SITE INFORMATION AND CORRESPONDENCE

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2905 Benjamin Holt Page 2 Corrective Action/Feasibility Testing The work plan submitted recently as a corrective action plan is unacceptable because it failed to comply with the California Code of Regulations,Title 23, Division 3, Chapter 16, Section 2425(d). As indicated previously, PHS/EHD has requested that feasibility tests be performed so that the most efficient remediation system design may be implemented. The work plan failed to include a correct site map. Figure 1 indicated that the site was located on the south side of Benjamin Holt when in fad it is located on the north side of the street. Figure 2 failed to locate monitoring well MW9, indicated that BHO-1 was a boring when in fad it is a monitoring well, and highlighted PR-2 instead of PR-1 which is in the vicinity of the Chevron station. Figure 3 failed to locate MW8 or MW9 and indicated that there were six multiple completion wells. Figure 4 indicated two well completion designs, both with soil vapor extraction wells and air sparge wells. PHS/EHD will approve the installation of the proposed wells as test wells to evaluate the effectiveness of air sparge and vapor extraction. Also, please note that PHS/EHD has observed significant problems with duel system design within the same boring. Excessive channelling results, which can short circuit and decrease the effectiveness of the wells. PHS/EHD recommends that air sparge wells not be placed in the same boring as vapor extraction wells to avoid this short circuiting problem. Please evaluate the design of these test wells. Any modifications should be submitted with the drilling permit application in addendum. The work plan also stated that approval of the work plan would include PHS/EHD acceptance of the specified remediation goals and conceptual Management Plan. PHS/EHD does not agree with the specific remediation goals as presented which includes soil to 100 ppm TPH-gas and groundwater to 10 ppb benzene followed by implementation of a groundwater management plan. Current state policy dictates that all pollution in water, considered beneficial to the state for use as drinking, industrial or agricultural, must be cleaned up to background levels (levels that existed prior to the discharge). As petroleum hydrocarbons are not naturally occurring in this area, this usually means to nondetectable levels. However, in some cases, existing technology, is the limiting factor in reaching this goal. There also exists in current state policy the provision that when the initial cleanup goal of background is not achievable using best available technology, or is economically unrealistic, the discharger may propose to mitigate the pollution to levels that protect the beneficial uses of the water, which for this area not only include primary and secondary drinking standards but also agricultural standards as well. Therefore, based on the above, before proposing less stringent cleanup goals for this site, it must be demonstrated with physical data from the site, that the best available technology has been implemented and any further remediation would not be technologically or economically effective for the benefit observed. Please propose clean-up goals in the final corrective action plan that are in accordance with the Central Valley Regional Water Quality Control Board Basin Plan. Compliance Schedule As PHS/EHD has indicated previously, various extensions have been granted over the last several years. You should be aware that unjustified extensions will no longer be granted. Based on industry standards, PHS/EHD has developed the following compliance schedule for this site. You should note that should this schedule not be met, enforcement actions will be initiated.