introduCtion Buoyancy The density of concrete is approximately 2.4 times that of water, but there are several installation conditions where the possibility of pipe flotation exists. Some of these conditions are: flooding to consolidate backfill; pipelines in areas which will be inundated, such as a flood plain or under a future man-made lake; subaqueous pipelines; and pipelines in areas with a high groundwater table. When such conditions exist, flotation probability should be determined. The buoyancy of a concrete pipeline depends upon the weight of the pipe, the weight of the volume of water displaced by the pipe, the weight of the liquid load carried by the pipe, and the weight of the backfill. As a conservative analytical practice, the line can be considered empty so the weight of any future liquid load is then an additional safety factor. ConCrete pipe stormwater treatment teChnologies box seCtions manhole and CatCh basin material LAFARGE PIPE eMANUAL PAGE 55