Note to Rusty Ward, Carrizo Oil & Gas vice president of regulatory affairs: Whenever there is a malfunction at one of your company's wells like the one that happened near two schools in Mansfield on Friday, take it very seriously.The initial report from Carrizo said a valve began leaking just before 8 a.m., venting an estimated 3,400 cubic feet of natural gas and about two barrels of water from the well on Debbie Lane near Matlock Road. The well produces about 6 million cubic feet of natural gas a day."That small amount of gas was completely on top of the atmosphere by the time you got to the wall of the drill site," Ward told Star-Telegram reporter Susan Schrock. "There was never any danger to a kid or residents."That's a little too dismissive.It's always dangerous when gas leaks from one of the hundreds of wells near Tarrant County neighborhoods and schools. Initial reports from Carrizo and fire officials said corrosive sand in the pipeline of a newly producing well caused a small rupture in a valve and allowed water and natural gas to escape.Arlington Fire Chief Don Crowson, whose personnel were called to the site to assist Mansfield firefighters, said primary and secondary safety valves failed before a third valve finally shut off the high-pressure leak after about 20 minutes. No gas was detected in the neighborhoods or schools downwind.Ward apparently saw no need for any great concern."This kind of stuff happens. You will have choke valves that will fail," he said. "There are so many redundant safety devices on these well sites. If one thing doesn't shut it down, something else will."That's sort of like the line from actor Tommy Lee Jones as space alien-chaser Agent K in the 1997 movie, Men in Black: "There was no alien, and the flash of light you saw in the sky wasn't a UFO. Swamp gas from a weather balloon was trapped in a thermal pocket and refracted the light from Venus..."A leak at a well site is a bad thing, and it's an even bigger problem when not just one but two safety systems fail to shut it down.Crowson takes such things very seriously. He recently persuaded the Arlington City Council to approve a gas well emergency preparedness and response plan.The city will charge gas companies $2,397 per well to pay for part of the plan.With that money, Arlington will create positions for a new fire captain, a gas well inspector and six additional firefighters, as well as pay for their specialized training in dealing with gas well emergencies.Separately, the city will pay for that kind of training for 42 additional firefighters.The idea is to draw up emergency action plans for each of the about 300 well sites in Arlington.The response team would not try to put out a major gas well blowout but would stabilize the scene and protect nearby residents until contractors hired by the gas companies arrive.Friday's leak at the Mansfield well delivers a simple message, Crowson says: "Things do happen at well sites."The Arlington Fire Department intends to be ready for any of those "things." Other cities in Tarrant County should take similar action to assure their own readiness.