SITE INFORMATION AND CORRESPONDENCE_FILE 1

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Public Health Service-Environmental Health Division San Joaquin County April 14, 1995 Page 2 In our conversation, I presented AFPC's proposal to provide further analytical support for our position concerning the absence of a threat to groundwater beneath the site. You have agreed to afford AFPC the opportunity to conduct additional testing as follows: • Installation of a groundwater monitoring well within 10 feet of the former waste oil i tank; I • Installation of two additional soil borings in locations where previous analyses reported TPH concentrations in excess of 5,000 ppm TPH; • samples Analysis of five soil les for WET extractable TPH constituents (diesel and semi- volatile compounds) to evaluate the concentration and mobility of TPH remaining in soils; • Evaluation of these data using geochemical modeling. We believe that the groundwater level measurements will be of particular value as a means of evaluating the impact of recent rainfall on the depth to groundwater beneath the site. We are prepared to commence the above-described work immediately and to present a report on our results by July 1, 1995. This report will include soil and groundwater analyses, modeling, and other studies required to evaluate the potential impact of TPH in soils on groundwater. An approximate time schedule for completing the additional work is attached. Based on the totality of the data generated through this next phase, we will mutually be in a better position to evaluate the risk presented by the site,-if any,--and-the options=for-fil-taiizirig ciosurer"� As we discussed, you have approved use of the November 1994 technical work plan for additional soil sampling and monitoring well installation that was previously, submitted to your offices. AFPC will apply for monitoring well and soil boring permits and attach a map showing the proposed locations for the soil borings after the initial groundwater level data is evaluated. SAC 146.12