Year Established: 2012 Start Date: 2012-03-01 End Date: 2013-02-28
Total Federal Funds: $25,000 Total Non-Federal Funds: $50,870
Principal Investigators: Jason Kirby
Abstract: In 2011, faced with growing concern over an aging combined storm/sewer system and widespread pollution of the Schuylkill and Delaware urban rivers, the city of Philadelphias Mayor Michael Nutter was faced with the challenge of either raising $9 billion for infrastructure improvements or finding an alternative solution [Grundwald, 2011]. The city ultimately responded with an aggressive campaign to keep stormwater out of its sewers with the help of rain barrels /gardens, new trees/parks, permeable green roads, and vegetated green roofs; effectively minimizing runoff conveyance requirements. Due to the decreased capital investments, measureable stormwater flow reductions, improved urban aesthetics and enhanced water quality for receiving waters this approach will become increasingly attractive to the numerous urban districts faced with similar dilemmas within our nation. Vegetated roofs are generally regarded as an ecologically-friendly, sustainable stormwater BMP that influences the runoff dynamics and the appearance of urban areas in a very positive manner [Villarreal et al., 2004]. However, the limited literature available that examines green roof runoff quality has shown that it may have higher nutrient concentrations than runoff from conventional roofs, whether from fertilizer application or decomposition of the compost portion of the green roof soil [Emilsson et al., 2007; Hathaway et al., 2008; see section N]. As green roof implementation increases, it will be imperative to fully understand the dynamics of these complex systems with respect to the quantity and quality of the resultant runoff.