Are Buffer Zones Needed at Locks & Dams Due to Horizontal Drilling & Fracking?

by Duane Nichols on March 5, 2019

Cross Creek Reservoir in Washington County, PA

Buffer zones debated for drilling near PA state’s dams

Edited from an Article by Don Hopey, Pittsburgh Post Gazette, March 2, 2019

Hundreds of shale gas wells are crowding close to and sometimes snaking under Pennsylvania’s many dams.

That’s because there’s no risk-based setback requirements for shale gas development around dams in Pennsylvania, now the nation’s second biggest natural gas producing state, with more than 11,500 Marcellus and Utica shale gas wells drilled and fracked, another 10,000 permitted, and the potential for tens of thousands more in the future.

That’s in contrast to buffer zones of 3,000 to 4,000 feet around scores of dams in other shale gas drilling states.

Examples of shale gas wells near dams in southwest Pennsylvania are easy to find. CNX has drilled and fracked 17 Marcellus Shale gas wells within 2,100 feet of the Beaver Run Dam in Westmoreland County, where a few thousand feet farther from the dam, the company lost control of a Utica Shale well last month, causing pressure spikes and gas flaring at nine nearby shallow wells near the reservoir.

In light of studies and analyses that suggest gas drilling could cause surface subsidence, some say that kind of encroachment is cause for concern or at least for a focused risk study to assess what could happen to dams when drilling and fracking occurs nearby.

Anthony Ingraffea, a civil and environmental engineering professor emeritus at Cornell University in New York, said such studies should be done to ensure public safety, especially around bigger dams where a breach or failure could cause loss of life or economic ruin.

“Yes, shale gas extraction will cause subsidence, and yes, dams will subside. But the question is how much, and then how much damage will that cause?” Mr. Ingraffea said. “Is subsidence the biggest issue raised by shale gas development? Probably not in Pennsylvania right now. But if a dam fails, then it will be a big ‘Ooops.’ I think it would be better to be safe than sorry.”

That was the approach by the U.S. Army Corps of Engineers Southwest Division which since 2011 has prohibited shale gas well drilling and fracking, horizontal laterals and pipeline routes within 3,000 feet of 90 of its dams in Texas, Oklahoma, Kansas, Arkansas and Missouri to protect them from structural damage and reduce the risk of catastrophic collapse.

And three years ago, the Fort Worth District in that same corps division conducted an engineering study that resulted in widening the 3,000 foot buffer zone to 4,000 feet around the massive Joe Pool Dam west of Dallas. The corps was concerned that continued and close drilling and fracking near the dam would put it in jeopardy.

If Pennsylvania had a 4,000 foot buffer around its dams, 303 shale gas wells would be within that exclusionary zone, according to mapping done for the Post-Gazette by Fractracker Alliance, an environmental nonprofit with mapping and data collection expertise.

And 167 of those are drilled and fracked wells within 3,000 feet of 27 dams in 10 counties, including wells close to 19 dams in seven southwestern Pennsylvania counties — Allegheny, Beaver, Butler, Greene, Fayette, Washington and Westmoreland.

The corps’ Joe Pool Dam study also recommended that deep wastewater injection wells — the kind that activated deep bedrock faults and caused 77 deep but minor earthquakes around Youngstown, Ohio, in 2011 — be kept five miles away from the dam.

Seven of the dozen deep injection wells in Pennsylvania are closer to dams than that, according to Fractracker mapping. Matt Kelso, Fractracker’s manager of data and technology, called on the corps in Pittsburgh to take a more proactive role in assessing the risk to dams.

“The Army Corps of Engineers has identified this particular risk with oil and gas wells and especially brine disposal wells in close proximity to dams in one part of the country, and yet the same practice is essentially unregulated in other locations,” Mr. Kelso said. “We encourage USACE to enact these common-sense preventative measures nationwide to protect this critical infrastructure.”

Drilling sideways or deep “horizontal drilling”

Modern shale gas wells don’t just go straight down. Some laterals can extend horizontally through the shale for more than three miles. So directional drilling from well pads located more than 4,000 feet from dams can also allow well laterals to burrow closer to, or even under, dams.

