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� ''Unive'rsity of Minnesota Pressure Distribution System Design - 10/25/04 All boxed rectangles must be entered,the rest will be calculated. Oas�re 8ewiwe 1. Select number of perforated laterals: 05 TRlATMC4(T �' PROORAM � 2. Select perforation spacing= �ft „�.- �.,�„ ._..._...__....._._.__.__--__._ ----- -- 3. Since perforations should not be placed closer that 1 foot to ��„„„m,_;;-;;�-,„,,,,,,�„_,�;,,-��.�,-_ the edge of the rock layer(see diagram),subtract 2 feet from 1 ��.,k the rock layer len th � ,�, " `Y,., 47 -2 ft= 45 ft ,�..��:,....,,,,;�;_, 4. Determine the number of spaces between perforations. Divide the length(3)by perforation spacing(2)and round down to nearest whole number. Perforation spacing= 45 ft/ 3 ft= 15 5. Select perforation size 7/32 inch 6. Number of perforations is equal to one plus the number of perforation spaces(4). *Check figure E-4 to assure the number of perforations per lateral guarantees < 10%discharge variation. 15 spaces+ 1 = 16 perforations/lateral E11 Maximum Number of 1/4 inch perforations E-5 Maximum Number of 3N6 inch perforations er lateral to uarantee<10%dischar e variation er lateral to uarantee<10%dischar e variation Perforation Perforation Spacing Pipe Diameter Spacing Pipe Diameter ft 1 inch 1.25 inch 1.5 inch 2.0 inch feet 1 inch 1.25 inch 1.5 inch 2.0 inch 2.5 8 14 18 28 2.5 12 19 25 39 3.0 8 13 17 26 3 11 18 24 37 3.3 7 12 16 25 3.3 10 17 23 36 4.0 7 11 15 23 4 10 16 21 33 5.0 6 10 14 22 5 9 15 20 31 7. A.Total number of perforations=perforations per lateral(5)times number of laterals(1). 16 perfs/lat x 5 laterals= 80 perforations B.Calculate the square footage per perforation. Recommended value is 6-10 sqft/perf.Does not apply to at-grades. 1. Rock bed area=rock width(ft)x rock length(ft) 16 ft x 47 ft= 752 ft2 2. Square foot per perforation=Rock Bed Area/number of perfs(6) 752.0 ft2 / 80 perfs = 9.4 ft/perf 8. Determine required flow rate by multiplying the total number of perforations(6A)by flow per perforations see figure E-6) 80 perfs x 0.56 gpm/perfs= 44.8 gpm E-6 Perforation Discharge in GPM Head Perforations diameter feet inches 3/16 7/32 1/4 1 0.42 0.56 0.74 2° 0.59 0.80 1.04 5 0.94 1.26 1.65 a. Use 1.0 foot for single-family homes. b.Use 2.0 feet for anything else , . '`/ 9. Determine Minimum Pipe Size . A. Manifold on End. If laterals are connected to header pipe , as shown in Figure E-1,to select minimum required lateral HgureE-I ManifoldLoca�edafEntlof3y�tem diameter;enter figure E-4 or E-5 with perforation spacing and number of perforations per lateral.Select minimum diameter for perforated laterals= 1.5 inches B. Center Manifold. If perforated lateral system is attached to F�q�..E-z M°^�,°�a°N° i IM Gnl�r o11M Sy�1�m � manifold pipe near the center,like Figure E-2,perforated lateral length(3) . _ � I and number of perforations per Iateral(5)will be approximately ' one half of that in step A. Using these values,select � , � I�I minimum diameter for perforated lateral= 0 inches • `Z-- ,�� I hereby certify that I ave completed this work in accordance with all applicable ordinances,rules and laws. (signature)_1�(license#) /O-LS 7d �date)