Exempt waste, disposal

Under the RCRA exemption, wastes intrinsically associated with the exploration and development of oil and gas do not have to follow Subtitle C regulations for disposal. Under Subtitle C, hazardous wastes must follow strict guidelines for storage, treatment, and transportation and disposal. The cost of handling materials under the Subtitle C scenario is overwhelming. Under the exemption, the operator is allowed to dispose of wellsite waste in a prudent manner and is not obliged to use licensed hazardous waste transporters and licensed Treatment, Storage, and Disposal Facilities (TSDF). 

Exempt wastes are usually disposed of on location following permission from the state oil and gas division. Liquid wastes, if not evaporated or fixated on location, are usually injected into Class II injection wells—refer to Chapter 6, Environmental Considerations. Solid wastes, if not acceptable to local landfills, are remediated onsite or buried in some instances. Table 4-175 shows exempt and nonexempt waste [234]. 

Pit sludges and contaminated bottoms from storage or disposal of exempt waste... 

Given the complexity of the problem of selecting a safe, effective waste disposal strategy from the relatively sophisticated array of disposal systems that are available, and given the RCRA farmer s exemption, there needs to be a way of providing disposal Information directly to the pesticide user. One such method would be to put It on the label. 

Exempt waste any waste containing hazardous substances that is generally acceptable for disposition as nonhazardous material (e.g., disposal in a municipal/industrial landfill for nonhazardous waste). 

Waste that exceeds concentration limits for exempt waste would be classified as low-hazard if it poses no more than an acceptable (i.e., barely tolerable) risk to a hypothetical inadvertent intruder at a dedicated near-surface disposal facility for hazardous wastes, with the important condition that an acceptable risk or dose used to determine low-hazard waste should be substantially higher than a negligible risk or dose used to determine exempt waste. 

Exempt Radioactive Wastes. The radioactive waste classification system in the United States does not include a general class of exempt waste (see Table 1.1). Rather, many products and materials that contain small amounts of radionuclides (e.g., specified consumer products, liquid scintillation counters containing 3H and 14C) have been exempted from requirements for use or disposal as radioactive material on a case-by-case basis. The various exemption levels are intended to correspond to low doses to the public, especially compared with dose limits in radiation protection standards for the public or doses due to natural background radiation. However, the exemption levels are not based on a particular dose, and potential doses to the public resulting from use or disposal of the exempt products and materials vary widely. 

The classification system lacks a set of principles for determining when a waste contains sufficiently small amounts of radionuclides that it can be exempted from regulatory control as radioactive material. The lack of a general class of exempt waste increases in importance as the resources required for management and disposal of radioactive waste increase compared with the resources required for management and disposal of these materials as nonradioactive waste, and it may foreclose possible beneficial uses of slightly contaminated materials. 

As part of this study, proposed radioactive waste classification systems that differ from the existing classification system in the United States were reviewed and evaluated. Of particular interest is the classification system currently recommended by the International Atomic Energy Agency (IAEA). This classification system and the disposal options for each waste class are summarized in Table 1.2. The basic waste classification system consists of exempt waste, low-and intermediate-level waste, and high-level waste. 

The basic waste classification system includes a general class of exempt waste, which is defined in terms of a dose to an individual member of the public, resulting from waste disposal, that is regarded as negligible. 

The similarities are of the following kinds. First, neither classification system includes a general class of exempt waste. Second, neither classification system is comprehensive, because the classification system for radioactive waste distinguishes between fuel-cycle and NARM waste and the classification system for hazardous chemical waste excludes many potentially important wastes that contain hazardous chemicals. Third, any waste must be managed and disposed of in a manner that is expected to protect public health and the environment. In addition, the approach to disposal of hazardous chemical waste under RCRA, which emphasizes monitoring of releases from disposal facilities and an intention to maintain institutional control over disposal sites for as long as the waste remains hazardous, is applied to disposal of uranium or thorium mill tailings under AEA. 

Technical requirements on treatment and disposal of spent fuel, high-level waste, and transuranic waste established under AEA should be largely unaffected by the presence of waste classified as hazardous under RCRA Some of these wastes meet technology-based treatment standards for hazardous chemical waste established by EPA (e.gvitrified high-level waste is an acceptable waste form under RCRA). Alternatively, a finding that disposal of the radioactive component of the waste complies with applicable environmental standards established by EPA under AEA can serve to exempt the disposal facility from prohibitions on disposal of restricted hazardous chemical wastes under RCRA [e.g., disposal of mixed transuranic waste at the Waste Isolation Pilot Plant (WIPP)]. 

The definition of exempt waste requires further elaboration. Although this Report is concerned with classification of waste for purposes of disposal, NCRP recognizes that some materials that contain only low concentrations of regulated hazardous substances may have beneficial uses if they could be exempted from regulatory control as hazardous material. 

Thus, NCRP intends that exempt waste could be used or disposed of in any manner allowed by laws and regulations addressing disposition of nonhazardous materials. However, waste that would be exempt for purposes of disposal would not necessarily be exempt for purposes of beneficial use as well. Exemption of materials that contain hazardous substances to allow beneficial use also should be based on considerations of health risks to the public. However, limits on the amounts of hazardous substances that could be present in exempt materials intended for a particular beneficial use could be substantially lower than the limits for disposal as exempt waste, due to differences in exposure scenarios for the two dispositions, and disposal may be the only allowable disposition of some exempt materials based on considerations of risk. In addition, exempt materials may consist of trash, rubble, and residues from industrial processes that have no beneficial uses and must be managed as waste. 

