Project: Kennington Station – Replacement of Defective Delta Lining
Client: Tube Lines Limited
Works Value: £170,000
We were tasked with the replacement of defective DELTA Lining on the Platform 4 walls. Works at high level were carried out off of mobile towers erected either onto the track bed or off of pit platforms.
The existing evaporation tray and the tile band were removed from the full length of the platform. At the north end of the platform we removed the delta lining from the evaporation tray up to the top advertising rail. At the south end of the platform we removed the delta lining to a height of 600mm above the evaporation tray.
We then fixed a new evaporation tray at twice the height of the existing, along the full length of the platform and sealed the top with an LUL approved water proof mastic. Drainage pipes were fitted to pre-drilled holes in the evaporation channel to allow water run off to the track pit invert.
The new Delta PT membrane was then fixed into place with Delta plugs (which have Delta mastic rope wrapped around them) hammered into holes drilled through the membrane, with sheets overlapped by a minimum of 200mm. Mastic was applied between the joints to maintain the integrity of the waterproofing and a three coat plaster system was then applied to the Delta Sheeting. This system will comprised of 1 coat of Whitewall plaster, a 2nd coat Whitewall plaster and a final coat of Whitewall plaster as a finish coat.
New border tiles were then fixed to the Delta lining above the evaporation tray with an approved tile adhesive.
Following a drying period we decorated the new Delta Lining and the area above up to the crown of the tunnel to colour match the existing wall.
Whilst on site we also repaired an area of defective plaster at the north portal wall and decorated the wall to match existing finishes.
Finally the area below the evaporation tray was to be decorated. At the north end of the platform the render at low level was found to be defective. This area was hacked off and the wall was re-rendered with Sika 1 to a finish. Following a cuing period this section and the tiled area at the south end of the platform were decorated with black matt paint.