The City of Richfield hired Barr to develop a detailed hydrologic and hydraulic model of its stormwater system, including 116 miles of storm sewer pipes. Using PCSWMM, a stormwater management model, Barr simulated 2-, 10-, and 100-year, 24-hour rainfall events using NOAA’s Atlas 14 data. Inundation maps were created for each of the design events, showing inundation extents and potentially flood-prone structures. The model can be used to assess performance of existing stormwater infrastructure and prioritize locations for upgrades and stormwater BMP implementation. The city will also be able to evaluate the impact of flooding on development and flood-mitigation options.
Barr also used stormwater-infrastructure spatial data and other topography, hydrology, and infrastructure parameters to evaluate the likelihood of failure of high-risk pipes and culverts and possible consequences. Failure likelihood and consequences were then combined to evaluate the relative risk of each storm sewer infrastructure component. Over 8,300 storm sewer pipe segments were analyzed. Although this qualitative analysis does not identify absolute risk or predict future failure, it allows the city to focus repair and replacement efforts on pipes most in need of attention or where the consequences of potential failure are greatest.