DRC-2008-002261 - 0901a0688075feaa

Environmental Report Support of Consfiuction
Cell 4b
Utatr
Prepared by Denison Mines (USA) Corp.
t050 tZft Street, Suite 950-
Denver, Colorado 80265
White Mesa ium Mill
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April 30,2008
Introduction
Denison Mines (USA) Corp. is seeking an amendment to its' Radioactive Materials
License, No. UTI900479 in order to obthin UDEQ's approval to construct, operate and
(when operations are complete) reclaim a proposed new tailings impoundment at its
White Mesa Uranium Mill, Cell 4b. The construction of the Cell 4b is an essential
element of future operations at the White Mesa Mill as its construction is necessary in
order to continue providing sufficient impoundment surface area for the evaporation ofMill processes water. This Cell also provides additional tailings capacity which is
necessary to accommodate the tailing volume associated with routine ore processing
operations. While the new cell has not yet been constructed, it was contemplated,
described and assessed previously, being a critical component of the initial 1978 NRC-
FEIS and attendant licensing of the facility. More specifically, the initial environmental
analysis and license application for the facility contanplated six tailing cells; operating
cells 1, 2 and 3, as well as 3 additional 80 acre cells, Cells 4, 5 and 6. With the
construction of Cell 4a (40 acres), Cell 4b will consume the second 40 acres of the
previously authorized 80 acre Cell4.
The information required for an amendment to the Mill's Radioactive Materials License
is found at R313-24-3. More specifically, the regulations state the following:
(l) Each new license application, renewal, or major amendment shallcontain an environmental report describing the proposed action, a
statement of its pu{poses, and the environment affected. The
environmental report shall present a discussion of the following:
(a) An assessment of the radiological and non-radiological impacts to the
public health from the activities to be conducted pursuant to the license or
amendment;
O) An assessment of any impact on waterways and groundwater resulting
from the activities conducted pursuant to the license or amendment;
(c) Consideration of alternatives, including altemative sites and
engineering methods, to the activities to be conducted pursuant to the
license or amendment;
and
(d) Consideration of the long-term impacts including decommissioning,
decontamination, and reclamation impacts, associated with activities to be
conducted pursuant to the license or amendment.
In order to fulfill the requirements above, Denison considered and used the information
topics and format cited by NRC in its guidance document NUREG 1359 for its recent
License Renewal Application. Because the Renewal Application provided current
environmental information and assessments, the scope of this Environmental Report can
be limited in some respects, focusing on pathways and assessments directly related to theconskuction of the new tailings cell. Accordingly topical headings suggested byNUREG 1359 have been included in this document; however, where p.*io*ty providei
information is sufficient and unaffected by this bmendment request, the prior information
is incorporated by reference. Denison's assessment of the pathways to be considered for
construction of cell 4b is principally focused on the examination of potential airborne
releases from the pond and the groundwater considerations tlpically attendant to the
design of a tailing cell. It is important to note that UDEQ has approved the design andconstruction of directly adjacent and nearly completed Cell 4a. The liner design andunderllng ground conditions for cell 4b me identical to those of cell 4a.
. Table of Contents
lntroduction
Table of Contents
lndex of Figures.1.0 Site Location and Layout.2.O Climate and Meteorology...
1.1 Regional Climate.
1.2 Onsite Monitoring Program...
3.0 Use of Adjacent Lands and Water.
4.0 Population Distribution and Socioeconomic Profile.
5.0 Topography...... i.......
6.0 Geologic Setting...
6.1 Regional Geology...
6.2 Iocal Geology.6.3 Site-Specific Geologic Setting..
7.0 Hydrologic Setting
7.1 Perched Zone Hydrogeology.
7.2 Perched Groundwater Flow..7.3 Perched Hydrogeology (Down-gradient of Tailings Cells..7.4 GroundwaterQuality.
8.0 Ecological Resources and Biota.
8.1 Te,rrestial.
8.2 Aquatic and Wetland Biota.....
9.0 Background Radiological and Non-Radiological Characteristics..........
10.0 Environme,ntal Effects Related Directly to the Construction of Cell 4bl0.l Groundwater Pathway Impact...
10.2 Proposed Additional Groundwater Monitoring....
10.3 Radiological Impact Related Directly to the Construction of Cell4b
10.4 Radiological Monitoring Assessment...
I 1.0 Alternatives.....
I1.1 Issuance of Amendme,nt for Cell 4b....
I1.2 No Action Alternative
I I .3 Alternatives Considered But Eliminated.....
I I.4 Cumulative Effects......
11.5 Comparison of Predicted Environmental Impacts.
11.6 Updates and Changes to Factors That May Cause Reconsideration of
Altematives.......
12.0 Costs and Benefits......
13.0 Mitigaiton of Impacts...
14.0 Long Term Impacts....
Appendix A
Site Hydrogeology Estimation Of Groundwater Travel Times and Recommended
Additional Monitoring Wells For Proposed Tailings Cell4BWhite Mesa Uranium Mill
Site Near Blanding, Utah
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Appendix B
Dose Assessment Pertaining to the Proposed Development of New Tailings Cells For the
White Mesa Uranium Mill, SENES Consultants, Hydro Geo Chem, Inc
Appendix C
Review of Environmental Monitoring Program, SENES Condultants
Index of Fisures
Fisure
Figure I
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure l0
Figure I I
Figure 12
Location Map White Mesa Mill
White Mesa Mill Land Map
White Mesa Wind Rose
Population in the Project Vicinity
Local Topography
Generalized Stratigraphy of Whit Mesa Mill
Approximate Elevation Top of Brushy Basin
Kriged 4ft Quarter Water Levels
Approximate Location of Ruin Spring
Depth to Perched Water
Stock Watering Pond Locations
Reclamation Cover Grading Plan for Cell 4b
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1.0 Site Location and Layout
The Mill is regionally located in central San Juan County, Utah, approximately 6 miles (9.5 km)
south of the city of Blanding. The Mill can be reached by taking a private road for
approximately 0.5 miles west of Utah state Highway l9l. See Figure 1.
Within San Juan County, the Mill is located on fee land and mill site claims, covering
approximately 5,415 acres , encompassing all orpart of Sections 21,22,27,28,29,32, and 33 of
T37S, P.22F,, and Sections 4, 5, 6, 8,9, and 16 of T38S, P.22F,, Salt Lake Base and Meridian.
See Figure 2.
All operations authorizedby the License are conducted within the confines of the existing site
boundary. The milling facility currently occupies approximately 50 acres and the current tailings
disposal cells encompass another 250 acres. See Figure 2.
The resident currently nearest to the milling facility is located approximately 1.2 miles (1.9 km)
north of the Mill site, just north of air sampling station BHV-I. See Figure 2.
2.0 Climate and Meteorolory
2.1 Reeional Climate
The climate of southeastern Utah is classified as dry to arid continental. Although varying
somewhat with elevation and terrain, the climate in the vicinity of the Mill can be considered as
semi-arid with normal annual precipitation of about 13.4 inches. Most precipitation is in the
form of rain with snowfall accounting for about 29o/o of the annual total precipitation. There are
two separate rainfall seasons in the region, the first in late summer and early autumn (August to
October) and the second during the winter months (Decernber to March). The mean annual
relative humidity is about 44 percent and is normally highest in January and lowest in July. The
average annual Class A pan evaporation rate is 68 inches (National Oceanic and Atmospheric
Administration and U.S. Department of Commerce, 1977), with the largest evaporation rate
typically occurring in July. This evaporation rate is not appropriate for determining water
balance requirements for the tailings management system and must be reduced by the Class A
pan coefficient to determine the later evaporation rate. Values of pan coefficients range from
600/o to 8lo/o. Denison assumes for a water balance calculations an average value of TOYo to
obtain an annual lake evaporation rate for the Mill area of 47.6 inches. Given the annual average
precipitation rate of 13.4 inches, the net evaporation rate is 34.2 inches per year.
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Figure 2
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The weather in the Blanding area is typified by warm summers and cold winters. The mean
annual temperature in Blanding is about 50" (F). January is usually the coldest month and July is
usually the warmest month.
Winds are usually light to moderate in the area during all seasons, although occasional stronger
winds may occur in the late winter and spring. The predominant winds are from the north
through north-east (approximately 30 percent of the time) and from the south through south-west
(about 25 percent of the time). Winds are generally less than 15 mph, with wind speeds faster
than 25 mph occurring less than one percent of the time. The National Weather Service Station
in Blanding, Utah is located about 6.25 miles north of the Mill. Data from the station is
considered representative of the local weather conditions (1978 ER, Section2.7.2). However, as
an element of the pre-construction baseline study and ongoing monitoring programs, the Mill
operates an onsite meteorological station, described in greater detail below. Further details about
weather and climate conditions are provided in the 1978 ER (Section 2.7) and in the FES
(Section 2.1). The 1978 ER and FEIS are resource documents, incorporated here by reference.
2.2 On Site Monitorins Proqram
On-site meteorological monitoring at the Mill was initiated in early 1977 and continues today.
The original purpose of the meteorological monitoring program was to document the regional
atmospheric baseline and to provide data to assist in assessing potential air quality and
radiological impacts arising from operation of the Mill.
After the Mill construction was completed, the monitoring programs were modified to facilitate
the assessment of Mill operations. The current meteorological monitoring program includes data
collection for wind speed, wind direction, atmospheric stability according to the standard
Pasquill scheme (via measurernents of deviations in wind direction, referred to as sigma-theta),
and precipitation as either rain or snow. The recorded on-site meteorological conditions are
reported to Denison on a serni-annual basis and are described in semi-annual reports prepared for
Denison and maintained at the Mill. Figure 3 shows the windrose for the Mill site during the
period of January - December 2007, the most recent full year of compiled meteorological data.
3.0 Use of Adjacent Lands and Water
Approximately 65.8oh of San Juan County is federally owned land administered by the U.S.
Bureau of Land Management, the National Park Service, and the U.S. Forest Service. Primary
land uses include livestock grazing, wildlife range, recreation, and exploration for minerals, oil,
and gas. Approximately 22oh of the county is Native American land owned either by the Navajo
Nation or the Ute Mountain Ute Tribe. The area within 5 miles of the Mill site is predominantly
range land owned by Blanding residents. The Mill site, including tailings cells, encompasses
approximately 3 00 acres.
4.0
A more detailed discussion of land use at the Mill site, in surrounding areas, and in southeastern
Utah, is presented in the FES (Section 2.5). Results of archeological studies conducted at the site
and in the surrounding areas as part of the 1978 ER are also documented in the FES (Section
2.s.2.3).
Population Distribution and Socioeconomic Profile
Demographic information is generally derived from information obtained by the U.S. Census
Bureau. These records are updated on a five year frequency for population centers which exceed
65,000 people and on a ten year frequency for lesser populations. As such, the local population
update for the area of interest was last recorded in the year 2000, and it is that data base which
was utilized to formulate the danographic information provided in the recent license renewal
effort and this report. According to the 2000 census, the population density of San Juan County,
in which the Mill is located, is 1.8 individuals per square mile. By comparison, the statewide
density is greater than27.2 persons per square mile. The town of Blanding, Utah, approximately
6 miles north of the Mill, is the largest population center near the Mill site, with 3,162 persons.
Approximately 5 miles southeast of the Mill site is the White Mesa community, where
approximately 277 Ute Mountain Ute tribal mernbers reside. See Figure 4. The Navajo
Reservation is located approximately 19 miles southeast of the Mill. The nearest community on
the Navajo Reservation is Montezuma Creek, a community of approximately 507 individuals in
Utah. The nearest resident to the Mill is located approximately 1.5 miles to the north of the Mill,
near air monitoring station BHV-I.
Table I provides population centers located within 50 miles of the Mill site.
Table l-Population Centers Within 50 Miles of the Mill Site
Populetion Center 2000 Population Distance From Siteo
(miles)
Blandine. UT 3.162 6
White Mesa. UT 27',t 4
Bluff. UT 320 l5
Montezuma Creek. UT 507 20
Aneth. UT s98 27
Mexican Hat. UT 88 30
Monticello- UT 1.958 2',1
Eastland/Ucolo. UT 249'32
Dove Creek, CO 698 37
Towaoc. CO 1.097 50
'2ooo census
2 Approproximate distance from Mill site by air
3 Based on l97E population estimate
San Juan County, Utah, is the largest and poorest county in Utah. As of Decernber 2006, the
unernployment rate in San Juan County was 4.9yo, compared to 2.60/o for Utah as a whole, and
4.5o/o for the nation as a whole. When operating, the Mill is one of the largest private employers
in San Juan County, ernploying up to 60-140 full time anployees. As
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Figure 4
Population in The Project Vicinity
2000 Ce,nsus
such, the Mills employees represent a significant economic base for the city of Blanding and
rural residents of San Juan County. In addition, the Company pays local taxes to San Juan
County, further supporting the development of the local economic base. The Mill also provides
income to local minorities, typically ernploying a high percentage of minority workers rangrng
from 45-75olo Native Americans
Since its inception in 1980, the Mill has run on a campaign basis, in each case rernaining on
standby pending accumulation of sufftcient ore stockpiles to justify a milling campaign.
Ctrrently, Mill employees are predominantly residents of San Juan County, or residents of
neighboring counties who commute to the Mill on a daily basis. Historically, the Mill has drawn
upon such residents of San Juan County and neighboring counties for each milling campaign,
rather than relying upon an influx of workers to the area. As a result, Mill campaigns have not
given rise to any unusual demands on public services or resulted in any cultural or
socioeconomic issues for the surrounding areas-
5.0 Topography
The Mill site is located on a gently sloping mesa that, from the air, appears similar to a
peninsula, as it is surrounded by steep canyons and washes and is connected to the Abajo
Mountains to the north by a narrow neck of land. On the mesa, the topography is relatively flat,
sloping at less than one (1) percent to the south and nearly horizontal from east to west. See
Figure 5.
6.0 Geologic Seffing
6.1 Regional Geoloey
The Mill site lies within a region designated as the Canyon Lands section of the Colorado
Plateau physiographic province. Elevations in the region range from approximately 3,000 feet in
the boffom of canyons to over 11,000 feet among the peaks of the Henry, Abajo and La Sal
Mountains. The average elevation for the area, excluding deeper canyons and isolated mountain
peaks, is about 5,000 feet.
The sedimentary rocks exposed in southeastern Utah have a total thickness of approximately
6,000 to 7,000 feet. These sedimentary units range in age from Pennsylvanian to Late
Cretaceous; older rock units which underlie those of Pennsylvanian age are not exposed in the
Mill site area.
Structural features in the Mill site area have been divided into three main categories on the basis
of origin or mechanism of the stress that created the structure. These categories are: (l) structures
related to large-scale regional uplifting or downwarping directly related to movernents in the
basement complex (the Monument Uplift and the Blanding Basin); (2) structures due to diapiric
deformation of thick sequences of evaporate deposits, salt plugs and salt anticlines (the Paradox
Fold and Fault Belt); and (3) structures formed due to magmatic intrusions (the Abajo
Mountains). A generalized stratigraphic column for the region is provided as Figure 6.
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Figure 5
Local Topography
And Location of Ruin Spring
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Figure 6
Generalized Stratigraphy of
White Mesa Mill
DAKOTA SANDSTONE
BURRO CANYON FORMATION
BRUSHY BASIN MEMBER
WESTWATER CANYON MEMBER
RECAPTURE MEMBER
SALT WASH MEMBER
SUMMER^/ILLE FORMATION
ENTRADA SANDSTONE
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The Summerville Formation, Entrada Sandstone, and Navajo Sandstone are the deepest units of
concern encountered at the site.
6-2 Local Geolosl/
The Mill site is located on thb western edge of the Blanding Basin, sometimes referred to as the
Great Sage Plain, lyrng east of the north/south-trending Monument Uplift, south of the Abajo
Mountains and adjacent to the northwest-trending Paradox Fold and Fault Belt. The AbajoMountains are the most prominent topographic feature in the region, rising over 4,000 ft above
the surface of the plain. The lithology of the immediate area is composed olthousands of feet ofmulti-colored pre-Tertiary age marine and non-marine sedimentary rocks. Erosion on theregionally-uplifted sedimentary strata has produced an array of eroded canyons and mesas.
The Mill is more specifically located on White Mesa and rests on alluvial windblown silt and
sand which covers sandstones and shales of Jurassic and Cretaceous age. The surface of the mesa
is nearly flat, with a surface relief of 98 ft. The maximum relief between White Mesa and the
adjacent Cottonwood Canyon is about 750 ft.
6.3 Site-Specific Geolosic Settine
The Mill is located within the Blanding Basin of the Colorado Plateau physiographic province.
Typical of large portions of the Colorado Plateau province, the rocks underlying thi site arerelatively underformed. The average elevation of the site is approximatety S,OOO ft (1,707 m)
above mean sea level (amsl).
The site is underlain by unconsolidated alluvium and indurated sedimentary rocks consistingprimarily of sandstone and shale. The indurated rocks are relatively flat lying with dipsgenerally less than 3". The alluvial materials consist mostly of aeolian silts and fine-grainid
aeolian sands with a thickness varying from a few feet to as much as 25 to 30 ft (7.6 to 9.1 m)across the site- The alluvium is underlain by the Dakota Sandstone and Burro Canyon
Formation, which are sandstones having a total thickness rangrng from approximately IOO to i+Oft (31 to 43 m). Beneath the Burro Canyon Formation lies the Morrison formatiorl consisting,in descending order, of the Brushy Basin Member, the Westwater Canyon Member, the
Recapture Member, and the Salt Wash Member. The Brushy Basin and Recapture Members ofthe Morrison Formation, classified as shales, are very fine-grained and Lurr" u very lowpermeability. The Westwater Canyon and Salt Wash Members also have a low average verticalpermeability due to the presence of interbedded shales. See Figure 6 for a generalized
stratigraphic column for the region.
Beneath the Morrison Formation lies the Summerville Formation, an argillaceous sandstone withinterbedded shales, and the Entrada Sandstone. Beneath the Entrada lies the Navajo Sandstone.
The Navajo and Entrada Sandstones constitute the primary aquifer in the area of the site. TheEntrada and Navajo Sandstones are separated from the Burro Canyon Formation by
approximately 1,000 to 1,100 ft (305 to 335 m) of materials having a low average verticalpermeability. Groundwater within this system is under
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artesian pressure in the vicinity of the site, and is used only as a secondary source of water at the
site.
7.0 HydrogeologicSetting
The site is located within a region that has a dry to arid continental climate, with average annual
precipitation of approximately 13.4 in. Recharge to aquifers occurs primarily along the mountain
fronts (for example, the Henry, Abajo, and La Sal Mountains), and along the flanks of folds such
as Comb Ridge Monocline.
Although the water quality and productivity of the Navajo/Entrada aquifer are generally good,
the depth of the aquifer (approximately 1,200 ft below land surface (bls)) makes access difficult.
The Navajo/Entrada aquifer is capable of yielding significant quantities of water to wells
(hundreds of gallons per minute (gpm)). Water in wells completed across these units at the site
rises approximately 800 ft above the base of the overlfng Summerville Formation.
7.1 Perched Zone Hydroeeoloey
Perched groundwater beneath the site occurs primarily within the Burro Canyon Formation.
Perched groundwater at the site has a generally low quality due to high total dissolved solids
(TDS) in the range of 1,200 to 5,000 milligrams per liter (mdL), and is used primarily for stock
watering and irrigation in the areas upgradient (north) of the site, The saturated thickness of the
perched water zone generally increases to the north of the site, increasing the yield of the
perched zone to wells installed north of the site. Perched water is supported within the Burro
Canyon Formation by the underlying, fine-grained Brushy Basin Member. Figure 7 is a contour
map showing the approximate elevation of the contact of the Burro Canyon Formation with the
Brushy Basin Manber, which essentially forms the base of the perched water zone at the site.
Contact elevations are based on monitoring well drilling and geophysical logs and surveyed land
surface elevations. As indicated, the contact generally dips to the south/southwest beneath the
site.
The permeability of the Dakota Sandstone and Burro Canyon Formation at the site is generally
low. No significant joints or fractures within the Dakota Sandstone or Burro Canyon Formation
have been documented in any wells or borings installed across the site (Ifuight Pi6sold, 1998).
Any fractures observed in cores collected from site borings are typically cemented, showing no
open space.
Based on samples collected during installation of wells MW-16 and MW-17 (the locations of the
various monitoring wells are indicated on Figure 7), located immediately downgradient of the
tailings cells at the site, porosities of the Dakota Sandstone range from 13.4Yo to 260/o, averaging
20Yo, and water saturations range from 3.7o/o to 27.2Yo, averaging l3.5yo- The average
volumetric water content is approximately 3Yo. The permeability of the Dakota Sandstone based
on packer tests in borings installed at the site ranges from 2.718-06 centimeters per second
(cm/s) to 9.128-04 cmls, with a geometric average of 3.89E-05 cm/s.
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The average porosity of the Burro Canyon Formation is similar to that of the Dakota Sandstone.
Based on samples collected from the Burro Canyon Formation at MW-16, located immediately
downgradient of the tailings cells at the site, porosity ranges from 2o/o to 29.lYo, averaging
l8.3oh, and water saturations of unsaturated materials range from 0.6% to 77.2Yo, averaging
23.4yo. Titan, 1994, reported that the hydraulic conductivity of the ilurro Canyon Formation
ranges from l.9E-07 to 1.6E-03 cm/s, with a geometric mean of l.lE-05 cm,/s, based on the
results of 12 pump/recovery tests performed in monitoring wells and 30 packer tests performed
in borings prior to that time.
Hydraulic testing of wells Mw-I, Mw-3, Mw-5, Mw-17, Mw-18, Mw-19, Mw-20, and MW-
22 duing the week of July 8, 2002, yielded average perched zone permeabilities ranging from
approximately 4.0E-07 cm/s to 5.0E-04 cm./s, similar to the range reported by previous
investigators at the site (HGC, 2002). Downgradient (south to southwest) of the tailings cells,
average perched zone permeabilities based on tests at MW-3, MW-5, MW-17, MW-20, and
MW-22 ranged from approximately 4-08-07 to 4.0E-05 cmls. Permeability estimates were based
on pump/recovery and slug tests analyzed using several different methodologies.
A number of temporary monitoring wells have been installed at the site to investigate elevated
concentrations of chloroform initially discovered at well MW-4 in 1999. Some of the
conglomeratic zones encountered within the perched zone during installation of these wells are
believed to be partly continuous or at least associated with a relatively continuous zone of higher
permeability (IUSA and HGC, 2001). The higher permeability zone defined by these wells is
generally located east to northeast of the tailings cells at the site, and is hydraulically cross-
gradient to upgradient of the tailings cells with respect to perched groundwater flow. Relatively
high permeabilities measured at MW-11, located on the southeastern margin of the downgradient
edge of tailings Cell 3, and at MW-14, located on the downgradient edge of tailings Cell 4, of
1.4E-03 cm/s and 7.58-04 cm/s, respectively (UMETCO,1993), may indicate that this zone
extends beneath the southeastern margin of the cells. This zone of higher permeability within the
perched water zone does not appear to exist downgradient (south-southwest) of the tailings cells,
however. At depths beneath the perched water table, the zone is not evident in lithologiclogs of
the southernmost temporary wells TW4-4 and TW4-6 (located east (cross-gradient) of Cell 3),
nor is it evident in wells Mw-3, Mw-5, Mw-12, Mw-15, Mw-16, Mw-17, Mw-20, Mw-21,or MW-22, located south to southwest (downgradient) of the tailings cells, based on the
lithologic logs or hydraulic testing of the wells.
Because of the generally low permeability of the perched zone beneath the site, well yields are
typically low (less than 0.5 gpm), although yields of about 2 Wm may be possible in wells
intercepting the higher permeability zones on the east side of the site. Sufficient productivity
can, in general, only be obtained in areas where the saturated thickness is greater, which is the
primary reason that the perched zone has been used on a limited basis as a water supply to the
north (upgradient) of the site.
t4
7.2 Perched Groundwater Flow
Perched groundwater flow at the site is generally to the south/southwest. Figure 8 displays the
local perched groundwater elevation contours at the Mill. As indicated, the perched groundwater
gradient changes from generally southwesterly in the western portion of the site to generally
southerly in the eastern portion of the site.
Perched water discharges in springs and seeps along Westwater Creek Canyon and Cottonwood
Canyon to the west-southwest of the site, and along Corral Canyon to the east of the site, where
the Burro Canyon Formation outcrops- Perched water flowing beneath the tailings cells
eventually discharges in springs and seeps located in Westwater Canyon, to the south-southwest
of the cells. The primary discharge point for perched water flowing beneath the tailings cells is
believed to be Ruin Spring, located approximately 10,000 ft south-southwest of the Mill site, as
shown in Figure 9.
7.3 Perched Zone Hydroeeoloev
(Beneath and Down-gradient Of the Tailings Cells)
As of the 4th Quarter,2006, perched water has been encountered at depths of approximately 50
to 115 ft bls in the vicinity of the tailings cells at the site (Figure l0). Beneath tailings Cell 3,
depths to water ranged from approximately 72 ft below top of casing (btoc) east of the cell (at
MW-31), to approximately 115 ft btoc at the southwest margin of the cell (at MW-23).
Assuming an average depth of the base of tailings Cell 3 of 25 ft below grade, this corresponds
to perched water depths of approximately 47 to 90 ft below the base of the cell, or an average
depth of approximately 70 feet beneath the base of the cell.
The saturated thickness of the perched zone as of the 4th Quarter, 2006 ranged from
approximately 94 ft in the northeast portion of the site to less than 5 ft in the southwest portion of
the site. Beneath tailings Cell 3, the saturated thickness varies from approximately 49 ft in the
easternmost corner of the cell to approximately 6 ft in the westernmost corner of the cell. South-
southwest of the tailings cells, the saturated thickness ranges from less than I ft at MW-21 to
approximately 25 ft at MW-I7. The average saturated thickness south-southwest of the tailings
cells, based on measurements at MW-3, MW-5, MW-12, MW-14, MW-l5, MW-17, and MW-
20, is approximately 14 ft. The average saturated thickness based on measurernents at MW-5,
MW-I5, MW-3, and MW-20, which lay close to a line between the center of tailings Cell 3 and
Ruin Spring, is approximately 12 ft. By projecting conditions at these wells, the average
saturated thickness is estimated to be approximately 10 to 15 ft between MW-20 and Ruin
Spring.
