Booster Pump Station Upgrades
Project Status
To help keep area residents informed of our construction progress, we will post project updates to this site on a regular basis. Click here to see status updates.
Project Details/Neighborhood
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City of Mercer Island Reservoir Booster Pump Station
Background
The City’s water distribution system is comprised of two 4-million-gallon water storage tanks, two booster pump stations (BPS), 120 miles of water mains, and 85 pressure reducing valves. The reservoir BPS utilizes five Byron Jackson submersible pumps and is responsible for supplying water service and fire flow to the largest pressure zone on the island, as well as a number of smaller pressure zones along the Island’s perimeter. Three of the pumps at the reservoir BPS were installed almost 30 years ago, while the other two were installed within the last decade. Four pumps are always operating, with the fifth pump on standby. While one of the five pumps was taken out of service in 2021 for emergency repairs, City staff discovered that the motors of the pumps contain mercury seals. Staff quickly procured engineering services to design the replacement of all five pumps, as well as evaluate hydraulic conditions within the pumped zone and analyze current and future system demands. RH2 Engineering, Inc. finalized this engineering and design in December of 2023. See https://www.mercerisland.gov/publicworks/project/reservoir-pump-station-equipment-assessment-design
Description
The Booster Pump Station Upgrades project will replace the five existing primary pumps and install two new smaller-sized jockey pumps at the City’s reservoir BPS site. While the primary intent is the safe removal and proper disposal of the existing pump’s mercury seals, upgrades to pump design and station configuration will also be performed. The pump design of the primary pumps (pumps 1-5) will change from vertical turbine to vertical split case, and two new jockey pumps (pumps 6-7) of in-line vertical centrifugal design will be added to the facility. These re-configurations will result in increased reliability and pumping efficiency of the station, especially during typical low flow conditions such as those seen during winter. In addition to the mechanical upgrades, the scope of work will include a host of associated structural, electrical, and automated control upgrades.
Project Timeline
Under Construction (April 2024– March 2025)
Estimated Budget
$1.45 M to $1.75 M
Contact
Christopher Marks, City of Mercer Island Utilities Engineer, (206) 677-1027; chris.marks@mercerisland.gov
Status Updates
February 6, 2025
This week, Strider made significant progress on the booster pump system. The team began piping and mechanical work for booster pumps 6 and 7 while also locating and uncovering the existing pump station discharge piping. The uncovering process spanned two days and required saw-cutting through 10.5 inches of concrete, followed by the removal of nearly 50 cubic yards of sand from a compartment beneath the pump room floor. This compartment—sealed off since the station’s construction in 1976—will serve as the connection location for the discharge piping of pumps 6 and 7.This week, Strider made significant progress on the booster pump system. The team began piping and mechanical work for booster pumps 6 and 7 while also locating and uncovering the existing pump station discharge piping. The uncovering process spanned two days and required saw-cutting through 10.5 inches of concrete, followed by the removal of nearly 50 cubic yards of sand from a compartment beneath the pump room floor. This compartment—sealed off since the station’s construction in 1976—will serve as the connection location for the discharge piping of pumps 6 and 7.
January 31, 2025
Performance testing of Pumps 4 and 5 was successfully completed this week and both pumps were placed into service. Additionally, the City received delivery of new Pumps 6 and 7, which are smaller 25 HP jockey pumps designed to optimize efficiency during winter and low-demand periods. The installation of these new pumps will be the primary focus over the next 3–4 weeks, with testing scheduled for early March.
January 23, 2025
Also this week, with the new station generator now online and the old generator removed, Strider has begun assembling the piping and mechanical systems for new pumps 6 and 7. The project is currently 70% complete.
This week, Strider completed the installation of all mechanical components to connect the new pumps (4 and 5) to the system. Next week, PumpTech, Ashford Electric, and S&B (the systems integrator) will collaborate to prepare the pumps for startup and commissioning. Startup and commissioning is scheduled for Thursday the 30th, between 9am and 3:30pm.
January 6, 2025
Originally scheduled for the new year, Strider Construction secured a spot on the concrete plant’s waitlist just before Christmas. A cancellation allowed the pour to proceed ahead of schedule, with curing completed over the holiday break. After resuming work in the New Year, Strider removed the forms and began setting pumps 4 and 5. These pumps are on track to come online by the end of the month, marking a significant 70% completion milestone. The project remains on schedule for completion in April.
December 19, 2024
With the successful activation of new pumps 2 and 3, Strider quickly transitioned to the next phase: replacing pumps 4 and 5. In just four days, the team removed both pumps and their associated barrels from the pump gallery, demolished the old concrete pads, and set the forms for the new ones. The pouring of the new pump pads for pumps 4 and 5 is scheduled to begin after the New Year.
