Denver’s City Park is an iconic symbol of the Mile High City. The oft-photographed park is home to the city’s zoo and the Denver Nature and Science Museum, as well as sports and recreational areas. In 2014, the asphalt parking lot for the Denver Pavilion inside the park was scheduled to be resurfaced. The city, with the help of StudioCPG, a landscape architecture and planning firm, had a better idea: use a porous parking lot to reduce runoff and mitigate contaminants flowing into nearby Duck Lake and the storm sewer system.
“Half of the asphalt drains that direction and is connected to the existing storm system about 40 ft away,” said Crissy Roe, project manager and senior landscape architect at StudioCPG. StudioCPG chose Gravelpave2, a porous aggregate containment system, for the entire west apron parking bays in the lot, installing 3,000 sq ft of the structure.
Gravelpave2 is a system of 100% recycled plastic cylinders connected on a grid, with a geotextile filter fabric molded to the underside. The system is anchored to a porous base course and is filled with decorative gravel. Unlike normal gravel surfaces, Gravelpave2 remains porous throughout its life. Porous pavers have the ability to filter contaminants from storm water. In this instance, the Gravelpave2 cleans runoff before it reaches Denver’s combined storm/sewer system and keeps runoff from reaching Duck Lake. The system saves the city money at the water treatment plant, keeps the lake’s aquatic life healthy, and will save on maintenance by reducing rutting, washboarding, gravel migration and resurfacing associated with traditional gravel parking lots.
The porous parking lot was installed in April 2014. One year later, the system is performing as intended. “The Gravelpave2 worked,” Roe said.