Montana Bureau of Mines and Geology photograph from postcard

A recent investigation of the upper Silver Bow Creek drainage by
the Montana Bureau of Mines and Geology has concluded that:
the site of the Parrot Complex is the most important source of groundwater contamination in the upper Silver Bow Creek drainage,
gaps in the water-quality and hydrogeologic data have led to
underestimation of the extent of contamination by the Parrot Complex,
hydrogeologic conditions (aquifer properties and hydraulic gradients) are
favorable for the migration of contaminated ground-water toward Silver
Bow Creek. Travel times of contaminates to reach Silver Bow Creek are
on the order of decades, and
the quality of ground-water can recover in a relatively short period of time
(less than 100 years) if a proper removal of source material at the Parrot
Complex is completed. If there is no removal, recovery will be on the
order of thousands of years.
This report is available electronically through the MBMG website:
http://www.mbmg.mtech.edu
contact: [email protected]
photograph from postcard: World Museum of Mining, Butte, Montana
MBMG
Montana Bureau of Mines and Geology
The area between Montana Street and Continental Drive in Butte,
Montana has been identified by several names including upper Silver Bow
Creek (U.S. Geological Survey, Geographic Names Information System),
Metro Storm Drain, and upper Area One Operable Unit. Surface and near
surface deposits of wastes associated with mining and milling have been
identified as potential sources of ground-water and surface-water
contamination. Prominent is a large area near the Butte Civic Center and the
"county shops" that contains tailings, slag, and other waste generated by the
Parrot smelter and mill; the site is herein referred to as the Parrot Complex.
Construction of the smelter was completed in July 1881 and consisted of open
stalls for roasting lump ore, reverberatory roasters, and matting reverberatory
furnaces. In 1884, with the installation of six converters, the Parrot was the
first smelter in the United States to successfully produce blister copper from
copper matte using the Bessemer Process; with the installation of the
converters, the Parrot was processing about 350 tons of ore per day and
producing about 25,000 pounds of copper per day. In 1886, the Parrot had
increased its facilities, and was the second largest copper producer in the Butte
area. Besides smelting, the Parrot also had a concentrating plant to treat the
second-class ore prior to smelting. The concentrating plant consisted of
crushing equipment, jigs, and vanning tables, and was capable of processing
250 tons of ore per day. The Anaconda Company purchased the Parrot Smelter
and closed the facility in 1899.
A recent report released by the U.S. EPA has made claims as to the
rate of ground-water flow and the migration of contaminated ground-water
through the alluvial aquifer in the upper Silver Bow Creek drainage. The
Montana Department of Environmental Quality (MDEQ)and the Montana
Department of Justice (MDOJ) solicited comments from the Montana Bureau
of Mines and Geology (MBMG) as to these claims; written comments were
provided to the agencies in December of 2003. These comments led to
funding by the EPA and MDOJ for the MBMG to drill and sample new wells,
conduct column leach tests on aquifer materials, and collect chemical data
from existing wells. These new data strongly add to the body of evidence
supporting the interpretations that for the aquifer underlying upper Silver Bow
Creek:
FIGURE 1. INTRODUCTION
LEGEND
Monitoring wells
(some are nested)
Tailings, slag, and mine waste
(approximate)
Surface water
(present day)
Streets and roads
PARROT
COMPLEX AMW-8
t
dS
n
co
Se
t
ree
Montana Street
nt
Fro
KOA
CAMP
CIVIC
CENTER
GS-41S/D
SHOPPING
CENTER
eet
Str
GS-42S/D
GS-10B/A
AMC-12
GS-50
PW-01
AMW-1
GS-35S/D
UPPER
SILVER BOW
CREEK
GS-46S/D
GS-43S/D
MF-7
Grand Avenue
GS-30
MF-3
GS-8,9,11
MF-10
George Street
MF-11
MF-9
MF-8
GS-31S/D
GS-14
AMW-12
AMC-24
AMC-13
George Street
ue
ven
nA
riso
Har
e
nu
ve
wA
Ka
GS-32S/D
East
Middle
School
GS-44S/D
Clark
Park
Cobban Street
AMW-13
BT98-02
GS-28
N
3) hydrogeologic conditions (aquifer properties and hydraulic gradients) are
favorable for the migration of contaminated ground-water toward Silver Bow
Creek. Travel times of contaminates to reach Silver Bow Creek are on the
order of decades, and
4) the quality of ground-water can recover in a relatively short period of time
(less than 100 years) if a proper removal of source material at the Parrot
Complex is completed. If no removal occurs, recovery will be on the order of
thousands of years.
