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1 <br /> MOUND DESIGN WORK SHEET(For Flows up to 1200 d) <br /> A. Average Design FLOW A-1: Estimated Sewage Flows in Gallons per Day <br /> number o <br /> Estimated f)-<Q_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 1, <br /> Jt o 4 ) -i ba oallons (see re C-1) 7 1050 600 370 11, or lu <br /> g 8 1200 1 675 1 408 1 columns. <br /> C. SOILS (refer to site evaluation) ai: Semptkk nk Capacities aeons <br /> Number of Minimum Liquid Liquid capacity with with di posal& <br /> 1. Depth to restricting layer = o z.S feet Bedrooms Capacity garbage disposal lift inside <br /> 2. Depth of percolation tests = /. o feet 2 orless 750 1125 1500 <br /> -A �01L1-y✓1 3 or4 Iwo15W 1500 2W3. Texture Q-A <br /> S orb 1500 2250 3000 <br /> Percolation rate A." mpi 7.8 or9 2000 30°° <br /> 4. Soil loading rate . 4< gpd/sqft(see figure D-33) <br /> 5. Percent land slope <br /> D. ROCK LAYER DIMENSIONS <br /> 1. Multiply average design flow (A)by 0.83 to obtain required rock layer area. <br /> 0-40 gpd x 0.83 sgft/gpd = t>a2 sgft <br /> 2. Determine rock layer width= 0.83 sqft/gpd x linear Loading Rate (LLR <br /> 0.83 sgft/gpdx )a. gpd/sgft= is ft Mound LLR <br /> 3. Length of rock layer= area+width = <br /> -14Z;L,.sgft (D1) + -1 ft (D2) =-e;-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 /> Loa ZL _sgft x 1 ft= "I tuft <br /> 2. Divide cuft by 27 cult/cuyd to get cubic yards <br /> co as cult +27 cuyd/cult=. R3 _cuyd <br /> 3. Multiply cubic yards by 1.4 to get weight of rock in tons <br /> _cuyd x 1.4 ton/cuyd = 3 a tons <br /> D-33: Absorption Width Sizing Table <br /> Percolation Rate Loading Rata <br /> F. SEWAGE ABSORPTION WIDTH in lvtinutaaper SoilTeature Gaittau Abaonprion <br /> Z <br /> per day Ratio <br /> WR OOl <br /> Faster than 5 coarseSud 1.20 1.00 <br /> Medium Sand <br /> Absorption width equals absorption ratio (See Figure D-33) Lcamys.nd <br /> times rock layer width (D2) <br /> 31 to 43 Wit .4 <br /> Silt <br /> a.(.,) x 10 ft=�_ft ��� SilyCl l.wm Law 0. 45 2.67 <br /> 61 to 120Silty pcamy 0. 24 5.00 <br /> Slower thon Sud <br /> -Syms ddprd for Umme r Ah no tK adw or prion u <br />