The brief
Affinity Water called us in to a very severe burst on a 12 inch water main running underneath concrete silos at Wintersells Cement Works in West Byfleet. The word “severe” carries some weight here: the main had failed badly enough that a conventional dig-and-replace was never going to be the answer, and the site conditions made sure of it.
The challenge
Cement works are working industrial sites. Silos are mass-concrete structures that sit on foundations and feed production around them. You can’t excavate a failed main running underneath them without consequences. Breaking the ground up would have meant working around live plant, structural concrete assessment, and a customer who still needs their site to operate while you’re doing it.
On top of that, any route involving main replacement at length in that environment would have meant extended supply disruption for downstream customers. The call was to find a technique that didn’t dig up the silos and didn’t take the main out of service for days on end.
Our approach
Slip lining. A 250mm replacement main was threaded through 70 metres of the damaged 12 inch original, using the existing main as a host conduit. That meant a couple of insertion and reception pits rather than a 70-metre trench, and it left the silos, their foundations, and the working cement plant alone.
Once the slip liner was in, the new main was pressure tested to confirm integrity, then chlorinated to bring it up to potable-water hygiene standards before being commissioned back into the network. Both of those are regulatory requirements for returning a drinking water main to service, and both were handled on site within the job window.
- Original main
- 12 inch (burst)
- Slip liner
- 250mm, 70 metres
- Site constraint
- Main under concrete silos
- Technique
- Slip lining + pressure test + chlorination
- Duration
- 4 days
- Customer impact
- Minimal
- Client framework
- Affinity Water R&M
Outcome
Main back in service in four days. Customer impact described as minimal — a respectable outcome on a severe burst under live industrial infrastructure. The slip lining approach avoided the silo excavation entirely and gave the shortest credible route back to normal supply.
For the broader technique context, see our no-dig and trenchless methods and our chlorination and pressure testing work. The service context sits under water mains repair and maintenance for water companies.
