Located 50 miles east of Phoenix, Boyce Thompson Arboretum welcomes 85,000 visitors annually. From the Visitor Center, they walk downhill on the main trail to the Interpretive Center, picnic area, and on to the various gardens, exhibits and natural areas. The trail down from the Visitor Center is the most public and heavily used. Its decomposed granite crushed stone eroded in heavy rains. Holes and washouts required frequent repairs. The Arboretum solved the problem by installing 2,980 square feet of Porous Pave XL. An eco-friendly green building product made in the U.S.A., Porous Pave XL is a highly porous, durable and flexible pour-in-place permeable paving material made from 50 percent recycled rubber chips and 50 percent 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, 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, AZ Porous Pave, 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 that is strong and durable, safe and suitable for foot traffic and wheelchairs, slip-resistant when wet, low maintenance, and attractive. The answer was Porous Pave. With up to 29 percent porosity, Porous Pave allows up to 6,300 gallons of stormwater per hour per square foot to drain through its surface, leaving no puddles on the trail. ADA-compliant, it is slip resistant and resilient because of the 50 percent recycled rubber content. Porous Pave colors are fade resistant. The manufacturing process infuses the rubber chips with dyes and UV inhibitors. The Arboretum selected the 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,” said Redfern. “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,” said Siegwarth. “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-square-foot section with the 20-degree slope, two inches of Porous Pave were installed on a new base of 3-4-inch aggregate. On the other section of the trail, 2,126 square feet of Porous Pave were poured on the existing crushed stone after new aggregate was added in washout areas. The installation was completed in May 2016.