Report - Valve Tunnel, Llyn Peris - North Wales - January 2013

[hhh]

I'm a little unsure whether to bother posting this, but having had a quick nose around the internet I've been unable to find anything on it (probably down to me using the wrong search terms). Not found other photographs either. No indication of tunnel old or current maps (scales 1:2,500 - 1:50,000). The entrance to the tunnel is very visible from the other side of the lake.

Between Nant Peris and Llanberis in North Wales on south western side of Llyn Peris between the lake and the road (A4096), Tunnel perhaps 30m deep, lined with spray concrete, inside the back of the tunnel is blocked with reinforced concrete coming out of which are two large c.2ft diameter steel pipes with valves on the ends. The valves are wrapped in grease and fabric. The pipes sound empty. The direction the tunnel goes in probably puts the back of the tunnel somewhere under the road. There is a flat area outside the entrance to the tunnel and then it is much steeper down to the lake edge.

The are remains of old copper mines in the mountainside behind.

Uncertain whether this is related to when Dinorwig Power Station was constructed on the other side of the lake or might be earlier.

 

[MotoSteve]

Spotted this tunnel today while out and about. Does anyone have any further information about this tunnel ?

 

[MotoSteve]

A slightly better view showing the location Grid Reference SH 59325 59154

 

[MotoSteve]

An update to trhis topic.

I received this reply from an enquiry mailed to Electric Mountain Visitor Centre;

"Good Morning Mr Doyle,

Thank for your enquiry.

During construction , to excavate the diversion tunnel they used three teams to complete the job faster. One team were up the pass digging down, second team digging up by the dam and third team in the middle digging up and down to meet the others.

What you’ve seen is the middle teams tunnel .It goes in for about 20 yards then its bricked up .Behind which is the diversion tunnel itself.

Hope that is of some help to you.

Kind Regards

Ana Maria Gaete
Tour Operations Team Leader/ Administrator
Electric Mountain Visitor Centre"

This report also adds further detail;

https://www.field-studies-council.org/media/2617045/background_information_-_afon_nant_peris.pdf

 

[monk]

Checked this out a few weeks back, was disapointed to find it was only a short tunnel.

 

[hhh]

From the original thread before it was archived (and comments removed):

[/URL]
You can see this tunnel for miles around, one day I'll bother to stop and take a look.
I got this email about the tunnel...

"The valve tunnel conects to a tunnel that was driven to cut off the stream entering Llyn Peris, bypassing Peris and emerging just to the west of Dolbdarn Castle. The valve tunnel was used to conect two huge pumps on pontoons used to drain Llyn Peris. I saw these in action in the early eighties.

I hope this may be of some help to the poster, from a long time lurker."