April 18, 2022

$40M King County pump station project wins sustainability award

Photo courtesy of Stantec [enlarge]

Sunset Pump Station in King County has a green roof.

King County's Sunset and Heathfield pump stations and force main upgrade, which was completed earlier this year, has been named an Envision Silver Award winner. The award, presented by the Institute for Sustainable Infrastructure, highlights projects that encourage sustainable, equitable and resilient design, construction, operations and maintenance processes and practices.

Stantec led the engineering and architecture for the $40 million project for the King County Wastewater Treatment Division. The Sunset and Heathfield pump stations send sewage from Sammamish, Issaquah and Bellevue to the WTD's South Treatment Plant in Renton. For nearly 50 years, these stations served the area reliably but were reaching their operational limits. The project upgraded the pump stations and the connected force main. The design included the installation of four new vertical extended-shaft pumps with higher capacities at each station; associated electrical upgrades; new facility roofs, including a sustainable green roof at Sunset Pump Station; new variable-refrigerant flow heating, ventilating, and air conditioning systems at both stations; and a novel oxygen injection odor and corrosion control system at Heathfield Pump Station. The upgrades allow the system to convey a peak capacity of 30 million gallons per day.

Other key project elements include the installation of a new 24-inch force main to replace an old 12-inch pipe, restoration of the Lake Sammamish shoreline below the Sunset Pump Station, habitat restoration at Heathfield Pump Station, and enhancement of wetlands.

Further achievements that contributed to the award included the use of only native vegetation and removal of invasive species; involvement of stakeholders that included surveying over 250 neighbors and community members during design; and the improvement of public health and safety by enhancing the continued reliability of the sewage treatment system and installing a new technology that will reduce pipe corrosion and extend the life of odor control.

“Assisting King County Wastewater Treatment Division provide needed upgrades to its facilities while also focusing on sustainability is very satisfying,” said Mark Graham, Stantec senior principal and project manager in Bellevue, in a press release. “Pump stations play a key role in wastewater management. To see these facilities also provide on-site stormwater management, a green roof, native plants, and more is a testament to the WTD's goal for sustainability.”