Belle Terre Avenue Stormwater Improvements: Estimated cost: $250,000
Construction of this project is scheduled to begin mid-March 2022. Drainage issues have been identified within the limits of the proposed pavement preservation cement treated base (CTB) project taking place on Belle Terre Avenue between Evergreen Road and Adams Street. High groundwater levels and poorly infiltrating soils contribute to failure of drainage structures in the area, resulting in ponding, erosion, and road maintenance issues. An overflow conveyance system is proposed from Suncrest Drive, to direct flows east, via pipe, to the existing ditch along the south side of Belle Terre. Stormwater design is complete, and the project was sent to ad in fall 2021
Cincinnati Drive & Pinecone Court: Estimated cost: $75,000
Utility potholing and drywell testing are the next planned steps to refine and complete the final design for this location. A homeowner RFI reported road flooding at this location and drywells appear to be failing. Vactor truck maintenance of the structures has not corrected the problem. The proposed solution includes adding additional drywells, replacing existing inlets with catch basins and piping. This project is planned to be built by the district crew in spring 2022.
Little Spokane Drive Bridge Swale: Estimated cost: Bridge funding
The SWU has been asked to size a new swale for treatment and disposal of stormwater associated with a bridge replacement project over the Little Spokane River at Little Spokane Drive Bridge No. 3704. This project is bridge funded, with the swale design to be incorporated into the larger bridge replacement plan package.
Midway Road (north): Estimated cost: $200,000
Final design is on-going to be incorporated into the CRP that is to be completed in coordination of a Whitworth Water District water main project that is scheduled for late spring 2022. Ditch erosion is occurring and worsening along the north side of Midway Road, from near Columbus Drive and downhill to the east. Culverts are also filling up with sediment and asphalt along the shoulder of the road is beginning to break apart. A small works project was designed and completed in 2018 along the south side of Midway Road to address similar erosion and sediment transport problems. Ditch armoring, check dams, and upsizing culverts are being explored for this issue. Maintenance district crews worked to temporarily address the asphalt damage and install wattles before winter weather set in during the fall of 2020.
Minihdoka Trail Spring Mitigation / Outfall Elimination:
Estimated cost: $100,000 (Ph 1 $10,000, Ph 2 $90,000)
This project will address a lack of treatment for a catch basin on the north side of the intersection by piping it across the road to a new, formalized swale. Secondly, a natural spring presents itself in the middle of Minihdoka Trail a few hundred feet south of Dartford Road. With the potential of spring flow increasing and deteriorating road conditions, a project to expand an existing swale and divert the spring flows (via a ditch) to the swale is also under consideration. Piping the catch basin across the road is planned for Spring 2022 in conjunction with planned road/water main construction along Dartford Dr. Expanding the swale and diverting the spring flow Is tentatively planned for Fall 2022.
West Rainier Way Drainage Mitigation: Estimated cost: $30,000
Two drywells near 319 West Rainier Way have a history of flooding failure. Vactoring of these structures has not solved the problem and a house/garage has had occasional flooding. A small works project is planned to fix the drainage issue by adding catch basins and new drywells.
65th Avenue & Regal Road: Estimated cost: $5,000 (for single structure project) $50,000 (for expanded project)
This project would include a drywell/catch basin replacement project for the failing structure at the northeast corner of the curved intersection. This project could be expanded to address other structures along 65th if the road is repaved. Field crews were originally planned for the work but were then unavailable.
4616 Argonne Rd – Parcel 45052.0608: - Estimated Cost: $50,000 for land, $10,000 for stormwater facility
Once the purchase of the property is completed, stormwater would be diverted from Argonne Road to a new swale, and structures if needed, on the property.
Bella Vista Drive: Estimated cost: TBD
This issue was sent to us through a request for investigation made by a homeowner reporting ponding and freezing water near their mailbox and driveway that serves four residences. A spring flow was located on the hillside a couple of hundred feet west and above the driveway approach. The spring surfaces on the hillside adjacent to the roadway and flow proceeds to the curb, flowing to the low spot in front of the mailbox. The road grade is nearly flat, causing ponding and slow-moving flows that easily freeze during the winter. This creates a hazard for mail services and pedestrians. Both the SWU and maintenance district are aware and exploring solutions to the issue.
