Section 319
NONPOINT SOORGE PROGRAM SOGGESS STORY
Addressing Abandoned Mine Discharges Allows Stream to Recover
Waterbodies Improved Elevated metal loads and low pH levels in acid mine
drainage (AMD) from abandoned coal mines had
degraded water quality in Pennsylvania's Little Coon Run. As a result, the Pennsylvania
Department of Environmental Protection (DEP) placed four segments of the stream (totaling
5.12 miles) on the state's 2004 Clean Water Act (CWA) section 303(d) list of impaired
waters. Implementing passive AMD treatment systems and plugging an abandoned
gas well improved water quality. Little Coon Run now meets state water quality criteria;
consequently, DEP intends to remove all four segments of Little Coon Run from the 2012
CWA section 303(d) list of impaired waters.
Problem
Little Coon Run flows north through Clarion County
and discharges into Coon Creek, which in turn
empties into the Tionesta Reservoir in northwestern
Pennsylvania's Forest County (Figure 1). Surface
and subsurface coal-mining activities took place
in this region between the 1940s and 1960s.
Improperly reclaimed coal-mining areas in the
watershed left minerals such as iron-sulfide (pyrite)
exposed to the elements. Pyrite chemically reacts
with water (provided by rain, stormwater runoff or
groundwater) and produces acidic (low-pH) water,
which can enter local waterbodies.
For decades AMD has impaired Little Coon Run's
aquatic life designated use because of low pH and
elevated manganese, iron and aluminum loads.
Low pH and elevated metal loads place stress
on aquatic organisms, sometimes to the point
at which the organisms perish and the streams
become lifeless. In August 1999 a Pennsylvania
DEP biologist performed a Statewide Surface
Water Assessment Program Survey at the mouth
of Little Coon Run, which identified AMD-related
impairments (low pH and elevated metal loads) and
a lack of pollution-intolerant macroinvertebrates.
As a result, the Pennsylvania DEP placed four
segments of Little Coon Run on the state's 2004
CWA section 303(d) list of impaired waters for
low pH and high levels of manganese. To meet
the state's standards, the pH must stay above
6.0 standard units and manganese concentrations
may not exceed 1.00 milligram per liter (mg/L).
Little Coon
Run Watershed
Figure 1. Little Coon Run is in northwestern
Pennsylvania.
Project Highlights
AMD sources are typically addressed through a
variety of remediation approaches. For example,
the alkalinity of the polluted streams is increased to
neutralize the acidity of the water and reduce metal
loads, enabling aquatic organisms to return. Each
site, however, can be unique; while one metal might
be a problem at one site, another might be a bigger
problem at another site. To restore AMD-impaired
streams, efforts are usually directed toward
reducing the metal loads and neutralizing pH by
adding alkalinity to the discharge.
Pennsylvania's Growing Greener Program funded
a Watershed Assessment and Restoration Plan on
Little Coon Run in 2003. Three discharges were
identified as the most significant sources of AMD
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Figure 2. Remediation projects to address AMD have significantly
improved the water quality in Little Coon Run.
in the watershed and were targeted for treatment.
Two of the discharges were abandoned gas wells
that were best suited for being plugged. The
third source, on State Game Lands #24, required
construction of a passive treatment system
consisting of an anoxic limestone drain, a settling
pond and a constructed wetland. Because the
passive AMD treatment sites need to be inspected
periodically, the project included constructing nearly
a mile of permanent access road. The well plugging
and passive system were completed in 2007.
Results
According to the restoration project's final report,
sample results from the mouth of Little Coon Run
demonstrate significantly improved water quality
(Figure 2). In 2001, before the restoration projects
were completed, the average pH was 4.5 standard
units. The average pH at the same location in 2008
was 6.2, and the final reading in September of that
year was 7.0 standard units, which meets state
water quality standards for attaining the designated
use of aquatic life.
Metal concentrations have also shown significant
improvement. The largest decrease was in
manganese, which dropped 70 percent between
2001 and 2008; aluminum declined 26 percent.
Iron and aluminum concentrations had begun
Figure 3. Biologists found this mottled sculpin, a pollutant-
intolerant fish species, near the mouth of Little Coon Run.
to decline before the treatment projects were
completed and were already attaining water
quality standards in 2001. Monitoring data
collected in September 2008 showed manganese
levels of 0.22 mg/L, which are well below the state
standard of 1.00 mg/L.
In addition, fish collected in a recent (2010) survey
indicate water quality has improved as a result of
remediation efforts. For example, the 2010 survey
found a mottled sculpin (Figure 3), a pollution-
intolerant species that is not frequently found in
streams with elevated levels of pollutants.
Partners and Funding
Partners involved in the restoration of Little
Coon Run include Pennsylvania DEP's Bureau of
Abandoned Mine Reclamation, Pennsylvania Game
Commission, Farmington Township, Western
Pennsylvania Coalition for Abandoned Mine
Reclamation and Hedin Environmental. The projects
were funded by Pennsylvania DEP's Growing
Greener Program ($40,000 for the watershed
assessment) and the Office of Surface Mining's
Appalachian Clean Streams Program (more than
$400,000 for constructing the passive treatment
system and plugging the wells). Farmington
Township provides ongoing operation and
maintenance of the passive treatment system.
I
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-11-001W
March 2011
For additional information contact:
Joe Kelly
Pennsylvania Department of
Environmental Protection
717-783-2404
Joseph kel@state. pa. us
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