ML20234E468
| ML20234E468 | |
| Person / Time | |
|---|---|
| Issue date: | 11/20/1987 |
| From: | Lohaus P NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Arthur W ENERGY, DEPT. OF |
| References | |
| REF-WM-68 NUDOCS 8801110006 | |
| Download: ML20234E468 (3) | |
Text
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W. John Arthur, Acting Project Manager "yp,.,
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Uranium Mill Tailings Project Office
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U.S. Department of Energy
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Albuquerque Operations Office P.O. Box 5400 Albuquerque, NM 87115
Dear Mr. Arthur:
Enclosed are NRC Staff comments on the Preliminary Design for the Green River, Utah uranium mill tailings site. A draft version of these comments was provided to R. Richey of your staff October 27 for discussion at the on-board review meeting in San Francisco November 3, 1987.
Response to the comments should be provided to support our review of the final design.
Should you have any questions on these, please contact Susan Bilhorn at FTS 427-4145.
I would like to use this opportunity to bring to your attention a potential problem the staff has identified with the review schedules proposed by DOE for documents on the Green River site. According to the schedule provided verbally by DOE November 18, NRC staff will be requested to review and comment on the final design between November 24 and December 11, 1987, and on the final RAP between February 2 and February 29, 1988. According to the DOE monthly schedule, the final EA will also be sent to NRC for review December 8, with comments requested January 11, 1988. These documents and the sequence for review of these documents differs from that referenced in the MOU between NRC
- nd 00E on UMTRCA activities. While the staff could conduct a cursory review the final design prior to receipt of the final EA, we consider it necessary t
to review the final EA before providing comments on the final design. The NRC staff does not consider it appropriate to review these documents out of sequence as such a review process would be an inefficient expenditure of limited staff resources.
Finally, elimination of the preliminary final Design / RAP will also adversely affect the staff's ability to develop the documentation needed to reach concurrence.
We also note that the review period suggested is greatly reduced from the 30 to 60 day review period provided in the MOU. Our attempting to comply with this schedule will certainly affect our review of other documents that are scheduled in the same time-frame. Thus, we see a need to have priorities clearly identified and for DOE to maintain consistent schedules, to the extent possible, so that we can plan and apply staff resources in the most effective manner.
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WM-69/87/11/12 I would appreciate an opportunity to discuss this tratter further with you in the near future.
Please contact me at FTS 427-4799.
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Paul H. Lohaus, Chief' Operations Branch Division of Low-Level Waste Management and Decommissioning
Enclosures:
As stated.
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R. Richey, 00E/AL DISTRIBUTION:
1.. LLWM s/f HMSS r/f LLOB r/f SBilhorn, LLOB
' MF11egel, LLOB PLohaus, LLOB JSurmeier, LLTB MKearney, LLRB JGreeves, LLWM MKnapp, LLWM NOTE:
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OFFICIAL RECORD COPY
WM-69/87/11/12 I would appreciate an opportunity to discuss this matter further with you in the near future.
Please contact me at FTS 427-4799.
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Paul H. Lohaus, Chief Operations Branch i
Division of Low-Level Waste Management I
and Decommissioning
Enclosures:
As stated.
cc:
R. Richey, DOE /AL DISTRIBUTION:
LLWM s/f NMSS r/f LLOB r/f SBilhorn, LLOB MFielge, LLOB PLohaus, LLOB JSurmeier, LLTB MKearney, l.LRB JGreeves, LLWM MKnapp, LLWM NOTE: This document was developed in coordination with LLTB 0FC: LLOB CB
- LLOB NAME:SBi
- MF11egel
- PLohaus DATE:87/11/LO :87/11/
- 87/11/
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WM-69/87/11/12 Page 1 of 6 NRC STAFF COMMENTS ON THE PRELIMINARY DESIGN FOR GREEN RIVER, UTAH GE0 TECHNICAL ENGINEERING GT/1 - Suograde Preparation, Specification Section 02200, Pg 3 Item 1.4-I does not include subgrade preparation of the bedrock excavation that will serve as foundation for the tailings. As the bedrock is proposed to be excavateo by ripping, DOE should address subgrade preparation of the bedrock excavation in the final design.
