COUNTRY HOMES BOULEVARD RESTORATION PROJECT
The Country Homes Boulevard Restoration Project was a water-quality retrofit project constructed in 2014, and is located in north Spokane, approximately five miles form 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, sent to adjacent property owners, provided an overview of the project. Read it first, by clicking on the graphic, then check out the Project Overview and FAQs that follow.
Images - Past To Present
What does CHBRP Mean?
CHBRP is an acronym that stands for Country Homes Boulevard Restoration Project. Throughout this County website, you will notice that references to the project will frequently involve the abbreviated form of the title, or CHBRP.
Why build the CHBRP?
- Spokane County’s NPDES Phase II permit, a permit required by the EPA and administered by the Washington State Department of Ecology, states that the County must provide water quality retrofit facilities in an effort to treat polluted stormwater before it reaches a surface water body or drinking water source.
- The Country Homes Boulevard channel is the main conduit for transporting stormwater runoff within the Five Mile Watershed to the Price and Wall Regional Stormwater facility. While Price and Wall is a water quality treatment facility, it does not have the capacity to treat all of the potential stormwater pollutants that reach the facility via the channel.
- Almost all of the pollution-generating impervious surfaces (i.e., roads, sidewalks, roofs, and driveways) that stormwater runoff flows across (starting from the Prairie on down to the channel) is currently lacking any stormwater pre-treatment.
- By restoring the Country Homes Boulevard channel, we approach meeting the treatment requirements of today’s water quality standards.
Why couldn't the Stormwater Utility just seal the cracks in the channel? Wouldn't that have been enough to keep the weeds from growing?
Sealing cracks is not a solution and would not prevent weeds from growing. Sediment would have always been transported from Austin Draw into the channel in its pre-existing state. Seeds would have continued to embed and grow in the sediment no matter how often the County removed the material.
Leaving the channel in its existing state would have meant stormwater that reached the asphalt channel would have been untreated.
Who financed the CHBRP?
Spokane County applied for and received two Washington State Department of Ecology Stormwater Retrofit grants totaling $1.75 million. These grants were a 75/25 match, meaning that one quarter (25%) of the project’s total cost was covered by Spokane County and the other three quarters (75%) was reimbursed by Ecology.
The Spokane County Stormwater Utility funded its portion of the project design and construction costs with fees previously collected from residents within the North Spokane Stormwater Service Area.
What were the project limits?
The Country Homes Boulevard Restoration Project began at Cedar Street and ended at Wall Street. A portion of the project extends through private property northeast toward the County's Price & Wall Regional Stormwater Facility.
The CHBRP did not involve replacing or increasing the number and width of traffic lanes. The County Traffic Engineer did elect to slightly narrow existing traffic lane widths in order to re-stripe existing parking and add new bicycle lanes along the Boulevard.
What was the projected timeline for construction?
The project started on May 27, 2014. Substantial completion was achieved by the end of November 2014.
People drive way too fast on Country Homes Boulevard. Will the project make it worse?
Studies show that vegetated medians have a calming effect on traffic, encouraging slower speeds as the landscaping helps to visually narrow the driving lane. In other words, the plantings and trees interrupt motorists’ views further down the street, rather than being able to see an endless length of pavement a long distance ahead. Research also indicates that the inclusion of trees and other streetscape features along boulevards may actually reduce crashes and injuries on urban roadways. In fact, accident rates on urban, tree-lined streets were reduced by 61% when compared to similar streets without landscaping and trees.
What regulatory permitting processes affected construction of the CHBRP?
- National Pollutant Discharge Elimination System Permit. The National Pollution Discharge Elimination System (NPDES) Permit was written and enacted in order to address polluted, non-point stormwater runoff. The Permit dictates that Spokane County programs and practices must be created for all new development, ensuring that stormwater runoff is being captured and treated in order to protect groundwater and surface waterbodies from further degradation.
- Conditional Letter of Map Revision (CLOMR). This conditional permit/certificate, issued by FEMA, was required due to the project being located within a designated floodplain. New hydrology for the area and hydraulic calculations for system design, along with resultant changes to the FIRM maps and floodplain elevations were submitted to FEMA in May 2012. The CLOMR was approved in May 2013.
- Letter of Map Revision (LOMR). The CLOMR process is being be repeated and a final LOMR will be issued by FEMA.
- Joint Aquatic Permit Application (JARPA). A JARPA was submitted by mid-September 2013. Multiple regulatory agencies (U.S. Army Corps of Engineers, Washington State Department of Ecology, Washington State Fish and Wildlife, etc.) joined forces to develop this application in order to streamline the environmental permitting process.
- State Environmental Policy Act (SEPA). Prior to submittal of the JARPA, a SEPA checklist was required and sent to affected property owners, the Spokane Tribes, and the Washington State Department of Archaeology and Historic Preservation. The County received a Determination of Non-Significance for the project.
