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CHAPTER 6
Project Considerations
for Pipe Replacement
Methods
6.1 Introduction
Existing sewer, water, and natural gas pipes can be replaced by three
basic methods of pipe bursting—pneumatic, hydraulic, and static
pull. In addition, there are proprietary trenchless pipe replacement
systems that incorporate significant modifications to the basic pipe-
bursting technique, including pipe reaming, the impactor method,
and pipe extraction (also called pipe insertion). Pipe reaming is the
most common method of pipe removal, where the broken pieces of the
existing pipe are actually taken out of the ground with the use of
slurry drilling fluids (see Sec. 6.3.1). The basic difference among these
systems is in the source of energy, the method of breaking the existing
pipe and some consequent differences in construction operations that
are briefly described in the following sections. The selection of a spe-
cific replacement method depends on soil conditions, groundwater
conditions, degree of upsizing required, type of new pipe, original
construction of the existing pipeline, depth of the pipeline, avail-
ability of experienced contractors, and the like.
6.2 Pipe Bursting
Pipe bursting was first developed in the United Kingdom in the
late 1970s by D. J. Ryan & Sons in conjunction with British Gas, for
the replacement of small-diameter, 3- and 4-in. cast-iron gas
mains (Howell, 1995). The process involved a pneumatically driven,
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