One such operation is Range Resources Appalachia LLC’s Avella Land Ventures well pad about a mile away from the Washington County-owned Cross Creek Park Dam. Three well laterals end approximately 400, 600 and 1,000 feet from the breastworks, and one 6,600 foot lateral stretches under the dam.

Washington County’s original 2003 lease for gas drilling under the 2,400 acre park prohibited drilling within 3,000 feet of the dam, but that was changed to accommodate newer directional drilling technology, said Lisa Cessna, executive director of the Washington County Planning Commission now and in 2012 when the commission approved the change.

Ms. Cessna said the change was made after the county consulted with engineers, but Bob Donnan, a local anti-drilling activist, said the higher revenue the county received also came at a higher risk. “One has to wonder what sort of risk that added to a potential failure of the earthen breastworks of the dam ,” he said. “The resulting flooding would severely affect the small town of Avella.”

State Rep. Rob Matzie, D-Beaver, introduced legislation two years ago that would have established a 4,000 foot setback from dams for wells and pipelines, but the bill didn’t get out of committee. He plans to reintroduce it this spring. “The number of wells within 4,000 feet of our dams speaks to the need to get some regulation in place,” said Mr. Matzie, whose interest in the issue was prompted by plans to route the Shell Falcon ethane pipeline close to the Ambridge Reservoir.

“I’m a big supporter of the natural gas industry, but I want to be cautious about our water supplies,” he said. “The industry should be cautious too if it wants to be a good neighbor. If setbacks are good enough for Texas they should be good for Pennsylvania too.”

Buffer zone debate being exposed

The corps’ Pittsburgh District has not established exclusionary safety zones between shale gas operations and any of its 13 flood control dams or 17 river navigation locks and dams in Western Pennsylvania.

And although all of the corps’ dams and locks in the state were built years before the first shale gas well was drilled, the local corps district hasn’t conducted specific engineering studies to assess impacts and risks from present and future shale gas development.

Officials in the corps’ Pittsburgh district office and its headquarters in Washington, D.C., say they have no plans to do new engineering assessments, but both have talked about doing so.

“We pulled a team together to see if we needed a specific process. We found that there was an ‘area of concern’ in the Southwest, but in Pennsylvania we did not identify a high level of concern for our projects,” said Tammy Conforti, a civil engineer and acting dam and levee safety officer in the corps’ D.C. office. “We concluded it was not an issue for a national policy, and (shale gas development) posed a threat similar to other industries.

“At this point we don’t feel a need to drill down and develop a specific approach for fracking, although there might be concerns on specific sites.”

So far in Pennsylvania, only two corps’ projects — Lock and Dam No. 8 on the Allegheny River near Kittanning in Armstrong County, and Lock and Dam No. 2 on the Monongahela River in North Braddock, Allegheny County — have shale gas wells within 4,000 feet, and the Pittsburgh corps office said it has no issues with those.

But the Pittsburgh corps did have some concern a decade ago when shale gas development was just getting started in the state, said Werner Loehlein, the corps’ water management chief in Pittsburgh until his retirement two years ago and now a senior lecturer in the civil and environmental engineering program at the University of Pittsburgh.

“One of the concerns we had then was what could happen when horizontal well laterals go under our dams,” Mr. Loehlein said. There were also internal concerns about the cumulative impacts on corps dams of hundreds or thousands of shale gas wells. “There were meetings about those concerns and we talked about a 3,000 foot buffer,” Mr. Loehlein said. “And I do remember there was talk about doing a research study. There was interest in doing it, but it just didn’t happen.”

Jeffrey Hawk, a Pittsburgh District corps spokesman, said the corps reviews shale gas well locations near its dams during “periodic assessments,” and evaluates the risk they pose. Although drillers and pipeline companies are not required to notify the corps about shale gas development operations on private land near dams, Mr. Hawk emphasized that the Pittsburgh corps has a “rigorous” dam safety inspection program that includes the use of inclinometers to determine if its dams are sinking, and includes regular inspections for cracks and leaks.