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White Mesa Mill
Approximate [ocation
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Figure l0
White Mesa Mill
Depth to Perched Water
Septerrber,2fi)2
Perched zone hydraulic gradients currently range from a maximum of approximately 0.04 feet
per foot (fl/ft) immediately northeast of tailings Cell 3 to less than 0.01 ff/ft downgradient of Cell
3, between Cell 3 and MW-20. The average hydraulic gradient between the downgradient edge
of tailings Cell 3 and Ruin Spring was approximated by HGC to be approximately 0.012 fl/ft.
HGC also estimated a hypothetical worst case average perched zone hydraulic gradient,
assuming the perched water elevation to be coincident with the base of tailings Cell 3, to be
approximately 0.019 fl/ft. See Section 3.2 of Appendix A.
HGC also estimated the average permeability of the perched zone downgradient of tailings Cell
3, based on pump/recovery test and slug test data obtained from perched zone wells located
along the downgradient edge of and south of Cell 3, to be between 2.398-05 cm/s and 4.3E-05
cm/s. See Section 3.3 of Appendix A to the February 28, 2007 Environmental Report
incorporated here by reference.
7.4 GroundwaterOuality
7.4.1 Entrada/Navajo Aquifer
The Entrada and Navajo Sandstones are prolific aquifers beneath and in the vicinity of the site,
Water wells at the site are screened in both of these units, and therefore, for the purposes of this
discussion, they will be treated as a single aquifer. Water in the Entrada./Navajo Aquifer is under
artesian pressure, rising 800 to 900 ft above the top of the Entrada's contact with the overlying
Summervillle Formation; static water levels are 390 to 500 ft below ground surface.
Within the region, this aquifer is capable of yielding domestic quality water at rates of 150 to 225
grm, and for that reason, it serves as a secondary source of water for the Mill. Additionally, two
domestic water supply wells drawing from the Entrada,rNavajo Aquifer are located 4.5 miles
southeast of the Mill site on the Ute Mountain Ute Reservation. Although the water quality and
productivity of the Navajo/Entrada aquifer are generally good, the depth of the aquifer (>1,000 ft
bls) makes access diffrcult.
Table 2 is a tabulation of groundwater quality of the Navajo Sandstone aquifer as reported in the
FES and subsequent sampling. The total dissolved solids (TDS) range from 244 to 1,110
mg/liter in three samples taken over a period from January 27, 1977, to May 4, 1977. High iron
(0.057 mg/liter) concentrations are found in the Navajo Sandstone. Because the Navajo
Sandstone aquifer is isolated from the perched groundwater zone by approximately 1,000 to
1,100 ft of materials having a low average vertical permeability, sampling of the Navajo
Sandstone is not required under the Mill's previous NRC Point of Compliance monitoring
program or under the state's GWDP. However, samples were taken at two other deep aquifer
wells (#2 and #5) on site (See Figure ll for the locations of these wells), on June 1,1999 and
June 8, 1999, respectively, and the results are included in Table 2.
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TEMPORAMT PERCHED T,ION]TORIIIIG WELL
SHC'WING DEPTH TO WATER IN FEET BTOC
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Figure I I
White Mesa Mill
Stock Watering Pond Locations
Table 2
Water Quality of Groundwater in the Mill Vicinity
Parameter
FES, Test Well
(G2R)
ot27t77 -3t23fi811
Well #2
6t0t9gr
Well #5
6toSDgr
Field Specifi c Conductivity
(umhos/cm)310 to 400
Field pH 6.9 to 7 .6
Temperature (oC)ll to 22
Estimated Flow m/hr (eDm)109(20)
pH 7.9 to 8.16
Determination. mey'liter
TDS (@I8trC)216tolll0
Redox Potential 2ll1o220
Alkalinitv (as CaCOS")180 to 224
Hardness, total (as CaCOr)177 to2O8
Bicarbonate 226 214
Carbonate (as COr)0.0 <l_0 <1.0
Aluminum 0.003 0.058
Aluminum, dissolved <0. I
Ammonia (as N)0.0 ro 0.16 <0.05 <0.05
Antimonv <0.001 <0.001
Arsenic- total .007 to 0.014 0.018 <0.001
Barium. total 0.0 to 0.15 0.1l9 0.005
Bervllium <0.001 <0.001
Boron. total <0.1 to 0.1 I
Cadmium. total <0.005 to 0.0 <0.001 0.018
Calcium 50.6 39.8
Calcium, dissolved 5l to l12
Chloride 0.0 to 50 <1.0 2.3
Sodium 7.3 9.8
Sodium, dissolved 5.3 to 23
Silver <0.001 <0.001
Silver. dissolved <0.002 to 0.0
Sulfate 28.8 23.6
Sulfate. dissolved (as SOo)17 to 83
Vanadium 0.003 0.003
Vanadium. dissolved <.002 to 0.16
Manganese 0.01l 0.032
Mansanese. dissolved 0.03 to 0.020
Chromium, total 0.02 to 0.0 0.005 0.005
Cooper- total 0.005 to 0.0 0.002 0.086
Fluoride 0. l8 0.18
Fluoride, dissolved 0.1to 0.22
Iron. total 0.35 to 2- l 0.43 0.20
Iron- dissolved 0.30 to 2.3
t Zero ualues (0.0) are below detection lirnits
21
Parameter
FES, Test Well
(G2R)
ot27t77 -3t23fl8t1
Well #2
6tLuggl
Welt #5
6t089gl
Lead, total 0.02 - 0.0 <0.001 0.018
Masnesium 20.4 21.3
Masnesium. dissolved l5 to 2l
Mercury, total <.00002 ro 0.0 <0.001 <0.001
Molvbdenum 0.001 <0.001
Molybdenum. dissolved 0.004 to 0.010
Nickel <0.001 0.004
Nitrate + Nitrate as N <0. l0 <0.10
Nitrate (as N)<.05 to 0-12
Phosphorus. total (as P)<0.01 to 0.03
Potassium 3.1 3.3
Potassium. dissolved 2.4 to 3.2
Selenium <0.001 <0.001
Selenium, dissolved <.005 to 0.0
Silica. dissolved (as SiOr)5.8 to 12
Shontium. total (as U)0.5 to 0.67
Thallium <0.001 <0.001
Uranium. total (as U)<.002 to 0.16 0.0007 o.0042
Uranium, dissolved (as U)<.002 to 0.031
Zinc 0.010 0.126
Zinc, dissolved 0.007 to 0.39
Total Orsanic Carbon l.l to 16
Chemical Oxvsen Demand <l to 66
Oil and Grease I
Total Suspended Solids 6 to 1940 <1.0 10.4
Turbidiw 5.56 19. I
Determination (pCi/liter)
Gross Alpha <1.0
Gross Aloha f orecision 1.6+1.3 to 10.2+2.6
Gross Beta <2.0
Gross Beta * precision 8+8 to 73+19
Radium 226 + orecision 0.3+0.2
Radium 228 <1.0
Ra126 * precision 0.1+-3 to 0.6+0.4
Th-230 + orecision 0.1+0.4 to0.7+2.7
Pb-2 l0 * precision 0.0+4.0 to l.GF2.0
Po-210 * precision 0.Gf0.3 to 0.0+0.8
Source: Adapted from FES Table 2.25 with additional Mill sampling data
7.4.2 Perched Groundwater Zone
Perched groundwater in the Dakota/Burro Canyon Formation is used on a limited basis to the
north (upgradient) of the site because it is more easily accessible. The quality of the Burro
Canyon perched water beneath and downgradient from the site is poor and extremely variable.
The concentrations of total dissolved solids (TDS) measured in water sampled from upgradient
and downgradient wells range between approximately 1,200 and 5,000 mg/|. Sulfate
concentrations measured in three upgradient wells varied between 670 and 1,740 mgll (Titan,
1994). The perched groundwater therefore is used primarily for stock watering and irrigation.
22
The saturated thickness of the perched water zone generally increases to the north of the site.
See the Background Groundwater Quality Report: Existing Wells For Denison Mines (USA)
Corp.'s White Mesa Mill Site, San Juan County, Utah dated December 2006 prepared by Intera,
Inc., Appendix B.
At the time of renewal of the Mill license by the NRC in March, 1997 and up until issuance of
the Mill's Groundwater Discharge Permit (*GWDP') in March 2005, the Mill implemented a
groundwater detection monitoring program to ensure compliance to 10 CFR Part 40, Appendix
A, in accordance with the provisions of Mill License condition I1.3A. The detection monitoring
program was in accordance with the report entitled, "Points of Compliance, White Mesa
Uranium Mill," submitted by letter to the NRC dated October 5,1994. Under that program, the
Mill sampled monitoring wells Mw-5, Mw-l1, Mw-12, Mw-14, Mw-15 and MW-l7, on a
quarterly basis. Samples were analyzed for chloride, potassium, nickel and uranium, and the
results of such sampling were included in the Mill's Semi-Annual Effluent Monitoring Reports
that were filed with the NRC up until August 2004 and with the DRC subsequent thereto.
Prior to 1997, commencingin 1979, the Mill monitored up to 20 constituents in up to 13 wells.
That program was changed to the Points of Compliance Program in 1997 because:
. The Mill and tailings system had produced no impacts to the perched zone or deep
aquifer; and
. The most dependable indicators of water quality and potential cell failure were
considered to be chloride, nickel, potassium and natural uranium.
8.0 Ecological Resources and Biota
8.1 Terrestrial
a) Flora
The natural vegetation presently occurring within a 25-mile (40-km) radius of the Mill site is
very similar to that of the region, being characteized by pinyon-juniper woodland intergrading
with big sagebrush (Arternisia tridentata) communities. The pinyon-juniper community is
dominated by Utah juniper (Juniperus osteosperma) with occurrences of pinyon pine (Pinus
edulis) as a codominant or subdominant tree species. The understory of this communitS which
is usually quite open, is composed of grasses, forbs, and shrubs that are also found in the big
sagebrush communities. Common associates include galleta grass (Hilaria jamesii), green
ephedra (Ephedra viridis), and broom snakewood (Gutierrezia sarothrae). The big sagebrush
communities occur in deep, well-drained soils on flat terrain, whereas the pinyon-juniper
woodland is usually found on shallow rocky soil of exposed canyon ridges and slopes. See
Section 2.9 of the 1978 ER.
Based on the work completed by Dames & Moore in the 1978 ER, no designated or proposed
endangered plant species occur on or near the project site (1978 ER, Section2.8.2.l). Of the 65
proposed endangered species in Utah at that time, six have documented distributions in San Juan
23
County. A careful review of the habitat requirements and known distributions of these species
by Dames & Moore in the 1978 ER indicated that, because of the disturbed environment, these
species would probably not occur on the project site. The Navajo Sedge has been added to the
list as a threatened species since the Dames & Moore study.
In completing the 2002 EA, NRC staff contacted wildlife biologists from the BLM and the Utah
Wildlife Service to gather local information on the occurrences of additional species surrounding
the Mill. In the 2002 EA, NRC staff concluded that the Navajo Sedge has not been observed in
the area surrounding Blanding, and is typically found in areas of moisture (2002 EA at 4).
b) Fauna
Wildlife data were collected by Dames & Moore through four seasons at several locations on theMill site, prior to construction of the Mill. The presence of a species was based on direct
observations, trappings and signs such as the occurrence of scat, tracks, or burrows. A total of
174 vertebrate species potentially occur within the vicinity of the Mill (1978 ER, Appendix D),
78 of which were confirmed (1978 ER, Section2.8.2.2).
Although seven species of amphibians are thought to occur in the area, the scarcity of surface
water limits the use of the site by amphibians. Eleven species of lizards and five snakes
potentially occur in the area (1978 ER, Section2.8.2.2).
Fifty-six species of birds were observed in the vicinity of the Mill site (1978 ER, Section
2.8.2.2).
The food habits of eagles vary depending on the season and the region in which they live. Fish,
carrion and waterfowl such as mallard, are consumed by eagles when available to thern. The
FES indicates that mallards are both common and permanent in the vicinity of the Mill (FES,
Table 2.28).
Raptors are prominent in the westem United States. Five species were observed in the vicinity
of the site. Although no nests of these species were located at the time of the FES, all (except the
golden eagle, Aquila chrysaetos) have suitable nesting habitat in the vicinity of the site. The nest
of a prairie falcon (Falco mexicanus) was found about 314 mile (1.2 km) east of the site.
Although no sightings were made of this species, members tend to return to the same nests for
several years if undisturbed (1978 ER, Section2.8.2.2).
Of several mammals that occupy the site, mule deer (Odocoileus hemionus) is the largest
species. The deer inhabit the project vicinity and adjacent canyons during winter to feed on the
sagebrush and have been observed migrating through the site to Murphy Point (1975 ER, Section
2.8.2.2). Winter deer use of the project vicinity, as measured by browse utilization, is among the
heaviest in southeastern Utah at 25 days of use per acre in the pinyon-juniper-sagebrush habitats
in the vicinity of the project site. In addition, this area is heavily used as a migration route by
deer traveling to Murphy Point to winter. Daily movement during winter periods by deer
inhabiting the area has also been observed between Westwater Creek and Murphy Point. The
present size of the local deer herd is not known.
24
Other mammals present at the site include the coyote (Canis latrans), red fox (Vulpes vulpes),
gray fox (Urocyon cineroargenteus), striped skunk (Mephitis mephitis), badger (taxidea taxus),
longtail weasel (Mustela frenata), and bobcat (Lynx rufus). Nine species of rodents were trapped
or observed on the site, the deer mouse (Peromyscus maniculatus) having the greatest
distribution and abundance. Although desert cottontails (Sylvilagus auduboni) were uncommon
in 1977, black-tailed jackrabbits (Lepus californicus) were seen during all seasons.
In the 2002 EA, NRC staff noted that, in the vicinity of the site, the U.S. Fish and Wildlife
Service had provided the list set out in Table 3.12-1, of the endangered, threatened, and
candidate species that may occur in the area around the site.
Table 3 Endangered, Threatened and Candidate Species in the Mill Area
The2002 EA also noted that, in addition, the species listed on Table 3.12-2 may occur within the
Mill area that are managed under Conservation Agreements/Strategies
Table 4
Species Managed Under Conservation Agreements/Strategies at the Mill Area
For the 2002 EA, NRC staff contacted wildlife biologists from the BLM and the Utah Wildlife
Service to gather local information on the occurrences of these additional species surrounding
the Mill. NRC staff made the following conclusions (2002 EA p. 4):
While the ranges of the bald eagle, peregrine falcon, and willow flycatcher encompass the
project area, their likelihood of utilizing the site is extremely low. The black-footed ferret has
not been seen in Utah since 1952, and is not expected to occur any longer in the area. The
Common Name Scientific Name Status
Navaio Sedse Carex specuicola Threatened
Bonytail Chub Gila elegans Endangered
Colorado Pikeminnow Prvchocheilus lucius Endangered
Humoback Chub Gila cvoha Endangered
Razorback Sucker Xyrauchen texanus Endaneered
Bald Eaele Haliaeetus leucoceohalus Threatened
California Condor GvmnoevDs cal i fornianus Endangered
Gunnison Sase Grouse Centrocercus minimus Candidate
Mexican Spotted Owl Strix occidentalis lucida Threatened
Southwestern Willow Flycatcher Empidonax traillii extimus Endansered
Western Yellow-billed Cuckoo Cocclrzus americanus occidentalis Candidate
Black-footed Ferret Mustela nisripes Endansered
Source: 20028A
Common Name Scientific Name
Colorado River Cutthroat Trout Oncorhynchus clarki oleuriticus
Gunnison Sage Grouse Centrocercus minimus
Source:2002F,A
25
Califomia Condor has only rarely been spotted in the area of Moab, Utah, (70 miles north) and
around Lake Powell (approximately 50 miles south). The Mexican Spotted Owl is only found in
the mountains in Utah, and is not expected to be on the Mesa. The Southwestern Willow
Flycatcher, Western Yellow-billed Cuckoo, and Gunnison Sage Grouse are also not expected to
be found in the immediate area around the Mill site.
8.2 Aquatic and Wetlands Biota
Aquatic habitat at the Mill site ranges temporally from exhemely limited to nonexistent due to
the aridity, topography and soil characteristics of the region and consequent dearth of perennial
surface water. Two small stockwatering ponds are located on the Mill site a few hundied yards
from the ore pad area (See Figure 11). One additional small *wildlife pond'', east of Celi 44,
was completed in 1994 to serve as a diversionary feature for migrating waterfowl. Althoughmore properly considered features of the terrestrial environment, these ponds essentiafy
represent the total aquatic habitat on the Mill site. These ponds probably harbor algae, insects,
other invertebrate forms, and amphibians. They also provide a water source for smajl mammals
and birds. Similar epherneral catch and seepage basins are typical and numerous to the northeast
of the Mill site and south of Blanding.
Aquatic habitat in the Mill vicinity is similarly limited. The three adjacent streams (Corral
Creek, Westwater Creek, and an unnamed arm of Cottonwood Wash) are only intermittently
active, carrying water primarily in the spring during increased rainfall and snowmelt runofi in
the autumn, and briefly during localized but intense electrical storms. lntermittent water flow
most tlpically occurs in April, August, and October in those streams. Again, due to the
temporary nature of these steams, their contribution to the aquatic habitat of the region is
probably limited to providing a water source for wildlife and a temporary habitat for insect and
amphibian species.
In the 2002F,A, NRC staff concluded that (p. 4) no populations of fish are present on the project
site, nor are any known to exist in the immediate area of the site. Four species of fish aesignated
as endangered or threatened (the Bonytail Chub, Colorado Pikeminnow, Humpback Chub and
Razorback Sucker) occur in the San Juan River 18 miles south of the site, which Dames &Moore noted in the 1978 ER (Section 2.8.2) is the closest habitat suitable for these species. NRCstaff further concluded that there are no discharges of mill effluents to surface waters, and
therefore, no impacts are expected for the San Juan River due to operations of the Mill.
9.0 Background Radiological and Non-Radiological Characteristics
Background Radiological and Non-Radiological Effects have been evaluated, updated andreported extensively in Denison's February 28, 2OO7 License Renewal Application and
accompanying Environmental Report, incorporated here by reference.
10.0 Environmental Effects Related Directly to the Construction of Cell 4b
The environmental effects of Cell 4b construction consist of those related to the release of
airborne particulate (dusting), radon release from the operating cell, and the impact, if any, on
26
groundwater beneath the pond. In order to evaluate these environmental considerations two
separate evaluations were completed, Site Hydrogeologt Estimation Of Groundwater Travel
Times and Recommended Additional Monitoring Wells For Proposed Tailings Cell 4BWhite
Mesa Uranium Mill Site Near Blanding, Utah, Hydro Geo Chem, Inc., 2008 and Dose
Assessment Pertaining to the Proposed Development of New Tailings Cells For the White Mesa
Uranium Mill, SENES Consultants, Ltd, 2008.
These evaluations are provided as Appendix A and Appendix B, respectively, and are discussed
in summary in the pertinent subsections below.
10.1 Groundwater Pathway Impact
The evaluation provided by Hydro Geo Chem tnc. finds that travel time for any water exiting the
pond to the perched water zone and then to the point(s) of perched zone discharge is very long,
far exceeding the time period of milling operations and closure of the tailings cells when little
free liquid is available for infiltration through the cell liner systern. More specifically, HGC
found that the time for fluids that could be released from the cells to reach the points of seepage
and spring formation at ruin spring and Cottonwood seep are on the order of several thousand
years. However, this analysis is very conservative in that travel time through the pond liner was
not considered, and because the liner systern is robust state-of-the art construction, travel time
through the liner is a significant protective factor. [n fact, this aspect has been evaluated
extensively by MWH Americas, Inc. in their report Infiltration and Contaminant Transport
Modeling Report, White Mesa Mill Site, Blanding (Jtah, November, 2007, incorporated here by
reference. The infiltration modeling effort revealed that the construction design for Cells 4a
and 4b will meet the "Closed Cell Performance Requirernents" of the Groundwater Discharge
Permit at Part 1.D.6. More specifically, MWH concluded that the approved reclamation plan for
the cells will meet the following regulatory requirements for a period of not less than 200 years:
a) Minimize infiltration of precipitation or other surface water into the tailings,
including but not limited to the radon barrier;b) Prevent the accumulation of leachate head within the tailings waste layer that
could rise above or over-top the maximum FML liner elevation internal to any
disposal cell, i.e. create a "bathtub" effect; and,c) Ensure that groundwater quality at the compliance monitoring wells does not
exceed Ground Water Quality Standards or Ground Water Compliance Limits
specified in Part 1.C.1 and Table 2 of the Permit.
10.2 ProposedAdditional GroundwaterMgnitorine
In order to monitor the performance of Cell 4b, and consistent with EPA Guidance, it was
concluded by Hydro Geo Chem Inc. that an additional well or wells will be needed to monitor
the Cell's performance at the downgradient edge of the cell. This in addition to the many wells
already incorporated into the Groundwater Discharge Permit for the facility. Accordingly, two
additional wells are proposed, one at the southwest corner of proposed Cell 4b and one between
the southwest corner well and existing well MW-15 (See Figure l0 of Appendix B. These
27
installations will conservatively maintain the approximate existing spacing as defined by the
proximity of MW-14 to MW-15 along the downgradient edge of existing Cell4a.
10.3 Radioloeical Impact
In February 2007, a dose assessment was prepared for DUSA by SENES Consultants, Ltd. in
support of the license renewal application for the mill. MILDOS-AREA was used to estimate
the dose commitments that could potentially be received by individuals and the general
population within a 50 mile (80 km) radius for processing of conventional ores. The assessment
was prepared for scenarios in which Colorado Plateau (0.25% U:Os and l.5Yo VzOs) or Arizona
Strip (0.637Yo) ores are processed at the mill.
In order to evaluate the radiological impact of Cell 4b's operation the prior dose assessment
analyses was extended from the previous report of February 2007 to incorporate the dose from
the proposed development of new tailings cells anticipated in the future. The results of this
extended assessment are provided as Attachment B to this report (Proposed Development of New
Tailings cells For The White Mesa (Jranium Mill, SENES, 2008), and reveal that the addition of
Cell 4b to the facility will not impact the ability of the facility to comply with regulatory
requirements
The U.S. NRC approved MILDOS-AREA was used to estimate the dose commitments received
by individuals and the general population within a 50 mile (80 km) radius of the site for the
processing of either Colorado Plateau or Arizona Strip ore separately. In each scenario, the
doses arising from emissions of dust and radon from the mill area and ore pads were assumed to
be the same as the previous 2007 report since the scenarios both involve the processing of
Colorado Plateau and Arizona Strip ores. Therefore, MILDOS-AREA runs from the previous
report were revised to exclude the tailings cells. The doses from the tailings cells were estimated
in separate MILDOS-AREA runs and added to the dose from the mill area and ore pads. Table 4
provides a summary of the source terms included in Phases I and 2 of the development of new
tailings cells including Cells 4a and 4b.
TABLE 4
SOURCE TERMS INCLUDED IN PHASE 1 AND 2
Source Term Phase I Phase 2
Mill area included included
Ore Pads included included
Tai ings Cell 2 with Interim Soil Cover included included
Tai ings Cell3 active interim soil cover
Tai ings Cell4A active active
Ta ings Cell48 excluded active
28
The wind erosion and radon release rates from the tailings cells (active and with interim
soil cover) were modeled by using a maximal worst case approach.
Each active tailings cell was modeled to have an active area of l0 acres (i.e., the
maximum expected to be uncovered at any time since it is not possible to predict the
diskibution of uncovered tailings between the active cells at any given time. The release
rate of wind-eroded tailings dust was estimated for 10 acres. The total annual radon
release rate was estimated by assuming a radon release rate of 20 pCi/m2s (i.e., maximum
radon-222 emissions to ambient air from an existing uranium mill pile) over the entire
area of each cell consistent with NESHAPs.
Emissions from the tailings cells (2 and 3) with interim soil cover were assumed to occur
over the entire area of each cell; however, only radon is released at a rate of 10 pCi/m2s
after the application of the soil cover.
The calculated total annual effective dose commitments (including radon) calculated
using MILDOS-AREA were compared to the Utah Administrative Code R3l3-15-
301(1)(a) requirement that the dose to individual mernbers of the public shall not exceed
100 mrem/yr (radon included). For proposed development of new tailings cells for the
processing of Colorado Plateau ore, the maximum total annual effective dose
commitments was calculated to be a maximum of 1.4 mrem/yr for an infant at the nearest
potential resident, BHV-I (Tables 6.1-1 and 6.1-3) (i.e., effective dose) and is aboutl.4Yo
of the R3l3-15-301(1)(a) limit of 100 mrem/yr (radon included) to an individual mernber
of the public for Phases I and 2. For proposed development of new tailings cell for the
processing of Arizona Strip ore, the total annual effective dose commitrnents were
calculated to be a maximum of 3.1 mrem/yr for an infant at the nearest potential resident,
BHV-I (i.e., effective dose) and is about 3.1% of the 100 mrem/yr limit (radon included)
to an individual member of the public for Phases I and 2. Overall, the predicted annual
effective dose commitments for proposed development of new tailings cells during
anticipated ore processing operations comply with R313-15.
In addition, our MILDOS-AREA calculated 40 CFR 190 annual dose commitments
(excluding radon) were compared to the 40 CFR 190 criterion, which is 25 mrem/yr to
the whole body (excluding the dose due to radon) and 25 mrem/yr to any other organ to
any mernber of the public (U.S. EPA 2002). The 40 CFR 190 doses were also used to
dernonstrate compliance with R313-15-101(4) (10 CFR 20.1101(d)) (i.e., the licensee
must dernonstrate that total effective dose equivalent to the individual member of the
public likely to receive the highest total effective dose equivalent will not exceed l0
mrem/yr (absent of the radon dose). For proposed development of new tailings cells for
the processing of Colorado Plateau ore, the 40 CFR 190 annual dose commitrnents were
29
calculated to be a maximum of 4.8 mrem/yr for a teenage at the nearest potential resident,
BHV-I (i.e., dose to the bone) and is about lgYo of the 40 CFR 190 dose criterion of 25
mrem/yr for Phases I and 2. Further, the 40 CFR 190 annual effective dose
commitments demonstrate compliance with the R3l3-15-l0l(4) (l0CFR 20.1101(d))
limit of 10 mrem/yr to the individual member of the public likely to receive the highest
total eflective dose equivalent. For Arizona Strip ore, the 40 CFR 190 annual dose
commitments were at most 12 mren/yr for a teenage at the nearest potential resident,
BHV-I (i.e., dose to the bone) and is well within the 40 CFR 190 dose criterion of 25
mrem/yr for Phases I and 2. Further, the annual effective dose commitments
dernonstrate compliance with R3l3-15-101(4) (10 CFR 20.1I01(d)) limit of 10 mrern/yr
to the individual member of the public likely to receive the highest total effective dose
equivalent.
