Buderus Manual on Trenchless Installation of Ductile Cast ... - Duktus

Other pluses that the two techniques have are these:
General
• There is no need for public-transport bus stops to be moved (see Fig. 3.3).
• There is almost no interference with delivery traffic in streets where there are business
premises.
• Other utilities carried in pipes are not put at risk by excavation work.
• Depending on the machinery used, whose maximum sound emission is less than .
dB(A), the installation work is particularly „quiet“ and free of dust. It is even possible
for work in residential areas to continue without any overnight breaks.
Above all when installation work is being done in inner city areas, where there are very
closely packed runs of pipe, intersecting pipelines and pipelines running in parallel are
very much at risk when heavy-duty digging equipment is used in open trenches. This risk
is cut to a minimum when trenchless replacement techniques are employed.
The two techniques can both be used for supply pipelines of nominal sizes ranging from
DN 80 to DN 00. What are required are:
• a machine pit to hold the machinery,
• an installation pit (about 7 metres long) for the new pipes,
• intermediate pits for the house connections or branch pipelines.
The distance between the intermediate pits depends on the nominal size of the old pipeline
and on the condition it is in, on the nominal size of the new pipeline, on the machinery
used, on the nature of the soil, on the trees present and their roots and of course on
the conditions relating to traffic and the medium involved. Depending on the technique
and the locality, the distance between the intermediate pits should not be more than 2
to 0 metres. With a straight run of pipes or one with a radius of curvature of not more
than 170 metres, the distance between the launch and arrival pits is normally from 100
to 180 metres. Before the replacement operation, the old pipeline has to be taken out
of service. The supply of the adjacent houses and other premises is maintained through
temporary interim pipelines, the water from which is fed into the house connecting
pipes, the ends of which have been closed off, in the pits for the house connections.
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