In late 2017, AAI conducted diamond core drilling and logging as part of an evaluation of the interior concrete conditions at five locks and dams on the upper Mississippi River for the U.S. Army Corps of Engineers (USACE). Falling head tests were completed in the core holes to measure permeability in the guide walls. ESI Labs was retained to perform concrete core petrographic and air void analyses. [Contract No. W912ES17P0091].