6
Potential Sites Identification

The Potential Sites Identification (PSI) step of the screening process (Figure 3.1) was described in the September 1989 Siting Commission's Report on Potential Sites Identification (ROPSI), which was published about 10 months after the Siting Plan itself (see Table 2.1). The report was published as part of New York State's effort to meet the January 1, 1990, milestone set by the 1985 Amendments Act (Table 2.1) so that waste generators in New York could retain access to disposal sites in other states. The objective of this screening step was to identify a small number of potential sites for a low-level radioactive waste (LLRW) disposal facility from among the 10 candidate areas identified in Candidate Area Identification (CAI) screening (Chapter 5). The PSI process involved detailed screening of the candidate areas, limited field observations at individual sites, and comparative evaluations. It resulted in the selection of five potential sites (Figure 6.1).

PSI screening involved four discrete activities, each involving the application of a different combination of exclusionary and preference criteria (Figure 6.2):

  • Geographic Information Systems (GIS) Screening. The 10 candidate areas were screened using 13 exclusionary and 27 preference criteria to identify 96 sites, which ranged in area from one-half to several square miles.
  • Qualitative Map Assessments. These 96 sites were rescreened using 1 exclusionary and 5 preference criteria. A total of 51 sites were selected.
  • Field Surveys. Limited field inspections (''windshield surveys'') were performed on these 51 sites and 4 other "offered" sites1 to identify unfavorable conditions. A total of 19 sites were selected for further review.

1  

These sites were offered to the Siting Commission as possible host sites for an LLRW disposal facility by the landowners. These sites are discussed in more detail later in this chapter.



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--> 6 Potential Sites Identification The Potential Sites Identification (PSI) step of the screening process (Figure 3.1) was described in the September 1989 Siting Commission's Report on Potential Sites Identification (ROPSI), which was published about 10 months after the Siting Plan itself (see Table 2.1). The report was published as part of New York State's effort to meet the January 1, 1990, milestone set by the 1985 Amendments Act (Table 2.1) so that waste generators in New York could retain access to disposal sites in other states. The objective of this screening step was to identify a small number of potential sites for a low-level radioactive waste (LLRW) disposal facility from among the 10 candidate areas identified in Candidate Area Identification (CAI) screening (Chapter 5). The PSI process involved detailed screening of the candidate areas, limited field observations at individual sites, and comparative evaluations. It resulted in the selection of five potential sites (Figure 6.1). PSI screening involved four discrete activities, each involving the application of a different combination of exclusionary and preference criteria (Figure 6.2): Geographic Information Systems (GIS) Screening. The 10 candidate areas were screened using 13 exclusionary and 27 preference criteria to identify 96 sites, which ranged in area from one-half to several square miles. Qualitative Map Assessments. These 96 sites were rescreened using 1 exclusionary and 5 preference criteria. A total of 51 sites were selected. Field Surveys. Limited field inspections (''windshield surveys'') were performed on these 51 sites and 4 other "offered" sites1 to identify unfavorable conditions. A total of 19 sites were selected for further review. 1   These sites were offered to the Siting Commission as possible host sites for an LLRW disposal facility by the landowners. These sites are discussed in more detail later in this chapter.

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--> Figure 6.1 Map of New York State showing the five potential sites, with the candidate areas  included for reference. Source: ROPSI.

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--> Figure 6.2 PSI screening process flowchart.

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--> Rescreening Using All Criteria. These 19 sites were rescreened using all 17 exclusionary and 43 preference criteria defined in the original siting plan (Appendix I). Five potential sites were selected. Table 6.1 shows the land areas of the state that were eliminated using the exclusionary criteria in the various steps of PSI screening. Shortly before the Siting Commission issued the ROPSI, it issued the Disposal Method Screening Report (1989a), which ruled out the use of vertical shaft mines for disposal. Consequently, drift mine disposal was the only underground storage method under consideration during PSI. At this time, the Siting Commission screened areas and sites for both aboveground or belowground methods and for drift mine disposal. GIS Screening GIS Screening was carried out at a scale of 1:24,000,2 which represented about a 10-fold increase in resolution from CAI screening. A grid consisting of 40-acre areas, or cells, was imposed on each of the 10 candidate areas identified through CAI screening. Each of the cells was evaluated using all of the exclusionary and preference criteria applied during CAI screening, in combination with an additional set of two exclusionary and six preference criteria. A list of these criteria is given in Appendix I. It is important to note that this group of criteria was significantly smaller than the full set specified in the original Siting Plan. Many of the socioeconomic criteria and a few of the performance criteria were not applied in this step of screening. 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 2   At this scale, 1 inch on the map is equal to 2,000 feet on the ground (or I centimeter on the map is equal to 240 meters on the ground). 3   In this screening step, scores were calculated in a different way than in previous steps. In particular, the weights of the preference criteria were not normalized to 1,000 before composite scores were calculated. Instead, composite scores were calculated using the "raw" weights shown in Table 1.2, and the composite scores were then normalized to

