North American Special - Trenchless International

Insertion of the liner takes about three hours.
Cured liner in the accessible
oval profile.
shaft the liner was equipped with pressure
locks so that it could then be expanded in
the sewer using compressed air.
projects
April 2009 - Trenchless International
liners of 32.5 metres and 173.6 metres in
length had to be installed, including all
preparatory and related work.
Light-curing GFRP liner
The related work included the opening
of the connection lines that are covered
up by the liner. This work played a decisive
role in the selection of the process
— due to the time factor. The planners
at HanseWasser decided at the outset
that only light-curing GFRP liner systems
were to be considered. With this pipe lining
variant there is no need to consider
the reduction of stresses in the liner,
which can take several days. The lack of
shrinkage means that there are no axial
movements and the connections can be
milled out directly after the curing of the
liner without the risk of changes in length.
Considering the high density of connections
in Ostertorsteinweg and the fact
that behind almost every connection there
is a multi-storey residential building with
retail space at ground floor level, smooth
maintenance of the drainage was especially
important. In order to maintain the
drainage during the rehabilitation, DN 400
free-flow pipelines were installed above
ground for temporary water drainage,
including sufficiently powerful pumps.
At exactly 9:00 pm, the last train had
just disappeared around the corner and
the preparatory cleaning work began in
the collection drain so that at 11:00 pm
the Brandenburger construction crew
could begin with the insertion of the liner
through the start shaft near Poststraße. The
10.4 tonne glass fibre tube was let down
into the opened shaft out of the transport
packaging and, using an electrical
conveyor belt, pulled with a steel cable
connection to the target shaft at the
Weberstraße. A foil that had been laid
down protected it from damage. At 2:00 am
on Saturday morning, the entire 173 metre
length of liner lay in the Ostertorsteinweg
collection drain. At the start and end of the
Lamp train and curing
A lamp train with nine UV modules,
each 1,000 watt maximum power, was
pulled through the form-fit calibrated liner
with pre-calculated speed. The connection
to the new UV technology with the
special resin recipe made it possible to
also achieve curing in a very short time.
The light-curing process lasted a total of
four and a half hours at a train speed of
65 cm per minute and was recorded in
all relevant parameters, including speed,
exposure dose and liner temperature. The
computer-aided documentation of this
data allowed for any eventual deviations
from target values of the technical parameters
to be recognised immediately and
allowed tracking of the curing procedure.
Connection lines
Directly after the curing of the liner,
work began to open the connections. By
midday Saturday, all 48 residential connections
in the rehabilitated collection
drain were milled open and at the start
of the tram traffic on Monday morning at
9:00 am they were all connected according
to the specifications of the client. This
was accomplished with the installation of
glass fibre short liners up to 50 cm over
the first pipe connection. The direct support
area was filled with an epoxy resin
system so that it was waterproof and
had no cavities. The local residents were
hardly affected by the project in terms
of disruptive effects normally associated
with construction projects.
Further construction sections
The combined second and third construction
sections in Ostertorsteinweg
were performed over ten days. As the
tram traffic was already suspended, there
was not the same degree of time pressure
as in the first section. Two 115 and
128 metre long liners were installed with
all preparatory and related work. There
was a work pause of almost four weeks
after the first construction section due
to a large number of residential connections,
in the area of the collection drain
yet to be rehabilitated, that were renewed
in open cut. This entailed excavation
work but also the renewed preparation
of the surrounding drainage conduit. The
independent laboratory inspection, as
a major component of the quality management
system, was performed in the
Ostertorsteinweg project by engineering
company Siebert in Oststeinbek. Their
analysis of the liner samples taken from
the construction site came to the positive
result that all specified parameter nominal
values of all liners were exceeded by
at least ten per cent.
Summary
HanseWasser was pleased with the
successful and on schedule completion
of the rehabilitation project. The successful
Ostertorsteinweg rehabilitation project
accentuated not only the special advantages
of the liner process that was used,
but is also another example for the plus
factors of the trenchless pipe lining technology
as a whole.
The rehabilitation using pipe lining with light-curing
reaction resin systems
The procedure has already proved itself in 26 countries, in which
over 2,000 km of sewers have been installed in diameters from DN
150 to DN 1000. In principle, the Brandenburger pipe liner procedure
is based on the same basic idea as all other liner. A tube support
saturated with reactive synthetic resin is brought into the sewer,
where it is expanded with inside pressure to be form-fitting, i.e.
with no ring gap, and then cured by a chemical reaction of the resin
to a self-supporting inner lining. This technology is consequently
trenchless, as no type of earthworks are necessary. The flexible
liner tubes are typically applied using existing inspection shafts
in the sewer. The special characteristics that differentiate the
Brandenburger liner system from other pipe lining types are:
• Use of seamlessly wound liners out of glass fibre laminate webs,
• Unique saturation of the raw materials before the production of
the pipe liner with UV-reactive UP resin (possibly with addition
of peroxides for the variation “hybrid curing” for larger wall
thicknesses over 10 millimetres)
• Drawing in the liner on a protective foil and form-fitting expansion
using compressed air
• Curing of the liner using precisely dosed UV exposure
(“BLUETEC® technology”).
projects
April 2009 - Trenchless International
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