Despite a long and chequered contribution to Canada's coal mining industry, a regional study of the geology and coal quality of the Wellington Seam has not been made since Charles Clapp finished his Geological Survey Memoir on the Nanaimo Coalfield in 1914. Since Clapp's time, a large volume of surface and subsurface geological data have been collected concerning the Wellington Seam, allowing the recognition of additional mineable reserves of Wellington coal.
Over the past fifty years, residential and commercial development of Nanaimo and its suburbs has led to conflicts between surface land use and coal mining activities. This study is intended to provide a basis for knowledgeable consideration of the geology, quality and remaining potential for mining development of the Wellington Seam.
Urban and suburban development has spread outwards from Nanaimo over the past fifty years, and now covers much of the northern half of the coalfield. The remainder of the area is occupied by small rural holdings and tree farms. As a result of development, the Nanaimo Coalfield is served by a good network of paved and gravelled roads.
Prospecting and further mine development at Wellington progressed steadily, so that in the year 1894, 383,006 tonnes of coal were mined from six interconnected mines which together constituted the Wellington Colliery. In 1895, Dunsmuir commenced development of a second large colliery at Extension, southwest of Nanaimo, where coal had been discovered by a local settler. Development of Extension Colliery was accelerated following the abandonment of the less profitable Wellington Colliery in 1900; in 1906, 370,542 tonnes of coal were produced from the three mines at Extension. Extension Colliery was closed in 1931, due to a combination of low coal prices and the high cost of production from several widely-scattered faces within an extensive complex of workings (Bowen, 1982).
Several smaller mines worked the Wellington Seam, in both the vicinity of the two larger collieries, and throughout a larger area extending from Lantzville in the north to Haslam Creek in the south. Among these operations were Wakesiah Colliery (1918-1930), East Wellington Colliery (1883-1893), Northfield Colliery (1889-1895 and 1936-1941), White Rapids Colliery (1944-1950) and Timberlands Colliery (1918-1926 and 1941-1944).
Interest in the Wellington coal was renewed by the oil price increases of the late 1970's. Following a large coal licence application by Netherlands Pacific Mining Co. Inc. in 1978, Gulf Canada and Esso Resources conducted aggressive programmes of land acquisition and rotary drilling, in an effort to find surface-mineable coal reserves near tidewater (Peach, 1981; Perry, 1981a, 1981b). Results of these programmes were mostly negative, with the exception of the 1981 drilling by Gulf, which disclosed the presence of an outlier of thick Wellington coal on Wolf Mountain, south of Mount Benson (Perry, 1981a). Despite trenching, adit driveage and drilling done by the Western Fuel Company between 1917 and 1935, the existence of mineable coal on Wolf Mountain had been previously unsuspected. Further drilling by Netherlands Pacific Mining and partners demonstrated the existence of underground-mineable reserves at Wolf Mountain (Perry, 1982, 1983). In 1984 a small underground mine, Wolf Mountain Colliery, commenced extraction of the Wellington Seam at Wolf Mountain (Roberts, 1985). The mine was closed in 1987 due to poor market conditions, leaving most of the coal reserves untouched.
Locations of known entries to mines and prospects in the Wellington Seam are shown on Map 1 (in pocket).
The Wellington Seam occurs at the base of the Extension Formation (Clapp, 1912a), about 180 to 210 metres above the base of the Nanaimo Group. Owing to relief on the basement paleosurface, the interval between the base of the Wellington coal and the top of the basement varies. Isolated hills and ridges of basement rocks locally project up above the stratigraphic position of the Wellington coal, resulting in local areas in which the coal was not deposited (Buckham, 1947a).
In the northern end of the coalfield, near Wellington and Lantzville, the coal measures are gently deformed into broad open folds which are broken by steep normal cross-faults. Deformation has been more intense to the south; near Extension the coal measures have been stacked into a succession of folded overthrust sheets (Clapp, 1914; Buckham, 1947a; Muller and Atchison, 1971).
