Independent air quality tests around the Rayzor Ranch gas well in Denton showed elevated levels of benzene and other harmful chemicals during several stages of the drilling process, according to results announced Friday.

The tests found cancer-causing benzene and a host of sulfides above levels the state sets for safe short- and long-term exposure, along with elevated readings of methane, said Alisa Rich, president of Flower Mound-based Wolf Eagle Environmental, which performed the tests.

DRC file photo/David Minton

A noise-reducing barrier surrounds the gas well site at Rayzor Ranch, seen in January. Independent tests have shown elevated levels of benzene and other harmful chemicals in the air.

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“This is very typical of what we’re finding all around the Barnett Shale,” said Rich, whose firm has tested air around natural gas facilities in area towns including Dish.

Officials with the company that drilled the well said they hadn’t seen the test results. But the findings raise doubts about the testing methods, said Rodney Waller, senior vice president of Fort Worth-based Range Resources.

“The critical thing was that if you don’t test with sufficient accuracy to blend out the background benzene that’s going to be coming from [vehicles on] the highway, you’re going to get a false positive,” Waller said. “If your testing integrity has not been set up properly, you’re going to get the wrong answer. I don’t know how they [Wolf Eagle] tested it. Some of their prior testing protocol has not been in accordance with industry standards.”

A group of neighbors and other contributors hired Wolf Eagle last year to perform air tests around a 3-acre gas well site near the northwest corner of Bonnie Brae and Scripture streets, where Range has drilled the first of up to five wells.

Margarete Neale, one of the leaders of the neighborhood effort, found the results troubling.

“The emissions are going to be compounded as they put more wells in,” she said. “In our neighborhood we do have a lot of elderly, a lot of people in that highly susceptible population … and it [the gas well] is right by a hospital and a retirement home. It seems to be in a very precarious position.”

Acting on complaints, state environmental regulators took air samples at the site on Feb. 7 and Feb. 17 and tested for certain pollutants. None were measured at or above levels that would be expected to cause health problems, said Terry Clawson, a spokesman for the Texas Commission on Environmental Quality.

A complainant also took an air sample at the site Feb. 18 using a state-provided canister. The results, analyzed by the commission’s lab, showed no emissions above state screening levels, Clawson said.

Commission officials had not seen the independent test results but would review them if asked to, he said.

Wolf Eagle performed four tests at the site on Dec. 13, Feb. 5 and Feb. 18, measuring air quality during the boring, hydraulic fracturing and flaring processes, Rich said. Three of the tests were 24-hour samples, the other a quick “grab” sample during flaring, she said.

“We got a very good representation of the emissions from three different parts of natural gas mining,” she said.

Rich rejected the idea that vehicles from nearby Interstate 35 tainted the results.

“Natural gas, as well as the coal industry and lot of other industries … have a fingerprint related to chemicals,” she said. “These chemicals are virtually identical to other [natural gas] sites. Is it possible it could have come from transportation? No, it’s not.”

If anything, the results may understate pollution from the site because the tests were performed during cold weather, when emissions are typically lower, Rich said.

The Denton City Council approved a zoning permit in October allowing gas drilling at the site despite widespread opposition to its location near McKenna Park, a neighborhood, a hospital and other medical facilities. The Texas Railroad Commission, the state agency that regulates gas drilling, had already approved drilling permits for the site.

Jim Engelbrecht, whose council district includes the Rayzor Ranch development, said he wanted to review the Wolf Eagle findings before commenting on them.

“Obviously, we have some air quality issues that we’re going to have to look at how to address — not only us, but also the whole region,” Engelbrecht said. “We are moving forward with addressing the issue at the city.”

City leaders plan to meet next month to overhaul Denton’s gas drilling ordinance, he said.

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