2024:822 - Timahoe North Solar Farm, Timahoe East Td, Kildare

The Grants of Planning with respect to the development of the Timahoe North Solar Farm and associated Substation and Grid Connection required that the excavations required of the development be archaeologically monitored. The entire development area is located within an area cut-over raised bog, with much of the surface still formed by remnant peat deposits; consequently, it was considered appropriate that such monitoring be undertaken under licence from the Department of Housing, Local Government and Heritage.

The subject area includes a section of the RMP Zone associated with a possible Road (unclassified togher), a small portion of which was identified in the early 1990s (SMR Nos: KD008-05; KD009-017). Research indicates that it would appear that any possible remains of the road/togher that might have been routed through the site area would have been at a higher level than that of the existing remnant bog surface and, consequently, removed during harvesting operations, particularly within the extent of the southern solar array. However, this has not been definitely proved and, consequently, it was agreed with NMS that some archaeological testing be undertaken. Four trenches were excavated through/transecting the established ZAP/N Corridor. The trenches were excavated by machine fitted with a toothless bucket; all were 2m wide and generally 1m in depth through the bog remnant but slightly shallower where subsoil was encountered. T1 measured 130m in length with the remainder all measuring 100m. T1 and T2 were excavated in areas of heather/brush surface cover, removal of which revealed the remains of in-situ bog remains. T3 and T4 were excavated in areas of a surface deposit of previously harvested peat, which was up to 0.35m in depth and sealed the underlying layer of in-situ bog, which was composed of an organic silty matrix, including minor spreads of decaying rootlets, grasses, moss, leaves and thin fragments of tree branches dispersed randomly throughout. A decaying tree trunk was uncovered at the base of T3 and a decaying tree stump and fragmented branches were uncovered in T4.

Nothing of archaeological interest was uncovered by the works; in particular, no evidence for the possible road/togher was uncovered. A 30m diameter buffer area was established around the SMR red-dot location of the monument, in compliance with the GOP.

A programme of tree felling was undertaken as a constituent of the overall development; the associated licence from the Department of Agriculture, Food and the Marine (DAFM; Licence No: TFL00659221) stipulated that a temporary exclusion area be established around the SMR ‘red-dot’ location for the above monument, pending an agreed felling plan for the zone. A methodology for such was prepared by the project archaeologist and submitted to the Forestry Service, DAFM and NMS in October 2022 and the trees/dense undergrowth were subsequently felled and removed using a tracked machine fitted with a shear/mulcher and grab; elsewhere trees were felled in a similar manner, or manually using a chainsaw, and the resultant brash/debris and stumps were left in situ, pending removal, where required, by the subsequent civil works associated with the development of the solar farm. As further required by the DAFM Licence, all such works were monitored by the project archaeologist as part of the monitoring programme required of the overall development.

The main haul road required of the development was along the route of a former industrial railway and was formed by raising the surface with stone over a layer of geotextile material laid on the existing surface; the only excavations was at the tie-in with the public road, where a new drain pipe was inserted through a depth of peat.

All the required access roads to the solar arrays were ‘floated’ and no excavations were required; similar construction processes were utilised with respect to the Contractor and Storage Compounds.

Bulk excavations were undertaken with respect to the substation and for foundation bases of the Transformers and associated crane bases; in all cases peat, with depths ranging from  0.35–4.1m, was removed to the surface of the subsoil. Other excavations were undertaken with respect to drainage, general service trenches and trenches associated with electrical connection networks (Low and High Voltage); the depths of these elements ranged from 0.9–1.7m and were generally excavated though depths of peat, although in some areas the peat was shallow, whereby the underling subsoils were also partially excavated. Similar conditions were also encountered with respect to the Grid Connection – four timber pole sets with associated stays and earth-mats and four steel lattice angle masts.

In general, apart from the removal of tree stumps, root systems and heavy undergrowth, no excavations were required of the solar arrays, the foundations of which were formed by sheet piles driven into the ground by percussion equipment fitted to mechanical excavators.

Afforestation works were also undertaken as part of the overall development, and under licence from the DAFM (Ref: CN88775), which also included an archaeological monitoring requirement. Inverted mounds were created by excavating the sod and replacing it back into position upside down, allowing the trees to be planted in the bare/exposed peat soil. In areas where there was no vegetation cover, tree planting was carried out by planting directly into the bare/exposed peat surface. All planting was done manually. Such work was also subject to archaeological monitoring.

No subsurface features of archaeological interest were uncovered by the works and no artefacts of interest were recovered.