The City of Bellevue’s Capital Improvement Program includes projects to maintain reliable sanitary sewer conveyance. As part of this program, the City must replace old, worn pumps and the associated undersized force main discharge line for the South Ridge Pump Station.
Why is this project needed?
The existing South Ridge Pump Station was constructed in the early 1990s by a developer prior to annexation of the area into the City of Bellevue. The originally selected pump style is inadequate for this location and requires frequent replacement. The City determined that the best course of action to provide cost-effective, reliable sewer service is to replace the pumps with a more robust, modern design. As a result of replacing the pumps, the associated force main discharge line needs to be upsized from an inadequate 2.8-inch diameter line to a 4-inch diameter line. Currently, the force main runs through steep, forested hillsides, and backyards. The new force main will be relocated to be fully within the public right-of-way to avoid disturbing private property, and a portion will be installed by horizontal directional drilling on SE 64th Street to minimize construction impacts.
Where is the project located?
The South Ridge Pump station is located on 108th Avenue SE. The force main replacement work will occur on 108th Avenue SE, going south from the station, then turning east and going along SE 64th Street.
Description of Construction – Force Main
The new force main will be installed along the west side of 108th Avenue SE, leaving the east side open for one lane of traffic during construction. . The pipe will also be installed by horizontal directional drilling (HDD) under the forested hillside on the western end of SE 64th Street. A drill rig will be placed at the bottom of the hill and will drill to the east. The HDD section of pipe will be fused together and staged along the north side of SE 64th Street, then pulled back through the excavation to complete the pipe installation. Temporary grading will be required at the drill area, which will be restored to existing conditions following construction. Disturbed pavement will be patched on 108th Avenue and SE 64th Street after construction, and is scheduled to be fully repaved by the City in 2026. The force main replacement is anticipated to occur before the pump station improvements and will take about two months to complete.
Description of Construction – Pump Station
To complete the pump station improvements, bypass pumping will be required. This will require the use of temporary diesel pumps. The existing pumps and some electrical equipment will removed, and then replaced with new equipment. . It is anticipated that this portion of construction will take about one to two months to complete.
Project Timeline
- 2022 - Alternatives Analysis
- 2023 to mid-2024 - Design and Permitting
- Summer 2024 - Bid
- Fall 2024 to Late 2025 - Construction
Construction may be delayed a few months if equipment is not acquired in time as anticipated.
Community Engagement
The City will engage with residents who may be impacted by this project as construction commences. We want to understand and support the needs of the community to the extent possible, and we are committed to working through construction with residents, to minimize impacts.
Potential Impacts
During construction, traffic on 108th Avenue SE and SE 64th Street will be impacted. Traffic restrictions will be in place during construction activities. Potential impacts may include temporarily blocked driveways during work days, and one-way alternating traffic. Flaggers and traffic control measures will be onsite to minimize traffic delays and create a safe work zone.
Services including garbage, mail, and emergency vehicles will not be impacted. The project team and the construction inspector will be in contact with residents during construction to communicate potential impacts. Residents are also encouraged to contact the construction inspector with any concerns about the project.
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