Rebuilt Seattle Pump Station Is A Work Of Art

By Thomas Renner

Figuratively and literally, Seattle Public Utilities transformed a pump station that served a city neighborhood for more than 60 years.

Workers completed construction of the Alki Pump Station project in November 2023, converting the airlift-style pump station to a more standard pump station. The conversion will reduce the risk of failure, improve system reliability and performance, and reduce maintenance costs.

Another major component to the project was the installation of artwork at the station. The Seattle Office of Arts & Culture (ARTS) worked with SPU and artist Sarah Thompson Moore to create Tracing Alki, a public artwork. Inspired by a topographic map of West Seattle printed in 1894, Tracing Alki incorporates the natural history of the area before European settlement. The artwork was created to interact with the natural environment.

“Often wastewater utility projects are an out-of-sight, out-of-mind thing for the general public,’’ said Avery Reger, PE, of SPU. “This project seized an opportunity to turn an otherwise unremarkable space into one that the public can truly appreciate, and it invites the public to better understand our wastewater system and our connection with the surrounding water bodies.”

Aging System

Two factors played into SPU’s plan to rebuild the pump station. The former station, built in 1959, was an airlift style facility that had reached the end of its useful life.

The community, however, had also transformed. When the station was built, it served a small basin of mostly single-family homes along Alki Beach in West Seattle. Now, there are many more multi-family residential buildings, resulting in increased wastewater flows.

Seattle, Washington’s largest city, saw its population grow by more than 21% between 2010 and 2020. West Seattle, which is where the Alki community is located, accounts for 20% of the city’s population. 

SPU considered several alternatives before deciding to eliminate the airlift system. In that system, also referred to as a pneumatic ejector, air compressors pressurize a sewage holding tank to force the wastewater up and out the force main. Over time, however, the air compressors and holding tanks deteriorated, demanding frequent maintenance. Replacement parts and equipment became increasingly hard to acquire.

“With improvements of modern pump technology, centrifugal pumps have become the norm for wastewater,’’ Reger said. “Increased electrical and hydraulic efficiency and ease of maintenance are just some of the benefits of electrically driven centrifugal pumps.”

Scope And Timeline

The retrofit of the station included removal of the existing airlift system, installation of centrifugal pumps and mechanical piping; dividing the existing structure into a separated wet well and dry wall configuration; replacing the 8-inch diameter force main with a 6-inch diameter force main; upgrading electrical and structural components and installing underground ventilation ducting, ducting and irrigation pipe.

Construction began in 2022, but supply chain issues delayed the project’s completion.

“Delivery delays of motors, pumps, valves and electrical components were longer than anticipated and pushed the commission of the station beyond the originally planned completion date,’’ Reger said. “Additionally, unexpected work to structurally improve a portion of the seawall was needed.”

One of the major challenges contractors faced was installation of the tile artwork. Thompson Moore proposed artwork to create “an engaging and thoughtful space in which visitors can participate in the richly layered story of this well-loved site.”

Complex Art Installation             

Thompson Moore developed the artwork by loosely gluing the intricate design of thousands of tiles on a fabric scrim at her artist’s studio.

The project covers 1,200 square feet, and the area was divided into manageably sized panels while concrete was poured and tooled. Thompson Moore worked with the contractor on precise placement of the tiles.

“After allowing the concrete to cure for a couple of hours, the scrim backing was removed leaving just the tiles in the pavement’’ Reger said. “The intricate dance that was required for this process to be executed was complex but managed exceptionally well by all involved.”

Some of the tiles were placed on two floor doors manufactured by BILCO, the manufacturer of specialty access products. The doors are equipped with AASHTO H-20 wheel-loading, which allows for truck axle loading of 32,000 pounds. One door was a 5-foot x 5-foot double leaf door, and the other was a single leaf door that measured 3-feet, 3-inches by 3-feet, 9-inches. The doors are also equipped with a pan-type cover that can accept a variety of flooring materials. The cover is designed with a 1-inch fillable pan for field installation of architectural flooring material. The doors allow access to equipment for repair and replacement of parts.

In most instances, the BILCO terrazzo doors are used for interior applications. It’s also uncommon for doors with the pan design to be included on H-20 doors. Harbor Pacific Contractors procured the doors for the project from Anderson Specialties, BILCO’s manufacturers representative in Seattle.

“BILCO hatches were submitted by contractor and met the design requirements,’’ Reger said. “There were limited manufacturers that could produce a hatch with an inlay pan for the concrete and tile artwork that was to be installed. Being able to extend the artwork on to the hatches was important for the artist’s vision and hides them in plain sight without affecting the accessibility of the station.”

Community Support

SPU held an outreach event in December 2023 and welcomed the community to visit the site. The project team, including Thompson Moore, invited residents to ask questions and celebrate the opening of the new public asset.

“The feedback from the community was very positive,’’ Reger said. “Many people praised the thought-provoking, highly detailed artwork and had an appreciation for the dedication and effort of everyone involved to deliver a unique and enjoyable space.”

Thomas Renner writes on a range of trade industry topics for publications throughout the United States.