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/L/r ('coed /PFt�oFi�CE <br />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 />/Z00 gpd Ajfy. <br />B. Septic Tank Liquid Volume <br />(see C-3 or C-5) ZODO gallons <br />C. Soil Characteristics <br />1. Depth to restricting layer <br />such as seasonally saturated <br />soil, bedrock, coarse soil, <br />etc.; 20 inches <br />2. Depth of percolation tests; <br />/S inches <br />3. Number of percolation test <br />holes; C holes <br />4. Ave. percolation rate; <br />7. / mp i <br />5. Landslope = .S — 6 y <br />D. Rock Laver Dimensions <br />1. Multiply gpd by 0.83 to <br />obtain required area of <br />rock layer; <br />/1,i gpd x 0.83 = /O.;.Osq ft <br />2. Select width of rock layer <br />(10 feet or less) = feet <br />3. Length of rock layer - Area <br />= Width t !Z O sq f t= /0 ft <br />_ /DO ft <br />E. Rock Volume <br />1. Multiply rock area by rock depth <br />to get cubic feet of rock; <br />/000 sq f t x 0.75 f t= ZSO cu f t <br />2. Divide cu ft by 27 cu ft/cu yd <br />to get cubic yards; 2 7. 8 <br />3. Multiply cubic yards by 1.4 to <br />get weight of rock in tons; <br />L 7_j cu yds x 1.4 - ,?$. 4tons <br />F. Pressure Distribution System <br />1. Select number of perforated <br />laterals S <br />2. Select perforation 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 = YA, S ft. <br />4. Divide lateral length by perfor- <br />ation spacing to get number of <br />perforations per lateral <br />So feet _ _Meet /% perfs <br />Note: last perforation must be <br />in end cap, (see page E-14) <br />5. Multiply perforations per <br />lateral by number of laterals <br />to get total number of <br />perforations; <br />/77_perfs/lat x 6 lats = <br />6. Determine required flow rate <br />by multiplying number of <br />perforations by flow per <br />perforation (see page E-17) <br />1pperfs x .Vf gpm/perf =;N SSgpm <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 />/ 1�- inches 4-re 2 " <br />G. Basal Width <br />1. Percolation rate in top 12 <br />inches of soil is 7_ / mpi urtc <br />2. Select allowable soil.loading <br />rate from table on page E-16; <br />a.-,e 0.60 gpd/ft2 <br />