In 2011, the City of Philadelphia released the Green City, Clean Waters plan, which provides a framework to reduce combined sewer overflows into the city’s streams and rivers through the use of green stormwater infrastructure (GSI). Philadelphia’s GSI manages stormwater from the public right-of-way, city property, and private properties in a decentralized fashion, so that the positive environmental, social, and economic impacts can be spread all throughout the city while it is implemented. 

This study, commissioned by the Delaware Valley Regional Planning Commission (DVRPC) analyzed a set of parking lots owned by the City of Philadelphia, but managed by the Philadelphia Parking Authority (PPA), to help PPA and the Philadelphia Water Department (PWD) identify locations where parking supply can be reduced and/or rearranged so that green surface features can be installed, maximizing green acres achieved, while minimizing impact of such retrofit on neighborhood parking capacity. 

This study developed a “Greening Capacity Score” to determine the potential for and prioritization of greening in the identified parking lots by evaluating them for three criteria: 

Pavement Condition

Parking lots in poor condition are considered better candidates for some level of green surface expression, since needed pavement repair could be taken as an opportunity to install GSI; similarly, lots in excellent, recently paved condition are less likely to warrant near term re-investment. Lots were assigned a score based on their pavement condition, ranging from 0-1, with 0 being total pavement structure failure, and 1 being a newly paved parking lot.