BRADY TWP — The Jennings Environmental Education Center is well known for its five miles of hiking trails and its 20-acre prairie system.

However, it also has one of the world's first abandoned mine drainage passive treatment systems.

The system, constructed in 1997, cost more than $300,000. It ran for 15 years before needing renovation last year.

Wil Taylor, center manager, said a renovation was necessary because the system's vertical flow pond, its primary element, became clogged.

“By improving the site here, we're improving water quality downstream in Slippery Rock Creek,” Taylor said.

Although the system only was built in 1997, there has been a long history of mine runoff in the area.

A coal mine on a hill east of Route 8 operated in the 1920s. When it was shut down, Taylor said it basically was abandoned and not sealed, leading to runoff causing occasional floods on Route 8 during heavy rain.

In the 1970s, there was a federal reclamation project that attempted to seal the entrance of the mine.

Jennings became a state park in 1980, and the mine seal failed shortly after the park opened.

“Since then, we've been trying to address that,” Taylor said.

In 1988, the center installed a small wetland to help treat the drainage. Taylor said it was not that effective, but it helped.

“It was an experiment,” Taylor said.

In 1994, an anoxic limestone drain was installed. Taylor said it worked for about six months before it became clogged.

When the center finally installed the current system in 1997, the wetland was included.

Mine runoff looks clear, but is acidic and contains metals and other contaminants.

Active treatment systems use strong chemicals to remove metals and contaminants while passive systems neutralize or remove contaminants using air, ponds and wetlands.

Taylor said active systems are expensive to run and take a lot of manpower.

He said a passive system costs next to nothing to operate. He checks it once a week and a volunteer comes in once a month to monitor it.

Treating mine runoff has three steps: neutralizing acidity, oxidizing and filtering.

The runoff comes out of the mine and is piped into a vertical flow pond, which is the primary treatment element of the system.

The water flows through what is called “treatment media,” which includes limestone, mushroom compost and wood chips. The limestone raises the water's pH, the compost promotes the growth of helpful bacteria and the wood chips help prevent the compost from decomposing and causing clogs.

Then the water flows through settling ponds and wetlands to oxidize and filter it. Finally, it is discharged into Big Run.

The system runs entirely by gravity.

“There's no electricity whatsoever,” said Ryan Mahony of BioMost of Mars.

The renovation project was required because the vertical pond plugged up due to decomposing mushroom compost. It still treated water, but it did not do it as efficiently.

Work started in May 2012 and the system was turned on again that July. The project cost about $60,000. BioMost administered the project.

Mahony said the project drained the pond, removed all of the old treatment media and pipes and added new ones. He also said it cleaned out excess vegetation at the wetland to prevent overflows.

During the renovation, the center treated water using an active method. Taylor said this gave the center a taste of the cost and effort it takes to operate such systems.

“I'm glad it was done,” Taylor said.

The system built in 1997 had a 10-year life span, but it ended up lasting 15 years.

Taylor said this likely will happen again.

“We're confident that the treatment life will be longer,” Taylor said.

“It was designed extremely well and it works extremely well,” he said.

Being one of the first systems of its kind in the world, Taylor said people from countries such as South America and Mexico have come to see how it operates.

Since it was built, 18 similar systems have been built in the Slippery Rock Creek Watershed, which covers about 400 square miles.

<B>WHAT: </B>Open house of renovated mine drainage passive treatment system<B>WHERE: </B>The Jennings Environmental Education Center, Route 528, Brady Township<B>WHEN: </B>starting at 11:30 a.m. MondayAttendees can walk or ride a shuttle to the project location.