The first detailed study of the Nanaimo Coalfield, including the Wellington Seam, was done by James Richardson of the Geological Survey of Canada (Richardson, 1872; 1878). Whiteaves (1879, 1903) described many of the fossils collected by Richardson. Henry Poole revisited the area for the Geological Survey in 1905, collecting additional data but publishing only a brief report (Poole, 1906). Charles Clapp conducted detailed geological mapping of the Nanaimo map-area for the Geological Survey in 1911. Two reports were published: a brief preliminary report (Clapp, 1912a) and a lengthy memoir (Clapp, 1914). Additional fieldwork, particularly in underground workings at Lantzville, was done by John McKenzie in 1921.
In 1939, Alexander Fraser Buckham commenced a resurvey of the Nanaimo Coalfield for the Geological Survey in an effort to resolve the structural complexities of the coal measures. Buckham continued working at Nanaimo for the Survey until 1948. He produced three unpublished reports on the coal resources near Lantzville (Buckham, 1943a, 1943b and 1943c) and two papers covering the entire Nanaimo Coalfield: a short discussion focussing on structural geology (Buckham, 1947a), and an annotated preliminary map (Buckham, 1947b). Buckham then left the Survey to become Chief Geologist for Canadian Collieries (Dunsmuir) Ltd. Buckham continued his studies of the Nanaimo Coalfield, producing a review (Buckham, 1966) of the history of coal mining at Nanaimo; nevertheless, much of his work remained unpublished. Before his death in 1976, Buckham donated his extensive collection of geological and historical notes and records to the British Columbia Archives and Records Service, where they are now available for study.
Some of Buckham's data were made available to Jan Muller of the Geological Survey of Canada, who remapped the Nanaimo Coalfield in the late 1960's. Muller revised the stratigraphy of the Nanaimo Group (Muller and Jeletzky, 1970), and published a study of the geology and remaining reserves of the Vancouver Island coalfields (Muller and Atchison, 1971). Muller and Jeletzky's work was subsequently expanded upon by Peter Ward, who restored to formational rank (Ward, 1976 and 1978) some of the stratigraphic units which had been previously suppressed by Muller and Jeletzky.
While the Geological Survey of Canada concentrated upon working out the basic geology of the Nanaimo Coalfield, the British Columbia Ministry of Mines concentrated on the application of geological information to engineering and safety problems in the Nanaimo mines. Some geological data were reported as part of the descriptions of coal mines in the annual reports of the British Columbia Minister of Mines, for the years 1874 through 1968. Following the closure of the last small colliery in 1968, Tony James, who was then the District Inspector of Mines, examined the potential for additional discoveries of mineable coal at Nanaimo. In his report (James, 1969), he was unable to provide a figure for remaining coal reserves, but did provide details of the potential for additional coal exploration in the Wellington Seam. Geological studies of the Wellington Seam were commenced by officers and contract staff of the British Columbia Geological Survey Branch in 1987. Preliminary findings have been published as several short papers (Bickford and Kenyon, 1988; Bickford, 1989; Kenyon and Bickford, 1989; Cathyl- Bickford, 1992).
The mining companies which worked the Wellington Seam commissioned a large number of technical reports. Geological studies, concentrating upon the documentation of mineable coal reserves, were done by Sutton (1904), Gwillim (1908), McCallum (1909), Turnbull (1910), King (1918 and 1929), Laird (1932), Buckham (1950), Curcio (1979), Peach (1981), Perry (1981a, 1981b, 1982, 1983), and Roberts (1985). Engineering studies, containing geological data, were done by Brewer (1902a and 1902b), Lewis (1910), Morison and Forster Brown (1910), Faulds (1918), Campbell-Johnston (1920), Graham (1926), Spruston (1926a and 1926b), Hunt and Scott (1931), Evans (1928 and 1932), Loftus (1936), Strong and others (1939) and Strachan (1941). Most of these reports are held by the British Columbia Archives and Records Service and the Glenbow-Alberta Institute Archives.
Several versions exist for some of the logs; wherever possible, corroboration has been sought from other sources such as engineering and geological reports, drilling cost records, drillers' time sheets, and similar contemporary documents.
Locations for most of the boreholes, as shown on Map 1, have been confirmed either by using old maps (Faulds, 1904; Forster Brown and others, 1910; Loftus, 1936, Buckham, 1943c) as guides to relocating the drill sites in the field, or by plotting of Hepburn's (1939) site survey notes onto accurate base maps. Casing has been left in some boreholes, and they could conceivably be reentered with downhole geophysical tools.
