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E-19 <br />MOUND DESIGN PROCEDURE <br />(For Flows up to 1200 gpd) <br />A. Sewage Flow Rate <br />See D-7 or I-3, 4, or 5, or use <br />metered value; Flow Rate = <br />�15 0 gpd <br />B. Septic Tank Liquid Volume <br />(see C-3 or C-5) 12DO gallons <br />C. Soil Characteristics <br />1. Depth to restricting layer <br />such as seasonally saturated <br />soil, bedrock, coarse soil, <br />etc.; __inches <br />2. Depth of percolation tests; <br />/8 inches <br />3. Number of percolation test <br />holes; holes <br />4. Ave. percolation rate; <br />A. 2 mp i <br />5. Landslope Z % <br />D. Rock Layer Dimensions <br />1. Multiply gpd by 0.83 to <br />obtain required area of <br />rock layer; <br />1150 gpd x 0.83 Q-?73,5 sq f t <br />2. Select width of rock layer <br />(10 feet or less) = 10 feet <br />3. Length of rock layer o urea <br />Width 371.3sq f t= L f t <br />-77. 3.7 f t <br />E. Rock Volume <br />1. Multiply rock area by rock depth <br />to get cubic feet of rock; <br />177�_sq f c x $. 75 f t= 2FOcu f t <br />2. Divide cu ft by 27 cu ft/cu yd <br />to get cubic yards; A0. y <br />3. Multiply cubic yards by 1.4 to <br />get weight of rock in tons; <br />ZiLycu yds x 1.4 - IV. 5 tons <br />F. Pressure Distribution System <br />1. Select number of perforated <br />laterals 6 <br />2. Select perforation spacing <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 ,lanifold 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 - /Z. Z ft. <br />4. Divide lateral length by perfor- <br />ation spacing to get number of <br />perforations per lateral <br />LZ,Lfeet _ 3 feet - 6 perfs <br />Note: last perforation must be <br />in end cap, (see page E-14) <br />5. Multiply perforatio-iis per <br />lateral by number cf laterals <br />to get total number of <br />perforations; <br />__perfs/lat x _C:.ats - .?6 <br />6. Determine required flow rate <br />by multiplying number of „ <br />perforations b <br />p y flow per �•r Pia .�; <br />perforation (see page E-17) <br />' 6 perfs x .7Ygpm/perf =76`b gprn <br />7. Sheer -'nimum required lateral <br />diame rom table on Page E-17; <br />anter with perforation <br />spacing, ,,erforation diameter, <br />and number of perforations per <br />lateral. Select minimum <br />diameter for perforated lateral <br />_ lYet" inches I-rIF /Y7" <br />G. Basal Width <br />1. Percolation rate in top 12 <br />inches of soil is J& 2 mpi <br />2. Select allowable soil loading <br />rate from table on page E-16; <br />oj-e 0. VS gpd/ft2 <br />