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0 0 TECHNICAL MEMORANDUM Evaluation of Bed Ash Disposal Forward Landfill San Joaquin, California November 1, 2016 Page 4 Figure 1 (these disposal areas total about 45 acres). Although uniform distribution is judged to be unlikely and it is possible that thicker layers are present, it is doubtful that the locations of pockets of bed ash at different depths within the total 45-acre disposal area could be identified by drilling, geophysical, excavation, or other means. Therefore, selective excavation of the bed ash is not feasible. Because selective excavation is not feasible, virtually all the 1.68 million tons of co-disposed refuse could require excavation to remove the 2,431 tons of bed ash.2 Excavation, transportation, and off-site disposal of this quantity of material may reasonably be assumed to be infeasible based on costs and potential environmental impacts. For example: • Data from three partial to complete non-hazardous waste landfill clean closures in California indicated costs that ranged from$21/cubic yard(yd 3)to$57/yd3 for excavation, transportation, off-site disposal, engineering, and monitoring. Although actual costs would be very site-specific and a cost estimate has not been developed for the Forward Landfill, the information indicates removing 1.68 million tons of waste from the landfill and disposing it offsite at a Class I landfill would be on the order of tens of millions of dollars or more; • Offsite disposal of 1.68 million tons of waste could require on the order of 67,000 truckloads and more than 21 million roundtrip vehicle miles assuming a hauling capacity of 25 tons per truck and disposal at the Kettleman Hills Landfill (the closest Class I landfill to Forward Landfill); • Refuse excavation of this magnitude in an active solid waste facility would likely require portions of the landfill gas system to be removed from service during the work. This would increase the potential for subsurface gas migration,would require a large quantity of water to manage dust and odors, and would increase air emissions and odors associated with landfill operations; and • Open excavations would appreciably increase the potential for subsurface fires by allowing oxygen access to the waste mass. z Depending on depths of burial,the total amount of excavation could exceed 1.7 million tons due to excavation slope requirements.