ML20211J060
| ML20211J060 | |
| Person / Time | |
|---|---|
| Issue date: | 10/30/1986 |
| From: | Martin D NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Themelis J ENERGY, DEPT. OF |
| References | |
| REF-WM-68 NUDOCS 8611100232 | |
| Download: ML20211J060 (8) | |
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WM Record fde WM Prcitet OCT 3 01986 Docket No.__
h0NC/10guno PDR /_ LPDR John G. Themelis, Project Manager Distribution:
Uranium Mill Tailings Project Office U.S. Department of Energy P.O. Box 5400 Return to WM,623 SS)
Albuquerque, NM 87115
Dear Mr. Themelis:
Enclosed please find NRC comments on the Green River, Utah Comparative Analysis of Disposal Site Alternatives Report (CADSAR). The additional attachment consisting of DOE's response to each NRC comment on the draft CADSAR was helpful in performing our review of the final CADSAR.
As indicated in the enclosed remarks, the NRC staff did not have sufficient information to determine whether the two options described would be adequate to meet EPA standards without greater difficulty and expense than is acknowledged in this CADSAR. According to DOE's specific responses to NRC concerns, further data and evaluations exist which would resolve this uncertainty; however, this infonnation was not available to us for this review.
Due to the " approach" DOE has taken in the preparation of this CADSAR, as well as of CADSARs in general, NRC will not be able to provide any consensus on a determination that a disposal site will be able to meet EPA standards. Even a preliminary judgment of this kind would require a greater level of field characterization data and information than is currently within the scope of the CADSAR.
Should you have any questions regarding this transmittal, please contact.
Giorgio Gnugnoli of my staff at (FTS) 427-4788.
Sincerely, M-Dan E. Martin, ection Leader Uranium Recovery Projects Section Low-Level Waste and Uranium Recovery Projects Branch Division of Waste Management Office of Nuclear Material Safety and Safeguards
Enclosure:
Specific Connents on the Green River CADSAR cc: w/enclo.
JGarcia, DOE /AL RSena, DOE /AL RDale Smith, URF0
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- 10/24/86
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GRN FINAL CADSAR/MHY/ DUP GROUNDWATER HYDROLOGY COMMENTS GREEN RIVER FINAL CADSAR Section 2, Alternative Site Selection, Page 3 The final CADSAR fndicates that several groundwater characteristics are undefined and that efforts are_under.way to better understand.and quantify the hydrogeologic system. However, in the DOE memorandum (November 19,1985) titled, " Implementation of New Planning / Development Process", DOE states "The CADSAR will be finalized after full site characterization activities have been-completed." Since~ several critical hydrogeological characteristics such as presence of Mancos Shale and existing groundwater contamination are unknown, the decision on final site selection in the CADSAR appears premature.
DOE should consider re-evaluating the decision-making process at Green River to determine whether results from additional characterization efforts should be factored into the final site selection.
Secticn 4.2. Stabilization on Site, Page 20 The CADSAR states that "the excavated pit may or may not require a low-perrr.eability liner." Since the cost of constructing the liner wasn't considered in the SOS cost summary found in Table 6.2, it appears that DOE has already elected not to employ a liner. A technical justification for this decision shculd be provided, especially in light of the SOS proposal to dispose of contaminated tailings on " highly permeable, highly variable" material. Without such a justification, DOE should anticipate the use of a liner (if the SOS option is exercised) and include the cost of liner construction in the cost of remedial action.
Section 8.2, Preferred Alternative, Page 26 The final CADSAR. states that only SIP and SOS options were considered because both options provided technically feasible disposal areas. After cost comparisens, the SOS option was chosen. However, several considerations pertaining to the hydrogeology of the preferred site are of particular concern l
to NRC staff, and they include:
A.
