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Maxville Tailings Removal and Londonderry Mine Reclamation
Project
October 1,
1996
Construction
was completed except for mulching and seeding on December
3, 1996. Mulch and seed were applied and site work was completed
on May 20, 1997.
Location: Maxville, Montana. For directions
to Maxville, click on the Icon. For an online GIS environment
with downloadable maps, go to the
Montana Natural Resource Information System and pick the
town name "Maxville".
(Supplement
1)
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| Maxville
Tailings/Londonderry Mine Before Reclamation |
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Site Cleanup Summary: The primary elements of concern at
this abandoned hard rock mine site included three waste rock dumps,
one acid producing tailings pond, and one adit discharging contaminated
water into a nearby creek. The tailings pond had also intermittently
been used by Granite County as a solid waste disposal dumpsite.
Arsenic, lead, and copper were determined to be creating adverse
ecological effects for fish, wildlife, and plants in the area. Arsenic
was present at concentrations high enough to create a human health
risk for the current open space land use. Although cyanide leaching
was used in the mining process, concentrations of cyanide
in the tailings material were found not to significantly exceed
background levels in nearby soils. Road access was limited for a
large portion of the site, and consequently access roads and a bridge
over Flint Creek had to be built in order to reclaim the area. One
of the three waste rock dumps and both of the tailings ponds were
excavated, moved to a modified RCRA landfill and capped in place.
One of the waste rock piles was regraded, lime was incorporated
to 12 inch depth, and the dump was recontoured, fertilized, and
revegetated. The smallest waste rock dump was not an acid producer
and was becoming well vegetated, thus it was not reclaimed.
Water from the adit discharge remains untreated at this time.
History of Site: The historic Maxville Mining District has
produced relatively large quantities of silver, gold, zinc, lead,
copper, and manganese. The first lode was discovered at the Hope
Mine in 1864 with other nearby areas following soon after. The most
active period of mining in this area was from 1881 to 1893. In 1887,
the Northern Pacific Railroad completed the Philipsburg branch,
which passed within 70 yards of the Londonderry Adit, allowing ore
to be moved to a smelter via rail. The nearby, larger Durand Mine
began operation in 1892. The Londonderry Mine is described as being
active as early as 1913, when five rail cars of ore were shipped
yielding $6.50 of gold and 50 ounces of silver per ton of ore.
From 1921 to 1924, the Londonderry Mine was operated by the Maxville
Gold, Silver and Development Company, but the property may have
been idle. From 1926 to 1927, the company expanded operations by
installing a 100-ton per day floatation mill on public land located
approximately 50 meters north of the adit. Facilities were also
constructed on adjacent private land (east side of Flint Creek).
With the new mill site in place, the Londonderry Lode expanded to
1,900 feet of horizontal adit tunnel and 300 feet of vertical shaft
with 1,500 feet of workings on three levels. Ore was moved to the
surface with rail mounted ore cars. The ore was loaded into a series
of hoppers and transferred to the nearby railroad for transport
to the smelter. The winter of 1930 was the last known year of production.
Little is known of the method of mining or where the ore was shipped
for processing.
By the early 1930's, the mine was leased to Mr. Richard Valiton.
In April 1936, a mineral survey was completed to patent the Londonderry
Lode to Mr. W.E. Albright. This survey shows that Mr. Albright had
five tunnels, two raises, and one cut within the proposed patent
area. In 1938, the Londonderry Lode claim was willed to Mr. Albright's
daughter in probate following his death. In 1939, the Londonderry
Lode claim passed from federal to private ownership as allowed under
the 1872 General Mining Laws. President Franklin D. Roosevelt granted
Patent #1100918 to Ms. Alta M. Patten of University City, Missouri,
in 1939. The Londonderry Adit is not shown in this patent because
the adit entrance is located 31.7 feet to the east on BLM (public)
lands. The Londonderry Adit entrance remains in federal ownership.
In 1988, contaminated water was observed discharging from the Londonderry
Adit into Flint Creek. Water quality data indicated high levels
of arsenic, bicarbonates, barium, calcium, cobalt, iron, magnesium,
manganese, cadmium, and zinc in the discharge. Associated waste
rock along the west bank of Flint Creek also contained elevated
levels of heavy metals and was contributing sediment into Flint
Creek.
In 1990, the BLM hired an environmental consultant to complete
a Site Inspection (SI) and evaluate hazardous materials at the site.
The consultant inspected the site and assigned a U.S. Environmental
Protection Agency (EPA) site score of 30.7, making the site eligible
for the National Priority List (NPL). The consultant completed a
Potential Hazardous Waste Site, Site Inspection Report (EPA Form
2070-13) and notified the EPA of the potential presence of hazardous
wastes at the site. To aid in the reclamation effort at the site,
the BLM attempted to identify any Potentially Responsible Party
(PRP). The site is now abandoned, with Mrs. Richard Valiton shown
as the current owner of the patented Londonderry Lode claim. In
1993, the Londonderry Mine adit and associated private tailings
areas were included on the Montana Department of State Lands (now
the DEQ) Abandoned Hardrock Mines Priority Sites List.
