ARCHIVED REPORTS XR0009306 - Laserfiche WebLink

Home Browse Search

7.4 Floating Oil • ` K A September 1998 sample of groundwater monitoring well MW-2 found black, floating oil that appeared to be typical of used motor oil Floating oil has been removed from MW-2, using disposable bailers and absorbent socks, periodically since that time Approximately 19 8 gallons of floating oil have been removed through 11/11/03 (Table 3) 7.5 Groundwater Flow The groundwater direction of flow for the area was inferred to be southeasterly at a gradient of I 0 00323 ft/ft(Figure 3) y Figure 4 shows groundwater elevations at various dates Elevations fluctuate over very significant ranges (up to 5 feet in 9 months), which will affect contamination levels, flow direction, gradient,etc A review of Figure 4, Groundwater Elevation, shows that wells MW-1, MW-3 and MW-4 kkw 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 ' of measuring groundwater elevations in MW-2 because of floating hydrocarbons in this well 8 0 Conclusions and Recommendations 8.1 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, 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 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-1) and MW-3 (southeast of MW-1) in April 2000"This was not evident in later samples until December 2001 - 4W-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) is ND The presence of diesel contamination in MW-2 indicates that diesel contamination is still affecting groundwater quality(Figure 5) MW-4 was installed down gradient (at that time) 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 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 MW4 continues to show contamination from gasoline,oxygenates and BTEX 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 southeasterly This coupled . with a very low gradient, will likely result in contamination remaining in relatively close 7 / i f