Mining Hydrogeology
Hydrogeologic studies are
an integral part of the modern mining industry, where investigations are required
for mine permitting, planning, and financing. The studies provide the necessary
information to assess baseline conditions, potential impacts due to mining, and
the effects of surface and ground water to the mining process.
Mine dewatering and water
control can be a major cost for a mining operation, and a potential threat to
personnel and equipment, as well as a limitation on operational flexibility.
Our team of scientists has extensive experience throughout the world in mine
dewatering, control investigations, and systems design. Detailed analyses of
existing wells, or exploration boreholes, local and regional geologic data,
and mine water inflows are used to design investigative programs. This helps
to minimize costs while still providing a sufficient level of confidence in
the quality of information for mine planning, development, and regulatory requirements.
Eon designs and installs dewatering systems using state-of-the art field testing,
analytical methodology, and modeling techniques to assess potential water inflows
and optimize design criteria.
Eon’s team can draw on
experience from work on over ninety mining or milling permits in eighteen states.
The permit activities have included, ground water and well analysis and modeling,
surface water flow rates and peak flows, average annual runoff, and ground water
recharge as well as the relationship of the ground and surface water regimes
to water related ecological systems and water rights evaluations. In addition,
the water resources related portions of nineteen Environmental Impact Statements
(EISs) or Environmental Assessments (EAs) have been completed for projects in
the continental United States, Alaska, the Czech Republic, and Kazakhstan. Eon
professionals have also contributed to the completion of Clean Water Act permit
applications, including various Sections of 404 Permits and wetlands issues.
Typical Mining Hydrogeology
Projects:
Name of Project: "Crown
Jewel EIS" Project work involved
the complete analysis and description of the ground and surface water regimes
for the Environmental Impact Statement for the proposed project. The area investigated
is located on over 4,000 acres of a geologically complex mountaintop with varied
surface water relationships encompassing five separate catchments. An extensive
review of existing ground water data was conducted and additional packer testing
recommended. Surface water hydrographs were constructed based on flow measurements,
and analyzed in conjunction with well hydrographs to relate the surface and
ground water regimes. A finite element model of the pre-project and post-project
ground water conditions was completed. The model calculated the ground water
inflow to the mine during and after the completion of mining and assessed the
potential mining impacts on ground water. Filling of the open pit after mining
was modeled, and the post-project water table and streamflow changes and the
potential ground and surface water related wetland hydrologic regime analyzed.
Accomplishments:
The Alumbrera Project
is a world class copper and gold mine located in northwestern Argentina. The
project is a joint venture between several international mining companies and
is scheduled to begin production in 1997. The project is located in an arid
region of Argentina where water resources are limited and are closely regulated
by local government agencies. Project work involved complete hydrologic consulting
services for the pre-feasibility, feasibility, and developmental phases of the
project. Hydrogeologic investigations were completed for the mine site, waste
disposal, tailings, water supply, and project facilities areas.
Work included the design
and implementation of hydrologic characterization studies involving the development
and installation of a baseline data monitoring system, water supply evaluation,
and potential impacts of mining operations on local water resources.
Several ground water flow
models were developed, based on baseline data, to assess potential impacts of
mine development on local water resources. The modeling studies involved potential
seepage from the open pit mine, waste rock disposal facility, and tailing impoundment
areas.
A preliminary study was
completed for the project to determine the potential ground water inflow into
the mine and the filling of the mine after operations. Potential water quality
of the pit water after filling was also analyzed. This study used available
pit wall rock geochemistry, chemical equilibrium modeling, and an "in house"
computer model developed to estimate pit water inflow and pit filling after
mining.
Accomplishments:
Client: U. S. Forest Service, Washington State Department of Ecology, and Battle
Mountain Gold Company
Name of the Project: "Alumbrera Project"
Client: Minera Alumbrera Limited, Argentina