ENVIRONMENTAL EVALUATION
OF
MINES DEVELOPMENT, INC. URANIUM & VANADIUM
MILLING OPERATIONS
AT
EDGEMONT, SOUTH DAKOTA
TECHNICAL SUPPORT BRANCH
SURVEILLANCE AND ANALYSIS DIVISION
U. S. ENVIRONMENTAL PROTECTION AGENCY
REGION VIII
APRIL, 1973
-------
mi.
SUMMARY
Since the Mines Development, Inc., uranium mill located at Edgemont,
South Dakota, began commercial operation in 1956, the resultant impact of
waste management practices on environmental radiation levels has been the
subject of several State and Federal studies. The first set of post-
operational samples were collected during June, 1957. During the latter
part of July, 1957, an intensive in-plant study was conducted to characterize
the mill process and liquid effluents. Water quality studies conducted
during September, 1966, and July, 1971, showed that process and waste
liquors were being lost by seepage from mill ponds and entering surface
waters - Cottonwood Creek and the Cheyenne River. Soil and bottom sediment
samples collected during the 1971 study confirmed the loss of unstabilized
sand tailings to the water environment by wind and water erosion.
Water quality degradation attributable to mill operations was considered
at the Environmental Protection Agency - State of South Dakota Conference in
the Matter of Pollution of the Navigable Waters of Western South Dakota (held
in Rapid City, South Dakota on October 19-21, 1971). Based principally on
the findings of the 1971 field study, the Conferees put forth recommendations
calling for (1) curtailment of pond seepage, (2) development of a plan pro-
viding for the stabilization and ultimate disposal of sand tailings, and
(3) the establishment of a water quality monitoring program (State in cooper-
ation with EPA) to monitor and document the progress of abatement actions.
The mill was revisited October 3, 1972, to discuss the efforts undertaken
by Mines Development, Inc., to abate radiological pollution and to assess the
progress achieved in the year following the 1971 Conference. To eliminate
seepage from mill ponds, the Company had instituted a program of operating
the ponds at lower fluid levels and systematically abandoning old ponds.
Although visual observations indicated that some reduction in the seepage
flow to Cottonwood Creek had been achieved, water quality monitoring data
for the period of May through September, 1972, showed no significant
improvement.
As the result of the mill visit, it was concluded that little progress
had been made on the crucial issue of sand tailings stabilization and
ultimate disposal. Aside from two limited experiments to test potential
stabilization procedures, no positive actions had been taken to prevent the
loss of sand tailings to the environment by wind and water erosion. At the
Pond No. 2 disposal area, sand tailings have drifted through the site Perimeter
fence and are migrating down the Cheyenne River bank, toward the State Highway,
and into the yard of a single family dwelling adjacent to the disposal site.
A soil sample collected from a residential area to the east of inactive sand
tailings pile No. 1 contained a high concentration of radium-226 indicative
of wind transport from this pile. To eliminate these situations and prevent
additional off-site contamination, a corrective action program should be
implemented without delay.
- i -
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TABLE OF CONTENTS
Page
SUMMARY i
INTRODUCTION 1
1971 FIELD STUDY . 4
Surface Waters 7
Well Waters 15
Seepage 17
Bottom Sediment and Soil 21
Fish-Angostura Reservoir 30
PROGRESS TOWARD POLLUTION ABATEMENT 32
Liquid Waste Management 32
Uranium Sand Tailings 35
WATER QUALITY MONITORING PROGRAM 44
REFERENCES 55
APPENDIX A A-l
- ii -
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LIST OF TABLES
Page
I SURFACE WATER SAMPLING STATIONS, CHEYENNE RIVER AND
TRIBUTARIES - 1971 5
II STREAM FLOWS 8
III RADIOACTIVITY IN CHEYENNE RIVER, COTTONWOOD CREEK, CASCADE CREEK,
AND HAT CREEK WATER SAMPLES 9
IV RADIUM-226 AND URANIUM IN CHEYENNE RIVER AND COTTONWOOD CREEK
WATER SAMPLES 10
V DISSOLVED RADIOACTIVITY IN ANGOSTURA RESERVOIR 12
VI RADIOACTIVITY IN WELL WATER SAMPLES 16
VII DISSOLVED RADIOACTIVITY IN SEEPAGE SAMPLES 18
VIII RADIOACTIVITY IN MILL PONDS 20
IX RADIOACTIVITY CONTENT OF BOTTOM SEDIMENTS FROM COTTONWOOD CREEK,
CHEYENNE RIVER, AND ANGOSTURA RESERVOIR 23
X RADIOACTIVITY CONTENT OF SOIL SAMPLES COLLECTED FROM THE CHEYENNE
RIVER BANK ADJACENT TO THE POND NO. 2 STORAGE AREA 29
XI RADIUM-226 AND URANIUM IN ANGOSTURA RESERVOIR FISH, AUGUST, 1971 31
XII MILL PROCESS AND RETENTION PONDS 33
XIII EDGEMONT MONITORING PROGRAM, CHEYENNE RIVER AT STATE HIGHWAY 18
BRIDGE UPSTREAM OF MINES DEVELOPMENT, INC., URANIUM MILL .... 45
XIV EDGEMONT MONITORING PROGRAM, COTTONWOOD CREEK UPSTREAM OF MINES
DEVELOPMENT, INC., URANIUM MILL AT COUNTY ROAD BRIDGE; JUST EAST
OF STATE HIGHWAY 52 47
XV EDGEMONT MONITORING PROGRAM, COTTONWOOD CREEK DOWNSTREAM OF
SEEPAGE FROM MINES DEVELOPMENT, INC., URANIUM MILL 49
XVI EDGEMONT MONITORING PROGRAM, CHEYENNE RIVER AT RED CANYON
APPROXIMATELY TWO MILES DOWNSTREAM OF THE CONFLUENCE WITH
COTTONWOOD CREEK 51
- iii -
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LIST OF FIGURES
Page
I LOCATION MAP 2
II ANGOSTURA RESERVOIR SAMPLING STATIONS 6
III COTTONWOOD CREEK BOTTOM SEDIMENT SAMPLING STATIONS 22
IV SAND TAILINGS PILE NO. 1 ALONG STRETCH OF COTTONWOOD CREEK,
OCTOBER, 1972 27
V SOIL SAMPLES COLLECTED FROM THE BANK IN THE VICINITY OF POND
NO. 2 28
VI POND NO. 2 SAND TAILINGS STORAGE AREA STABILIZATION TEST PLOT,
OCTOBER, 1972 37
VII SAND TAILINGS PILE NO. 1 STABILIZATION TEST PLOT, OCTOBER, 1972 . 38
VIII VIEW FROM STATE HIGHWAY 18 ACROSS POND NO. 2 SAND TAILINGS
STORAGE AREA, OCTOBER, 1972 40
IX VIEW OF MARTINEZ PROPERTY SHOWING ENCROACHMENT OF SAND TAILINGS
FROM POND NO. 2 AREA, STATE HIGHWAY 18 IN IMMEDIATE BACKGROUND -
IDENTIFIED BY YELLOW ROAD SIGN AND BRIDGE, OCTOBER, 1972 .... 41
X VIEW FROM STATE HIGHWAY 18 ACROSS POND NO. 2, SEPTEMBER, 1966 . . 42
- iv -
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INTRODUCTION
Field studies to quantify the impact of waste disposal practices at
the Mines Development, Inc., uranium mill on the quality of Cottonwood
Creek and the Cheyenne River have been conducted on several occasions by
Federal and State personnel - the most recent field study occurring in
July of 1971. The findings of these efforts were the basis for the
Environmental Protection Agency report(') presented at the Conference in
the Matter of Pollution of the Navigable Waters of Western South Dakota
(held in Rapid City, South Dakota, on October 19-21, 1971). Consistent
with the Environmental Protection Agency recommendations calling for
improvement in waste management practices, the Conferees set forth the
following requirements:
1. "By January 1, 1973, sealed storage for liquid uranium and
vanadium mill wastes at Mines Development, Inc., at Edgemont,
South Dakota, shall be provided to eliminate the seepage into
Cottonwood Creek and the Cheyenne River. A progress report
shall be made by Mines Development, Inc., and the State to
the Conferees by July 1, 1972."
2. "A plan providing for the stabilization and ultimate disposal
of sand tailings from Mines Development, Inc., shall be
developed by February 15, 1972. One alternative for ultimate
disposal that should be investigated is storage in the excavated
portions of the open-pit uranium mine operated by Mines Develop-
ment, Inc."
3. "By July 1, 1972, monitoring stations shall be established on
Cottonwood Creek (at the mouth) and the Cheyenne River (down-
stream from the Mines Development, Inc., mill) by the State of
South Dakota in cooperation with the Environmental Protection
Agency to determine the extremes in chemical and radioactivity
concentrations as well as the annual average radioactivity."
A map of the area covered by the water quality studies is shown in
Figure 1.
