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MOUND DESIGN WORK SHEET(For Flows up to 1200 gpd) <br /> A. Average Design FLOW A-1: Estimated Sewage Flows in Gallons per Day <br /> number of <br /> Estimated 250 gpd (see figure A-1) bedrooms Class I Class II Class Ill Class IV <br /> or measured — x 1.5 (safety factor) = -- gpd 23 300 20 25 218 225 ohne <br /> 4 600 375 256 values <br /> B. SEPTIC TANK Capacity 5 750 450 294 in the <br /> 6 900 525 332 Class I, <br /> 1tJc 1 000 gallons (see figure C-1) 7 1050 600 370 oral <br /> 8 1200 675 408 columns, <br /> C. SOILS (refer to site evaluation) Gl: Septic Tank Capacities(in gallons) <br /> Liquid capacity <br /> Number of Minimum Liquid Liquid capacity with with disposal& <br /> 1. Depth to restricting layer = a-o 8- 4 feet <br /> Bedrooms Capacity garbage disposal lift inside <br /> 2. Depth of percolation tests = 1' 0 feet 2 or less 750 1125 1500 <br /> 3. Texture IA-> ' 1-00 vvi 3 or 4 1000 1500 2000 <br /> 5 or 6 1500 2250 3000 <br /> Percolation rate ii o• o mpi 7,8 or 9 2000 3000 4000 <br /> 4. Soil loading rate .4 gpd/sqft(see figure D-33) <br /> 5. Percent land slope '') 0/0 <br /> D. ROCK LAYER DIMENSIONS <br /> 1. Multiply average design flow (A) by 0.83 to obtain required rock layer area. <br /> 0 6/0 gpd x 0.83 sqft/gpd = Co a`),, sqft <br /> 2. Determine rock layer width = 0.83 sqft/gpd x linear Loading Rate (LLR <br /> 0.83 sqft/gpd x /a. gpd/sqft = /O ft Mound LLR <br /> 3. Length of rock layer = area =width = <br /> ((,:) ,,> sqft (D1) _ /0 ft (D2) = (a-t ft < 120 M PI < 12 <br /> E. ROCK VOLUME J 120 MPI < 6 <br /> 1. Multiply rock area (D1) by rock depth of 1 ft to get cubic feet of rock <br /> C..7D c), sqft x 1 ft = Cc") D cuft <br /> 2. Divide cuft by 27 cuft/cuyd to get cubic yards <br /> C,9D cuft =27 cuyd/cuft = c1 , cuyd <br /> 3. Multiply cubic yards by 1.4 to get weight of rock in tons <br /> 0.'`,.,) cuyd x 1.4 ton/cuyd = R: tons <br /> D-33: Absorption Width Sizing Table <br /> F. SEWAGE ABSORPTION WIDTH Percolation Rate Loading Rate <br /> in Minutes per Soil Texture Gallons Absorption <br /> inch per day per Ratio <br /> (MPI) square foot <br /> Faster than 5 Coarse Sand 1.20 1.00 <br /> Medium Sand <br /> Absorption width equals absorption ratio (See Figure D-33) F�Sot an <br /> times rock layer width (D2) L6 to 15 Sandy Loam 0 60 1 50 <br /> l6 to 30 Loam 0.60 2.00 <br /> 31 to 45 Silt Loam 0.50 2.40 <br /> Silt <br /> -,,),.ll7 r'.) x /0 ft = r (.-. ,) ft 46 to 60 Sandy Clay Loam 0.45 2.67 <br /> Silty Clay Loam <br /> flay Loam <br /> 61 to 120 Silty Clay 0.24 5.00 <br /> Sandy Clay <br /> clay <br /> Slower than 120" <br /> •System designed for these roils mut be other or performance <br />