MARSHALL — Construction bids for Marshall’s new aquatic center are in — but at more than $5 million over an engineer’s estimate.

The city of Marshall held a public bid opening for the project on Thursday afternoon. While the base bids were all in a similar range, the apparent low bid was about $22.37 million, compared to an engineer’s estimate of $16.5 million.

Representatives from Stockwell Engineers said they would review the bids with Marshall city staff, and the bids would then go before the Marshall City Council. The council’s next regular meeting is Sept. 10.

There were five sealed bids submitted for the aquatic center project, each with a base bid and a total of eight alternates. Bidders included Donlar Construction, Sentry LLC, Breitbach Construction Co., BCI Construction Co. and McGough Construction. Base bids submitted for the project ranged from about $22.37 million, to $24.4 million.

The apparent low bidder was Breitbach Construction, with a base bid of $22,375,000.

Last fall, Marshall voters approved a proposal to extend the city sales tax to raise up to $18.37 million in funds for a new aquatic center. However, estimated costs for the project have risen since Marshall first brought the sales tax extension to the state Legislature two years ago.

When the city went out for bids on the aquatic center project earlier this summer, the cost estimate for construction came to about $16.5 million. Additional costs, including safety equipment, concessions equipment, and construction administration, brought total base bid project costs to about $18.95 million.

On top of base project costs, additional features that could be added to the aquatic center came to an estimated cost of about $1.27 million. Those items included features like a body slide, a water walk, climbing walls and shade structures for the Aquatic Center, as well as a privacy wall screening the center from Highway 19.

A community-led committee is working to raise funds to help add amenities at the new aquatic center, with a goal of $1 million. Last week, committee members said community donations and sponsorships have so far raised more than $500,000 toward that goal.