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Local governments must dispose of solid waste that is not recyclable, compostable, or considered household hazardous waste. The two primary types of disposal practices are landfilling and municipal waste combustion, or incineration, which may employ conventional techniques or a "waste-to-energy" approach.
Landfill Operation
Local governments often own and operate a solid waste landfill for final disposal of the majority of solid waste generated within the local government's jurisdiction. Solid waste landfills provide an engineered facility for the long term containment of solid waste and include the following activities, including:
· Receiving and depositing solid waste into the landfill
· Controlling disease vector populations
· Managing/monitoring landfill gas production, leachate, and storm water
· Recordkeeping.
Most landfills include a large disposal area that contains numerous smaller cells. Solid waste is deposited in these cells daily, compacted using specially designed bulldozers, and then generally covered with either a thin layer of soil or some alternative cover. The local governments controls the flow of solid waste into the facility to exclude materials such as hazardous waste or other materials that should be managed elsewhere or could be recycled to make the landfill safer and preserve capacity. Once a cell is full it is covered with a final cover designed to limit infiltration and vector populations, and provide a base for cover vegetation.
Local governments must monitor groundwater in close proximity to the landfill and employ a system of pipes that collect methane gas generated as a byproduct of decomposition. Methane gas has been identified as a significant greenhouse gas. Facilities that generate sufficient quantities of methane can recover the landfill gas for use as a source of energy. Storm water runoff associated with landfills may also be regulated under the CWA storm water provisions.
Landfill operations are subject to the minimum criteria for municipal solid waste landfills found at 40 CFR Part 258. These minimum criteria address location restrictions, operating criteria, design criteria, groundwater monitoring and corrective action requirements, closure and post-closure care requirements, and financial assurance criteria. Where a municipal solid waste landfill subject to this rule does not meet these requirements, it is considered an open dump, which is prohibited under §4005 of RCRA.
A local government could be subject to state permit provisions if their state has developed its own solid waste permit program under delegated authority from EPA (61 FR 2584; Jan. 26, 1996). Under the CAA, landfills are subject to air emission guidelines (40 CFR § 60.30c), and EPA is developing NESHAPs emitted from landfills as a long term action. In addition, landfills may be regulated under prevention of significant deterioration (PSD), nonattainment area (NAA) provisions, and new source performance standards (NSPS) programs.
Municipal Waste Combustion
An alternative method of managing solid waste is through combustion. Solid waste combustion involves the incineration of all or a portion of the solid wastestream in specially designed solid waste combustion facilities and the disposal of the residual ash in landfills.
When choosing to employ municipal combustion, local governments can either retrofit existing facilities, build new facilities, or enter into regional partnerships. If they are building new facilities, they must site, design (incorporating elaborate air pollution controls), permit, and construct the combustion facility. Once a combustion facility is in place, the local government must ensure its proper operation, provide a relatively constant flow of waste as a feedstream, and manage and dispose of the residual ash. Most new incinerators have the capacity to recover and reuse the energy released during combustion (the"waste-to-energy" process).
Municipal waste combustion is regulated primarily under the CAA (40 CFR Part 60), which establishes guidelines and standards of performance for municipal waste combustors, as well as standards of performance for incinerators. Regulations under RCRA would only apply if the facility receives and burns hazardous waste. Other CAA regulatory programs to which combustion may be subject are PSD, NAA provisions, NESHAPs, and NSPS.
The disposal of residual ash from the combustion of municipal waste, including fly ash and bottom ash, is regulated under RCRA and state law. Generally, these two types of ash are combined and then disposed in either a municipal landfill or a special ash landfill. Under RCRA, each facility must determine whether the combined ash constitutes a hazardous waste and if so, the ash must be managed as a hazardous waste. Where the ash is not a hazardous waste, it can be managed under state law, which may allow disposal in a solid waste landfill or provide for disposal in an ash monofill (or impose other special requirements).
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