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KLEINFFLDER <br /> • 5 CONCLUSIONS AND RECOMMENDATIONS <br /> 51 Conclusions <br /> ' TPH extractable concentrations of 500 and 3,900 mg/kg were detected in boring AB-3 at <br /> approximate depths of 5 and 10 feet, respectively Low concentrations of xylenes and/or <br /> ' ethylbenzene were also detected in boring AB-3 at these depths Operation of the AGSTs <br /> appears to have impacted soil in the vicinity of boring AB-3 to a depth of 10 feet <br /> Generally, low TPH concentrations were reported in boring VB-2 at the termination depth of 25 <br /> feet (22 mg/kg) Since TPH concentrations were not detected in soil samples in this boring <br /> (VB-2) above 25 feet, the concentrations reported may be due to migration of TPH in <br /> groundwater from a nearby source or from vadose zone transport <br /> Surface samples collected from AB-1 through AB-4, and VB-1 and VB-2 had TPH extractable <br /> concentrations reported ranging from 22 to 3,400 mg/kg No BTEX compounds were reported in <br /> these surface samples above laboratory reporting limits <br /> ' Groundwater was not encountered duringi v <br /> this approved drilling program and therefore was not <br />' assessed The drill cuttings have been removed from the site and properly disposed of at Forward <br /> Landfill <br />' 5 2 Recommendations <br />' Based on TPH concentrations detected in boring AB-3 and the surface samples, the impacted soil <br /> should be excavated for remediation or disposal at an appropriate waste disposal facility <br /> Confirmation soil samples will need to be collected from the excavation sidewalls and bottom <br /> These soil samples should be analyzed for TPH extractable using the modified EPA Method <br />' 8015 According to the RWQCB, if any impacted soil is to remain in place a waste extraction <br /> test will need to be performed to assess leachability and evaluate potential impact to <br /> groundwater Due to the low concentrations reported in one sample collected from VB-2 at a <br />' depth of 25 feet (22 mg/kg), Kleinfelder does not recommend additional assessment of soil in <br /> this area <br />' 23-482276-AOO/TR950096 Page 9 of 12 October 19, 1995 <br /> Copyright 1995 Kleinfelder, Inc <br />