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OSTP Trench Design <br /> UNIVERSITY <br /> Minnesota Pollution Worksheet OF MINNESOTA <br /> Control Agency <br /> 1. SYSTEM SIZING: Project ID: v 05.13.14 <br /> A. Design Flow: 750 GPD <br /> B. Code Maximum Depth: inches Designers Maximum Depth: inches <br /> C. Soil Loading Rate: 0.78 GPD/ft2 Contour Loading Rate: 12.0 gal/ft <br /> D. Required Bottom Area: Design Flow(1.A)-Loading Rate (1.C) = Initial Required Bottom Area <br /> 750 1 GPD- 0.78 GPD/ft' = 962 ft <br /> E. Select Dispersal Media: 0 Rock <br /> (selection required) ❑ Registered Product <br /> F. Select Distribution Method: ❑ Pressure Iv Gravity-Drop <br /> Gravity-Other <br /> G. If distribution media is installed in contact With sandy or loamy sand or with a percolation rate of 0.1 to 5 mpi <br /> indicate distribution or treatment method: <br /> 2. TRENCH CONFIGURATION: ROCK <br /> A. Initial required Sidewall Bottom Area Bottom Area Design <br /> trench bottom area Absorption trench — <br /> ft2 from 1.D (inches) Reduction Multiplier bottom area <br /> ( ): ( ) Cover <br /> 6 to 11 1 962 <br /> Q <br /> 962 Distribution <br /> 12 to 17 20% 0.8 769 <br /> 18 to 23 34% 0.66 635 Sidewall <br /> 24 40% 0.6 577 <br /> B. Select Sidewall Height: 20 inches = ft ���/� <br /> Width <br /> C. Design Bottom Area (2.A): 635 ft <br /> D. Select Trench Width: 2 ft <br /> E. Total Designed Trench Length: Bottom Area :Trench Width =Total Required Trench Length <br /> 635 ft _ 2.0 ft= 318 ft <br /> I. Calculate Minimum system length based on Contour Loading Rate: Design Flow : Contour Loading Rate = <br /> 750 gpd. 12.0 gal/ft = 62.5 ft <br /> F. Select No. of Trenches: trenches <br /> G. Select Trench Spacing : ft (typically 5 - 12 ft from center to center) <br /> H. Calculate Lawn Area:Trench Length (2.E)X Trench Spacing (2.G) =square feet of lawn area <br /> 318 ft X ft = 1588 ft2 lawn area <br /> J. Select Depth Required to Cover Distribution Pipe: <br /> 0.5 ft (0.33 ft for pressure, 0.5 ft for gravity) <br /> K. Calculate Rock Volume: (Sidewall Height (2.6) + Depth to Cover Pipe (2.J))X Bottom Area(2.C)=cubic feet <br /> ft + 0.50 ft ) X 635 ft, = 1376 ft <br /> Divide ft'by 27 ft3/yd 3 to calculate cubic yards: <br /> 1376 ft3 + 27 = 51 yd3 <br />