CTEC Newsletter
and Technical Comments
Montana
Pole and
Treating Site
Silver Bow Creek/
Butte Area Site
West
Camp/Travona Shaft
Warm
Springs Ponds
Butte
Priority Soils
(see
a .PDF file of the EPA's proposed plan for BPSOU by clicking
here.)
Berkeley
Pit
Rocker
Timber Framing & Treating Plant
Stream
side Tailings
Lower
Area 1
Superfund Contacts
SILVER BOW CREEK/BUTTE AREA SITE
Silver Bow
Creek west of Butte before reclamation work began.
The boundary of the Silver Bow Creek/Butte Area site begins above
Butte, near the Continental Divide, and extends westward along
Silver Bow Creek to and including the Warm Springs Ponds (a treatment
area). The site covers about 40 miles of stream and stream side
habitat. Silver Bow Creek was used as a conduit for mining, smelting,
industrial and municipal wastes for more than a hundred years.
Vast mine tailings deposits are found along the creek. These
deposits contain elevated levels of metals and have been dispersed
over the entire flood plain. The Silver Bow Creek/Butte Area
Site is one of four contamination areas, jointly known as the
Clark Fork Basin Sites. Others (with separate fact sheets) are
the Milltown Reservoir Sediments, Anaconda Company Smelter, and
Montana Pole & Treating site. All are on the Environmental
Protection Agency (EPA) National Priorities List.
THREAT AND CONTAMINANTS
Wind-blown particles, ground
water, surface water and soils are contaminated with arsenic
and other heavy metals, including copper, zinc, cadmium and lead.
Silver Bow Creek and the Clark Fork River contain metals from
Butte to Milltown. The tailings, dispersed along the creek and
river, severely limit aquatic life forms and have caused fish
kills in the river. Potential health threats include direct contact
with and accidental ingestion of contaminated soil, surface water,
ground water or inhalation of contaminated air particles.
CLEANUP APPROACH
The site is being addressed in several stages: immediate actions and seven long-term remedial phases focusing on the West Camp/Travona Shaft Area; Warm Springs Ponds; Butte Priority Soils; Berkeley Pit; Rocker Timber Framing and Treating; Stream side Tailings; and Lower Area I. Some of these separate actions involve parts of a single operable unit, such as the Travona Shaft and the Berkeley Pit, which are parts of the Mine Flooding operable unit.
RESPONSE ACTIONS
In Walkerville, Montana, a small
incorporated town just north of Butte, EPA and Potentially Responsible
Parties (PRPs) excavated and stabilized approximately 300,000
cubic yards of lead contaminated soil from mine waste dumps.
These actions were completed in 1988. Contaminated soil was removed
from four earthen basements and 23 residential yards. Concrete
basements were constructed, and 18 inches of clean fill and sod
were placed in the yards. South of Butte, at Timber Butte, approximately
40,000 cubic yards of contaminated soil were moved to a temporary
on-site repository in 1989.
Contaminated soil was removed from two residential yards. Clean
soil was placed on the excavated areas and revegetated. Atlantic
Richfield Company (ARCO), a PRP, removed highly contaminated
materials in the Rocker Timber Framing and Treating Area, under
state supervision. Arsenic wood treating wastes and contaminated
soils and wood chips were hauled to a licensed hazardous waste
disposal facility. Equipment and debris were consolidated on
the site and buried. Major areas of the site were covered with
topsoil and seeded. Between 1990 and 1991, 24 waste dumps containing
approximately 100,000 cubic yards of soil were either capped
or removed. In addition, a railroad bed and seven residential
yards were reclaimed.
In late 1991, removal activities
began at the Colorado Smelter site. Elevated levels of arsenic
and lead were detected in on-site soils. Under a Unilateral Order,
the Potentially Responsible Parties conducted the removal activities.
Approximately 40,000 cubic yards were moved to a temporary on-site
disposal area. In 1992, removal activities were conducted at
the Anselmo Mine Yard/Late Acquisition Silver Hill areas. Elevated
levels of arsenic and lead were detected in on-site soils. The
PRPs conducted this removal under a Unilateral Order.