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--> TABLE 6.1 Lands Excluded During PSI Screening (after New York State Siting Commission, 1993, p. 4-6, table)   Acres Excluded Percentage of State Excludeda Criterion Aboveground/ Belowground Mines Aboveground/ Belowground Mines 6 105,100 105,100 0.33 0.33 11 2,120 2,120 < 0.01 < 0.01 15 12,320 — 0.04 — 16 169,200 169,200 0.53 0.53 17 140,680 — 0.44 — 28 5,840 5,840 0.02 0.02 32 2,320 2,320 < 0.01 < 0.01 36 3,800 3,800 0.01 0.01 38 26,720 26,720 0.08 0.08 41 600 600 < 0.01 < 0.01 44 170,300 170,300 0.54 0.54 57 1,280 1,280 < 0.01 < 0.01 Totalb 463,360 404,800 1.46 1.28 a Percentages computed using 31,728,640 acres as the area of the state of New York. b Total is less than the sum because of mutually exclusive conditions. 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.     5,000 points. Except for rounding differences, this method should yield results identical to those obtained by normalizing the weights.

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--> Qualitative Map Assessments The 96 sites were rescreened qualitatively using criteria that could be evaluated on the basis of map data (Table 6.2). For each of these criteria, the sites were assigned qualitative scores of "+," "0," or "-." These scores were then aggregated, and an overall rating was applied as shown below: A:   A site received no more than one 0 score and no-scores. B:   A site received more than one 0 score and no-scores. C:   A site received at least one-score. Sites that received an A or B rating and that were at least 400 acres in size were selected for further analysis. Field Surveys The 51 sites selected by Map Assessments screening, and 4 additional sites offered by private landowners (see discussion later in this chapter), 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 Proximity to incompatible activities/ nonresident populations 44a Mineral soil groups 19 Drainage 20 Erosion 49 Existing transportation a 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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--> collection of the GIS data, to observe current land use, and to look for obvious exclusionary features. The sites were evaluated first for characteristics such as wetlands, soils, geologic complexity, erosion, mineral resources, and proximate incompatible activities. Some of these criteria were duplicative of criteria used in the Map Assessments step (Table 6.2). Aerial photos were used to augment field observations (e.g., of heavily wooded or otherwise inaccessible areas). Supplemental technical information provided by local government units also was used in some cases (see discussion later in this chapter). A team of geological and mining experts performed an additional survey at selected sites being considered for the drift mine disposal method. Local geologists (not Siting Commission staff) also made a series of selected site visits. The details of this screening step (e.g., what combinations or levels of unfavorable conditions would exclude a site) were not described fully in the ROPSI. Based on this procedure, the Siting Commission excluded 16 of the 55 sites. The remaining sites were then rescreened using the following criteria: drainage, presence of hydric soils, ground water discharge within the site, presence of nonresident populations, and slopes that were too steep for aboveground or belowground methods and too shallow for drift mines. This evaluation eliminated an additional 20 sites. Again, the basis for making site selections, or for excluding sites, was not discussed fully in the ROPSI. Rescreening Using all Criteria Field screening reduced the number of potential sites to 19. 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). 5 The ROPSI summarizes the results of this screening as follows (p. 9-1): 5   The Siting Commission never applied criterion 9, a preference criterion relating to existing mines, because existing mines were excluded before this criterion had been used.

