Aberduna Engine House, Llanferres, Denbighshire, Wales

Welsh Mines Preservation Trust. Report on the Aberduna Mine Engine House by R.W. Vernon. 1. Introduction The Aberduna Lead Mine is located about 3 kilometres south-west of the town of Mold in the parish of Llanferres, Denbighshire. ( See Figure 1). The mine site lies immediately on the west side of the minor road that runs south from the A494 to the village of Maeshafn. An active quarry lies immediately to the south of the mine site. The mine was also known as Coed Cynric and Denbigh Consols. Throughout this report the mine will usually be referred to as Aberduna. The mine was worked along a north-west / south-east mineralised fault which downthrows to the northeast and is known as the Coed Cynric Lode. The chief ore is galena with a gangue predominantly of calcite. Another fault, the north-south trending Cathole Crosscourse intersects the Lode, east of the main workings. The main rock type is Carboniferous Limestone. The mine workings were accessed from two shafts, the Phoenix Engine Shaft (depth ~ 125 yards) and Quaker's Shaft (depth ~ 112 yards). (For locations of the shafts see Figure 2) Both shafts are connected underground at the 112 yard Level. The mine did not have an adit level. Mine water was pumped out at Phoenix Shaft by a 36 inch cylinder Cornish Beam Engine erected between 1840 and 1850. The mine stopped working in 1884 and was finally abandoned in 1887. All the mine building were located immediately west of the minor road and included Dressing Floors with probably a Crusher House, Office, Smithy, Carpenters Shop and Cornish Engine House together with a Boiler House, Flue and Chimney. The layout of the site in the 1880s can be seen on Figure 3. Over 100 years later, the only major feature remaining on the site is the Cornish Engine House, but even this is becoming structurally unsound and is in danger of collapsing. This is exacerbated further by the adjacent quarrying activity. In 1970, the base and shaft of the engine house could be examined in detail but gradually fill material has encroached the engine house and filled the shaft. The weight of the fill material now exerts pressure on the west wall of the engine house and may eventually lead to the collapse of this wall should total structural failure occur in either the north or south walls. The Engine House currently protrudes from a heavily vegetated slope composed of quarry fill material. This report details the present visible condition of the Engine House based on a simple tape and photographic survey carried out by R.W. Vernon on the 13th November 1996. For the purposes of this report, dimensions will be given in imperial units. 2. The Cornish Engine House in Flintshire / Denbighshire The lead mines of Flintshire / Denbighshire are predominantly on Carboniferous Limestone. Typical of elevated limestone areas, much of the water regime lies below the surface. As the mines got deeper greater quantities of water were encountered which had to be pumped out to surface. Often pumping was partly done by waterwheel, as at the Maeshafn Mine, adjacent toAberduna, but the limited availability of surface water meant that steam power had to be used. The ready availability of coal from the bordering coalfields eventually led to steam being the prime source of power with the consequence that Flintshire / Denbighshire once contained numerous Cornish Engine House. However, with the decline in the industry from the 1880s onwards, many engine house have been demolished, those remaining are under threat from demolition, e.g. Gronant. Only a handful remain, most are in danger of collapsing due to wooden lintel and mortar failure or vegetation invading the fabric of the building. Once structural integrity is lost, the building undergoes rapid deterioration. Page 1 3. The Aberduna Engine House The Aberduna Mine Engine House was constructed between 1840 and 1850 probably by the Coed Cynric Lead Mining Company Limited. It housed a 48 hp Steam Pumping Engine with a cylinder diameter of 36 inches. This produced a cylinder stroke of 8ft stroke and a shaft stroke of 7ft. Externally, the engine House measures 25ft by 20ft. The walls varied in thickness from 3ft to 5ft. The adjacent boiler house contained a 36ft by 6ft boiler with hemispherical ends. Detail from the 1872 Ordnance Survey 25" map indicates that a small flue led to a chimney on the south-west corner of the boiler house. South of the boiler house, the ground was higher and a trackway ran from the minor road to a yard probably used for coal storage. (See Figure 3 for the layout of the mine site) Figure 4 compares the standing Aberduna Engine house with the layout of a typical Cornish Engine House, with the engine in-situ. The comparison shows that there is nothing exceptional about the Aberduna Engine House in layout. The area of the cylinder mounting block and cataract pit are clearly discernible. Existing remnants of timber beams and the cavities for them show that the Aberduna Engine House had three floors. The bob wall and the cylinder door wall are also readily identifiable. Figure 5 details a simplified section and plan of the Engine House. The bob wall will be referred to as the south wall. It is thicker than the other three walls as it had to carry the weight of the cast iron beam