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VA K.S <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 />C gpd <br />B. Septic Tank Liquid Volume <br />(see C-3 or C-5) ��_. , 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 />/ $ inches <br />3. Number of percolation test <br />holes; 3 holcq <br />4. Ave. percolation rat- <br />L12, Y '-,Pi <br />5. Landslope = 7 <br />D. Rock Layer Dimensions <br />1. Multiply gpd by 0.83 to <br />obtain required area of <br />rock layer; <br />K' gpd x 0.83 sq ft <br />2. Select width of rock layer <br />(10 feet or less) - /O feet <br />3. Length of rock layer a Area <br />- Width sq f t , p ft <br />ft <br />E. Rock Volume <br />1. `lultiply rock area by rock depth <br />to get cubic feet of rock; <br />Saa sq ft x / ft iSO0cu ft <br />2. Divide cu ft by 27 cu ft/cu yd <br />to get cubic yards; /.9. _,- <br />3. !Iultiply cubic yards by 1.4 to <br />get weight of -ock in tons; <br />/'.','.'cu yds x 1 .4 a 1v ' tons <br />F. Pressure Distribution System <br />1. Select number of perforated <br />laterals 6 <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 - 2T. S ft. <br />4. Divide lateral length by perfor- <br />ation spacing to get number of <br />perforations per lateral <br />!2, 5 feet 3_feet �_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 ;;et total 'number of <br />perforations; <br />yperf s/lat x _(�lats <br />6. Determine required flow rate <br />by multiplying number of <br />perforations by flow per %Y PfK:=i. <br />perforation (see page E-17) <br />J , perfs x.71/gpm/perf -.l 5gpm <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 />/ %/ " inches ".re I %2 " <br />G. Basal Width <br />1. Percolation rate in top 12 <br />inches of soil is ?2,�mpi <br />2. Select allowable coil loading <br />rate from table on page E-16; <br />4ef O. SO gpd/f t- <br />