10.4 Prooosed Radioloeical Monitorine to Accommodate Cell4b Operations
As an elernent of evaluating potential off-site doses related to the construction and
operation of Cell 4b, Denison commissioned a review of its environmental monitoring
programs in order to determine what, if any, additional monitoring would be needed to
accommodate the operation of Cell 4b. The review was conducted by SENES
Consultants, Ltd who concluded that the current environmental monitoring regime was
sufficient and that added monitoring was not warranted due to the operation of Cell 4b.
The results of the SENES review are attached here as Appendix C to this report.
11.0 Alternatives
The action under consideration is the construction of an already contemplated tailings
Cell (Cell 4b) in order accomodate continued operation of the Mill. The alternatives
available to the Executive Secretary are to:
a) Amend the License to include the construction of Cell 4b with its existing
terms and conditions;
b) Amend the License to include the construction of Cell 4b with such additional
conditions as are considered necessary or appropriate to protect public health,
safety and the environment; or
c) Deny the addition of Cell 4b construction into the License.
As demonstrated in this ER, the environmental impacts associated with construction and
operation of Cell 4b do not warrant either limiting the Mill's future operations or denying
the Cell 4b construction approval request. As there are no significant public health,
safety or environmental impacts associated with the construction of Cell 4b, Denison
30
asselts that alternatives with equal or greater impacts need not be evaluated, and
altemative a) is the appropriate alternative for selection.
l1.l Issuance of Amendment for Cell 4a
The Mill is one of only two operating uranium mills in the Unites States and the only
uranium mill on the western slope of the Rocky Mountains. As a result, the Mill is the
only currently available opportunity for production of uranium from conventionally
mined ore in San Juan County and in the four corners area of the United States. The Mill
therefore provides a benefit to the regional community and to the uranium industry as a
whole in the United States. The construction of Cell 4b would allow the Mill to continue
to provide these benefits for many more years and as contemplated in the original
licensing effort.
As was dernonstrated in Section 3 of the ER accompanying the 20O7 License Renewal
Application, the Mill's equipment, facilities and procedures are adequate to minimize
impacts to public health, safety and the environment. More importantly, UDEQ has
already approved the construction of Cell 4a which is identical to Cell 4b with regard to
its robust and state-of-the-art protective design features. Also, the Mill has operated
since its inception in compliance with all applicable regulatory standards and ALARA
goals and is capable of continuing to operate in compliance with such standards and
goals.
In addition to the License, the Mill has been issued a Groundwater Discharge Permit,
which provides additional protection for public health and the environment, including a
rigorous groundwater monitoring program to monitor and assess the performance of
tailings cells associated with the facility. The Mill has demonstrated that it is capable of
continuing to operate in a manner that satisfies all regulatory standards and ALARA
goals under the existing terms and conditions of the License and GWDP, this amendment
application has assessed and proposed additional monitoring necessary to accommodate
newly constructed Cell 4b. Based upon these factors and considerations Denison asserts
that there is no need to add any additional conditions to the License in order to protect
public health, safety or the environment as a result of Cell 4b construction.
11.2 No Action Alternative
A "no action" alternative would result in the amendment request being denied and the
immediately available processing opportunities for mined uranium ore being lost in the
short term, severely impacting independent uranium miners in the area and lessening the
United States' capability to respond to the need for uranium for nuclear power
generation.
Denying the request for construction of Cell 4b severely constrain the utilization of the
Mill in the near term and eliminate its ability to operate over the longer term during a
time when commodity prices for uranium are favorable, and the dernand for uranium
milling capacity is unprecedented. Permitting the Mill to continue processing
3l
conventionally mined ore for the recovery of uranium and the construction of Cell 4b will
provide the opportunity for regular employment in an economically depressed area of the
United States. A large percentage of the workers at the Mill are Native American, and
this employment opportunity has significant direct impact in the local Native American
community. In addition to the direct hiring of employees at the Mill, local miners and
other western United States mining companies require access to hn operating uranium
mill. The inability of these mining entities to gain access to local milling services will
prevent the mining industry from responding to the current uranium supply shortage.
Thus, secondary local economies will not enjoy the benefit of renewed mining income,
and national dernand for uranium will continue to be reliant primarily on foreign supplies
of uranium for nuclear fuel. In order to respond to the current uranium market,
conventional mining companies will be forced to license and construct new uranium
milling facilities to engage in conventional ore processing, directly in opposition to the
objective of non-proliferation of new uranium mill tailings disposal facilities ernbodied
by 10 CFR Part 40 Appendix A, Criterion 2.
As has been demonstrated by the forgoing assessments, the impacts associated with the
construction and operation of Cell 4b are well within the realm of impacts anticipated in
the FES, the 1985 EA and the 1997 EA, and UDEQ's approval of Cell 4b construction
will satisff applicable criteria inR313-22-33 and P.3l3-24. As a result, Denison asserts
that the Executive Secretary should have no basis for denying the proposed action.
I1.3 Altematives Considered But Eliminated
a) Consideration of Alternative Sites
The Mill is already sited and in existence and has been operating for over 25 years. It is
not feasible to consider moving the Mill to an alternative site or to construct additional
tailing cells at a different location. Even if that were possible, it has been demonstrated
in Section 3 of the February, 2007 ER accompanying the License Renewal Application
that the Mill is sited in a good hydrogeologic setting and is otherwise well sited for its
operations, including tailings cells contemplated at the time of the Mill's original
licensure. This is evident from the fact that the Mill has operated since its inception in
compliance with applicable regulatory standards and ALARA goals.
If the construction of Cell 4b is not approved as an element of continued milling
operations, there can be no assurance that, as an alternative, an equally well-suited site
for milling and tailings cell contruction, that complies with the applicable siting
requiremants of l0 CFR Part 40 Appendix A, can be identified and obtained. Even if a
suitable alternative site were to be identified and obtained, licensing and construction of a
new mill and tailings cells could not be accomplished in a time frame that would ensure
production could commence in a period of suitable market conditions. Furthermore, as
the existing Mill tailings would have to be decommissioned in place, creation of a new
mill site would result in unnecessary proliferation of mill tailings disposal facilities in
contravention of l0 CFR Part 40 Appendix A, Criterion 2.
32
b) Consideration of Alternative Engineering Methods
As will be demonstrated in Section 3, the existing Mill facilities, equipment, procedures
and training of personnel have resulted in ttre Mill operating since inception in
compliance with all applicable regulatory standards and ALARA goals- Current
modeling demonstrates that the Mill is capable of continuing to operate urider the existing
terms and conditions of the License in a manner that will continue to comply with such
standards and goals. Furthermore, the Mill's GWDP institutes additional protections and
engineering controls, including the requirement that any new construction of tailings cells
must meet current best available technology standards. Therefore, there is no need to
consider alternative engineering methods. The existing equipment and facilities, together
with the existing terms and conditions of the License and the GWDP are sufficient to
ensure that all applicable requirements will continue to be satisfied.
ll.4 Cumulative Effects
There Ne no past, present, or reasonably foreseeable future actions which could result in
cumulative impacts that have not been conternplated and previously approved under the
existing Mill License and the design of Cell4b.
As stated throughout this License Amendment request, the Cell 4b construction will
result in no activity with potential, significant, incremental impacts to public health,
safety or the environment over and above the actions contemplated in the FES, the 1985
EA and the 1997 EA. The activities contemplated with regard to ore processing and
disposal of tailings remain unchanged from those previously authorized under the
License.
I1.5 Comparison of the Predicted Environmental Impacts
There have been no observed significant impacts which were not previously quantified
and addressed to public health, safety or the environment resulting from the proposed
construction of Cell 4b. As there will be no significant changes in Mill operations if the
License is amended to accommodate construction of Cell 4b, possible impacts to public
health, safety or the environment will not exceed those predicted in the original License
application and periodic renewals.
11.6 Updates & Changes to Factors That May Cause Reconsideration of
Alternatives
As discussed in Section 12 below, Costs and Benefits, there have been no changes to
factors that may cause reconsideration of alternatives. There have been no significant
changes in the costs associated with operation of the Mill (including its impoundments),
and the benefits associated with continued operation and construction of already
contemplated tailing cells have become more evident over time as the number of uranium
mills has dwindled and the demand for uranium milling service capacity from local
miners and the industry as a whole has increased in recent years. Furthermore, no new
33
alternatives to the services provided by
identified since the last License renewal in
12.0 Cost and Benefits
the Mill and its impoundments have been
1997.
Appendix A to NUREG 1569 requires that the applicant for a license renewal describe
any updates and changes to the economic costs and benefits for the facility since the last
application.
There have been no significant changes to the costs associated with the Mill since the last
License renewal in 1997. While there will a change to the currently disturbed area as a
result of the Cell 4b construction, this additional Cell was conternplated, described and
assessed, as a critical component of the initial 1978 NRC-FEIS and attendant licensing of
the facility. As indicated in Section 3 of February,2007 ER accompanylng the renewal
application, the Mill has operated in accordance with applicable regulatory standards and
ALARA goals since its inception, and updated MILDOS AREA modeling indicates that
the Mill is capable of continuing to operate well within those standards and goals. There
have been no significant demographic changes that have impacted the ability of the Mill
to operate in a manner that will result in no significant impacts to public health, safety or
the environment. It is expected that continued Mill operations will continue to draw
primarily upon the existing work force in the area with little impact on social services.
The Mill is one of only two operating uranium mills in the United States and is one of the
largest private employers in San Juan County. The benefits of the Mill will continue to
be the provision of well-paying jobs to workers in San Juan County and the support of the
tax base in that County. Moreover, as the only operating uranium mill on the westem
slope of the Rocky Mountains, the Mill is relied upon by the large number of independent
uranium miners in San Juan County and the Colorado Plateau as the only feasible
uranium mill for their uranium ores. With the recent gap between the supply and demand
for uranium and the increases in the price of uranium, the need for continued licensing of
the Mill is crucial for such miners and for the uranium industry in the United States as a
whole.
In sum, the costs associated with the operation of the Mill have not changed significantly,
but the benefits have become more evident over time as the number of uranium mills has
dwindled and the demand for uranium milling services from local miners and the industry
as a whole has increased.
13.0 Mitigation of Impacts
NUREG 1569 requires that the ER provide the "results of ef[ectiveness of any mitigation
proposed and implemented in the original license". In the case of the White Mesa Mill,
there have not been any mitigations proposed or implemented under the License.
34
14.0 Long Term Impacts
The long term impacts, including decommissioning, decontamination, and reclamation
impacts associated with activities conducted pursuant to the License have been
considered in detail in the FES, the Mill's Reclamation Plan, and the 2000 EA prepared
by the NRC in connection with the Reclamation Plan.
The Mill's Reclamation Plan and financial surety zurangements, as well as the provisions
in the Mill's GWDP that relate to final reclamation of the site are described in detail in
Section 8 of the February, 2007 License Renewal Application, and are incorporated here
by reference. The construction of Cell 4b will not result in any changes to operations at
the Mill that would impact decommissioning, decontamination or reclamation aspect
associated with Mill activities, or the previous analyses of such aspects. The grading
contours and other reclamation features related to closure of Cell4b at site closure are
shown in Figure 20. All design features for Cell 4b are included in the Cell4b Design
Report prepared by Geosyntec Consultants which was transmitted to UDEQ in January of
2008.
35
SITE ITYDROGEOLOGY
ESTIMATION OF GROUI\DWATER TRAVEL TIMES
AND RECOMMEiYDED ADDITIONAL MONITORING WELLS
FOR PROPOSED TAILINGS CELL 48
WIIITE MESA URANIUM MILL SITE
NEAR BLAI\DING, UTAH
Prepared f'or:
DENTSON MrNES (USA) CORP
Independenc e Plaza, Suite 950
1050 lTth Street
Denver, Colorado 80265
[phone]
Prepared by:
ITYDRO GEO CHEM,INC.
51 West WeEnore, Suite l0l
Tucson, Arizona 85705-1 678
(s20)293-1s00
January 8,2008
2.
l.
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008
TABLE OF CONTENTS
INTRODUCTION ............... I
SITE HYDROGEOLOGY............. .........32.1 Geologic Setting....... ...................32.2 Hydrogeologic Setting ................42.3 Perched Zone Hydrogeology .........................5
2.3.1 Lithologic and Hydraulic Properties............... .........................6
2.3.1.1 Dakota .-.-.-......-7
2.3.1.2 Burro Canyon .............-.......7
2.3.2 Perched GroundwaterFlow ...............9
PERCHED ZONE HYDROGEOLOGY BENEATH AND DOWNGRADIENT
OF THE TAILINGS CELLS ................. 1I3.1 Saturated Thickness .................. I I3.2 Perched WaterFlow.......... -....-..123.3 Permeability .-......... 13
EVALUATION OF POTENTIAL FLOW PATHS AND TRAVEL TIMES
FOR TTYPOTHETICAL SEEPAGE ORIGINATING FROM CELL #3...-..................... I54.I Estimated Travel Time from the Base of Cell #3 and Proposed Cell48
to the Perched Zone ......... ......... 154.2 Estimated Travel Times from Tailings Cell #3 and Proposed Cell48
to Ruin Spring....... .................... 164.3 Estimated Total Travel Time from the Base of Tailings Cell #3
and Proposed Cell 48 to Ruin Spring........ .....................17
RECOMMENDED ADDITIONAL PERCHED ZONE MONITORING WELLS
DOWNGRADIENT OF PROPOSED CELL 48 ............. ..........21
REFERENCES............. .....23
LIMITATTONS STATEMENT.......... _._..____..____......2s
TABLES
Peel Hydraulic Test Results
Results of July 2002 and June 2005 Hydraulic Tests
J.
4.
5.
6.
7.
TABLE OF CONTENTS (Continued)
FIGURES
I Site PIan and Perched Well Locations2 Kriged Brushy Basin Contact Elevations3 Perched Water Levels, August 19904 Perched Water Levels, August 19945 Perched Water Levels, September 20026 Ikiged 3'd Quarter, 2007 Water Levels7 Portion of USGS Black Mesa 7.5' Sheet Showing Approximate Location of Tailing Cells
in Relation to Nearby Canyons and Ruin Spring8 Depth to Water, 3dQuarter 20079 Approximate Saturation Thickness, 3rd Quarter 200710 Site Plan showing Existing and Proposed Perched well Locations
Sile Hydrogeology GW Travel Times Proposed Wells Cell 48
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1. INTRODUCTION
This report provides a brief description of the hydrogeology of the White Mesa Uranium
Mill site (the 'Mill" or the "site"), located south of Blanding, Utah, and focuses on the
occrurence and flow of groundwater within the relatively shallow perched groundwater zone at
the site. Based on available existing hydrogeologic information from the site, estimates of
hydraulic gradients and intergranular rates of groundwater movement (interstitial or pore
velocities) are provided. These estimates are used to calculate average travel times for a
hypothetical conservative solute (assuming no dispersion) from existing tailings cell #3 and
proposed cell 48 at the site to a downgradient discharge point. Recommendations for additional
perched zone monitoring wells downgradient of proposed cell48 are also provided. Figure I is a
site plan showing the locations of perched monitoring wells and proposed cell48.
Tailings cell #3 has been in service for many years and a large quantity of groundwater
monitoring and hydraulic test data exists for perched monitoring wells completed around the
perimeter of the cell. Data from the vicinity of the cell are used in conjunction with data
downgradient of the cell to calculate perched zone hydraulic properties and groundwater
gradients between cell #3 and the discharge point. Cell 48 is proposed to be installed at the
downgradient edge of cell #3. The data from the immediate vicinity and downgradient of cell #3
used to compute rates of movernent and travel times for a hypothetical conservative solute will
likewise be used to calculate travel times for the hypothetical solute from proposed cell 48 to the
discharge point.
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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2. SITE ITYDROGEOLOGY
Titan, 1994 provides a detailed description of site hydrogeology based on information
available at that time. A brief summary of site hydrogeology that is based primarily on Titan,
1994, but includes the results of more recent site investigations, is provided below.
2.1 Geologic Setting
The White Mesa Uranium Mill site is located within the Blanding Basin of the Colorado
Plateau physiographic province. Typical of large portions of the Colorado Plateau province, the
rocks underlying the site are relatively undefonned. The average elevation of the site is
approximately 5,600 feet above mean sea level (amsl).
The site is underlain by unconsolidated alluvium and indurated sedimentary rocks
consisting primarily of sandstone and shale. The indurated rocks are relatively flat lying with
dips generally less than 3". The alluvial materials consist mostly of aeolian silts and hne-grained
aeolian sands with a thickness varying from a few feet to as much as 25 to 30 feet across the site.
The alluvium is underlain by the Dakota Sandstone and Burro Canyon Formation, which are
sandstones having a total thickness ranging from approximately 100 to 140 feet. Beneath the
Burro Canyon Formation lies the Morrison Formation, consisting, in descending order, of the
Brushy Basin Member, the Westwater Canyon Member, the Recapture Member, and the Salt
Wash Member. The Brushy Basin and Recapture Members of the Morrison Formation,
classified as shales, are very fine-grained and have a very low perrneability- The Brushy Basin
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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Member is primarily composed of bentonitic mudstones, siltstones, and claystones. The
Westwater Canyon and Salt Wash Mernbers also have a low average vertical permeability due to
the presence of interbedded shales.
Beneath the Morrison Formation lie the Summerville Formation, an argillaceous
sandstone with interbedded shales, and the Entrada Sandstone. Beneath the Entrada lies the
Navajo Sandstone. The Navajo and Entrada Sandstones constitute the primary aquifer in the
area of the site. The Entrada and Navajo Sandstones are separated from the Burro Canyon
Formation by approximately 1,000 to 1,100 feet of materials having a low average vertical
permeability. Groundwater within this system is under artesian pressure in the vicinity of the
site, is of generally good quality, and is used as a secondary source of water at the site.
2.2 HydrogeologicSetting
The site is located within a region that has a dry to arid continental climate, with average
annual precipitation of less than ll.8 inches, and average annual evapotranspiration of
approximately 61.5 inches. Recharge to aquifers occurs primarily along the mountain fronts (for
example, the Henry, Abajo, and La Sal Mountains), and along the flanks of folds such as Comb
Ridge Monocline.
Although the water quality and productivity of the NavajolEnhada aquifer are generally
good, the depth of the aquifer (approximately 1,200 feet below land surface [bls]) makes access
difficult. The Navajo/Entrada aquifer is capable of yielding significant quantities of water to
Site Hydrogeology CW Travel Times Proposed Wells Cell 48
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wells (hundreds of gallons per minute [gpm]). Water in wells completed across these units at the
site rises approximately 800 feet above the base of the overlying Summerville Forrration.
Perched groundwater in the Dakota Sandstone and Burro Canyon Formation is used on a
limited basis to the north (upgradient) of the site because it is more easily accessible. Water
quality of the Dakota Sandstone and Burro Canyon Formation is generally poor due to high total
dissolved solids (TDS) and is used primarily for stock watering and irrigation. The saturated
thickness of the perched water zone generally increases to the north of the site, increasing the
yield of the perched zone to wells installed north of the site.
2.3 Perched Zone Ilydrogeology
Perched groundwater beneath the site occurs primarily within the Burro Canyon
Formation. Perched groundwater at the site has a generally low quality due to high total
dissolved solids (TDS) in the range of approximately 1,200 to 5,000 milligrams per liter (mdL),
and is used primarily for stock watering and irrigation in the areas upgradient (north) of the site.
Perched water is supported within the Burro Canyon Formation by the underlying, fine-grained
Brushy Basin Member. Figure 2 is a contour map showing the approximate elevation of the
contact of the Burro Canyon Formation with the Brushy Basin Member, which essentially forms
the base of the perched water zone at the site. Contact elevations are based on perched
monitoring well drilling and geophysical logs and surveyed land surface elevations. As
indicated, the contact generally dips to the south./southwest beneath the site.
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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Groundwater within the perched zone generally flows south to southwest beneath the site.
Beneath the tailings cells, perched water flow is generally southwest to south-southwest.
2.3.1 Litholoeic and Hvdraulic Properties
Although the Dakota Sandstone and Burro Canyon Formations are often described as a
single unit due to their similarity, previous investigators at the site have distinguished between
them. The Dakota Sandstone is a relatively-hard to hard, generally fine-to-medium grained
sandstone cemented by kaolinite clays. The Dakota Sandstone locally contains discontinuous
interbeds of siltstone, shale, and conglomeratic materials. Porosity is primarily intergranular.
The underlying Burro Canyon Formation hosts most of the perched groundwater at the site. The
Burro Canyon Formation is similar to the Dakota Sandstone but is generally more poorly sorted,
contains more conglomeratic materials, and becomes argillaceous near its contact with the
underlying Brushy Basin Member. The permeability of the Dakota Sandstone and Burro Canyon
Formation at the site is generally low.
No significant joints or fractures within the Dakota Sandstone or Burro Canyon
Formation have been documented in any wells or borings installed across the site (Knight
Pi6sold, 1998). Any fractures observed in cores collected from site borings are typically
cemented, showing no open space.
Site Hydrogeologr GW Travel Times Propord Wells Cell 48
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Ianuary 8,2008 6
2.3.1.1 Dakota
Based on samples collected during installation of wells MW-l6 (no longer in service) and
MW-17, located immediately downgradient of the tailings cells at the site, porosities of the
Dakota Sandstone range from 13.4 to 26percent, averaging 20 percent, and water saturations
range from 3.7 to 27.2 percent, averaging 13.5 percent- The average volumetric water content is
approximately 3 percent. The permeability of the Dakota Sandstone based on packer tests in
borings installed at the site ranges from 2.71 x 10-6 centimeters per second (cm/s) to g.l2x lpa
cm/s, with a geomekic average of 3.89 x l0-5 cm/s.
2.3.1.2 Burro Canyon
The average porosity of the Burro Canyon Formation is similar to that of the Dakota
Sandstone. Based on samples collected from the Burro Canyon Formation at MW-16, located
immediately downgradient of the tailings cells at the site (and no longer in service), porosity
ranges from 2 to 29.1 percent, averaging 18.3 percent, and water saturations of unsaturated
materials range from 0.6 to 77.2 percent, averaging 23.4 percent. Titan, 1994, reported that the
hydraulic conductivity of the Burro Canyon Formation ftrnges from 1.9 x 10-7 to 1.6 x l0 -3 crn/s,
with a geometric mean of l.l x l0-5 cm/s, based on the results of l2pumping/recovery tests
performed in monitoring wells and 30 packer tests performed in borings prior to that time.
Hydraulic testing of wells Mw-01, MW-03, Mw-05, Mw-I7, Mw-lg, Mw-I9, Mw-
20, and MW-22 during the week of July 8, 2A02, and newly installed wells MW-23,1\/N,l-25,
Mw-27, Mw-28, Mw-29, Mw-30, Mw-31, Mw-32, Tw4-20,Tw+zl, and TW4-22 during
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008 7
June, 2005, yielded average perched zone permeabilities ranging from approximately 2 x lO'7
cm/s to 5 x 104 crn/s, similar to the range reported by previous investigators at the site (Hydro
Geo Chem, Inc [HGCf, 2002; HGC, 2005). Downgradient (south to southwest) of the tailings
cells, average perched zone permeabilities based on tests at MW-3, Mw-5, Mw-17, Mw-20,
MW'22, and MW-25 ranged from approximately 4 x l0-7 to I x lOa cm/s Permeability
estimates from these tests were based on pumping/recovery and slug tests analyzed using several
different methodologies.
A number of temporary (TW4-series) perched zone monitoring wells have been installed
at the site to investigate elevated concentrations of chloroform initially discovered at well MW-4
in 1999. Some of the conglomeratic zones encountered within the perched zone during
installation of these wells are believed to be partly continuous or at least associated with a
relatively continuous zone of higher permeability (International Uranium IUSA] Corporation
UUSAJ and HGC, 2001). The higher permeability zone defined by these wells is generally
located east to northeast of the tailings cells at the site, and is hydraulically cross-gradient to
upgradient of the tailings cells with respect to perched groundwater flow. Relatively high
permeabilities measured at MW-11, located on the southeastern margin of the downgradient
edge of tailings cell #3, and at MW-14, located on the downgradient edge of tailings cell #4, of
1.4 x 10-3 cm/s and 7.5 x tA-a cm/s, respectively (UMETCO , lgg3), may indicate that this zone
extends beneath the southeastem margin of the cells. This zone of higher pemreability within the
perched water zone does not appear to exist downgradient (south-southwest) of the tailings cells,
however. At depths beneath the perched water table, the zone is not evident in lithologic logs of
the southemmost temporary wells TW4-4 and TW4-6 (located east [cross-gmdient] of cell #3),
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008
nor is it evident in wells MW-3, MW-5, MW-12, MW-15, MW-16, MW-17, MW-20, MW-21,
or MW-22, located south to southwest (downgradient) of the tailings cells, based on the
lithologic logs or hydraulic testing of the wells-
Because of the generally low permeability of the perched zone beneath the site, well
yields are typically low (less than 0.5 gpm), although sustainable yields of as much as about
4 gpm may be possible in wells intercepting larger saturated thicknesses and higher permeability
zones in the northeast portion of the site. Sufficient productivity can, in general, only be
obtained in areas where the saturated thickness is greater, which is the primary reason that the
perched zone has been used on a limited basis as a water supply to the north (upgradient) of the
site.
2.3.2 Perched Groundwater Flow
Perched groundwater flow at the site has historically been to the south/southwest.
Figures 3 through 6 are perched groundwater elevation contour maps for the years 1990, 1994,
2002, and 200'1, respectively. The 1990, 1994, and 2002 maps were hand contoured because of
sparse data. As groundwater elevations indicate, the perched groundwater gradient changes from
generally southwesterly in the westem portion of the site, to generally southerly in the eastern
portion of the site. The most significant changes between the 2002 ar,d 2007 water levels result
from pumping of wells MW-4, TW4-19, TW4-20, and MW-26. These wells are pumped to
reduce chloroform mass in the perched zone east and northeast of the tailings cells.
Site Hydrogeolog5r GW Travel Times Proposed Wells Cell 48
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In general, perched groundwater elevations have not changed significantly at most of the
site monitoring wells since installation, except in the vicinity of the wildlife ponds and the
pumping wells. For example, relatively large increases in water levels occurred between 1994
and 2002 at MW-4 and MW-19, located in the east and northeast portions of the site, as shown
by comparing Figures 4 and 5. These water level increases in the northeastern and eastern
portions of the site are likely the result of seepage from wildlife ponds located near the
piezometers shown in Figure 5, which were installed in 2001 for the purpose of investigating
these changes. The increase in water levels in the northeastem portion of the site has resulted in
a local steepening of groundwater gradients over portions of the site. Conversely, pumping of
wells MW-4,TW4-l9,TW4-20, and lvIW-26 has depressed the perched water table locally and
reduced average hydraulic gradients to the south and southwest of these wells.
