2001:419 - DUNDRUM: Dundrum Town Centre, Dublin

The proposed development will incorporate retail, leisure, hotel, residential and office units. The centrepiece of the development will be a civic square around the old millpond and mill house.

Excavations were carried out on the site in January and February 2001 to clarify the extent of the remains of the 19th-century ironworks that operated on the site, their association with the millpond and dam and their connection with the recorded remains of the culvert system that was exposed during previous testing and survey work. Other questions were posed about the survival of any vestiges of the earlier mills that operated on this site, drawing on earlier cartographic evidence, which showed buildings flanking the River Slang.

The tradition of water-powered milling has been associated with this site since around 1602, when Richard Fitzwilliam of Dundrum Castle is cited as having a watermill, probably a cornmill, functioning on his demesne. Rocque’s map of 1760 depicts a building on the bank of the River Slang that may be a watermill. On Barker’s map of 1762 a mill is clearly captioned at the same location. The Mill House on the Sandyford Road is possibly illustrated, but there is no evidence for a pond. In 1800 a descriptive survey of County Dublin notes the presence of two mills in Dundrum: a paper-mill and an ironworks. It is not until the 1837 edition of the Ordnance Survey that the site is named ‘Dundrum Ironworks’. In 1847 the ironworks is described as follows: all of the buildings but three were single-storey and the majority were thatched. Four buildings were slated, including Mill House. Two overshot wheels are recorded. One was 3ft wide, had a diameter of 12ft and powered a bellows; the other operated a tilt-hammer, was 4ft 6in. wide and similar in diameter. By 1860 the ironworks is listed as vacant.

Manor Mill Laundry appears on the valuations of 1864. Apart from the addition of a turbine to generate electricity, which field evidence suggests took place between 1920 and 1940, little change took place at the laundry between 1914 and its closure in 1942.

Pye (Ireland) Ltd acquired the site in 1943. The factory had assumed its present form by the late 1960s. The Pye factory, at its peak, employed over 1,200 people and was a regular source of employment in Dundrum until 1985, when it finally ceased operations.

Excavations
The purpose of the current excavation was to open a number of areas to determine the water-power system associated with the millpond and dam and how this system was utilised to power the ironworks and subsequently Manor Mill Laundry. It was thought that further excavation might also reveal information about the 18th-century cornmill that operated on the site.

Two test-trenches were opened about 3m east of the present line of the River Slang. A masonry wall was exposed in the first trench. It was built of four to five courses of masonry surmounted by the springings of a segmental arch of red brick voussoirs. These voussoirs appeared to be all that remained of a red brick culvert raised over what seemed to be the remains of a tail-race, possibly the one depicted on William Duncan’s map of 1821. This race does not appear on any map after 1821. A second trench was opened further to the south. This exposed a foundation line of contiguously set granite boulders far more substantial than the walls of the tail-race. The boulders appeared to have been roughly dressed and deliberately placed to establish a firm footing for a building. Duncan’s map shows two buildings in this location, both of which are shown to straddle the tail-race. The exposed foundation line was not exactly in line with the race, but parallel to it and slightly to the west. It might therefore be the foundation of one of the buildings that straddled the race, although it might equally be the foundation of an earlier 18th-century mill that took its power directly from the River Slang. The tail-race was culverted before 1837, by which time it was functioning as a tail-race for the ironworks and subsequently for the laundry.

Excavation immediately to the west of the dam wall revealed a backfilled channel with flanking masonry walls. The channel was 1.6m wide and was exposed over a distance of 10m. The area west of this terminus was unexcavated as it had to be kept clear for vehicular access. The channel or head-race originated from an embrasure in the dam wall. The embrasure had cut granite jambs and a single cut granite lintel and was 1.39m wide. The embrasure had been reused to accommodate the control valve for the turbine.