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--> As a result of the comparative assessments described in the previous sections, staff concluded that many of the 19 sites appeared to be technically excellent and had a high potential for ultimately being found suitable for certification and licensing as a low-level radioactive waste disposal facility. Nevertheless, in moving forward into the next phase of the siting process, staff also recognized that schedule and cost constraints dictate that attention must be focused on a limited number of sites that appear most suitable. For these reasons, five sites with greatest potential, in staffs judgment, are recommended; the others would be set aside along [with] the sites previously considered. Thus, 14 of the 19 sites were set aside by a staff decision, leaving 5 potential sites for further study (Table 6.3; Figure 6.1). Although in the ROPSI the Siting Commission describes some of the factors considered in making this decision and provides some explanation for why 14 areas were set aside, the details of the screening and the basis for the selection of the 5 potential sites are not described. Site Characterization During the last step of phase 1 of the screening process (Figure 3.1), additional field studies were to be undertaken of the five potential sites to further assess their suitability. These studies were to have included limited drilling and surface assessments. As noted in Chapter 3, however, the screening process was halted by the governor before these investigations could be initiated. Once these field studies had been completed, at least two sites were to be identified for more detailed characterization. Full site characterization was to last at least a year to allow technical experts to observe changes at the sites over an annual cycle. Studies were to address geology, ground and surface water conditions, weather patterns, plants and animals, population, land use, archeological and cultural resources,

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--> TABLE 6.3 Final Potential Sites (after ROPSI, Table S-1) Site Name County Town(s) Size (Acres) Taylor Central Cortland Taylor 473 Taylor North Cortland Taylor 686 West Almond Allegany West Almond 918 Caneadea Allegany Caneadea, Allen 1,039 Allen Allegany Allen 780 Total     3,896 transportation, and other natural and human features of the sites. 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. The Siting Plan indicated (pp. 2-5 and 2-6) that such volunteers will be subject to the same technical and regulatory requirements applicable to other areas and sites. . . . An assessment will be performed first against statewide exclusionary criteria to determine whether the recommended site or area merits further consideration. If these criteria are satisfied, the volunteer will be carried through subsequent stages of the screening process. Unless exclusionary conditions rule out a volunteer site supported by a community, every effort will be made to keep it under consideration until the point where it can be compared with other potentially suitable sites in terms of technical suitability and other decision factors.

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--> Recommended sites without community support must be obviously superior compared to other potential sites in order to continue evaluations beyond the initial steps. During the GIS Screening, five parcels of land were offered by private landowners.6 None of the landowners offered evidence that these sites had support from their surrounding communities. In its consideration of these properties, the Siting Commission made several amendments to the procedures of the Siting Plan in a resolution passed at its January 1989 meeting. The resolution distinguished between offered sites, which were offered by landowners without community support, and volunteer sites, which were offered by landowners with the support of the surrounding communities. The January 1989 resolution established new procedures for determining the suitability of both types of sites. Unlike the original Siting Plan, however, the language of the resolution was vague about the particular screening procedures that would be applied to the volunteer and offered sites. On this point, the newly stated procedure was only to perform initial in-house review against technical criteria to determine that the parcel meets the cutoff level in use at the current selection stage. The parcel must be at least as good as the sites being considered at that stage. Four of the offered sites were added to the list of 51 sites being evaluated during the Field Surveys step. The offered site in Cortland County (Taylor North) was included among the five final potential sites (Table 6.3; Figure 6.1). Contributed Information Following the conclusion of the CAI screening (Chapter 5), the Siting Commission requested information from local governments on each of the 10 candidate areas identified, including data on the following: 6   According to the ROPSI, four of the sites are located in Allegany, Clinton, Cortland, and Franklin counties. The location of the fifth site is not given.

