LakeHennesseyBathymetryMap_(1).pdf

This is a bathymetry map of Lake Hennesey located in Napa County, California, created to support the City of Napa's Request for Qualifications for the Conn Dam Stability Assessment, Spillway Improvements, and Feasibility Alternatives Study. The map displays contour lines representing the underwater topography and elevation variations of the lake, with elevation data ranging from a high of 317.7 feet to a low of 226.2 feet. The survey was conducted on September 25, 2017, and the map uses one-foot intermediate contours and five-foot index contours to illustrate the bathymetric features. The map serves as a baseline technical resource for qualified multidisciplinary engineering consulting firms that will be selected through a qualifications-based selection process to conduct comprehensive dam engineering services.

The City of Napa is seeking consulting firms to provide professional engineering, geotechnical, environmental, hydraulic, structural, dam safety, and economic evaluation services across three project phases. Phase one requires the development of a geotechnical data report for submission to the California Division of Safety of Dams (DSOD) by December 31, 2028; phase two will assess dam stability including deformation estimates under static and seismic conditions; and phase three will produce a feasibility alternatives analysis addressing identified deficiencies including known spillway issues. The procurement will comply with federal procurement requirements under 2 CFR Part 200 and the Brooks Act, with anticipated federal funding support for design and construction through the U.S. Army Corps of Engineers, which has included Conn Creek Dam, California in the 2022 Water Resources Development Act.