February’s melting snow hits nearly completed $200 million stormwater tank project in Spokane

The snow that has piled onto lawns throughout Spokane and lingered through a frigid February will eventually find its way to the city’s storm drains as temperatures mercifully climb for spring.

During the next several weeks, that runoff will test a nearly $200 million system that is nearing completion beneath the city’s streets and parkland, a multiyear effort that was lauded by Mayor David Condon before a panel of federal lawmakers last week and is intended to stop the decadeslong practice of raw sewage running into the Spokane River untreated.

“We’re in the final year of the largest infrastructure project that our community has ever seen,” Condon told members of Congress on Capitol Hill, urging them to consider further legislation to allow cities to embark on building programs like the one Spokane undertook six years ago. The project is funded by a portion of the utility bills paid by each water and sewer user within city limits.

Much of that work has occurred below ground; but what was easily visible to residents was the skyscraping crane that had been digging into a bluff near City Hall for the past two years to place a chamber capable of holding 2.2 million gallons of water when the city’s combined sewer and stormwater system is inundated with rainfall or snowmelt. At another locale, drivers heading home on Interstate 90 east of downtown could see the mounds of earth extracted from East Central’s Liberty Park to place a 2.1 million gallon tank that began operating in January.

The crane was taken down earlier this year, with the downtown tank scheduled to begin operating later this fall, and any mounds of earth left along Interstate 90 are the result of other projects, including the construction of the North Spokane Corridor highway project.

Spokane’s subterranean stormwater work is nearing its end. Another tank is also scheduled for completion this year near the East Sprague corridor.

“It’s just really the last three tanks,” said Marlene Feist, the city’s acting communications director who has worked with the utilities division on the project since its inception more than five years ago.

Those three tanks are among the largest to be buried in a process that eventually will be able to store more than 16 million gallons of stormwater in the event of a deluge. That’s important, because the city’s combined stormwater and sewer system is only able to handle a certain amount of water before the pipes divert any runoff and sewage away from the water treatment plant and into the Spokane River, in an effort to keep the city’s main runoff pipe from failing and causing sewer backups throughout town.

These diversions of combined sewer and stormwater, known as “outfalls,” must be limited under an agreement the city signed in 2011 with the Washington Department of Ecology to reduce pollution in the Spokane River. Under the terms of the agreement, there can only be one failure per site, per year, over a 20-year average.

“Essentially, if there were like two in a row, that’s cause for Ecology to work with the city on compliance,” said Brook Beeler, director of the Ecology Department’s regional office in Spokane. “If it’s one, then it’s OK, we’re watching.”

Also watching will be Spokane Riverkeeper Jerry White Jr., who has advocated against the city lobbying federal regulators from intervening in a state process that has established extremely strict standards for pollution discharge into the Spokane River. Condon has said those levels are immeasurable and would cost taxpayers exorbitant amounts of money to meet.

“We are certainly going to be watching to see if they are effective,” White said. “The city has to meet some pretty strict standards for discharges.”

In 2017, the city reported 144 outfall events at 26 monitoring sites throughout town, according to Spokane’s annual report on its discharges into the river.

Ecology has not seen any outfalls in areas of town where the city has installed a working stormwater tank, Beeler said. However, these discharges continue to occur in other areas and are reported monthly and annually to the Department of Ecology by the city of Spokane.

Those 144 outfall events released about 71 million gallons of untreated water into the river. Numbers have not been finalized for 2018, but monthly reports indicate a much drier year resulted in just 78 outfalls totaling 41.6 million gallons of untreated water entering the river, the lowest such total since 2013 as the city also completed work on multiple tanks capable of capturing millions of gallons of water to prevent outfalls.

White applauded the city’s efforts, but noted any discharge into the river from the combined sewer pipes would be a health hazard to those residents enjoying the river and the wildlife that depend on it.

“Really nothing is appropriate, no raw sewage is appropriate,” he said.

Most of the outfalls occur during the weeks of heavy snowmelt in late spring and then again during the rainy months of late fall, according to reports filed by the city.

