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Curlew Mine Tailings Pond Area Reclamation Project
September
16, 1996
November 16,
1996
Ravalli
Montana
46° 27' 49"
114° 10' 45"
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| Curlew
Pit Before Reclamation |
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Nearest town and distance: Victor, Montana lies approximately
3.5 miles to the southeast.
Location: The Curlew Mine is located adjacent to the Bitterroot
National Forest, approximately 15 miles east of the Montana/Idaho
border. The majority of the Curlew Mine Site is located in Sections
13 and 14, Township 8N, Range 21W. The elevation of the mine site
ranges from 3,500 to 4,000 feet above mean sea level. Big Creek
is the closest perennial stream to the mine site and is located
approximately 3 miles north of the site. Big Creek flows approximately
two miles east of the site before it empties into the Bitterroot
River. For an online GIS Environment with downloadable maps, go
to the Montana Natural
Resource Information System and pick the town name "Victor".
Select five mile radius, high priority mine sites, aerial photo
display, and zoom in on the mine site northwest of Victor.
Reclamation Costs: The total project cost was $1,514,310.82.
The total construction cost for the Curlew Reclamation Project
was $1,348,350.58. Envirocons original bid was for $1,296,072.00,
with three change orders totaling $52,278.58. To view these
Change Orders, click on the link below.
Change Orders: (Table
1)
The total engineering cost for the project was $165,960.24. Costs
associated with the preparation of the Reclamation Investigation
Work Plan (PRC EMI 1995a), Field Sampling Plan (1995b), and the
Final Reclamation Investigation Report (1996a) were $74,120.28.
Preparation of the Expanded Engineering Evaluation/Cost Analysis
(PRC EMI 1996b) was $10,555.61. Engineering design and bid specification
preparation cost (PRC EMI 1996c) was $28,847.64.
Construction inspection and management cost was $52,436.71.
Site Characterization and Engineering and Construction Management
Costs Table: (Table
2)
Five qualified bidders responded with bids ranging from $1,296,072.00
to $2,026,794.00. The engineers estimate was not provided to the
prospective bidders but was calculated at $2,173,520.00. The contract
was awarded to the low bidder, Envirocon, Inc., 500 Taylor Street,
Missoula, Montana 59802 (406) 523-1150. Subcontractors used by Envirocon,
Inc. for the project are shown in the subcontractor table below.
Subcontractors used by Envirocon, Inc.: (Table
3)
Project Sponsor(s): Montana Department of Environmental
Quality, United States Department of the Interior, Office of Surface
Mining and Reclamation.
Oversight Agency: Montana Department of Environmental Quality
- Abandoned Mine Reclamation Bureau.
Project Partners: (Table
4)
Reasons for Action: Site reclamation involved removing
those waste sources that were the principal sources of concern at
the Curlew Mine Tailings Pond Area (the tailings pond, mill site,
and tailings overflow areas and other designated areas). These wastes
were placed in a constructed repository. The contaminants of concern
were primarily arsenic, lead, and manganese. The maximum arsenic
concentration was 1,860 parts per million (ppm) and the mean detected
concentration was 858 ppm. The maximum lead concentration was 16,000
ppm and the mean detected was 1,870 ppm. The maximum manganese concentration
was 46,400 ppm and the mean detected was 15,700 ppm.
Objectives: The primary objective of the Curlew Reclamation
Project was to protect human health and the environment in accordance
with the guidelines set forth in the National Contingency Plan (NCP).
Specifically, the remedy selected must limit human and environmental
exposure to the contaminants of concern and reduce the mobility
of those contaminants to prevent impacts to local surface water
and groundwater resources.
History of Site: The Curlew Mine was first opened in 1897.
The Helena-Victor Mining Company operated the mine to produce gold,
silver, lead, zinc, and some copper. The mine included the Curlew,
Elizabeth, Pauline, and Granite Reef claims.
