1993- MCWD permit #93-72 - Laserfiche WebLink

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Erosion problems are common along bluff shorelines where a variety of forces and processes act together. The most prevalent causes of bluff erosion and recession are occur at the toe(base)by waves and instability of the bluff materials themselves. A typical bluff often consist of layers of different soils, which do not stand permanently at a vertical face. Failure of the slope depends on the nature of the material. A cohesive material (clay)will move as large blocks either by toppling due to undercutting or by sliding out in a curved arc. Granular material (sand or gravel)will erode easily by flowing water and wave action. Vertical sided blocks will drop due to and undercutting of the slope or the soil will suddenly flow down an inclined plane. Height is a factor because high bluffs (over 20 feet) impose greater stresses and are likely to have more severe stability problems than low bluffs. The Design for the Susan Sumey project does not try to design against these unpredictable forces. The Landowner(Susan Sumey)should be told of these phenomenas, and instructed on maintenance of their measure should they occur. The Soil Conservation Service policy in Minnesota does not allow installation of high-maintenance protection for a single landowner without proven means to maintain the installation. An example of a high-maintenance measure is artificial nourishment. The technician, conservationist, or engineer involved in the project should discuss maintenance with the landowner prior to design of the measure. A maintenance plan should be prepared by the designer for the specific job. It should be discussed with the landowner. The Landowner must be aware of their responsibility in this area, and sign a maintenance agreement prior to the installation of the measure. The plan must be attached to the O&M agreement signed by the landowner. Sincerely, *1" 44117 Stephen Spartz