Decisions will soon be made as to the remediation of contaminated groundwater in this area. Whereas many factors such as engineering, economic, and
societal impacts must be considered, all good judgments must be based on
good science. In a careful review of all of the available data collected over the
past 20 years, this report summarizes the concepts shared by the authors as
well as a good many colleagues.
AMW-22
MF-5
MF-1 GS-29SR
2) gaps in the water-quality and hydrogeologic data have led to
underestimation of the extent of contamination by the Parrot Complex,
AMC-6
AMW-9
GS-7
GS-33
AMC-23
Continental Drive
GS-40
MF-4
1) the site of the Parrot Complex is the most important source of ground-water
contamination in the upper Silver Bow Creek drainage,
COUNTY
SHOPS
GS-45
MF-6
GS-29S/D
AMW-20 `
BT98-01
C Street
BT98-03
BT98-04
I-
SCALE
0
1/4
1/2 mile
15
&
90
MBMG
Montana Bureau of Mines and Geology
FIGURE 2: PREVIOUS AND RECENT INVESTIGATIONS
LEGEND
Previous Investigations
30-45
Surface water
(present day)
Historic surface water
(~1912)
Streets and roads
bore holes for column
tests
wells sampled for
isotope analyses
Screen depth (feet below ground
surface)
DRAINAGE BELOW HARRISON
AVENUE
et
e
r
t
VOLUMES (cubic
S yards)
nd
o
c
Se
tailings and tailings-alluvium
mix 200,000
fill (overlying waste materials)
570,000
et
e
r
TOTAL
770,000
St
nt
o
r
F
39-49
GS-33
tailings and tailings-alluvium mix 480,000
alluvial fill
300,000
slag
580,000
fill (overlying waste materials)
1,010,000
TOTAL
2,370,000
47.5-57.5
GS-42S/D
4-14
AMW-1
23.5-33.5
GS-35S/D
12-17
MF-10
8-13
MF-1 GS-29SR
35-45
100-110
AMC-12
GS-10B/A 248-268
GS-50
130-160
GS-7
PW-01 17-42
12-17
MF-5
13-18
MF-7
6-11
GS-28
Clark
Park
28.5-38.5
GS-30
10.5-15.5
MF-11
11-16
MF-9
60.5-75.5
125.5-145.5
GS-8,9,11 28.6-38.6
GS-31S/D
52-62
8-23
GS-14
AMW-12
1/4
George Street
C Street
10-15
BT98-04
I-
1/2 mile
Grand Avenue
47-55
AMC-13
NEW WELLS: screened interval
(feet below ground surface)
East
Middle
School
AMW1b: 33.5 to 43.5
George Street
AMW1c:
90 to 100
MSD1b: 40 to 45
MSD1c: 110 to 115
MSD2:
35 to 45
MSD3:
40 to 50
(bore hole to 70)
Cobban Street
14-19
BT98-02
15-25
BT98-01
SCALE
51-61
GS-46S/D
49-59
GS-43S/D
50.4-60.4
GS-44S/D
13-23
AMC-24
5-15
AMW-13
AMW-22
27-37
AMW-9
27-37
GS-32S/D
9-14
MF-8
Continental Drive
53-63
AMC-6
52-62
GS-40
50.5-60.5
GS-41S/D
21-26
MF-4
13-18
MF-3
19-29
AMC-23
AMW-20
30-45
AMW-8
ue
ven
nA
riso
Har
30-39
GS-29S/D
e
nu
ve
wA
Ka
13-18
MF-6
New Investigation
In the spring of 2004, with funding provided by the EPA and MDOJ,
six monitoring wells were installed at four sites along the ground-water flow
path between the Parrot tailings area and the confluence of Blacktail and Silver
Bow Creeks near Montana Street. The wells were drilled deeper than most
others in the area; the objective was to determine the lithology and groundwater quality in the deeper portion of the alluvial aquifer. In addition to the
wells, samples of the contaminated aquifer material were collected from
boreholes in the source area near the Civic Center and midway down the
drainage (green dots). These materials were used to construct soil columns
through which clean ground water was circulated; the data were used to
evaluate whether the natural aquifer would recover if the waste material were
removed. Helium and tritium isotope samples, used to determine the apparent
age of ground water, were collected from six wells (blue circles). The age of
the ground water might suggest whether ground water and the contaminants
therein are moving very slowly (very old apparent age) or more quickly (young
apparent age).
