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Mr. Fernando Amador �- 4. Page ES -2, Executive Summary 2 July 1996 As part of its remedial approach to ground water, PG&E recommends implementing the soil remedy to be presented in the final feasibility study and remedial action plan. The current soil remedy proposed consists of treating four soil source areas within Area I to minimize COPC migration to ground water. The State has not agreed to the definition of the source areas nor has it agreed to allow no further definition in non -source areas. Based on the bench study, the current soil remedy proposed will mobilize COPC to the ground water. The proposed remedial alternative will comply with State Water Resources Control Board Resolution No. 92-49 only if the wastes left in the ground will not release contaminants at concentrations that will impact the ground water, or if it is infeasible to eliminate all potential impacts, will not affect the beneficial uses of the ground water. Page 10, Environmental Risk Assessment The report states that the discharge of surface runoff has not occurred from the surface water collection system since a sump was installed. The fate of the sump contents should be- described in the report. 6. Page 12, Nearby Environmental Investigations The report states that the Fire Department has not tested Zones B and C, and MW -14 (which is located on Commerce Street and downgradient of the Fire Department and upgradient of the PG&E) has had detectable concentrations of benzene and total petroleum hydrocarbons (TPH). I concur that the Fire Department has not tested Zones B and C. However, based on current information, it is not clear if PG&E is really downgradient from the Fire Department. As suggested in Item 2 above, the Fire Department is cross gradient of PG&E in Zone A. Also, the fuel petroleum hydrocarbon contamination in MW -14 is questionable. MW -14 had detectable benzene and TPH as diesel (TPHd) in November 1994, which was the first sampling event after well installation. Subsequent sampling events have shown nondetectable levels of benzene and TPHd. It is possible that during well installation, contamination was pushed down from a contaminated zone by the drilling equipment or the drilling equipment itself was contaminated. Laboratory error also could have caused the one-time detection of benzene and TPHd. In June 1995, TPHg was detected with an estimated concentration of 0.014 µg/1 which is lower than the detection limit of 0.015 µg/1 making; this result highly questionable. Based on the monitoring data, it seems that benzene and TPH were not really present at MW -14 in Zone C. There does not seem to be sufficient evidence to support that the potential upgradient source, which is the Fire Department, is a contributing source. However, we need to resolve with PG&E the issue of potential upgradient sources and their contribution, if any, to the contamination at PG&E, because it always comes up in reports and meetings. 7. Page 16, Modifications to the Work Plan The report states that MW -22R, which is the alternative to the original MW -22 location, indicat:c d a. diesel odor in the soil. Based on this information and the knowledge that there were former service stations on the far side of Church Street, PG&E decided to install MW -22 in the original location