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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 r)SO 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 3 450 300 218 0 % <br /> of <br /> >✓:clss)s+ � � >MA{-i�ti 4 600 375 256 values <br /> B. SEPTIC TANK Capacity k-s'. 1?v w - tic 6 900 455 750 5 294 Classthe, <br /> 7 1050 600 370 ll, or III <br /> I-)D--,c0 4- I-iooagallons (see figure C-1) 8 1200 675 408 columns. <br /> C. SOILS (refer to site evaluation) C-I: Septic Tank Capacities(in gallons) <br /> Liquid capacity <br /> Number of Minimum Liquid Liquid capacity with with disposal& <br /> 1. Depth to restricting layer = 1,0 feet Bedrooms Capacity garbage disposal lift inside <br /> 2. Depth of percolation tests = /•0 feet 2 or less 750 1125 1500 <br /> 3. Texture_G "j A- 3 or 4 1000 1500 2000 <br /> 5 or 6 1500 2250 <br /> Percolation rate I a . (a mpi 7,8 or 9 2000 3000 400 <br /> 4. Soil loading rate 04 gpd/sqft (see figure D-33) <br /> 5. Percent land slope '7 % J <br /> D. ROCK LAYER DIMENSIONS <br /> 1. Multiply average design flow (A) by 0.83 to obtain required rock layer area. <br /> 9 0 gpd x 0.83 sqft/gpd = c,,,a D sqft <br /> 2. Determine rock layer width = 0.83 sqft/gpd x linear Loading Rate (LLR) <br /> 0.83 sqft/gpd x I a gpd/sqft= 10 ft Mound LLR <br /> 3. Length of rock layer = area+width = <br /> (o a a, sqft (D1) + JO ft (D2) = Co(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 /> L,a s sqft x 1 ft = D. cuft <br /> 2. Divide cuft by 27 cuft/cuyd to get cubic yards <br /> Co a. cuft +27 cuyd/cult = a 3 cuyd <br /> 3. Multiply cubic yards by 1.4 to get weight of rock in tons <br /> a cuyd x 1.4 ton/cuyd = 3 a 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) Loamy <br /> c SSand <br /> times rock layer width (D2) 6 to l56to30 Sandy Loam o 761.So_ <br /> 1lyL 0.60 0 2.00 <br /> 31 to 45 Silt Loam 0.50 2.40 <br /> Sill <br /> -�o / <br /> �7 x J0 ft = ac,. 7 ft 4610 60 Sandy Clay Loam 0.45 <br /> 2.67 <br /> Cey laLourLoam y <br /> 61 to I.') Silty Clay 0.24 5.00 <br /> Sand Cl <br /> ClaYay <br /> Slower than 120* <br /> *System designed for Nue rolls nun be other or performance <br />