CONCRETE PIPE TYPE 5a ManholEs Manhole Material TYPE 5a ManholEs PREBENCHED BASE All newly built prebenched bases incorporate an engineered pipe to manhole connector. The boot-style gasket clamps onto the pipe, reducing infiltration PREBENCHED BASE and exfiltration. For profile pipe (i.e. All newly built prebenched bases ultra-rib, X2), a straight wall adaptor is incorporate an engineered pipe to recommended to maintain the integrity of manhole connector. The boot-style gasket the seal. onto the pipe, reducing infiltration clamps and exfiltration. For profile pipe (i.e. ultra-rib, X2), a straight wall adaptor is recommended to maintain the integrity of the seal. PAGE 22 LAFARGE PIPE eMANUAL