Review of New York State Low-Level Radioactive Waste Siting Process (1996) / Chapter Skim
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6 Potential Sites Identification
6 Potential Sites Identification
Pages 87-125
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From page 87... ...
· Qualitative Map Assessments. These 96 sites were rescreened using 1 exclusionary and 5 preference criteria.
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POTENTIAL SITESIDENTIFICATION 5 Volunteer Sites ~ L FIGURE 6.2 PSI screening process flowchart. 89 10 Candidate Areas GIS Screening 1 96 Sites Map Assessments 4 S tes I 1 51 Sites 1 Field Surveys 1 1 19 Sites - 1 Rescreening _ ~ 5 Potential Sites
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From page 90... ...
As in previous screening steps, cells containing excluded features were eliminated from consideration. The remaining cells were then scored using the preference criteria.3 Based on the distribution of scores 2At this scale, 1 inch on the map is equal to 2,OOO feet on the ground (or 1 centimeter on the map is equal to 240 meters on the ground)
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From page 91... ...
and the need to select a manageable number of sites, the Siting Commission imposed a cutoff score of 3,900 points over a minimum of five contiguous 40-acre cells in an approximately square pattern. A total of 96 sites with scores of 3,900 or higher were identified.
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, were subjected to reconnaissance, or "windshield surveys."4 The purpose of these surveys was to identify changes in the sites since _TABLE 6.2 Criteria Used for Qualitative Map Screening Criterion Number Description 31,35 44a 19 20 49 Proximity to incompatible activities/ nonresident populations Mineral soil groups Drainage Erosion Existing transportation Exclusionary criterion. 4"Windshield surveys`' were conducted by Siting Commission staff from their vehicles; staff did not enter the sites during these surveys.
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These were located in the Allegany, Chenango North, Cortland, Montgomery, and Washington candidate areas (Figure 5.4~. The Siting Commission rescreened these sites by applying the entire set of exclusionary and preference criteria identified in the Siting Plan (Appendix I)
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SITE CHARACTERIZATION During the last step of phase ~ of the screening process (Figure 3.1) , additional field studies were to be undertaken of the five potential sites to further assess their suitability.
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Information gathered and analyzed during site characterization was to provide the necessary data for the Siting Commission to recommend one or more sites for certification. VOLUNTEER AND OFFERED SITES In its Siting Plan the Siting Commission recognized that landowners might "volunteer" land for an LLRW facility.
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was included among the five final potential sites (Table 6.3; Figure 6.~. CONTRIBUTED INFORMATION Following the conclusion of the CAT screening (Chapter 5)
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In their responses to this request, most of the counties criticized the siting process and argued that no potential sites could be found in their candidate areas. The counties believed that the contributed data could be used to exclude their areas from consideration, just as much of the state had been excluded in previous screening steps.
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The Siting Commission responded that a thorough study of ground water would be conducted during the site characterization step if a potential site was identified. SENSITIVITY ANALYSES During GIS Screening, the Siting Commission performed a rudimentary sensitivity analysis to test the importance of three exclusionary criteria (44 mineral soil groups; 17- wetlands exclusion; and 6 reforestation areas)
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The Siting Commission recognized that it could not overcome all opposition to siting, so it decided to concentrate its outreach efforts on less vocal segments of the affected communities. The commission planned to increase its presence in these communities, disseminate information of local concern, improve responses to public questions and comments, and coordinate technical and field activities so that accurate information would be provided.
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One meeting was canceled by Cortland County, and an invitation to meet with the Siting Commission for a site walkover was declined. A meeting of Siting Commission staff and CortIand County officials and technical staff was finally held to discuss technical issues in February 1990.
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ANALYSIS AND DISCUSSION . As noted previously, all 17 exclusionary criteria and 43 preference criteria were applied during PSI screening.
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The Siting Commission macle an implicit and in the committee's opinion, a simplistic-assumption, namely, that uniform geology provides simple or predictable subsurface flow pathways. Flow complexity depends on the distribution of porosity and permeability, which is partly related to rock type and state of deformation and partly to fracture characteristics (spacing, length, interconnectivity, and orientation)
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no LLRW disposal site should be located where there is any indication of dissolution, regardless of disposal methodology. Geologic maps and cross sections of New York show the locations of these potentially soluble rocks both on and below the surface, and the presence of dissolution features can be ascertained through field studies.
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Classification System, that are in active agricultural production. This criterion is based on a system for quantifying the agricultural productivity of soiis.9 The Siting Commission implemented this criterion by excluding sites with more than 5 acres of land in active agricultural use with mineral soil groups 1 through 4.
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Three of the sites contained soils in groups ~ and 2, the most productive agricultural land, and the remaining sites contained soils in groups 3 and 4. Thus, in applying this criterion as it did, the Siting Commission deviated from its previous practices of removing cells that contained any part of an exclusionary feature.
