To understand how a stormwater drainage system functions, calculations and analysis must be performed.  This analysis and calculations can be performed via a large number of methodologies.  Over the last 7 years, using PCSWMM, the City of Virginia Beach has developed a SWMM model of its Primary Stormwater Management System (PSMS).

Each portion of developing the master model has challenges, and multiple lessons have been learned during the process.  Lessons learned include:

1. Data collection – you need to know what you have in the way of infrastructure;
2. Validation and Calibration – once you’ve created the model, how do you make sure it is correct;
3. Overflows – runoff knows no boundaries and you must confirm appropriate pathways are provided to handle the flows; and,
4. Use of the Model – what is the most efficient way for designers to use the models.