SITE INFORMATION AND CORRESPONDENCE

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Michael Oliphant 26 September 2012 Chevron TAOC TRY 6111 Street Offsite-West, Tracy • Since a cancer slope factor has not been established/published for benzo(g, h, I)perylene, and it has not been identified as a carcinogen, it is not appropriate to calculate a potential cancer risk. • AMEC reviewed the 2012 California Natural Diversity Database maintained by the California Department of Fish and Game for the Tracy quadrangle and found that four endangered, threatened, or sensitive species were identified within a one-mile radius of the Site. According to the evaluation, lack of suitable habitat for the species noted in the vicinity, there is no potential for the special species to occur within the residential project area. According to the Report, the non-cancer health hazard value of 1.6E-05 for the COPC reported in the 0 to 10 feet bgs interval - benzo(g, h, i) perylene, is well below the acceptable value of 1. Thus, the Report concluded that the site-related chemicals are not likely to result in non-cancer health hazards under the conditions evaluated. Since this COPC is not considered a carcinogen, the cancer risks were not evaluated. The Site does not provide suitable habitat for the species noted within one-mile of the Site and no potential impacts were identified/evaluated. Based on my review, l have the following comments: • Consistent with other TAOCIOVP sites, a Soil and Groundwater Management Plan (SGMP) needs to be submitted. The SGMP designates Chevron as the responsible party and serves as a guideline for Chevron to implement for handling soil affected by the degraded crude oil that may be encountered during future Site activities. • Central Valley Water Board staff concurs with the findings of the Screening Evaluation and related supporting documentation, and that the Site is a candidate for closure. A request for a No Further Action Required (NFAR) determination may be prepared. • Documentation to support a NFAR closure determination should be completed in accordance with California Regional Water Quality Control Board, Central Valley Region's 16 April 2004 update to Appendix A of the Tri-Regional Board Staff Recommendations for Preliminary Investigation and Evaluation of Underground Tank Sites- No Further Action Requests, Section 6.5 - NFAR for Cases Exceeding Water Quality Objectives should be followed for documenting Site conditions.