Under their IDIQ contract with the NRCS, DJ&A provided engineering services for assessment of flood hazards associated with eleven (11) USFS dams across California varying in height between 6 and 50 feet.
Site visits were conducted at each dam to observe and document the condition of the existing dams, the basin upstream, the downstream reaches, and potential downstream hazards. Additional activities included screening level assessments to assess inundation of potential hazards, dam breach analysis and modeling, hydrologic analysis, and dam hazard classification reports.
One of the dams included in the project task order in California, San Bernardino #4 Dam, was hit with wildfire only weeks prior to the site visit. DJ&A engineers who visited the site found that the dam was seriously damaged by the fire, with tree roots in the dam embankment burned leaving ±8’ deep holes in the dam. DJ&A engineers reported their findings to the Forest Service and an emergency breach was completed by lowering the spillway elevation.
- Background research and preliminary data collection
- Site visits including dam surveys, condition assessments and screening level assessments
- Dam breach analysis using HEC-HMS and/or HEC-RAS
- Hydraulic analysis for flood-induced breach and auxiliary spillway flow inundation using HEC-HMS
- Preparation of inundation maps with all downstream hazards
- Development of hazard classification assessments