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Blaes Environmental Management Inc U-Hau1#709 50 002-70950-03 Groundwater Monitonng Report 10/22/01 4 0 CONCLUSIONS Blacs Environmental conducted a groundwater monitoring event at U-Haul facility #709-50 on September 24 -26 2001 In general, groundwater levels in September 2001 have dropped approximately 5 5 feet since July 2001 Based on the groundwater level measurements from the middle "B" well casings, the groundwater surface map for September 2001 indicated a slight flow gradient toward the southwest The highest groundwater elevation from the middle "B" well casings was measured in monitor well MW-513 Groundwater level measurements from the lower "C" well casings indicated a relative groundwater high at monitor well MW-7 and a relative low at monitor wells MW-6 and MW-8 Despite groundwater on the U-Haul property being relatively flat, the general flow gradient appears to be toward the west Analytical results of groundwater samples collected in September 2001 from the middle "B" and lower "C" well casings both indicated the presence of hydrocarbons in groundwater Results of samples . collected from the middle "B"well casings revealed that the main portion of the hydrocarbon plume(with benzene concentrations greater than 10,000 µg/L) includes wells MW-213 and MW-313 Results of samples collected from the lower"C" well casings revealed that elevated concentrations of hydrocarbons exist near wells MW-4 and MW-6 These wells are located on the eastern and western property boundaries, respectively Despite the detection of hydrocarbons in well MW-4 and MW-6, the central portion of the site near well MW-3 did not contain detectable concentrations of hydrocarbons in groundwater during this sampling event In general, the former fuel USTs and dispenser islands areas are sources of the hydrocarbon plume near wells MW-213 and MW-3B The hydrocarbons detected in the lower "C" well casings do not appear to originate from the same source as the hydrocarbons detected in the middle `B" casings Due to the proximity of the former dispenser area, the detection of hydrocarbons in groundwater from well MW-4 are likely associated with the former dispenser area The detection of hydrocarbons in groundwater from well MW-413 supports this suggestion However, the detection of hydrocarbons in samples from wells MW-6 and MW-6B do not have local source areas and are most likely attributed to the migration of hydrocarbons in groundwater or an unknown source area The migration of hydrocarbons appears to be 10