Assessment and prediction of acid rock drainage (ARD) quality
has become an important aspect of mine planning activities for
predicting the potential future environmental liabilities in mine
facilities.
S.E.T. geochemists evaluated ARD quality at numerous mine sites
as well as the quality of potential toe seepage from tailing impoundments,
heap leach piles, and mine waste rock piles. S.E.T. is well-qualified
and experienced in predicting mine pit lake hydrology and quality.
Our team is also regularly asked by our clients to provide third
party reviews of other consultants' geochemical modeling efforts.
For geochemical predictions, S.E.T. utilizes geochemical models
such as PHREEQ, MINTEQ, WATEQ equilibrium models as well as the
EQ 3/6 model which incorporates reaction kinetics.
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ARD Mitigation and Treatment System Analysis and Design
S.E.T. geochemists have
prepared numerous ARD mitigation plans and developed design criteria
for passive treatment systems for mine facilities in the Western
U.S. Based on the design criteria developed, S.E.T. engineers have
designed passive treatment systems (i.e., crushed limestone cells)
to treat ARD.
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Natural Attenuation
S.E.T. is one of the
leading experts in the Western U.S. for natural attenuation of inorganic
constituents in saturated and unsaturated media. Natural attenuation
is a naturally occurring process in the environment that acts without
human intervention to reduce the mass, toxicity, mobility, and concentration
of constituents in those media. These in-situ processes include
the following:
- Dispersion
- Dilution
- Sorption
- Precipitation/co-precipitation
- Neutralization
- Volatilization
- Chemical and Biological Stabilization or Destruction
Soils and rock formations of the Western United States are know
to contain high levels of neutralization potential, which promotes
natural attenuation of ARD. S.E.T. has developed numerous laboratory
and pilot-scale tests and used computer modeling to evaluate the
effectiveness of geochemical processes listed above. The evaluations
are conducted to quantify the natural attenuation potential as
the ARD either infiltrates through an unsaturated material (i.e.,
vadose zone), or flows through a saturated zone (i.e., aquifer).
At a mine site in Arizona, S.E.T. developed a conceptual geochemical
profile of the vadose zone soils under an unlined ARD settling
pond. At this site, the S.E.T. team demonstrated that the ARD impact
in the last 70 years was minimal and that the soils between the
pond bottom and the groundwater table still contained 1000 years
of natural attenuation potential before the groundwater can be
impacted.
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Radiochemistry
S.E.T. team members have
extensive experience with radionuclide monitoring and evaluations
for both soil and groundwater. Ongoing projects include evaluation
of radionuclide groundwater/soil results and sampling programs which
also included sampling protocol training for client field personnel.
S.E.T. has also presented several short courses on radionuclides
in groundwater, which were sponsored by major mining companies for
state agency and public presentation. In addition, S.E.T. team members
are periodically retained by legal counsel or state and federal
mining associations (on behalf of the mining industry) to evaluate
EPA reports and proposed rules. Subjects of interest include uranium
in minerals associated with copper deposits, the concentration of
radioactive materials in copper extraction and beneficiation, along
with reporting exemptions for radionuclide releases.
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Research and Development
S.E.T. provides research and development services to the natural
resources industry for the following technology developments:
