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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 1-3, 4, or 5, or use <br />metered value; Flow Rate » <br />^SO gpd <br />F. Pressure Distribution System <br />B. Septic Tank Liquid Volume <br />(see C-3 or C-5) fooo gallons <br />C. Soil Characteristics <br />1. Depth to restricting layer <br />such as seasonally saturated <br />soil, bedrock, coarse soil, <br />®tc.; inches <br />2. Depth of percolation tests; <br />if Inches <br />3. Number of percolation test <br />holes; ^ holes <br />4. Ave. percolation rate; <br />//. O mpl <br />Z X5. Landslope « <br />D. Rock Layer Dimensions <br />1. Multiply gpd by 0.83 to <br />.• obtain required area of <br />rock layer; <br />gpd X 0.83 ft <br />2. Select width of rock layer <br />(10 feet or less) - jp feet <br />3. Length of rock layer ■ Area <br />- WidthJ7/.5 sq ft - iP ft ' <br />- ft <br />E. Rock Volume <br />1. Multiply rock area by rock depth <br />to get cubic feet of rock; <br />sq ft y^P,75 tt - 2££cu ft <br />2. Divide cu ft by 27 cu ft/cu yd <br />to get cubic yards; /^. y <br />3. Multiply cubic yards by 1.4 to <br />get weight of rock In tons; <br />/P,ycu yds X 1.4 - /y. 5 tons <br />1. Select number of perforated <br />laterals € <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 />rock layer length <br />a perforation <br />If manifold is in <br />rock layer, lateral <br />one-half rock layer <br />length, less half a perforation <br />spacing. Perforated lateral <br />length - /7. Z ft. <br />length Is <br />less half <br />spacing, <br />center of <br />length Is <br />4, Divide lateral length by perfor­ <br />ation spacing to get number of <br />perforations per. lateral <br />/7.2 feet f( ^ fjfeet “ C perfs <br />Note: last\^ej;foratlon 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 />< perfs/lat x ^ lats - SC <br />6. Determine required fl,ow rate <br />by multiplying number of <br />perforatiorxs^^ flow per <br />perf orat; <br />SC perfi <br />r <br />m^Ts^page E-17) <br />x>7ygWperf "7^. Cgpm <br />7. Select minrsiuiiL^equlrcd 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 />“ Inches " <br />G. Basal width <br />1. Percolation rate in top 12 <br />inches of soil is //. Q mpl <br />2. Select allowable soil loading <br />rate from table on page E-16; <br />use _gpd/ft^