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a <br />THOMAS R. FLINN <br />a DIRECTOR <br />4C/FOR�` <br />THOMAS M. GAU <br />DEPUTY DIRECTOR <br />MANUEL SOLORIO <br />Wwk,110, fcrYou <br />DEPUTY DIRECTOR <br />STEVEN WINKLER <br />DEPUTY DIRECTOR <br />December 20, 2007 <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 />11 <br />P. 0. BOX 1810 -1810 E. HAZELTON AVENUE <br />STOCKTON, CALIFORNIA 95201 <br />(209) 468-3000 FAX (209) 468-2999 <br />www.sjgov.org <br />6r:(; 2 4 2007 <br />ENVItR01AIENT HEALTH <br />SUBJECT: CLARIFICATION OF PROPOSED EVALUATION MONITORING PLAN <br />REVISION, CORRAL HOLLOW SANITARY LANDFILL <br />Dear Mr. Del Frate: ,o 1 <br />Thank you for your letter of December 5, 2007, and your time on the telephone Wednesday <br />discussing our proposed approach to the issues at the Corral Hollow Landfill. This letter <br />memorializes that conversation as you asked, and clarifies our letter of November 16, 2007. In <br />that letter the County proposed to adjust the work at the site in recognition of the recent <br />discovery of refuse extending east into adjacent CalTrans property. The refuse at the edge of <br />our property and in CalTrans' property is likely not under the influence of our landfill gas (LFG) <br />collection system, and may be the direct cause of the VOC impact (approximately 10 ppb) at <br />groundwater monitoring well MW -5. Therefore, we proposed to install approximately four new <br />LFG wells within our property to collect LFG from our property and the newly discovered refuse, <br />and to install two additional permanent shallow -aquifer monitoring wells within our property <br />(Figure attached). <br />It is possible that these new LFG wells will mitigate, perhaps even remove, the VOC impact at <br />MW -5. Because of this, I proposed that sampling of soil and soil gas in adjacent properties be <br />postponed until the effectiveness of the increased LFG collection could be accessed. If the <br />water quality markedly improves, then perhaps we will have demonstrated that the "plume" has <br />been removed and our corrective action is successful. In this case, further investigation beyond <br />our property may not be necessary. <br />This approach is consistent with Section 20430 of Title 27 CCR entitled "Discharger -Initiated <br />Corrective Action Program Changes". <br />