#built-environments

RPWRF Landscape Design

Client: City of Spokane Wastewater Management

Design Consultant: CH2M Hill + AHBL, Inc. + Others

Personal Contributions: Conceptual Design / Schematic Design / Planting Design / Construction Details

Post-occupancy Photography: Craig Andersen, AHBL, Inc.

The Riverside Park Water Reclamation Facility (RPWRF) is the City of Spokane’s primary sewage treatment plant. Installation of new outdoor wastewater clarifiers prompted the design of a visual screen to minimize the visual impact. Rather than completely obscure this infrastructure, which is culturally significant, the adopted design utilized large sculptural screens in conjunction with locally-appropriate plantings to beautify the corridor and screen less desirable views without completely obscuring the inner workings of the facility.

Site Description

The Riverside Park Water Reclamation Facility is the community's oldest and largest water recycling facility. The facility recycles about 34 million gallons of wastewater a day and returns the cleaned water to the Spokane River. Water recycling occurs in a multi-step process requiring the water to pass through dedicated physical infrastructure. The earliest phases of this process occur within clarifiers located in the eastern outdoor portion of the facility.

The installation of upgraded clarifiers prompted significant site improvements guided by a master plan developed some two decades prior to recent construction. The master plan's designation of viewshed screening along the frontage of Aubrey L. White Parkway became the focus of landscape architectural services. The area of work, approximately 650 linear feet by 20–25 feet deep, rests on the parkway's southern edge. The site is exposed and subject to solar exposure, heat, wind, and precipitation. Its adjacency to the parkway subjects it to vehicular traffic, dust, gravel, and plowed snow. Large electrical vaults are permanent features of the site. Prior to site improvements, the site functioned as overflow parking for employees and visitors. It also hosts a large, permanant sculpture called "Evaporation Screen," designed by rhiza A+D, made of perforated galvanized steel and set in concrete footings.

The RPWRF facility is nestled between the Spokane River and Aubrey L. White Parkway, located at the toe of the north slope of the Spokane River below the Northwest Neighborhood. Riverside State Park covers the area on the south and west sides of the river.

My contributions were specifically related to the Phase I improvements (denoted in green). The design aesthetic, sculptural screens, and plant palette set the tone for future Phase II improvements.

Project Goals

Meet the intent and goals of landscape restoration, storytelling, masking, and creating a sense of place outlined the the RPWRF Aesthetic Master Plan.

Minimize the visual impact of the interior site infrastructure and wastewater clarifiers as necessary.

Design cost effective, low maintenance, and resource efficient landscapes consistent with the goals of the Aesthetic Master Plan and Schematic Design documents.

Balance the goals of the RPWRF Aesthetic Master Plan with current City development codes that were predominantly oriented towards new construction and not landscape restoration.

Develop enhanced wayfinding and arrival experiences at the visitor entry while protecting restored landscapes from foot traffic.

Provide cost effective public education and site interpretation for stormwater, wastewater reclamation, sewage treatment, and landscape restoration.

Design Program

Conceptual design and construction documents for visual mitigation and streetscape improvements along Aubrey L. White Parkway from the East Approach near the Headworks Area to the Administration Building.

An existing chain-link fence and degraded stacked rock retaining wall was removed. A new retaining wall was to be constructed with a security fence affixed to it, except near the clarifiers where the wall would be kept and the security fence built adjacent to it.

A new plaza would be created to surround an existing public artwork and fucntion as an outdoor classroom. Materials and plant selection were recommended to be sustainable and for site runoff to be minimized.

Selected images of previous site condition. This stretch of the site perimeter represents the main focus of screening efforts. Images depict existing utilities, chain link fencing, a public art piece to be retained, and groundcover of gravel shoulder and lawn.

Sketched analysis of the proposed infrastructure to be screened superimposed on composited panorama.

Design Concept

Drawing the ideas of massing, geometry, and fluidity from the above, the concept brought the allegory of water to life through impressive sculptural wave screens that rise up amongst a simulated riparian landscape of dry riverbed. The semi-transparent screens cooperate with the planting scheme to softly screen undesirable views of the facility's infrastructure without totally obscuring it. Through intrigue and excitement in the landscape, the landscape celebrates the important role that the water reclamation facility plays in preserving the vitality of the Spokane River.

This final concept drew upon previous iterations to integrate the theme of the riparian landscape with significance of the facility's infrastructure.

Line drawing of the screening concept.

Rendered conceptual elevation including superimposed infrastructure height markings.

Construction Detailing

Wave Panels

While the early concept imagined waves of bluestone emerging from the ground as both sculpture and screen, the more economical and flexible decision was made to construct these as perforated steel panels, formed to shape and powder coated in blue, with a dark accent panel. These were mounted on galvanized pipe posts and set with concrete footings.

Layout of Boulders, Rock & Hardscape

To simulate the river, a winding dry bed of river stones and boulders were set along the length of the frontage.

Landscape Plantings

Given the dry, exposed conditions of the site, as well as the likelihood of snow accumulation from plowing, the planting scheme required a tough, hardy front edge comprised of drought-resistant bunchgrasses and evergreen groundcover. A dappled shade canopy was created with multi-stemmed river birch trees. The design program's screening requirement necessitated a backdrop of medium evergreen shrubs and trees. Seasonal color contrast was provided with drifts of purple catmint and yellow solidago.

The west end of the frontage included plaza plantings distinct from the rest of the landscape, integration with the main building at the facility, and a shady understory due to the preservation of mature London plane trees.

The east end of the frontage is narrow and required the most screening.

Post-Occupancy

Photos by Craig Andersen

Roadway Screening

As time has progressed, the frontage plantings have matured and created the soft screening effect imagined by the design concept.

Dappled shade provided by the river birch canopy helps reduce solar exposure to the groundcover. (c. 2021)

Preservation of the existing pine, in combination with new plantings and the wave panels, forms a contiguous screen. (c. 2021)

Plaza

The plaza remains a visual centerpiece, however there are some issues. In particular, the imagined screen to be provided by mature ash trees failed to materialize. This may be a consequence of the site's exposure, problems with the plaza planting well details, or perhaps poor installation practices. Whatever the case, the landscape would have benefited from a secondary soft screen as backdrop to the plaza.

c. 2013

c. 2021

c. 2013

c. 2021

Administration Building Frontage

Perhaps the more enduring quality of this project is the way it established a paradigm for the rest of the campus. Following the completion of Phase I, Phase II saw the extension of the plantings across the whole of the parkway frontage.

c. 2013