Slurry trenches and relief wells installed to strengthen Ohio and Mississippi river levee systems

Abstract

I n April of 2011, the Ohio River began flooding farmland and cities in Ohio, Indiana, Kentucky, and Illinois, which were not protected by levees. Cairo, Illinois, and many of the other cities on the Ohio and Mississippi rivers protected by levees did not flood, but their levees and floodwalls were in danger of failing due to the constant water pressure against and under the levees and floodwalls. The extra weight of the river at flood stage pushes water under-neath levees and floodwalls increasing the potential for sand boils and undermining the strength of the levee and its capacity to hold back floodwater (Camillo 2012; Morton and Olson 2015). By early May of 2011, the Ohio River gage at Cairo, Illinois, had reached 18.7 m (61.7 ft) (NOAA 2012), and floodwaters were starting to put significant pressure on both Ohio and Mississippi river levee and floodwall systems to the north of Cairo (figure 1). Although, the New Madrid Floodway south of the Ohio and Mississippi river confluence at Cairo was deliberately breached on May 2, 2011, by the United States Army Corps Engineers (USACE) to reduce levee pressure, the levee system north of Cairo, the levee system south of Hickman, Kentucky,…