The channel was lined with coursed masonry and extended from present ground level to the base of the channel at a depth of 1.8m, and the turbine pipe lay on this surface. It is recorded in the valuations that the ironworks operated two overshot mill-wheels. Prior to the 1840s, each industrial process requiring water-power required its own wheel. In the case of the Dundrum ironworks, historical data refer to two processes and two wheels. Structurally on this site only one wheel-pit and race was extant, implying that the two wheels operated in tandem in this channel.

A clearly defined overflow outlet is situated high on the dam wall on its southern end, delimited by rough granite jambs, with a projecting granite ‘spout’ forming the sill. Water from this ope fell down the wall to a V-shaped gully feeding into a drainage channel. This channel carried the run-off to a pair of ceramic pipes carrying the water off site to the west. Excavation to the west of the dam exposed a linear feature that originated in this gully and ran in a south-east/north-west direction to where it joined the mill-race/wheel-pit. The confluence of this channel with the race occurred 9.6m west of the dam. Two stone blocks of dressed and chamfered granite defined the point where the two waterways merged. The channel was deliberately backfilled and showed no evidence of silting.

The nature of the archaeological evidence recovered during the excavation would suggest that this was in fact a spade-mill. Fortunately, the alterations made on site during the establishment of Manor Mill Laundry did not impact heavily on the remains of the ironworks, and diagnostic features were preserved in the area excavated. To the south of the wheel-race was a floor level defined by a thin layer of black material, predominantly charcoal/coal-based, reflecting heavy industrial activity such as metalworking. Considerable evidence of ironwork was retrieved from this area, including quantities of charcoal, cinders, iron slag and iron fragments. Further excavation in this area identifies it as the location of the forge. Evidence of two ‘anvils’ was noted. These were identified as blocks of wood, well preserved, embedded in a stone-lined pit. In cross-section these blocks displayed a deep indentation with an obtuse ‘V’ profile with a flattened base. This is representative of the profile of head bits utilised in the manufacture of spades. The plan of this anvil was in the shape of a spade, which appeared to have been used for forming the products, while the trip-hammer shaped it. A further ‘anvil’ partially underlay the pit to the west. Nothing remained of the trip-hammer mechanism, but the subrectangular pit may correspond to the location of the cam-wheel that activated the trip-hammer.

Another work floor was exposed on the northern side of the wheel-race. It was of a similar composition to the area described above, containing a high density of charcoal, cinders and iron slag. The floor displayed a partial cladding of blue Bangor slates in the vicinity of the work area. Various features, including pits and mountings, were visible on the floor.

The dam wall was built to increase the head of water contained within the millpond to a sufficient height to operate the two overshot wheels. The wall was well founded on the granite bedrock and followed the natural contours of the site. It stood to an average height of 5m and was approximately 18m in length. The wall itself was formed of granite rubble, brought to courses and set in mortar.

The area to the west of the dam wall and west of the remains of the ironworks was to be tested to determine the line of the wheel-race as it continued from the dam and to find substantive evidence of the culvert that acted as the covered tail-race for the ironworks and ultimately housed the turbine pipes. Excavation showed that the tail-race continued out from the dam for about 20m before turning north into the culverts that extended under the laundry buildings. The culvert system did not appear to have been an original design feature, as in most cases; it was created by capping the existing races. This capping would allow for the maximum use of the land by channelling the waterways underground.

Excavation and testing were stopped at this point, and it was decided to proceed with monitoring of this area during the removal of structural material. During the course of this work, the octagonal base of the laundry chimney was exposed. The chimney was of fine brick construction around an open octagonal space. The chimney appears on the 1907 OS map and suggests the introduction of a steam boiler. The purpose of the boiler is uncertain but it may have been associated with an engine or heated process water.

Further archaeological work on this site is required to examine the base of the millpond during the restoration phase, at which time it will be possible to test the area below the ‘puddle clay’ and assess the purpose of the granite boulders and black silt.

The planned development will retain the Mill House, the millpond, the dam and the turbine control valve. The value of retaining structural remains from the past is only validated through interpretation. Therefore it is important that these features are interpreted archaeologically for the public.

2 Killiney View, Albert Road Lower, Glenageary, Co. Dublin