Purpose

A draft Problem Appraisal Report (PAR) was completed in 2017 to address long term maintenance concerns on the Locks and Dams 2 – 10 embankments.  The draft PAR found that complete riprap overlay of the embankments to rehabilitation rock degradation was not economically justified, but there are other opportunities to improve scour resilience while improving the ecosystem. Some options include upstream berms (figure above), islands to reduce wave fetch, and providing submergible segments with crest superiority at some dams.

Location

Upper Mississippi Locks and Dams 2 – 10.

Description

The U.S. Army Corps of Engineers has designed and constructed many islands in shallow water habitation of the lock and dam pools under Navigation and Ecosystem Sustainability Program (formerly Environmental Management Program, EMP) for environmental sustainability. But these projects have not been considered or placed little emphasis on the embankments scour resiliency. The draft PAR is focused on the dam embankments.

Status

Structural scour protection consisting primarily of riprap overlays was provided near the lock and spillway abutments since 2001, but this work does not include the majority of the embankments. The PAR addressed the remainder of the embankments not rehabilitated by the structural scour protection. The PAR is not a decision or authorization document; and it remains draft since it is for interior use and was not forwarded for division approval. It does provide background data and information use to programmatic prioritization for embankment rehabilitation and repair needs. Separate feasibility reports with integrated environmental assessments will be completed if justified.

The Corps initiated the first feasibility report at Lock and Dam 2 in fiscal year 2017 and completed the report in fiscal year 2021. Plans and specifications for a protective island upstream of Lock and Dam 2 will be completed in fiscal year 2023. Contract award for the Lock and Dam 2 island is contingent upon receipt of funds. The estimated cost is $5.6 million.

Additional non-structural embankment repair at the other locks and dams will continue in future fiscal years.

Authority

Congress authorized the Upper Mississippi River 9-Foot Channel Navigation Project as part of the River and Harbor Act approved July 3, 1930.

Funding

Embankment rehabilitation work at the locks and dams is completely funded by the federal government.

FY 2023:

Updated plans and specifications              $100,000

FY 2024:

Updated plans and specifications ready for award