ML20195G681
| ML20195G681 | |
| Person / Time | |
|---|---|
| Issue date: | 05/27/1988 |
| From: | Tokar M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Fliegel M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-72 NUDOCS 8806280096 | |
| Download: ML20195G681 (8) | |
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MAY 2 71988 l'EMORANDUM FOR: Myron Fliegel, Section Leader Operations Branch Division of Low-Level Waste Management ana Deconrnissioning, NMSS FROM:
Michael Tokar, Section Leader Technical Branch Division of low-Level Waste Management and Decommissioning, NMSS
SUBJECT:
SPOOK PRELIMINARY DESIGN REVIEW As requested, we have perforned a review of the Preliminary Design documents for the proposed remedial actions at the Spook site.
The review comments are presented in the attachment to this memo.
This review was performed by Banad Jagannath; please contact him should you have any questions.
ORtGNALMNEDBY Michael Tokar, Section Leader Technical Branch Division of Low-level Waste Management and Deconunissioning, NMSS
Enclosure:
As stated Distribution:
w/ enc 1.
w/ encl.
w/o encl.
'LLWM/SF SWastler RBanagart NMSS r/f MTokar MBell LLTB r/f BJagannath PLohaus JJSurmeier SBilhorn JGreeves
- see previous concurrence OFC :LLTB
- LLTB
- LLTB 2:
2....:............:............:.....
MAME :BJagannath* :MTokar *
- JSur,eier 2....:............:............:............:...........
DATE :05/ /88
- 05/ /88
- 05/7/88 2
0FFICIAL RECORD COPY 8806280096 880527 WN l
PDR WASTE g@
MEMORA UM FOR: Myron Fliegel, Section Leader Operations Branch Division of Low-Level Waste Management and Decommissioning, NMSS FROM:
chael Tokar, Section Leader Technical Branch Divit(Becommissioning,NHSS on of Low-Level Waste Management and
SUBJECT:
SP0OK PREL INARY DESIGN REVIEW As requested, we have performed review of the Preliminary Design documents for the proposed remedial actions t the Spook site.
The review comments are presented in the attachment to this.emo.
This review was performed by Banad Jago nath; please contact him should you have any questions.
Michael okar, Section Leader Technica Branch Division o Low-level Waste Man >]ement and DecoK. ssioning, NMSS
Enclosure:
As stated Distribution:
w/ encl.
w/ encl.
w/o encl.
LLWM/SF SWastler RBanagart NMSS r/f MTokar HBell LLTB r/f BJagannath PLohaus JJSurmeier SBilhorn JGreeves
~~
JFC
- LLTB
- LL1 1AME :BJagannath
- liTokar 3 ATE :05/26/88
- 054Lc/88 OFFICIAL RECORD COPY
- ~.
a' GE0 TECHNICAL ENGINEERING REVIEW C0ftMENTS PRELIMINARY DESIGN FOR REMEDIAL ACTION PLAN-FOR INACTIVE URANIUM MILL TAILINGS SITE AT SPOOK, WYOMING Review by: Dr. Banad Jagannath, LLTB, LLWM.
Documer.ts Reviewed (References):
1.
Uranium Hill Tailings Remedial Action Project, Spook, Wyoming; Subcontract Documents-Preliminary Design Review, April 1988.
2.
Uranium Mill Tailings Remedial Action Project, Spook, Wyoming; Information for Bidders-Preliminary Design Review, Volume 1, April 1988.
3.
Uranium Hill Tailings Remedial Action Project, Spook, Wyoming; Information for Bidders-Preliminary Design Review, Volume 2, April 1968.
4.
Uranium Mill Tailings Remedial Action Project, Spook, Wyoming; Calculations (UMTRAP)- Preliminary Design Review, April 1988.
5.
Uranium Hill Tailings Reniedial Action Project, Spook, Wyoming; Calculations (AML)- Preliminary Design Review, April 1988.
6.
Information for Reviewers, April 1988.
GEsTECHNICAL ENGINEERING COMMENTS 1.
Foundation for Tailings Embankment - page 2 of Reference 6.
The basic conceptual oesign of the UMTRA project is to place contaminated niaterial on a prepared foundation in the bottom of the Spook Pit and cover it
> with a low-permeability layer. The specifications require that the top six inches of the subgrade be at a minimum density of 90 percent standard proctor compaction. There is no other requirement such as the depth of the foundation material to be stripped and compacted, material to be used, or the minimum thickness of the compacted layer beneath the tailings embankment.
Details of all aspects of this foundation preparation task should be clearly shown in the contract drawings, and also included in the specifications.
The AML backfill (mine waste) will be placed on a prepared foundation layer of 3-feet-thick, compacted, fine grained material from the 800-mine waste pile.
The AML report (page 7A-23 of Appendix 7 to A;tL report) suggests that a 3-feet-thick compacted layer of fine grained material from the western portion of the 800 pile, 900 pile or material excavated from the northern channel may be used as a bedding cr liner beneath the tailings embankment.
This layer would result in the additional benefit of retarding the transport of contaminants through this layer by approximately 1,000 years.
