2008:1002 - Birr, Offaly

Test excavation and monitoring were undertaken in Birr between June 2007 and January 2008 during the construction of a metropolitan area network (MAN) as part of the Shannon Broadband Project. The excavation phase of the project involved the opening of a series of trenches throughout the town centre and its surrounding hinterland. All of the trenches were located along roads, either in the carriageway proper or the adjoining verge or footpath. There were no river crossings other than at existing bridges. The trenches were 0.6m wide and excavated to a standard depth of 0.9m in carriageways and 0.6m in verges/footpaths. Junction boxes (1.25m2) were excavated where two or more trenches intersected and at regular intervals along long straight sections. Prior to development a series of three test-trenches were excavated at locations where the MAN route crossed the presumed line of the town defences at The Green, Chapel Street and Bridge Street. No archaeological features, finds or deposits were encountered during the course of testing. All works within the area of archaeological constraint surrounding the town were monitored on a full-time basis. Works outside of these areas were monitored intermittently.
Approximately 15m from the junction with Main Street/Bridge Street a stone wall was encountered traversing the trench along a north–south orientation. The top of this wall was c. 0.4m beneath the street surface. The wall was constructed from rubble masonry and had been severely damaged during the course of previous works in this area. It measured 0.6m in width and 0.5m in height, although it is unclear if these were the original measurements. It is possibly associated with the buildings indicated running along the southern side of Brendan Street on the first edition of the OS map (1838), which were removed before the second edition (1884–5) was surveyed. In order to attain preservation in situ the wall footings were covered with geotechnical membrane and the overall depth of the trench was reduced.
Approximately 13m from the eastern end of The Green a wall footing was encountered 0.6m beneath the street surface. The wall was orientated west-north-west to east-south-east and was exposed for a length of 2m, running diagonally across the trench. The exposed portion of the wall consisted of a single course of roughly worked limestone blocks averaging 0.5m in width with traces of lime-based mortar evident. In order to attain preservation in situ the wall footings were covered with geotechnical membrane and the overall depth of the trench was reduced.
The initial trench excavated running from Bridge Street to Moor Park Road ran across the small green area located at the north-western end of Moor Park Road. However, due to issues arising as to the ownership of this piece of land, this trench was immediately backfilled without any ducts being installed. The trench running across this area was excavated to an average depth of 0.7m. The topsoil layer averaged 0.1m in depth and lay directly over a mixed deposit of mid-brown/greyish silty sand that contained many small and medium-sized stones and construction debris. Sherds of blackware pottery and various clay-pipe components were also recovered from this deposit. At the base of the trench a cobbled surface was encountered. This surface extended for c. 1.5m and was made up of well-rounded stones which were consistent in both size and morphology.
The rerouted trench ran from Bridge Street to Moor Park Street along the northern side of the carriageway. At the western end of the street the road construction deposits of asphalt and aggregate had a combined average depth of 0.35m. Immediately beneath the aggregate layer at the western end of the street a wall running north–south was encountered. This wall was constructed from roughly hewn cut stone of regular size and bonded with lime-based mortar with occasional inserts of red brick. Immediately to the east of the wall there was a level concrete surface, which probably represents the remains of an internal floor. As the trench curved around to the south-east a second wall was encountered orientated east–west. This wall was of a similar size and scale to the first and appears to have been part of the same structure. It was located 0.45m below the street surface. Artefacts recovered from the immediate environs of the walls consisted of sherds of blackware, stoneware and bottle glass along with clay-pipe stems. Both walls appear to be those of a building indicated on both the first and second editions of the OS maps but subsequently demolished. The structure appears to have been late 18th- or early 19th-century in date. As it was not possible to reroute the trench in this area, 0.15–0.2m was removed from each wall in order to facilitate duct installation.