In 1993, further removal activities were conducted in Walkerville
to address four additional dump areas because of the elevated
levels of lead. In 1994 and 1995, 12 more waste dumps were addressed.
These dumps were either removed or capped in place. EPA is presently
negotiating to complete plans for removal activities for contaminated
railroad beds on the Butte Hill. Also, the PRPs are under Unilateral
Order to complete removal activities addressing storm water problems
on the Butte Hill.
West
Camp/ Travona Shaft Area:
In 1989, under EPA supervision, the PRPs addressed rising mine
waters in the West Camp/Travona Shaft area by constructing a
pumping and piping system, which connected to a municipal sewer
line on Iron Street. Mine water has been pumped to the Metro
Plant at a rate of approximately 160,200 gallons per minute since
early 1990. Pumping continues to keep the water level below the
control level of 5,435 feet to prevent flooding of basements
and discharge of contaminated ground water to the alluvial aquifer
and Silver Bow Creek.
Warm Springs Ponds: The three Warm Springs Ponds cover
2,400 acres at the confluence of Silver Bow, Mill, Willow, and
Warm Springs creeks. The ponds were constructed by the Anaconda
Company between 1911 and 1959 in an attempt to trap tailings
before they entered the Clark Fork River, which begins immediately
below the ponds. An investigation of the ponds was completed
in 1989.
Public comments were extensive and led to a decision to speed
up cleanup plans in the Mill-Willow Bypass. The bypass contained
approximately 200,000 cubic yards of tailings and contaminated
soils that were a principal cause of fish kills. In 1990 and
1991, the tailings and contaminated soils were excavated and
consolidated in Pond 3. The ponds contain 19 million cubic yards
of tailings and contaminated soils. The selected remedy to cleanup
the two active and one inactive Ponds included:
- Removing the Mill-Willow Bypass tailings and placing them on top of tailings in the berms of Pond 3;
- Reinforcing all ponds and upgrading their treatment capabilities;
- Dry closing Pond 1 by covering it with a cap and vegetation;
- Wet-closing (flooding tailings areas) Pond 2; and
- Enlarging Pond 3 to handle a 100-year flood event.
Ground water interception trenches were installed to divert ground water to Pond 3 for treatment. The PRPs designed the selected remedy in late 1991, and began cleanup activities in mid 1992; construction was completed in 1995. EPA's five year review of the remedy is complete and undergoing public review. EPA concluded that although Warm Springs Ponds (the focus of the review) has not always performed as dictated by the ROD, the remedial action has been protective of human health and the environment.
Butte Priority Soils: The Butte Priority Soils Operable Unit has been divided into two phases. Phase I, an expedited Response Action has addressed source areas by removing waste dumps, railroad beds, or other related mine wastes. These source areas were adjacent to or up gradient of receptor areas (residential yards, gardens, parks and playgrounds). The local government is running a lead abatement program that addresses children with elevated blood lead levels; residential yards with lead levels over 1,200 parts per million; residential homes with lead drinking pipes; indoor dust contaminated with lead; and interior and/or exterior lead paint. This is a five-year program with oversight by EPA.
For Phase II, an investigation
will assess the actions already taken, all other areas of contamination,
storm runoff, and future land use problems in Butte and Walkerville.
Berkeley Pit: EPA and the state of Montana are concerned about
rising levels of contaminated mine water in the pit that could
eventually migrate into the shallow aquifer and into Silver Bow
Creek.
The investigation of the Berkeley Pit has been completed and
the remedy calls for:
- Permanent control of surface inflow into the Pit;
- Maintenance of the water level in the Berkeley Pit system;
- Continued control of the West Camp/ Travona System;
- Implementation of an extensive compliance monitoring program; and
- Implementation of institutional controls to restrict access to contaminated bedrock aquifer waters, as well as increased public education efforts.
The PRPs started inflow control
(average 3.8 million gallons per day) in April 1996. Controlling
inflow has cut the rise rate in the Berkeley Pit by 50 percent.
This inflow is treated with lime and used as makeup water in
the present mining operation.
Rocker
Timber Framing and Treating Plant: EPA, working with the Montana Department of Environmental
Quality, selected the remedy for the Rocker Timber Framing and
Treating Plant in late 1995. The remedy addresses human health
risks from potential exposure to contaminated soils and ground
water. Approximately 41,000 cubic yards of soils and source materials
that contributed to groundwater contaminated with arsenic were
excavated and treated on the site.
