Green Infrastructure for Flood Resilience

Green Infrastructure for Flood Resilience

Over a decade ago, EOR developed a statewide training program to promote Green Infrastructure (GI) and Low Impact Development (LID) throughout Iowa on behalf of the Iowa Economic Development Authority. Ever since, Storm Lake has adopted the most progressive stormwater and erosion and sediment control ordinances in the State of Iowa to proactively addressed flooding and their stormwater-based nutrient-loading issues. 

Working with the City of Storm Lake, to identify the costly, community flooding issues, EOR performed a comprehensive survey and assessment of the City’s storm water infrastructure and constructed a PCSWMM model that encompassed 1700 acres (700 ha) of mixed urban and agricultural land, as well as 11 miles (18 km) of storm sewer and drain tile.

Flooding was determined to be caused by a combination of factors including insufficient inlet capacity, pipe capacity, and tailwater effects at the storm sewer outfall. Due to these factors and the high cost of reconstructing sizeable sections of storm sewer, solutions were identified in strategic upstream areas that could retain and detain runoff before it entered the storm sewer, freeing up capacity and significantly reducing flooding events.

Solutions included road reconstruction in areas where standing water damaged pavement, as well as additional storm sewer piping and inlets for increased capacity. These practices were designed and constructed in contaminated soils, as well as around utilities that required extensive investigation due to the potential for conflicts. Further capacity was provided by regional biofiltration basins, grass waterways, and storm water wetlands in City owned parkland that was under-utilized due to flooding.