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 also 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 were 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.