The objectives of this report are three-fold:
1. To present all the analytical results from the July 1971 water
quality study and discuss the significance thereof. As noted
in the Conference report, only a limited number of the 1971
results were available at the time of the Conference.
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FIGURE I
LOCATION MAP
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NEBRASKA STATE LINE
9 MILES
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2. Discuss the efforts expended and the progress achieved by
Mines Development, Inc., in the abatement of seepage from
mill ponds and the stabilization of on-site tailings piles.
3. Present the initial results of the "Edgemont" water quality
monitoring program (five month period of May through September,
1972).
- 3 -
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1971 FIELD STUDY
Detailed descriptions of the July 1971 field study and associated
sample processing procedures were presented in the Enforcement Conference
report. The study involved the collection of surface water, well water,
seepage, soil, and bottom sediment samples. Summarized briefly, surface
water sampling stations were established on the following:
Water sampling stations for the Cheyenne River and three tributaries are
listed in Table I and are shown in Figure I. Angostura Reservoir stations
are shown in Figure II.
The collection frequency for water samples from Cottonwood Creek and
the Cheyenne River was daily over the 5-day study period at all stations
except Stations 9 and 10. At these latter two stations as well as at the
stations on at Cascade Creek and Hat Creek, grab samples were collected only
once during the study. In the case of Angostura Reservoir, grab water
samples were collected at the surface and near the bottom of the water
column at each station.
Flow data for the study period are summarized in Table II. Flow in
Cottonwood Creek increased from an average 0.1 cfs upstream of the mill
(Station 2) to 0.4 cfs at the road culvert and 0.5 cfs at the mouth. The
approximate 0.3 cfs increase between Station 2 and the road culvert was
largely due to overflow from the mill water tower and seepage from mill
ponds. The small flow increase between the culvert and the creek mouth
might represent the drainage into the creek from an abandoned railroad
well. However, this small difference was within the limits of the meter-
ing procedure employed for flow measurements. Flow in the Cheyenne River
was about 5 cfs at the upstream railroad bridge (Station 1) and approximately
132 cfs at the State Highway 71 Bridge. The increase was largely attrib-
utable to Hat Creek (100 cfs) and Cascade Creek. All other potential
tributaries were dry.
Cheyenne River
Cottonwood Creek
Hat Creek
Cascade Creek
Angostura Reservoir
7 Stations
3 Stations
1 Station
1 Station
13 Stations
- 4 -
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1
2
3
4
5
6
7
8
9
10
11
12
TABLE I
SURFACE WATER SAMPLING STATIONS
CHEYENNE RIVER AND TRIBUTARIES - 1971
Description
Cheyenne River just upstream of the State Highway 18 Bridge
outside of Edgemont; at the railroad bridge.
Cottonwood Creek upstream of mill property at the county
road bridge; off State Highway 52.
Cottonwood Creek at the mill road culvert; downstream of
sand tailings pile No. 2.
Cottonwood Creek at the confluence with the Cheyenne River.
Cheyenne River about 1.5 miles downstream of the mill.
Cheyenne River about six (6) miles downstream of the mill;
at Gull Hill Park.
Cheyenne River at ford on County Road 11.
Cheyenne River at State Highway 71 Bridge.
Cheyenne River in the headwaters of Angostura Reservoir.
Cheyenne River below Angostura Dam.
Hat Creek at State Highway 71 Bridge.
Cascade Creek near Brainerd Indian School.
- 5 -
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FIGURE II
ANGOSTURA RESERVOIR SAMPLING STATIONS
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Surface Waters
Water quality results for the Cheyenne River, Cottonwood Creek,
Cascade Creek, and Hat Creek are summarized in Tables III and IV. In the
case of stations for which composite samples were prepared, complete radio-
chemical analysis was performed only on the composite sample (Table III)
with analysis of the daily samples limited to dissolved radium-226 and
uranium (Table IV). With the exception of the radium-226 results for
Station 2, there was excellent agreement between the average results
calculated for the daily samples and the corresponding results for the
composite samples. Based on the separate results for the five (5) samples
collected at Station 2, the background concentration of dissolved radium-226
in Cottonwood Creek was approximately 0.10 pCi/1 instead of the 0.26 pCi/1
indicated by composite sample analysis.
The radioactivity results for the Cottonwood Creek stations showed a
significant degradation in quality as the creek traverses mill property.
The level of dissolved radium-226 increased 30-fold from 0.10 pCi/1 upstream
of the mill to 3.1 pCi/1 at the road culvert. Similarly, dissolved uranium
increased from 26 ug/1 to 147 ug/1. Field pH measurements also showed a
small reduction in pH in the reach receiving seepage from mill ponds - 7.0
to 7.1 upstream at Station 2 as compared to 6.4 to 6.8 at the road culvert.
In contrast to the degradation of water quality in Cottonwood Creek,
there was no detectable change in the radiological water quality of the
Cheyenne River as the result of pond seepage. Concentrations of radium-226
and uranium at Station 5, approximately 1.5 miles below the confluence with
Cottonwood Creek, were comparable to those at the upstream or baseline station
(Station 1). This is consistent with results of mass balance calculations.
Even by assuming complete conservation of the pollutants in the dissolved
form (i.e., no loss by chemical precipitation, adsorption, etc.), the
calculated concentrations for Station 5 for a complete mixing condition are
not dramatically different than background levels - calculated values of
0.5 pCi/1 and 31 ug/1 of radium -226 and uranium, respectively. The fact
that the mass balance approach is not totally accurate is undoubtedly
attributable to several factors, including the possible transition of
radium-226 and uranium from the dissolved to solid state. Dissolved
radium-226 results for Stations 7 and 8 on the Cheyenne River indicated
a contributing source in this reach as the average concentration increased
from 0.25 pCi/1 to 0.34 pCi/1 (Table IV). Apparently, the source of this
small increase was the small tributary, Cascade Creek. A single grab sample
from this stream contained 1.7 pCi/1 of dissolved radium-226.
Water quality data for Angostura Reservoir (Table V) showed no
detectable impact of radioactivity-bearing seepage from the mill on dissolved
radioactivity in the reservoir. Based on the collective analysis of the
separate results, the average dissolved concentrations of radium-226 and
uranium were 0.17 pCi/1 and 8 ug/1, respectively. These values are comparable
- 7 -
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TABLE II
STREAM FLOWS
Station
Date
Flow(cfs)
1
- Cheyenne River
7/26
6.6
upstream of mill
7/27
3.8
7/28
4.4
7/29
5.6
7/30
4.4
Avg. - 5.0
2
- Cottonwood Creek
7/26
0.14
upstream of mill
7/27
0.12
7/28
0.12
7/29
0.05
7/30
0.07
Avg. - 0.10
3
- Cottonwood Creek
7/26
0.64
at mill road
7/27
0.12
culvert
7/28
0.29
7/29
0.29
7/30
0.29
Avg. - 0.40
4
- Cottonwood Creek
7/26
0.62
near mouth
7/27
0.62
7/28
0.39
7/29
0.62
7/30
0.50
Avg. - 0.53
8
- Cheyenne River
7/26
148
at State Hi ghway
7/27
137
71 Bridge
7/28
129
7/29
127
7/30
122
Avg. - 132
11
- Hat Creek
7/26
100
Method of Measurement
Permanent USGS Gage
Staff Gage
Staff Gage
Staff Gage
Permanent USGS Gage
Permanent USGS Gage
- 8 -
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TABLE III
RADIOACTIVITY IN CHEYENNE RIVER, COTTONWOOD CREEK,
CASCADE CREEK, AND HAT CREEK WATER SAMPLES
Sol ids Dissolved Radioactivity
Station
Suspended
(mg/1)
Dissolved
(mg/1)
Total Alpha
Radium (pCi/1)
Radium-226
(pCi/1)
Urani um
(uq/1)
Total Alpha
Thorium (pCi/1)
Thorium-natural
(uq/1)
£H
1 -
Composi te
—
0.11
0.24
16
0.10
4
8.0 - 8.2
2 -
Composite
...
—
0.67
0.26
26
0.80
3
7.0 - 7.1
3 -
Composite
—
—
0.75
3.1
147
0.02
2
6.4 - 6.8
4 -
Composite
...
—
0.09
2.6
177
0.38
1
6.7 - 7.1
5 -
Composi te
...
...
0.17
0.32
28
0.85
7
7.8 - 8.0
6 -
Composi te
...
—
0.32
0.28
14
0.06
5
8.1 - 8.4
7 -
Composi te
...
...
0.11
0.21
19
0.10
3
7.9 - 8.2
8 -
Composi te
...
—
0.10
0.31
14
0.10
3
7.9 - 8.2
9 -
Grab (7/27)
32
1360
0.14
0.49
10
0.20
3
...
10 ¦
¦ Grab (7/26)
3
—
0.11
0.47
12
0.11
3
...
