Colliery heritage project: Exploration and rehabilitation of Comox No. 3 Mine as an underground education site

Tags: coal bed, Vancouver Island, potential, geological mapping, workings, Mining in British Columbia, Comox, floor, Mines Branch, British Columbia Archives, coal beds, coal face, Cathyl-Bickford, mining equipment, Coal balls, domestic coal, Comox Formation, coal markets, coal mining, Geological maps, Canadian Institute of Mining and Metallurgy, Geological Survey of Canada, Mines Annual Report, B.C. Ministry of Energy and Mines, pages, Exploration, coal mines, underground tours, roof conditions, safety equipment, Southwestern British Columbia, saleable coal
Content: COLLIERY HERITAGE PROJECT: EXPLORATION AND REHABILITATION OF COMOX NO.3 MINE AS AN UNDERGROUND EDUCATIONAL SITE By C.G. Cathyl-Bickford1
KEYWORDS: Comox Colliery, No.3 Mine, Comox No.2 coal bed, Cumberland Member, Dunsmuir Member, Comox Formation, industrial heritage, tourist mine, coal geology, mining conditions, measured sections, underground geological methods, coal balls, Nanaimo Group. INTRODUCTION This report is part of a series of geological and mining studies of the coalfields of Vancouver Island, begun in 1987. Knowledge of the geology and mining conditions of the coalfields is a prerequisite to informed decisions on current and future land-use and resource planning on the Island. In contrast to previous years' work, this study considers the industrial heritage and educational potential of one of the oldest coal mines in British Columbia, opened near the village of Cumberland in 1889 and abandoned in 1893. Comparisons are drawn between the educational and industrial consequences of various features of local coal geology, as exemplified by the No.3 Mine of Comox Colliery. While researching mining activities in the Cumberland area as a retirement project in the summer of 1999, former colliery surveyor Robert Williams BCLS (retired) recognised No.3 Mine's potential for development as an industrial heritage and tourism site. The Village of Cumberland provided labour and equipment to briefly reopen three of the mine's portals for initial examination in September of 2000, and for a more detailed exploration of the underground workings in January of 2002. HISTORY First Nations people walking along creeks and rivers near Comox Lake may have observed coal outcrops several thousand years ago, but neither oral histories nor archaeological evidence are available to suggest that they made any use of the coal. In 1870 a British emigrant, Samuel Cliffe, prospected coal outcrops southeast of Comox Lake, for the Union Coal Company. Mine development was delayed until after the Union Coal Company was taken over by Dunsmuir, Diggle & Co. in 1881 (Isenor and others, 1987). The new owners traced the coal along the hillside east of Perseverance Creek (locally known as Coal Creek), and drove two adits and two airways into the uppermost of three coal beds in 1888 (Dick, 1889). Substantial surface facilities, including a weighing house and a long loading trestle, 1Project Manager, No.3 Mine, Village of Cumberland
were constructed outside the lowest of the mine's portals. Mining continued until 1893 (Dick, 1894), at which time all equipment was withdrawn from the mine in favour of expanded production from thicker coal beds elsewhere on the property. Although the mine was originally known as "The Adit Levels" or "Nos.1 and 2 Tunnels," (B. Nicholas, personal communication, 2001) from 1922 onwards it was known as No.3 Mine of Comox Colliery. No.3 was not officially reported as a producing mine after its closure in 1893, but further undocumented working was done in the 1930s and 1940s by Chinese miners who hauled sacks and wheelbarrow loads of coal from the mine down to Cumberland's Chinatown (W. Moncrief, personal communication, 2001). Despite the great age of the mine, its workings remained open and accessible until at least 1985, at which time it was still possible to enter one of the adit levels and conduct geological exploration (Cathyl-Bickford, 1988). In 1987 the mine's portals were blasted shut, and entry further discouraged by piling soil and rock over their mouths (R. Bone, personal communication, 1987). LOCATION AND ACCESS No.3 Mine is situated adjacent to the Village of Cumberland in the eastern foothills of the Beaufort Range, southeast of Comox Lake on Vancouver Island. The mine is served by recently-constructed all-weather gravel road, Rocky's Main, which branches from the