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3. ABSORPTION AREA SIZING Note:Mound setbacks are measured from the Absorption Area. A. Calculate Absorption Width:Bed Width (2.8)X Mound Absorption Ratio (1.F)=Absorption Width 10.0 ft X 2.0 = 20.0 ft B. For slopes>1%, the Absorption Width is measured downhill from the upslope edge of the Bed. Calculate Downslope Absorption Width:Absorption Width (3.A)-Bed Width (2.B)=ft 20.0 ft - 10.0 ft = 10.0 ft 4. MOUND SIZING A. Calculate Clean Sand Lift: 3 feet minus Depth to Limiting Condition (1.C)=Clean Sand Lift (1 ft minimum) 3.0 ft - 1.2 ft = 1.8 ft Design Sand Lift (optional): 1.8 B. Calculate Upslope Height:Clean Sand Lift (4.A)+media depth (1 ft.)+cover (1 ft.) =Upslope Height 1.8 ft + 1.0 ft + 1.0 ft= 3.8 ft 3.34:Slope Muitiplier Table Land Slope% 0 I 2 3 4 5 6 7 8 9 10 11 12 13 14 115 16 17 18 19 20 21 22 23 24 25 UpSIUpe 3:1 3 OC 2 91 2 13 2 75 2.68 2.61 2.54 2,43 2.42 2.35 2 31 2.26 2.21 2'7 2'312 09 206 2,03 2.0.3 1.97 1.95 1.93 1,9' 1.89 1.87 1.85 BPr01 Rdl'0 4:1 4.00 3.85 3.70 3.57 3.45 3.33 3.23 3.12 3.03 2.94 2.86 2.78 2.70 2.62 2.55 2,48 2,41 2.35 2.29 2.23 2.18 2.13 2,08 2.03 1.98 1.93 Land Slope% 0 I 2 3 4 5 6 7 8 9 10 11 12 13 14 IS 16 17 18 19 20 21 22 23 24 25 UG'.mslope 13:1 3 O 3.09 3.'9 33 30 3.41 3.53 3.66 3.80 3.95 4.11 4.29 4.48 4.69 4.95 5 24 5.55 5.88 6.24 6.63 7.34 7.47 7.93 8.42 3.93 9.46 X3.02 Burro Rat:o !4:1 4 OC 4.17 4.35 4.54 4.76 5,00 5.26 5.56 5.88 6.25 6.67 7.14 7.69 8.29 8.92 9.57 10.24 10.94 1167 12.42 13.19 13.99 14.82 15.67 16.54 17.44 Select Upslope Berm Multiplier C. (based on land slope): 3.23 (figure D-34) D. Calculate Upslope Berm Width:Multiplier (4.C)X Upslope Mound Height (4.B)=Upslope Berm Width 3.23 ft x 3.8 ft = 13.0 ft E. Calculate Drop in Elevation Under Bed:Bed Width (2.8) X Land Slope (1.D): 100=Drop (ft) 10.0 ft X 7.0 % + 100= 0.70 ft F. Calculate Downslope Mound Height: Upslope Height (4.B)+Drop in Elevation (4.E)=Downslope Height 3.8 ft + 0.70 ft = 4.5 ft G Select Downslope Berm Multiplier (based on land slope): 5.56 (figure D-34) H. Calculate Downslope Berm Width:Multiplier (4.G)X Downslope Height (4.F)=Downslope Berm Width 5.56 x 4.5 ft = 25.0 ft I. Calculate Minimum Berm to Cover Absorption Area:Downslope Absorption Width (3.B or 3.C)+4 ft. =ft 10.0 ft + 4 ft = 14.0 ft J. Design Downslope Berm =greater of 4H and 41: 25.0 ft K. Select Endslope Berm Multiplier: 3.00 (usually 3.0 or 4.0) L. Calculate Endslope Berm (4.K)X Downslope Mound Height (4.F)=Endslope Berm Width 3.00 ft x 4.5 ft = 14.0 ft M.Calculate Mound Width: Upslope Berm Width(4.D)+Bed Width (2.6) +Downslope Berm Width (4.J)=ft 13.0 ft + 10.0 ft + 25.0 ft = 48.0 ft N. Calculate Mound Length: Endslope Berm Width (4.L)+Bed Length (2.C) +Endslope Berm Width (4.L)=ft 14.0 ft + 63.0 ft + 14.0 ft = 91.0 ft Comments: