Case study: UV cured lining

CaseStudy
UV Cured Lining
Customer: Thames Water
Location: Farnham
Project: UV Cured in-Situ Sewer Lining
A problematic drain at a rail crossing adjacent to Farnham Railway Station
was repeatedly flooding, causing pollution of a nearby river and leading to
serious concern from the Environment Agency. The failing drain had already
been jetted, with a CCTV survey being carried out to determine the cause.
The survey showed that the 70m long drain constructed from 225mm diameter
vitrified clay pipe that was suffering from serious root infiltration and was also
suffering from a number of structural defects. Several of the lateral connections
were intruding into the pipe, which combined with a very steep fall and high flow
rate meant that flooding was almost inevitable. In-Situ cured lining was identified
as the ideal solution to stabilise the pipe’s and act as a barrier to prevent further
re-growth of roots and prevent blockages. Other companies approached by
Thames Water had declined this contract due to its demanding nature.
On investigation OnSite determined that a UV cured in place pipe (CIPP); with its
much smaller site footprint compared to hot cure lining; greatly reduced curing
time of just 90 minutes compared to around 6 hours for a hot cure liner; and no
requirement for hot curing water and its associated problems with disposal of
polluted liquid on completion; offered clear advantages over hot water systems.
Because the project was located on an active rail crossing, it required working
under the supervision of a crossing guard within a strict six hour overnight
‘possessions’ allocated by Network Rail. The location also meant that flow control
had to be achieved using tankers and that all lining plant had to be positioned
outside the crossing, with cables running from the cutting and lining rigs, with a
system of pulleys set up to run under the crossing gates even when shut.
“I was genuinely impressed with the planning and execution
of the Station Hill sewer lining work, given the proximity of
the live railway track. It was fantastic to see the team working
through the night to ensure the job was completed on time.”
Martin Perrin, Thames Water South East Area Network Manager.
CaseStudy
UV Cured Lining
Lining and lateral cutting was controlled remotely
from the dedicated operations vehicle.
The UV ‘light train’ used to cure the liner in a tenth
the time required for hot water cured systems.
“The project was a success on all fronts, not
least in meeting and exceeding stakeholder
expectations. It enabled Thames Water to
rehabilitate a drain which had given repeated
problems. The Environment Agency is
pleased to now see prevention of further
flooding and pollution to the nearby river.
Network Rail, owner of the land and
assets, incurred no damage to property
and minimal disruption to its services.
Finally domestic users connected to
the drain experienced no interruption
to supply. All in all, this was a well
planned, managed and executed
project and we’re proud of our
team’s efforts.”
The project was programmed to be carried out over three
consecutive night time ‘possessions’, each of six hours.
Steve Ovington, OnSite
89 Blackpole West • Blackpole • Worcester WR3 8TJ.
From OnSite’s survey of the site it was established that the
lateral connections were sufficiently long to accommodate
being blocked off for a 24 hour period without affecting the
properties that they served. However a leaflet drop was
made to ensure local residents that might be affected by
the works were kept fully informed.
Night one saw the Robotic Root Cutter, Jetter and Tankers
mobilised to carry out all the preparatory on-site work.
On the second night the Lining Rig, Jetting unit and
Tankers were utilised to install the lining, which was cured
in place in just sixty minutes; a feat impossible for hot
water systems that would have required the entire six hour
possession simply to be cured.
During the final night the Robotic Cutter was utilised to reopen the lateral connections. An OnSite traffic management
team were in attendance throughout the project. An OnSite
main line CCTV rig was also in attendance to provide
support surveying of any problem areas that might arise.
[email protected]
www.onsite.co.uk 08454 600 365
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