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_.. ` .__ ....... <br />`{ THOMAS M. GAU <br />DIRECTOR. <br />��<tt 3uT�`P <br />FR17Z BUCHMAN <br />DEPUTY DIRECTOR <br />MICHAEL SELLING <br />DEPUTY DIRECTOR <br />STEVEN WINKLER <br />DEPUTY DIRECTOR <br />ROGERJANES February 29, 2012 <br />BUSINESS ADMINISTRATOR <br />Mr. Robert McClellon, Program Coordinator <br />Environmental Health Department <br />600 East Main Street <br />Stockton, California 95202 <br />P. O. BOX 1810 -1810 E. HAZELTON AVENUE <br />STOCKTON, CALIFORNIA 95201 <br />(209) 468-3000 FAX(209)468-2999 <br />mmsigov.org/pubworks <br />SUBJECT: IMPROVEMENT OF PERIMETER LANDFILL GAS MONITORING WELLS <br />AT SAN JOAQUIN COUNTY -OWNED LANDFILLS <br />Dear Mr. McClellon:®r iL <br />{v <br />Thank you and Gino Yekta for your review of our proposed improvement to the perimeter landfill gas <br />migration monitoring wells at San Joaquin County -owned landfills. The improvement (insertion of a <br />small -diameter tube within the existing probe pipes) will greatly reduce the time required for <br />monitoring, increase the reliability of the measurement of the subsurface gas composition, and ensure <br />that combustible gas does not enter the soil of adjacent properties. <br />This letter is written in response tdthe email received February 22, 2012 from Mr. Gino Yekta of <br />CalRecycle's Closure branch which granted approval of our proposed improvements under.certain <br />conditions. We are pleased to meet these conditions, as follows: <br />1. Monitoring is not compromised by the'insertion of the tubes. <br />Monitoring is not compromised. In fact, monitoring will be improved by reducing the amount of <br />air that must be removed from the well to measure subsurface soil gas concentrations. <br />2. We provide "Certification from the Operator/consultant that the new design will function the <br />same way as the original design. <br />I am pleased to provide the certification below. Measurement of the concentration of gasses <br />in the soil will be by the same method as before: bringing a small amount of air to the surface <br />where we use a hand-held instrument to measure gas concentrations. <br />Measurement will be more reliable because the smaller tube means reduced potential for <br />dilution of the subsurface gas by air intrusion and the time required for monitoring, an issue <br />raised by Mr. Yekta. <br />3. If issues are discovered with the new design, the Operator will immediately change to the <br />original design. <br />Yes, if we find problems with this design that cannot be solved, then we will immediately and <br />easily remove the tubes, restoring the probes to their original condition. <br />