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0 0 <br />Work Plan for UGT Investigations -5- 7 November 1991 <br />DDRW, Sharpe Site <br />Tank Site Rationale for Well Installation <br />D-42 Soil sample data had high concentrations of gasoline and <br />BTX and elevated concentrations of diesel (110, 15.99 and <br />1000 mg/kg, respectively). <br />D-44 Soil sample data had high concentrations of diesel, <br />gasoline and BTX (2700, 230 and 20.1 mg/kg, respectively). <br />Page 3-1. The Plan states that the soil borings are to extend to a depth of 15 <br />feet. A depth of 15 feet below ground surface may not provide <br />representative samples from beneath the UGT. The soils borings should be <br />installed in the excavated tank site and samples should be collected <br />starting at the base of the excavated tank and should extend to the <br />ground water table, which may or may not be 15 feet. <br />Page 3-1. The Plan states that all 20 soils borings will be analyzed for lead. <br />However, based on the analytical results for heavy metals in the soils <br />samples from the tank sites (as listed in Table 2-2), very few of the <br />tank sites appear to have elevated concentrations of lead. Therefore, <br />analysis for lead may be excessive. The Plan should have more clearly <br />justified why analysis for lead is needed at each of the soil borings <br />sites. <br />Pages 3-2 Figures 3-1 to 3-4 depict the locations of the soils borings and <br />to 3-5. monitoring well locations. These Figures depict 16 soils borings and <br />seven monitor well locations. These numbers of borings and wells do not <br />correspond to the number of borings and wells as discussed in the text <br />and tables. Therefore, the Figures need to be revised to correspond to <br />the text. <br />Figures 3-1 to 3-4 depict the locations of the soils borings outside of <br />the area of the tank excavations. The soils borings should be installed <br />inside of the area of the former tanks. Soils samples taken vertically <br />through the former tank site, rather than outside of the tank site, are <br />more likely to have been impacted from a leak in the tank. <br />Page 3-9. Table 3-1 lists the analytical parameters for the proposed soils borings. <br />Tank area 0 (tank D-6) is to be analyzed for organochlorine pesticides <br />(Method 8080) and volatile organics (Method 8240). Rather than analyzing <br />for volatile organics in samples from a tank that was known to contain <br />pesticides, the samples should be analyzed for some of the other types of <br />pesticides such as organophosphorus pesticides (Method 8140), carbamate <br />pesticides (modified Method 632) and chlorinated herbicides (Method <br />8150). <br />Page 3-10. Figure 3-5 depicts the proposed soils samples locations to be analyzed <br />for lead using a portable X-ray fluorescence (XFR) unit in the area of <br />Building S-119. Soils samples S3-SED1, as listed on page 6-247 in the RI <br />Report, did not reveal high concentrations of lead in the sludge samples <br />from the sump. Therefore, it is unclear why so many samples need to be <br />analyzed for lead using the XFR unit. The Plan should have more clearly <br />