Courtesy image: Pictured above is the current design for the Interstate 29 interchange at 20th Street South. The clover is in the southwest quadrant and not in the other quadrants due to protected wetland areas and Edgebrook Golf Course. There are other designs for the overpass, but Alternate 5 is being recommended for the project.

Plans for a new Interstate 29 interchange at 20th Street South are on schedule and remain under budget, and a recommended design has been presented to local officials.

City Engineer Jackie Lanning gave a 60% update on the project to city councilors and county commissioners in the past two weeks.

The update provided new information Lanning has gathered from the draft Environmental Assessment (EA) of the project, speaking with the landowners affected by the project and to address their concerns, and to provide additional information for the cost estimate.

The most significant change to the update was the asphalt cost estimate, which went up from $18,193,035 to $18,354,703, bringing the total project cost estimate at this point to $22,971,140. Asphalt has been chosen for the project because there are settlement concerns with a concrete roadway.

The City and County are funding $2 million apiece for the project, and the BUILD Grant awarded in 2019 is kicking in $18.7 million. Private donors are adding nearly $700,000.

“This is a really condensed timeline due to the grant requirements that were stipulated, and we asked during the COVID season if there were any exceptions and extensions to these timelines, and there are not. So right now, we are staying on schedule,” said Lanning at the Dec. 1 County Commission meeting.

Everything is still on track for scheduling and construction timelines, and the project remains under the $23.3 million budget.

The draft EA recommends a design for the interchange that is new for the Brookings area.

“And as you can see, it will have typical ramps on the east side of the interstate and then a clover leaf on the southwest quadrant. And this interchange will look much like the Flying J interchange on I-29 down near Sioux Falls,” Lanning said at the Dec. 8 Brookings City Council meeting.

Lanning said working around the golf course and wetlands would be expensive and extend the project timeline. So instead, they would not do the clover ramp on those sections of the interchange.

“There are protected wetlands in the northeastern quadrant that could not be disturbed, and then also the golf course could not be disturbed” due to federal funding used when the course was started, Lanning said.

“One item that we’re working on with this project is the streetlight layout. … Really wanting to stay on time and on budget and for simplicity’s sake, we’re going with just a standard lighting system. So we’ll have our steel cobrahead lights. They’ll be 30 feet tall with an 8-foot arm. They will be LED … and these are the lights that are on the west end of Sixth Street,” said Lanning at the City Council meeting.

“We’re proposing for the City to provide all of the power to the streetlights on this system, even on the interchange and off ramps. Typically, the municipality will provide power. It’s not something that is provided by the DOT or Federal Highway, and we do have a statute listed there giving us the authority to provide that power,” Lanning said.

Planners still need to finalize the environmental assessment for the impact of the interchange and will respond to landowners about their questions, including access options.

“For next steps, we’re compiling the comments and the responses on the EA. We’ll finalize that EA document, and we submit it for approval, and what we’re wanting to have at the end of the process is a ‘Finding of No Significant Impact,’ … that means that all of the environmental clearances have been approved, there’s no significant impact and it’s signed off by DOT and Federal Highway,” Lanning said at the county meeting. “And then we’re also working with the landowners and their questions. They have had some access questions as to driveway approaches and things like that on 20th Street South, so we’re working through those.”

Appraisals for obtaining rights-of-way will begin in January, and determining cost estimates for utilities is still ongoing. 

The 90% project update is anticipated in February 2021, with the bidding process to begin in September 2021 and construction to begin in 2022.

Information in the interchange can be found at

Contact Matthew Rhodes at

COURTESY OF: The Brookings Register

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