The city constructed the Alder Pump Station at SE Water Avenue and SE Alder Street in 1952. This upgrade project will improve reliability and increase pumping capacity, which will help prevent sewage releases into buildings and streets and combined sewage and stormwater overflows into the Willamette River.
Site mobilization and pre-construction activities began in August 2017. Demolition of the pump station occurred November 2017 through January 2018. Foundation construction was completed in March 2018. Construction of the circular below-grade caisson structure will continue through June 2018. The project will continue through the summer of 2019.
The Alder Pump Station pumps sewage and stormwater from central eastside Portland to the Columbia Boulevard Wastewater Treatment Plant in north Portland.
The pump station service area contains 88 acres of industrial and commercial properties and city right-of-way. The combined sewer system in this area conveys both sanitary sewage and stormwater runoff in the same pipes. During very heavy rain storms, stormwater runoff can fill the system to capacity and cause a combined sewer overflow to the Willamette River. Heavy rain and an overloaded sewer system have caused 11 sewage releases in the Alder Pump Station service area since 2005.
Pump Station Improvements
Environmental Services will demolish the existing above-ground pump station and construct a temporary pumping system that will be removed once the new system is operational:
- Demolish the existing station and above-ground reinforced concrete circular building
- Retain the below-ground portion of the building as a structural shoring system for construction of a new wet well
- Replace existing pumps and equipment with two submersible pumping systems in a common wet well and make the new structure more earthquake resistant
- Replace outdated mechanical, electrical and control equipment and systems
- Upgrade heating, ventilation and air conditioning systems
- Provide a drive-through with access from both SE Water Avenue and SE Alder Street
- Install security fencing with gates at each end of the access drive-through
- Install screen walls, retaining walls and a loading dock area
- Construct an ecoroof and stormwater facility incorporated into a ramp structure
- Install a new, standby diesel-engine generator
- Upgrade the pump station’s exterior appearance
Different phases of this project may require different traffic controls as upgrades on the site and frontage improvements in the public right-of-way are completed. The general traffic control plan is as follows:
- Allow access to private driveways at all times
- Employ flaggers to direct bicyclists away from the work area but not into the flow of motor vehicle traffic and to direct pedestrians to safe crossings and open sidewalks
- Establish traffic controls so that traffic queues do not extend into the railroad track zones
- Maintain a one-way, westbound travel lane on SE Alder Street to SE Water Avenue
- Maintain two-way traffic on SE Water Avenue
- Remove on-street parking in the work zone