Cascade Way – Wall to Normandie Stormwater Retrofit: Estimated cost: $420,000
The goal of this project is to address existing stormwater structures along Cascade Way, including drywells, that do not meet stormwater treatment regulations. Previous plans were created with an application for an Ecology grant that was approved but the project was not completed at that time for various reasons. The new plan now being considered proposes installing catch basins and a conveyance pipe to direct stormwater flows to an existing pipe network to the west in Wall Street. Flow would then continue north along Wall to the Spokane County property of Price and Wall where formal stormwater treatment facilities would be constructed. Preliminary design and estimates are being completed for coordination with potential partnership with road funding through SRTC.
Dartford Drive Flooding & Erosion: Estimated cost: $20,000
In early 2020, a new Whitworth Water line extending from Mill to Dartford Drive was installed. In spring/summer 2020 the Mill Road stormwater project constructed a large infiltration swale in the area between Mill Road and Dartford Drive. The large wetland bordering the south side of Dartford Drive is a flooding concern, thus the SWU would like to take a proactive approach and add an overflow culvert across Dartford Drive to handle the anticipated increase in water quantity. Flooding of the road can be alleviated by installing a cross culvert that allows water to drain to the floodplain without flowing over the roadway. Exploration and coordination of any required permits was underway before delays due to Covid-19. Maintenance district crews had plans to complete this work when permitted but follow up will be required as construction is pursued.
Decant Facility Upgrades: Estimated cost: $125,000
As the stormwater maintenance vactor program has been developed, issues have arisen related to fine sediment transport through the decant facility system. This has caused issues with clogging of the inlet structures, concrete pad cleanliness, and deposition of material into the treatment swale at the site. In 2020, ecology blocks were installed to create a meandering flow path across the concrete pad to allow more fine sediments a chance to drop out of the water. A settling pond at the end of the pad has also been explored as a solution if other, less expensive, options prove ineffective.
Hastings Road & Guinevere Drive: Estimated cost: $60,000
This location has consistent flooding on the south lane of Hastings Road. The stormwater facilities at this location have been well maintained, eliminating any possible maintenance issues. There appears to be a groundwater issue reducing the capacity of the drywells on both the north and south side of the street along with swale inlet issues up Guinevere Drive. One solution may be to pipe the nearby drywells to each other, equalizing their capacity, plus increase the swale depth at the of corner Hastings Road and Guinevere Drive. The road is concrete and has a fairly high ADT which may add to the cost of any retrofit fixes. Apartments are under construction on the north side of the intersection so a solution using that area was explored. An overflow easement is being requested from the developer but cannot be included as a permit requirement, and it is unknown if they will agree. Other options to reduce the flow from Guinevere Drive will be explored. Swales in the neighborhood have been inspected and many do not function as originally designed.
Hatch Road at Bidwell Park: Estimated cost: TBD
This project would address drainage issues occurring at Bidwell Park which is a Spokane County owned facility. New improvements have recently been made at the park and a new swale, located along the east side of Hatch Road is already not functioning as designed. The goal of this project would be to remediate the swale, either on site or by creating an overflow path, and create a long-term solution to drainage issues at the site. This project could be done in conjunction with a road project.
Juanita Road – Banbury Drive – Elma Drive: Estimated cost: TBD
This project addresses flooding issues at the above locations. There is a culvert at the corner of Juanita Road and Banbury Drive that crosses under two private lots driveways, which does not drain. It has been vactored twice and has had a camera sent through it without finding the outlet or unclogging it.
