| The use of green stormwater infrastructure (GSI) continues to grow as an important source of stormwater management in cities across the United States and the world. Designing GSI systems often includes implementing pretreatment practices to avoid clogging, reduce maintenance, and increase the life span of the infrastructure. Often, design guidelines are adopted for these pretreatment practices with unknown impact on the longevity and performance of the subsurface systems. This is due to a lack of detailed information on the local stormwater runoff characteristics, particularly particle size distribution (PSD). This study outlines a methodology by identifying site selection, sampling procedures, and measurement device selection to ultimately better understand GSI performance. By sampling two Philadelphia stormwater management practices (SMPs) during simulated runoff tests (SRTs) and natural rain events at set sampling locations throughout the stormwater flow path in the SMP, local stormwater particle size distribution is analyzed. Subsurface infiltration trenches are the preferred SMP type for this research due to their prevalence in Philadelphia, which make them a key tool for the success of Philadelphia's stormwater management plan, the Green City, Clean Waters initiative. Total suspended solids (TSS), total dissolved solids (TDS), turbidity, and conductivity analyses were also conducted for further characterization of the sediments. Initial results indicate that distribution pipe samples have higher volume concentrations with coarser PSD curves than sump samples for SRT tests, which may indicate resuspension of sump sediments and their transport into the distribution pipe. This may negatively impact the performance of the distribution pipe and SMP over time, but more analysis is needed to investigate this trend during rainfall events. Additionally, no strong relationships were found between TSS/ turbidity and TDS/ conductivity, contrary to expectations. |
