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' PRESSURE DISTRIBUTION SYSTEM Geotextile fabric 1. Select number of perforated laterals 3 1 Quarter inch perforations spaced a 3' 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 perforations 5 -2 ft = S3 ft per lateral to guarantee<10%discharge variation Rock layer length perforation 4. Determine the number of spaces between perforations. spacing 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= 4-3 ft+ 3 ft= Y') ,spaces 3.0 8 13 17 26 5. Number of perforations is equal to one plus the number of 3.3 7 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 I') spaces+1 = )cd 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) si perfs/let x 3 let= Sti perforations (feet) 3/16 7/32 1/4 1.00 0.42 0.56 0.74 B. Calculate the square footage per perforation. Should be 6-10 sqft/perf.Does not apply to at-grades. 2.Ob 0.59 0.80 1.04 Rock bed area = rock width(ft)x rock length(ft) 5.0 0.94 1.26 1.65 o ft x Ss'. ft= SSa sqft 0 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 cnythinsl else. SS 0 sqft+ 5y_perfs= /0•-4- sqft/perf L etercko LOCATED AT END or mum oISTammos SYSTEM 7. Determine required flow rate by multiplying the total number of perforations (6A) by flow per perforation(see figure E-6) Sy perfs x .r)y gpm/perfs= 40 gpm /VC Mom 8. If laterals are connected to header pipe as shown on upper •.. example,to select minimum required lateral diameter;enter Pr"-_...,..0""‘ " "� figure E-4 with perforation spacing(2)and number of perforations \,.- d per lateral(5) Select minimum diameter for perforated lateral= inches. "`DVPRE MME a..RO°„ra.E,LATERALS FOR 9. If perforated lateral system is attached to manifold pipe near CE .sWwm PLASM..c the center,lower diagram,perforated lateral length(3)and Ju"'`l . 'VP.M"'°"M° Mhn number of perforations per lateral(5)will be approximately one . ;�r•.a....�.... ^ .n half of that in step 8. Using these values,select minimum '- diameter for perforated lateral= )`z-inches. "P' ''U? ..w a • • I hereby certify that I have completed this work in accordance with applicable ordinances, rules and laws. - -- 61 , a (signature) 3',ti (license#) 4!-1'3-v / (date)