11 •
• Grab (7/26)
25
1560
0.08
0.37
23
3
7.7
12 ¦
- Grab (7/26)
2
1530
0.08
1.7
5
< 0.01
< 1
6.8
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TABLE IV
RADIUM-226 AND URANIUM IN CHEYENNE RIVER AND
COTTONWOOD CREEK WATER SAMPLES
Suspended
Dissolved
Dissolved
Dissolved
Collection
Sol ids
Sol ids
Radium-226
Uranium
Station
Date
(mg/1)
(mq/1)
(pCi/1)
(uq/1)
1
7/26
9
2540
0.34
17
7/27
7
0.27
18
7/28
6
0.22
24
7/29
7
0.45
19
7/30
4
0.26
15
Avg. - 0.31
Avg. - 19
2
7/26
9
4050
0.02'
26
7/27
15
0.11
38
7/28
6
0.10
22
7/29
6
0.10
20
7/30
5
0.07
18
Avg. - 0.08
Avg. - 25
3
7/26
1422(a)
2950
3.6
67
7/27
31
4.0
212
7/28
85
3.2
194
7/29
24
2.8
156
7/30
37
2.5
233
Avg. - 3.2
Avg. - 160
4
7/26
75
2810
2.0
158
7/27
27
2.5
150
7/28
86
3.7
228
7/29
16
2.2
89
7/30
11
2.1
135
Avg. - 2.5
Avg. - 152
5
7/26
11
3850
0.34
33
7/27
4
0.25
27
7/28
4
0.40
14
7/29
9
0.24
21
7/30
21
0.29
20
Avg. - 0.30
Avg. - 23
- 10 -
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TABLE IV
(Continued)
Suspended Dissolved Dissolved Dissolved
Collection Solids Solids Radium-226 Uranium
Station Date (mg/1) (mq/1) (pCi/1) (ug/1)
6 7/26 8 1800 0.22
7/27 6 0.23
7/28 8 0.28
7/29 7 0.29
7/30 5 0.30
Avg. - 0.26
7 7/26 4 2720 0.27
7/27 5 —- 0.27
7/28 3 0.22
7/29 3 0.21
7/30 3 0.28
Avg. - 0.25
8 7/26 7 1720 0.31
7/27 . 8 0.34
7/28 5 0.37
7/29 11 0.33
7/30 6 0.33
Avg. - 0.34
(a) High result considered to be due to the channel disturbance
caused by the 7/25 reconnaissance of the creek.
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TABLE V
DISSOLVED RADIOACTIVITY IN ANGOSTURA RESERVOIR
Sol ids
Station (a)(b)
A-l:
Surface
Bottom (12')
A-2:
1 Surface
^ Bottom (22')
A-3:
Surface
Bottom (20')
A-4:
Surface (30')
Bottom (-)
A-5:
Surface
Bottom (-)
Date
7/26
7/26
7/26
7/26
7/26
Suspended Dissolved
(mg/1) (mg/1)
Dissolved Radioactivity
14
37
79
130
12
28
5
10
7
22
930
980
1260
1230
1110
Radi urn-226
(pCi/1)
0.23
0.24
0.24
0.02
< 0.01
< 0.01
0.21
0.19
0.46
0.16
Uranium
(uq/1)
9
8
10
13
8
10
10
9
Total Alpha
Thorium (pCi/1)
< 0.01
0.04
< 0.01
0.07
< 0.01
0.02
< 0.01
0.06
< 0.01
0.22
Thori um-natural
(ug/1)
0.0
0.7
1 .5
4.9
0.7
0.7
0.5
0.5
0.3
0.3
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TABLE V
(Conti nued)
Sol ids
Suspended Dissolved Radium-226
Station Date (mg/1) (mq/1) (pCi/1^
A-6: 7/26
Surface 5 1090 < 0.01
Bottom (561) 7 — 0.05
A-7: 7/27
—¦ Surface 8 — 0.23
CO
Bottom (-) 9 — 0.14
A-8: 7/27
Surface 4 — 0.13
Bottom (-) 6 — 0.18
A-9: 7/27
Surface Sample Lost
Bottom (-) 8 — 0.12
¦10: 7/27
Surface 4 — 0.15
Bottom (481) 9 — 0.23
Dissolved Radioactivity
Uranium Total Alpha Thorium-natural
(uq/1) Thorium (pCi/1) (uq/1)
11 < 0.04 0.0
9 0.08 3.4
9 0.05 0.0
6 0.08 1.5
7 < 0.04 0.3
9 0.08 1.2
8 <0.04 0.7
8 < 0.04 1.7
8 0.06 1.1
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TABLE V
(Conti nued)
Solids
Station
A-11:
Surface
Bottom (45')
A-l 2:
Surface
Bottom (34')
A-l 3:
Surface
Bottom (14')
Date
7/26
7/27
7/27
SusDended
(mg/1)
6
18
11
16
17
19
Di ssolved
(mg/1)
1120
Radium-226
(pCi/U
0.13
0.34
0.28
0.18
0.14
0.26
(a) Refer to Figure II
(b) Collection depth in parentheses
Dissolved Radioactivity
Uranium Total Alpha Thorium-natural
(uq/1), Thorium (pCi/1) (uq/1)
9 < 0.01 0.3
9 0.07 0.7
6 0.12 0.9
7 < 0.04 1.4
8 < 0.04
4 < 0.04
-------
with the corresponding baseline concentrations for the Cheyenne River.
No significant difference was observed between the "surface" and "bottom"
concentrations of either radionuclide.
Well Waters
Seven wells in the Edgemont area were sampled (grab samples) to
determine the concentrations of radium-226 and uranium in groundwater:
Mines Development, Inc., well - mill process water
City Airport well
City Park well
City Reservoir well
Railroad wells - "old" and "new"
Cheyenne River Campground well
All wells, excluding the campground well, were completed in a deep,
confined aquifer. The campground well, located on the opposite side of
the river from the other wells, was completed in a shallow aquifer under
water table conditions. Radiochemical analysis was performed on the
samples "as collected" without filtration.
The radium-226 concentration in groundwater used for municipal water
supply and mill process water was substantially higher than the naturally-
occurring concentration in area surface waters. Grab samples from the
municipal, mill, and railroad wells contained 3.3 to 5.0 pCi/1; averaging
3.9 pCi/1 (Table VI). For uranium, the opposite was the case with the
groundwater level somewhat lower than the surface water level - 4 to 7 ug/1
versus an average 19 ug/1 at Station 1 on the Cheyenne River. Unlike the
deep wells, the shallow campground well contained a low concentration of
radium - 0.12 pCi/1. This difference indicates a lack of inter-connection
between deep and shallow aquifers.
Although the radium-226 concentration in groundwater is sufficiently
high to consider the water tower overflow and the "old" railroad well
drainage as sources of increased radium-226 (dissolved) in Cottonwood
Creek, the associated low flows of these discharges indicate that the
actual impact is not great because of dilution by natural creek flow and
seepage. The average daily flow of the water tower overflow is estimated
by mill management to be on the order of 2 to 3 gpm. Such a flow was only
about 1% of the creek flow at the road culvert during the field study.
Similarly, flow measurements at the road culvert and the confluence showed
the railroad well drainage to be less than 0.1 cfs.
- 15 -
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TABLE VI
RADIOACTIVITY IN WELL WATER SAMPLES
Radioactivity
CT>
Well Description
Mines Development, Inc., mill
wel 1
City of Edgemont
Airport well
Park wel1
Reservoir well
Cheyenne River campground
well - north of the
mill; across the river
Railroad wells
"Old" well
"New" well
(Both wells located within
several hundred feet of the
mill well)
Radium-226
(pCi/1)
3.5
3.7
4.4
5.0
0.12
3.7
3.3
Uranium
(ug/1)
5.0
7.0
5.0
5.0
0.2
4.0
5.0
Total Alpha
Thorium (pCi/1)
0.09
0.13
< 0.05
0.07
< 0.04
0.12
Thorium-natural
0.8
0.5
0.0
-------
The Edgemont water supply was sampled in 1966 by Messrs. Hickey and
Campbell(2) in their effort to identify population groups consuming water
with a relatively high radium content (more than 3.0 pCi/1). Their
reported finding for a single grab sample was 5.33 pCi/1 which is consistent
with the 1971 results. Assuming an intake of 1.0 liter per day of drinking
water, radium-226 intake by Edgemont residents served by the municipal
supply is on the order of 5 pCi per day from this source. This falls within
Range II (2-20 pCi per day) of the Federal Radiation Council guidance(3)
for radium-226 intake by the general public. For any level of intake within
Range II, it is appropriate to undertake quantitative surveillance and
routine control to ensure that the intake from all sources, not drinking
water alone, does not exceed the upper limit - 20 pCi per day of radium-226.
