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E-19 <br />MOUTJD DESIGN PROCEDURE <br />(For Flows up to 1200 gpd) <br />A. Sewage Flow Rate <br />See D-7 or 1-3, A, or 5, or use <br />metered value; Flow Rate = <br /><^0 0 gpd <br />B. Septic Tank Liquid Volume <br />(see C-3 or C-5) /£fao gallons <br />C. Soil Characteristics <br />1. Depth to restricting layer <br />such as seasonally saturated <br />soil, bedrock, coarse soil, <br />etc. ; 7^ inches <br />2. Depth of percolation tests; <br />/4 inches <br />3. Number of percolation test <br />holes; V holes <br />4. Ave. percolation rate; <br />/?. 2 mpi <br />5. Landslope = 3 % <br />D. Rock Layer Dimensions <br />1. Multiply gpd by 0.83 to <br />obtain required area of <br />rock layer; <br />(,0 0 gpd X 0.83 ° SOO sq ft <br />2. Select width of rock layer <br />(10 feet or less) = /O feet <br />3. Length of rock layer = Area <br />■1 Width-T££_sq ft -j- tO ft <br />" SO ft <br />E. Rock Volume <br />1. Multiply rock area by rock depth <br />to get cubic feet of rock; <br />SOO sq ft X O.-ySit = 375cu ft <br />2. Divide cu ft by 27 cu ft/cu yd <br />to get cubic yards; /3. 9 <br />3. Multiply cubic yards by 1.4 to <br />get weight of rock in tons; <br />fjcu yds X 1.4 “ /y, y tons <br />F. Pressure Distribution System <br />1. Select number of perforated <br />laterals _ _£_ _ _ <br />2. Select perfor"..ion spacing <br />= 3_ _ft <br />3. Select perforated lateral <br />length; Note if manifold is <br />at end of rock layer, lateral <br />length is rock layer length <br />less half a perforation <br />spacing. If manifold is in <br />center of rock layer, lateral <br />length is one-half rock layer <br />length less half a perforation <br />spacing. Perforated lateral <br />length = 23.5 ft. <br />4. Divide lateral length by perfor­ <br />ation spacing to get number of <br />perforations per lateral <br />5 feet f _3_feet = 2 porfs <br />Note: last perforation must be <br />in end cap, (see page E-14) <br />5. Multiply perforations per <br />laternl by number of laterals <br />to got total number of <br />perforations; <br />2 pcrfs/lat X ^ lats = ^2 <br />uur/i <br />•/‘i" <br />6. Determine required flow rate <br />by multiplying number of <br />perforations by flow per <br />perforation (see page E-17) <br />perfs X .7/ gpm/perf =Jf^gpm <br />7, Select minimum required lateral <br />diameter from table on Page E-17; <br />enter table with perforation <br />spacing, perforation diameter, <br />and number of perforations per <br />lateral. Select minimum <br />diameter for perforated lateral <br />= / y<f " inches t//<f z'/i" <br />G. Basal V/idth <br />1. Percolation rate in top 12 <br />inches of soil is /?. ^mpl <br />2. Select allowable soil loading <br />rate from table on page E-lb; <br />O. (50 gpd/f t^-