2008:427 - River Liffey, 100m upstream of O’Connell Bridge to Butt Bridge, Dublin

Intertidal and underwater archaeological assessment of a 350m section of the River Liffey was undertaken as part of the proposed Metro North Project on behalf of the Railway Procurement Agency. Proposed works in the Liffey include the construction of a temporary pontoon deck to the east of O’Connell Bridge and the construction of a temporary, decked bailey-bridge connecting Marlborough Street and Hawkins Street. The survey commenced 100m upstream of O’Connell Bridge and continued downstream to Butt Bridge.
The assessment area retains a number of features of historic interest that include two 19th-century quayside structures (Burgh Quay and Eden Quay; DU18–020–461), a bridge structure of late 18th- and 19th-century date (Carlisle/O’Connell Bridge), and a 19th-century timber revetment associated with Burgh Quay. In addition, a possible fording-point was encountered upstream of O’Connell Bridge.
Systematic visual inspection of the sub-tidal area consisted of c. 19978m2 of riverbed, the base of both attendant quayside structures, and those sections of riverbed located under O’Connell Bridge. Detailed descriptions were made of riverbed topography, bottom composition, and the existing river environment; recording all changes in substrate, flora, and fauna encountered as part of the survey. In addition, a probe survey was undertaken to record sediment levels within identified riverbed areas. A series of river profiles were also taken, mapping the topographic changes encountered across the riverbed. Three underwater video surveys were also carried out and included the detailed video documentation of the riverbed areas along the base of the central pier structure, and the base of Burgh Quay and Eden Quay. No material, structures, or deposits of archaeological significance were encountered as part of the underwater survey.
A systematic visual inspection of all exposed intertidal riverbed areas was also undertaken (at Low Water), allowing a detailed written and photographic record of any features encountered to be made. This record was supplemented by GPS position-fixing and total-station survey. Particular attention was paid to the inspection and recording of a timber revetment located along the northern half of Burgh Quay. In addition, two sections of quayside located within the impact area for the proposed temporary Marlborough Street Bridge underwent detailed survey, recording the quay structures in plan, cross-section and elevation.