Stormwater Management Academy is conducting pioneering research—Bold & Gold™ Now Deployed on more than 50,000-sq ft of Green Roofs throughout Florida

It’s hard to miss the lush, green tropical lemongrass that adorns the roof of the Starbucks at Downtown Disney. What you might not see at first glance, however, is the innovative soil media that keeps the lemongrass firmly rooted and thriving on this “green roof.” Developed by the University of Central Florida’s Stormwater Management Academy, the patented Bold & Gold™ soil media provides significant filtration and reduction of stormwater runoff and is now deployed on more than 50,000-square feet of green roofs throughout Florida.

Composed of expanded clay matter between the size of a coarse grain of sand and a popcorn kernel, Bold & Gold™ is an innovative soil media developed by UCF’s Stormwater Management Academy team.

Composed of expanded clay matter between the size of a coarse grain of sand and a popcorn kernel, Bold & Gold™ is an innovative soil media developed by UCF’s Stormwater Management Academy team.

This past May, the Stormwater Management Academy was part of a team including Starbucks, MetroVerde and several other roofing and construction firms that completed the 1,800-square foot green roof project. Planted with lemongrass, the green roof features a hurricane-strength system, cradle-to-cradle sustainability and micro-drip irrigation. Adding to the eco-friendly benefits, coffee grounds are saved from the store and are recycled to feed the green roof plants.

For its part, the Bold & Gold soil media sits on top of the roof’s waterproof membrane—typically already in place as part of the roof infrastructure—and provides a 2- to 6-inch deep filtration layer. Bold & Gold provides exceptional extraction of pollutants, reduces the overall amount of runoff, and serves as a fertile material for lemongrass and other plants to flourish.

“At the core of Bold & Gold is an expanded clay material we’ve developed that provides excellent extraction capabilities for nitrogen and phosphorus pollutants,” explained Marty Wanielista, Ph.D., P.E., professor emeritus with UCF’s Stormwater Management Academy. “In addition, over the course of a year, this light weight and durable soil media can reduce the overall amount of the stormwater runoff by approximately 75 percent when used with a cistern to recycle the water to the roof.”


The Stormwater Management Academy team prepares Bold & Gold™ for an upcoming deployment. The patented soil media is deployed on more than 50,000-sq ft of green roofs throughout Florida.

Dr. Wanielista and other UCF professors, graduate students and undergrads are conducting pioneering work in stormwater research and have developed several pollutant-control and plant-growth variations of Bold & Gold. The soil media is deployed on green roof-related projects throughout Florida, including Starbucks, the Student Union and Physical Science Building on the UCF campus. It also is used on green roofs at other universities around the state and on a number of commercial and government building roofs, including the Honda sales facility in Clermont and an Escambia County government building. Tecta America, a leading roofing company in America, works closely with the Academy in building green roofs and was the lead on the Honda facility.  The StormWater team also works closely with green roof specialist MetroVerde and various roofing and construction firms on green roof projects.

“In addition to the extraction of pollutants and reduction in the stormwater runoff, a benefit of a green roof is that it increases the life of the overall roof structure up to three times longer than a traditional roof,” said Mike Hardin, MSEnv.E., P.E., research associate and manager of UCF’s stormwater lab. “A green roof not only provides a physical layer of protection but it keeps the roof at a more consistent temperature. Less variation in temperature means less stress for the roof membrane and erosion of materials.”

In addition to stormwater management, pollutant extraction and roof durability, other benefits of a green roof include effective water diversion, aesthetic enhancement, improved energy efficiency for the underlying structure, and moderation of urban heat island effects. Green Roofs for Healthy Cities, the green roof and wall industry association, recently reported a 10 percent growth rate in green roofs for North America in 2013.

Composed of expanded clay matter between the size of a coarse grain of sand and a popcorn kernel, Bold & Gold is also used for septic drain fields and stormwater infiltration.

Work on the soil media began a decade ago. Initial research funding related to the Academy’s green roof efforts was through the Florida Department of Environmental Protection. Today, the Stormwater Management Academy, which is part of UCF’s Department of Civil, Environmental and Construction Engineering, is working on a number of programs with industry- and government-funded research related to stormwater management including green roof technology.