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Douglas Creek Tailings Removal
July 27,
1998
January 12,
2000
Granite
Montana
S of the
SE of Section 31 and the SW of the SW of Section 32 in Township
7 North, Range 13 West and the NE of the NE of Section 6 in
Township 6 North, Range 13 West.
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| Douglas
Creek at beginning of restoration. (taken on July 15,
1998) |
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Nearest Town and Distance: Philipsburg, Montana is approximately
1.5 miles to the NW.
Location: The Douglas Creek Tailings Site is located adjacent
to Douglas Creek along both the east and west banks, in the vicinity
of Philipsburg, Montana. The site contains two separate tailings
impoundments. The tailings impoundments are located approximately
1.5 miles southeast of Philipsburg.
Estimated Cost: The total cost of the project was $2,458,390.
This includes $455,230.00 for engineering (planning, investigation,
design, and oversight) and $2,003,160 for construction. The ratio
of engineering (total) to construction cost was 22.7%. The ratio
of engineering construction management cost to construction cost
was 13.4%. To view the engineering cost summary and the engineering/construction
change orders for the Douglas Creek restoration click on the icons
below.
Engineering Cost Summary: (Table
1)
Engineering/Construction Change Orders: (Table
2)
Project Sponsors: Montana Department of Environmental Quality,
Mine Waste Cleanup Bureau and the United States Department of the
Interior, Office of Surface Mining.
Oversight Agency: The reclamation project was completed
in cooperation with the Montana Department of Environmental Quality,
Mine Waste Cleanup Bureau, P.O. Box 200901, 2209 Phoenix Avenue,
Helena, MT 59620, Telephone: (406) 444-2074.
Project Partners: Pioneer Technical Services, Inc. (Pioneer),
was responsible for planning and providing supporting documentation
necessary to provide resource managers with the appropriate decision
making tools for full-scale reclamation at the site. Pioneer was
also responsible for preparing the final design and engineering
specifications for the project, and for overseeing construction.
Pioneer's address and telephone is:
Pioneer
Technical Services, Inc.
P.O. Box 3445
Butte, MT 59702
Telephone: (406) 782-5177
The project site is owned by Frank Antonioli, Contact Mining Company,
1029 Choteau, Helena, MT 59601.
Reasons for Action: The Douglas Creek Tailings Site is an
abandoned hardrock mine site listed on the DEQ/AMRB Priority Sites
List. At this site, tailings from the historic Bi-Metallic and Granite
Mountain Mills were impounded in the Douglas Creek drainage and
were eroding into the creek. The tailings contained elevated levels
of arsenic, cadmium, copper, manganese, mercury, lead, antimony,
and zinc at concentrations greater than three times background concentrations.
Surface water downstream from the site contained elevated arsenic,
manganese, lead, and zinc.
Objectives: The purpose of the Douglas Creek Tailings Reclamation
Project was to limit human, livestock, wildlife, and environmental
exposure to the COCs present at the site (primarily heavy metals)
and to reduce the mobility of the contaminants to mitigate potential
impacts to local surface water and groundwater resources. This objective
was achieved by removing waste from within the stream channel, constructing
a stabilized stream, and covering all waste with an impermeable
cap and vegetated cover soil.
History of Site: The historic Philipsburg Mining District
has produced large quantities of silver, gold, zinc, lead, copper,
and most recently, manganese. The first lode was discovered at the
Hope Mine in 1864 with other areas following soon after. In 1867,
Philipsburg was founded. The period of greatest prosperity for the
mining camps of this area was from 1881 to 1893, during which time
the Granite Mountain Mine was most productive, and the largest ore
bodies of the Bi-Metallic Mines were uncovered.
The tailings at the Douglas Creek Site originated from mine workings
at the Bi-Metallic and Granite Mountain Mines located approximately
one mile east of the site. The Granite Mountain and Bi-Metallic
Mines are located approximately 2.5 miles southeast of Philipsburg
on the steep western slope of Granite Mountain. Although they were
located on the same ore shoot and controlled from the beginning
by practically the same interests, they were worked separately,
each with its own reduction plants, until a consolidation was effected
in 1898, after which the mines operated as one (USGS, 1913).
