Final environmental impact statement : Marigold Mine expansion project

540 Pages·2001·152 MB·English

by  United States. Bureau of Land Management. Winnemucca Field Office

BLM LIBRARY
United States Department of the Interior
88066683 Bureau of Land Management
Winnemucca Field Office
Winnemucca, Nevada March 2001
Final Environmental
Impact Statement
Marigold Mine Expansion Project
blmubrary
BLDG 50, ST-150A
DENVER FEDERAL CENTER
P.O. BOX 25047
DENVER, COLORADO 80225
BLM MISSION STATEMENT
The Bureau of Land Management is responsible for the stewardship of our public lands. It is
committed to manage, protect, and improve these lands in a manner to serve the needs of the
American people for all times.
Management is based upon the principles of multiple use and sustained yield of our nation's
resources within a framework of environmental responsibility and scientific technology. These
resources include recreation, rangelands, timber, minerals, watershed, fish and wildlife,
wilderness, air and scenic, scientific, and cultural values.
BLM/WN/PL-01/009+1610
United States Department of the Interior
BUREAU OF LAND MANAGEMENT
Winnemucca Field Office
5100 East Winnemucca Boulevard
Winnemucca, Nevada 89445
[phone]
http://www.nv.blm.gov/winnemucca
In Reply Refer To:
1793/3809
NV-020
March 9, 2001
Dear Reader:
This Final Environmental Impact Statement (FEIS) for the Glamis Gold, Marigold Mine
expansion, prepared by the Bureau of Land Management (BLM), Winnemucca Field Office
is submitted for your review and comment.
The FEIS is based on a Plan of Operations submitted to the BLM under 43 CFR 3809
regulations. The FEIS analyzes the direct, indirect and cumulative impacts related to
expansion of existing mine facilities (pits, overburden dumps & heap leach pads) and
development of the 8-North and 5-North deposits, including construction of new pits, new
overburden disposal areas, additional heap leach facilities, new tailing impoundment,
drainage diversions, haul and exploration roads, and ancillary facilities
Alternatives analyzed include the Proposed Action, No Action, and the 8-South Partial Pit
Backfill alternative. The Plan of Operations, Draft EIS (DEIS), and applicable technical
reports are available for review at this office.
Comments were received on the DEIS during the 60 day comment period, which ended April
10, 2000. Public meetings were held on the DEIS in Winnemucca and Battle Mountain,
Nevada on March 8, 2000 and March 9, 2000.
This FEIS contains in its entirety the analysis originally presented in the Draft EIS (issued
February 11, 2000), with all text changes highlighted. Also included in the FEIS are
responses to comments received during the public comment period on the Draft EIS.
Comments on this FEIS will be accepted until the close of business April 9, 2001. Written
comments or questions may be directed to Jeff Johnson, Environmental Coordinator, at the
Bureau of Land Management, Winnemucca Field Office, 5100 East Winnemucca Boulevard,
Winnemucca, Nevada 89445.

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FINAL
ENVIRONMENTAL IMPACT STATEMENT
MARIGOLD MINE EXPANSION PROJECT
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Lead Agency: U.S. Department of the Interior
Bureau of Land Management
Winnemucca Field Office
Project Location: Humboldt County, Nevada
Comments on this EIS Jeff Johnson
Should be Directed to: EIS Project Manager
Bureau of Land Management
Winnemucca Field Office
5100 East Winnemucca Blvd.
Winnemucca, NV 89445
[phone]
Date Draft EIS Filed with EPA: February 11,2000
Date Final EIS Filed with EPA: March 9, 2001
ABSTRACT
Glamis Gold, Inc./Rayrock Mines, Inc., doing business as Glamis Marigold Mining Company (GMMC) proposes
to construct new facilities and expand existing gold mining operations at the Marigold Mine in Humboldt County,
Nevada. The mine is located on public and private lands near Interstate Highway 80 approximately 13 miles
northwest of Battle Mountain and approximately 40 miles southeast of Winnemucca.
The proposed Marigold Mine Expansion Project would disturb approximately 462 acres of private land and
255 acres of BLM-administered public land, for a total of 717 acres. The proposed project would include:
expansion of two pits and development of two new pits; expansion of two waste rock dumps and development of
two new waste rock dumps; addition of lifts to three existing heap leach cells, addition of one cell to an existing
leach pad, and development of a new heap leach facility; expansion of the tailings impoundment and construction
of a new tailings impoundment; haul roads, solution ponds, growth media stockpiles, exploration drill pads and
access roads, and diversion channels; and realignment of a public access road (Buffalo Valley Road) and power
line. The Proposed Action would extend the mine operations an additional 5 years through 2007.
This Final Environmental Impact Statement provides responses to comments received by BLM during
the public comment period on the Draft Environmental Impact Statement (Draft EIS). The Draft EIS
analyzed the environmental effects of the Marigold Mine Expansion Project, the 8-South Partial Pit
Backfill Alternative, and the No Action Alternative.
