초록 ▼

An extension collar suitable for engagement with an upper ledge of an invert liner positioned within the canal bed of the base of a manhole or catch basin structure. The extension collar is replaceable and is suitable for use in either new construction or rehabilitation of the manhole structure. A p

An extension collar suitable for engagement with an upper ledge of an invert liner positioned within the canal bed of the base of a manhole or catch basin structure. The extension collar is replaceable and is suitable for use in either new construction or rehabilitation of the manhole structure. A plurality of extension collars may be sealably stacked one on top of the other to create a corrosion resistant barrier at a desired height from the bottom of the base of the manhole or catch basin.

대표청구항 ▼

[What is claimed is:] [1.](a) an annular center section shaped to fit within said manhole structure, said center section having inner and outer concentric sides and an opening extending between an upper portion and lower portion of the center section, wherein a diameter of the outer concentric side

[What is claimed is:] [1.](a) an annular center section shaped to fit within said manhole structure, said center section having inner and outer concentric sides and an opening extending between an upper portion and lower portion of the center section, wherein a diameter of the outer concentric side is less than an inner diameter of said base of said manhole structure;(b) an upper ledge extending outwardly from the upper portion of said center section; and(c) a lower ledge extending outwardly from the lower portion of said center section, wherein said upper ledge is adapted for receiving a lower ledge of a similar extension collar positioned in stacked relation to said extension collar.