The influence of uranium ore bodies on natural radioactivity present in
groundwater at Coles Hill uranium deposit in Pittsylvania County, VA
Caitlin Neely
Introduction
Finding new ways to meet the rapidly increasing energy demands of society is essential in order
to sustain our current way of life. In order to meet these energy needs, various approaches are
used in order to generate power, including nuclear power. Nuclear power is generated using
uranium, a radioactive element. Uranium spontaneously emits radiation due to the degeneration
of its atomic nuclei. Uranium has several isotopes, but it’s most common is Uranium 238.
Uranium decays into plutonium by the process of fission in nuclear reactors (Slaughter, 2010).
This fission generates heat that is used to generate steam, which turns a turbine and generates
electricity. For this reason, uranium is an important energy resource and is currently of high
economic value. Since nuclear power makes up sixteen percent of the world’s electricity, it is
important for geologists to locate uranium deposits in order to mine the ore for use in nuclear
reactors (Slaughter, 2010).
History of Uranium in Virginia
In 1973 the Atomic Energy Commission created the National Uranium Resource Evaluation
(NURE) program to identify uranium resources within the United State due to the increase in
demand for uranium. In 1977, the Marline Uranium Corporation began looking for uranium
deposits in Virginia and came across the Coles Hill property located in Pittsylvania County
(Slaughter, 2010). The incidents at Three Mile Island and Chernobyl in the 1980 caused uranium
prices to plummet for many years (Gannon et al., 2012). These incidents caused Virginia
legislature to place a moratorium on uranium, prohibiting uranium mining applications until the
state could create a law permitting a uranium mining program (Slaughter, 2010). The recent rise
in prices made the Coles Hill deposit economically valuable, and has created a debate about
whether or not the moratorium should be lifted to allow for uranium mining in Virginia.
The uranium deposit at Coles Hill is the largest undeveloped uranium deposit in the United
States (Gannon et al. 2012). The Coles Hill property consists of two ore bodies of uranium, one
more northerly than the other. The southern ore body is located near latitude36°52'18"N,
longitude 79°18'00"W on the Spring Garden USGS 7.5-minute quadrangle topographic map, and
the North deposit is centered near latitude 36°52'43"N, longitude 79'18'12W" on the Gretna
USGS 7.5-minute quadrangle topographic map (Christopher, 2007). The southern ore body is
thought to contain much more uranium than the northern. (Slaughter, 2010). The total value of
the Coles Hill deposit is currently estimated between 7 and 10 billion dollars (Slaughter, 2010).
Geology of Coles Hill Deposit
The Coles Hill uranium deposit is located within the Piedmont geologic province located in the
foothills of the Appalachian Mountains. The region generally consists of granite, gneiss, schist
and slate of Proterozoic and Paleozoic age (National Research Council, 2012). More specifically,
the rocks located in the piedmont northwest of Chatham fault can be characterized by three
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distinct units. Starting from the west is the Leatherwood granite which is part of the Martinsville
Igneous Complex, and then there is the Fork Mountain formation consisting of schist and gneiss,
and lastly the Central Virginia Volcanic-Plutonic belt containing augen gneiss interlaid by
amphibolites. The foliation of these three units dips south toward the Chatham fault,another key
geologic feature in this region(Gannon, 2009). The fault separates crystalline rocks to the west of
the fault from the metasedimentary rocks of the Danville Triassic Basin (Henika & Thayer,
1983).
The uranium ore at Coles Hill is a hydrothermal deposit. Hydrothermal deposits occur in
intersecting fractures where fluids are able to mix and precipitate high-grade uranium minerals
(Wyatt, 2009). The uranium minerals are located within the augen gneiss that is directly west of
the Chatham fault zone (Gannon, 2009). The main ore minerals from this deposit are uraninite
and coffinite (National Research Council, 2012). The uranium is located within shallow,
horizontal fractures which suggest that uplift and erosion formed the tension veins containing
uraninite and coffinite (Wyatt, 2009).
