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OSTP Pressure Distribution <br /> UNIVERSITY <br /> Minnesota Pollution Design Worksheet OF MINNESOTA „ _. ' <br /> Control Agency �!a - <br /> 1. Select Number of Perforated Laterals in system/zone: 3 �Jy ceote>mle I <br /> �!J ° MM EC►.r Minimum�O .►;i►°at <br /> (2 feet is minimum and 3 feet is maximum spacing) Q!,�G'/< perforations spaced 3'apart -1-ed 2'of rock S., x <br /> 2. Select Perforation Spacing: 3.0 ftp., <br /> Zi ♦! _• a !.. ►it r l► 9 of r9ck i a~►.J-,*„. ...,.1-,J ♦ �. ..�: 'o <br /> 3. Select Perforation Diameter Size 7/32 inch perforation sizing:'A"to'/: <br /> Perforation spacing:r to 3• <br /> 4. Length of Laterals =Media Bed Length-2 Feet. Perforation can not be closer then 1 foot from edge. v 11.05.31 <br /> 63 - 2ft = 61 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 = 61 ft 3 ft = 20 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 = 20 Spaces + 1 = 21 Perfs. Per Lateral <br /> Check table below to verify the number of perforations per lateral guarantees less than a 10%discharge variation. The value is <br /> double if the a center manifold is used. <br /> Maximum Number of Perforations Per Lateral to Guarantee r1096 Discharge Variation • <br /> '/a inch Perforations 7132 Inch Perforations 1 <br /> Perforation Spacing(Feet) Pipe Diameter(Inches) Perforation Spacing Pipe Diameter(inches) 1 <br /> 1 116 1% 2 3 (Feet) 1 156 112 2 3 <br /> 2 10 13 18 30 60 2 11 16 21 34 68 <br /> 21"- 8 12 16 28 54 21' 10 14 20 32 64 <br /> 3 8 12 16 25 52 3 9 14 19 30 60 <br /> 3/16 Inch Perforations 1/8 Inch Perforations <br /> Pipe Diameter(Inches) Perforation Spacing Pipe Diameter(Inches) <br /> Perforation Spacing(Feet) <br /> 1 116 11: 2 3 (Feet) 1 156 lis 2 3 <br /> 2 12 18 26 46 87 2 21 33 44 74149 <br /> 216 12 17 24 40 80 2st 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 /> 21 Perf. Per Lateral X 3 Number of Perf. Laterals = 63 Total Number of Perf. <br /> 8. Calculate the Square Feet per Perforation. Recommended value is 4-10 ft 2 per perforation. Perforation Discharge(GPM) <br /> Does nota i to At-Grades Perforation Diameter <br /> apply Head 00 1,, /, /1, <br /> Bed Area = Bed Width(ft)X Bed Length(ft) ,.w o..,e 0 0.56 0.74 <br /> 1.5 022 0..,.51 0.69 0.9 <br /> 10 ft x 63 ft = 630 ft2 2.0" 0.26 0.59 0.8a 1.04 <br /> 2.5 0.29 0.65 0.89 1.17 <br /> 3.0 0.32 0.72 0.98 1.28 <br /> Square Foot per Perforation =Bed Area divided by the Total Number of Perforations (Line 7). 4.0 0.37 0.83 1.13 1.47 <br /> 5.0' 0.4, 0.93 1.26 1.65 <br /> Dwellings <br /> 630 ft2 63 perforations = 10.0 ft2/perforations 'foot <br /> perfora ns[h 3/16 inch to I/4 inch <br /> Dwellings with 1/8 huh perforations <br /> 2 feet Other establishments and MSTS with 3/16 <br /> 9. Select Minimum Average Head: 1.0 ft inch to 1/4 inch perforations <br /> 5 reel Other establishments and MST5 with 1/8 inch <br /> perforations <br /> 10. Select Perforation Discharge (GPM)based on Table III: 0.56 GPM per Perforation <br /> 11. Determine required Flow Rate by multiplying the Total Number of Perforations (Line 7)by the Perforation Discharge (Line 10). <br /> 63 Perforations X 0.56 GPM per Perforation = 36 GPM <br />