As water rushed toward St. Louis in May 2015, attention is on geotechnical runaway development that has occurred since the floods of 1993.
ST. LOUIS, — Miles and miles of bigger and stronger levees have been built along the Missouri and Mississippi Rivers since the deadly floods of 1993, and millions of dollars have been spent on drainage improvements.
Building is happening on flood plains across Missouri, but most of the development is in the St. Louis area, and it is estimated to be worth more than $2.2 billion. Though scientists warn about the danger of such building, the Missouri government has subsidized some of it through tax financing for builders.
The existing alignment of the Missouri River levee and embankment system is recognized to have breach/foundation distress from underseepage and boil activity concerns as a result of hydrologic conditions and flow constrictions. The repetitive cycle of repairing levees in place after each major flood event has resulted in increased O&M and RR&R costs, increased flood risk, and a general concern over the effective level of protection. Levee repairs in place do not reduce flood risk. Additionally, the current alignment of federal levees has acted to disconnect the river from its historic floodplain causing environmental degradation and impaired habitat for fish and wildlife. It several locations, bridges (rail and highway) and abutments, have encroached into the river’s conveyance area, increasing stages on the upstream side and increasing velocities on the downstream side, which also influence the performance of the levees.