Environmental Impacts
There are many concerns with allowing uranium mining in Virginia because all mining activities
result in environmental impacts (National Research Council, 2012). ). Uranium mining in
Virginia has the potential to affect surface water quality, groundwater quality, air quality, soils
and biota (Carvalho & Oliveira, 2006; Slaughter, 2010; Rogers, 2011; Kingston et al. 2012;
National Research Council, 2012). Uranium mining is more detrimental than other mining
activities because uranium production generates waste containing radioactivity that can be
released into the environment and become a radiological concern (Carvalho and Oliveira, 2006).
More specifically, radioactive elements have harmful impacts to public health, such as various
types of cancer, kidney damage, skeletal tumors, and paranasal sinus carcinomas (Rana et. al.,
2010, Canu et al., 2011).
The key concerns about mining Coles Hill are related to surface and groundwater quality of the
region. Since Coles Hill is located within the Dan River basin, there are many concerns about
how water quality of the Dan River might be affected by uranium mining. The Dan River is very
important because it drains into the Kerr Reservoir which, in turn feeds Lake Gaston (National
Research Council, 2011). Lake Gaston is the source of drinking water for Virginia Beach,
Chesapeake, and Norfolk, areas that are home to the majority of Virginias’ population. Also,
groundwater quality and quantity is a concern for residents of Pittsylvania County, because their
drinking water comes mostly from private wells. The mine dewatering process could affect the
quantity of groundwater because the water table may need to be lowered in order to facilitate
mining. Mine dewatering prevents groundwater from entering the mine by either pumping it out
and discharging it at the surface, or by lowering the water table using extraction wells
surrounding the mine to prevent water from entering (National Research Council, 2012).
Lowering the water table leads to lower groundwater levels in surrounding wells which can
cause wells to eventually go dry. Groundwater contamination from failures or leaks in retaining
structures for ore tailings is also a major concern (National Research Council, 2011). For this
reason, a better understanding of the magnitude of these environmental impacts are needed in
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order to determine if the mine can safely operate, and if so, help identify measures needed to
mitigate or minimize the adverse effects.
Hydrogeology
Little is known about the impact uranium mining could have on groundwater quality in the
region. Research suggests that only small amounts of groundwater in the Piedmont region flow
through the Chatham fault and into the Danville Triassic basin (Gannon, 2012). However,
fractures and cross faults in the subsurface around the Coles Hill deposit make the area
extremely heterogeneous and difficult to determine local groundwater flow around the deposit
(Gannon, 2009). More extensive research about groundwater flow and current groundwater
quality near the deposit is needed because approximately 60 percent of Pittsylvania county
residents get their drinking water from private wells. More specifically, there are 250 private
wells located within 2-3 miles of Coles Hill (Moran, 2011). Additionally, private wells are not
regulated by the Virginia Department of Health for any contaminants beyond bacteriological
contamination (Uranium Working Group, 2012). Therefore, it is important to study the
groundwater flow of the area in order to better understand the potential impact a failure or leak in
retention structures would have on the private water supply of nearby residents.
Current research suggests that uranium concentrations in shallow groundwater at the Coles Hill
deposit are naturally lower than the EPA maximum contaminant level of 30 µg/L due to presence
of phosphate minerals that precipitate to form a sparingly soluble U(VI) phosphate, Ba metaautunite (Jerden & Sinha, 2002). However, other radionuclides are also present in uranium
deposits from the natural decay series of uranium such as radium and radon (Johnson, 1991). It is
expected that these radionuclides are dissolved in the groundwater and contribute to the amount
of radioactivity in the groundwater at Coles Hill. The gross alpha test provides the overall
amount of radioactivity present in the water. The purpose of this study is to determine if there are
higher levels of gross alpha activity in groundwater sampled at the uranium deposit than samples
taken farther away from the deposit. This is expected because uranium and its decay products
contribute to an elevated gross alpha activity. If this is supported by the data, the direction of
groundwater flow, including flow through the Chatham fault, may be determined based on the
amount of gross alpha activity in the groundwater.
