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AGS recommends that the collection and analysis of water samples from the two <br /> ' domestic water supply wells be suspended. The December 1998 sampling event marked <br /> the second round of samples collected at these two wells following the remedial soil <br /> ' excavation. Analytical data indicate no adverse impact to these wells, either prior to or <br /> following the remedial excavation activities. <br /> AGS further recommends that monitoring wells MW-5, MW-7 and MW-9 be removed <br /> from the quarterly ground water monitoring program. Historical analytical data indicate <br /> that these wells have shown non detectable levels of gasoline and BTEX throughout their <br /> ' sampled history with the exception of the first sampling event at MW-9. This includes 17 <br /> sampling events at MW-5, and 12 events each at MW-7 and MW-9. <br /> Monitoring well MW-5 is located across the gradient and MW-7 is located upgradient <br /> from the former UST location. Wells MW-5 and MW-7 should be retained as ground <br /> water level measuring points for the purpose of determining the ground water gradient <br /> ' during future sampling events. <br /> Monitoring well MW-9 was installed down gradient from the former UST location, but <br /> ' was screened through the second aquifer to determine the vertical extent of impact. Since <br /> the ground water contaminant plume is well defined, both laterally and vertically, this <br /> '. well no longer provides significant data for'site characterization. Consequently, it is <br /> recommended that MW-9 be destroyed in accordance with California State well <br /> standards. <br /> The next sampling event is scheduled to take place in mid March, 1999. <br /> • CA95DE-029 American Geological Services, Inc. <br /> ' <br /> 11 <br />