Tetra Tech INCA completed this concept study in 2005 for the Rock Island District, which followed work previously performed in 2000 to design 118-foot long post-tensioned concrete box beams for new lower guide walls on the Upper Mississippi River. Both design efforts required close coordination with Rock Island and St. Louis Districts.

INCA prepared design criteria, developed lock concepts, evaluated the new lock alternatives, prepared preliminary construction schedules (including considerations of required closures of the existing lock), and completed quantity take-off and planning level cost estimates. INCA recommended a lift-in precast concrete alternative for the new lock wall designs, and this general concept was selected as the basis for future design phases. In performance evaluations for this task order, INCA received an overall rating of Excellent and our design services were rated at Outstanding in all categories.