Northridge Addition

Owner:  Anza Corporation
Location:  City of Watertown, Codington County, South Dakota

Northridge Addition is 180 acres located on the north edge of Watertown, SD. The addition is zoned for residential and light commercial use. Staff at Civil Design Inc. were responsible for surveying and engineering design for drainage improvements.

The drainage point for over 500 acres was through this subdivision. Three detention basins controlled the upstream flow into additional detention basins that controlled the flow into Roby Creek. Flow into the existing detention basins had to be controlled at historic levels to prevent overloading. Peak discharges were controlled to a design peak effluent of approximately 43 cfs, or a flow equal to the two-year historic flow, allowing the developed flow to remain consistent with the design inflow of the downstream detention structures.

The professionals at CDI proposed an innovative system of four detention structures which, once constructed, will manage runoff without affecting downstream infrastructure. In addition to improving drainage in the subdivision, the detention system also provides green space for the development, as all the detention ponds were designed to be dry under normal conditions.

Design elements in this project included roadway design, grading design, detention ponds, control structures, storm sewers, sanitary sewers, potable water, and open channels for storm water conveyance.  Also included was subdivision planning, platting, and construction staking.

Aerial view of three detention ponds in series at Northridge Addition. 
The fourth detention pond is partially visible at the bottom of the picture, below the streets.