The US Army Corps of Engineers, Rock Island District (District), requests your review of the Environmental Assessment (EA) titled, Emergency Dredging, Lock and Dam 22 Lower Dredge Cut, Pool 24, River Mile 300.0 – 301.0, Upper Mississippi River, dated May 2021. Although the emergency dredging took place in 2020, the District is interested in your review and comments regarding the alternative analysis and project outcomes. The District is also letting the public know how the District met its environmental compliance requirements.
The public is invited to submit comments regarding the alternative analysis and preferred alternative for this project through June 2, 2021.
Comments can be submitted via this online COMMENT FORM, through email at: PublicInvolvement@usace.army.mil, or by writing to the address below.
To request a paper copy or CD, contact the District’s Environmental Compliance Branch at 309-7945791, email: PublicInvolvement@usace.army.mil, or write to:
Department of the Army
US Army Corps of Engineers, Rock Island District
Attn: Jordan(PD-C) Clock Tower Building
P. O. Box 2004
Rock Island IL 61204-2004
PROJECT INFORMATION
In 2020, the District identified up to 66,000 cubic yards (CY) of material blocking the navigation channel in the Mississippi River 9-Foot Navigation Channel in Pool 24 at river mile (RM) 300.6. This shoal developed downstream of the Lock 22 approach. As water levels continued to drop, the approach became challenging or impassable for commercial shipping traffic creating an emergency situation.
The District has not dredged this area in Pool 24 since 2014. Due to lack of dredging requirements at this location and concerns about mussel resources at historic placement sites, the District prepared this EA to evaluate the environmental impacts of emergency dredging and placement of dredged material.
ALTERNATIVES CONSIDERED
- No Action
- Dredge to the authorized depth and place in the Channel Border adjacent to the dredge cut.
- Dredge and place material along the Missouri bankline adjacent to the Missouri Thompson Conservation Area
- Dredge and place material along the Illinois bankline adjacent to the Cottel Island (or Brown’s Island).
- Dredge to the authorized depth and place at the Lock and Dam 22 DMMP, Upland Site 8.
PREFERRED ALTERNATIVE
Alternative 2, Dredge to the authorized depth and place in the Channel Border adjacent to the dredge cut. Initially, the District mechanically dredged a narrow pilot channel and placed the 6,402 CY of dredged material along the Gilbert Island shoreline (RM 298). The District used the Dredge Potter to hydraulically dredge 107,246 CY to the open water channel border adjacent to the dredge cut. Material was placed channelward of the wing dams to avoid impacting habitat between the wing dams or mussel beds along the Illinois bankline. Due to time constraints, this was the preferred alternative to avoid placing material on top of known mussel beds along the Illinois and Missouri shorelines (See Alternatives 3 & 4). The On Site Inspection Team (OSIT) concurred this location would be the most environmentally acceptable placement site. If the District conducts emergency dredging in this location in the next 5 years and these placement sites have adequate capacity, the District may use these sites, pending OSIT approval.