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Project 113-13 <br /> July 28, 1994 <br /> Page 2 <br /> In a November 12, 1990 report, Dames and Moore documented that groundwater <br /> samples were collected on October 24, 1990 All samples were ND Depth to <br /> groundwater was 25.3 feet BGS <br /> A fourth monitoring well (MW-4) was installed by Parker Environmental Services <br /> at the site on September 6, 1991 Soil samples analyzed from the boring were all ND <br /> for TPH-g and BTEX Groundwater samples obtained on September 11, 1991 from all <br /> four monitoring wells were also ND for TPH-g and BTEX Depth to groundwater <br /> was 28 to 29 feet BGS <br /> Quarterly monitoring was performed by Parker Environmental Services during 1993 <br /> In March, 1993, during the first quarter of monitoring, xylene was measured at 12, <br /> 1.1, and 0 96 ppb in three of the wells (MW-1, MW-2, and MW-3) Toluene was <br /> present (1.2 ppb) in MW4 All wells were ND for both TPH-g and BTEX in July, <br /> September, December, 1993, and April, 1994 <br /> A pump discharge test was done by Parker Environmental Services at the site <br /> October 15-16, 1991 The drawdown between wells indicated that all four monitoring <br /> wells are probably in the same aquifer. <br /> II. Current Activities <br /> Groundwater samples were obtained on <br /> P July 8, 1994 Pryor to sampling, groundwater <br /> elevation measurements were obtained with an electronic water level meter <br /> Results are presented in the table below <br /> Table 1 <br /> Cheapen #76, 890 North Main Street, Manteca, California <br /> Groundwater Measurement Results* <br /> Measured on July 8, 1994 <br /> MW-1 MW-2 MW-3 MW-4 <br /> Well Elevation 3312 3322 3355 3366 <br /> Depth to GW 2415 2400 2441 2471 <br /> GW Elevation 897 922 914 895 <br /> * elevation above mean sea level, in feet <br /> Shallow groundwater measurements indicate the water table is approximately 14 <br /> feet lower than measurements taken in April, 1994 As shown on the attached <br /> groundwater flow direction drawing, the flow direction is toward the southwest, <br /> with a gradient of about 0 005 ft /ft (Figure 2 - Groundwater Flow Direction) <br /> Each monitoring well was purged using a submersible electric pump prior to <br /> sampling At least 10 gallons were removed from each well, which equaled at least <br /> Parker Environmental Services 190 East 7th Street Pittsburg CA 94565-6116 <br /> Phone (510) 439-1024 Fax (510) 439-2566 <br />