ARCHIVED REPORTS XR0010503 - Laserfiche WebLink

Home Browse Search

CALIFORNIA GEOPHYSICAL GROUP,' N(t. O Box 578341, Modesto, CA 95357 Tel (209) 527-1247 December 18 , 1997 Fax (209) 527-4810 Mr. Steven Sasson REHS Environmental Health Division 304 E. Weber Ave. , 3rd Floor Stockton, CA 95202 Re: Darpetro EXXON, 749 E. Charter Way, Stockton, CA 95206 Site 1060 We have received your letter dated November 25, 1997. This letter covered several concerns by your office over the past year. Each concern will be addressed in the order presented in the letter. We will begin testing all the wells at this site for oxygenates, TPH gasoline, and BTEX starting in January, 1998 . We are submitting three revised Tables number 3 , 3A and 3B, which shows the data, which was originally included in the laboratory reports in the Quarterly Report of November 10 , 1997. Please replace the old tables with these revised ones. The wells where the ORC is placed is noted on Table 3A in the "OXYGEN" column. In the May 16 , 1997 Quarterly Report we listed the wells where the ORC was placed. We also stated we would be watching the oxygen levels in wells BM-5 and BM-8 . Monitoring of the oxygen levels has been performed in wells BM-5 (side gradient) and BM-8 (down gradient) . The oxygen levels in these wells have increased even though the contamination in the wells remains high. This indicates the oxygen is able to migrate through the aquifer either through dispersion or advection. The dispersion distance is beyond 40 feet from each well and the advection of over 100 feet. It is our policy to quarterly sample the least contaminated well from the last quarter results. During the July 1997 event we switched wells BM--9 and BM-7 . The reason for this was the fact that a car was parked over well BM-9 when it was to be sampled, so the technician went to the next well BM--7. After sampling BM- s the car moved and he could then sample BM--9. In the future, if a vehicle is parked over the well , we will go on to the next well and return to that well as soon as it can be sampled. We have been checking the quality of the tubing used by the purging pump to remove the water from each well . The present tubing used is teflon lined, .it has checked to contain non- detectable amount of hydrocarbons over the past three months. The pump is placed in each well without any water in .it from the last well . It then pumps about 10 to 12 gallons of well water.