Perched water discharges in springs and seeps along Westwater Creek Canyon and
Cottonwood Canyon to the west-southwest of the site, and along Corral Canyon to the east of the
site, where the Burro Canyon Forrnation outcrops. The discharge point located most directly
downgradient of the tailings cells is Ruin Spring. This feature is located approximately 10,000
feet south-southwest of tailings cell #3 and is depicted on the USGS 7.S-minute quad sheet for
Black Mesa (Figure 7).
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008 10
3. PERCHED ZONE IIYDROGEOLOGY BENEATH AND DOWNGRADIENT OF
TIIE TAILINGS CELLS
Perched water as of the 3rd Quarter, 2007 was encountered at depths of approximately 57
to I 15 feet bls in the vicinity of the tailings cells at the site (Figure 8). Beneath tailings cell #3,
depths to water ranged from approximately 77 feet below top of casing (btoc) in the eastern
portion of the cell (at MW-25), to approximately 114 feet btoc at the southwest margin of the cell
(at MW-23). Assuming an average depth of the base of tailings cell #3 of 25 feet below grade,
this corresponds to perched water depths of approximately 52 to 89 feet below the base of the
cell, or an average depth of approximately 70 feet beneath the base of the cell. A similar
assumption can be made for proposed cell 48.
3.I SaturatedThickness
The saturated thickness of the perched zone as of the 3rd Quarter, 2007 ranges from
approximately 93 feet in the northeast portion of the site to less than 5 feet in the southwest
portion of the site (Figure 9). Beneath tailings cell #3, the saturated thickness varies from
approximately 49 feet in the eastemmost corner of the cell to approximately 7 feet in the western
portion of the cell. South-southwest of the tailings cells, the saturated thickness ranges from less
than I foot at MW-21 to approximately 26 feet at MW-17. The average saturated thickness
south-southwest of the tailings cells, based on measurements at MW-3, MW-5, MW-12, MW-14,
MW-15, MW17, and MW-20, is approximately 14 feet. The average saturated thickness based
on measurements at MW-5, MW-15, MW-3, and MW-20, which lay close to a line between the
center of tailings cell #3 and Ruin Spring, is approximately 12 feet. By projecting conditions at
Site Hy&ogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008 I I
these wells, the average saturated thickness is estimated to be approximately 10 to 15 feet
between MW-20 and Ruin Spring.
3.2 Perched Water Flow
Perched groundwater flow beneath the tailings cells has historically been southwest, with
the gradient steepening in recent years (since about 1994) and becoming more westerly as
perched water levels in the northeastern portion of the site have risen. Perched water flowing
beneath the tailings cells eventually discharges in springs and seeps located in Westwater
Canyon, to the south-southwest of the cells. The primary discharge point for perched water
flowing beneath the tailings cells is believed to be Ruin Spring, located approximately 10,000
feet south-southwest of the cells.
Perched zone hydraulic gradients currently range from a maximum of approximately 0.05
feet per foot (fl/ft) east of tailings cell #2 to approximately 0.01 fl/ft downgradient of cell #3,
between cell #3 and MW-20. The average hydraulic gradient between the downgradient edge of
tailings cell #3 and Ruin Spring can be approximated assuming the following:
The elevation of Ruin Spring, based on the USGS topographic map for Black Mesa,
is approximately 5,390 feet amsl.
The distance between the downgradient edge of tailings cell #3 and Ruin Spring is
approximately I 0,000 feet.
The average groundwater elevation at the downgradient edge of tailings cell #3 is
approximately 5,510 feet amsl.
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008 12
l)
2)
3)
Using these assumptions, the average perched zone hydraulic gradient between tailings cell #3
and Ruin Spring is approximately:
55 l0 - 5390 =O.Olzft I fi10,000
A hypothetical worst case average perched zone hydraulic gradient can also be estimated
assuming the perched water elevation to be coincident with the base of tailings cell #3. The
elevation of the base of tailings cell #3, which is also the approximate pre-existing land surface
elevation near the center of the cell, is approximately 5,580 feet amsl. Under these conditions,
for an unconfined perched zone, the maximum possible average perched zone hydraulic gradient
between tailings cell #3 and Ruin Spring would be approximately:
s580 - s390 =0.019ft I ft10,000
Although the downgradient edge of proposed cell 48 is closer to Ruin Spring (approximately
9,000 feet from Ruin Spring rather than about 10,000 feet), the above hydraulic gradient
calculations can also be applied to cell48.
3.3 Permeability
The average permeability of the perched zone downgradient of tailings cell #3 can be
approximated based on the pumping/recovery test and slug test data obtained from perched zone
wells located along the downgradient edge of and south of cell #3. Peel conducted hydraulic
tests at perched zone wells MW-I1, MW-I2, MW-14, and MW-15 n 1992 (LIMETCO, 1993).
Site Hy&ogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008 I 3
Results of these tests are provided in Table l. HGC conducted slug tests at perched zone wells
MW-3, MW-5, MW-17, MW-20, and MW-22 in July 2002 (HGC,2002), and MW-25 in June,
2005 (HGC,200s).
The HGC slug test results were analyzed using various solution methods including KGS
(Hydea 1994), and Bouwer-Rice (Bouwer and Rice, 1976). Each method yielded slightly
different results as shown in Table 2, which is based on Table 1 of HGC, 2002, and Table 1 of
HGC, 2005. A range of average permeabilities for the portion of the site south of the tailings
cells can be obtained by taking the geometric mean of the Peel test results and the results
obtained by the various solution methods used to analyze the HGC data. Averaging the Peel test
results for wells MW-ll, MW-12, MW-14, and MW-15 with the HGC KGS results for wells
MW-3, MW-5, MW-17, MW-20, MW-22, and MW-25 yields a geometric average of 2.3 x l0-5
crn/s, and similarly averaging the Peel test results with the HGC Bouwer-Rice results yields a
geomehic average of 4.3 x l0-s cm/s, as shown in Table 2. The "early timd'results at MW-5
using the Bouwer-Rice solution (from Table I of HGC, 2002) were used in the computations to
yield a conservatively high estimate of permeability.
Sile Hydrogeology GW Travel Times Proposed Wells Cell 48
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January8,2008 14
4. EVALUATION OF POTENTIAL FLOW PATHS AI{D TRAVEL TIMES FOR
ITYPOTITETICAL SEEPAGE ORIGINATING FROM CELL #3
Although more than 25 years of groundwater monitoring at the site has shown no impact
to perched water from the tailings cells, an evaluation of hypothetical transport of a conservative
solute in seepage from existing cell #3 and proposed cell 48 is presented assuming a flow path
from the base of the existing and proposed cells to the perched water, and thence to Ruin Spring.
Average travel times for a conservative constituent moving from the base of tailings cell #3 and
proposed cell 48 to the perched water, and then moving with the perched water to Ruin Spring,
are computed assuming no dispersion.
The porosities and water saturations used in the calculations were based on measurements
reported in Titan, 1994,for samples collected from the Dakota Sandstone during drilling of MW-
16 and Mw-17, and from the Burro canyon Formation during drilling of MW-16.
4.1 Estimated Travel Time from the Base of Cell #3 and Proposed CeIl 48 to the perched
Zone
Knight-Pi6sold estimated a maximum volumetric seepage rate for tailings cell #3 based
on cell construction and liner characteristics, of approximately 80 cubic feet per day (fVday) or
0.42 gpm over the entire cell (Knight-Pi6sold, 1998). Most of this seepage was estimated to be
via diffusion through the liner. This rate was estimated to decrease over time as the cell
desaturates once the final cover is emplaced. Assuming a cell fooprint of 3.38 x 106 ft2, this rate
is equivalentto 2.37 x l0-5 fttday or 0.0086 feet per year (fVyr).
Site Hy&ogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008 15
The average rate of downward movement of a conservative solute dissolved in the
seepage, assuming l) no dispersion, 2) an average water saturation of 0.20, 3) an average
porosity of 0.18, and assuming that this rate of seepage would not significantly raise the average
saturation of the underlying materials, can be approximated as:
o.oo86ft I yr
= 0.24 ft / vr(.20x.18)
The average time to travel 70 feet to the perched water zone would then be approximately 290
years. This is a conservative estimate because the average water saturations would be likely to
increase, thereby reducing the downward rate of travel, and increasing the travel time.
Assuming a similar travel time from the base of proposed cell 48 to the perched water
would be even more conservative because the improved liner system to be used for that cell
would result in less seepage than from cell #3. However, for purposes of calculation, potential
seepage rates and downward rates of movement for a hypothetical conservative solute will be
assumed to be the same for cell 48 as those calculated for cell #3.
4.2 Estimated Travel Times from Tailings Cell #3 and Proposed Cell48 to Ruin Spring
Under current conditions, the average hydraulic gradient between the downgradient edge
of tailings cell #3 to Ruin Spring is estimated to be 0.012, as discussed in Section 3.2. Assuming
the following:
Site Hydrogeology CW Travel Times Proposed Wells Cell 48
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January 8,2008 I 6
Average porosity
Average hydraulic gradient
Flow path length
Average penneability ftmge
:0.18
: A.Ol2
: 10,000 feet
:2.3 x 1o-5 to 4.3 x 10-5 cm/s
(0.064 ftlday to 0.120 fl/day)
the average rate of intergranular movement of perched groundwater (interstitial or pore velocity)
can be approximated to range from 0.0043 ftlday to 0.0080 ftJday (or 1.6 fl/yr to 2.9 ftlyr). The
estimated average travel time for a conservative solute, assuming no dispersion, from tailings
cell #3 to Ruin Spring would then be approximately 6,250 to 3,450 years over this range of
perrreabilities. Under conditions of the maximum possible average perched groundwater
gradient of 0.019 ftlft, as estimated in Section 3.2, and assuming the same permeabilities,
porosity, and path length as above, the estimated average travel times would range from
approximately 4,055 to 2,160 years.
For proposed cell 48, which is about 9,000 feet from Ruin SprinB, the estimated travel
times would be approximately 5,625 to 3,100 years using the gradient of 0.012, and
approximately 3,650 to 1,950 years using the gradient of 0.019.
4.3 Estimated Total Travel Time from the Base of Tailings Cell #3 and Proposed CeIl4B
to Ruin Spring
The total average travel time for a conservative solute from the base of tailings cell #3 or
proposed cell48 to Ruin Spring under current conditions would be the sum of l) the travel time
from the base of either cell to the perched water table, and 2) the time to travel within the
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008 17
perched zone to Ruin Spring. Based on the estimates provided in Sections 4-l and 4.2, the total
average travel time of a conservative solute (assuming no dispersion) over the range of average
permeability estimates would be between 6,540 and 3,740 years for cell #3, andbetween 5,915
and 3,390 years for proposed cell 48, assuming an average hydraulic gradient of 0.012 ft/ft. As
discussed in Section 4. 1, because the rate of movement of a conservative solute from the base of
cell 48 would likely be slower than for cell #3 because seepage rates would lower, the total
travel time would likely be higher than estimated above.
Conditions may hypothetically develop under which travel times may be reduced, such as
an increase in average perched zone groundwater gradients between tailings cell #3 or cell 48
and Ruin Spring (as discussed in Section 3.2) or as a result of reduced vadose zone travel times
due to development of a relatively large leak in either cell. Under hypothetical conditions in
which a relatively large leak were to develop, potentially reducing vadose zone travel times to
only a few years, the vadose zone travel time could be ignored, and the total average travel time
(assuming no dispersion) would range from approximately 6,250 to 3,450 years for cell #3, and
between 5,625 and 3,100 years for proposed cell 48, assuming an average hydraulic gradient of
0.012 fl/ft. Under hypothetical conditions in which the average perched zone hydraulic gradient
between either cell and Ruin Spring reached 0.019 fl/ft, which also implies a negligible vadose
zone travel time, the total average travel time (assuming no dispersion) over the estimated range
in permeability would be between approximately 4,055 and2,160 years for cell#3, and between
3,650 and 1,950 years for cell 48.
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008 18
Es ''na1ss based on hypothetical assumptions of a relatively large leak in tailings cell #3
or an average hydraulic gradient as high as 0.019 fl/ft betrveen either cell and Ruin Spring are
considered very conservative because they assume conditions that are unlikely ever to develop.
Furthermore the improved construction and leak detection system proposed for cell 48 would
make this hypothetical scenario even less likely for cell4B than for cell #3.
Site Hydrogeolory GW Travel Times Proposed Welts Cell 48
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January 8,2008 19
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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January &,2008 20
5. RECOMMENDED ADDITIONAL PERCIMD ZONE MONITORJNG WELLS
DOWNGRADIENT OF PROPOSED CELL 48
The current perched grotrndwater monitoring well network for the tailings cells includes
wells that are upgradient, crossgradient, and downgradient of the cells as shown in Figure 10.
Most of the wells are located along the margins of the cells and many that are between the cells
function as both upgradient wells for the cell located immediately downgradient of the wells and
as downgradient wells for the cell located immediately upgradient of the wells. For example,
well MW-30 functions as a downgradient well for cell #2 and as an upgradient well for cell #3.
Wells MW-5, MW-12, and MW-23 that currently function as downgradient wells for cell #3
would also serve as upgradient wells for proposed cell 48. The current arrangement of tailings
cell perched monitoring wells is conservative with respect to U.S. Environmental Protection
Agency (US EPA) Draft Technical Guidance (US EPA, 1992) which generally recommends
downgradient wells only along the downgradient margin of the facility which in this case would
be the entire complex of tailings cells.
Once proposed cell 48 is installed, an additional well or wells would be needed at the
downgradient edge of the cell to be consistent with EPA Draft Guidance (US EPA, 1992). As
shown in Figure 10, two additional wells are proposed, one at the southwest corner of proposed
cell 48 and one between the southwest comer well and existing well MW-I5. These installations
would conservatively maintain the approximate existing spacing as defined by the proximity of
MW-14 to MW-15 along the downgradient edge of existing cell 4A. Existing wells MW-3,
MW-20, and MW-21 would continue to firnction as distal downgradient wells for the entire cell
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008 21
complex. Once installed, sampling frequencies for the new wells will be based on testing of the
wells for perched zone hydraulic prcperties in the same fashion as for the existing wells.
Site Hydrogeolory GW Travel Times Proposed Wells Cell 48
H:V I 8000\ccll,lb\lrydrcell4b.docJanuary8,2008 22
6. REFERENCES
Bouwer, H. and R.C. Rice. 1976. Aslug test method for detennining hydraulic conductivity of
unconfined aquifers with completely or partially penetrating wells. Water Resources
Research, Vo. 12:3. Pp.423-428.
Hyder, 2., l.J. Butler, C.D. McElwee, and W. Liu. 1994. Slug tests in partially penetrating
wells. WaterResources Research. Vol. 30:11. Pp. 2945-2957.
Hydro Geo Chem. 2001. Update to report "Investigation of Elevated Chloroform
Concentrations in Perched Groundwater at the White Mesa Uranium Mill Near Blanding,
Utah".
Hydro Geo Chem. 2002. Hydraulic Testing at the White Mesa Uranium Mill Near Blanding,
Utah During July, 2002- Submitted to Intemational Uranium (USA) Corporation,
Denver, Colorado.
Hydro Geo Chem. 2005. Perched Monitoring Well Installation and Testing at the White Mesa
Uranium Mill, April Through June, 2005. Submitted to International Uranium (USA)
Corporation, Denver, Colorado.
KnighrPi6sold. 1998. Evaluation of Potential for Tailings Cell Discharge - White Mesa Mill.
Attachment 5, Groundwater Information Report, White Mesa Uranium Mill, Blanding,
Utah. Submitted to UDEQ.
TITAN. 1994. Hydrogeological Evaluation of White Mesa Uranium Mill. Submitted to Energy
Fuels Nuclear.
UMETCO. 1993. Groundwater Study. White Mesa Facilities. Blanding, Utah. Prepared by
UMETCO Minerals Corporation and Peel Environmental Services.
US EPA. 1992. EPA RCRA Ground-Water Monitoring: Draft Technical Guidance,
November 1992.
Site Hydrogeology GW Travel Times hoposed Wells Cell 48
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January 8,2008 23
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008 24
The opinions and recommendations presented in this report are based upon the scope of
services and information obtained through the perforrnance of the services, as agreed upon by
HGC and ttre party for whom this report was originally prepared. Results of any investigations,
tests, or findings presented in this report apply solely to conditions existing at the time HGC's
investigative work was performed and are inherently based on and limited to the available data
and the extent of the investigation activities. No representation, warranty, or guarantee, express
or implied, is intended or given. HGC makes no representation as to the accuracy or
completeness of any information provided by other parties not under contract to HGC to the
extent that HGC relied upon that information. This report is expressly for the sole and exclusive
use of the party for whom this report was originally prepared and for the particular purpose that
it was intended. Reuse of this report, or any portion thereof, for other than its intended purpose,
or if modified, or if used by third parties, shall be at the sole risk of the user.
Site Hydrogeology CW Travel Times Proposed Wells Cell 48
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January 8,2008 25
Site Hydrogeology GW Travel Times Proposed Wells Cell 48
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January 8,2008 26
TABLE 1
Pee! Hydraulic Test Resutts 1
Nofes.'
' From UMETCO,lgg3
Well llydreufic eondrrctMty
(cm/s)
vtw-11 1.4 x 10"
\rw-l2 2.2 x 1O'
vrw-14 7.5 x 10'
vtw-15 1.9 x 10-
H1718000\cell4b\Tables.xls: Table 1 11812008
TABLE 2
Results of July 2002 andJune 2005 Hydraulic Tests 2
Geometric Average of above tesf resulfs with Peet3 tesf results for MW-l1,
MW-12, MW-14, and MW'15.
2.3x10s I +.3x10-s
Nofes.'2 From HGC,2002; HGC,20053 From UMETCO,1993
Well Permeability in centimeteni per second
KGS Bouwer-Rice
vtw-3 4.0 x 10-7 1.5 x 10-5
\rw-5 3.5 x 10€2-4 x1O'5
MW.17 2.6 x 106 2.7 x 1O-5
vrw-20 9.3 x 10€
vw-22 1.0 x 10€7.9 x 106
MW-25 1.1 x 104 7.4 x 10-5
H:\718000\cel14b\Tables.xls: Table 2
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GEO
CHEM, INC.
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W}IITE MESA SITE
DOSE ASSESSMENT IN SUPPORT OF THE LICENSE
RENEWAL APPLICATION & ENVIRONMENTAL
REPORT FOR THE WHITE MESA URANIUM MILL
Prepared for:
Denison Mines (USA) Corp. (DUSA)
Prepared by:
SENES Consultants Limited
121 Granton Drive, Unit12
Richmond Hill, Ontario
L4B 3N4
February 2007
Printed on Recycled Paper Containing Post-Consumer Fibre
Q
Dose Assessment in Support of the License Renewal Application and Environmental Report
for the Wite Mesa Uranium Mill
EXECUTIVE SUMMARY
Denison Mines (USA) Corp. (DUSA) operates the White Mesa Uranium Mill (hereafter referred
to as the "mill") in San Juan County, Utah, approximately 6 miles (9.5 km) south of the city of
Blanding. The mill is located on a parcel of land and mill site claims covering approximately
5,415 acres (2,191ha). The mill is licensed by the State of Utah Division of Radiation Control
(DRC) to process uranium ore and selected alternate feed materials.
DUSA has commenced mining activities in the Colorado Plateau district, and conventional ores
are being hauled and stockpiled at the mill. In addition, DUSA has mining assets in the Aizona
Strip and processing of ores from those properties can be anticipated in the future. Milling of
conventional ore is scheduled for early 2008 when the milling of currently available alternate
feed material is completed (DUSA 2007).
This dose assessment was prepared in support of the license renewal application for the mill. An
element of the license renewal application is to complete a dose estimate to members of the
public based on the operations at the mill.
During the recovery of uranium from conventionally mined ore at the mill, small amounts of
uranium and other radioactive contaminants can be released to the atmosphere from various
processes and activities. The radioactivity can be dispersed by wind into the surrounding
environment and subsequently, via deposition to soil, plants and animals.
In this assessment, MILDOS-AREA was used to estimate the dose commitments that could
potentially be received by individuals and the general population within a 50 mile (80 km) radius
for the processing of Colorado Plateau ore or Arizona Strip ore. The expected ore grade from the
Colorado Plateau ore is an average of 0.25% U3Os and l.5Yo YzOs NRC 1980) while the
Arizona Strip ore is assumed to contain 0.637% U:Os (DUSA (2007a)). The proposed ore
process rate for the Colorado Plateau ore and Arizona Strip ore is approximately 730,000 tons
per year (tpy) (an average of 2000 tons per day). Assuming that the average uranium recovery is
at the historical recovery yield of 94Yo,approximately 1,715 tons (3,431,000 lbs) of U3Os per
year would be recovered from Colorado Plateau ore at the proposed ore process rate. Similarly,
approximately 4,371 tons (8,742,188 lbs) of U3Os per year would be recovered from Arizona
Strip ore at the proposed ore process rate. The proposed operating schedule at the mill is
assumed tobe Z4hr/day for 365 days per year.
The MILDOS-AREA calculated total annual effective dose commitments (including radon) were
compared to the Utah Administrative Code R3l3-15-301(l)(a) requirements that the dose to
individual members of the public shall not exceed 100 mrem/yr (radon included). Overall, the
34489 - February 2007 ES-I SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application and Environmental Report
for the White Mesa Uranium Mill
total annual effective dose commitments are at most 1.20 mrem/yr (effective dose for infant at
BHV-I) of the R3l3-15-301(1)(a) limit of 100 mrem/yr (radon included) to an individual
member of the public for the processing of Colorado Plateau ore. The total annual effective dose
commitments are at most 2.94 mremlyr (effective dose for infant at BHV-I) of the R3l3-15-
301(1)(a) limit of 100 mrem/yr (radon included) to an individual member of the public for the
processing of Arizona Strip ore. Therefore, the predicted annual effective dose commitments for
anticipated ore processing operations comply with R313-15.
In addition, the MILDOS-AREA-calculated 40 CFR190 annual dose commitment (excluding
radon) was compared to the 40 CFR190 Criterion of 25 mrem/yr to the whole body (excluding
the dose due to radon) and 25 mrem/yr to any other organ to any member of the public (EPA
2002). The 40CFR 190 doses were also used to demonstrate compliance with R313-15-101(4)
(i.e., the licensee must demonstrate that total effective dose equivalent to the individual member
of the public likely to receive the highest total effective dose equivalent will not exceed 10 mrem
(absent of the radon dose)). Overall, from Table 6.3, the 40 CFRI90 annual dose commitments
are at most 4.62 mrem/yr (dose to the bone for the teen at BHV-I) of the 40 CFRI9O dose
criterion of 25 mrem/yr for Colorado Plateau ore. In addition, the 40 CFR190 annual effective
dose commitments demonstrate compliance with the R3l3-15-l0l(4) limit of 10 mrem/yr to the
individual member of the public likely to receive the highest total effective dose equivalent.
From Table 6.8, the 40 CFR190 annual dose commitments are at most 11.7 mrem/yr (dose to the
bone for the teen at BHV-I) of the 40 CFRI9O dose criterion of 25 mremlyr for Arizona strip
ore. In addition, the 40 CFRI9O annual effective dose commitments demonstrate compliance
with the R313-15-101(4) limit of 10 mrem/yr to the individual member of the public likely to
receive the highest total effective dose equivalent. For Colorado Plateau ores, the maximum
effective dose is 0.535 mrem/yr and for Arizona Strip Ore it is 1.37 mrem/yr, in both cases for an
infant at BHV-I. Therefore, the predicted 40 CFR annual effective dose commitments for
anticipated ore processing operations comply with R313-15-101(4).
34489 - February 2007 ES-2 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
Wite Mesa Uranium Mill
34489 - February 2007 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
Wite Mesa Uranium Mill
LIST OF TABLES
PagS: No.
4.1 Characteristics of Tailings at White Mesa......... ........4-7
4.2 Radioactive Particulate and Radon Emission Rates (Colorado Plateau Ore).......... ........4-9
4.3 Radioactive Particulate and Radon Emission Rates (Arizona Strip Ore)........................4-9
6.1 Comparison of Annual Dose Commitments with Applicable Radiation
Protection Standards (Colorado Plateau Ore).......... ........-...........6-2
6.2 Total Annual Dose Commitments (mrem) for Meat lngestion Pathway
(Colorado Plateau Ore).......... ..................6-5
6.3 Comparison of 40 CFR190 Annual Dose Commitments with Applicable
Radiation Protection Standards (Colorado Plateau Ore) .......... ...6-6
6.4 40 CFR190 Annual Dose Commitments (mrem) for Meat Ingestion Pathway
(Colorado Plateau Ore).......... ..................6-9
6.5 Annual Population Dose Commitments within 50 miles (80 km) of the Mill
for Colorado Plateau Ore........... ..............6-9
6.6 Comparison of Annual Dose Commitments with Applicable Radiation
Protection Standards (Arizona Strip Ore) ................6-10
6.7 Total Annual Dose Commitments (mrem) for Meat lngestion Pathway
(Arizona Strip Ore) ..............6-13
6.8 Comparison of 40 CFR190 Annual Dose Commitments with Applicable
Radiation Protection Standards (Arizona Strip Ore) .................6-14
6.9 40 CFR190 Annual Dose Commitments (mrem) for Meat Ingestion Pathway
(Arizona Strip Ore) ..............6-17
6.10 Annual Population Dose Commitments within 50 miles (80 km) of the Mill
for Arizona Strip Ore ...........6-17
LIST OF F'IGURES
Paee No.
4.1 Source Locations.. ..................4-2
5.1 Receptor Locations with Respect to the Vanadium Stack......... ....................5-2
34489 - February 2007 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
White Mesa Uranium Mill
ACRONYMS & ABBREVIATIONS
ALC Allowable Concentration
ANL Argonne National Laboratory
ALARA As Low As Reasonably Achievable
Avg. Average
ASCII American Standard Code for Information lnterchange
Bi-210 Bismuth 210
Bi-214 Bismuth 214
CCD Counter Current Decantation
CFR Code of Federal Regulations
Ci Curie
DCF Dose Conversion Factor
DRC State of Utah Division of Radiation Control
DUSA Denison Mines (USA) Corp.
