When owner Prime Outlet Malls began planning the Williamsburg Prime Outlets Expansion in Williamsburg, Va., it sought a sustainable design that would meet the parking demands of a shopping facility while creating an eco-friendly solution for the space. Stormwater collection—increasingly becoming the focus of many pavement construction projects—was also an important aspect of the business plan.
Pervious concrete met the business goals of the project by providing an alterative to traditional paving materials. With pervious concrete, the construction project was able to capture stormwater runoff and return it to the soil, reducing the cost of watering the outlets’ landscaping features. Underground cisterns would store the stormwater temporarily until it was needed.
The project began by removing the existing asphalt and expanding the parking lot area. Due to impervious subgrade, cisterns collect the stormwater under the parking lot and funnel it through drain pipes for future use. A layer of open-graded stone aggregate acts as a holding reservoir between the pervious concrete and the storage structures. Once the stormwater reaches the cisterns, it is fed through a bio filter to remove hazardous materials, such as fertilizers, antifreeze, engine oil, and hydrocarbons. Once filtered, the gray water is used for irrigation around the outlet mall. Concave landscape beds helped to break up the pervious pavement and allow runoff to irrigate the surrounding vegetation.
In addition to being a solution for stormwater management, the pervious concrete contributed to reducing the heat island effect. Its lighter color helps reduce the ambient air temperature, as much as 10 degrees. Pooling water, sometimes found in parking lots, also would be eliminated. Upon completion, the project used 4624 cubic yards of pervious concrete, as well as 777 yards of conventional concrete. The 275,000-square-foot facility, now complete with a sustainable designed parking lot, optimally used the space it had to accomplish the project goals and provide an ecofriendly solution.