ML20198B652
| ML20198B652 | |
| Person / Time | |
|---|---|
| Issue date: | 02/12/1986 |
| From: | Garcia P, Pettengill H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| Shared Package | |
| ML20198B636 | List: |
| References | |
| REF-WM-186, TASK-TF, TASK-URFO NUDOCS 9801070025 | |
| Download: ML20198B652 (4) | |
Text
._ .. - - - ._- _- .- .- __ - . . -
DISTRIBUTION URF0 s/f URP WM 186 URF0 r/f DBangart, RIV
'.URP WM-186/PJG/86/01/30/0- W rcia> & '
3 GKonwinski LLW Branch, WMLU FEB 121986 BBrown, RIV WDEQ(2)
JHaes, RCPD, WY URF0:PJG-URP WM-186 040WM186110E MEMORANDUM FOR: File URP WM-186 FROM: Pete J. Garcia, Project Manager
-Licensing Branch 1 Uranium Recovery Field Office, Region IV O
SUBJECT:
RECLAMATION OF UNNAMED HEAP LEACH SITE
' Background By letter dated November 4,1985, Energy Fuels Nuclear (EFN) submitted for NRC review and approval a proposed reclamation plan for an unnamed heap leach site located in the Gas Hills area of Fremont County, Wyoming.
The original operation was conducted by Western Nuclear Inc., but the site is currently not under an active license. The. reclamation of the site, however, will be voluntarily performed by EFN, the current owner of the-site. The plan submitted by EFN was in response to a letter from the.
~ NRC' dated September 24, 1985. ;
The old heap leach operation represented an early effort to heap leach low grade' uranium ore. The remaining ores, the plastic liner, and the Q'- _
drain pipes, as well as some of the underlying natural soils, were removed in 1982 by EFN and disposed in an adjacent mine dump overburden
_ pile. The staff was unable to establish the exact cciantity or location of these materials, but it is known that the disposed materials were covered by a minimum of 30 feet of overburden soils, and they are well above any water table. Also, the staff has previously reviewed this disposal-and concluded that little or no potential for release to the environment exists. The staff further concluded that a long-term possession license in accordance to Section 83 of the Atomic Energy _ Act was not warranted in this case.
9901070025 860212 PDR WASTE WM-186 PDR .
C : : : : : : :
ME :
l . . . : _ _ _ . . _ _ _ _ _ _ _ :: . . . _ _ _ _ _ _ _ .: . :: _ _ _ _: _ _ _ _ _ _ _ :: . _ _ _ _ _
l TE :86/02/07 : : : : : :
l.
[
m-n g- s.A V 1
URP WH 186/PJG/86/01/30/0 However, recent soil samples taken by EFN indicate that Ra-226 concentrations in excess of 10 CFR 40 standards still exist in underlying soils at the original heap leach site. The proposed reclamation plan, therefore, is intended to meet regulatory limits for reclamation of similar heap leach sites under active license and still contain residual byproduct material.
Discussion The area of the old leach pad to be reclaimed consists of approximately 2.8 acres. The proposed reclamation plan includes the placement of 1 foot of cover over all the contaminated soil areas and the construction of a diversion ditch designed to convey flows resulting from a 100-year n
V storm over a 1.8 acre watershed above the site. The top of the reclaimed area will be graded to a very gentle 2% slope and blended into the natural topography. Future mining of an adjacent pit would subsequently result in the placement of additional cover over the old heap leach site.
A plan view of the reclamation and surrounding area is shown on the map accompanying the November 4, 1985 submittal.
The staff review of the proposed reclamation plan included calculations to determine the amount of cover necessary to attenuate radon emanation from the remaining contaminated soil to less than 20 pCi/me /sec in accordance with 10 CFR 40. Soil samples taken by ErN at five locations .
I within the contaminated area show an average Ra-226 content of l
22.1 pC1/g, with the results ranging from 5.7 to 28.3 pCi/g. The staff used the high v. of 28.3 pCi/g and an assumed layer thickness of 1 foot in the ca. .ations to conservatively estimate radon flux from the r
i contaminated soil. Tne diffusion coefficient of the contaminated !
material was calculated using Equations 12 and 13 of NUREG/CR-3533, f (^)
" " Radon Attenuation Handbook for Uranium Mill Tailings Cover Design." The radon flux from the contaminated soil was then calculated using Equation 3 of NUREG/CR-3533 The calculations show the radon flux from the contaminated soil to be approximately 5.8 pCi/mr /sec, well below the existing standards already applied to licensed sites. Thus, a soil cover is not necessary to meet the required radon attenuation standard.
