SITE INFORMATION AND CORRESPONDENCE

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Mr. Kyle le Christie 22 February 1989 . . ARCO Products Company • 200 Alameda de las Pul gas P.O. Box 5811 . San Mateo, CA 94403 3 WORK PLAN FOR PROBLEM ASSESSMENT INVESTIGATION FOR ARCO STATION NO. 2093 AT 3425 TRACY BOULEVARD,, TRACY, SAN JAOQUIN COUNTY Thank you for submitting your 10 October 1988 work plan for this site for our review. This letter is a response to both the 10 October 1988 work plan and the incomplete 27 September 1987 PAR. -*WORK PLAN (10 October 1988) he work proposed in this work plan will not define the full extent of petroleum hydrocarbon contamination related to this site. !A site assessment, and corresponding PAR, cannot be considered complete untilithe "effective zero line" has been established. I discussed this by telephonewith your consultant, Mr. Lawrence Phillips of Brown and Caldwell (BC) on 21 February 1989. Mr. Phillips stated that BC, in agreement with ARCO; plans a phased approach site investigation which consists of the on-site phase followed by the off-site phase. The current work plan is for the on-site phase of the investigation to supply soil and ground water data to assist in selecting the locations of the monitoring wells for the off-site phase of the investigation.. 7 Although we -believe this investigation has been protracted ° inordinately, we 2 agree to accept this phase approached investigation with the understanding �j that the results of the on-site phase, along with a work plan for the off-site phase are to be submitted to us- and the San Joaquin Local Health District (SJLHD) by 15 April 1989. We request that .water samples be collected. from all; the monitoring wells, and in' addition to BTX&E and TPH analyses, 1 ,2-dichloro ethane analyses be performed. In the off-site investigation the full extent of ground water contaminated by petroleum hydrocarbons is to be defined and integrated with the on-site work. The documentation is to be- submitted as a revised PAR to us and the SJLHD by 2 June 1989. The revised PAR is to expand -on the information presented in the 28 September 1987 PAR and include all other necessary information as specified in my summary below and Appendix A of the Tri-Regional Guidelines, pages A-9 through A-11 (Enclosed) . PROBLEM ASSESSMENT REPORT- (28 September 1987) The 28 September 1987 PAR cannot be considered complete because the extent of the hydrocarbon plume was not defined. In 'addition, we have the following comments about the submitted .PAR that are to be addressed in your revised PAR: 1 . All ground water wells within 2000 feet of this site ''are to be identified and shown on a well survey map. One municipal well was identified in the 28 September 1987 PAR, but no mention was made about private domestic or irrigation wells. If no private domestic or irrigation wells are located within 2000 feet of the site, so state;