WAKEFIELD — In a report, DPW Director Stephen Casazza has linked the cause of the elevated fluoride levels in the water system on Friday, July 28, to the apparent failure of a feed valve and the resulting “back siphon” of fluoride from the chemical feed system into the water supply at the Broadway Water Treatment Plant. The conclusion was endorsed by state officials and outside consultants, who also determined the town acted correctly in dealing with the fluoride overfeed situation.
Some have been critical of the way the DPW notified townspeople of the fluoride problem two weekends ago. One Bennett Street man, for example, wrote to Casazza and asked if anyone had become sick from “the poisoning.”
The selectmen are scheduled to discuss the issue at their meeting tonight.
Casazza detailed the series of events that Friday from the discovery of the elevated fluoride level in the water which began with pipe repairs at the Broadway facility between noon and 4 p.m. that Friday.
At 4:30 p.m. Water Division personnel noticed abnormal readings in pH and chlorine residue, readings which were attributed to debris in the pipes from the earlier repair activity. The facility was off-line during the repair and through the weekend.
In a random check Water and Sewer Supervisor Steven Fitzpatrick noticed the inconsistent readings and called in other water personnel. The elevated fluoride levels were identified at about 5:30 and the fluoride system was isolated.
Flushing of hydrants by Water Division employees and firefighters began soon after, with water samples taken adjacent to and approximately 100 yards from the Broadway plant. Initial readings at the plant showed 23 milligrams per liter of fluoride in the water, while another sample further away showed levels of 12.5 mg/L.
The Maximum Contaminant Level (MCL) under Massachusetts Drinking Water Regulations is 4 mg/L. Exceeding the MCL required the DPW to publish a drinking water notice in last Friday’s edition of the Daily Item which detailed that short term exposure to fluorides at concentrations less than 40 mg/L should not result in adverse health effects. The same notice also declared the incident was not an emergency but added those with kidney or liver problems may want to consult a physician because the fluoride in high concentration can affect both organs.
By 6:30 residents of the Crystal View Apartments were cautioned not to drink the water. Businesses along Broadway, North Avenue and Main Street were notified by Fire Department personnel, while police notified restaurant owners in the Square by 7:30. A water alert notice was distributed to local television stations and announced over Police and Fire department radio channels.
With the purging of the water system throughout the night, by Saturday morning fluoride levels in the system were found below 4 mg/L. The townwide precautionary water ban was in effect until six o’clock Saturday evening.
The specific cause of the overfeed was the apparent malfunction of an anti-siphon valve of the chemical feed pump during work on the pipes. A vacuum was created in the pipe as it was drained, the anti-siphon valve malfunctioned, causing the fluoride to be siphoned from a holding tank into the system.
Both Walter Pitts, engineer from the Cambridge firm of Camp Dresser and McKee Inc. — the town’s water quality consultant — and Frederick Barker, fluoride engineer from the Massachusetts Department of Public Health were brought in to assess the cause and the town’s handling of the situation. They agreed with DPW findings and actions.
The DPW will keep the Broadway plant — which pumps water from Crystal Lake and sends it to about 15 percent of the town — closed for a couple of weeks. Following are some preventive measures to be implemented:
-The chemical feed pump will be replaced with a new unit.
-The anti-siphon valve will also be replaced.
-A new injection nozzle at main with ball check valve will be installed.
– Secondary/ back up anti-siphon valve on the supply line will be installed.
-An in-line solenoid valve will be installed to ensure that the chemical feed system is closed when not in operation.
-Replace existing 50-gallon fluoride holding tank with a 12-gallon tank.
-Modify the analyzer monitoring pH so that it will trigger an alarm, which will notify a “call person” in the event of high pH levels.
In a memo incorporated into the report, Pitts stated, “In conclusion, I believe that the town did everything possible to cope with this emergency, the reason for the overfeed has been identified and the fluoride system will be upgraded to prevent any future occurrence.”