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--> population, zoning, local climate, well records, and locations of recreational facilities, ecologically sensitive areas, historic zones, large private institutions, schools, hospitals, tourist attractions, inactive waste disposal sites, and floodplains. The contributed information was reviewed to determine whether it affected the sites under consideration in PSI screening. Some of this information was used during the windshield surveys and some during the Rescreening step to verify previous Siting Commission conclusions. Most of the information, however, was set aside for site characterization activities and preparation of the draft environmental impact statement. 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. The Siting Commission, however, decided that most of the data were too detailed to be used at this stage and preferred to defer application of the information until characterization, after potential sites had been chosen. A description of the information contributed by local governments is summarized in the ROPSI. On the basis of information received on the sites in Allegany County, two surface water bodies and watersheds were excluded, and the location of a surface water intake was corrected in the Siting Commission database. Extensive information was received from Cortland County, but the Siting Commission decided not to utilize most of it for PSI screening. Cortland County argued that the 1980 census was outdated and that the 1986 census should have been used. The Siting Commission defended the use of the 1980 census data, noting that they were available for all candidate areas. Washington County submitted information on regional geology and cultural and historic resources. The Siting Commission used the regional geology in its windshield surveys. Cayuga County conducted a GIS analysis similar to the Siting Commission's exercise. That analysis and other contributed information were reviewed by the Siting Commission to verify its GIS database. Oswego County also conducted a GIS analysis and produced a composite map showing areas that should be excluded. These results corresponded closely with the Siting Commission's analysis. Chenango County provided general background

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-->   Criterion Scaling Factor for Scenarioa Category (Criterion Number) Weighta #1 #2 #3 #4 #5 #6 #7 #8 Geologic units (5) 35 1 1 1 5 5 5 5 3 Mineral resource potential (8) 20 1 1 1 5 5 5 1 5 Distance from oil and gas fields (10) 20 1 1 1 5 5 5 1 5 Primary and principal aquifers (12) 55 1 1 1 5 5 5 5 1 Unconsolidated stratigraphic units (14) 40 1 1 1 5 5 5 5 1 Best usage of surface waters (22) 30 1 1 1 5 5 5 5 1 Ecology (29) 55 1 1 1 5 5 5 5 5 Distance from historical/cultural resources (59) 20 1 1 1 5 5 5 1 5 Subtotal 375 375 375 375 1,795 1,795 1,875 1,635 1,165 Population Quantities Low population densities (33) 45 1 5 5 1 5 1 5 5 Highly populated places (34) 45 1 5 5 1 5 1 5 5 Routes through incorporated places (53) 10 1 5 5 1 5 1 1 5 Subtotal 100 100 500 500 100 500 100 460 500 Total Score 705 715 1,115 1,475 2,135 2,535 2,575 2,735 2,815 Normalized Scoreb 1,001c 1,015 1,583 2,095 3,032 3,600 3,657 3,884 3,997 a See Chapter 3 for an explanation of these quantities. b Normalized scores were determined by multiplying by a factor of 1.42. This factor represents the ratio of the maximum score using this subset of criteria (maximum score = 3,525 when siting factor = 5 for all criteria) 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. 4-45) In CAI Initial Preference Screening, weights were renormalized to 1,000 points before scores were determined. c This score was reported as 1,000 in the ROPSI.

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--> TABLE 6.5 Potential Sites Rescreening Sensitivity Analysis   Criterion Scaling Factor for Scenarioa Category (Criterion Number) Weighta #1 #2 #3 #4 #5 #6 #7 #8 Known Quantities Distance from mines (7) 20 1 1 5 1 1 5 5 5 Surface water features (13) 40 1 1 5 1 1 5 5 5 Distance from wetlands (18) 30 1 1 1 1 1 1 5 1 Drainage (19) 30 1 1 1 1 1 1 5 1 Flooding (21) 25 1 1 1 1 1 1 5 1 Annual precipitation (23) 20 1 1 1 1 1 1 5 1 Chronic severe weather (24) 15 1 1 1 1 1 1 5 1 Severe weather frequency (25) 20 1 1 1 1 1 1 5 1 Other radionuclide sources (30) 20 1 1 1 1 1 1 5 1 Distance from federal lands (37) 10 1 1 5 1 1 5 5 5 Distance from state lands (39) 10 1 1 5 1 1 5 5 5 Distance from Indian lands (42) 10 1 1 5 1 1 5 5 5 Government-owned lands (43) 20 1 1 5 1 1 5 5 5 Transportation access (47) 10 1 1 1 1 1 1 5 1 Existing transportation (49) 5 1 1 1 1 1 1 5 1 Multimode access (50) 5 3 3 3 3 3 3 5 3 Proximity to waste generators (51) 20 1 1 1 1 1 1 5 1 Labor force (54) 10 1 1 1 1 1 1 5 1 Housing stock (55) 10 1 1 1 1 1 1 5 1 Municipal services (56) 15 1 1 1 1 1 1 5 1 Viewshed (60) 15 1 1 1 1 1 1 5 1 Subtotal 360 370 370 810 370 370 810 1,800 810 Uncertain Quantities Geologic complexity (1) 45 1 1 1 5 5 5 1 5 Seismic hazards (2) 20 1 1 1 1 1 1 5 1 Subsurface dissolution (3) 35 1 1 1 5 5 5 1 5

