Environmental Engineering Reference
In-Depth Information
Waste stabilization is specifically included in the NCP as a method of remedying
releases of hazardous materials and controlling release of waste to surface water.
Solidification and encapsulation are mentioned as techniques available for on-site
treatment of contaminated soils and sediments. Under the general requirement to
evaluate all alternatives for remedial action, it will be necessary to evaluate the cost-
effectiveness of S/S systems as applied to specific sites even if the technology is not
selected in the final analysis of remedial techniques. Costs and engineering consid-
erations are critical to these evaluations.
The performance expected from S/S waste must also be assessed as accurately
as possible. Cost estimates must take into consideration future expenditures needed
to maintain the final waste disposal site after response work is complete. The NCP
emphasizes the selection of proven remediation technologies. Examples of success-
ful applications are an important part of any technical evaluation.
Overall guidance on remedial action technologies including a survey of S/S is
provided in a Technology Transfer Handbook by the EPA.
The decision to imple-
ment the S/S option must be preceded by the detailed investigation of many variables.
Both waste and site characteristics must be evaluated to ensure that the S/S alternative
is cost-effective and environmentally acceptable. The USEPA has provided general
guidance on the procedure to be followed in selecting the most appropriate remedial
actions.
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With regard to radioactive waste, 10 CFR Part 61 establishes a waste classifi-
cation system based on the radionuclide concentrations in the wastes. Class B and
C wastes are required to be stabilized, but Class A wastes have lower concentrations
and do not have to be stabilized. Liquid waste, including Class A, requires solidifi-
cation, or absorption into solid media, to meet free liquid requirements. The U.S.
Nuclear Regulatory Commission (USNRC) technical position on radioactive waste
forms was initially developed in 1983. This technical position was revised in 1991,
often referred to as the USNRC Technical Position paper of 1991, with an appendix
specifically addressing cement-stabilized radioactive waste forms. This Technical
Position paper gives the overall objectives of stabilizing radioactive wastes as well
as a list of specific tests and limiting values. These tests are discussed in Chapter 11.
Mixed waste is a hazardous waste as defined by RCRA that contains radionu-
clides. Such wastes must meet the requirements of both USEPA and USNRC for
disposal. Most treatment, storage, or disposal facilities (TSDFs) are licensed for
hazardous waste by USEPA and are not equipped to handle radioactive or mixed
waste. The USNRC licenses facilities for disposal of commercial radioactive waste,
and the U.S. Department of Energy (USDOE) establishes standards and procedures
for disposal of radioactive waste on USDOE sites, usually compatible with USNRC
guidelines. Some overlap occurs among these three government agencies requiring
cooperative agreements for disposing of mixed waste and radioactive waste gener-
ated at U.S. government facilities, not only among the agencies, but also among
state and local governments. For disposing of hazardous waste from these facilities,
the environmental rules and regulations of USEPA, the state, and the local govern-
ments take precedence.
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