Lowe Road & Greenleaf Avenue: Estimated cost: $125,000
This location has three drywells that are sitting in groundwater, reducing their storage capacity, and causing both sides of the road to flood in a normal rain event. The de-watering pumps in Eaglewood do not appear to directly mitigate this issue. One option being explored would be to add a pipe (like the one north of these structures) that would flow between two residential lots to the Eaglewood stormwater ponds allowing for treatment and compacity. A drainage easement would be required for this option. The easement, surveying and design work is planned for this year using a consultant, and construction is planned for next year.
Morris Road & Fruit Hill Road Erosion Projects: Estimated cost: $165,000
These projects are planned for coordination with the Environmental Program for design and completion.
The ditches along Morris Road, between near Simpson Road and Starr Road, have a history of erosion and washout. Previous maintenance attempts to shore up the ditches with asphalt and riprap have not been successful. A solution using swales, flow control features, and ditch reinforcement would be needed.
The second location is Fruit Hill Road along the hill below Arbor Crest Wine Cellars. Catch basins feed culverts across the road and generate large bypass flows. Due to steep grades, these flows cause erosion on the downhill side of the road. Potential mitigation measures include using pipe, riprap, and larger swale areas, to help address the erosion issues.
Nevada Street & Newport Highway Flooding Mitigation: Estimated cost: $100,000-$320,00
This project is to address flooding that occurs regularly within County right-of-way on Nevada street east of Newport Highway. Some of this flooding is caused by poor road conditions channeling stormwater past existing structures and into the intersection. Work could consist of building new stormwater treatment and disposal along Nevada Street. There is also a need to replace some of the existing stormwater structures, which could include treatment devices (such as Filterras or swales), piping, catch basins and drywells. Previous solutions proposed an infiltration facility to the north of the road, but this project had been paused due to utility conflicts. There is some potential for this project to turn into an Ecology Grant application, adding treatment to the other structures along Nevada Street. This would also need to be coordinated with pavement replacement along the roadway to fully fix drainage issues, which may happen through SRTC funding. At this time, multiple designs are being completed to accommodate improvements, with or without State grant funding.
Waikiki Road and Hemlock Street Drainage: Estimated cost: $20,000
A regularly clogging drywell grate has been causing flooding and damage to nearby properties. Work was completed by the maintenance district crew in 2020 to install a new dome-style grate to the drywell and initial indications were that the drywell was still not handling all flows. Paving and regrading were also done on the southwest corner of the intersection to better direct flows to the culvert and eliminate some exposed granular material. In early 2021, the adjacent homeowner hired a contractor to install a retaining wall running the length of his fence to the north of the drywell and depressed landscaped area. Additional work by County crews to raise the grate was completed in fall 2021 and the effects of this change will be observed through the winter. Additional improvements are being considered including adding a baffle wall or rock the culvert outlet, grading to create a larger swale area, and additional structures set higher to capture overflow/increase infiltration capacity to prevent a breach of the new wall.
Warren Street & Bradbury Avenue: Estimated cost: TBD
Issues have been reported in early 2022 at this location. Flooding at this intersection appears to be occurring due to settlement of the asphalt near the existing catch basins, preventing water from entering the conveyance system. Settlement could be an issue throughout this development, so early investigations are underway. Flows from this stormwater system are directed to a pond on the southwest corner of Warren Street and Jay Avenue that is managed by the SWU through a drain water account.
Woodland Estates Erosion: Estimated cost: TBD
This project is located at the Spokane County-owned, Woodland Estates stormwater facility at the northeast end of Columbia Drive near Argonne Road. Erosion is occurring on the north hillside where the existing capacity was not able to handle incoming flows. This project will address the existing erosion and add capacity or bolster overflow structures to prevent further erosion. This may be accomplished by upsizing the pipe and/or creating a reinforced overflow channel down the hillside. Clean-up of the material deposited at the bottom of the pond, near existing drainage structures, will also be performed. Maintenance activities may be performed in the short-term as an alternate means to address some problem areas. Geotechnical consulting is recommended to ensure project success; the erosion is occurring on the nearly 30%, sandy, granular slope.