EPA Environmental Protection Agency
Ew Process Emission Factor
F Radon Release
FES Final Environmental Statement
Fs Annual frequency of occurrence of wind group S
ft Feet
ft3 Cubic feet
grams
g ore Grams of ore
GPS Global Positioning System
GUI Graphical User Interface
ha hectares
hr hours
ICRP International Commission on Radiological Protection
ID Induced Draft
lbs Pounds
km Kilometres
kts Knots
NESHAPS National Emission Standards for Hazardous Air Pollutants
NRC Nuclear Regulatory Commission
NUREG Regulatory Guide
m Meters
m' Square metres
rffem Millirem
34489 - February 2007 AC-1 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
Wite Mesa Uranium Mill
MPC
Pb-210
Pb-zt4
pci
Po-210
Po-218
Pla-226
Rn-222
Rs
s
S
SENES
TGLM
Th-230
tpy
U:Os
Unat
u-234
u-235
u-238
VzOs
yd3
yr
Maximum Permissible Concentration
Lead2l0
Lead2I4
picoCurie
Polonium 210
Polonium 218
Radium 226
Radon222
Resuspension rate for wind group S
Seconds
Emission Rate
Specialists in Energy, Nuclear and Environmental Science
Task group on Lung Dynamics Lung Model
Thorium 230
tons per year
Triuranium octaoxide ("Yellowcake")
Natural Uranium
Uranium 234
Uranium 235
Uranium 238
Vanadium Oxide
Cubic yards
Years
34489 - February 2007 AC.2 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
Wite Mesa Uranium Mill
1.0
l.t
INTRODUCTION
BlcrcRouNo
Denison Mines (USA) Corp. (DUSA) operates the White Mesa Uranium Mill (hereafter referred
to as the "mill") in San Juan County, Utah, approximately 6 miles (9.5 km) south of the city of
Blanding. The mill is located on a parcel of land and mill site claims covering approximately
5,415 acres (2,19I ha). The mill was built in 1979 and licensed by the U.S. Nuclear Regulatory
Commission (NRC) to process uranium ore and selected altemate feed materials. The mill began
operations in July 1980. In August 2004, the State of Utah became an Agreement State for the
regulation of uranium mills, and primary regulatory authority over the mill was assumed by the
State of Utah Division of Radiation Control (DRC) at that time.
The mill is a standard design with both uranium and vanadium circuits and uses the acid leach-
solvent extraction process for uranium recovery from uranium ores and uranium/vanadium ores.
Vanadium in uranium/vanadium-bearing ores is partially solubilized during leaching, and the
dissolved vanadium present in uranium raffinate is further processed for recovery of vanadium
before recycling (NUREG 1979).
In the early 1990s, the mill began receiving "alternate feed material" (uranium-bearing materials
other than conventionally mined ores) for processing. From 1999 to present, the mill has relied
solely on alternate feed materials. The mill goes on standby for periods of time and then it
processes the stockpiled altemate feeds for the recovery of uranium. The residual tailings from
these processes are stored in the tailings ponds on-site. DUSA has commenced mining activities
in the Colorado Plateau district and conventional ores are being hauled and stockpiled at the mill.
In addition, DUSA has mining assets in the Arizona Strip and processing of those ores can be
anticipated in the future. Milling of conventional ore is scheduled for early 2008, when the
milling of currently available alternate feed material is completed (DUSA 2007).
This dose assessment was prepared in support of the license renewal application for the mill. An
element of the license renewal application is to complete a dose estimate to members of the
public based on the operations at the mill. The goal is to determine potential doses to both
nearby individuals and to populations in the vicinity of the mill from ore processing operations at
the mill.
34489 - February 2007 l-1 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
White Mesa Uranium Mill
1.2 Os"rrcrrvB
The objectives of this assessment are to estimate the potential annual doses to the people living
close to the mill and to the population living within 50 miles (80 km), from any releases to the
atmosphere of natural uranium (i.e., uranium-238 decay chain and associated radioactive
constituents) during the routine ore processing operations.
The mill is licensed for the annual recovery of 4,380 tons of uranium (as UlOs) The amount of
ore needed to provide that quantity of uranium depends on the grade(s) of the ores processed,
with larger quantities of low grade ores and smaller quantities of higher grade ores required to
achieve the same production. The mill uses an acid leach-solvent extraction process for uranium
recovery with a nominal recovery of approximately 94Yo, with remainder of the uranium being
discharged to tailings.
The ore supply expected for the mill is typically from mining activities on the Colorado Plateau
and Arizona Strip districts. The expected ore grade from the Colorado Plateau district is an
average of 0.25o/o U:Os and l.5YoYzOs NRC 1980) while the Arizona Strip ore is assumedto
contain 0.637% U:Os and no vanadium (DUSA (2007a)).
In this assessment, the doses to individual members of the public are estimated separately for the
processing of Colorado Plateau and Arizona Strip ores. The proposed ore process rate for the
Colorado Plateau ore and Arizona Strip ore is approximately 730,000 tons per year (tpy) (an
average of 2000 tons per day). Assuming that the average uranium recovery is at the historical
recovery yield of 94Yo, approximately 1,715 tons (3,431,000 lbs) of U3Os per year would be
recovered from Colorado Plateau ore at the proposed ore process rate. Similarly, approximately
4,371 tons (8,742,188lbs) of U3O3 per year would be recovered from Arizona Strip ore at the
proposed ore process rate.
The activity concentration of the U-238 in the ore is calculated as follows:
ActivityConcentration=(OreGrade (gUrOr/gore))(%U-238lgUrO*)(SpecificActivityof U-238) (1)
where,
Ore Grade (g U3Os/ g ore) : 0.0025 for Colorado Plateau Ore and 0.00637 for Arizona
Strip Ore
%U-238lgof U:Os:0.848
Specific Activity of U-238:3.30 x 105 pCi/gtJ-2381gorc
a
a
t-234489 - February 2007 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
White Mesa Uranium Mill
Using equation 1, the activity concentration of U-238 for Colorado Plateau ore is 700 pCi
tJ-2381g ore. Similarly, the activity concentration of U-238 for Arizona Strip ore is 1783 pCi
U-Z3&lgore. In all cases, the ores are assumed to be in secular equilibrium.
It should be noted that the current licensed production capacity is 4,380 tons of UrOs
(8,760,000 lbs of UsOr) per year. Therefore, the processing of Colorado Plateau ore is
approximately at 40Yo of the current licensed U3Os production capacity while the processing of
Arizona Strip ore is just below the current licensed yellowcake production capacity. The
proposed operating schedule at the mill is assumed to be 24 hr/day for 365 days per year.
1.3 AppRoacH
The MILDOS computer code calculates the dose commitments received by individuals and the
general population within a 50 mile (80 km) radius of an operating uranium recovery facility.
The MILDOS code is an NRC-approved code designed as a tool to provide input on regulatory
and compliance evaluations for various uranium recovery operations.
As part of this assessment, the EnecoTech analysis (EnecoTech 1991a and l99lb) was reviewed
to examine the input parameters and emissions calculations used to perform the previous
MILDOS modeling for the mill in 1991. The intent of the review was to ensure that issues
addressed in 1991 were addressed in the current assessment where relevant.
It should be noted that the MILDOS code developed in 1981 has gone through a number of
changes over the years and served as the basis for the development of the MILDOS-AREA code.
The approach used for this assessment is to evaluate the exposure pathways considered in the
EnecoTech analysis with the updated MILDOS-AREA code. All sources considered in the
EnecoTech analysis (EnecoTech 1991a) are considered in this assessment and updated as
appropriate to current conditions. As discussed later, emissions from the vanadium stacks are
also considered in this analysis. A description of the sources used in this assessment is provided
in Section 4.0.
The source emissions calculations for airborne radioactive releases at the mill include those
related to dust generation during ore handling, area source dusting from ore pad stockpiles and
the tailings ponds. The source emissions calculations generally follow the guidance of NRC's
Regulatory Guide 3.59 (NRC 1987) and NUREG-0706 (NRC 1980). Details of emissions
estimates are provided in Appendix A.
34489 - February 2007 l-3 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
Wite Mesa Uranium Mill
Many of the receptors used in the EnecoTech analysis were also used in this assessment. A
description of the receptors used in this assessment is provided in Section 5.0. Locations for the
sources and receptors used in this assessment were updated with Global Positioning System
(GPS) coordinates provided by DUSA (DUSA 2007b).
The physical parameters pertaining to particle size (and distribution) are consistent with the
EnecoTech analysis. These parameters are the default values within the MILDOS-AREA code
(ANL 1998) as well as in NUREG-0556 (NRC 1979).
The dose to receptors near the mill was estimated using MILDOS-AREA for the processing of
Colorado Plateau ore and, separately, for the processing of Arizona Strip ore. The proposed ore
process rate for the Colorado Plateau ore is approximately 730,000 tpy which would recover
approximately 2,573 tons (3,431,000 lbs) of U3Os per year (assuming that the average uranium
recovery is 94%). The proposed ore process rate for Arizona Strip ore is approximately 730,000
tpy, which would recover approximately 4,371tons (8,742,188 lbs) of U3O3 per year (assuming
that the average uranium recovery is 94%).
In addition to doses to individual receptors, the dose received by the general population within an
50 mile (80 km) radius of the mill is predicted.
CoNrnNrs On THrs Rsponr
The remainder of this report is arranged into seven sections.
Section 2.0, Regulatory Compliance, provides a description of the regulatory framework
pertaining to the applicable dose limits to members of the public from licensed activities at the
mill.
Section 3.0, Radiation Dose Assessment, describes the method used to estimate the radiation
doses to members of the public and how MILDOS-AREA was used. Section 3.0 also describes
how the MILDOS-AREA software has evolved, highlighting some of the key differences
between the updated version, MILDOS AREA (NRC 1998), and the original version of
MILDOS.
Section 4.0, Source Terms, describes the source terms and source emission rates related to the
ore processing operations and other input parameters required (i.e., meteorological data and
population data) for the MILDOS-AREA runs. The source emission rates were calculated for
processing Colorado Plateau ore and Arizona Strip ore based on the ore grade, ore process rate
and uranium recovery yield.
1.4
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Section 5.0, Receptors, describes the receptors used in the MILDOS-AREA runs.
Section 6.0, Radiation Dose Estimates, provides the dose results from the MILDOS-AREA
runs using the parameters described in Sections 4.0 and 5.0.
Section 7.0, Overviews, provides a summa.ry of the dose estimates from the MILDOS-AREA
runs.
Section 8.0, References, provides a list of reference material used to prepare this report.
Appendix A: Emissions Calculations describe the basis of the emission estimates for each
source.
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2.0 REGULATORY COMPLIANCE
The DRC has the regulatory authority over the license issued for the site. As required by Utah
Administrative Code R313-15-101(2), the mill shall, to the extent practical, employ procedures
and engineering controls based upon sound radiation protection principles to achieve
occupational doses and doses to members of the public that are as low as reasonably achievable
(ALARA). The licensee is required to demonstrate that the total dose equivalent to individual
members of the public from the licensed operation does not exceed 0.1 rem in a year, exclusive
of the dose contribution from natural background (including radon) and medical sources. Under
10 CFR20.1301 (NRC l99l), the NRC has adopted the provisions of the U.S. Environmental
Protection Agency (EPA) environmental radiation standards in 40 CFRI9O (EPA 2002). This
subpart requires that the licensee provide reasonable assurance that the radiation attributed the
mill operations does not exceed the annual dose of 25 millirem (mrem) to the whole body,
75 millirem to the thyroid and25 millirem to any other organ of any member of the public (radon
and it daughters excepted). In addition, 10 CFR20.1301 (d) (R313-15-l0l(4)) sets a constraint
limit on air emissions of radioactive material to the environment, excluding Radon-222 and its
daughters such that the individual member of the public likely to receive the highest total
effective dose equivalent will not exceed 10 mrem/yr.
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3.0
3.1
RADIATION DOSE ASSESSMENT
ENrcorrcH ASSESSMENT
As mentioned in Section 1.3, all of the sources considered by EnecoTech are addressed in this
analysis. In addition, the vanadium stack which is an additional point source, is considered in
this assessment. The emission calculations from the mill point sources (grinder, loading ore to
the gizzly, yellowcake stack and vanadium stack) and area sources such as the ore pads and the
tailings ponds were revised based on the new operating parameters and meteorological data
provided by DUSA. Some of the receptors used in the EnecoTech analysis are used in this
assessment. In addition, there are new receptor locations added to this assessment. Locations for
the sources and receptors used in this assessment were updated using the GPS coordinates
provided by DUSA (DUSA 2007b).
A description of the sources and receptors used in this assessment is provided in Sections 4.0 and
5.0, respectively. It should be noted that the MILDOS code used in the EnecoTech analysis is
outdated. The MILDOS code has been updated to MILDOS-AREA; the most up-to-date
MILDOS-AREA code version 2.20P is used in this assessment. A discussion on the
development of the MILDOS code is provided in Section 3.2.
GnNnnal lxponnnarroN ABour Mrr-nos-Anra
The MILDOS computer code was developed from the version IV for Argonne National
Laboratory's (ANL's) Uranium Dispersion and Dosimetry (UDAD) computer program 1981.
The MILDOS program was based on the models and assumptions from the U.S. NRC's Draft
Regulatory Guide RH802-4 (Calculational Models for Estimating Radiation Doses to Man from
Airbome Radioactive Material Resulting from Uranium Milling Operation) and portions of the
UDAD document (Strenge and Bender 1981).
In 1989, ANL developed MILDOS-AREA code by modifying the MILDOS code developed in
1981. The MILDOS-AREA code was designed or used on IBM or IBM compatible computers;
the changes made were intended to enhance capabilities for calculating dose from large area-
sources and updated dosimetry calculations. The major revision from the original MILDOS code
is the treatment of atmospheric dispersion from area sources; MILDOS-AREA substituted a
finite-element approach for the virtual-point source method (the algorithm used in the original
MILDOS code) when specified by the user. The new approach subsequently led to a reduction
in the number of sources from 20 to 10 in MILDOS-AREA due to the fact that a large area can
be considered as a single source rather than two or more point sources.
3.2
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The internal dosimetry calculations were also updated in MILDOS-AREA. In the original
version of MILDOS, the dose to exposed individual is calculated for comparison with
requirements of both 40 CFR190 and 10 CFR Part 20 (R313-15). The calculations of ingestion
DCFs were based on ICRP Publication 2 and 10A's ingestion models (ICRP 1966). The
inhalation DCFs are calculated by the ANL computer program UDAD (Momeni 1979) in
accordance with Task group on Lung Dynamics lung model (TGLM) of the lnternational
Commission on Radiological Protection (ICRP 1966; ICRP 1972). ICRP Publication 19 (ICRP
1972) gives dose commitments to adult members of the public at age 20 that are assumed to live
another 50 years. DCFs are provided as a function of particle size and organ for the
radionuclides U-238, U-234,Th-230,Ra-226, Pb-210, Po-210 and Bi-210. The inhalation dose
factors incorporated into MILDOS-AREA are calculated using the dosimetric model from ICRP
Publication 30 (ICRP 1979) (Yu 1991); the inhalation dose factors are provided for the age
groups of infant, child, teenager and adult. However, these factors are fixed internally in the
code, and are not part of the input options. The annual average air concentrations were
computed to the maximum permissible concentrations (MPCs) in 10 CFR Part 20. The MPCs in
l0 CFR20 (incorporated by reference in R3l3-15) were revised in 1994 to incorporate the
updated dosimetry to the ICRP 1978 recommendations.
ln 1997, the MILDOS-AREA code was updated to meet the requirements of the revised l0 CFR
Part 20. The dose limit to the general public also changed; which led to a revised calculation of
the allowable concentrations (ALCs) for unrestricted areas, with MPC replaced with the term
"effluent concentrations".
In 1998, ANL again updated the MILDOS-AREA code in an attempt to improve the "user
friendliness" of the software. In the past, the user must develop an input file in an American
Standard Code for Information Interchange (ASCID file containing values that are required by
the code. The code executes this file to produce the output. The latest version of MILDOS-
AREA, has a graphical user interface (GUD which provides an interface for the user to input
each parameter needed for the calculations in the Windows operating system. The GUI allows
the results of the MILDOS-AREA calculations to be viewed. The 1998 update was the last time
ANL made changes to the MILDOS-AREA code. The most up-to-date version of MILDOS-
AREA is used in this assessment.
MILDOS-AREA calculates the impacts based on annual average air concentrations of nuclides
considered. The human pathways considered in MILDOS-AREA for individual and population
impacts are: inhalation, external exposure from ground concentrations, external exposure from
cloud immersion, ingestion of vegetables, ingestion of meat and ingestion of milk.
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3.3 TUB Usn Or Mrloos-AREA Ix Turs AssnssurN:r
The 1991 EnecoTech analysis conducted by EnecoTech Environmental Consultants (under
contract from Umetco Minerals) evaluated the potential radiological doses arising from the
production of 8,760,000 lbs of U3Os per year at the mill from processing conventionally mined
ores. As mentioned, the original MILDOS code is no longer applicable.
In this assessment, the most up-to-date MILDOS-AREA code version 2.20P (ANL 1998a) was
used to estimate potential radiation doses to members of the public estimated from the processing
of Colorado Plateau or Arizona Strip ores, in separate cases, at the proposed ore process rates for
each ore. As mentioned, the proposed ore process rate for the Colorado Plateau ore is
approximately 730,000 tpy would recover approximately 1,715 tons (3,431,000 lbs) of U3Os per
year (assuming that the average uranium recovery is 94%). The proposed ore process rate for
Arizona Strip ore is approximately 730,000 tpy would recover approximately 4,371 tons
(8,7 42,188 lbs) of yellowcake per year (assuming that the average uranium recovery is 94%).
MILDOS-AREA was used to design a conceptual model of the mill. MILDOS-AREA requires
the location of sources and receptors to be defined by the user; the locations are calculated
relative to the reference point at the mill on a Cartesian grid system. The reference point used
for the MILDOS-AREA code used in this assessment was the vanadium stack. The GPS
coordinates were ploffed using Google Earth Pro (Google 2005). The easting, northing and
elevation of each source and receptor relative to the vanadium stack were measured in Google
Earth Pro. The measured coordinates are entered directly for point sources. For area
(quadrilateral) sources (i.e., ore pads and tailings ponds), the user must enter the boundaries and
elevation of the area source which are calculated based on the easting and northing of the source.
The sources are defined to represent each significant radionuclide release point at the mill;
radionuclide releases for particulates and radon are defined by the user for point sources.
MILDOS-AREA calculates the release rates from area sources based on the radionuclide
concentrations, source area and meteorological data.
MILDOS-AREA only considers airborne releases of radioactive materials; releases to surface
water and groundwater are not addressed. The U-238 decay chain is assumed to be the only
significant source of radiation from uranium milling operations (the contribution from the U-235
chain is less than 5o/o of that from the U-238 chain). The particulate releases include U-238,
Th-230, Ra-226 and Pb-210. The gaseous releases are defined for Rn-222 with in-growth of
short-lived daughter products also considered. TheseRn-222 daughters include Po-218, Pb-214,
Bi-214, Pb-210 and Po-210. The model accounts for the releases and in-growth of other
radionuclides using the assumption of secular equilibrium within the U-238 decay chain.
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The transport of model radiological emissions from the point and area sources is predicted using
a sector averaged Gaussian plume dispersion model. The dispersion model uses the
meteorological data provided by the user and also includes mechanisms of dry deposition of
particulates, re-suspension, radioactive decay and progeny in-growth and plume reflection.
Deposition build-up and in-growth of radioactive progeny are considered in estimating ground
concentrations.
The impacts to humans through various pathways are estimated based on the calculated annual
average air concentrations of radionuclides. The pathways considered in this analysis include:
inhalation, external exposure from ground concentrations, external exposure from cloud
immersion, and ingestion of meat and vegetables.
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4.0 SOURCE TERMS
The radionuclides of concern for license renewal modeling consideration include; U-238 and its
daughters Th-230, Ra-226, Pb-210 andRn-222 which are assumed to be in secular equilibrium
with the ore. The radioactive particulates and radon are emitted from airborne radioactive
releases related to dust generation during ore handling (unloading ore from truck to ore pads and
loading ore to the gizzly), point sources (grinder, yellowcake stacks and vanadium stack) and
area source dusting from ore pad stockpiles and the tailings ponds. The large area sources such
as the tailings area are divided into smaller sources (four tailings ponds) to allow for the size and
irregular shape ofthese areas.
As mentioned in Section 3.3, the source locations used in the EnecoTech analysis were revised
using the GPS coordinates provided by DUSA (DUSA 2007b). The coordinates for all the
sources except for the grinder were calculated first by plotting the GPS coordinates provided by
DUSA (DUSA 2007b) in Google Earth Pro and then using the measuring tool in Google Earth
Pro to measure the easting, northing and elevation of each source relative to a reference point at
the mill (i.e., the vanadium stack). The source locations (plotted in Google Earth) are shown in
Figure 4.1.
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FIGURE 4.1
SOURCE LOCATIONS
Source Legend:
11 Vanadium Stack12 Ore Pad13 Grizzly
14 Tailings Pond'l
15 Tailings Pond 216 Tailings Pond 3
17 Tailings Pond 418 North Yellowcake Stack
19 South Yellowcake Stack20 Grinder
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The dose to members of the public is estimated for the processing of Colorado Plateau ore or
Arizona Strip ore in separate cases. Therefore, the emission calculations are provided for each
ore type based on the activity concentration of U-238 in the ore, expected ore grade, average
uranium recovery and the proposed ore process rate. It should be noted that the MILDOS-AREA
model for Colorado Plateau ore has an additional point source (i.e., vanadium stack) since the ore
may contain vanadium (assumed at l.5o/o VzOs). A description of the approach used to calculate
the emissions from the point and area sources are described in Section 4.1 and 4.2,respectively.
Detailed source emissions calculations are provided in Appendix A.
4.1 PorNr SouncBs
Mill point sources used in the EnecoTech analysis were also used in this assessment. These
sources include the grinder, loading ore to the gizzly and yellowcake stacks (north and south).
The vanadium stack described in section 4.1.4 is exclusive to the processing of Colorado Plateau
ore. A description of the approach used to calculate the emissions from point sources is provided
in this section.
4.1.1, Grinder
There is no onsite crushing of the ore, only a wet grinding operation. The ore dust emissions are
controlled because the material is wet during the grinding operations. The particulate emission
control from the grinding operation is assumed to be 99.9%o. U-238 and its decay daughters are
all emitted at a rate of 9.27E-05 Cilyr (assuming secular equilibrium) for Colorado Plateau ore.
This calculation assumes the proposed ore process rate of 730,000 tpy and an ore specific
activity of 700 pCilg. Similarly, U-238 and its decay daughters are all emitted at a rate of
2.368-04 Cilyr (assuming secular equilibrium) for Arizona Strip ore. This calculation assumes
the proposed ore process rate of 730,000 tpy and an ore specific activity of 1783 pCilg. The
emission rates for Rn-222 released during wet grinding is calculated assuming that only 20% of
the radon is available for release or emanation from the mineral grains in which it is produced
(NUREG 1980). The Rn-222 concentration in the ore was assumed to be equal to the U-238
concentration. The Rn-222 released during wet grinding is 92.7 Cilyr and 236 Cilyr for
Colorado Plateau ore and Arizona Strip ore, respectively.
4.1.2 Grizzly
The emissions from trucks dumping ore onto the gizzly is highly controlled; the truck dump
area is enclosed on three sides and has a negative pressure on it during dumping activities. The
ore is delivered wet with an average moisture content of l0%o. The exhaust from the induced
draft (ID) fans used on the grizzly is ducted through a baghouse. The combined particulate dust
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control on this operation is assumed tobe99.9o/o. U-238 and its decaydaughters are all emitted
at a rate of 9.27E-05 Cilyr (assuming secular equilibrium) for Colorado Plateau ore. This
calculation assumes the proposed ore process rate of 730,000 tpy and an ore specific activity of
700 pCilg. Similarly, U-238 and its decay daughters are all emitted at a rate of 2.368-04 Cilyr
(assuming secular equilibrium) for Arizona Strip ore. This calculation assumes the proposed ore
process rate of 730,000 tpy and an ore specific activity of 1783 pCi/g.
4.1,3 Yellowcake Stacks
The mill has two yellowcake dryers (north and south yellowcake dryers). From the EnecoTech
analysis, stack tests on the yellowcake dryer yielded a yellowcake emission rate of 0.06 lbs/hr
U:Os when the process rate was 1300 lbs/hr. This yields an emission rate of 0.092 lbs/hr of
yellowcake per ton of feed (EnecoTech l99la and 1991b). The emission rate is with all the
particulate emissions controls. Since there are north and south yellowcake dryers, the stack
emissions from U-238 and its decay daughters are assumed to be divided equally between the
two (i.e., north and south yellowcake stacks), and are based on the proposed ore process rate of
Colorado Plateau ore and Arizona Strip Ore. Therefore, U-238 is all emitted at a rate of
1.01E-02 Cilyr for Colorado Plateau ore. This calculation assumes the proposed ore process rate
of 730,000 tpy and an ore specific activity of 700 pCilg. Similarly, U-238 is emitted at a rate of
2.368-04 Cilyr for Arizona Strip ore. This calculation assumes the proposed ore process rate of
730,000 tpy and an ore specific activity of 1783 pCilg.
Based on field measurements, the decay daughters of U-238 (Th-230, Ra-226 and Pb-210) are
processed along with yellowcake at 0.22o/o,0.13% and 0.78oh, respectively (EnecoTech 1991a
and l99lb). Therefore, the decay daughters Th-230, Ra-226 and Pb-210 are emitted at a rate of
2.228-05 Cilyr,1.31E-05 Cilyr and 7.88E-05 Cilyr, respectively for Colorado Plateau ore. This
calculation assumes the proposed ore process rate of 730,000 tpy (divided equally between the
north and south yellowcake dryers) and an ore specific activity of 700 pCilg. Similarly, the
decay daughters Th-230, Ra-226 and Pb-210 are emitted at a rate of 5.67E-05 Cilyr,
3.35E-05 Cilyr and2JlE-04 Ct/yr, respectively for Arizona Strip ore. This calculation assumes
the proposed ore process rate of 730,000 tpy (divided equally between the north and south
yellowcake dryers) and an ore specific activity of 1783 pCilg.
Since the ore processing steps reject nearly all the radium to the tailings, very little radon is
released during the production of yellow cake. No significant radon releases occur during
yellowcake drying and packaging, since only about 0.lo/o of the original Ra-226 in the ore is
found in yellowcake. Therefore, the amount of Rn-222 emitted from the yellowcake stack is
assumed to be negligible.
