Lock and Dam #3 is located six miles north of Red Wing and just downriver from the Prairie Island nuclear plant on the Mississippi River at Welch, Minnesota. It was originally constructed in 1938 and last underwent major rehabilitation in the late 1980s. Since that time, the changes in the river’s navigable waterways and traffic levels required upstream improvements.
The lock is one of the most highly trafficked by recreational boaters in the Upper Mississippi. AET worked under Ed Kraemer & Sons via design-build procurement to assist with these efforts for the U.S. Army Corps of Engineers (USACE), St. Paul District. The large undertaking consisted of extending the upstream guidewall, placing a 50-foot diameter, concrete-filled sheet pile cell and modifying the river flow to reduce the outdraft condition at the lock and dam.
AET provided geotechnical engineering, construction materials testing (CMT), construction inspections and quality management throughout the project. During the embankment construction, AET monitored pore-water pressure via vibrating wire piezometers. The new guidewall was constructed using piles supporting a cast-in-place concrete wall. The wall was further protected by an earthen dyke that ties the new wall to the existing USACE dock facility. A unique type of wall was constructed utilizing precast segments and cast-in-place concrete to reduce the construction impacts to navigation. AET performed specialized concrete temperature modeling for large mass concrete placements, to ensure that cast-in-place materials remained in specified temperature ranges to meet anticipated strength.