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Sent By: RWOCB; 2553439;WWI Jun-20 !y' 7:14; Page 3/3 <br /> Former Town and County Chevron -2 - 20 June 2001 <br /> 13336 Highway 88 East,I=keford <br /> maximum depth of 120 feet on the subjwt property and convcrted to monitoring wells. TPI1g,benzene,and <br /> toluene were identified in soils down to 36 feet, and low concentrations of toluene were; identified in soils down <br /> to 99 feet, the total depth of soil sampling. <br /> The three monitoring wells were purged And sampled on 10 March 2001. The only contaminant identified in <br /> groundwater was toluene in MW-2 at 5 110. MtBE and other oxygenates were non-detect at appropriate <br /> detection Iimits. The depth to water was,measured at 81 feet below ground surface. <br /> GeoSoly recommcn&continued sampling of the three monitoring wells to determine contaminant trends. Board <br /> and County staff discussed the results an'd recommendations of the investigation Report,and agree with your <br /> recommendations. Therefore,please cothplete the next quarterly monitoring and sampling event by <br /> 30 June 2001,and submit the second:qukrter monitoring report by 15 August 2001. All groundwater samples <br /> must be analyzed for TPHg by EPA Method 801 SM,for BTEX by EPA Method 8020 or 8260B,and for Mt.BF, <br /> TBA, DIPB,ETBE,TAME, 1,2-dichlorgetbane,and ethylene dibromide by EPA Method 8260B. Some <br /> laboratories can run a complete suite ofpetroleum constituents and fuel additives by EPA Method 8260B, <br /> thereby saving considerable cost, <br /> Until investigation and cleanup activities are complete and the site receives a No Further Action Requirrd letter, <br /> Chevron must submit quarterly status reports to the County and Regional Board. These reports must include <br /> results of groundwater monitoring,and be prepared as presented in enclosed Appendix A to the Tri-Regional <br /> Recommendations. <br /> Also,a revised mass balance estimate must be submitted in the second quarter status report. Board staff <br /> reviewed the mass balance estimate submitted with the Soil Boring Report, and determined that you incorrectly <br /> converted milligrams to kilograms. The result of this error has overestimated the contaminant mass in soil by <br /> 1,000 times. The rcicvance of estimating the contaminant mass in soil is to determine the potential for soil <br /> contamination to impact groundwater. In this case,your estimate of 67,812 kilograms of TI'Hg(or <br /> 22,950 gallons)shows a very high potential for soil contamination to impact groundwater. <br /> Once the County and Board staff's review future quarterly status reports,we can detcrmine if additional corrective <br /> actions are-needed. Please contact Jefky Wong at San Joaquin County Environmental Health Division at least <br /> two business days prior to any site work or sampling. If you have any questions,please call Jeffrey Wong at <br /> (209)468-0335,or me at(916)255-3115. <br /> APPROVED <br /> Author <br /> Marty Hartzell <br /> Associate Engineering Geologist . <br /> Senior <br /> Attachment <br /> cc: Mr.Mark Owens,UST Cleanup Fund, State Water Resources Control Board, Sacramento <br /> Mr.Jeffrey Wong, San Joaquin County Environmental Health Division, Stockton <br /> Mr.Prank Goldman,C'teoSoly LLC, Sonoma <br />