Abstract Submission: Stormwater management is an integral aspect of design and planning, yet it can be challenging to design and construct infrastructure that achieves all the goals of runoff management practices. A persistent challenge involves lessening capture inefficacy and bypass, which significantly reduces the performance of stormwater infrastructure and green stormwater infrastructure (GSI) in particular. GSI relies on receiving runoff for infiltration, vegetation health, and effective performance. The capture inefficacy and bypass reduce runoff treatment, as water evades the intended GSI and creates a discrepancy in the designed runoff capacity. One connected GSI system, the Commons, located at Villanova University was constructed in 2019. Previously a 9-acre 100% impervious parking lot, the area was transformed into a student housing community that incorporated various continuously monitored GSI and designed to manage drainage from 14 acres. The site includes nine rain gardens, two cisterns, three underground infiltration systems, and one detention basin. Using collected data and visual observations, the sites' performance was evaluated. It was observed that many of the GSI have substantial capture inefficacy and bypass as there is a lack of volume entering each GSI within the watershed system. The GSI response to storms was analyzed, and it was found that many of the rain gardens do not pond as anticipated, if at all, for many of the larger storm events where ponding and overflow are expected. Recommendations were suggested to mitigate the challenges in this system, to address and lessen bypass, and to re-direct water into the prioritized bioinfiltrating practices. These performance challenges and lack of success for the connected GSI system highlight areas of improvement in both the design and construction process and can help to inform future stormwater designs.
