Holey Asphalt: New Lamont Parking Lot will Help Reduce Runoff
It isn't often that a new parking lot receives positive reviews from the environmental community. In keeping with Lamont Doherty Earth Observatory's history of environmental stewardship along the Hudson River, however, the new lot currently under construction on campus is no ordinary blacktop.
Intended as a replacement for the existing lot that will soon become the site for the new geochemistry building, the 85-space, 24,000 square-foot parking lot will incorporate porous pavement on top of a groundwater infiltration bed. When completed, the lot is expected to reduce or eliminate storm runoff from the site. It was designed by Cahill Associates, an environmental consulting firm in Philadelphia with more than 20 years of experience designing and installing porous surfaces around the country.
"It is going to capture virtually every drop of rainfall that will hit it," said Daniel Weibel, an engineer from Cahill in charge of the project. "That's what it was designed to do. Right up to the 100-year storm, this system has the capacity to infiltrate that water."
Rain washing off of a conventional, impervious asphalt surface can carry oil, grit and other unwanted materials into local sewers or surrounding water bodies. For that reason, the New York State Department of Environmental Conservation (DEC) requires that conventional parking lot designs include an approved storm water management practice such as a detention pond or wetland to capture runoff.
A porous surface, however, permits rain to pass through the pavement to a gravel storage bed beneath. Over time, this water will gradually percolate into the ground, where many of the impurities will be filtered out or captured by sub-surface geology and soils. When completed, the new parking lot will be able to capture and temporarily store approximately 97,000 gallons of water at one time, eliminating the need for additional remediation measures.
The only drawback to the technology is that it requires slightly more attention than a traditional paved surface. In order to prevent it from becoming clogged, the pavement will have to be vacuumed twice a year. For the same reason, sand cannot be used to improve traction in winter, and spills of oil or gasoline need to be avoided.
On the plus side, ice will not easily form since no puddles of standing water can form. Moreover, the durability of porous pavement is often better than traditional paving materials. According to Weibel, the porous surface is expected to last 25 years, whereas standard asphalt usually needs to be resurfaced every eight to ten years.
Although the technique has been around for more than 30 years, the idea is relatively new to the New York City area. So new, in fact, that Lamont-Doherty had to receive special permission from the DEC to install a porous surface as the sole method of controlling runoff from the site. State and local officials plan to monitor the parking lot after it is completed with an eye to possibly adopting the method more widely in the future.
"We are very eager to see how well this technology performs in reducing runoff," said Michael Purdy, Director of the Lamont-Doherty Earth Observatory. "Everyone here takes their work protecting and researching the environment very seriously whether it's on the other side of the world or in our own back yard."
Funding for the parking lot was made possible in part by a donation from Gary Comer and the Comer Science and Education Foundation to construct the Observatory's new geochemistry research laboratory. Groundbreaking for the lab will take place on September 27. The new lot is expected to be completed in October.