Laserfiche WebLink
MOUND DESIGN WORK SHEET(For Flows pp to 1200 gpd) <br /> A. Average Design FLOW <br /> A-l: Estimated Sewage Flows in Gallons per Day <br /> number of <br /> Estimated L.o O gpd (see figure A-1) bedrooms Class I Class II Class 111 Class IV <br /> or measured x 1.5 (safety factor) = - gpd 2 300 225 180 60% <br /> 3 - 450 300 218 of the <br /> B. SEPTIC TANK Capacity 4 600 375 256 values <br /> 5 750 450 294 in the <br /> 6 900 525 332 Class I, <br /> .--)00 t7 gallons (see figure C-1) 7 1 050 600 370 II,or Ill <br /> i o 0 0 g �� Gy �, <br /> .,1 �1 � R 8 1200 675 408 columns. <br /> C. SOILS (refer to site evaluation) C-1: Septic Tank Capacities(in allons) <br /> Number of Minimu n Liquid Liquid capacity with wihidisal& <br /> 1. Depth to restricting layer= a.S , a.'613.0 feet Bedrooms Capacity garbage disposal <br /> 2. Depth of percolation tests = 1.0 feet 2 or less 7S0 1125 llf1 mslde <br /> 3. Texture 1-1--4q t_o Awl 3 or 4 '000 1500 1500 <br /> 5 or 6 500 2250 2000 <br /> Percolation rate L..9 mpi 7,8 or 9 .000 3000 3000 <br /> 4. Soil loading rate •9 gpd/sqft(see figure D-33) a000 <br /> 5. Percent land slope JO <br /> D. ROCK LAYER DIMENSIONS <br /> 1. Multiply average design flow (A) by 0.83 to obtain required rock layer area. <br /> Loa gpd x 0.83 sqft/gpd = 491 sgft-t-toga= S42 <br /> 2. Determine rock layer width = 0.83 sqft/gpd x linear Loading Rate (LLR: <br /> 0.83 sqft/gpd x I gpd/sqft= Jo : ft <br /> 3. Length of rock layer = area_width = Mound LLR <br /> S'12 sqft(Dl) _ /0 ft (D2) = SS ft < 1 20 MPI < 1 2 <br /> E. ROCK VOLUME <br /> > 120 MPI < 6 <br /> 1. Multiply rock area (D1)by rock depth of 1 ft to get cubic feet of rock <br /> 6'4') sqft x 1 ft = S4 9 cuft <br /> 2. Divide cuft by 27 cuft/cuyd to get cubic yards <br /> 549 cuft _ 27 cuyd/cuft = .J) cuyd <br /> 3. Multiply cubic yards by 1.4 to get weight of rock in tons <br /> 1.1 cuyd x 1.4 ton/cuyd = - .0/ 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 <br /> (MPI) square foot Ratio <br /> foot <br /> Faster than 5 2oarse Sand 1.20 1.00 <br /> Absorption width equals absorption ratio (See Figure D-33) l..oamy San Sand <br /> ..oamy Sand <br /> Fine Sand <br /> times rock layer width (D2) 6 to 15 Sandy Loam 0.79 1.50 <br /> 16 to 30 Loarn 2.00 <br /> 31 to 45 Silt Loam 0.5500 2.40 <br /> • Silt <br /> tor/ x 10 ft = ..io.0 ft 46 to 60 Sandy Clay Loam 0.45 2.67 <br /> Silty Clay Loam <br /> Clay Loans <br /> 61 to 120 Silty Clay 0.24 5.00 <br /> Sandy Clay <br /> Clay <br /> Slower than 120• <br /> *System designed for these toils must be other or performance <br />