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iINTRODUCTION <br /> This update, STATUS UPDATE 40, presents data from June 28 , <br /> through August 15, 1995 and includes the sewer discharge update, <br /> monthly ground water mMonitoring and results of venting MW8 <br /> The permit to dump treated ground water to the sewer has been <br /> renewed Presently we are batch dumping the treated water from <br /> the "ConVault" whenever it is full The water for treatment is <br /> collected from the vapor recovery condensate dropouts and <br /> produced from the sampling and monitoring of the monitor wells <br /> by Lawrence Tank Testing (LTT) pumping service <br /> LOCATION <br /> The station is located at 6425 Pacific Avenue at the intersection <br /> of Douglas Road, Stockton, in San Joaquin County, California. <br /> The site lies in Section 21, T2N, RGE, MDB&M at approximately 12 <br /> feet above mean sea level (MSL) (see Figures 1, 2, 3) The <br /> parcel is # 31 and can be located in Assessor' s Book 97 on page <br /> 41 (97--041--31) On October 2 , 1992 , a licensed surveyor with <br /> Nolte & Assoc surveyed all monitoring well locations and top of <br /> casing elevations to a known datum, ie City of Stockton Bench <br /> Mark Number 12 , elevation 11 74 ' above mean sea level <br /> GROUND WATER MONITORING <br /> Depth to ground water measurements and water samples were <br /> obtained from all monitor wells on August 1, 1995 The vapor <br /> extraction system (VES) was shut down on June 7, 1995 due to <br /> excessive noise generating from the blower and no corrections for <br /> vacuum were necessary for the depth to water measurements <br /> Figure 4 , represents the measurements obtained on August 1, 1995 <br /> Ground water gradient shows the start of a discharge cycle, with <br /> a discharge trough forming at MW1 and a high ridge extending from <br /> MW9 towards MW10 and MW3 The overall flow direction is <br /> predominately to the east <br /> GROUND WATER SAMPLING <br /> Laboratory results received for selected ground water samples <br /> collected from MW1, MW6 and MW9, collected on April 19 , 1995 , <br /> were all below detection limits EPA method 8260 - Volatile <br /> Organics These wells are upgradienz of chis size and are <br /> situated between the Lincoln Village solvent plume and former <br /> Regal 603 gasoline hydrocarbon plume At that time vapor samples <br /> were also obtained when a limited vapor recovery (1 hour per <br /> well) was also performed on these wells, using LTT vacuum truck <br /> and the portable vacuum/orifice manifold supplied by WEGE. This <br /> limited vapor recovery used the same procedures as the bio- <br /> venting of MW8 Results of the vapor samples were all below <br /> laboratory detection limits for EPA method 8260, as was performed <br /> by Superior Precision Analytical, Inc see Update #29-Appendix <br /> A <br /> PAGE 1 R603 UPDATE-40 8/29/95 <br />