2013:018 - CAHERDOWNEY, Cork

The Millstreet 220/110kV Substation Project, comprising the construction of a substation complex with associated access road, construction of five masts and the provision of approx. 4.8km of a buried cable line from the substation to an existing substation at Garow, Co. Kerry, is presently being undertaken by EirGrid and ESB Networks. Planning permission by An Bord Pleanála for the development required that all excavation works be monitored.
Monitoring of site preparation works/topsoil stripping onto the surface of the underlying sterile subsoils associated with the construction of the substation at Caherdowney townland was undertaken on a phased basis from 14 December 2012 to 14 March 2013. The works included the site access road and entrance, service roads, overall extent of substation and associated fencing areas, and drainage elements. In addition, topsoil stripping for the temporary construction compound and a temporary service road for temporary dumping of topsoil was also monitored.
In general, all topsoil stripping was carried out by mechanical excavators fitted with wide toothless ditching/grading buckets, except for the southern section of the access road and entrance from the L5226 road. This area had been planted by forestry and a toothed bucket was used to remove the associated stumps and roots, following which bulk excavation works were undertaken. A layer of peat, up to 0.85m in depth, was removed from this area, revealing compact grey sandy silty clay ‘natural’ sterile subsoil. Excavations elsewhere within the site were undertaken in improved grasslands/pastureland. In general, removal of dark brown silty clay topsoil for the access road and temporary construction compound, which was up to 0.25mm in depth/thickness, revealed a moderately loose layer of mixed peat and subsoil. This layer was formed by previous agricultural improvement works to former moorland, whereby the lands were deep-ploughed, the subsoil mixed with the peaty topsoil, harrowed and rolled, with the surface planted with grass to form pasture. Removal of this layer, which was up to 0.3mm in thickness, revealed the disturbed surface of the sterile subsoils which, in areas, incorporated spreads of disturbed rust-orange iron panning. Similarly, excavations works associated with the substation areas and associated service roads revealed a layer of mixed peat and subsoil under the surface layer. Subsequent bulk excavations in these areas revealed the mixed layer to be 0.3–0.5m in depth/thickness and that it lay directly on sterile subsoil, the surface of which was previously disturbed. However, no evidence for a ‘mixed-layer’ was encountered at the northernmost area of the development site where a new drainage ditch was required, or in the area of the attenuation structure and percolation area where removal of shallow peaty topsoil revealed the surface of the underlying subsoil.
Nothing of archaeological interest and/or potential was noted during the programme of monitoring. However, three sherds of pottery, four fragmented clay pipe stems and a fragment of clay pipe bowl, all of probable 19th-century date were recovered, all from the intermediate ‘mixed-layer’ between the sod/topsoil and subsoil horizons.
It is anticipated that further monitoring of works associated with the construction of masts and cabling will be undertaken during 2014.

7 Cnoc Na Greine Square, Kilcullen, Co. Kildare