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Construction Air Permit media vessel in adsorption operation while the other media vessel is idle or going through its regeneration cycle. During this adsorption cycle, the solid media will adsorb organic siloxane compounds, and much of the other NMOCs that are typically present in LFG. The resulting "clean" LFG will provide fuel for the reciprocating IC engines. After an adjustable length of time, the adsorption media vessels will become saturated and be switched with the standby vessels to allow a regeneration cycle to begin. The maximum regeneration cycle (including warm up and cool down cycle) for one vessel will not exceed %2 of the time of the adsorption cycle,which is expected to be between 24 and 36 hours. The media regeneration system includes electric heater units, air compressors, and associated piping and system controls. During the regeneration cycle, ambient air(about 1,300 scfm at 4 psig)will be heated with an electric heater to approximately 450 'F and purge the media bed of siloxanes and other collected contaminants(primarily VOCs and sulfur compounds). This purge air will contain higher concentrations of organic constituents at the beginning of the regeneration cycle and mostly air at the end of the cycle, and all purge air will be directed to the small enclosed flare for destruction. This variability in the purge air, as the media bed goes through its regeneration cycle, is problematic for source testing since the constituents in the purge air will vary throughout the regeneration cycle. Likewise,the waste gas flare must be designed differently than normal enclosed LFG flares where this type of variability is not encountered. Because extremely low concentration levels of siloxane degrade the reduction efficiency of the back end control equipment, Ameresco will include a second stage siloxane cleaning system called the Fixed Bed Polisher. This system includes two non-regenerative vessels containing activated carbon to remove any remaining organic contaminants before fueling the reciprocating engines. The flare for the SRS regeneration off-gas is an enclosed 30 foot high ground flare firing approximately 100- 200 scfm of LFG at approximately 50%methane to maintain the required destruction temperatures. The flare has a minimum combustion temperature of 1,500 °F (1,500 to 2,100 °F with 1,800 °F nominal), and a minimum residence time of 1.0 second. It is rated at 5.64 MMBtu/hr with an exhaust gas flow rate of 10,653 actual cubic feet per minute (acfm). This flare uses about 68 scfh of propane to ignite. It is equipped with fully modulating air dampeners for primary air mixing. The combustion chamber is round with a cross sectional area of 8.7 square feet and a chamber volume of 261 cubic feet. A process flow diagram of the gas pre-treatment system is provided in Appendix D. S