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VV U C LLI V�� <br /> C� ARCADIS J���� _� 2010 <br /> Infrastructure, environment, buildings ENVIRON ENT HEATH ARCADIS <br /> g f 950 Glenn Drive <br /> PERMIT/SERVICES Suite 125 <br /> Folsom <br /> California 95630 <br /> Ms. Lori Duncan Tel 916-985-2079 <br /> Senior Registered Environmental Health Specialist Fax 916-985-2093 <br /> San Joaquin County Environmental Health'De partm ent www.arcadis-us.com <br /> IL600 East Main Street <br /> Stockton, California 95202-3029 <br /> ENVIRONMENT <br /> Subject: <br /> Downgradient Well Installation Approval Request- <br /> Former Texaco Service Station <br /> Chevron Site ID 309075 ' <br /> 3978 South.Highway 99 J Date: <br /> Stockton, California , . January 5, 2010 <br /> SJCEHD Site Code: 1322 ;- <br /> } Contact: <br /> Dear Ms. Duncan: rr Sherrie Lang_ <br /> ARCADIS, on behalf of Chevron Environmental Management Company(Chevron), Phone: <br /> has prepared this letter to request approval from:the,San Joaquin County 916.985.2079 ext. 16 <br /> Environmental Health Department(SJCEHD) regarding the downgradient.-well email: <br /> f... <br /> installation. The shallow well (MW-6)was installed-as proposed in ARCADIS' Work Sherrie.Lang@ <br /> Plan for Site Assessment, dated September 30;`2009;with the exception'of the well arcadis-us.com. <br /> screen. During a telephone conversation between Brett Krehbiel•with ARCADIS and <br /> Lori Duncan with SJCEHD on November 12,2009, the SJCEHD approved the our ref: <br /> shallow well (MW-6)screen interval to be installed.at a depth of 55 to 70 feet below 60046434.0000 <br /> ground surface (bgs) rather than 65 to 75 feet rbgs td accommodate the higher <br /> groundwater elevations encountered in the field.,The shallow and deep wells were <br /> installed during the week of November 9, 2009 anti,developed and sampled on- <br /> November 17, 2009. During installation of the deep'well (MW-6D), the'bottom of the <br /> poly vinyl chloride (PVC)casing was set at 1,119 feet bgs; however, the bottom of the <br /> well was measured at 115.6 feet bgs during development. In addition, the pH at <br /> MW-6D was measured at or above.11.76 during development(Attachment 1). <br /> To investigate the discrepancy of the to well depth observed at MW-6D;ARCADIS <br /> supervised Cascade Drilling,LP(Cascade), during scoping activities using,a down= <br /> well camera on November 20, 2009. Based on the down-well scoping results, it has <br /> been determined that grout enteredthe casing through the.well screen and <br /> settled at the bottom creating the shallower well depth and causing elevated pH <br /> measurements.The total depth of the well was confirmed at 115.6 feet bgs with a <br /> screen interval of 109 to 115.6.feet bgs.The,pH was collected again and:measured <br /> Imagine the result <br /> IICA5FPIData*rro whEN%ACHEVROM3090752 Canmurrvcatim_Tmspmdence\Cmrespohdence Regulator AWetl Install LetteAM75 Deep Wetl Install 4pmva1 Request_4281010950.d. <br />