Reservoir Safety Improvement Works for Llyn Mair in Eryri National Park

Reservoirs Act 1975: Llyn Mair Reservoir, County of Gwynedd, Eryri National ParkReservoir Safety Improvement Works (MIOS)Tender Expression of InterestStillwater Associates has been employed by Eryri National Park to oversee the implementation of reservoir safety improvement works on Llyn Mair Reservoir.

The site is located close to the village of Maentwrog, NGR SH 653 412.The proposed works are the construction of a new siphon pipe to allow the reservoir level to be drawn down in case of emergencies. This is to be achieved by repurposing one of the four existing spillways (Spillway ‘C’) to contain the new HDPE siphon and then subsequently backfilling with mass concrete or aggregate depending on the location.

The upstream leg of the siphon is to be installed using qualified divers with some partial demolition work undertaken to the chamber. Additionally, Spillway ‘D’ is to be abandoned in situ by forming a wall across the existing channel.The works are required to address statutory recommendations made in the interests of reservoir safety.

Eryri National Park has committed to having the works completed by 31st July 2026 and it is imperative that the successful contractor delivers the works accordingly.NOTE: To register your interest in this notice and obtain any additional information please visit the Sell2Wales Web Site at https://www.sell2wales.gov.wales/Search/Search_Switch.aspx?ID=161799.The buyer has indicated that it will accept electronic responses to this notice via the Postbox facility.

A user guide is available at https://www.sell2wales.gov.wales/sitehelp/help_guides.aspx.Suppliers are advised to allow adequate time for uploading documents and to dispatch the electronic response well in advance of the closing time to avoid any last minute problems. see tender documents(WA Ref:161799)