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GRADING: <br /> Provide cut and fill calculations in cubic yards. <br /> For bank retention project at <br /> 1905 Concordia Street <br /> Orono, MN <br /> The Cut & Fill calculations get complex because after an erosion episode like happened at the <br /> 9105 Concordia ST because you no longer have good survey information. So, in place of that <br /> we can describe how the work is done and document the materials moved on the site. <br /> The process of installing a subterranean timber grid to anchor a eroding or sliding can provide a <br /> long time protection on shoreline banks. The process looks like a series of retaining walls <br /> stacked up the grade. The difference is that the entire timber structure will be buried under <br /> the surface on the bank. This factor gives the grid the control needed with the treated timbers <br /> which are under the soil so they do not rot for a very long time. <br /> The process starts from the bottom of the bank just behind the rip rap or other shoreline <br /> barrier. The structure is installed a row at a time and each row is dug into the ground as it is <br /> billed. The step are as follows; <br /> 1. Excavation of the area of the bank where the grid will go. This soil is put aside while the <br /> timbers installed and connected to the upper or lower rows of timbers and also supports are <br /> dug into the bank below the timbers giving an anchoring effect. <br /> 2. After the wall of timber is in place the wall is backfilled with an area of gravel rock and a <br /> drainage system in the bottom of the gravel rock. The perforated rock and drainage system <br /> allow moisture to slowly move down out of the spaces in the wall chambers. This removes the <br /> possibility of water build up behind the wall that could push it toward the lake. <br /> 3. When the rock and drainage is in place the spoils of soil that were taken out of the hill are <br /> placed back behind walls at a slope equal to the top of each wall as you progress up the bank. <br /> That process generally uses up all the soil that was moved out to build the next part of the <br /> slope to the top. <br /> Each "section" is 4ft tall 8' wide and 4' back into the bank. When building the sections, the soil <br /> removed generally equals the amount of materials that get placed back into each section of <br /> wall giving a equal cut and fill amounts. If there are differences, those only amount to a few <br /> cubic yards of additional added or removed from the hill side. It amounts to taking soil out of a <br /> trench and then putting it back in the next section of timbers. <br /> Dale Gustafson <br /> Greendale Design <br />