SITE INFORMATION AND CORRESPONDENCE 1995-2004

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Mr. Fernando Amador -5- 14 December 1995 13. Page 4-12, Section 4.2.1.5, Borings Outside of Source Areas a. Northern Third The bulk of the contamination in other areas was found at approximately 25 feet bgs. However, the deepest sample from the former gas holder was taken only at about 13 feet bgs. On the other hand, MW-17 was sampled only at 100 feet bgs. The FS did not explain why B-5, MW-2, and SB-4 were not tested for TPHd/g. A sample should be taken in the storage building and at each of the former purifiers. If PG&E proposes not to sample these former facilities, the FS should provide the justification for not sampling. b. Middle Third The lateral contamination extent of SB-1-95, B-16, SB-1B, SB-21-95, B-14, and B-26 should be defined. Vertical definition is necessary at B-16, SB-IA, and B-14. A sample should be taken in the former lampblack separator and oil tank. The data for B-1 and MW-5 are not included in Table 4-6. The FS did not explain why SB-IA, SB-1B, unnamed boring location (28-33 feet bgs), MW-4, and B-2 were not tested for TPHd/g. c. Southern Third The FS should explain the rationale for the inconsistent sampling depths. For example, SB-5- 95 was sampled only at about five and 25 feet bgs, SB-6-95 was sampled only at four and 23 feet bgs, etc. Lateral definition is needed at B-7. The FS should explain why B-13, B-7, B-8, B-12, and B-10 were not tested for TPHd/g. The lateral and vertical extent of the contamination at B-7 should be defined. 14. Page 5-1, Section 5.1, Remedial Action Objectives The FS states that one of the objectives of the remedial action is to reduce the potential for migration of the constituents of potential concern (COPC) to ground water beneath the PG&E property. For clarification, the objective should state that the purpose of the remedial action is to reduce contaminant concentrations to levels which will not result in exceedance of water quality goals in ground water. 15. Page 5-1, Section 5.2.1, Federal and State Regulations and Guidelines for Soil The State Water Resources Control Board Resolution No. 92-49 should be included in this section. A copy of Resolution No. 92-49 (Attachment 2) is enclosed for your reference. 16. Page 5-2, Section 5.2.2, Remedial Action Goals for Soils The FS states that specific federal or state standards are not available for COPC in soil for the protection of human health and the environment. The beneficial-use protective numerical limits in ground water to protect municipal and domestic supply are presented in Attachment 3. PG&E should perform a water quality assessment using Dr. Jon Marshack's Designated Level