FORT WORTH — Janice Colston is used to hearing strange noises from the natural gas wells across from her home in east Fort Worth.But when she heard a loud, continuous sound on the evening of Nov. 2 and opened her garage door to see vapors rising above the multi-well site, she knew something was wrong. She called Chesapeake Energy, the well sites operator, and then 911.I was very, very frightened. I did not know what in the world it was. I got in my car, and I got out of the area, said Colston, who said she fled so quickly, she left her dog behind.What Colston saw and heard, according to the citys report, was a spray of natural gas and wastewater escaping from a hole in a pipe that carries gas from the well. When natural gas rushes to the surface, it carries fluid and sand used in the hydraulic fracturing process, and that sand eroded a hole in the pipe, called a flow line, according to a city of Fort Worth report.The company eventually activated an emergency shutdown system, consisting of valves that close the flow line.City officials in Fort Worth, Arlington and Denton say such incidents are not common. More than 4,000 gas wells are scattered across Tarrant County, and there are more than 18,000 in the entire Barnett Shale, which covers all or parts of more than 20 North Texas counties.Fort Worth has responded to 28 reports of gas leaks at well sites since 2007, said Tom Edwards, senior gas well development inspector for the city. Arlington said it responded to one leak this year and one in May 2012. Two additional incidents in 2011 involved the release of natural gas by equipment designed to relieve pressure, said the citys Bridgett White.And, in March 2012, two safety valves at a Carrizo Oil & Gas well site in Mansfield failed. A third valve automatically shut down the well after about 20 minutes.The most dangerous recent event occurred April 19 in Denton, a well blowout that took about 14 hours to bring under control. It prompted the evacuation of four homes but caused no injuries.A blowout is a much rarer event; there have been 18 such incidents in the Barnett Shale since 2001, according to the Texas Railroad Commission. An industry worker was killed in one blowout, and one was injured in another.Otherwise, the city of Denton has reported only a small handful of incidents such as faulty valves, according to a city representative. Failure to communicateWhen something goes wrong on a well, public safety personnel and energy companies enact procedures aimed at minimizing the impact. State and local ordinances require emergency contact numbers to be posted at each site. Operators install emergency shutdown systems that allow either the company or municipal workers to close a well, sometimes from a remote location.Ed Ireland, who heads the industry-sponsored Barnett Shale Energy Education Council, called the shutdown systems highly reliable and simple to use.Most of these producing sites within cities have whats called the big red button. And thats the training: You enter the site and push the button, Ireland said.Those procedures didnt work as scripted, however, that evening at Chesapeakes well site at 6990 Ederville Road, at the southeast corner of Interstate 30 and East Loop 820, near Janice Colstons home.Four firetrucks and a hazmat team from the Fort Worth Fire Department responded to the leak. But a communications mix-up with Chesapeake and the initial failure of the shutdown system led to a delay in stopping the leak, Edwards said.The initial call to Chesapeake was misinterpreted as a complaint, not an accident, according to a city report. When the mistake was realized, personnel at the companys Oklahoma City monitoring center tried to remotely deploy the emergency shutdown system, but it did not activate.A local Chesapeake pumper, a company worker who maintains a well site, was notified and shut down the well remotely before arriving on the scene. City crews were at the site for about 20 minutes before the leak was stopped, and about an hour elapsed from the 911 call to when Fort Worth fire and police personnel cleared the scene.Tim Hardeman, spokesman for the Fort Worth Fire Department, said firefighters are trained to respond to gas well incidents and can shut down a well if it is absolutely necessary. They prefer, however, to work with the site operator because they are the experts on that particular subject matter, he said.This is one of the more unique ones, Edwards said of the Nov. 2 incident. He said the city will review its communications with operators and perhaps offer refresher training to fire personnel. Chesapeake has more than 1,200 wells in Tarrant County and more than 2,500 in the Barnett Shale. Spokesman Gordon Pennoyer said the company would not comment on the leak or its response.The hole that produced the leak was in a 90-degree joint in the wells steel flow line, according to the citys report. Chesapeake is replacing 90-degree joints with more gradual bends to reduce wear from sand and corrosion, the report says.No one was injured, and the hazmat team detected no hazardous materials, according to the city.Still, Colston questions the effectiveness of the response system. What would have happened if that had happened in the middle of the night and no one knew it and no one saw it? she asked.Fort Worth Councilwoman Gyna Bivens, who represents Colstons neighborhood, said she has questions about Chesapeakes response, such as what caused the call to be transferred to Oklahoma City and why the remote shutdown did not initially work.Some areas in the process I am not clear on or happy about in this moment, she said.Issues with sand and steelSand erosion has been cited in two other incidents.In May 2012, Arlington firefighters responded to 911 call that also involved a leak in the flow line on a well at a Chesapeake site off Matlock Road just south of Southwest Green Oaks Boulevard.Arlington fire personnel used the emergency shutdown system to close the well. An inspection revealed a one-inch hole caused by sand friction in the wells piping, according to the citys report.Sand erosion in a valve was also cited in the 2012 Mansfield incident.Anytime you have sand entrained at high velocity, it can erode steel, said Dan Hill, head of the petroleum engineering department at Texas A&M University. Erosion can also be caused by liquid droplets if the velocity is high enough, even on steel.But sand erosion is not normally a problem in a shale formation such as the Barnett, he said. Although sand is pumped deep into the rock as part of the fracturing process, the goal is for it to stay there, Hill said.Chesapeake was cited for violating Arlingtons drilling ordinance. Its one of just two leaks that have produced citations by the city.The other was in August, when a 911 call reported hissing and popping sounds from a well site on Eden Road in southwest Arlington. When fire personnel arrived at the Edge Resources well site, they activated the emergency shutdown system, but it did not fully close off one of two wells at the site.That well had to be closed manually, according to a city report. Edge was cited for failing to maintain an automated valve that closes a well. The company replaced the safety valves on both wells at the site, said Jessica Minley, gas well specialist for the city.Edge, based in Fort Worth, did not respond to the Star-Telegrams requests for comment.A beefy responseA communications problem related to a Chesapeake well in April 2011 prompted Arlington to tighten its regulations and responses related to gas wells.Firefighters werent notified for more than 20 minutes after 911 callers reported a loud hissing sound at the well near Texas 360 and Sublett Road. Chesapeake personnel shut down the well manually.Arlington riled gas producers when it proposed a $2,397 annual fee last year on each of the more than 300 gas wells in the city to fund emergency responders.The fee, the first in the Barnett Shale, is expected to raise about $800,000 a year, although the city is not collecting it yet, pending resolution of a lawsuit filed by two industry groups.But the city has already beefed up its response plan.It now maintains crews at two fire stations, one in the downtown area and one in the Wimbledon area in south Arlington, said Arlington fire Capt. Steve Hendrix, who oversees the departments response to gas well incidents. Those crews can generally reach a site within eight minutes, he said.After the incident, Fire Chief Don Crowson made a change to require 911 dispatchers to immediately notify the Fire Department in natural gas incidents. The policy was used soon after, on July 10, at another site that vented natural gas to relieve a rise in pressure.Those two incidents in 2011 did not produce citations because they involved pressure-control equipment operating as designed, the citys White said.The city has handed out 36 citations at Arlington gas well sites since the start of 2009. The vast majority involve noise or other nuisance, or some technical violation, such as inadequate signage or paperwork, according to city records. In Fort Worth, Colston remains wary, looking out her kitchen window each time she hears a noise.If I could move out of this neighborhood, I would move in a minute to get away from it, because I think they are that dangerous, she said. I dont think they ever should have been put into neighborhoods at all.