2008:821 - Boyne Centre, Bolton Street, Drogheda, Louth

Test-trenching took place in on 24 and 25 September 2008 of a site at the Boyne Centre, Drogheda. Works were conducted at the south-west end of the proposed development site, in an area abutting a section of the medieval town wall. The proposed development consists of alterations and refurbish-ments of existing retail units and carpark and the demolition and relocation of an ESB substation. Only one area of the development site was tested, the location of a proposed extension to Londis. A possible portion of the town wall (only one face surviving) lies to the south-west of the site. The area of the proposed building extension is c. 118m2. Two parallel test-trenches, c. 3m apart, were excavated by a mini-digger fitted with a grading bucket. The trenches were both orientated from north to south and were 1.7m wide. Trench 1 was c. 12m long and Trench 2 was c. 10m long.
The area tested was covered in a layer of concrete, c. 0.25m thick which was removed by machine prior to the excavation of the trenches. Below the concrete on the surface of the site was a mixed deposit of modern material in a sandy clay matrix which was on average 1m thick.
Trench 1 was excavated to the west of the area, was 1.7m wide and was excavated to an average depth of 1.3m. The deposits exposed were quite disturbed. An east–west-orientated sewage pipe (also seen in Trench 2) was located c. 3.6m from the north end of the trench, 0.7m from ground level. On either side of this pipe were areas of redeposited boulder clay. A small area of sterile boulder clay was exposed in the north-west corner of the trench. A single deposit of grey silty clay was exposed throughout the rest of the trench from a depth of c. 0.8m to a depth of at least 1.6m. This deposit was mixed and contained patches of redeposited boulder clay, modern pottery, a sherd of medieval pottery and some animal bone. It is likely that the area of this trench was substantially disturbed during the construction of the Boyne Centre.
Trench 2 was located c. 3m to the east of and parallel to Trench 1. This trench was 1.7m wide and was excavated to an average depth of 1.3m. The sewage pipe exposed in Trench 1 was also exposed in this trench, c. 2.4m from the north end of the trench. Just under halfway along this test-trench the edge of a cut feature was exposed orientated north-east/south-west diagonally across the trench. To the south of this feature sterile boulder clay was exposed within the remainder of the trench. This feature was filled with the same grey silty clay deposit that was exposed in Trench 1, and it extended beyond the northern limit of the trench. The cut feature could be the remains of the filled-in town wall ditch.
The testing revealed that the east side of the site is likely to have been substantially disturbed by the construction of the Boyne Centre. The feature revealed in Trench 2 may be the inner edge of part of the town wall ditch and the small area of sterile subsoil in the north-west of Trench 1 may delineate part of the outer edge of the ditch. If these do represent the two edges of the town wall ditch it would be c. 7m wide in this location. No portions of a town wall ditch have previously been noted on this side of the town. The evidence of the testing suggests that the ditch at this location was a substantial feature, which would have provided a formidable obstruction to any would-be attackers. The fill of this feature was grey silty clay similar to a garden soil. Some modern pottery was found in the top of the fill which indicates disturbance.
The ditch feature was exposed at an average depth of 1.2m below the ground level after the concrete had been removed. The foundations of the proposed extension are at depth of 1.1m below finished floor level. There will be a minimum buffer of 0.3m between the base of the foundation and the top of the town wall ditch it will therefore be preserved in situ below the new development.