and its bearings. The wall containing the cylinder door ( the cylinder passed through this door for installation on the cylinder mounting block) will be referred to as the north wall. The two side walls will be referred to as the west and east walls. Pumping was stopped on the 29th March 1884. It is probable that the engine was sold or scrapped shortly after this date. The last company to lease the site left in 1887. The 1912 Ordnance Survey 25" map provides some evidence for the deterioration of the mine buildings at the time of the survey in 1910. The Mine Office appears to be roofless. The Engine House still has its roof, but the Boiler House is roofless at the northern end. This suggests that the boiler at least had been scrapped or sold at this time. It was not uncommon for boilers to be removed via the flue wall end of the boiler house, the end away from the shaft area. Other evidence would also indicate that later use was made of the boiler house. The connecting door between the engine house and the boiler house is bricked up on the boiler house side, and photographic evidence (Figure 6, 1970) shows that a brick wall was constructed on top of the limestone backwall to the coal storage yard. It is possible that the construction of the brick wall was connected with the early phases of quarry development. Prior to 1970, the expansion of the quarry and its infra-structure mean that fill / waste material was pushed eastward enveloping the boiler house. Figure 7 consists of external photographs of the south walls of the Engine House taken in 1970, 1985 and 1996. Clear differences can be seen between 1970 and 1985 photographs. The quarry fill / waste material was pushed even further east to cover completely the coal storage yard and the engine shaft. In addition, it also surrounded much of the Engine House, which now protrudes unnaturally from the waste. Clearly little was done to the Engine Shaft in the form of capping, as the material that covered the shaft had by 1996, slumped into it. This now poses an addition problem to the Engine House as the shaft and more particularly the foundations of the Engine House immediately on the side of the shaft cannot be inspected. Any significant slumping of the shaft fill material will now have a wider cone of depression and exert an influence on a significantly greater portion of the Engine House. The photographs in Figure 8 of the external north wall show that no significant changes, other than spread of fill, have occurred in the last 26 years to this wall. Neither Figures 7 and 8 detail the interior of the Engine House, where the main structural problems are occurring, it is this aspect that the Survey carried out in November 1996 will try to elaborate on. Page 3 4. The Survey A simple tape and photographic survey was carried out on the 13th November 1996. All measurements are imperial as this is the system of measurement in usage when the Engine House was constructed. Specific measurements in such structures as Engine Houses usually conform to precise measurements in feet. The Aberduna Engine House is no exception have external dimensions of 20ft by 25ft. The height of the Engine House has meant that it has not been possible to examine or measure in detail much of the upper part of the structure. The measurements of inaccessible parts have been estimated by examination and scaling of photographs Parts of the east and south wall are covered in vegetation, which is rooted into the mortar. It was not possible to see clearly wall detail beneath the vegetation at the time of the visit. The Engine House is constructed from roughly dressed blocks of local grey Carboniferous Limestone, which often weathers to an off-pink colour. Most of the massive blocks occurs towards the base of the house and within the south (bob) wall. Generally the mortar in the walling from middle chamber upward has eroded out which if combined with lintel failure has caused the internal walling to collapse. Elsewhere within the structure, brick ( usually 9½" x 4½" x 3" ) has been used around windows to either brick them up, or to provide seating for windows panes. The window in the north wall, top chamber is an exception with brick being used extensively below the sill of the interior wall. All lintels have been constructed from wood usually 3" or 6" in thickness. Major north-south aligned wooden beams for supporting parts of the Engine are also incorporated into the fabric of the Engine House and vary from 15" to about 18" square. It is proposed to describe each wall separately. 