ML20215J476
| ML20215J476 | |
| Person / Time | |
|---|---|
| Issue date: | 06/11/1987 |
| From: | Lohaus P NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | James Anderson ENERGY, DEPT. OF |
| References | |
| REF-WM-43 NUDOCS 8706250014 | |
| Download: ML20215J476 (10) | |
Text
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DISTRIBUTIQl, JUN 111987 LLWM-43 7 NMSS RF LLOB RF WM43/MH/06/03/87 el hard file WM Pdd -
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, M. }i-MFliegel i
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TJohnson PLohaus l
James R. Anderson, Project Manager Uranium Mill Tailings Project Office U.S. Department of Energy
'rkin KWestbrook Albuquerque Operations Office _
. _ LDeering
.._ _hf DWidmaye r P.O. Box 5400
_. _ _,/
M Kn a p p i
Albuquerque, NM 87115
! wm a W. Om JGreeves
Dear Mr. Anderson:
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The Nuclear Regulatory Commission has completed its review of the Draft CADSAR for the Lowman, Idaho site. Our review consisted of a broad overview to identify fatal flaws, potential issue areas, and omissions.
Based on that review, my staff have identified two major concerns with the stabilization proposal. The first is that the site appears to have siting features that will make the final design complex and costly.
The second concern is that the draft Comparative Analysis of Disposal Site Alternatives Report dismisses alternatives other than stabilization on site with, in our view, too little analysis.
If the current site could be clearly shown to be a very good location, we could understand eliminating other sites in the CADSAR with little further analysis.
However, the current Lowman site has steep slopes leading into a creek, good and possibly very shallow ground water, and is in an area of potentially significant faulting. Given these factors, the early elimination of other sites is not warranted.
It may well be i
that this site is the most feasible location to work with, but this needs to be properly demonstrated.
Because of the potential design complexities associated with this site, we would like to plan a meeting to further discuss our comments. We will need to i
see the site, the Five Mile Creek area, and see why, as indicated in the draft I
CADSAR, no other suitable sites could be found -- through driving, maps, photos, etc. We would like to plan on this meeting in mid-July, if possible.
Please call Mark Haisfield at FTS 427 4722 if you have any questions on the enclosed comments and to coordinate the site visit.
Sincerely, originalgig,sd W gyron H. Flit 601 8706250014 870611 Paul H. Lohaus, Acting Chief PDR WASTE Operations Branch WM-43 PDR
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Division of Low-level Waste Management and Decommissioning
Enclosure:
Lowman Coments
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7FFICIAL RECORD COPY
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j-UMTRA DOCUMENT REVIEW FORM SECTION 1 Site: Lowman, ID Date: June 1987 Document: d CADSAR Comentor: NRC/ Geoloqy-Seismoloqy fi Coment:
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Section 3.2 of the draft CADSAR states that a portion of soil beneath the 1
tailings is composed of brown to black sandy clay.
It is further stated that
" Steep slopes and the presence of these potentially weak residual soils will require carefui consideration during-design of.the stabilized pile."- The NRC staff considers that the seismic stability aspects of the soils beneath the j.
. tailings require ~ detailed consideration, especially because t is area is h
seismically active, as evidenced by a 6.1 (ML) event in 1944 only 22 miles from the site, and because there is a potentially capable fault 4 miles west of the s i t,e.
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2 UMTRA DOCUMENT REVIEW FORM SECTION 1 Site: Lowman, ID Date: June 1987 Document: d CADSAR la 1
j Commentor: NRC/ Geology-Seismology Comment:
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9 Section 3.2 of the draft CADSAR provides a. seismic design acceleration for the jl site based (n) a floating earthquake of magnitude 6.2.
Because a magnitude 6.1 earthquake _ occurred within 22 miles of the site, a magnitude 6.2_ earthquake may I
not be conservative enough for design purposes. This.is further indicated by ll the existence of a potentially capable fault 4 miles west of the site.' The final CADSAR should be revised to select a larger seismic design acceleration.
or to justify the seismic design acceleration based on a magnitude 6.2 L
earthquake in light of existing site information.
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UMTRA DOCUMENT REVIEW FORM SECTION 1 Site: Lowman, ID Date: June 1987 Document: d CAD 5AR Comentor: NRC/ Geology-Seismology Comment:
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20 Under the heading " Summary of Data Needs" it is indicated that the planned site-specific work may include low-sun-angle aerial roconnaissance of the site area to locate potentially active faults and geomorphic features. The NRC staff considers that low-sun-angle reconnaissance data are necessary for the Lowman site because the site area is seismically active as evidenced by a potentially capable fault located four miles from the site and the magnitude 6.1 earthquake that occurred in 1944 only 22 miles from the site. The final CADSAR should be revised to identify low-sun-angle data as a definite data need.
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UMTRA DOCUMENT REVIEW FORM SECTION 1 Site: Lowman, ID Date: June 1987 Document: d CADSAR I
I Commentor: NRC/Hydroloqy Comment:
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15 Anexaminationoftheproposeddesignforstabilizationon-site (Figure 4.1) indicates that the stabilized pile will be located on a relatively steep hillside.
It further appears that diversion ditches will be needed to divert surface water runoff around the pile. At this location, the proposed ditches will have to be very steep (possibly greater than 10%) and the drainage area upstream of the ditchas does not appear to be extremely small.- Therefore, it.-
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. may be necessary to armor the. ditches with very large riprap for erosion.
1 protection against potential flow velocities greater than 25 feet per second.
. l NRC staff experience with steep terrain has indicated that it may be very difficult to provide erosion protection riprap of the required size.
