In an area where rainfall may total over 40 inches per year, flooding can become a major problem. Streets in Manayuck, a suburb of Philadelphia, Pa., flood yearly and residents have learned to prepare for such events. The Philadelphia Water Department has made plans not only to try to resolve the flooding issues on Venice Island near Manayuck but to do it using green technology.
The $46 million construction project at Venice Island began in January 2012 with the demolition of the existing facilities and the excavation of land. The PWD retained Hazen and Sawyer, a water engineering firm, to design a green combined sewage overflow detention facility, but the firm has plans for the entire island that include a detention facility, headhouse, performing arts center, recreational facilities and a parking lot to hold over 170 vehicles.
The first and most crucial step was to remove the existing sanitary sewer overflow, which went straight into the Schuylkill River and sometimes caused flooding issues. PWD will, instead, be constructing a 3.5 million-gallon detention basin along the southern end of Venice Island to manage storm water. The detention tanks must be constructed underground since space is so tight. The water that reaches the basin during intense rain storms will be diverted and then recycled or dispersed into the Schuylkill River in small doses as necessary.
“The project was designed to incorporate numerous green infrastructure features that will manage stormwater and wet weather events,” Mark Bottin, Philadelphia office director at Hazen and Sawyer, explained.
Curves in the parking lot will allow rain runoff to follow the curb and drain into a series of over 30 rain gardens and tree trenches along the way. The gardens then will be interconnected via a piping system and then to the basin. Water that is not used will then flow the rest of the way into the river. Between the parking lots, extraneous water that does not travel into the rain gardens will be collected through planted berms. The facility will host over 500 trees and several thousand plants, shrubs and other plants as a means natural water collection.
The top of the buildings will also feature green design.
“The headhouse was designed as a LEED-Silver eligible facility,” Bottin said. The headhouse will be completely facilitated by a sedum roof, which will cover nearly 70 percent of the roof and rain garden. The headhouse will also features regionally-harvested stones for the backdrop.
Inside the building, an incredible glass stair tower will allow for additional light to be brought in during the day, reducing the need for lighting inside the building. To add to that, the shade and reflective devices will allow for sun control, reducing the need for air conditioning and lowering energy costs with the occupancy sensors in areas of the building.
The facility’s performing arts center will also include sedum roofing, covering around 30 percent of the roof, and a gray tank to recycle the harvested rainwater for toilet flushing purposes.
It is expected that rainwater runoff will be collected at the facility and diverted to the detention center, recreational facility and performing arts center at least six to seven times per year.