Booster Pump Station Upgrades

​​Project Status

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Project Details/Neighborhood 

• 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 

www.mercerisland.gov/WU0128