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;I <br /> I� If%fto <br /> i <br /> Item 4: <br /> Well 4D showed contamination in March, 90 aj d March, 91. It has sampled <br /> clean since that time. As we explained above, iiwe feel that 4D is constructed <br /> properly and that it is not acting as a conduit for contamination from the upper <br /> to the lower aquifer. The only conclusion is that there is a minor amount of <br /> contamination (all below action levels) in the lower aquifer. <br /> There are several ways that it could have gotten in the deeper (Sand 2) aquifer. <br /> The Union Ice Company site is surrounded by navigable water. The Stockton <br /> Ship Channel is 750 feet north of the site and the Mormon Slough is 500 feet <br /> south of the site. Sand 2 most likely subcrops on the bottom of both these <br /> bodies of water. I would not want to drink the water in the Ship Channel; it is <br /> probably not to clean. There are also several other industrial sites up gradient <br /> of the Union Ice site. <br /> Lastly, it is possible that minor amounts of contain,ination from Sand 1 could <br /> have leaked through fractures or some other means through Clay B into Sand 2. <br /> This seems unlikely, however. <br /> i <br /> Item 5: <br /> I <br /> The northern portion of the excavation was excavated to a depth of about 15 <br /> feet and was slightly into the saturated zone. Sample S 5 was taken between the <br /> 12 foot and 15 foot contours in the northeast portion of the excavation. This <br /> sample was "Non Detect" for gasoline and BTXE!. <br /> Soils sample results for 4S and 41) follow: <br /> WELL DEPTH GASOLINE BTXE <br /> 4S 10 18 ppm All ND <br /> 15 30 ppm All ND <br /> 4D 9 17 ppmAll ND <br /> 15 61 ppm 17.9 ppb Xyl - rest ND <br /> In the boring log for these holes, the rigside geologist described soils from 15 to 16.5 <br /> feet as "gasoline saturated", the laboratory results would11indicate that they were not. <br /> We know now that the sewerline shown in Plate 7 was 104 "and that this leakage <br /> discolored soils, etc., in the excavation vicinity. Perhapi�,the;geologist,was Tooking at <br /> some leakage from the sewer. <br /> I <br /> i <br /> We did not dig the excavation on the eastern side of wells 4S and 4D, because we were <br /> afraid of loosing the wells. We did not propose any wells to the east of these two (2) <br /> i <br /> h <br />