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EC’s Wetlands Program
Acid Mine Drainage (AMD) is a form
of water pollution caused by the presence of dissolved metals and other
contaminants in water that drains from active or abandoned mines. The most common type of AMD develops in areas
that have been mind for coal. On those
sites, pyrite (iron disulfide) is the main acid-generating rock mineral and
is often found in underground mine workings or mountains of waste coal
material, called culm banks. Culm banks and mine scarred sites
might look inactive and harmless, but they are actually a constant source of
pollution and contribute to the AMD problem.
Each time it rains or snows, water seeps through and rolls off these
areas, carrying metals and other contaminants into the ground water and
nearby waterways. The result of the
iron in the water can be seen along waterways as a yellow or orange sediment,
called “yellow boy”, and built-up on the steam floor and edges. In Pennsylvania alone, an estimated
3,000 miles of waterways are AMD-impacted.
A large percentage of those damaged waterways are in the minefields of
Northeastern Pennsylvania. The AMD
problem is a direct result of the mining that occurred in Pennsylvania
between the mid-1800s and mid-1900s, prior to environmental regulation. One alternative to treating AMD is the
use of constructed wetlands, which are considered to be a passive,
non-invasive, approach to remediating the problem. EC now has two wetland areas to treat
AMD. Both watersheds on EC land, the
Newport and Nanticoke Creek Watersheds, are tributaries of the Susquehanna
River, which is a major tributary of the Chesapeake Bay. By addressing problems in our own
watersheds, we benefit other watersheds downstream.
Students from Nanticoke High School measure iron
levels at the Phase I Wetlands In 1993, EC received a grant from
the U.S. Environmental Protection Agency (EPA) for $625,000 for a constructed
wetlands demonstration project to treat AMD. In 1995, additional
funding, in the amount of $300,000 was provided by EPA to extend the
project. Our Phase I wetland was a 0.3-acre
trial project to determine if this technique would be successful in treating
mine drainage. The wetland is located along, but adjacent to, Espy Run
in the Loomis Park area of Hanover Township. In this wetland, the water
flow is diverted into the constructed treatment cell, where iron particles
are removed through a natural oxidation process, which utilizes the natural
flow of the water through the cell.
The cell, or pond, contains natural plant life, such as Cattails and
other grasses, which act as filters catching the solid iron particles. The plants stop the iron from continuing on
through the water and hold them in the cell. Cleaner water then flows
back into Espy Run. Since the project's implementation,
water quality improvements at the Phase I site have been realized and
increased vegetation and animal life have been observed. The Phase II site, also in Hanover
Township and started in 1999, builds upon the success of the Phase I
project. This wetland treats a portion
of AMD outfall from the Askam Borehole into Nanticoke Creek. At its
peak flow, this outfall discharges an estimated 7,000 gallons per
minute. This 2.2-acre wetland is unique in
several ways: first, water is pumped uphill into the wetland
area for treatment; second, EC is uses an innovative device called a
"Maxistripper" to add oxygen to the water in an effort to increase
the oxidation rate of iron present in the mine drainage. The Phase II wetland consists of
two cells, a treatment cell and a polishing cell. The water is pumped into the treatment cell
from the borehole discharge, where it flows through the cell and natural
settling of the heavy iron particles occurs.
From the treatment cell the water flows into the polishing cell, where
plants and grasses act as filters to gather remaining iron particles. From this cell the water flows back into
the Nanticoke Creek.
Phase II Treatment Cell showing high
levels of iron in the water The Phase II project has shown
great success. This wetland treats up
to 500 gallons/minute of AMD. Analysis
has shown that this system removes approximately 95% of the iron from the
water. This project marks the first
time a Maxistripper and the constructed wetland treatment process is being
used to treat mine drainage in Northeastern Pennsylvania.
Phase II Polishing Cell
where additional iron particles are removed from water These projects are the culmination
of efforts by numerous key people and entities, including: EC, Eastern
Coalition for Abandoned Mine Reclamation (EPCAMR), Pennsylvania Department of
Environmental Protection, and Wilkes University.
Pictured above is the final outflow of treated water
from the wetland polishing cell as it flows back into the Nanticoke
Creek. |