0
PARROT COMPLEX
VOLUMES (cubic yards)
49-59
GS-45
Montana Street
The most comprehensive study of the upper Silver Bow Creek
drainage was released by the Montana Department of Environmental Health
(now the MDEQ) in 1990; that study concluded that the Parrot Complex was
the most significant source of contamination in the drainage. A report released
by the MDOJ in 1995 identified the Parrot Complex as the most significant
source (Maest and others, 1995); that report relied heavily on the 1990 report.
A report released by the PRP Group in 2002 (PRP, 2002) made no statements
as to source areas. A report released by the EPA in 2004 (EPA, 2004)
concluded that there were multiple sources and that the Parrot Complex was
not a significant source of contamination for the majority of the drainage.
Detailed information related to ground water in the upper Silver Bow
Creek area is sparse and generally limited to the shallowest part of the aquifer.
Although there are about 50 monitoring wells in the area between Montana
Street and Continental drive, the majority were installed in the late 1980's and
a few in 1991; no wells have been installed in the last 12 years - except those
installed for this investigation. All of the wells have been sampled for water
quality, some wells have been sampled several times, but about 20 of the 50
wells were sampled only once in 1989 and have not been sampled in 15 years.
Water levels have been collected from most of the wells at least once;
continuous data sufficient for hydrographs, however, are limited to a few wells
near Continental Drive. Concurrent water levels from all of the wells,
sufficient to produce a potentiometric map, have only been done three times in
the last 15 years - most recently for this investigation. The alluvial aquifer is
over 200 feet thick in most of the area; however, the average depth of the 50
wells is less than 35 feet.
The areal extent and thickness of tailings and contaminated material
in the upper Silver Bow Creek is fairly well documented by lithologic logs for
wells and core samples collected over the years. Early reports suspected the
presence of tailings or other contaminated material beneath the Butte Civic
Center and the shopping center; most recent data shows that such materials are
limited to the old stream channel. The volumes of tailings and other materials
are presented in figure 2.
Monitoring wells
(some are nested)
Tailings, slag, and mine waste
(approximate)
15
&
90
N
13-18
BT98-03
MBMG
Montana Bureau of Mines and Geology
FIGURE 3: NEW WATER QUALITY DATA
LEGEND
Monitoring wells
(some are nested)
New Water-Quality Data
Previous investigations were limited to the upper 20 feet of the
alluvial aquifer between the Parrot Complex and the lower portion of the
drainage; as noted, the average depth of all the wells in the area is less than 35
feet. This data gap led to an underestimation of the extent of ground-water
contamination caused by the tailings, slag, and other materials in the Parrot
Complex. Water-quality, hydrologic, and lithologic information from the new
wells fills an important gap in hydrogeologic and geochemical data in the
intermediate and deeper portions of the upper Silver Bow Creek alluvial
aquifer. Concentrations of dissolved constituents in upper Silver Bow Creek
alluvial ground water are several orders of magnitude greater than those
predicted in previous work. For example, the measured concentration of
copper in well MSD-1b was 4,200 micrograms per Liter (ug/L), yet copper
concentrations in ground water from this location were previously thought to
be less than 100 ug/L (shown by contours on map). The concentration of zinc
in well MSD-1b was about 200,000 ug/L, whereas previous studies estimated
a concentration of only 10,000 ug/L. A comparison of concentrations of other
constituents shows similar discrepancies and demonstrate that most preexisting wells were too shallow to detect the migration of contaminated
ground water from the Parrot Complex.
