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MOUND DESIGN WORKSHEET (For flows up to 1200 gpd) <br /> i' OU14D A <br /> A. FLOW 375 gpd or measured X 1.5 = gpd <br /> B. SEPTIC TANK LIQUID VOLUMES: 2 - 1250's <br /> C. SITE EVALUATION INFORMATION <br /> 1. Depth of clean sand req. 18.00 inches or 1.50 feet <br /> 2. Depth of percolation tests = 12 inches <br /> 3. Perc. Rate 17 mpi <br /> 4. Land Slope 2.0 percent <br /> D. ROCK LAYER DIMENSIONS <br /> 1. Multiply flow rate by 0.83 to obtain required area of rock layer: <br /> 375 gpd X 0.83 sq ft/gpd 311.25 sq. ft. rock area <br /> 2. Select width of rock layer (Max 10' if<120, or max 5' if>120) 10.0 Yeet <br /> 3. Rockbed length (area/width) 311 sq. ft. / 10.0 feet = 33 feet <br /> E. ROCK VOLUME <br /> 1. Multiply rock area by rock depth to get cubic feet of rock: <br /> 311.25 sq. ft X 1.0 = foot = 311 cubic feet <br /> 2. Divide cubic feet by 27 to get cubic yards: <br /> 311 cu. ft. / 27 = 11.5 cubic yards <br /> 3. Multiply cubic yards by 1.4 to get weight of rock �n tons: <br /> 11.5 cu. yd. X 1.4 = 16.1 tons X 10 % = 20.2 ton req'd <br /> F. ADSORPTION WIDTH <br /> 1. Percolation rate in top 12 inches of soil is 17.0 m i <br /> Soil Texture is SILL ISize for Clay Loam <br /> 2. Select allowable soil loading rate from table: 0.45 gpd 1 sq. ft. <br /> PEC RATE MPI SOIL TEXTURE GPD/SQ.FT. RATIO <br /> FASTER>0.1 COARSE SAND1.2(1 1 00 <br /> 0.1 TO 5 SAND 1.20 1.00 <br /> 0.1 TO 5 FINE SAND 0.60 2.00 <br /> 6 TO 15 SANDY LOAM 0.79 1.52 <br /> 16 TO 30 LOAM 0.60 2.00 <br /> 31 TO 45 SILT LOAM 0.50 2.40 <br /> 46 TO 60 CLAY LOAM 0.45 2.67 <br /> 60 TO 120 CLAY 0.24 5.00 <br /> >120 CLAY 0.20 6.00 <br /> 3. Calculate adsorption width ratio by dividing rock layer loading rate <br /> of 1.20 gpd / sq. ft. by allowable soil loading rate: <br /> 1.20 gpd/ sq. divided by 0.45 gpd / sq. ft. equals 2.67 <br /> 4. Multiply adsorption width ratio by rock layer width to get required adsorption width: <br /> 2.67 X 10.0 feet = 27 feet adsorption width <br /> additional feet added. <br />