Geologic Hazards Assessment – Lake Hemet Spillway
Project Summary
Lake Hemet Municipal Water District (2018)
As a response to major damage to the service and emergency spillways at
Oroville Dam, the California Division of Safety of Dams (DSOD) conducted
detailed evaluations of dams throughout the state. At Lake Hemet Dam,
DSOD noted potential geologic, structural and performance issues that
could jeopardize its ability to survive a flood event. As such, they
requested a comprehensive condition assessment of the spillway, with a
focus on potential geologic hazards, including the susceptibility of
foundation materials to erosion and instability.
Our Role
IFE was retained as a subconsultant to Cozad & Fox, Inc. to characterize and evaluate the foundation material below and adjacent to
the spillway. Our services included:
- Review of design and as-built documentation for Lake Hemet Dam in files at the DSOD offices in Sacramento
- Review of stereo-paired aerial photographs and geologic data for the dam, spillway and surrounding area
- Earthquake fault lineament analysis, aerial photograph review and an ortho-rectified 2005 color aerial photograph
- Geologic reconnaissance and mapping of exposed bedrock and surficial soil at abutments and adjacent to spillway
- Preparation of draft report for submittal to DSOD for review
- Site meeting with DSOD reviewers to discuss and resolve draft comments
- Preparation of final report