ARCHIVED REPORTS XR0009313 - Laserfiche WebLink

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i 4.4 Floating Oil iA September 1998 sample of groundwater monitoring well MW-2 found black, floating ail that iappeared to be typical of used motor oil Floating oil has been removed from MW-2, using disposable bailers, periodically Approximately 13 4 gallons of floating oil have been removed ithrough 19 September 2001 ' 4.5 Groundwater Flow The groundwater direction of flow for the area bound by MW-1, MW-2 and MW-4 was inferred ito be toward the southeast at a gradient of 0 0079 ft/ft (Figure 3), groundwater direction of flow in the area bound by MW-1, MW-3 and MW-4 was inferred to be curving toward the east a igradient of 0 0101 ft/ft The flow gradient increased from the previous quarter i Figure 4 shows groundwater elevations at various dates Elevations fluctuate over very Isignificant ranges (up to 5 feet in 9 months), which will affect contamination levels, flow direction, etc 5.0 CONCLUSIONS AND RECOMMENDATIONS 5.1 Conclusions The former waste oil USTs caused significant contamination of the soil and groundwater immediately adjacent to the tanks Substantial quantities of oil have been removed from MW-2, however, some contamination remains (as evidenced by the amount of floating oil removed during the quarter) The used oil appears to move very slowly through the soil, so that the area of contamination appears to be in relatively close proximity to the former USTs location The former diesel USTs caused moderate contamination of the soil and groundwater adjacent to ' the tanks Diesel contamination was detected in MW-2 (northeast of MW-1) and MW-3 (southeast of MW-1) in April 2000 This was not evident in later samples Diesel contamination was detected in MW-1 and in MW-4 in the samples taken in September 2001, indicating that diesel contamination still poses a threat to groundwater quality (Figure 5) Environeenng,Inc Project No 01-009 012 Page 5 I