San Diego Gas & Electric Company’s (SDG&E) Fire Risk Mitigation (FiRM) initiative was developed to proactively address fire risk by hardening critical circuits within service areas most at risk for wildfires.
SDG&E is replacing existing high-risk circuits and wood distribution poles susceptible to fire or wind damage, and new foundation excavations will be drilled to set the replacement steel distribution poles. Subsurface conditions which can result in difficult or slow drilling during foundation excavation can have significant impact on the project construction and cost. To support SDG&E with front-end project planning and design, Geosyntec performed geologic and geotechnical evaluations to characterize ground conditions along various circuits in addition to obtaining site specific information regarding soil parameters for design of pole foundation using the Moment Foundation and Design (MFAD) software for self-supporting pole foundation design. Targeted geotechnical evaluations (exploratory borings and seismic refraction surveys) at select locations allowed for extrapolation of data across areas of similar ground conditions and providing representative engineering recommendations for design and construction. Preliminary geologic and geotechnical evaluations can help save time, money, and reduce contractor change orders associated with unforeseeable field conditions.
Challenges associated with the FiRM projects include the remote locations and the quantity of “high risk” poles within a specific circuit. The various circuits extend for miles across remote areas in eastern San Diego County and range from 100 to >1,000 existing poles. Other challenges include extrapolating data along large circuits with limited site specific geotechnical information and coordinating fieldwork with multiple client groups due to land jurisdiction, site access, and environmental restraints.
Geosyntec successfully completed geologic and geotechnical evaluations for seven different circuits on time and under budget. Geotechnical information obtained from the evaluations has been provided to bidding contractors to help them provide accurate cost estimates and reduce potential change orders during construction activities. Geosyntec has been requested to continue performing additional evaluations for new distribution circuits into the future.
- Location: San Diego County, California
- Client: San Diego Gas & Electric
- Project Practice Areas: Contaminated Sites, Environmental Management, Geotechnical
- Type of Facility: Electric Transmission Lines
- Services Provided: Geologic Mapping, Exploratory Drilling and Geophysics, Engineering Evaluations, Foundation Design Recommendations, Fire Risk Mitigation
- Type of Work: Fire Risk Mitigation
- Governing Regulation: State and local