City of Saskatoon Capacity Analysis

City of Saskatoon, Infrastructure Services, Public Works 222 3rd Avenue North Saskatoon, Saskatchewan S7K 0J5

Galen Heinrichs 306.975.7522

April 2006 – January 2007

On June 29, 2005, the City of Saskatoon reported basement backups and lift station flooding during a significant rainfall. The City retained Water Resources Modeling, LLC to develop two XPSWMM models for the Forestry Farms and Avenue M basins. These models included about 5,000 manholes and over 450 kilometers of sewers. The first task of the project was to build the models using the City’s Geographic Information System. The City’s database was directly imported into xpswmm and all of the data was reviewed for data inconsistencies. Less than 200 data inconsistencies were noted which shows how much effort the City has put into their sewer database. These areas were reviewed by City staff and the model was updated. Dry weather flows were added to the model.

After the June 29th storm, Saskatoon started a flow monitoring program and the available rainfall data and flow monitoring data were added to the model. The model was then calibrated to the wet weather flows. Then the rainfall data for the June 29th storm was then added to the models and the models were used to determine the causes of the sewer backups and lift station flooding. Site surveys by City staff identified several blockages that were included in the model by using user defined pipes. In several areas, these blockages were determined to cause basement backups and lift station flooding while in others excessive inflow and infiltration appeared to be the cause.