Water treatment

August 18, 2013
Water treatment

Committee studies alternatives for Bend’s surface water

By Hillary Borrud

A committee of Bend citizens is beginning to wade into the debate over how the city should treat drinking water from the Bridge Creek watershed.

The city originally faced a 2012 federal deadline to treat or filter its water for the parasite cryptosporidium, but it received an extension to October 2014.

City Manager Eric King said it is unclear what penalties the city might face if it misses that deadline. “We really don’t know," King wrote in an email. “The state has not been clear on what the potential fines would be."

City councilors favored a membrane filtration plant that would capture debris if there is a fire in the watershed, but they voted 4-3 in February to re-examine whether to build a less costly ultraviolet light treatment plant instead. The city formed the citizen advisory committee to research these options and report back with a recommendation to the City Council by Oct. 2.

On Aug. 14, the committee met to receive information about the cost and time required to build the membrane and ultraviolet treatment plants.

It might cost the city an estimated $30 million to build a membrane filtration plant, according to the Aug. 14 city presentation. The annual cost to operate this type of plant would likely be approximately $400,000.

An ultraviolet light treatment plant, which would deactivate the parasite cryptosporidium, would cost closer to $13.4 million, according to the city presentation. The city estimated operations would cost slightly less for the ultraviolet plant: $360,000 annually.

If the city builds an ultraviolet treatment plant, it could construct a bare bones version or one that would include the basis for the city to later add a filtration system, consultant Peter Kreft, of the engineering and construction company MWH Global, told the committee. The city hired Kreft to help the committee gather information, said Assistant City Engineer Jeff England.

There is a limit to how much sediment is allowed in municipal water, so if a wildfire sends debris into Tumalo and Bridge creeks, it might force the city to rely solely on groundwater wells.

In Oregon, more than 200 municipalities rely on surface water. Bend is one of only four — the others are Baker City, Reedsport and Portland — which do not have filtration facilities to remove cryptosporidium, according to Oregon Drinking Water Services. The federal Safe Drinking Water Act required municipalities to begin filtering surface water in 1991, but these four cities received exemptions and delayed building water treatment facilities for decades due to their relatively pure water and protected watersheds. However, a recent cryptosporidium outbreak in Baker City was a reminder of the potential for waterborne illness.

In 2006, the U.S. Environmental Protection Agency issued a new rule that required all surface water systems to treat for cryptosporidium by 2012.

City employees expect to miss Bend’s extended October 2014 treatment deadline regardless of which treatment option officials select. A membrane filtration plant could begin operations in fall or winter of 2015, and an ultraviolet plant might be up and running by fall or winter 2016, according to the presentation. This is at least partly because the membrane plant design is nearly complete, whereas the city would have to design an ultraviolet plant.

Kreft told the advisory committee that the city has already invested more than $5 million in the design, permits and other preparations for a membrane filtration system.

Sonia Andrews, the city’s chief financial officer, told the committee the city will have approximately $8 million in reserves to put toward the treatment plant. However, that could change if ratepayers reduce their water usage, or if there is an unexpected increase in water system maintenance costs.

“So I don’t want to just promise you guys there’s this $8 million sitting there," Andrews said.

— Reporter: 541-617-7829, hborrud@bendbulletin.com

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