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Partial Facility Closure Plan for
B-20 Detonation Area
March 1994
Section 6
Development of Corrective Measures Study
The corrective measures study (CMS) is the next logical step in the B-20 area closure sequence after remedial investigation (site characterization) and the baseline RA. The CMS will be undertaken if the remedial investigation establishes the evidence and extent of contamination and the baseline RA determines a potential for unacceptable exposure risks at the site, and hence, the need for remedial actions. The CMS identifies, evaluates, and recommends specific and detailed corrective actions for the closure of B-20 area. Specific objectives of the CMS will be the following:
Based on site conditions, and actual or potential exposure risks, identify appropriate technologies and screen for human health, environmental, institutional and financial criteria.
Based on the technology screening, identify and develop proposed corrective actions. Evaluate these actions for technical feasibility, environmental and human health impacts, regulatory compliance and financial impacts.
Identify and present sufficient information on compliance requirements, and proceed with corrective action design and implementation.
The first step in conducting a CMS will be to identify the site cleanup levels or the closure objective. These are determined by the closure performance standard (section 3.2) and the results of the baseline RA. Also, other regulations and criteria may be applicable in determining the site cleanup levels based on the release nature and location, found during the closure investigation.
The next step in the CMS is to identify appropriate technologies for achieving the site cleanup standards for environmental media of concern. These technologies will be screened based on the site and contamination characteristics, and technology limitations. The technologies that were found during screening to possess severe limitations to reliably achieving the closure objective will be rejected. The remaining technologies will be combined to develop a workable number of corrective action alternatives.
The corrective action alternatives will be evaluated for technical, environmental, human health, regulatory, and institutional, and cost criteria. The technical criteria evaluation will include performance, reliability, implementability, and safety. The environmental criteria assessment will consider the short- and long-term impacts of alternatives and analysis of measures to minimize any adverse environmental impacts. The human health evaluation of alternatives will include reduction of short- and long-term exposure risks based on contaminant type, exposure pathways and target population. The regulatory and institutional criteria will address compliance with applicable regulations and acceptance of corrective actions by the agencies, related institutions and the public. The cost evaluation of each alternative will involve development of cost estimates for implementation, operation and monitoring of alternatives.
Based on the results of alternatives evaluation, the best alternative that will achieve the closure objective will be selected. The basis for the alternative selection will be provided in the form of comparative evaluation of alternatives. The CMS evaluation will also conform to the procedures listed in 31 TAC 335.563. A CMS report will be prepared to present the evaluation process and the findings in accordance with 31 TAC 335.553(b)(3). Based on the findings of the CMS, a corrective action will be chosen, with the approval of the regulatory agencies, for implementation at the B-20 site.
At present, the available information regarding the B-20 site conditions is insufficient to conduct a full CMS, or to completely identify corrective action alternatives. A range of corrective actions may be applicable to the B-20 site. These alternatives range from no action to active remedial actions to reduction of exposure risks to below acceptable levels.
If the baseline RA indicates the residual contamination is at concentration below the concentration which represents acceptable risk, the CMS will recommend no further remedial actions be taken at the site. If the baseline RA indicates limited areas of the site contain contaminants at concentrations above acceptable exposure levels, several remedial actions would be evaluated in the CMS. For instance, if the areas of elevated concentrations are limited and scattered, the areas could be excavated and disposed of offsite. On the other hand, if the elevated concentrations were more extensive, a cap could be constructed over portions of the site. Finally, the most extensive remedial action would be to construct a cap over the entire site. Although preliminary data indicate this extensive remedial action is not necessary, it represents the most conservative preliminary corrective action.
For cost estimating purposes as part of the CMS, a range of corrective action technologies such as institution controls, containment, active treatment and/or removal, and post-closure care will be considered for the B-20 site. Based on the preliminary investigation data, active waste treatment/removal technologies such as excavation and in situ treatment may not be required at the B-20 site. A conservative assumption that a containment technology consisting of RCRA landfill camp along with appropriate institutional controls will be necessary to achieve the closure objective was made solely for the cost estimating purposes for this closure plan.
The actual outcome of the CMS may be different than the landfill cap chosen for this closure plan. The alternatives evaluated in the CMS and the associated cost estimates will be updated to reflect the findings of the actual remedial investigation and baseline RA.