ML20148F510
| ML20148F510 | |
| Person / Time | |
|---|---|
| Issue date: | 02/09/1988 |
| 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-62 NUDOCS 8803280190 | |
| Download: ML20148F510 (3) | |
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.s RIFLE MEM0 1-FE8 0 91988 MEMORANDUM FOR: Myron Fliegel, Section Leader Operations Branch Division of Low-level Waste Management and Decomissioning FROM: Michael Tokar, Se(. tion Leader Technical Branch Division of Low Level Waste Management and Ceccmissioning
SUBJECT:
GE0 TECHNICAL ENGINEERING COMMENTS ON THE PfiELIMINARY DESIGN FOR THE RIFLE, C0 UMTRA SITES.
Enclosed are the geotechnical engineering comments on the Subcontract Documents, Volumes I thru III of the calculations, and the associated Appendices for the Rifle, C0 VMTRA Site, Phase II Preliminary Design.
Derek Widmayer of my staff performed this review.
Geotechnical engineering coments on Volumes IV and V will follow by COB today.
Griginsi Signed Dr Michael Tokar, Section Leader Technical Branch Division of low-Level Haste Management and Decommissioning
Enclosure:
As stated DISTRIBUTION:
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1 URANIUM MILL TAILINGS REMEDIAL ACTION PROJECT (UMTRAP)
RIFLE, COLORAD0 SITE GE0 TECHNICAL ENGINEERING REVIEW 0F PHASE II FRELIMINARY DESIGN DOCUMENTS Documents Reviewed: Subcontract Documents, Calculations, Volumes I through III, and Appendices A and C (dated: November,1987.)
Reviewad by: Derek A. Widmayer, Civil Engineer, LLTB REVIEW COMMENTS GT/1 - Disposal of Asbestos and Hazardous Waste Materiais The handling and disposal of asbestos and containers of hazardous materials with the tailings and other described contaminated and uncontaminated materials is mentioned in the subcontract documents (pages 02200-1and02200-18). There is no description or characterization of either the asbestos or the hazardous materials. A description of these materials, the quantities involved, and other important characteristics that ensure proper disposal of these materials should be included in future documents. The discussion should include infomation on any effect the inclusion of these materials will have on the design and the perfomance of the tailings embankment.
GT/2 - Preparation of Foundation Soils Cross-Section A in Drawing No. RFL-DS-10-0723 of the Phase II Design Documents l indicates large areas at both the north and south ends of the stabilized l tailings embankment where no apparent foundation preparation will take place.
However, tailings embankment details found in Drawing No. RFL-05-10-0724 appear to contradict this. Foundation preparation is indicated on the typical l detail of the south toe (Detail 2) and the apron (Details 1 and 3) drawings, i
This discrepancy should be corrected. Details of this foundation preparation should be included in future remedial action documents.
- GT/3 - Shear Strength Tests and Values
( In the NRC staff comments on the dRAP and the dEIS on the Rifle UMTRA sites, l staff had several concerns regarding the shear strength tests and values l reported in these documents. In reviewing the soil properties for design (Calculation No. 06-525-05-00), staff concludes that, for the most part, these concerns have not been addressed in the Preliminary Design documents. These
- concerns are reiterated below. These concerns must be addressed in future design or remedial action documents.
l (a) The shear strength value reported for the foundation soil is still based on only one laboratory test. Staff continues to recommend additional tests to fully characterize this mateiial.
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(b) The shear strength value reported for the unconsolidated-undrained triaxial test for the sand-slime tailings (perfonned on a sample from borehole is based on this lone laboratory test. Staff continues to recommend additional tests to fully characterize this material.
(c) The shear strength values reported for the foundation soils, remolded
("radon barrier") soils, and the tailings materials are all based on non-standard "staged" triaxial shear strength tests. Staff continues to be concerned over the use of this non-standard test, and continues to recommend the use of standard engineering practice where triaxial compression tests are performed on several samples of the same material at the same density and moisture content.
GT/4 - Subpile and Offpile Materials Design properties of the off- and subpile materials reported in Calculation No. 06-525-05-00 are assumed based on limited available information reported in the dRAP. The assumed values are within reasonable ranges of values, considering that these materials should be similar to the soils characterized at the Old and New Rifle sites. However, these materials make-up approximately 22% of the estimated total of all materials that will be disposed of, and the offpile materials will be placed over the tailings materials in a separate layer, as shown on the drawings in the subcontract documents. Therefore, these materials should be characterized separately and completely, and the use of assumptions justified if they will be used. These characterizations should appear in future design and remedial action documents.
GT/5 - Properties of Sand-Slime Mixtures Values for in-situ dry density, moisture content, and moisture content vs.
dry density (standard proctor test) reported in Calculation No. 06-525-05-00 for the sand-slime fraction of the tailings from the Old Rifle site are based on laboratory tests on either 2 (in the case of the in-situ dry density and the moisture content) or 1 (in the case of the standard proctor test) laboratory test.
The sand-slime fraction of the Old Rifle tailings will comprise approximately 12%
of the estimated total amount of tailings to be disposed of. Therefore, these values should be based on results from a more reasonable number of tests considering the significant contribution the material makes to the total amount of material.
These additional test results should appear in future design or remedial action documents.
GT/6 - Boring and Test Pit Identifications The identification numbers for borings 917, 918, and 919, have been changed on sheet 30 of Calculation No. 06-525-05-00. According to details provided in Appendix A of the Preliminary Design documents, these changes are erroneous.
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