Yale Road near Colbert Road Drainage Mitigation: - Estimated Cost: TBD
Failing structures have been identified on Yale Road just north of Colbert Road after a request for investigation and subsequent vactor cleaning. The site contains a drywell, two catch basins, and a pipe that was found to be clogged and the location of the outflow not able to be located. Groundwater was seen backflowing into the drywell during cleaning, indicating the need for an alternative solution. The adjacent parcel appears to be nearly all impervious surfaces and lacks on-site stormwater management which is significantly contributing to the flooding issue.
63rd and Martin – Drainage Mitigation:
This project consisted of installing new drainage structures; including catch basins, piping and drywells; in a neighborhood area that regularly saw roadway flooding during runoff events. The new structures were installed along 63rd Avenue, near the intersections of Helena Street, Martin Street, and Crestline Street. The goal of this project was to decrease the frequency and extent of roadway flooding and add sediment storage capacity to increase the required maintenance interval of these drainage structures. Construction of this project was completed by NNAC Inc. under the supervision of Spokane County Stormwater Utility in November 2018.
Argonne Lane: Cost: $40,159
Constructed by district crew in fall 2020. This project is where Argonne Lane intersects Argonne Road. A new culvert was installed to replace the failing culvert and drain that was unstable and a safety hazard. A structure was added to connect a second, existing pipe to the new culvert, located between Argonne Lane and the fire lane to the north. Ditch shoring, grading and new asphalt completed the project. This project was bid but put on hold prior to award.
Argonne Rd & Maringo Dr to Upriver Dr:
Spokane County Stormwater Utility's Argonne Road Stormwater Retrofit Project took place in the spring of 2015. The project involved installing treatment structures, in the form of sand filters, ahead of existing drywells in a portion of Argonne Road where untreated stormwater was being intercepted and directly injected into the sandy subsoils below the drywells in a highly susceptible aquifer protection zone. The new treatment takes stormwater runoff from the roadway, sidewalks and hydraulically connected driveways. 15 drywells were retrofitted with 16 new sand filters, intercepting approximately 4 acres of pollutant generating impervious surface (PGIS) to provide pretreatment of stormwater.
Cincinnati Drive & Woodglen Court: Estimated cost: $10,000
This project was completed by maintenance district crews in fall 2021. A homeowner RFI reported that road runoff was coming down their driveway and entering the garage. Flow coming down the hill along Cincinnati Drive was bypassing the structure near the northeast corner at Woodglen Court. The solution consists of adding additional WSDOT type catch basins along the east side of the road, uphill of the existing structures, to better capture flows.
Country Homes Boulevard Restoration Phase I:
The Country Homes Boulevard Restoration Project, Phase 1, was a water-quality retrofit project constructed in 2014. 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. 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.
Country Homes Blvd Phase II:
Construction for the Country Homes Boulevard Phase 2 - Wall to Division project was completed in late fall 2016. The project involved constructing a stormwater facility within existing islands of Country Homes Boulevard, incorporating both disposal and water quality treatment. The facility is a network of catch basins and pipes that collect and convey stormwater to bioinfiltration swales in the existing center islands. The swales are designed to treat and detain stormwater generated by pollution generating impervious surfaces, or PGIS, of the Country Homes Boulevard corridor. Drywells were installed in the swales for stormwater overflow, replacing existing drywells that did not have a treatment element.
Hawthorne East-Division St to Newport Hwy: Cost: $425,000
Construction was completed in the summer of 2016. This project replaced aging disposal structures with new structures and provided stormwater treatment.
Hawthorne West-Waikiki Rd to Division St: Estimated Cost: $600,000
The Hawthorne West project was a stormwater retrofit and road improvement project which proposed to provide water quality treatment in an area where none had previously existed, provide pedestrian safety features, traffic calming and road resurfacing.
Jefferson Dr. and Carolina Way: Estimated cost: $10,000
Flooding at the structures this project connected to has resulted in continued monitoring of this site.
