PAINT TWP. - The Clarion County Park has seen many "visible" improvements over the past few years and one improvement is not so visible but is just as important.

The Clarion County Park in Paint Township was built on a reclaimed coal strip mine site mined in the 1970s and 1980s by Glacial Minerals. As with many old mines in the area the Glacial mine's legacy was acid mine drainage (AMD).

Adjacent to the park is an AMD site.

Mine drainage is formed when pyrite (an iron sulfide) is exposed and reacts with air and water to form sulfuric acid and dissolved iron.

The acid runoff further dissolves heavy metals such as copper, lead, and mercury into groundwater or surface water.

Acid mine drainage also affects the wildlife living within the affected body of water.

Aquatic macroinvertebrates living in streams or parts of streams affected by acid mine drainage show fewer individuals, less diversity, and lower biomass.

Many species of fish also cannot tolerate the pollution.

The Clarion Conservation District was awarded an Environmental Stewardship and Watershed Protection (Growing Greener) Grant by the Pennsylvania Department of Environmental Protection for an AMD treatment system overhaul at the park.

The grant was for a total of $93,000 and was used in conjunction with the DEP Sole Source Award in the amount of $72,800.

The grant funding was used to replace the AMD treatment system that was first installed in 1991.

Acid mine drainage occurred at the site and was treated chemically until Glacial Mineral's bankruptcy.

The bonding company installed a passive treatment system in 1991 but the system was abandoned for more than 20 years.

The system declined substantially because of neglect.

Tricia Mazik, a resource technician with the Clarion Conservation District, said in an earlier interview that a passive treatment system would remove metals and raise the pH of the water.

A passive system requires minimal maintenance but iron oxide sludge needs to be cleaned out every 15-20 years.

The subsurface AMD water is directed to flow through a buried, high-quality limestone bed to raise the pH level. The limestone effluent will then flow into two serially connected settling ponds to remove metals and the outflow of the second pond will flow to a constructed wetland for polishing residual metals.

"It is just about finished now," Clarion County Commissioner Ed Heasley said recently. "They did a great job and their effort will make a big change there."

Heasley said the county will attempt to acquire small pieces of lands from private landholders at the edge of the park where the drainage takes place.

"That will allow the county access to the site for future maintenance," he said.