Environment

Some of the tree wells in Louisville’s downtown got a makeover last week. Rather than installing the iron grates with holes that ring most downtown trees, the Louisville Downtown Partnership and Metro Public Works filled in more than 50 wells with a new porous material.

Louisville Downtown Partnership Director of Operations Ken Herndon said there are a number of benefits to using the new material, which is made of recycled tires, small gravel and rubber resin.

“The porous pave is a mixture that seals off that area and it stays flat and it’s completely porous,” he said. “It uses recycled materials, it forms a nice flat surface to walk on and it’s cheaper than the cast iron, about half as much or so.”

Unlike iron grates which can become crooked if tree roots grow close to the surface, the new tree well filler will stay flat, which is safer for pedestrians. And the material allows more water to be absorbed, feeding the tree’s roots and keeping water out of Louisville’s combined sewer system.

“When we did the installation the other day, we laid one of our water tank hoses on there at about 10 gallons a minute and just let it run for about 15 minutes, and the water just completely disappeared,” Herndon said.

LDP made the choice to invest in the new porous material after a trial run in six wells last year. Herndon said it held up well, despite the rough winter.

“It’s not for every place but it’s a good tool to have in our arsenal of options so we can do the best by the trees in the wells and get the most water to them, and also provide a safer walking experience for the pedestrian,” he said.

The current wells with iron grates likely won’t be replaced anytime soon unless there’s a problem, Herndon said. And the porous material may not work on wells with mature trees; if their roots are close to the surface, there may not be the four inches of depth needed for the porous pavers.