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-->   Criterion Scaling Factor for Scenarioa Category (Criterion Number) Weighta #1 #2 #3 #4 #5 #6 #7 #8 Geologic units (5) 35 1 1 1 5 5 5 1 5 Mineral resource potential (8) 20 1 1 1 5 5 5 5 5 Distance from oil and gas fields (10) 20 1 1 1 5 5 5 5 5 Primary and principal aquifers (12) 55 1 1 1 5 5 5 1 5 Unconsolidated stratigraphic units (14) 40 1 1 1 5 5 5 1 5 Erosion (20) 35 1 1 1 5 5 5 1 5 Best usage of Surface waters (22) 30 1 1 1 5 5 5 1 5 Ecology (29) 55 1 1 1 5 5 5 1 5 Distance from historical/cultural resources (59) 20 1 1 1 5 5 5 1 5 Subtotal 410 410 410 410 1,970 1,970 1,970 650 1,970 Population Quantities PSD increment (27) 30 1 5 5 1 5 1 5 5 Proximity to incompatible activities (31) 20 1 5 5 1 5 1 5 5 Low population densities (33) 45 1 5 5 1 5 1 5 5 Highly populated places (34) 45 1 5 5 1 5 1 5 5 Nonresident populations (35) 25 1 5 5 1 5 1 5 5 Development/population growth (45) 20 1 5 5 1 5 1 5 5 Traffic congestion (48) 10 1 5 5 1 5 1 5 5 Transportation safety (52) 15 2 4 4 2 4 2 4 4 Routes through incorporated places (53) 10 1 5 5 1 5 1 5 5 Noise sensitivity (61) 10 1 5 5 1 5 1 5 5 Subtotal 230 245 1,135 1,135 245 1,135 245 1,135 1,135 Total Score 1,000 1,025 1,915 2,355 2,585 3,475 3,025 3,585 3,915 NOTE: PSD = Prevention of Significant Deterioration. a See Chapter 3 for an explanation of these quantities.

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--> 230, 375, and 100, respectively. The relative differences in these weights are similar to those in the CAI Initial Preference Screening (see Table 5.5), which were 347, 533, and 120. Consequently, many of the conclusions of the sensitivity analysis for CAI Initial Preference Screening also apply here. Most notably, preference criteria scored using ''uncertain quantities'' continue to play a significant role in PSI 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) than for Initial Preference Screening in CAI (4,400 points) allowed sites to exceed the cutoff with less favorable overall ratings. Most significantly, sites could receive less favorable or even unfavorable scores on important performance-related criteria and still exceed the cutoff. This situation is illustrated in Scenario 8 in Table 6.4. Many of the critical performance criteria are ranked as unfavorable [scaling factor (sf) = 1], yet the total score (3,997 points) still exceeds the cutoff. In contrast, these critical performance criteria are scaled as most favorable (sf = 5) in Scenarios 6 and 7, yet the total scores (3,884 and 3,657 points) fall below the cutoff because of unfavorable ratings on other criteria. The score in Scenario 7 can be boosted above the cutoff by an inconsequential change in a preference criterion such as annual precipitation. GIS Screening had a modest bias toward rural areas. The DEC regulations also had a bias toward rural areas, but it is not clear that the Siting Commission fully recognized the additional degree of bias it introduced through the use of multiple criteria. The total weight of population-related criteria was 100 out of 750 points. The other criteria used in this step of screening correlated only weakly with population criteria. Table 6.5 shows the sensitivity in scores to the full range of preference criteria that were used in the Rescreening step of PSI. The weights of the three categories of preference criteria (i.e., known, unknown, and population quantities) are 360, 410, and 230. Population and associated socioeconomic criteria take on a much greater

