Pleasants Valley Regional Detention Facilities
City of Vacaville, California

West Yost provided a feasibility study, predesign, and final design for two regional detention facilities to reduce flooding in the City. This project included two basins located on either side of Encinosa Creek (tributary to Alamo Creek). The recommended detention basins have a combined detention storage capacity of 200 acre-feet.

West Yost prepared a feasibility study followed by a Preliminary Design Report, and final design for the regional detention basins. Several alternative configurations were evaluated and preliminary cost estimates prepared. The project work included updating the watershed mapping and hydrologic modeling (HEC-1), surveying and mapping, developing a HEC-RAS model of Encinosa Creek, and developing detailed hydraulic analysis for the basins and their effect on the hydraulics of the other basins.These basins are operated as off-line basins. A third basin, located just to the north, was designed as an on-line basin, to eliminate a localized flooding problem. The configuration of basins, also took into consideration extensive wetlands and the discovery of an American Indian burial grounds on the project site.

The project included design of the inlet and outlet structures and West Yost also evaluated the downstream storm drain system and assisted City staff in permitting with the Department of Safety of Dams.