About six months after a controversial fluoridation stoppage was discovered at Gilbert’s North Water Treatment Plant, the town has the system repaired and back online, fulfilling a voter mandate to pump small doses of the cavity-fighting chemical into the public water supply.

Gilbert spent $235,000 to fix the fluoride system after hazardous conditions prompted officials to shut down the pump in July 2011. Word of the system failure apparently never went higher than the town’s public works director, and months passed without any real effort to make repairs.

The Gilbert Town Council initially approved fluoridation in 2000, but a resident referendum forced an election on the issue that November. The measure passed with 54 percent of the vote, and fluoridation began in February 2002.

When the year-long stoppage was finally uncovered last August, Gilbert immediately put its public works director and water manager on leave, and both no longer work for the town.

Town officials then launched a major effort to improve communication within its water division’s other departments and in November hired PCL Construction to build a new fluoride-injection system.

The project wrapped up last month, and the new system became fully operational on Feb. 22, according to assistant town engineer Edgar Medina. The system includes several improvements from the initial, decade-old pump.

The new chemical-injection system allows the town to pump hydrofluoroslicic acid into a water reservoir through its own isolated piping arrangement, Medina said.

Construction workers also installed a concrete block enclosure area to house the system in the North Water Treatment Plant, near Guadalupe and Higley roads. The project also included new observation windows, a ventilation system, fluoride analyzer and an alarm to alert officials should something go wrong again.

Design flaws in the initial system may have led to its demise and created a potential health hazard to employees working in and around the pump area, according to town documents and statements from two former water division employees.

Gilbert had just one water-treatment plant when it began fluoridating its water 11 years ago, and town officials had opted to convert a system designed for adjusting pH levels rather than build an entirely new system.

However, that equipment wasn’t contained within a separate, well-ventilated room as fluoridation systems typically are, according to a town memo. As pipes, fittings and gauges on the pumping system began to corrode, white powder formed on the equipment, causing a burning sensation in workers’ eyes, nose and skin, the memo said.

Tests conducted in August 2011 — one month after officials halted fluoridation — found evidence in the powder of the hazardous chemical hydrofluorosilicic acid, which had apparently evaporated and crystallized, according to an industrial hygiene report by IHI Environmental.

Following the announcement that fluoride was not being added to part of Gilbert’s water supply, the town moved quickly to rebuild public trust and improve oversight of its water-treatment operations.

Last fall, the town contracted with Colorado-based CH2M Hill Engineers to perform an independent audit of its water operations, and the company found Gilbert to be meeting bare-minimum standards for safety and quality while struggling to deal with vacant positions and insufficient training.

The water-quality group has since improved quality control procedures and is expanding the use of project-management procedures, assistant to the town manager Nicole Dailey said. The town is also cross-training its staff to be better prepared for handling emergency situations, she said.

Deputy Town Manager Marc Skocypec said the town cannot accomplish its vision for “best in class” service without setting the highest standards for communication.

“We are deeply committed to looking at our operations and performing continuous quality improvements in order to ensure that our residents receive the best service possible,” Skocypec said.