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1 <br /> October 4,2002 <br /> NOA ENVIRONMENTAL PROJECT NUMBER: LE00-429 <br /> According to the site closure requirements of the Tri-Regional Board Staff Recommendations for <br /> Preliminary Evaluation and Investigation of Underground Tank Systems, the total petroleum <br />' hydrocarbon levels must be less than 100 ppm in soil samples taken within the first two feet of native <br /> soil beneath the tank The NOA Environmental samples were taken at rune (9) feet down in the <br /> region ofthe former UST This depth should be reasonable because Mr Knott,in his 1987 Inspection <br />' Report, stated that he took soil samples"8-10 feet below surface"(Appendix C), it can be assumed <br /> therefore that the tank pit was approximately this deep The extractable hydrocarbon levels in the <br /> samples taken by NOA Environmental were reported at a maximum of 1 9 ppm at this level, well <br /> 1 below the 100 ppm maximum for TPH <br /> Additionally,BTEX was found to be non-detectable at a reporting limit of 0 0050 ppm Site closure <br />' was initially denied because the BTEX detection limit of 0 2 ppm was too high for shallow <br /> groundwater (Appendix C), the test results from Sequioa Analytical should dismiss any lingering <br />' concerns regarding BTEX contamination <br /> Finally, the soil at the site has low permeability As stated above in section IV, the soil is <br /> predominantly clay with silty clay, silty clay loam, loam, and hardpan in places <br /> The following points are also worthy of mention when considering this site for closure, pursuant to <br /> Table#3 of the Tri-Regional Board guidelines(see Mr Knoll's Inspection Report in Appendix C for <br /> confirmation) <br /> • No obviously contaminated soil was noted by Mr Knoll at the site of the former UST, <br /> consequently, no additional soil sampling was necessary <br /> • Sampling and analytical protocols conformed to the standards described in the Tri-Regional <br /> Board guidelines <br /> • Appropriate laboratory analyses were determined based upon the requirements of Table 2 of <br /> the Tri-Regional Board guidelines, these analyses and QA/QC are included in Appendix E <br /> • No note was made in the Inspection Report of a need for sidewall sampling <br /> • No mention was made in the Inspection Report of water found in the excavation pit during <br /> the tank removal <br /> • No underground piping was indicated in the Inspection Report <br /> ' The depths and locations of the soil samples taken are submitted in Appendix F <br /> 1 <br /> ' 11 <br /> 1 � <br />