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IMIYEtSffYW MtR'K69pf. <br /> Pressure Distribution Design - - <br /> Minnesota Pollution Worksheet 7 <br /> Control Agency <br /> 1. Select Number of Perforated Laterals(2-3 foot spacing) <br /> m <br /> 3• 2•of rods <br /> 2. Select Perforation Spacing(<9 ft !perforation) <br /> Note:Must use 2 feet for media filters 9•ofrodc <br /> 3. Select Perforation Diameter 1/4 inch <br /> Pafaa9on ,ti.to'A" <br /> Pubradon qmft 2-a 3- <br /> 4 Length of Laterals =Media Bed Length-2 Feet. Perforation can not be closer then 1 foot from edge. <br /> 38 - 2ft = 36 it <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 = 36 ft ft = 12 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 = 12 Spaces + 1 13 <br /> Check Table I to ensure that the number of perforations per lateral guarantees less than a 1OX disdfarge variation. <br /> Table 1 Mwdmum Number of Perforations Per Lateral to Guarantee 0096 Discharge Variation <br /> '/,indi Holes 71"Inch doles <br /> Perforation Pipe Diameter(inches) Perforation Pipe Diameter(Inches) <br /> Spacing(Feet) 1 1% 1% 2 3 Spacing(Feet) 1 1% 1% 2 3 <br /> 2 10 13 18 30 6.0 2 11 16 21 34 68 <br /> 2% 8 12 16 28 54 2% 10 14 20 32 64 <br /> 3 a 12 16 25 52 3 9 14 19 30 60 <br /> 3/,s inch Holes '/s inch Holes <br /> Perforation Pipe Diameter(Inches) Perforation Pipe Diameter(Indies) <br /> Spacing(Feet) 1 134 1% 2 3 Spacing(Feet) 1 1% 1% 2 3 <br /> 2 12 i8 26 46 87 2 21 33 44 74 149 <br /> 23A 12 17 24 40 8o 2% 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 (Line 6)multiplied by the Number of <br /> Perforated Laterals (Line 1). <br /> 13 Perf.Per Lateral xNumber of Perf. Laterals = 39 Total umber of Perf. <br /> Calculate the Square Feet per Perforation <br /> 8. Bed Area = Bed Width(ft)X Bed Length(ft) <br /> 10 <br /> it x 38 ft = 380 fe <br /> 9. Square Foot per Perforation =Bed Area (Line 8)divided by the Total Number of Perforations (Line 7). <br /> 380 ft2 a 39 perforations = 9.74 fe/perforations <br /> Recomriended value is 4-10 ft2 per perforation. Does not apply to At-Grades <br /> CONTINUED ON NEXT PAGE <br />