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e <br /> J <br /> -�m <br /> THOMAS M.GAU P.O.BOX 1610-18'10 E.HAZELTON AVENUE{ _ fives <br /> - DIRECTOR. ,.F�,L � .', STOCKTON,CALIFORNIA 95201 <br /> (209)468-3000 FAX(209)468-2999 <br /> tT T-� ;♦ vmv.sjgov.org/pubworks <br /> FRITZ BUCHMAN Working for YOU <br /> DEPUTY DIRECTOR <br /> MICHAEL SELLING <br /> DEPUTY DIRECTOR <br /> STEVEN WINKLER <br /> DEPUTY DIRECTOR <br /> ROGER JAMES 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 /> SUBJECT: IMPROVEMENT OF PERIMETER LANDFILL GAS MONITORING WELLS <br /> AT SAN JOAQUIN COUNTY-OWNED LANDFILLS <br /> Dear Mr. McClellon: <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 t6the 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 />