2019:508 - River Dodder and River Liffey, Dublin City, Dodder Public Transport Opening Bridge Project, Dublin

Underwater Archaeological Impact Assessment (UAIA) of two sections of the River Liffey was carried out, at a point close to the confluence of the River Dodder/River Liffey, upstream of the East Link Bridge. The assessment was undertaken as part of the planning process for the Dodder Public Transport Opening Bridge project, a project that replaces development plans previously explored as part of the Dublin Bridges project. The latter project comprised plans to construct four new bridges, crossing the River Liffey/River Dodder between Samuel Becket Bridge and the East Link Bridge. ADCO combined a detailed UAIA with geotechnical testing of the riverbed as part of the feasibility study for that project, carried out in 2016, under DCHG licence numbers 16E0495, 16D0070, and 16R0175.

The proposed Dodder Public Transport Opening Bridge lies within a historically rich landscape, highlighted by the development of this section of the River Liffey for maritime use in the late eighteenth and early/mid-nineteenth century, Sir John Rogerson’s Quay and the North Wall Quay forming tangible reminders of that maritime industrial past.

Much of the riverbed/quayside areas impacted by the proposed bridge structure have been previously assessed by ADCO (2016). As such, only two riverbed areas required further assessment, where the new design footprint fell outside those riverbed areas previously subject to assessment. The centrepoint coordinates for these areas are as follows:
• Area A, ITM 717944E, 734247N
• Area B, ITM 718011E, 734247N
The larger of the two areas (Area A) is roughly triangular in shape, measuring 111m x 101m x 80m, and extends across both the intertidal and subtidal zones on the south side of the river channel. The smaller area (Area B), measuring 18m x 7m, is also located on the south side of the channel, immediately upstream of the East Link Bridge.

The assessment comprised systematic visual inspection of the intertidal and subtidal components at the two identified locations, undertaken on a Spring Low Water tide cycle. The assessment sought to record riverbed topography, assess the potential of riverbed deposits to retain archaeological material, and identify any additional features/structures of archaeological or historic significance that are present. In addition, targeted metal-detection was employed to help assess the riverbed and highlight any metallic concentrations present within these deposits.
No additional archaeological significant material, deposits, or structures were encountered as part the survey. The on-site work was carried out on 9 April 2019.

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