ARCHIVED REPORTS_2005_3 - Laserfiche WebLink

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The expansion construction project started in August 2003 and covered the southwest corner of the site that includes cells WMU D-00, D-01 and D-02. The expansion project consisted of the following tasks: • Extension of the 18-inch header pipe (above and below ground) • 19 vertical gas extraction wells (average depth 120 vertical feet) • 4-inch lateral piping • Compressed air line • Condensate line • Condensate pump stations • Gas monitoring stations (4 locations) On October 2, 2003 the LFG system expansion was completed and vacuum was applied to the new extraction wells. The wells are now monitored as part of the sites routine LFG collection system operations. All monitoring is conducted in accordance with SJVAPCD regulations and Federal Title V requirements. LFG Monitoring Data Monitoring data (gas concentrations) for the new LFG extraction (monitoring) wells is located in Attachment "A". A copy of the most recent Operations, Monitoring and Maintenance Report prepared by SCS Field Services is located in Attachment"B". Current Compliance Status The new extraction wells are monitored and tuned by qualified technicians to provide the maximum collection efficiency based on operating parameters (methane, oxygen, carbon dioxide & nitrogen). The methane gas concentration in gas monitoring probe GP-9 should be reduced as generated gas is collected by the new LFG system. However, because the monitoring probe (GP-9) is located outside a lined Subtitle D cell, it is likely that the gas has migrated over the anchor trench and cannot be collected by the new LFG extraction system. That is, the HDPE geomembrane in the Subtitle D liner is likely to prevent the new extraction wells from collecting the LFG that has already migrated beyond the cell. (In addition, there is a slight chance that LFG may have migrated beneath the Subtitle D liner from "pre-Subtitle D"portions of the landfill. In either case, the geomembrane will prevent the new extraction wells from collecting the "escaped" LFG.) Therefore, it may be necessary to install temporary extraction wells in soil outside the lined cell to capture this LFG. (These temporary wells will be especially important if the LFG is migrating beneath the Subtitle D liner from older portions of the landfill. If this is occurring, Nve will need to operate the temporary wells for a longer period while installing additional collection wells in older portions of the landfill. Continued monitoring of the new wells and the affected probe is likely to reveal if this is happening.) We would operate these temporary wells only until the monitoring probe is clear, verifying that the "escaped" LFG has been collected. To collect all of this "escaped" LFG, Forward Landfill may need to install some of the temporary wells within 100-feet of the monitoring probe. The Notice and Order prohibits extraction wells within