Although studies have not been conducted in Edgemont to determine the average
daily intakes from other sources (air, foodstuffs, beverages, etc.), it is
unlikely that these sources together with the drinking water supply produce
a total daily intake in excess of 20 pCi. Despite the fact that the average
dose received by Edgemont residents is apparently below the recommended
limit, dose reduction through treatment of the water supply to remove
radium-226 is desirable. Reduction in the radium concentration to near
surface water concentrations should be achievable by centralized municipal
water softening or "home" water softeners.
Seepage
Dissolved radioactivity results for seepage samples are summarized in
Table VII. Based on the uranium content of groundwater samples (less than
10 ug/1), the high uranium concentrations in seepage samples collected in
the vicinity of the pipeline suspension bridge indicated the mill ponds
are the major source of seepage entering Cottonwood Creek. Similarly,
the uranium concentration in direct seepage to the Cheyenne River just
below the confluence with Cottonwood Creek indicated the source of this
seepage is also the mill ponds. Although the sample collected from the
seepage zone just upstream of Pond No. 1 was not analyzed for uranium,
the source of this seepage was identified to be Pond No. 1 during the
1966 field study (1966 - 89 ug/1 of uranium).
The concentrations of radium-226 and uranium in seepage collected
at the base of the river bank adjacent to the Pond No. 2 sand tailings
storage area are consistent with the premise that the source is the
movement of drainage from the abandoned railroad well through the sand
tailings. At the time of the field study, this drainage had formed a
small pool at the south end of the storage area.
A comparison of the dissolved radioactivity in the ponded liquors
and seepage samples shows substantial reductions in radionuclide con-
centrations as the solutions move through the soil to the surface waters
(Tables VII and VIII). This is well illustrated by the results for Pond
No. 3 and the seepage samples collected at the base of the east wall of
the pond (wall thickness less than 50 feet). There was about a 100-fold
difference in the dissolved radium-226 concentrations and only
- 17 -
-------
TABLE VII
DISSOLVED RADIOACTIVITY IN SEEPAGE SAMPLES
Description
Cottonwood Creek (along east bank);
(a) Several hundred yards upstream
of the pipeline suspension bridge
(approximately 6 feet above the water
surface) - two samples
(b) 50-100 feet upstream of the
pipeline suspension bridge (at the
bank - stream bed interface)
Cheyenne River (south bank):
(a) At base of bank adjacent to
Pond No. 2; just downstream of
State Highway 18 Bridge
(b) Approximately 100 yards
downstream of the confluence with
Cottonwood Creek
Dissolved Radioactivity
Radium-226 Uranium Total Alpha Thorium-natural
(pCi/1) (ug/1) Thorium (pCi/1) (ug/1)
0.18 332 0.31 0.8
1.1 816 0.0
0.54 —
2.3 5 0.26 3.0
0.35 176 17 50
-------
Descri ption
Cheyenne River (south bank):
Conti nued
(c) Just upstream of Pond Number 1
(approximately 2 feet above the water
surface)
(d) Approximately 1 1/2 miles down-
stream of the mill (just above water
surface)
On Site:
Seepage from Pond No. 3 across
road toward Edgemont sewage lagoon
TABLE VII
(Continued)
dissolved Radioactivity
Radium-226 Uranium Total Alpha Thorium-natural
(pCi/1) (uq/1) Thorium (pCi/1) (uq/1)
1.1 —
2.1 26 0.19 0.0
0.68 2320 0.94 3.0
-------
TABLE VIII
RADIOACTIVITY IN MILL PONDS
Solids Dissolved Radioactivity Bottom Sediment (dry weight basis)
Suspended Dissolved Radium-226 Uranium Total Alpha Thorium-Natural Radium-226 Uranium Total Alpha Thorium-natural
Description (ppm) (ppm) (pCi/1) (uq/1) Thorium (pCi/1) (ug/1) (pCi/g) (ug/q) Thorium (pCi/g)- Vug/9)
Influent to Pond 587 — 98 1860 1240 110 — — — —
No. 1
Pond No. 1 — — 61 1860 1400 180 1007 19 11
Pond No. 2 554 52,360 93 8090 — 180 46 140 63 180
Pond No. 7 — 41 ,300 726 56,000 — 650 75 33 67
-------
about a 4-fold difference in the dissolved uranium concentrations. The
higher affinity for radium-226 to be retained in the soil is an expected
finding.
Bottom Sediment ahd Soil
Radioactivity results for bottom sediments collected from Cottonwood
Creek, the Cheyenne River, and Angostura Reservoir are presented in Table
IX. These data showed the same contamination pattern as exhibited by the
radioactivity results for water samples. Bottom sediment contamination
in Cottonwood Creek occurred throughout the reach extending from the
channel adjacent to sand tailings pile No. 1 downstream to the confluence
with the Cheyenne River. Radium-226 and uranium concentrations in the
contaminated reach of the creek ranged from 3 to 41 pCi/gram and 3.1 to
53 ug/gram, respectively. Comparatively, background levels range from
1.0 to 2.5 pCi/gram for radium-226 and 1.0 to 6.0 ug/gram for uranium.
All sediment samples from the Cheyenne River and Angostura Reservoir
showed background levels.
Contamination zones in Cottonwood Creek were not-identical for
radium-226 and uranium. Uranium contamination was largely confined
to the lower portion of the creek; the seepage impacted stretch extending
from a point just upstream of the pipeline crossing downstream to the
mouth. Radium contamination included this stretch and the stretch extending
upstream to the pool adjacent to sand tailings pile No. 1 (Figure III).
This finding illustrated the difference between contamination attributable
solely to the errosion of sand tailings piles versus the combined effect
of radioactivity-bearing seepage and tailings pile errosion. Sand tailings
material contains a high concentration of radium-226 (on the order of 200
pCi/gram), but is essentially depleted in uranium (>20 ug/gram). Thus,
as shown by the results for Stations C, D, and E (Table IX; Figure III),
the deposition of sand tailings from pile No. 1 in the creek has produced
elevated radium-226 concentrations without a corresponding increase in the
uranium content. The confinement of uranium contamination to the seepage-
impacted stretch indicates that uranium entering the creek via the seepage
flow undergoes mass transport from the dissolved to solid state by physical
(adsorption/absorption) and/or chemical reactions (precipitation).
As was the case in previous studies, the sediment sample collected at
the pedestrian bridge across Cottonwood Creek (Station A) contained radium-
226 at a concentration slightly greater than the background level. The
possible explanations are a natural source (spring flow) or periodic con-
tamination of the site by windblown sand tailings from pile No. 1 (located
several hundred feet downstream). Since the sediment was stained at this
- 21 -
-------
FIGURE III
COTTONWOOD CREEK
BOTTOM SEDIMENT SAMPLING STATIONS
FOOTBRIDGE
NOTE: DRAWING NOT TO SCALE
\SAND TAILINGS
PILE NO. 2
POND
NO. 7
- 22 -
-------
TABLE IX
RADIOACTIVITY CONTENT OF BOTTOM SEDIMENTS FROM COTTONWOOD CREEK
CHEYENNE RIVER AND ANGOSTURA RESERVOIR
Radioactivity Content (dry weight basis)
Radium-226 Uranium Total Alpha Thorium-natural
Station (pCi/q) (ug/q) Thorium (pCi/q) (uq/q)
Cottonwood Creek:^a)
2 - Upstream of all waste sources 2.4 6.7 0.08 15
A - Pedestrian footbridge; Figure III 3.9 6.4 1.6 22
B - Ponded area; Figure III 24 8.2 8.4 15
C - Riffle area; Figure III 41 2.8 0.20 15
D - Ponded area; Figure III 11 3.1 3.3 6
E - Approximately 50 yards above the
pipeline suspension bridge;
Figure III 12 7.5 4.0
F - 50-100' upstream of the pipeline
suspension bridge; Figure III 15 17 1.9
G - Pipeline suspension bridge;
Figure III 40 53 —
3 - 19 13 0.38 15
4 - 4 28 0.29 16
-------
Station
Cheyenne River:
1 - Upstream of all waste sources
H through M - Sampling locations
spaced along the edge of the river
channel ; downstream edge of Pond
No. 1 to approximately one mile
downstream
5 -
6 -
7 -
8 -
9 -
TABLE IX
(Conti nued)
Radioactivity Content (dry weight basis)
Radium-226 Uranium Total Alpha Thorium-natural
(pCi/g) (ug/g) Thorium (pCi/g) (ug/g)
1 .0
2.4
0.08
9
1.0-2.6
1.5-4.4
0.8-1.5
1 .0
3.1
0.08
16
2.5
3.1
0.11
18
1 .0
—
0.09
10
0.90
—
0.11
12
1.6
—
0.43
17
-------
Station
Angostura Reservoir:^)
1
2
3
cn 4
' 5
6
7
8
9
10
11
12
13
(a) Refer to Figure III
(b) Refer to Figure II
TABLE IX
(Conti nued)
Radioactivity Content (dry weight basis)
Radium-226 Uranium Total Alpha Thorium-natural
(pCi/g) (ug/g) Thorium (pCi/g) (ug/g)
1 .7
4.1
0.41
30
1.7
3.9
0.66
26
1.7
4.6
0.73
25
1 .0
3.2
0.39
18
1 .4
4.4
0.75
32
1.7
4.6
42
1.8
3.3
0.64
44
1.4
3.2
0.32
39
1.2
3.2
0.57
35
1.3
3.3
0.43
31
1 .6
5.4
0.66
25
2.6
4.1
0.69
19
1 .5
3.6
0.84
--
-------
location (reddish-brown to reddish-orange discoloration), the former
cannot be discounted as a contributing factor. However, as discussed
in the following section of this report, a soil sample collected across
the creek from pile No. 1 (to the east) showed a high level of contamina-
tion. This finding indicated that wind transport of sand tailings may
well be the major source of the elevated radium-226 concentrations at
Station A.