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--> significance in this screening step; that is, they account for more of the total weight. The significance of these criteria is even greater than that indicated by the increase in weight, however, because many of these criteria are correlated, as explained below. In general, the population criteria give high scores to rural areas with low populations, with the possible exception of the Criterion 35, concerning the presence of nonresident populations. For this reason, the committee concludes that scoring at this stage of screening is biased toward rural areas. It should again be noted that part of this bias is derived from a bias toward rural areas inherent in DEC regulations, but that it is not clear whether the Siting Commission fully appreciated the degree of bias that was present due to the combined effects of the full set of factors. Preference criteria scored with "known quantities" are linked strongly to population. These criteria include existing transportation (Criterion 49), labor force (54), housing stock (55), and municipal services (56). In general, the scores for these criteria are inversely proportional to those for the population quantities: highly populated areas will tend to score highly on these factors. There are also a number of transportation criteria that are highly correlated. Thus, they will receive similar scores because they largely describe the same siting factors. These include transportation access (47), existing transportation (49), multimode access (50), traffic congestion (48), transportation safety (52), and routes through incorporated places (53). Together, these 6 criteria have a weighting of 55 points, comparable to or greater than the weights of many of the individual performance-related criteria. 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, 48, 52, 53, 54, 55, 56, 59, 60, and 61 (see Table 1.2). These criteria, which addressed issues such as the available labor force, access to highways, and population density, account for 30 percent of the total weight (300 out of 1,000). The committee recognizes that socioeconomic issues are critical concerns in siting an LLRW

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--> disposal facility, but there are two problems with the way in which these issues were handled by the Siting Commission. First, the specific criteria applied in screening mainly addressed demands for local facilities and services when large numbers of workers move into a rural area—which would have been quite modest for any of the facilities being envisioned even in the most rural areas of New York State—as opposed to focusing on the specific socioeconomic concerns that had been identified as most important by the scientific literature of the day. The more relevant concerns, as well known even by the early 1980s, are those having to do with equity, local control, and susceptibility to what were called "special" impacts (see Chapter 7). Second, a site could receive unfavorable ratings for critical performance factors and yet still be selected if it scored highly on socioeconomic and other factors that were not so directly related to facility performance, as in the case of the rainfall example noted earlier. 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. The analysis in Table 6.5 also shows that a rural site with little baseline information could also score above this cutoff. This is illustrated by Scenario 8, which received favorable ratings (sf = 5) on all but two of the uncertain and population quantities and was located away from ground water discharge zones and federal, state, and Indian lands. In the committee's judgment, site selection should be optimized for both performance-related criteria and socioeconomic criteria, but to the extent feasible and reasonable, the performance-related criteria should be applied first: that is, screening based on performance criteria should be carried out before screening based on socioeconomic or other criteria not directly related to facility performance. The committee recognizes that such a division will often prove more challenging than is first apparent because even the most precise screening using "performance-related" criteria involve an inescapable element of human

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--> judgment, particularly when it is necessary to consider those criteria in combination with one another. A 1981 assessment (reprinted in U.S. Office of Technology Assessment, 1985, p. 218) recognized that judgments about acceptability [of nuclear waste facilities] are fundamentally matters of preference. Scientific and technical findings can inform those judgments by clarifying what the levels of safety associated with particular system design or repository siting decisions are likely to be. Even if those findings should be consensually accepted as being empirically accurate (no small task in itself), it still remains for the individual or society as a whole to determine, based on a set of values, whether those levels of safety are satisfactory or not. Although the Siting Commission combined performance-related and nonperformance-related criteria in ways that ultimately proved to be problematic, the problem is not simply that socioeconomic criteria were explicitly included in the calculations. Rather, most of the attention to socioeconomic criteria was focused on matters of relatively minor concern. 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. Summary 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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--> The committee analyzed the exclusionary and preference criteria used in PSI, and it also analyzed the PSI screening process itself. The committee's findings are summarized in the following sections. 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. The remainder are summarized below. The assumption underlying the design of Criterion 1—geologic complexity—namely, that uniform geology provides simple or predictable subsurface flow pathways, is overly simplistic. The application of this criterion at this stage of screening was inappropriate without more detailed, site-specific data. Criterion 3—subsurface dissolution—should have been applied as an exclusionary condition because of the significant performance implications of dissolution. Subsurface dissolution can produce large subsurface voids, leading to subsidence or collapse. Criterion 20—erosion—should have been applied as an exclusionary condition. In the judgment of the committee, LLRW disposal facility should not be located in areas with a high potential for surface erosion. The methodology used to apply Criterion 44—mineral soil groups—during screening was inappropriate, because it failed to exclude all areas under active agriculture containing these soils. At this point in the process, the Siting Commission deviated from its previous practices of removing cells that contained any part of an exclusionary feature. The design of drainage criteria, particularly Criterion 14—unconsolidated stratigraphic units—was unnecessarily restrictive and may have eliminated many otherwise suitable areas of the state from consideration.

