Koster solves water seepage on a section of London Underground track

  • 1 Feb 2019

Koster was recently invited to investigate signs of water seepage on a section of track located close to the London Underground’s Farringdon station.

Koster carried out a trial on a section of track (the Metropolitan Line). The brief was to provide an elastic, permanent repair solution which would accommodate the stresses associated with tunnel waterproofing whilst being sympathetic to the ageing construction and causing no detrimental effect to the structure nor the trains passing through.

The construction of the tunnel is multiple layers of brickwork with an assumed tar or bitumen waterproofing layer externally. There was evidence of water seeping from the brickwork, stalactites, heavy salt and soot crust formations throughout the tunnel and a previous installation of injection packers which lined the crown.

Prior to conducting a product trial, a close examination of the tunnel was undertaken. One area which was showing significant signs of water seepage (water ingress via the brickwork) was at the tunnel’s crown.

Screen Shot 2019-02-01 at 10.15.12The areas of active leakage were evident (through old injection packer holes and badly pointed brickwork). These areas of active leakage were initially sealed using Koster Waterstop and KD2 Blitz to immediately prevent the passage of pressurised water.

Once the area was free from running water, the second job was to measure and mark out the borehole positions for Koster Superpackers – small injection lances which have been specially designed to give a superior grip whilst delivering a constant flow of grouting resin. Koster specified the Injection ports to be placed at 400mm centres in a grid pattern, with a single packer positioned in the centre.

The boreholes were drilled to a pre-determined depth which would facilitate the packers. Koster Superpackers were then inserted and the area was ready for the Gel injection. The material used was an acrylic-based resin, Koster G4 Gel, which has a similar initial viscosity to water.

The Koster G4 Injection Gel fills the same minute tracks and veins that water follows when infiltrating the structure. When injected into pore structures, the Injection Gel G4 cures to form an elastic, permanent gel which is then able to move and flex within the brickwork. 

The G4 Injection pump was set up and operated from a rolling platform below the scaffold tower, allowing for ease of access to each packer during the injection stage. Following the injection phase, the Koster Superpackers were removed and the boreholes filled using Koster KB Fix 5 fast-set mortar.

Consequently, the water seepage has now stopped and the brickwork lining is now fully protected from future water ingress without compromising the tunnel lining.


Delta Membrane Systems,
Delta House,
Merlin Way,
North Weald,
CM16 6HR
United Kingdom

Visit Delta Membrane Systems' website

Leave a Reply

Latest news


VELUX: Building considerations for commercial rooflight refurbishment

For any commercial rooflight refurbishment project, there are a number of building considerations to factor in. Therefore, VELUX Commercial’s new detailed white paper explores these considerations influencing commercial building refurbishment.

Posted in Articles, Building Industry News, Building Products & Structures, Glass, Innovations & New Products, Lighting, Publications, Research & Materials Testing, Restoration & Refurbishment, Retrofit & Renovation, Roofs, Windows


EJOT provides innovative anchoring solution for Hempcrete eco-insulation

Construction fastening technology specialist EJOT provides an effective anchoring solution to enable a Yorkshire building contractor to use hemp-based insulation as part of the sustainable upgrade of a 200 year old cottage.

Posted in Articles, Building Industry News, Building Products & Structures, Case Studies, Innovations & New Products, Insulation, Posts, Restoration & Refurbishment, Retrofit & Renovation, Sustainability & Energy Efficiency, Walls


Global brand Oakio adds cladding to its UK offer

Oakio next generation external cladding is now available in the UK. This product ticks boxes for looks, durability and sustainability with 95% of the boards made from reclaimed oak and other recycled products. 

Posted in Articles, Building Industry News, Building Products & Structures, Building Systems, Cladding, Innovations & New Products, Restoration & Refurbishment, Retrofit & Renovation, Sustainability & Energy Efficiency, Timber Buildings and Timber Products, Walls, Waste Management & Recycling, Wooden products


Keyline encourages civils industry to look after mental health

Keyline Civils Specialist is teaming up with the Lighthouse Construction Industry Charity to launch a social media campaign encouraging the civils sector to open up about mental health and wellbeing.

Posted in Articles, Building Industry News, Building Products & Structures, Drainage, Drainage, Guttering, Soffits & Fascias, Fascias, Health & Safety, Information Technology, Innovations & New Products, news, Plumbing, Roofs, Walls