This facility
was designed, permitted, and constructed to treat acid,
metal-bearing drainage from abandoned surface and
underground coal mines on property at the Pittsburgh
International Airport, near Clinton Road in Findlay Township,
Allegheny County. Construction was completed in Spring
2006. The system is preventing about 44,000 pounds of acid
and more than 6,000 pounds of metals annually, primarily
aluminum, from entering the West Fork of Enlow Run, a
tributary to Montour Run. This was a project of the Montour
Run Watershed Association with subcontractors N.A. Water
Systems and Quality Aggregates, Inc. The total funding was
$253,525 ($70,525 from a Pennsylvania Department of
Environmental Protection Growing Greener Grant; $73,000 from
an Office of Surface Mining Appalachian Clean Streams
Initiative grant; $100,000 from the Allegheny County Airport
Authority; and $10,000 from the Western Pennsylvania
Watershed Program).
The
system consists of two vertical flow ponds – basically
limestone- and mulch-filled basins that neutralize the
acidity and precipitate the dissolved aluminum.
No
formal wetland creation is included in this project;
however, existing wetland areas are utilized and enhanced in
the treatment process. This
system has reduced the acidity from about 300 to 14 mg/l
and the total aluminum from about 32 to less than 5 mg/l in
the discharge leaving the site. As a result, the health of
an estimated 2 ½ miles’ length of this stream has been
substantially improved.