AMD

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Greater Redstone Clearwater Initiative P.O. Box
632 Uniontown, PA 15401 www.grci.org
Working together to promote a healthy environment
in Fayette County.

• AMD

by Brian Chalfant OSM/VISTA Watershed Development
Coordinator
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Outline
1. How is coal formed? 2. What is mine
drainage? 3. What is AMD? 4. How is AMD
formed? 5. AMD Chemistry 6. Why is AMD a
problem? 7. What can be done about AMD? 8.
Resource recovery
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www.perryopolis.com/coal.shtml
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How is coal formed?
Even though coal has always been forming and can
be found in any era, there were several periods
in ancient history where land and climate
conditions were just right to allow vast swamps
to form over very long periods. One was during
the Carboniferous around 300 million years ago.
The second was in the Mesozoic particularly in
the Cretaceous and Jurassic periods. In North
America, coal was formed in both eras. The coals
in the Midwest and Eastern United States were
formed during the Carboniferous, while the coals
in the Western United States were formed in the
Mesozoic.
Argonne National Laboratory Chemistry
Division http//chemistry.anl.gov/carbon/coal-tuto
rial/coalgeneral.html
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How is coal formed?
Earth 300 million years ago The Carboniferous
Period
Prehistoric Pennsylvania was once located near
the Earths equator and had a hot, wet, tropical
climate.
Images from www2.nature.nps.gov/geology/usgsnps/pl
tec/scplseqai.html
Today, Pennsylvania is located in the northern
hemisphere and has a temperate climate.
Modern Earth
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Information from The AMD Avengers vs. The
Pollution Posse coloring book produced by the
Eastern Pennsylvania Coalition for Abandoned Mine
Reclamation (www.orangewaternetwork.org)
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Information from The AMD Avengers vs. The
Pollution Posse coloring book produced by the
Eastern Pennsylvania Coalition for Abandoned Mine
Reclamation (www.orangewaternetwork.org)
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www.dcnr.state.pa.us/topogeo/maps/map11.pdf
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From Goodbye Orange Water activity book produced
by the Environmental Education Center at St.
Vincent College (http//facweb.stvincent.edu/eec)
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www.perryopolis.com/coal.shtml
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www.perryopolis.com/coal.shtml
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From Goodbye Orange Water activity book produced
by the Environmental Education Center at St.
Vincent College (http//facweb.stvincent.edu/eec)
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From Goodbye Orange Water activity book produced
by the Environmental Education Center at St.
Vincent College (http//facweb.stvincent.edu/eec)
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What is mine drainage?
Drainage flowing from or caused by some form of
mining or earth disturbance (surface mining, deep
mining, coal refuse piles) that is typically
highly acidic with elevated levels of dissolved
metals.
It usually results from chemical reactions
between water, oxygen, and rocks containing metal
and sulfur-bearing minerals.
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What is AMD?

• The term AMD has been used to stand for
• Abandoned Mine Drainage
• Acid Mine Drainage

