ML19257B811
| ML19257B811 | |
| Person / Time | |
|---|---|
| Issue date: | 12/21/1979 |
| From: | Miller H NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Rookstool J PIONEER URAVAN, INC. |
| References | |
| REF-WM-20 NUDOCS 8001180412 | |
| Download: ML19257B811 (4) | |
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WASHINGTON, D. C. 20555 DEC 211979 Pioneer Uravan, Incorporated ATTN: Mr. John Rookstool Project Manager, San Miguel Project P. O. Box 151 Amarillo, Texas 79105 Gentlemen:
Enclosed please find a series of questions and requests for additional information which have been identified in our evaluation of the proposed San Miguel project. All of the information requested here concerns factors which will affect the tailings management scheme described in the Environmental Report (ER) and the Dames & Moore Design P.eport (DR).
Page/section numbers have been included when possible to assist you in understanding specific information in question.
Previously forwarded to you by letter dated December 5,1979,was the draft Regulatory Guide entitled " Calculational Models for Estimating Radiation Doses to Man from Airborne Radioactive Materials Resulting from Uranium Milling Operations." Please compile and submit the data outlined in Table A-1 of the draft Regulatory Guide providing all assumptions, calculations, and justifications. The submittal of this compilation is required to assure the preparation of a thorough and technically sound radiological impact evaluation.
If the information is incomplete, the NRC staff will have to make assumptions which might result in an overly conservative radiological assessment.
Your complete and timely response to these questions (within 2-3 weeks) is important for keeping us on our schedule for review of your proposed project.
If you have any questions regarding this request for information, please contact Kathleen Hamill of my staff (301-427-4103).
Sincerely, WA H.
. Miller, Section Leader Uranium Recovery Licensing Branch Division of Waste Management
Enclosure:
As stated 1770 152 8 00118 0 M/.2__.
Ouestions Regarding Impacts to Water 1.
It is stated that a seepage analysis was conducted to estimate the amount of seepage losses from the evaporations ponds and that the results indicate that total maximum seepage will be on tie order of five gallons per minute. Describe the methodology and provide the detailed calculations used in estimating the seepage from the evaporation ponds.
It is further stated that six inches is the assumed thickness of contaminant migratitn in the bottom of the evaporation ponds.
Expl ai n how contaminant migration was detarmined or predicted. Describe the methodology, assumptions, soil properties, and other inputs used in the detemination.
Describe in detail the clay liner permeability tests and include discussion of the cation exchange capacity, buffering capacity and coefficients of the linar and underlying soils.
In addition, provide a seepage analysis for the tailings area.
2.
It is stated in the ER on pg. 2.6-3 that field permeability values for the Mancos shale at the site range from near zero to 1,800 ft/yr, depending on the degree of fracturing. Generally, it is stated that 0.17 ft/yr is the average value for the unfractured material.
(In the Dames & Moore DR, 200 ft/yr is stated as the average pemeability based on borings drilled during the geotechnical investigation.) The high variability in secondary permeability, indicated in the ER, makes it difficult to justify use of the Mancos shale alone in the tailings area without further compaction and/or treatment. Unless, it can be demonstrated through the pump tests referred to below (in item 3b) that high secondary permeability is not typical of the material under-neath the proposed tailings disposal area, describe what design changes can be made to ensure meeting the objective that seepage be minimized.
3.
Although 'penneability and hydraulic gradient values are stated, no real definitive infomation is presented on groundwater movement within the Mancos shale fonnation. At the site visit, it was verbally stated that water movement consists solely of infiltration followed by subsequent evaporation during the drier months, i.e., little lateral movement actually occurs.
If this is true, it needs to be substantiated and adequately documented, as most of the information assembled in the Dames & Moore DR f ndicates southwesterly flow, a.
All discharge points for the Mancos shale aquifer should be identified.
Both Nicholas Wash and an ephemeral spring were stated as possibilities at the site visit.
This should be sub-stant iated.
