MGE, as the joint venture managing partner in Associated California Engineers, LLC, completed the design documentation report (DDR), plans, specifications, and cost estimating for modification of the reach of Napa Creek through the City of Napa between Main Street and Jefferson Street to increase channel capacity by adding flood plain terraces and two underground reinforced concrete box culverts to serve as flood bypasses. The channel improvements include re-grading approximately 2,400 feet of the existing Napa Creek channel to smooth and remove obstructions, and the construction of overbank flood plain terraces, floodwalls, berms, and hydraulic grade control structures to create riffles and pools. Twin-cell 12-foot high by 11-foot wide box culverts are being constructed at two locations to carry flood flows at creek locations prone to flooding. The first bypass culvert extends from just downstream of Main Street to just upstream of Pearl Street, a distance of 440 feet. The second bypass culvert is 550 feet in length and extends from Behrens Street to just downstream of Seminary Street. Civil improvements included the reconstruction of 3 parking lots, design of 5 street intersections, wet and dry utilities design and relocation, detailed staging and phasing for the 30-month construction duration and implementation of aesthetic treatments and ADA accommodations throughout the project. Creek reconstruction/restoration included bio-engineered channel and bank treatments, in-water wood structures and 5 grade control structures to accommodate an increased flood flow regime and provide environmental and habitat enhancement.

Responsibilities also included preparation of utility conflict maps, and coordination with the Napa County Flood Protection District, City of Napa and other project stakeholders. MGE is currently providing construction support services for this project under a separate IDIQ contract. Construction for this $15+ million project was awarded in August 2010 and is expected to be complete in 2013.

Key Staff:
Project Manager/Structures Lead: Bob Sennett
Civil Lead: Jeff Crovitz

Key Facts:
Construction expected to be completed in 2013
Construction cost: $15 Million

Sacramento District US Army Corps of Engineers