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' A review of Figure 4, Groundwater Elevation, shows that wells MW-1, MW-3 and MW-4 • , moved in tandem from April 2000 through September 2001, with MW-2 generally following the same trend, but, moving higher or lower somewhat randomly This is due to the difficulty 9 of measuring groundwater elevations in MW-2 because of floating hydrocarbons in this well 1 � f � 1 8 0 Conclusions and Recommendations 1 � I i 81 Conclusions ' I 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, contamination remains The used oil appears to move very slowly through the soil and in relatively close proximity to the former USTs location The contamination does not ' I appear in any of the other three wells 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-I) and MW-3 l (southeast of MW-1) in April 2000 `This was not evident in later samples until December 2001 3 IN fe}�-29$ (MW-2) when contamination was detected again Since that time, the diesel contamination in MW-3 and MW-4 has disappeared The contamination in MW-2 remains although it is decreasing consistently The diesel contamination in MW-1 (site of the former diesel USTs)remains The presence of diesel contamination in MW-I and MW-2 ' indicates that diesel contamination is still affecting groundwater quality(Figure 5) E MW-4 was installed down gradient (at that time) from MW-2 to detect possible movement of f ' . used motor oil in the groundwater from the contamination source (former waste oil USTs at MW-2) No oil has been 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 continues to show contamination from gasoline, oxygenates and BTFX Groundwater flow was south/southeast in December 2001, east in March 2002, north/northeast ' in June 2002, southeasterly in September 2002, easterly from MW-1 to MW-3, southerly from MW-2 to MW-3, southwesterly from MW-4 to MW-3 and now easterly from all wells This coupled with a very low gradient, will likely result in contamination remaining in relatively ' close proximity to the source(s) F i 8.2 Recommendations EI recommends • Continued removal of floating oil from MW-2 every four weeks until motor oils no longer appear • Continued quarterly monitoring of the four groundwater monitoring wells at CTL to accumulate data as a basis for future actions, or to show when contamination levels have dropped to insignificant levels • Replace the seal at the grade of MW-1 I E ��