EVALUATION OF IMPACT
MINES DEVELOPMENT, IMC. MIL
ITY CONDITIONS IN THE CHEYENNE RIVER
ONMENTAL,PHDTECTI
Regffon VIII
Denser, Colorado
September 1971
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EVALUATION OF THE IMPACT
OF THE
MINES DEVELOPMENT, INC. MILL
ON
WATER QUALITY CONDITIONS IN THE CHEYENNE RIVER
ENVIRONMENTAL PROTECTION AGENCY
Region VIII
Denver, Colorado
September 1971
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TABLE OF CONTENTS
Section Title Paqe
LIST OF FIGURES ii
LIST OF TABLES ii
I INTRODUCTION 1
II SUMMARY 7
III RECOMMENDATIONS 12
IV WASTE MANAGEMENT PRACTICES 14
V PREVIOUS WATER QUALITY STUDIES 18
VI 1971 FIELD STUDY 37
Study Procedures 37
Sample Processing Procedures 41
Results 42
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LIST OF FIGURES
Figure No. Title Page
1 Location Map 3
Mines, Development, Inc. Uranium Mill
Process Ponds and Tailings Piles
LIST OF TABLES
Table No. Title Page
I Radioactivity Standards 10
II Mill Process and Retention Ponds 15
III Cheyenne River and Cottonwood Creek 19
Sampling Stations
IV Dissolved Radioactivity in Cheyenne 20
River and Cottonwood Creek Water
Samples
V Chemical and Physical Characteristics 23
of Cheyenne River and Cottonwood
Creek Water Samples
VI Physical and Radiological Characteristics 27
of Seepage Samples
VII Radioactivity Chemical Contents Of Bottom 32
Sediments From The Cheyenne River and
Cottonwood Creek
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LIST OF TABLES (Continued)
Table No. Title Page
VIII Radium-226 Concentrations in 36
Angostura Reservoir Fish -
September, 1966
IX Cottonwood Creek and Cheyenne River 38
Sampling Stations - 1971
X Dissolved Radioactivity in the Cheyenne 43
River, Cottonwood Creek, Hat Creek,
and Cascade Springs
111
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I. INTRODUCTION
An intensive water quality study of the Cheyenne River
and the tributary stream, Cottonwood Creek, in the environs
of the Mines Development Mill located at Edgemont, South
Dakota, was conducted by EPA personnel!/ during July 26-30,
1971. The objectives of the study were to determine and
evaluate:
1. Water quality conditions in Cottonwood Creek and the
Cheyenne River during a period of dry weather flow.
2. Chemical and radioactivity loadings (mass/day) on
Cottonwood Creek and the Cheyenne River as the re-
sult of seepage from mill ponds.
3. Radioactivity levels in the water, biota and bottom
sediment of Angostura Reservoir.
The July study was conducted at the request of the South Dakota
State Department of Health. In this respect, the study repre-
sented a continuation of the support provided to the State in
its long-term program to monitor and assess the environmental
impact of mill operations. Mines Development personnel were
I/ Radiological Activities Section, Division of Technical
Support, Office of Water Programs, Cincinnati, Ohio
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most cooperative in providing the field team with unlimited
access across mill property and bench space in the mill labora-
tory.
The "Edgemont" mill is operated by Mines Development, Inc.,
a subsidiary of the Susquehanna Corporation, As shown in Figure
I, the mill is located in the southwest corner of South Dakota
on the south bank of the Cheyenne River. A tributary to the
Cheyenne River, Cottonwood Creek, traverses the mill property
and is flanked on both sides by inactive sand tailings piles
(Figure 2). Angostura Reservoir, a recreational lake, is
located about thirty-five miles downstream near the city of Hot
Springs.
Mineral processing operations carried out at the mill in-
volve the recovery of uranium, vanadium, and molybdenum (a
contaminant in the uranium ore). Recovery and extraction
operations for vanadium and uranium are housed in separate
buildings. However, the two circuits are connected with the
slime tailings -effluent from the uranium circuit becoming the
feed solution to the vanadium circuit after clarification in
the mill ponds. Uranium ore is locally obtained from shaft and
open-pit mines. A foreign source of ore is used as the dry feed
to the vanadium circuit to supplement the soluble vanadium feed
from the uranium circuit. During the July study, the average
2
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HOT SPRINGS
AIRPORT
ANGOSTUKA
R£S>£R.VOi
W£BRASKA STATE
LOCATION MAP
FIGURE 1
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CHEYENNE RIVER
SAND TAILINGS PILE *!
MINES DEVELOPMENT, INC:
URANIUM MILL
PROCESS PONDS AND TAILINGS PILES
FIGURE 2
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ore feeds to the uranium and vanadium circuits were 400 and
15.5 tons/day, respectively. For uranium, this corresponded to
operation at approximately sixty percent of plant capacity,
650 tons/day.
Pre-operational surveillance of the Cheyenne River was per-
formed during February, 1956, by personnel of the South Dakota
Department of Health and U. S. Public Health Service. Four
stations were sampled: (1) upstream from the mill site at the
State Highway 18 bridge, (2) approximately 1.5 miles downstream
from Edgemont, {3) at Falls Canyon and (4) just upstream from
the confluence with Tepee Creek. Unfortunately, since the
mechanics of environmental surveillance were in the develop-
mental stages at that time, radioactivity analysis was limited
to gross procedures instead of the more definite, analysis for
specific radionuclides. Water samples contained 10 to 40
picocuries per liter (pCi/1) of dissolved alpha activity and
10 to 120 pCi/1 of dissolved beta activity; suspended radio-
activity was negligible. In retrospect, dissolved gross alpha
and beta concentrations at the upper limits of the observed
ranges now seem unusually high for natural background conditions.
Bottom sediment samples showed an average content of 10 and 15
picocuries per gram (pCi/g) of dry solids of alpha and beta
activity, respectively. All the biological samples (algae.
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insects, minnows and plankton) showed corresponding low con-
centrations of gross radioactivity. The initial post-opera-
tional monitoring effort (June 1957) did not show levels of
dissolved radioactivity in either the Cheyenne River or Cotton-
wood Creek greater than background levels, despite a low flow
drainage from the sand tailings pond to the creek containing
1400 and 1800 pCi/1 of dissolved alpha and beta activity, re-
spectively.