December 12, 2024
The City successfully completed the startup and performance testing of new Pumps 2 and 3, marking a significant milestone in the booster pump station upgrade project. The testing verified the pumps' performance and ensured compatibility with the existing system.
This coordinated effort brought City project and operations staff alongside key partners: RH2 Engineering, Brown & Caldwell, Strider Construction, PumpTech, and S&B Inc. Over six hours of rigorous testing, the team evaluated both pumps across all potential system demand scenarios. The next pumps scheduled for replacement in the sequence are Pumps 4 and 5.
December 10, 2024
On Thursday, December 12, the City of Mercer Island will conduct startup and performance testing for two new pumps at the City’s Reservoir Booster Pump Station. As part of this process, water operations staff will be flushing fire hydrants at various locations across the Island. The testing is scheduled to take place during normal working hours, from 8:00 AM to 5:00 PM.
During this time, some residents may experience temporary fluctuations in water pressure or reduced water flow.
We appreciate your understanding and patience as we work to improve the City's water infrastructure.
December 4, 2024
Photo: Connection of new pumps 2 and 3 is underway at the City’s Reservoir BPS
The new Pumps 2 and 3 have arrived, and installation of the piping and mechanical components is now underway. While the pumps themselves are identical, the dimensions between the suction and discharge headers at the station vary. As a result, custom-fitted flanges are required to ensure a proper fit. The project team is continuing to target the end of next week for the successful startup and testing of the pumps.
November 27, 2024
pads 2 and 3. 
Photo 1: Nearly 8 cubic yards of concrete is used to decommission the existing pump cans and to form new pump pads 2 and 3.
Photo 2: The concrete is expected to achieve 60% of its 5000psi compressive strength after just seven days.
This week, we completed the pour for the massive concrete pads that will support the new pumps. Nearly 8 cubic yards of concrete were used which will cure to approximately 60% strength over the extended Thanksgiving break. These pads are set to receive pumps 2 and 3, which are scheduled for delivery on Tuesday. Following delivery, it will take approximately two weeks to finalize the mechanical and electrical installations, after which the pumps will be fully operational.
November 21, 2024
The weight of the existing pumps is estimated at 3,000lbs
Photo: The existing pumps 2 and 3 along with pump 2’s pump barrel are being removed from the pump gallery. The weight of the existing pumps is estimated at 3,000lbs.
Strider Construction Co. mobilized on-site Monday and began the removal of the existing piping, pipe supports, couplings, check valves, and other mechanical components connected to primary pumps 2 and 3. By the end of this week, the demolition of the existing pumps, pump barrels, and pump pads is expected to be completed. This will allow Strider to proceed with the installation of rebar and formwork in preparation for next week’s concrete pour. We anticipate that the installation of new pumps 2 and 3 will be completed and ready for testing prior to Christmas. The project is being executed in carefully coordinated phases to ensure a minimum of three pumps remain operational at all times, meeting the required water demand flows. Work on replacing pumps 1, 4, and 5 is scheduled for completion by March next year.
August 21, 2024
Photo: The project team met at the Reservoir BPS to coordinate the pump startup and testing plan.
On August 14th City staff and RH2 Engineering met with representatives from Strider Construction and PumpTech to discuss the startup and testing plan for the new pumps. Testing will require installation of temporary pressure gauges, flow meters, and vibrational analysis equipment. Extensive planning is also required to ensure that the station remains operational throughout construction and testing. Construction start is still anticipated to occur in November of this year.
June 20, 2024
Photo: The existing pump gallery where the majority of work will take place.
Since the last update, Strider Construction Co. was quick to submit and receive approval for the pumps they propose to furnish for the project. This is an important milestone because current pump delivery timelines are six months or more. In the following months, Strider will continue submitting for work plan, material, and equipment approvals. Construction start is tentatively scheduled for November 2024.
May 9, 2024
A pre-construction meeting was held on April 25th to kick off the project. The City’s project team along with the design consultant, RH2 Engineering, and the construction contractor, Strider Construction Co., discussed key project elements such as schedule, expectations, materials availability and delivery timelines, submittals, and work plan elements. The highest priority is the approval and ordering of the seven new pumps that the project will install. Current pump manufacturer estimates indicate long lead times that may delay construction start to late 2024.
March 29, 2024
The project was advertised on January 29, 2024, and five construction bids were received and opened on February 29, 2024. The lowest responsive bid was received from Strider Construction Co. (Strider) from Bellingham, Washington. On March 19, 2024, the Mercer Island City Council awarded the project to Strider in the amount of $1,726,011.28. Strider has completed numerous water and wastewater pump station projects of similar scopes and scale for public agencies across the Pacific Northwest. The City looks forward to kicking off this project and working with the Strider team. More updates to follow.
WU0128 PROJECT LOCATION (2 MB)