“The height’s not so bad,” said Bryan Thomsonowak, dangling from a harness nearly 70 feet above ground at Drexel’s biowall in the Constantine N. Papadakis Integrated Sciences Building.
Thomsonowak, along with his colleague Andrew Lee, are employees of Parker Plants, the company tasked with maintaining the biowall, the largest living biofilter in North America and the only such structure installed at an American university.
Once a month, Thomsonowak and Lee devote a full Saturday to pruning and inspecting the 80-foot-tall, 22-foot-wide biowall.
“We usually split the wall in half vertically, and it takes us each about four hours to work our way from top to bottom,” Lee said.
To reach the top of the wall, Thomsonowak or Lee is hitched to a harness and a small wooden seat at the top floor of the building. Using a pulley system, the other person slowly pulls the seat to the wall. Once situated in the center of the wall, there are two ropes attached to the pulley system that allow them to move to either direction as needed.
“We’ve been doing this for almost a year now, and I think we’re finally getting the hang of it,” Lee said with a laugh.
The towering height of the wall might prove to be daunting for most, but for Thomsonowak, an arborist, and Lee, an avid rock climber, the process of mounting the wall is routine.
“I was lucky enough to find them on Craigslist,” said Jay Satava, national service manager at Parker Plants. “This is like nothing for them.”
The monthly task of pruning wilted leaves, pulling out dying plants and treating for insects is necessary for the overall health and efficiency of the biowall—a wall consisting of as many as 20 plant species that filters and purifies the building’s air.
Aside from a day’s worth of maintenance per month, the biowall system is designed to regulate itself.
“The system that we have here at Drexel is the most advanced wall of its kind,” Satava said.
The plants are rooted between two layers of brown, “Brillo Pad-like” material, Satava said. Two 500-gallon tanks in the basement circulate water to the top of the wall, trickling down to the bottom where its cycle repeats. The tanks are equipped with a mineral-content monitoring system that allows it to regulate the water it supplies to the wall.
“The tanks are filled with city water,” Satava said. “If the salt level in the water gets too high, it will flush it and refill it with more city water. If it loses any water to evaporation, it’ll fill it as needed.”
The plants’ roots break down volatile organic compounds such as benzene, methyl-ethyl ketone, formaldehyde and toluene, which are actively blown through the biowall by the HVAC system. This reduces overall airborne pollutant concentrations by an estimated 25 percent.
“We inspect the wall regularly; we make sure it’s getting enough light and that everything’s working properly. And it does need to be pruned,” Satava said. “But for the most part, it’s making this building—the science building—better by its own design.”