The city of Spokane expects to issue about $65 million in bonds next year and $100 million in 2015 to fund future phases of its integrated clean water plan to reduce the volume of untreated discharges into the Spokane River.

Similar to hundreds of U.S. cities, Spokane is adding infrastructure that better manages wastewater and stormwater runoff to reduce pollutants entering waterways as required by the federal Clean Water Act and other regulations.

By year-end 2017, Spokane must reduce by a substantial volume its combined sewer and stormwater runoff that flows into the river during major storm events, under rules of that federal water act.

Upcoming expenditures of up to $350 million are expected for projects over about five years involving combined sewers, stormwater drainage, and another level of treatment at the city's Riverside Park Water Reclamation Facility, says city spokeswoman Marlene Feist.

While city ratepayers ultimately will pay toward much of the improvements, the city also will rely on revenue bonds and other funding sources, Feist says. She says Mayor David Condon has set a goal that any increases for city ratepayers won't rise above an annual cost-of-living index, or more than 2.9 percent annually, "even with these huge investments."

"We're trying to maximize use of grant dollars, plus low-interest loans," Feist says. "I expect we'll have to bond probably in the next six months."

Already, the city has spent about $220 million on wastewater and stormwater system upgrades since 2000, including $175 million at the water treatment plant, located at 4401 N. Aubrey L. White Parkway.

In March, Condon outlined new strategies for a city clean water plan that includes prioritizing projects by what most significantly reduces pollutants going into the river, and integrating steps to reduce stormwater runoff with upgrades to streets, parks, water mains, and city landscaping.

"The integrated clean water plan framework came about because a lot of mayors across the country were realizing that stormwater was as big an issue as the combined sewer overflows are," says Rick Romero, the city's utilities division director.

Romero adds, "With stormwater, you've got PCBs (polychlorinated biphenyls), metals, and other kinds of toxins."

The city's integrated plan also sets out a goal to use more landscaping and permeable ground features as ways to absorb and filter stormwater runoff. These types of projects include what are called "rain gardens," which can be landscaped features in a narrow strip along streets that have a small depression in the ground with native plants and soils, Feist says.

Feist says city engineers recently have used computer modeling to evaluate all major discharges into the river, identifying problem spots and outlining projects aimed at better managing overall stormwater and wastewater flows throughout the city's entire system.

In Spokane, about one-third of stormwater goes directly into dedicated stormwater-only drains, mainly on the North Side, while another third goes into the grassy swales, drywells, evaporation ponds, and other means by which the runoff flows are absorbed or evaporate.

An estimated third of the city's runoff from heavy rains and rapid snowmelt goes into areas with a combined wastewater and stormwater sewer system. When big storms send more runoff than the treatment plant can handle, that system redirects some combined stormwater and untreated sanitary sewer wastewater into the river from 20 overflow outfalls.

Major work is scheduled by the end of this year and in 2014 specifically to reduce what are called combined sewer overflows (CSOs) originating from older sections of Spokane. The efforts include installing some massive underground tanks in major drainage areas to capture excess stormwater. When storms subside, the water in the tanks then can flow to the city's treatment plant.

The U.S. Environmental Protection Agency and the Washington state Department of Ecology are mandating that, by the end of 2017, combined sewer overflows into the river must be reduced to one overflow event per discharge site per year, Feist says.

"Right now, we have overflows multiple times a year," Feist adds. "We're working to reduce that."

Currently, some 54 million gallons of combined wastewater and stormwater enters the river annually through the 20 combined sewer discharge points, Feist says. She says city projects in the past few years have included installing eight wastewater overflow storage tanks and removing four outfall pipes to the river. The city also modified seven control devices in various pipes to reduce flow.

To build the city's next sewer overflow containment project, Clearwater Construction & Management, of Spokane, is the apparent low bidder at $4.7 million to install a 1 million-gallon tank this fall on a vacant lot the city owns at 21st Avenue and Ray Street. Construction is scheduled from October through fall of 2014.

The project is located in a basin that drains from the Lincoln Heights area through the west half of the East Central neighborhood and connects to an interceptor just south of the Mission Street Bridge. Feist says that in addition to stopping overflows from eventually entering the river, the South Hill project also is expected to prevent some basement flooding near the area that occurs occasionally.

Additionally, a 1.5 million-gallon tank for combined sewer overflow is scheduled to be installed at Underhill Park, at 2910 E Hartson, Feist says. Estimated at about $12 million, that project likely will go to bid in November, tentatively for work to begin in February. The city also plans to rebuild the parking lot under which the tank will be installed, Feist says.

Another longer-term project still in the conceptual phase would place a 4 million- to 6 million-gallon underground tank at Glover Field, located at 214 N. Cedar in Peaceful Valley. This project would serve the combined sewer overflow basin that covers most of downtown, Feist says.

"We'd like to reach that tank with a pipe extension that could be covered with a trail that would run from about City Hall to Glover Field," she says.

Romero says that at Glover Field, the early plans call for about a 30-foot-tall tank built against a grade near West Main Avenue and level to that road, with the tank to be covered by a new parking lot and better access to Glover Field. This project likely won't be built before 2016 or early 2017, he says.

To improve infrastructure in other areas of Spokane, the city also has identified projects to reduce discharges from its separate system of stormwater-only dedicated drains and piping that takes storm runoff into the river and that isn't part of the combined sewer system, Feist says.

From the city's separated storm drains, about 1 billion gallons of untreated stormwater enters the river each year. Romero says about half of that stormwater comes from a big North Side basin that eventually flows into the river from an overflow pipe located near the T.J. Meenach Bridge.

To mitigate that, Romero says the city is planning to use undeveloped portions of the city-owned Downriver Golf Course property, at 3225 N Columbia, to build some holding ponds with grassy filtration and soils to capture and filter stormwater and allow water to percolate into the ground.

"Parks are quickly becoming an important partner as we look to clean up the river," Romero says. "We're looking for win-wins, such as enhancing a trail system, building out park amenities, as we build these improvements. If we're going to spend $350 million, how do we get multiple benefits from those dollars?"

Feist says the city has about half a dozen employees spending the bulk of their time on projects relating to the clean water infrastructure, but that those workers also perform other tasks for the city.

Rick Eichstaedt, executive director for the Spokane-based legal advocacy group Center for Justice, says the center supports the city's integrated efforts to solve water quality issues. Spokane Riverkeeper is one of the center's programs that seeks to preserve, protect, and restore the Spokane River.

"It's obviously important to us that the city meet its responsibilities under the Clean Water Act," Eichstaedt says. He says the group has met with city employees to learn about the new clean water plan and agrees that it makes more sense to "right-size" tanks in strategic locations and incorporate concepts such as park-like features to capture stormwater.