The proposed disposal site is located on alluvium that "... would most likely be highly permeable, [and] highly variable in both extent and composition...." This type of medium for disposal of
_ _ _. - _ = _ _ _ _ _ _ _ _
i GRN FINAL:CADSAR/tiHY/ DUP ' contaminated tailings may promote migration of contaminants, due to high hydraulic conductivity, into an aquifer system containing water that ".~.. may be suitable for irrigation and stock watering." In fact, the CADSAR states that alluvial, shale and deep (Burro _ Canyon Fomation) wells already'show signs of contamination. Concentrations of uranium in the Mancos Shale and Burro Canyon Formation downgradient of the pile are 1.4 mg/l and 0.02 mg/i respectively, higher than upgradient values.
S.
Although many other UMTRA project sites-are located within the Mancos Shale, a well-known stratum in the area, the proposed disposal site
"... may or may not directly overlie the low-permeability Mancos Shale found nearby."
In fact, from Figure 3.3 of the CADSAR, it-appears that the Mancos' Shale (called Tununk Shale in the figure) consists primarily of sandstone / shale interbeds, which may not constitute a good confining layer. Therefore, there is some uncertainty as to whether the presence of the Mancos Shale has really been established, and whether deeper aquifers can be protected from potential contamination.
C.
According to the CADSAR, unlined pits located abcut 1000 feet _ west and downgradient of the pile, were fomally used for the disposal of wastes from a nearby launch facility. However, the types of wastes disposed of in these unlined pits were' not discussed. Since potential groundwater contamination from the launch facility's disposal area may significantly ma~sk the results of groundwater conitoring activities initiated by DOE, it may be difficult to determine the source of groundwater pollution.
This could present a problem in characterizing the extent of tailings-related pollution for remedial action-purposes, as well as for. future monitoring during the-surveillance and maintenance phase.
D.
The tailings pile may have already impacted water quality in Brown's Wash. According to the CADSAR (page 14), water quality results show uranium concentrations as high as 1.3 mg/1, indicating recharge of the wash by centaminated ground water. This presents a potential problem in identifying the source of any future contamination, specifically from the SOS disposal area, when contamination from the existing pile is already present in surface and ground water nearby.
Based on these conditions, dispcsal of tailings using the SOS option may lead-
.to increased contamination of usable ground water in the Green River area.
Furthermore, contributions from other unquantified sources of pollution in the near-field environment may complicate the evaluation of tailings-related contamination from the SOS option.
From the considerations above, it does not
GRN FINAL CADSAR/MHY/ DUP appear that all the available information on the hydrogeology and present grounowater quality was taken into account daring the decision-making process.
If the SOS cption is pursued, DOE should consider the characterization dnd monitoring activities needed to fully understand the hydrogeological characteristics of'the site and vicinity during the design phase of the remedial action and to ensure com;;11ance with water quality criteria specified in DOE's proposed plan.
m.
GRi1 FINAL CADSAP/MHY/0UP EROSION PROTECTION - SURFACE. WATER HYDROLOGY COMMENTS GREEN RIVER FINAL CADSAR Section 7, Comparision of Alternatives, p. 25.
In this section, it is concluded that the SOS option is preferable to the SIP option. One of the reasons cited for this preference is the comparative. cost of placing erosion protection for these options.
Based on observations made on the October 1, 1986 visit to the site and additional reconnaissance-level information not provided in the CADSAR, it appears that a potentially significant disadvantage of the SOS option is the presence of numerous, deep gullies immediately in the vicinity of the proposed pile location. Though information presented in the CADSAR is not sufficient to reach a firm conclusion, it appears that an erosion protection design capable of meeting EPA standards for the SOS option may be more costly than is presently envisioned by DOE.
These concerns are based on the following observations:
A.
Gullies exist imediately adjacent to the proposed SGS pile location.
The potential latoral erosion of these gullies could compromise the integrity of the pile.
B.
Gullies exist where the SOS pile will be placed. Headcutting of such guilies could require the placement of extensive erosion protection.
C.
Existing gullies are deep and have been incised into bedrock, althcugh it is not clear whether this material is actually competent bedrock.
In combination with the factors listed above, the depth of the riprap toes and aprons which may be needed to protect the pile, may be rather large. Such a determination would also depend on the depth at which competent rock exists.
~
D.
