Human error put lye in water

The state Department of Environmental Protection said yesterday that operator error was responsible for the excess of sodium hydroxide in the Spencer public water supply last week, creating an emergency that spanned several days.

Martin Suu-berg, regional director of the DEP’s Central Region office, said that based on interviews and an investigation with the help of the state Environmental Police, it was determined that operators repairing a leak in the sodium hydroxide feed system had left the apparatus in “manual operation mode.”

Once the repairs to the feed pump were made, the oversight came in not returning the sodium hydroxide feed pump to “automatic” operation.

Without naming the two operators, Spencer Town Administrator Carter Terenzini said they had been reassigned to other duties within the Utilities and Facilities Department.

In the interim, he said, licensed operators from Weston & Sampson Engineers Inc. of Peabody had taken over the operation of the water treatment plant and pumping station.

On any given day, that feed pump metes out sodium hydroxide to maintain a pH level that prevents the leaching of lead and copper from domestic plumbing.

Because the feed pump remained in manual mode overnight, 34 gallons of sodium hydroxide was put into the system over a period of 12-1/2 hours without proper dilution.

The regional director said that when the pumps at the Meadow Road well and treatment plant came on at 4 a.m. April 25, in response to the demand for water, the undiluted slug of sodium hydroxide — lye — began to move through the distribution system.

In subsequent testing, the highest pH recorded, 9.58, was on Route 31 north. The neutral pH level is 7. Levels below that are acidic, and above it are called basic; the maximum pH possible is 14.

Mr. Suuberg said that while alarms sounded within the treatment plant, no alarm messages were sent to the treatment plant operators, who recognized the error shortly before 7 a.m. April 25 and returned the system to automatic operation.

The anti-corrosion system was shut off after the discovery of the excessive lye in the water system, and remains off, Mr. Suuberg said.

He said the agency is continuing its investigation as to why the alarm system failed to notify the operators overnight.

Mr. Suuberg said that as a result of its investigation, the DEP would refer the two licensed water system operators to the Board of Professional Licensure.

Mr. Suuberg said the DEP would continue to evaluate the alarm system malfunction before issuing orders pertaining to alarms and other safeguards to prevent such an incident from recurring.

The regional director said the sodium hydroxide feed system that safely metes out 25 to 30 gallons of diluted anti-corrosive over a 24-hour period would remain offline, until the review and investigation had been completed and DEP had approved modifications to the feed system.

He also said the investigation would look at any other pertinent operational issues, and the appropriate enforcement orders would be issued after the investigation.

Mr. Suuberg said the town and all of its employees, including the two water system operators, had cooperated fully in the investigation and Mr. Terenzini praised the DEP for its speed in bringing its preliminary findings to the public.

Both men characterized the act that triggered the water emergency as an accident or simple oversight, and said there was no criminal intent.

Mr. Suuberg said the matter was investigated by Paul Anderson, Andrea Lemerise and Eugene Brunelle of the Central Region office’s Bureau of Resource Protection, as well as Lt. Gail Larson, Sgt. Patrick Haley and Officer Chris Baker of the state Environmental Police.

As a result of the excessive amount of lye in the town water system, more than 100 people received medical attention at a decontamination center in East Brookfield and at Worcester hospitals, and at least one resident was hospitalized for two days with internal burning and irritation of the esophagus and lungs from exposure to the town water.