ML20027C109
| ML20027C109 | |
| Person / Time | |
|---|---|
| Issue date: | 09/20/1982 |
| From: | Scarano R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Campbell R ENERGY, DEPT. OF |
| References | |
| REF-WM-58 NUDOCS 8210120574 | |
| Download: ML20027C109 (3) | |
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' Reg IV WMUR w/f WMUR r/f NMSS r/f KHamill WMUR:KJH RScarano WM-58 Linehan DMartin HPettengill Richard H. Campbell, Project Manager RBrowning UMTRAP Project Officer JMartin U.S. Department of Energy BFisher Albuquerque Operations Office P.O. Box 5400 Albuquerque, New Mexico 87115
Dear Mr. Campbell:
This letter provides NRC's conments on the Draft Remedial Action Concept Paper for the uranium mill tailinos site at Shi rock, New Mexico.
The comments noted in the enclosure are in many cases similar to comments previously made on the remedial action concept papers for the Salt Lake City, Utah and Durango, Colorado sites.
If you have any questions regatding these comments please contact Kathleen Hamill of my staff on FTS 427-4115.
Sincerely, ORIGINAL SIGNED By Ross A. Scarano, Chief Low-Level Waste Licensing Branch Division of Waste Management
Enclosure:
NRC Staff Coninents on August 1982 00E Shiprock RACP
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l ENCLOSURE I
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NRC STAFF COMMENTS ON AUGUST 1982 DOE SHIPROCK RACP 1.
pg.4(Sec.4.1): The Table 1 summary of EPA's interim remedial action cleanup standards indicates that remedial action would be required if Ra-226 concentrations on open lands were greater than 5 pCi/gm. This implies that remedial action would be necessary if measurements indicated that the total concentration was greater than 5 pCi/gm.
In view of the specific language of the EPA standard, which references concentrations " attributable to residual radioactive material from any designated processing site," NRC interprets the interim EPA standard of 5 pri/gm to be above background concentrations.
2.
pg. 7 (Sec. 4.3): The discussion of environmental factors to be considered in the evaluation of alternative options mentions the effects on potable ground water. The proposed EPA standard defines an underground source of drinking water to be an aquifer in which the groundwater contains less than 10,000 milligrams / liter to'a1 dissolved solids. Thus, it appears that EPA intended that water of a quality appropriate for other uses, such as agricultural uses, also be considered ar.d protected.
Various state water quality standards, such as Wyoming (which establishes 500 mg/l TDS for domestic use and 5000 mg/l TDS for livestock use) and New Mexico (which establishes a value of 1000 mg/l TDS for both domestic and agricultural use), provide evidence supporting this interpretation by establishing limits for use categories other than domestic drinking water well within the 10,000 mg/l value. Therefore, NRC staff considers use of the term " potable" ground water may too narrowly restrict the scope of the evaluation of potential impacts on groundwater.
3.
pg. 8 (Sec. 5):
It is stated that "The earth and rock materials needed for the cover would be obtained from a pit dug into the underlying Mancos Shale on the southwest side of the present south pile. This pit would then be filled with unusable borrow materials to above the groundwater level and then with tailings and other contaminated material from the north pile."
It is further stated on page 11 of the RACP that "...the presence of water beneath the piles (believed to be residual water drained out of the tailings), of washes adjacent to the piles and leading to the river, and of 10 to 20 feet of fractured shale on top of a solid Mancos Shale base indicates that there may be a need for additional protection against the possibiltiy that ground water would move through the
'ings and carry contamination offsite. A slurry wall around part or of the site would provide this additional protection."
It is not clear that the conclusions that, if necessary, a slurry wall will provide any necessary groundwater protection, is supported. A number of questions arise in connection with this which, if the conclusion is going to l
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be stated, should be addressed in the concept paper.
These questions relating principally to characterization of existing conditions include:
A)
How much liquid is presently contained in the tailings? Will release of liquids (i.e., seepage) from the tailings occur over next few years?
Pg.11 implies that the potential for future groundwater leaching of the tailings is the only reason for isolation measures. However, in view of the fact that the excavation will be backfilled to above the groundwater level, consideration of the slurry wall seems to imply some concern about the potential for seepage from the tailings.
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B)
Presuming that some potential for seepage exists, it would be considered approriate to address -- How deep the pit will be dug?
Where is the existing groundwater level? What is the nature of this groundwater? What will be the extent of backfill (i.e., how thick of a soil barrier will exist)?
4.
pg. 8 (Sec. 5): What is the reason for placing a 1 foot layer of gravel directly over the tailings?
5.
pg. 8 (Sec. 5): What is the basis for identifying 4-12 inch diameter rock for rip rap and indicating that the rip rap would extend 10-20 feet out from the toe of the slopes? Such restrictions on design in a conceptual document i
appear to be inappropriate.
6.
pg. 12 (Sec. 7-Table 3):
Information related to preliminary cost estimates, if it is to be included in the concept paper in support of judgements such as proposing a particular action, should be accompanied by at least a general discussion of the assumptions made in developing such estimates.
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