Margaret T. Hance Park in downtown Phoenix, Arizona, hosted an official NFL Super Bowl Experience leading up to the big game in 2023. It marked a celebration for a community landmark undergoing a $100 million revitalization and transformation.

For Olsson, seeing Hance Park play a role in Super Bowl LVII added a little more excitement to the nation’s most-celebrated sporting event.

International landscape architecture and design firm Hargreaves Jones brought in Olsson to provide soil design and geotechnical services for Hance Park. A public-private partnership led by the Phoenix Community Alliance and the Hance Park Conservancy is working alongside the City of Phoenix to fund and guide the project.

Ted Hartsig, a senior scientist at Olsson, is designing the soils to support the park’s landscape, which tops a row of interstate highway overpasses known locally as Deck Park Tunnel. A 1.6-acre sustainable garden within the park was completed just in time to begin four days of music, food, kids’ activities, and vendors, all capped by a community Super Bowl watch party.

Hence, there was some extra foot traffic at Hance.

“Ideally, we like to let everything settle in for a month or so to get to stabilization before crowds arrive,” Ted said. “But it wasn’t a problem. After all, it’s not every day that Phoenix hosts the Super Bowl.”

Natural Park Environments

It wasn’t the first time Ted has contributed his skills to a high-profile restoration.

For example, he has designed the soils for a major revitalization at Gateway Arch National Park in St. Louis, Missouri, which also involved a bridge-like structure. He has also contributed to Waterloo Park in downtown Austin, Texas, which hosts a rotating lineup of community events and live entertainment.

“Creating natural park environments on top of structures does require an extra element in terms of landscape architecture and landscape design because you don’t have a natural soil profile to work with,” Ted said. “With this project, instead of trying to invent a soil, we’re seeking to recreate soils similar to those from the Sonoran Desert biome.”

Hance Park encompasses a 32-acre natural open space in the heart of the nation’s fifth most populous city. Named after the city’s first woman mayor, Hance Park is also home to the Japanese Friendship Garden, Irish Cultural Center, Phoenix Center for the Arts, and two libraries.

The park now showcases a sustainable desert garden  that, when fully complete, will be populated with native vegetation to support pollinators like bees, birds, and butterflies. Designed to use less water, the garden also features shaded paths and seating for visitors. The garden project is supported by a $2 million sponsorship from the Republic Services Charitable Foundation.

“Public parks and open spaces are essential to healthy communities, and this sustainable garden is an investment that will pay dividends for those visiting and living in our downtown Phoenix community,” Mayor Kate Gallego said at the garden ribbon-cutting ceremony.

Putting Soil Microbes to Work

During the process of recreating a soil endemic to the area, Ted reviewed existing literature and consulted with experts in desert biomes. Then he sought a supplier who could provide a workable topsoil to serve as the base.

Loads of base soils were tested for pH composition and nutrients like nitrogen, phosphorous, potassium, and a suite of micronutrients. The soil that passed the initial screening was augmented with compost before it was installed at the site.

“People think you need mostly sand for desert soil, but sand is heavy, drains quickly, and it doesn’t retain nutrients,” he said. “We also needed to establish the soil microbiological community. Plants won’t grow very well in soil without the right microbial mix.”

After soil was trucked in, additional tests were conducted for density, compaction, infiltration, and other factors. Olsson’s Shameem Dewan, technical leader of the Arizona Field Operations team, was essential for the quality assurance/quality control aspects of the project.

Most visitors won’t give a thought to the soil as they walk, roll, and play in Hance Park. But they’ll no doubt appreciate the beautiful native plants and trees made possible by it. For Olsson, that’s like helping the team win the big game.