Hamilton Lake logging road about one kilometre south of the village. Access to the mine may also be gained by means of a network of hiking and cycling trails which radiate from Cumberland's old Chinatown. The minesite was selectively logged during the summer and autumn of 2001, and many bedrock ledges are newly visible through openings in the forest cover. Most of the outcrops can easily be accessed by foot from the roads or trails, although getting to some requires scrambling through logging debris and thick underbrush. GEOLOGICAL SETTING The coals of the Comox coalfield are hosted by the Cumberland and Dunsmuir members of the late Cretaceous Comox Formation (Bickford and Kenyon, 1988; Mustard, 1994). The Comox Formation consists of interbedded sandstone, siltstone, mudstone and coal, with occasional thin beds of oil shale and conglomerate (Cathyl-Bickford, 2001). Most of the thick coal beds lie within the predomi-
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nantly nonmarine Cumberland Member of the formation, which contains six coals numbered 4, 3A, 3, 2A, 2 and 2R from base to top. Thinner but perhaps more laterally-continuous coal beds lie within the overlying predominantly marine Dunsmuir Member, which contains six coals numbered and lettered 1L, 1, 1R, Z, Y and X from base to top. Of the twelve correlatable coal beds within the Comox Formation, only the thickest four, presently known as the Nos. 4, 3A, 2 and 1 coal beds, have been mined (Graham, 1924). PREVIOUS WORK James Richardson (1872; 1873) first examined the Comox coalfield in detail for the Geological Survey of Canada. His work was followed-up by J.D. MacKenzie (1922), who measured several closely spaced sections of the Comox Formation along Perseverance Creek. Muller and Atchison (1971) compiled a regional synthesis of coal geology, including a structural map of the Comox coal mines. None of these workers did appreciable work underground in the Comox mines, with the exception of a few days' sectioning and sampling done by MacKenzie in the No.4 and No.5 mines on the north side of the Village of Cumberland. The bulk of MacKenzie's work remained unpublished owing to his sudden death in 1923, but many of
his maps and notes have been preserved in the British Columbia Archives in Victoria, as part of Additional Manuscript 436. More recent regional geological mapping is available for the Comox coalfield, including the vicinity of No.3 Mine, at 1:20,000 scale (Cathyl-Bickford and Hoffman, 1998). A detailed geological map (Figure 1) of the minesite area at 1:5000 scale was compiled during the summer of 2001 in support of the Village of Cumberland's application for a mine reclamation permit (Cathyl-Bickford and Williams, 2001). DETAILED GEOLOGY No.3 Mine was initially understood to have worked the Comox No.1 coal bed (Muller and Atchison, 1971; Saunders and others, 1974), but it is now thought to have worked the underlying No.2 coal bed. Reinterpretation of the stratigraphic position of No.3 Mine is based on comparison of marker beds exposed along the mine's access road (see Measured Section 9, in Appendix A) with the more complete section of the formation exposed in the canyon of Trent River above the Inland Island Highway (see Measured section 10, in Appendix B). Eight previously-reported stratigraphic sections are contained in pa-
Figure 1. Geological map of No.3 minesite, showing reported extent of mine workings in relation to bedrock geology. 102
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Photo 1. View southward into workings inbye Portal 4. Timber posts are 20 to 30 cm in diameter, and have single cap-pieces to spread load against carbonaceous mudstone roof of coal bed. pers by Kenyon and others (1991) and Cathyl-Bickford (2000). The main roof of the No.2 coal bed at No.3 Mine consists of at least 6 metres of thin- to thick-bedded sandstone of the basal Dunsmuir Member of the Comox Formation. The sandstone contains locally-abundant coalified wood fragments and shell debris, with occasional large but poorly-preserved mollusc fossils (tentatively identified as Inoceramus sp.) The immediate nether roof of the No.2 coal bed consists of 30 to 50 centimetres of interbedded dark grey to black canneloid, carbonaceous and silty mudstone with occasional thin and thick bright coal bands, representing the uppermost part of the Cumberland Member of the Comox Formation. The Comox No.2 coal bed itself has a gross thickness of 1.05 to 1.2 metres where exposed near the mine