Edinburgh Castle: 'Significant rockfall hazard' detected by geologists

A ‘significant rockfall hazard’ has been detected at Edinburgh Castle, with safety works set to be carried out.

Geologists have found weaknesses in Castle Rock to the south west of the castle complex, below the piping school, in an area close to King’s Stables Road.

Inspections of the rock slope in July 2021 found the area had “significantly deteriorated”, with a “significant rockfall hazard” and a potential impact to the fabric of the castle structure reported.

An application by Historic Environment Scotland (HES) to carry out scheduled monument works has now been lodged.

Edinburgh Castle from the Grassmarket, with the problem area of rockface to the west of this southerly view. PIC: CC/Stephencdickson

It proposes to fit netting to the area of rock face to “prevent rockfalls, thus protecting pedestrians on the footpath below, while also preventing undermining of the curtain wall of Edinburgh Castle”.

HES stressed in a separate statement there was no risk to the public at present with access restricted to the area and the footpath sealed off.

A report from geologists at Fairhurst Engineering said the problem area, which measures roughly 10m by 6m, was inspected in 2019 and found to have “significantly deteriorated” during a further inspection in July 2021.

A report said: “The potential consequence in this area are two-fold and potentially impact the fabric of the castle structure and the users of the park below.

The problem sits to the south west of the castle complex under the New Barracks, which later served as the army's piping school. PIC: CC/Kim Traynor.

“There is no evidence that there is an imminent failure of a scale that is likely to undermine the castle walls, but given the potential for the further development and increased rate of deterioration it is thought prudent that HES are made aware of the situation and able to consider planning for works to secure both the upper slope and the castle walls.”

“It is assumed that the castle wall exerts a static load onto to the rock slope and is reliant on the rock slope for bearing and support. It is also unknown how thick the wall is and what material is present behind.”

Parts of the rock surface had suffered “relatively rapid deterioration” since 2019, geologists found.

The report said: “If this cycle were to continue, there is the potential that the instability will gradually extend back toward the wall where support could be significantly reduced, potentially influencing the integrity of the castle walls.”

Water ingress and the penetration of plant roots into the joints of the rock are the main divers for the “general deterioration” in the stability of the outcrop, the report added.

Rockfall netting, which adds pressure to the rock to stop it from moving further, will be placed over the problem area with anchors to be drilled into the castle wall. Some repointing will also take place.

A statement from HES said: “As part of a routine inspection, our specialist geotechnical engineers discovered some deterioration in an area of the rock slope at Edinburgh Castle.

"There were no immediate rockfall concerns and the rock slope is above an area which is closed to the public. As part of our annualised programme of works, we have been carrying out works to the area, including de-vegetation, and we have now applied for scheduled monument consent to install containment netting and carry out pointing works to the rock. This work forms part of our routine rock risk management.”