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INTRODUCTION <br /> This update, STATUS UPDATE 43 , presents data from December 19, <br /> 1995 through March 19, 1996 and includes the Quarterly Ground <br /> Water Sampling and Air Monitoring and 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 March 6 , 1996 <br /> Ground water gradient shows the start of a recharge cycle, with <br /> ground water rising approximately two feet across the site, <br /> forming a high water ridge spreading from MW1 towards MW4 and MW3 <br /> to MW5- The overall flow direction is predominately to the east <br /> (MW12) and south (MW7) <br /> GROUND WATER SAMPLING <br /> Laboratory results received for selected ground water samnles <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 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 /> PAGE 1 R603 UPDATE-43 3/25/96 <br />