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Fracking's Footprint: Scientists Study Impact of Shale Gas Development on Pennsylvania's Forests


This article in Soil Horizons

  1. Vol. 53 No. 4, p. 1-3
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  1. Madeline Fisher
  1. Madeline Fisher, associate editor–magazines, Soil Science Society of America, Madison, WI

Travel the length and breadth of Pennsylvania and you'll notice a divide that has defined the state from the start: The southeast is settled and wealthy farm country, while the less prosperous north and west have always depended on boom-and-bust cycles of resource extraction. Nearly all of Pennsylvania was clear-cut in the late 1800s and early 1900s, making it for a time the largest producer of lumber in the United States. Underground coal mining began even earlier, followed by surface strip-mining in the 20th century. Oil and gas production have also flourished here; since 1859, more than 325,000 wells have been drilled.

Now the latest boom is on. Thousands of feet below the surface are the Marcellus and Utica shales and their largely untapped reserves of natural gas.

For decades, geologists have known about the fuel stored in deep rock formations such as the Marcellus, which runs beneath Pennsylvania, New York, West Virginia, and other Appalachian states. But extracting it wasn't economical until the advent of horizontal drilling and the controversial technique known as hydraulic fracturing (view video here: http://marcellus.psu.edu/resources/drilling/index.php), or fracking. In the latter process, millions of gallons of pressurized water, sand, and chemicals are injected deep into the earth to fracture the shale and release the trapped gas.

Since 2004, nearly 3,000 shale gas wells have been drilled in Pennsylvania, which is still just a tiny fraction of the state's conventional oil and gas wells. But because shale gas is so deep and extracting it means handling massive amounts of water, much more infrastructure is involved than in conventional drilling—creating a much bigger footprint as a result, says Pennsylvania State University assistant soil science professor Patrick Drohan.

“I could see right away when I saw my first Marcellus gas pad,” he says, “that this would be something that would change Pennsylvania's landscape unlike anything the state has seen in well over 50 years.”

To support the drilling of a 5,000-foot-deep well and the fracking process that follows, engineers must build a raised, gravel pad of three to five acres in size and a stormwater system to handle the resulting runoff. New roads to the drill pad are needed, as are compressor stations for pumping the gas and pipelines to carry it away. And because most of the pressurized water comes back up once hydraulic fracturing is finished, flowback water storage ponds and treatment facilities must be constructed, as well.

A gas pad in Pennsylvania.


Pad access road in Pennsylvania.


Pipeline construction in Pennsylvania.


But the vast landscape changes produced by shale gas development are poorly understood, which is why Drohan, Penn State wildlife ecologist Margaret Brittingham, and others are now working to shed some much-needed scientific light on the process. Their first goal has been to characterize the Pennsylvanian landscapes where development is occurring: where the activity is concentrated, what the topography and soils are like, whether the land cover is agriculture or forest.

They then hope their data can inform the siting of future wells, pipelines, and roads so this infrastructure causes the least disturbance in the short term and eases the way toward bringing back farmland and forest later on.

Pennsylvania's Pine Creek Gorge.


Some of the most beloved forests in the state are found in and around Pine Creek Gorge (http://www.dcnr.state.pa.us/forestry/oldgrowth/pinecreek.aspx), known as the Grand Canyon of Pennsylvania. The site's expanse of trees is also among the last unbroken, “core” forest in the state and across the entire northeastern United States, as well.

It may not remain so, however. Drohan and Brittingham's work suggests that nearly 25% of Pennsylvania gas pads are being built in core forest areas, including those near Pine Creek, where at least one well rig now towers above the hills and trees. All told, some 1,700 acres of core forest could be lost to gas development, according to the scientists’ study published this spring in Environmental Management. “That's still a very small part of the state,” Drohan says. “But it's a very significant part of the state's forest.”

Core forest is significant, in part, because of the birds that depend on it for their livelihood and survival, especially neo-tropical migrants, such as warblers, thrushes, and tanagers, which over-winter in Central and South America and then fly north in the summer to breed. Roughly 20% of the world's population of scarlet tanagers, for example, breeds in Pennsylvania.

