The Army Corps of Engineers is expanding the zone where hydraulic fracturing is banned near Joe Pool Lake to protect the structural integrity of its dam.
The drilling exclusion zone is growing from 3,000 feet to 4,000 feet from the dam, the corps said Tuesday. The original exclusion area did not meet the dam’s minimum tolerable risk guidelines and posed a risk to the structure, the lake and the public, a corps official said.
The corps also said it will limit wastewater injection wells within 5 miles of the dam because of the effects of “induced seismicity,” or earthquakes triggered by human activities.
The corps “welcomes environmentally sound oil and gas exploration and other mineral extraction activities,” Col. Calvin C. Hudson, the commander of the Fort Worth corps district, said in a statement. “But we must always ensure that those activities pose no threat to our critical facilities and life safety.”
The Grand Prairie city manager has called a staff meeting to discuss the corps’ findings and recommendations, city spokeswoman Amy Sprinkles said.
“The city’s primary concern is for the safety of our residents. The city will be evaluating the corps’ report to determine what changes in our ordinance might be necessary,” Sprinkles said.
The study was initiated after an inquiry by someone living near the dam, corps spokeswoman Rhonda Paige said. A 2011 letter from the corps to the city of Grand Prairie raised concerns about natural gas drilling near the dam by Chesapeake Energy that could “contribute to a catastrophic dam failure.” Paige said there is no drilling in the area at this time that the agency is aware of.
The study says the closest injection well to the lake’s dam is 9 miles away.
The original 3,000-foot drilling exclusion zone was adopted by the corps more than 20 years ago before the Barnett Shale drilling boom took off in the mid-2000s.
Joe Pool Lake is a reservoir in southeast Tarrant and southwest Dallas counties near the cities of Grand Prairie, Cedar Hill and Mansfield. The dam is in Grand Prairie and Dallas, and the lake is the water source for Midlothian, according to the corps’ website.
The current study was completed in February 2015, and two authors are Jon Olson and Cliff Frohlich, professors at the University of Texas at Austin. After it was completed, and because of its findings, it underwent a stringent independent and external review, the corps said.
Olson declined to comment on the study, citing a confidentiality agreement with the corps.
The study’s goal was to evaluate the effect of fracking in the Barnett Shale formation, which lies underneath Joe Pool Lake and its dam. Fracking is a process where drillers inject water, sand and chemicals deep into rock formations to free oil and gas.
The study used published data and site-specific information obtained by drilling companies to evaluate possible effects of drilling, injection wells and extraction on rock formations. It acknowledges limitations since the data being provided was limited.
While induced seismicity is mentioned as a concern with injection wells, one that has become a major public concern, the study notes there are no documented cases of felt earthquakes in Texas caused by hydraulic fracturing and there have been no quakes associated with fluid extraction.
Other experts have disagreed on whether injection wells have induced quakes. The Texas Railroad Commission concluded there was no link between two wastewater injection wells northwest of Fort Worth and a rash of earthquakes in 2013 and 2014. But a study by Southern Methodist University scientists linked the oil and gas process to the flurry of earthquakes that hit the Azle and Reno area.