- Habitat Management Plan (HMP). The HMP is referred to throughout the JARPA in order to demonstrate that all aspects of potential impact to the environment have been investigated and analyzed, and were accounted for before and during project construction.
How does the new bio-infiltration swale and subsurface pipe system work?
The new system is a combination landscaped bio-infiltration swale for treatment of stormwater runoff and a subsurface pipe to carry flood and ground water from Five Mile Prairie, plus serve as conveyance during large storm events; overflow structures are connected to the pipe.
Runoff from Country Homes Boulevard, and the neighboring side-streets, driveways, and sidewalks will either sheet flow into the new swale area and slowly infiltrate through the bio-engineered treatment soil, or, in places where side-street runoff is currently hard-piped into the existing asphalt channel, where constructible will now be hard-piped to the swale onto an energy dissipater.
Stormwater that is carried in the subsurface pipe may still outfall at the same termination point that it did in its pre-construction condition: at the Price and Wall Regional Stormwater Facility.
Will the swale be able to handle heavy rainfall in the same capacity that the existing asphalt channel did?
During large storm events, when the soil is saturated and the stormwater cannot infiltrate fast enough to keep up with the rate of precipitation, water will pond up and spill over into structures in the swale that are directly connected to the subsurface pipe. The subsurface pipe is sized to carry the 100-year storm but, in most sections of the pipe, can also carry the 500-year storm.
Will standing water in the bio-infiltration swale attract mosquitoes?
No. Mosquitoes need stagnant water to breed. While the engineered topsoil is designed to infiltrate slowly for pollutant removal, stormwater runoff should not pond in the swales for longer than 72 hours.
How will the bio-infiltration swale handle snow?
Vehicle-rated pullouts are sited alongside each overflow structure for facility cleaning, access for mowing and weeding, and for the placement of snow in winter months. There are also 2-foot gravel shoulders before the planting area to allow for additional snowpack storage. Plant selection involved materials that are salt, sand, and ice resistant.
Due to the height and density of the plant material, and the desire to be good stewards of the aquifer, a subsurface drip system is proposed for a high level of watering efficiency. Weather sensors will automatically make adjustments based upon on-site conditions. Other sensors can detect leaks, send alerts, and shut down the parts of the system that are leaking, all while continuing to irrigate elsewhere.
Who will be responsible for post-construction landscape maintenance?
The residents within the North Spokane Stormwater Service Area are levied stormwater fees on their bi-yearly property tax bill. The Stormwater Utility will use current and future fees to maintain the CHBRP landscaping.
Weeds were a huge nuisance in the channel. How will the CHBRP fix this problem?
The Stormwater Utility will contract with landscape professionals to provide maintenance for the completed project after the warranty period for the project landscaper has expired. The first few years, extra weed abatement will be required until the closely-spaced plants grow in and around each other. At that point, the plantings will naturally block out the weeds. The facility will also have bark mulch to help prevent weed growth.
As the native grasses and trees grow, will visibility at the intersections / crossings along Country Homes Boulevard be impaired?
Traffic studies do show that having a barricade of some kind, particularly grasses, shrubs, and trees, may decrease visibility across the median. However, the Stormwater Utility, in cooperation with the project landscape architect, will select appropriate plant material and account for overhang in order to facilitate safe vehicular sight distances at all Country Homes Boulevard intersections / crossings.
Will there be permanent signage placed at the site?
The Stormwater Utility has decided not to build interpretive signs along the post-constructed bio-infiltration channel. There are no suitable places to put the signs that will allow passing traffic and pedestrians to safely view them.
Since there will not be signs, how will the public be made aware of the CHBRP?
Attractive banners have been placed on light standards along the project corridor, and there are project entrance monuments (5 at each end of project) that "tell the story", in essence, from precipitation to stormwater runoff to water quality treatment. The banners meet the criteria for outreach and education as required by the Washington State Department of Ecology.
Will wildlife be enticed to nest or live in the bio-infiltration swale? Country Homes Boulevard is a very busy road and, as such, would be a dangerous place for animals to be, in addition to a vehicular hazard.
Deer, small animals, birds, coyote, moose, etc., are already frequently spotted in the area, including at the Price and Wall Regional Stormwater Facility and in surrounding neighborhoods, due to the proximity to the vegetated hillside of the Five Mile bluff. The bluff provides important habitat for area wildlife. It is highly unlikely that more animals will come to the project area, let alone live or nest in it permanently, as it is a very busy, noisy corridor that is simply not conducive to nesting species.
Note: Some of the statistics quoted can be found at http://depts.washington.edu/hhwb/Thm_SafeStreets.html
View media coverage here:
If you have technical questions about the project, contact Colleen Little, P.E., at 477-7241.