Hatfield's Ferry installs wetland treatment facility
Allegheny Energy Supply has turned away from chemistry and toward nature to treat fly ash at its Hatfield's Ferry Power Plant along the Monongahela River in Greene County.
The electricity generator has created a passive wastewater wetlands system stretching across five acres to treat the flow of groundwater from its fly ash landfill, which carries with it iron, manganese, and aluminum.
The company had treated the flow with sodium hydroxide and settling tanks - but with tighter regulations being imposed by the state Department of Environmental Protection for a permit renewal, Allegheny decided to install a passive wetlands system to do the job.
Fly ash is a byproduct of burning coal to generate electricity, along with the cinders known as bottom ash.
About half the fly ash generated by the Hatfield's Ferry operation is sold for such uses as a mix for concrete; the remainder is deposited in a landfill at a nearby site.
C. Michael Saurborn, the environmental manager at Hatfield, said using chemicals to meet the revised DEP standards would involve other environmental concerns.
A larger chemical tank would have to be installed at the site, adding to the danger of spills. Getting the mix exactly right could also be an issue with overfeeding of the chemical spiking the pH level in the water and under-filling, not proving adequate treatment, according to Saurborn.
The solution was to build a series of four wetland areas and the accompanying treatment systems. 'It's a wonderful thing to let nature do it for you,' Saurborn said.
The groundwater from the landfill is directed to a tank to maintain an even flow rate. Aerators in this tank oxidize the flow causing much of the iron to drop out.
The wastewater then flows to four 'vegetative wetland' ponds, planted with cattails, moss and various grasses. The flow is either directed to two ponds on 'Track A' or two on 'Track B,' or through all four ponds, where the wetland plants filter out the heavy metals.
After flowing through the wetlands, the water goes into rock drains - washing over limestone that develops a natural bacterial coating, further oxidizing the magnesium.
The water then flows to a settling pond before continuing into Little Whitely Creek, a Monongahela River tributary.
Drains that snake around the property carry fresh rainwater away before it can mix with wastewater. Fly ash is used in the fiberglass lining of the drains.
'We use fly ash any way we can here,' said Janice D. Lance, an Allegheny Supply spokeswoman.
Saurborn said the passive wetlands treatment has resulted in a reduction of iron in the treated water from three parts per million to .1 part per million. He said the removal of other materials in the water have 'followed suit,' although the reductions haven't been quite as dramatic.
The 'passive' treatment also has advantage in that it requires fewer pumps and other equipment, resulting in a savings in maintenance costs. One disadvantage is the cost to build the system.
Lantz said there has been some local concern over Allegheny's request to allow Allegheny Power to use the Hatfield's Ferry landfill as a backup facility for fly ash generated at the Mitchell power plant in Monongahela.
She said, however, that Mitchell wouldn't produce a large amount of fly ash and that including two power plants on a permit for a backup is common.
Saurborn, a chemist who is a convert to using wetland systems to treat the wastewater, said the DEP should be 'real happy' with the new system.
'The chemical tank is going to be empty,' he said.
The company installed similar wetland treatment systems at its Albright power station in Albright, W.Va., in 1988, and in Springdale, Pa., in 1995. The Springdale facility was honored in 1997 with a Pennsylvania Governor's Award for Excellence.
The Hatfield's Ferry Power plant was opened in 1969 and it generates about 1,710 megawatts of electricity.
Allegheny Energy Supply is an unregulated electricity generating subsidiary of Allegheny Energy Inc., of Hagerstown, Md. It is a sister company to Allegheny Power, the utility that serves portions of five states, including Pennsylvania.
