Hazardous waste may be sequestered in a hazardous waste landfill or permanent disposal facility. “In terms of hazardous waste, a landfill is defined as a disposal facility or part of a facility where hazardous waste is placed or on land and which is not a pile, a land treatment facility, a surface impoundment, an underground injection well, a salt dome formation, a salt bed formation, an underground mine, a cave, or a corrective action management unit” (40 CFR 260.10).
Final Disposal of Hazardous Waste
Historically, some hazardous wastes were disposed of in regular landfills. This resulted in unfavorable amounts of hazardous materials seeping into the ground. These chemicals eventually entered to natural hydrologic systems. Many landfills now require countermeasures against groundwater contamination. For example, a barrier has to be installed along the foundation of the landfill to contain the hazardous substances that may remain in the disposed waste. Currently, hazardous wastes must often be stabilized and solidified in order to enter a landfill and must undergo different treatments in order to stabilize and dispose them. Most flammable materials can be recycled into industrial fuel. Some materials with hazardous constituents can be recycled, such as lead‐acid batteries.
EXAMPLE 4.21
Land Disposal Daily Cover
Landfill‐DNR asks: How much material do we need for daily cover for our proposed hazardous waste landfill? How much of our total volume (air space) will be used as the daily cover during the life of the landfill? How much longer could the landfill be used if daily cover were not employed? The landfill is 500 m × 250 m in average plan and 15 m high. Daily filling rates are 15 m × 10 m × 2 m and the daily cover is 0.3 m.
SOLUTION
The total landfill air space is
Each daily layer (lift) has a volume of
The daily cover has a volume of
The volume of air space (in percent) used by daily cover is
The life of the landfill with daily cover is
The life of the landfill without daily cover is
Therefore, the landfill life will be extended by
Industrial Waste Generation Rates
Industrial waste is the waste produced by industrial activity which includes any material that is rendered useless during a manufacturing process such as that of factories, industries, mills, and mining operations. It has existed since the start of the Industrial Revolution. Some examples of industrial wastes are chemical solvents, pigments, liquid waste and sludges, metals, plastic, ash, paints, sandpaper, paper products, industrial by‐products, electronic waste, metals, glass, and radioactive wastes.
Given the shortcomings in the available data, it is clear that there are significant uncertainties in the United States estimates of industrial waste generation. Because there is no single source of data on waste generation that is truly comprehensive, trying to develop a national picture of industrial waste generation is much like trying to develop a picture of an elephant by having a dozen blindfolded people touch different parts of the animal. Some waste databases touch the tail, other the trunk, only a few touch the main body of the elephant.
The best estimates available from national waste generation data indicate that more than 12 billion T of combined industrial waste are generated in the United States annually. Only 800 million T, or less than 10% of this waste mass, are defined as hazardous under RCRA. Based on EPA data from sources such as the Biennial Report System, the Toxic Chemical Release Inventory, and the National Survey of Hazardous Waste Generators, more than 25 000 generators of hazardous waste can be identified. The precise number of generators of hazardous waste is subject to considerable uncertainty, due to definitions of hazardous waste and reporting limits that vary from inventory to inventory and from state to state. Despite the uncertainties, it is clear that there are tens of thousands of industrial hazardous generators in the United States producing 300–800 million T of hazardous waste annually. The large uncertainty in the amount of waste generated is again due to differing definitions.
Generator Requirements and Responsibilities
Generators of hazardous waste are the first link in the cradle‐to‐grave chain of hazardous waste management established under RCRA. The regulatory requirements for hazardous waste generators include (USEPA 1986) the following:
- Obtaining an EPA identification (ID) number
- Handling of hazardous waste before transport
- Manifesting of hazardous waste
- Record keeping and reporting
Generators are responsible for determining whether the wastes they generate are hazardous and, if so, for managing them in with 40 CFR 261.20‐261.24. Determine if materials are hazardous wastes involves classifying them as waste, ensuring they are not excluded from RCRA regulations, and evaluating them for the hazardous properties outlined in the regulations.
The USEPA recognized that hazardous waste regulations would impose a substantial burden on small generators if they were brought entirely within the Subtitle C regulatory system. Thus, the EPA has exempted small‐quantity generators from most hazardous waste requirements. The EPA defines generators as follows:
- Large‐quantity generators (LQGs) are those facilities producing more than 1000 kg of hazardous waste per calendar month (about 2200 lb). LQGs have permit to store hazardous waste in 55‐gal drums on‐site and keep them on‐site for 90 days or less (may be extended by regulator).
- Small‐quantity generators (SQGs) are those facilities producing more than 100 kg but less than 1000 kg of hazardous waste per calendar month. SQGs may store hazardous waste in 55‐gal drums and keep them on‐site for 180 days or less; if a disposal site is over 200 miles away, up to 270 days.
- Conditionally exempt small‐quantity generators are those facilities producing less than 100 kg of hazardous waste or less than 1 kg of acutely hazardous waste per calendar month. The requirements for this category additionally limit the facility’s waste accumulation to less than 1000 kg of hazardous waste, 1 kg of acute hazardous waste, or 100 kg of any residue from the cleanup of spill of acutely hazardous waste at any time.
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