Highly contaminated ground water was treated in place using an
iron solution to remove arsenic from the ground water. A contingency
plan is available to contain the arsenic ground water plume,
if it cannot be treated or migrates, thus threatening drinking
water wells. During the term of the remedy, a ban exists on expanded
ground water development within a quarter mile of the site. An
alternative source of water has been provided for the community
to meet its increasing water demands due to growth.
The ground water ban is needed to prevent accelerated movement
of the existing arsenic plume into uncontaminated groundwater
supplies. Surrounding wells and Silver Bow Creek are being monitored
to see if they remain unaffected and to document trends in contaminant
concentrations. Pilot scale tests in 1996 produced arsenic levels
almost 1000 times lower than sampled levels. Treatment of arsenic
contaminated ground water in the field dropped arsenic concentrations
from as high as 20,000 milligrams per liter (ug/l) to less than
30. The State standard for arsenic in drinking water is 18 ug/l.
Full-scale cleanup began in spring 1997 and was completed in
the fall of the same year. Close communication is being maintained
with the Rocker Water Board and the Butte Silver Bow County Health
Department.
Stream side Tailings: In November 1995, the Montana Department
of Environmental Quality and EPA selected a remedy for the Stream
side Tailings area. Tailings impacted soils that can't be safely
treated and stabilized in place will be removed from the flood
plain of Silver Bow Creek and placed in repositories. Lime amendment
in place and revegetation will be used for tailings impacted
soils not removed. Fine-grained in-stream sediments located in
Silver Bow Creek will be removed and placed in repositories with
the excavated tailings impacted soils. Remedy design on the upper
portion of the stream is complete, and construction began in
fall 1999. A portion of the reconstructed stream has water flowing
again since June 2000. An Explanation of Significant Differences,
which adjusts the remedy to some extent, has been released and
is available from the state of Montana.
Lower
Area I: EPA conducted
an Expedited Response Action for Lower Area I. Removal of the
Department of Defense manganese stockpiles (approximately 245,000
tons) occurred in the summer and fall of 1992. Removal of the
mine tailings (Colorado and Butte Reduction) began in the spring
of 1993 and was completed in 1997. An estimated 1.4 million cubic
yards of tailings was removed to a repository. The tailings were
originally transported by rail to the Opportunity Ponds near
Anaconda, but in the final year, the tailings were transported
by truck to the Clark Tailings in Butte, and the closure of the
Clark Tailings was integrated with the closure of the old Butte
Silver Bow landfill.
A ground water collection and treatment system will be installed
as the final step to this action. An investigation also is taking
place at the Butte Soils area to determine if any further cleanup
actions are necessary. Capture and treatment of contaminated
ground water is expected to occur in the future. Final cleanup
decisions will be part of the Priority Soils Record of Decision.
Legal Actions: A unilateral order was issued to ARCO,
Montana Resources, ASARCO, MRI, ARCO, and Dennis Washington to
enforce the Remedial Design and Remedial Action implementation
for the Berkeley Pit project. The State issued a Unilateral Order
requiring ARCO to remove highly contaminated materials in the
Rocker Timber Framing and Treating area. In 1989, EPA issued
an Administrative Order on Consent to the PRPs to either discharge
the West Camp water to the Butte Metro Plant and meet all pre-treatment
requirements or to build a treatment facility that meets classification
discharges for toxic metals and drinking water standards for
arsenic.
ENVIRONMENTAL PROGRESS
Numerous completed cleanup actions at the Silver Bow Creek/Butte
Area Site have reduced human exposure to metals and other health
threats. However, EPA has determined that high concentrations
of metal in soils and drainage from the smelter still pose risks
that will be addressed in future cleanup actions.
To download the 2006 EPA ROD for the Butte Priority Soils Operable Unit, click here. or contact CTEC for a copy on CD.
The Berkeley Pit Public Education Committee prints a quarterly tabloid called Pit Watch that contains infromation about the science and policies surrounding the Berkeley Pit. To see the web site version, visit www.pitwatch.org.
