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4 5 Groundwater Flow Groundwater flow direction is southeasterly It appears to turn easterly near the south and east ' property boundaries (Figure 3) The flow gradient dropped very significantly from previous quarters, approaching zero (0 001 ft/ft) Figure 4 shows groundwater elevations at various dates Elevations fluctuate over very significant ranges (3 and 4 feet in 3 to 4 months), which will affect contamination levels, flow direction, etc I 5.0 CONCLUSIONS AND RECOMMENDATIONS 5.1 Conclusions ISI IThe former used 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 contamination was detected in MW-2 (northeast of MW-I) and MW-3 (southeast of MW-1) in April 2000 This was not evident in later samples (July and November 2000 and March 2001), and the diesel contamination in MW-1 continues to drop over this same ' period (330 ppm to 8 8 ppm), indicating that diesel contamination is dissipating and poses little or no threat to groundwater quality (Figure 5) 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 used 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 Environeering,Inc Project No 01-003 10 Page 5