Twenty-first century technology has helped gas engineers work a hole lot quicker in Durham’s historic city centre.
Instead of digging metres of trenches, engineers working for Northern Gas Networks pushed their new plastic pipe inside the old iron gas main while the gas was still flowing through it.
The specialist technique is called live mains insertion, because the gas main is still “live” when the new pipe goes in.
In all, 500m of old gas pipe in Market Place, Silver Street, Saddler Street and Elvet Bridge are being renewed by United Utilities and Balfour Beatty on Northern Gas Networks’ behalf.
The scheme, which started on January 28, is expected to last until the end of April and is costing the firm £77,000.
Barry Watson, of United Utilities, said around 200m of new pipe was pushed under the full length of Silver Street from the Market Place to the far side of Framwelgate Bridge.
“This process took us a matter of days. Digging it out would have taken weeks and it would have been messy. It’s not something we wanted to do in such a busy shopping area,” he said.
Previously little used in the North of England, live mains insertion looks set to be speeding up many more mains replacement jobs across the region this year.
United Utilities manages Northern Gas Networks’ £60m annual programme of gas mains investment which will see 528km of mains replaced this year. A significant proportion will be done by live mains insertion.
Engineers are now preparing to start the next phase of their work in Durham, which will be outside St Nicholas Church. Work on this phase starts on March 31 and is expected to last two weeks.