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4.1.4 Vanadium Stack
The vanadium stack source term was only used in the MILDOS-AREA model for Colorado
Plateau ore. The vanadium present in the Colorado Plateau ore is partially solubilized during
leaching. The dissolved vanadium is present in uranium raffinate. Depending on its vanadium
content, the uranium raffinate will either be recycled to the counter-current decantation step or
further processed for recovery of vanadium before recycling. The product from the vanadium
recovery contains less than 0.005% U:Os (NUREG 1980). Therefore, the emission rate for the
vanadium stack was calculated to be 0.005o/o of the total emission rate from the yellowcake
stacks (north and south yellowcake stack). U-238 is emitted at a rate of 1.01E-06 Ci/yr for
Colorado Plateau ore. This calculation assumes the proposed ore process rate of 730,000 tpy and
an ore specific activity of 700 pCilg.
By adopting the EnecoTech analysis (EnecoTech l99la and 199lb) measurements for the decay
daughters of U-238 (Th-230, Ra-226 and Pb-210) processed along with yellowcake of 0.22oh,
0.13% and0.78o/o, respectively, the emissions from the remaining radionuclides are assumed to
be negligible and in any event are likely discharged to the tailings ponds.
4.2 Anna Souncrs
Mill area sources used in the EnecoTech analysis were also used in this assessment. These
sources include the ore pads and the tailings ponds. The area of the ore pad was reduced in this
assessment to match anticipated future requirements as discussed below. In addition, the number
of tailings ponds was reduced from 5 (used in the EnecoTech analysis) to 4 in this assessment. A
description of the approach used to calculate the emissions from area sources is provided in this
section.
4.2.1 Ore Pads
The ore pad storage operation has two different sources of emissions namely unloading ore from
trucks to the ore pad and wind emissions. Approximately 300,000 tons of ore is assumed to be
temporarily stockpiled at the mill's ore pads at any given time. Using a bulk ore density of
1.47 tons/yd3 1DUSA, Feb. 6/07), the quantity of ore would create a pile 30 ft. (9.1 m) tall
covering approximately 4 acres (17,000 m2) stockpile area.
With respect to the truck unloading emissions, a process emission factor of 0.04 lbs of ore is
emitted per cubic yard handled (for a truck end and assuming no control (NRC 1987)) and a bulk
ore density of 1.47 tons/yd3 is used in the calculations. U-238 and its decay daughters are all
emitted at a rate of 1.58E-02 Cilyr for each isotope for Colorado Plateau ore. This calculation
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assumes the proposed ore process rate of 730,000 tpy and an ore specific activity of 700 pCi/g.
Similarly, U-238 and its decay daughters are all emitted at a rate of 4.028-02 Cilyr (assuming
secular equilibrium) for Arizona Strip ore. This calculation assumes the proposed ore process
rate of 730,000 tpy and an ore specific activity of 1783 pCilg.
Wind erosion from the ore pad is assumed to have a 50o/o control factor due to the active
watering program in place. This is conservative, in that actual dust control on the ore pads may
be better than this. The annual dust loss from the ore pad is 21.29 gl^'yr; this was calculated
using the method from NRC's Regulatory Guide 3.59 (NRC 1987) on the basis of the
meteorological data (provided by DUSA (DUSA 2007c) presented in Appendix A; the annual
dust loss from the ore pads is 10% that of the tailings piles since the particulates in the ore pads
are coarse material (1 to 6 inch) because the ore has not yet been ground. U-238 and its decay
daughters are all assumed to be emitted at a rate of 3.178-04 Ci/yr for each isotope for Colorado
Plateau ore. This calculation assumes the proposed ore process rate of 300,000 tpy and an ore
specific activity of 700 pCi/g. Similarly, U-238 and its decay daughters are all emitted at a rate
of 8.07E-04 Cilyr (assuming secular equilibrium) for Arizona Strip ore. This calculation
assumes the proposed ore process rate of 300,000 tpy and an ore specific activity of 1783 pCilg.
Therefore, the total emission rate of U-238 and its daughter from truck dumping and wind
erosion is l.6lE-02 Cilyr and 4.108-02 Cilyr for Colorado Plateau ore and Arizona Strip ore,
respectively.
Rn-222 will be produced in the ore pads from the decay of Ra-226. The estimated annual radon
release rate from the ore pads is 375 Ct/yr and 956 Cilyr for Colorado Plateau ore and Arizona
Strip ore, respectively.
4.2.2 Tailings ponds
The current, or anticipated, status of the various tailings ponds at the mill are summarized in
Table 4.1. In brief, Tailings Cell 1 is used as an evaporation pond and will always have a water
cover (tailings solution); hence, no dust or radon emissions are expected from Tailings Cell 1.
Tailings Cell 2 is almost entirely covered with an interim soil cover. Data from the 2005
NESHAP's report indicates an average radon flux of 6.6 pCilr*s from covered areas and an
average radon flux of 55.8 pCi/m2s from remaining exposed beaches
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Tailings Cell Water Cover
(acres)
Interim Soil Cover
(acres)
Beach
(acres)
I 55
2 66.1 0.7
J 35 37 7
4A 36 4
TABLE 4.1
CHARACTERISTICS OF TAILINGS AT WHITE MESA
Wind erosion of tailings from Cell 2 will be limited to the small area remaining to be covered.
Tailings Cell 3 has a mixture of water cover (tailings solution), an interim soil cover and exposed
tailings beach. As for cell l, it is assumed that no tailings dust or radon will be released from the
water covered parts of Cell 3. Wind eroded tailings dust would arise from uncovered tailings
beach. Radon release rates are based on the 2005 NESHAP's report which indicates a radon flux
about 7.1 pCi/m2s from covered areas and24.2pCilm2s from exposed tailings beach.
In the case of Cell 4, for present purposes, it is assumed that the cell is fully developed with
approximately 36 acres of water cover (tailings solution) and 4 acres of exposed tailings.
As mentioned in Section 4.0, large area sources such as the tailings area are divided into smaller
sources (four tailings ponds) to allow for the size and irregular shape ofthese areas. Therefore,
the tailings areas were divided into four area sources in the MILDOS-AREA run. Tailings ponds
I , 2, 3, and 4 represent cell 1 , cell 2, cell 3 and cell 4,A., respectively.
Using the onsite wind data generated over the last 3 years (provided by DUSA (DUSA 2007c)),
the annual dust loss from the tailings ponds is estimated to be approximately 213 g/m2yr; this
was calculated using the method from NRC's Regulatory Guide 3.59 (NRC 1987). It is assumed
that the average uranium recovery rate is 94%o. ln addition, a process emission control factor of
70oh was assumed, based on 1) the active watering (tailings solutions spraying) program on
exposed areas of tailings beaches in active areas; 2) solutions cover other tailings areas; and 3)
crusting agents from the sprayed solutions act to minimize the erosion of the tailings beaches by
wind. With these assumptions and the particulate emission factor, U-238 is emitted at a rate of
2.09E-04 Cilyr and the decay daughters Th-230, Ra-226 and Pb-210 are emiffed at a rate of
3.48E-03 Cilyr from Cell2 and 3 while U-238 is emitted at a rate of 1.09E-04 Cilyr and the
decay daughters Th-230, Ra-226 and Pb-2 l0 are emitted at a rate of 1 .8 I E-03 Cilyr from Cell 44'
for Colorado Plateau ore. These calculations assume the proposed ore process rate of 730,000 tpy
and an ore specific activity of 700 pCilg. Similarly, for Arizona Strip ore, U-238 is emitted at a
rate of 5.328-04 Cilyr and the decay daughters Th-230, Ra-226 and Pb-210 are emitted at a rate
34489 - February 2007 4-7 SENES Consultants Limited
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of 8.87E-03 Cilyr from Cell2 and 3 while U-238 is emitted at a rate of 2.768-04 Cilyr and the
decay daughters Th-230,Ra-226 and Pb-210 are emitted at arate of 4.61E-03 Cilyr from Cell 44'
for Arizona Strip ore. These calculations assume the proposed ore process rate of 730,000 tpy
and an ore specific activity of 1783 pCi/g.
The tailings consist of a mixture of sands and slimes, which are the sources of radon. The
National Emission Standards for Hazardous Air Pollutants (NESHAPS) (Regulation 40 CFR60,
Subpart W) standard limits theRn-222 emission rate to 20 pCi/m2s from uranium mills and their
associated tailings impoundments. [n order to demonstrate compliance with NESHAP's, the mill
carries out a NESHAP's evaluation on an annual basis. As indicated previously, data from the
2005 NESHAP's report (IUC, 2005) was used in this assessment. In this analysis, a total annual
radon releases rate of approximately 130 Ci/yr was estimated for the tailings source.
MnrBoRor,oGrcAL Dara
Meteorological conditions influence re-suspension and dispersion of radionuclides from point
sources and area sources. The mill has an onsite weathering monitoring station that records the
wind speed, wind direction and stability class. This data is used to formulate a joint frequency
distribution which is a required input for MILDOS-AREA. The joint frequency distribution used
in this assessment was provided by DUSA (DUSA 2007c) using the most recent three years
(2004 to 2006) of recorded data.
4.4 PopularroN DATA
The population data was obtained from the year 2000 U.S. census and were used to complete
demographic and population dose projections. Census data is only available in 10 year intervals
and local demographics have experienced little change since the 2000 census.
4.5 URaNruu Mrr,r, Souncp Erratsslox RarBs
4.5.1 Colorado Plateau Ore
The calculated mill radioactive particulate and radon emission rates from point sources and area
sources described in Sections 4.1 and 4.2,respectively for Colorado Plateau ore are provided in
Table 4.2.
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TABLE 4.2
RADIOACTIVE PARTICULATE AND RADON EMISSION RATES
(coLoRADO PLATEAU ORE)
a) No signihcant release during this process.
b) Source is exclusive to the processing ofColorado Plateau ore.
4.5.2 Arizona Strip Ore
The calculated mill radioactive particulate and radon emission rates from point sources and area
sources described in Sections 4.1 and 4.2, rcspectively for Arizona Strip ore are provided in
Table 4.3.
TABLE 4.3
RADIOACTIVE PARTICULATE AND RADON EMISSION RATES
(ARTZONA STRrP ORE)
Process
Grinding Ore Dump
to Grizzly
0re
Pads
North YC
Stack
South YC
Stack
Tailings
Cell2
and 3
Tailings
Cell4A Vanadium
Stackb
Emission
Rate
(Cilyr)
u-238 9.27E-05 9.278-05 t.6tE-02 1.0lE-02 l.0lE-02 2.09E-04 1.09E-04 l.0lE-06
Th-230 9.27E-O5 9.278-05 1.61E-02 2.228-O5 2.22E-05 3.48E-03 l.8lE-03 222E-09
Ra-226 9.278-05 9.27E-05 t.6tE-02 t.3lE-05 t.3l E-05 3.48E-03 t.8l8,03 l.3l E-059
Pb-2 l0 9.27E-05 9.278-05 t.6tE-02 7.888-05 7.88E-05 3.48E-03 l.8lE-03 7.88E-09
Rn-222 9.278+01 Note a 3.758+02 Note a Note a 117.71 12.36 Note a
Notes:
Process
Grinding Ore Dump
to Grizzly Ore Pads North YC
Stack
South YC
Stack
Tailings
Cell 2 and 3
Tailings
Cell4A
Emission
Rate
(Cilyr)
u-238 2.36E-04 2.368-04 4 oE-02 2.588-02 2.58E-02 5.32E-04 2.768-04
Th-230 2.368-04 2.36E-04 4.0E-02 5.67E-05 5.67E-05 8.87E-03 4.61E-03
Ra-226 2.368-04 2.368-04 4 0E-02 3.35E-05 3.35E-05 8.87E-03 4.61E-03
Pb-2 I 0 2.36E-04 2.368-04 4 0E-02 2.01E-04 2.01E-04 8.87E-03 4.61E-03
Rn-222 2.368+02 9.568+02 Note a Note a tt7 .7 |t2.36
Note:
a) No significant release during this process.
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5.0 RECEPTORS
The receptors used in this assessment were provided by DUSA. The receptors used in this
assessment are as follows:
o Nearest Historical Resident (BHV-2);
o Nearest Actual Resident
o Nearest Potential Resident (BHV-I);
o White Mesa Ute Community;
o Blanding, Utah.
ln addition, two grazing locations I and2 are considered as a possible source of meat.
As mentioned in Section 1.3, the receptor locations were determined using a GPS receiver and
were provided by DUSA (DUSA 2007b). The GPS coordinates were used for all the receptors
except for Grazing location I and2 where the easting and northing for Grazing locations I and 2
were taken as nominal "mid-points" in Google Earth for these two receptor locations.
The receptor locations (plotted in Google Earth) with respect to the vanadium stack are shown in
Figure 5.1.
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FIGURE 5.1
RECEPTOR LOCATIONS WITH RESPECT TO THE VANADIUM STACK
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At the time of the 1979 Final Environmental Statement (FES) for the mill, the nearest resident
lived approximately 4.8 miles (4.5) km north-north east of the mill building, near the location of
air monitoring station BHV-2 (also referred to as the historical nearest resident). Currently, the
nearest 'opotential" resident is approximately 1.2 miles (1.9 km) north of the Mill, near the
location of air monitoring station BHV-1. The nearest actual resident is located approximately
1.6 miles (2.5 km) north of the mill. Nearby population groups include the community of White
Mesa, about 8.5 km south east and the city of Blanding, approximately 6 miles (10 km) from the
mill.
The area to the immediate north of the mill (Grazing location l) is believed to be used only for
grazing of meat animals (beef) (NRC 1979). A second location (Grazing location 2) to the east
and south of the mill is also used for the grazing of meat animals (beef) as was assumed in the
EnecoTech analysis (EnecoTech l99la and 1991b). Although considered unlikely, in one worst
case scenario, it is possible that the meat animal grazed at Grazing location I and 2 would be
eaten by the residents near the mill. We have not included a scenario whereby it is assumed that
gtazing at Grazing locations I and 2 supports dairy cattle, because the prospect of supporting
dairy cattle in those locations is not credible, given the arid climate and the much larger feed
requirements of dairy cattle as opposed to beef cattle. We have also been advised by DUSA that
no dairy catlle graze in Grazing locations I and2. It should be noted, however, that in all of the
MILDOS AREA model runs in this report, we did assume, conservatively, that individuals at
each receptor location are assumed to drink all of their milk from cows and eat all of their beef
from cattle that graze at the receptor location (but not at Grazing locations I or 2). This is also
thought to be a very conservative assumption.
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6.0 RADIATION DOSE ESTIMATES
This section describes the MILDOS-AREA results of the mill's potential radiological impacts to
the population in the vicinity of the Mill. This analysis is primarily based on the estimated
annual releases of radioactive materials and assumptions discussed in Sections 4.0 and 5.0. All
potential exposure pathways which are likely to impact individuals near the mill have been
included in the MILDOS-AREA model.
MILDOS-AREA calculates the total annual effective dose commitment (including radon). The
calculated total annual effective dose commitments are compared to the 10 CFR20 (R313-15)
requirements that the dose to individual members of the public shall not exceed 100 mrem/yr
(radon included). In addition, MILDOS-AREA calculates 40 CFRI9O doses (excludes radon).
The 40 CFRI90 Criterion is 25 mrem/yr to the whole body (excluding the dose due to radon) and
25 mrem/yr to any other organ to any member of the public (EPA 2002). The 40CFR 190 doses
are also used to demonstrate compliance with 10 CFR20.ll0l(d) (R313-15-l0l(4)). Under 10
CFR 20.llOl(d) (R313-15-101(4) the licensee must demonstrate that the total effective dose
equivalent to the individual member of the public likely to receive the highest total effective dose
equivalent will not exceed l0 mrem/yr (absent of the radon dose).
In this assessment, a worst case scenario in which there is a possibility that individuals near the
mill ingest meat from cattle grown at Grazing Location I or 2 is considered. It is assumed that
the cattle will graze at Grazing location I or 2 for 2 months of the year (due to the arid nature of
the region and the lack of forage). Therefore, the meat ingestion dose to individuals near the mill
who might consume beef grazed at Grazing Location I or 2 is assumed to be one-sixth of the
MILDOS-AREA calculated meat ingestion dose from these grazing locations.
MILDOS-AREA was run separately for Colorado Plateau ore and Arizona Strip ore. Total
annual dose commitments and 40 CFRI9O annual dose commitments were estimated for
locations in which individual members of the public might reside (BHV-I (nearest potential
resident), BHV-2, Nearest Actual Resident, White Mesa Ute Community and Blanding, Utah)
are provided in Sections 6.1 and 6.2 for Colorado Plateau ore and Arizona Strip ore, respectively.
In addition, total annual dose commitments and 40 CFR190 annual dose commitments from the
meat ingestion pathway that is estimated for Grazing location I and 2 are provided in Sections
6.1and6.2.
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6.1 MILDOS-Anr.q. Rrsulrs Fon Cor,oRADo Pla,roau Onr
The potential annual doses to the people living close to the mill and to the population living
within 50 miles (80 km) as a result of processing Colorado Plateau ore is calculated using
MILDOS-AREA. As mentioned in Section 1.2, the proposed ore process rate for the Colorado
Plateau ore is approximately 730,000 tpy. Assuming that the average uranium recovery is at the
historical recovery yield of 94o/o, the ore processing operations is expected to yield 1715 tons
(3,431,000 lbs) of U:O8 per year.
The MILDOS-AREA-calculated total annual dose commitments (including radon) and 40
CFR190 total annual dose commitment for processing of Colorado Plateau ore are provided in
Sections 6.1.1 and 6.1.2, respectively
6.1.1 R313-15-301(lXa) Regulatory Compliance
The MILDOS-AREA calculated total annual dose commitments (including radon) are provided
in this section. These doses are regulated by R3l3-15-301(l)(a) which requires the dose to an
individual member of the public shall not exceed 100 mrem/yr (radon included).
Table 6.1 presents a summary of the individual dose commitments for the residential receptors
for the age group of infant, child, teenage and adult.
TABLE 6.1
COMPARISON OF ANNUAL DOSE COMMITMENTS TO APPLICABLE RADIATION
PROTECTTON STANDARDS (COLORADO PLATEAU ORE)
Location Age
Grorrn Organ Estimated Dose
(mrem/vr)
Applicable Limit
(mrem/vr)
Fraction
of Limit
Nearest Potential
Resident (BHV-1)
Infant Effective 1.20E+00 100 t.20E-02
Bone 1.86E+00
Avs. Lung 5.01E-01
Bronchi 1.05E+01
child Effective 8.93E-01 100 8.93E-03
Bone 1.31E+00
Avg. Lung 6.68E-01
Bronchi 1.058+0t
Teenage Effective 9.34E-01 100 9.348-03
Bone 4.65E+00
Avs. Luns 5.34E-01
Bronchi 1.05E+01
Adult Effective 8.25E-01 100 8.25E-03
Bone 2.04E+00
Avs. Lung 3.728-01
Bronchi 1.05E+01
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TABLE 6.1 (Cont'd)
COMPARISON OF ANNUAL DOSE COMMITMENTS TO APPLICABLE RADIATION
PROTECTTON STANDARDS (COLORADO PLATEAU ORE)
Location Age
Grorrn Organ Estimated Dose
(mrem/vr)
Applicable Limit
(mrem/vr)
Fraction
of Limit
Nearest Historical
Resident (BHV-2)
Infant Effective 2.548-01 100 2.548-03
Bone 2.898-01
Ave. Luns 9.56E-02
Bronchi 2.698+00
child Effective 2.10E-01 100 2.10E-03
Bone 2.16E-01
Ave. Lune 1.17E-0t
Bronchi 2.69E+00
Teenage Effective 2.t6E-O1 100 2.168-03
Bone 7. 1 8E-0 t
Ave. Lune 9.428-02
Bronchi 2.69E+00
Adult Effective 2.00E-01 100 2.008-03
Bone 3.288-01
Avs. Lune 6.85E-02
Bronchi 2.698+00
Nearest Actual
Resident
lnfant Effective 7.s9E-01 100 7.59E-03
Bone 1.098+00
Avg. Lung 2.958-0t
Bronchi 7.01E+00
child Effective s.77F-01 100 5.778-03
Bone 7.7 tE-ot
Avg. Lung 3.93E-01
Bronchi 7.01E+00
Teenage Effective 6.01E-01 100 6.01E-03
Bone 2.70E+00
Avs. Luns 3. I 6E-0 I
Bronchi 7.01E+00
Adult Effective 5.388-01 r00 5.388-03
Bone l.l9E+00
Avs. Luns 2.21E-01
Bronchi 7.01E+00
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TABLE 6.1 (Cont'd)
COMPARISON OF ANNUAL DOSE COMMITMENTS TO APPLICABLE RADIATION
PROTECTION STANDARDS (COLORADO PLATEAU ORE)
Location Age
Group Organ Estimated Dose
(mrem/vr)
Applicable Limit
(mrem/vr)
Fraction
of Limit
White Mesa
Community
Infant Effective 1.77F-01 r00 t.77E-03
Bone 1.29E-01
Avs. Luns 5.5sE-02
Bronchi 2.16E+00
child Effective 1.56E-01 r00 t.s6E-03
Bone 9.088-02
Avs. Lune 5.2t8-02
Bronchi 2.16E+00
Teenage Effective 1.57E-0 t 100 1.57E-03
Bone 2.48E-01
Ave. Luns 4.t5E-02
Bronchi 2.16E+00
Adult Effective 1.52E-01 100 t.s2E-03
Bone 1.25E-01
Avs. Luns 3.31E-02
Bronchi 2.16E+00
Blanding
Infant Effective 8.37E-02 100 8.37E-04
Bone 8.26E-02
Ave. Lune 2.918-02
Bronchi 9.21E-01
child Effective 7.098-02 100 7.098-04
Bone 6.00E-02
Avs. Lune 3.358-02
Bronchi 9.218-01
Teenase Effective 7.238-02 100 7.23E-04
Bone 1.898-01
Ave. Lune 2.73E-02
Bronchi 9.2tF-01
Adult Effective 6.81E-02 100 6.81E-04
Bone 8.89E-02
Ave. Lung 2.O6E-02
Bronchi 9.21E-01
From Table 6.1, the total annual effective dose commitments are at most 0.0120 (effective dose
for infant at BHV-I) of the R3l3-15-301(lXa) limit of 100 mrem/yr (radon included) to an
individual member of the public. Therefore, the predicted annual effective dose commitments
comply with R3 13-1 5-30 1.
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In the worst case scenario in which there is a possibility that individuals near the mill ingest meat
from cattle grown at Grazing Location I or 2. It is assumed that the cattle will graze at Grazing
location I or 2 for 2 months of the year. The meat ingestion dose to individuals near the mill
who might consume beef grazed at Grazing Location 1 or 2 is assumed to be one-sixth of the
MILDOS-AREA calculated meat ingestion dose from these grazing locations. Table 6.2
presents a summary of the annual dose commitments from the meat ingestion pathway for
Grazing location I and2. Even in the very unlikely event that a resident were to consume meat
from one of the grazing locations, the total dose would remain well below regulatory limits.
TABLE 6.2
TOTAL ANNUAL DOSE COMMITMENTS (mrem) FOR MEAT INGESTION
PATHWAY (COLORADO PLATEAU ORE)
Location Age
Group
Organb
Effectiye'Bone"Avg. Lung'
Gruzins. Location I Infant 0.0081{0 0.00E+00 0.00E+00
child 1.088-02 5.35E-02 4.878-02
Teenaqe 1.68E-02 2.788-01 4.27E-02
Adult 1.228-02 l.slE-01 3.52E-02
Grazins. Location 2 Infant 0.00E+00 0.00E+00 0.00E+00
chitd 5.828-04 2.88E-03 2.38E-03
Teenase 8.9sE-04 t.52E-02 2.08E-03
Adult 6.358-04 7.93E-03 1.728-03
Note:
a) Assumes cattle will graze at the particular Grazing location for 2 months of the year.
b) Exclusive ofradon.
6.1.2 40 CFR190 Regulatory Compliance
MILDOS-AREA calculated 40 CFR190 doses (excludes radon). These doses are regulated by
the 40 CFR190 criterion, which is 25 millirem (mrem) to the whole body (excluding the dose
due to radon) (EPA 2002) or to any organ of the body. The 40CFR 190 doses are also used to
demonstrate compliance with R3l3-15-l0l(4) (10 CFR20.1101(d). The licensee must
demonstrate that total effective dose equivalent to the individual member of the public likely to
receive the highest total effective dose equivalent will not exceed l0 mrem/yr (absent of the
radon dose).
Table 6.3 presents a summary of the 40 CFR190 individual dose commitments for the residential
receptors for the age group of infant, child, teenage and adult.