Sediment samples from the Cheyenne River contained radium-226 and
uranium within the background ranges of 1.0 to 2.6 pCi/gram and 1.5 to
4.4 ug/gram, respectively. This included the special set of six samples
collected along the channel edge from the downstream corner of Pond No. 1
to a point approximately one mile downstream (Stations H through M - Table
IX). Since this stretch of river was characterized by sediment staining
attributable to seepage from Pond No. 1, it had been anticipated that the
radium and uranium concentrations of these samples would be slightly higher
than the observed background levels. Angostura sediment samples contained
radium-226 and uranium in concentrations comparable to those in the Cheyenne
River.
The field study eliminated any question regarding the transport of
sand tailings from pile No. 1 into Cottonwood Creek by errosive action
during periods of high runoff and/or wind action. Such transport was
documented by the analysis of bottom sediment samples as well as visual
observation of the common boundary between the creek and the tailings
pile for a distance of several hundred feet. One small section of this
common boundary is shown in Figure IV (photograph taken on October 3, 1972-
low flow condition). Similar documentation was obtained for the loss of
sand tailings from the Pond No. 2 storage area. Soil samples collected
at thirteen locations on the Cheyenne River bank and the dry stream bed
adjacent to Pond No. 2 (Figure V) showed that sand tailings had breached
the security fence and were beginning to migrate down the slope. Radium-226
concentrations in samples collected just outside the fence - Stations SI,
S2, S3, and S4 - were indicative of sample compositions approaching 25 to
50% sand tailings (Table X). Along the line marking the sharp increase
in bank slope - Stations S5, S6, S7, S8, and S9 - background concentrations
of radium-226 were found. These data suggested that a loss of solids to
the river had and continues to take place, but the magnitude of the loss
has not been large. Slightly elevated radium-226 concentrations in the
dry stream bed - Stations SI 1 and S12 - were probably caused by seepage
as opposed to sand tailings.
Sand tailings have sloughed from pile No. 2 onto the flood plain
of Cottonwood Creek. This was evidenced by the mounds of "white" sand
on the bench between the tailings pile and the creek channel. A grab
sample from one of the mounds showed the presence of "pure" sand tailings -
162 pCi of radium-226 per gram. During periods of high flow, this is
undoubtedly a source of contamination to the Cheyenne River system.
- 26 -
-------
FIGURE IV
SAND TAILINGS PILE NO. 1 ALONG
STRETCH OF COTTONWOOD CREEK
OCTOBER 1972
- 27 -
-------
FIGURE V
SOIL SAMPLES COLLECTED FROM THE BANK
IN THE VICINITY OF POND NO. 2
-------
TABLE X
RADIOACTIVITY CONTENT OF SOIL SAMPLES COLLECTED
FROM THE CHEYENNE RIVER BANK ADJACENT TO THE
POND NO. 2 STORAGE AREA
Radioactivity Content (dry weight basis)
Station^3)
Radium-226
(pCi/q)
Uranium
(uq/q)
Total Alpha
Thorium (DCi/q)
ST -1
43
14
4.7
SI
96
16
6.4
S2
46
5.4
5.5
S3
56
23
12
S4
54
19
8.2
S5
1.8
3.3
1.0
S6
2.0
3.3
0.4
S7
1 .9
3.2
2.6
S8
2.1
4.3
0.9
S9
1.3
4.5
0.5
SIO
sn
5.4
0.6
2.5
S12
5.3
4.1
0.7
(a) Refer to Figure V
- 29 -
-------
Fish - Angostura Reservoir
Consistent with the background radioactivity levels in the water
and bottom sediments of Angostura Reservoir, the analysis of fish samples
showed extremely low concentrations of radium-226 and uranium in bone
and edible tissue (flesh). Summarized in Table IX, all radium-226
results were less than 0.1 pCi per gram (dry weight) and all but one
uranium result were less than 0.1 ug per gram, these data are identical
with the results for fish collected from the reservoir during the Septem-
ber 1966 study. U)
- 30 -
-------
TABLE XI
RADIUM-226
AND URANIUM IN ANGOSTURA
RESERVOIR
FISH
AUGUST 1971
Number
Length
Radium-226
Uranium
Radium-226
Uranium
Species
of Fish
(Inches)
(pCi/q)
(uq/q)
(pCi/q)
(uq/q)
Carp
1
--
<0.1
<0.1
<0.1
<0.1
Channel Catfish
1
_ _
<0.1
<0.1
<0.1
<0.1
3
—
<0.1
<0.1
<0.1
<0.1
Crappie
7
<10
<0.1
<0.1
<0.1
<0.1
Perch
4
--
<0.1
<0.1
<0.1
<0.1
Walleye
1
15
<0.1
0.6
<0.1
<0.1
1
16
<0.1
<0.1
<0.1
<0.1
1
20
<0.1
<0.1
<0.1
<0.1
1
21
<0.1
<0.1
<0.1
<0.1
(a) Results refer to live weight
-------
PROGRESS TOWARD POLLUTION ABATEMENT
Environmental Protection Agency personnel visited the mill on
October 3, 1972, to discuss the efforts undertaken by Mines Develop-
ment, Inc., to abate radiological pollution from the milling operation.
The Company's overall program generally follows the points expressed by
Mr. K. L. Hudson, District Manager, in his statement prepared for the
Enforcement Conference record.(4) Specific actions taken in the period
of about one year following the Conference are described below together
with an assessment of the probability of success in resolving the
existing problems.
Liquid Waste Management
The operational changes instituted to eliminate seepage from mill
ponds involve the operation of ponds at reduced static heads, i.e.,
smaller holding volumes than was the practice prior to 1972 and a long-
term program of new pond construction. Mines Development, Inc., personnel
view the seepage problem as one caused by the deterioration of the ponds
with age complicated by excessive fluid pressure on embankments. There-
fore, by operating the ponds with lower embankment pressures and system-
atically abandoning "old" ponds, it is believed that the seepage problem
can be eliminated.
Several changes in the pond system have been made since October,
1971, consistent with the above analysis of the problem. Pond No. 10
(75 million gallon capacity) was constructed and became operational in
February, 1972, replacing Pond No. 1 for vanadium raffinate storage. The
reason for the abandonment of Pond No. 1 was to eliminate one source of
direct seepage to the Cheyenne River. Although the stored raffinate was
being pumped out of the pond at the time of the mill visit, the liquid
level indicated that Pond No. 1 had been in a static state for the bulk
of the year; consequently, a continued source of seepage. Pond No. 3
has been drained and the deposited slimes are being mined for vanadium
recovery. Based on Mr. Hudson's statement to the Enforcement Conference, '
this pond will also be abandoned at the completion of this mining activity.
The two other significant changes involve Ponds No.'s 8 and 9 (formerly
No. 10). These ponds were converted from a contingency status to active
process ponds. Table XII summarizes the operational functions of the
various ponds as of October, 1972, and the changes in the pond system
since the 1971 field study.
Through October, 1972, significant improvement in the seepage problem
was not evident. There was limited visual evidence to indicate that some
reduction in the seepage flow to Cottonwood Creek had occurred since the
high bank to the west and north of Pond No. 7 was dry in appearance. In
1971, this same area was observed as moist (and "dripping") to a height
over six feet above the water surface. However, damp sections on the creek
bank just upstream of sand tailings pile No. 2 indicated that the seepage
- 32 -
-------
TABLE XII
MILL PROCESS AND RETENTION PONDS
Pond Use
CO
CO
Pond
No. 1
No. 2
No. 3
No. 4
No. 7
October 1972
1971
No. 8
Scheduled for abandonment; liquor is being
pumped to No. 10.
Sand tailings storage.
No liquid storage; deposited slime tail-
ings are being mined for vanadium recovery.
"Polishing" sedimentation basin for vana-
dium-bearing liquor.
Retention and storage of uranium sand
tailings; water recycled for use as process
water and repulping sand tailings for pump-
ing to this pond.
Retention and storage of uranium slime tail-
ings and flyash and slag residues from the
vanadium circuit; sedimentation basin to
produce clarified blue liquor.
Disposal of raffinate from the vanadium
extraction circuit.
