Grade (pitch)

The elevation of a surface or a surface slope. The elevation of the invert of the bottom of a pipeline, canal, culvert, or conduit. The fall (slope) of a line of pipe in reference to a horizontal plane. The inclination or slope of a pipeline, conduit, stream channel, or natural ground surface; usually expressed in terms of the ratio or percentage of number of units of vertical rise or fall per unit of horizontal distance (rise over run).