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II. SUMMARY
Uranium and vanadium recovery operations carried out at
the Edgemont mill generate liquid wastes and spent ore solids
which are discharged to a system of ponds. These ponds retain
the fine (slimes) and coarse (sand tailings) ore solids on the
mill property. However, due to the permeability of the soil
in which the ponds are excavated, liquid wastes are lost to the
ground and eventually reach the Cheyenne River and Cottonwood
Creek in the form of seepage. The impact of this seepage in
the water environment is the following:
1. Unsightly discoloration of stream bank and channel
areas by the accumulation and/or deposition of "iron-
rich" solids.
Although the areas so affected are rather extensive
during low flow conditions, the only area which is
readily visible from the State Highway 18 bridge is
the seepage zone adjacent to Pond No. 2.
2. Increases chemical and radioactivity concentrations
in Cottonwood Creek and, to a much lesser extent, the
Cheyenne River.
The 1964 study showed dissolved uranium and radium-
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226 concentrations in Cottonwood Creek substantially
in excess of background concentrations (30 and 100X
greater, respectively). In subsequent studies,
radium and uranium concentrations were lower; approxi-
mately one order of magnitude greater than back-
ground levels.
Consistent with the findings for Cottonwood Creek,
the maximum radioactivity concentrations in the
Cheyenne River were obtained in the 1964 study. At
a location about 1.5 miles below the mill, dissolved
radium-226 and uranium concentrations were 2.5 pCi/1
and 130 pg/1, respectively. These values corre-
sponded to a ten-fold increase above background. The
results for other studies at this same sampling
station and other downstream stations were substan-
tially lower - values less than 1.0 pCi/1 of radium-
226 and 50 pg/1 of uranium.
Flow data for the 1971 study indicated that Hat Creek has a
decided impact on Cheyenne River water quality conditions, at
least during low flow periods. During the 1971 study, Hat
Creek was responsible for 80 percent of the Cheyenne River
flow at the State Highway 71 bridge.
8
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Increased radioactivity levels in the Cheyenne River down-
stream from the mill do not pose a health hazard from excessive
exposure to radiation. Obviously, the non-use of the Cheyenne
River for domestic water supply makes this conclusion a fact.
However, a comparison of the observed concentrations of radium-
226 and uranium with currently accepted standards (Table I)
also shows that the radiological quality of the Cheyenne River
is acceptable for drinking water purposes. Based on the radium-
226 concentrations observed during low flow conditions, it
seems possible that the annual average concentration of radi-
um-226 does not exceed 1.0 pCi/1. If the Cheyenne River was
used as a regular source of drinking water, the resultant in-
take would be only 5% of the transient rate of daily intake for
the general population, as recommended by the Federal Radiation
Council (upper limit of Range II). The fact that the maximum
radium concentration observed in the Cheyenne River was less
than the current Public Health Service guideline for radium-
226 in drinking water also demonstrates the absence of a poten-
tial health hazard from this radionuclide. Similarly, the dis-
solved uranium concentrations in the river have not approached
levels of public health significance. The maximum concentration
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TABLE I RADIOACTIVITY STANDARDS
Drinking Water
Radionuclide Standard
Radium-226
Uranium
700 ug/1
22 mg/l(c)
Limiting Rate Of
Daily Intake
From All Sources
(Annual Average)
3.0 pCi/l 20 pCi/day
0 to 2 pCi/day-Range I
2 to 20 pCi/day-Range II
20 to 200 pCi/day-Range III
0.7 ing/day
22 mg/day(d)
Recommendi ng
Authority
U.S. Public Health Service
Federal Radiation Council
International Commission
on Radiological Protection
(ICRP)
National Committee on
Radiation Protection (NCRP)
(a) The limit may be exceeded if the radioactivity intake from all sources in addition to
that from water does not exceed intake levels recommended by the Federal Radiation
Council for control action (the upper limit of Range II).
(b) Action required:
Range I - Periodic confirmatory surveillance as necessary.
Range II - Quantitive surveillance and routine control.
Range III - Evaluation and application of conditional control measures as necessary.
(c) Calculated from the limiting rate of daily intake by assuming a daily intake from
drinking water of 1 liter/day and no intake from other sources.
(d) Based on 1/30 of the maximum permissible concentration for natural uranium for con-
tinuous occupational exposure, the specific activity for uranium-238» an activity
ratio (uranium-234/uranium-238) equal to unity, and a daily water intake of 2.2
liters/day from all sources.
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of dissolved uranium observed in Cheyenne River was about 20%
of the ICRP standard; negligible in comparison to the NCRP
standard. (Note; To date, the more restrictive ICRP standard
has not been formally adopted by the NCRP.)
The contaminated reach of Cottonwood Creek lies wholly
within the mill property with access to the general public re-
stricted. Therefore, the creek is not a direct source of
radiation exposure to the general public.
Based on visual observations, sand tailings from the three
storage areas (Pile No. 1, Pile No. 2, and Pond No. 2) are
entering the water environment by wind and/or water errosion.
Such off-site losses of these high-radioactivity solids is most
undesirable and should be curtailed at an early date.
11
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III. RECOMMENDATIONS
1. The bottom and sidewalls of the retention ponds should be
sealed to eliminate seepage into Cottonwood Creek and the
Cheyenne River.
2. A two phase program providing for the stabilization and
ultimate disposal of sand tailings should be developed with
a reasonable timetable for implementation. As a first
phase, immediate action should be taken to stabilize the
huge bulks of sand tailings stored in Pile No. 1, Pile
No. 2, and Pond No. 2 against wind and/or water errosion.
The most desirable alternative for the second phase of the
program, ultimate disposal, seems to be storage in the ex-
cavated portions of the open-pit uranium mine operated by
Mines Development, Inc.
3. Monitoring stations should be established on Cottonwood
Creek (at the mouth) and the Cheyenne River (downstream
from the mill) to determine the extremes in chemical and
radioactivity concentrations as well as the annual average
radioactivity concentrations. As a minimal effort, weekly
grab samples should be collected with analyses performed
on monthly composites. Monitoring should be continued
12
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after recommendation (1), above, has been implemented to
show the sustained integrity of the sealed ponds. Dur-
ing this stage, the frequency of sample collection could
be reduced to monthly grabs.
