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4'- 1� J i f7 1 ► FP, C Ge o fogicaf Technics Inc. t 2741 xiverRoarl modesw,California 95351 v (209)538-6424IFax#538-5852 February 4, 1999 Project No.: 251.3 Project Name: McGranahan (Gawne Road) Mr. L. Kris Brown State Water Resources Control Board 2014 T Street, Suite 130 P.O. Box 944212 Sacramento, CA 94244-2120 ;. RE: February 2, 1999 Letter McGranahan - Former Moresco Property, 16865 Gawne Road, Stockton, CA USTCFP Claim No.: 010323; Site Code No.: 505486 Dear Mr. Brown: Thank you for your review of the cost pre-approval request for the site at 16865 Gawne Road, Stockton. With regards to you letter of pre-approval of corrective action costs dated February 2, 1999, 1 have the following questions to be clarified before this work is performed. After you review my questions, please give me a call and we can discuss these issues. 1. Time Considerations: • Drilling a borehole with V&W is fairly quick once the drill rig is set up. It takes approximately 4 minutes to drill and sample every five feet. By 10 AM we will be at 70 feet. • Lab testing of MTBE by 8260 takes approximately 1.5 to 2 hours per sample. So by 12 PM a mobile lab should have the results from the 70-foot sample. According to your letter, at this point we could decide whether or not to continue drilling. • The problem I see is with the timing of the other samples. Your letter states that if .. down to-to -then drilling should continue with= petroleum contamination=is-found samples being tested at 5-foot intervals down to groundwater. If contamination is found every five feet down to groundwater then the well should be installed. If we wait the 1.5 to 2 hours for each sample to be tested we would be out there for up to another 16 hours before a decision could be made as to whether or not the well is going to be installed. • If we assume that drilling would not wait for the lab test results, drilling from 70 feet .down to 110 feet should be complete at approximately 12 PM. At that point the last soil sample would go into the lab and the drill rig would go on standby for two hours until the testing is complete. At 2 PM we could decide if the well would be installed or not. 2. Cost Considerations' There are two primary cost considerations: • Lab Fees - mobile lab fees are more expensive then stationary labs and'to make the determination on a five foot interval from 70 feet to 110 feet will take twice as many i