In 1928, the mine was described as having shafts up to 1,200 feet
long and was quite productive. The Elizabeth claim was described
as bearing gold, copper, and some zinc. In the mid-1930s, the mine
was operated by Hamilton-Victor Reduction Company; the mine remained
in operation until 1949. In 1967 the mine was re-opened by Roy Davidson,
Bill Elsasser, and Harold Ebbett of DEE Mines, Inc. for the primary
extraction of silver ore. In November 1968, the Champion Oil and
Mining Company purchased the lease to the Curlew Mine. In 1986,
the Curlew, Elizabeth, Granite Reef, Pauline, New Strike, and Moss
Back claims were sold to C.W. Mann and M.L. Mann. The claims were
then sold in 1992 to Delmar E. and Pamela D. Buckallew, current
owners of the Curlew Mine claims. Areas included in these claims
were the actual tailings ponds and mill site. Most of the tailings
overflow area was located on land owned by Roger and Diana Tout.
Pre-Restoration Photos? Yes, see photo at top of page.
Design Narrative: The Curlew Mine Site was divided into
two main areas: (1) the tailings pond area and (2) the upper mine
area. The tailings pond area encompassed the topographically lower,
less steep eastern portion of the site and contained the tailings
pond, the former mill site, and some scattered waste rock piles.
The upper mine contained four waste rock dumps, two open pit areas,
an operational gravel pit, and other disturbed soil areas.
Because the Old Mill Site had the highest lead and arsenic concentrations
at the project site, this portion of the site received priority
for reclamation activities. The Upper Mine Area was not a part of
this project.
Construction Narrative: The Curlew Mine Tailings Pond Area
Reclamation Project (Curlew Reclamation Project) consisted of providing
all labor, materials, earthwork, and incidentals necessary to construct
short access roads; improve existing access roads; clear and grub
the work site; and excavate, transport, and dispose of approximately
89,250 cubic yards of mill tailings and other materials in a constructed
waste disposal repository. The total footprint area of the repository
required to contain the specified wastes was approximately 4.5 acres
and resulted in a 6.3 acre repository cap. In addition, excavated
areas were recontoured, covered with topsoil, and revegetated. A
total of 32 acres of disturbed land was included in this reclamation
project. Specifically, there is a 7.05 acre tailings pond, 17.87
acre tailings overflow area, 6.3 acre repository cap, and 0.37 acre
mill site. To view a list of construction equipment, click the lcon
below.
Reclamation Construction Equipment: (Table
5)
Contaminated waste piles were placed in the repository. A gravel
stockpile was used to fill in a collapsed adit. Silt fencing was
installed near the waste piles and adjacent to an irrigation ditch
to control surface water runoff.
The repository was constructed on the boundary of land owned by
the Buckallews and Touts with approximately one-half the repository
on each landowner's property. The total footprint area of the repository
required to contain the specified wastes was approximately 4.5 acres
(results in a 6.3 acre repository cap). After the specified wastes
were loaded and compacted in the repository, a multi-layered lined
cap was constructed overlying the wastes, and the cap was seeded
and mulched. The excavated areas were backfilled, where necessary,
to contours matching the surrounding topography, and these areas
were also seeded. Excess clean soil originating from the excavations
was used as fill material in low-lying areas.
Ditches were constructed to divert runon and runoff away from the
repository. A 6-foot high woven-wire fence was constructed to surround
the repository to allow for the establishment of vegetation without
interference from livestock or wildlife. In addition, a 4-wire barbed-wire
fence was constructed around the entire perimeter of the reclaimed
tailings pond area, as well as around the mill site, to control
livestock grazing until the revegetation has established. Temporary
roads constructed at the site were obliterated and reclaimed immediately
after the reclamation activities were completed. Original site roads
remained intact and were improved to allow access for monitoring
the progress of the reclaimed areas (and maintenance when necessary).
Construction Photos? No
Suppliers/Products Used: Bentomat, Geonet geocomposite
Services/Contractors Used: The successful low bidder for
the construction project was Envirocon, Inc. (Envirocon) of Missoula,
Montana. The project manager for Envirocon was Greg Frame. The on-site
superintendent was Bill Whealy.
PRC Environmental Management, Inc. (PRC EMI) was assigned the responsibility
of engineering and preparing the reclamation specifications before
construction contractor selection. PRC's project manager for this
project was Dr. J. Edward Surbrugg. The project engineer was Gary
Sturm, P.E.
PRC performed the quality control inspection for the construction
of the project. Brian Goodman, Dan Shaffer, and Chris Reynolds acted
as primary construction inspectors. GMT Inc. of Missoula, Montana
performed all soil and tailings proctor analysis and also performed
all on-site densiometer testing required during repository construction.
