The North Washington Street Watershed project was driven by the city’s growth to the northwest and by the last “piece” of the regional stormwater facilities.

Apex prepared the stormwater master plan for the North Washington Street Watershed in the InfoSWMM modeling platform. This provided the city with a dynamic stormwater management model. The master plan included proposed storm sewer improvements and regional detention facilities for the subwatershed feeding into Hay Creek. The Regional facilities were designed using future land use and proposed stormwater management features in the watershed.

The master plan model began in 2012, with the first phase of regional facilities completed in 2014. As developments continue to grow within the watershed, Apex completed the master plan model for the upper portion (last development area). The last phase of construction was completed in the fall of 2020.

After the second phase of construction was completed, eight regional detention facilities (moving approximately 144,000 yd3 of material) and 2,300 ft of large-diameter storm sewer were installed to manage surface water in northwest Bismarck. A FEMA LOMR was recently approved for the second phase.