Bill Carter crested the hill at McKenna Park on Thursday morning, his pet sheltie in tow, and saw a towering flame rising from the Rayzor Ranch property.

DRC/Barron Ludlum

The Range Resources drilling company flares its Rayzor Ranch natural gas well on Bonnie Brae Street in Denton on Thursday.

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An energy company was flaring its natural gas well — burning the gas as one of the final stages in the drilling process. Carter’s daily walks are for his health, he said, but lately they don’t feel so healthy.

The flaring “definitely adds to the toxicity of our air pollution,” said Carter, a retired mechanic who lives nearby and opposed the drilling at the Rayzor Ranch development. “Should I be afraid? Of course I am. It’s dangerous.”

An official with Fort Worth-based Range Resources, which is drilling the well, said the company flared the well to test the rate of its gas flow. The information will help company officials decide how large of a pipeline to build and whether they’ll drill more wells at the site, said Mark Whitley, senior vice president of production.

The flaring started at 9 a.m. Thursday and was expected to end by 5 p.m., Whitley said.

Drillers flare wells for various reasons, including to burn off waste gases and to separate gas from water and other materials that come up with it. The Texas Railroad Commission, the state agency that regulates the oil and gas industry, generally allows operators to release gas for up 10 days after a well is complete.

Denton City Council members placed time-of-day limits on flaring when they approved a zoning permit allowing drilling at Rayzor Ranch last year, but they didn’t forbid the practice. Flaring at the site is restricted to 8 a.m. to 5 p.m. Monday through Friday and 11 a.m. to 5 p.m. on weekends.

Flaring is considered less harmful to the environment than venting, or releasing gas into the atmosphere, but both practices have been criticized as wasteful and for releasing greenhouse gases and other pollutants. A 2009 report by Al Armendariz — now the regional leader of the Environmental Protection Agency — for the Environmental Defense Fund said flaring can produce emissions of carbon dioxide, carbon monoxide, polycyclic aromatic hydrocarbons and particulate matter, or soot. The amount and types of pollution can vary based on many site-specific conditions, including the equipment used and the chemical makeup of the gas and hydrocarbon liquids, the report states.

Some well operators now use “green completions,” a process endorsed in the Armendariz report in which gas is captured instead of released. Whitley said that wasn’t an option for the Rayzor well.

“We don’t have a pipeline to put that gas into during the completion process,” he said. “Here, we have to flare it to figure out how good of a well we’ve got.”

Whitley said the environmental impact would be minor.

“Flaring basically turns all of your hydrocarbons into non-hydrocarbons, which is basically CO2 and water vapor,” he said. In this case, “it’s being done on a very short-term basis, so there’s not a significant emission of anything.”

Terry Clawson, a spokesman for the Texas Commission on Environmental Quality, said the flaring, if properly done, should destroy the vast majority of any pollutants.

“The source of emissions going to the flare and the amount of material going to the flare determine the actual amount of any residual emissions,” Clawson said in an e-mail.

The drilling site is near the northwest corner of Scripture and Bonnie Brae streets, across the street from McKenna Park and close to a neighborhood, a hospital and other medical facilities.

LOWELL BROWN can be reached at 940-566-6882. His e-mail address is lmbrown@dentonrc.com .