portals, but it probably thins to the south within the mine workings, as alluded to in inspector's reports (Dick, 1889; 1894). The coal bed consists of 80 to 90 centimetres of very hard, blocky, bright banded coal with thin but laterally-persistent partings of mudstone and siltstone. Partings were observed in surface exposures and within mine pillars, where some of the parting material has squeezed out into the adjacent workings, perhaps due to loading of the pillars. Coal balls, consisting of ellipsoidal masses of silicified plant material, are occasionally present within the No.2 coal bed. Plant-fossil preservation appears to be quite good: details of wood grain, including knots and compression wood, are evident in the coarser plant material within the coal balls. The floor of the No.2 coal bed consists of thinly-interbedded mudstone, siltstone and sandstone, much of which contains fossilised plant roots and occasional entire coalified logs as well as coalified stumps in their growth position. The coal-measures near No.3 Mine are gently folded into an east-plunging open syncline about 700 metres wide. Mine workings lie within the western nose of the fold where dips range from 8 to 14 degrees to the east and southeast.
Photo 2. Original firewall of brick and stone, on north side of underground ventilation furnace, inbye Portal 5. Sandstone roof above furnace has been baked and reddened, and shows minor flaking. Two minor extensional faults and one bedding-plane shear zone were observed during mapping, but none of these structures appear to be particularly extensive and the greatest fault displacement observed is just slightly over 2 metres. MINING CONDITIONS During the underground exploration in January 2002, observations were made of the performance of the roof and floor of the mine workings, as well as the support methods employed by the miners. The basal Dunsmuir sandstone appears to form a very strong roof, standing unbroken across spans up to 20 metres wide, which is a creditable performance even considering the shallow cover (generally less than 10 metres) over the mine workings. Of greater significance, perhaps, is the apparent strength of the uppermost Cumberland mudstones, which form the immediate nether roof of the mine. In most cases these mudstones have been used as the working roof of the mine, and they are standing well with minimal bed separation despite the lack of effective artificial roof support in the mine. Good roof performance has allowed the old workings of No.3 Mine to stand open for more than a hundred years, which provides some encouragement for the prospect of rehabilitating the mine for underground tours and education. However, such strong roofs might provide problems for future mines located deeper within the Comox coalfield, since delayed caving of mine roof can cause overloading of modern mechanised support systems, and can also cause severe air blasts within the mine workings. The hard coal of the No.2 coal bed appears to form strong pillars, which have probably also contributed to the apparent long-term stability of the mine workings. When
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the mine portals were dug out in January 2002, the coal broke out as very large blocks across the full thickness of the coal bed, each weighed between one and several hundred kilograms. During the period of main working of the mine in the 1890s, and indeed up until the end of the domestic coal era in the 1950s, such hard coal would have formed a high proportion of large lumps. Miners put considerable effort into increasing the proportion of lump coal within run-of-mine production, since the larger sizes of coal could be sold at much higher prices than the finer coal. However, modern coal markets do not place such a premium on large product sizes, and the No.2 coal's hardness could be detrimental to its Economic Value since machine power requirements and cutting-pick consumption are increased when working harder coal. Piles of fine coal found during recent exploration of the mine suggest that the miners screened or raked the coal underground, discarding material smaller than 25 mm, and hauling only the larger lumps out of the mine. The No.2 coal displays a well-developed face cleat striking 028 to 033, and dipping 70 to 80 degrees to the northwest, and an irregular butt cleat striking 115 to 125. The face cleat forms subparallel planes of weakness within the coal, affording a means for shearing of the coal face with hand