SITE INFORMATION AND CORRESPONDENCE 1995-2004

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James L. Tjosvold, P.E. June 6, 1996 Page 2 groundwater operable unit feasibility studies into one FS in order to evaluate the effectiveness of soil and groundwater remedial alternatives together (DTSC had previously suggested that the soil and groundwater be divided into separate operable units and that a feasibility study be developed for each operable unit). As requested at the May 22, 1996 meeting, PG&E is planning to submit a combined soil and groundwater feasibility study that will include a range of groundwater goals. To minimize further iterations of this process, PG&E requests agreement on the remedial action objectives, the soil goal, the range of groundwater goals, and the FS approach for evaluating alternatives as outlined below. Proposed Remedial Action Objectives and Goals The proposed remedial action objective for the PG&E Stockton former MGP site Feasibility Study is: • Protect public health and the environment from the COPCs present in on-site soil and ground water and minimize the potential migration of COPCs to groundwater. To meet the remedial action objective, the following range of remedial action goals and points of compliance are proposed to be addressed during soil and groundwater remedial alternatives evaluation: 1. Goals for soil: • Minimize exposure of humans and the environment to the COPC compounds. • Reduce the potential migration of COPCs to groundwater to achieve a range of groundwater goals. 2. Range of goals for groundwater: • Background concentrations (non-detect). • The RWQCB's "Beneficial Use Protective Numerical Limits in Groundwater". • Maximum Contaminant Levels (MCLs), or if no MCL, a 10-5 cancer risk based for carcinogens and a hazard index of less than one for noncarcinogens.