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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 Coo o gpd (see figure A-1) bedrooms Class I Class II Class Ill Class Iv <br /> or measured — x 1.5 (safety factor) = — gpd 2 300 225 450 300 218 0 % <br /> 3othe <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 /> a- /060gallons (see C-1) 7 1050 600 370 II, or Ill <br /> gure 8 1200 675 408 columns. <br /> C. SOILS (refer to site evaluation) G1: Septic Tank Capacities(in gallons <br /> Liquid capacity <br /> Number of Minimum Liquid Liquid capacity with with disposal& <br /> 1. Depth to restricting layer = 'az, .(o,a.9 feet Bedrooms Capacity garbage disposal lift inside <br /> 2. Depth of percolation tests = 1.0 feet 2 or less 750 1125 1500 <br /> 3. Texture L-01D1--w)-(o ct_14,4�.or}vh 3 or 4 1000 1500 2000 <br /> 5 or6 1500 2250 3000 <br /> Percolation rate .Z).`d mpi 7,8 or 9 2000 3000 ,ddd <br /> 4. Soil loading rate ,‘-i,‘ gpd/sqft(see figure D-33) <br /> 5. Percent land slope / 0 % <br /> D. ROCK LAYER DIMENSIONS <br /> 1. Multiply average design flow (A) by 0.83 to obtain required rock layer area. <br /> (000 gpd x 0.83 sqft/gpd = 1-19ce sgft-)-loth = 5y)tli <br /> 2. Determine rock layer width = 0.83 sqft/gpd x linear Loading Rate (LLR) <br /> 0.83 sqft/gpd x I 2- gpd/sqft= /0 ft Mound LLR <br /> 3. Length of rock layer = area +width = <br /> Syr") sqft (Dl) + 10 ft (D2) = 55 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 /> Ste') sgft x 1 ft = c14`) cuft <br /> 2. Divide cuft by 27 cuft/cuyd to get cubic yards <br /> Ste') cuft + 27 cuyd/cuft = a.0 cuyd <br /> 3. Multiply cubic yards by 1.4 to get wei�ht of rock in tons <br /> a.o cuyd x 1.4 ton/cuyd = ' 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) s.uare foot <br /> Faster than 5 Coarse Sand 1.20 1.00 <br /> Medium Sand <br /> Sand <br /> Absorption width equals absorption ratio (See Figure D-33) LoamyFine Send <br /> 6 to 14 Sandy Loam �a , i9 <br /> times rock layer width (D2) 16to30 Loam 0.60 a• <br /> 31 to 45 SiltSilt <br /> Loam 0.50 2.40 <br /> Q. l// x /,r, ft = a .n! f t 46 to 60 Sandy Clay Low 0.45 2.67 <br /> Silty Clay Loam <br /> Clay Loam <br /> 61 to 120 Silty Clay 0.24 5.00 <br /> Sandy Clay <br /> Clay <br /> Slower than 120' --' <br /> •System designed for Nese soils oust be ocher or performance <br />