In 2010, the City of Humboldt experienced severe flooding and widespread sewer backups due to extreme weather events. In response, Catterall & Wrigt developed an XPSWMM computer model to simulate the city’s entire sanitary sewer collection system and analyze its response to the storm event.

To calibrate the model, data was gathered from high water marks in sanitary manholes, locations of sewer backups, sewage pump station records, and known environmental conditions. With a reliable model in place, mitigation strategies were evaluated, including the recommendation to construct a large sanitary sewer storage tank system. Construction of the tanks began in the fall of 2012 and was completed by the spring of 2013. These tanks provide temporary storage during heavy rainfall events, allowing for controlled release back into the system once flows subside.  This system ultimately helps to prevent basement flooding during major storms.