2006:1083 - Mullinabro, Kilkenny

Monitoring of groundworks in Mullinabro townland was carried out in an untested area during construction of the N25 Waterford city bypass (Mainline Chainage 12060–12510). The groundworks involved the excavation of a culvert channel to remove a meander of Strangsmill Stream, which extends into the road corridor, and to divert the watercourse into the area to the north of the proposed road. This area of the stream flood-plain is tidal and the ground conditions were subject to waterlogging at the time of monitoring. The diversion channel measured c. 100m east–west by 6m wide and its depth gradually increased from 1.5m at the east end of the channel to 2.5m at the west end.
The exposed soil profiles consisted of a peaty sod/topsoil layer (0.1–0.2m deep) that overlay a yellowish-grey alluvium clay deposit (0.5m average depth). This sealed a mid-grey alluvial silty clay deposit (0.25–0.5m depth), which in turn overlay a homogenous layer of mid-brown peat that was still present at the maximum excavated depth of 2.5m below existing ground level in the west end of the diversion channel. A filled-in drainage ditch extended north-west to south-east through the area impacted by the diversion channel. This was U-shaped in profile and measured 0.8m deep by 1.4m wide. It was cut into the uppermost yellowish-grey alluvial deposit and was filled with a sterile greyish-white silty clay deposit. All of the exposed soil deposits contained moderate amounts of reeds and some non-archaeological wood. No archaeological features or deposits were exposed and no finds were recovered during monitoring of the excavation of the diversion channel. Soil samples were taken from the alluvial deposits and the underlying peat in case they are required for environmental analysis. The remainder of construction works in this untested area will be creating a road embankment on existing ground levels and no further ground-reduction works will be carried out.