City engineer reports on 20th St. S. interchange project early stages

Courtesy image: City Engineer Jackie Lanning presented an update on the 20th Street South interchange to the Brookings City Council this week.

City Engineer Jackie Lanning on Tuesday gave the Brookings City Council an update on the 20th Street South interchange project 30% of the way through the process – which is moving quickly.

Most aspects of the project were on target, but estimates for the design, right of way, Department of Transportation costs and utility relocation were running almost a million dollars over estimates, she said. Cost savings in other areas are helping to even out the difference. 


Lanning gave the council a refresher on the project. 

The city was awarded a federal “Better Utilizing Investments to Leverage Development” (BUILD) grant in the fall of 2019. 

“The BUILD Grant was awarded through the U.S. Department of Transportation for a total project cost anticipated at $23,347,037. Approximately $4,669,407 or 20% of the funding is local. This local match is met with city partners including $2 million from Brookings County, $669,407 from private donors and $2 million of city funding to make the project possible,” according to a memo by Lanning, which is attached to the agenda available on the city’s website.

The project started with traffic counts, website release and landowner meetings in March, she said. In May and June, there were updates to the Interstate Justification Report, environmental assessment, utility meetings and preliminary design. More environmental assessments and utility exploration were done in July and August. Preliminary designs take them to 30% plans and cost estimates, Lanning said.

The grant agreement was approved Sept. 1, so this is the first phase of the grant agreement, which includes the design of the project, she said, giving credit to the DOT for administering the project, which helped the city meet the timelines.

“That’s really a key piece,” Lanning said.

“In September and October, one of our key tasks is to release the draft (environmental assessment) on our public online meeting,” Lanning said. The presentation will be posted on the city’s website for 30 days with a public comment section.

They will finalize the right-of-way and finish more plan design, she said.

In November and December, her office wants to meet with landowners and show them the preferred alternative, Lanning said.

The 60% review is tentatively scheduled for November 2020.

“Finally, early next year, moving into finalizing the plans, purchasing right of way, producing our wetland mitigation and then our 90% cost estimate,” Lanning said.

She anticipates bid letting in September 2021.

“And then start construction in 2022 and then finish in 2023,” Lanning said.

“Normally, this is a four-year time-frame, all those tasks, and we’re accomplishing those in about a year and a half timeline,” Lanning said.

Design and costs

Lanning showed a graphic of what the road design will look like, much like the existing 20th Street South segment, 36 feet wide with curb and gutter. Some parts will have three striped lanes, and some details are still to be worked out, she said.  

Lanning ran down the costs, what the original estimates were, and where the estimates are at the 30% mark. 

In the grant agreement, the design, right of way, DOT costs and utility relocation estimate was $1.9 million, but the 30% cost estimate is $2.8 million, she said.

Design was about $500,000 higher than estimated, she said.

“A lot of that is due to just the speed and the number of people it takes, and manhours, to accomplish the design of the project,” Lanning said.

There were about $138,000 of costs by DOT for geotech analysis and design, plan review and right of way appraisal review, Lanning said.

Utility relocation costs needed about $250,000, Lanning said. 

“We’re having a boring company locate those utilities; they shoot the elevations, map it all,” she said.

Councilor Patty Bacon asked for more details on the DOT hours.

“They did the actual geotech borings themselves, too, with their drill rigs; they did the work and the analysis,” Lanning said, as well as the plan review and right of way appraisal review.

Wetland mitigation has not been determined yet, so it continues to stand at $186,090, she said.

DOT construction and administration costs are the same at $1,604,063, she said.

In the grant application, they didn’t specify what type of pavement was to be used, so Lanning broke it down between asphalt and concrete. 

“The DOT will be determining what type of material we should be constructing out of,” Lanning said. 

The grant application estimated construction costs would be $19,644,245. Current estimates for asphalt come in at $18,193,035, while concrete comes in at $18,536,885, she said.

“There’d be only one of those that would be bid,” Lanning said.

The total estimate for the project on the grant application was originally $23,347,037. Current  estimate with asphalt is $22,809,472; current estimate with concrete is $23,153,322, she said.

“Both of those just falling a little bit less than our grant application,” Lanning said.

Councilor Nick Wendell asked if the cost savings make up for the difference in the design and utility relocation so the costs even out.

“Yes,” Lanning said.

Mayor Keith Corbett thanked Lanning and her team for a great job. He added that Sen. John Thune’s office reached out to say “they were tracking this and what a great job all of you are doing and so glad it’s under budget; that’s even better.”

Lanning said the next steps were to continue the design and right of way layouts. The environmental assessment draft will be posted online for a 30-day public comment period; postcards will be mailed out and it will be advertised so the public will be aware and watch it, and her office will meet with landowners.

For more information, visit online.

Contact Jodelle Greiner at

Courtesy of The Brookings Register

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