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To some, it may seem counterintuitive to develop an LLRW facility in a. permeable stratigraphic unit through which radionuclide-laden water could "flush" into the water table, but, in fact, permeable and sorptive stratigraphic units, if present, may provide excellent performance as one component of a comprehensive system design.
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The committee's primary concern with the Map Assessments step is that the screening methodology transformed preference criteria into exclusionary conditions. A single negative mark for one of the five preference criteria was sufficient to exclude a site.
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its response to this issue focused on the information that was collected, not on how it was used. The use of the windshield surveys during PSI screening was controversial because of county allegations that information was collected that should have been used to exclude two of the final potential sites (Taylor North and Taylor Central; Table 6.3; Figure 6.11.
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were not the highest-scoring sites. The 5 sites were ranked 1, 5, 6, 7, and 13 for aboveground or belowground disposal and 1, 2, and 4 for mine disposal, based on scoring using the 43 preference criteria.
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One area of particular concern to the committee is the scaling factors used in scoring the sites. Scaling factors for most of the preference criteria used in this step of screening were assigned values of 1, 3, or 5 according to the conditions at the site, but there were several exceptions.
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T81. From its own analysis, the committee believes that the Siting Commission's decision to include the Taylor North site in the final list of five potential sites was inconsistent with the commission's requirement that an offered site must be "at least as good as" other sites.
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it is important to recognize that the commission had considerable flexibility in the interpretation and implementation of the preference criteria used in PST screening. Thus, a detailed sensitivity analysis would have been useful for assessing the sensitivity of the siting decision to these criteria.
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Table 6.5 utilizes the entire set of preference criteria employed at the final stage of PSI screening. The Siting Commission did not use a cutoff score for this screening step.
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Weighta # 1 Scaling Factor for Scenarios #2 #3 #4 #5 #6 #7 #8 Known Quantities Distance from mines (7) Surface water features (13)
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to the maximum score using the complete set of preference criteria (maximum score = 5,000 when siting factor = 5 for all criteria) , as documented in the ROPSI (p.
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Subtotal Criterion Scaling Factor for Scenarioa Weights# 1 #2 #3 #4 #5 #6 #7 #8 20 40 30 30 25 20 15 20 20 10 10 10 20 10 5 1 5 3 20 1 10 1 10 1 15 1 15 1 360 370 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 S 15 15 15 15 11 11 33 11 11 11 11 11 370810 S 1 1 1 1 1 1 1 1 1 1 3 3 1 1 1 1 11 11 11 15 1 3 11 11 11 370370814 5 5 5 1 5 1 5 1 5 , 1 5 1 5 1 5 1 5 5 is Uncertain Quantities Geologic complexity (1) 45 1 1 1 5 5 5 1 5 Seismic h~ds(2)
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5511155515 Unconsolidated stratigraphic units (14) 4011155515 Erosion (20)
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Most notably, preference criteria scored using "uncertain quantities" continue to play a significant role in PST screening, indicating that there may be a weak correlation between the final score and the suitability of a site for an LLRW disposal facility. The use of a lower cutoff score for GIS Screening in PSI (3,900 points)
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Rescreening with the full set of preference criteria addressed a large number of socioeconomic issues. Socioeconomic criteria included Criteria 27, 31, 33, 34, 35, 45, 4B, 52, 53, 54, 55, 56, 59, 60, and 61 (see Table T.21.
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Although a cutoff score was not used at this stage, the five selected potential sites had scores in the range of 3,585 to 4,125 points. As shown by Scenario 7 in Table 6.5, it would be possible to attain a score of 3,585 and still receive unfavorable scores on most of the performance-related criteria.
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In addition, the Siting Commission did not do the kinds of sensitivity analyses that would have identified the degree to which its actual choice of sites was shaped by factors having little to do with the probable safety or performance of the site. SUMMAlRY The purpose of the PSI process was to screen the 10 candidate areas in 4 discrete steps in order to identify a limited number of potential sites for an LLRW disposal facility.
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Screening Criteria All 17 exclusionary and 43 preference criteria were applied during PSI screening. The committee identified problems with several of these criteria, some of which are discussed in Chapter 5.
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The primary technical problem with this screening step is that it treated preference criteria as exclusionary conditions in that a single unfavorable mark on any one of five preference criteria was sufficient to eliminate a site from consideration. Additionally, there appeared to be little attempt by the Siting Commission in selecting sites for further screening to assess whether each site's limitations outweighed its positive attributes, as determined by using the preference criteria.
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The sensitivity analysis undertaken by the Siting Commission was of limited value because it was directed largely at criteria that were specified by law or regulation. The Siting Commission had considerable flexibility in the implementation of preference criteria at this stage of screening.
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The next screening step would apply performance criteria that are related most strongly to licensing and site performance, using a cutoff score selected to meet the desired area goal. Subsequent screening steps would apply those socioeconomic factors that are less strongly related to site performance in some logical and defensible order.
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