Sand tailings storage.
Storage basin for vanadium-bearing liquor
(blue 1iquor).
Not in use.
Retention and storage of slime tailings
and sand tailings; sedimentation basin
to produce clarified blue liquor.
Conti ngency.
-------
TABLE XII
(Conti nued)
Pond Use
Pond
October 1972
1971
No. 9*
(formerly No.
10)
Surge pond to receive and store liquor
from No. 8.
Conti ngency.
No. 10
Disposal of vanadium raffinate.
(Constructed
in 1972).
*The small porid designated Number 9 in 1971 has been abandoned.
-------
flow had not been totally stopped. A comparative type observation of
the previously observed areas of heavy bank seepage (1966 and 1971) in
the vicinity of the pipeline crossing was not possible because these
areas were inundated by downstream beaver dam construction. The lack
of improvement indicated by the visual observations is substantiated
by the water quality monitoring data (discussed in the following section)
which show no reduction in the radiological contamination of Cottonwood
Creek during 1972.
It is likely that the apparent lack of improvement in this seepage
problem is partially attributable to a yet unsteady-state condition
following the changes in the pond system. However, despite the abandon-
ment of Ponds No.'s 1 and 3, the majority of the old ponds remain in
service, albiet at reduced storage volumes. The resultant effect can be
expected to be a reduction in seepage, but not total abatement. Total
abatement will require the new ponds to be properly constructed to prevent
fluid loss by seepage.
Unless the rate of evaporation is sufficiently high, the continued
operation of the mill will require that an increasing amount of land be
committed to waste storage. To prevent an undesirable sprawl of waste
retention ponds, the alternatives of trucking spent ore solids (as emerging
from the mill process) back to the open-pit mine and a system of sealed
basins with a completely treated effluent should be investigated. It is
entirely possible that the costs of these alternatives may be more econom-
ically attractive than those associated with new pond construction and
land restoration following the cessation of millinq operations.
Uranium Sand Tailings
The progress made on controlling and stabilizing stockpiled sand tail-
ings to prevent wind and water errosion and the development of an ultimate
disposal plan is not satisfactory. It is a matter of the Conference record
that the Company considers the proposed ultimate storage of sand tailings
in the open-pit mine to be economically prohibitive. (4)' Instead, the
Company has proposed on-site stabilization with a vegetative cover.
The only action of a positive nature undertaken during 1972 was the
establishment of two small test plots (each approximately one and one-half
acres) to investigate possible stabilization procedures. A brief progress
report concerning this study was submitted to the South Dakota Department
of Health by Mr. G. A. Fluke, District Engineer, in a letter dated
November 28, 1972 (Appendix A). Briefly, the test plots involved the
foil owing work:
1. Sand Tailings Pile No. 1 - Pretreatment of the sloping plot
(to the southeast, varying from 5 to 20 percent) consisted of
blading to smooth the area, addition of lime to neutralize the
latent acidity of the sand tailings, and spreadinq of manure.
This was followed by seeding with a blended mix of rye grass
and red clover and the application of fifteen pounds of ammonium
nitrate. Native fireweed seed was also "thrown" on the plot.
No irrigation.
- 35 -
-------
2. Pond Number 2 Area - Same procedure as that for the sand
tailings' pile Mo. 1 test plot except irrigation was provided.
The plot was watered by a sprinkler system on an average of
onee every three days throughout the growing season.
From the standpoint of vegetative growth, both test plots were failures.
Fiqure VI shows the growth of the rye grass on the Pond No. 2 test plot.
Figure VII shows a sparse growth of only fireweed and sunflowers on the
pile No. 1 test plot. As expected without routine watering, there was
no germination of grass seed on this plot. Despite the sparsity of growth,
the mere fact that fireweed could grow on the "treated" sand tailings is
viewed optimistically by plant personnel as indicating that fireweed may
provide suitable vegetative cover if the growth period is sufficiently
long. As observed by Mr. Hudson, the sparsity of rye and clover growth
may have been attributable, at least in part, to the late planting date -
late June. However, it seems more likely that the major causative factor
was the lack of a good topsoil base and adequate irrigation.
Additional testing of fireweed growth is planned for 1973. The plan
calls for leveling additional areas, adding fertilizer at a loading greater
than that used for the 1972 test plots, pumping Cheyenne River water into
the areas during the spring period of high sediment transport in order to
build-up a topsoil base, and encouraging the subsequent growth of native
fireweed. It is envisioned that after two to three years, the fireweed
could be burned to obtain the mulch required for the establishment of
natural grass. The drawbacks to this plan are several:
1. Pumping water onto the stock-piled sand tailings creates the
risk of solids loss to the Cheyenne River via runoff. Extreme
caution will have to be exercised.
2. Without any assurance of success that could be immediately
achieved by the conventional procedure of covering with
top-soil, seeding, and irrigating, the proposal increases
by several years the period of time that the stock-piled
sand tailings will be subjected to wind and water errosion.
3. There is no provision for removing sand tailings which have
drifted to locations along the banks of Cottonwood Creek and
through the security fence surrounding the Pond No. 2 storage
area.
If on-site stabilization is to be practiced, it seems appropriate that
the conventional procedure mentioned above be employed.
Of immediate urgency for positive control action is the stabilization
and control of sand tailings stock-piled in the Pond No. 2 storage area.
- 36 -
-------
FIGURE VI
POND NO. 2 SAND TAILINGS
STORAGE AREA STABILIZATION TEST PLOT
OCTOBER 1972
- 37 -
-------
FIGURE VII
SAND TAILINGS PILE NO. 1
STABILIZATION TEST PLOT
OCTOBER 1972
- 38 -
-------
Not only have the sand tailings drifted through tne security fence to
within a few feet of State Highway 18 (Figure VIII) and onto the river
bank, but tailing's now form a common boundary with the Martinez family
property (Figure IX). The Martinez property immediately adjacent to
the tailings storage area is used for a pig pen, chicken coop, and yard
for a milk cow. (Small pigs were observed running on the tailings.) A
soil sample collected in the chicken area just inside the fence - judged
to be predominately sand tailings by visual observation - contained 34 pCi
of radium-226 per gram; nearly twenty times natural background. More
importantly, significant contamination was found in the soil sample
collected in the play yard. The radium-226 content of this sample was
9.2 pCi/gram, or approximately five times the background level. Accordingly,
the following control actions are recommended:
1. Sand tailings which have drifted through the security fence
should be collected and stored at a suitable disposal site.
Additionally, a tailings-free barrier (excess of 10 feet)
should be created between the pile and the fence.
2. The pile should be contoured, covered with topsoil (an alternative
to trucking the material to the open-pit), and seeded with rye
grass or some other suitable grass or grain. Irrigation must
be practiced.
3. A new fence should be installed which effectively prevents
access to the stabilized pile.
In view of the nearness of the Martinez house, reworking the sand tailings
will probably require working with "damp" material in order to prevent
dust and subsequent wind transport.
Some insight to the environmental degradation which has occurred as
the result of sand tailings storage in Pond No. 2 can be gained from
Figure X which shows largely the same area as Figure VIII. The difference
is that the photograph shown in Figure X was taken in September 1966 just
after the start of sand tailings input to Pond No. 2.
To check on the possibility of wind-drift of sand tailings across
the small residential area lying to the east of pile No. 1, a composite
soil sample was collected from the sloping terrace area adjacent to a
mobile home - across the creek channel. The area over which the sample
was composited was used for children's play and received vehicular traffic.
Although contamination was expected, the actual high level was surprising -
45 pCi of radium-226 per gram. This finding approached the concentrations
found just outside the Pond No. 2 area fence. Admittedly, the sampling
was biased toward emphasizing the presence of sand tailings by the collection
of loose and/or sandy-type material. Nonetheless, the finding of contamination
- 39 -
-------
FIGURE VIII
VIEW FROM STATE HIGHWAY 18 ACROSS POND
NO. 2 SAND TAILINGS STORAGE AREA
OCTOBER 1972
- 40 -
-------
FIGURE IX
VIEW OF MARTINEZ PROPERTY SHOWING ENCROACHMENT
OF SAND TAILINGS FROM POND NO. 2 AREA
STATE HIGHWAY 18 IN IMMEDIATE BACKGROUND -
IDENTIFIED BY YELLOW ROAD SIGN AND BRIDGE
OCTOBER 1972
- 41 -
-------
FIGURE X
VIEW FROM STATE HIGHWAY 18
ACROSS POND NO. 2
SEPTEMBER 1966
- 42 -
-------
in this residential area further substantiated the existence of off-site
land contamination and the need to take control actions. To eliminate
any concern of the possibility of localized "hot spots," it is recommended
that a soil sampling and analysis program be undertaken to delineate zones
of contamination and the levels of radium-226 contamination therein. If
areas of undesirably high concentration are found, a corrective action
program will be required to remove the contaminated soil.
