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Blaes Environmental Management Inc U-Haul#709-50 002 70950-03 Groundwater Monitoring Report 10/22/01 Analytical results of groundwater samples collected from the well casings screened across the groundwater interface (middle "B" casings) revealed the highest concentrations of hydrocarbons in groundwater from wells MW-313, MW-213, MW-413, and MW-613 The concentrations of hydrocarbons in groundwater from MW-313 (170,000 micrograms per liter [µg/L] TPHg and 40,000 µglL benzene) and MW-213 (59,000 µg/L TPHg and 18,000 µg/L benzene) suggest that the source area of hydrocarbons was near MW-313 and MW-213 The elevated concentrations of hydrocarbons in water from MW-413, and MW-613 suggest that the hydrocarbon plume has spread across the site between the eastern and western property boundaries The non-detect levels of benzene in groundwater from monitor wells MW-513 and MW-8A suggests that the boundary of the hydrocarbon plume has not spread to the northern portion of the site The analytical results of the sample from well MW-913 indicated a non-detect level of benzene and the detection of 140 µg/L TPHg This result suggests that the southern extent of the hydrocarbon plume is near well MW-9B The approximate extent of hydrocarbons in groundwater associated with the middle"B" casings is shown on Figures 5 and 6 Analytical results of groundwater samples collected from the lower "C" casing wells, screened between approximately 60 and 100 feet bgs, revealed the highest concentrations of hydrocarbons in groundwater • from wells MW-6 and MW-4 The detection of hydrocarbons in groundwater from wells MW-6 and MW-4, and the absence of hydrocarbon in groundwater from well MW-3, indicated a shift in the hydrocarbon concentration pattern compared with data from the middle "B" casings Rather than a uniform and consistent hydrocarbon plume, the hydrocarbon plume in the lower "C" casing wells is segregated by the lack of detectable hydrocarbons at well MW-3 Samples from monitor wells MW-5 and MW-8 did not contain TPHg or benzene above method detection limits The approximate extent of hydrocarbons in groundwater associated with the lower"C" casings is shown on Figures 7 and 8 Laboratory analysis of groundwater samples for fuel additives (MTBE, TBA, DIPS, ETBE, TAME, and naphthalene) indicated non-detectable results In some samples, the method detection levels were raised due to laboratory sample dilution,which may, in part, explain the lack of detection of fuel additives 9