4. The classification of Cottonwood Creek should be resolved
in regard to applicable standards, i.e., effluent limits
or receiving water standards. Upstream from the mill the
creek is an intermittent stream whereas flow in the reach
traversing mill property is maintained by seepage, possible
spring flow, and drainage from an abandoned railroad well.
13
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IV. WASTE MANAGEMENT PRACTICES
The waste management program conducted by Mines Develop-
ment essentially provides for the on-site retention of liquid
and solid wastes with no direct release to the water environ-
ment. Briefly, liquid wastes from the uranium and vanadium
extraction circuits are discharged to a system of process ponds
wherein volume reduction occurs by evaporation and seepage.
Seepage losses are the result of pond excavation in a zone of
permeable soil. In order to control the total volume of re-
quired ponding, water is recycled for use as process water.
Sand tailings are stored in two unstabilized piles and two re-
tention ponds. An areal schematic showing the locations of the
ponds and the sand tailings piles is presented in Figure 2.
Operational functions of the various ponds are summarized
in Table II. The flow scheme for the pond system is the follow-
ing;
1. Slime tailings and sand tailings from the uranium cir-
cuit are discharged to Pond No. 7, a pond functioning
as a retention and sedimentation basin.
2. Clarified vanadium-bearing liquor (blue liquor) is
pumped to Pond No. 3.
14
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TJffiLE II MILL PROCESS & RETENTION PONDS
Pond Use
Pond
Current
Past
No 1
No 2
No 3
No 4
No 7
No 8
No 9
No 10
Disposal of raffinate from
the vanadium extraction circuit,
Sand tailings storage.
Storage basin for vanadium-
bearing liquor (blue liquor)
Not in use.
Retention and storage of" slime
tailings and sand tailings;
sedimentation basin to pro-
duce clarified blue liquor.
Contingency.
Not in use.
Contingency.
Retention of slime tailings from
the uranium circuit.
Disposal of vanadium raffinate and
retention of slime tailings.
Retention of slime tailings.
"Polishing" sedimentation basin for
vanadium-bearing liquor.
Same as current use except for the
storage of sand tailings.
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3. Clarified blue liquor is pumped from Pond No. 3 to
the head-end of the vanadium extraction circuit.
4. Vanadium raffinate is discharged to Pond No. 1.
There is sufficient flexibility built into the pumping system
to transfer liquid between any two ponds, including the two ponds
which are in standby condition.
Until the weekend of August 27-28, 1966, Pond No. 2 was
used for the storage and retention of slime tailings and
vanadium raffinate. At that time, the discharge of repulped
sand tailings was diverted from Pile No. 2 to this pond. This
was an attempt to seal the bottom of Pond No. 2 with ore solids;
thereby stopping the seepage into the Cheyenne River at the base
of the bank. The resultant mass of sand tailings stored in this
area rises above the original elevation of the pond surface.
Based on visual observations, the tailings appear to be drifting
toward Highway 18 and down the river bank with perhaps some
level of entry into the Cheyenne River. This was anticipated
when it was noted in the report on the 1966 study that "storage
of sand tailings in Pond No. 2 does present this somewhat un-
desirable feature of placing the sand directly on the bank of the
Cheyenne River."
Sand tailings Pile No. 1 is contiguous with Cottonwood
Creek for a distance of several hundred feet (conservatively
16
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estimated). Therefore, there is undoubtedly some loss of
solids to the creek as the result of errosion during a period
of high runoff and wind transport. Although the bulk of sand
tailings Pile No. 2 is located at much higher elevation than
the channel of Cottonwood Creek, there appears to be sloughing
of material from the pile onto the flood plain. In essence,
sand tailings from the inactive piles are probably reaching
the Cheyenne River with subsequent transport downstream into
Angostura Reservoir.
17
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V. PREVIOUS WATER QUALITY STUDIES
Short-term field studies to monitor water quality condi-
tions in the Cheyenne River and Cottonwood Creek have been con-
ducted on five occasions since the initial 1957 post-operational
study; October 17-18, 1962; August 6-7, 1964; September 7-9,
1966; early December, 1967; August 15, 1968. These have been
cooperative investigations between the South Dakota State De-
partment of Health and the Environmental Protection Agency'3'.
For all studies, the radiochemical analyses were performed in
EPA laboratories. In the case of 1966 study, water and bottom
sediment sampling was a cooperative undertaking. State personnel
were solely responsible for sample collection in the other
studies. A list of the stations at which water and bottom sedi-
ment samples have been collected in the course of these studies
is given in Table III.
The results of the physical and chemical analyses of water
samples are summarized in Tables IV and V. Similar data for
the seepage samples collected during the 1966 study are pre-
(a) Organizational predecessors of the Office of Water Programs,
Environmental Protection Agency. That is, the U.S. Public
Health Service {Division of Water Supply and Pollution Con-
trol) , the Federal Water Pollution Control Administration
and the Federal Water Quality Administration.
18
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TABLE III CHEYENNE RIVER AND COTTONWQOD CREEK SAMPLING STATIONS
Station Description
1 Cheyenne River just upstream from the Highway 18 bridge outside of Edgemont.
2 Cottonwood Creek at the pedestrian bridge; 200 feet above sand tailings Pile
No. 1 and just south of the fence that forms the south boundry of mill property.
3 Cottonwood Creek several hundred feet upstream from its confluence with the
Cheyenne River; downstream from sand tailings Pile No. 2.
4 Cheyenne River between the Cottonwood Creek confluence and Pond No. 1.
5 Cheyenne River about 1.5 miles downstream from the mill.
6 Cheyenne River at the Highway 71 bridge.
7 Cheyenne River in the headwaters of Angostura Reservoir; 0.5 miles downstream
in Tepee Canyon.
