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PUBLIC HEALTH SERVICES O.P�u!N•C <br /> SAN JOAQUIN COUNTY 2: <br /> ENVIRONMENTAL HEALTH DIVISION y <br /> Ernest M. Fujimoto, M. D., M.P.H., Acting Health Officer <br /> 304 E. Weber Ave., Third Floor • P. O. Box 388 • Stockton, CA 95201-0388 c"�1FOR� P <br /> 209/468-3420 <br /> BRETT HUNTER NOV 2 S 1Q96 <br /> CHEVRON USA <br /> PO BOX 5004 <br /> SAN RAMON, CA 94583-0804 <br /> Re: 45 East Harding Way <br /> Stockton CA 95204 <br /> San Joaquin County, Public Health Services, Environmental Health Division (PHS/EHD) has <br /> completed review of the "Revised Request for Site Closure" dated November 12, 1996 that was <br /> prepared by Pacific Environmental Group, Inc. PHS/EHD has the following comments for your <br /> consideration. <br /> The revised report was prepared at PHS/EHD request following review and notation of the <br /> deficiencies in the initial request for closure. The revised report indicated that it was prepared <br /> in accordance with the Tri-Regional Board Staff Recommendations: Appendix B - Request for <br /> Site Closure prepared by the Central Valley Regional Water Quality Control Board Staff and dated <br /> March 1, 1994. While this revision is a definite improvement over the initial report, there exists <br /> a number of significant deficiencies which affects the ability of staff to review your request for site <br /> closure. PHS/EHD has attached the draft site chronology which is being prepared as part of the <br /> closure review process, for your information. <br /> PHS/EHD has discussed with you on a number of occasions and included discussion in <br /> correspondence, the evaluation of the groundwater level in relation to the construction of <br /> monitoring wells and the ability to obtain representative samples. Groundwater levels have <br /> ranged from 35.36 feet below ground surface (bgs) in February 1989 to 58.01 feet bgs in October <br /> 1992, with the current water level at 37.74 (October 1996). It was indeed fortunate that the wells <br /> which were installed in 1989 had screened intervals between approximately 20 - 44 feet bgs, so <br /> that representative groundwater samples could be obtained. The wells which were installed when <br /> water was significantly deeper than the current levels, were screened from approximately 30 feet <br /> to 75 feet bgs. Wells with greater than 20 feet of screen through the groundwater have problems <br /> with dilution as do wells with screened intervals below first water. For example, MW11 which is <br /> screened between 43 and 73 feet bgs currently has a groundwater level of 37.74 feet bgs; <br /> therefore this well not only has 30 feet of screened interval but its screened interval is <br /> approximately 6 feet below the current groundwater level, representing significant dilution <br /> problems. <br /> PHS/EHD requested an evaluation of these problems and Pacific Environmental responded with <br /> the statement that "Groundwater sampling results are deemed representative of site conditions <br /> with the exception of Wells MW-9 and MW-13." These wells were so polluted that they continued <br /> to evidence total petroleum hydrocarbon contamination and Methyl Tertiary Butyl Ether (MTBE) <br /> contamination after the screened intervals were submerged. <br /> A Division of San Joaquin County Health Care Services <br />