tools. Unlike other still-accessible mine workings of similar vintage in the Vancouver Island coalfields, such as the Sage Mine on Newcastle Island and Dunsmuir's Original Entry in the northern part of the City of Nanaimo, the accessible coal faces of No.3 Mine do not show many pick marks or other tool marks. The original miners probably found it quite easy to wedge the well-cleated coal down from the coal faces. Coal balls within the No.2 coal bed afford the possibility of an unusually-detailed view of Late Cretaceous flora, since their contained plant material was cemented and preserved prior to compaction of the coal-measures. On the other hand, the presence of coal balls is a detriment to future mining, since the coal balls are prone to sparking when encountered by coal-cutting equipment. Furthermore, coal balls are a potential source of instability in coal faces, and constitute an additional body of unsaleable waste to be handled and disposed of. The floor of the No.2 coal bed is markedly softer and weaker than its roof. The floor appears to have heaved and rolled up into some of the workings, partially blocking the circulation of air within the mine and reducing travel within the workings to a muddy exercise of crawling on one's belly. The floor heaves may be due to load transfer from the mine's pillars into its floor, or may also be due to swelling of moisture-sensitive clays. Although in the 1890s it might have been reasonable to expect miners to travel through workings no more than 90 cm high, modern mining equipment can only traverse and work such thin coal with difficulty. Even the most adventurous of tourists is unlikely to want to crawl through workings that have been partially blocked by floor heaves. On the other hand, the soft floor of the No.2 coal bed could be excavated with greater ease than the sandstone roof. Suffi-
cient height for comfortable passage of visitors could be gained by lifting 1.2 to 1.5 metres of the mine's floor. Pillars of remnant coal within the mine workings are surprisingly uncommon. Most of the mine's roof support appears to have been provided by timber props, 25 to 50 centimetres in diameter and 0.9 to 1.1 metres long, set on 1.2-meter centres. Along the sides of underground roadways, randomly-spaced rock-filled cribs supplemented the props. Not surprisingly, given the mine's great age, nearly all of the timbers were found to be rotten during the most recent examination of the mine, and most of the rock-filled cribs had partially or completely collapsed owing to failure of their timber frames. No.3 Mine, like several other old collieries on Vancouver Island, was ventilated by means of an underground furnace. Furnaces typically were built within a coal bed, close to the bottom of an airshaft or the mouth of an adit. Because of the obvious risk of setting fire to the adjoining coal pillars, brick or stone firewalls were customarily built along either side of the furnace, and its grate was set between the walls. Remains of the No.3 furnace are preserved in the most southerly of the mine's five known portals. The furnace's firewalls were constructed with mortared stone blocks and bricks, paralleling each side of the portal and situated a few metres inside its mouth. The walls show signs of baking and heat-induced spalling, as does the mine's roof immediately between the walls. No sign of the furnace's grate is visible, but remnants of it may remain beneath the piles of rubble, which partially block the passageway between the furnace walls. EXPLORATION METHODS AND RESULTS Reopening of the mine entrance was easily accomplished by means of a tracked excavator provided by the works crew of the Village of Cumberland. About two hours of machine time were required to windrow logging debris that covered the minesite, and to dig out two portals which had been blocked by piles of earth and rock. One hour of machine time was devoted to reinforcing the covering over an existing gated access structure. Two hours of machine time were required to backfill and regrade the portals, ensuring that unsupervised visitors could not easily gain access to the mine. The total cost of a day's work at the mine was probably less than a thousand dollars, including volunteer labour that was donated on the Village's behalf. Underground exploration was conducted by a party of three persons, led by a certificated fireboss, accompanied by a colliery surveyor and a mining geologist. Mine air was tested for carbon monoxide by means of Draeger tubes, and for methane by means of a portable methanometer. Several sets of tests were conducted, but neither gas was detected in the mine. Bearings and distances within the mine were determined by tape and compass, supplemented by laser rangefinder observations from the mine's portals. Progress within the mine was hampered by mounds of debris and heaved floor material, and by concerns for roof stability within untimbered areas. Nevertheless, three hour's work
