2022:731 - Letterilly and Gortnamucklagh, Donegal

An Bord Pleanála gave approval to Donegal County Council for the construction of the N56 Leitirmacaward to Glenties (Kilraine) national road scheme. This report relates to archaeological monitoring of the N56 Letterilly to Glenties section of that scheme. Directions were issued to Donegal County Council by the Minister for Housing, Local Government and Heritage in respect of the archaeological requirements of the scheme (Ministerial Directions Number: A065). Following the completion of the Environmental Impact Assessment (RPS, 2011) the proposed route was subject to a testing programme (E005014) followed by archaeological excavation of exposed material in 2019 (E005040).

An area set aside as a permanent topsoil deposition area was tested by Billy Quinn in 2021 (Extension to E005316).  Several areas were previously unavailable or unsuitable for investigation.

This report relates to archaeological monitoring of these areas carried out by the author, Declan Moore, assisted by archaeologists Billy Quinn, Will Anderson and Tamlyn O’Driscoll between January 2021 and September 2022 and the results of an archaeological strategy to protect a ringfort site (DG074-001---) which is immediately adjacent to the road take. The work was carried out under an Extension to E005316.

Area MA01

Area MA01 is in Letterilly townland and comprised an area of peat at the north-western end of the road from Chainage 20568 – Chainage 20695. This area was unsuitable for testing in 2018 as it was tree covered. This section measured roughly 130m in length. A temporary access track was excavated from the existing N56 to the north, and excavations were carried out to facilitate road construction from the southeast to the northwest.

Archaeological monitoring at MA01 took place between in May and June 2021. The stratigraphy was consistent throughout and comprised 2-3m of peat overlying a compact grey to whitish natural subsoil with outcrops of bedrock. A deposit of burnt material and burnt stone was observed in the northern section face at chainage 20890. This material was located roughly 25m southwest of the site of Litterilly 1 which was excavated in 2019 (E005040). The deposit represents the spoil resulting from the excavation of Letterilly 1. Nothing of archaeological significance was noted during the monitoring.

Area MA02

Area MA02 is in Letterilly townland and comprised an area of peat at the north-western end of the road from Chainage 21447 – Chainage 21658. This area was unsuitable for testing in 2018 as it comprised steep slopes and frequent outcrops of bedrock. This section measured roughly 200m in length. A ringfort – cashel (DG074-001----) is located 8m south of the landtake for the scheme at this location.

A monument protection strategy was prepared in consultation with all relevant parties (including the National Monuments Service) to protect lands adjacent to the monument from collapse or erosion and thus protect the area outside the landtake on which the site is located from being undermined or destabilised.

Excavations were carried out to facilitate road construction from the southeast to the northwest. Soil nailing, slope-facing matting, rock netting and a bolting system were installed in the vicinity of the ringfort – cashel.

Archaeological monitoring at MA02 began in January 2021. Regular site inspections were carried out at this location throughout the duration of the works. The stratigraphy was consistent throughout and comprised topsoil and sod overlying a shallow mid-brown subsoil directly over bedrock. There were frequent outcrops of bedrock, particularly on the steep slope adjacent to the ringfort - cashel. Nothing of archaeological significance was noted.

The following measures were taken to ensure that the lands adjacent to the monument, within the landtake for the works, would not experience collapse or otherwise undermine, destabilise or cause damage to the monument. Soil nails, slope-facing matting, rock netting and a bolting system were installed in the vicinity of DG074-001. The soil nailing began in August 2021. The closest nail was 2.5m horizontally & 6.5m vertically away from the monument.

A staged approach methodology was adopted. This entailed excavating the cutting at 3.5m drops and leaving a 5m flat bench for the drilling rig to sit on.  This bench also ensured the stability of the slope on a temporary basis.

No further excavation took place until the soil nails were in place. Once soil nails were in place the contractor continued to excavate in 3.5m drops and repeated this process to the base level of the new road. Prior to works commencing, noise and vibration monitors were set up within the area to record data from the works. This data was downloaded regularly to ensure compliance.

The author was present to liaise with the contractor on the start date of operations and thereafter there were regular intermittent inspections to ensure the safeguarding of the site in compliance with the agreed strategy.

No disturbance of the ringfort occurred during the works.

Area MA03

Area MA03 is in Letterilly townland and comprised an area of peat at the north-western end of the road and comprised two separate elements. To the north of the mainline a sideroad was constructed (Chainage 0 – Chainage 166). This area comprised a steep, wooded slope and was deemed unsuitable for testing in 2018 for safety reasons. Monitoring of works at this location took place in February and March 2021. During the works an area to the south, within the landtake for the road between Chainage 21970 and Chainage 22200, was also inspected. At this location there was a requirement to remove an additional amount of peat beneath the footprint of the road alignment. These works were inspected in April and May 2022. Nothing of archaeological significance was noted.

Area MA04

Area MA04 is in Letterilly townland and comprises an area of deep peat. The peat depth in the centre and at the southeast and north parts of this area reaches up to 7m. No excavation work was carried out by the contractor for the deposition of topsoil. Given the depth of the peat and the fact that no excavation works were anticipated in this area, it was agreed in consultation with Orlaith Egan (TII Project Archaeologist) and the NMS that Declan Moore intermittently inspect the works to ensure that no features of archaeological potential were present or could be disturbed by movement of tracked excavators within the peat. Intermittent inspections were carried out at this location throughout 2022.

An additional topsoil storage area was originally proposed for similar works in Letterilly (TSA03). Subsequently, construction-related works did not proceed in that area and an alternative area was proposed (MA04 extension) and agreed upon with the relevant parties. The topsoil deposition is located to the south of the roadtake between approximately Chainage 22737 – Chainage 22905.

Additional works within the roadtake were carried out between Chainage 22,840 and Chainage 22,950. Inspections were carried out at this location as the overall construction methodology had been altered in this surcharge area by excavating previously undisturbed underlying peat. Inspections at this location were carried out in May and June 2022.

 

 

 

3 Gort na Rí, Athenry, Co. Galway