8th Street and 20th Avenue Drainage Improvements

8th Street and 20th Avenue Drainage Improvements


Brookings, SD

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The State Avenue Watershed is a 680-acre watershed in the heart of Brookings that affects residents, businesses, and college students during storm events. The watershed includes residential and commercial districts in addition to South Dakota State University. The City of Brookings, through their drainage master plan, identified five storm sewer improvement projects to mitigate localized flooding and handle 5-year and/or 100-year storm events within the watershed. Banner analyzed the existing watershed model and provided recommended improvements to the storm sewer system. Banner prepared cost estimates for the improvements to help the City budget for the improvements.  

The first phase consisted of storm sewer improvements on 8th Street, north of Village Square. Storm sewer was installed under the street and includes added inlets to capture flow off the street. The system also allows for additional connections from Village Square. The Structural Department designed a specialized junction box to tie the proposed storm sewer into an existing box culvert crossing 8th Street. The project also improved pedestrian access by completing the sidewalk network with ADA-compliant pedestrian ramps at the intersection of 8th Street and 20th Avenue. The sidewalk network is also connected to the trail that runs through McCrory Gardens. Banner provided design and construction phase services for the first phase of this significant drainage project.

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Project Goal #1

Reduce storm water flows passing through the commercial area of Village Square and the SDSU Greek Residential neighborhoods.

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Project Goal #2

Improve storm water conveyance on 8th Street and 20th Avenue.

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Project Goal #3

Complete the sidewalk/trail network at the intersection of 8th Street and 20th Avenue to provide access for pedestrian traffic to both sides of the roadway and to the trail through McCrory Gardens.

Project Features

  • Approximately 1,100 LF of reinforced concrete storm sewer pipe ranging in diameter from 18" to 36"
  • 5 Drop Inlet Structures - (4 Sioux Falls Type and 1 Type B)
  • 7 Concrete Junction Boxes
  • ADA accessible pedestrian facilities

Services Provided

  • Topographic Survey
  • Watershed and Hydraulic Analysis
  • Preliminary/Final Design
  • Construction Contract Administration
  • Construction Staking and Observation

Support Disciplines