RSA+ provided a full scope of services including conceptual planning, tentative map, improvement plans and phased final map for the 90 acre, 72 home subdivision in western Napa. The site was located on a hillside and was encompassed by creeks on 3 sides, which lent itself to City Hillside regulations and strict Fish and Game requirements. Project highlights include 3 bridges crossings, storm water detention facilities consisting of oversized underground detention pipes interconnected to detention basins and extensive hillside grading calculations to minimize impacts to the hillside and offhaul down the older roads of Napa. The project was also required to include offsite mitigations of 1200 feet of waterline upsizing and the addition of 700 feet of public curb, gutter and sidewalk.
Hussey Ranch was previously an open hillside and the introduction of impervious area in the way of streets and homes created the challenge of tactfully treating and detaining the stormwater runoff without compromising the site aesthetics. Through the use of interconnected underground storm drain pipes and above ground detention basins linked to metering devices we were able to keep the post project flows below pre project levels. All water on the site is treated for pollutants via bioswales and mechanical separators, which required extensive coordination with Regional Water Quality Control Board.
Located within a hillside, the topography of Hussey Ranch lent itself to the restrictions of Hillside Development in the City of Napa. One third of the homes had to be positioned with a 24-foot vertical envelope from existing grade to be contained within viewshed requirements. This scenario created a challenging grading scheme and RSA worked smartly to minimize offhaul of dirt down many of the older roads in Napa by running several earthwork calculations to determine the optimal design.
Three creeks encompassed the exterior boundary of the Hussey Ranch subdivision requiring three bridges for ingress and egress. These creeks and bridges required extensive coordination with the Department of Fish and Game, City of Napa and Napa Sanitation to approve the allowable riparian zone, bridges, utilities crossing the bridges and storm water outfall structures. Through RSA’s close relationships with the City agencies we were able to tread our way through this process virtually unscathed.
Architect | Hunt Hale Jones Architects