The photovoltaic solar array system at Ohlone College spans 7 acres and was designed to offset the campus’s annual operational energy costs. The system includes approximately 5,000 photovoltaic modules. ENGEO’s involvement centered on geotechnical engineering and foundation design, supporting the system’s long-term stability and performance. The solar arrays are supported on drilled–pier foundations.
ENGEO prepared a geotechnical report that included field exploration, laboratory testing, analysis, and geotechnical recommendations for foundation design. ENGEO was also involved in the site’s complex grading plan, which required redistributing soil from elevated areas to lower zones to create a stable foundation pad. ENGEO coordinated with utility locators to avoid underground conflicts and established protocols for handling hazardous materials encountered during excavation. These efforts supported the safe installation of the solar array on drilled–pier foundations
The solar panel installation at Ohlone College faced several geotechnical and environmental challenges. A major issue was the presence of approximately 50,000 to 60,000 cubic yards of undocumented fill in the northeastern portion of the site, raising concerns about contamination and structural integrity. ENGEO addressed this by conducting subsurface investigations, including test pit excavation and soil sampling, followed by environmental lab testing for pesticides, hydrocarbons, and metals. Another challenge was ensuring environmental compliance for commercial land use, which ENGEO resolved through detailed reporting and screening against California Human Health Screening Levels. These solutions helped mitigate risks and provided for the long-term stability of the solar infrastructure.