8 Central portion of Angostura Reservoir.
9 Cheyenne River about 0.25 miles below Angostura Dam.
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TABLE IV DISSOLVED RADIOACTIVITY IN CHEYENNE RIVER
ro
O
Station
1 - 1962
1964
1966
1967
1968
2 - 1962
1964
1966
1967
1968
Cottonwood
Creek at the
seepage zone
adjacent to
Pond No. 7
(1968)
AND
COTTONWOOD CREEK WATER SAMPLES
Dissolved Radioactivity
Gross Alpha
(pCi/1)
12
15
9
17
Gross Beta
(pCi/1)
55
61
_ _
_
163
Radium- 2 26
(DCi/1)
0.26
0.25
0.10
0.10
____
0.26
0.10
Lead- 210
(pCi/1)
__.
0.6
0.9
_ __
0.7
Uranium
(ucr/1)
._
17
12
13
7
__
7
18
Thorium
(ucr/1)
____
N.D.
N.D.
____
0.11
18
N.D.
0.86
100-200
(a)
(a) Analytical difficulty prevented reporting of a specific concentration.
N.D. - Not detectable, i.e. net counting rate less than two standard deviations counting rate
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TABLE IV (Continued) DISSOLVED RADIOACTIVITY IN CHEYENNE RIVER
AND
COTTONWOOD CREEK WATER SAMPLES
Dissolved Radioactivity
ISJ
Station
Cottonwood
Creek at the
seepage zone
adjacent to
sand tailings
Pile No. 2
(1967)
3 - 1962
1964
1966
1967
1968
Cheyenne River
adj acent to
Pond No. 2
seepage zone
1964
1966
1967
1968
Gross Alpha
(pCi/1)
Gross Beta
(pCi/1)
48
1
14
Radium-226
(pCi/1)
Lead-210
(pCi/1)
Uranium
(uq/1)
0.60
0.26
0.50
0.10
0.27
N.D,
4.7
0.2
53
4
18
26
15
Thorium
(uq/1)
2.3
180
53
24
1.6
0.60
0.46
_
1.2
N.D.
___
550
49
64
12
_-_
5.7
5.0
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TABLE IV (Continued) DISSOLVED RAD10ACTIVITY IN CHEYENNE RIVER
M
AND
COTTONWOOD CREEK WATER SAMPLES
Dissolved Radioactivity
Station
4 -
5 _
6 -
7 .
8 -
9 _
1966
1967
1968
1962
1964
1966
1962
1964
1966
1967
1962
1966
1966
1966
Gross Alpha
(pCi/1)
- 15
11
9
20
__
5
3
5
5
3
Gross Beta
(pCi/1)
50
56
127
mmmm
101
37
51
23
29
Radium- 2 26
(pCi/1)
0.29
0.44
2.5
0.50
_ ««.*
0.44
0.30
0.40
____
0.26
0.14
0.28
Lead-210
(pCi/1)
0.2
«_.
N.D.
N.D.
___
0.1
0.1
Uranium Thorium
(uq/1) (uq/1)
10 N.D.
130
26
__ ____
8
13
19 8.5
__ ____
Q __ _
13
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TABLE V CHEMICAL AND PHYSICAL CHARACTERISTICS OF
CHEYENNE RIVER AND COTTONWOOD CREEK WATER SAMPLES
NJ
U)
Station
1 - 1962
1964
1966
1967
1968
2 - 1962
1964
1966
1967
1968
Cottonwood
Creek at the
seepage zone
adj acent to
Pond No. 7
(1968)
Dissolved
Solids
(mq/1)
3552
3098
4160
4112
Susp.
Solids
(mq/1)
28
Total
Iron
(mq/1)
36
Sulfates Nitrates
(mq/1) (mq/1)
2140
PH
7.8 - 8.0
20
2350
39
7.0
7.3
Vanadium
<100
<20
<20
<20
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TABLE V (Contined) CHEMICAL AND PHYSICAL CHARACTERISTICS OF
CHSYEHME RIVER AND COTTONWOOD CREEK WATER SAMPLES
Station
Cottonwood
Creek at the
seepage zone
adjacent to
sand tailings
Pile No. 2
(1967)
Dissolved
Solids
(mg/1)
Susp.
Solids
(mq/1)
Total
Iron
(mg/l)
Sulfates
(mq/1)
Nitrates
(mq/1)
pH
Vanadium
(uq/1)
<100
3 -
1962
1964
1966
1967
1968
5328
6286
.._
67
2400
0.29
268
6.4
6.3
<100
<20
Cheyenne River
adjacent to
Pond No. 2
seepage zone
1964
1966
1967
1968
196
3240
0.36
19500
178
6.0
6.5
<100
<20
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TABLE V (Continued) CHEMICAL AND PHYSICAL CHARACTERISTICS OF
in
Station
4 -
5 -
6 -
7 -
8 -
9 -
1966
1967
1968
1962
196'4
1966
1962
1964
1966
1967
1962
1966
1966
1966
CHEYENNE RIVER AND COTTONWOOD CREEK WATER SAMPLES
Dissolved Susp. Total
Solids Solids Iron -Sul fates Nitrates pH Vanadium
(mq/1) (mq/1) (mq/1)* ' (mq/1) (mq/1) (uq/1)
3D DO 4&X <-» mmmmmmm* mm ****** mm mm mum mm mm mm
" i
<20
3624
42 3667 1.52 7.4
3538 6
3084 r
47 1593 0.10 7.8
2664 5 ~
__ <100
824 '
1558 37
1656 2 - ~ ^ ~
looo 3 ** «-... ____ __ __ _
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sented in Table VI. Although data for the 1962, 1964, and 1966
studies were the subject of a previous report, these data are
included herein to maintain continuity and to present the com-
plete historical record, particularly for comparative purposes.
As shown in Table IV seepage into Cottonwood Creek re-
sults in significant degradation of water quality. The specific
reductions in chemical, physical and radiological quality were
the following:
1. Significant increases in the concentration of dissolved
gross alpha and beta radioactivity, radium-226, urani-
um, and lead-210. The maximum concentrations of
radium-226 and uranium were observed in 1964. These
values, 550 pg/1 of uranium and 24 pCi/1 of radium-
226 were approximately 30 and 100 times the respective
background levels.
2. Increases in the dissolved solids and total iron (dis-
solved) concentrations.
3. pH decrease.
4. Discoloration to the extent that the creek has been
described as "running red" on occasion. This was con-
sidered to be attributable to a chemical reaction be-
tween the natural water and the iron-bearing seepage.
