Lewiston irrigation restrictions still in place

Jul. 27—Lewiston's irrigation restrictions might extend through the weekend while personnel work through unanticipated challenges that surfaced when they were bringing the town's recently upgraded water treatment plant online.

Even though the process has slowed, Lewiston Public Works Director Dustin Johnson said Wednesday afternoon he still believes the city will meet its goal of lifting the ban on automated irrigation for most Lewiston water customers no later than Monday.

"We're taking it hour by hour now," he said.

The repairs at Lewiston's High Reservoir, which sustained a rupture in January, are complete and the pipe that connects it to the water treatment plant along the Clearwater River in east Lewiston is functioning, he said.

The Idaho Department of Environmental Quality has signed off on the reservoir repairs and water from the reservoir passed bacteria tests, he said.

But filling the reservoir with water from the treatment plant started on Tuesday, a day later than anticipated, Johnson said.

That was because the expert responsible for turning on the pumps that feed the water from the treatment plant to the reservoir got stuck in a road closure near a bridge at Vantage, Wash., because of wildfires.

Then the filling had to be suspended Tuesday when error messages appeared indicating pressure issues with strainers that remove sand, grit and dirt from river water before it's treated, Johnson said.

Crews cleaned the strainers, but they weren't entirely convinced that the amount of material they contained would have triggered the error messages, he said.

As of early Wednesday evening, the reason for the messages hadn't been identified and filling the reservoir was on hold while processes at the plant were being adjusted, he said.

"This is just part of any start-up process," Johnson said.

Those working on the problem include employees of Pall, the manufacturer of the new membrane treatment system at the plant; Imco, the construction contractor; and the city, he said.

"They will work out these kinks and they will hand it off to the city operators," Johnson said. "(I) want to be sure the city operators are comfortable before we lift the restrictions."

High Reservoir is the primary place that water from the water treatment plant goes, he said.

That made it impossible to bring the $30 million upgrade of the water treatment plant online at full capacity until High Reservoir's repairs were done, Johnson said.

The remainder of the city's water comes from wells and goes through a much less extensive chlorination treatment process on well sites, he said.

Right now, High Reservoir is about two-thirds to three-fourths full. Much of the water it contains is from city wells pumped into it from a hydrant last week so the city could run water tests and be sure it was sound before it was connected to the plant, he said.

Keeping the reservoir full with that method on a long-term basis wouldn't work. It was significantly slower than drawing from the water treatment plant and took water from other parts of the system, Johnson said.

Once the issues at the water treatment plant are resolved, the repaired High Reservoir should serve the same function for the long term as it did before it failed in January, he said.

A new reservoir cover that was recently installed can be replaced after its estimated 15-year life span ends, Johnson said.

The capacity of High Reservoir is less, somewhere between about 3 million and 4 million gallons, compared with its capacity of 4.5 million before the breach, Johnson said.

But that diminished capacity is more than adequate because of improvements at the water treatment plant, he said.

Previously, the facility had two settings, on and off. The process to bring the water treatment plant online was complex, something that complicated managing the facility because it is often offline in the winter when water demand is low, Johnson said.

The new system is designed to function more like a faucet and can run at a multitude of volumes, Johnson said.

"There's far more control in the output," he said.

Williams may be contacted at [email protected] or (208) 848-2261.