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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, D-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, D-31 , D-32, D-33, D-41, D-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 D-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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