Superfund Explanation of Significant Difference for the Record of Decision (EPA211 Region 9): Treasure Island Naval Station, Hunters Point Ship Yard Site, Parcel B, 211 San Francisco, CA., October 20, 1998

摘要

This Explanation of Significant Differences (ESD) is for a change to the remedy211u001eselected in the Record of Decision for Parcel B, Hunters Point Shipyard dated 211u001eOctober 7, 1997 (PB98-964501). In the Parcel B ROD< the Navy's selected remedy 211u001efor contaminated soils located on Parcel B was excavation to the groundwater 211u001etable followed by offsite disposal. The depth to groundwater below Parcel B was 211u001ebelieved to typically occur at 10 feet below ground surface (bgs). However, in 211u001eearly 998, fieldwork on the Site indicated that the depth to groundwater beneath 211u001eParcel B could be as shallow as 2.3 feet bgs. This ESD revises the selected 211u001eremedy of the Parcel B ROD to require cleanup of contaminated soils to a cleanup 211u001elevel of 10 to the -6th power cancer risk (residential) or to a maximum depth of 211u001e10 feet bgs instead of the groundwater table to ensure that the Parcel B remedy 211u001eis protective of human health and the environment.