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w . PRESSURE DISTRIBUTION SYSTEM Geotextile fabric ' 1. Select number of perforated laterals � uarter�inch erfotahons s aced�^3 12 �" _ � � ^ 2. Select perforation spacing = � ft ::, ... ,? ' ; ��:of,�o�lr. , ;': �; ,. , . , , Perf Sizing 3/16"-1/4" 3. Since perforations should not be placed closer than 1 foot to Perf Spacing 1.5•-s' the edge of the rock layer (see diagram),subtract 2 feet from the rock layer length. E-4: Maximum aUowable number of 1/4-inch perforations �� per lateral to guarantee<10%discharge variafion Rock layer length -2 ft = � ft Af�OfOf10fl P 4. Determine the number of spaces between perforations. spacing feet 1 inch 1.25 inch 1.5 inch 2.0 inch Divide the length (3) by perforation spacing (2) and round down to nearest whole number. 2.5 8 14 18 28 Perforation spacing= S�es ft= 3 ft= � spaces 3.0 8 13 17 26 5. Number of perforarions is equal to one plus the number of 3.3 7 12 16 25 perforarion spaces(4). Check figure E-4 to assure the number of 4'0 7 11 15 23 perforations per lateral guarantees <IO% discharge variation. 5.0 6 10 14 22 � spaces + 1 = �-I perforations/lateral E-6: Perforation Dischorge in gpm 6. A. Total number of perforations = perforations per lateral (5) perforation diameter times number of laterals (1) head inches (feet� ��8 3/16 7/32 1/4 �-1 perfs/lat x 3 lat= �.� perforations 1.0a 0.18 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 0.26 0.59 0.80 1.04 Rock bed area = rock width (ft) x rock length (ft) 5.0 0.41 0.94 1.26 1.65 �Q_ft X j� ft=�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 onvthin eise. � sqft=_�perfs = 9.S sqft/perf i. Determine required flow rate by multiplying the total number of � „�,; � perforations (6A) by flow per perforation (see figure E-6) � a�r�„o�,� I <'o� � perfs x � 79�,apm/perfs =�gpm e,�� I � 8. IE laterals are connected to header pipe as shown on upper � �..• example,to select minimum required lateral diameter; enter j o G�fe,,�,� figure E-4 with perforation spacing (2) and number of perforations Figure E•1:Manitold located at End of System per lateral (5) Select minimum diameter for perforated lateral = �- inches. �igure E-2:Manifold locofed ,e"0C0p in the Center of the System 9. If perforated lateral system is attached to manifold pipe near the center,lower diagram,perforated lateral length (3) and �robp� number of perforations per lateral (5)will be approximately one half of that in step 8. Using these values, select minimum diameter for perforated lateral= inches. arc�e�,o 0 ppe irom amw I hereb certify that I hav co 'pleted this work in accordance with applicable ordinances, rules and laws. �d��``'� si ature � � license# �o � � ��'� date � � ) --,-� ) � )