4.1 South Wall (See Figures 6, 8, 9 and 14) The South Wall is 5ft in thickness. It was the most robust of all the walls as it had to carry the weight of the cast iron beam (or bob) and its bearings. It would also have had to endure continuous vibration. The south wall is about 20ft long and the top of the bob wall is about 25ft above original ground level. Central to and at the bottom of the wall a rectangular vertical opening gave access to the feeder pump and the condenser located on a small platform or inset between the shaft and the south wall the base of which is below the original ground level. Originally a wooden lintel would have supported the south wall above this opening, but this is no longer present. Further timber work would have sat on top of the wall to support two wooden beams on which bearings where bolted down to. This timber appears to have extended across the full width of the Engine House and incorporated into the fabric of the east and west walls. The bearings acted as a fulcrum for the heavy cast iron beam that lifted the pump rods up and down in the shaft below. The two wooden beams would have originally extended over the shaft to allow access to the bearing that connected the pump rods to the cast iron beam. A bolt is visible in the top of the South Wall which may have been used for holding down the wooden beams. The quarry waste material covers much of this wall making inspection difficult. Figure 8 shows the external elevation of the South Wall. Much of the east side of the wall is covered by vegetation which also grows along the top of the bob wall. The condenser opening is shown minus any timberwork. The masonry has fallen away around the lintel area. The location of timber extending into the west and east (assumed) walls is shown in Figure 8. In the west wall this timber has become rotten and has become compressed by the weight of the overlying masonry. The result of this is that severe cracking has developed in the west wall and a large portion of it is in danger of collapsing onto the south wall. This additional weight falling onto the south wall may well destroy any remaining structural integrity and cause further collapsing of the south wall. In the longer term this same problem will probably arise in the east wall, if this process has not started already. Page 8 Figure 9 details the structural problems with the interior of the South Wall. The composite photograph (A) consists of five photographs taken at ground level, hence the apparent reduction of interior width towards the top of the photograph. The key diagram (B) summarises the main components. The reference diagram (C) is cross-referenced with the following description. The two side walls of the condenser opening (1 and 2) can be seen standing from the quarry fill / waste material. The west side (1) is partly constructed from brick whilst the east side (2) is built from masonry. Remnants of the original wooden lintel (3) lies adjacent to the east wall. It probably extended across the full width of the engine house. It is not known if the timberwork forms part of the east wall. A cavity next to the west wall (4) indicates the where the lintel was accommodated. Immediately above the timber lintel, there is a stack of two bricks (5) which probably supported wooden beams that held up the floor of the middle chamber. Above the position of the lintel the masonry has collapsed along the full width of the south wall (6). Further timberwork would have formed part of this collapse. Trees are also growing in the area of collapse. Their roots will eventually wedge open gaps in the masonry. Vegetation is also growing along the top of the south wall (7). The location of the crack in the west wall, referred to earlier in this section has also been identified (8). Figure 14 is a photograph of the interior of the Engine House looking south. Collapse areas in the South Wall can be seen clearly. The brick arched opening in the west wall was the access to the boiler house. Figure 6 identifies some of the changes that have occurred to the South Wall over the last 26 years. 4.2 East Wall (See Figures 10 and 16) The East Wall lies adjacent to a track that runs from the minor road. The East Wall is 25ft long by 30ft high and 3ft 6in thick. Most of the East Wall appears to be intact, although the presence of vegetation up the full height at the southern end of the wall precludes examination. It is not known if timber from the South Wall is forming a focal point for structural weakness to occur in the East Wall. The mortar is visibly in poor condition for about the top third of the wall. (See Figure 16) There are six visible openings in the wall and these are shown in Figure 10. The lowest opening (1) does not appear to go completely through the wall, its position is below the level of the top of the cylinder mounting block. A further opening (2) is bricked up internally just above the top of the cylinder mounting block. It is brick lined down one side. Externally a small tree grows out of it. Three smaller openings (3) occur adjacent to (2). The lower two have been sealed with single bricks, whilst the upper one is brick lined. They may be openings for pipes. A window (4) at a level with the top of the middle chamber is unblocked. It is brick lined on one side and at the top. The wooden lintels are in situ, but internally are in very poor condition. In the short term it is unlikely that any major collapse of stone work will occur on the external walling of the window. However internally, minor collapsing has occurred above and at the side of the window. Vegetation is growing along the top of this wall. 4.3 North Wall (See Figures 7, 11, 12 and 15) The north wall is 3ft thick. It is about 36 ft high from original ground level to the apex of the roof. It is 20ft wide. The doorway to the bottom chamber was used for installing the Engine Cylinder. The width of this doorway is regarded a being a guide to the diameter of the cylinder. In this instance the doorway, without its original wooden frame, is 54 inches wide for a 36 inches diameter