INNOVATIONS

For construction of foundations for the new river crossing, Kraemer implemented the use of precast floors that served as templates for the foundation casings for the new bridge. We integrated elements from a traditional cofferdam and a deep water precast cofferdam to create a hybrid to expedite construction and substantially reduce the depth of the seals needed for a traditional cofferdam. In addition, this system provides a higher level of quality and reduces environmental impacts within the St. Croix National Scenic Riverway. From a quality standpoint, our approach to the floors of the cofferdams provides a template to ensure the caissons are installed in the correct location and help control the quality of the concrete seal. Our innovative cofferdam design allowed us to install sheet pile directly onto the precast floor while above water, greatly reducing impacts to the river bottom and water clarity by eliminating the need to drive pile with a vibratory hammer.