Lost Creek Dam

This project involved design for modifications of a concrete arch dam on a tributary to the South Fork of the Feather River. The dam required spillway, bridge deck, and abutment approach modifications, and new retaining walls to accommodate the dam modifications.

Following a thorough review of Division of Safety of Dams (DSOD) records, Blackburn Consulting completed exploratory borings, seismic refraction surveys, geologic mapping, and a geotechnical design report for design of dam facing, spill protection, retaining walls and approach cuts and fills.

Our investigation included extensive rock coring at the base of the dam to evaluate the rock for erosion/plucking at the toe, and evaluation of dam embedment and rock wedge/block failure. During the investigation, Blackburn identified a significant shear zone that passed through the dam footprint which required additional geologic mapping and trenching to evaluate. Blackburn coordinated with the prime design consultant, South Feather Water and Power Agency (SFWPA), DSOD, Federal Energy Regulatory Commission, and the California Department of Fish and Wildlife to deliver a successful design.