RES 702 Draft 01 2006-2008 - Laserfiche WebLink

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2.0 EVALUATION OF LANDFILL SUBSURFACE CONDITIONS 2.1 BACKGROUND Post -operations air emissions from the Kailua Kona Landfill have reportedly included low levels of VOCs, including benzene, toluene, ethylbenzene, carbon monoxide (CO), and hydrogen sulfide (H2S) (ATSDR,1994). Other constituents monitored in the emissions from the site include 02, CO2, and CH4, basic atmospheric gases that are tracked to determine possible subsurface fires. However, an active landfill gas management system is not currently operational at the site. Therefore, an analysis of the current condition of the landfill from a physical and chemical perspective is required to assess the nature and extent of landfill emissions, and the potential for subsurface fires within the waste mound. The investigation and monitoring activities should include both existing gas monitoring probes and extraction wells, as well as supplemental, focused subsurface explorations. Critical to this assessment is knowledge of the east -center, north -center and northwest portions of the landfill, which have been identified most recently as areas of concern. Several techniques for subsurface fire suppression have been attempted at the landfill. Smothering the fires, involving eliminating the supply of 02 to the fire source either via soil cover and compaction, cover and leakage repair, and/or the injection of a suppressing gas, such as CO2, has been attempted. None of these previous efforts were performed to an extent or duration necessary to substantially suppress subsurface fires. Excavating the cover material within the landfill waste and flooding burning material with water and/or suppressants such as a fire -retardant foam is a method that has been attempted at other landfill sites with mixed results (TriData, 2002). A version of removing the cover material and burning waste material from a known hot zone, and extinguishing by way of foam flooding is proposed for the Kailua-Kona Landfill to suppress ongoing subsurface fires. If the fire is extensive and temperatures are high, applied water may convert to steam upon contact with the burning waste material, and may limit fire -suppression effectiveness. Large volumes of suppression water could potentially infiltrate to the underlying groundwater aquifer, potentially impacting groundwater quality by leaching contaminants from waste materials. Use of a foam suppression material is less likely to result in contaminant leaching and is believed to be a more environmentally -safe suppression technique. ERM 5 KAILUA-KONA LANDFILL/ 0061204 - 3/14/2008