Responsible Official for EIS:
j Terry A. Reed
Field Office Manager
Winnemucca Field Office
'
SUMMARY
SUMMARY ALTERNATIVES
This environmental impact statement (EIS) analyzes
PROPOSED ACTION
the direct, indirect, cumulative, and residual
environmental impacts of the Proposed Action,
Glamis Marigold Mining Company (GMMC) proposes 8-South Partial Pit Backfill Alternative, and the No
to construct new facilities and expand existing gold Action Alternative. The alternatives are described in
mining operations in Humboldt County, Nevada. The the following sections.
mine is located on public and private lands near
Interstate Highway 80 (1-80) approximately 13 miles 8-South Partial Pit Backfill Alternative
northwest of Battle Mountain and approximately
40 miles southeast of Winnemucca, Nevada. GMMC
The 8-South Partial Pit Backfill Alternative would
has been operating the Marigold Mine since 1988.
include the backfilling of the existing 8-South Pit with
Historical mining in the proposed project vicinity dates
waste rock originating from the proposed 8-North Pit.
back to 1927. To date, approximately 1,349 acres
This alternative would eliminate the need to construct
have been disturbed.
the 8-North Waste Rock Dump (85 acres) thereby
decreasing total disturbance to 632 acres.
A Plan of Operations Amendment and Reclamation
Plan for the proposed Marigold Mine expansion was
No Action Alternative
submitted to the Bureau of Land Management (BLM)
in August 1998. Current mine facilities consist of a
Under the No Action Alternative, currently permitted
series of pits, waste rock dumps, a heap leach pad
operations at the Marigold Mine would cease after
and associated processing plant, a tailings
2001, with final reclamation extending 10 years
impoundment, access and haul roads, and ancillary
beyond closure. Additional minerals in the project
facilities. The proposed Marigold Mine Expansion
area would remain undeveloped, and no construction
Project would disturb approximately 462 acres of
or expansion of mine pits, waste rock dumps, heap
private land and 255 acres of BLM-administered
leach pads, tailings impoundment, or other ancillary
public land, for a total of 717 acres. The proposed
facilities would occur.
project would include: expansion of two pits and
development of two new pits; expansion of two waste
IMPORTANT ISSUES AND IMPACT
rock dumps and development of two new waste rock
CONCLUSIONS
dumps; addition of lifts to three existing heap leach
cells, addition of one cell to an existing leach pad, and
development of a new heap leach pad; expansion of
A small number of issues were raised during scoping
the tailings impoundment or construction of a new
for this EIS. Public scoping meetings were held in
tailings impoundment; haul roads, solution ponds,
Battle Mountain and Winnemucca, Nevada, on
growth media stockpiles, exploration drill pads and
October 6 and 7, 1998, respectively. Additional issues
access roads, and diversion channels; and
were identified by resource specialists during the
realignment of a public access road (Buffalo Valley
preparation of the EIS. These issues along with their
Road) and power line. The Proposed Action would
impact conclusions are presented below. Impact
extend the mine operations an additional 5 years,
conclusions include the implementation of mitigation
through 2007. Reclamation and monitoring would
measures that have been identified. These measures
continue through 2017.
are presented in detail in Chapter 3.0 of this EIS for
each affected resource.
SUMMARY
Water Resources and Geochemistry Issue: Long-term stability of diversion
channels.
Issue: Formation of a pit lake as a result of
Conclusion: The diversion channels would be
mine development and impacts to
designed and constructed to
wildlife from degraded water quality.
accommodate a 100-year storm
Conclusion: The construction and development of event.
the 8-North Pit would not occur unless
the price of gold is $400 per ounce or Issue: Degradation of surface water from
heap leach expansion and tailings
greater. If the pit is developed, it
impoundment.
would only be mined to a depth that
would not intercept groundwater; no
pit lake would form. Conclusion: Perennial streams and springs do not
exist within the project area.
Issue: Impacts to surface water and Intermittent creeks exist within the
project area and convey water only
groundwater levels resulting from pit
during seasonal snowmelt or heavy
dewatering and groundwater use for
mine operations. precipitation events. Heap leach
facilities and the tailings impoundment
Conclusion: Based on the evaluation of historic would be designed to contain potential
contaminants (e.g., cyanide solution).
and current groundwater level data
These facilities would be closed
within the project vicinity, hydrologic
impacts to springs or intermittent systems with no release of solutions
to areas outside the facilities.
creeks located in the project vicinity
Therefore, no impacts to surface
are not anticipated. Springs and
water are expected.
intermittent creeks located in the
project vicinity would not be affected
since the water source for the springs Issue: Degradation of groundwater quality.
