2008-05-01_REVISION - M1973007SG (5)

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MINING PLAN Slope Creation below the Ditch: Although somewhat less critical than the slope above the ditch, the long and high slope below the ditch is still very important to be created in a fashion that achieves maximum stability. Once again, the use of backfill in creating this slope should be limited to only superficial amounts in the upper one to two feet of the final surface. Ideally, all of the slope should be created in completely native material. But mining with such precision, especially when it may take several years to complete this slope, is simply not practical. Erosional damages will occur on the slope during the course of the mining and these will need to be repaired before any headward erosion reaches the top of the slope and undermines the ditch structure. Leaving the surface of this slope with a very rough texture will help limit the ability of water to achieve a high velocity and thereby producing deep gullies. Water can catch in small puddles and more readily soak into the sand rather than combining to create a torrent flowing down a smoothed slope. If an unreclaimed slope, over time,becomes smooth with windblown sand and runoff filling depressions then the slope will be roughened again. All texture created on this slope will be created along the contour and never up and down the slope. Vertical texturing only increases the erosion potential and encourages the creation of deep,rapidly expanding gullies in sand. If a bulldozer is used and it is run up and down the slope, it should always be followed by the bulldozer running along the contour as a final treatment. Harrowing or even discing along the contour is undoubtedly the most economical way to create roughness on a slope. As described in the Reclamation Plan,this can also be a way to prepare the slope for revegetation-as-well as create some additional physical resistance to gully erosion. Th slope below the di�cw2 3.5:1 t the steepest and preferabl�I.T.`!Cross-sectioning of the entire excavation showed that a 3:1 slope, when in sand and south facing, unless very carefully topsoiled with an excellent and very deep silty to sandy loam soil and revegetated quickly and densely, would likely open the door to eventual failure of the ditch. The fact is, 3:1 slopes such as this are highly susceptible to erosion and reducing the erosion on a sandy slope is primarily a function of slope gradient rather than revegetation. Dense vegetation may take several years to develop with a sandy subsoil and should not be relied upon for erosion control for many years. Therefore, a�.I slope is preferred with no areas steeper than 3.5:1. A steeper slope could be created if it is was stepped (terraced),but the final effect on sand production of a stepped slope is very similar to a continuous less gradual slope. The effect on sand production is very similar whether a gradual slope that would look better or a stepped slope that would be marginally more stable but look less attractive is created. Therefore, the better looking continuous slope at 4:1 to 3.5:1 has been selected. Mining the Remainder of the North Area: The mining of the remainder of the North Area is simply a matter of removing the remaining sand, including the material under the current ditch route that will connect the North and South Areas. This can be done by whatever means are appropriate to Daniels Sand Pit Amendment (2008) Exhibit D Page 24 of 28