Arizona State University Orange Mall Green Infrastructure Project
Landscape Performance Benefits
- Directs 100% of runoff from a 10-year-storm through a series of biodetention and retention areas and on to an offsite infiltration well that recharges groundwater. The site has been observed managing stormwater volumes equivalent to a 25-year storm without overtopping.
- Saves an estimated 1,000 gallons of water annually by using building-generated air conditioner condensate as supplemental irrigation.
- Improves water quality with net reduction in total phosphorus of stormwater as it passes through the bioretention basins.
- Mitigates flooding by increasing on-site stormwater management capacity, lowering the high water elevation during a 100-year storm event by 1 inch.
- Reduces mean radiant temperature by 22-24° F in areas that received added shade and by 4 °F in areas that did not receive added shade, as measured on a sunny afternoon, compared to adjacent areas with conditions similar to the site before the redesign.
- Diverted 99.9% of demolition materials from the site and buildings from the landfill through recycling, repurposing, and composting.
- Provides opportunities for socializing and relaxation for an average of 400 daily site users who spend at least 2 hours on site as observed on typical days during 3 consecutive semesters from spring 2018 to spring 2019.
- Provided educational value for 7 courses and 500 students within The Design School at Arizona State University in 2019. Students learned about the sustainable features and functions of the site.
At a Glance
Colwell Shelor Landscape Architecture
Former Land Use
400 E Orange St
Tempe, Arizona 85281
The Arizona State University (ASU) Orange Mall Green Infrastructure (GI) Project in Tempe, Arizona transformed an asphalt roadway into a performance-driven pedestrian mall and multi-use plaza for programmed events and informal social gatherings on campus. Developed concurrently with the adjacent LEED-Platinum and Net-Zero Student Pavilion, the integrated design utilizes low impact development (LID) techniques to address both urban heat and stormwater management. The SITES Gold-certified landscape employs a connected system of runnels to convey stormwater runoff originating from on-site and adjacent roadways and buildings through a series of biodetention basins with native and adapted desert plantings. Runoff then flows into a rain garden with any overflow conveyed to an existing stormwater management system south of the site. On-site stormwater monitoring stations and signage offer educational opportunities to university students, local practitioners, and visitors from the broader community. As a commitment to ASU’s overall sustainability goals, the Orange Mall GI Project serves as a regional model for the sustainable management of water resources and the careful consideration of human comfort in a hot, arid climate.
- A connected system of biodetention basins allows for the conveyance and infiltration of stormwater from surrounding campus buildings and hardscape, along with adjacent roadways. After travelling through this system, stormwater makes its way to the rain garden at the southern end of the site and the overflow is discharged through underground pipes to a large infiltration dry well under an athletic field south of the site.
- Seat walls with integrated power outlets act as weirs along the biodetention basins to slow water flow throughout the site while creating a flexible, multi-use space.
- The biodetention basins have terraced steps along the edges to encourage pedestrian access to the planted areas while natural steel bridges allow for fluid pedestrian movement across the basins, revealing the connected path of stormwater throughout the site.
- The rain garden at the south end of the site is the largest basin and last stop for stormwater managed on site. It is adjacent to a quieter area of moveable seating in direct proximity to the plants, removed from the centralized busy pedestrian corridor.
- A stalactite-inspired water feature consisting of a series of brass pipes hangs over the entry of the newly-constructed Student Pavilion building, conveying air conditioning condensate from the building into the landscape. Students and campus visitors can witness the reuse of water and perceive the cooling effect it provides as they enter the building. Scupper roof drains that direct water into the surrounding landscape are another visible stormwater management feature along the south façade of the Student Pavilion.
- The site has an exclusively native or desert-adapted, and low water-use plant palette, with species such as Fan-West ash (Fraxinus ‘’Fan-West’), Aloe vera, and deergrass (Muhlenbergia rigens), which support pollinators. Because of the site’s central location and high visibility, the plants are connected to an efficient drip irrigation system for typical dry circumstances and receive valuable supplemental water during uncommon rain events.