Based on these considerations and the purpose of this study, disposal is the only disposition discussed in developing recommendations on exemption of waste that contains small amounts of hazardous substances based on risk. Consideration of dispositions of exempt materials other than disposal as nonhazardous waste is beyond the scope of this study. However, the principles used in this Report to define exempt waste based on risk also could be used to define exempt material for any other purpose. 

NCRP recommends that risks to hypothetical individuals at waste disposal sites should be evaluated in classifying waste, as described in the following section, and that the risk to an individual that arises from disposal of any hazardous substance be expressed in the form of a dimensionless risk index (RI). The risk index for the ith hazardous substance (Rid is defined in terms of the risk that arises from disposal of that substance relative to a specified allowable risk for an assumed type of disposal system (e.g., municipal/industrial landfill for disposal of exempt waste) as ... 

Exempt Waste. Waste classified as exempt would be regulated as if it were nonhazardous, and would be generally acceptable for disposition as nonhazardous material (e.g., disposal in a municipal/ industrial landfill). As noted in Section 1.4.1, disposal is the only disposition of exempt materials considered in this Report. Limits on concentrations of hazardous substances in exempt waste would be derived based on an assumption that the risk or dose to a hypothetical inadvertent intruder at a disposal site should not exceed negligible levels. The use of a negligible risk or dose to determine exempt waste is based on an assumption that a disposal facility for nonhazardous waste could be released for unrestricted use by the public soon after the facility is closed. 

Disposal facilities for nonhazardous waste (e.g., municipal/indus-trial landfills) normally are constructed without substantial engineered barriers, such as a rock cover or cement waste forms, that would deter inadvertent intrusion into waste, and the waste itself often is in a readily accessible physical form. Therefore, in determining exempt waste, scenarios for inadvertent intrusion involving permanent occupancy of disposal sites and normal human activities that could access waste would be appropriate. Examples include excavation in the construction of homes and permanent residence on... 

The assumed disposal systems for exempt waste and low-hazard waste both involve near-surface disposal, and either type of waste often would be emplaced sufficiently close to the surface that inadvertent intrusion into the waste could occur as a result of normal human activities. However, there are differences in the two types of disposal systems that should be taken into account in developing appropriate scenarios for inadvertent intrusion. Disposal facilities for low-hazard waste frequently include engineered barriers to deter inadvertent intrusion, impenetrable waste forms, or deliberate emplacement of more hazardous wastes at locations where access to the waste during normal human activities would be less likely. Most importantly, as noted previously, current plans call for institutional control to be maintained over hazardous waste disposal sites for a considerable period of time after facility closure, which allows for substantial... 

In developing generic scenarios for inadvertent intrusion into near-surface disposal facilities used to determine limits on concentrations of hazardous substances in exempt and low-hazard waste, consideration must be given to the question of how far into the future the scenarios should be applied, as well as the earliest time at which the scenarios could occur. This issue arises because the potential risk posed by some radionuclides e.g., uranium) increases with time, due to the long-term buildup of radiologically significant decay products, and some hazardous chemicals could be transformed over time into more hazardous forms. NCRP believes that scenarios for inadvertent intrusion used to classify waste should be applied over a time period consistent with the time period for applying standards for protection of members of the public beyond the boundaries of waste disposal sites. 

The risk index for any hazardous substance in Equation 1.1 or 1.2 (see Section 1.5.1) is calculated based on assumed exposure scenarios for hypothetical inadvertent intruders at near-surface waste disposal sites and a specified negligible risk or dose in the case of exempt waste or acceptable (barely tolerable) risk or dose in the case of low-hazard waste. Calculation of the risk index also requires consideration of the appropriate measure of risk (health-effect endpoint), especially for carcinogens, and the appropriate approaches to estimating the probability of a stochastic response per unit dose for carcinogens and the thresholds for deterministic responses for noncarcinogens. Given a calculated risk index for each hazardous substance in a particular waste, the waste then would be classified using Equation 1.3. 

The waste classification system presented in this Report would apply to all radioactive and hazardous chemical wastes from any source, and it would be based on considerations of health risks to the public that arise from waste disposal. The recommended classification system differs from the existing waste classification systems in three respects radioactive and hazardous chemical wastes would be included in the same classification system all waste would be classified based on its properties, rather than its source and the classification system would include a general class of exempt waste. 

Many details would need to be considered in developing a new waste classification system based on the framework presented in this Report. Assumptions about generic scenarios for exposure of hypothetical inadvertent intruders at waste disposal sites to be used in classifying waste and the time frames for applying the scenarios would be required. Decisions would need to be made about negligible and acceptable (barely tolerable) doses or risks that would be used in classifying waste as exempt or low-hazard, respectively. 

In addition to the exemptions established in regulations, NRC issued guidance on concentration limits for disposal of residual thorium or uranium from past operations with no restrictions on burial method (NRC, 1981). There wouldbe no restrictions on burial method if the concentrations were less than (1) 0.4 Bq g 1 for natural thorium or uranium with its decay products present and in activity equilibrium, (2) 1.3 Bq g 1 for depleted uranium, and (3) 1 Bq g 1 for enriched uranium. These concentration limits were intended to provide criteria for remediation of contaminated sites to permit unrestricted use by the public, but they could be applied to waste disposal as well. 

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