Laserfiche WebLink
• Item $. No— The vertical and lateral extent of groundwater contamination has not <br /> been defined. <br /> See Workplan for Vertical and Lateral Extent Sampling Downgradient of MW12, dated February <br /> 20, 2001 <br /> Item 9 No - Zone of influence calculated and assumptions used for subsurface <br /> remediation system and the zone of capture attained for the soil and groundwater <br /> remediation system. <br /> Table 1 found in all reports shows the measured vacuum influence at the well heads Figures 8A, 8B <br /> and 8C show the radius of influence from direct measurements obtained at the monitoring wells <br /> December 1992, March 1994 and March 1998 respectively. <br /> Item 93. Complete a mass balance calculation of groundwater contamination using <br /> all monitoring well data <br /> Figures 4A, SA, 6A, 7A, and 9A show the lateral and vertical extent of TPHg soil, TPHg <br /> groundwater, and TPHg soil gas prior to vapor extraction The areas from these figures were used <br /> to calculate the TPHg mass associated with this site prior to remediation, see Table 3. <br /> An estimated 28,244 gallons of gasohne range hydrocarbons were associated with the soils, soil gas <br /> and groundwater beneath R603 prior to remediation. <br /> Free product bailing, vapor extraction and groundwater purging removed an estimated 12,083 <br /> gallons of gasoline Vapor extraction and removal of CO2 contributed to an additional 23,233 <br /> gallons as gasoline removed, for a total of over 35,000 gallons of gasoline range hydrocarbons <br /> removed from the subsurface beneath R603 (124% removal), see Table 4. <br /> Influent samples obtained from the vapor extraction system have shown that removal rates have <br /> decreased to asymptotic levels, see Table 3 <br /> Soil Contamination <br /> Prior to site remediation, UST removal and limited over-excavation soil samples showed high <br /> concentration of TPHg and BTEX were left in place Remediation (vapor extraction) successfully <br /> removed the gasoline contaminants from high concentrations of TPHg 5100 mg/Kg, Benzene 120 <br /> mg/Kg, Toluene 650 mg/Kg, Ethylbenzene 1100 mg/Kg, and Xylenes 960 mg/Kg to below <br /> laboratory lower detection limits, see Table 2 and W A. Craig,lnc , Underground Storage Tank <br /> Closure Report,dated November 10, 2000. <br /> Confirmation soil samples obtained November 3, 2000, from native soil beneath the recently <br /> removed UST's were below laboratory lower detection limits for all analytes tested Laboratory <br /> 5 R-603 Jan 2001 <br />