- A date palm grove at the center of the site shades the pedestrian mall while connecting visually to ASU’s iconic Palm Walk. These palm trees provide edible dates which are harvested and sold by volunteers with the Campus Harvest Program. Date palms were selected to provide instant shade, as compared to installing other native trees which would take many years to establish and provide shade.
- A modular suspended pavement system provides increased stormwater infiltration and allows tree roots to access greater volumes of uncompacted soil for large tree growth.
- Approximately 15,000 sf of durable, high solar reflectance index (SRI) concrete paving is laid out in easily replaceable sections, facilitating maintenance.
- Manage stormwater from the site and nearby roadways to provide additional capacity to mitigate flooding on campus during the extreme rain events.
- Create a programming-flexible pedestrian mall, event space, and social amenity for students while managing microclimate to create thermally comfortable spaces.
- Create a living educational laboratory to highlight sustainable, water-sensitive, and deserted-adapted planting design that supports ASU’s campus sustainability mission and initiatives.
- Improve the mental and physical health of students with an outdoor space that helps to improve student stress levels.
The Orange Mall GI Project provides multiple overlapping educational benefits to the students and researchers at ASU, visitors, and regional community at large. The site features informational signage that explains the ecological and hydrologic functions of the site along with prominent features. Landscape architecture faculty also use Orange Mall within a multitude of classes for a more in-depth investigation of the site.
Orange Mall is part of guided in-person campus tours and featured as part of ASU’s Tempe Campus Virtual Tour. Additional tours take place with community and municipal entities interested in replicating green infrastructure (GI) design features in the project, including the Flood Control District of Maricopa County and Paideia Academy, a charter school in Phoenix. Both parties were interested in learning more about GI design details, performance, maintenance, and monitoring efforts for application on their respective campuses.
ASU students have been involved in both the SITES certification process and post-construction performance monitoring of the site. Undergraduate students participated in site observations of site users engaging in social interaction and mental restoration activities that were used for official site user counts and to support social benefits credits for SITES. This information was then compiled by graduate students and used for final SITES submissions.
Christopher Sanchez, MS in Sustainability, reported on the development and implementation of an ecological performance monitoring protocol for the Orange Mall GI Project, as documented in his 2019 thesis entitled: Designing and Implementing Ecological Monitoring of Aridland Urban Ecological Infrastructure (UEI): A Case-Study of Design Process and Outcomes. Site performance was monitored over a 7-month study period from August 2018 to February 2019 to examine the quantity and quality of stormwater managed by the site, along with transpiration rates of vegetation, and soil moisture after storm events. Sanchez demonstrated that the site was able to meet or exceed the intended stormwater management design goals through examining the soil moisture data and water level gauges at discharge points. He also demonstrated the site’s stormwater quality improvement, measuring the removal of total phosphorus as water moved through the connected system of biodetention basins. Sanchez also demonstrated that plants within the biodetention basins contributed to the management of stormwater through recorded increased transpiration rates in plants following storm events. Sanchez’s data was used extensively throughout this investigation and has directly informed subsequent GI monitoring projects on the ASU campus as well as other GI design experiments in Phoenix metropolitan communities.
- One major lesson learned was the importance of performing additional potholing to confirm the locations and depth of existing utilities across the site prior to project construction. The existing site was a roadway through the center of campus with a major utility tunnel running directly below. It was discovered after demolition that a section of the utility tunnel was actually located closer to the surface than adjacent documented sections of the tunnel. This became an immediate challenge as underground stormwater piping between the bioswales had already been planned in this zone to connect over the tunnel into the rain garden. There was already an extremely tight construction schedule in order to complete the project before the start of the fall semester. The solution was to design channels with rectilinear piping in order to gain clearance above the utility vault to replace the original piping. The channels were fabricated into a nearby stair riser to connect at a higher elevation, and an additional bioswale was added to the north in order to connect the steel runnels at various heights. Because of the reduced clearance above the underground utilities, thinner concrete pavers were also necessary in this area for the grade to drain properly during storm events.
