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COON AI+ AUI THOMAS R.FLlrIN <br /> DEPARTMENT OF PUBLIZU <br /> KS DEPUTY DIRECTOR <br /> P.O.BOX 1810-g���0 • E <br /> 4Gi F pRe� STO O.IYF bAU1 RNIA 95201 THOMAS M.GAU <br /> (209)468-3000 DEPUTY DIRECTOR <br /> MANUEL LOPEZ FAX(209)468-2999 <br /> DIRECTOR <br /> STEVEN WINKER <br /> DEPUTY DIRECTOR <br /> July 11,2001 <br /> Victor Izzo <br /> California Regional Water Quality Control Board <br /> 3443 Routier Road,Suite A <br /> Sacramento,California 95827 <br /> SUBJECT:FOOTHILL SANITARY LANDFILL MONITORING RESULTS <br /> Dear Mr.Izzo: <br /> The County received your letter dated June 19,2001,regarding first quarter 2001 monitoring results at the <br /> Foothill Sanitary Landfill. The issues discussed in the letter are addressed below. <br /> Issue: The analysis for several wells showed exceedances of the concentration <br /> limits. <br /> Response: Where concentration limits could be established,no exceedances occurred. <br /> For the constituents that concentration limits could not be determined, <br /> further analysis,including the Sanitas®Interwell ANOVA variance and <br /> Intrawell Sen's Slope trend tests,seems to show that these are also not <br /> exceedances. <br /> Issue: Chloride,Nitrate,and Sulfate were over the concentration limits for MW-1, <br /> MW-2,and MW-3. <br /> Response: Concentration limits were not established for chloride,nitrate,and sulfate <br /> because the false positive rate was greater than 5%. As indicated in the first <br /> quarter monitoring report and acknowledged in your letter,an ANOVA test <br /> was performed on these constituents which showed variance. However <br /> further analysis using the Sanitas®Intrawell Sen's Slope/Mann Kendall test <br /> showed no increasing trends in these constituents,and in several cases a <br /> lower mean value in the downgradient wells versus the upgradient well. <br /> Since the ANOVA is not a very powerful test and there are no increasing <br /> trends,the County believes that these are not exceedances,and the wells are <br /> not impacted. <br /> If you have any questions regarding the above responses,please call me at(209)468-3066. <br /> Sincerely, <br /> N E ARIF <br /> Junior Engineer <br /> NZ:vn <br /> N:\MichaeUMGWmon\lst2OOl_reVonsc.wpd <br /> c: Robert McClellon,Environmental Health Division <br /> LA 64201 <br />