- 43 -
-------
WATER QUALITY MONITORING PROGRAM
As directed by the Conferees, a water quality monitoring program was
initiated in the Edgemont, South Dakota, area during May, 1972. The
monitoring program consists of a network of four stations sampled for the
purpose of determining the annual average concentrations (dissolved)
and variations therefrom of radium-226, uranium, and selected heavy metals.
Sampling locations are the following:
1. Cheyenne River at State Highway 18 bridge; upstream of Mines
Development, Inc., mill.
2. Cottonwood Creek at County Road Bridge; east of State Highway
52; upstream of Mines Development, Inc., mill.
3. Cottonwood Creek downstream of road culvert on mill property.
4. Cheyenne River at Red Canyon; approximately two miles below
the confluence with Cottonwood Creek.
Samples are collected by a local Edgemont resident under contract to the
Environmental Protection Agency with shipment to the Region VIII laboratory
for analysis. Samples for radiological analysis are shipped without
pretreatment or filtration; "metals" samples are filtered shortly after
collection and acidified. During January, 1973, the collection frequency
was reduced from the initial weekly rate to bi-weekly.
Monitoring results for the period of May through September, 1972,
are presented in Tables XIII - XVI. These data yielded the below
findings:
Cheyenne River
1. With the exception of dissolved iron, there was no detectable
impact on Cheyenne River water quality as the result of seepage
from mill ponds - to Cottonwood Creek or directly to the river.
As shown in Tables XIII and XIV, the five-month average concen-
tration for each parameter, excluding iron, were equivalent at
the two stations bracketing the mill. The dissolved iron con-
centration showed approximately a two-fold increase at the
downstream station (Red Canyon). However, additional monitoring
data will be required to verify this finding since the accuracy
of the dissolved iron results was not high. This was attributable
to the precipitation of iron and subsequent coating of the sample
container walls in the time interval between sample collection
and analysis.
- 44 -
-------
^inc
iq/i)
58
22
21
20
82
54
50
105
49
54
21
Suspended Portion
Radium-226 "Uranium
(pCi/g) (ug/g)
2.3 1.0
3.4
2.2
1.6 0.4
1.5 0.7
2.0
3.5
TABLE XIII
EDGEMONT MONITORING PROGRAM
CHEYENNE RIVER AT STATE HIGHWAY 18 BRIDGE
UPSTREAM OF MINES DEVELOPMENT, INC., URANIUM~MILL
Dissolved Portion
Gross Alpha Gross Beta Radium-226 Uranium Arsenic Iron Lead
(pCi/1)
(PCi/1)
(PCi/1)
(uq/i)
(uq/1)
(ug/i)
(uq/1;
—
—
—
<10
—
—
—
—
<10
100
100
<1
8
0.3
20
<10
60
98
<1
8
<0.1
16
—
40
105
<1
6
<0.1
17
<10
40
112
<1
<1
0.1
14
...
3300
85
<1
17
0.2
10
...
3700
60
<1
<1.5
0.1
4
<10
470
60
25
<20
O
ro
12
—
1900
87
<3
<20
0.3
16
...
310
67
<2
54
1.8
15
...
90
70
<2
<20
0.3
20
60
80
-------
TABLE XIII
EDGEHONT MONITORING PROGRAM
CHEYFNNE RIVER AT STATE HIGHWAY 18 BRIDGE
UPSTREAM OF MINES DEVELOPMENT, INC., URANIUM MILL
Suspended
Portion
Dissolved
Portion
Collection
Date
Flow
(cfs)
Radi um-226
(pCi/g)
Urani urn
(ug/g)
Gross Alpha
(pCi/1)
Gross Beta
(PCi/1)
Radium-226
(PCi/1)
Urani um
(uq/1)
Arsenic Iron
(ug/1) (ug/1)
Lead
(uq/1)
Manganese
(uq/1)
Vanadi um
(uq/1)
Zinc
(ug/1)
8/7/72
64
2.2
1.8
<2
<20
0.2
5
—
—
8/14/72
2.9
22
—
<2
<20
0.4
16
420
60
60
7
56
9/2/72
8.1
—
—
8
<20
0.2
12
...
150
60
60
7
40
9/9/72
16
1.4
1.2
3
<20
<0.1
9
—
—
...
...
9/14/72
4.0
1.5
—
<2
25
0.7
19
—
150
60
80
4
54
9/23/72
4.0
2.3
...
<2
<20
0.3
19
— -
70
70
60
4
30
5-Month
Average
0.3
14
740
78
105
14
48
-------
inc
13/11
30
30
30
22
64
50
50
60
65
112
59
TABLE XIV
EDGEMONT MONITORING PROGRAM
COTTONWOOD CREEK UPSTREAM OF MINES DEVELOPMENT, INC., URANIUM MILL
AT COUNTY ROAD BRIDGE; JUST EAST OF STATE HIGHWAY 52
Suspended Portion Dissolved Portion
Radium-226 Uranium Gross Alpha Gross Beta Radium-226 Uranium Arsenic Iron Lead
(pCi/q) (uq/q) (pCi/1) (pCi/1) (pCi/1) (uq/1) (uq/1) (uq/1) (uq/1)
—
...
...
—
<10
...
—
...
...
...
...
...
<10
60
94
11
<1
15
0.2
16
<10
270
112
...
<1
7
0.2
23
...
60
152
...
<1
<3
0.1
34
<10
60
124
...
<1
7
0.4
21
—
60
130
...
<1
11
0.1
16
...
80
40
...
<1
10
0.1
27
<10
180
105
1.4
<1
<20
0.1
19
...
110
107
...
<2
<20
<0.1
25
...
340
87
—
<2
<20
0.7
32
...
160
80
<2
<20
0.1
57
260
100
-------
TABLE XIV
EDGEMONT MONITORING PROGRAM
COTTONWOOD CREEK UPSTREAM OF MINES DEVELOPMENT, INC. , URANIUM MILL
AT COUNTY ROAD BRIDGE; JUST EAST OF STATE HIGHWAY 52
Suspended
Portion
Dissolved
Portion
Col lection
Date
Radi um-226
(pCi/q)
Urani urn
(uq/q)
Gross Alpha
(pCi/1)
Gross Beta
(PCi/1)
Radi um-226
(PCi/1)
Uranium
(ug/1)
Arsenic Iron
(uq/1) (ug/1)
Lead
(ug/1)
Manganese
(uq/i)
Vanadi um
(ug/1)
Zi nc
(uq/1)
8/7/72
0.1
<2
<20
<0.1
49
860
90
60
9
104
8/14/72
—
—
3
22
0.2
54
---
...
...
...
...
9/2/72
1.8
—
8
21
0.1
41
160
70
60
86
68
9/9/72
9.7
...
<2
<20
0.3
28
380
110
80
7
93
9/14/72
10
...
<2
<20
0.4
33
190
90
60
16
86
9/23/72
9.3
...
<2
<20
0.4
32
110
100
40
8
48
5-Month
Average
0.2
32
213
99
96
11
61
-------
Zinc
27
10
31
27
35
58
36
354
295
126
108
TABLE XV
EDGEMONT MONITORING PROGRAM
COTTONWOOD CREEK DOWNSTREAM OF SEEPAGE
from mines development, inc., uranhjitrtll
Suspended Portion Dissolved Portion
Radium-226 Uranium Gross Alpha Gross Beta Radium-226 Uranium Arsenic Iron Lead
(Pci/g) (ug/g) (pCi'/l) (pCi/1) (pCi/1) (uq/1) (ug/1) (ug/1) (uq/1)
—
—
—
<10
—
...
...
...
...
...
<10
470
100
35
4
20
0.8
157
<10
110
80
—
2
11
0.4
82
...
30
120
—
2
26
0.3
203
<10
30
124
—
6
18
1.6
230
...
3600
110
—
8
27
1.8
270
...
1200
20
—
19
10
1.1
233
<10
2480
132
144
16
45
6.5
194
...
3600
117
32
15
38
8.7
134
...
32000
27
160
30
68
5.7
456
...
980
80
54
12
37
10
331
6960
100
-------
TABLE XV
EDGEMQNT MONITORING PROGRAM
COTTONWOOD CREEK DOWNSTREAM OF SEEPAGE
FROM MINES DEVELOPMENT, INC., URANIUM MILL
Suspended
Portion
Dissolved
Portion
Collection
Date
Radi um-226
(pCi/q)
Urani urn
(uq/q)
Gross Alpha
(pCi/1)
Gross Beta
(PCi/1)
Radium-226
(pCi/1)
Uranium
(ug/1)
Arseni c
(uq/1)
Iron
(ug/1)
Lead
(ug/1)
Manganese Vanadium
(ug/1) (ug/1)
Zinc
(ug/1)
O
8/7/72
8.1
66
<4
<20
5.1
444
...
1860
120
2360
200
89
8/14/72
8.9
25
13
<20
9.8
500
—
1620
100
1820
180
96
9/2/72
54
—
33
41
1.9
400
—
1880
70
1840
7
148
9/9/72
55
...