Mine drainage can occur from abandoned mining
sites and active mining sites. The nature of
mine drainage often varies greatly from site to
site, some are acidic and others are alkaline.
The characteristics of AMD are a function of
geology, hydrology, and mining technology
employed at each mine site.
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How is AMD formed?
Most AMD results from a series of complex
geochemical and microbial reactions that occur
when water and air come in contact with pyrite
(iron disulfide minerals) in coal, coal refuse,
or the overburden of a mine operation.
www.mineralminers.com/html/pytmins.stm
PYRITE Iron Disulfide (FeS2)
BITUMINOUS COAL
Pyrite, also known as fools gold, is commonly
found in rocks near coal seams.
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How is AMD formed?
Mine drainage can result from many types of
mining operations, including coal, copper, gold,
silver, zinc, lead, and uranium.
www.fs.fed.us/r6/wenatchee/holden-mine/
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How is AMD formed?
Metal-rich drainage can also occur in mineralized
areas where no mining has occurred.
http//northgateexploration.ca/expansion_files/ARD
.html
http//technology.infomine.com/enviromine/ard/Intr
oduction/Natural.htm
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How is AMD formed?
Many mines below the groundwater table have to be
actively pumped to prevent the mines from
accumulating water while in operation. After the
mines are abandoned, those below the groundwater
table begin collecting water and eventually
flood. AMD can exit mines through fractures in
overlying geologic strata or through existing
mine structures (bore holes, portals, constructed
drainages). AMD also emanates from unflooded
mines above the groundwater table and from mine
waste piles (gob piles).
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Gob piles
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AMD Chemistry
Four commonly accepted chemical reactions
represent the chemistry of pyrite weathering to
form AMD.
(1) Oxidation of pyrite by oxygen 2 FeS2 (s) 7
O2 (g) 2 H2O (l) ? 2 Fe2 (aq) 4 SO42- (aq)
4 H (aq) Pyrite Oxygen Water ? Ferrous Iron
Sulfate Acidity
While dissolved, ferrous iron and sulfate ions
are colorless and the water may look crystal
clear. This is not a particularly fast reaction,
just as the formation of rust occurs rather
slowly.
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AMD Chemistry
Four commonly accepted chemical reactions
represent the chemistry of pyrite weathering to
form AMD.
(2) Oxidation of ferrous iron to ferric iron by
oxygen 4 Fe2 (aq) O2 (g) 4 H (aq) ? 4 Fe3
(aq) 2 H2O (l) Ferrous Iron Oxygen Acidity
? Ferric Iron Water
This reaction is pH dependent, occurring slowly
at low pH (2 3) and several orders of magnitude
faster at higher pH (5). Certain bacteria
(Thiobacillus ferrooxidans and Leptospirrilum
ferrooxidans) increase the rate of this
reaction. This reaction is referred to as the
rate-determining step in the overall
acid-generating sequence.
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AMD Chemistry
Four commonly accepted chemical reactions
represent the chemistry of pyrite weathering to
form AMD.
(3) Hydrolysis of iron 4 Fe3 (aq) 12 H2O (l)
? 4 Fe(OH)3 ? (s) 12 H (aq) Ferric Iron
Water ? Ferric Hydroxide (yellowboy) Acidity
Formation of ferric hydroxide precipitate
(yellow-orange solid) is pH dependent, generally
solids form if pH is above about 3.5 but below pH
3.5, little or no solids precipitate.
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AMD Chemistry
Four commonly accepted chemical reactions
represent the chemistry of pyrite weathering to
form AMD.
(4) Oxidation of additional pyrite by ferric
iron FeS2 (s) 14 Fe3 (aq) 8 H2O (l) ? 15
Fe2 (aq) 2 SO42- (aq) 16 H (aq) Pyrite
Ferric Iron Water ? Ferrous Iron Sulfate
Acidity
Ferric iron is generated in reaction step
(2). This part of the overall reaction is cyclic
and self-propagating. It takes place very
rapidly and continues until either ferric iron or
pyrite is depleted. Note that ferric iron is the
oxidizing agent in this reaction, not oxygen.
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AMD Chemistry
Overall summary reaction 4 FeS2 (s) 15 O2 (g)
14 H2O (l) ? 4 Fe(OH)3 ? (s) 8 H2SO4
(l) Pyrite Oxygen Water ? Ferric Hydroxide
(yellowboy) Sulfuric Acid
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AMD Chemistry
Associated AMD reactions (among many others)
Acid dissolution of clays Clay H ? SiO2 Al3
Mg2 Ca2 Mn2
Acid neutralization by bicarbonate ion H HCO3-
? H2O CO2 Acid neutralization by hydroxyl
ion H OH- ? H2O
Aluminum hydrolysis Al3 3H2O ? Al(OH)3
3H Acid neutralization by calcite CaCO3 2H ?
Ca2 H2O CO2
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Why is AMD a problem?
