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Uxivcxsirr cw A11xxflrtlin <br /> rr <br /> SITE <br /> Pressure Distribution Design ON <br /> SEWAGE <br /> Minnesota Pollution TREATMENT <br /> Worksheet PROGRAM <br /> Control Agency <br /> 1. Select Number of Perforated Laterals(2-3 foot spacing): GeotaWle Minimum <br /> ll�� y: rforations spaced 3'a rt 2"of rock <br /> 2. Select Perforation Spacing(< 9 ft 2/perforation): 3.0 ft 12" <br /> Note:Must use 1 feet for media filters 9"of rock <br /> in <br /> 3. Select Perforation Diameter I-finch Perforation sizing:'W to'14" <br /> J Perforation spacing:2'w 3' <br /> 4 Length of Laterals =Media Bed Length-2 Feet. Perforation can not be closer then 1 foot from edge. <br /> 55 eft = 53 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 = 53 ft i ift = 17 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 = 17 Spaces 1 = 18 <br /> Check Table I 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 X1096 Discharge Variation <br /> 1/4 Inch Holes 7/32 Inch Holes <br /> Perforation Pipe Diameter(Inches) Perforation Pipe Diameter(Inches) <br /> Spacing(Feet) 1 1Y4 1% 2 3 Spacing(Feet) 1 1'/4 1% 2 3 <br /> 2 10 13 18 30 60 2 11 16 21 34 68 <br /> 2% 8 12 16 28 54 2% 10 14 20 32 64 <br /> 3 1 8 12 16 25 52 3 9 14 19 30 60 <br /> 3/16 Inch Holes '/s Inch Holes <br /> Perforation Pipe Diameter(Inches) Perforation Pipe Diameter(Inches) <br /> Spacing(Feet) 1 1% 114 2 3 Spacing(Feet) 1 1Y4 1% 2 3 <br /> 2 12 18 26 46 87 2 21 33 44 74 149 <br /> 214 12 17 24 40 80 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 /> 18 Perf. Per Lateral X Number of Perf. Laterals = 54 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 55 ft = 550 fe <br /> 9. Square Foot per Perforation =Bed Area (Line 8)divided by the Total Number of Perforations (Line 7). <br /> 550 ft 54 perforations = 10.19 ft2/perforations <br /> Recommended value is 4-10 ft'per perforation. Does not apply to At-Grades <br /> CONTINUED ON NEXT PAGE <br />