The $5 million River Greenway project along the banks of the Big Sioux River in downtown Sioux Falls is digging up some hidden costs.
The River Greenway project began three months ago. It will add larger sidewalks, an amphitheater and more landscaping to make the banks of the Big Sioux more of a park than just a bike path.
And to build the walls along the water crews have to drill down to the bedrock, but that rock is not where they thought it would be.
"The bedrock elevation throughout the wall section of our project was a little bit deeper than anticipated," River Greenway project Manager Brad Ludens said.
The soil borings done before construction to find the depth of the bedrock hit big boulders, which gave project managers a false sense of where they'd find the bedrock.
Now that work has started, crews found out they have to dig deeper and pour more concrete for the walls. They also have to remove more soil which is costly because it's contaminated from its industrial past.
"And all that has to go out to the landfill and you have the extra costs associated with more concrete and more steel for the walls themselves," Ludens said.
"We're constructing a project in the hardest part of town to do something in. So, these types of things we know are going to happen and that's why we try to build flexibility into the project," Jon Jacobsen with the project consulting firm Confluence said.
There is a $1.4 million contingency fund built into the 'quality of life' bond that includes the River Greenway project. But, the city will look for other ways to save money to make up for the hidden costs they dug up.
"The mayor does not want to tap into that contingency fund at this point, so what we're doing then in order to stay in our project budget is we're taking a look at some ways to scale back the budget," Ludens said.
The city is still adding up how much the extra work will cost.