In the new wells, concentrations in ground water at intermediate
depths (AMW1b, MSD1b, and MSD2) generally decreased in the downgradient direction from the upper Silver Bow Creek area (AMW wells) to the
mid-portion of the aquifer (MSD1 and MSD2). New water-quality
information from the most recent investigation indicates that metals and
sulfate at intermediate depths in the alluvial aquifer have migrated at least
2,000 feet down gradient in the 100 years from the source area into the lower
drainage.
Concentrations of metals and sulfate in the deeper wells (AMW-1c
and MSD1c) were lower than those at intermediate depths. Concentrations in
MSD2, which is more down gradient and adjacent to the stream channel, were
generally higher than those at MSD1. This may indicate that MSD2 is nearer
the center of the contaminant plume than the other wells.
Data from the new wells cannot answer all of the questions related to
ground-water flow and migration of contaminants, but they do demonstrate
several things:
Surface water
(present day)
New monitoring
wells
Copper Concentrations
in Ground Water (ug/L)
Age date of water
22.7 based on tritium helium isotopes
Streets and roads
Previous investigations
New data (no contours)
AMW-20
`
AMW1b
et
tre
S
nd AMW1c
co
e
S
Montana Street
MSD1b
et
tre
S
MSD1c
nt
Fro
MSD2
97,040
4,344
10
10
0,
GS-41S/D
41.8
,0 000
00
1,
GS-42S/D
00
GS-10B/A
38.2 GS-50
10 0
GS-7
PW-01
4,201
0
AMW-1
22.7
GS-35S/D
269
AMW-9
AMC-12
GS-43S/D
GS-46S/D
Grand Avenue
MF-5
GS-33
43,639
MF-7
East
Middle
School
GS-44S/D
Clark
Park
30.9 AMC-13
GS-30
MF-3
George Street
MF-11
MF-9
MF-8
GS-8,9,11
GS-31S/D
GS-14
MF-1 GS-29SR
AMW-12
AMC-24
George Street
ue
ven
nA
riso
Har
e
nu
ve
wA
Ka
GS-32S/D
MF-10
AMW-22
GS-40
MF-4
AMC-23
AMC-6
GS-45
MF-6
GS-29S/D
Continental Drive
AMW-8
PARROT
COMPLEX
MSD2 43,639
Cobban Street
AMW-13
BT98-02
GS-28
N
1) data gaps have led to gross underestimation of the extent of ground-water
contamination originating from the Parrot Complex,
2) contamination from the Parrot Complex has migrated several thousand feet,
and
BT98-01
3) concentrations of contaminants decrease rapidly with depth; most of the
contamination occurs at 50 to 75 feet below the surface.
C Street
BT98-03
BT98-04
The concentrations of tritium and helium isotopes, used to determine the
apparent age of ground water, indicate a young, dynamic flow system.
Overall, there is little change in the age of the waters and the apparent,
absolute age is young (less than 50 years). These data support the concept that
contaminated ground water has migrated from the Parrot Complex to Blacktail
Creek in a few decades.
I-
SCALE
0
1/4
1/2 mile
15
&
90
MBMG
Montana Bureau of Mines and Geology
Redefining the Ground-Water Flow System and Travel Times
Monitoring well
(water elevation)
Surface water
(present day)
Surface water site
Streets and roads
Hydrographs of wells in the Parrot
Complex area (shown in blue)
5464
Water-elevation contour
April, 2004
(contour interval 1 foot)
Direction of groundwater flow
GS-45
5462
LP-2
5468.4
LP-6
5460
5601.7
Berkeley
5458 Pit
LP-5
LP-9
5463.8
GS-46D
5444.4
SCALE
GS-41D
GS-42D
5456
0
0.25
GS-44D
5478.5
0.5 mile
5454
Dec-80
AMC-13
LP-10
Dec-84
Dec-88
Dec-92
Dec-96
Dec-00
Dec-04
LP-16
AMC-5
5429.2
5440.5
LP-17
5443.8
DATE
LP-14
5458.4
LP-12
5460.2
AMW-20
AMW-8
GS-45
5458.7
5461.1
5458.9
AMC-6
5459.1
GS-40
AMW-9
5457.3
GS-41D
5459.4
AMC-8
AMW-22
5461.9
5459.4
GS-42D
AMC-12
5455.9
AMW-1
5453.1
5457.9
5454.8
MF-5
GS-46D
5448.7
GS-33
MF-6
5435.4
GS-29R
MF-1
5437.9
MSD-3
GS-30D MF-11
5445.4
GS-9
MF-9 5449.9
5446.8
MF-3
AMC-23
5442.2
MF-8
5440.0
MF-10
5454.8
Water balance for shaded area
5445.9
GS-31D
5445.5
AMW-12
5442.9
5446.7
AMC-24
5440.7
GS-28
surface water = 187,000 gallons per day
ground water = 172,000 gallons per day
BT9802
5444.9
5
0
544
5445.4
60
AMC-13
545
MF-2
AMW-11
5438.2
AMW-13
5438.8
5465.3
54
GS-44D
5456.0
GS-32D
5439.5
AMC-15