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-- b.
Aquifer perfomance data is needed as discussed at the (November 18,1979) meeting following the site visit.
Pump test data should be provided to define the flow characteristics of the Mancos shale aquifer.
c.
Documentation should be provided concerning the lack of hydraulic connection between the Mancos shale and the underlying Dakota Sandstone. The Dames & Moore DR does not address this adequately.
4.
What is the possiblity of moisture release from within the tailings resulting from overburden pressure? Might a " squeezing effect" release more water for subsequent seepage than initially considered?
Questions Regarding Waste Management Capacity 5.
Quantify the miscellaneous solid wastes expected to be buried with the tailings at the time of final decommissioning (e.g., soils from evaporation ponds, ore pads, access roads, etc.,).
Demonstrate that storage volume in trenches will be adequate.
6.
It is stated in ER 3.2-8 that the amount (30 percent of the total raffinate flow) of internal recycle is based on current metallurgical testwork and operating data from other mills in the area with similar process designs. Provide information to support this figure. Al so,
provide any information available from the referenced pilot plant pro-gram pertaining to the possible internal recycle of solutions.
7.
It is stated (ER 3.3-3 and Figure 3.2.1) that the liqiuid waste flow will be in the range of 152 to 303 gpm depending on the technical feasibility of the internal recycle and waste treatment facilities.
If the Selected Membrane Mineral Extraction (SMME) system will not be employed (and it is stated on 3.2-9 that its use appears doubtful),
1 the liquid waste flow will probably be close to the upper value of 303 gpm. However, in ER 3.4-13, it is stated that an assumed net water discharge rate of 200 gpm was used in proportioning the ponds.
Please clarify this apparent contradiction.
In addition, Figure 3.4-6 shows that both north and south ponds are going to be filled to capacity significantly before the end of milling operations.
Explain this situation in terms of the remaining years of operation.
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.., Other Miscellaneous Questions 8.
Provide a detailed water balance (quantity of water withdrawn from surface / ground water, evaporation, seepage, etc.,).
To detemine the impacts of consumptive use of water, provide a water quality analysis of the aquifer from which water will be removed for use in the process.
9.
Provide the available hydrogeological data from the referenced investi-gations (ER3.2-8) which were scheduled to be completed by February,1979.
- 10. Please provide a 2-foot contour interval map and cross-sections outside the site which illustrate the 100-year flood boundary.
- 11. Clarify what the final slopes of the tailings disposal trenches will be.
A reference is made in ER 9.4-1 that slopes will be 4:1, wh2reas all other references are to 5:1 slopes, the latter being consistent with proposed regulations. Will all side slopes be covered with rip rap?
- 12. What are the potential effects of an earthquake on the tailings disposal area over the long-tem? Consider the long-tem potential for liquefaction of the tailings.
13.
It was indicated during the course of the November 18, 1979, site visit that design of the tailings disposal system has been constrained by the supposition or belief that tailings must be kept above the groundwater.
However, it was also stated that the Mancos shale, in which the tailings are to be placed, is a very tight fomation; in essence, a static system.
Therefore, as NRC staff and consultants indicated at the site visit, the feasibility of deeper excavation, which would permit placement of tailings and cover below-grade to promote long-tem stability, should be evaluated.
- 14. Please specify criteria for selection of the 19 borings for field pemeability tests since 28 borings were made.
- 15. Dames & Moore DR C Reference is made to soil samples which were collected for radiological analysis. What are the results of the testing done on these samples?
- 16. Dames & Moore DR D There is not enough infomation to pemit an evalu-ation of the proposed, unenclosed tailings conveyor system. Please provide a detailed analysis of the operating plan for the system which ensures windblown tailings will not result, including additional infomation on the physical characteristics (e.g., moisture content, particle size) of the tailings as they are transported via conveyor to the disposal trenches.
As discussed at the site visit, provide any available infomation regarding the characteristics of tailings which can be derived from tests done at the mini-mill.
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