GT/2 - Radon Barrier Materials, Specification Section 02200, Pgs 7 & 8 The specifications in this section should be revised to limit the maximum size of the particle permitted for the radon barrier material. The specifications presented in the preliminary design requier only that a minimum of 50 percent of the material pass through a #200 sieve. This may result in a poorly graded material which will exhibit a higher coefficient than a well graded material with a minimum or 50 percent material passing through a #200 sieve.
DOE should revise the gradiatin specification to ensure that the material placed as the radon barrier cover is similar to that tested to determine the coefficient of permeability values used in the design.
GT/3 - Contaminated Material Excavation, Specification Section 02200, Pc 12 The draft RAP indicated that the tailings embankment will be constructed by placing the highly contaminated tailings near the bottom of the pile and less contaminated material towards the top of the pile. However, this layering stategy is not addressed in the preliminary design l
specifications.
Item 3.3-8 of the cited specifications states only that l
contaminated material shall be "placed in the proper part of the tailings embankment." The staff think that these specifications should be more explicit. DOE should clearly describe the process of tailings placement (including layering) in the final design.
WM-69/87/11/12 Page 2 of 6 GT/4 - Field Quality Control Tests, Specification Section 02200, Pg 18 The field quality control specifications state that the frequency for in place density tests on the subgrade will be performed at a minimum of one test per 5000 square yards surface raaterial. However, at the Canonsburg and Salt Lake City (Clive) sites the frequency for in place density tests on the subgrade is one per 1500 square yards _. DOE should explain why a less conservative test frequency has been specified for the Green River site.
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WM-69/87/11/12 Page 3 of 6 GROUND-WATER HYDROLOGY GW/1 - Tailings Amendments, (general)
DOE is proposing to stabilize the Green River tailings on top of a fractured bedrock unit.
Random dispersal of leachate into the substrate is possible and may significantly affect DOE's ability to demonstrate compliance with EPA's ground-water protection standards. While the possibility of chemically amending the tailings to retard leaching was discussed during the September 15 on-board preliminary design review meeting, this action was not addressed in the preliminary design for review. NRC staff suggests that DOE consider amending the tailings, and evaluate the potential advantage of this action.
GW/2 - Material Excavation, Drawing No. GRN-PS-10-0512 The embankment design presented in the preliminary design is based on the assumption that all the contaminated material will be stabilized in the excavated area. However, DOE has not fully determined the amount of contamination in the impoundment structures west of the mill yard, or from the area within the mill yard west of the mill buildings. Because these areas could provide significant additional volumes for disposal, NRC staff suggests that DOE survey these areas and determine the extent of radiological contamination prior to finalizing the embankment design.
G9/3 - Monitor Well Abandonment, Drawing No. GRN-PS-01-0518 This drawing does not indicate which monitor wells and borings will be abandoned, and which wells will be maintained during the remedial action.
It appears that almost all wells and borings are to be abandoned as part of the remedail action, however no justification has been provided for abandoning these devices.
NRC staff considers monitoring ground water during remedial action necessary to evaluate the impacts of tailings disposal on ground-water resources.
If the ground water is not monitored during remedial action there will be gaps in DOE's database and it will be more difficult to demonstrate compliance with EPA's ground-water protection standards.
Therefore, the staff suggests that DOE clarify their plans and provide justification for abandoning wells and well points at the Green River site.
WM-69/87/11/12 Page 4 of 6 GW/4 - Permeability of Cover Material, Calculation No. 10-536-01 There appears to be a discrepancy between the permeability value used in the design and the values obtained from test results, as presented in the preliminary design. DOE used a " conservative" value of 1 E-07 cm/s for the proposed cover material (Sheet 45/63), however the test results presented on Sheet 44/63 indicate the permeability of the disposal site soils range from 2.8 E-05 to 5.2 E-06 cm/s.
DOE should resolve this apparent discrepancy and demonstrate that the site soils can meet the specified design permeability, without ammendment or treatment as suggested by DOE.
