For the Germantown Flood Relief Capital Improvement Project, NTM assisted in the data collection and reviewed data of previous studies including the AIM1 Report. NTM provided insights on integration of the existing system and alternatives with the upstream/adjacent watershed, utilizing knowledge from experience and modeling with the Act 167 stormwater management plan.
NTM Engineering evaluated the existing EPS Stormwater Management Model (SWMM) for input data accuracy, including a comparison against Geographic Information System (GIS) data sets. NTM’s evaluation included a detailed check of the conduit attributes, analysis of storage curves, surcharge, and summary of trunkline constrictions throughout the model. NTM also created a summary of parameters within SWMM and the GIS data sets.
NTM utilized findings from an analysis of the existing SWMM and GIS data to develop recommendations for enhancing the 1D SWMM model for use in developing a 2D model of the Germantown watershed. NTM evaluated the outfall gate boundary condition for three (3) steady-state scenarios in the existing Germantown SWMM model using past experience with the Tookany/Tacony-Frankford SWMM watershed. NTM analyzed basement storage utilization during flood events, evaluated inter basin transfer and weir performance, and consolidated flood complaint data and incorporated all data into the GIS. NTM also ran 18 SWMM model scenarios to evaluate the best alternatives for flood control.