Site Address: Gilfach Nature Reserve, St Harmon, Rhayader, LD6 5LF

Bridge Location Grid Reference: SN 95901 71419.

Bridge Location What 3 Words: ///burden.shook.acquaint

Work Brief: Removal of built bridge arch structure and abutments down to the springing course. Reprofiling of approaches to a 1:2 batter and river banks to 45 degrees, aiming to restore a naturalistic varied structure

Accessibility: The bridge is 110 meters directly from a minor road, roughly 700 meters from the A470. This 110 meter stretch is steep, with a difference in elevation of roughly 20 meters between road and river bank. It is clear, but with natural upland features such as small rocky outcrops. There are footpaths leading to the bridge along the riverside on both sides, all surrounding land belongs to the Radnorshire Wildlife Trust. To area to the north of the bridge is an old tunnel entrance, the tunnel is inaccessible but the area in front is level and could make a suitable base area for works. Planned works must aim to keep ground damage to a minimum, we are happy to discuss options for temporary access improvements.

Environmental Considerations: The broader area is designated as Site of Special Scientific Interest (SSSI) and a Special Area of Conservation (SAC).The River Marteg is in itself a SSSI too, and is liable to sudden changes of flow, as is typical of spate rivers. In addition to preventing any ground damage through site access, any proposed demolition plan must minimize the likelihood of any debris falling into the river – with any debris being removed. We would expect to see the construction of a protective structure beneath the bridge to address this, though note no equipment may enter the river itself. The potential for the presence of contaminating materials such as clinker must also be considered, no testing has yet been undertaken.

Arisings: We would like arisings to be removed from site where possible, with the intention to sell marketable materials, we would prefer this to be arranged by the contractor. There is sufficient space on site for debris subject to environmental considerations and a design for appropriate landscaping.

Site Safety: Gilfach is our flagship nature reserve and very popular with visitors, site safety and security measures such as the erection of fences and temporary path closures must be included to ensure the general public is excluded from the working area.

Reasoning: The structure is in poor and deteriorating condition as is detailed in civil and structural engineering reports available for review by tendering contractors. In response to these reports access over the bridge via a permissive footpath and for management use for staff has now been closed. In addition, access to the bridge abutment sides and underside on foot has been blocked, however access along the watercourse cannot be permanently blocked (though could be closed temporarily to ensure safe works). The Trust cannot fund repairs of a disused non-heritage asset so there is now potential for environmental damage by the structure’s collapse into the water course, causing contamination and impacting the river’s hydrology and requiring a reactive clean-up operation. We have explored options for repair, but concluded that this is prohibitively expensive given the continued maintenance cost.

Contact: To arrange a site visit please contact Robert Hall - Reserves Officer, 07990913227, or robert@rwtwales.org

Dates: Written quotes must be supplied to the above contract by November 20th 2023, with Contracts to be granted in Spring 2024, for work to be completed Autumn/Winter 2024.