Even three years later, almost any review of the July 2011 accident at the Board of Water & Light’s Wise Road Water Plant leads to the same question BWL investigators pursued in the accident’s immediate aftermath.

How did a load of bleach end up being pumped into a fluoride tank, creating a corrosive cloud that sent three people to the emergency room and doing $23 million in damage to the plant?

BWL had taken safe delivery of chemicals to the plant for decades, had a long-service, “beyond competent” and licensed operator on duty, had mandatory safety protocols for handling every step of deliveries, and the fill ports for a bleach tank and fluoride tank are on different exterior walls (southeast and north, respectively) of the plant.

“I lay awake at night wondering what happened,” Water Director Dick Peffley, a 38-year veteran of BWL, told the State Journal.

Following procedure

Normally, the plant’s water systems operator — the only employee assigned to the plant on a daily basis — meets each delivery driver, Peffley said.

“They go through a tailgate meeting, which is going over the safety aspects of the job,” he said.

“We have the paperwork. It was filled out and the chemical got in the wrong tank. They may have checked the boxes, but if they had followed every procedure it wouldn’t have happened.”

Although he usually worked at the Dye Water Plant in downtown Lansing, water operator Chris Thompson was no stranger to the Wise Road plant or to the delivery of chemicals. Chemical truck driver Dan Wheaton, however, never had made a delivery to the Wise Road plant.

According to BWL’s internal investigation, Wheaton parked his truck at the loading dock and near the fluoride intake port and waited until Thompson came outside.

Accounts offered separately by Thompson and Wheaton are not consistent about what followed.

Wheaton submitted a statement through AmeriGas/Propane Transport International of Houston, for whom he was driving. According to Wheaton’s statement:

» After introductions were made near the loading dock, Thompson went back and forth between the inside of the plant and the loading dock several times. Thompson attached an adapter to the pipeline to the nearby tank “so my hose would hook up.”

» After Wheaton began pumping his load, Thompson emerged to say “there must be a leak” because he could smell fumes inside.

» “I went back to check with Chris and then I smelled the fumes and then Chris realized that he told me the wrong hookup location.”

According to a photo included in BWL’s investigative report, the fluoride intake pipe was clearly marked. Thus, neither Thompson nor Wheaton should have hooked the tanker truck’s hose to the fluoride pipe — assuming they knew the truck was delivering a different chemical.

Records obtained through a Freedom of Information Act request don’t speak to Wheaton’s familiarity with the contents of his truck.

He was delivering sodium hypochlorite, commonly referred to as chlorine or liquid bleach. His truck was connected to the fluoride intake pipe — fluoride being a common term for hydrofluosilicic acid.

It was incorrect for the BWL intake pipe to be labeled “FLUORIDE INLET” at the loading dock area outside the plant,” according to the Michigan Occupational Safety and Health Administration, which conducted a six-week investigation.

The BWL’s Thompson, who was interviewed by three BWL managers and his union’s business agent, admitted knowing chlorine, or liquid bleach, was to be delivered. While going back and forth between inside chores and the loading dock, he expected Wheaton to pull the tanker truck around the corner to the southeast side of the plant where the chlorine intake pipe was located.

When he “began smelling something like chlorine” bleach and returned to the back door of the plant, he said he was surprised to see the truck driver was still in the area of the loading dock. Distracted by multiple alarms going off in the plant, he went back inside without saying anything.

Only after rushing out the front door and running back to the loading dock did he notice the chemical truck hose was hooked up to the fluoride intake, at which point he told Wheaton to stop unloading.

BWL’s internal investigation was unable to determine whether:

• It was Thompson or Wheaton who installed the hose adapter to the wrong inlet pipe.

• Wheaton assumed the hook-up location was on the north side of the loading dock where the tailgate discussion was occurring.

• Thompson instructed Wheaton to hook up to the wrong pipe.

• Wheaton assumed he could start unloading when he was ready.

• Thompson gave the OK to start unloading while he was performing other chores inside the plant.

BWL ultimately concluded both men failed to follow their respective standard operating procedures.

“In attempting to ‘multi-task,’ ” Thompson took his attention off one critical task — filling the liquid bleach day tank — to perform another critical task — unloading a delivery of liquid bleach, BWL concluded.

While Thompson “was going back and forth between these two critical tasks, the driver hooked up to the wrong chemical inlet port and the mistake was not recognized by (Thompson) until it was too late,” BWL concluded.

Wheaton failed to verify the connection to the proper line for discharging into the proper tank, BWL reported. “Had the driver looked at the label on the chemical inlet port and compared it to the chemical specified on the bill of lading, the accident could have been avoided,” BWL concluded.

Insurance covered all but $500,000 of the $23 million repair cost, Peffley said. BWL is working with its insurer to recover its deductible from the trucking company. The plant operated through a combination of manual and automated activity until recently, when it returned to full automation.

Thompson cooperated with the BWL investigation, but retired without ever returning to work.

“It happened so quickly and the next thing I know I’m at the hospital and then I’m saying things and then there’s an internal report,” Thompson told the State Journal. “I felt like it was in my best interest to retire because I didn’t feel comfortable.”