Shadle-area stormwater gardens will filter runoff

The city is contracting with the Lands Council on a pilot stormwater management project in the Shadle area.

“We are pretty excited about this,” said Mike Peterson, executive director of the Lands Council. It’s the first time the council – a local nonprofit organization dedicated to protecting the quality of life and the environment in the Inland Northwest – has contracted with the city.

The $30,000 project’s main focus is the construction of a few stormwater gardens, somewhat like the swales on South Lincoln Street, along streets and parking lots in the Shadle neighborhood.

Peterson said the street-side gardens will draw rainwater runoff from surrounding pavement and filter it through layers of engineered dirt, including a layer of a charcoallike material that filters out major contaminants like PCBs.

“When the water runs off the street it has many different contaminants in it, including oil,” Peterson said Tuesday morning. “The whole point is to keep contaminated stormwater out of the river and to clean it here, on the spot.”

This pilot project is part of the city’s new integrated clean water plan to manage stormwater and wastewater that impact the Spokane River.

The city has been under pressure from the Department of Ecology for years to stop the periodic overflows of sewage and stormwater into the Spokane River. One problem is that when it rains heavily, some stormwater is funneled into the regular sewer system which can’t keep up with the flow and then releases a mix of stormwater and sewage into the river.

The city is constructing stormwater overflow tanks that will hold some water back until a storm has passed and the wastewater treatment plant can deal with it.

The Lands Council will start the project by going door-to-door looking for property owners interested in hosting a stormwater garden. Properties located within the Shadle combined sewer overflow area – roughly bordered by Maple and Belt streets, and Garland and Rowan avenues – may participate.

“There’s about 4,000 households in that area,” Peterson said. “We hope to get a mixture of private households and businesses, and maybe some churches.”

The Shadle stormwater gardens will require less construction than the ones on South Lincoln, which were put in as part of a repaving project.

“A garden could simply be between the sidewalk and the street,” Peterson said.

The gardens will be planted with mostly native plants such as kinnikinnick and the Lands Council will maintain the gardens by weeding and picking up trash, Peterson said.

“We are looking at how we can reduce the flow of stormwater that ends up in the river,” said Marlene Feist, city utilities communication manager. “By capturing the water before it hits those pipes we can manage it much better.” Feist added that the city is looking at other types of green technology such as permeable pavement and other landscape features to help clean contaminants out of stormwater where it originates.

“Over time,” Feist said, “if you put in more green technology we will get a better bang for our buck.”