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a• <br /> To: Dale Leach <br /> Date:October 2014 <br /> Page 4 <br /> Fill Materials <br /> Fill material requirements can vary depending on location and use. There are four main fill types <br /> associated with this work: <br /> Concrete Chucks/Rock and Earth Fill from Donath Lake (Structural Fill) - Fill material <br /> within 7 feet of the ditch below the normal ditch water line should be generally free of debris and <br /> organic matter. Sand excavated from the ditch should not be placed in these sections. This <br /> material should be used to build up the damaged sections of the ditch as well as undamaged low <br /> spots on the ditch road. <br /> Concrete Chunk/Rock Fill— Fill material placed on the outer ditch embankments in the two <br /> sections that have washed out should be free draining with a stable surface. The interior of this <br /> fill should be composed of concrete chucks and/or rocks. Sand should be added only on the <br /> outer surface to allow vegetation to grow on the outer surface and should not comprise a large <br /> portion of the fill. <br /> Sand Fill - Fill on-top of the existing Louden road could tolerate settlement and could be <br /> anything that could create a drivable surface. Trees, sand and other organic matter may be used. <br /> These areas will settle at different rates over time, future low maintenance to maintain a smooth <br /> drivable surface will be needed. <br /> Placing material on wet or frozen surfaces can prevent intimate contact between layers of <br /> material creating a greater chance for the layers to separate (failure plain) and increase <br /> maintenance issues. <br /> The bottom of ditch near the headgate likely has a rocky, naturally formed channel bed. <br /> Downstream sections of the ditch likely have clay or natural rock surface. The pre-flood ditch <br /> bottom should not be penetrated when excavating debris or during ditch reconstruction. Leaving <br /> a layer of sediment on top would be preferable to risking penetrating this layer. Penetrating this <br /> layer can increase water loss through the bottom of the ditch and create a weak spot allowing <br /> erosion to propagate. If the ditch bottom is damaged it should be repaired prior to the irrigation <br /> season. Repair would include excavating out the damaged spot and placing high clay content <br /> materials similar in texture, size, and composition to the undamaged ditch bottom and <br /> compacting in thin layers. <br /> R:\Louden_Ditch\Louden_Ditch\Products\2013_Flood\Engineering Rec Letter\1 0032013_Louden_Ditch_Eng_Assesment_Letter.docx <br />