CONCRETE PIPE Prebenched Manholes The Calgary Pipe Operation is unique in its prebenched manhole configuration, as it is the only facility in Western Canada that has an octagonal base and is manufactured entirely with wetcast concrete. G F H E A D C B Due to the octagonal shape, each face is located at a 45 degree angle, which forces all openings to be provided at these angles only. Other angles are accommodated through either flexibility in the pipe connection (i.e. within 10 degrees of the 45 degree face) or an oversized opening. Stock prebenched based are generally available for dead end and straight through configurations, including all pipe sizes (i.e. 100, 150, 200, 250, 300, 375, 450, 525, 600 mm diameter) and types (i.e. plastic or concrete). Notes: • • • Maximum pipe opening for a standard 813 mm high prebenched base is 525 mm diameter. An extended 1110 mm high prebenched base is available for 600 mm diameter pipes. Beyond 600 mm diameter pipes, a Type 1-S manhole is required. Minimum 90 degrees permitted between 600 mm pipes. Prebenched manhole bases come complete with circular cast in rubber gaskets for SDR 35 pipe, except in the case of an oversized opening. PAGE 24 LAFARGE PIPE eMANUAL