Herron Playground in South Philadelphia serves as an example of city collaboration and ingenuity, working in the interest of the environment and the public. The original recreation center site was mostly impervious cover, lacking vegetation as well as the capacity to manage stormwater runoff. The creators of Herron Playground wanted to create a prototype for urban sites that used multifaceted techniques in dealing with stormwater management.
One of the project’s objectives was to capture 100% of the site’s first inch of stormwater and recycle it back into the landscape areas. The approach taken to reach this goal was to minimize connected impervious areas as much as possible to promote infiltration and increase evapotranspiration. To accomplish this, the existing structures and pavement were demolished and the site was restored as a public urban green space for all age groups. The renovation’s overall design focused on three key features: a rain garden, basketball court and playground. Each element was designed with respect to the others in order to maximize sustainable practices. It was also designed to reintroduce the human scale, creating an inviting and welcoming site through landscape, sporting activities, site amenities and architectural structures. New vegetated cover added to the site during this project included 70 trees, 136 shrubs, 2,500 grasses and 650 perennials.
The basketball court and rain garden function as one designed space, collecting, storing and dispersing water. The city’s Capital Projects Division of Public Property and Philadelphia Water Department worked together to complete the basketball court’s rehab. Directly below the basketball court’s porous asphalt surface is a storage tank composed of separate stone cells which capture runoff. Each cell is graded so that captured runoff flows towards the rain garden. Also, a peripheral drain connects to the cells and empties any excess water into the adjacent rain garden. Four monitoring wells have also been installed along the edge of the court, at the request of the University of Pennsylvania for future educational studies.
The 200 by 50-foot rain garden was designed as a concave retention basin. Sweeping masses of native grasses, shrubs and trees were selected based on seasonal attributes; as well as their tolerance of wet and dry conditions. Selections of flowers, leaf color and fruit were carefully considered for their ability to attract birds, bees, and butterflies. The soil composition has a high content of sand, which promotes quick drainage to the vegetative root systems. Success of this basin required proper drainage, in order to avoid standing water which would encourage mosquito proliferation. The size of the herbaceous material was also key to the retention basin’s success. For the initial planting, one quart to one gallon-size material was used, rather than smaller-sized plant plugs. To see a list of the plants installed for this project, click here.
Seventy five percent of the play and spray areas are either vegetative or porous. The remaining twenty five percent is sloped, channeling runoff and spray water into the planting beds. The safety surface of the play area is 100% recycled bonded rubber which has a natural mulch appearance. The rubber material also allows stormwater to permeate through its surface, slowing its velocity and allowing it to travel to the plant root systems.
In addition to the new vegetation, catch-basin traps were constructed in each inlet to allow oil and floatable materials to rise to the top of an inlet, thereby preventing the pollutants from entering the sewer system.
The multi-agency collaboration among city government departments addressed stormwater management, velocity reduction, ecological restoration, future educational programs, and monitoring opportunities. Langan Engineering and Environmental Services also worked closely with the Philadelphia Water Department to receive a Green Project Review, a review process provided to redevelopment projects that disconnect 95 percent or more of their directly connected impervious area.
Watershed: Delaware River
Capital Projects Division of Philadelphia Department of Public Property
Langan Engineering & Environmental Services
Philadelphia Water Department
Capital Projects Division
Philadelphia Department of Public Property
790 City Hall
Philadelphia, PA 19107
Thomas Spokas, PE, LEED AP
Langan Engineering and Environmental Services
30 South 17th Street, Suite 1300
Philadelphia, PA 19103