Author: Professor, Dr. Dietrich Stein - TrenchlessOnline

ensures 100 percent grouting of the annular void, even for
long distances.Additional grout characteristics are a defined
material expansion and an exceeding short-term strength.
The latter is decisive to keep the interruption time at an
acceptable low level.
The GIPP Method
Despite of the GIPP method’s economic advantages,
Trolining’s tender for the Bielefield project also succeeded
due to the certified quality assurance and the high experience
level in the field of large pipe rehabilitation, especially
egg-shapes. The Trolining Double System with a wall
thickness of 43 mm was quoted in that case — double
meaning due to comprising two layers of studded HDPE
liners. Additional reasons for choosing the GIPP method
were the environmental friendliness and drinking water
approval of HDPE, as well as the material’s compatibility
with other lining components. State-of-the-art PE extrusion
welding allows absolutely tight connections between the
actual pipe liner and manhole rehabilitation sheets or the
inverted HDPE saddles used for lateral connection.
An exceptional difference to other lining systems was
the special system configuration Trolining was able to provide
for dealing with Bielefeld’s specific project needs.
While the common Trolining Double System involves an
outer Preliner and a smooth HDPE liner that gets inserted
prior to the studded ones, it was omitted in that case.
Omitting the Preliner means that the outer annular void of
the Double System was limited at the outside
by the host pipe itself, while the first
studded liner represented the inside
boundary. In that way, it was possible to
properly re-fill all defective joints
between the brick work and embed the
whole interior host pipe wall into a highly
protective alkaline milieu by direct
adhesion of the cementitious grout.
One year before, in August 2005,
Trolining had successfully rehabbed a
comparable host pipe, a pear-shape brick
sewer, sized 1,800- x 2,250-mm I.D., by
application of the same method. Drilling
cores taken at this project proved the
deep and reliable penetration of the
Trolining grout into deteriorated brick
wall joints.
Project Implementation
Before the actual system installation
could start, a number of essential preparations
had to be done.A major item was the
erection of a bypass line to divert the arising
sewage around the construction area
for the period of work.A steel pipe measuring
800 mm in diameter was laid over
the ground to provide sufficient capacity
for keeping the rehab sections dry. After
dewatering the entire 520 m, technicians
could access the host pipe and evaluate
the further steps. Intensive cleaning and
the provisional stopping of strong water
infiltrations were required. At the same
www.trenchlessonline.com
Circle 43 on reader service card.
Here, studded HDPE liner is unwound from the coil into the insertion pit.
time,subcontractors enlarged those manholes that were designated
for the HDPE liners’ insertion, to chambers of 2 x 2
m.
About three weeks after starting the preparations, the first
liners were installed.The common manhole distances for the
1,200 x 1,800 mm were 60 m in average,which is a standard
pipe length to rehab in municipal areas. More challenging
were the manhole distances of the 1,400- x 2,100-mm host
pipe;103 and 107 m were the lengths that had to be lined in
one step.While liner production for diameters of 1,200 mm
September 2007 TRENCHLESS TECHNOLOGY 49