Archaeological investigations carried out ahead of a major gas infrastructure project in Co Westmeath have uncovered evidence of medieval settlement dating back as far as 1,600 years.

The discoveries were made during pre-construction works for the Kiltotan gas transmission pipeline, which runs for 5.5 kilometres through the townlands of Kilbrennan, Collinstown and Oldtown. The pipeline will supply gas to the Castlelost electricity generation plant near Rochfortbridge.

Commissioned by Gas Networks Ireland, the archaeological investigations were led by Dr Rose Cleary of Archaeological Consultancy Services Unit (ACSU) as part of the company’s code of practice for major pipeline works. The site was subject to an Environmental Impact Assessment and licensed surveys under the supervision of the National Monuments Service.

A geophysical survey in April 2024 identified five previously undocumented archaeological sites. Excavation works followed, with 56 test trenches completed by November 2024. The findings include postholes, pits and a circular enclosure linked to a medieval field system. Artefacts recovered from the site include stone-lined cereal drying kilns, pottery, flint tools and clay tobacco pipes.

Most of the site has been preserved in situ while selected features were excavated by hand and removed for conservation. Post-excavation analysis including radiocarbon dating of charcoal and seeds has been completed. Final reports are expected before the end of the year.

Maeve O’Reilly, Senior Environmental Engineer at Gas Networks Ireland, said the company takes its responsibility to protect Ireland’s archaeological heritage seriously and coordinated closely with specialists and landowners throughout the project.

Dr Cleary said pipeline construction often reveals hidden archaeological sites beneath modern landscapes and that the Castlelost project contributes valuable insights into the historic environment of Westmeath.

Donald Murphy, Managing Director of ACSU, described the site as offering an extraordinary glimpse into how communities lived and worked over the centuries.

More information and a video about the Gas to Castlelost project is available here.