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MOUND DESIGN WORK SHEET(For Flows up to 1200 d) <br /> A. Xverage Design FLOW A-1: Estimated Sewage Flows in Gallons per Day <br /> number o <br /> Estimated (p00 gpd (see figure A-1) bedrooms Class I Class 11 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 /> ( <br /> ll <br /> � -/0 0 C7 gallons see re - 7 1050 600 378 II,or III <br /> g �� C1) 8 1 1200 1 675 408 columns. <br /> C. SOILS (refer to site evaluation) G1: Septic Tank Capacities m ilons <br /> Number of Minimum Li uid Liquid capacity with Liquid capacity <br /> 9 9 P�ty wwith disposal& <br /> 1. Depth to restricting layer = 1 r ) feet Bedrooms Capacity garbage disposal lift inside <br /> 2. Depth of percolation tests = /10 feet 2 or less 750 1125 1500 <br /> 3. Texture L L� ✓� 3 a 4 1000 1500 2000 <br /> Sorb 1500 2250 3000 <br /> Percolation rate I ix-3 o 7,g or 9 2000 3000 4W 1 <br /> 4. Soil loading rate -4.5'.5' gpd/sgft(see figure D-33) LL4K )_0Y4 YVA <br /> 5. Percent land slope Le % <br /> D. ROCK LAYER DIMENSIONS <br /> 1. Multiply average design flow (A) by 0.83 to obtain required rock layer area. <br /> - (,,(Do gpd x 0.83 sgft/gpd = 4 624 sgft <br /> 2. Determine rock layer width = 0.83 sqft/gpd x linear Loading Rate (LLR <br /> 0.83 sqft/gpd x !—1, gpd/sqft= /0 ft Mound LLR <br /> 3. Length of rock layer = area=width = <br /> sgft(D1) j Q ft (D2) = 90 ft < 120 MPI <12 <br /> E. ROCK VOLUME > 120 MPI < b <br /> 1. Multiply rock area (D1) by rock depth of 1 ft to get cubic feet of rock <br /> l ­) (g�' sqft x 1 ft= 4c7 s� cuft <br /> 2. Divide cuft by 27 tuft/cuyd to get cubic yards <br /> 1015K' cuft i 27 cuyd/cuft = I � cuyd <br /> 3. Multiply cubic yards by 1.4 to get weight of rock in tons <br /> _cuyd x 1.4 ton/cuyd = a 5' tons <br /> D-33: Abrtorption Width Sizing Table <br /> PercoF. SEWAGE ABSORPTION WIDTH in Minute Rote Loading Rate <br /> in Minute per Soil Texture Gallons Absorption <br /> Inch per day per Ratio <br /> MPI uere foot <br /> Faster than 5 Coarse Sand 1.20 1.00 <br /> Medium Sand <br /> oamAbsorption width equals absorption ratio (See Figure D-33) l Fine Sand <br /> sand <br /> 79 1 <br /> times rock layer width (D2) 16 0 2.°° <br /> 1 to 45Silt Loam 2.40 <br /> Silt <br /> x 1 C� ft — n? f t 46 a 60 Sandy 0.45 2.67 <br /> — Silt Clay <br /> loam <br /> 61 to 120 Silty Clay 0.24 5.00 <br /> Sandy Clay <br /> Slower than 120• <br /> -System designed fm these mils mwt be other or performs— <br />