Napa Valley, California – In partnership with the Napa County Flood Control & Water Conservation District (NCFCWCD) and the United States Army Corps of Engineers (the Corps), MWH has completed a critical element of the multi-year, $250 million Napa River Flood Protection Project in Napa, California.
The effort included the remediation and flood terrace construction of a 2000-foot length of the Napa River where former bulk oil storage impacted soils and groundwater. The two-year project included the construction of extensive sheet piles, a site-specific 1,000 gallons per minute water treatment plant and a comprehensive soil sampling mechanism, conducted under regulatory oversight. In total, MWH excavated 325,000 cubic yards of soil and constructed a series of river terraces along the entire 2000-foot length as part of the Project’s overall flood protection design. Approximately half of the excavated soil (147,000 cubic yards) was contaminated. This equated to 236,000 tons of contaminated material, and took about 8700 truckloads to transport to a disposal site in Stockton, about 50 miles east of Napa.
When complete, the overall Napa River Flood Protection Project will provide 100-year flood protection to the City of Napa and surrounding areas. The overall project includes the construction of river terraces, flood walls and levees along seven miles of the Napa River. Additionally, the project creates over 400 acres of wetland habitat to improve the river’s water quality. This complex project also includes construction of several new roadway bridges, relocation of railroad tracks, as well as significant recreational trails. MWH will continue to play an integral role in the Napa River Flood Protection Project, providing project controls support services to NCFCWCD and facilitating cost recovery for remedial actions performed.
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About MWH
Headquartered in Broomfield, Colo., MWH is a private, employee-owned firm with approximately 6,000 employees worldwide. The company provides water, wastewater, energy, natural resource, program management, consulting and construction services to industrial, municipal and government clients in the Americas, Europe, Middle East, India, Asia and the Pacific Rim. For more information about MWH, please visit the company’s Web site at www.mwhglobal.com.