Experimental Procedure
Sample collection
I took 6 water samples from wells located on or near the Coles Hill uranium deposits (Figure
1.1). Sites were determined based on which wells I was given permission to sample. I collected
samples by first decontaminating the spigot or faucet with isopropanol and then purging the
water line for 5 minutes. Protocol was not followed on site 5 because the pump was powered by
solar panels. I feared that there would not be enough water after running for 5 minutes (NHDES,
2011). The samples were collected in 500 ml sterile bottles and then capped tightly.
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Figure 1: Map of site locations
Gross alpha analysis
The samples were delivered to a laboratory for measurement of gross alpha activity using EPA
900.0 method (EPA, 2009). The EPA limit for gross alpha is 15 pCi/L. Table 1.1 shows the gross alpha
activities for each 6 sample locations.
Site #
Gross Alpha pCi/L
Site 1
0.163 ± 0.826
Site 3
0.204 ± 1.02
Site 4
183 ± 12.2
Site 5
8.0 ±1.54
Site 6
-0.143 ±0.834
Site 7
0.217 ± 0.930
Table 1: Gross Alpha activity measured in pCi/L
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Results
The natural gross alpha activity in groundwater around the Coles Hill uranium deposit was found
to vary from -0.143± 0.834 pCi/L to 183 ± 12.2 pCi/L. The EPA maximum contaminant level
(MCL) for gross alpha is 15 pCi/L.Site 4 was found to be above the EPA MCL. The other
measurements were below the MCL for gross alpha. The results show that the highest gross
alpha activity is found at sites 4 and 5. The gross alpha in sites 1, 3, 6, and 7 are much lower than
sites 4 and 5 (Table 1). Figure 2 shows a map of the site locations with corresponding gross
alpha activities. Sites 3 and 7 are located on the east side of the Chatham fault and all other
samples were taken on the west side of the Chatham fault (Figure 3). The lowest gross alpha
activities on samples taken from the west side of the fault are farther away from the northern and
southern uranium ore bodies (Site 1 & Site 6). The highest gross alpha activities (Site 4 & Site 5)
are located on or close to the northern ore body (Figure 3).
Figure 2: Map of sample locations and corresponding gross alpha activity in pCi/L
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Figure 3: Map showing uranium ore bodies in red, Chatham fault in white, and sample locations
Discussion
This pilot study reveals that there is an elevated gross alpha in sites on or close to the northern
uranium ore body. Gross alpha located almost on top of the southern ore body is not elevated,
but can be explained by its location on the eastern side of the Chatham fault. Sites located farther
from the uranium ore bodies have very low gross alpha activities as expected. The low gross
alpha activities of well water taken on the east side of the fault can further support that the
Chatham fault might be acting as a barrier to groundwater flow. Overall my results support my
hypotheses; however, well depth data is needed in order to further investigate why some gross
alpha activities were low and some high. The large difference gross alpha activities in site 4 and
site 5 might be a result of how deep the wells were. If the well at site 4 was much deeper than at
site 5, the difference in gross alpha activities would make sense. However, I was not able to
obtain well depth data. Also, duplication of these samples during different times of the year
would be useful in order to get a more accurate radioactivity level. More sample locations would
also be useful for further investigation of groundwater flow through the Chatham fault.
Conclusions
The results of this study show higher gross alpha activities in groundwater samples taken on the
west side of the fault as you get closer to the uranium ore bodies. The results also support that the
Chatham fault acts as a barrier to groundwater flow due to low gross alpha activities from sites
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located on the east side of the fault. The results may also be explained by other factors not
addressed in this study.
This study addresses concerns the local community has about allowing mining of the Coles Hill
deposit. There is a drop in gross alpha activity of water samples taken farther (~1km) from the
ore bodies. This could indicate that local residents using private wells as their drinking water
source are not in danger of having natural radioactivity in their well water as a result of the
uranium ore bodies.
Acknowledgements
I would like to thank Dr. Joe Aylor for all of his help with this project, as well as Walter Coles
for allowing me to sample wells on the Coles Hill property. I would also like to thank Lynchburg
College for its support through the Schewel Student-Faculty Research Award.
