Levees are frequently built on compressible alluvial soils along rivers because of river depositional patterns. These compressible and saturated soils settle over time due to primary and secondary compression. This continued settlement results in the levee having to be repeatedly raised to provide the desired flood protection. Levees are usually raised with conventional soil fill to return the levee to its original level. The extra weight from the levee raising causes additional settlement and the cycle of settlement and raising continues.
EPS geofoam can be easily installed to provide the volume needed to return the levee to its original configuration. And with approximately 1% of the weight of traditional soil fills, the use of EPS as fill reduces/eliminates additional stress and the cycle of settlement and levee raising. Of course, sufficient protective soil cover must be placed above the EPS geofoam. EPS geofoam can be easily handled at sites that have difficult accessibility and, if needed, EPS geofoam can be transported by barge.
To allow placement of the EPS geofoam, a portion of the existing levee is removed and stockpiled for reuse as soil cover for the EPS geofoam. A geotextile is used on the exposed subgrade to provide separation and improved stability. EPS geofoam blocks are placed on a sand-leveling bed and a geomembrane cover is used to encapsulate the blocks. A geotextile is placed over the geomembrane and the excavated soil is compacted over the EPS geofoam to bring the levee to its design elevation. These same principles can be applied to the construction of a new levee.