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ral <br />?[ <br />THOMAS R. FLINN <br />DIRECTOR <br />THOMAS M. GAU <br />CHIEF DEPUTY DIRECTOR <br />MANUEL SOLORIO <br />DEPUTY DIRECTOR <br />STEVEN WINKLER <br />DEPUTY DIRECTOR <br />ROGER JANES <br />BUSINESS ADMINISTRATOR <br />January 28, 2008 <br />P. O. BOX 1810 - 1810 E. HAZELTON AVENUE <br />STOCKTON, CALIFORNIA 95201 <br />(209) 468-3000 FAX (209) 468-2999 <br />www.sjgov.org/pubworks <br />DRECOVE, <br />Mr. Todd Del Frate EAlTK <br />California Regional Water Quality Control Board ENVIRONMENT <br />VIRONMENTNT HEAL <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 (CDCs). 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:\1 Foothill\Groundwater Monitoring\Repts2007\2ndSemO7\2ndSemO7letter.doc <br />Enclosure <br />c: Robert McClellon, Environmental Health Department <br />LA 31610 <br />