Wells
‘non-detect’ for perchlorate for third straight month
Once again the monthly report on the presence of perchlorate in 13 city wells, including three where the chemical had previously been found, has come back clean. Or at least non-detect, according to City Manager Ed Tewes who made the announcement to the Council and the public Wednesday night.
He also urged water conservation by residents in the face of an emergency water situation that caused one of the closed wells to be brought back on line for a few hours Wednesday to increase reserves.
Even though the three wells have consistently tested non-detect during the past three months, they remain off-line, a situation that caused a near crisis on Tuesday when the water supply was teetering on the edge of comfort.
“Last night we went to the lowest level of storage in our reservoirs in the entire year,” Tewes said. “We fell to a level that is just above your master plan limits, trying to have a 25 percent supply in reserve.”
Tewes said the reserves are important for fire protection or if other wells go off-line for any reason.
“For a short period of time this evening, we are bringing the Nordstrom well on line for eight to ten hours in order to bring up the levels,” he said.
Tewes stressed the importance of conservation.
“It’s needed now more than ever,” he said.
The weather forecast is for warm, but not hot, temperatures, a situation that should help reduce the demand.
The detect level is 4 parts per billion and the city, responding to state and federal mandates, does not ask for testing below that level.
“Our plan is to follow rigorous state mandated protocols,” Tewes said on Thursday. “The Department of Health Services regulates and establishes the standards.” Those standards are 4 ppb, the level at which action must be taken, namely notifying water users of the chemical’s presence.
What levels are actually safe to consume have not yet been determined.
The city has never asked its laboratory to test below 4 ppb.
“I could not say if there is perchlorate below 3.9 ppb in city water,” Tewes said. “Four parts per billion is the lowest level for which there is reliable testing in labs certified by the state.”
In January 2002 the state DHS reduced its action level from 18 ppb to 4 ppb to provide a wider protective buffer for the public. The state only began to require statewide testing for the chemical last year.
“The Council has adopted a conservative approach,” he said, “with monthly tests.” Council also had previously ordered three city wells temporarily shut down when perchlorate levels above 4 ppb were discovered in recent months, which they did not have to do. The state mandates closure only when levels are considerably higher.
To insure the quantity and quality of municipal water supplies, Tewes said, the Council has ordered a package treatment plant to be installed at the Tennant and Nordstrom wells. Work on the Nordstrom well has begun but four of 10 (treatment) vessels did not function and will be replaced.
“We are still testing at Tennant,” he said.
