Thames Water Large Diameter Pressure Pipe Rehabilitation

Works carried out on behalf of Thames Water / Eight20 (SMB)

The alliance brings together global expertise from multiple sectors – including Thames Water – aligned around a common set of outcomes and a shared vision. Eight2O is a place where all partners put in their best people, practices and techniques to deliver innovative, sustainable solutions. This brings greater value for money and benefits to Thames Water customers and a stable return.

Works Description

The scope of the works was to install 170m x 800mm pressure UV liner using the Alpha Liner from Reline Europe. This was between Fishguard Way and The Royal Docks.

The objective of the main work is for the remediation of the pressure main from Store Road pumping station. After a recent burst in the area where the know location of the burst would block the only access route into a large residential estate an open cut repair wasn’t feasible. Therefore the solution was to excavation two pits 170m apart and install a pressure UV liner between these points, capable of withstanding pressures varying between 12bar and -0.9bar (almost full vacuum).

Figure 1: Demonstrates the location of Burst

This was the first UV pressure liner to be installed within the Thames Water network – therefore a lot of time and effort was put in to assure the liners capabilities and previous test data to get the sign off from Thames and Eight20 design teams.

The initial stage was to open the pipe and undertake a pre survey and laser scan to ensure the feasibility of liner installation. As you will see from the photos below we modified and produced a scanning device with the ability to laser scan the 800mm pipe whilst completing the mainline survey. This allowed us to establish the ovality for design inputs and ensure we could install the liner successfully. The outcome was a 10% deformed pipe.

The nature of the effluent in this sewer was known to be very corrosive and was known to attack the host pipe. Therefore, a consideration was required for this and the installation of the UV liner with Vinylester (VE) resin was necessary to protect against the corrosive nature.

In order to install this 15ton liner the design and fabrication of a complex winching frame was required. Allowing for a reverse pull, capable of withstanding a 10ton pull force. This was required due to the limited working space around the excavation at the Royal Docks.

Upon installation and curing of the liner it was necessary to install GRP resin fixed flanges to either end which would allow for the reconnection of the main. Finished off with a fiberwrap externally to secure the host pipe, liner and flange couple together.

The final stage before reconnection and re-commissioning was to pressure test the main to 5.25bar. This was 1.5x working pressure.

This successfully passed the test and has been put back into commission.

The installation sequence:

Undertake final cleaning and a pre-lining CCTV survey of the pipe immediately prior the installation of the liner.
Undertake installation of the liner.
Fit flange collars to either end of the liner (PN10) and seal.
Fit mono seals across inner connection
Undertake water pressure test to 5.25 bar.

Considering this was the first installation it was delivered successfully on time and within budget.

We commenced on site w/c 08/04/19 and was completed including full reconnection detail and testing/recommission 15/05/19.

Below are some photos of the installation and show what was installed.