A nifty project on Spokane’s south hill offers a glimpse at how a commitment to creativity and good design can improve a neighborhood, save tax dollars, and help protect the Spokane River.
On a crisp, blue morning the scene on Lincoln Street near Wilson elementary school is a dauntingly loud and earth-shaking departure from what you’d expect in one of the city’s quieter neighborhoods.
There’s no way around it. Rebuilding a street is a noisy, traffic disrupting, nerve-rattling business. But as long as you have to do it, you’d want to do it the way the City of Spokane is doing it on south Lincoln. Because this time the earth-moving and re-engineering isn’t just to re-build an important north-south street, it’s also to help the Spokane River.
That’s why one of the guys in hard hats, on this crisp, blue morning in May, is Spokane Riverkeeper Rick Eichstaedt and he likes what he’s hearing and seeing.
“Stormwater has a major effect on water quality in the Spokane River,” Eichstaedt explains. “The best way to address it is through infrastructure, looking at our roads, looking at the way we design things like parking lots and roofs. So the project we’re looking at today is part of an effort the city is taking to address and mitigate how roads contribute to stormwater.”
It’s actually two projects folded into one. The street work is funded by a voter-approved bond issue to upgrade city streets. But rebuilding the street also presented an important opportunity to attack a problem with stormwater that contributes to water pollution in the Spokane River. So the city’s sewer department is also spending money on the Lincoln Street project both to treat storm water at its source and to ease the burden on the city’s wastewater treatment plant in west Spokane.
Part of city designer Steve Hanson’s scheme for the stretch of Lincoln Street between 29th Avenue to the south and 17th Avenue to the north is to use multiple curb extensions–basically contoured peninsulas that re-define the boundaries of the street.
What motorists and pedestrians will notice right away is that the extensions narrow the street and calm traffic. What’s less visible to the naked eye is that the extensions are actually carefully designed “rain gardens” (a.k.a. “storm gardens”). The rain gardens will use native and other drought tolerant plant species (i.e. Creeping Mahonia, Kinnikinnick, Blue fescue) to anchor biofiltration cells in the curb extensions. The purpose of the biofiltration cells is to absorb and purify stormwater, as much as 86,000 gallons per rainfall event. 
The naturally treated stormwater that flows out of the cells will be collected in a separate drainage system. Only if a storm event overwhelms the diversion capacity of the biofiltration system will the stormwater re-emerge into the street where it can be captured by a separate drainage system that routes it to the city’s sewage treatment plant.
“What will happen is that the rain water goes through the curb slot into the rain gardens,” explains senior city engineer Lars Hendron. “It’ll then soak down through the soil into a perforated pipe that’s underneath, and then it will be carried down to the pond.”
The “pond” Hendron referred to is the Cannon Hill pond, and feeding the cleaned stormwater down to the pond (in a swath of park land just west of Manito Park) is another dimension of the Lincoln Street project that directly and indirectly helps the Spokane River.
The direct benefit is that, like much of the south hill, wastewater in the area of the Lincoln Street project would ordinarily be shoved into a combined sewer. Ordinarily, that’s not much of an issue. The combined rain water and sewage goes to the city’s treatment plant.
But in large rainfall events the combined sewer infrastructure simply can’t handle all of the water pouring into the system. It then overflows and the excess water (containing both stormwater and sewage) is diverted to outfalls along the Spokane River and Latah Creek.
In 2008, the CSO basin serving this area of the south hill had 15 documented overflow events, discharging an estimated 2.48 million gallons of untreated wastewater (stormwater and sewage) to the river. It’s a significant ecological and public health issue for the river, and a legal problem for the city, which needs to address CSO basin discharges to comply with the Clean Water Act.
Keeping stormwater out of the CSO system can only improve the odds of avoiding overflow events. More certainly, it will save money. It costs $1,000 to treat a million gallons of wastewater at the sewage treatment plant, so over time the diversion of stormwater to rain gardens and the Cannon Hill pond will save money.
It will also save water. The Cannon Hill pond has a leak in it, and requires 26 million gallons a year just to sustain its water level. That water comes directly from the Spokane aquifer which, of course, is a source of clean, cold water for the Spokane River. By diverting the stormwater from Lincoln Street to the pond, it will at least make a dent in the city’s make up water for the pond. Moreover, if the city’s current plan to seal the pond later this year comes to fruition, then it’s at least possible that the cleaned stormwater off Lincoln Street can provide much, if not all, of the water needed to maintain the pond.
One of the people joining Rick Eichstaedt on the tour of the project earlier this month was Teresa Rowell, the mother of a first grader whose daughter was introduced to the pond last year by her kindergarten teacher. The teacher was beginning to educate her young students about the ecosystems of local ponds but was dismayed to hear of the city’s plan.
“She’d heard that they were going to funnel all the stormwater to the pond,” Teresa said, “and she was concerned that this was a bad thing, that it would kill all the plant life, because of the Lincoln Street project. So I said I would follow up on that, and that’s what I’m doing here today.”
Teresa said she didn’t know about the plan for the cleansing rain gardens until that day’s tour. What she was learning was putting her at ease.
“I don’t feel like it would be the death of the pond,” she said, after hearing from Hendron and others explain how it would work. “If eventually the city can wean the pond off city water, that would save everybody money.”
“It almost seems like common sense,” says Eichstaedt, “but these are the kind of actions that we need to be taking to protect our river from stormwater. And it’s much more efficient to keep stormwater from going into the pipes and keep it out of the stormwater system, than it is to try to treat it with conventional pollution controls.
“One of the things I’d like to see us do as part of a ‘complete streets’ process is to really make this a complete ‘green’ streets program and not only look at what sort of bike and pedestrian and car amenities we can put on streets, but look at stormwater as well, like we’re doing here on Lincoln Street, so that we’re bring it all together for efficiency sake.
“It doesn’t mean that these opportunities are always going to exist, but this should be part of the decision-making process that we go through.”
–CFJ
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