The neighborhood around a water-treatment plant is still jittery after a Feb. 13 chlorine gas leak sent four children, a firefighter and two plant employees to the hospital.

None of the people treated for ill affects suffered from the chlorine was seriously injured, although fire Capt. Todd Hyer was hospitalized overnight.Engineers that supervise the plant's operation are working on changes that would prevent a future accident.

Byron Jorgenson, Sandy's chief administrative officer, said Thursday that residents near the plant, at 116th South and 25th East, need to know what's going on to ensure safety at the plant. Meanwhile, Jorgenson said he can understand why stray odors in the air cause concern.

Besides being Sandy's chief administrative officer, Jorgenson serves on the board of the conservancy district that operates the treatment plant. He lives in the affected neighborhood, and his daughter was one of the children treated at the hospital after being exposed to the chlorine while she was walking to Lone Peak Elementary School.

"People are smelling things all the time," he said of his neighbors since the leak. "I get calls at the city, and they call my wife at home."

Sandy firefighters have been dispatched to the treatment plant several times since the leak after someone saw an unusual cloud or smelled something foul, Jorgenson said. On none of those subsequent occasions did firefighters find a leak at the plant.

The treatment plant, operated by the Salt Lake County Water Conservancy District, was being activated the day of the leak after spending the winter in mothballs.

Chlorinators at the plant were activated at 7:30 a.m. A woman who lives near the plant was outside when she smelled the gas and called the fire department. Firefighters from all three Sandy fire stations scrambled to the plant after getting the call at 9:19 a.m. Firefighters went a second time that day after another leak was reported.

Richard Bay, the conservancy district's acting chief engineer, said the leak has been traced to a valve that did not close properly because it was obstructed by corrosion that migrated from an adjacent section of pipe. The leak was hard to trace because the gas collected in ventilation ducts that were isolated from gas-sniffing sensors inside the room where several two-ton tanks of chlorine are kept.

A ventilation fan, that turns on automatically when gas is detected as a safety measure for workers inside the building, started several times during the leak and pumped the escaped gas into the outside air.

Similar ventilation systems are used at other water-treatment plants in the valley, Bay said. But changes are planned at the plant in Sandy and at other treatment facilities operated by the conservancy district to capture escaped chlorine gas.

Filtering scrubbers could be added to the ventilation stacks to trap escaping gas before it leaves the plant. Another option would be to build containers that would trap escaped gas on site.

Bay said the first change will be to add leak detectors to the ventilation system.

The conservancy district board approved a measure Thursday that would reimburse medical expenses that resulted from the February accident. District officials also will inform the residents surrounding the plant of new safety measures once they have been implemented.