California Valley Solar Ranch


SunPower Corporation


Geotechnical Engineering Geology & Geomorphology Geologic Hazard Evaluation Fault Exploration Groundwater Resource Evaluation Development of Mining Plan


San Luis Obispo County, California

Project Overview

The California Valley Solar Ranch is a 250 megawatt (MW) solar power collection facility on a 5,000-acre site located in the northern portion of the Carrizo Plain of California. The solar ranch consists of ground-mounted tracking solar arrays covering approximately 1,800-acres of the site, and equipment pads, maintenance and other facilities at various locations across the site. The project is south of an existing 230 kiloVolt (kV) transmission line operated by Pacific Gas & Electric (PG&E) which will provide connection to the power grid.

Engeo's Role

ENGEO performed a geotechnical exploration, including analysis of the geologic hazards, probabilistic seismic hazard analysis, geotechnical design criteria, recommendations for site grading and foundation construction, engineering consultation and consultation regarding water supply wells and septic system design.

Additionally, ENGEO evaluated potential sources for construction aggregates and prepared a mining plan. Recommendations were provided for use of aggregates for construction of roadways.


The San Andreas Fault crosses the northeastern portion of the project site. The presence of highly corrosive soils was also part of the design challenge.

Solutions and Outcome

ENGEO developed setback for solar arrays and structures from the mapped trace of the fault, and provided alternative foundation design recommendations for corrosion protection.

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