MSD-2
5448.4
MF-4
5458.8
MSD-1
MF-7
5440.8
total
BT9803
BT9801
5443.6
BT9904
545
5445.2
Blacktail Creek
= 359,000 gallons per day
average
household use = 615 gallons per day
5453.1
5449.8
0
584 households could be served
(assuming 100% consumption)
5
544
Water-level elevations in wells near the Parrot Smelter have been
collected by the MBMG since 1991 and in other areas since 1983. The inset
shows hydrographs of water-level elevations in wells in the upper part of the
drainage. The differences in water-level elevations among the wells clearly
indicate that the water table in the Parrot Complex area is not flat, and that
ground water readily flows though the area. The hydrographs also indicate
that during the wet years of the 1990's, the hydraulic gradients in the area were
greatest for the period of record. Currently, gradients are less due to several
years of normal to below normal precipitation and it is not unreasonable to
conclude that gradients will become steeper again when climatic conditions
become wetter. The gradients may also become steeper in the future due to the
rising water level in the Berkeley Pit. Overall, hydraulic gradients reflect the
topographic gradient of the valley and range from .002 to .006 ft/ft.
Lithologic and hydrologic data from the new monitoring wells in
conjunction with data from existing wells indicate the presence of three
ground-water flow systems. The shallow system, the subject of previous
investigations, is fairly well documented. Water levels in these wells are
generally above the elevation of Silver Bow Creek and are the likely source of
loading to the creek, especially in the upper drainage. The hydraulic
conductivity of the shallow material reflects the fine-grained litholoies
described in the well logs; values are on the order of a few feet per day. The
concentrations of dissolved constituents in the upper 40 feet of the aquifer
reflect local sources of contamination, if any, and surface recharge.
The intermediate ground-water, 40 to 60 feet below ground surface,
flows through discrete layers of gravel and sand with minor silt and clay. In
the upper part of the drainage, this flow system is dominated by a continuous
layer of coarse gravel; in the lower part of the drainage, the coarse gravel
apparently grades to a fine gravel. A layer of gravel coincident with poor
quality water was recorded in lithologic logs for wells completed in the source
area (e.g. GS41 and GS42) in previous investigations. The western extent of
the gravel was not found during this investigation, but the concentration of
dissolved constituents in these gravels tends to remain high nearly 2,000 feet
from source area. When specific capacity (discharge/drawdown) is used as a
rough estimate, the hydraulic conductivity of the gravel is about 150 feet per
day in AMW1b and about 87 feet per day in MSD1b.
The deeper ground-water flow system in this discussion is that which
is greater than 60 feet below ground surface. Lithologic information collected
during the installation of the new monitoring wells indicates discrete layers of
sand with minor silt and clay. Specific capacity data collected during sampling
of AMW1c produces a hydraulic conductivity of about 17 feet per day for a
five-foot interval of sand at a depth of 95 to 100 feet below ground surface.
Concentrations of dissolved constituents in the deeper flow system are much
less than those of the intermediate flow system, but still reflect migration of
contaminated water from the Parrot Complex at least 1,000 feet farther than
described in previous investigations. The chemistry of the deep flow system
likely reflects mixing of contaminated water from the Parrot Complex with
deep uncontaminated ground water. Using the appropriate hydraulic
conductivity and gradient data, ground-water velocities in the Parrot Complex
area are on the order of 0.5 to 0.9 feet per day.
