1997:123 - DUBLIN: 37–41 East Essex Street, Dublin

Archaeological test excavation was carried out at the Project Arts Centre, 37–41 East Essex Street, Dublin 2, in conjunction with engineering site investigations by Ove Arup and Partners on behalf of Temple Bar Properties Ltd. The site lies within the original estuary of the Poddle/Liffey confluence at its eastern side. The Poddle culvert passes beneath the southern and eastern limits of the development area. The archaeological appraisal of the site was undertaken in response to a condition in the grant of planning permission for the scheme and was carried out over three days in early April 1997.

The assessment was based on the examination of seven engineering test-pits and one long test-trench. These were opened by hand and by mini-digger inside the standing theatre buildings. The assessment sought to ascertain the position and nature of the Poddle culvert and the location of the uppermost level of underlying archaeological deposits. On the basis of inspection at adjacent sites, the archaeological presence on this site was likely to be seen as foundations of primary and secondary buildings (17th–18th-century), and below these the organic silt accumulation of the Poddle estuary. These deposits can be up to 4m deep where bedrock on the old river shoreline deepens sharply along the Essex Street frontage (seen in the Essex Street frontage of the Meeting House Square development). Much of the organic silt in the ancient estuary appears to have accumulated rapidly after the building of the Anglo-Norman city wall.

The new complex will not have a basement but subsurface works will penetrate to a depth of between 1200mm and 1500mm. Where the existing Poddle culvert is present beneath the centre, the proposed structure will be cantilevered over it.

Test-pit 1 was opened on both sides of one of the internal walls of the present complex under which the culvert runs. The northern limit of the culvert was defined but the excavation area was too constricted to expose the structure for archaeological examination. It was covered by loose fill and red brick rubble in a brown garden-type soil.

Test-pit 2 was opened for engineering purposes and revealed a loose rubble fill to a depth of just 700mm and the foundation of the party wall to the west, which was just 300mm deep.

Test-pit 3 revealed a concrete foundation to the party wall to the west, which was exposed to a depth of 1.3m, and excavation did not continue below that depth. It is assumed that the loose fill in this location represents a backfilled basement.

Test-pit 4 was an irregular shape as it had to be opened around standing walls. The supposed 17th-century tail-race wall was exposed in this location 0.5m to the west side of the culvert and at a depth of 1.6m below present ground level. It was exposed to a depth of 0.25m and was sealed by the (later) red brick wall of the present building, to the east, which was made of roughly unstructured mortar, limestone and red brick.

Test-pit 5 was a large irregular pit measuring c. 1.7m east-west by c. 3.2m north-south and 1.8–2m deep. The complete width of the roofed culvert (2.5m) was exposed at a depth of 1.4m below present ground level and it was seen to be built of mortar, limestone and red brick. At a distance of 0.5m on its northern side the supposed 17th-century tail-race wall was exposed at a depth of 1.35m below present ground level. This wall is made of solid limestone blocks. The culvert also meets another, smaller channel which feeds into it from the west at this point.

Test-pit 6 revealed only red brick backfill and no archaeological deposits were encountered. It is considered likely that a basement existed in this location and that the overall depth of rubble is likely to be in excess of 2.2-2.5m.

Test-pit 7 measured 2m east-west by 2m north-south and was a maximum of 2m deep. The arched brick roof of the Poddle culvert was exposed in the south-east corner of the trench at a depth of 1.7m below present ground level. The arch was covered and sealed by rough mortar, limestone and red brick. The exterior is not faced, indicating that the structure must have been built from the inside out. This contrasts with the length of the culvert exposed at Dublin Castle by L. Simpson (Excavations 1994, 22–3, 94E074), where the exterior was faced. At Dublin Castle, the exposed 4.05m width of the culvert was not its full width. The solid limestone wall of the 17th-century tail-race was located running parallel to and 0.45m west of the side wall of the culvert on the west side of the trench. This lay at 1.55m below present ground level. As in Pit 5, it appears to have been replaced by the present culvert wall in this location when it was bricked over. The culvert and the possible 17th-century wall were each sealed by a c. 0.5m-thick layer of fill and the wall of the present building, which has a pronounced red brick batter.

Test-trench E was opened across the floor of the auditorium. The full width of the culvert was exposed at the southern end, where it measured 2.8m, and the roof appeared to rest on the 17th-century limestone walls. The remains of a red brick drain orientated east-west and measuring 0.5m wide by 0.2m high crossed close to the northern wall of the structure, partly obscuring it. The remainder of the trench continued in a north-south direction through the existing theatre floor.

It was originally planned to open the full length of the trench (15m) to expose the upper surface of the archaeological deposits. A decision was made, however, based on the archaeological findings (and in deference to the requirements of the occupants to shorten the work), to open a series of pits along its length instead. In all, five 2-3m-long pits were opened, each displaying a similar profile of rubble fill to a depth of over 2.3m, i.e. the full reach of the 'mini'-excavator. In all cases, the rubble fill material was not bottomed and it can be assumed that this fill extends right across this portion of the development area.

The proposed new structure will rest on a foundation of piles (likely to be 300mm odex-type piles) and there will be no pile caps. The scheme, therefore, will have quite a minimal impact on the estuarine mud and organic deposits which almost certainly underlie the rubble fill exposed.

During building development works and immediately after demolition and site clearance works the opportunity to examine the precise nature of the 17th-century tail-race of the Poddle will be provided. In addition, the trenches cut for ground-beams will be examined for early red brick wall foundations. If the precise nature and stratigraphic sequence of the Poddle estuary bed is also to be established, an additional north-south trench is to be opened right through the site post-demolition and pre-development.

Rath House, Ferndale Road, Rathmichael, Co. Dublin