2011:181 - Blackrock, Dublin

The Dublin Region Watermain Rehabilitation Project is an initiative intended to tackle the high level of water leakage from within the water distribution network. The project will seek to identify those areas of watermain infrastructure yielding the greatest sustainable water savings throughout the Greater Dublin Region (GDR). The GDR for the purposes of the project consists of the county council areas of Dublin City, Fingal, South Dublin, Dun Laoghaire–Rathdown and parts of Kildare and Wicklow. To date, the project has recommended mains in 55 DMAs for rehabilitation.
On the basis of the techniques which were to be used, a series of five scenarios for determining the level of monitoring were agreed with the City Archaeologist and the National Monuments Service. In March 2009 these scenarios were reviewed and amended on the basis of the results of the monitoring on this project to date. As a result of this review only two scenarios necessitated archaeological attendance. In Scenario 1, where open-cut trench excavation is carried out within 30m of RMP/within ZAP, full-time monitoring is required if there is no existing main within the trench; intermittent monitoring is required where the trench is excavated over an existing main. The second scenario requiring monitoring is Scenario 5: where any excavation technique is to be used within 10m of a National Monument, full-time monitoring is required.
There are four archaeological monuments within the Blackrock DMA: a Martello tower (DU023-002) on the coast, a cross at the Main Street in Blackrock village (DU023-005), and the site of a possible castle (DU023-008) and holy well (DU023-009) on the south-eastern edge of the DMA. All four RMPs are located directly within those areas that were to be subjected to watermains rehabilitation.
While a licence had been issued for monitoring in 2009, the bulk of the groundworks associated with the DMA were not carried out until 2011. Therefore an extension to the licence was granted in March 2011. Monitoring of works in this DMA was carried out on occasions between January and June 2011. The works that formed part of the Blackrock DMA consisted of monitoring in the vicinity of the cross (DU023-005) at the junction of Main Street, Carysfort Avenue and Temple Road and in the vicinity of the holy well (DU023-009) in Maretimo Gardens East.
The process of rehabilitation involved either the exposure of the existing watermain or the excavation of a new trench for a new pipe (new-lay). This was generally carried out with the use of a mechanical excavator of either JCB type or a smaller ‘mini-digger’ type. Where necessary, some of the trenches were also excavated by hand.
The works undertaken in the vicinity of the cross consisted of mainly open-cut trenches. The trenches measured approximately 0.5m in width and ranged from approximately 0.6m to 1m in depth. In some cases larger areas were opened to expose the junction between a number of watermains. Following the removal of the upper surface of tarmac, the underlying hardcore/sand was removed. Below this the entire trenches were backfilled with modern deposits containing modern ceramics and building waste. Neither material nor features of an archaeological nature were exposed during the excavation of these trenches. The work in Maretimo Gardens East was initially intended to be open-cut but upon the excavation of trial pits it was decided to undertake pipe-bursting. A trenchless technique was employed in the vicinity of the Martello tower (DU023-002) along Seafort Parade.
No archaeological features, deposits or artefacts were revealed during monitoring of these groundworks.

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