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PgUIN <br /> R O.BOX 1810-1810 E.HAZELTON AVENUE <br /> THOMAS R. FLINN STOCKTON,CALIFORNIA 95201.3018 <br /> DIRECTOR (209)468-3000 FAX(209)468-2999 <br /> r �.. ` cosan-joaquin.w.us . <br /> q��FoaN <br /> THOMAS M.GAU t/ <br /> DEPUTY DIRECTOR Worlftg for YOU� <br /> MANUEL SOLORIO (; <br /> DEPUTY DIRECTOR ��I'f I "11� _ <br /> STEVEN WINKLER L�J <br /> DEPUTY DIRECTOR <br /> BENTON ANGOVE OCT 1 5 2003 <br /> BUSINESS ADMINISTRATOR <br /> October 14, 2003 i=NViROWENT WEALTH <br /> PERMJJ-/SERVICES <br /> Ms. Kim Schwab <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> 3443 Routier Road <br /> Sacramento, California 95827 <br /> SUBJECT: CORRAL HOLLOW SANITARY LANDFILL GROUNDWATER <br /> AND SURFACE WATER MONITORING, THIRD QUARTER 2003 <br /> Dear Ms. Schwab: <br /> Enclosed is a copy of the Third Quarter 2003 Monitoring Report for the Corral Hollow Sanitary <br /> Landfill, submitted in compliance with Waste Discharge Requirements, Order No. 5-01-176. <br /> There were no exceedences of concentration limits this quarter where these limits could be <br /> determined. Concentration limits could not be determined for nitrate and pH at well MW-4 <br /> because of a decreasing trend for pH and an increasing trend for Nitrate. <br /> The decreasing trend in pH at MW-4, the down-gradient well, reflects the decreasing trend in pH <br /> at up-gradient well SB-1 that was indicated by Sanitas for the first time this quarter. Because <br /> both upgradient and downgradient wells appear to be responding to the same influence, and <br /> because we assume that the upgradient well is not influenced by the landfill,we believe it likely <br /> that that the landfill is not affecting pH at well MW-4. However,this will be subject to further <br /> evaluation, as the trend in nitrate at well MW-4 continues to be evident(see below). <br /> Two new wells (MW-6 and MW-7)were installed this quarter to monitor the deep aquifer. The <br /> data from these samples are included in this report. <br /> The work of the Workplan to investigate apparent impact to groundwater at MW-4 is complete, <br /> and the results of the analyses are included in this report. As you know,we were investigating <br /> the possibility that the nitrate detected at MW-4 was from an off-site source. Unfortunately,we <br /> were able to sample the shallow aquifer at one additional location only. Several of our attempts <br /> to sample water were unsuccessful due to the inconsistency of the shallow aquifer and other soil <br /> conditions (details included in this report). We are presently evaluating this data and our <br /> options, and will submit these results and proposed follow-up work in a separate document. <br />