ARCHIVED REPORTS_2007_9 - Laserfiche WebLink

Home Browse Search

Environmental Consultants 4707 Greenleaf Circle 209 545-8490 and Contractors Suite F FAX 209 545-8391 Modesto,CA 95356 www.scsengineers.com March 27, 2009 File No. 07202055.00 Ms. Christina Carbajal Forward Landfill 0 20109 9999 S. Austin Road E N'V A L T,H Manteca, California 95336 PER- " -s,'-R,V I c-F S Subject: First Quarter 2009 San Joaquin Valley Air Pollution Control District(SJVAPCD) Title V Surface Emissions Testing at the Forward Landfill, Manteca, California Dear Ms. Carbajal: This letter provides results of the January 9,2009, site Title V permit and NSPS landfill emissions monitoring performed by SCS Field Services(SCS) at the subject site. All work was performed in accordance with our current contract. SUMMARY AND CONCLUSIONS On January 9, 2009, surface and/or component emissions testing showed no exceedences of the Title V or SJVAPCD Rule 4642 threshold limit of 500 or 1000 ppmv,respectively. Based on these test results,no additional testing is required at this time. Therefore, the next quarterly surface test event is due by the end of June 2009. BACKGROUND As you know,the Forward Landfill site is an active organic refuse disposal site. By way of background, organic materials buried in a landfill decompose anaerobically(in the absence of oxygen) producing a combustible gas which contains approximately 50 to 60 percent methane gas, 40 to 50 percent carbon dioxide, and trace amount of various other gases, some of which are odorous. The Forward Landfill property contains a LFG collection and flare system to control the combustible gases generated in the landfill. The gases produced in a landfill will either vent vertically to the atmosphere or migrate horizontally through subsurface soil to locations on adjacent properties. If the soil surrounding a landfill consists of permeable materials,there is a greater likelihood that the LFG will migrate to off-site locations. If the methane gas component of LFG is allowed to accumulate in a confined area(i.e.,utility lines, irrigation valve boxes, vaults,basements, wall spaces, etc.) and is exposed to an ignition source, it can be explosive at concentrations between 5 and 15 percent by volume. At higher concentrations,methane is flammable. However, the presence of methane gas in site soil does not mean there is an immediate threat of explosion because flames cannot typically propagate through soil.