This project was completed in fall 2021 by maintenance district crews. A spring from the Five Mile hillside at parcel 36193.0604 was flowing across the road causing a freeze/thaw condition. This is like the remediate situation at parcel 36193.0601. A new catch basin was installed and piped to the existing system to the north. A pipe was also stubbed to the property line from the new catch basin for the property owner to connect a new French drain system.
Market St-Francis Ave to Lincoln Rd: Estimated Cost: $900,000
This project was completed in the fall of 2017. The Market Street - Francis to Lincoln Stormwater Retrofit project involved removing and replacing existing stormwater structures. The pre-existing drainage system consisted of catch basins and drywells. The project replaced the catch basins with Filterra Biofiltration Units and bioretention swales that capture and remove stormwater pollutants such as trash and debris, oils and grease, sediments, nutrients, metals, and bacteria.
Mill Road- Hastings to Dartford Stormwater Improvements: Cost: $641,144
This project was originally an Ecology grant award that later became ineligible. The project took existing drywells offline and replaced the system with new piping and swales. Most of the project area is piped to a recently acquired County parcel near the north end of Mill Road. A large swale was constructed to treat and dispose of the stormwater runoff at this location.
Monroe Street – Stormwater Retrofit:
This project was completed in 2017. Stormwater improvements included catch basins and piping to convey stormwater to new bio-infiltration swales for stormwater treatment and disposal.
Northside Decant Facility: Estimated Cost: $1,500,000
The Northside Decant Facility project involved construction of a regional vactor-truck decant facility for north Spokane. The facility will protect water quality in area rivers, streams, and Spokane’s sole-source aquifer, and will serve Spokane County, the City of Spokane, and the Washington State Department of Transportation. The facility consists of a covered concrete pad, an oil/water separator, bio-infiltration swale, site utilities such as water and power, allows for future sewer connection, and has an asphalt paved road to the facility. Only vactor waste from storm sewers, and waste from street sweepers will be allowed at this facility.
Price & Wall – Spring Mitigation: Cost: $22,000
This project aimed to address nuisance flooding and potential safety hazards that had developed at the Price and Wall Regional Stormwater Facility, resulting from two increased spring flows from adjacent properties. These flows had previously been routed to the County owned property. Work consisted of rerouting the two flows, via pipe and surface grading, under walking paths to the designated wetland area within the property.
Rolland & Post Neighborhood Drainage Mitigation: Cost: $75,645
County crews completed this work in 2020. This project consisted of the addition and replacement of drainage structures in a neighborhood (Elder Addition, Elder 1st Addition plats) north of the City of Spokane. Pine needle clogging is a known problem for inlet grates in the area. When the inlets get clogged, all bypass flows reach the low point in Rolland Avenue, east of Post Street, which results in flooding at the cul-de-sac. Additional drainage problems near the intersection of Wall Street and Falcon Avenue were addressed. Work included abandonment and replacement of existing structures, connection of existing structures to new catch basins, and installation of new structures at locations to help mitigate drainage issues.
Twisted Willow ADA: Estimated cost: $15,000 (from ADA budget)
This Project was completed by Bacon Construction in Spring 2022. Residents of the Twisted Willow neighborhood reported 2 hazardous deep stormwater channels near ADA pedestrian ramps. This was solved by filling portions of the existing channels near the ramps and reforming the inlets into a smaller footprint while maintaining conveyance flows off the street.
West Plains – West Terrace Stormwater Study: Cost: $325,000 (Phases 1-5)
Due to continual high groundwater and stormwater related issues in this area, a comprehensive stormwater study was completed to identify and prioritize improvement options to better handle drainage in the West Terrace. Previous methods of addressing localized problems have proven to be ineffective and a consensus of support from property owners has been hard to achieve. Osborn Consulting was hired to develop a comprehensive plan. Draft concepts were developed and input from the public was gathered through an online comment period. A final plan including a prioritized list of Capital Improvement Projects (CIPs) has been compiled and the study completed in early fall 2021. Funding options for the list of projects are being explored, with final designs and construction to follow.