The City of Bellevue declared an emergency earlier this year to address public safety and environmental hazards caused by a failed culvert where Lakemont Boulevard crosses Coal Creek.
As part of the emergency, the City has commenced an emergency project where a bridge will be built to secure the stability of Lakemont Boulevard at the location of the culvert. The culvert conveying Coal Creek under Lakemont Boulevard and the roadway embankment surrounding it can no longer ensure adequate flood protection or road stability due to erosion and aging infrastructure; therefore, the road is at risk of collapsing or flooding.
Why is this project needed?
The corrugated metal pipe carrying Coal Creek is deteriorating. Additionally, storm events have exacerbated embankment settlement around the culvert, creating a road safety hazard from pavement deformation. A new bridge spanning the creek will provide greater structural stability to the roadway by placing its foundation outside of the influence of the culvert. A future phase of this project will restore the natural channel and improve fish passage and habitat in Coal Creek through the proposed bridge per guidance and requirements from Washington State Department of Fish and Wildlife (DFW).
The project is implemented in two phases to address the emergency declaration quickly and efficiently.
Phase 1: Lakemont Boulevard will be replaced with a bridge over Coal Creek as an emergency project. The north side of the road will have a pedestrian sidewalk. The south side of the road will have a mix-use sidewalk for pedestrians and bicycles. Secant piles are overlapping structural concrete columns, to create a continuous wall. The secant pile walls will provide the foundation for the bridge and also act as a retaining wall for the hillside next to Coal Creek. An emergency overflow channel will be excavated under the bridge and lined with rock to protect against erosion.
Phase 2: After Phase 1 is complete, planning will begin for channel restoration under the bridge following a typical project timeline.
- Design and permitting are expected to be completed by Sept. 2023.
- Construction duration is expected Oct. 2023 – June 2024.
- Full road closure expected to start Oct. 24, 2023 - June 2024
Why will the road be closed for eight months?
To adequately ensure the safety of Lakemont Blvd at Coal Creek, the City is constructing a new permanent bridge, not a temporary bridge or repair. It will take eight months because:
- Over 60 piles need to be installed to depths ranging from 20 to 33 feet with many being in the footprint of the coal mine and mine seams.
- The City is excavating and removing over 40 feet of roadway embankment.
- Concrete in the piles, abutment walls, and bridge deck will require time to harden and cure.
- The construction area is relatively compact due to site constraints which means the bridge components can only be constructed sequentially with minimal opportunity for coincident construction.
- Because of the region's wet weather patterns during the fall and winter, the City does plan additional time for construction.
*Note: Schedule is preliminary and subject to change
Traffic: During construction, traffic on Lakemont Boulevard SE and Newcastle Golf Club Road will be closed entirely while major construction activities are occurring. This traffic restriction will be in place 24 hours a day throughout the construction period. Flaggers will be onsite to minimize traffic delays.
Detour: Lakemont Boulevard SE / Newcastle Golf Club Road will be closed between Forest Drive SE to 155th Avenue SE. A detour will be directed along Forest Drive SE to Coal Creek Parkway SE, connecting to Newcastle Golf Club Road via Newcastle Way.
Trail Access: There may be delays entering and exiting the Red Town Trailhead during peak construction activity. Access may also be restricted for short periods to allow for the safe delivery of equipment and material. Access to the Coal Creek Trail from Lakemont Boulevard may also be limited during construction.
Services: Garbage, mail, and emergency vehicles will have access right up to the construction site on both sides and then can follow the detour.
Construction: Construction work will occur Monday through Saturday, 7:30 a.m. to 4:00 p.m. Equipment and materials will be stored in designated areas.
Puget Sound Energy: Prior to the start of construction, Puget Sound Energy will be relocating their facilities out of the project site which may cause traffic delays.
The project team and the construction inspector will contact residents during construction to communicate potential impacts. Residents are also encouraged to contact the construction inspector with any concerns about the project.
The project team has prepared the following presentation to provide a detailed overview of the project, the two-phase solution, and the impact to the community. Also, a PDF of the presentation is available.
For additional questions and comments about this project, please contact: