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underground storage tanks (USTs) did not contain lead above the <br /> • laboratory detection limit of 10 parts per million (ppm) These results <br /> are presented in the "Preliminary Investigation and Evaluation Report" <br /> prepared by Geological Audit Services, Inc dated March 28, 1995 In <br /> addition, composite soil samples collected on June 5, 1998 did n o t <br /> contain elevated lead concentrations These results are presented in the <br /> "Interim Investigation and Remediation Report" prepared by Remedy, Inc <br /> dated September 16, 1998 In the eight samples analyzed for lead, the <br /> lead concentrations ranged from 20 to 45 ppm All of these Iead <br /> concentrations are below 5-times the Soluble Threshold Limit <br /> Concentration (STLC), which suggests that lead should not be an issue a t <br /> the site It is also worth noting that these samples contained petroleum <br /> hydrocarbon concentrations, which show that these samples were <br /> collected in relevant locations and not dust in "clean" locations away from <br /> the USTs For these reasons, ASE believes that lead need not be added to <br /> the analytical suite for the site, and it is extremely unlikely that lead, a <br /> metal compound with limited mobility, would be detected in groundwater <br /> samples collected in wells off-site If for some reason lead were to b e <br /> detected in these off-site wells, it would seem more Iikely that it would b e <br /> related to other off-site sources <br /> CONCERN#2—SCREENED INTERVALS OF MONITORING WELLS <br /> ASE agrees with the modification in screened intervals in the RWQCB <br /> letter ASE will modify the scope of work to reflect these changes <br /> CONCERN#3 —DRILLING PROCEDURE FOR FLOWING SANDS <br /> ASE does follow the drilling procedure noted in the RWQCB letter The <br /> augers will be filled with water prior to pushing out the auger plug for <br /> well construction to minimize potential problems with flowing sands <br /> Should you have any additional questions or comments, please call us at <br /> (925) 820-9391 <br /> Respectfully submitted, � gED GFol <br /> AQUA SCIENCE ENGINEERS, INC <br /> Ho 65� :t <br /> Robert E Ktt?�, R G , R E A OF CAL <br /> • Senior Geologist <br /> Frank's One Stop Workplan Addendum — October 2003 <br /> -2- <br />