A standpipe is a pipe that extends vertically from a building drain to increase the water level in case of a basement flood. Soil stacks are often used as standpipes.
A standpipe does not need to be more than 18 inches off the floor for it to work. Soil stacks are open at the top, which means gases from the sewer may smell bad if they escape into living areas through an open soil stack or around loose-fitting joints.
Inspection is fairly straightforward and only requires looking at connections and clearances from obstructions such as foundation walls, insulation, ducts, pipes and other equipment mounted on ceiling joists or roof rafters.