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. . Ti,�i%� Fs" //�l.v:.S�.v; <br /> � �1 �'�.��,�G�,�f � �-�� <br /> MOUND D�SIGN PROCEDURE <br /> (For Flows up to 1200 gpd) <br /> , <br /> A. Sewage Flow Rate F. Pressure Distribution System <br /> See D-7 or I-3, 4, or 5, or use 1. Select nur.lber oL perforated <br /> metered value; Flow Rate = laterals c� <br /> �O O sPd <br /> 2. Select I�erforation s��acin�; <br /> B. Septic Tank Liquid Volume = .3 ft <br /> , (see C-3 or C-5) �QDO gallons <br /> 3. Select perforated lateral <br /> C. Soil Characteristics length; Note if manifold is <br /> � at end of rocic layer, lateral <br /> 1. Depth to restricting layer length is rock layer len�th <br /> such as seasonally saturated less half a perforation <br /> soil, bedrocl:, coarse soil, + spacing. If manifold is in <br /> etc. ; •..`�inches center of rock layer, lateral <br /> 2. Depth of percolation tests; length is one-half rock layer <br /> � /$ inches length less half a perforation <br /> spacing. Perforated lateral <br /> 3. Number of percolation test lengttl = 2.�, � f t. <br /> holes; • . ;�.6 holes 4. Divide lateral length by perfor- <br /> 4. Ave. percolation rate; ation. spacing to get number of <br /> S 9;��_. „�� mpi perforations per lateral <br /> � Z� S feet : ,3 feet = ,s� perfs <br /> 5. Landslope = �.7 % urF 7% Note: last perforation must be <br /> `_ D. Rock Layer Dimensions in end cap, (see pa�;e �-14) <br /> l. ttultiply gpd by 0.83 to 5 . Ttultiply perforations per <br /> obtain required area of lateral by number oF laterals <br /> rock layer; to g,et total numbcr oF <br /> perforations; <br /> 600 �pd x 0.83 =SOOsq ft � � perfs/lat x � lats = %,r <br /> 2. Select width of rock layer - <br /> (10 feet or less) _ /D .feet 6. Determine required flow rate <br /> by multiplyin� mnnber of „ <br /> 3. Len th of rock la er = Area . erforations b flo:� er � <br /> g Y P Y P �Y P�R�:' <br /> - Width�pOsq ft - �ft ' perforation (see page �-17) <br /> = SD ft ' ��perfs x ,7y�pm/perf =jS.S�;i�m <br /> E. Rock Volume 7. Select minimum required lateral <br /> • diameter from table on Pa�;e L-17; <br /> 1. Multiply rack area by zock depth enter table with perforation �- <br /> to get cubic feet, of rock; spacing, perforation diameter, <br /> s04 sq f t x / f t• =s40cu f t and number of perforations p�r � <br /> lateral. Select minimum <br /> . 2. Divide cu. ft by 27 cu ft/cu yd diameter for pertorated lateral <br /> to get cuk�ic•.,yards; /8 S - //•� " inches �fIE /yz�� <br /> 3. Multiply cubic yards by 1.4 to <br /> get weight of rock in tons; G. Basal jdidth <br /> ��J cu yds x 1.4 = �f, 9 tons 1. Percolation rate in top 12 <br /> inches of soil is.'.S 9 mpi <br /> 2. Select allowable soil. loadin�; <br /> _. rate from tab12 on page �-16; <br /> �,/,f�c �_gpd/f t <br />