StatusAs of September 2017
The City is in the early stages of implementing a phased approach to reduce Ballinger Creek flooding along 25th Avenue NE between Brugger’s Bog Park and NE 195th Street. On July 31, 2017, City Council approved a Staff-recommended approach (see Update on Design of the 25th Avenue NE Flood Reduction Project Staff Report) to address flooding by “daylighting” the creek within new open channel between Brugger’s Bog Park and NE 195th Street and installing multiple large box culverts where the creek crosses driveways and roadways. This preferred approach (see Preferred Approach map) is considered the best approach to eliminate flooding, restore the creek, and provide an amenity to the community; part of this approach will seek to construct a daylighted channel and floodplain storage within a portion of the City’s North Maintenance Facility (NMF) property. The project will be phased to allow for short-term and long-term shared uses of the NMF property, pursuit of funding opportunities, and coordination to facilitate replacement of the NE 195th Street culvert, which is outside of City of Shoreline jurisdiction but causes in-City flooding.
Ongoing efforts include:
- Finalize Draft Pre-Design Report and recommended approach.
Completed efforts include:
- Field investigations - survey, critical area assessment, utility potholing, geotechnical borings, and CCTV pipe inspections.
- Preliminary hydrologic and hydraulic modeling.
- Critical Areas Report (Draft)
- Geotechnical Report (Draft Preliminary)
- Ballinger Creek flow gaging (Since December 2016)
- Coordination with stakeholders.
Based on the preferred approach approved by Council, near-term tasks include:
- Design through 60% level and permitting by the end of 2018
- Grant pursuits
- Coordination with City of Lake Forest Park and WSDOT related to project elements outside of the City of Shoreline
- Coordination with the City’s Public Works Maintenance Facility project regarding of the NMF property.
Overview and History
The project, which was recommended as a high priority in the City’s Lyon Creek Basin Plan, will reduce Ballinger Creek flooding impacts by installing improvements along the inadequate stream conveyance system located along 25th Avenue NE between Brugger’s Bog Park and NE 195th Street. Specific extent, configuration, and time frame of flood reduction improvements will be determined during pre-design and design efforts, which will accommodate input from a wide array of stakeholders including permitting and other regulatory agencies, neighbors, the general public, utilities, and other public and private entities.
Since 2001 the City has received reports of Ballinger Creek flooding on at least 16 separate occasions. Nearby public and private properties have flooded, including public rights-of-way, the City’s North Maintenance Facility site, and private properties.
The existing undersized stream conveyance system includes 550 feet of pipes along 25th Avenue NE and a 75-foot culvert crossing under NE 195th Street, which generally range in size from 24 to 36-inches in diameter. This system appears to surcharge on an approximate a 2-year recurrence interval, both as observed from past flooding events and as estimated from the Lyon Creek Basin Plan analysis. The magnitude of flooding can range from minor to severe; the most recent major flooding was December 3, 2007, during an extreme storm event.
Ballinger Creek enters the 25th Avenue NE pipe system at the southeast corner of Brugger's Bog Park and the northeast corner of the North Maintenance Facility property.
Although the NE 195th Street culvert is completely within right-of-way shared by the neighboring City of Lake Forest Park and WSDOT, the City of Shoreline may propose improvements to this culvert as a critical component necessary to reduce upstream flooding within the City of Shoreline. Coordination between Shoreline, Lake Forest Park, and WSDOT will be a major component in planning and implementing this project. In October 2016 WSDOT repaired a failed gabion retaining wall on the south side of NE 195th Street under a separate, emergency repair project.
Ongoing work is funded in part by a King County Flood Control District (KCFCD) Flood Reduction Grant as well as the KCFCD Sub-Regional Opportunity Fund.