AUBURN — A malfunctioning computer controller sent the lake water pumps into overdrive last week at the Lewiston-Auburn ultraviolet treatment facility, flooding the building and forcing a weeklong cleanup effort.
Auburn Water District Superintendent John Storer said a programmable logic controller, known as a PLC, which pumps Lake Auburn water into the treatment facility, failed at about 2:15 a.m. Jan. 26.
With the controller locked on, the pumps flooded the facility floor, including the mechanical and electronics room, the laboratory and offices.
The system stopped pumping water to both Lewiston and Auburn customers right away, and Storer said Auburn service was restored by 10 p.m. Lewiston service was restored by 10:30 p.m.
"We probably could have started back up sooner, but we wanted to make sure that all of the diagnostic equipment was set, all the chemical systems were set and all the individual components were set," Storer said.
The cleanup effort was further complicated by an ice-clogged culvert outside the facility.
"The water was supposed to drain out of the facility down into the culvert, but we couldn't get the pipe to open because of all the ice," Storer said.
Crews had to remove several dead or fallen trees and one living tree to make room for the culvert work, he said. Crews had to deepen the culvert, adding a drain pipe under the driveway leading to woods along the lake.
Once the culvert was opened and the water began draining, staff from the Lewiston Water Department and Auburn Water District mopped up the facility. Cleanup crews removed the bottom foot of Sheetrock from the facility's walls to help dry them.
"We've had everybody in here with shop vacs, drying things up," Storer said. "We had fans blowing everywhere. It's been a long series of nights, all week for everybody."
Storer said the facility is mostly dry and back to normal, but the ultraviolet reactor, which is designed to bombard water from Lake Auburn with UV radiation to sanitize it, remains offline.
"We're relying on Auburn and Lewiston's historic method of treatment," Storer said. "We're using free chlorine and then we add ammonia to make chloramines. So people shouldn't notice any difference in their water. It's the same old thing."
The UV system was built in 2010 between Turner Street and Lake Auburn, north of Central Maine Community College. It came online late in 2011. It's designed to meet federal standards requiring water providers to use at least two methods to disinfect drinking water. The federal standards are set to go into effect in October.