East Coast Mainline Case Study - EDF Energy (St. Neots).

EDF Energy are constantly upgrading both its retail and commercial services and having to do all that in cost effective, non disruptive and environmentally friendly ways.

Shifting its supply from a route some 30 metres from the main East Coast Mainline in Cambridgeshire to go underground across neighbouring land on the other side of the tracks was always going to pose problems. But the prize for EDF is not just efficiencies - it's also about getting rid of massive ugly pylons that stretch across the countryside.

CTB moved in at the beginning of September and finished the job inside 10 days.

And, as is our usual practice, we left the site cleared and cleaned with all drilling fluids properly and environmentally recycled.


So, How Did We Do It?

Utilising one of their Vermeer 33 x 44 drilling rigs & recycling plant CTB installed three 180 PE100 SDR11 ducts beneath the line. Each duct was installed at 3 metre centres, 6.5 metres deep beneath the railway & 90 metres long, crossing a high pressure gas main and through to open countryside with not one train delay and no scars to the environment.

Was it really that straightforward?

Very low overhead cables dropping into the substation meant that CTB could not get their mixing & recycling plants within 185 metres of the drilling site.

So, to keep the drill rig & recycling plant supplied with drilling fluid, a 485 metre labyrinth of mud lines had to be installed around the site, and additional water was brought to site using CTBs 1500 gallon lorry mounted water bowser & mixing plant.

The reactive clay ground conditions weren't exactly a bonus either. The potential problems in such ground are many and varied.

Pilots were drilled using standard top loading drill housing & location was done remotely using one of CTBs Eclipse location systems. But we're equal to all that and using a mix of techniques, materials and machinery (including large quantities of biodegradable betonite polymer based drilling fluids - 70 gallons per min marshal funnel viscosity 45-50 seconds ) we pre reamed & swabbed each crossing a total 5 times to ensure the hole was clear of cuttings so that pulling the product pipe was problem free.