AMD is considered the main pollutant of surface
waters in the Mid-Atlantic region of the United
States (Delaware, Maryland, Pennsylvania,
Virginia, West Virginia, Washington D.C.) by the
United States Environmental Protection Agency.
The Pennsylvania Department of Environmental
Protection estimates that over 3,000 miles of
Pennsylvanias 54,000 miles of streams are
polluted with AMD. This number is expected to
rise as more streams are inventoried. Various
organizations have estimated that it would cost
over 15 billion to address all of the
environmental impacts of mining activities in
Pennsylvania.
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Why is AMD a problem?
AMD is most often characterized by one or more of
four major components (1) Low pH (high
acidity) (2) High metal concentrations (iron is
most common) (3) Elevated sulfate
concentrations (4) Excessive suspended solids
and/or siltation
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Why is AMD a problem?
(1) Low pH (high acidity)
Acids in streams are a problem because they can
corrode metal pipes and structures, break down
concrete, and kill or stunt growth of plants and
other aquatic life. Acidic waters can also
dissolve metallic compounds of iron, manganese,
aluminum, copper, lead, mercury, and other metals
found in nearby rock or earthen waste
piles. Most aquatic organisms require net
alkaline, neutral pH conditions for survival.
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Why is AMD a problem?
(2) High metal concentrations (iron is most
common)
Metals such as iron, aluminum, and manganese can
be dissolved from mining sites through the action
of acid runoff or they can be washed into streams
as sediment. Many metals, though common, can be
toxic to fish and other aquatic organisms when
they are present in high dissolved
concentrations. Aluminum is toxic to humans
(though this is not well understood) and is
highly toxic to fish and other aquatic organisms.
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Why is AMD a problem?
(2) High metal concentrations (iron is most
common)
Iron and manganese cause problems with domestic
water systems (scaling, clogged pipes, orange
clothing). AMD polluted water cannot be used for
many industrial purposes. Dissolved iron and
iron precipitate can kill the aquatic biota that
fish feed on, thus reducing the overall fish
population. Iron forms a solid and coats the
bottoms of streams, smothering aquatic insects
and organisms that form the base of the food
chain. Iron precipitate can also clog the gill
structures of fish which will eventually lead to
increased fish mortality.
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Why is AMD a problem?
(3) Elevated sulfate concentrations
Sulfates can bond with water molecules to form
sulfuric acid or can attach to calcium ions to
form a gypsum sludge, adding to the problem of
excessive precipitates.
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Why is AMD a problem?
(4) Excessive suspended solids and/or siltation
Many people believe that AMD impacts on streams
are primarily chemical, but a significant threat
to water quality and aquatic organisms comes from
eroding soils at abandoned mining sites. Tiny
fly nymphs, insect larvae, and other organisms
that form the base of aquatic food webs can be
wiped out by heavy accumulations of soil and mine
waste particles that wash into streams after rain
events.
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Why is AMD a problem?
(4) Excessive suspended solids and/or siltation
Suspended silt particles can clog gills of fish
and smother fish eggs on the stream
bottom. Streams and rives muddied by silt and
other suspended solids also lead to higher costs
at municipal and industrial water treatment
plants and accelerated sedimentation in
reservoirs.
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Why is AMD a problem?
Ecological concerns Lowers water quality,
degrades habitats, and impairs aquatic
life. Economic concerns Restricts stream use for
recreation, public drinking water, and industrial
water supplies. Declines in valued recreational
fish species such as trout and decline in outdoor
recreation and tourism Lower property
values Unattractive to new residents and
businesses
Human health concerns Possible metal
toxicity Social concerns Feelings of apathy or
powerlessness with respect to environmental
pollution Aesthetic concerns Its ugly
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What can be done about AMD?
The type of AMD treatment that is most
appropriate depends upon the type of AMD
(chemical characteristics), the amount (flow),
and the space available for treatment.
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What can be done about AMD?
Pre-1980s Active Treatment