The Granite Mountain property was originally located in the fall
of 1872, but allowed to lapse periodically until July 6, 1875, when
the claim known as the Granite Mountain Lode was located. Charles
D. McLure acquired the title in 1880. Prior to this time, little
development at the mine had occurred. Originally, the ore was milled
at the Algonquin Mill located 1.25 miles northwest of the mine at
Hasmark. As exploration reached greater depth and the ore became
of higher grade, a dry-crushing stamp mill with a chloridizing roasting
furnace was built at the mine. Soon after, a larger mill was built,
which provided a total of 80 stamps. From 1885 to 1892, the mining
company was extremely prosperous and produced $20,000,000.00 in
silver and gold. A third mill with 100 stamps was built 1.5 miles
south of the mine at Rumsey. This mill was connected to the mine
by a wire tramway, and the railroad at Philipsburg was extended
a distance of 7.7 miles to the mill. During the same period, a tunnel
was driven 8,500 feet from Rumsey toward the mine.
The Bi-Metallic Mining Co. was organized in 1882, and its plant
was similar to that of the Granite Mountain Co. A 100-stamp chloridizing
mill was built at the Bi-Metallic Site on Douglas Creek approximately
1.25 miles above Philipsburg. This was connected by rail with the
railroad from Philipsburg to Drummond and by wire tramway with ore
bins at the hoist house. Water was supplied to these mills by a
ditch from Fred Burr Lake located three miles east of the Granite
Mine. The production of the mine from 1883 to 1893 totaled approximately
$6,000,000.00. Due to the declining price of silver, the mine was
shut down in 1893 and remained closed until the consolidation with
the Granite in 1898.
Extensive improvements were made after the consolidation. An 8,850-foot
tunnel from the canyon of Douglas Creek to the mine was completed.
This tunnel drained the Bi-Metallic Mine at a depth of 1,000 feet
and the Granite at a depth of 1,450 feet and greatly reduced the
cost of pumping. A subsidiary organization, the Montana Water, Electric
Power & Mining Co., built the Flint Creek Dam and a hydroelectric
power plant, which formed what is now known as Georgetown Lake,
to supply the mines and mills with 1,100 horsepower. A 300-ton concentrator,
built below the collar of the Bi-Metallic shaft, was the last notable
improvement. From 1898 to 1904, production at the mines was steady
at approximately $1,000,000.00 annually. In 1901, the company employed
300 men and produced 250 tons of silver ore per day. The mines closed
in 1905 due to declining silver prices and decreasing value of the
ore. The mines were then reopened in 1906 above the drain tunnel
(USGS, 1913).
The mines were worked from five drift tunnels, two deep shafts,
and the Douglas Creek tunnel. The Granite shaft was approximately
1,550 feet deep, and the Bi-Metallic shaft was approximately 1,800
feet deep. The vein was stoped as far as 2,600 feet below the surface,
and the drifts and crosscuts had a total length of more than 20
miles (USGS, 1913).
USGS 1913 - U.S. Geological Survey, 1913. Geology and Ore Deposits
of the Philipsburg Quadrangle, Montana, Professional Paper 78, Written
by William Harvey Emmons and Frank Cathcart Calkins, 1913.
Pre-Restoration Photos? No
Design Narrative:
Tailings pond #1 (TP1) is a large uncontained tailings pond
located at the west end of the site. Douglas Creek bisects the pond
with the majority of the tailings situated on the north side of
the creek. In the past, a dam composed of logs and tailings was
present at the west end of TP1; at present, this has been breached
where Douglas Creek flows through. The face of the dam, as well
as the channel of the creek within TP1, are extremely steep and
the channel is being actively eroded by the creek.
To determine the extent of metal, arsenic, and cyanide contamination
in the tailings, eleven test boreholes were drilled through TP1
to natural soil using a Geoprobe. In addition, two trenches were
excavated by hand in the south bank of Douglas Creek within TP1.
Based on the X-Ray Fluorescence (XRF) results, a total of sixteen
composite samples were submitted to the laboratory from TP1, which
included 5 for Target Analyte List (TAL) metals analyses, 3 for
Toxicity Characteristic Leaching Procedure (TCLP) metals analyses,
12 for acid base accounting (ABA) and SMP buffer capacity analyses,
and 4 for physical and agronomic characteristics. Both the original
XRF data and the metal laboratory results indicate that there are
three distinct tailings types present in TP1 and can be distinguished
by color and/or texture.
Maximum and Average Metals Concentrations in Tailings by XRF Analysis:
(Table
3)
Metals Concentrations (mg/kg) - Generalized Layers of TP1 by XRF
Analysis (Table
4)
Tailings pond #2 (TP2) is located approximately 1,000 feet
upstream of TP1 in Douglas Creek. TP2, like TP1, is a large uncontained
tailings pond bisected by Douglas Creek. In the past, TP2 had a
dam of logs and tailings on the west end, which has been breached
by Douglas Creek. The face of the dam and the banks of Douglas Creek
within TP2 are steep. Areas along the creek are being undercut,
and there is evidence of recent slumping of tailings into the creek.
A total of five test boreholes were drilled on the north side of
TP2 to natural ground using a Geoprobe. In addition, two boreholes
were excavated using hand augers on the south side of TP2.
Construction Narrative: Project tasks from July 27, 1998,
to October 30, 1998 included completion of stream diversions, construction
of sediment ponds, placement of tailings in the lower tailings impoundment,
and construction of a portion of the overexcavation/consolidation
area at TP2 during this time period.
At the beginning of December 1998, DEQ and Mungas agreed that Mungas
could complete the project, during the winter, instead of shutting
things down, if they started immediately and worked through the
winter and spring months. Mungas began work to complete the project
on December 17, 1998. Mungas crews worked more or less continuously,
depending on weather and conditions, until January 12, 2000. At
that time, all work was completed, except for mulching, willow plantings,
and fencing.
At two locations, tailings located within the Douglas Creek floodplain
were excavated, removed from the floodplain, and consolidated to
one side of the creek. Two consolidation areas were created; these
areas included one on the south side of the creek at the lower impoundment
(TP1) and one on the north side of the creek at the upper impoundment
(TP2). Both consolidation areas were graded and covered with a geomembrane,
a drainage layer and two feet of cover soil. A new stream channel
was constructed through the excavated areas. Run-on control channels
were constructed around the consolidation areas to divert surface
water.
Presence of shallow groundwater in the tailings impoundments, construction
of the consolidation areas presented challenges for long-term stability
of the facility. At TP1, a buttress was constructed to insure slope
stability. The buttress consisted of overexcavated and recompacted
tailings along the north toe of the consolidation area, underlain
by a groundwater interception drain (geocomposite). Additional groundwater
interception drains were added to the design during construction
to accommodate groundwater in the tailings. These drains, consisting
of perforated pipe, drain rock, and geotextile, were placed in the
drainages that had originally cut their way through the tailings
from the south to the north.
At TP2, the presence of groundwater and saturated, loose tailings,
required that all of the tailings on the south side of the creek
be overexcavated and recompacted in lifts to form the consolidation
area. Prior to replacing the materials, the entire area was underlain
by a geocomposite to intercept groundwater.
Areas where tailings were removed received a minimum of one foot
of cover soil. All disturbed areas were seeded, fertilized, and
mulched.
The reconstruction of the Douglas Creek stream channel was accomplished
by constructing steps and pools in the new channel using on-site
and imported rocks and boulders. The floodplain was constructed
by wrapping seeded cover soil in a woven coir fabric. Willows were
to be planted in the fabric. Grade control structures, consisting
of a valley-wide trench filled with large rock, were installed at
grade changes in the stream to prevent major grade and alignment
changes. The stream side of both consolidation areas was protected
with riprap and overlain with cover soil.
