Work begins on second water-treatment plant

Cedar River supply will taste better for 1.3 million people around Seattle

Thursday, June 6, 2002

By PHUONG CAT LE
SEATTLE POST-INTELLIGENCER REPORTER

Seattle and suburban communities should expect better-tasting tap water once Seattle builds the second of its two multimillion-dollar treatment plants.

At Lake Youngs in Renton yesterday, Mayor Greg Nickels broke ground on the Cedar River Treatment Facility that could disinfect up to 180 million gallons of water a day when completed in 2004.

It's the largest such facility in the world that uses ultraviolet light to disinfect and zap disease-causing microbes such as cryptosporidium and giardia, city officials say.

The Cedar River supplies 70 percent of the drinking water used by 1.3 million people in Seattle and surrounding suburbs. The city's Tolt River supplies the other 30 percent.

For decades, Seattle has relied on protected but unfiltered water sources from the Tolt and Cedar rivers to provide clean drinking water.

Over the years, state and federal water quality standards have become stricter, and the city has had to improve its water quality.

The Cedar River facility is being built as part of an agreement the city reached with state regulators in 1992 after water supplies showed levels of fecal coliform that exceeded standards. The city was required to come up with a work plan, said Elizabeth Kelly, project director with Seattle Public Utilities.

The new facility will cost $78 million to build and $31 million to maintain for 25 years. The city will own the treatment plant, but the contractor will operate it.

The project will be funded through water rates and bonds. But customers shouldn't see a new rate increase for this particular project, SPU spokeswoman Susan Stoltzfus said.

In late 2000, the city opened its first treatment facility at the Tolt River, a $101 million filtration plant, to provide a more reliable water source.

Unlike the Tolt's water, water from the Cedar River still isn't filtered and won't be. The city keeps humans and development out of the watershed as the first step toward keeping the water clean, Kelly said.

The Cedar River facility will use an unusual two-step disinfectant process -- first ozone and then ultraviolet light.

The result? "More reliably good-tasting water to our customers," Kelly said.

"The whole industry is excited about UV because it will be lower in cost," she said. "We're on the cutting edge here with the treatment process."

In the first step, oxygen is converted into ozone using an electrical discharge. The gas is then bubbled through the water, killing bacteria and removing compounds that cause bad odor and taste.

Then UV, both from natural sunlight and installed lamps, is used to further disinfect and zap disease-causing parasites, including cryptosporidium.

The project also is unusual because the city hired the same contractor, CH2M HILL, to design, build and operate the water-treatment plants. Having one prime contractor saved about $50 million.

P-I reporter Phuong Cat Le can be reached at 206-903-0370 or phuongle@seattlepi.com

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