Maxville/Londonderry Mine Reclamation Costs: (Table
1)
Construction Change Orders: (Table
2)
Project Sponsors/Partners: (Table
3)
Reasons for Action: In general, the area is fairly continuously
forested and is important habitat for a variety of big game animals,
fur bearers, waterfowl, and birds including: mule deer, elk, moose,
black bear, beaver, bobcat, and various ducks/geese and mountain
grouse. Flint Creek is considered a Class 3 sport fishery which
annually receives 192 recreational fishing days per mile.
Arsenic, silver, cadmium, copper, iron, mercury, lead, tin, and
zinc were detected at the site at concentrations significantly above
background.
According to the human health risk assessment, the primary pathway
and contaminant of concern (COC) was arsenic via soil ingestion/dust
inhalation. Human ingestion of arsenic via contaminated water or
fish was a significant secondary pathway. Reclamation alternatives
focused on addressing these exposure pathways.
The environmental risk assessment concluded that lead, copper,
and arsenic in soil, water, and stream bed sediments at the site
were probably causing adverse health effects to fish, wildlife,
and plants. The ecologic risk characterization demonstrated that
contaminants at the site constituted a probable adverse ecologic
effect via all three exposure scenarios and justified appropriate
cleanup.
Objectives: The reclamation project was designed to reduce
human, livestock, wildlife, and environmental exposure to the contaminants
of concern, as well as reduce the mobility of the contaminants to
limit impacts to the local surface water and groundwater.
Pre-Restoration Photos? Yes, see photo at top.
Design Narrative: Three waste rock dumps and two tailings
ponds were reclaimed at the site. Waste rock dumps 1 (WR1), 3 (WR3)
and 4 (WR4) contained 71,000 yds3, 1,300 yds3,
and 750 yds3 of waste material, respectively. Dumps WR1
and WR3 comprised acid producing material, pH of 3.4 and 4.8 for
WR1 and pH of 3.5 for WR3. WR1, the largest dump, was actively eroding
into Flint Creek for about 400 feet along the bank. Dumps WR1 and
WR3 contained antimony, arsenic, barium, copper, iron, lead, mercury,
silver, and zinc, at greater than three-times background levels;
WR3 contained elevated cadmium concentrations as well. Dump WR4
was vegetated with grasses, willow, alder, weeds, and several lodgepole
pine trees, whereas the other 2 dumps were largely barren. Although
WR4 contained elevated concentrations of arsenic, lead, mercury,
and silver; the dump did not appear to be a major acid producer,
as the pH of a sample from it was 6.4. All three rock dumps had
low organic matter contents; samples contained 0.2 to 1.1% for WR1,
0.4% for WR3, and 1% for WR4. None of the waste rock dumps were
classified as a resource conservation and recovery act (RCRA) hazardous
wastes based on the toxicity characteristic leaching procedure (TCLP)
analysis. All three waste rock dumps were inaccessible by vehicles
because the only road into the remote site came from the other side
of the creek. Access roads and a temporary bridge had to be built
to allow access into the remote dump sites.
Supplemental Dump Description: (Supplement
2)
Vegetation Survey Table: (Table
4)
Two tailings ponds were located at the site, the first was much
smaller than the second. The second tailings pond, tailings pond
#2, (TP2) was a large uncontained tailings impoundment located on
the east side of Flint Creek. An unknown quantity of municipal solid
wastes were intermixed with TP2. In the past, Granite County used
the site as a solid waste disposal dumpsite, but the site was closed
to dumping in the late 1980's. When the dumpsite was operational,
the disposed solid waste was routinely covered and mixed with tailings.
The smaller tailings impoundment, TP1, was located approximately
100-feet north of TP2. The volume of TP2 was estimated at 15,700
cubic yards. Concentrations of the following metals were significantly
elevated above background (>3X) in the tailings: antimony, arsenic,
cadmium, copper, lead, mercury, silver, and zinc. The pH of three
separate composite samples of TP2 ranged from 3.9 to 6.7. The tailings
material had organic matter content that ranged from 0.2% to 1.8%.
TP2 was also not classified as a RCRA characteristic hazardous waste.
Tailings Description: (Supplement
3)
Contaminants of Concern Concentration Tables: (Table
5)
Maxville Bats: (Supplement
4)
Construction Narrative:
The two acid producing waste rock dumps (WR1 and WR3) and both
tailings ponds (TP1 and TP2) were excavated, consolidated, and disposed
of in a constructed repository. The repository was constructed at
the former Maxville solid waste dumpsite located on the east side
of Flint Creek (out of the floodplain of Flint Creek). The total
area of the repository was approximately 1.13 acres. The repository
cap consisted of a geosynthetic clay liner (GCL), geocomposite drainage
layer, and a fertilized, seeded, and mulched cover soil layer. Improvements
of existing roadways, construction of a temporary bridge across
Flint Creek, and construction of a gravel ramp over a set of railroad
tracks were all required to allow access for the required equipment
to construct the project. Several unstable wooden buildings and
structures were dismantled and burned, disposed of, or salvaged
by the BLM.
