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PaU 1 N. <br /> )O'_aeE�.CpG <br /> H ?� THOMAS R. FLINN P.O.BOX 1810-1810 E.HAZELTON AVENUE <br /> STOCKTON,CALIFORNIA 95201-3018 <br /> c... P'• DIRECTOR [�1h (209)468-3000 FAX(209)468-2999 <br /> www.co.san-joaquin.ca.us <br /> THOMAS M.GAU <br /> DEPUTY DIRECTOR <br /> MANUEL SOLORIO Workkg for YOU <br /> DEPUTY DIRECTOR <br /> STEVEN WINKLER <br /> DEPUTY DIRECTOR <br /> April 4, 2006 <br /> ROGER JANES <br /> BUSINESS ADMINISTRATOR <br /> Mr. Todd Del Frate, PG <br /> Central Valley Regional Water Quality Control Board <br /> 11020 Sun Center Drive#200 <br /> Rancho Cordova, California 95670-6114 <br /> SUBJECT: RESULTS OF EXPLORATION TO ASSESS SOURCE OF GROUNDWATER IMPACT AT <br /> THE CLOSED CORRAL HOLLOW LANDFILL <br /> Dear Mr. Del Frate: PIP) <br /> e <br /> Attached please find the Results q f Phase I Investigation to Evaluate Potential Impacts to Groundwater at the <br /> Corral Hollow Sanitary Landfill. This investigation was performed in accordance with the Plan to Evaluate <br /> Impacts to Groundwater as Part of Corrective Action,submitted February 10,2005. <br /> In summary,we found refuse at three exploratory trenches across the drainage ditch west of the eastern landfill <br /> access road. The closure cap was apparent at only one of these locations. Refuse was not found east of that <br /> road. Directing rainwater to the drainage ditch,where it flows over refuse which sometimes is without closure <br /> cap, is probably responsible for the apparent impact to the shallow aquifer as indicated at groundwater <br /> monitoring well MW-5. <br /> A likely corrective action would be to extend the closure cap from its present edge to include the drainage <br /> ditch and a portion of the access road. Such cap extension is best accomplished by the installation of GCL. <br /> Phase 2 exploration,proposed in this report,would determine the edge of the closure cap west of the road, and <br /> the area over which the closure cap would be extended. <br /> Although not initially proposed as corrective action,regrading the drainage ditch to eliminate ponding in <br /> December 2003 seems to have reduced infiltration sufficiently to allow dissipation of the impact seen at MW- <br /> 5. <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:lj <br /> N:\1Corral Hollow\PlanToEvalImpaetToGW\TDelFrateOI-Phase IInvestigResults.doc <br /> Enclosure <br /> c: R. McClellon,Environmental Health Department <br /> LA 21850 <br />