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INTRODUCTION <br /> This update, STATUS UPDATE 42 , presents data from October 19, <br /> through December 19, 1995 and includes the sewer discharge <br /> update, Quarterly Ground water sampling and Air Monitoring and <br /> venting of 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, R6E, 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 November 14 and December 12 , <br /> 1995 The vapor extraction system (VES) was operating at <br /> that time, but there was no vacuum influence to MW10 , the vapor <br /> lateral was completely full of condensate water Corrections for <br /> vacuum were necessary for the depth to water measurements, see <br /> Appendix D. <br /> Figure 4 , represents the measurements obtained on December 12 , <br /> 1995 Ground water gradient shows the start of a discharge <br /> cycle, with discharge troughs forming at MW1 and MWS The <br /> overall flow direction is 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 Anr77 is � aa� <br /> were all below detection limits EPA method 8260 ---Volatile <br /> Organics These wells are upgradient of this site 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 /> PAGE 1 R603 UPDATE-42 1/11/96 <br />