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contamination level, as shown in Figure 5, dropped to ND in June 2001, increased to 59 ppm in <br /> Sept 2001 and has remained relatively constant since Contamination from THP-gasoline <br /> decreased this quarter <br /> Diesel contamination continues to appear in MW-2 - <br /> pp as well as MW 4 MW-3 showed no diesel <br />' contamination this quarter after the appearance last quarter <br /> The reversal of trends shown in this, and the prior quarter sampling, may have resulted from the <br /> Iextreme changes in groundwater elevation (Figure 4), a 7 ft drop from April 2000 to September <br /> 2001, a 4 foot increase to March 2002 and a 1-foot drop this quarter <br /> 4.4 Floating Oil <br /> A September 1998 sample of groundwater monitoring well MW-2 found black, floating oil that <br /> appeared to be typical of used motor oil Floating oil has been removed from MW-2, using <br /> disposable bailers, periodically since that time Approximately 15 9 gallons of floating oil have <br /> been removed through 25 June 2002 (Table 3) <br /> • 4.5 Groundwater Flow <br /> The groundwater direction of flow for the area was inferred to be curving toward the north at a <br /> gradient of 0 002 ft/ft to 0 005 ft/ft (Figure 3) <br /> r <br /> The flow gradient increased slightly from the previous quarter <br /> Figure 4 shows groundwater elevations at various dates Elevations fluctuate over very <br /> significant ranges (up to 5 feet in 9 months), which will affect contamination levels, flow <br /> direction, etc <br /> 50 CONCLUSIONS AND RECOMMENDATIONS <br /> 5.9 Conclusions <br /> The former waste oil USTs caused significant contamination of the soil and groundwater <br /> immediately adjacent to the tanks Substantial quantities of oil have been removed from MW-2, <br /> however, some contamination remains The used oil appears to move very slowly through the <br /> Enveroneenng,Inc Prgect No 02 00716 page 5 <br /> I <br />