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TABLE 6.3
COMPARISON OF 40 CFR19O ANNUAL DOSE COMMITMENTS WITH
APPLICABLE RADIATION PROTECTION STANDARDS
(coLoRADO PLATEAU ORE)
Location Age
Groun Organ Estimated Dose
(mrem/vr)
Applicable Limit
(mrem/vr)
Fraction of
Limit
Nearest Potential
Resident (BHV-l)
Infant Effective 5.358-01 25 2.t48-02
Bone L82E+00 25 7.298-02
Avs. Luns 4.63E-01 25 1.85E-02
Bronchi 9.55E-04 not limited
child Effective 2.238-01 25 8.94E-03
Bone t.278+00 25 5. I 0E-02
Avs. Lune 6.308-01 25 2.s2F-02
Bronchi 9.55E-04 not limited
Teenage Effective 2.65E-01 25 1.068-02
Bone 4.628+00 25 1.85E-01
Avs. Luns 4.96E-01 25 1.98E-02
Bronchi 9.558-04 not limited
Adult Effective 1.568-01 25 6.248-03
Bone 2.00E+00 25 7.99E-02
Ave. Luns 3.33E-01 25 1.33E-02
Bronchi 9.55E-04 not limited
Nearest Historical
Resident (BHV-2)
Infant Effective 7.84E-02 25 3.14E-03
Bone 2.72E-01 25 1.09E-02
Avs. Lune 8.018-02 25 3.21E-03
Bronchi 1.358-04 not limited
child Effective 3.42E-02 25 1.37E-03
Bone 1.988-01 25 7.918-03
Avs. Luns 1.00E-01 25 4.018-03
Bronchi 1.35E-04 not limited
Teenage Effective 4.03E-02 25 l.6l E-03
Bone 6.92E-0t 25 2.77E-02
Avs. Luns 7.768-02 25 3. l0E-03
Bronchi 1.358-04 not limited
Adult Effective 2.408-02 25 9.618-04
Bone 3.07E-01 25 t.23E-02
Avp. Lune 5.258-02 25 2.10E-03
Bronchi 1.358-04 not limited
6-634489 - February 2007 SENES Consultants Limited
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TABLE 6.3 (Cont'd)
COMPARISON OF 40 CFR19O ANNUAL DOSE COMMITMENTS WITH
APPLICABLE RADIATION PROTECTION STANDARDS
(coLoRADO PLATEAU ORE)
Location Age
Grouo Organ Estimated Dose
(mrem/vr)
Applicable Limit
(mrem/vr)
Fraction of
Limit
Infant Effective 3. I I E-01 25 1.258-02
Bone 1.06E+00 25 4.258-02
Ave. Luns 2.678-0r 25 1.078-02
Bronchi 5.50E-04 not limited
child Effective 1.30E-01 25 5.188-03
Bone 7.40E-01 25 2.968-02
Avs. Luns 3.63E-01 25 1.458-02
Bronchi 5.508-04 not limited
Teenape Effective 1.53E-01 25 6. l4E-03
Bone 2.66E+00 25 t.07E-01
Avs. Luns 2.868-01 25 t.t4E-02
Bronchi 5.508-04 not limited
Adult Effective 9.018-02 25 3.60E-03
Bone 1.16E+00 25 4.648-02
Avs. Lung 1.93E-01 25 7.70F-03
Bronchi 5.50E-04 not limited
Infant Effective 3. I 8E-02 25 t.278-03
Bone l.l lE-01 25 4.438-03
Avs. Luns 4.048-02 25 1.628-03
Bronchi 4.06E-05 not limited
child Effective I . l8E-02 25 4.738-04
Bone 7.018-02 25 2.808-03
Ave. Luns 3.398-02 25 r.35E-03
Bronchi 4.068-0s not limited
Teenage Effective t.24E-02 25 4.95E-04
Bone 2. I 0E-0 t 25 8.388-03
Ave. Lune 2.398-02 25 9.568-04
Bronchi 4.06E-0s not limited
Adult Effective 7.758-03 25 3.10E-04
Bone 9.888-02 25 3.958-03
Avs. Luns 1.68E-02 25 6.718-04
Bronchi 4.068-05 not limited
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TABLE 6.3 (Cont'd)
COMPARISON OF 40 CFRl9O ANNUAL DOSE COMMITMENTS WITH
APPLICABLE RADIATION PROTECTION STANDARDS
(coLoRADO PLATEAU ORE)
Location Age
Gronn Organ Estimated Dose
(mrem/vr'l
Applicable Limit
(mrem/vr)
Fraction of
Limit
Blanding
Infant Effective 2.138-02 25 8.51E-04
Bone 7.34E-02 25 2.948-03
Avg. Luns 2.188-02 25 8.738-04
Bronchi 3.36E-05 not limited
child Effective 8.58E-03 25 3.438-04
Bone 4.978-02 25 1.998-03
Avs. Lung 2.448-02 25 9.788-04
Bronchi 3.368-05 not limited
Teenage Effective 9.778-03 25 3.91E-04
Bone 1.698-01 25 6.75E-03
Avg. Luns 1.86E-02 25 7.43E-04
Bronchi 3.36E-05 not limited
Adult Effective 5.87E-03 25 2.358-04
Bone 7.51E-02 25 3.00E-03
Avs. Luns 1.26E-02 25 5.06E-04
Bronchi 3.36E-05 not limited
From Table 6.3, the 40 CFR190 annual dose commitments are at most 0.185 (dose to the bone
for the teen at BHV-I) of the 40 CFRI9O dose criterion of 25 mremlyr. In addition, the
40CFRI9O annual effective dose commitments demonstrate compliance with the R313-15-
101(4) (10 CFR20.1101(d) limit of 10 mrem/yr to the individual member of the public likely to
receive the highest total effective dose equivalent. The maximum total effective dose equivalent
was 0.535 mrem/yr (infant at BHV-l), or 0.0214 of the 10 mrem/yr limit.
In the worst case scenario in which there is a possibility that individuals near the mill ingest meat
from caffle grown at Grazing Locations I or 2, it is assumed that the cattle will graze at Grazing
location I or 2 for 2 months of the year. The meat ingestion dose to individuals near the mill
who might consume beef grazed at Grazing Location I or 2 is assumed to be one-sixth of the
MILDOS-AREA calculated meat ingestion dose from these grazing locations. Table 6.4
presents a summary of the 40 CFRI9O annual dose commitments from the meat ingestion
pathway for Grazing Locations I and,2. As before, in the unlikely event a receptor were to eat
meat from cattle grazing in areas I or 2, the total dose would remain well below regulatory
limits.
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TABLE 6.4
40 CFR190 ANNUAL DOSE COMMITMENTS (mrem) FOR MEAT INGESTION
PATHWAY (COLORADO PLATEAU ORE)
Location Age Group Organo
Effective"Bone"Avs. Luns"
Grazing Location I
Infant 0.008+00 0.008+00 0.008+00
child 1.08E-02 5.358-02 4.87E-O2
Teenase 1.68E-02 2.78E-01 4.278-02
Adult 1.22E-02 L5IE-01 3.52E-02
Grazing Location 2
Infant 0.008+00 0.00E+00 0.00E+00
child 5.80E-04 2.878-03 2.378-03
Teenase 8.92E-04 t.s2E-02 2.078-03
Adult 6.33E-04 7.908-03 1.728-03
Note:
a) Assumes cattle will graze at the particular Grazing location for 2 months of the year.
b) Exclusive ofradon.
The annual doses to the population estimated within 50 miles (80 km) of the site are provided in
Table 6.5.
TABLE 6.5
ANNUAL POPULATION DOSE COMMITMENTS WITHIN 50 MILES (80 km) OF THE
MILL FOR COLORADO PLATEAU ORE
Organ
ANNUAL POPULATION DOSE COMMITMENTS,
PERSON-REM PER YEAR
Mill Ooerations
Effective
Bone
Avg. Lung
Bronchi
l.l5E-01
9.18E-01
1.22F-01
6.28E+00
The population dose arising from the processing of Colorado Plateau ore is estimated at
0.15 person-rem. This can be compared to the dose from natural background sources of
In the United States, nominal average levels of natural background radiation are as follows
(National Council on Radiation Protection and Measurements (NCRP), 1987):
Cosmic and Cosmogenic
Terrestrial
Inhaled (Radon)
Ingested
Total (Average)
28 mrem/yr
28 mrem/yr
200 mrem/yr
40 mrem /yr
296 mremlyr (96 mrem/yr excluding radon)
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In the area of the White Mesa Mill, natural background radiation was measured at two sites in
1977: the project site (Blanding) and the Hanksville site. At the Blanding site, the average dose
equivalent from external radiation was about 142 mrem/yr. Of this 142 mrem/yr, 68 mrem/yr
came from cosmic radiation, while T4mremlyr came from terrestrial radiation. (Dames &
Moore, 1978). At the Hanksville site, the corresponding average dose equivalent was about
122 mrem/yr (68 mrem/yr from cosmic radiation and 54 mrem/yr from terrestrial radiation).
(Dames & Moore, 1978).
lngested radionuclides would contribute (about) a further 18 mrem/yr (NRC, 1979). This brings
the total background dose from external radiation and ingested radioactivity, but exclusive of the
dose from radon-222, to about 161 mrem/yr; which is higher than both the US averages of 96
mrem/yr.
If the nominal U.S. dose from radon of about 200 mrem per year is added, then the total dose
from natural background in the area of the mill is 360 mrem/y (or more assuming the dose from
radon would increase along with that from terrestrial source).
The current population of San Juan county is about 14,400 people. Assuming everyone living in
San Juan county receives an annual dose of (about) 360 mrem/y, then the total dose due to
natural background is approximately 5184 person-rem. The theoretical incremental dose of
0.15 person-rem is clearly inconsequential by comparison.
6.2 MILDOS-ARna Rpsulrs FoRARTzoNA SrRrp ORE
The potential annual doses to the people living close to the mill and to the population living
within 50 miles (80 km) as a result of processing of Arizona Strip ore is calculated using
MILDOS-AREA. As mentioned in Section 1.2, the proposed ore process rate for Arizona Strip
ore is approximately 730,000 tpy. Assuming that the average uranium recovery is at the
historical recovery yield of 94Yo, the ore processing operations is expected to yield 4,371 tons
(8,742,188lbs) of yellowcake per year.
The MILDOS-AREA calculated total annual dose commitments (including radon) and 40
CFR190 annual dose commitments for processing of Arizona Strip ore are provided in
Sections 6.2.1 and 6.2.2, respectively.
34489 - February 2007 6-10 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
White Mesa Uranium Mill
6.2.1 Ri13-15-301 (lXa) Regulatory Compliance
The MILDOS-AREA calculated total annual dose commitments (including radon) are provided
in this section. These doses are regulated by R3l3-15-301(1Xa) which requires the dose to an
individual member of the public shall not exceed 100 mrem/yr (radon included).
Table 6.6 presents a summary of the individual dose commitments for the residential receptors
for the age group of infant, child, teenage and adult.
TABLE 6.6
COMPARISON OF ANNUAL DOSE COMMITMENTS WITH APPLICABLE
RADIATION PROTECTION STANDARDS (ARIZONA STRIP ORE)
Location Age
Groun Organ Estimated Dose
(mrem/vr)
Applicable Limit
(mrem/vr)
Fraction
of Limit
Nearest Potential
Resident (BHV-l)
lnfant Effective 2.94E+00 100 2.94E-02
Bone 4.748+00
Avg.
I-uns 1.27E+00
Bronchi 2.49E+01
chitd Effective 2. l5E+00 100 2.t5E-02
Bone 3.35E+00
Avg.
Luns 1.698+00
Bronchi 2.498+01
Teenase Effective 2.25E$0 100 2.258-02
Bone l.l8E+01
Avg.
Lung 1.35E+00
Bronchi 2.498+01
Adult Effective 1.97E+00 100 1.97E-02
Bone 5. I 9E+00
Avg.
Lune 9.408-01
Bronchi 2.49E+01
34489 - February 2007 6-1 1 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
White Mesa Uranium Mill
TABLE 6.6 (Cont'd)
COMPARISON OF ANNUAL DOSE COMMITMENTS WITH APPLICABLE
RADIATION PROTECTION STANDARDS (ARIZONA STRIP ORE)
Location Age
Groun Organ Estimated Dose
(mrem/vr)
Applicable Limit
(mrem/vr)
Fraction
of Limit
Nearest Historical
Resident (BHV-2)
Infant Effective 6.008-01 100 6.00E-03
Bone 7.35E-01
Avg.
Luns 2.40E-01
Bronchi 6.098+00
child Effective 4.87E-01 100 4.87E-03
Bone 5.458-01
Avg.
Luns 2.948-Ot
Bronchi 6.098+00
Teenase Effective s.038-01 100 5.03E-03
Bone 1.82E+00
Avg.
Lung 2.36E-01
Bronchi 6.09E+00
Adult Effective 4.60E-01 100 4.60E-03
Bone 8.29E-0t
Avg.
Lung 1.70E-01
Bronchi 6.09E+00
Nearest Actual
Resident
Infant Effective 1.838+00 r00 L838-02
Bone 2.788+00
Avg.
[-uns 7.478-01
Bronchi 1.63E+01
chitd Effective 1.37E+00 t00 1378-02
Bone 1.96E+00
Avg.
Luns 9.968-01
Bronchi 1.63E+01
Teenase Effective 1.43E+00 100 t.43E-02
Bone 6.888+00
Avg.
Lunp 7.99E-01
Bronchi 1.638+01
Adult Effective 1.278+00 100 1.278-02
Bone 3.03E+00
Avg.
Lrrns 5.598-01
Bronchi 1.638+01
34489 - February 2007 6-12 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
White Mesa Uranium Mill
TABLE 6.6 (Cont'd)
COMPARISON OF ANNUAL DOSE COMMITMENTS WITH APPLICABLE
RADIATION PROTECTION STANDARDS (ARIZONA STRIP ORE)
Location Age
Grouo Organ Estimated Dose
(mrem/vr)
Applicable Limit
(mrem/vr)
Fraction
of Limit
White Mesa
Community
lnfant Effective 3.96E-0r 100 3.96E-03
Bone 3.238-01
Avg.
Luns 1.36E-01
Bronchi 4.728+00
child Effective 3.458-0t 100 3.45E-03
Bone 2.248-01
Avg.
Lung t.268-01
Bronchi 4.728+00
Teenase Effective 3.47E-01 r00 3.47E-03
Bone 6.188-01
Avg.
Lung 9.94E-02
Bronchi 4.728+00
Adult Effective 3.34E-01 t00 3.348-03
Bone 3.10E-01
Avg.
Luns 7.868-02
Bronchi 4.72E+00
Blanding
Infant Effective 1.94E-01 100 1.94E-03
Bone 2.08E-01
Avg.
Lung 7.20E-02
Bronchi 2.06E+00
child Effective t.628-01 100 t.628-03
Bone 1.50E-01
Avg.
Luns 8.278-02
Bronchi 2.06E+00
Teenage Effective 1.65E-01 100 1.65E-03
Bone 4.74F-01
Avg.
[.uns 6.68E-02
Bronchi 2.06E+00
Adult Effective 1.548-01 100 1.548-03
Bone 2.22F,01
Avg.
Luns 5.028-02
Bronchi 2.06E+00
34489 - February 2007 6-t3 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
White Mesa Uranium Mill
From Table 6.6, the total annual effective dose commitments are at most 0.0294 (effective dose
for infant at BHV-I) of the R313-15-301(1)(a) of 100 mrem/yr (radon included) to an individual
member of the public. Therefore, the predicted annual effective dose commitments comply with
R3 l3-l s-101(l)(a).
In the worst case scenario in which there is a possibility that individuals near the mill ingest meat
from cattle grown at Grazing Location I or 2. It is assumed that the cattle will graze at Grazing
location I or 2 for 2 months of the year. The meat ingestion dose to individuals near the mill
who might consume beef grazed at Grazing Location I or 2 is assumed to be one-sixth of the
MILDOS-AREA calculated meat ingestion dose from these grazing locations. Table 6.7
presents a summary of the annual dose commitments from the meat ingestion pathway for
Grazing location I and2. As before, even in the unlikely event that a receptor consumed beef
from one of the grazing locations, the total dose would remain well below regulatory limits.
TABLE 6.7
TOTAL ANNUAL DOSE COMMITMENTS FOR MEAT INGESTION PATHWAY
(ARTZONA STRrP ORE)
Location Age Group organb
Effective"Bone"Avs. Lunsu
Grazing Location 1
lnfant 0.008+00 0.008+00 0.008+00
child 2.738-02 1.37E-01 t.248-01
Teenage 4.28E-02 7.10E-01 L09E-01
Adult 3. I 0E-02 3.83E-01 8.97E-02
Infant 0.00E+00 0.00E+00 0.00E+00
child 1.48E-03 7.35E-03 6.05E-03.rts Teenase 2.28E-03 3.88E-02 5.30E-03
Adult t.62E-03 2.028-02 4.388-03
Note:
a) Assumes cattle will graze at the particular Grazing location for 2 months of the year.
b) Exclusive ofradon
6.2.2 40 CFR190 Regulatory Compliance
MILDOS-AREA calculated 40 CFR190 doses (excludes radon). These doses are regulated by
40 CFR190 Criterion is 25 millirem (mrem) to the whole body (excluding the dose due to radon)
(EPA 2002). The 40CFR 190 doses are also used to demonstrate compliance with
R313-15-101(4) (10 CFR20.ll01(d)). The licensee must demonstrate that total effective dose
equivalent to the individual member of the public likely to receive the highest total effective dose
equivalent will not exceed 10 mrem/yr (absent of the radon dose).
34489 - February 2007 6-t4 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
Wite Mesa Uranium Mill
Table 6.8 presents a summary of the 40 CFRI9O individual dose commitments for residential
receptors for the age group of infant, child, teenage and adult.
TABLE 6.8
COMPARISON OF 40 CFR19O ANNUAL DOSE COMMITMENTS WITH
APPLICABLE RADIATION PROTECTION STANDARDS (ARIZONA STRIP ORE)
Location Age
Group Organ Estimated Dose
(mrern/vr)
Applicable Limit
(mrem/yr)
Fraction
of Limit
Nearest Potential
Resident (BHV-l)
lnfant Effective 1.378+00 25 5.478-02
Bone 4.65E+00 25 1.86E-01
Avg.
Luns l. l8E+00 25 4.72E-02
Bronchi 2.438-03 not limited
child Effective 5.70E-0r 25 2,288-02
Bone 3.248+00 25 L298-01
Avg.
Lune 1.60E+00 25 6.418-02
Bronchi 2.43F.03 not limited
Teenase Effective 6.75E-01 25 2.708-02
Bone 1.1 7E+0 I 25 4.708-01
Avg.
Luns 1.26E+00 25 5.058-02
Bronchi 2.438-03 not limited
Adult Effective 3.968-01 25 1.588-02
Bone 5.108+00 25 2.048-01
Avg.
Luns 8.488-01 25 3.398-02
Bronchi 2.43E-03 not limited
Nearest Historical
Resident (BHV-2)
Infant Effective 2.008-01 25 8.008-03
Bone 6.968-01 25 2.798-02
Avg.
Luns 2.04E-0r 25 8.188-03
Bronchi 3.458-04 not limited
child Effective 8.728-02 25 3.498-03
Bone 5.03E-01 25 2.018-02
Avg.
Luns 2.558-01 25 1.02E-02
Bronchi 3.458-04 not limited
Teenase Effective 1.03E-01 25 4.108-03
Bone 1.768+00 25 7.03F-02
Avg.
Lunp 1.988-01 25 7.9r8-03
Bronchi 3.45E-04 not limited
Adult Effective 6.1 lE-02 25 2.4s8-03
Bone 7.838-01 25 3.13E-02
Avg.
Luns 1.34E-01 25 5.358-03
Bronchi 3.45E-04 not limited
34489 - February 2007 6-1s SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
White Mesa Uranium Mill
TABLE 6.8 (Cont'd)
COMPARISON OF 40 CFR19O ANNUAL DOSE COMMITMENTS WITH
APPLICABLE RADIATION PROTECTION STANDARDS (ARIZONA STRIP ORE)
Location Age
Group Organ Estimated Dose
(mrem/vr)
Applicable Limit
(mrem./vr)
Fraction
of Limit
Nearest Actual
Resident
lnfant Effective 7.938-01 25 3.178-02
Bone 2.71F.+00 25 1.09E-01
Avg.
Luns 6.77E-01 25 2.718-02
Bronchi 1.40E-03 not limited
child Effective 3.30E-0t 25 t.32E-02
Bone 1.898+00 25 7.548-02
Avg.
Lune 9.25E-01 25 3.70E-02
Bronchi 1.40E-03 not limited
Teenase Effective 3.91E-01 25 t56E-02
Bone 6.80E+00 25 2.728-01
Avg.
Lung 7.288-0t 25 2.9t8-02
Bronchi 1.40E-03 not limited
Adult Effective 2.298-01 25 9. I 7E-03
Bone 2.968+00 25 I . I 8E-01
Avg.
Luns 4.908-01 25 1.96E-02
Bronchi 1.40E-03 not limited
White Mesa
Community
Infant Effective 8.128-02 25 3.25E-03
Bone 2.828-01 25 Lt3E-02
Avg.
Lung t.03E-01 25 4.12E-03
Bronchi 1.038-04 not limited
child Effective 3.01E-02 25 1.208-03
Bone 1.79E-01 25 7.15E-03
Avg.
Luns 8.628-02 25 3.458-03
Bronchi 1.038-04 not limited
Teenage Effective 3.16E-02 25 1.268-03
Bone 5.358-01 25 2.148-02
Avg.
[,uns 6.088-02 25 2.43E-03
Bronchi 1.03E-04 not limited
Adult Effective r.97E-02 25 7.908-04
Bone 2.53E-01 25 l.0lE-02
Avg.
Luns 4.278-02 25 L7lE-03
Bronchi 1.03E-04 not limited
34489 - February 2007 6-16 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
Wite Mesa Uranium Mill
TABLE 6.8 (Cont'd)
COMPARISON OF 40 CFR19O AI\NUAL DOSE COMMITMENTS WITH
APPLICABLE RADIATION PROTECTION STANDARDS (ARIZONA STRIP ORE)
Location Age
Groun Organ Estimated Dose
(mrem/vr)
Applicable Limit
(mremiyr)
Fraction
of Limit
Blanding
Infant Effective 5.44E-02 25 2.1 8E-03
Bone 1.87E-01 25 7.48E-03
Avg.
Luns 5.s7E-02 25 2.238-03
Bronchi 8.578-05 not Iimited
child Effective 2.198-02 25 8.768-04
Bone 1.278-01 25 5.06E-03
Avg.
Luns 6.24E-02 25 2.498-03
Bronchi 8.57E-05 not limited
Teenase Effective 2.49E-02 25 9.958-04
Bone 4.30E-01 25 t.72E-02
Avg.
Luns 4.728-02 25 1.89E-03
Bronchi 8.578-05 not limited
Adult Effective 1.49E-02 25 s.988-04
Bone 1.92E-01 25 7.668-03
Avg.
Luns 3.22E-02 25 1.29E-03
Bronchi 8.578-05 not limited
From Table 6.8, the 40 CFRI90 annual dose commitments are at most 0.47 (dose to the bone for
the teen at BHV-l) of the 40 CFRI9O dose criterion of 25 mrem/yr. In addition, the 40 CFRI9O
annual effective dose commitments demonstrate compliance with R3l3-15-101(4) (10
CFR20.1l0l(d)) limit of 10 mrem/yr to the individual member of the public likely to receive the
highest total effective dose equivalent.
In the worst case scenario in which there is a possibility that individuals near the mill ingest meat
from cattle grown at Grazing Location I or 2. It is assumed that the cattle will graze at Grazing
location I or 2 for 2 months of the year. The meat ingestion dose to individuals near the mill
who might consume beef grazed at Grazing Location I or 2 is assumed to be one-sixth of the
MILDOS-AREA calculated meat ingestion dose from these grazing locations. Table 6.9
presents a summary of the 40 CFRI9O annual dose commitments from the meat ingestion
pathway for Grazing location I and 2. Again, even in the unlikely event that someone were to
consume beef from grazing area I or 2, the total dose would be small and well below regulatory
limits.
34489 - Februarv 2007 6-t7 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
Wite Mesa Uranium Mill
TABLE 6.9
40 CFR190 ANNUAL DOSE COMMITMENTS (mrem) FOR MEAT INGESTION
PATHWAY (ARTZONA STRrP ORE)
Location Age Group Organ
Effective"Bone"Avs. Luns"
Grazinglocation I
Infant 0.00E+00 0.00E+00 0.00E+00
child 2.73E-02 1.378-01 t.24E-01
Teenage 4.28E-02 7.10E-01 1.09E-0r
Adult 3. l0E-02 3.83E-01 8.978-02
Grazing Location 2
Infanl 0.00E+00 0.00E+00 0.00E+00
child 1.488-03 7.32E-03 6.03E-03
Teenase 2.278-03 3.878-02 5.288-03
Adult t.6lE-03 2.O2F-02 4.358-03
Note:
a) Assumes cattle will graze at the particular Grazing location for 2 months of the year.
b) Exclusive ofradon.
The annual doses to the population estimated within 50 miles (80 km) of the site are provided in
Table 6.10.
TABLE 6.10
ANNUAL POPULATION DOSE COMMITMENTS WITHIN 50 MILES (80 km) OF THE
MILL FOR ARIZONA STRIP ORE
Organ
ANNUAL POPULATION DOSE COMMITMENTS,
PERSON.REM PER YEAR
Mill Ooerations
Effective
Bone
Avg. Lung
Bronchi
2.7tE-01
2.21E+00
2.88E-01
1.418+01
The population dose arising from the processing of Colorado Plateau ore is estimated at
0.345 person-rem. This can be compared to the dose from natural background sources of
radiation in the Colorado Plateau of about 360 mrem/yr as previously discussed.
In the United States, nominal average levels of natural background radiation are as follows
(National Council on Radiation Protection and Measurements (NCRP), 1987):
The current population of San Juan county is about 14,400 people. Assuming everyone living in
San Juan county receives an annual dose of (about) 360 mrem/y, then the total dose due to
natural background is approximately 5184 person-rem. The theoretical incremental dose of
0.345 person-rem is clearly inconsequential by comparison.
34489 - February 2007 6-l 8 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
Wite Mesa Uranium Mill
7.0 KEY OBSERVATIONS
As mentioned in Section 1.0, milling of conventional ore is scheduled for early 2008 when the
milling of currently available altemate feed materials completed (DUSA 2007). This dose
assessment was prepared in support of the license renewal application for the White Mesa
Uranium mill.
The goal was to determine the potential doses to populations in the vanity of the mill.
In this assessment, MILDOS-AREA was used to estimate the dose commitments received by
individuals and the general population within a 50 mile (80 km) radius for the processing of
Colorado Plateau ore or Arizona Strip ore. The expected ore grade from the Colorado Plateau
ore is an average of 0.25o/o U:Os and l.5o/o YzOs NRC 1980) while the Arizona Strip ore is
assumed to contain 0.637% U3O8 (DUSA 2007a). The proposed ore process rate for the
Colorado Plateau ore and Arizona Strip ore is approximately 730,000 tons per year (tpy)
(2000 tons per day). Assuming that the average uranium recovery is at the historical recovery
yield of 94o/o, approximately 1,715 tons (3,431,000 lbs) of U3Os per year would be recovered
from Colorado Plateau ore at the proposed ore process rate. Similarly, approximately 4,371 tons
(8,742,188 lbs) of UlOs per year would be recovered from Aizona Strip ore at the proposed ore
process rate. The proposed operating schedule at the mill is assumed to be 24 hr/day for
365 days per year.