and intermittent creeks is not
hydrologically connected with the Conclusion: Geochemical testing indicates that
bedrock aquifer. No pit dewatering is waste rock from the mine does not
anticipated during mining. Water used have a potential to generate acidic
for the proposed mine operations seepage. Seepage from waste rock
would be obtained from the Lone Tree dumps may be elevated in arsenic
and mercury, but would not be
Mine and supplemented with the
water from water supply wells in the expected to reach groundwater due to
project vicinity. The source of water the low permeability of the soil and the
for the water supply wells is mainly depth to groundwater (about 80 feet).
the bedrock aquifer, whereas the The current tailings remediation plan
source of water for the springs and at the existing tailings impoundment is
intermittent creeks is shallow expected to reduce seepage to
alluvium and surface flows resulting groundwater and keep any impacts to
from runoff. groundwater within State drinking
water standards. A new tailings
impoundment may be constructed if
the 8-North and 5-North Pit deposits
are mined. This impoundment would
have a low permeability base
SUMMARY
consisting of compacted clay or a infestations during mine operation and
geosynthetic liner. reclamation.
Issue: Utilize native species in reclamation
Air Quality seed mixes.
Issue: Cumulative impacts to air quality. Conclusion: The interim seed mix would include
crested wheatgrass, which is a
non-native species. This species
Conclusion: The annual and 24-hour contributions
would be used since it readily
from the mine sources would not
establishes on disturbed sites and
cause the air quality in the region to
degrade below National or State reduces soil erosion. The
ambient air quality standards. permanent reclamation seed mix to
be used during reclamation would
consist primarily of native species.
Vegetation Resources These mixes were developed as a
result of past and current revegetation
studies and successful reclamation
Issue: Loss of wetland or riparian areas
conducted at the mine site.
resulting from the construction of the
diversion structures.
Issue: Reclamation of the proposed tailings
impoundment.
Conclusion: Wetlands or riparian areas would not
be affected within or adjacent to the
Conclusion: GMMC has committed to reclaim the
project area.
proposed tailings impoundment area
after mining operations cease. After
Issue: Potential long-term impacts to the
reclamation has been completed, the
Humboldt River and wetlands near its
area would be monitored for several
terminus.
years to evaluate reclamation
success.
Conclusion: The project area does not include
perennial creeks or rivers. Therefore,
no impacts to the Humboldt River or
wetlands located adjacent to the river Wildlife and Fisheries Resources
would be affected by mine expansion.
Potential impacts to groundwater and Issue: Wildlife habitat disturbed or lost.
surface water would be limited to the
mine site and immediate vicinity. Conclusion: No riparian habitat would be affected.
Loss of upland habitat would not
Issue: Minimize the spread of noxious exceed 717 acres. The value of
weeds. habitat lost would be low to moderate,
due to the proximity of the project to
Conclusion: GMMC has committed to use seed past and present disturbances and
that has been tested for noxious activities and the availability of native
weed seeds prior to application, habitats in the surrounding region.
and control or eradicate any weed Approximately 656 acres of disturbed
habitat would be reclaimed.
SUMMARY
Issue: Loss of mule deer winter range. Special Status Species
Conclusion: A total of 717 acres of mule deer
Issue: Potential impacts to special status
winter range would be removed for
species.
the life of the project.
Conclusion: With the exception of sensitive bat
Issue: Direct mortalities, habitat
species, no sensitive plant or wildlife
fragmentation, and animal
species would be affected. The
displacement.
implementation of the committed
environmental protection measures
Conclusion: Direct mortalities would be limited.
would minimize impacts to sensitive
Incremental habitat fragmentation
bats.
would occur and terrestrial wildlife
would be displaced for the life of the
project.
Range Resources
Issue: Impacts to resident and migratory
Issue: Loss of available grazing land and
birds.
interference in ranch management
activities resulting from the
Conclusion: Potential effects to breeding birds
construction of the range perimeter
(e.g., passerines, raptors) could occur
fence.
from incremental habitat loss,
disturbance to nesting habitat, and
Conclusion: Construction of the range perimeter
increased noise and human presence,
fence would remove 5,762 acres of
particularly from mine exploration
rangeland available for grazing
activities. These impacts would be
resulting in the temporary loss of
minimized by the applicant committed
288 animal unit months. A permanent
protection measures. Effects to
loss of 6 animal unit months would
upland game birds would be minor,
result after mine reclamation.
based on relative habitat value, bird
species occurrence, and committed
Issue: Construction of the diversion
protection measures.
structures may affect water available
for livestock.
Issue: Measures to prevent wildlife exposure
to cyanide solutions on heaps, in
Conclusion: Segments of Trout and Cottonwood
solution channels, and ponds should
creeks located within the project area
be developed.
have intermittent flows and are used
by livestock as seasonal water
Conclusion: Potential impacts from cyanide
sources. The construction of the
ingestion would be low, since bird
diversion structures would alter the
netting would be installed over the
configuration of these creeks.
solution ponds and GMMC would
However, these creeks would still be
monitor heap leach pads to avoid
available for seasonal use by livestock
the puddling of cyanide solution
during mine operation. In addition,
Ames and Mud springs are located
within the general vicinity of the
IV