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(N <br /> THOMAS R.FLINN P.O.BOX 1810.1810 E.HAZELTON AVENUE <br /> DIRECTOR STOCKTON,CALIFORNIA 95201 <br /> (209)468-3000 FAX(209)468-2999 <br /> www.sjgov.org/pubworks <br /> ' TCHIEF HOMAS DEPUTY DIRECTOR Working for <br /> MANUEL SOLORIO Workfo YOU <br /> DEPUTY DIRECTOR <br /> ' STEVEN WINKLER <br /> DEPUTY DIRECTOR <br /> ROGERJANES <br /> BUSINESS ADMINISTRATOR <br /> January 28, 2008 <br /> Mr. Todd Del Frate <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> 11020 Sun Center Drive, #200 <br /> Rancho Cordova, California 95670-6114 <br /> ' SUBJECT: SECOND SEMESTER AND ANNUAL 2007 GROUNDWATER AND SURFACE WATER <br /> MONITORING REPORT; FOOTHILL SANITARY LANDFILL <br /> ' Dear Mr. Del Frate: <br /> Enclosed is the Second Semester 2007 Monitoring Report for the Foothill Sanitary Landfill. <br /> Groundwater monitoring continues on a semi-annual basis in accordance with our WDRs. <br /> It appears that laboratory contamination with Acetone continues to be a problem, as it was reported in three of five <br /> ' wells in this second semester. Acetone was not found in the quality control samples, but has been found in <br /> previous events and is identified as a common laboratory contaminant in the WDRs. We have asked our <br /> consultants to investigate this problem. More than 10 percent of the analyses for upgradient well MW-1 have <br /> reported the presence of Acetone, usually also found in quality assurance (QA)samples. <br /> The two new wells (MW-4 and -5)were sampled for the first time this semester, including for Constituents of <br /> Concern (COCs). No volatile organic compounds(VOCs)were reported in those wells; however, trace <br /> concentrations of semi-volatile Di-n-butyl Phthalate were found in both wells and in QA samples (this compound is <br /> also identified as a common laboratory contaminant in the WDRs). A trace concentration of pesticide Fensulfothion <br /> was reported in well MW-5. This compound has previously not been detected in any well. <br /> ' Because of these results and because the next COC monitoring is not scheduled until 2010, we have directed that <br /> all wells be sampled for Di-n-butyl Phthalate and Fensulfothion the next quarter. <br /> Surface water was not available for sampling this semester. The rains of late December did not appreciably affect <br /> the landfill. <br /> If you have any questions, please call me at(209)468-8504. <br /> Sincerely, <br /> ' W. MICHAEL CARROLL, PE <br /> Senior Civil Engineer <br /> ' WMC:sc <br /> N:\1Foothill\Groundwater Mon itori ng\Repts2007\2ndSemO7\2nd Sem071etter.doc <br /> Enclosure <br /> c: Robert McClellon, Environmental Health Department <br /> LA 31610 <br />