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Work Plan for UGT Investigations -2- 7 November 1991
<br />DDRW, Sharpe Site
<br />Preliminary Evaluation and Investigation of Underground Tank Sites be used
<br />instead of the LUFT Manual for the investigation and cleanup of UGTs.
<br />Page 2-2. Table 2-1 summarizes the current status of UGTs at the site. Two tanks
<br />are reported as never used. It is unclear whether or not these tanks had
<br />been filled with fuel. If the tanks have been filled with fuel, the tanks
<br />have the potential to leak and therefore may be regulated by the State.
<br />Page 2-4. Table 2-2 indicates that the B series tanks are not regulated. It needs
<br />to be clarified that if a tank has been filled, then the tank may be
<br />regulated. In addition, this Table appears to be contradictory to Table
<br />2-1 which indicates that active tanks are regulated. The discrepancies
<br />between the Tables needs to be clarified.
<br />Pages 2-4, Tables 2-2, 2-3, 2-4 and 2-5 are very useful. These Tables summarize the
<br />2-6, 2-8, previous data for each of the UGTs at the site. My review was expedited
<br />2-10 because the Plan contained these Tables. ESE should be commended for
<br />presenting this information in tabular form. We should encouraged ESE to
<br />continue to present technical data in tables and other graphical forms.
<br />However, these Tables could be improved by adding a column which provides
<br />the depth of the soils samples, if available, for which the concentration
<br />data are presented. Without the depths of the soil samples, it is not
<br />possible to evaluate whether or not the cleanup levels established in the
<br />Plan are acceptable or to provide recommendations for the cleanups of the
<br />individual tank sites.
<br />Page 2-4. Many of the tanks (D-2, D-3, D-4, D-7 D-20, D-24, 0-25, D-35, D-36, D-37,
<br />and D-38), listed in Table 2-2 as removed, have no analytical results for
<br />soil samples from the tank excavations. The majority of these tanks were
<br />removed prior to 1990. For the tanks with no data, Sharpe should contact
<br />the San Joaquin County to verify whether or not the County has any
<br />additional data. If there are no data at the County, Sharpe may
<br />ultimately be required to demonstrate that these removed tanks did not
<br />leak.
<br />Page 2-6. Table 2-3 lists those tanks which meet the LUFT Manual Guidelines. Many
<br />of the tanks had low concentrations of either diesel, gasoline or benzene,
<br />toluene and xylene (BTX). Several of these tanks (D-8, D-10, D-17, D-21,
<br />D-28, D-29, D-30, 0-31, D-32, D-33, D-41, 0-45 and D-48), had
<br />concentrations of these contaminants which may pose a threat to water
<br />quality if left in-place. Because the depth of these soil samples were
<br />not provided in the Table, it is not possible to determine whether these
<br />concentrations are acceptable clean-up levels for these tank excavations.
<br />If Sharpe wants to perform a "clean closure" (i.e., cleanup to background
<br />concentrations) for the above listed tanks, then these tanks may need to
<br />be further remediated.
<br />In addition, three of the tanks (D-30, D-32 and D-41) appear to have
<br />elevated concentrations of diesel, gasoline and/or BTX's. The sample from
<br />D-30 had 74 mg/kg of diesel, the sample from 0-32 had 93 mg/kg of diesel
<br />and 0.23 mg/kg of BTX and the sample from D-41 had 45 mg/kg of diesel,
<br />0.15 mg/kg of gasoline and 0.08 mg/kg of BTX. Depending on the depth of
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