2016:449 - 98-99 Francis Street, Dublin, Dublin

The assessment was carried out on 9 May 2016 and involved the re-excavation of Test Trench 3 that was originally excavated by O’Carroll in 2005 in the northern part of the site. Previous testing in 2005 failed to identify archaeology in the southern plot (No. 98) and the remains of cellars/basements of 19th-century date that fronted onto Francis Street removed any potential archaeology in the eastern part of the site.

Demolition debris overlay natural subsoil in the western part of the site. A wall of possible 17th-century date was identified in Trench 3 (Plot 99) and the purpose of the current works was to further assess and record this wall. During the current investigations, a trench excavated in this part of the site at the location of the wall failed to identify it. A red brick basement that was plastered internally occupied a large portion of the site and was presumably part of a building of 19th-century date that occupied No. 99 Francis Street. The test trench was excavated within this infilled basement and as the supposed 17th-century wall fragment was also located within this basement, it was clearly not the remains of a 17th-century wall and was most likely a section of demolition rubble within the infilled basement that was misinterpreted. There was no evidence of any buildings identified on Speed’s map of 1610 within the test trench. It would appear that basements along the street frontage at Nos 98 and 99 Francis Street destroyed any possible archaeological deposits in the eastern part of the site to depths of at least 2.5m.

The western part of the site was also disturbed and no archaeological deposits were identified during testing in 2005. The current assessment failed to identify any archaeological features or finds.

In addition to the archaeological works, two boreholes and two test pits were excavated to assess ground conditions in advance of preparing a suitable foundation design for the site. This element of the works was carried out under archaeological supervision. The boreholes and test pits confirmed the evidence from the archaeological investigation, with 2.5m deep basements overlying brown natural boulder clay along the eastern part of the site and 2m of rubble fill overlying brown boulder clay to the west.

The proposed foundation design will consist of ground beams constructed on piled foundations. Throughout the foundation footprint, the existing ground level will be reduced by approximately 0.5m to accommodate the ground beams and sub floor. This will impact on the upper levels of the 19th-century basements and the piles will penetrate the basement floors. As no pre-19th-century material/structures were exposed during the testing of the site, the impact from the ground beams is considered minimal to archaeology.

The geotechnical site investigation work confirmed that the horizons below the basement floors consisted of natural boulder clays and there will therefore be no impact on archaeology along the east side of the proposed development. At the west end of the site, a proposed attenuation tank will be constructed below ground level and this will necessitate excavation in this part of the site to depths of at least 2m. Although test trenching in this part of the site did not reveal any archaeological deposits, the proposed excavation area here extends to 6m by 3.3m in an area where 19th-century basements were not present.