Guidelines and Procedures for Use in Preparation of the Candidate Site Identification Report

(1) Objective. The principal objective of the Candidate Site Identification Report is to identify at least two, but not more than five, candidate sites that have a high likelihood of satisfying the requirements of 310 CMR 43.41(1). In addition, the report is intended to present the results of a preliminary characterization of the meteorology, surface and ground water, geology, tectonics, geomechanics, air quality, ecology, land use, cultural resources and social and economic characteristics of each such candidate site; a description of the procedure used to identify the candidate sites based on such preliminary characterization; and draft plans for detailed site characterization of each candidate site. Installation of ground water wells is not required for sites which are not selected as candidate sites. The purpose of310 CMR 43.60 is to provide guidance on how, at a minimum, the requirements for technically superior sites should be interpreted and applied in the preparation of this report. (2) Data Collection and Evaluation Protocols. (a) The Candidate Site Identification report should be prepared on the basis ofthe types ofdata sources described at 310 CMR 43.40 and 43.50, additional published and unpublished data and maps and additional field data obtained and technical analysis carried out during this or previous phases of the siting process. (b) All exclusion, conditional consideration and, in the Board's discretion, preference criteria should be applied and evaluated in the preparation of the Candidate Site Identification Report. (c) The Board may continue to use the GIS for data analysis and comparative evaluations of siting factors. Map scales should be employed, if reasonably available, which most accurately depict the characteristic being evaluated. Mapping accuracy should be commensurate with the map scales employed and the accuracy of the data sets. (d) Computer modeling may be used in the site evaluation process for those factors for which computer models are determined to be reliable and valid in prediction, including, but not limited to, generally accepted performance assessment, hydrogeologic and hydraulic models. It is not required that the computer code be specifically developed for low-level radioactive waste management siting provided the code is applicable to the site/facility and the parameter being investigated. Where a code is not generally accepted a determination of reliability and validity should include, but not be limited to the following factors: 1. The model should have supporting documentation that establishes its ability to represent the factors under investigation and any history of its previous applications; 2. The set ofequationsrepresentingthe factor under investigation must be theoretically proven and must be well documented; 3. The numerical solutions must be based on sound mathematical principles and supported by verification and checking techniques; 4. The model must be calibrated against site specific field data developed in accordance with 310 CMR 43.00; and 5. A sensitivity analysis should be conducted to measure the model's response to changes in the values assigned to major parameters, specified error tolerances and numerically assigned space and time discretizations. (e) Conceptual model uncertainty should be addressed by identifying a broad range of conceptual models, and using each in performance assessments. Revisions of these models should be made by accounting for progressive data collected that can be used to eliminate some models from consideration. Uncertainties about the future of the site should be addressed by projecting alternative future site conditions. Parameter uncertainty may be addressed by using Monte Carlo analysis in combination with other techniques (such as Latin Hypercube Sampling) to reduce the computation effort. (f) Despite the efforts to validate models, substantial uncertainties are likely to be encountered in making predictions. Sole reliance on these numerical predictions to determine compliance may not be appropriate; the Board may chose to supplement such predictions with qualitative judgments as well. (g) Any ground water wells that are installed to collect data and evaluate the extent to which the site meets the criteria for a superior site should be installed and maintained in accordance with Department guidance document, Standard Reference for Monitoring Wells, WSC-31-91. (h) In the absence of specific Department policy/guidance documents, the analysis of hydraulic factors necessary to calculate saturated and unsaturated groundwater flow paths including, without limitation, horizontal gradient, hydraulic conductivity, transmissivity, hydraulic head, porosity, geometry, boundary conditions and the time of travel of the flow shall be conducted in accordance with generally accepted standards, principles and protocols, including, without limitation, a pump test performed inaccordance withgenerallyaccepted methods, if appropriate. Where an evaluation of these parameters isdependentuponmeasurementofsoil or water samples the measurement may be done by direct measurement in situ or by the testing of laboratory samples. The use of both methods is highly desirable,but more extensive investigations may be deferred to the Detailed Site Characterization stage. (i) The site characterization activities should be consistent with the guidance set forth at 310 CMR 43.42(1) to the extent that the detail set forth in said guidance is consistent with and applicable to the scope ofa site investigation necessary to conduct a valid preliminarysite characterization. The Board should indicate in its report where further site characterizations are to be deferred to the Detailed Site Characterization stage. In addition to these guidelines the further guidelines of 310 CMR 43.61 and 43.62 should be applied. (j) Where the Board determines that adequate data exists and/or reasonable assumptions can be made on site characteristics, waste characterization and probable facility design, a preliminary performance assessment on likely sites may be conducted. The purpose of the assessments is to assist in the evaluation of how the site will perform by itself and in conjunction with suitable technologies to meet DPH performance objectives. The preliminary performance assessments should be used to estimate factors including, but not limited to: 1. The potential release of radioactivity from waste packages into the facility; 2. The potential release of radioactivity through the engineered barriers into the ambient or geologic environment; 3. The movement of radioactive materials through the environment to humans by ingestion or direct contact; 4. The resulting exposure to humans in comparison to DPH performance objectives and among the sites. (k) Performance assessments need not provide complete assurance that DPH performance objectives will be met. Because of the long time periods which may be involved and the nature of the events and processes of interest, there will inevitably be substantial uncertainties in projecting site and facility performance. What is required is a reasonable expectation based on reasonably conservative assumptions in relation to the record before the Board that compliance with DPH dose performance objectives is reasonably likely to be achieved.