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UplViitliY a Airnnrsor� <br /> Pressure Distribution Design <br /> Minnesota Pollution Worksheet ..,.. k A ' <br /> Control AgencyGeotextile <br /> 1. Select Number of Perforated Laterals(2-3 foot spacing): 3 ; p'r'„♦,,v., Minimum►v� ►'i o� <br /> '/. eratram 3 T' --12'of rock nt- ,,,;' <br /> 2. Select Perforation Spacing - <br /> (<9 ft2/perforation): 3.0 ft & >� fz• <br /> Note:Must use 2 feet for media filters , x a 1a, �a,l. 1a, T! 9 �! ,k Ttc. <br /> 3. Select Perforation Diameter 1/4 inch Perforation skimpµ 'le to y. <br /> Perforation spaaig 2'to 3' <br /> 4 Length of Laterals =Media Bed Length-2 Feet. Perforation can not be closer then 1 foot from edge. <br /> 50 - 2ft = 48 ft <br /> 5. Determine the Number of Perforation Spaces. Divide the Length of Laterals (Line 4)by the Perforation Spacing (Line 2)and <br /> round down to the nearest whole number. <br /> Number of Perforation Spaces = 48 ft ÷ 3 ft = 16 Spaces <br /> 6. Number of Perforations per Lateral is equal to 1.0 plus the Number of Perforation Spaces (Line 5). <br /> Perforations Per Lateral = 16 Spaces + 1 = 17 <br /> Check Table to ensure that the number of perforations per lateral guarantees less than a 10%discharge variation. <br /> Table I Maximum Number of Perforations Per Lateral to Guarantee 410%Discharge Variation <br /> '/4 inch Holes ''32 Inch Holes <br /> Perforation I Pipe Diameter(inches) Perforation Pipe Diameter(Inches) <br /> Spadng(Feet) 1 11 1/ 2 3 Spadng(Feet) 1 134 11/2 2 3 <br /> 2 10 13 18 30` 60 2 11 16 21 34_ 68 <br /> 23 8 12 16 28 54 21/2 10 14 20 32 64 <br /> 3 8 12 16 25'' 52 3 9 14 19 30 60 <br /> 3/u inch Holes '/e Inch Holes <br /> Perforation I Pipe Diameter(Inches) Perforation Pipe Diameter(Inches) <br /> Spacing(Feet) 1 11 11 2 3 Spacing(Feet) 1 11 1/ 2 3 <br /> 2 12 18 26 46 87 2 21 33 44 74 149 <br /> 2/ 12 17 24 40 80 21 20 30 41 69 135 <br /> 3 12 16 22 37 75 3 20 29 38 64 128 <br /> 7. Total Number of Perforations equals the Number of Perforations per Lateral (Lina 6)multiplied by the Number of <br /> Perforated Laterals (Line 1). <br /> 17 Perf.Per Lateral X 3 Number of Perf. Laterals = 51 Total Number of Perf. <br /> Calculate the Square Feet per Perforation <br /> 8. Bed Area = Bed Width(ft)X Bed Length(ft) <br /> 10 ft x 50 ft = 500 ft2 <br /> 9. Square Foot per Perforation =Bed Area (Line 8)divided by the Total Number of Perforations (Line 7). <br /> 500 ft2 ÷ 51 perforations = 9.80 ft2/perforations <br /> Recommended value is 4-10 ft2 per perforation. Does not apply to At-Grades <br /> CONTINUED ON NEXT PAGE <br />