2011 Walnut Street, Floor 2
Philadelphia, PA 19103
JM Patterson Schoolyard
Starting in fall of 2015, A K Architecture with ThinkGreen and Durkin Associates
designed green schoolyard stormwater infrastructure improvements at the J M Patterson
School for the Trust for Public Land and two partners: The Philadelphia School District
and the Philadelphia Water Department. J M Patterson School is a K-4 public school
located at 70th and Buist Streets in southwest Philadelphia. The design and bid
documents were completed spring 2017 and the construction is scheduled to start summer
2017. The construction budget is $547,000.
The Patterson Site Improvements include a new playground (1,917 SF) and turf field
(2,174 SF) zone and a rain garden with a stone infiltration storage trench (2513 SF). A
performance area has the rain garden as the backdrop, and an outdoor classroom area is
nestled into the center of the rain garden. A concrete path and paving (1400 SF) separates
the rain garden from the permeable turf field and porous recycled rubber safety surface
playground. The site improvements are included in one continuous area of site
disturbance that also includes the two asphalt basketball half courts surrounded by a two
lane asphalt track (4,115 SF).
The area of disturbance/concrete pavement removal is 13,572 square feet. The Patterson
School stormwater management design will retain 2” of stormwater over an 20,110 SF
drainage area. The rain garden with its boulders and field stone outdoor classroom will
have a 10” stone infiltration bed with 2’-0” of planting soil above.
The rain garden is graded to allow stormwater to pond during a large rain event to a
maximum of 6” deep. At the west end of the site, the water from the impervious existing
concrete pavement starting at the Holbrook St. Sidewalk edge (elevation 44.61) and the
new asphalt basketball court pavement will surface flow towards the playground and turf
field which will capture stormwater at a 1:1 rate. All excess water from the playground
porous rubber safety surface and the turf field areas will migrate subsurface and, also,
surface flow to the rain garden infiltration bed at the east side of the site. The low edge of
the rain garden will be at the northeast corner: elevation 41.0. Any extreme storm event
that results in more than 2” of stormwater will be managed by overflow piping to the
existing sewer main in Holbrook Street on the south side of the site.