Permeable Pavement Improves Arizona Arboretum

Located 50 miles east of Phoenix, Boyce Thompson Arboretum welcomes 85,000 visitors annually. From the visitor center, guests walk downhill on the main trail to the interpretive center, picnic area and through various gardens, exhibits and natural areas.

The trail from the visitor center is the most public and heavily used. Its decomposed, crushed granite stone eroded in heavy rains. Holes and washouts required frequent repairs. The arboretum solved the problem by installing 2,980 sq ft of Porous Pave XL. An eco-friendly green building product made in the U.S.A., the pavement is a highly porous, durable and flexible pour-in-place permeable material made from 50% recycled rubber chips and 50% stone aggregate with a moisture-cured, liquid binder.

“First impressions are critical. They can define the visitor’s experience. From the visitor center, what you see first is a stunning vista,” said Mark Siegwarth, executive director of Boyce Thompson Arboretum. “Visitors were taking in the view while standing on an unsightly crushed stone trail with patched holes and washouts. The condition of the trail detracted from the view.”

“We do not get a lot of rain in Arizona, but when it does rain, it pours,” said Julie Redfern, co-owner of Arizona Porous Pave and regional distributor for the permeable paving product. “The crushed stone on the trail could not handle our short-duration, intense downpours. Critical parts of the main trail would quickly erode. Repeated repairs were disruptive, and all the patches made the surface uneven and unappealing.”

The arboretum needed a pavement material suitable for foot traffic and wheelchairs, but also would be slip-resistant when wet, require low maintenance, and enhance the attractive nature of the area. With up to 29% porosity, the pavement allows up to 6,300 gal of storm water per hour per sq ft to drain through its surface, leaving no puddles on the trail. ADA-compliant, it is slip resistant and resilient because of the 50% recycled rubber content. The colors are fade resistant, too, as the manufacturing process infuses the rubber chips with dyes and UV inhibitors. The arboretum selected a tan color to complement its landscape.

“One part of the trail has a 20-degree slope. Porous Pave is the only permeable paving option for steep slopes,” Redfern said. “The installation process is minimally disruptive, and the material cures in just 24 hours, so the surface is useable right away.”

“Porous Pave performs as promised. We have seen visitors walking with umbrellas in pouring rain, and there were no puddles, no erosion on the trail,” Siegwarth said. “One unexpected benefit is that the rubber imparts some give, making it comfortable to walk on. The material also catches the light. Depending on the light, there are subtle changes in its appearance, much like our natural desert landscapes.”

On the 857-sq-ft section with the 20-degree slope, 2 in. of the pavement were installed on a new base of 3- to 4-in. aggregate. On the other section of the trail, 2,126 sq ft of it was poured on the existing crushed stone after new aggregate was added in washout areas. The installation was completed in May 2016.

Source: Porous Pave