Pinnacle Engineering was retained by a southern Minnesota City to assist with dredging and expansion of harbor facilities adjacent to the Mississippi River. The expansion was needed to divert waiting barge traffic out of the main Mississippi River channel and to improve safety in the harbor. The City hired Pinnacle to design the dredging and spoils area, interface with regulators, prepare an Environmental Assessment Worksheet (EAW), obtain dredging, wetland, and threatened and endangered species permits, and remediate water quality.
Pinnacle completed an EAW in Minnesota and an Environmental Assessment in Wisconsin to allow for the dredging to proceed. The project required extensive permitting and negotiations with U.S. Army Corp of Engineers, Minnesota Pollution Control Agency, Minnesota Department of Natural Resources, Minnesota’s Board of Water and Soil Resources, U.S. Fish and Wildlife Service, and Wisconsin Department of Natural Resources. Each agency had specific requirements for the project. Extensive study of issues related to water quality, wildlife habitat functions and potential sensitive environmental species, and thorough wetland delineation and mitigation, were required to satisfy all interests.
In addition, the Project had a limited dredge spoils disposal area which required extensive negotiations with the MPCA over water quality issues. A dewatering method was agreed upon for the dredge spoil area.
Ultimately, nine acres of the backwater was dredged, increasing the harbor’s staging and loading capabilities, and backwater wetland impacts were mitigated by creating over 12 acres of new wetlands in a nearby City park.