OS Grid Ref: NH 22393 10846 (access tunnel portal)
Date opened: 1959
Date closed : Operational
The surge shaft at Ceannacroc is on the hill above the power station; in
this view you can actually see the surface buildings, the transformer,
and the road running down to the access tunnel below:
Photo: Ceannacroc Surge Shaft
Photo by: Mike
Ross
The surge shaft is equipped with a control gate and gatehouse, and access
ladders for climbing down the shaft:
Illustration: Ceannacroc Surge Shaft
Illustration by: Scanned by Mike Ross, from Proceedings of the Institution
of Civil Engineers, Sept. 1958
The view down Glenmoriston from the surge shaft is spectacular:
Photo: Ceannacroc Surge Shaft
Photo by: Mike Ross
The view down the surge shaft isn't normally quite so spectacular; it's
almost always full of water:
Photo: Ceannacroc Surge Shaft
Photo by: Mike
Ross
But on rare occasions the entire system is dewatered for maintenance. This
reveals the full spectacular dimensions of the shaft - 180ft deep, 45ft
in diameter:
Photo: Ceannacroc Surge Shaft
Photo by: Mike Ross
Here's the view straight down the shaft. It's a plain open shaft; there's
no differential riser, throttle, or orifice. The water enters from the
lower right, through the control gate (covered in scaffolding in this shot),
passes through the screen in the middle, and drops another 180ft down the
vertical high-pressure shaft (boarded over in the upper right of this shot):
Photo: Ceannacroc Surge Shaft
Photo by: Mike Ross
Here's a drawing of the surge shaft and high-pressure system I managed
to photograph - the high-res version is much better:
Photo: Ceannacroc Surge Shaft
Photo by: Mike Ross
This drawing shows how the surge shaft fits into the more general scheme of things:
Illustration: Ceannacroc Power Station
Illustration by: Scanned by Mike Ross, from Proceedings of the Institution
of Civil Engineers, Sept. 1958
The day after the above shots were taken, I returned, by invitation, and
was given a guided tour through a construction adit and into the low-pressure
tunnel. This gave me the unique chance to take some pictures at the bottom
of a surge shaft. In the shot below, I've just emerged from the low-pressure
tunnel (behind the gentlemen in blue boiler suits), passed under the control
gate (which is hidden behind the scaffolding), and climbed the staples
on the left, to the floor of the surge shaft itself:
Photo: Ceannacroc Surge Shaft
Photo by: Mike Ross
Looking up from the bottom of the climbing staples - a spectacular view
of the daylight streaming down the shaft:
Photo: Ceannacroc Surge Shaft
Photo by: Mike Ross
A slightly different angle, giving a better view of the climbing ladders
(no I didn't climb them!) and the operating gear running down from the
gatehouse to the control gate:
Photo: Ceannacroc Surge Shaft
Photo by: Mike Ross
A final spectacular view up the shaft, this time exposed for the sky rather
then the walls:
Photo: Ceannacroc Surge Shaft
Photo by: Mike Ross
