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1--. I <br /> ' PUBLIC 14EALTH SERVICES <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <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 <br /> 209/468-3420 <br /> BRETT HUNTER <br /> ENVIRONMENTAL ENGINEER ^, <br /> CHEVRON USA <br /> P 0 BOX 5004 NOV 18 1996 <br /> SAN RAMON CA 94583-0804 <br /> RE: Lincoln Village Chevron Station #9-4275 SITE CODE: 1952 <br /> 2905 West Benjamin Holt <br /> Stockton CA 95207 <br /> San Joaquin County Public Health Service, Environmental Health Division (PHS/EHD) conducted a <br /> series of site visits on November 18, 1996 related to the installation of an underground storage <br /> tank remediation system and to the removal of underground storage tank piping. <br /> The underground storage tank remediation system was designed to remediate soil and groundwater <br /> contamination which was related to the underground storage tanks which were removed in 1989. <br /> The system installed will consist of soil vapor extraction wells, air sparge wells, and associated <br /> piping to the treatment area. The vapor extraction wells are screened from 17 to 10 feet below <br /> ground surface (bgs). The design of the system was based on historic information. <br /> The November 10, 1996 soil samples were collected at approximately 3 feet bgs and evidenced soil <br /> contamination based on visual and olfactory observations. PHS/EHD requests that the pea gravel <br /> be removed from trenches so that areas of soil contamination can be further investigated. In order <br /> to determine the lateral and vertical extent of the soil contamination, further soil investigation is <br /> required. Since Chevron plans on replacing the piping, in some areas within the same trench, the <br /> investigation of the former piping area is required prior to the installation of additional piping. <br /> Chevron related in correspondence dated October 28, 1996, a schedule for the installation and <br /> operation of a remediation system to achieve water quality goals as put forth by Geraghty and Miller <br /> within the Workplan dated August 31, 1995 and amended by regulatory comments of PHS/EHD <br /> dated November 30, 1995. The work plan submitted by Geraghty and Miller has undergone <br /> numerous revisions to accommodate information available regarding the former underground storage <br /> tanks. As the remediation system's installation should be completed by November 29, 1996, <br /> Chevron will be required to investigate the soil contamination evidenced beneath the product piping <br /> and any modifications to the remediation system, proposed and implemented to remain in <br /> compliance with Chevron's committed schedule. If you have any questions, please contact me at <br /> (209) 468-0337. <br /> Donna Heran, REHS, Director <br /> Environmental Health Division <br /> Mary Meays, Senior REHS Margare�-Lagorio, REHS <br /> Site Mitigation Unit Supervisor <br /> MM/2905BENHO <br /> c: Elizabeth Thayer, CVRWQCB <br /> c: David Irey, San Joaquin County Deputy District Attorney <br /> c: Kent O'Brien, Geraghty and Miller. <br /> A Division of San Joaquin County Health Care Services <br />