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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 ').0 gpd(see figure A-1) bedrooms Class I Class II Class III Class IV <br /> or measured -- x 1.5 (safety factor) = - gpd 2 300 225 180 60% <br /> 3 . 450 300 218 of the <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 /> 7 1050 600 370 II,or III <br /> 1-)).So 1-1000 gallons(see figure C-1) 8 1200 675 408 columns. <br /> 14.5n cf.1 Tisw►v L14.14"icF. <br /> C. SOILS (refer to site evaluation) C-1: Septic Tank Capacities(18 gallons) <br /> Liquid capacity <br /> 1 44 3 y 's Number of Minimum Liquid Liquid capacity with with disposal& <br /> 1. Depth to restricting layer= 1..S 1.c 4,..o•feet Bedrooms Capacity garbage disposal lift inside <br /> 2. Depth of percolation tests = ). v ' feet 2 or less 750 1125 1500 <br /> 3. Texture /.1....k.- 1.0 A-wl 3 or 4 1000 1500 2000 <br /> 5 or 6 1500 2250 3000 <br /> Percolation rate 30, 0 mpi 7,8 or 9 2000 3000 4000 <br /> 4. Soil loading rate +`A S gpd/sqft(see figure D-33) <br /> 5. Percent land slope Le oh <br /> D. ROCK LAYER DIMENSIONS <br /> 1. Multiply average design flow (A)by 0.83 to obtain required rock layer area. <br /> r_<0 gpd x 0.83 sqft/gpd = to a.1 sqft <br /> 2. Determine rock layer width= 0.83 sqft/gpd x linear Loading Rate (LLR) <br /> 0.83 sqft/gpd x 1 gpd/sqft= to ft Mound LLR <br /> 3. Length of rock layer= area+width= <br /> (o�:")...sgft(Dl) + 10 ft (D2) = (o ft < 120 MPI <12 <br /> E. ROCK VOLUME > 120 MPI < 6 <br /> 1. Multiply rock area (Dl) by rock depth of 1 ft to get cubic feet of rock <br /> (ex). sqft x 1 ft= to a a cuft <br /> 2. Divide cuft by 27 cuft/cuyd to get cubic yards <br /> Le cuft +27 cuyd/cuft = a3 cuyd <br /> 3. Multiply cubic yards by 1.4 to get weight of rock in tons <br /> al cuyd x 1.4 ton/cuyd = 3 a tons <br /> t <br /> D-33: Absorption Width Sizing Table <br /> Percolation Rate Loading Rate <br /> F. SEWAGE ABSORPTION WIDTH In Minutes per Soil Textu a Gdlons Absorption <br /> Inch per day per Ratio <br /> (MPI) square root <br /> Faster than 5 Coarse Sand 1.20 1.00 <br /> Medium Sand <br /> Loamy Sand <br /> Absorption width equals absorption ratio (See Figure D-33) 6 to 1s <br /> Fine <br /> ySand <br /> 79 1.50 <br /> times rock layer width (D2) 6 t°}}QQ p� 0.60 2.00 <br /> �1 11 tol3 Si SI Loam 0.50 2.40 <br /> d•�e x ft= fie.7 f t 46 to 60 Sandy OLoam <br /> Sindy Clay Loam 0.45 2.67 <br /> l7ay Inam <br /> 61 to 120 Silty Clay 0.24 5.00 <br /> Si cyaClay <br /> Slower than 120' 11 <br /> *System designed for these soils num be ether or perromesece <br />