Kewaunee Steel Sheet Pile Wall

Case study narrative

Project narrative

7NT was awarded the Geotechnical Engineering Services Contract by the United States Army Corps of Engineers (USACE) for geotechnical services in the Detroit and Chicago Districts. Work was also performed for projects in the Great Lakes and Ohio River Division, which includes all or parts of 17 states: Minnesota, Wisconsin, Illinois, Indiana, Ohio, Kentucky, New York, Pennsylvania, West Virginia, Tennessee, Alabama, Mississippi, Georgia, Michigan, North Carolina, South Carolina, and Virginia.

Work was also performed in Illinois and Wisconsin in the Rock Island District. The Kewaunee Steel Sheet Pile Wall Project in Kewaunee, Wisconsin was under this contract.

The Kewaunee Harbor is a commercial harbor that currently serves primarily recreational boat traffic. The harbor also supports transitory barge traffic. There is approximately 6,500 feet of breakwater and pier structures, and Kewaunee Harbor has approximately 5,500 feet of maintained channel. This harbor is vital to supporting the Government Floating Plant on Lake Michigan.

7NT was contracted to perform geotechnical investigation to determine and characterize the subsurface conditions behind the existing seawall. The geotechnical information was used to design foundations for a steel sheet pile wall.

The project consisted of 7NT completing a Quality Work Plan, Accident Prevention Plan, Schedule, Monthly Progress and Testing Reports, Construction Meetings, and contract modifications for USACE. Two borings were advanced through the overburden soils using 4.25-inch hollow stem augers (HSA). SPT sampling was performed at 2.5-foot intervals to 35 feet and at 5-foot intervals thereafter. Cohesive Shelby Tube samples were taken for each cohesive layer of soil encountered.

The borings were terminated at 58.5 feet and 53.7 feet and grouted with cement/bentonite grout from the bottom using a 1-inch tremie pipe. Lab testing consisted of moisture content, dry density, particle size analysis, Atterberg limits, hydrometer analysis, unconfined compressive strength, consolidated drained triaxial, loss-on-ignition, and description and identification of soils. 7NT submitted a final Subsurface Investigation Report to USACE.

The original page also noted that being an integral part of such a large project for 5 to 10 years speaks to the quality that 7NT staff members regularly deliver.

Scope of work

Technical scope