Since DOE is committed to take all feasible measures to reduce the groundwater contamination, this recommendation in the AML report should be seriously considered for implementation.
(see comment on this item by groundwater hydrologist).
2.
AML backfill above tailings - page 2 of Reference 6.
The statement thot the upper 18 or more feet of backfill will have materials with less than or equal to 0.2 or 0.1 ppm of Se and 5.0 pCi/gm of Ra-226 or less is not consistent with the statements in the AML report that designate this material as Zone 3 material containing less than 20 pCi/gm of Ra-226.
The AML program considers material with less than 20 pCi/gm of Ra-226 to be a clean fill, whereas DOE /tJMTRA considers 5 pCi/gm of Ra-226 as the upper limit for a clean fill.
DOE should officially indicate which material is defined as residual radioactive material, low-grade ore or clean overburden.
NRC staff
e s understands that radon flux calculations do not consider the effects of exhalation from overburden material.
However, DOE is considered responsible for the long-term stability of the residual radioactive material, and thus are responsible for ensuring that overburden placement does not compromise the integrity of the tailings embankment.
00E should provide assurances that the overburden material will be placed according to design specifications because of the relationship between overburden placement and tailings stability.
3.
Construction Sequence - page 3 of Reference 6.
The present thinking of the DOE is that both the DOE /UMTRA program and the State /AML program will be constructed by the same subcontractor, and portions of both may be constructed concurrently.
The preliminary design calls for a 1.5 feet thick low-permeability layer to cover the tailings embankment which has a side slope of 2H:1V.
This in turn will be covered with mine waste backfill placed under the AML program.
The tailings and the AML backill are specified to be compacted to 90 % standard proctor density whereas the thin (1.5 feet thick) low-permeability layer, sandwiched between these two materials, is specified to be compacted to 95 % standard proctor density.
This is difficult to accomplish even if a single subcontractor works concurrently on both the UMTRA and AML projects.
The DOE should present details in the firal RAP on how this will be constructed to strict ccmpliance with the design thickness and compaction specifications presented in this preliminary design.
Consideration may be given to the options of either increasing the thickness of the low-permeability layer or changing the compaction specifications.
4.
Radon Barrier Design - Calculation 07-720-00 of Reference 4 The design of the radon barrier and value of the hydraulic conductivity of the infiltration barrier layer, presented in the preliminary design, are based on
l' very limited site specific test data, and are therefore considered to be preliminary. The NRC staff expects the design to be presented in the final RAP to be supported by adequate test data.
5.
Construction Sequence - Item 1.3.C.7 page 01010VA-4, Reference 1 Item 7 implies that the tailings embankment construction will be completed before initiating construction of the low-permeability cover layer. This contradicts the current thinking of concurrent construction of both VMTRA and AHL programs by the same subcontractor. This item should be modified to reflect the current thinking of concurrent construction.
6.
Borrow Area Location - Item 1.4.A, page 01010U-4, Reference 1.
Contrary to the statement in the above item, the location of the borrow area A is not shown in the subcontract drawings. The location of the borrow area shoulo be shown in the subcontract drawings.
7.
Unidentified Waste - Item 1.2.C.4, page 020500-2, Reference 1.
For disposal of unidentified waste, reference is made to the standards of the Colorado Department of Health. The reference should be to the standards of the Wyoming Department of Health as the site is in the state of Wyoming.
8.
Equipment - Item 2.4, page 02200U-9, Reference 1.
This section provides guidance on the equipment intended for compacting granular meterial only.
However, there is clayey material to be compacted for the low-permeabi?ity cover layer over the tailings embankment.
The t
.. specifications should include guidance, similar to that provided for the vibratory roller, for the equipnent to be used for compacting the low-permeability cover material.
9.
Compaction Requirements - Item 3.5.C.2, page 022000- 16, Reference 1.
This item specifies the mois iire content range for compaction of the low-permeability cover layer only.
To be consistent, this item should also provide guidance on the moisture content range for compaction of the tailings material also.
- 10. Backfilling Mine Drif ts - Item 3.6. A, page 02200U-17, Reference 1.
The specifications for this item of work are very ger.cral and do not provide any specific details on the material to be used, placement control etc..
This section should be revised to provide detailed specifications for this item of work.
4 11.
Field Quality Control-Item 3.7.B.1.b, page 02200U-17, Reference 1.
The testing frequency for the low-permeability cover material is one test for evt:ry 500 cyd of material placed.
Since the volume of this material to be placed is only 13,600 cyd and the construction sequence may require placement of a limited quantity at a time, the testing requirement should include that at I
least one test be performed every day that over 150 cyd. of material is placed f
and a minimum of one test be performed for every lift and every full shift of compaction operation.
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Payment for Inspection Pits-Item 1.6.B.5, page 02200A-6, Reference 1.
The inspection and testing frequencies for the AML material to be placed directly above the DOE tailings erbankment should be identical to those used by the DOE for placement of cover material on UMTRA projects.
- 13. Drawir9 SPK-AML-PS-10-0206.
This drawing should show the tailings embankment constructed under the DOE /UMTRA contract, as this will impact on the volume of backfill to be placed under the AML program.
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