Supplementary Narrative: Reclamation of the Curlew Mine
Tailing Pond Area was completed within the change order modified
contract period and well within the Engineer's cost estimate. Nevertheless,
during construction several issues developed that required extra
effort by the State, engineer, and contractor to resolve. These
issues included the large quantity of logging debris left after
the landowner logged the site, the cost and extent of dust control,
the definition of design quantities, the degree of subcontracting,
the use and control of hourly rental equipment (force account work),
the combining of pay items by the selected contractor, and the difficulty
and extra work involved in locating a suitable source of cover soil.
The quantity of logging debris left on site after logging was substantially
more than anticipated during project design. Ideally, site clearing,
if it is to be provided by the landowner, should have been completed
prior to the design of the project to insure that the bid documents
include an accurate representation of the project site. The other
alternative would have been to have the contractor complete the
clearing.
The cost and extent of dust control were a point of conflict between
the contractor's responsibility to provide a safe workplace and
the State's desire to reduce off-site migration of contaminants
while minimizing project costs. In addition, the cost of dust control
was negotiated after the bid opening. Had this cost been bid as
a unit cost, the probable bid cost would have been less than the
negotiated cost.
The issue related to the definition of design quantities can probably
be traced to the use of a similar term in U.S. Forest Service (USFS)
contracts. The USFS allows contractors to claim additional compensation
if the actual quantity of a design quantity pay item exceeds the
estimated bid quantity by more than 15 percent. The contractor on
this project believed that the language in the Paragraph 3.22 of
project specifications allowed a claim for additional compensation,
if the actual quantity of a major bid item exceeded the design estimate
by more than 25 percent. The engineer based the language of the
design quantity paragraph upon an earlier AMRB contract. In retrospect,
if a design quantity bid item is meant to be lump sum type bid,
then the language of this paragraph should be modified to more clearly
state that a design quantity bid item is not subject to modification.
However, due to the difficulty in accurately determining quantities
for some items on a project such as this, it may be more equitable
to allow a contract modification in those situations where an estimated
design quantity is substantially less than the actual quantity as
allowed by the USFS.
On this contract, well over 75 percent of the total contract was
completed by subcontractors. This degree of subcontracting created
both communication and project management challenges. Several agreements
were reached between the major subcontractor and adjacent landowners
without the knowledge or approval from the prime contractor. The
unauthorized agreements resulted in issues during project close
out that required significant effort by the State project manager
to resolve.
On future projects, out-of-scope work completed using equipment
rental rates should be based upon a pre-approved estimate of equipment
hours required to complete the proposed out-of-scope work.
The contractor combined two pay items in the contractors bid into
a single unit cost. While acceptance of this bid resulted in a substantial
savings to the State when compared to the second lowest bid, it
did cause misunderstanding later in the project. Bid acceptance
should have been contingent upon the contractor providing a separate
unit cost for each of the two bid items prior to contract award.
Substantial effort was also expended by the State and engineer
in approving off-site coversoil source areas. The major subcontractor
attempted to locate a less expensive source of coversoil than the
source assumed for purposes of preparing the original bid. As a
consequence, additional costs were incurred. To avoid this issue
in the future, the successful bidder should designate the coversoil
source area(s) prior to contract award.
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| Curlew
Pit Following Reclamation |
For more information on this project, contact:
Mr. Tom Mostad, Project Manager
Montana Department of Environmental Quality
Abandoned Minelands Reclamation Bureau
2209 Phoenix Avenue
P.O. Box 200902
Helena, MT 59620-0902
Ph: (406) 444-3846 Fax: (406) 444-1901
Available Documentation:
This evaluation report is supported by the following previous reports:
the Reclamation Investigation (RI) Report for the Curlew Mine Site
(PRC EMI 1996), The Reclamation Work Plan for the Remedial Investigation
of the Curlew Mine Site (PRC EMI 1995a), and the Field Sampling
Plan for the Remedial Investigation of the Curlew Mine Site, (PRC
EMI 1995b).
Submitted by: Montana Department of Environmental Quality
Summarized by: Mari Reeves, Reclamation Research Unit, Montana
State University
Date: January 19, 2001 |
