SITE INFORMATION AND CORRESPONDENCE

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Michael N. Oliphant -2- 1 June 2011 Chevron Former Vernalis Pump Station total potential onsite residential cancer risk of 1 E-06 is equivalent to the de minimus level of 1 E-06, which indicates an acceptable cancer risk for exposure to onsite soils. In addition, the non-cancer health hazard index determined at 3E-03 is well below the de minimus level of 1, which is also a conservative estimate of risk. The cancer risks and non-cancer health hazards, at or less than respective de minimus levels, should not result in unacceptable health risks for an adult or child onsite resident. Also, an ecological screening evaluation indicated there do not appear to be any ecological receptors at/within one mile of the Site. SAIC concluded that no remedial action is necessary to protect human or ecological health and a risk management decision for no further action could be made and that the Site is a candidate for closure. Based on the investigative findings of SAIC's HHSE and the earlier reports, Central Valley Water Board staff concur that the presence of the residual crude oil remaining at the Site does not pose an unacceptable risk to potential future onsite resident under the conditions evaluated. Consistent with other OVP/TAOC sites, Chevron needs to submit a site-specific Soil and Groundwater Management Plan (SGMP), designating Chevron as the responsible party. The SGMP, which documents onsite conditions, will serve as a guideline for Chevron to implement for the handling, reuse, and disposal of any soil and/or groundwater affected by the degraded crude oil and/or groundwater that may be encountered or excavated during future Site activities. The SGMP should be provided to San Joaquin and Stanislaus Counties Health Services staff and to owners of property that overlie areas of crude oil affected soil and/or groundwater at the Site. The Central Valley Water Board is required to provide the public a 20 to 30-day period of opportunity to comment on closure decisions under state law (including Health and Safety Code 25356.1). Chevron staff, in conjunction with Central Valley Water Board staff will notify nearby landowners, residents, and occupants of proposed closure cases. Pursuant to Section 2728 of the California Code of Regulations, Title 23, Division 3, Chapter 16, the Central Valley Water Board requests that Chevron conduct a property and offsite property owner survey (Survey). The Survey should determine: a) all properties overlying soil and groundwater determined to have been impacted by the historical pipelines' release, and b) adjacent properties within a 200-foot radius of the impacted areas delineated at the Site. Upon completion of the Survey, submit a table or spreadsheet listing property owner names and mailing addresses, business and residence mailing addresses, and assessors' parcel numbers and a corresponding map(s). By 15 November 2011, please submit the results of the Survey and the SGMP. Chevron representatives, in conjunction with Central Valley Water Board staff will submit written notification regarding the proposed site closure to parties listed on the Survey and provide owners of affected property an opportunity to submit comments.