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M <br /> f <br /> v <br /> approximately in the center of the former UST and extended to the <br /> saturated zone, approximately 35 feet. Soil samples were collected <br /> at each five feet commencing at 11 feet. A grab water sample was <br /> collected. Figure 2 presents the location of the former UST area <br /> and B-T. <br /> The soil and groundwater samples were analyzed for Total Petroleum <br /> Hydrocarbons as Gasoline (TPHG) and Benzene, Toluene, Ethylbenzene <br /> and Xylene (BTEX) using Modified EPA Methods 8015/8020. <br /> Based on the results of the analysis from the initial boring, San <br /> Joaquin County Environmental Health Division (SJCEHD) required an <br /> additional subsurface investigation to better define the extent of <br /> the soil and possible groundwater contamination. JPCA to address <br /> the county requirement prepared a workplan which was accepted by <br /> SJCEHD. <br /> A permit was requested and received from SJCEHD prior to drilling <br /> the three borings and three monitoring wells. In October 1994 , the <br /> borings and wells were completed with soil and groundwater samples <br /> collected for analysis. <br /> Soil samples collected at a depth of 20 feet to groundwater at a <br /> depth of approximately 30 feet were analyzed and contained gasoline <br /> and gasoline constituents. Groundwater samples contained <br /> actionable levels of gasoline and gasoline constituents. <br /> FIELD WORK <br /> GRADIENT DETERMINATION <br /> Prior to purging and sampling the depth to groundwater was measured <br /> by an electronic probe in the three Monitoring Wells on site. The <br /> water depth was measured from a mark located on the top of the <br /> casings. The groundwater gradient data are presented in Table 1. <br /> The calculated gradient is S74oE or 1640 at 0. 009 ft/ft. This <br /> gradient may be influenced by ponded water approximately one foot <br /> in depth located approximately 50 feet west of the wells. This <br /> excavation is for a new concrete apron. The groundwater gradient <br /> is depicted in Figure 2 . Field notes are contained in Appendix A. <br /> TABLE 1 <br /> Groundwater Elevations (ft) - December 11, 1995 <br /> Well ID Top of Casing Depth to Water Groundwater Elevation <br /> MW-1 40. 00* 28. 69 11. 31 <br /> MW-2 40. 03 28. 54 11. 49 <br /> MW-3 39 .43 27.77 11. 66 <br /> * Assumed elevation <br /> • 3 <br />