and receiving pits. Continuous sliplining generally requires bypassing the existing flow. Storm culverts are often installed without bypass pumping. If the HDPE pipe has been butt welded, the external bead must be removed from the pipe, which is done with an 'external de-beader' tool. This provides a smooth exterior on the HDPE pipe, allowing it to pass through the existing pipe easily. Because the weld bead does not contribute any strength to the butt-welded join, removing it is no detriment to the strength or pressure rating of the pipeline. References Center for Underground Infrastructure Research and Education CUIRE Mohammed Najafi, PhD, PE and Sanjov Gokhale, PhD, PE, Trenchless Technology (New York: McGraw Hill, 2004), p. 295-311. Available from Water Environment Federation at http://www.e-wef.org/timssnet/static/OM/WPM404.htm Trenchless technology