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PRESSURE DISTRIBUTION SYSTEM Geotextile fabric <br /> 1. Select number of perforated laterals 12 <br /> Quarter inch perforations spaced @ 3' <br /> 9"of rock <br /> 2. Select perforation spacing = 3 _ft <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 /> 38 / per lateral to guarantee<10%discharge variation <br /> Rock layer length -2 f t = 3( f t perforation <br /> spacing <br /> 4. Determine the number of spaces between perforations. (feet) 1 inch 1.25 inch 1.5 inch 2.0 inch <br /> Divide the length (3)by perforation spacing(2) and round <br /> down to nearest whole number. <br /> 2.5 8 14 18 28 <br /> Perforation spacing= 36. ft_ 3 ft= /a 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 /> 4.0 7 11 15 23 <br /> perforation spaces(4). Check figure E-4 to assure the number of 5.0 6 10 14 22 <br /> perforations per lateral guarantees <10% discharge variation. <br /> 1e- spaces + 1 = 13 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) 3/16 7/32 1/4 <br /> i3 perfs/lat x 3 lat= 39 perforations <br /> 1.00 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 0.59 0.80 1.04 <br /> Rock bed area = rock width (ft) x rock length(ft) 5.0 0.94 1.26 1.65 <br /> /0 ft x 38- ft = 360 sqft ° Use 1.0 foot for single-family homes. <br /> Square foot per perforation = Rock bedaarea _number of perfs (6) b Use 2.0 feet for anything else. <br /> 3 e v sqft T 3 perfs = /(/ sqft/perf MANIFOLD LOCATED AT END cc PRESSURE C4STRIeUTION 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 /> 31 perfs x . 74' gpm/perfs = a 9 gpm <br /> 8. If laterals are connected to header pipe as shown on upper _.--- <br /> ' ::� <br /> example, to select minimum required lateral diameter;enter --- ,�- 5' <br /> figure E-4 with perforation spacing (2) and number of perforations \�``� <br /> per lateral (5) Select minimum diameter for <br /> LAYOUT OE PERFORTED PIPE LATERALS TOR <br /> perforated lateral = I,‘).s- inches.��YY��S//..11EE��ies. PRESSURE DISTRIBUTION PI r.wwD <br /> c�{{ ER..P.T.o.,.,TK <br /> 9. If perforated lateral system is attached to manifold pipe near `LT„-, . . <br /> the center, lower diagram,perforated lateral length (3) and "ro '„n;.`"�"�" "�`�� <br /> V 4•1340k 0 <br /> number of perforations per lateral (5) will be approximately one KR.m;;a.,,;.,.DT,R..a , <br /> half of that in step 8. Using these values, select minimum op. <br /> diameter for perforated lateral = 1, 0 inches. <br /> -<..D c.r b• Pµ <br /> T� <br /> m <br /> d <br /> I hereby certify that I have completed this work in accordance with applicable ordinances, rules and laws. <br /> f <br /> 7:;,/��"L ' Z-- (signature) �/O (license #) /o ..)--4/ (date) <br />