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underground was sufficient to establish the general conditions near the mine entries, and assess whether the proposed rehabilitation of the mine was feasible. Appropriate safety equipment such as hard hats, approved mine lamps and knee pads were used. Knee pads, although often forgotten, lend a precious level of comfort to underground geological mapping of thin coal beds. Crawling about in a coal mine is exhausting work, made more difficult by the occasional need to belly one's way over piles of rock, or squeeze through a tight spot. Most of the mapping and safety equipment was carried by hand (requiring great dexterity to move it and use it effectively), or attached to work belts (thus affording considerable potential for jamming its owner between rocks and hard places). A lesson learned from trying to work within the mine is that tools and equipment should be attached to shoulder-straps or lanyards, so that they can be effectively dragged by one's feet as well as one's hands while crawling through the mine. Large steel spikes that had been painted bright orange for easy recognition and retrieval temporarily marked geological control points within the mine. In an inactive mine such as No.3 Mine, spikes make good place-markers for mapping as well as for measurement of stratigraphic sections of coal pillars and exposed roof and floor strata. However, their use in an active mine might be less desirable, since any spikes left underground could puncture the tires of mobile equipment, or wreak havoc within a coal-preparation plant in the event that they found their way into the mined product. Very few plans of the mine remain in existence, and the most detailed of them (held by the Cumberland Museum and Archives) was at some time in the past trimmed in such a manner as to cut off most of the workings of No.3 Mine. None of the various plans, at whatever scale, show internal details of No.3 Mine's pillars and underground roadways. EDUCATIONAL POTENTIAL No.3 Mine is unusual among coal mines, in that its current value is as an accessible example of Vancouver Island's industrial heritage, rather than a potential source of saleable coal. Based on the limited underground examinations done to date, the mine appears to be in good shape except for the condition of its timbers. The fact that the mine is still standing open is a rather encouraging sign for its prospects as a tourist site; good roof conditions will ensure the safety of visitors to the mine. The most likely route for underground tours would be along the inside edge of the remnant barrier pillar that bounds the outcrop edge of the No.2 coal bed. Educational possibilities of No.3 Mine include demonstrating of the evolution of mining methods in the Comox coalfield (ranging from hand-hewing through early machine mining to modern continuous-miner and shuttle-car systems), seeing geological structures within coal-measures, and the palaeontology of animal and plant fossils, particularly the Cretaceous coal-ball flora. No.3 Mine, once it has been made safe, would be an excellent locale for teaching surface and
underground geological mapping, since just enough geology is exposed to make an instructive, solveable puzzle to a would-be mapper. As the mine currently exists, considerable rehabilitation would be needed before visitors could safely enter it. Although the roof conditions are remarkably good for a coal mine of its vintage, the timbering is unstable owing to rot and localised crushing by roof pressure. Mounds of fine coal, discarded rock, and heaved floor strata that litter the mine, make it impassable locally. In the absence of an accurate plan of the mine's workings, it is not possible to assess the extent to which pillars have been robbed, or the proportion of supported to unsupported roof. Challenges to rehabilitation of the mine include: the possibility of spontaneous combustion when adequate ventilation is established; the unassessed potential for acid mine drainage from the