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Literature Cited
Campos, M., de Azevedo, H., Nascimento, M., Roque, C., & Rodgher, S. 2011. Environmental
assessment of water from a uranium mine (Caldas, Minas Gerais State, Brazil) in a
decommissioning operation. Environmental Earth Sciences, 62(4), 857-863.
Canu, I., Laurent, O., Pires, N., Laurier, D., & Dublineau, I. 2011. Health Effects of Naturally
Radioactive Water Ingestion: The Need for Enhanced Studies. Environmental Health
Perspectives, 119(12), 1676-1680.
Cappello, M., Ferraro, A., Mendelsohn, A. B., & Prehn, A. 2013. Radon-Contaminated Drinking
Water From Private Wells: An Environmental Health Assessment Examining a Rural
Colorado Mountain Community's Exposure. Journal Of Environmental Health, 76(4), 1824.
Carvalho, F. P., & Oliveira, J. M. 2007. Alpha emitters from uranium mining in the
environment. Journal Of Radioanalytical & Nuclear Chemistry, 274(1), 1-8.
Christopher, Peter A. 2007. Technical Report on Coles Hill Property Pittsylvania County,
Virginia.1-49.
Environmental Protection Agency. 2009. Gross Alpha and Gross Beta Radioactivity in Dringing
water Method 900.0. 1-9.
Gannon, John. 2009. Evaluation of Fracture Flow at the Coles Hill Uranium Deposit in
Pittsylvania County, VA using Electrical Resistivity, Bore Hole Logging, Pumping Tests,
and Age Dating Methods. Virginia Polytechnic Institute and State University. 1-291.
Gannon, J., Burbey, T., Bodnar, R., & Aylor, J. 2012. Geophysical and geochemical
characterization of the groundwater system and the role of Chatham Fault in groundwater
movement at the Coles Hill uranium deposit, Virginia, USA. Hydrogeology
Journal, 20(1), 45-60.
Henika, William S., & Thayer, Paul A. 1983. Geologic Map of the Spring Garden Quadrangle,
Virginia.
Jerden, James L. & Sinha, A.K. 2002. Phosphate based immobilization of uranium in an
oxidizing bedrock aquifer. Applied Geochemistry. 823-843.
Johnson, Stanley. 1991. Natural Radiation. Virginia Division of Mineral Resources Virginia
Minerals. 37(2) 9-15.
Kingston, J.F., Castro-Bolinaga, Zavaleta, E.R., & P. Diplas. 2012. Probable maximum flood
inundation modeling: a case study in southern Virginia. Virginia Polytechnic Institute and
State University, 1-8.
Moran, Robert E. 2011. Site Specific Assessment of the Proposed Uranium Mining and Milling
Project at Coles Hill, Pittsylvania County, VA. 1-39.
8
National Research Council. 2012. Uranium Mining in Virginia: Scientific, Technical,
Environmental, Human Health and Safety, and Regulatory Aspects of Uranium Mining
and Processing in Virginia. The National Academies Press, Washington DC. 1-345.
New Hampshire Department of Environmental Services. (2011). New Hampshire Sample
Collection & Preservation Manual for Drinking Water. 1-55.
Rana, B.K., Tripathi, R.M., Sahoo, S.K., Sethy, N.K.,Sribastav, Shukla, A.K., & Puranik V.D.
2010. Assessment of natural uranium and 226 Ra concentrations in ground water around
the uranium mine at Narwapahar, Jharkhand, India and its radiological significance.
Journal of Radioanalytical and Nuclear Chemistry. 285(3), 711-717.
Slaughter, K. E. 2010. Will Uranium Get a Glowing Welcome in Virginia? Virginia
Environmental Law Journal, 28(3), 471-518.
Uranium Working Group. 2012. Commonwealth of Virginia 2012 Uranium Working Group
Report. 1-104.
Wyatt, J. 2009. The Relationship between Structural and Tectonic Evolution and Mineralization
at the Coles Hill Uranium Deposit, Pittsylvania County, Virginia. 1-58.
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