Three separate seed mixtures (Table
5) were used. Seed Mix #1 for the south-facing slopes and general
reclamation areas such as the flat areas and reclaimed roadways
and applied at a rate of 46 pounds per acre; Seed Mix #2 was specifically
formulated for the north-facing slopes and applied at a rate of
53.5 pounds per acre; and Seed Mix #3 was formulated specifically
for the riparian area (reclaimed areas within the floodplain of
Douglas Creek) and applied at a rate of 30.5 pounds per acre. The
following application rates for seed are based on the drill seeding
method. When the broadcast seeding method or the hydraulic seeding
method is used, the application rates listed below shall be doubled
at no additional cost to the Owner.
Construction Photos: Yes
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| Douglas
Creek during restoration (taken on August 10, 1998) |
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| Douglas
Creek during restoration(taken on September 15, 1998) |
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| Douglas
Creek towards end of restoration(taken on October 13, 1998) |
Services/Contractors Used:
Mungas Company, Inc.
P.O. Box 236
Philipsburg, MT 59858
Telephone: (406) 859-3203
Was this project successful? Yes
How was success determined? The Douglas Creek Tailings Site
has been reclaimed, and the environmental problems associated with
the tailings piles in the creek have been mitigated. The contaminant
sources responsible for most severely impacting the Douglas Creek
drainage have been isolated from the stream. The waste sources have
been consolidated in an engineered repository, which is protected
from erosion, infiltration, and direct contact.
Contaminated sediments have not been removed from Douglas Creek
downstream of the project site. Remaining sources below the site
include the adit discharge and waste rock dump approximately 0.5
mile downstream, which will continue to contribute metals to Douglas
Creek.
Supplementary Narrative: The project was completed generally
as specified. There were, however, several changes to the design
and additions to the project. Significant additions to the original
project included the following:
- addition of groundwater interception drains in the surface water
drainage channels at TP1;
- additional tailings overexcavation for buttress construction
at TP1;
- routing of run-off control ditch at TP1 to the east instead
of along the toe;
- reconstruction of the entire length of stream in the section
below TP2;
- additional tailings overexcavation for the consolidation area
at TP2;
- contractor's decision to add lime to saturated tailings as a
drying/placement aid; and changes in the topography of both consolidation
areas due to placement of more tailings and lime in TP1 and less
in TP2.
- additional work was planned at the site in the summer of 2000,
including willow plantings and mulching. The actual design life
of the repositories is not certain; consequently, long-term monitoring
and routine inspection and maintenance of the repositories will
be needed. Planting of pine seedlings and shrubs on the regraded
slopes (except for areas covered with geomembrane) should be considered
to allow these areas to naturally blend in with the surrounding
environment.
The following is a list of comments that addresses how the planning
and design for future reclamation projects should be addressed based
on lessons learned from the planning, design, and construction of
the Douglas Creek Tailings Reclamation Project.
- For projects with similar logistical considerations (i.e. consolidation
of waste in close proximity, volumes, and space constraints),
consider a longer contract time.
- Require watertight pipe and more stringent installation for
stream diversion pipes in anticipation of the potential need for
stream diversion longer than one season.
- Consider specification of lime amendment for saturated tailings
as a contingency for material drying and placement.
- Consider provisions in the contract to allow oversight personnel
the authority to limit worker exposure to dust, particularly lime
dust.
- Provide a table of ditch types, rock types, geotextile types
in the plans to help clarify specifications.
- Conduct more laboratory verification samples of geotechnical
borings. Include all laboratory data in bid documents.
Jack Yates, Reclamation Specialist, was responsible for coordination
of all planning phases for the project, as well as for providing
technical and regulatory review during the alternatives evaluation
and reclamation design process.
For more information on this project, contact:
Mr. Jack Yates
MDEQ/AMRB
1520 East Sixth Avenue
Helena, MT 59620
Phone: (406) 444-4957
Email: jyates@state.mt.us
Submitted by: Montana Department of Environmental Quality
Summarized by: Mari Reeves, Reclamation Research Unit, Montana
State University
Date: 01/29/01 |
