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/ ElDdti .Duvet/ <br /> 3 BED�ov� E-19 <br /> / MOUND DESIGN PROCEDURE <br /> (For Flows up to 1200 gpd) <br /> A. Sewage Flow Rate F. Pressure Distribution System <br /> See D-7 or I-3, 4, or 5, or use <br /> metered value; Flow Rate 1. Select number of perforated <br /> 5/SO gpd laterals <br /> 2. Select perforation spacing <br /> B. Septic Tank Liquid Volume = 3 ft <br /> (see C-3 or C-5) /O00 gallons ' <br /> 3. Select perforated lateral <br /> C. Soil Characteristics length; Note if manifold is <br /> at end of rock layer, lateral <br /> 1. Depth to restricting layer length is rock layer length <br /> such as seasonally saturated less half a perforation <br /> soil, bedrock, coarse soil, spacing. If manifold is in <br /> etc. ; _inches ( center)of rock layer, lateral <br /> 2. Depth of percolation tests; length is one-half rock layer <br /> /8 inches length less half a perforation <br /> spacing. Perforated lateral <br /> 3. Number of percolation test length Z ft. <br /> holes; ,3 holes <br /> 4. Divide lateral length by perfor- <br /> 4. Ave. percolation rate; ation spacing to get number. of <br /> LS S mpi perforations per lateral <br /> 5. Landslope = y % /7, 2 feet -. 3 feet = 6 perfs <br /> Note: last perforation must bu <br /> D. Rock Layer Dimensions ' in end cap, (see page E-14) <br /> 1. Multiply gpd by 0.83 to 5. Multiply perforations per <br /> obtain required area of lateral by number of laterals <br /> rock layer; to get total number of <br /> `/SO gpd x 0.83 =37..Ssq ft perforations; <br /> 6 perf s/lat x 6 lats = 36 <br /> 2. Select width of rock layer 6. Determine required flow rate <br /> (10 feet or less) _ _/feet <br /> by multiplying number of „ <br /> 3. Length of rock layer - Area perforations by flow per f <br /> = Width 37,E Ssq ft = /o f terf oration <br /> 37. 35f t �� p (see page E-17) <br /> 36 perfs x Ztgpm/perf =,?6.69pm <br /> E. Rock Volume 7. Select minimum required lateral <br /> diameter from table on Page Ii-17; <br /> 1. Multiply rock area by rock depth enter table with perforation <br /> to get cubic feet of rock; spacing, perforation diameter, <br /> 37,E Ssq ft x O.7Sft - 280cu ft and number of perforations per <br /> 2. Divide cu ft by 27 cu ft/cu yd lateral. Select minimum <br /> to get cubic yards; /0•t/ diameter for perforated lateral <br /> _ /�y •• inches <br /> 3. Multiply cubic yards by 1.4 to <br /> get weight of rock in tons; G. Basal Width <br /> /-0.ycu yds x 1.4 /Y.'05 tons <br /> 1. Percolation rate in top 12 <br /> inches of soil is !t. 5 mpi <br /> 2. Select allowable soil loading <br /> -- rate from table on page E-16; <br /> O Rpd/f t2 <br />