Koster Aquatecnic were approached to provide recommendations for sealing of the heavily leaking basement areas-containing kitchens, food storage/ food preparation areas, spa, plant rooms and accommodation.
The hotel is near to the river Thames and the below ground levels are subject to continuous water pressure due to the high water table. The original waterproofing system was based on the secant piled walls and a block wall internally to provide a basic drained protection system with drainage holes at various points draining to a lower level. Over time, the third floor had become completely saturated with all levels of the basement experiencing water ingress in varying levels from damp patches to significant ‘in rushes’ of water through the secant piles.
Firstly, the secant piles were exposed and thoroughly cleaned to remove dirt, salts, and loose particles. At the top of each basement level there was a concrete corbel connected into the piles, our research had shown that this was acting as a pathway for water to circulate around the building. We injected into this with Koster 2 IN 1 to seal the pathway between the corbel and the soffit and between the pile and the corbel.
The piles were then injected with the Koster G4 Gel. Before injection we slowed the water flow significantly with a combination of KD 2 Blitz and Koster Waterstop. 14mm boreholes were drilled directly through the piled wall at the point that the piles intercepted. Each borehole was closed with a Koster Super Packer, prior to drilling the next hole. The boreholes were drilled at 350mm centres in a vertical line between each pile.
The G4 Gel was injected using an acrylic gel pump. Each packer was injected in turn starting at the top and working to the bottom of the run. Each packer was injected multiple times in rotation, until the Gel was set and the borehole was completely sealed. After this the packers were removed, and the boreholes filled with Koster Repair Mortar Plus.
As work progressed it became apparent that some areas were quite dry and other areas were leaking very heavily. In the areas of the heaviest ingress, we were still able to seal the leakage, by either adapting the speed of the G4 Gel by increasing the salt content (in strict accordance with instructions received from Koster Bauchemie) or by using Koster S4 Gel which has an even faster gel time, this proved to be very useful backup material.
After each area was sealed by injection a period of 5 weeks was allowed for observation before application of the cavity drainage system. However, in all cases no further in-rushes of water occurred.
