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1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />current ground levels. The initial material will be removed from the site. After a portion of the <br />mine is opened up, the stockpiles will be placed in the bottom of the pit. <br />A small temporary uninhabitable trailer will be used as a scale-house and it will be removed during <br />the reclamation of the site. The trailer is approximately 16 feet by 20 feet and will be placed near <br />CR 13 at the access point. The trailer will be anchored to the ground for protection against flooding <br />events. HEC-2 modeling shows that the trailer would not have any significant impact on the water <br />surface elevation if a flood were to occur during the mining process. <br />Because the site will be under consistent change during the alining process, there is no way to <br />accurately model the interim condition. With the removal of the initial stockpiled material, the <br />elevation of existing ground is not raised. Therefore, the hydraulic capacity of the site is not <br />reduced and there should be no negative impact on the floodplain or the floodway. <br />The proposed reclamation plan includes the construction of a reservoir for water storage. The <br />reservoir embankments will be returned to existing grade. The reservoir will be inundated by and <br />interact in flood conditions with the Cache la Poudre main channel flows. <br />The reclaimed reservoir returns the perimeter of the reservoir to the existing ground elevations. <br />Printouts of the input and the output for the HEC-2 model are in the located in Attachment G of this <br />document. In order to be conservative it was assumed that the reservoir was full during a flood <br />event. No flood storage was accounted for in the reservoir. The Manning's N value to reflect water <br />on water was assumed to be 0.01. These updates to the existing model result in the following <br />changes to the model shown in Table 2 below: <br />NA 148960 4780.7 <br />NA 149580 4781.4 <br />NA 151100 4782.8 <br />NA 152250 4785.4 <br />NA 152300 4785.6 <br />'A 152340 4787.6 <br />*61 152390 4787.6 <br />'C 153515 4787.9 <br />'D 154485 4788.8 <br />'E 155595 4789.8 <br />F 156815 4792.5 <br />G 156865 4794.4 <br />H 156905 4794.8 <br />I 156955 4795.2 <br />J 157720 4796.6 <br />K <br />L 159000 4797.4 <br />8 <br />159805 4797 <br />. <br />' On Site Cross Sections <br />4781.4 0.0 <br />4782.8 0.0 <br />4785.4 0.0 <br />4785.6 0.0 <br />4787.6 0.0 <br />4787.6 0.0 <br />4787.9 0.0 <br />4788.2 -0.6 <br />4788.2 -1.5 <br />4792.5 -0.1 <br />4794.4 0.0 <br />4794.8 0.0 <br />4795.3 0.0 <br />4797.4 0.0 <br />4797.8 0.0 <br />Table 2: Existing vs. Proposed Conditions <br />The proposed HEC-2 model indicates that the reclaimed conditions would not significantly affect <br />the water surface elevations with a maximum increase being 0.0 feet in the natural (non-floodway) <br />run. This amount is not measurable in relation to the FEMA base flood elevations for the natural <br />Serfer Pit I Floodplain Development Permit <br /> <br />