26
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TABLE VI PHYSICAL AND RADIOLOGICAL CHARACTERISTICS OF SEEPAGE SAMPLES
NJ
Dissolved Radioactivity
Description
Seepage from
bank of Cotton-
wood Creek
adjacent to
Sand Tailings
Pile No. 2
Seepage from
bank of Cheyenne
River upstream
from Pond No. 1
Gross
Alpha
(pCi/1)
Gross
Beta
(pCi/1)
Radium-226
(pCi/1)
148
187
32
35
342
1.4
Lead-210
(PCi/1)
0.8
0.4
Uranium
(ocr/1)
Dissolved
Solids
(mg/1)
175
8212
89
21,800
6.3 to
6.7
5.7
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Presumably, iron-bearing precipitate was formed which
gave the stream a red to reddish-brown appearance when
suspended and transported in the liquid phase.
Although the flow in Cottonwood Creek is intermittent in nature
upstream from the mill, seepage or a combination of seepage and
spring flow apparently maintain flow in the creek throughout
the reach on mill property. Intermittent flow appears to be
the reason for the finding of maximum concentrations during the
1964 study. There was no observable flow upstream from the see-
page zone in 1964 - the only study period for which such a con-
dition was noted. Correspondingly, the differences in concentra-
tion increases indicated by the five studies are considered to be
more a function of specific flow conditions and the dilution
provided rather than differences in seepage flow or quality.
Several factors indicated the process and retention ponds
were a major source of the seepage entering Cottonwood Creek:
the extension of the zone of active seepage to bank height(s)
substantially above the water surface, accumulation of reddish-
brown deposits in the seepage fcone considered to be indicative
of high iron content in the seepage, and the physical and
radiological characteristics of the seepage samples. The high
radium-226 and uranium concentrations (Table VI) low pH, and
28
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implied high iron content of the seepage samples were consis-
tent with the physical and chemical composition of the vanadium
raffinate and vanadium-bearing liquors held in the ponds. These
ponded liquors were characterized by low pH values (2.0 to 2.5),
dissolved radium-226 concentrations in the range of 60 to 300
pCi/1, and dissolved iron concentrations in excess of 500 mg/1.
Another possible source of seepage in 1966 was drainage
from sand tailings Pile No. 2 since the pumping of repulped
tailings (50% slurry) was terminated only two weeks before the
study. Moreover, mill personnel believed that as far as bulk
flow into the creek was concerned, an underground spring rather
than pond seepage or tailings pile drainage was the causative
agent. If an underground spring is responsible for sustained
flow in the creek, the water quality conditions in the creek in-
dicate that the spring flow is contaminated by pond seepage.
The adverse effect of seepage from Pond No. 2 into the
Cheyenne River was the unsightly discoloration of the stream
bed at the base of the bank and for some distance downstream.
Although the 1966 water samples from this location showed in-
creased radioactivity levels (Table iv) , the results were
judged to be representative of partially diluted seepage perco-
29
-------
lating up through the stream bed; not stream quality. These
samples were collected from a channel of flowing water adjacent
to the dike, but separated from the main channel by a sand bar.
As such, the indicated change in radiological water quality rep-
resented only a minute fraction of the Cheyenne River flow at
this site.
Seepage into the Cheyenne River at a point just upstream
from Pond No. 1 contained concentrations of dissolved radium
and uranium in excess of surface water background levels (Table
VT) . However, the concentrations were much lower than those
found in the seepage flowing into Cottonwood Creek - an order
of magnitude less for radium-226. The seepage had no effect
on Cheyenne River water quality because the observed flow was
only trickle.
Downstream from the confluence with Cottonwood Creek, the
Cheyenne River showed recovery to nominal or background levels
in the vicinity of Station 5 or 6. Consistent with the find-
ings for Cottonwood Creek, the maximum results for dissolved
radium-226 and uranium concentrations in the Cheyenne River were
observed in the 1964 study -2.5 pCi/1 of radium-226 and 130 ug/1
of uranium. This is in contrast to the results of the other
studies which have shown radium-226 and uranium concentrations
30
-------
in the river to be only slightly in excess of background
levels. For example, with exception of the 2.5 pCi/1 result,
the maximum radium-226 concentration was 0.5 pCi/1 at Station
5 during the 1966 study.
Chemical and radioactivity results for bottom sediment
samples are presented in Table VII. Although the vanadium re-
sults indicated somewhat higher levels in the seepage zone of
Cottonwood Creek, the finding was not considered definitive in
terms of providing positive identification of vanadium liquors
as a major source of seepage. This was due to the limited num-
ber of samples analyzed and the relative insensitivity of the
analytical procedure. Similarly, the iron data did not provide
a quantitive-type illustration of the bank and channel discolora-
tion. This was, in part, attributable to the method of sample
collection. Sediment samples were collected in a manner such
that they were representative of the average condition at each
location and were not limited to the collection of obviously
discolored material (unless the discoloration was distributed
across the channel width).
