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INTRODUCTION This update, STATUS UPDATE 46, presents data from October 17, 1996 through January 15, 1997 and includes the Quarterly Groundwater Sampling, Vapor Extraction System Monitoring and Venting of MW8 The permit to dump treated groundwater to the sewer has been renewed Presently we are batch dumping the treated water from the "ConVault" whenever it is full The water for treatment is collected from the vapor recovery condensate dropouts and produced from the sampling and monitoring of the monitor wells by Lawrence Tank Testing (LTT) pumping service . LOCATION The station is located at 6425 Pacific Avenue at the intersection of Douglas Road, Stockton, in San Joaquin County, California The site lies in Section 21, T2N, R6E, MDB&M at approximately 12 feet above mean sea level (MSL) (see Figures 1 , 2, 3) The parcel is # 31 and can be located in Assessor' s Book 97 on page 41 (97-041--31) On October 2, 1992 , a licensed surveyor with Nolte & Assoc surveyed all monitoring well locations and top of casing elevations to a known datum, ie City of Stockton Bench Mark Number 12 , elevation 11 74 ' above mean sea level GROUNDWATER MONITORING Depth to groundwater measurements and vacuum readings were obtained from all monitor wells on December 10 , 1996 Water samples were obtained from wells MW1, MW2 , MW3 , MW8 , MW10 and MW12 at that time The vapor extraction system (VES) is monitored weekly and was operating at the time of the quarterly sampling/monitoring Corrections for vacuum were necessary for the depth to water measurements, see Appendix D - Field Notes and Methods and Proceedures Figure 4 , represents the measurements obtained on December 10, 1996 Groundwater gradient shows a recharge cycle, groundwater has risen from 1 58 feet at MW8 to 4 25 feet at MW1, averaging a little over a foot and a half across the site A low pressure basin has formed at the wells being used for vapor recovery (MW3 and MW10) The overall flow direction is predominately to the east r*r)nrrTrnrrn 7'L'a o�LMDr rnrr On December 10, 1996, quarterly groundwater samples were obtained from wells MW1, MW2 , MW3 , MW8, MW10 and MW12 , see Table 1 and Appendix A. These samples were collected by a WEGE Geotechnician and "Chain of Custody" delivered on ice to a State certified testing laboratory, AMERICAN ENVIRONMENTAL NETWORK, INC DHS #1172 , for chemical analyses These samples were analyzed for TPH, BTEX and MTBE concentrations using EPA Methods 8015/5030 and 602 respectively, see Appendix A, Table 1 PAGE 1 R603 UPDATE--46 02/04/97