“To date,” he said, “the Pittsburgh District’s assessments have not determined any significant risks to district dams and no damage has occurred.”

Much is unknown about fracking impacts

There’s been no damage in Texas either, but the corps’ Fort Worth District, in coordination with the Southwestern Division has gone the extra 3,000 or 4,000 feet in ensuring dam safety.

That approach was embodied in an April 2011 letter to the mayor of Grand Prairie, where the Joe Pool Dam is located, from Col. Richard Muraski Jr., then commander of the Fort Worth District. Mr. Muraski wrote that the corps was adopting the buffer zone because it had “significant dam safety concerns” about the impact of hydraulic fracturing, or fracking, on its dams.

“Much is unknown about the impact of hydraulic fracturing and removal of oil and natural gas from formations in close proximity to USACE dams and other key structures,’ Mr. Muraski said in the letter. “Although hydrofracturing generally occurs in formations that are found more than a mile below the ground surface, there is concern that the disruption to the geologic structure of natural gas shale formations could result in subsidence of the underground structures supporting dams, resulting in damage to the dams and associated structures.”

The Joe Pool study of February 2015, done for the corps by DLZ National Inc., an engineering consulting firm from Columbus, Ohio, found that the area’s closely spaced wells could cause dam subsidence of from 2 inches to 21 inches. “There were a lot of wells already around the dam and we were concerned that any type of subsidence from fracking or faults could produce (slumps) or displacement at the dam,” Mr. Muraski, now retired from the Army, said in a phone interview last month.

Loree Baldi, chief of the Dam and Levee Safety Section and the geotechnical branch in the corps’ Fort Worth District, said corps concerns were heightened by memories of the Baldwin Hills Dam failure near Los Angeles in 1963, which killed five people and has been blamed on significant subsidence activated by oilfield extraction and deep injection well activity along a fault line.

Ms. Baldi said the corps undertook the Joe Pool engineering study to determine if it could rule out negative impacts to its dam projects from drilling in the 8,600 foot deep Barnett Shale. By comparison, the Marcellus Shale in Pennsylvania lies between 5,000 and 9,000 feet underground.

“But the information developed could not rule that out,” Ms. Baldi said. “The risk posed by shale gas wells near Joe Pool Dam was not acceptable to allow drilling to go forward. Other, outside experts reviewed our study and concluded the same thing.”

Pennsylvania Under Consideration

Pennsylvania agencies — the Department of Environmental Protection, Department of Conservation and Natural Resources, Game Commission, Fish and Boat Commission — own more than 250 dams. None of those agencies reported damage to their dams from shale gas operations, but none have conducted engineering studies to assess risks from existing and future gas development.

The PA-DEP, which owns 10 small dams, and regulates the shale gas industry through permitting and enforcement, issued a statement saying it does not track distance between its dams and gas wells and does not consider seismic activity from fracking a risk to surface structures like dams.

The PA-DEP, in the aftermath of one “induced seismic event,” causing several “low magnitude earthquakes apparently associated with hydraulic fracturing” in Lawrence County, does require seismic monitoring at shale gas wells in the northwestern part of the state and at underground injection wells for wastewater disposal.

The state Dam Safety Program, part of the Department of Environmental Protection, oversees regulation of approximately 3,400 dams, including 747 classified as “high hazard” dams, meaning their failure or collapse would likely cause loss of human life.

Roger Adams, director of PA-DEP’s Waterways Engineering and Wetlands Bureau, which contains the state Dam Safety Program, said many of the state’s dams, especially the high hazard dams, are designed to withstand a seismic event, like an earthquake.

But subsidence is another matter, one that warrants watching, he said, noting that the concrete Duke Lake Dam in Ryerson Station State Park in Greene County cracked due to mining subsidence in 2005, causing the state to draw down the water in the popular recreational lake, which remains drained.

“Subsidence raises different concerns because dams are not designed for subsidence,” said Mr. Adams, who is also president of the Association of State Dam Safety Officials. “Subsidence is not something we’ve heard much about, but something we need to look into.”

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