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PRESSURE DISTRIBUTION SYSTEM Geotextile fabric 1. Select number of perforated laterals � Quarter Inch perforations spaced C 3• u .12,'. . • • °Crock 2. Select perforation spacing= 3 ft Perf Sizing 3/16"-1/4" 3. Since perforations should not be.placed closer than 1 foot to Perf Spacing 1.5•-5• the edge of the rock layer(see diagram),subtract 2 feet from the rock layer length. E-4: Maximum allowable number of 1/4-Inch perforation per lateral to guarantee<10%discharge variation RD hyZ��Rg�, -2 ft = L O ft perforation .spacing 4. Determine the number of spaces between perforations. Divide the length(3)by perforation spacing(2)and round (feet) 1 inch 1.25 inch 1.5 Inch 2.0 inch down to nearest whole number.. 2.5 8 14 18 28 Perforation spacing= coo ft+ 3 ft= Q o spaces 3,0 8 13 17 26 5. Number of perforations is equal to one plus the number of 3.3 1 12 16 25 perforation spaces(4)..Check figure E-4 to assure the number of 4.0 7 11 15 23 perforations per lateral guarantees<10%discharge variation. 5.0 6 10 14 22 ao spaces + 1 = D ) perforations/lateral E-6: Perforation Discharge in gpm 6. A. Total number of perforations= perforations per lateral (5) perforation diameter times number of laterals (1) head Inches) `1 `' (feet) 3/16 7/32 1/4 a. 1 erfs/lat x '1 lat= t.;� erforations p p 1.00 0.42 0.56 0.74 B. Calculate the square footage per perforation. b Should be 6-10 sqft/perf. Does not apply to at-grades. 2.0 0.59 0.80 1.04 Rock bed area= rock width (ft)x rock length(ft) 5.0 0.94 1.26 1.65 10 ft x !,Z ft= co-zo sqft • a use 1.0 foot for single-family homes. Square foot per perforation=Rock bed area+number of perfs (6) b Use 2.0 feet for onythina else. (oma sqft+ (-,*1 perfs= 9.cl sqft/perf . MANIFOLD LOCATED AT CND OF PRESSURE DISTRIBUTION STSTEI 7. Determine required flow rate by multiplying the total number of perforations (6A) by flow per perforation(see figure E-6) W":[•' 3 ' perfs x 9 gpm/pe fs= 9 7 gpm `� _ 8. If laterals are connected to header pipe as shown on upper ,,,,,' example,to select minimum required lateral diameter;enter ..ev'm ' " figure E-4 with perforation spacing(2) and number of perforations \�"0M per lateral(5) Select minimum diameter for LJIYO.tT O/KMMUTIO•Mt LATERALS roe perforated lateral= inches. MIClMAC DI+TI1DDtION A MOUND ttIAMMm Mt C M tt 9. If perforated lateral system is attached to manifold pipe near �KMtMnM :.-• �` the center,lower diagram,.perforated lateral length(3) andz"'�'`�' " Yr�as number of perforations per lateral (5)will be approximately one `.t.T;ri�;t.,�M.. - -.. half of that in step 8. Using these values,select minimum •� -• - .-Ia, diameter for perforated lateral= J`t Z- inches. !t✓ I hereby certify that have co)npleted this work in accordance with applicable ordinances, rules and laws.