Trees, water features help Northwest Arkansas parking lots go green

FAYETTEVILLE — In Northwest Arkansas parking lots these days, trees are popping up in planters and water is flowing through rocks, creating areas that resemble gardens more than spaces for cars.

These are environmentally friendly parking lots. They lower the heat emanating from stretches of pavement and reduce the amount of sediment flowing to streams, which keeps pollutants out of drinking water, local and national experts say.

In Fayetteville, at least two such projects are in development, with numerous others scattered throughout the city.

In Rogers, water soaks through the gravel in the gridded parking area at Lake Atalanta. Parking at the Eighth Street market district in Bentonville features native plants and bioswales, ponds with vegetation that collect runoff, and filter debris and sediment.

The Beaver Water District’s administration center in Lowell boasts grass pavers in its parking lot to allow water to seep into the ground instead of run off into streams. The entire lot has about 100 spaces and was built nearly a decade ago, said Bill HagenBurger, district plant engineer.

The district’s porous parking lot’s use of bioswales also slows runoff, reducing erosion of ditches, HagenBurger said. After nearly a decade, the lot has had some aggregate wear in one high-traffic area that has the most water flow, but that’s about it, he said. “Overall, we haven’t done a lot of maintenance on it.”

Late last year, the Beaver Watershed Alliance, whose mission is to maintain the quality of drinking water at Beaver Lake and protect its watershed, received a $500,000 federal grant that it put toward building green parking lots. The lake provides drinking water for much of Northwest Arkansas.

“When you have a lot impervious surface — surfaces that water can’t move through — you’re altering the hydrology of our landscape,” said Becky Roark, outreach director for the alliance. “So when we put in these parking lots, the water can’t soak into the ground the way it used to. It has to run off somewhere.”

Green parking lots typically feature a permeable surface. It can be gravel or turf, or made of bricks with spaces in between them. Plants and native grasses are generally placed prominently throughout a site, with conduits to allow water to flow to a drainage basin, usually a bioswale.

The U.S. Green Building Council in 2010 awarded the Beaver Water District’s administration center a Leadership in Energy and Environmental Design gold certification for energy use, lighting, water, material use and other sustainable strategies.

Peter Nierengarten, sustainability director for Fayetteville, says the city works to incorporate low-impact development when feasible in all of its new projects.

Though there’s nothing in the city’s code to dictate development of green parking lots, the city has adopted an energy action plan that lists such lots.

The city also is working to identify the worst flooding spots and is considering assessing a fee on water bills to help address them. One option might be to encourage landowners to retrofit their lots to earn credits that would reduce the stormwater fee, city engineer Chris Brown said.

The University of Arkansas Cooperative Extension Service awarded the city a $20,000 grant to install pervious pavers in eight spaces in a campus parking lot on West Avenue to address drainage issues. Work should begin in the next few weeks, said Justin Clay, city parking manager.

A plan also is underway to build a 50-space green parking lot next year at Kessler Mountain Regional Park in south Fayetteville. At least 20 spaces will have permeable material, and the lot will feature at least one bioswale. The cost is $300,000, with the city putting in $140,000 and the federal grant to Beaver Watershed Alliance paying the rest.

The city has several other examples of green lots, including one across from City Hall that has a median cut-out with a rock swale.

Green lots cost more to build, but the maintenance associated with them usually pales in comparison with that of a traditional concrete or asphalt lot, said Jason Glei with the National Parking Association, a trade group specializing in parking industry research.

Asphalt needs regular repaving, and concrete routinely breaks apart, he said.

Green parking lot materials are getting less expensive. But whether green parking lots become the parking lot norm will depend on what makes the most sense financially, he said. “If the financial sense is there, it’ll follow.”

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