Before a tragic landslide killed two young students on a field trip to Lilydale Regional Park this past spring, slope failures, rockfalls and other changes had occurred within the park and elsewhere along the Mississippi River bluffs.
But two independent investigations commissioned by the city of St. Paul concluded that despite evidence of soil erosion, the city couldn't have predicted or prevented the fatal landslide.
St. Paul Mayor Chris Coleman announced the results at a Thursday news conference accompanied by investigators who led the inquiries.
"The tragic nature and consequences of what happened were not predictable or forecastable and at the end of the day, the city staff had acted appropriately in response to what they knew about the general conditions in Lilydale Park," Coleman said.
Fourth-graders Mohamed Fofana, 10, and Haysem Sani, 9, from Peter Hobart Elementary School in St. Louis Park, died after a cliff at the park collapsed on May 22. Two other children were injured. The students had been hunting for fossils at the popular site, when the waterlogged hillside gave way.
Following the incident, the city of St. Paul hired Hamline University School of Law Dean and former Assistant U.S. Attorney Don Lewis to lead a review of internal processes and communications leading up to the landslide. Northern Technologies Inc. (NTI), a civil engineering firm, was tasked with examining the collapse's cause.
Lewis' team concluded that the city did know that soil erosion was an environmental threat within Lilydale park, however, the city didn't know that soil erosion was a threat to the safety of visitors to the fossil ground site.
A 2009 study noted there was "erosion along the walls of the former clay pits" and recommended that the city survey erosion and identify stabilization measures, but the city hadn't done so by the time the landslide occurred.