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Under the river and through the city will go Sacramento Regional County Sanitation District’s (SRCSD) $600-million Lower Northwest Interceptor (LNWI), a 19-mile pipeline being built with the aid of more than 22 contractors and subcontractors using some of the most sophisticated digging equipment on the planet.

The pipeline, which will serve the fast-growing Natomas and West Sacramento areas. SRCSD parceled out the work to assure competition and contracting capacity. Tasks are spread among nine projects, including two new pump stations, five pipeline projects and 14 tunneled crossings–two under the Sacramento River. During peak wet weather flows, the system will handle as much as 200-million gallons per day of water. It will serve 200,000 homes, linking them to the 181-mgd Sacramento Regional Wastewater Treatment Plant in Elk Grove. These days, the plant is running well under its design capacity, even during wet weather. It was last expanded more than 20 years ago, and district officials believe they have at least another decade before more treatment capacity will be needed.

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The project required the acquisition of right-of-way for more than 230 parcels, 122 permits and satisfying a stakeholder list of more than 5,000 people. SRCSD is funding the project with a bond issue. The expanded rate base is expected to be sufficient to retire the debt, officials say.

Despite an excessively wet winter and spring, Construction Team Lead Neil Mann says the project is on time because "rain delays were build into the schedule. Most of the work to this point has all been preparation for the big event anyway." Mann, technically an employee of program manager MWH, Broomfield, Colo., is responsible for program administration, design review, public outreach, surveying and mapping and environmental monitoring.

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Scheduling is paramount in a project with so many moving parts. Work started before the program management assignment was granted. MWH conducted the corridor analysis and prepared the preliminary design. "We also provided support to the political negotiations conducted between SRCSD, West Sacramento and Sacramento," Mann says.

Those negotiations were key to making the massive project cost affordable and had a large impact on routing. "It was a great opportunity to add the City of West Sacramento, which was facing significant cost to bring their facilities up to modern specifications," says Neal Allen, principal engineer for SRCSD. "It also allowed us to bring in new ratepayers," he adds.

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The project started with the New Natomas Pump Station (NNPS), which replaces an existing, smaller pump station and receives wastewater from the Upper Northwest Interceptor and local Natomas trunk sewers. Omaha, Neb.-based HDR, Inc. designed the $115-million pump station and its sister, South River Pump Station (SRPS). West Los Angeles-based Psomas is the construction manager and Kiewit Pacific, a division of Omaha, Neb.-based Peter Kiewit Sons’ Inc., is the contractor.

The two stations will ultimately include six 2,000-hp pumps. NNPS pumps into dual 60-in diameter force mains and the SRPS pumps into dual 66-in diameter force mains. The wetwell arrangement at both pump stations includes a self-cleaning...