To develop the Wissahickon Creek Act 167 Plan, NTM Engineering collaborated with Temple University’s Center for Sustainable Communities on the project. The Plan’s goal was a comprehensive stormwater management plan for this urban watershed, which experienced flash flooding and water quality problems.
The Wissahickon Creek Watershed encompasses approximately 64 square miles and includes 15 municipalities. To date, NTM has provided data collection, GIS mapping, technical analysis, hydrologic modeling, bridge capacity analysis and standards, and reporting services and has collaborated with the Philadelphia Water Department (PWD) and Montgomery County Planning Commission.
NTM requested data on problem areas and basins from the watershed municipalities, reviewed and compiled the data, and forwarded it to Temple University. NTM identified flooding problem areas and included all structures that are impacted by the 100-year flood event. The problem areas include multiple residential and commercial buildings, and the flooding cause is generally due to either backwater from bridges or high volume. NTM researched FEMA profile maps and identified and mapped the significant flow obstructions and researched FEMA repetitive loss information for Philadelphia and Montgomery Counties. NTM researched previous studies related to stormwater, basin characteristics, and water quality within the watershed. GIS mapping services have included cataloguing and compiling the municipality data to import into GIS and coordinating with Temple. NTM developed mapping of impaired streams based on the 303d list.
NTM has field viewed and analyzed the Wissahickon Creek’s problem areas and flooding obstructions. The firm is developing specific solutions for the detailed problem areas. NTM also identified existing detention basins and determined approximate basin size and storage volumes. NTM performed basin rankings and identified potential sources of funding for improvements.
The initial Act 167 Plan report has been developed. NTM continues to develop and expand an implementation plan and keeps project team members updated via presentations at Wissahickon Plan Advisory Committee meetings.