Mansfield Gas Well Awareness, an advocacy group founded by a northwest Mansfield neighborhood, led the push for wider buffer zones of up to 1,500 feet. The 600-foot minimum separation was unchanged in the proposed amendments.

Tamera Bounds, a group leader, said she supported the ordinance revisions, calling it “a step in the right direction.”

But she said, “The most important components were buffers,” Bounds said. Many areas cities have buffers ranging from 1,000 to 1,500 feet.

“Would it really cost jobs to move the buffer another 400 feet?” she said.

“There is good science backing up [the health risks] to proximity,” said Jim Schermbeck, leader of the environmental group Downwinders at Risk. Five or 10 years from now, he told the council, “you'll regret not doing this now.”

Another group, Citizens for Mansfield, formed recently to support the proposed ordinance as is and to counter demands for wider buffers. Its members and other speakers told the council that anything near a 1,500-foot minimum separation from the public would effectively ban new well development.

Ed Ireland, executive director of Barnett Shale Energy Education Council, said that as the industry has drilled 20,000 wells over the years, “ozone levels and other pollutant levels have declined.”

“There's never been a wellhead fire in the Barnett Shale,” Ireland said.

Among the changes in the proposed ordinance: