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ERIE <br />TECHNICAL NOTE <br />Dual Wall HDPE Perforation Patterns <br />TN 1.01 <br />July 2007 <br />Introduction <br />Perforated pipe plays an integral role in many applications of HDPE pipe. Generally, perforated pipe is used to <br />accelerate the removal of subsurface water in soils or to allow storm water to percolate into the soil. Currently, <br />two classifications of perforations are specified in the AASHTO material specifications for HDPE pipe; Class I, <br />and Class II. Class I perforations are commonly used in combination storm/underdrain systems while Class II <br />incorporates subsurface drainage and detention/retention systems. Both classes are explained in more detail <br />in the AASHTO materials specifications (M294 and M252). AASHTO M252 covers pipe diameters 3- through <br />10 -inch (75 - 250 mm) while M294 covers 12 -inch through 60 -inch (300 - 1500 mm). <br />Standard Perforation Patterns <br />AASHTO Class II Perforation <br />The following terminology for perforations is derived from the applicable AASHTO specification. Differences <br />between the specifications are covered in Table I. The perforations shall be circular and/or slotted. The <br />perforations shall be located in the outside valleys of the corrugations. The water inlet area shall be no less <br />than 0.945 in2/ft (20 cm2/m) for pipe diameters 4- through 10 -inch (100 - 250mm), 1.42 in2/ft (30 cm2/m) for <br />pipe diameters 12- through 18 -inch (300 - 450 mm) and 1.89 in2/ft (40 cm2/m) for pipe diameters larger than <br />and equal to 24 inches (450 mm). Table 1 below represents ADS standard perforation patterns for AASHTO <br />Class II. Patterns indicated with an asterisk are a made to order product and should allow for additional lead- <br />time when ordering. <br />Nominal I.D. <br />Perforation <br />Type <br />Maximum Slot <br />Length or <br />Diameter <br />Maximum <br />Slot Width <br />Minimum <br />Inlet Area <br />in <br />mm <br />in <br />mm <br />in <br />mm <br />in2/ft <br />cm2/m <br />*4 <br />100 <br />Slot <br />0 875 <br />22 <br />0.125 <br />3 <br />1.0 <br />21 <br />*6 <br />150 <br />Slot <br />0.875 <br />22 <br />0.125 <br />3 <br />1.0 <br />21 <br />*8 <br />200 <br />Slot <br />1.18 <br />30 <br />0.125 <br />3 <br />1.0 <br />21 <br />*10 <br />250 <br />Slot <br />1.18 <br />30 <br />0125 <br />3 <br />10 <br />21 <br />12 <br />300 <br />Circular <br />0.313 <br />8 <br />- <br />- <br />1.5 <br />32 <br />15 <br />375 <br />Circular <br />0 313 <br />8 <br />- <br />- <br />1.5 <br />32 <br />18 <br />450 <br />Circular <br />0.313 <br />8 <br />- <br />- <br />15 <br />32 <br />24 <br />600 <br />Circular <br />0.313 <br />8 <br />- <br />- <br />2.0 <br />42 <br />30 <br />750 <br />Circular <br />0.375 <br />9.5 <br />- <br />- <br />2.0 <br />42 <br />36 <br />900 <br />Circular <br />0.375 <br />9.5 <br />- <br />- <br />2.0 <br />42 <br />42 <br />1050 <br />Circular <br />0.375 <br />9.5 <br />- <br />- <br />2.0 <br />42 <br />48 <br />1200 <br />Circular <br />0 375 <br />9.5 <br />- <br />- <br />2.0 <br />42 <br />54 <br />1350 <br />Circular <br />0.375 <br />9.5 <br />- <br />- <br />2.0 <br />42 <br />60 <br />1500 <br />Circular <br />0 375 <br />9 5 <br />- <br />- <br />2.0 <br />42 <br />Denotes perforation pattern made to order <br />4640 TRUEMAN BLVD. HILLIARD, OH 026 (800) 821-6710 - www.ads-pipe.com <br />1 <br />ATN101 9 CADS 2007 <br />