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t it, WWI <br /> 0ualit Control Boal <br /> California Regional Water Q Y = <br /> Central Valley Region stay Davis <br /> Steven T.Butler,Chair /Governor <br /> S <br /> Nvinston H.Hickos Sacramento Main Office _• ���; <br /> secreralyfor <br /> Internet h[tpa/wvM's"rt0 California 95827-3003 <br /> 3443 Routier Road,Suite A,Sacramento, <br /> Environmental 916 255-3015 <br /> Protection Phone(9l6)255-3000•FAR( ) — <br /> 9 June 2000 <br /> Ms.Margaret Lagorio <br /> ironmental Health Division <br /> San Joaquin County Env <br /> 304 East Weber Avenue <br /> Stockton,CA 95202 <br /> REVIEW OF WORKPLAN FOR GROUNDWATER ASSESSMENT• <br /> ARCO#6100, 25775 PATTERSON PASS, TRACY,SANJOAQUIN COUNTY <br /> lan submitted by Delta <br /> I reviewed the 5 June 2000 Workplan for Groundwater Assessment(Workplan) <br /> for the subject (property.) iThe Workplan describes completing <br /> Environmental Consultants,Incorporated(Dthe area of highest hydrocarbon soil <br /> one boring to a maximum depth of 200 feet below ground surfaceet bS om lete the boring. Soil samples will be <br /> impact. Delta will utilize an air-rotary casing-hammer drilling rig P <br /> collected at 30, 50,70, and 100 feet, and beginning at 100 feet, samples by EPAMethods 8015/8021,ected at every 10 Band for all <br /> total depth of the boring. All samples will be analyzed for TPHg,BTEX by <br /> fuel oxygenates,ethanol,methanol, 1,2-DCA,and EDB by EPA Method 8260B. <br /> Delta also stated in the Workplan that they would extend the boring to groundwater or until two consecutive soil <br /> samples, over a distance of 20 feet,have been collected that do not contain petroleum hydrocarbons. This is not <br /> approved. As stated in our 14 March 2000 and 16 May 2000 letters, Arco must determine whether petroleum <br /> hydrocarbons released from their USTs has impacted groundwater.Therefore,the proposed investigation must <br /> identify the petroleum hydrocarbon impact to groundwater. <br /> The Workplan is approved with the following revisions: <br /> • Complete the proposed boring on the southeast,side of Patterson Pass Road near existing vapor well <br /> VW-17 as stated in the Workplan narrative,not as shown on Workplan Figure 2. <br /> • The boring must extend to groundwater or a minimum of 200 feet bgs. <br /> Please inform me when the fieldwork will start. If you have any questions or comments, call me at <br /> (916)255-3115. <br /> Marty Hartzell <br /> Associate Engineering Geologist <br /> California Environmental Protection Agency <br /> Qa Recycled Paper <br />