cylinder. After cylinder installation a wooden stairway would have provided access to the doorway from ground level. Figure 11 is a sketch of the external elevation of the North Wall. Externally, stonework appears to be in relatively good condition, with only one major crack. The crack runs down the west side of the top and middle chamber windows. Photographic evidence would indicate that this crack has not increased significantly in the last 26 years. (See Figure 7) Page 11 Timber has been incorporated into much of the wall. Above the Bottom Chamber cylinder door a 6 inch thick wooden lintel extends for 24 inches on either side of the doorway. Centrally above and supported by this lintel, there were two major north-south aligned beams (12inches square). They ran the whole length of the engine house and would have also been supported by the wooden lintel above the Condenser Open in the South Wall. They provided seating for various bearings and valve controls. Only a short length of the eastern beam remains in situ, a square hole denotes the location of the eastern beam. Both beam apertures show evidence for bricks having been used as packing around the beams. A lathe of 3 inch thick timber lies on top of the two beams and probably represents the level of the floor in the middle chamber. An opening, roughly 2ft 6in square, lies on the eastern side of the bottom chamber doorway. Its purpose is not known. It is untypical, and may have been cut through the wall after the Engine House was abandoned. A similar arrangement of timber can also be found above the window of the middle chamber. However, the two north-south aligned beams are greater in cross-section (15 to 18 inches square). They supported the bearings for the cast iron beam. Remnants of both beams are still in situ together with the original brick and stone packing. The top chamber window is smaller. The stonework above is supported by a short lintel. The external cracking starts roughly from the centre of this window. Brickwork extend up the east side of the window. Figure 12 details the structural problems with the interior of the North Wall. The composite photograph (A) consists of five photographs taken at ground level, hence the apparent reduction of interior width towards the top of the photograph. The key diagram (B) summarises the main components. The reference diagram (C) is cross-referenced with the following description. The interior of the North Wall has collapsed in the vicinity of the Cylinder Door (1). The wooden lintel (3) above the door and the remnants of the wooden flooring (8) above it is very rotten. Their failure contributes to much of the collapse. Further collapse occurs on the eastern end of the lintel above the square opening (2). The locations of the north-south wooden beams that were supported by the lintel (4 and 5) are clearly visible. A portion of the original beam is still in situ (4). A series of vertical slots (6) between (3) and (8) held wooden joists for supporting the Middle Chamber floor. They are not evident on the west side of the doorway where a large collapse has occurred (7). The collapse extends up (10) to the base of and around the west side of the Middle Chamber window (9). A large crack (11) is also evident on the west side of the window and its position would indicate that it linked to the previously described large external crack. Figure 15 is a close up photograph of the collapse area, features 1 to 11 can all be clearly identified. The lintel of the Middle Chamber window (12) consists of three timber beams probably measuring 12 inches by 6 inches in cross-section. All three beams appear to be, for the moment, stable. The remains of the main balks of timber (13) for the cast iron beam bearings rest on the lintel. The row of adjacent slots once housed the joists for supporting the Top Chamber floor. Some of the original flooring (15) appears to be incorporated into the wall, as it runs the full width of the Engine House. The short wooden lintels above the Top Chamber window (16) have collapsed internally resulting in a small collapse (18) internally. A large stone from the collapse rest precariously on the Top Chamber window sill. (See Fig 12 photograph A) The internal wall below the sill is faced with bricks (17) down to floor level (15) The remainder of the walling up to the roof apex appears to be intact. However, much of the mortar has weathered out and vegetation grows on the top courses of masonry. The only window in the West Wall can also be seen on Figure 12C (18). The quarry fill / waste material has not entered the engine house on this side. Page 13 4.4 West Wall (See Figures 13 and 17) Most of the external West Wall is buried under quarry waste / fill material. The Wall is 3ft 6in in thickness and 25ft long by about 30ft high. Most of the wall appears to be in relatively good condition apart from a major crack in the end adjacent to the South Wall. Figure 13 identifies all the major features in the West Wall. The bricked up doorway (8ft high by 2ft 6in. wide) through to the boiler house forms a major feature internally. However, externally it is buried under the quarry waste. Two courses of brick form an arch over the doorway. The side window to the Middle Chamber is also bricked up. Wooden beams form the lintel and sill. There is no evidence