The big 2011 Missouri River flood caused riverbank erosion – and that affected the Double Ditch Indian Village, north of Bismarck.
The site is an important one for the Mandan Indians, in terms of trade on the Missouri.
"The following year -- 2012 -- we noticed the beginning of the slumping," said Fern Swenson with the State Historical Society of North Dakota. "At that point, we knew we needed to contact some people and seek some funding, in order for us to be able to stabilize this very important site.
Swenson says the Society hired Atwell Group of Georgia to do a site survey – and figure out what needs to be done to stabilize the bank and shore up the site. Charlene Webber with Atwell says it’s a complicated situation.
"It is enhanced by being adjacent to and abutting one of the most culturally-sensitive sites north of Bismarck," said Webber. "It's to the point where even below, the slump is now uncovering prior burial grounds. So there is archeological significance."
Webber says because of that, Atwell will not be doing a traditional engineering approach. Instead, she says Atwell will take more of a “bio-engineering approach.”
"We're working with the Mandans, we're working with the State Historical Society, to be very sensitive, and keep the historical integrity of the site as natural looking, with natural plantings, to make it look as if nothing ever happened," said Webber.
Webber says her firm has also been encouraged to “think outside the box” when it comes to improvements at the site.
"We want to make it available to the community, in terms of pathways and walkways," said Webber. "Maybe extending those walkways at Double Ditch to have access to the water. We're trying to accommodate a lot of wishes into our engineering plan. But first and foremost, it's to stabilize the bank, so this doesn't happen again."
The state Historical Society was given $3.5 million from the Legislature to make the site improvements at Double Ditch.
