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01/06/2004 16 07 2094683433 FIFTH FLOOR PAGE 02 <br /> ru r <br /> ENVIRONMEN'T'AL HEALTH DEPARTMENT <br /> *FFzo <br /> S,�N .lrOA.QU'Yl�T COITNT'�'Donna K.Heran R E H SArector 304 East Weber Avenue,lord Floor Carl Borgman,R E H S <br /> Aa Olsen,R E A.S Stockton, Califorma 95202-2708 Mike Huggins,R E H S,R D I <br /> Pro am Mruia er Douglas W Wilson,R.E H S <br /> Program <br /> A Catulla,R H S Telephone (209) 46$-3420 Margaret Lagono,RE H S <br /> Program Manager Fax. (209)464-0138 Robert McClellon,R E K S <br /> Mark Sarcellos,R.E H S <br /> ffi]WARD C RALSTON �V] <br /> CONOCOPHILLIPS <br /> 76 BROADWAY <br /> SACRAMENTO CA 95812 <br /> RE. Circle K Store/ Service Station #01205 SITE CODE 507195 <br /> 16470 Cambridge St RO# 138 <br /> Lathrop, CA , 95330 <br /> WORK PLAN "Addendum to Work Plan for Off-Site Assessment" <br /> DATED October 13, 2003. <br /> PREPARED BY Secor— Rusty Benkosky, P.E. <br /> STATUS: APPROVED (with conditions noted below) <br /> ADE UATE AND NECESSARY ELEMENTS OF THE WORK PLAN [H&S <br /> 25299 37, subd(c)(3)1• <br /> • Two phase approach with phase one proposal to install five offsite <br /> GeoProbes, 12-15 feet deep to north, northeast, and east in <br /> continuing effort to define the lateral extent of the ground water <br /> petroleum plume and, <br /> In phase two, install (1-5)shallow groundwater monitoring wells <br /> AP offsite in areas of concern as determined by Geoprobe phase and, <br /> Analyze selected soil and all ground water samples for TPH as <br /> gasoline, BTEX, 1,2-DCA, EDB, MISE, Ethanol, and the Oxygenates <br /> and submit the report of findings to END. <br /> COMMENTS AND CONDITIONS- <br /> 0 'Response'/ proposal dated December 30, 2003, advised the Site <br /> Conceptual Model (SCM) will not be submitted to EHQ until after the <br /> lateral and vertical delineation is completed. Also noted in this latest <br /> proposal was the intent to enter interim remediation (Ozone sparge) <br /> onsite to reduce the MtBE impact. With the highest MtBE ground <br /> water concentration now down gradient and offsite (MW-12), EMD is <br /> concerned that onsite interim (TRAP) action without a clear <br /> understanding of the MtBE migration and extents may not be cost- <br /> effective or practical. <br />