With temperatures forecast to climb into the 50s for the first time since November, the tank at Liberty Park will likely see its first true storage test. So will the so-called “Silva cells” that were buried this summer beneath the streets of the West Central neighborhood, an alternative strategy that captures and disseminates snowmelt into the soil in smaller chambers scattered along street corners.

“It seems to be working just fine,” said Feist, with the city. “There’s still an outfall there, though. There’s still a safety valve if the water backs up.”

Also online for the first time in 2019 is the largest of the city’s tanks, the 2.3 million gallon chamber that was buried just west of the KHQ-TV studios downtown. Construction of the tank beneath a vacant lot on the west side of Adams Street between Sprague and First avenues began in spring 2017, and final construction will conclude later this summer when the city and the nonprofit Spokane Arts complete work on a public green space above the $24 million project.

“It’s going to highlight the automotive history of the neighborhood,” said Melissa Huggins, executive director of Spokane Arts. Lead artist Susan Zoccola created a pair of 12-foot-tall archways punctuated by rainbow-colored wheels suspended in air. Zoccola’s other work includes the wheat features hanging from the ceiling of Cheney Middle School and the steel “Wave Walls” inside the Seattle Aquarium.

The above-ground plaza also will feature areas for food trucks, an amphitheater for performances and future stops on STA’s Central City Line, Huggins said. Completion tentatively is scheduled around Hoopfest weekend at the end of June.

The city is sharing the costs of the plaza at First and Adams with the Art Commission while working on its own design for the tank behind the downtown Spokane Public Library branch. Final work on the tank built into a bluff overlooking Spokane Falls is expected to winnow Lincoln Avenue down to a one-way southbound road between Spokane Falls Boulevard and Main Avenue, Feist said.

“We’re going to get rid of the two-lane thing, two lanes that can turn to the right in front of the library,” Feist said, noting there were many close calls from people turning right off of Lincoln and then immediately changing lanes to head south on Monroe Street. The city also will return the pedestrian crosswalk on the west side of the intersection of Main Avenue and Lincoln Street.

Spokane Falls Boulevard behind the library will reopen to two lanes of traffic this spring, and there will be intermittent closures of both Spokane Falls and Lincoln as crews make pipe connections to the tank, Feist said.

While the city is focused on what’s being put in above ground, crews digging to bury the tanks discovered a few unique things of their own. Digging beneath what’s known as the Bosch lot, city-owned park property between Monroe and Post streets just north of the Monroe Street bridge, for the 800,000 gallon, $6.5 million tank revealed a railroad bridge abutment from the pre-Riverfront Park days that engineers reburied at the request of historians, Feist said.

Also revealed in Liberty Park was an old access tunnel believed to have been dug during the Great Depression by laborers with the Civil Works Administration, President Franklin Roosevelt’s employment program, in winter 1934. The small tunnel was planned to provide access from the west side of the park, where the tank now sits near an I-90 on-ramp, to the eastern edge of the park where a popular skating and swimming pond was located.

Unwelcome groundwater was discovered beneath a tank site near the old McKinley School at Riverside Avenue and Napa Street, pushing its completion back from the end of last year to this fall, according to a timeline provided by the city of Spokane.

After completing the tanks, the city will turn its attention to what’s known as the Cochran Basin as it also completes final upgrades to the Spokane Water Reclamation Facility northwest of town. The 5,000-acre stormwater plain in north Spokane is the single largest contributor of stormwater runoff to the Spokane River, created when the city separated its sewer and stormwater systems in that part of town in the 1980s. That runoff includes significant levels of polychlorinated biphenyls, or PCBs, a cancer-causing compound whose levels are limited by federal rules.

White, the riverkeeper, called it “the next 600-pound gorilla in the room.”

The city already has started identifying funding sources for that work, Feist said, and the potential treatment could include integration with the water features at nearby Downriver Golf Course.

“We think we can start work in 2020 on that project,” Feist said.