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. , . .2'. .7'./�oB„t Gct�J7' NauS'E` .. . . . � <br /> � , ' -� �'fOR o0� E-19 � <br /> MOUND DESIGN PROCEAURE <br /> (For Flows up to 1200 gpd) ••• <br /> � .. . , , <br /> A. Sewage Flow Rate � ' E`. Pressure Distribu'tion''System <br /> See D-7 or I-3, 4, or 5, or use <br /> metered value; Flow Rate = � 1• sel�ct' number of perforated . �� <br /> yS 0 gPd laterals 6 <br /> B. Septic Tank Liquid Volume 2• 3elect perforation spacin� <br /> (see C-3 or C-5) /000 gallons - �---f t - <br /> 3. Select perforated lateral .. <br /> � C. Soil Characteristics length; Note if manifold is <br /> l. Depth to restricting layer at end of rock layer, lateral <br /> such as seasonally saturated length is rock layer l.en�th <br /> soil, bedrock, coarse soil, less half a perforation <br /> � � spacing, If inanifold is in <br /> etc. ; S� inches Eenter of roektlayer, lateral � <br /> �..�_— <br /> 2. Depth of percolation tests;, length is one=half rock layer <br /> /� inches ' length less half a perforation <br /> 3. Number of percolation test sPacing. Perforated lateral <br /> length = / , 2,5 f t. <br /> holes; �'y holes /A/�y,tKy ,S/T� .° .. <br /> 4. Divt�� ]:aC�r�l l�ng'th by perfor- ' <br /> 4. Ave, percolation rate; ation spacing to..get number of <br /> ZO. 6 mpi perforations per lateral <br /> 5. Landslope. = 2 x /7.25 feet : _�feet = �, perfs <br /> Note: last perforation must be <br /> _ D. Rock Layer Dimensions' in end cap, (see page E-14) <br /> 1. Multiply gpd by 0.83 to ,,5• Multiply perforations per - <br /> obtain required area of late.ral. .b.y.•number� of laterals <br /> rbck layer; to g;et total number of <br /> S/SD gpd x 0.83 � ,�7Ssq ft perforations; � <br /> 6 perfs/lat x ( lats = ;36 <br /> 2. Select width of rock layer <br /> (10 feet or less) __ /D feet 6. Determine required flow rate <br /> by multiplying number of � <br /> 3. Length of rock layer = Area perforations by fTow per �y yPF�f�;; <br /> � Wid th 37S sq f t - /p f t ' erf ora tion <br /> _ ,�7. 5 f t p , (see page E-17�: , <br /> ��perf s x ,7�gpm/perf =26,(gpm � <br /> E. Rock Volume 7. Select minimum required lateral <br /> diameter from table on Page E-17; <br /> 1. Multiply rock area by rock depth enter table with perforation � <br /> to get cubic feet. of rock; spacing, pe:foration diameter, <br /> 37 S sq f t x / ft = ,�75 cu�f t and number of perforations per <br /> 2. Divide cu ft by 27 cu ft/cu yd lateral. Select minimum <br /> to get cubic yards; /,3, 9 . dianieter for perforated l.ateral <br /> _ �inc'hes � ' ' � <br /> 3. Multiply cubic yards by 1.4 to <br /> get weight of rock in tons; ' G. Basal WY.dth • <br /> /�,9 cu yas x 1.4 � /9.Y tona l. Percdiatiore zate �in top 12 � <br /> . inches o.f soil is ZO. (mpi <br /> 2. Select allowable soil loading <br /> ` rate from table on pa�e F.-16; <br /> O. �O �pd/f t2 . <br />