of collapse associated with them. Internally on the sill beam, there is a series of protruding nails which would have been used for hanging up either clothing or tools. Timber associated with the top of the South Wall is incorporated into the West Wall. This timber through natural decay has lost much of its strength with the result that it has been compressed into a wedge shape by the stonework that it supported. Differential loading on the timber has resulted in the south end of the West Wall to move. This has produced a large crack in the West Wall and the detached portion of masonry is leaning inward over the South (Bob) Wall. A tree disturbed by slumping in the fill over the Engine Shaft, now leans against the detached masonry and may have temporarily arrested movement. Figure 17 is a close up photograph of the crack. There are several iron brackets protruding externally from the West Wall. There locations are shown on Figure 13. 4.5 The Floor (See Figure 5) The internal floor of the Engine House can be divided into two. The raised northern half of the floor was the mounting for the 36 inch cylinder. This area was excavated, the holes for the cylinder bolts would be revealed. The southern half of the floor is lower, and is known as the cataract pit. It once contained various valves and pipework to the condenser. The cataract pit is 13 ft long by 7ft wide. It is full of waste material so its full depth is not known. 4.6 The Roof The Engine House is completely roofless. It was probably slated. The roof apex is about 6 ft above the tops of the East and West Walls. 4.7 Boiler House and Flue There is no visible evidence of the boiler house. As a portion of the boiler house yard was still visible in 1970 it is presumed that much of the boiler house is buried under the quarry waste material and still sufficiently intact to make the structure interpretable. The addition of a brick wall on top of the early limestone walling would indicate that the Boiler House and the Engine House had another use after the Engine was scrapped. What this was is not known. 5.0 The Future The future of the Aberduna Mine site is unclear at present. As it is now only one of a handful examples in North-East Wales, some attempt should be made to stabilise its decay. Enough of the Engine House remains for it to be interpretable although their are insufficient other mining remains on the site to place it in its true context. As a one off feature, however, it could be usefully incorporated into the mining trail that is currently under consideration. Clearly a more through report needs to be conducted on the Engine House to determine the full costs involved to make it safe, arrest deterioration and make it interpretable. Page 16 Appendix 1 A Brief History of the Aberduna (Coed Cynric) Engine House by Tony King During the 1840s Aberduna and Coed Cynric lead mines were originally operated independently. They were only combined from 1872 onwards. It is not clear from the sparse literature whether they were on adjacent mineral veins or along the same vein. The construction of the Engine House, between 1840 and 1850, is usually attributed to the Coed Cynric Mine operators, but the exact details are not known. The Coed Cynric Mine was operated on a 61 year lease which expired in 1876. However, the mine is older than this as it was probably worked by the London Lead Company (a Company run by Quakers) in the eighteenth century: one of the main shafts is known as Quaker's Shaft. The two main shafts are the Phoenix Engine Shaft (depth ~ 135 yards) and Quaker's Shaft (depth ~112 yards) 200 yards to the west. Parry's Shaft west of Quaker's Shaft was apparently sunk to 50 yards in the 1770's, but was later deepened to about 127 yards. The main development levels worked by the Denbighshire Consolidated Mines Company were the 112 (yards) east, 112 west and the 66 west. The 112 yard level connect both the Phoenix and Quaker's shaft. At the final closure of the mine the 112 extended for a distance of 900 yards and a connection had been made between Parrys Shaft and the 112 west. The 48 hp Steam Pumping Engine was operated by a 36 inch cylinder and developed an 8ft stroke in the cylinder and a 7ft stroke in the shaft. The Steam Boiler was 30ft long and 6ft in diameter with hemispherical ends. The mine buildings included Offices, Smith and Carpenters Shops and Dressing Floors. During operations by the Denbighshire Consolidated Mines a kiln and a changing house for the men were added. In addition, the company installed a 32 hp,16inch diameter cylinder, winding engine and Cornish Tubular Boiler at Phoenix Shaft. It was also used to draw material from Quaker's Shaft, work the crusher and power other ore dressing machinery. The mine is known to have been worked by the following companies: Coed Cynric Lead Mine Co. Ltd:   Incorporated 21st January 1859. Resolution to wind up company passed on the 25th November 1864. Denbighshire Consolidated Mines Ltd:   Incorporated 25th April 1872. Resolution to wind up company passed on the 24th July 1882. Aberduna Lead Mines Ltd:   Incorporated 25th August 1882. Petition to wind up company on the 28th March 1884 Mold District Lead Company Ltd:    Incorporated 23rd April 1885. Company inactive 1887. Company dissolved 3rd August 1894. Page 20 View publication stats