Radium-226 and uranium concentrations in the bottom sedi-
ments showed the same contamination pattern as that exhibited
by the corresponding results for water samples. That is, the
31
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TABLE VII RADIOACTIVITY CHEMICAL CONTENTS OF
to
BOTTOM SEDIMENTS
FROM THE
CHEYENNE RIVER AND COTTONWOOD CREEK
Station
1
2
- 1962
1964
1966
1967
1968
- 1962
1964
1966
1967
1968
Gross Alpha
(pCi/g)
7
5
70
7
Gross Beta
(pCi/g)
37
18
__
195
41
Radium- 2 26
(pCi/g)
1.4
1.2
__ _
1.2
__ _
4.4
2.0
2.3
Uranium
(uq/q)
2.4
___
0.6
_____
5.6
2.2
Vanadium
(uq/q)
___
<50
_____
___
<50
60
Iron
(uq/q)
i
____
4720
_____
_____
>2500
8180
Cottonwood
Creek at the
seepage zone
adjacent to
Pond No. 7
(1968)
7.9
2.7
<50
9530
-------
TABLE VII (Continued) RADIOACTIVITY CHEMICAL CONTENTS OF
BOTTOM SEDIMENT FROM THE
CHEYENNE RIVER AND COTTONWOOD CREEK
Station
Cottonwood
Creek at the
seepage zone
adjacent to
sand tailings
Pile No. 2
1966
1967
Gross Alpha
(pCi/g)
Gross Beta
(pCi/g)
55
61
Radium-226
(pCj/g)
12
15
Uranium
(uq/q)
9.5
Vanadium
(pg/gl
Iron
(uq/g)
310
>2500
3 -
1962
1964
1966
1967
1968
124
55
195
61
74
12
45
31
62
6.5
8.5
190
90
>2500
6350
Cheyenne River
at base of
Pond No. 2
dike
1964
1966
1967
1968
24
1.1
1.0
1.8
1.1
9.3
1.9
0.6
<50
<50
<50
1550
>2500
1890
-------
TABLE VII (Continued) RADIOACTIVITY CHEMICAL CONTENTS OF
BOTTOM SEDIMENTS FROM THE
Station
4 -
5 -
6 -
7 -
8 -
9 -
1966
1967
1968
1962
1964
1966
1968
1962
1964
1966
1967
1962
1966
1966
1966
Gross Alpha
(pCi/g)
11
14
15
13
7
11
8
6
4
CHEYENNE
Gross Beta
(pCi/q)
33
64
25
91
24
47
31
32
17
RIVER AND COTTONWOOD CREEK
Radium- 2 26
(pCi/a)
2.9
3.7
2.7
3.9
2.7
2.1
0.9
1.7
0.9
1.7
1.5
1.3
Uranium Vanadium Iron
(uq/q) (uq/q) (uq/q)
<50 1875
2.2 <50 1970
1.6 60 3010
11 __
1.5 <50 3150
1.4 ~
<50 1075
0.9 <50 825
___ __ ____
-------
highest level of contamination occurred in Cottonwood Creek
with concentrations ranging from 12 to 74 pCi/gram for radium-
226 and 7 to 85 pg/gram for uranium (Table VII -Station 3).
These values are in comparison to background concentrations on
the order of 1.0 to 2.0 pCi of radium-226 and 1.0 to 2.0 pg of
uranium. In the Cheyenne River, the sediment concentrations
decreased to background levels in the reach between Stations 5
and 6. Radium-226 and uranium concentrations at the pedestrian
bridge across Cottonwood Creek (Station 2) were slightly greater
than background levels. A possible explanation is periodic
contamination of this location by windblown sand tailings from
Pile No. 1 (located several hundred feet downstream).
Radium-226 results for fish collected from Angostura Reser-
voir during the September, 1966, study are shown in Table VIII.
Based on a comparison with similar results for fish collected at
locations upstream from uranium mills in the Colorado River
Basin, the Angostura fish were at typical background levels.
This was consistent with the background level of dissolved ra-
dium-226 in Angostura Reservoir.
35
-------
TABLE VIII RADIUM-226 CONCENTRATIONS IN ANGOSTURA RESERVOIR FISH
SEPTEMBER, 1966
Radium-226 in Flesh
Species
(a)
Black Crappie
(3)
Bluegill
(6)
Ringed Perch
(48)
Live Weight of
Composite Sample
(gram)
105
151
727
pCi/gram
Ash Weight
0.06
0.04
0.47
(b)
pC i/kilogr am
Wet Weight
0.75
0.52
5.3
(b)
Radium-226 in Bone
pCi/gram
Ash Weight
0.08
0.07
0.10
U)
(a) Number in parentheses refers to the number of fish in the composite sample
(b) Probably high as the result of the fusion of the sample with the porcelain dish
during dry ashing.
-------
VI 1971 FIELD STUDY
The July 1971 field study was conducted by personnel of the
Environmental Protection Agency (Radiological Activities Sec-
tion, Office of Water Programs) in cooperation with the South
Dakota State Department of Health. Sampling extended over the
five day period of July 26-30.
STUDY PROCEDURES
Sampling stations on the Cheyenne River and three tribu-
taries, Cottonwood Creek, Hat Creek, and Cascade Springs, are
listed in Table IX, Water samples were collected daily at
the Cheyenne River and Cottonwood Creek stations (excluding
Stations 9 and 10) whereas single grab samples were collected
from Hat Creek and Cascade Springs. Bottom sediment samples
were collected once at each station during the study period.
Staff gages (rated with a pygmy current meter) were used
to meter the flow in Cottonwood Creek at each of the three
sampling stations. The permanent gaging stations of the U. S.
Geological Survey were used to obtain the flows in the Cheyenne
River above the Edgemont mill and downstream at the State High-
way 71 bridge. Flow in Hat Creek was also obtained from a
U.S.G.S. gaging station.
37
-------
Ul
CD
TABLE IX COTTONWOOD CREEK AM3 CHEYENNE RIVER
SAMPLING STATIONS - 1971
Station Description
1 Cheyenne River just upstream from the State Highway 18 bridge outside
of Edgemontj at the railroad bridge.
2 Cottonwood Creek upstream from mill property at the county road bridge;
off State Highway 52.
3 Cottonwood Creek at the road culvert? downstream from sand tailings
Pile Mo. 2.
4 Cottonwood Creek at confluence with the Cheyenne River.
5 Cheyenne River about 1.5 miles downstream from the mill.
6 Cheyenne River about 6 miles downstream from the mill; at Gull Hill Park,
7 Cheyenne River at ford on County Road 11.
8 Cheyenne River at State Highway 71 bridge.
9 Cheyenne River in the headwaters of Angostura Reservoir.
10 Cheyenne River below Angostura Dam.
11 Hat Creek.
12 Cascade Springs.
-------
In addition to the collection of samples at the main
stations on Cottonwood Creek and the Cheyenne River, bottom
sediment samples were also collected in the following areas:
(a) Cottonwood Creek:
Six locations between the pipeline suspension bridge
immediately upstream from sand tailings Pile No. 2
and the pedestrian footbridge. Sampling locations
were selected to assess the variations in radio-
activity concentrations throughout this previously
unsampled reach.
(b) Cheyenne River:
Along the edge of the river channel extending from
the downstream edge of Pond No. 1 for a distance of
approximately one mile downstream (seven samples).
This area was characterized by reddish-brown discolora-
tion.
Thirteen soil samples were collected from the bank and dry stream
bed adjacent to Pond No. 2.
