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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.
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Deborah Cahill
Capital Projects Division
Philadelphia Department of Public Property
790 City Hall
Philadelphia, PA 19107
215-683-3657
deborah.cahill@phila.gov
Thomas Spokas, PE, LEED AP
Langan Engineering and Environmental Services
30 South 17th Street, Suite 1300
Philadelphia, PA 19103
215-864-0640
tspokas@langan.com
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