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' BURfEnwronmental Management Inc U-14aul#709-50 002-70950-02 Semi-Annual Report 12/14/00 ' 4.0 CONCLUSIONS Blaes Environmental conducted two groundwater monitoring events at U-Haul facility #709-50 in June and September 2000 Groundwater level measurements collected during the two monitoring events indicated that the groundwater elevation dropped approximately seven feet from June 26 to September 26, 2000 On June 26, 2000, the groundwater level at the site ranged from 24 49 to 26 23 feet below mean sea IeveI The corresponding groundwater flow direction was toward the northwest with an estimated gradient of approximately 0 0625 feet per foot(Figure 3) On September 26, 2000, the groundwater level at the site ranged from 32 24 to 32 58 feet below mean sea level The corresponding September groundwater gradient was relatively flat with no apparent flow direction Due to the change In water level from June to September, the upper "A" casing wells did not contain water during the September monitoring event IDissolved oxygen measurements from the two monitoring events indicated that the lower casing wells typically contained higher levels of dissolved oxygen with concentrations greater that 10% The exceptions to this trend were measurements from monitor well MW-4, where elevated hydrocarbon concentrations may have influenced dissolved oxygen concentrations Analysis of groundwater samples from both monitoring events revealed similar results Groundwater Isamples from monitor well MW-3A In June and MW-313 in September both contained the highest concentrations of hydrocarbons detected In the suite of samples collected from the site These results suggest that a source point for hydrocarbon impact to the groundwater surface appears to be near monitor well MW-3A The other consistency in results was visible in the figures showing the extent of I hydrocarbons (Figures 4, 5, 6, 8, and 9) Comparing the extent of hydrocarbons between the casings interfacing with the groundwater surface (casings "A" In June and casing "B" In September) and the lower casings, both monitoring events revealed a shift In concentrations from beneath the dispenser island to the western portion of the site The extent of hydrocarbons at the groundwater surface from both monitoring events appeared to be defined to the northwest and north Samples from the lower casings indicated the presence of hydrocarbons across the site 15