After the specified wastes were excavated and consolidated, the
excavations were backfilled with imported cover soil. The backfilled
areas were recontoured to match the topography of the surrounding
area, and the backfilled areas were then fertilized, seeded, and
mulched. Waste sources that were not excavated and hauled to the
repository (waste rock dump # 3 [WR3]), were reclaimed in place.
WR3 was regraded to match the existing contours (2H:1V maximum slope);
lime was then incorporated into the upper 12 inches of the graded
material, and imported cover soil was placed over the lime-amended
waste rock and this was fertilized and seeded. Erosion control mat
was used to minimize erosion potential on all reclaimed slopes steeper
than 2.5:1. Erosion control mat was installed over WR3 and the south
half of WR1. Areas steeper than 2.5:1 slope were hydroseeded/hydromulched;
areas with slopes less steep than 2.5:1 were mulched via crimped
straw and were drill seeded. Riparian Areas received seed mix at
21.5 pounds per acre. Semi-Riparian Areas received 22.5 pounds per
acre. WR3 and the reclaimed roadways received 27 pounds per acre,
and the Waste Consolidation Cap and surrounding areas received 21.5
pounds of seed per acre.
A stream protection structure, consisting of silt fence, two continuous
rows of straw bales (one row stacked on top of the other), and sand
bags for anchoring the structure, was used to minimize the impact
of excavation activities on Flint Creek. After each area had been
reclaimed, ditches were constructed to prevent water from running
onto the reclaimed areas, and woven wire fences were installed to
keep livestock and wildlife out of the newly reclaimed areas. The
fences will be removed when the vegetation is well established on
each reclaimed area.
The majority of the roads constructed for reclamation purposes
were reclaimed after construction was completed. The main site access
road remained intact to allow for maintenance and monitoring of
the site. The temporary bridge over Flint Creek and the ramp over
the railroad tracks were removed when construction was completed.
The contractor utilized from three (3) to fourteen (14) employees
on the job site at various times; installation of the stream protection
structure was the most labor-intensive task involved with the project.
A total of twenty (20) different workers performed different tasks
at the site; this number includes the subcontracted seeding crew
as well as a Montana Conservation Corp (MCC) crew who were on-site
for one week filling sand bags, backfilling an open adit, and assisting
with installation of the stream protection structure.
Major Equipment List: (Table
6)
Construction Photos? No
Was this project successful? Yes
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| Maxville
Tailings/Londonderry Mine Site After Reclamation |
How was success determined? The site remedial objectives
were achieved by removing the solid media waste sources at the site
(two uncontained tailings piles and one waste rock dump in close
proximity to Flint Creek), containing these wastes via an impermeable,
modified RCRA cap, and re-establishing vegetation over the remaining
disturbed areas at the site.
The contaminant sources responsible for most severely impacting
the Flint Creek drainage have been removed from their unstable locations.
The waste sources have been disposed of in an engineered repository,
which is protected from erosion, infiltration, and direct environmental
contact. Additionally, grading and revegetating of WR3 should significantly
stabilize this source by providing an erosion-resistant, vegetated
surface that provides protection from surface water and wind erosion
and reduces net infiltration through the contaminated media by increasing
evapotranspiration processes.
Supplementary Narrative: The following list of comments
(in no particular order) 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 Maxville
reclamation project.
- Provide detailed specifications for the site topographic map.
The specifications should provide for the required scale, contour
interval, coordinate system, exact area involved, and the establishment
of several benchmarks throughout the work area so that the survey
can be reproduced in the field. The Maxville site map (which was
developed from a Global Positioning System [GPS] survey) lacked
the resolution and precision required for detailed design work.
Conventional topographic mapping is preferable over GPS mapping
for detailed design work.
- For reclamation projects of comparable scope and work conditions
(e.g., elevation, remoteness, terrain, etc.), the preferred alternative
should be selected by about mid-March, so that the detailed design
can be completed and the project can be advertised by mid-May,
and construction can begin by July 1. The start of the Maxville
project was delayed due to pilot-scale testing being conducted
on the adit discharge during the spring of 1996; consequently,
completion of the project was delayed until late November when
winter was in full-force at the site, causing postponement of
the final phases of the project until the following spring.
For more information on this project:
The DEQ/MWCB Project Manager, Ben Qui�ones, Solid and Hazardous
Waste 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.
Available Documentation: (Supplement
5)
Submitted by: Montana Department of Environmental Quality
Summarized by: Mari Reeves
Date: February 19, 2001
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