EHG6506 - Walkover survey - Beauly to Loch Buidhe to Spittal 400Kv Overhead Line

A walkover survey and setting sensitivity assessment were undertaken by AOC Archaeology Group in 2024 to inform the Environmental Impact Assessment (EIA) report on the alignment and routing of a proposed 400kV Overhead Line (OHL), to extend from Beauly to Loch Buidhe as the South alignment, and from Loch Buidhe to Spittal as the North Alignment. The proposed development alignments were refined during the programme of work, with sections added and removed as the design progressed through various consultations and revisions. Walkover and windscreen surveys were also undertaken for proposed permanent and temporary access tracks. This subsequent data structure report (DSR) presented the findings in detail as they pertained to the November 2024 route alignments and access arrangements provided to AOC. The assessment identified the historic environment baseline of the proposed development inasmuch as was possible for the scale of the proposal, using defined survey corridors to identify the known upstanding heritage resource present within the potential works areas for the overall proposed development’s alignment, where access was available, and to infer the archaeological potential for hitherto unidentified archaeological remains within those corridors based on the presence of similar remains within the local surrounds up to 1km distant from the alignments. Potential direct impacts to the known heritage resource within the project area were considered and mitigation advice specific to those assets was presented. The walkover survey was begujn in April 2024 and extended across summer and into autumn, and as a result vegetation in some areas of the survey corridors was obstructive for surveying. These conditions were incorporated into the findings. All assets identified during the walkover survey were included within the project gazetteer, but only those assets that stood within the survey corridor as it pertained to the November alignment were discussed. Site visits were undertaken to designated heritage assets where accessible. These site visits established the current setting of the assets, how setting contributed to the understanding, appreciation and experience of the assets and an assessment of how sensitive these assets were to changes in their setting to form a baseline for the setting assessment within the EIA report. The assessment considered the archaeological potential across the alignment corridors to range from Negligible to High, with archaeological importance of assets similarly ranging from Negligible to High. There was considered to be a Low potential generally for remains of Early Historic, Medieval and Modern date. The High potential across portions of the route was predominantly for post-medieval archaeological remains, with prehistoric remains following. The archaeological importance of such assets generally ranges between Negligible and Low for the post-medieval remains, and while broadly similar for the prehistoric period archaeological remains, there were some instances of potentially Medium and High importance archaeological remains to be present. As a broad rule, this archaeological potential was highest within the more sheltered areas of the alignment, within settings such as straths, glens or broad south and southeast-facing slopes, which offered hospitable environments for settlement and agricultural activities. The archaeological potential tended to diminish in the very upland and less hospitable portions of the alignment corridors. Direct physical impacts on both the known and unknown archaeological remains could result in a High adverse effect on the archaeological resource. It was advised that a detailed mitigation programme, area specific and incorporating the survey findings, should be prepared in advance of any ground-breaking works. Depending on the results of these investigations further archaeological works may be required. The scope of any such works would be required to be agreed via a Written Scheme of Investigation with the Highland Historic Environment Team as advisors to the Highland Council on such matters. <1> <2>