The New Normal: A Silva Cell Case Study in Normal, Illinois

Supporting and tripling the life expectancy of 67 trees, and helping to shape a sustainable identity for Normal’s Uptown Center: The Circle

Halfway between St. Louis and Chicago, sits Normal, Illinois, a town of about 52,000 that borders the metropolitan region of Bloomington. Illinois State University and neighboring Wesleyan University bring a youthful and collegiate vibe to the town. Over the past decade, the town has enjoyed the benefits of the Normal Uptown Renewal Project.

The Uptown Center and the surrounding green infrastructure redesign comprises a roundabout, near main streets, restaurants, pubs, and the Children’s Discovery Museum. The 5-acre project borders an abandoned railway that formerly bifurcated the historic downtown core and impeded retail traffic. The Amtrak rail connecting St. Louis and Chicago is just yards away from the project site. However, the town lacked significant public space. Normal wanted to leverage infrastructure improvements (transportation and stormwater) and add green infrastructure to the design.

The concept was to keep the existing circular plaza and beautify it with water features whose large trees and soil quantities would help manage the flow, quality, and volume of stormwater through evapotranspiration and detention. All of this was possible thanks to the hard-working project team that incorporated what was (at the time) a new green infrastructure technology, Silva Cell. The goal of project designers Hoerr Schaudt Landscape Architects and the city was a beautiful downtown with long-lived trees. The team thought it was important to qualify for a LEED-ND (Leadership in Energy and Environmental Design Neighborhood Development) certificate. They could not have foreseen that the project would go on to receive five other awards for planning and design excellence.

Below are renderings that show the roundabout design, the extensive placement of trees and green infrastructure outside of the roundabout, and the incorporation of Silva Cells in the design plan. The last photo is the Circle come to life. All designs and schematics provided by Hoerr Schaudt.

Normal Illinois Uptown Project Site Plan, including 67 trees.

 

The diagram demonstrates how water is cleaned as it moves throughout the uptown circle. Note the Structural Cells Below Permeable Paving are the Silva Cell 1st generation.

The rendering of the circle in design. The schematic highlights the flow of water.

The Circle brought to life. Photo taken 2012.

The all-star project team

The hard-working project team ameliorated the complexities of time while still achieving the design goals through grace and grit. The Landscape Architects of Hoerr Schaudt, Peter Schaudt, and Geoff Valentino, worked closely with the municipality’s urban development director, Wayne Aldrich P.E., to achieve the desired certification goals. Aldrich, Schaudt, and Valentino cultivated the necessary tools and technology to achieve a unique yet sustainable space. Aldrich managed the city’s requirements for the project and ensured the redevelopment would succeed in receiving the LEED-ND certification. Wayne did his due diligence in finding a solution to meet all project team members’ goals. He found that “the Silva Cell system was the most reasonable method to achieve the desired results of satisfying the site’s loading requirements while providing adequate soil volumes to the trees.” Schaudt, Valentino, and Aldrich made the decision to install Silva Cells to support Boulevard, East Beaufort, and West Beaufort and in a central roundabout at the intersection of the four streets.

Silva Cell installation. Photos taken April, 2009 by Al Key.

A birds-eye view of The Uptown Circle during construction in 2009. The photo is displaying Constitution Blvd., south-facing.

Constitution Blvd., south-facing. Photo courtesy of Binder, taken in 2012.

Research on long-term economic and environmental performance

In 2011, Aldrich worked with a team of researchers from the University of Michigan (Christopher D. Ellis, Byoung-Suk Kweon, Sarah Alward, and Robin L. Burke) to complete a thorough case study* for the site through a grant from the Landscape Architecture Foundation’s Landscape Performance Series. Using both exact project data and modeling techniques, the team gathered the economic and environmental impacts of the Uptown Normal site on the community. Among other benefits, they found that incorporating green infrastructure features contributes the following to Normal, Illinois.

  • Prevent an additional 1.4 million gallons of stormwater from entering the municipal storm sewer by directing runoff from sidewalks into tree wells and planter areas augmented by underground structural cells. This also recharges groundwater.
  • Improve water quality in the fountain by removing an estimated 91% of total suspended solids, 79% of total phosphorous, and 64% of total nitrogen from stormwater with each pass through the sand, UV, and bog filter system.
  • Sequester at least 10,790 pounds of carbon annually in 104 new trees.
  • Save $61,000 in tree purchase and installation costs over 50 years by more than tripling the expected lifespan of street trees from 13 to 50+ years through the use of underground structural cells.

To read the full report of the landscape performance benefits, click here.

The Normal Uptown Circle in 2013.

“The design celebrates the people. That’s what makes this successful. It’s beautiful and memorable.” – Mayor Mark Peterson, Normal, Illinois, 2011

UPTOWN NORMAL AWARDS AND ACCOLADES THROUGH THE DECADE 

  • Leadership in Environmental and Economic Design, New Construction (LEED-ND), Silver- 2009
  • President’s Award for Illinois ASLA Chapter, Urban Category, 2010
  • US UPA National Award for “Smart Growth Achievement”, 2011 For the interview between the EPA and Normal Mayor, watch here
  • S. FTA/FHA “Transportation Planning Excellence Award,” 2012
  • Urban Open Space Award Finalist, 2020: For more on the details of the Urban Open Space Award, read here

Normal, Illinois

Uptown Normal in 2017

Installation Summary:
Number of Silva Cell: 1180 2x
Amount of Soil volume per tree: 600 ft 3(17 m3)
Number of trees and type: 67 trees
Type of Project: Streetscape, Trees, Plaza, Stormwater
Project Designer: Hoerr Schaudt
Project Contractor: Stark Excavating
Installation Date of Silva Cells: April 2009
Project timeline: 2009-2010