GW/5 - Clean-up Inconsistency, Calculations No. 10-535-01 and No. 10-536-01 The criterion presented in the preliminary design for clean-up of tailings along the banks of Brown's Wash are inconsistent. On sheet 1 of Calculation No. 10-535-01, DOE states that " excavation is carried out to the 15 pCi/g limit...", whereas on sheet 1 of Calculation No. 10-536-01, DOE states that the " depth of excavation is based on the level of contamination to 5 pCi/g of Ra-226." DOE should correct this inconsistency and recalculate, if necessary, the volume of tailings to be removed along Brown's Wash.
GW/6 - Tailings Embankment Design, Drawing No. GRN-PS-10-0517 This drawing indicates that precipitation falling on the pile will be discharged via percolation into the alluvial material and bedrock along the flanks of the embankment. No surface discharge structures are included to quickly convey water away from three sides of the embankment.
NRC staff are concerned that performance of the proposed embankment may be affected by: a) Water collecting in the riprap lens beneath overlying backfill, leading to increased flux through the infiltration barrier and possible saturation of the tailings; b) Saturation of the riprap lens by severe or prolonged precipitation and overtopping onto the backfill material causing erosion; i
c) Saturation of the overlying backfill material and decreased landscape I
stability, posing a concern to future occupants of the decommissioned mill buildings 300 feet NW of the embankment; d) Percolation of water from the alluvium and bedrock back into the tailings material.
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WM-69/87/11/12' Page 5'of 6 In telephone conversations with M. Young, NRC (November 12,1987),L.
Coons, DOE / TAC stated that results from recent field work indicate that the permeability of the Cedar Mountain Formation is almost four orders of magnitude higher than the radon barrier. Thus, water will flow away from the cell and not accumulate in the riprap lens.
Furthrer, L. Coons stated that geochemical modeling shows contaminants migrating from the cell will be sorbed by the bedrock and will not affect the water quality.
NRC staff will need to review the report that presents the additional data.
and new information before this issue can be closed. DOE should submit this information in a timely manner to allow for NRC staff review prior to receiving the final Design / RAP.
A WM-69/87/11/12 Page 6'of 6 SURFACE WATER HYDROLOGY SW/1 Riprap Material, Specification Section 02278, pg 3 h
Specifications for riprap material presented in the preliminary. design indicate that the rock will have to meet only the following durability requirements:
Specific Gravity - Not less than 2.45 Absorption
- Not greater than 4.00 l
NASO 4 Soundness - Not greater than 30 "4.oss (5 cycles)
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In general, NRC staff considers that these requirements will not be acceptable to assure that the epa long-term stability requirements will be met. Based on research performed for vne NRC staff (NUREG/CR-2642, Table a
6.7), rock meeting only these minimum specifications is likely to weather severely and thus may not meet epa longevity standards.
While the staff recognize that the selected rock will likely exceed minimum requirements, it is nevertheless possible that rock approaching the minimum limits could be used following these specifications. The minimum limits should be raised and/or an acceptable quarry should be specified. The source selected should be one where rock is shown, based on testing, to exceed the absolute minimums.
The riprap described in the preliminary design is not considered acceptable, even if oversized. DOE should provide the basis for selection of the rock durability specifications and should provide additional information regarding durability of the selected rock, including any information and evaluations related to oversizing.
In addition, DOE should document the efforts that were made to locate sources of good quality rock.
GEOLOGY /GE0 MORPHOLOGY GS/1 - Tailings Embankment, Calculation No. 10-536-08-00 i
Sheet 4 of this calculation states that the disposal cell excavation will be limited to a depth of no greater than elevation 4,115 feet and will avoid excavation into the Cedar Mountain Formation.
Based on drawings and core data provided to the staff during the September 15, 1987 on-board preliminary design review meeting, this condition appears unrealistic.
In a telephone conversation with J. Grimm (October 23,1987), NRC, R. Rager, DOE / TAC acknowledged that the calculation presented in the design document I
is incorrect and that the tailings embankment will be founded in the Cedar I
Mountain Formation, barring future alterations in the design.
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DOE should assure that revisions to the design documents reflect this change.
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