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15 feet bgs in each well bore, i e , from at and just below the water table No petroleum <br /> • hydrocarbon analytes were detected in any of the soil samples Following development, the wells <br /> were sampled two consecutive quarters, with no analytes detected In the groundwater samples <br /> (Shaw, 2003b) There were no field indications of fuel product or dissolved fuel constituents <br />' observed in either of the sampling events Copies of the well installation logs are included in <br /> Appendix B A summary of the soil and groundwater analytical results is included to Tables 6 <br />' and 7, with the groundwater gradient data from the last quarterly monitoring event depicted in <br /> Figure 7 (Shaw, 2003c) <br /> Based on the lack of analytes detected in the groundwater samples collected from the monitoring <br /> wells, the relative immobility of the remaining heavy-end petroleum hydrocarbons and the <br /> overall depth to groundwater, the site is being recommended for case closure, with no further <br /> action recommended <br /> 4.0 Extent of Soil and Groundwater Impact <br /> TPH-D was detected at concentrations up to 5 0 ppm in soil samples collected following the <br /> removal of the 2,000-gallon diesel UST in March 2002, and up to 2 7 ppm in soil borings <br /> lie completed in September 2002 No petroleum hydrocarbons were encountered in soil samples <br /> collected following the removal of a 500-gallon heating oil tank in February 2002, or in soil <br /> samples collected during monitoring well Installation activities in July 2003 Figure 8 depicts the <br /> estimated lateral and vertical extent of petroleum hydrocarbons in soil <br />' A groundwater sample collected from the 2,000-gallon diesel UST excavation contained <br /> concentrations of TPH-D at a concentration of 130 ppb TPH-D was also encountered in <br /> groundwater from three of the soil borings advanced at the site at concentrations ranging from 50 <br /> ppb to 390 ppb No BTEX constituents or MTBE were encountered In any of the groundwater <br /> samples collected from the site No petroleum hydrocarbon analytes have been encountered In <br /> any of the groundwater samples collected from the monitoring wells Figure 9 depicts the <br />' estimated extent of impacted groundwater <br />' No lighter-end hydrocarbons or fuel oxygenates (BTEX and MTBE) have been detected in any of <br /> the soil or groundwater samples collected from the site TPH-D has been the only analyte <br />' encountered, at concentrations up to 5 ppm in soil, in the immediate vicinity of the former 2,000- <br /> gallon diesel UST and piping trench Based on sample analytical data from previous <br /> CNCUISHARE\US'R04-"I doc 3 <br />