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oWo►iF.S 40'*B6,vvFrr �t'FrioF.�-cF� <br /> r -rriGr, -ax 7 ecox, ''�S E-19 <br /> MOUND DESIGN PROCEDURE <br /> (For Flows up to 1200 gpd) F_Ot3i N <br /> A. Sewage Flow Rate F. Pressure Distribution System <br /> See D-7 or I-3, 4, or 5, or use 1. Select number of perforated <br /> metered value; Flow Rate.= l6 <br /> 12 00 gpd laterals <br /> 2. Select perforation spacing <br /> B. Septic Tank Liquid Volume = 3 ft <br /> (see C-3 or C-5) gallons <br /> 3. Select perforated lateral <br /> C. Soil Characteristics length; Note if manifold is <br /> at end of rock layer, lateral <br /> 1. Depth to restricting layer length is rock layer length <br /> such as seasonally saturated less half a perforation <br /> soil, bedrock, coarse soil, spacing. If manifold is in <br /> etc. ; 2 Lf_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 length = ,3 6 ft.SOarqlo� 6'/ 'tioK-,v <br /> holes; S holes 4. Divide lateral length by perPor- <br /> 4 . Ave. percolation rate; ation spacing to get number of <br /> /2 . 6 mpi perforations per lateral <br /> 5. Landslope = 7 % 4yxx 4T P. FNS S feet -. 3 feet = /2 perf s f0#71/ <br /> Note: last perforation mu s)t be <br /> D. Rock Layer Dimensions' in end � 2-1/ <br /> p, (see page R4 <br /> NO <br /> OC2. S <br /> 1. Multiply gpd by 0.83 to 5. Multiply perforations per <br /> obtain required area of lateral by number of laterals <br /> rock layer; to get total number of <br /> /2 O O gpd x 0.83 =/DOOsq ft perforations; <br /> /2 perfs/lat x 3 Tats = 36 Jour.S/ <br /> 2. Select width of rock layerZ/ 'I = "RrN <br /> (10 feet or less) /O feet 6. Aetermine required flow rate <br /> by multiplying number of <br /> 3. Length of rock layer = Area perforations by flow per �t?2 �i <br /> = <br /> Width/,,14949 sq f t /O f t perforation (see page E-17) <br /> _ '/00 ft 2',r perfs xO,S6gpm/perf = '55gpm <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, perforation diameter, <br /> 14/00 sq f t x ./, Q f t =t49490cu f t and number of perforations per <br /> 2. Divide cu ft by 27 cu ft/cu yd <br /> lateral. Select minimum <br /> diameter for perforated lateral <br /> to get cubic yards; 37, = . 2 inches 5W,*6 .-r 4f/roRF <br /> 3. Multiply cubic yards by 1.4 to <br /> get weight of rock in tons; G. Basal Width <br /> ,37. Ocu yds x 1.4 - t/. Ptons 1. Percolation rate in top 12 <br /> inches of soil is /2. 7 inpi <br /> 2. Select allowable soil loading <br /> rate from table on page E-16; <br /> G/�F 0, 50 gpd/ft2 <br />