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Thtifty Oil Company <br /> 1250 N.Wilson Way <br /> Page 2of2 <br /> Additionally, final approval of the RAP can not be conducted without a comparative cost <br /> effectiveness evaluation. No costs were provided other than the estimated $30,000 to <br /> hook up the new wells to the system. <br /> The RAP is inadequate and not approved at this time. (CA Health & Safety Code, <br /> 25296.1 0(c)(3)]. <br /> Please submit an addendum to the RAP that includes a discussion of the treatment <br /> methods and disposal of extracted ground water. A cost analysis is also to be included <br /> that estimates the total costs to implement the RAP.. <br /> The ground water laboratory data from the soil boring/CPT-4 in this area indicated that <br /> total petroleum hydrocarbons as gasoline (TPHg) were detected in the layers of soil. at <br /> approximately 100 feet below ground surface (`bgs). The soil sampling in CPT-4 was <br /> incomplete from 95' bgs to 110' bgs and the depiction of the soils sampled on the boring <br /> log at these depths is a bit confusing. With substantial ground.water contamination <br /> detected at these depths and data gaps in the soil lithology present, EHD cannot concur <br /> with a conclusion that this area is vertically defined. Additional vertical investigation is <br /> warranted. <br /> EHD directs you to install a deeper monitoring well near MW-513. Soil lithology and <br /> soil samples are to be collected by continuous coring procedures starting. at 95' bgs and <br /> continuing to 115' bgs. Based on the location of the zone of highest permeability at this <br /> interval, a five-foot or ten-foot screened-interval monitoring well must be constructed. <br /> The addendum to the RAP is to include a work plan for the required monitoring <br /> well installation and is due at EHD by July 28, 2006. <br /> You may continue to address your submittals to Michael Infurna and if you. have any <br /> concerns, you may either phone him at (209) 468-3454, or contact him by electronic <br /> mail at minfurna sicehd.com. <br /> Donna Heran, REHS, Director <br /> Environmental Health artment <br /> 4 4411 1 'I-k- <br /> Michael J. Infurna Jr., Senior REHS Nuel C. Henderson Jr. RG <br /> LOP / Site Mitigation Unit IV Engineering Geologist, Unit IV <br /> c: CVRWQCB — James L.L. Barton <br /> SWRCB-CUF — Mark Owens <br />