Jacksonville Florida - 27 Years of Stormwater Capital Improvements Using SWMM

The City of Jacksonville began using the United States Environmental Protection Agency (EPA) StormWater Management Model (SWMM) version 3 (3.3) in the 1980s during the early stages of what would become the world-class comprehensive stormwater management program that exists today. The City is at the outlet of the St Johns River, which is the largest river in Florida and extends for more than 500 km. The Master Stormwater Management Plan (MSMP) and implementation program covers 12 tributary subbasins and over 128,000 Ha. The model network contains flat interconnected complex open-channel floodplain systems, wetlands, piped networks and tidal effects, necessitating use of a dynamic model such as SWMM. Watershed models were developed, calibrated, and applied at the city-wide scale to guide design of more than $100 M of stormwater capital improvements projects. The City was an early-adopter of floodplain protection (100 year no net loss) and flow controls for volume and timing, based largely on the demonstration of downstream impacts available with the SWMM dynamic model. Today, using EPA SWMM 5, the City of Jacksonville has expanded their stormwater program to include notable technical features in the application of SWMM, as well as notable policy features and integration of hydrology and hydraulics with other program goals as noted in these two examples: On the policy side: the City partnered with the Federal Emergency Management Administration (FEMA) in the 2006 MSMP update to concurrently develop updated survey, models, and floodplain maps. Through partnership planning, the City was able to better control the floodplain and floodway development process using SWMM, as opposed to the more commonly applied HEC-RAS. On the technical side: a custom dynamic floodway routine was developed for SWMM that more accurately quantifies the impact of floodplain development, by considering storage and conveyance changes ,important for flat looped stream networks. Also, several of the models were validated for Tropical Storm Fay, which produced 12.1 inches of rain in 36 hours over the City. Currently, the City of Jacksonville has a 340 million dollar stormwater capital improvement plan based largely on SWMM alternative analysis coupled with decision support software, and a dedicated funding mechanism to implement the plan.