Seepage samples were collected at four locations by ex-
cavating small collection basins in the bank proper:
(1) Cottonwood Creek just upstream from the pipeline sus-
pension bridge (at the bank-stream bed interface).
39
-------
(2) Cottonwood Creek several hundred yards upstream from
the pipeline suspension bridge (approximately six
feet above the water level in the creek).
(3) Cheyenne River just upstream from Pond No. 1 (approxi-
mately two feet above the stream water level).
(4) Cheyenne River about 1 1/2 miles downstream from the
mill (just above the stream water level).
The collection basins were allowed to flush overnight and the
samples collected the following morning with a polyethlene
beaker or glass pipette. At the base of the Cheyenne River bank
adjacent to Pond No, 2, seepage was collected from a natural
depression in the dry steam bed.
Water and bottom sediment samples were collected from
Angostura Reservoir at thirteen locations, providing complete
coverage of the impoundment. At each station, the water column
was sampled at the surface and near the bottom. Fish samples
for radiological analysis were obtained from the fish sampling
study conducted earlier in the year by the Division of Field
Investigations - Denver, Environmental Protection Agency.
To assess the chemical and radiological characteristics
of ground water in the mill environs, grab samples of well
water were collected from the Edgemont reservoir well, Edgemont
40
-------
park well, Edgemont airport well, Mines Development process
water well, an abandoned railroad well (next to Pond No. 2),
and the Cheyenne River campground well (across the river from
the mill).
SAMPLE PROCESSING PROCEDURES
Surface water samples and seepage samples were filtered on
the day of collection. Well water samples were not filtered.
All pH measurements were performed in the field or in the mill
laboratory (within a few hours of collection) with a Yellow
Springs portable meter.
Chemical and radiochemical analyses will be performed on
the daily water samples collected at the Cottonwood Creek and
Cheyenne River stations as well as 5-day composite samples.
In the case of seepage in the vicinity of Pond No. 1, analyses
will be performed on a composite sample prepared from the
samples collected on two consecutive days.
Due to the large number of samples requiring analysis,
the time required for a radium-226 determination, and the com-
plexities of preparing sediment samples for radiochemical
analysis, the quantitive data to be reported herein are largely
limited to pH, dissolved uranium, and total alpha radium (dis-
solved) for water samples. A complete compilation of the
41
-------
radioactivity results will be the subject of a supplemental
report.
Spectrographic metals analysis of the seepage samples was
performed by the EPA Analytical Duality Control Laboratory,
Cincinnati, Ohio.
RESULTS
Flows in Cottonwood Creek during the study period averaged
0.1 cfs at the upstream stations, 0.4 cfs at the road culvert,
and 0.5 cfs at the mouth. The small increase between the
culvert and the mouth might represent the drainage into the
creek from the abandoned railroad well. However, the small
difference is within the limits of metering error. Flow in the
Cheyenne River was about 5 cfs at the upstream railroad bridge
and approximately 132 cfs at the State Highway 71 bridge. The
increase was largely attributable to Hat Creek (100 cfs) and
Cascade Springs. All other tributaries were dry.
The limited results on water quality conditions in Cotton-
wood Creek and the Cheyenne River are presented in Table X.
These data show the same pattern of water quality degradation
as observed in past studies. That is, due to seepage, the
dissolved uranium concentration in Cottonwood Creek approached
a level in excess of 10X the natural level. In contrast, there
42
-------
Station
1
2
3
4
5
6
7
8
9
10
11
12
TABLE X DISSOLVED RADIOACTIVITY
IN THE
CHEYENNE RIVER, COTTONWOOD CREEK,
HAT CREEK, AND CASCADE SPRINGS
Dissolved Radioactivity'5'
Total Alpha
Radium Uranium Thorium
(pCi/1)
0.11
0.67
0.75
0.09
0.17
0.32
0.11
0.10
0.14
0.11
0.08
0.08
Uranium
(ug/1)
16
26
147
177
28
14
19
14
10
12
24
5
4
3
2
1
7
5
3
3
3
pH
8.
7.
6.
6.
7.
8.
7.
7.
0
0
4
7
8
1
9
9
- 8
- 7
- 6
- 7
- 8
- 8
- 8
- 8
7.7
6.8
.2
.1
.8
.1
.0
.4
.2
.2
(a) With the exception of single grab samples for Stations 11 and 12, the values refer
to 5-day composite samples.
-------
was a negligible concentration increase in the Cheyenne River
downstream from the mill. This finding is consistent with the
flow data which showed the dilution capacity afforded by the
Cheyenne River was on the order of 50 times.
The total alpha radium analysis is commonly used as a
quick guide to the probable radium-226 concentration. However,
the analysis is not particularly sensitive and should not be
depended upon completely to demonstrate small differences.
For example, the results for the total alpha concentrations in
the Cottonwood CreeTc samples indicated essentially no increase
in the dissolved radium-226 concentration in the reach receiv-
ing seepage, a finding which was not consistent with the urani-
um results. However, radium-226 determinations on the composite
samples for Stations 2 and 3 showed dissolved concentrations of
0.26 and 3,1 pCi/1, respectively. This was in complete accord
with the uranium results.
By visually inspecting the reach of Cottonwood Creek ex-
tending from the pipeline bridge to the pedestrian bridge, the
occurence of seepage from mill ponds was observed to extend
at least as far upstream as a point opposite the north edge of
Pond No. 7. In this area, the high bank was observed to be
moist {and "dripping") to heights of over six feet above the
water surface. Further, pooled sections of the creek were
44
-------
observed to have the same yellowish-green color as the seepage
samples. Quantitative support for the conclusion that the mill
ponds were a significant source of seepage was the high concen-
trations of molybdenum (5 to 25 mg/1) in the seepage samples.
Molybdenum is a mill byproduct and dissolved concentrations in
the ponds ranged from 20 to 75 mg/l^aJ. The seepage samples
also showed traces of iron and manganese «2 mg/1) and, in one
case, chromium, nickel and lead concentrations in the range of
5 to 25 mg/1.
Areas of reddish-brown (reddish-orange) channel discolora-
tion were observed in Cottonwood Creek as far upstream as the
pedestrian bridge and on both sides of the channel. This
suggested the possibility that natural sources (springs, etc.)
were partly responsible for the channel discoloration effect.
