The project involves approval of an Explanation of Significant Differences (ESD) to a Remedial Action Plan (RAP) for the General Electric Company (GE) Oakland site (Site). The U.S. Environmental Protection Agency (EPA) currently has an environmental oversight role at the Site with respect to polychlorinated biphenyls (PCBs). Bridge Point Oakland, LLC (Bridge) acquired the Site in 2019 and plans to redevelop it into an approximately 530,000-square foot (sf) warehouse building. The 2011 RAP, approved by DTSC and EPA, considered the current vacant land use and a future occupancy of existing buildings at the Site, but did not contemplate a new onsite warehouse building. The remedy, as modified by this ESD, will involve minor and significant changes to the remedy described in the RAP to accommodate the redevelopment. The significant difference will involve inclusion of a vapor intrusion mitigation system (VIMS) for the new warehouse building. DTSC has determined that this is a significant but not a fundamental change to the remedy as described in the 2011 RAP and requires that an ESD be prepared.
The draft final ESD describes the following minor changes that will be made to the remedy in conjunction with the redevelopment:
• Removal of the existing site-wide cap and construction of a new cap for the redevelopment, to various depths depending on the planned ground surface: (1) concrete pavement; or (2) concrete building slab. Drainage for the new cap (i.e., surface water control system) will be functionally equivalent to the existing system;
• Modification of the existing onsite components of the groundwater remedy (treatment system, extraction wells, monitoring wells, and related infrastructure) as needed to allow for the construction of the planned warehouse building. Some monitoring wells will be destroyed and new wells will be installed after construction of the new building. The modified network will continue to provide volatile organic compound (VOC) source control and containment as described in the 2011 RAP;
• Expansion of the VOC excavation to include an additional area near existing Building 1 in the vicinity of borehole 5GP5 for mass removal and to reduce potential impacts to soil gas and groundwater in the area; and
• Excavation of soil with the highest known concentrations of PCBs remaining on the Site. A total estimated volume of 2,650 cubic yards of soil will be excavated for off-site disposal at a permitted facility.
The VIMS will be a sub-slab depressurization system (SSD) with components that are integral to the new warehouse building design. The integrated components of the SSD system will be installed during building construction and will be active and tested prior to building occupancy.
The SSD system will cover the entire ground-floor footprint of the new warehouse building (approximately 530,000 sf). Testing will consist of indoor air and sub-slab soil vapor sampling. Based on testing, chemicals of concern (COCs) for indoor air and sub-slab vapor will be identified and site-specific commercial/industrial cleanup goals for COCs in soil gas beneath and indoor air within the new building will be developed under DTSC oversight consistent with DTSC’s Human Health Risk Assessment Note 3. The expected outcome from the addition of the VIMS is to continue to have a remedy in place that is protective of human health (i.e. future building occupants) and the environment.
The Department of Toxic Substances Control (DTSC) utilized information and analysis in the GE Site Redevelopment and Redevelopment Project (PLS19- 076/ER18-013) Environmental Impact Report (EIR) to support a final determination about the type of environmental document required to be prepared for the proposed GE Oakland Explanation of Significant Differences as provided by Sections 15162, 15163, and 15164 of the CEQA Guidelines. Specifically, the EIR analyzed potential impacts related to contaminated soils in Section 4.1 (Cultural Resources and Tribal Cultural Resources), Section 4.2 (Hazards and Hazardous Materials), Section 4.3 (Transportation and Circulation), Section 4.4 (Air Quality), Section 4.5 (Greenhouse Gas Emissions and Energy), Section 4.6 (Noise and Groundborne Vibration), Section 4.7 (Geology, Soils and Seismicity), and Section 4.8 (Hydrology and Water Quality).