The drainage areas of the gullies in the proposed SOS area appear to be relatively large and may have been further enlarged by recent highway construction.
It is likely that diversion channels will be needed.
E.
The natural slopes existing in the site area are relatively steep.
These slopes may require large riprap sizes, and large quantities
GRN FINAL CADSAR/MHY/ DUP of riprap may be needed for the steep ditches and/or apron slopes.
' A re-analysis should be performed, taking into account the design difficulties identified above.
In conclusion, there is little evidence to suggest that providing erosion protection for the SOS optien will be as inexpensive or as uncomplicated as suggested in the CADSAR. NRC's preliminary review of site features indicates that providing erosion protection may be a significant problem, and it should have been identified in the CADSAR.
Section 8, Recommendations It would seem prudent not to terminate the search for alternate sites or alternate disposal methods when only limited reconnaissance-level information is included in the decision-making process. Too many variables need to be assessed before a firm decision can be reached with regard to any one site, and the final design tends to be developed only after a large amount of data and information has been gathered.
The NRC staff considers the selection of preferred alternatives and the elimination of other options to be premature in the CADSARs reviewed to date, based on the information provided.
During the NEPA evaluation stage for the Green River remedial action, it is reccomended that additional alternative sites or alternative designs be seriously considered.
~...
GRN FINAL CADSAR/MHY/ DUP GE0 TECHNICAL ENGINEERING COMMENTS GREEN RIVER FINAL CADSAR General 1.
NRC ccmments on the draft CADSAR.were summarized by DOE and submitted with DOE responses in the final CADSAR package. DOE responses indicated that NRC geotechnical concerns would be aodressed in later documents such as the RAP, since those concerns focused on detailed technical information.
However, DOE acknowledged that the early identification of these concerns would prove to be useful in conducting future site characterization field work and data collection-and evaluation.
It is strongly recommended that these concerns regarding characterization of foundation soils, durability of erosion protection material and other geotechnical aspects of a disposal option be factored into the field characterization and data collection for all sites still in the early CADSAR stages.
2.
Comment El on the draft CADSAR raised the issue of the premature rejection of off-site disposal options. DOE's response indicated that data collection and evaluation subsequent to the time of the NRC review of the draft CADSAR confirmed DOE's selection of SOS. Since NRC was not provided with the data or summary of data collected nor with the additional data collection plan, there is no basis on which to agree, even in principle, with DOE's conclusion to exclude all but SIP or SOS options.
4
GRN FINAL CADSAR/t1HY/ DUP GEOMORPHOLOGY COMMENTS GREEN RIVER FINAL CADSAR
-Section 3.2, Geological and Geotechnical (Characterization of the Site)
The final CADSAR recognizes a potential disadvantage of the stabilization-on-site alternative (50S) in the nature of terrace alluvium occurring beneath the site. Based upon field observations (October 1,1986 site visit), the NRC affirms the alluvium is loosely consolidated and appears to be easily erodible.
Further, vegetation at the site is extremely sparse, adding to the potential i
for severe erosion of naturally occurring soil materials due to sheetwash, gullying, or eclian deflation. Also, youthfulness and/or recent instability of the surficial deposits is evidenced by lack of soil-profile development (weathered pedogenic profiles). Finally, Mancos Shale underlying the site, and exposed in at least one gully, appears fractured and intensely weathered.
Therefore, neither shallow bedrock nor terrace alluvium are likely to provide resistance to erosion at the Green River site.
The:,e conditions are critical to the site, because of the relatively deep gullies with steep longitudinal profiles observed during the October 1 site visit. The existence of these gullies, not indicated in the CADSAR, and the relationships with surficial deposits show that the site is geomorphically unstable and in an eroding regime.
Based on these conditions, the NRC con-cludes that the CADSAR underestimates the surface geologic conditicns at the site and their potential impact on long-term site stability.
It appears the naturally occurring drainage system around the proposed disposal area will require significant modifications and engineering measures to ensure meeting EPA standards for long-term site stability.
These concerns should be factored into the NEPA and RAP analyses.
,