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R603 UPDATE-30 6/29/94 1. 0 INTRODUCTION This update, STATUS UPDATE 30, presents data from May 24, through June 22 , 1994, collected at the site on June 13 and 22, 1994 , see Appendix A - Field Notes The system has operated 100. since the system repairs were completed February 1, 1994 The permit to dump treated ground water to the sewer has been renewed Presently we are batch dumping the treated water from the "ConVault " whenever it is full This water is collected from the vapor recovery condensate dropouts and the water produced from the sampling and monitoring of the monitor wells by Lawrence Tank Testing (LTT) pumping service We are continually evaluating the need for a ground water pump and treat system 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, le City of Stockton Bench . Mark Number 12 , elevation 11 74 ' above mean sea level 2 . 0 GROUND WATER LOCAL GROUND WATER FLOW Ground water flow direction in this region is to the west and towards south Stockton from the foothills of the Sierra Nevada Mountain Ranges, and towards the east from the Sacramento-San Joaquin Delta At present, encroachment of saline waters from the Delta is impairing the quality of the ground water in the Stockton area Vapor extraction has created a ground water potentiometric low (an apparent mounding) beneath the site near MW2 , MW3 and MW10 Measurements obtained on June 22 , 1994 , represents ground water gradient under the influence of vapor extraction and shows a capturing cone centered near MW10 and MW2 Vapor extraction is being concentrated on MW2 , MW3 and MW10 , see Figure 4 GROUND WATER QUARTERLY SAMPLING Ground water samples were collected on June 22 , 1994 see Table 1 These samples were collected by a WEGE Geo-technician and "Chain of Custody" delivered on ice to a State certified testing laboratory (AMERICAN ENVIRONMENTAL NETWORK, INC DHS $#1.172) for chemical analyses The March 2 , 1994 samples were analyzed for . Halogenated Volatile Organics using EPA Method 8010 The compounds of interest are associated with the Lincoln Village ground water plume (Dichloroethane (DCE) -- Specific Gravity of 1 18 and solubility of 0 6., Trichloroethylene (TCE) - Specific PAGE 1