Stage I, Wapello, Iowa, November 2006.
 
Matrix has been awarded this contract through the U.S. Army Corps of Engineers Rock Island District. 
The project includes the construction of a new 1,100 foot spillway, strengthening of seven miles of Mississippi and Iowa River levees, and the construction of wetlands for snake habitat improvement.
The 1,000 foot spillway was built with recompacted levee soils with 9" of bedding stone and 2 feet of riprap on the river side. This is anchored by a four foot deep 1,100 foot long concrete cutoff wall.  The refuge side of the spillway is comprised of 6 inches of drainage stone overlain and underlain by a non-waven heavy duty geotextile fabric topped with a 4.75 " thick articulated concrete block.  
Matrix will also perform dredging of 300,000 cubic yards of sand from the Mississippi River bottom to provide material for the enhanced the levee system.

Matrix is continuing work at Lake Odessa on a Stage II A contract to dredge 87,000 cubic yards of sediment from the Blackhawk and Yankee Chutes and to pump it 15,000 feet by pipeline to a designated 49 acre dredge disposal site that Matrix cleared and graphed.

On this Stage IIA contract Matrix is placing 6,000 tons of riprap to protect shoreline from erosion at USALE - designated environmentally sensitive zones at eight locations within the Port Louisa National Wildlife Refuge with 4,900 tons placed from the water using a specialized barge with backhoe and conveyor.

In addition, Matrix is mechanically dredging 6,800 cubic yards from two channels connecting inland waterways, constructiong four inland water control structures, and three pump pads to assist the U.S. Fish and Wildlife Service in managing water levels within the refuge.