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7 <br /> Environmental Consultants 4707 Greenleaf Circle 209 545-8490 <br /> Suite F Fax 209 545-8391 <br /> Modesto, CA 95356 www.scsengineers.com <br /> June 6, 2006 <br /> File No. 07202055.00 <br /> Ms. Christina Carbajal <br /> Forward Landfill <br /> 9999 S. Austin Road <br /> Manteca, California 95336 <br /> Subject: Operation, Monitoring, and Maintenance of the Landfill Gas (LFG) Migration <br /> Control Facilities at the Forward/Austin Landfill, Manteca, California <br /> Dear Ms. Carbajai: <br /> This letter provides a status report on the operation, monitoring, and maintenance (O&M) work <br /> performed by SCS Field Services (SCS) on the subject system. All activities were performed in <br /> accordance with our approved contract work scope dated February 14, 2003. Below is a summary <br /> of O&M efforts during the period of May 1 through 31, 2006. <br /> Conclusions and Recommendations <br /> As of the dates of our testing, the LFG control facilities appeared to be operating satisfactorily and <br /> generally meeting the operational criteria with the exception of elevated methane gas <br /> concentrations detected at Perimeter Monitoring Probe Nos. GP-11 and GP-12 (up to 12.4 percent <br /> by volume). By May 23, 2006, methane gas concentrations detected at these probes had decreased <br /> to below the LEL in response to system adjustments. Also, on May 15, 2006, SCS performed <br /> monitoring of Temporary Gas Probes, defined as TGP-01 through TGP-39, as directed by the <br /> Client. Results of this monitoring indicated that methane gas concentrations in excess of the LEL <br /> were detected at several locations tested (up to 60.4 percent by volume). Note, that these probes <br /> are intended for evaluation purposes only and are not compliance locations. All LFG extraction <br /> wells were observed to be receiving adequate vacuum and several were adjusted during this <br /> monitoring period. Recommendations regarding repair or maintenance activities may be <br /> contained in subsequent sections of this report. Please advise SCS as soon as possible <br /> regarding implementation of these recommendations. <br /> Background <br /> As you know, the Forward/Austin Landfill site is an active organic refuse disposal site. By way of <br /> background, organic materials buried in a landfill decompose anaerobically (in the absence of <br /> oxygen)producing a combustible gas, which contains approximately 50 to 60 percent methane, 40 <br /> to 50 percent carbon dioxide, and trace amounts of various other gases, some of which are <br /> odorous. The Forward/Austin property contains a system to control the combustible gases <br /> generated in the landfill. <br /> Offices Nationwide <br />