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SECOR www secor corn <br /> INTERNATIONAL 3017 Kdgore Road Suite 100 <br /> S E C 0 R INCORPORATED Rancho Cordova CA 95670 <br /> ` 916 861-0400 TEL <br /> (\ 916-/867-0430 Fnx <br /> j April 1, 2004 ��E <br /> I <br /> APR 0 8 2004 <br /> Mr Ed Ralston ENVIRUNMENT HEALTH <br /> ConocoPhillips PERMIT/SERVICES <br /> 76 Broadway <br /> Sacramento, CA 95818 <br /> RE Quarterly Remedial Performance Summary-Third and Fourth Quarter 2003 <br /> ConocoPhillips Station No 6981 <br /> 4707 Pacific Avenue <br /> Stockton, CA <br /> SECOR Project No 77CP 60004 01 6981 <br /> Dear Mr Ralston <br /> This letter, prepared by SECOR International Incorporated (SECOR) on behalf of ConocoPhillips, <br /> presents a remedial action performance summary for the ozone injection system operating at the site <br /> referenced above Attachment A presents the remedial performance summary for the fourth quarter <br /> 2003 Field Data Sheets are presented as Attachment B Certified laboratory analytical reports and <br /> chain of custody documentation are presented as Attachment C A brief site background and the <br /> status of recent remedial activities are presented below <br /> (� SITE BACKGROUND <br /> The site is located at the intersection of Pacific Avenue and West March Lane In Stockton, California <br /> The site is currently an operating 76 service station In November 2001 Gettler-Ryan installed an <br /> ozone microsparge system on the site SECOR took over site operation in September 2003 <br /> REMEDIAL PERFORMANCE EVALUATION <br /> Ozone Injection Operation <br /> The ozone injection systems consist of panel mounted KVA C-SpargeTM Systems that produce 4 <br /> grams per hour (0 009 pounds per hour)of ozone The system injects ozone to ten ozone wells SP- <br /> 2, SP-4 through SP-9, and SP-11 through SP-13 System operational data is presented in Table A-1 <br /> The system was placed Into operation on December 19, 2001 During the third and fourth quarter of <br /> 2003 the system operated at 100% of the programmed runtime <br /> Ozone Injection Performance <br /> The performance of the ozone Injection system in causing breakdown of contaminants beneath the <br /> site is determined by groundwater sampling Monthly groundwater samples were collected from <br /> monitoring wells MW-16 and VW-7 on July 22, August 22, September 26, October 31, November 25, <br /> and December 17, 2003 and analyzed for total petroleum hydrocarbons as gasoline (TPHg), <br /> benzene, toluene, ethylbenzene, and total xylenes (BTEX compounds), and methyl tert-butyl ether <br /> (MtBE) Results of monthly groundwater sampling events are summarized in Table A-2 <br /> Concentration versus time graphs for dissolved TPHg, benzene, and MtBE in monitoring wells MW- <br /> 16 and VW-7 are provided In Figures A-1 and A-2 Certified laboratory analytical reports and chain- <br /> of-custody documentation for the groundwater monitoring events conducted during the third and <br /> fourth quarter of 2003 are provided in Attachment C <br /> I <br /> I IConocoPhdhps%Tosco Marketmg169811QRPS16981 4QO3 QRPS doc <br /> I <br />