Drainage Project



Project Owner:
City of Sioux Falls, SD

Key Experience:

  • Combination of improvements within basin to reduce flooding
  • Limit flooding for adjacent properties
  • Reestablish natural
    drainage patterns

Key Features:

  • Utilized easements for
    surface drainage and underground piping
    through existing properties
  • Coordinated with USACE to modify an existing weir within the Big Sioux
    Levee System

DGR Engineering (DGR) was hired by the City of Sioux Falls in 2016 to analyze and model 120 acres within the City that had experienced multiple flooding events in the recent past. Rain events had caused streets to flood which impacted adjacent private properties.

There was a natural drainage path that was filled in as the area was developed, and the existing storm drainage piping within the right-of-way was inadequate to handle the necessary flows. Furthermore, when the Big Sioux Levee system was built, the outlet for the drainage basin was controlled by piping and weirs, further limiting the discharge.


DGR presented multiple alternatives within the drainage analysis and ultimately the City decided to move forward with three options to improve the drainage and reduce the flood threat.

These options included: 1) Re-routing water further up the basin (at the corner of 46th Street and S. Western Ave.) to utilize existing piping that wasn’t flowing at full capacity. 2) Adding an overland flow channel and underground piping relief on the existing system between properties

(along S. Western Ave, north of 50th Street) to limit street and building flooding. 3) Modifying an existing weir within the Big Sioux Levee System to lower the maximum water elevation within the basin during rain events.

This combination of improvements and restoration of the natural drainage path provides a relief for flood water during rain events, thus reducing the impact to the adjacent properties.