Author: Professor, Dr. Dietrich Stein - TrenchlessOnline

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A pear-shape, brick sewer, 1,800 x 2,250-mm I.D., was rehabbed with
the Trolining Double-System.
was limited to 85 m in the past, the mentioned distances
required additional efforts from both Trolining’s liner manufacturer
and the installation crew. Trolining engineers and
site experts tackled the situation and presented the solution
after a number of technical meetings and process improvements.
Insertion of the 2.5-ton weighting liners occurred from
the intermediate manhole, which separated the 210 m of
egg-shape pipe into 103 and 107 m, both into the up-stream
and downstream direction.Large triangle stands were placed
next to the insertion pit to hang up the liner coils. For drawing
the liners into the pipe,diversion rollers had to be placed
right above the manhole chamber. After insertion of both
studded liners, the resulting annulus was sealed by manual
extrusion welding. Inflatable egg-shape packers were then
used to plug the liner-package at both ends and water was
fed in to build up a defined hydrostatic pressure. Special
attention had to be given to the plug bracing — with a water
column of 8 m (equal to 11.6 psi back pressure) and a crosssectional
area of 2.45 sq m.An equivalent horizontal force of
approximate 20 tons had to be taken by the construction
that held the plugs in place.
The 103- and the 107-m long pipe sections were
rehabbed separately. Grouting of both occurred with the
Trolining-specific mixing technology. Three standard mixing
units were employed to prepare the injection grout.
The Double System’s outer annular void space was filled
first, needing approximately 1.5 hours for completion.The
inner annulus could then be grouted within just one hour.
After an additional 16 hours of curing, the high-strength
grout attained the necessary short-term strength necessary
for releasing the inside pressure from the lining system.
Right afterward, the incoming house connections could be
re-opened and connected.
Jens Kirste is with technical sales at Trolining GmbH, which
is headquartered in Troisdorf, Germany.
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50 TRENCHLESS TECHNOLOGY September 2007 www.trenchlessonline.com