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University of Minnesota Mound Design Worksheet - 10125/04 <br /> All boxed rectangles must be entered,the rest will be calculated. <br /> ONsrrr <br /> SEWAGE <br /> A. Estimated Flov4 600 gpd(Fig.A-1) 7:17-re <br /> REAT rrrT <br /> PROGRAM _- <br /> A-1 Estimated Sewage Flows in GPD <br /> Number of Class <br /> Bedrooms I II III IV <br /> 2 300 225 180 60%of <br /> 3 450 300 218 the <br /> 4 600 375 256 values <br /> 5 :' 750 450 294 in the <br /> 6 900 525 332 Class I, <br /> 7 : 1050 600 370 II or II <br /> 8 1200 675 408 columns <br /> B. Minimum Septic Tank Capacity <br /> Septic tank capacity 2000 gallons Number of tanks/compartments 0 <br /> Effluent filter(yes/no) Yes <br /> C-1 Minimum Septic Tank Capacity in Gallons <br /> Number of Minimum Capacity with Capacity with GD and *GD=garbage disposal <br /> Bedrooms Capacity GD* pump in basement** Must have multiple tanks or compartments <br /> 2 or less 750 1125 1500 ** Must have multiple tanks,compartments <br /> 3 or 4 1000 1500 2000 or effluent screen <br /> 5 or 1500 2250 3000 <br /> 7,8 or 2000 3000 4000 <br /> C. SOILS(Site evaluation data) D-33 Absorption Width Sizing Table <br /> 1. Depth to restricting layer 1.6 feet Perc Rate <br /> mpi Soil Texture Loading Rate Absorption <br /> 2. Texture loam (gpd/ft2) Ratio <br /> Coarse sand,Loamy <br /> 3. Loading rate(see Fig D-33) 0.60 gpd/ft2 <5 sand,Med and Fine 1.20 1.00 <br /> sand <br /> 4. Absorption Ratio(Fig D-33) 2.00 6-15 Sandy loam 0.79 1.50 <br /> 16-30 Loam 0.60 2.00 <br /> 5. Percolation rate if available 3 MPI 31-45 SiltLoam,Silt 0.50 2.40 <br /> 46-60 Clay loam(CL),Silty 0.45 2.67 <br /> 6. %Slope 7 % or Sandy CL <br /> 61-120 Silty or Sandy 0.24 5 <br /> Clay or Clay <br /> >120* <br /> *Must be other or performance. <br /> D. ROCK LAYER DIMENSIONS <br /> 1. Multiply average design flow(A)by 0.83 to obtain required area of rock layer.Item A x 0.83= <br /> 600 gpd x 0.83 ft2/gpd 498 ft2 LLR Chart <br /> 2. Determine rock layer width =0.83 ft2/gpd x Linear Loading Rate(LLR)(see LLR chart) Perk Rate LLR <br /> 0.83 ft2/gpd x 12 = 10.0 ft <120 MPI <=12 <br /> 3. Length of rock layer=area divided by width= >=120 MPI* <=6 <br /> 498 ft2 / 10 ft = 50.0 ft *or other limited soil conditions <br /> E. ROCK VOLUME <br /> 1. Multiply rock area by rock depth to get cubic feet of rock <br /> 498 X 1 ft = 498.0 ft3 <br /> 2. Divide ft3 by 27 ft3/yd3 to get cubic yards <br /> 498.0 ft3 / 27 = 18.4 yd3 <br /> 3. Multiply cubic yards by 1.4 to get weight of rock in tons; <br /> 18.4 yd3 X 1.4 ton/yd3 = 25.8 tons <br /> 4. Add in 10%extra for constructability= 1.1 x 25.8 = 28.4 tons <br />