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6633 Pacific Avenue <br /> July 1997 <br /> Page 2 <br /> Current Status <br /> In correspondence dated August 27, 1997, PHS/EHD stated that if petroleum hydrocarbon and <br /> MTBE concentrations continue to decrease, despite problems inherent with submerged well <br /> screens, that a closure report should be submitted. <br /> The results of the February 24, 1997 groundwater sampling event evidenced significantly higher <br /> concentrations of benzene in the sample collected from MW7, an increase from <0.5 ppb on <br /> August 12, 1996 to 39 ppb on February 24, 1997. Additionally, the groundwater level has <br /> continued to rise. The groundwater monitoring wells are screened generally between 45 and <br /> 70 feet bgs and the most recently reported groundwater level was approximately 38.5 feet bgs. <br /> PHS/EHD has evaluated the monitoring capabilities of the existing monitoring wells and has <br /> found that it is necessary to install an additional well(s) to characterize the definition of the <br /> groundwater contamination plume. Please submit by August 15, 1997, a work plan to install <br /> additional well(s) to characterize the groundwater contamination plume. <br /> Your correspondences which accompanied the Fourth Quarter Groundwater Monitoring Report <br /> dated December 16, 1996 with the November 1996 sampling results and which accompanied <br /> the First Quarter Groundwater Monitoring Report dated March 31, 1997 with the February 1997 <br /> sampling results, requested the following: <br /> Gauge and sample wells MW2, MW6, and MW7 semi-annually; <br /> Discontinue gauging and sampling all other wells; <br /> Analyze all samples for BTEX and MTBE only; and <br /> Submit reports semi-annually without potentiometric surface maps. <br /> PHS/EHD works with responsible parties to comply with the Health and Safety Code and <br /> Underground Storage Tank Regulations in the most technologically and cost effective manner <br /> possible. However, PHS/EHD cannot grant your request given the monitoring capabilities at <br /> the site, the dramatic changes in groundwater elevations, and the significant changes in <br /> concentration levels. Please reinitiate quarterly sampling immediately. <br /> If you have any questions, do not hesitate to contact me at (209) 468-0337. <br /> Donna Heran, REHS, Director <br /> Environmental Health Division <br /> Mary Meays, Sen r REHS Margar6f Lagorio, REHS <br /> Site Mitigation Unit Supervisor <br /> cc: Elizabeth Thayer, CVRWQCB <br /> cc: David Irey, San Joaquin County District Attorney's Office <br /> cc: Wilbur Smith, Sims-Grupe Management, 615 Lincoln Center, Stockton CA 95207 <br /> cc: Stephen Carter, Gettler-Ryan Inc., 6747 Sierra Court, Ste. J, Dublin CA 94568 <br /> cc: Donald Bradshaw, Levine-Fricke-Recon, 1900 Powell St., 12`h Floor, Emeryville CA <br /> 94608-1827 <br />