RES 702 Draft 01 2006-2008 - Laserfiche WebLink

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It should be noted that the use of cells in the construction of any landfill, and the application of a soil daily cover, was conceived initially, and is intended primarily as a firebreak feature. The goal was to isolate any fire in a single cell. Often, this requires bulk excavation of the landfill waste material to physically separate the "hot" waste from the remaining "fuel"; this ex -situ separation and extinguishment can be costly with associated air emissions difficult to control. Incomplete removal of all burning waste can permit the fire to re -kindle and eventually migrate from one cell to another as long as there is 02 available. Another limitation of bulk waste excavation is that it makes 02 available and can exacerbate the fire. Alternatively, the burning waste may be surgically removed to prevent it from igniting other combustible waste, however this requires knowledge on the precise location of the subsurface fire, which can be difficult to obtain. The incorporation of cells during landfill construction also introduces a limitation on extinguishing fires through in-situ inundation. The cellular structure; i.e., entombment of waste in soil cells, creates discontinuities in the vertical flow regime for water, foam, or any other delivered fire - suppression fluid through the waste mound. Infiltrating fluids are redirected by the soil layers and may circumvent certain cells. Therefore, inundation from the landfill surface is difficult to assure due to the difficulty of delivering fluid to the precise location of the fire. Further, the application of water creates potentially -contaminated leachate. This may not be a significant environmental issue if the resulting fluids are collected, extracted, and properly disposed, but at a site such as the Kailua-Kona Landfill, that does not have an underlying liner and leachate collection system, leachate may discharge directly to the underlying groundwater. In this instance, leachate discharges to groundwater which could itself discharge to the Pacific Ocean would be counter to the state and federal policies on leachate management. The basaltic rock that forms the basement floor and portions of the sidewalls of the landfill exhibits a fractured structure and, further, the intact rock is itself relatively porous. This porosity is supplemented by "lava tubes" formed during deposition that provide open conduits for the exchange of air with the waste in the landfill, as well as the discharge of leachate and groundwater downgradient toward receptors. Injected materials or vertical containment barriers in the vicinity of the lava tubes have been considered to intercept these pathways, but it is expected that these approaches will not significantly reduce the air exchange or water transmission, given the mass porosity of the surrounding rock through both fractures and porous structure. ERM 6 KAILUA-KONA LANDFILL/ 0061204 - 3/14/2008