8
21
5.5
300
...
1160
80
1160
122
73
9/14/72
76
46
8
21
4.3
245
...
300
90
1080
78
75
9/23/72
61
20
5
<20
8.8
300
...
860
110
900
122
77
5-Month
Average
4.5
280
3480
93
2240
290
98
-------
Zini
lusA
22
30
12
15
82
70
54
170
40
54
16
TABLE XVI
EDGEMONT MONITORING PROGRAM
CHEYENNE RIVER AT RED CANYON
APPROXIMATELY TWO MILES DOWNSTREAM M CONFLUENCE WITH COTTONWOOD CREEK
Suspended Portion
Dissolved Portion
Radium-226
(pci/g)
Uranium
(ug/g)
Gross Alpha Gross Beta Radium-226 Uranium Arsenic Iron Lead
(pCi/1) (pCi/1) (pCi/1) (ug/1) (ug/1) (ug/1) (uq/1)
...
---
...
...
...
...
<10
...
...
1.7
...
<1
10
0.2
14
<10
380
98
2.5
1.0
<1
17
0.4
23
<10
50
98
1.5
<1
7
0.1
21
...
30
94
2.9
...
1
8
0.2
14
<10
30
120
1.9
1.1
<1
10
0.3
10
...
9000
80
1 .0
0.5
1
9
0.1
8
...
5100
50
—
0.6
<1
11
0.1
4
<10
545
53
14
...
...
—
0.6
...
—
2450
98
1.5
4
<20
0.3
15
...
140
80
15
...
<2
<20
0.3
20
...
60
80
<2
<20
0.3
19
20
80
-------
TABLE XVI
Col lection
Date
8/7/72
8/14/72
9/2/72
9/9/72
9/14/72
9/23/72
5-Month
Average
EDGEMONT MONITORING PROGRAM
CHEYENNE RIVER AT RED CANYON
APPROXIMATELY TWO MILES DOWNSTREAM THE CONFLUENCE WITH COTTONWOOD CREEK
Suspended Portion Dissolved Portion
Radium-226 Uranium Gross Alpha Gross Beta Radium-226 Uranium Arsenic Iron Lead Manganese Vanadium Zinc
(pCi/g) (ug/q) (pCi/1) (pCi/1) (pCi/1) (ug/1) (uq/1) (ug/1) (uq/1) (ug/1) (ug/1) (ug/1)
1.9 1.3 <2 <20 0.2 5
6.9 2.7 <2 <20 0.3 16 — 640 70 60 9 57
<2 <20 0.3 15 — 20 60 20 2 12
1.0 1.3 <2 <20 0.3 10
2.1 — <2 <20 0.3 16 — 70 70 80 5 61
<2 <20 0.4 14 — 110 50 60 4 11
0.3 14 --- 1240 79 79 6 47
-------
2. Dissolved radium-226 concentrations were low and within the
range of 0.1 -0.7 pCi/1; excluding the one anomolous result
of 1.8 pCi/1 at the State Highway 18 bridge (7/24). Similarly,
low leveTs of dissolved uranium were observed with concentrations
in the range of 5 to 20 ug/1. For both radionuclides, concen-
trations were independent of river flow and remained relatively
constant throughout the five-month data period.
3. Concentration ranges for heavy metals were:
Arsenic vig/1
Lead 50 - 120 yg/1
Manganese 20 - 320 yg/1
Vanadium "I ~ "^0 ug/1
Zinc 12 ~ 170 ug/1
Cottonwood Creek
1. With the exception of dissolved uranium, water quality at the
county road bridge was similar to upstream Cheyenne River water
quality. Dissolved radium-226 results (Table XIV) showed a
maximum of 0.7 pCi/1, and a 5-month averaqe of 0.2 pCi/1. This
average is the same as those calculated for the Cheyenne River
stations. In contrast, dissolved uranium - on an average value
basis - occurred at a concentration sliqhtly greater than twice
that found in the Cheyenne River - 32 ug/1 versul 14 uq/1.
Furthermore, the dissolved uranium data did not exhibit relative
constancy over the 5-month period. Instead, the data showed a
rise to a maximum in late-July and August, and subsequently
declining values.
2. Attributable to seepage from mill ponds, average concentrations
of dissolved uranium and radium-226 at the station downstream of
the road culvert (Table XV) were substantially greater than back-
ground levels (10 and 20 times greater, respectively). For the
5-month data period, dissolved radium-226 showed a range of 0.4
to 10 pCi/1; dissolved uranium a range of 82 to 500 ug/1. The
rise in concentrations during the monitoring period were undoubtedly
caused by decreasing creek flow; hence, decreasing dilution of
seepage flowing into the creek. The data do not support any claim
to the effect that radioactivity levels upstream of the mill do,
on occasion, exceed the corresponding levels downstream of the
zones of active seepage.
3. Seepage also produced significant increases in the concentrations
of dissolved iron, manganese, and vanadium (Table XV). Based on
5-month average values, the increases were on the order of 15,
20, and 30 times greater than naturally-occurring levels for iron,
manganese, and vanadium, respectively. It is interestinn to note
- 53 -
-------
that despite the large increase in the dissolved iron
concentration and the extensive precipitation that occurs in
Cottonwood Creek, the maximum concentrations of dissolved iron
were found in the Cheyenne River.
4. Seepage did not impact the concentration of arsenic, lead, and
zinc. Consequently, analysis of these metals has been terminated.
Based on comparisons with the results of previous studies, no significant
improvement in the water quality of Cottonwood Creek occurred through
September, 1972. Although sufficient data have not been accumulated to
reach a final decision, it is an obvious possibility that the actions taken
to date may not be adequate for achieving demonstrable improvement in water
quality. The other possibility is that the data are representative of a
transitional phase and some improvement will be observed during 1973.
Therefore, the actions taken by Mines Development, Inc., to abate seepage -
although suspect in terms of overall adequacy - remain an open question at
this time.
- 54 -
-------
REFERENCES
(1) U. S. Environmental Protection Agency, "Evaluation of the Impact
of the Mines Development, Inc., Mill on Water Quality Conditions in the
Cheyenne River," Region VIII, Denver, Colorado (September 1971).
(2) Hickey, J. L. S., and S. D. Campbell, "High Radium-226 Concentra-
tions in Public Water Supplies," in Public Health Reports, 83, 7, pp.
551-557 (July 1968).
(3) Federal Radiation Council, "Background Material for the Development
of Radiation Protection Standards," Staff Report Number 2 (September 1961).
(4) U. S. Environmental Protection Agency, "Transcript of Proceedings
in the Matter of Pollution of the Navigable Waters of Western South
Dakota," Held at Rapid City, South Dakota (October 19-21, 1971).
- 55 -
-------
APPENDIX A
-------
lrj>i\£b' Development, Inc.
EDGEMONT, SOUTH DAKOTA
C
o
p November 28, 1972
Dr. Robert H. Hays
State Health Officer
South Dakota Department of Health
Pierre, South Dakota 57501
Dear Sir:
A progress report on the stabilization tests for the sand tailings at Mines
Development, Inc., follows:
A test plot of approximately one and one-half acres was established north of
the mill complex. Based upon a soil analysis made by the Brookings Lab.,
pretreatment consisted of blading the area smooth (the plot has a general slope
of about 6% to the southeast), addition of one-half ton of 1 inw per acre in
the form of 5" down, crushed rock; spreading of eight to ten of manure
per acre and discing. A blend of broms grass and red clover was seeded,
followed by the application of fifteen pounds of ammonium nitrate. The seed
bed was watered by an overhead sprinkler system on an average of once every
three days throughout the growing season. No reliable estimate of the water
used is available.
The results were the establishment of a grass stand on approximately fifteen
percent of the seed bed. No clover appeared to have germinated in this en-
vironment. The grass that matured was generally located down slope from the
sprinkler locations.
The alternjlo test plot located south of the mill complex was prepared in the
same manner. The slope, again to the southeast, varied from 20 to 5 percent.
Here the growth of native annuals and bushes was promoted by the nutrients
added. The results indicate that tv.'o species known locally as Fireweed and
Sunflowers will grow in this environment. Sources for the Fire.veed seed have
not been found and furthor seediny will have to cone from a ir.ulch prepared
from cuttings. The weed has a tough stock that should resist sand erosion
but the root system is not too extensive for holdinj purposes.
- A-l -
-------
Or. Robert Hays
SO State Health Officer
-2*
November 28, 1972
Additional areas will be leveled and substantially more fertilizer added during
the next growing season. The addition of some soil builders by flooding test
plots with silted water from the creek at high water will be done In the coming
spring.
Very truly yours,
MINES DEVELOPMENT, INC.
G. A. Fluke
District Engineer
gaf: Ih
cc: Mr. Irvln L. Dlcksteln, Director
EPA, Enforcement Division
Denver, Colorado
- A-2 -
------- |