As part of the design-build team for this project, Ayres Associates provided hydraulic and scour analysis in support of this design-build project to replace the US 61 bridge over the Mississippi River in Hastings, Minnesota. The project involved detailed floodplain hydraulics using HEC-RAS, bridge scour analysis, and scour countermeasure design.
An important aspect of the hydraulic design was the need to ensure compliance with Federal Emergency Management Agency floodway regulations. Ayres provided a design that did not require revising the floodway or requesting a Conditional Letter of Map Revision. Scour and debris issues also were significant. The project required regular coordination with a large, multidisciplinary design team and strict adherence to schedule milestones.