2023:812 - River Slaney, Tullowbeg, Tullow, Carlow

Underwater Archaeological Impact Assessment (UAIA) was undertaken of the River Slaney within Tullowbeg Td., Tullow, Co. Carlow, where an upgrade to the existing Tullow Waste Water Treatment Plant (WWTP) is to take place. As part of the upgrade works, it is proposed to insert a new outfall structure on the west bank of the River Slaney at ITM 685345E, 672791N (centrepoint). In addition, a new combined sewer pipe will cross the river between ITM 685328E, 672842N and ITM 685341E, 672849N, at a point 17.5m downstream of an existing sewer pipeline (c. 96m upstream of the proposed outfall), which is to be decommissioned. It is planned to directionally drill the sewer-pipe at a depth of -2m beneath the existing bed-level. As a result, direct impact to the upper riverbed is not anticipated at this location. However, the riverbed surrounding the crossing point was also included within the assessment area, allowing for any future potential change to construction phase measures at this location.

The UAIA comprised systematic visual inspection of a 128m section of the River Slaney, extending 37m upstream of the proposed crossing point, and 24m downstream of the outfall location, ITM 685306E, 672874N - ITM 685353E, 672768N. A walkover survey of the attendant bank structures was also undertaken and targeted metal detection employed to help assess the bankside/riverbed area and highlight any metallic concentrations present.

Two features of archaeological interest were encountered within the river assessment area:

Feature 1 comprises a c. 35m-long section of nineteenth-century river-wall, located on the west side of the watercourse: ITM 685335E, 672816N and 685346E, 672783N. The structure is roughly-coursed with rough-cut limestone masonry comprising up to four visible courses, although it is only the topmost course that is visible along much of its extent. The masonry varies in size/shape, ranging between 200mm-4000m length and 120mm-380mm width. The wall structure is similar in appearance to Feature F02 and is likely to be a contemporary build. The proposed outfall structure will directly impact the southern terminus of this feature (c. 8m section).

Feature 2 comprises a c. 64m-long section of masonry boundary wall, delineating the riverside extent of an adjacent burial ground (Mallawn Cemetery), located on the east side of the watercourse (ITM 685360E, 672831N to ITM 685365E, 672770N). The OS 25-inch Map (1906) shows a riverside boundary wall that corresponds with the alignment of this feature, indicating that the structure was in situ at that time and was most likely constructed in the nineteenth century.

No other archaeologically significant features, structures, or deposits were encountered for the area under assessment. Likewise, metal detection across a series of riverbed areas did not yield any items of interest.

The assessment was carried out on 16th January 2023, under licence from the DHLGH.

ADCO completed detailed archaeological recording, including laser-scanning, of Feature 1 on 24 May 2024.

Archaeological Monitoring of the removal of a 7m-section of the feature was undertaken by ADCO on 6 August 2024, under the  wider project excavation licence (22E0086, held by Pádraig Dunne of TVAS Ireland). The wall-section was removed in a systematic and controlled manner, with associated bankside spoil undergoing metal detection. All masonry removed from the structure was stockpiled for reuse, subsequently being used as rock-armour protection, placed on either side of the headwall for the outfall.