2012:202 - Dorset Street Upper/Parnell Street/Dominick Place/Marlborough Street/Hawkins Street/D’Olier Street/College Street/College Green/Broadstone, Dublin, Dublin

A programme of monitoring was undertaken of the excavation of 15 utility slit trenches along the proposed route of Luas Broombridge (Luas BXD). The purpose of the utility slit trenches was to investigate the size, type, level, gradient and position of all existing utilities and associated fixtures, including any underground culverts, basements, chambers etc. along the route of the proposed scheme. Most of the trenches were located within the zone of archaeological potential for Historic Dublin (DU018-020; AC1) and all were located in proximity to sites recorded in the Record of Monuments and Places and/or areas of archaeological potential, as outlined in the Luas Broombridge Environmental Impact Statement. On that basis it was determined that a programme of monitoring should be undertaken in conjunction with the excavation of these trenches.

No significant archaeological features or deposits were encountered, with the exception of Trench ST-121 on Parnell Street where a triple barrel vaulted post-medieval cellar of likely 18^th-century date was identified and Trench ST-104 where collapsed bonded red brick material associated with a cellar structure was identified along with the a brick-build culvert. In addition a stone-lined lintelled drain and associated metalled surface (most likely of 19^th-century date), was identified in Trench ST-103 and a collapsed red brick wall was identified within Trench ST-102. However, it should be noted that the utility slit trenches were limited in scope and were targeted and positioned at locations with high levels of disturbance (where in situ services are currently located). Therefore, in situ archaeological features or deposits could survive outside of the areas directly investigated.

Following on from this, seven utility/archaeological slit trenches were excavated at various locations within the forecourt of the old Broadstone MGWR Railway Terminus (‘the Broadstone building’) and within the Dublin Bus Phibsborough Depot at Constitution Hill. The locations were selected using information from historic mapping, with the aim of establishing (where possible):

• the location of the canal/harbour walls and any associated structures
• the width of the canal/harbour walls
• the nature and condition of the canal/harbour walls, nature of the fill, the canal banks and any associated structures

Evidence for structural remains associated with the canal channel or harbour was identified in trenches ST-127 and ST-128 only. Taken in conjunction with the results from the previous investigations in 2010 (T. Doyle, Licence No. 10E0090) this would suggest a substantial section of the original canal channel walls remain in situ to the east of the main entrance to the Broadstone building.

No indications of any in situ structural remains were identified within the trenches located to the west of the main entrance of the Broadstone building. Significantly, the southern limit of the canal channel was not encountered in either ST-125 or ST-126. This means that the exact location, character and condition of this section of the canal channel remains unconfirmed. There were also no indications of any surviving structural remains demarcating or defining the footprint of the canal harbour which is located beneath within Dublin Bus Phibsborough depot (ST-122–ST-124). However, a possible cut into natural boulder clay in ST-124 may mark the eastern limit of the harbour and might suggest that any stone elements which may originally have lined the sides of the harbour had been deliberately removed.

The basal deposits in all seven trenches tended to be waterlogged. In particular a black organic clay deposit was encountered both in the canal channel (ST-125 and ST-128) and canal harbour (ST-122 and ST124) and contained obvious wood and plant fragments suggesting a high potential for anaerobic preservation at the site. This was confirmed by the discovery of a timber in ST-122 that remains in situ. There is a clear potential that additional wooden or timber features could survive at the site. In particular, there is a high potential that any scuttled or sunk canal vessels that were left in situ during the demolition or decommissioning of the canal spur line and harbour will be well preserved at the site.

Rubicon Heritage Services Ltd, Unit 2, Europa Enterprise Park, Midleton, Co. Cork