Bwlch Nant yr Arian Reservoir
Client: NATURAL RESOURCES WALES
- RESERVOIR EMBANKMENT EARTHWORKS AND RIP-RAP PROTECTION
- CONSTRUCTION OF NEW POND INCLUDING FEEDER PIPE AND MANHOLES
- REINFORCED CONCRETE SPILLWAY
- REMOVAL OF THE EXISTING OUTFALL
- FOOTBRIDGE, FENCING, LANDSCAPING, IMPROVEMENT WORKS TO EXISTING ACCESS TRACKS AND FOOTPATHS
As part of the new reservoir regulations Walters were engaged by NRW to undertake several Measures in the Interest of Safety (MITIOS) works to this Category A High Risk reservoir in Ceredigion. A S10 inspection report by All Reservoir Panel Engineer (ARPE) had identified that several works needed urgently doing to maintain the integrity of the reservoir including refurbishing the existing dam, constructing an overflow and installing facilities to draw down the reservoir. All of these works needed completing within a tight programme and with the works being constructing in a remote and sensitive location that is a very popular tourism destination.
We developed a robust 14 week programme in order to finish the proposed works 3 weeks ahead of schedule. This was based on utilising our self-delivery resource to prepare all necessary pre-start approvals – including CEMP, NRSWA and APRE – and deliver the construction works. We prepared a detailed approach to constructing the works around the local red kite population including working around their daily feeding time. We worked closely with the local visitor centre to ensure our works had minimal impact on visitors who included walkers, bikers and visitors to the centre itself. We also improved an existing access track to enable us to bring the required plant and material to the works. The works were ultimately finished on time and ahead of programme.
We developed an innovative approach to transporting the required concrete to the new slipway – using an all-terrain mini-mix on a dumper chassis. This was loaded at a land transfer point by road going lorries and then transported along the existing access track to site. This avoided the requirement to upgrade the existing access track which would have led to habitat loss.
NEW SPILL WAY
In order for the existing reservoir to achieve the MITIOS standards, a new spill way was constructed along with penstock to control water flows within the existing pond. A new foot bridge was installed to maintain pedestrian access around the pond.
The existing dam was carefully repaired and re-profiled using clay and site won topsoil around the spill way, and with a geosynthetic liner and rip-rap installed along the upstream face and wrapped beyond the mitre to protect the face.