However, the magnitude of discoloration within the mill proper
indicates that seepage intensifies the problem and the overall
situation is undoubtedly much worse than it would be in the
absence of seepage from the ponds.
Based on the discoloration of the dry stream channel
adjacent to Pond No. 2, seepage from the pond has not been corn-
fa) Analysis of samples collected from the ponds.
45
-------
pletely stopped despite the fact that the pond is an inactive
repository for uranium sand tailings. The pond was not com-
pletely dry but contained a small pool of water in the end
nearest the mill. Presumably, drainage from the abandoned rail-
road well is entering the pond.
The impact of seepage in the area of Pond No. 1 was sub-
stantially greater than that observed in 1966. During the
1966 study, the seepage caused only a small localized effect.
However, in this most recent study, the impact of the seepage
as measured by channel discoloration was observed for a dis-
tance of over one mile downstream. It was not determined
whether this was the result of differences in Cheyenne River
flow or increased seepage flow.
Dissolved uranium concentrations in the Angostura Reser-
voir samples were at natural background levels. The overall
concentration range was 6 to 13 ug/1 with no significant
differences between the surface and "bottom1,1 samples.
46
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ADDENDUM I
TO
"EVALUATION OF THE IMPACT OF THE
MINES DEVELOPMENT, INC. HILL
ON
WATER QUALITY CONDITIONS IN THE CHEYENNE RIVER"
DISSOLVED MERCURY IN CHEYENNE RIVER,
COTTONWOOD CREEK, AND SEEPAGE SAMPLES-
Dissolved Hg
Station (uq/1)
1. Cheyenne River just upstream from the State 2.1
Highway 18 bridge outside of Edgemont.
2. Cottonwood Creek upstream from mill property 3.5
at the county road bridge; off State Highway
52.
3. Cottonwood Creek at the road culvert; down- 4.2
stream from sand tailings Pile No. 2.
4. Cottonwood Creek at confluence with the 1.8
Cheyenne River.
5. Cheyenne River about 1.5 miles downstream 0.6
from the mill.
6. Cheyenne River about 6 miles downstream from 3.0
the mill; at Gull Hill Park.
7. Cheyenne River at ford on County Road II. 3.2
8. Cheyenne River at State Highway 71 bridge. 0.8
9. Cheyenne River in the headwaters of Angostura 1.8
Reservoir.
Seepage into Cottonwood Creek just upstream from the 1.0
pipeline suspension bridge.
Seepage into Cottonwood Creek several hundred yards 2.3
upstream from the pipeline suspension bridge.
-------
Dissolved Hg
Station (ug/1)
Seepage into the Cheyenne River just upstream from 2.2
Pond No. 1.
NOTE: Analyses performed on field-filtered samples by the
Division of Field Investigations - Cincinnati, Environmental
Protection Agency. With the exception of the seepage samples,
the dissolved mercury values refer to 5-day composite samples.
-------
ADDENDUM II
TO
"EVALUATION OF THE IMPACT OF THE
MINES DEVELOPMENT, INC. MILL
ON
WATER QUALITY CONDITIONS IN THE CHEYENNE RIVER"
1. Page 1: In the fourth line, change the superscript ]_/
to a/. Similarly, change the footnote designation from
I/ to a/.
2. Page 6: Insert the superscript 1 after the last word on
this page.
3. Page 7, Item 2: "Increases11 should be changed to "In-
creased".
4. Page 10, Table I: Insert superscripts 2,3,4, & 5 after
U. S. Public Health Service, Federal Radiation Council,
International Commission on Radiological Protection (ICRP),
and the National Committee on Radiation Protection (NCRP),
respectively.
5. Page 11: The following paragraph is to be added after the
second paragraph:
Despite the fact that the increased radioactivity
concentrations in Cottonwood Creek and the Cheyenne River
do not pose a public health hazard, steps should be taken
to eliminate or substantially reduce the radioactivity of
the seepage entering Cottonwood Creek and the Cheyenne
River. This is consistent with a policy of minimizing
the release of radioactive materials to man's environment
insofar as is practicable. That is, the waste management
program should be the best available provided the specific
practices are technologically feasible and economically
reasonable. Moreover, elimination of the aesthetically
displeasing discoloration of bank and channel areas re-
quires curtailment of the seepage from the retention ponds
(or substantial reduction thereof).
In the fourth line of the third paragraph, Insert the super-
script a/ after "... high-radioactivity solids,.11. This
change is accompanied by the following footnote at the bottom
of the page:
-------
a/ A Sample of drained sands from Pile No. 2
collected during the 1966 study contained
230 pCi of radium-226 per gram dry weight.
Page 26: In the second sentence, insert the superscript
6 after "report".
A section listing references, Section VII, should be added
as the last page of the report and noted in the Table of
Contents.
VII. REFERENCES
1. Tsivoglou, E. C.f Kalda, D. C.» and Dearwater, J. R.f
"The Resin-In-Pulp Uranium Extraction Process. Mines
Development Company, Edgemont, South Dakota", Technical
Report W62-17, U. S, Public Health Service, R. A. Taft
Sanitary Engineering Center, Cincinnati, Ohio (1962)
2. U. S. Public Health Service, "Drinking Water Standards-
1962", Publication No. 956.
3, Federal Radiation Council, "Background Material for
the Development of Radiation Protection Standards",
Staff Report No. 2 (September, 1961).
4. International Commission on Radiological Protection,
"Recommendations of the International Commission on
Radiological Protection, as Amended 1959 and Revised
1962", ICRP Publication No. 6, Pergamon Press, New
York, New York (1964).
5. National Committee on Radiation Protection,"Maximum
Permissible Body Burdens and Maximum Permissible Con-
centrations of Radionuclides in Air and Water for
Occupational Exposure", Handbook 69 (including Adden-
dum I), U. S. Department of Commerce, National Bureau
of Standards (August 1963).
6. Federal Water Pollution Control Administration, "Evalua-
tion of the Radioactivity Levels in the Vicinity of the
Mines Development, Inc. Uranium Mill at Edgemont, South
Dakota, 1966", Technical Advisory and Investigations
Branch, Physical and Engineering Sciences Section,
Cincinnati, Ohio (May 1967).
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