Surface-water flow based on direct measurements and ground-water
flow based on the above information yields a total of about 400,000 gallons
per day discharging through the shaded area of the map (see second inset for
the water balance).
FIGURE 4: REDEFINING THE GROUND-WATER
FLOW SYSTEM
LEGEND
5456.6
Blacktail Creek at Fr. Sheehan Park
(off map)
N
FIGURE 5: AQUIFER RECOVERY
Cadmium
Zinc
90000
500
LEGEND
70000
300
red line is the
drinking-water standard
50000
30000
Surface water
(present day)
Streets and roads
bore holes for column
tests
100
Monitoring wells
(some are nested)
Tailings, slag, and mine waste
(approximate)
0
10000
0
-100
0
10
20
pore volumes passed
30
0
40
10
20
pore volumes passed
30
40
AMW-20
Continental Drive
AMW-8
Copper
80000
GS-40
400
60000
t
dS
n
co
Se
300
40000
20000
0
-10000
100
0
0
10
20
pore volumes passed
30
40
0
Montana Street
200
t
ree
GS-41S/D
GS-42S/D
20
pore volumes passed
30
GS-10B/A
MF-7
`
AMC-23
5440.0
MF-10
5442.78
MF-1 GS-29SR
AMC-24
5440.73
5438.15
AMW-13
5438.8
GS-28
5440.79
GS-30
East
Middle
School
MF-11
MF-9
8000
GS-8,9,11
7000 GS-31S/D
5445.4
6000
GS-14
5000 AMW-12
4000
3000
2000
BT98-02
5444.89
1000
0
0
5
George
Street
Zinc
AMC-13
George Street
ue
ven
nA
riso
Har
e
nu
ve
wA
Ka
GS-29S/D
GS-32S/D
MF-8
Grand Avenue
GS-44S/D
Clark
Park
MF-3
GS-46S/D
MF-5
MF-4
Column tests using aquifer material from two contaminated areas
(green dots) were conducted to test whether the water quality in the aquifer
would recover if the source of contamination (tailings, slag, etc.) were
removed. Uncontaminated water from the aquifer was passed through each
column of contaminated material at a rate of one pore volume per day; a
sample was collected and analyzed after each pore volume passed. The inset
graphs show the concentrations (vertical axis) of zinc, copper, cadmium, and
iron for each column. In both tests, the quality of the water improved
throughout the test. With one exception, the water flowing out of the column
met drinking water standards (red line) before the end of the test. The one
exception is cadmium in the column for the aquifer beneath the tailings;
cadmium decreased from nearly 500 to about 7 ug/L (the drinking water
standard is 5 ug/L). These tests demonstrate that if the source of
contamination is removed, the quality of water in the aquifer will likely
recover to meet drinking water standards. The rate of recovery is simply a
matter of inducing flow by pumping to pass the required number of pore
volumes of clean water through the material. Thus, recovery could be induced
and drinking water standards met in less than 100 years.
GS-50
PW-01
GS-43S/D
MF-6
Aquifer Recovery
AMC-12
AMW-1
GS-35S/D
GS-33
40
AMW-9
GS-7
et
tre
S
nt
Fro
10
AMW-22
AMC-6
GS-45
Iron
red line is the
drinking-water standard
70
50
30
Cobban Street
10
15
20
25
pore volumes passed
Cadmium
90
30
35
10
0
0
5
10
15
20
25
pore volumes passed
BT98-01
35
Iron
Copper
1500
N
30
BT98-03
C Street
0.6
BT98-04
1000
SCALE
0.4
I15
500
&9
0.2
0
0
0
1/4
1/2 mile
0.0
0
5
10
15
20
25
pore volumes passed
30
35
0
5
MBMG
10
15
20
25
30
35
pore volumes passed
Montana
Bureau of Mines and Geology
The two major objectives of this investigation were to 1) evaluate the
rate of transport of contaminated ground water from the Parrot Complex in
upper Silver Bow Creek, and 2) evaluate the recovery rate of the water quality
in the aquifer if the source were removed.
