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PRESSURE DISTRIBUTION SYSTEM Geotextile fabric <br /> 1. Select number of perforated laterals_&& Quarter inch perforations spa (9 3• 12 <br /> 2. Select perforation spacing= _ft 9"of rock <br /> Perf Sizing 3/16"-1/4" <br /> 3. Since perforations should not be placed closer than 1 foot to Perf Spacing 1.5'-5' <br /> the edge of the rock layer (see diagram),subtract 2 feet from <br /> the rock layer length. E-4: Maximum allowable number of 1/4-inch perforations <br /> per lateral to guarantee<10%discharge variation <br /> Rocklaver length <br /> -2 ft = ft perforation <br /> 4. Determine the number of spaces between perforations. spacing <br /> Divide the length (3)by perforation spacing (2) and round feet 1 inch 1.25 inch 1.5 inch 2.0 inch <br /> down to nearest whole number. <br /> 2.5 s 14 la 2e <br /> Perforation spacing= 40 ft_ 3 ft= ZO spaces 3.0 8 13 17 26 <br /> 5. Number of perforations is equal to one plus the number of 3.3 7 12 16 25 <br /> perforation spaces(4). Check figure E-4 to assure the number of 4.0 7 11 15 23 <br /> perforations per lateral guarantees <10% discharge variation. 5.0 6 10 14 22 <br /> ,ZO spaces + 1 = .Z'/ perforations/lateral E-6: Perforation Discharge in gpm <br /> 6. A. Total number of perforations = perforations per lateral (5) perforation diameter <br /> times number of laterals (1) head inches <br /> (feet) 1/8 3/16 7/32 114 <br /> Z� perfs/lat xlat= .3 perforations 1.00 0.18 0.42 0.56 0.74 <br /> B. Calculate the square footage per perforation. b <br /> Should be 6-10 sqft/perf. Does not apply to at-grades. 2.0 0.26 0.59 0.80 1.04 <br /> Rock bed area = rock width(ft) x rock length(ft) 5.0 0.41 0.94 1.26 1.65 <br /> J0ft x_4_ft= 6Z Z Sqft ° Use 1.0 foot for single-family homes. <br /> Square foot per perforation=Rock bed area-- number of perfs (6) b UFse 2.0 feet for anvthina else. <br /> C.2 Z sgft=-L..3-perfs=-?.8 sqft/perf MANIFOLD LOCATED AT END OF PRESSURE DISTRIBUTION SYSTEM <br /> 7. Determine required flow rate by multiplying the total number of <br /> perforations (6A) by flow per perforation(see figure E-6) <br /> perfs x_gpm/perfs =349' gpm <br /> 8. If laterals are connected to header pipe as shown on upper 1 <br /> example, to select minimum required lateral diameter;enter <br /> figure E-4 with perforation spacing(2) and number of perforations <br /> per lateral (5) Select minimum diameter for <br /> LAYOUT OF PERFORATED PIPE LATERALS MR <br /> perforated lateral=�Z inches. PRESSURE DISTRIBUTION W MOUND <br /> PCIYM..TD R.STIC.»< <br /> 9. If perforated lateral system is attached to manifold pipe near .,°N,,P.�,,.. ,,� �` <br /> the center,lower diagram,perforated lateral length (3) and ~ 'WEE 0. Al K V.' "rua.- <br /> number of perforations per lateral 5 will be approximately one ...°..TI ON BOT,W P. <br /> P P ( ) PP Y ...,TIPI.. <br /> half of that in step 8. Using these values,select minimum <br /> diameter for perforated lateral= inches. _C..�b. --� <br /> "WA <br /> F,pprcO \"I 111E..oM <br /> STN <br /> LE <br /> I hereb certify that I have completed this work in accordance with applicable ordinances, rules and laws. <br /> �� (signature) 43 (license#) (date) <br />