machines and one shielded rock machine. Initial support consisted of precast concrete segmental linings.

The NEIS tight project schedule was driven by a Cease and Desist Order deadline imposed by the Regional Water Quality Control Board. NEIS became operational three days ahead of schedule.