Large old trees give so much. They provide beauty and shade, raise property values, remove pollutants, and have even been shown to bolster mental health.
However, their sprawling roots tilt up concrete sidewalks, posing physical risks in the form of tripping hazards that can open cities to costly lawsuits.
What's an environmentally conscious and legally liable community with mature trees to do?
In Logan, Utah, they are looking beyond the age-old solution of getting out the chainsaws. Instead, they have replaced some buckling slabs of cement with paving tiles made from 100 percent recycled low density polyethylene. Called Terrewalks, the 24-inch-by-30-inch tiles are 35 pounds each and can be easily removed to trim tree roots and then set back in place.
Not only have Terrewalks saved trees in at least 200 U.S and Canadian cities, the raw materials for the synthetic squares come from some of the lowest grades of LDPE. We're talking dirty agricultural film that previously had little if any demand, as well as by-products from composite wood deck maker Trex Co. Inc. And, that solves another issue of what to do with some problematic post-consumer waste.
Terrewalks are sold by Terrecon Inc., which is based in Fountain Valley, Calif. CEO and founder Lindsay Smith got the idea for the business in 2001 after seeing red Xs painted on 26 ficus trees marked for removal in her California neighborhood. Her company started out using rubber for the flexible sidewalks but added recycled plastic in 2007.
The raw materials, such as plastic wrap used to bale hay for dairy cows, are converted into Terrewalk tiles through a process called thermo-kinetic technology, which, unlike injection and extrusion molding, does not require plastic to be clean, sorted or pelletized.
“It's a form of compression molding that allows the plastic to be coarse and diverse,” Smith said in an email. “This contributes to the concrete-like appearance of Terrewalks.”
Terrecon has partnered with three different manufacturers in the western United States to date. But starting in April, Lehman & Sons Enterprise LLC of Bristol, Ind., will exclusively handle production. Smith said a central location is needed as plastic sidewalks make inroads across North America.
“This is part of the evolution of the company and a desire to lower costs of the products,” she said. “Being in the central U.S. will reduce the cost of shipping, but most importantly, it's because there is so much ag plastic in the Midwest. Before, we were spending a lot on moving plastic.”
Root of the problem