Glyn Rhonwy – Common Land Application and Open Access land

Snowdonia Pumped Hydro are currently in the process of developing the site at Glyn Rhonwy into a pumped storage hydro scheme. Part of the development and ancillary works would be on common land at Cefn Du (CL 15 & 18). To develop on common land, consent is required. This requires a formal application separate to the main planning application.

As part of this application, we will be de-registering an area of land approximately 32 acres which includes a fenced off disused quarry (Chwarel Fawr) of around 18 acres, which cannot be accessed for grazing. To compensate for the loss of common land, we will be replacing this area with grazeable fields of 40 acres; this land will have rights of common transferred to it. As this compensatory area takes into account in the inaccessible quarry area, there will be a net increase in grazeable land of approximately 26 acres, and a net increase in common land area of 8 acres in perpetuity.

As well as the permanent land take, there will also be an additional area of approximately 30 acres common which is temporarily fenced during the construction period for health and safety purposes. As this area will be fenced for up to 4 years, we will compensate by providing a piece of land in exchange for the fenced area to be used for grazing. This land consists of 25 acres which will be made available to commoners on the same basis as the temporarily fenced off common. Following completion of the project the 30 acres of common will be restored and returned to its present use.  

There will also be approximately 2.7 acres included in the application for road improvement works to allow for the placing of lay-bys, road widening and general road improvements up to Cefn Du. The actual area taken up by the improved road will be much smaller, will be at the edge of the common and will improve road safety and access to Cefn Du.

The works will also involve the creation of a temporary public access track within an area of 1.8 acres on the common. The track will not use all of this area, will not be fenced, and will be removed following construction.

Since most of the land around Cefn Du already is either already Common Land, or Countryside Rights of Way Act [CROW] designated, the replacement land we plan to offer is already designated as open access land. On its own, this would result in a net decrease in open access land area. To make up for this, we plan to designate 65 acres of currently undesignated, non-open access land as CROW land. The land area of this exchange land will be greater than any impacted land during construction and operation. It will also form a link or open access land between the common land at Cefn Du, and CROW open access land on Moel Eilio. The permanent impact of the development as proposed would be an increase in the area of common land of 8 acres and an increase in the area of land available for public recreation of 25 acres.

A selection of maps detailing the plans accompany this note. They are listed in the table below:

Figure No. Description Links
GR_CL_001 Map showing common land at Cefn Du Link
GR_CL_002 Map showing proposed access arrangements during construction Link
GR_CL_003 Map showing proposed access arrangements during operation Link
GR_CL_004 Map showing fenced area and replacement land during operation Link
GR_CL_005 Map showing fenced area and replacement land during construction Link
GR_CL_006 Map showing area for access improvements to Cefn Du Link
GR_CL_007 Map showing detail of access Improvement area Link
GR_CROW_001 Map showing current open access designations at Cefn Du Link
GR_CROW_002 Map showing proposed CROW replacement during construction Link
GR_CROW_003 Map showing proposed CROW replacement during operation Link


We are very interested to hear your views on this application. If you think that this is going to impact you, please let us know as we are very happy clarify any issues and to discuss what steps we could take to mitigate that impact and cause you the least disruption.

 If you have any questions about the application, you can contact the team by:

•             writing to us at 12a Head Street, Halstead, Essex, CO9 2BX.

•             email at This email address is being protected from spambots. You need JavaScript enabled to view it. 

•             online at