This former chemical manufacturing facility, with operations dating back to the 1890s, produced agricultural and industrial chemicals for over a century. In the late 1990s, Terraphase initiated environmental investigations and remedial planning to address legacy contamination under the oversight of the San Francisco Bay Regional Water Quality Control Board (RWQCB) and the California Department of Toxic Substances Control (DTSC). These efforts have guided the site’s transition toward long-term environmental compliance and risk reduction.
Scope of Services
Terraphase investigations included collecting hundreds of soil, groundwater, soil gas, and pore water samples across the site under the oversight of both the RWQCB and the DTSC. The samples were analyzed for volatile organic compounds (VOCs), semivolatile organic compounds, metals, pesticides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and radionuclides to evaluate risks associated with technologically enhanced naturally occurring radioactive material from previously processed ore at the site. The findings demonstrated the site posed no risk to human health.
Terraphase also developed a sea-level rise vulnerability assessment (SLR-VA) using historical and current groundwater elevation data collected at the site, local tidal information, and peer-reviewed sea-level rise scenarios. Terraphase also prepared a human and ecological health risk assessment to identify remedial activities aimed at mitigating risks to future site users. Remedial alternatives were further evaluated in a feasibility study/remedial action plan (FS/RAP).
- Stabilization of pyrite cinders using dolomitic limestone
- Installation of a biologically active permeable barrier
- Design, permitting, and operation of a soil-vapor extraction (SVE) system
- Targeted soil excavations and capping
- In-situ treatment of groundwater VOCs using chemical reduction and bioremediation
- Establishment of engineering controls
Current operations include ongoing maintenance and performance monitoring of the soil-vapor extraction (SVE) system for compliance with the Bay Area Air District (BAAD) permit and implementation of the groundwater monitoring program for continued evaluation of the in-situ remedy performance. In-situ treatment for metals in groundwater will be implemented in accordance with the FS/RAP pending approval of the preliminary design document currently under DTSC review.
Notable Accomplishments
- Stabilized approximately 300,000 cubic yards of pyrite cinders
- Removed approximately 50,000 cubic yards of soil from targeted excavations
- In-situ treatment involved over 700 tons of zero valent iron injected through 950 fractures, and over 250,000 gallons of electron donor and microbial cultures through 182 wells to enhance reductive dechlorination
- Implemented a comprehensive site management plan and requirement of vapor mitigation systems for proposed buildings as engineering controls
- Incorporated a comprehensive groundwater monitoring program consisting of quarterly sampling of 130 monitoring wells and semiannual sampling of subset wells to evaluate the in-situ remedy for VOCs