- Because Orange Mall is a major pedestrian spine through Arizona State University’s Tempe campus, there are certain color and design standards for pigmented concrete imposed by campus administration. Many mock-ups of concrete paving were created in an effort to find the appropriate balance of color and finish for solar reflectance, durability, and ease of replacement should underground utility repairs be required over time. Concrete paving was then designed in large rectilinear blocks with a maximum proportion of 6:9 to reduce potential for cracking, and blocks were assigned slightly different finishes. If maintenance on below-grade utilities becomes necessary, the University is able to remove sections of concrete to the nearest joint. Once repairs are complete, replacement concrete blocks will not create a noticeable alteration to the hardscape patterning.
- The collaborative communication process implemented for this project, which centered on weekly project team meetings, ultimately facilitated a more efficient construction process. The meetings typically included all team members or, when appropriate, a smaller focus group to discuss a specific design aspect or issue. Conference calls and/or video conferencing engaged sub-consultants or specialists in the meetings as required. Close communication with the contractor was crucial to the SITES process along with making the requirements for submission clear at the onset; the weekly meetings then served as check-ins to make sure necessary SITES paperwork was being completed.
- A modular suspended pavement system was used on the Orange Mall GI Project to ensure successful tree maturation to create a shaded and comfortable pedestrian space. This system has shown to be effective in reducing compaction and improving moisture retention. At the time of construction, there was no precedent for use of modular suspended pavements in this context in the state of Arizona, and it took some time to persuade both the civil engineer and the University to include them in the project. The contractor was also unfamiliar with the installation process, and although they were able to learn and install them effectively, the initial construction phase would have proceeded at a faster pace had additional training been available.
- The site performance monitoring protocol for Orange Mall was an important aspect of the project design that was co-produced by ASU researchers, professional practitioners, the ASU campus architect’s office, the contracted landscape architect, and structural and civil engineers. The decision to implement ecological monitoring emerged after site construction had begun, and thus the placement and protection of monitoring equipment on site included challenges like limited time and capacity for ongoing stakeholder and research engagement meetings and limited funding to conduct the actual monitoring. Though the immediate challenges of the project were addressed through collaboration along the design-research nexus, these important lessons have been carried to subsequent GI projects on campus. First, preliminary stormwater monitoring data from Orange Mall has directly influenced design and monitoring decisions for two similar projects on campus. Additionally, the collaboration between researchers and practitioners on these other projects was initiated much earlier in the design development process, and the associated budget plans included funding and other accommodations for research at the onset.
Concrete unit paving: Acker-Stone Industries
Moveable seating (tables and chairs): Maglin Site Furniture
Tree grates: Urban Accessories
Modular suspended pavement system: DeepRoot Silva Cells
Structural soil: CU-Structural Soil
Client: Arizona State University
Arizona State University: Byron Sampson, RLA, University Landscape Architect; Norman Yatabe, RLA, Design Manager; Pedro Chavarriaga, Project Manager
Landscape Architecture: Colwell Shelor Landscape Architecture (Allison Cowell, RLA - Prime Consultant)
Irrigation: Spectrum Irrigation Consulting Inc. (David Powell, CID)
Structural Engineering: Bakkum Noelke Structural Engineers (Gregory Bakkum, PE)
Civil Engineering: KLAND Civil Engineers (Lesley Kland, PE; Casey Haderly, PE)
Electrical Engineering: Woodward Engineering (Douglas Woodward, PE)
Contractor: J.E Dunn Construction Company (Daron Kettler, Project Manager)
SITES Consultant: Ecological Environments (Cindy Quinn, AIA)
Role of the Landscape Architect
The landscape architect served as designer and Landscape Architect of Record for the project. They were involved in all phases of the project, from early campus engagement meetings through project management, concept, design, and construction administration. They continue to be involved with the project through requests of the University and professional organizations for education and research opportunities within the project site.
Case Study Prepared By
Research Fellow: Chingwen Cheng, PhD, ASLA, PLA, LEED AP, Assistant Professor of Landscape Architecture, Arizona State University
Research Assistant: Amanda Trakas, Masters of Landscape Architecture Candidate, Arizona State University
Firm Liaison: Allison Colwell, Landscape Architect, Colwell Shelor Landscape Architecture
Cheng, Chingwen, and Amanda Trakas. “Arizona State University Orange Mall Green Infrastructure Project.” Landscape Performance Series. Landscape Architecture Foundation, 2020. https://doi.org/10.31353/cs1640