It may'be prudent for DOE to examine other potential sites to avoid the need for such, extensive and costly hydraulic design measures. We suggest that DOE examine the feasibility of relocating the tailings to other sites and/or examine the feasibility of implementing other design measures at the preferred site. The final CADSAR should be revised.to assess the feasibility of extensive erosion protection measures in light of the above discussion and to consider other-alternatives.
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UMTRA DOCUMENT REVIEW FORM 4
SECTION 1 Site: Lowman, ID Date: June 1987 Document: d CADSAR
-l Commentor: NRC/ Hydrology ii Comment:
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Examination of the proposed location of the stabilized pile (Figure 4.1)
- 1 indicates that the toe of the pile slope will be placed on a very steep slope.
!l In fact, it appears that the natural ground slope (e.g., in the southeast f'
portion) may be as steep as the side slope of the pile. Unless the slope is i
composed of bedrock, it appears that this steeper natural slope may also need
.i to be stabilized.
In addition, this slope may need to be protected Nainst because the creek is apparently a large, swiftly-floving stream.
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l) flooding by Clear Creek, probably necessitating use cf very large riprap 1 1 Based on the potential problems discussed above (assuming that the slope is not composed of bedrock), the final CADSAR should be revised to assess g
stabilization of the natural slope at the toe of the proposed tailings L
embankment and to consider alternate designs and/or alternate sites. At the Il very least, the location and extent of bedrock needs to be clearly defined h'
before any other designs are developed.
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UMTRA DOCUMENT REVIEW FORM SECTION 1 Site: Lowman, ID Date: June 1987 Document: d CADSAR Co;,rnentor: NRC/ Groundwater Comment: 6 Page:
gensral f
If results of the groundwater field investigation confirm that' that the water i
table is close to the ground surface, groundwater will be a significant environmental concern at the Lowman site.as indicated in the draft-CADSAR.
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this event, NRC-staff will review the proposed SOS alternative with two key questions in mind:
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Is the proposed disposal design adequate to isolate the tailings from a
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fluctuating near-surface water table? This will be paramount as the i
shallow aquifer is reported to be of excellent quality and is used as a I
water source to nearby residents and businesses.
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B.
Has it been adequately demonstrated that infiltration through the cover will not result in significant leachate production and subsequent t-migration into and through the shallow potable aquifer?
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7 UMTRA DOCUMENT REVIEW FORM SECTION 1 Site: Lowman ID Date: June 1987 Document: Draft CADSAR Consnentor: NRC/ Groundwater 3
Comment:
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7 The draft CADSAR states that the tailings from the Lowman site are different
.I IJ from tailings from other UMTRAP sites because they have been mechanically rather than chemically processed. A discussion should be provided regarding
's what differences are anticipated with respect to leachability and mobility of contaminants between the Lowman tailings and chemically-processed tailings i.
piles. The final CADSAR should include water quality results of groundwater sampling from the unsaturated zone within the tailings to characterize, in part, the contaminant source term,
- j ia The final CADSAR or draft EA should also provide information on groundwater j'
chemistry in support of site characterization as it influences groundwater 1
contaminant concentrations and site stability.
In addition, the future documentsshouldprovideinformationonsoilandsedimentgeochemistry(1.e.,
solubility, ion exchange, sorption, and carbonate content) to provide an understanding of the processes affecting contaminant migration and rock and 3
soil chemical stability.
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k UMTRA DOCUMENT REVIEW FORM
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SECTION 1 Site: Lowman, ID Date: June, 1987 Document: Draft CADSAR Commentor: NRC/ Groundwater Comment:
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'l The draft CADSAR states that approximately 12 monitoring wells will be installed on and near the Lowman site to locate and characterize groundwater.
It is not clear whether these 12 wells are part of an initial phase of the l-field investigation, or represent the entire groundwater monitoring program.
j Based on previous site characterization programs at UMTRAP sites, NRC
'l recommends that the groundwater characterization program allow for.at least two j
phases of groundwater monitoring well installation in the program schedule, p
with placement of the monitoring wells as needed in the second phase based upon d
results obtained from the initial monitoring wells. Such flexibility will 1
facilitate a more efficient and cost effective monitoring program.
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addition, information from operational assessment, aerial photographs, surface I
geology, soil borings, and geophysical investigations should be used to guide the placement and number of the groundwater monitoring wells.
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9 UMTRA DOCUMENT REVIEW FORM
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SECTION 1 Site: Lowman, ID Date: June 1987
'l Document: Draft CADSAR (Statement of Work)
- j Comentor
- NRC/ Groundwater l'
Comment:
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6 (of S0W)
Section 5.2, Exhibit A of the S0W indicates that a two-inch diameter monitor wells will be installed in each of.12 borings in order to determine-
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hydrogeologic characteristics underlying the site and to assess the extent of 3
subsurface contamination originating from the mill tailings. Two-inch diameter H
wells may not be large enough to support hydraulic testing and sampling that may be necessary to characterize site hydrogeology.
For example, the i
Environmental Assessment for the Green River VMTRAP site (December 1986) indicates that a two-inch diameter casing precluded adequate hydraulic testing j;i
, because it is too small to accommodate a submersible pump capable of pumping at J
a sufficient rate. NRC staff suggests that DOE consider installing four-inch d
diameter monitoring wells rather than two-inch wells to ensure that the wblis are large enough to accommodate pumping rates required for successful aquifer testing.
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In addition, the S0W should indicate that monitoring wells will be designed and I
installed to ensure stratigraphic correlation.
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