Miller Hull

Willamette River Water Treatment Plant

Wilsonville, OR
This public project transforms a secured facility into a public amenity by landscaping parklands of natural meadow and stream behind a long, punctured concrete and brick garden wall that protects the facility AIA Seattle Award Jury Comment
Client City of Wilsonville
Size 6,000 SF
Completion 2003


Located on a beautiful piece of property adjacent to the Willamette River, this project provided an elegant amenity for the adjacent residential community at the same time providing a secure and expandable water treatment plant.

The 800 foot cast-in-place concrete and stone “garden wall” running north-south, bisects the site into the secure water treatment plant on one side and a public park and ponds on the other. The wall is essentially a series of connected building elevations that express the public works functions beyond.  The garden wall maintains a top of wall datum line that is constant; the wall stays level as the site drops to the river bank.

At the south end, the raw water pump station pulls river water up to begin the process. Each wall segment denotes a particular purification process such as ozone generation, acti-flo (sedimentation), ozonation, filtration, clear water storage and finally high pressure pumps that distribute water to the community.  A galvanized cap plate on the top of the concrete walls prevents rain from staining the concrete wall, which is important in the northwest climate.

From the garden side, a path of interpretive panels and view window portals look into and explain the operating functions of the facility from the piping, pumps, filters and water of the to park users as they walk along the path which eventually culminates in a river view lookout. A public meeting room attaches to this wall and sits in a pond. Two park shelters containing 30-student long picnic tables also attach to the wall. Future growth is expressed along the wall while providing plant security immediately.  Stone walls act as gaskets between the process buildings.

The public park/landscape includes a water feature that consists of a series of ponds that continue through the length of the site.  Stormwater from the park side will empty into the different ponds.  These ponds will enhance the local wildlife corridor along the western edge by providing natural eddies and emergent plants.  The plants in the landscape are indigenous to the area and the surface treatment is mainly comprised of meadows with gravel pathways.

A water feature contains a series of ponds that filter water much like nature’s own process. These ponds broaden the local wildlife corridor along the rivers edge by providing natural eddies for emergent native plants.  Community use of the park, trails and meeting room has been intensive which is encouraging especially since the original plans foresaw no public amenities.