Drilling details and stratigraphic interpretations of the boreholes are presented in Appendix I.
Information contained in these plans, besides the position and extent of Wellington coal workings, includes notes on the thickness and working section of the coal bed, elevations of the roof or floor of the coal, location and displacement of faults, and summaries of boreholes through the coal bed.
Plans of the later mines generally contain the most useful information. Particularly detailed plans are available for Northfield Colliery, Timberlands Colliery, Beban Mine and Wolf Mountain Colliery.
Coal lithotypes are macroscopically recognizable bands of coal seams (Stach and others, 1982). In this study, a modified version (Table III) of the Australian 'dull-bright' lithotype classification system (Diessel, 1967; Hoffman, Jordan and Wallis, 1982) was used to describe the coal. British National Coal Board standards (Elliott and others, 1984) were followed for the description of dirt bands, along with the roof and floor strata. The thickness of the coal bed and its constituent layers was measured using a tape graduated in 20ths of a foot (15 millimetres). The minimum band thickness measured was 1/20th of a foot (15 millimetres).
Debris and loose coal were cleared away from the coal face at each site, and the section of the coal bed was then recorded for later reference. A column of coal was outlined with a sledgehammer and drill bit, by carving two parallel grooves across the thickness of the coal, about 10 centimetres apart and 15 centimetres deep. Blocks of coal and associated rock bands were then extracted with a wood chisel, and successively placed in a wooden box for transport to the laboratory.
Three sets of replicate samples were obtained, to determine their petrographic composition, ash and moisture content, and caking power.
The first set of samples was prepared for determination of their petrographic composition by mixing with Transoptic™ plastic powder and forming into pellets using a Buehler ™ Speed Press. The pellets were polished following the procedure specified by Bustin and others (1985).
The pellets were examined at high magnification (625x) under incident light in oil immersion, using a Leitz MPV II ™ petrographic microscope and a Swift ™ automatic point-counting stage. Eleven macerals, following the standard classification scheme for bituminous coals (Bustin and others, 1985; Table IV) plus mineral matter were counted by point-counting. A minimum of 300 points were counted for each sample.
Following the splitting out of a subsample for maceral samples, the samples were recrushed to pass a 250 micron sieve, by means of stage crushing to minimize fines. A second set of samples, for determination of moisture and ash content, was split out of the recrushed material. Moisture and ash content of the samples were determined by standard methods D3173-73 and D3174-73 of the American Society for Testing and Materials (1980).
To test for moisture according to standard method D3173-73, a sample of powdered coal is placed in a covered container, weighed, and heated at a temperature of 104 C to 110 C for one hour. The sample and container are then allowed to cool within a desiccator. When cooled to room temperature, the sample and crucible are weighed. The weight loss from the sample indicates its moisture content.
To test for ash according to standard method D3174-73, a sample of powdered coal is placed in a container, weighed, and heated in a furnace to a temperature of 700 C to 750 C. Ignition of the sample is continued until it attains a constant weight. The material remaining in the container after complete ignition is the ash of the coal sample. The ash content of a coal as obtained by this high-temperature method is often less than the original mineral matter content of the coal, because when certain minerals are heated rapidly they evolve volatile substances such as water and carbon dioxide. For example, clays and gypsum yield water when heated rapidly, carbonates yield carbon dioxide, and pyrite yields sulphur dioxide.
The third set of samples was used for investigation of the caking power of the coal, by determining its free swelling index (FSI) following standard method D720-67 of the American Society for Testing and Materials (1980). The FSI test involves heating 1 gram of powdered coal in a covered crucible to a temperature of approximately 800oC over a period of 2.5 minutes. The crucible is then removed from the source of heat and its contents compared to a set of standard profiles. FSI values are reported on a dimensionless scale from 0 to 9.
The FSI of a coal is a simple measure of its potential value for manufacture of coke (Ward, 1984). The ideal FSI value of a coking coal is 4 to 6, which indicates that the coal will expand sufficiently during coking to produce a porous coke, but will not expand so greatly as to produce an overly-porous, thin-walled coke with low crushing strength.