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' The site at present has had two hydraulic gradients , the <br /> principal one to the northeast and a slight secondary one to the <br /> southwest in April 1993 . In 1990 the gradient was to the <br /> northwest, but this was when the watertable was much higher and <br /> could have been perched water. Groundwater maps of the area (San <br /> Joaquin County Flood Control 1986 and 1991) indicate a regional <br /> hydraulic gradient toward the east. <br /> The wells installed recently were positioned to define the limits <br /> of the groundwater contamination. Well BM-10 and BM-11 have <br />' defined the northern and eastern limits of the groundwater plume . <br /> Well BM-9 has contamination levels higher than the wells on the <br /> site except for well BM-5 , which is located very near the old <br /> tank pit where the source of contamination is beleived to have <br /> started at this site. The hydraulic gradient is to the east <br /> northeast as it has been for the past two years. Therefore, the <br /> contamination in well BM-9 must come from another source. <br /> 10 We have recorded abnormally high h readings in well BM-7 in the <br />' past and have reported the fact in our report of August 24 , 1993 . <br /> These high readings are explained by the high readings at BM-9 . <br /> See Figure 2 . There appears to be a bulge in the groundwater <br />' plume to the north. Based upon the groundwater gradients <br /> contamination from an off site source could be migrating across <br />' the site and to the north of the site. This would explain the <br /> northerly bulge. <br />' The groundwater in well BM-6 contains some contamination. No <br />' soil contamination have been found on the north side of this site <br /> either in the vadose zone or the capillary fringe. Contamination <br /> migrating from off site could be the source of the contamination <br />' in BM-6. <br /> Drill Cutting <br />' Page 7 <br />