- A half round channel cast in the concrete in the bottom of a manhole to direct discharge when the flow is low.
- Concrete placed in horizontal steps on steeply sloping fill to prevent sliding.
- Concrete laid on the side slopes of drainage channels where the slopes are interrupted by manholes, etc.
- Concrete laid ina pipeline trench to provide firmer support.
- noun the layer of concrete in a manhole between the channels and the brickwork