ARCHIVED REPORTS XR0009314 - Laserfiche WebLink

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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 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 contarnination 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, and the diesel contamination in MW-1 is no longer evident, indicating that diesel contamination has dissipated ' and poses little or no threat to groundwater quality (Figure S) ' MW-4 was installed down gradient from MW-2 to detect possible movement of used motor oil in the groundwater from the contamination source (former waste oil USTs at MW-2) No oil was detected in the groundwater at MW-4, indicating that used oil contamination has not spread down gradient from MW-2 as far as MW-4 MW-4 groundwater was also free of diesel ' contamination MW-4 remains contaminated by gasoline, oxygenates and BTEX, at relatively high levels The ' source of this contamination is not known at this time The adjacent site (south of the CTL site) is a former key-lock gasoline service station The USTs from that site were removed in September 1998 ' 5.2 Recommendations EI recommends 1 Continued removal of floating oil from MW-2 every two to four weeks, depending upon ' re-charge rate, until motor oils no longer appear 2 The next groundwater monitoring should be conducted concurrently with the adjacent Environeenng,Inc Project No 01-006 011 Page 6 1