• Expensive chemical plants were the only way to
  treat AMD.
• In these chemical treatment systems, the acidity
  is buffered by the addition of alkaline chemicals
  such as calcium carbonate, sodium hydroxide,
  sodium bicarbonate, or anhydrous ammonia.

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What can be done about AMD?
Pre-1980s Active Treatment
Chemicals raise the pH to acceptable levels and
decrease the solubility of dissolved metals.
Metal precipitates form that are settled from the
solution. These types of active treatment
systems require regular maintenance and/or
addition of treatment chemicals as well as costs
associated with disposal of metal-laden sludge.
Therefore, active treatment is often
prohibitively expensive.
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What can be done about AMD?
1980 to the present Passive Treatment
Techniques developed since that time, beginning
in the late 1970s and collectively called
passive treatment, use natures own products to
treat AMD. The concept behind passive treatment
is to allow the naturally occurring chemical and
biological reactions that aid in AMD treatment to
occur in the controlled environment of the
treatment system, and not in the receiving water
body.
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What can be done about AMD?
1980 to the present Passive Treatment

• Treatment technologies that can function with
  little or no operation or maintenance (OM) over
  long periods of time.
• All systems will require some OM, but passive
  treatment systems can function for weeks, years,
  even decades with little interference from
  humans. The current standard is to operate for
  25 years with no major OM.
• The use of chemical addition and energy consuming
  treatment processes are virtually eliminated with
  passive treatment systems. As a result, OM
  costs for passive treatment systems are
  considerably less than for active treatment
  systems.

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What can be done about AMD?
Examples of passive treatment

• Ponds
• Wetlands (aerobic and anaerobic)
• Anoxic limestone drains a buried bed of
  limestone that water runs through in a controlled
  manner
• Vertical flow ponds and wetlands a
  pond/wetland that drains through the bottom,
  which is constructed of organic material and
  limestone
• Open limestone channels
• Diversion wells
• Limestone dosing
• Sulfate reducing bioreactors

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What can be done about AMD?
Ponds
www.facstaff.bucknell.edu/kirby/4ponds.html
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What can be done about AMD?
Wetlands
www.dep.state.pa.us/dep/deputate/minres/bamr/amd/s
cience_of_amd.htm
www.wvu.edu/agexten/landrec/passtrt/passtrt.htm
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What can be done about AMD?
Anoxic Limestone Drains
www.dep.state.pa.us/dep/deputate/minres/bamr/amd/s
cience_of_amd.htm
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What can be done about AMD?
Anoxic Limestone Drains
www.amrclearinghouse.org/Sub/AMDtreatment/Wetlands
Handbook.pdf
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What can be done about AMD?
Anoxic Limestone Drains
www.facstaff.bucknell.edu/kirby/ALDOLD.html
www.wvu.edu/agexten/landrec/passtrt/passtrt.htm
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What can be done about AMD?
Vertical Flow Ponds and Wetlands
www.dep.state.pa.us/dep/deputate/minres/bamr/amd/s
cience_of_amd.htm
www.wvu.edu/agexten/landrec/passtrt/passtrt.htm
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What can be done about AMD?
Vertical Flow Ponds and Wetlands
www.amrclearinghouse.org/Sub/AMDtreatment/Wetlands
Handbook.pdf
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What can be done about AMD?
Open Limestone Channels
www.dep.state.pa.us/dep/deputate/minres/bamr/amd/s
cience_of_amd.htm
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What can be done about AMD?
Open Limestone Channels
http//pa.water.usgs.gov/projects/amd/treatments.h
tml
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What can be done about AMD?
Open Limestone Channels
www.wvu.edu/agexten/landrec/passtrt/passtrt.htm
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What can be done about AMD?
Diversion Wells
www.dep.state.pa.us/dep/deputate/minres/bamr/amd/s
cience_of_amd.htm
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What can be done about AMD?
Diversion Wells
http//pa.water.usgs.gov/projects/amd/treatments.h
tml
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What can be done about AMD?
Limestone Dosing
www.wvu.edu/agexten/landrec/passtrt/passtrt.htm
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What can be done about AMD?
Sulfate Reducing Bioreactors
www.wvu.edu/agexten/landrec/02TFS/Gusek.pdf
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What can be done about AMD?
Usually passive treatment systems contain several
of the previous elements in series.
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What can be done about AMD?
www.facstaff.bucknell.edu/kirby/PassTreatmtMeth.ht
ml
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What can be done about AMD?
www.facstaff.bucknell.edu/kirby/PassTreatmtMeth.ht
ml
www.facstaff.bucknell.edu/kirby/0SCRAnewHome/Site4
2.html
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What can be done about AMD?
Each component and each passive treatment system
is suited for a particular purpose in a
particular type of water. Although there are a
few general rules about passive treatment, all
sites and situations are different. Therefore,
analytical sampling of the AMD is extremely
important in the selection of appropriate
treatment technologies.
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What can be done about AMD?

