The U.S. Army Corps of Engineers Rock Island District has released for public review, the Regulating Structure Repair Environmental Assessment for River Miles 595.4-599.0 in POOL 11 of the Mississippi River. The public is invited to submit comments regarding the alternative analysis and preferred alternative for this project through March 5, 2021.
Comments can be submitted via this online COMMENT FORM, through email at: PublicInvolvement@usace.army.mil, or by writing to the address below.
The purpose of this Regulating Structure Repair project is to reduce sediment deposition in the navigation channel and frequency of dredging events in the Hurricane Island and Finley’s Landing Reaches in Pool 11 of the Upper Mississippi River. This reduction in dredging would allow for the cost-effective operation and maintenance of the 9-foot navigation channel project.
To view a full copy of the report click here: Regulating Structure Repair Environmental Assessment for River Miles 595.4-599.0 in POOL 11
To request a paper copy or CD, contact the District’s Environmental Compliance Branch at 309-794-5174, email: PublicInvolvement@usace.army.mil, or write to:
Department of the Army
US Army Corps of Engineers, Rock Island District
Attn: Michl (PD-P)
Clock Tower Building
P. O. Box 2004
Rock Island IL 61204-2004
The Regulating Structure Repair project is in Pool 11 along the right descending bank of the Upper Mississippi River, between river miles 595.4 and 599.0. The navigation channel centerline is the border between Grant County, Wisconsin, and Dubuque County, Iowa. The Rock Island District proposes to reduce dredging in Pool 11 by making structural improvements to two closing dams in the Hurricane Island and Finley’s Landing reaches of the Mississippi River and constructing rock vanes to stabilize the Hurricane Island bank line placement site. The District’s future concern is that sediment deposition in this area is impeding commercial shipping within the 9-foot Navigation Channel Project. This would cause navigation delays for barges travelling upstream and downstream. This Environmental Assessment, noted above, assesses the potential impacts of the proposed regulating structure repairs as part of the operation and maintenance of navigation channel.
The primary goal of regulating structure construction is to reduce future demand for maintenance dredging in the 9-foot navigation channel along this stretch of the river, thus decreasing the impacts of dredging and dredge material placement and the cost of operation and maintenance of the navigation channel. Restoring regulating structures would allow commercial navigation to continue with a reliable and safe navigation channel depth and width.
PROPOSED AND ALTERNATIVE ACTIONS
During the planning process, 17 alternatives were analyzed, as described in Section II of the Regulating Structure Repair Environmental Assessment for River Miles 595.4-599.0 in POOL 11. Each alternative was screened for its ability to meet both the project objective of reducing shoaling in the navigation channel and the federal standard for environmental acceptability and cost-effectiveness. Two alternatives, Alternative 0, No Federal Action, and Alternative 17a, Closing Dam Restoration and Enhancement with Rock Vanes, were considered feasible and reasonable and were carried forward to a final array of alternatives. The District then determined Alternative 17a as the preferred alternative.
Alternative 17a includes rebuilding the closing dam at the head of Hurricane Island near RM 599.2 to original design grade elevation (600 feet mean sea level), raising the closing dam along the left descending bank at RM 595.8 to elevation 601 feet mean sea level, and installing nine rock vanes (at 604.5 feet mean sea level) to stabilize the bank line adjacent to the Hurricane Island placement site. The closure structure at RM 595.8 would have a notch with a length of 250 feet to an elevation of 599.5 feet to ensure access for recreational boaters, as requested by the Iowa Department of Natural Resources.