Vicksburg, Miss… The U. S. Army Corps of Engineers (Corps) Vicksburg District’s Mat Sinking Unit (MSU) is scheduled to begin laying articulated concrete mats on the banks of the Mississippi River on August 26. The vessels of the MSU will depart the Vicksburg Harbor, Friday, 23 August 2013, and assemble around noon below the I-20 bridge before proceeding to their first worksite.