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This velocity equates to about 6. 3 feet per quarter. At the time the hydropunch testing was done, the groundwater level in wells BM-6 , BM--7 and BM-9 was located between 44 and 46 feet below the surface. Hydropunch HP-1 collected water between 45 and 50 feet bgs. The time to fill up the sampler was about 2 hours. We tried to perform the same test .in the same interval in HP-2, however, no water was obtained in the sampler after 2 hours. We tried lowering the sampler to between 50 and 55 feet ' bgs and again were unable to obtain a water sample. We rebored HP- 2 a week later and opened the sampler between 55 and 60 feet. This time a water sample was obtained. Because of this, we assessed the possibility that the aquifer was confined in this ' area. Figure 4 shows the cross section taking into account the data from well. BM--9 and the hydropunch logs. ' It appears that the aquifer is partially confined from well BM--9 east to somewhere between BM-9 and BM-7 . The aquifer is not confined under the service station site, nor the wells to the ' east of the site. Figure 5 shows our interpretation of the plume configurations at ' the time of the hydropunch work. RATIONALE FOR TWO PLUMES 1 . The hydraulic gradient has remained to the east since January, 1990. Although, gradient bearings are not known before 1990 from site data, the San Joaquin County Flood Control data ' shows an easterly gradient for this area since 1989. From 1990 to the present groundwater would have traveled approximately 145 feet to the east. ' 2 . The groundwater contamination in well BM-9 is about twice as much as in well BM-7. See Table 3 . Contamination in well BM-4 , which is near to the source area, is always above that in well t BM-7 and sometimes is close to the contamination in well BM-9 . Therefore, when profiling the contamination between BM-9 and BM-4 the contamination is high in BM-9, lower in BM-7 and rises again in BM-4 . This contamination profile is happening while moving ' away from the source and in an up gradient direction. We believe it is not possible for a contamination plume to increase as it moves away from the source and in an up gradient direction. 1 3. No contamination in the vadose zone was found in well BM-9, except for the sample taken at the capillary fringe or confining ' aquifer soil . The vadose zone contamination is defined and no contamination has been found in the area west of the property line. ' 4. The fact that the aquifer is partially confined adds an • additional restriction to up gradient movement of the contaminants. The groundwater velocity should increase in the Page 3