Portsdown Tunnels - The Green Pipes

The Green Pipes

Created 01-02-2013 Last update 01-02-2013

For many years I have had enquiries from readers about a green pipe (or green funnel, green tube) which sticks out of the ground in a lane behind the Churchillian Pub which is just east of Fort Widley. I had also noticed that some fairly wild theories about the pipe's purpose were published on the internet. As usual these revolved around some kind of secret bunker or a connection with the London Road Tunnel Shelter or the Fort Widley Civil Defence Bunker.

Eventually I found time to look into this mystery (hence its inclusion in the Legends & Mysteries section) and I started off by ruling out what it wasn't:

there is no bunker at this location or even a requirement for one
the green pipe did not conform to the usual above ground bunker structures
it was too far from any existing underground working to be connected to it and would serve no purpose anyway.

I then looked at what it might be. On examination, the top of the pipe appeared to be engineered in a way that suggested a ventilation stack of some kind. I also noticed that an indicator post was located in a field nearby showing that a gas pipeline ran under the site. I now narrowed its purpose down to two theories:

that it was connected in someway to an agricultural feature such as a methane ventilator for an underground bio-digester
that it was a component of the nearby natural gas pipeline.

Examination of the surrounding area pretty much ruled out the first idea since there was no other supporting evidence. I then decided to pursue the second theory and contacted Scotia Gas Networks a company, which remarkably, is responsible for Southern Gas Networks. There was some initial confusion since they seemed to be under the impression that I wanted to dig up the site! However once this was sorted out they were very helpful and put me in contact with a company representative who finally solved the mystery.

Sources:	Scotia Gas Networks
	Haley Storey
	Andy Parfitt
	Richard Bradshaw

The red ellipse at the top right shows the green pipe's location indicating its geographical relationship with Fort Widley and the Churchillian pub. The red arrow at the bottom shows the camera viewpoint of the next photograph.

Looking north (see the red arrow in the above photo). This is the field between Fort Widley to the west (left) and the Churchillian pub to the east (right). The lane leading to the pipe can just be seen in the hedgerow a quarter way along the photo from the right. In the distance are the South Downs.

The Green Pipe, ecologically painted and placed so as not to easily show-up. A 42 inch, high pressure, natural gas pipeline runs up the hill at this point supplying gas to Portsmouth and the surrounding area. To prevent corrosion the actual gas pipeline is placed within another pipeline called a sleeve. The space between the two pipes is filled with nitrogen gas to about 1.5 bar (22psi). Should the natural gas pipeline leak then the gas would flow into the sleeve and thus be safely contained in an inert nitrogen atmosphere. The proper name for the green pipe is a 'Burster Pipe" and it is connected directly to the sleeve. In the event that the sleeve over-pressures for any reason then a burster disk will open at the top of the pipe and vent the gasses to the atmosphere. In other words it's a safety valve.

Just a few yards further north along the lane is this structure called the 'Sleeve Terminal'. These are the access shafts to the start of the sleeve. The natural gas pipeline runs south in direct contact with the ground up to this point where it then enters the gastight nitrogen filled sleeve. The sleeve runs from here to the Crookhorn Golf Course where the gas pipeline then returns to ground contact. In the field between and behind the two shafts is the gas pipeline marker.

It was just possible to take a chance photo through the grill at the top of the access pipe giving a partial view of the terminal chamber.

Home Page

Site Index