The staff review also included an evaluation of the amount of cover necessary to achieve isolation of the contaminated soil for a period of 1000 years in accordance with 10 CFR 40 Sheet water and wind erosion
-analyses were conduc'ed utilizing Soil Conservation Service methods and erosion parameters specific to the area in which the site is located.
- C : : : : : :
\ME : ..---__..:....________:..__________:
iTE :86/02/07 : : :
metmmwnn: e ~ '
G%
p/ _,
.=
URP Wi-186/PJG/86/01/30/0 Vegetation parameters were based on values recommended by Mark Moxley of the Wyoming Department of Environmental Quality.
The erosion analyses conducted conservatively estimate that wind and sheet erosion over a 1000-year period would result in the removal of 0.5 feet and 0.06 feet of cover, respectively. Multiplying the cumulative amount (0.56 feet) by a factor of safety of 1.5 results in a total required thickness of 0.84 feet. The proposed 1 foot thickness is therefo.e acceptable.
Finally, the staff perfonned an assessment of the potential for erosion in the diversion ditch, due to the proximity of the ditch to the reclaimed area. The channel proposed by EFN is a triangular channel,
,m 4 feet wide and 1.5 feet deep. As stated previously, the ditch was V designed by EFN to convey flows from a 100-year stonn. Larger ,torms, including the Probable Maximum Flood, would overtop the diversion channel and flow as sheet flow over the reclaimed area. The staff perfonned an analysis of flow velocities during a 100-year flood which could exist in the channel using Manning's equation and an 'n' value of 0.022, which is a conservative value for an earthen channel.
l The staff analysis indicates that velocities in the channel would be about 4.3 feet per second (fps). Since the channel is only designed to convey a 100-year flood, velocities in excess of 4.3 fps would exist in the channel many times over a 1000-year period. Velocities in the 4_6 fps range are generally considered marginally erosive. Based on the l
number of times the channel would experience velocities in that range
- over a 1000-year period and the fact that the channel is located adjacent to the reclaimed site, the staff concludes that the deliberate A concentration of flood flows by constructing a channel only serves to
[
V increase the potential for impact to the reclaimed area. Without the diversion channel, the potential for concentrations of flow which could erode the reclaimed area is substantially reduced. The staff therefore concludes that the diversion channel should not be constructed, and that the confluence of the reclaimed area and the upstream drainage area should be graded so that sheet flows would occur over the entire reclamation area.
As cdentified in earlier staff reviews (September 24,1985), the unnamed heap leach site is located in a very remote area of Wyoming. Due to the location of the site, the very small areal extent of the contamination (2.8 acres), the low level of contamination ( 28.3 pC1/g), and the small quantities of contaminated soils involved, the staff concludes that
- E
- : :
E :86/02/07 : :
URP WM-186/PJG/86/01/30/0 '
4-transfer of title to the reclaimed heap leach site area is not necessary or desirable to minimize any impact to public health and safety or the environment. The staff further concludes that a long-term possession license in accordance with Section 83 of the Atomic Energy Act of 1954, as amended, is not necessary.
Conclusion Based on the review discussed above, the staff concludes that the reclamation plan proposed by EFN for the unnamed heap leach site, as modified by the staff, meets the requirements of 10 CFR 40, and that
!icensure of the site following completion of this reclamation activity is not warranted. It is recommended the staff need only verify that the reclamation is completed.
S i n
~
Pete J. Garcia, Project Manager Licensing Branch 1 7 Uranium Recovery Field Office, RIV t Approved by:
l Edward F. Hawkins, Chief Licensing Branch 1 Uranium Recovery Field Office, RIV Approved by:
Harry J. Pettengill, Chief O 'iceasia9 areach 2 Uranium Recovery Field Office, RIV Case Closed: 040WM186110E Ah-C : t RF0 : R /) : . RF0 : : -
.[/.....:._.6......:_
.: ..g...:...______..:_....______
ME : PGarcia/lv: G' rinski :
EHawkins :HPett ill : B : :
TE :86/02/07 $ g. ._......______
...:__.......___..... Nd [ 2/p' ..__....._._. &.._ F_
A[I : :
_ - _ _ _ _ _ _