The MILDOS-AREA calculated total annual effective dose commitments (including radon) were
compared to the R3l3-15-301(1)(a) (10 CFR20) requirements that the dose to individual
members of the public shall not exceed 100 mrem/yr (radon included). Overall, the total annual
effective dose commitments are at most 0.0120 (effective dose for infant at BHV-I) of the
R313-15-301(lXa) (10 CFR20) limit of 100 mrem/yr (radon included) to an individual member
of the public for the processing of Colorado Plateau ore. The total annual effective dose
commitments are at most 0.0294 (effective dose for infant at BHV-1) of the R313-15-301(l)(a)
(10 CFR20) limit of 100 mrem/yr (radon included) to an individual member of the public for the
processing of Arizona Strip ore. Therefore, the predicted annual effective dose commitments for
anticipated ore processing operations comply with R313-15-301(1)(a) (10 CFR20).
ln addition, the MILDOS-AREA-calculated 40 CFRI9O annual dose commitment (excluding
radon) were compared to the 40 CFR190 Criterion, which is 25 mremlyr to the whole body
(excluding the dose due to radon) and 25 mrem/yr to any other organ to any member of the
public (EPA 2002). The 40CFR 190 doses were also used to demonstrate compliance with
R313-15-101(4) (10 CFR20.1l0l(d)) (i.e., the licensee must demonstrate that total effective dose
equivalent to the individual member of the public likely to receive the highest total effective dose
34489 - February 2007 7-l SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
Wite Mesa Uranium Mill
equivalent will not exceed l0 mrem/yr (absent of the radon dose). Overall, from Table 6.3, the
40 CFRI9O annual dose commitments are at most 0.185 (dose to the bone for the teen at BHV-I)
of the 40 CFRI9O dose criterion of 25 mremlyr for Colorado Plateau ore. tn addition, the 40
CFRI90 annual effective dose commitments demonstrate compliance with the
R3l3-15-101(4) (10 CFR20.l10l(d) limit of l0 mrem/yr to the individual member of the public
likely to receive the highest total effective dose equivalent. From Table 6.8, the 40 CFRI9O
annual dose commitments are at most 0.47 (dose to the bone for the teen at BHV-I) of the
40 CFR190 dose criterion of 25 mrem/yr. In addition, the 40 CFRI9O annual effective dose
commitments demonstrate compliance with R313-15-101(4) (10 CFR20.1101(d)) limit of
l0 mrem/yr to the individual member of the public likely to receive the highest total effective
dose equivalent. Therefore, the predicted 40 CFR annual effective dose commitments for
anticipated ore processing operations comply with R313 -15 (10 CFR20).
34489 - February 2007 7-2 SENES Consultants Limited
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White Mesa Uranium Mill
8.0 REFERENCES
Argonne National Laboratory (ANL) 1998a. MILDOS-AREA, Version 2.208, Developed at the
Environmental Assessment Division
Argonne National Laboratory (ANL) 1998b.
Environmental Assessment Division
MILDOS-AREA User's Guide (Draft),
Code of Federal Regulations (CFR) Title 10 Part 20 Standards for Protection Against Radiation.
May.
Dames & Moore 1978. Environmental Report: Wite Mesa Uranium Project San Juan County,
Utahfor Energy Fuels Nuclear, Inc. Jantary.
Denison Mines (USA) Corp. (DUSA) 2007. Press Release: Denison Announces Operations
Update. January 30.
EnecoTech Environmental Consultants 1991a. MILDOS Modeling Results (Letter), Prepared for
Umetco Minerals. October 31.
EnecoTech Environmental Consultants 199lb. MILDOS Modeling Coruection (Letter), Prepared
for Umetco Minerals. November 27.
Environmental Protection Agency (EPA) 1989, Code of Federal (CFR) Regulations Title 40 Part
National Emission Standards for Hazardous Air Pollutants (NESHAPS), Subpart W.
December.
Environmental Protection Agency (EPA) 2002. Code of Federal (CFR) Regulations Title 40 Part
190 Environmental Radiation Protectionfor Nuclear Power Operations. February.
Google 2005. Google Earth Pro 3.0.0762, November.
International Commission on Radiological Protection (ICRP). 1959. Report of ICRP Committee
II on Permissible Dosefor Internal Radiation, Health Physics 3:l-380, 1960.
International Commission on Radiological Protection (ICRP). 1966. Deposition and retention
models for internal dosimetry of the human respiratory tract. Health Physics 12; 173-
207.
34489 - February 2007 8-1 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
White Meso Uranium Mill
International Commission on Radiological Protection (ICRP). 1971. Recommendations of the
International Commission on Radiological Protectioz. ICRP Publication l0A. Pergamon
Press, New York.
International Commission on Radiological Protection (ICRP). 1972. The Metabolism of
Compounds of Plutonium and Other Actinides. ICRP Publication 19, Pergamon Press.
International Commission on Radiological Protection (ICRP) 1979. Limits for Intakes of
Radionuclides by Workers (adoptedfrom July 1978). ICRP Publication 30.
ruC 2005. NESHAP's Evaluation of White Mesa Mill.
Landau, S. (DUSA) 2007a. Email: RE: 34489- Preliminary Mildos Results and Emissions
Calculations. Received Feb. 13/07.
Nuclear Regulatory Commission (NRC) 1987. Report No. 94. Exposure of Population in the
United States and Canadafrom Natural Background Radiation
Nuclear Regulatory Commission (NRC) 1979. Final Environmental Statement Related to the
Energlt Fuels Nuclear, ftc, NUREG-0556. Docket No. 40-8681. May.
Nuclear Regulatory Commission (NRC) 1980. Final Generic Environmental Impact Statement
on Uranium Milling Project M-25, NUREG-0706 Vol. 3. September.
Nuclear Regulatory Commission (NRC) 1987. Methods for Estimating Radioactive and Toxic
Airborne Source Terms for Uranium Milling Operations, March.
Strenge, D.L. and Bander, T.J. 1981. MILDOS- A Computer Program for Calculating
Environmental Radiation Doses from Uranium Recovery Operations, NUREG/ CR-
201 l. Prepared for US Nuclear Regulatory Commission.
Turk, D. (DUSA) 2007b. Email: RE: Receptor GPS. Received February 14-15.
Turk, D. (DUSA) 2007c. Email: FW: Additional Weather Information. Received Feb 7.
Yu, C. 1992. Calculation of Radiation Dose from Uranium Recovery Operations for Large
Area- Sources, Argonne National Laboratory.
34489 - February 2007 8-2 SENES Consultants Limited
Dose A,ssessment in Support af the License Renewal Application & Emtironmental Reportfor
White Mesa Uranium Mill
APPENDIX A
EMIS$ONS CALCULATIONS
3,{489 -February 2007 SENES eonsultants Limitd
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
Wite Mesa Uronium Mill
A.O EMISSIONSCALCULATIONS
Supplemental Information which describes the model and assumptions used to calculate the
sonrce emissions for the sources described in Section 4.0 are provided below.
A.1 Calculation of Annual Dust Loss
The calculation of the annual dust loss from the ore pads and the tailings ponds was required to
calculate an emission factor. This dusting rate for the tailings impoundments is calculated
according to the emission factor (E*) equation from NRC's Regulatory Guide 3.59 (NRC 1987).
The equation of for the dusting rate is calculated as follows:
3.156x10?*0.5s
where,
E*: annual dust loss per unit area in d^?rr;
Fs: aflnual average frequency of occurrence of wind speed group S (dimensionless) obtained
from the joint relative frequency distribution for the mill (provided by DUSA (DUSA 2007c);
Rs: resuspension rate for the tailings pond at the average wind speed for wind group S, for
particles < 20 pm in diameter in glmzs;
3.156x107: number ofseconds per year; and,
0.5: fraction of the total dust lost constituted by particle < 20 pm in diameter.
TABLE A.1
PARAMETER VALUES FOR CALCULATION OF ANNUAL DUSTING RATE FOR
EXPOSED TAILINGS
a) Resuspension rate of a function of wind speed is computed by the MILDOS code.
b) Wind speed frequency obtained from joint frequency distribution data provided by DUSA (DUSA 2007c).
A-1
Wind Speed (kts)Average Wind
Speed
Resuspension
Rate (Rs)
(g/m's)"
Frequency
of
Occurrence,
(Fs)b
RsxFg
0to3 1.5 0 0.165 0.00E+00
4to6 5.5 0 0.427 0.00E+00
7tol0 10.0 3.92E-07 0.276 1.08E-07
ll to 16 15.5 9.68E-06 0.106 L03E-06
17 to 2l 21.5 5.71E-05 0.021 1.20E-06
2l+28.0 2.088-04 0.005 1.04E-06
Is 3.37E.06
Notes:
34489 - February 2007 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
Wite Mesa Uranium Mill
Using equation A.1 and the parameters in Table A-1, the annual dust loss from the tailings ponds
is approximately 213 gl^'yr. As mentioned in Section 4.2.1, the annual dust lost for ore pads is
l0o/o of that of the tailings ponds since the particulates on the ore pad are coarse material (1 to 6
inch) because the ore has not yet been ground; therefore the annual dust loss from the ore pad is
21.29 il^'yr.
L.2 Emission Calculations
The equations and assumptions used to calculate the radioactive particulate ((U-238) and its
daughters thorium (Th-230), radium (Ra-226) and lead (Pb-210)) and radon emission rates from
the grizzly, grinding, ore pads, vanadium stack (exclusively for processing Colorado Plateau
ore), yellowcake stacks (north and south yellowcake stacks) and the tailings ponds were taken
from NRC's Regulatory Guide 3.59 OfRC 1987), NUREG-0706 OrRC 1980) and the EnecoTech
analysis (EnecoTech l99la and 1991b).
A.2.1 Wet Grinding
Radiouctive Partic ulate Emission Rates
Colorado Plateau
Ore
Arizona Strip
Ore
Process Rate (tpy)730,000 730,000
Contaminant Concentration (pCi/g U-238)700 1783
Process Emission Factor (lbs/ton)u 0.16 0.16
Activity Enrichment Ratio 2.5 2.5
Control Factor (%)"99.90 99.90
Notes:
a) For moisture <8% (NRC 1987).
b) Particulate emission control from the wet grinding operations is assumed tobe99.9o/o (EnecoTech l99la and
leeeb)
The U-238 Emission Rate (S) is calculated as follows:
S: (Process Rate (tons/yr))*(Process Emission Factor (lbs/ton))*(453.6 g/lb)*(Contaminant
Concentration (pCi/g))*(Activity Enrichment Ratio)*(l-Control Factor)*(10-'' CilpCil (A.2-1)
Using equation A.2-1, the U-238 Emission Rate from wet grinding operations of Colorado
Plateau ore is approximately 9.27E-05 Ci/yr. U-238 decay daughters (Th-230, Ra-226 and Pb-
210) are assumed to be in secular equilibrium; therefore the decay daughters are also emitted at a
rate of 9.278-05 Cilyr. Similarly, the U-238 Emission Rate from the wet grinding operations of
34489 - February 2007 A-2 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
Wite Mesa Uranium Mill
Arizona Strip ore is approximately 2.368-04 Cilyr and the decay daughters (Th-230, Ra-226 and
Pb-210) are also emitted at arate of 2.368-04 Cilyr.
Radon Emission Rates
Colorado
Plateau ore
Arizona
Strip ore
Process Rate (tpy)730,000 730,000
Contaminant Concentratron
(pCr/gRa-226)
700 r 783
Activity Factor(%o)"20 20
Note:
a) It is assumed that only 20oh of the radon is available for release or emanation from the mineral grains in which it
is produced (i.e. the emanating fraction or power is 0.20) (NUREG 0706 1980).
Radon Release (F):
F: (Process Rate (tons/yr))*(2000 lbs/ton)*(453.6 g/ton)*(Contaminant Concentration pCi/g Ra-
226)*Oo't2 CilpCi)*(Activity Factor) ( -2-2)
Using equation A.2-2, the radon release from the wet grinding operations of Colorado Plateau
ore is approximately 92.7 Cilyr. Similarly, the radon release from the wet grinding operations of
Aizona Strip ore is approximately 236 Cilyr.
A.2.2 Ore Dump to Grizzly
Radioactive Partic ulate E mission Rates
Colorado Plateau
Ore
Arizona Strip
Ore
Process Rate (tpy)730,000 730,000
Contaminant Concentration (pCi/g U-238)700 I 783
Process Emission Factor (lbs/ton)"0.l6 0.16
Activity Enrichment Ratio 2.s 2.5
Control Factor (%)99.90 99.90
Notes:
a) For moisture <8% (NRC 1987).
b) Gizzly Dump is enclosed on three sides. Trucks dump inside enclosure under negative pressure. The ID fans
are ducted through a baghouse. Ore moisture content is l0 %.
34489 - February 2007 A-3 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Report for
ll'hite Mesa Uranium Mill
The U-238 Emission Rate (S) is calculated as follows:
S: (Process Rate (tons/yr))*(Process Emission Factor (lbs/ton))*(453.6 g/lb)*(Contaminant
Concentration (pCi/g))*(Activity Enrichment Ratio)*(l-Control Factor)*(10'" Cilpctl (A.2-3)
Using equation A.2-3, the U-238 Emission Rate due to the trucks dumping Colorado Plateau ore
on the gizzly is approximately 9.278-05 Cilyr. U-238 decay daughters (Th-230, Ra-226 and
Pb-210) are assumed to be in secular equilibrium; therefore the decay daughters are also emitted
at a rate of 9.27E-05 Ctlyr. Similarly, the U-238 Emission Rate due to the trucks dumping
Arizona Strip ore on the gizzly is approximately 2.368-04 Crlyr and the decay daughters
(Th-230, Ra-226 and Pb-210) are also emitted at a rate of 2.368-04 Crlyr.
Radon Emission Rates
No radon is released from the trucks dumping ore onto the grizzly.
A.2.3 YellowcakeStacks
As mentioned in Section 4.1.3, the mill has two
stack dryers); therefore the total emissions were
stacks (i.e., north and south yellowcake stacks).
Radioactive Partic ulate E mission Rates
yellowcake dryers (north and south yellowcake
assumed to be divided equally between the two
Colorado Plateau
Ore
Arizona Strip Ore
Process Rate (tpy U3Os)t7t6 4371
Contaminant Concentration (Cilg of U-238)3.338-07 3.338-07
Process Emission Factor (g U-238/g U3Os)0.848 0.848
Emission Rate/ Control Factor (lbs/ton)u 0.092 0.092
Note:
a) Based stack tests that showed an emission rate of 0.06 lbsnu UrOe per 1300 lbs/hr process rate which translates
to 0.092 lb/ton including controls.
The U-238 Emission Rate (S) for one yellowcake stack is calculated as follows:
S: [(Process Rate (tons/yr U:Os))*(Emission Rate (lbs/ton))*(Process Emission Factor)*
(453.6gllb)*(ContaminantConcentration(Crlg))llz ( .2-4\
34489 - February 2007 A-4 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
White Mesa Uranium Mill
Based on field measurements, the decay daughters Th-230, Ra-226 and Pb-210 are processed
along with yellowcake at 0.22oh,0.13% and0.78oh, respectively.
Using equation A.2-4, the U-238 Emission Rate from each yellowcake stack (north and south
yellowcake stacks) is approximately 1.01E-02 Cilyr for the processing of Colorado Plateau ore.
The emission rate for the decay daughters Tlt-230, Ra-226 and Pb-210 is 2.228-05 Cilyr,
1.31E-05 Cilyr and 7.88E-05 Cilyr, respectively from each yellowcake stack (north and south
yellowcake stacks). Similarly, the U-238 Emission Rate from each yellowcake stack (north and
south yellowcake stacks) is approximately 2.58E-02 Cilyr for the processing of Arizona Strip
ore. The emission rate for the decay daughters Th-230,Ra-226 and Pb-210 is 5.67E-05 Crlyr,
3.358-05 Cilyr and 2.018-04 Cilyr, respectively from each yellowcake stack (north and south
yellowcake stacks).
Radon Emission Rates
There is no significant radon releases during this process.
A.2.4 Vanadium Stack
Radioactive Particulate Emission Rates
As mentioned in Section 4.1.4, the vanadium source was only used in the MILDOS-AREA
model for Colorado Plateau ore. The product from the vanadium recovery contains less than
0.005% UrOs (NUREG 1980). Therefore, the emission rates of U-238 and its decay daughters
from the vanadium stack were assumed to be 0.005% of the total emission rate from the
yellowcake stacks (north and south yellowcake stacks).
Radioactive Particulate
Emission Rate (S) (CUvr)
Total from
Yellowcake
Stacks
Vanadium Stack"
u-238 2.028-02 1.52E-06
Th-230 4.458-05 3.348-09
Ra-226 2.638-05 1.97E-09
Pb-210 1.58E-04 t.l8E-08
Note:
a) Total from yellowcake stacks (north and south yellowcake stacks)*0.005%
Radon Emission Rates
There are no significant radon releases during this process
34489 - February 2007 A-5 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
Wite Mesa Uranium Mill
A.2.5 Ore Pads
The ore pad storage operation has two different sources of emissions - namely unloading from
the truck to the ore pad and wind emissions. For the wind emissions calculated, it was assumed
that approximately 300,000 tons of ore are temporarily stockpiled with a height of 30 ft. and bulk
density of ore of 120 lbs/ft3 (1.47 tons/yd3;. Usirrg these assumptions, the area of the ore pad is
approximately I 7,000 m2.
Radioactive Particulate Emission Rates
Source Description: Truck Unloading
Colorado Plateau
Ore
Arizona Strip
Ore
Process Rate (tpy)730,000 730,000
Contaminant Concentration (pCi/g U-238)700 1783
Process Emission Factor (lbs/yd')"0.04 0.04
Activity Emission Ratio 2.5 2.5
Control Factor None None
Bulk Density of Ore (tons/yd')1.47 1.47
Note:
a) Process emission factor for Truck end dump (NUREG 1987).
The U-238 Emission Rate (S) is calculated as follows:
S: (Process Rate (tons/yr))*(t yd3lt.+l tons)*(Process Emission Factor (lbs/yd3))*(453.6
g/lb)*(Contaminant Concentration (pCi/g))x(Activity Enrichment Ratio)*(10-" Cilpcil (A.2-5)
Using equation A.2-5, the U-238 Emission Rate from truck unloading Colorado Plateau ore is
approximately 1.58E-02 Crlyr. U-238 decay daughters (Th-230, Ra-226 and Pb-210) are
assumed to be in secular equilibrium; therefore the decay daughters are also emitted at a rate of
1.58E-02 Cilyr. Similarly, the U-238 Emission Rate from truck unloading of Arizona Strip ore is
approximately 4.02E-02 Cilyr and the decay daughters (Th-230, Ra-226 and Pb-210) are also
emitted at arate of 4.02E-04 Cilyr.
34489 - February 2007 A-6 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
Wite Mesa Uranium Mill
Colorado Plateau
Ore
Arizona Strip Ore
Area (m')'17000 17000
Contaminant Concentration (pCi/g U-238)700 1783
Process Emission Factor,Ey (g/m'yr)"21.29 21.29
Activity Enrichment Ratio 2.5 ')<
Control Factor (%o)'50 50
Notes:
a) Calculated assuming a stockpile of 300,000 tons of ore with a height of 30 ft. and bulk ore density of 1.47
tons/yd3.
b) The process emission factor for the ore pad was derived in Section A. 1.
c) The control factor of 50% is based on the assumption that an active watering progam will be in place during
operations.
The U-238 Emission Rate (S) is calculated as follows:
S: (Process Emission Factor (d*2y.))*(Area (m2))*(Contaminant Concentration (pci/g))
*(Activity Enrichment Ratio)*(l-Control Factor)*(10-'' Ci/pcil (A.2-6)
Using equation A.2-6, the U-238 Emission Rate from trucks unloading Colorado Plateau ore is
approximately 3.1,78-04 Cilyr. U-238 decay daughters (Th-230, Ra-226 and Pb-210) are
assumed to be in secular equilibrium; therefore the decay daughters are also emitted at a rate of
3.178-04 Cilyr. Similarly, the U-238 Emission Rate from truck unloading of Arizona Strip ore is
approximately 8.07E-04 Cilyr Cilyr and the decay daughters (Th-230, Ra-226 and Pb-210) are
also emitted atarute of 8.07E-04 Cilyr.
The total radioactive particulate emission rates from the ore pad are obtained by adding the
results of truck unloading and wind erosion and are as follows:
Radioactive Particulate
Emission Rate (S) (Ci/yr)
Colorado Plateau
Ore
Arizona Strip
Ore
u-238 l.6l E-02 4.toE.-o2
Th-230 l.6tE-02 4.10F-02
Ra-226 t.6tE-02 4.t0E-02
Pb-2 l0 t.6tE-02 4.10E-02
34489 - February 2007 A-7 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
White Mesa Uranium Mill
Radon Emission Rates
Colorado
Plateau ore
Arizona
Strip ore
Area (m')17000 17000
Contaminant Concentration
(pCr/gRa-226)
700 1783
Specific Radon Flux Factor
(pCi Rn-222 lm2s)/(pCi/g Ra-
226)
I I
Radon Release (F):
F: (Specific Radon Flux Factor (pCi Rn-2221m2s)/(pCi/g Ra-226))*(Contaminant Concentration
(pCi/gRa-226))*(Area(m2)*(3.156x107s/yr)*(10-r2Ci/pci) (A-2-7)
Using equation A.2-7, the radon release from storage of Colorado Plateau ore is approximately
375 Clyr. Similarly, the radon release from storage of Arizona Strip ore is approximately956
Cilyr.
L.2-6 Tailings Ponds
Radioactive Particulate E missio n Rates
Colorado Plateau Ore Arizona Strip Ore
Cell 2 and 3 Cell4A Cell2 and 3 Cell4A
Area (acres)7.7 4 7.7 4
Contaminant Concentration (pCi/g U-
238r
42 42 107 107
Contaminant Concentration of all other
isotopes (pCi/g)
700 700 I 783 I 783
Process Emission Factor, Ee,, (g/m'yr)"2t3 213 213 213
Activity Enrichment Ratio 2.5 2.5 2.5 2.5
Control Factor (%)"70 70 70 70
Notes:
a) Assumes 94o/o rccovery.
b) The process emission factor for the tailings ponds was derived in Section A. L
c) The control factor of70%o is based on the assumption that an active watering program as well as crusting agents
are used to minimize the erosion of the tailings by wind.
The Emission Rate (S) for U-238 and its decay daughters are calculated as follows:
34489 - February 2007 A-8 SENES Consultants Limited
Dose Assessment in Support of the License Renewal Application & Environmental Reportfor
Wite Mesa Uranium Mill
S: (Process Emission Factor (g/m2yr))x(Area (acres))*(4047 m2lacre)*(Contaminant
Concentration (pCi/g)) *(Activity Enrichment Ratio)*(l-Control Factor)*(10-'' Ci/pci; (A.2-8)
Using equation A.2-8, the U-238 Emission Rate from Tailings Cell2 and 3 from the processing
of Colorado Plateau ore is approximately 2.098-04 Crlyr. The decay daughters (Th-230, Ra-226
and Pb-210) are emittedata rate of 3.48E-03 Cr/yr. The U-238 Emission Rate from Tailings
Cell 44 from the processing of Colorado Plateau ore is approximately 1.09E-04 Cilyr. The
decay daughters (Th-230, Ra-226 and Pb-210) are emitted at a rate of 1.81E-03 Crlyr.
Similarly, the U-238 Emission Rate from the Tailings Cell 2 and 3 from the processing of
Arizona Strip ore is approximately 5.328-04 Cr/yr. The decay daughters (Th-230, Ra-226 and
Pb-2 1 0) are emitted at a rute of 8.87E-03 Cily . The U-23 8 Emission Rate from Tailings Cell 4A.
from the processing of Arizona Strip ore is approximately 2.76E-04 Cilyr. The decay daughters
(Th-230, Ra-226 and Pb-210) are emitted at a rate of 4.61E-03 Crlyr.
Radon Emission Rates
Colorado Plateau Ore Arizona Strip Ore
Cell 2 and 3 Cell4A Cell 2 and 3 Cell4A
Area (acres)I12.8 4 I12.8 4
Contaminant Concentration (pCi/m's)8. l7 24.2 8. 17 24.2
Radon Release (F):
F: (Contaminant Concentration (pCi/m2s)*(Area (acres))*(4047 m2lacre)*(3.156x107 s/yr)*(10-
'2 ci/pci; (A-2-9)
Using equation A.2-9, the radon release from Tailings Cell 2 and 3 (combined) and Tailings Cell
4,A. is approximately 117.71 Cilyr and 12.36 Cilyr, respectively from the ore processing
operations at the mill.
34489 - February 2007 A-9 SENES Consultants Limited
8/2008) Loren Morton - RE: Denison: Cell 48 Environmental Report - Problems with Figures Page 1
From: "Steve Landau" <[e-mail]>
To: "'Loren Morton"'<[e-mail]>CC: "'David Frydenlund"'<[e-mail]>, "'Dane Finerfrock"'...Date: 5114108 2:26 PMSubject: RE: Denison: Cell 48 Environmental Report - Problems with FiguresAttachments: FIGURE 4.1.pdf; Figure 12.pdf
Loren,
Please find attached the figures you have requested.
Steven D. Landau
Manager, Environmental Affairs
Denison Mines (USA) Corp.
1050 17th Street, Suite 950
Denver, CO 80265
[phone]
[phone] Fax
---Original Message---
From : Loren Morton [mailto:LMORTON@utah. gov]
Sent: Tuesday, May 13, 2008 9:48 AM
To: Steve Landau
Cc: David Frydenlund; Dane Finerfrock; John Hultquist
Subject: Denison: Cell 48 Environmental Report - Problems with Figures
Steve,
We got the extra copies of the 4l3il08 Cell 48 Environmental Report
yesterday. After looking over the PDF files you sent, we found a couple of
problems, that need to be fixed, as follows:
1 . Missing Figure 12 - there was no electronic copy provided for Figure 12
of the Environmental Report.
2. Unreadable Figure in Appendix B - on page 4-2 of the 4/08 Senes
Consultants Ltd report there is a Figure 4.1, Site Locations - that is
unreadable in the PDF format.
Please provide the missing figure, and correct the unreadable one. lf it
will help, you can email the revised files to me.
Thanks,
Loren
512812008) Loren Morton - Denison: Cell 48 Environmental Report - Problems with Figures in Electronic 1
From: Loren ModonTo: Steve LandauCC: Dane Finerfrock; David Frydenlund; John HultquistDate: Sll3lOB 9:48 AMSubject Denison: Cell 48 Environmental Report - Problems with Figures in Electronic Version
Steve,
We got the extra copies of the 4/30/08 Cell 48 Environmental Report yesterday. After looking over the PDF files you sent,
we found a couple of problems, that need to be fixed, as follows:
1. Missing Figure 12 - there was no electronic copy provided for Figure 12 of the Environmental Report.
2. Unreadable Figure in Appendix B - on page 4-2 of the 4/08 Senes Consultants Ltd report there is a Figure 4,1, Site
Locations - that is unreadable in the PDF format.
Please provide the missing flgure, and correct the unreadable one. If it will help, you can email the revised files to me.
Thanks,
Loren