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III. Hydrologic Condition: Good ( Good: >75% ground cover) <br />IV. Hydrologic Soil Group = C <br />V. CN =74 <br />Runoff Curve Number and Runoff (SurvCAD) <br />Project: Pond 013 By: B Langenfeld Date: 08/18/09 <br />Location: New Horizon #2 Checked: Date: <br />Present <br />1. Runoff Curve Number (CN) <br />Cover description <br />CN <br />Soil Type <br />Area(Acre) <br />Pasture Grassland Range (Good) <br />74 <br />C <br />5.242 <br />Pasture Grassland Range (Good) <br />74 <br />C <br />6.160 <br />Pasture Grassland Range (Good) <br />74 <br />C <br />42.023 <br />Pasture Grassland Range (Good) <br />74 <br />C <br />18.967 <br />CN (weighted): 74.0 <br />Total Area: 72.392 Acre <br />2. Runoff <br />Return Period: 10 -Year <br />Rainfall, P: 2.00 in <br />Runoff, Q: 0.3498 in <br />Runoff Volume: 2.1104 Acre -Ft <br />The pond volume below the emergency spillway will be comprised of three design needs: <br />1) 10 year storm inflow of 2.1 acre feet, as described above <br />3) 3 year sediment delivery of 0.1 acre feet, as based on the calculations shown below. <br />Therefore, the total design volume below the emergency spillway is 2.1+ 0.1 ac -ft which is 2.2 <br />acre feet. As is shown on the stage storage relationship for the as built pond, the bottom of the <br />emergency spillway is 5559', which has a volume of 9.9 acre -ft at this elevation. <br />REVISED AUGUST 2009 Attachment 2.05.3(3) -6 -4 <br />