• In order to design successful passive treatment
  systems, the following information is necessary
• high, low, and average flow rates
• iron content and form (ferrous and ferric)
• aluminum content
• total acidity
• total alkalinity
• pH
• dissolved oxygen content
• site layout (topography and area available to
  construct treatment system)

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What can be done about AMD?
If AMD is net alkaline, usually only ponds and/or
wetlands are necessary to allow the metals to
precipitate.
If AMD is net acidic but does not contain
aluminum, dissolved oxygen, or ferric iron, an
anoxic limestone drain may be used to add
alkalinity to the water. The anoxic limestone
drain is usually followed by ponds and/or
wetlands to precipitate the metals, but metals
are not retained within the limestone.
If AMD is net acidic and contains aluminum,
dissolved oxygen, or ferric iron, anoxic
limestone drains cannot be used. In this case,
vertical flow ponds and/or wetlands are usually
used. These can be used in series with one
another to generate additional alkalinity if
necessary.
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What can be done about AMD?
www.wvu.edu/agexten/landrec/passtrt/passtrt.htm
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What can be done about AMD?
www.amrclearinghouse.org/Sub/AMDtreatment/Wetlands
Handbook.pdf
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Resource recovery
Potential for iron oxide recovery Hedin
Environmental and Iron Oxide Recovery, Inc. have
demonstrated that a marketable iron oxide product
can be produced from coal mine drainage. The
Phillips discharges are suitable for iron oxide
production and could produce between 750 1,000
tons per year of product. Production and
recovery methods developed by Hedin Environmental
and Iron Oxide Recovery, Inc. utilize the passive
precipitation of iron in specifically designed
sedimentation ponds. This approach may eliminate
long-term operation and maintenance concerns for
the treatment system.
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Resource recovery
Potential for iron oxide recovery To learn more
about iron oxide recovery and recovery of other
resources from mine drainage treatment systems,
follow the links below. Hedin Environmental www.h
edinenv.com Environoxide www.environoxide.com Fr
om orange streams to green buildings Congressman
John Murthas Resource Recovery
Page www.house.gov/murtha/res-reco/overview.htm S
outhern Alleghenies Conservancy www.saconservancy.
org
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References
If you want to learn more about AMD and what can
be done about it, check out the following
websites
The United States Environmental Protection Agency
Region 3 www.epa.gov/Region3/acidification/what_
is_amd.htm The United States Geological Survey
Coal Mine Drainage Projects in Pennsylvania http/
/pa.water.usgs.gov/projects/amd The Pennsylvania
Department of Environmental Protection Bureau
of Abandoned Mine Reclamation www.dep.state.pa.us/
dep/deputate/minres/bamr/amd/science_of_amd.htm B
ucknell University Carl S. Kirby www.facstaff.bu
cknell.edu/kirby/ West Virginia University
Agriculture and Natural Resources www.wvu.edu/age
xten/landrec/land.htm The Abandoned Mine
Reclamation Clearinghouse www.amrclearinghouse.org
Hedin Environmental www.hedinenv.com
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Greater Redstone Clearwater Initiative P.O. Box
632 Uniontown, PA 15401 www.grci.org
Working together to promote a healthy environment
in Fayette County.
Thanks for learning about the Greater Redstone
watershed! If youd like to learn more about the
Greater Redstone watershed and what you can do
help improve it,please contact the Greater
Redstone Clearwater Initiativeby writing to the
address above or by email through our website
(www.grci.org).