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--> Screening PSI screening comprised four discrete steps: (1) GIS Screening, (2) Qualitative Map Assessments, (3) Field Surveys, and (4) Rescreening Using All Criteria. The committee's findings with respect to these screening steps are summarized below. GIS Screening. As with CAI Initial Preference Screening, in GIS Screening there may be only a weak correlation between scoring and the likely performance of the site. Qualitative Map Assessments. The Qualitative Map Assessments step was not discussed in the Siting Plan but was added at a later time by the Siting Commission. 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. Field Surveys. The plan, staff training, and criteria applied in the Field Surveys step appear to the committee to be conceptually sound. There was not enough information provided to the committee, however, for it to determine how the information collected in these surveys was actually used in site selection. There are some indications that data from these surveys were not used appropriately in at least some cases. For example, field survey data collected for the Taylor sites (which were among the five final sites; Table 6.3; Figure 6.1) indicate that they should have been excluded because of the presence of incompatible structures. Rescreening Using All Criteria. The selection of five potential sites was based on an undocumented staff decision, a decision that was not adequately described in the ROPSI. The design of scaling factors is not documented adequately in any of the Siting Commission's reports.

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--> Although the committee recognizes that, at best, scaling factors are subjective, it questions whether many of the scaling factors are based on reasonable technical considerations. Volunteer and Offered Sites. The Siting Commission's decision to include the Taylor North site in the final list of potential sites (Table 6.3; Figure 6.1) is inconsistent with the commission's requirement that offered sites must be at least as good as other sites. The Taylor North site did not meet the minimum cutoff score applied to other sites at the same stage of screening. Furthermore, the site contained soils in mineral soil groups 1 through 4 and was under active agriculture (see footnote 13), which should have disqualified it from further consideration. Contributed Information. In the committee's judgment, the Siting Commission made a sincere effort to obtain, review, and use contributed information supplied to it by local governments, but the commission did not effectively communicate why it decided to defer using much of the information until later stages. The committee compared some of this contributed information with data in Siting Commission databases and found no inconsistencies. Sensitivity Analyses. 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. Consequently, it should have performed a detailed sensitivity analysis to address the effects of its scoring system on siting decisions. The committee performed its own sensitivity analysis for two steps of PSI screening (GIS Screening and Rescreening) in order to examine the effects of the weighting and scaling factors on scoring. Its conclusions are summarized below: Preference criteria scored using uncertain quantities (i.e., data of unknown or uneven accuracy and completeness) had a significant effect on scoring during both GIS Screening and Rescreening.

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--> Consequently, there may be a weak correlation between the final score for a site and its suitability as an LLRW repository. As with CAI Initial Preference Screening, sites could receive unfavorable scores on performance-oriented criteria and still exceed the cutoff if they scored well on socioeconomic criteria. Sites with scores near the cutoff could be pushed across the cutoff threshold by inconsequential changes in certain criteria (see also point 4 below). The GIS Screening and the Rescreening steps had a bias toward rural areas, which is partly reflective of a bias in the DEC regulations. In the committee's judgment, scoring for the Rescreening step inappropriately combined performance and socioeconomic criteria. Thus, a site could receive less favorable or unfavorable ratings for important performance criteria yet still score above the cutoff if it received favorable scores on a large number of socioeconomic factors. The committee believes that site selection should have been based on a sequential screening using both performance-related and socioeconomic criteria after the exclusion of lands specified by regulations. 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.