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PRESSURE DISTRIBUTION SYSTEM Geotextile fabric er of perforated lateralsuarter inch erforations s acc a fel 3' 1` :select perforation spacing = _ft of rock Pert Sizing 3/16"-1/4" .. ince perforations should noE be laced closer than 1 foot to Perf Spacing, 1.5'-5' P p I.lie edge of the rock layer (see diagram),subtract 2 feet from i he rock layer length. E-4: Maximum ailowable number of 1/4-inch perforations 37 -2 ft = � ft per lateral to guarantee 40%discharge variation Rock layer length perforation 31 - 2- 36- spacing 4. Determine the number of spaces between perforations. feet 1 inch 1.25 inch 1.5 inch 2.0 inch i)ivide the length(3)by perforation spacing(2) and round down to nearest whole number. ----- 2.5 8 14 18 28 Perforation spacing= 55 ft_ 3 ft = 2 spaces 3.0 8 13 17 26 4po 3.3 7 12 16 25 Number of perforations is o11,e plus the nber of 4.0 7 11 15 23 perforation spaees(4). Check figure E-4 to assure the number of 5.0 6 10 1 14 1 22 perforations per lateral guarantees <10% discharge variation. spaces+ 1 = perforations/lateral E-6: Perforation Discharge in gpm 6. A. Total�mber of perfora ions= perforations per lateral(5) perforation diameter tines number of laterals (1) head inches (feet) 3/16 7/32 1/4 perfs/gat x 3 lafi= perforations 1,0a .42 0.56 0.74 I . Calcis e square footage per perf 2.0b 0.59 0.80 1.04 Recommeded value is 6-10 sqft/perf. Does not apply to at-grades. 4 , Crock bed area = rock width(ft) x rock length(ft) 5.0 0.94 1.26 1.65 ft x ft= sgft °Use 1.0 foot for single famlly homes. Square foot per perforation= Rock bed area+number of perfs (6) b Use 2.0 feet for anythingelse. __ _sgft_ perfs= sgft/perf . Determine required flow rate by multiplying the total number of perforations (6A) by flow per perforation(see figure E-6) n�wpwfw /moi:%! ✓ {Vo flan P—P Emu 3 erfs x gpm/perfs= m If lilt ra s ar conn o header pipe a upperofaf�, Of P4� hon,P—P example, to select minimum required lateral diameter;enter Figure E-1:Manifold Located at End of System figure E-4 with perforation spacing(2) and number of perforations -- per lateral (5) Select minimum diameter for perforated lateral= inches. F' a E-2:Mangold Located �1. if perforated lateral system is attached to manifold pipe near h center of the SysteFn the center,lower diagram,perforated lateral length(3) and - number of perforations per lateral (5) will be approximately one # tllwinfa brofha half of that in step 8. Using these values,select minimum �= ofd,„h�n,,,,, diameter for perforated lateral= inches. ' ! P"I x I hereby certify that I�haavve completed this work in accordance with applicable ordinances, rules and laws. 1/ ` (signature) (license#) (date)