workings or acid generation from any loose materials loaded out of the mine; and the unknown dimensions and locations of the mine's remaining pillars. Nevertheless, No.3 Mine affords the prospect of educating its visitors in the historic practices of coal mining in British Columbia, as well exposure to the emerging art and science of coal-mining geology. ACKNOWLEDGEMENTS Robert Williams brought the educational potential of the well-preserved workings of No.3 Mine to the Village's attention in the autumn of 2000, and since then he has been a hard-working and diligent colleague and an outspoken advocate for the mine. The Cumberland woods crew of Mike Hamilton Logging Ltd. built the access road to the mine and were most accommodating to a geologist's urgent, albeit unfathomable, need for better exposure of the Comox coal measures. Cumberland Mayor William Moncrief and Councillor Leslie Baird, underground manager Bruce Fairbrother, and mine inspector Ed Taje of the British Columbia Mines Branch have unstintingly given their support and wise counsel to this project. Peter Mustard of Simon Fraser University offered some insights into the geology of the Comox Formation at Trent River, but the sections accompanying this paper represent my own views on the subject. Clarity of expression within this paper was considerably improved by William McMillan's editorial ministrations. REFERENCES Bickford, C.G.C. and Kenyon, C. (1988): Coalfield geology of eastern Vancouver Island; in Geological Fieldwork 1987, B.C. Ministry of Energy and Mines, Paper 1988-1, pages 441 to 450. Cathyl-Bickford, C.G. (1988): First report on the geology, anticipated mining conditions and coal resource potential of the Allen Vale coal prospect, Vancouver Island, B.C.; unpublished report, G. Hoffman Consulting Services Ltd., 27 pages. Cathyl-Bickford, C.G. (2001): Lithostratigraphy of the Comox and Trent River Formations in the Comox Coalfield, Vancouver Island; in Geological Fieldwork 2000, B.C. Ministry of Energy and Mines, Paper 2001-1, pages 363 to 370.
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Cathyl-Bickford, C.G. and Hoffman, G.L. (1998): Geological maps of the Nanaimo and Comox coalfields; B.C. Ministry of Energy and Mines, Open File Report 1998-7, 14 maps. Cathyl-Bickford, C.G. and Williams, R. (2001): Mineral and coal notice of work and reclamation, 2001, on the No.3 Mine, Comox Colliery; Village of Cumberland, 50 pages. Dick, A. (1889): Union Colliery, Comox; in Minister of Mines Annual report 1888, B.C. Ministry of Energy and Mines, pages 336 and 337. Dick, A. (1894): Union Colliery, Comox; in Minister of Mines Annual Report 1893, B.C. Ministry of Energy and Mines, pages 1100 and 1101. Graham, C. (1924): The problems of the Vancouver Island coal industry; Canadian Institute of Mining and Metallurgy, Transactions, volume XXVII, pages 456 to 477. Isenor, D.E., McInnis, W.N., Stephens, E.G. and Watson, D.E. (1987): Land of plenty: a history of the Comox district; Ptarmigan Press, Campbell River, 464 pages.
Kenyon, C., Bickford, C.G.C. and Hoffman, G.L. (1991): Quinsam and Chute Creek coal deposits; B.C. Ministry of Energy and Mines, Paper 1991-3. MacKenzie, J.D. (1922): The coal measures of Cumberland and vicinity, Vancouver Island; Canadian Institute of Mining and Metallurgy, Transactions, volume XXV, pages 382 to 411. Mustard, P.S. (1994): The Upper Cretaceous Nanaimo Group, Georgia Basin; in Geology and geological hazards of the Vancouver Region, Southwestern British Columbia ,J.W.H. Monger, (Editor), Geological Survey of Canada, Bulletin 481, pages 27 to 95. Richardson, J. (1872): Coal fields of the east coast of Vancouver Island; Geological Survey of Canada, Report of Progress 1871-1872, pages 73 to 100. Richardson, J. (1873): Coal fields of Vancouver Island; Geological Survey of Canada, Report of Progress 1872-1873, part 4, pages 32 to 65. Saunders, C.O., Howey, H.O. and Campbell, D.D. (1974): Report on the reserves and mining costs of the Comox Coalfield, Vancouver Island, B.C.; unpublished report, British Columbia Hydro and Power Authority.
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Appendix A Continued
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Appendix A Continued
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Appendix A Continued
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Appendix A Continued
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Appendix B Continued
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