Although the objectives were normally those of the remedial
investigation, the data presented here demonstrate that previous investigations
fell short of a complete characterization of the ground-water flow system and
the geochemical conditions of the upper Silver Bow Creek. This investigation
demonstrates that ground-water flow velocities are at least an order of
magnitude higher than those previously reported and that contaminants have
migrated much farther than presented in recent reports. It is important to note
that the migration of the contaminants has probably occurred in the last 50
years. Thus, the rate of ground-water flow and rate of contaminant transport
are on the order of years and decades not centuries.
Column tests, based on worst-case conditions, demonstrate a recovery
rate sufficient to restore water quality to beneficial use if the source of
contamination is removed. Existing hydraulic gradients, which were assumed
for this evaluation, are much lower than those that would be induced during
source removal or those that could be induced by short-term pumping and
treating (increasing the hydraulic gradient would dramatically increase the rate
of recovery).
This investigation was not intended to fully characterize the upper
Silver Bow Creek drainage. Rather, it filled several gaps in the data collected
over the past 15 years. Additional work should include refinement of the
hydrogeologic model based on lithology and water quality in 1) the lower area
near the confluence of upper Silver Bow Creek and Blacktail Creek, 2) north
and west of the present stream channel, and 3) at the source area where coarse
sands and gravels were identified in earlier investigations.
The MBMG gratefully acknowledges the U.S. EPA and the Montana
Department of Justice for their support and cooperation in this investigation.
This report is available electronically through the MBMG website:
http://www.mbmg.mtech.edu/search_1.asp?type=pid
contact: [email protected]
FIGURE 6: SUMMARY
LEGEND
Monitoring wells
(some are nested)
Surface water
(present day)
Tailings, slag, and mine waste
(approximate)
New monitoring
wells
Streets and roads
Contaminated ground
water
Extent of contamination - concentrations
of dissolved constituents in ground water
exceed one or more maximum contaminant
level or secondary maximum contaminant
level, based on 2001 data
AMW-20
`
PARROT
COMPLEX
t
dS
n
co
Se
t
ree
AMW-9
GS-10B/A
Montana Street
GS-7
MF-7
MF-3
George Street
MF-11
MF-9
MF-8
GS-8,9,11
GS-31S/D
GS-14
MF-1 GS-29SR
AMW-12
AMC-13
George Street
ue
ven
nA
riso
Har
e
nu
ve
wA
Ka
GS-30
East
Middle
School
GS-44S/D
AMC-24
Cobban Street
AMW-13
BT98-02
GS-28
N
Maest, A.M., Metesh, J.J., and Brand, 1995, Butte Groundwater Injury
Assessment Report, Clark Fork River Basin NPL Sites, Montana,
prepared by RCG/Hagler Bailey for the Montana Natural Resources
Damage Litigation Program, January, 1995, 120pp.
BT98-01
C Street
BT98-03
BT98-04
PRP Group, 2002, Butte Priority Soils Operable Unit, Silver Bow Creek /
Butte Area Superfund Site, Phase II Redial Investigation Report,
prepared by MFG, Inc., April, 2002, 2 volumes.
EPA, 2004, Response action contract for remedial, enforcement oversight, and
non-time critical removal activities at sites of release or threatened
release of hazardous substances in EPA Region VIII, Final Phase II
Remedial Investigation / Feasibility Study, Appendix E, Focused
Feasibility Study of the Metro Storm Drain, prepared by CDM
Federal Programs Corporation, February, 2004.
Grand Avenue
MF-5
GS-32S/D
MF-10
GS-46S/D
GS-43S/D
MF-4
MDHES, 1990, Draft Final Silver Bow Creek CERCLA Phase II Remedial
Investigation Data Summary: Area One Operable Unit, prepared by
CH2MHill, Inc. and Chen-Northern, Inc., Helena, Montana, August,
1990, 2 volumes.
GS-50
PW-01
AMW-1
GS-35S/D
MF-6
References Cited
AMC-12
Clark
Park
AMC-23
AMW-22
GS-40
GS-42S/D
GS-33
GS-29S/D
AMC-6
GS-45
GS-41S/D
et
tre
S
nt
Fro
Continental Drive
AMW-8
I-
SCALE
0
1/4
1/2 mile
15
&
90
MBMG
Montana Bureau of Mines and Geology