Determining the Feasibility of a Sponge City Design on Montclair State University Campus

In this project I examine the sponge city concept as a Low Impact Development (LID) approach to mitigating the adverse impact of stormwater runoff. LID techniques incorporate Green Infrastructure (GI) practices, which minimize the adverse impact of contemporary urban areas. Specifically, I am examining LID on the Montclair State University (MSU) campus within the context of stormwater runoff. The Quad and the Quarry, two areas on the MSU campus, were selected for both their topographic depressions for containing runoff and for their built environment with large buildings and parking lots, an urban design feature that increase runoff. A 1/9 arc-second Digital Elevation Model (DEM) was downloaded and analyzed in ArcGIS Pro to determine surface flow characteristics at these two sites. The buildings and parking lots were extracted and digitized to evaluate the feasibility of the following GI design solutions: extensive green roofs, rain gardens, porous asphalt, and bioswales. Based on the slope of the ground surface, stormwater drains towards the Quad and Quarry. During large weather events, the stormwater runoff from the buildings and parking lots at these two locations could be directed there. The amount of runoff each study area can collect and store is 3,761 m3 for the Quad and 94,579 m3 for the Quarry. Designing a LID approach with GI can provide flood resiliency and alleviate storm damages. This sponge city concept can minimize the negative effects of flooding by reducing runoff, improving water quality, and enhancing ecosystems. The Soil Conservation Service Curve Number (SCS-CN) was used to quantify runoff. Extensive green roofs at the two sites would reduce stormwater runoff by approximately 30% compared to metal roofs. The Rational Method was used to calculate the peak discharge to prevent overwhelming and overflowing stormwater systems on campus. A Cost-Benefit Analysis (CBA) was calculated using a Life Cycle Cost Analysis (LCCA) and Benefit Analysis (BA). Published costs derived from these methods were used to determine the cost effectiveness of the GI design practices. The LCCA analyzed total project cost. Using CBA I found extensive green roofs to provide a saving of about $34 million in life cycle costs over its projected 40-to 50-year lifespan. Savings were generated through mitigation of projected environmental costs. Rain gardens over a 20-year life expectancy provided a saving of approximately $760,000. Similarly, bioswales had a saving of around $600,000 over 20-year lifespan. Porous asphalt costs exceeded saving by $2 million