Twelve trees in the school’s east-side campus plaza provide shady, welcoming environment for students while also helping treat at-source stormwater
The central plaza at the University of California-Berkeley Haas School of Business has been an intimate student gathering space for years; however, as student needs evolved and the necessity for a more open outdoor environment became apparent, a redesign by GLS Landscape Architecture was initiated in the early 2010s. The renovation replaced the plaza’s old spatial dividers with a more open concept, perfect for commencements and fundraisers, while also retaining the area’s inviting feel with a dozen new Red Maple trees – whose large canopy, offering shady respite to students and faculty, was made possible with the DeepRoot Silva Cell system (which also ensured that plaza stormwater was cleansed before flowing into nearby Strawberry Creek).
Number of Silva Cells: 600 frames, 260 decks
Amount of Soil Volume Per Tree: 500 ft3
Number of Trees and Type: 12
Type of Project: Integrated Trees/Stormwater
Project Designer: GLS Landscape Architecture
Project Contractor: McGuire and Hester
Installation Date of Silva Cells: January-February 2013
The building cluster at the central plaza of the Haas School of Business was designed by renowned architect Charles Moore, one of his last completed projects before his death in 1993. A few eyebrows were thus raised when plans to renovate this area began in the early 2010s as a response to the evolving needs of the school and its student body, which was increasingly valuing collaborative learning methods – and in turn desired a more open-style community space to reflect this.
The intimate but compartmentalized space was re-envisioned: the stepped plaza with tree planters was replaced with an open concept more suitable to large events, like commencements and fundraisers, as well as student gatherings and free movement of pedestrians otherwise discouraged by the previous spatial divisions.
Creating an open concept, however, did not mean that the design team at GLS Architecture wanted to lose the inviting, shady atmosphere of the plaza. Plans for twelve new Red Maple trees were incorporated into the project from the beginning. It was important for GLS and Jim Horner, the UC Berkeley campus landscape architect, to identify a solution that would support plaza paving while also providing enough soil volume to ensure healthy tree growth for decades.
Likewise, the team prioritized the at-source treatment of stormwater as part of the school’s broader environmental initiatives. Ensuring the quality of runoff from the plaza was critical, as all campus stormwater flows into the adjacent Strawberry Creek.
The DeepRoot Silva Cell was the obvious choice, serving as an underground suspended-pavement system with both soil volume and stormwater treatment benefits: a way to guarantee the sustainability of the Haas plaza for years to come.
A total of 600 Silva Cell frames were installed in January and February 2013, providing 500 cubic feet of soil volume per tree. The urban forest, surrounding the perimeter of the plaza, offers a peaceful ambiance for collaborative study – consistent with the larger school objectives of providing students with community gathering areas and increasing campus green space.
The Silva Cell system also performs on-site stormwater cleansing. It was imperative that the restoration not increase stormwater runoff from the plaza; by installing Silva Cells, project planners guaranteed that water would be captured and cleansed before flowing into Strawberry Creek. To capture the water, contractors made each planter into a tributary area and paved around each of the tree beds with permeable granite planks with ¼” gaps filled with gravel. The resulting system allows all the plaza runoff to funnel directly into the soil contained in the Silva Cells (each one able to manage approximately 2 cubic feet of stormwater at a time, a total of 1,200 cubic feet of water for the entire project).
Underdrains provide a route for excess water to run off if necessary. Since all the stormwater from this part of campus flows into Strawberry Creek, the university was understandably concerned about controlling the quality of the runoff. By filtering this stormwater through the soil stored in Silva Cells, quality control is maintained on location.
The overall health and vitality of the plaza is, a decade later, flourishing thanks in no small measure to the green infrastructure benefits of the DeepRoot Silva Cells. As observed in a recent article on the project: “The apparent simplicity of the plaza conceals elaborate Silva Cell detailing below the surface of the 14,000 square foot site.” The trees are thriving, and the plaza remains a favorite of students and visitors alike.
Check out a timelapse video of the Silva Cell installation on this project here.
Also, check out GLS Architecture’s review of the project on their website.