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EXECUTIVE SUMMARY • Upgradient Environmental Consultants visited the Valley Motors dealership on October 2 7 to measure water depths and collect groundwater samples from the four on-site monitor well, The depth to groundwater has remained relatively constant since the last monitoring in August and measurements indicate that groundwater continues to flow to the east The data indicate the t the gradient is steeper in the northern part of the site near VM-4 than in the southern part of the site near VM-3 The difference appears to be related to the permeability of the water-bearing z.,ne In the north, low-permeability clay near the ground surface forms a slight confining layer, causing the static water surface to be slightly deeper than in the southern part of the site. After measuring the depth to groundwater in all four wells, 12 to 15 gallons of water were oumped from each well and contained in a 55-gallon drum Water samples were then collected wit] disposable Teflon bailers,poured into 40-m1 vials and 1-liter amber bottles, and preserved For laboratory analysis The samples were analyzed for TPH-gasolme and TPH-diesel using E['A method 602, for BTEX using EPA method 8020, and for five oxygenates using EPA method 8240B Contaminant concentrations continued to decline in VM-1, and are now at about die same level as in December 1997 Concentrations in VM-2 are lower than they were in August, t it still exceed their concentrations in December 1997 Concentrations of all analytes m VM-4 are approximately 50% lower than their previous levels in August, except for tert-butanol, wh ich was previously not detected No MTBE was detected in any of the wells In accordance with previous communications regarding the analysis for chlorinated hydroc arbons, . the water samples were not analyzed for these contaminants It is presumed that the concei trations of these compounds continue to exceed regulatory limits The data collected since 1995 imply that contaminated soil in the general vicinity of the foimer dispenser island(northwest cornier of the site) is a continuing source for further groundwat,.r contamination,particularly when the static water level is less than 35 feet Removal of thi: source is likely to result in immediate as well as long-term improvement in groundwater quality, bet ause groundwater is presently at a depth of 34 feet and is likely to rise during the first quarter of 1999 In our April 1998 Soil Assessment Report we estimated that approximately 1,000 cubic yards of soil are present beneath the site Nearly all of this soil should be accessible to excavation, althc ugh some contaminated soil is probably present beneath the sidewalk along Grant Street and is not accessible Although it would be preferable to excavate this soil now,before the static wat-r level begins to nse, financial and operational constraints make this impossible The next opporti inity to perform the excavtion work will be dunng the second quarter of 1999, after the water leve has stabilized or begun to decline i 1