The Country Homes Boulevard Restoration Project was a water-quality retrofit project constructed in 2014, and is located in north Spokane, approximately five miles from the city center, in a highly urbanized area within a high ADT (26,350) Urban Principal arterial roadway.
The nearly one-mile long center median area between the traveled lanes, in its pre-construction state, was a V-ditch asphalt channel situated within a 100-year floodplain corridor that conveys stormwater and groundwater from the Five Mile Watershed.
The channel also conveyed all of the surrounding road runoff to another Spokane County regional stormwater facility located at the corner of Price Avenue and Wall Street. The Price and Wall facility provides water quality treatment but was not large enough to provide adequate treatment for the 133 acres of pollutant generating impervious surface (PGIS) that drained to it.
Prior to these two projects, there was no water quality treatment for the pollutant generating impervious areas. Post-construction the two projects, in combination, provide 100% of the water quality treatment per today's standards. The finished project includes a 48-inch sub-surface squashed pipe, required to continue to provide flood control conveyance for the 100-year storm and groundwater, and a low-impact hybrid raingarden / bio-infiltration swale on top for water quality treatment.
The new treatment area includes 18 inches of bio-engineered topsoil and a wide palette of plant material. The plant material was chosen to accommodate several purposes: provide regeneration of the organics in the soil (for pollutant removal), uptake pollutants into the roots of the plants, fill in and grow thick like a barrier (for traffic calming and to lessen the need for mechanical weeding), be tolerant to snow and deicer that may be placed along the edges and within the facility during larger snow events, plus be aesthetically compatible to the surrounding neighborhoods, pleasing to the eye.
This project incorporate a permanent public education element through interpretive entrance features at both ends of the project, including banners mounted on the adjacent light poles that mimic the same message with regard to the hydrologic cycle and how the facility treats stormwater prior to reaching the river or aquifer.
The 2013 Fall Newsletter (PDF), sent to adjacent property owners, provided an overview of the project. Read it first, then check out the Project Overview and FAQs that follow.