The forest edge next to a gas pad.


The problem for these birds is that construction of pads, roads, pipelines, and other infrastructure opens up the canopy and creates new forest edges—essentially carving large, continuous blocks of forest habitat into smaller, patchier ones. As this occurs, Brittingham predicts that tanagers and other forest birds will be replaced by chickadees, woodpeckers, and other “generalist” species that thrive in smaller woodlots. And the same is true of plants, mammals, and amphibians.

“Basically, any species that can do well around people or across a range of habitats will tend to benefit” from the changes, she says. “And ones that are very specialized on a certain type of habitat and are sensitive to disturbance—you lose those.”

Just as important is the loss of the ecological roles they play. Neo-tropical migrants, for instance, “are the insect-eating machines of the forest,” Brittingham says, keeping down mosquitoes and forest pests. “They've evolved with the forest,” she says, “and the forest has evolved with them.”

Gas development in Bradford County, PA, in the Susquehanna River basin.


As forest is cleared and soils are removed or covered over to create pads and roads, land managers and scientists also want to prevent sediment erosion and nutrient runoff into downstream waterways. Of particular concern is shale gas development in the Susquehanna River basin—the source of more than half of the freshwater flowing into the embattled Chesapeake Bay.

Not only does this basin contain more pads than any of Pennsylvania's other major river basins (60% of existing pads and 54% of future, permitted ones), Drohan says, but 25% of these pads are in core forest, as well. Roughly 145 miles of new roads could also be built in the basin—an amount that is 10 to 100 times greater than in any other.

What this all means is that shale gas development poses a substantial new risk to the water quality of Chesapeake Bay, which people have already been struggling for decades to improve.

Plantings of trees and ground vegetation in a shale gas drilling area.


There is an urgent need, in other words, for a regional, landscape approach to siting drilling infrastructure, Drohan says, and on this front some progress is already being made. The Pennsylvania Department of Conservation and Natural Resources (DCNR), for example, is trying to get drillers to share pipeline corridors on state lands, rather than letting each cut its own pipeline path through the forest. Drohan also recently received a grant from the DCNR to model the locations of the wettest, most vulnerable soils on state forests so that the agency can work with the shale gas industry to protect these areas.

At the same time, 90% of Pennsylvania shale gas development is happening on private land today, according to his analysis with Brittingham, meaning that no single agency or organization has the final say on where drilling can take place or in what manner. Nor, for that matter, can any one group decide that people in economically depressed areas of Pennsylvania can't take advantage of the new opportunity.

Thus, the key to doing things right—or as right as possible—is for scientists, companies, landowners, local governments, and the public to keep on talking, Drohan says.

“I think one thing people need to be careful about is polarizing the issue. Once you do that, you're going to shut the door on any potential compromise,” he says. “And at the end of the day, no entity is going to get its way. Some compromise will have to occur.”

Editor's note: Unless otherwise noted, the images in this story come from the Penn State Extension Marcellus Electronic Field Guide (http://marcellusfieldguide.org/index.php), a resource for landowners on management topics ranging from preparing for shale gas development to restoring vegetation and wildlife habitat once drilling is finished. Interested in this topic? Check out the full-length version in the July issue of CSA News magazine (https://www.soils.org/publications/csa-news/).



James Boyle said...
This excellent article, with accompanying videos, is an outstanding description of a "wicked problem" (~~complex, multiple ramifications, no simple solution) of natural resources uses and management. I urge all soil scientists to read and ponder the content, and, to encourage colleagues who teach in the realms of natural resources management, policy, economics, sciences and conservation to consider this "case study" as a springboard for education and discussion of the complexity of the issue. Congratulations to Patrick Drohan and colleagues, and to Madeline Fisher for the education. And, and as one interested in engineering and technology, as well as natural resources, I found the video on the drilling and fracking process to be fascinating - impressive engineering with multiple unforeseen potential consequences in application. Jim Boyle, Professor Emeritus, College of Forestry, Oregon State U.
2012-07-13 13:37:05

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