Water Projects

North Washington Street Regional Stormwater and Sanitary Sewer Improvements

Bismarck, ND

Urban Stormwater Master Planning
Services Provided
  • Hydrologic Evaluation
  • InfoSWMM Model Development
  • Stormwater Master Planning
  • Detention Pond Design
  • Culvert and Storm Sewer Design
  • Inlet Drop Structure Design
  • Open Channel Design
  • Regional Sanitary Sewer Trunk Sizing, Routing, and Design
  • Plans and Specification Prepared to City of Bismarck Standards
  • Construction Observation 

The North Washington Street watershed, which is a sub-watershed of Hay Creek, was originally master planned using HEC-1 in 2004 with an update completed in 2007.  In 2012, Apex Engineering Group was retained by the City of Bismarck to complete stormwater and sanitary sewer improvements within the area.


The first phase included developing an InfoSWMM model of the existing 1500-acre sub-watershed. By using the City of Bismarck's GIS as background data, a to-scale model of the watershed was created including the current stormwater infrastructure.

From that point, Apex created a proposed conditions model which utilized future land use and proposed stormwater management features. The proposed conditions InfoSWMM model allowed the design team to optimize the required storage and structure sizes. One of the key features of the project was modeling the timing of multiple watersheds. The project was constructed in the fall of 2014 and spring of 2015. 


The modeling phase provided the City and its constituents the benefit of a dynamic stormwater management model which included features such as structures and detention ponds. The models offered solid proof that the improvements would solve the challenges faced in the area and would allow for continued development in North Bismarck.