What Does Manhole Chimney Mean?
A manhole chimney is defined as the assembly of components that connect the vertical manhole barrel section to the casting frame that supports the manhole lid at an elevation that is considerably level with the top layer of the surrounding road pavement.
The chimney usually consists of a concentric or eccentric conical concrete section that extends upward from the manhole barrel and one or more concrete adjusting rings that are used to adjust the overall elevation of the manhole.
Trenchlesspedia Explains Manhole Chimney
The upper portion of the manhole (which consists of the manhole chimney) is considered to be the weakest part of the manhole structure. Increased traffic loading over time, freeze and thaw cycles, impact loading, and deteriorated construction materials contribute to the degradation of the manhole chimney sections. This ultimately leads to the infiltration of water and soil between openings in the adjustment rings and can lead to manhole structural failure, settlement and cracking of the surrounding road pavement.
Common methods of repairing and rehabilitating manhole chimneys include:
- Cured-in-place (CIP) liners or sleeves
- Internal and external chimney seals
- Internal joint seals
- External joint wraps
- Lid gaskets and
- Lid plugs