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Thermal imaging unit on a helicopter locates acid mine drainage

Monday, February 22, 1999

By Don Hopey, Post-Gazette Staff Writer

On a computer monitor in an Allegheny County Airport hangar, a color-enhanced aerial picture shows the Brinkerton mine acid discharge as a thumb-sized royal blue smear bleeding into the meandering black ribbon of Sewickley Creek.

 
  Charles Golanics of Bechtel Nevada explains the operation of the company's multispectral imaging technology, which is helping pinpoint acid mine drainage in southwestern Pennsylvania. (Department of Energy)

No surprise there. Brinkerton, between Armbrust and Norvelt in Westmoreland County, is one of the largest discharges in the state, gushing 4,100 gallons of acidic water each minute. It's a well-known contributor to the demise of aquatic life in the creek.

But it is a few, fine, bluish-white lines along the creek and a wetland next to Brinkerton in the image that really excite a dozen people from local watershed groups, the U.S. Geological Survey and the U.S. Department of Energy crowded around the screen.

Those lines mark smaller, previously uncharted discharges from abandoned mines.

The picture on the computer screen was produced by the DOE's Remote Sensing Laboratory - a helicopter equipped with the same advanced thermal imaging technology used by the Mars Pathfinder for geologic assessment and space satellites to produce maps of rain forest destruction and weapons plants in the Middle East.

It was the first time the technology - called multispectral imaging -- was used to map discharges from abandoned mines, introducing a high-tech tool for watershed groups and government agencies to use in battling the state's most devastating and widespread water pollution problem.

More than 2,400 miles of the state's streams run polluted and dead because of discharges from 250,000 acres of abandoned underground and surface mines.

"There a lot of applications for this in Western Pennsylvania, a lot of mine drainage," said Jim Sams, a hydrologist with the U.S. Geological Survey.

"There are a lot of groups out there trying to clean up watersheds. The first thing they need to know is the sources of the mine drainage. In the past, they'd just go out into the field, maybe armed with mining maps, and look around. That was time-consuming and labor-intensive."

The DOE's helicopter-mounted imaging lab changes all that.

Based in Las Vegas and operated by Bechtel Nevada Corp. personnel, the multispectral imaging system detects and records electromagnetic energy - including infrared - that is emitted by certain environmental features.

Because different materials absorb and emit energy in different thermal ranges, the system is able to measure and identify the materials, then, combined with a global positioning program, produce an aerial photograph based on the computer imaging.

The technology has been used since 1985 to detect disturbed earth and buried caches of chemicals, assess forest health and map Texas coastal lagoons.

It can measure forest health by focusing on the chlorophyll content of leaves, said Terry Ackman, of the DOE's Federal Energy Technology Center in South Park.

"Trees and vegetation that are healthy or stressed show up differently on the picture," he said. "A leaf dying off or stressed experiences a slowdown in chlorophyll."

Mine drainage flows are highlighted in the multispectral imaging because of different thermal "fingerprints." Overlaying the multispectral data with mapping programs pinpoints their location.

Operating only at night to maximize temperature contrasts, the helicopter flew 59 parallel passes over the 167 square mile Sewickley Creek watershed. The data is being transformed into a mine drainage map, and sources of mine water contamination that may be otherwise unknown and even undetectable will be pinpointed.

Watershed groups in Somerset County can attest to the difficulty and uncertainty of making this kind of assessment without a such a tool.

"It took four years to locate, map and assess 300 abandoned mine discharges along the Stonycreek River," said Juliane Brown, a geographic analyst for the Geological Survey. "And I know we didn't find them all. This would definitely help. It would be a major tool for reconnaissance."

On the Sewickley Creek watershed, honeycombed with abandoned underground mines and inundated by Brinkerton and half-a-dozen other major discharges, the helicopter flyovers will help determine which discharges to treat first, said Tom Keller executive director of the Sewickley Creek Watershed Association.

Keller said the group has the money to fix the Brinkerton discharge by building a passive treatment facility in an adjacent wetland, but doesn't know if there are other discharges that could be disturbed or opened up by the project.

"The images from the flyover can tell us if there is another major discharge in the wetland. It's a great data-gathering tool," he said. "It will save us money because it will keep us from digging in and opening another discharge that we'll have to fix too."

The technology would be useful throughout southwestern Pennsylvania, where many streams and rivers, including the lower Youghiogheny, are undermined.

"About 20 percent of the mine water is flowing directly into the river from underground mines," said Robert Kleinmann, division director at the DOE's South Park facility. "We hope, as a result of these flights, to find where the underlying rock has been fractured."

As a result of the sub-river fracturing, mines not only discharge drainage into the rivers but also are recharged by river water.

"After we identify the fractures we can use a polyurethane grout to seal them," Kleinmann said. "The grout is a Band-Aid to separate the river from the mines. We'd still have to treat the mine discharges."

He said the polyurethane grout has been used on creeks in West Virginia and Maryland with a 90 percent success rate.

The DOE helicopter completed its flyover of the Sewickley Creek watershed and lower Youghiogheny River, from McKeesport to Connellsville, last week.

A breakdown in the imaging system has delayed plans by the state Department of Environmental Protection to use the helicopter to identify mine discharges feeding into the Monongahela River from the West Virginia state line to Mc-Keesport.

That work will be done as soon as repairs are made.

The DEP wants to use the data from the DOE helicopter to study discharges from abandoned mines and how shutdowns of active mines will affect water quality in the Monongahela River.

"We're trying to do a predictive study of the watershed, the mine drainage that's there, and how future shutdowns will affect things," said Michelle Miller, DEP mining bureau spokeswoman. "The helicopter will help us identify clearly and precisely where the discharges are and get a better understanding for the future."

The information gathered will enable government agencies and local watershed groups to set strategies for treatment and cleanup of the discharges.

In addition, four watershed groups have applied through the state for federal money to pay for additional helicopter reconnaissance. It cost the Federal Energy Technology Center $140,000 to bring the helicopter here from its home base in Las Vegas, Nev., and do the initial work in the Sewickley Creek watershed and on the Youghiogheny River.

"Getting the helicopter here is the big expense," Kleinmann said. "Piggybacking additional work while it's here makes sense, and the costs are very reasonable if there are more watershed programs splitting them."



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