2016:037 - Mercer Street, Dublin, Dublin

A programme of archaeological monitoring was carried out within St Stephens Ward, Dublin in the historic core of the city (RMP DU018-020) in October and November 2013 by the author on behalf of Bord Gais Networks.
The works involved the laying of approx. 125m of 180mm PE main extension along an existing road in an open cut trench from the junction of Bow Lane East and Mercer Street Lower to Johnson Place. The trench dimensions were approximately 700mm-1.3m deep by 500mm wide.
Groundworks involved the cutting of the existing road surface and the machine excavation of underlying material along a trench that ran NE/SW along Mercer Street. The general stratigraphy was a mix of modern and 19th century fills typically made up of a grey brown, compact silty clay with inclusions of red brick, cast iron and occasionally ceramic pipe fragments.
Monitoring took place along a 125m long open cut trench extending from the junction of Bow Lane East along Mercer Street terminating at an existing gas main at Johnson Place. Work took place over five weekends between September and October 2013. The works were subject to archaeological supervision due to its proximity to the historic city of Dublin (RMP DU018-020) and the three RMP sites. The trench measured 500mm in width and was dug to a maximum depth of 1.3m. Typically the road surface was cut and removed by a tracked mini digger, where possible the ground was machine dug but some manual excavation was involved in order to avoid assorted modern services including water, sewerage, electricity etc. Older services included the redundant remains of a red brick culvert/wall and occasional cast iron and ceramic pipes. Given the frequency of the services and the relative shallowness of the trench all the exposed material consisted of composite modern aggregates and 19th -20th century redeposited fills. Generally the stratigraphy consisted of a layer of tarmac (250mm) over road base (150-300mm). Discounting modern service fills, the underlying material was composed of a compact, grey/brown, silty clay with frequent small stones and gravels continuing to the trench base. Throughout the length of the trench there were inclusions of red brick, fragments and pockets of ash, mortar and sand. Nowhere along the length of the trench was natural ground exposed.
In order to minimise traffic disruption the road crossing from Bow Lane east to the eastern carriageway of Mercer Street was partially carried out at night. Near the center of the road groundworks at the base of the trench exposed an isolated spread of well packed cobbles in a sandy bed (NGR 715604/733566). The cobbles were sub angular in shape and averaged 8cm in length. The cobbles were located at a depth of 1.3m below the modern road surface and it was possible to decrease the depth of the trench to ensure that these cobbles were retained in situ.
Along the length of the Saint Stephens Green Car Park the material exposed was generally made up of an upper layer of modern rubble fills with frequent services overlying the silty clay as previously described. At the junction of Mercer Street and Johnson Place there was a compact grey white mortar rich layer at a depth of 0.7m, this layer continued northwards for approximately 4m.

3 Gort na Rí, Athenry, Co. Galway