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I. Introduction

1.1 Introduction

The Wellington Seam has contributed a substantial part (about 30 megatonnes) of the production of the Vancouver Island coalfields since its discovery in 1871. During the years of peak production and sales (1890 to 1920) the Wellington coal was reputed to be an excellent coal for household and industrial heating. Mining of the Wellington coal continued, with some interruptions, until 1987. Throughout the history of mining in the Wellington Seam, difficult geological conditions, including seam splits, washouts and faults, have hampered the mechanization of underground coal mines, and have presented hazards to workers and equipment.

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.

1.2 Objectives

The purpose of this study is to determine, by means of stratigraphic and sedimentological mapping, geological controls upon the original extent, quality and mining conditions of the Wellington Seam within the Extension Formation, in the Nanaimo Coalfield of southwestern British Columbia (Figure 1-1). The major objectives of this study are to:
  1. establish a regional correlation for the coals of the Extension Formation, including the Wellington Seam;
  2. relate the lateral continuity, thickness, quality and mineability of the Wellington Seam to depositional environment; and
  3. establish the petrographic composition and depositional origin of coal and mudstone lithotypes present within the Wellington Seam.

1.3 Terminology

Coal miners and mining engineers, including those of the Vancouver Island coalfields, have a rich and varied vocabulary of specialized terms for geological features of coal seams and technological features of coal mining. Most if not all of the specialized vocabulary used on Vancouver Island was originally derived from the dialect spoken by Scottish and Welsh coal miners and geologists. Definitions of terms used in old mining and geologic records of the Wellington Seam are presented in Appendix IV of this thesis.

1.4 Location And Access

The Nanaimo Coalfield (Figure 1-2) is situated on the eastern coast of Vancouver Island, in southwestern British Columbia. The coalfield is part of a once-larger sedimentary basin (Georgia Basin), which has been dissected by erosion. The centre of the Nanaimo coalfield underlies the city of Nanaimo. Coal measures extend for about 28 kilometres along the coastal lowlands of the island, from Lantzville in the northwest to Cassidy in the southeast (James, 1969). The Wellington Seam crops out along the western edge of the coalfield, and extends eastward towards the coastline, beneath Nanaimo.

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.

1.5 Mining History

The Wellington Seam was discovered by Robert Dunsmuir in 1871, two years after his discovery of an overlying, thinner coal bed (Dunsmuir, 1871). Dunsmuir's discovery outcrop was situated about 2 kilometres northwest of Diver Lake, a short distance north and west of the coal property owned by his previous employer, the Vancouver Coal Mining and Land Company (Bowen, 1982). Dunsmuir had previously found an outcrop of the Little Wellington coal at Harewood, 4 kilometres southwest of Nanaimo, but had judged it unsuitable for development and sold it to an English syndicate (Brown, 1870; Clapp, 1914).

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).

1.6 Exploration History

Exploration for additional reserves of the Wellington coal commenced soon after development of Wellington Colliery, and generally kept pace with the requirement to replace worked-out areas. Most of the exploration was in areas adjacent to existing mines. This first phase of exploration ended in 1949, when Canadian Collieries (Dunsmuir) Limited ceased drilling in the Nanaimo Coalfield, in favour of exploration in the Tsable River Coalfield further to the north.

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).

1.7 Geological Setting

The Nanaimo Coalfield occupies the northwestern corner of the Nanaimo sub-basin of the Late Cretaceous and Tertiary Georgia Basin (Muller and Atchison, 1971; Bickford and Kenyon, 1988; Monger, 1990). The coal measures at Nanaimo are part of the Nanaimo Group (Table I; Figure 1-3) which is of Turonian to Maastrichtian age (Muller and Jeletzky, 1970; Haggart, 1991). Basement beneath the Nanaimo Group within the study area consists of Triassic volcanic rocks of the Wrangellia Terrane (Jones and others, 1977), which are locally intruded by Jurassic plutons.

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).

1.8 Previous Geological Work

Clapp (1914) and Muller and Atchison (1971) have aptly summarized the geological literature which was available to them. Most of the early work on the Nanaimo Coalfield was published by the Geological Survey of Canada. Historical details of the Survey's work on Vancouver Island have been outlined by Zaslow (1975), as part of a history of the Geological Survey of Canada. The following discussion draws heavily upon these sources, with the addition of materials which became available after 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.

1.9 Extent of available data

1.9.1 Boreholes

At least 215 boreholes have been drilled to or below the stratigraphic level of the Wellington Seam in the Nanaimo Coalfield. Records for 158 of the holes have been preserved in the coal assessment report files of the British Columbia Ministry of Energy, Mines and Petroleum Resources, or in the extensive collections of the British Columbia Archives and Records Service. Additional borehole records are held in the Nanaimo City Engineer's office, the Glenbow-Alberta Institute Archives and the Nanaimo Museum.

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.

1.9.2 Mine plans

Detailed plans are available for most of the Wellington bed workings. Official abandonment plans of the larger collieries are held in the office of the District Inspector of Mines and Resident Engineer at Nanaimo, while large-scale (1:1200) composite plans, which were compiled in 1939 by J.T. Hepburn, are held in the office of the Inspection and Engineering Branch in Victoria. Intermediate-scale (1:6000) composite plans were compiled by Island Geotechnical Services in 1979 (Pelly, 1979). Copies of these plans are available through the Nanaimo City Engineer's office. Many additional plans, including geologists' and engineers' progress plans, are held in the archival map collection of the Nanaimo Centennial Museum, and in the Map Division of the British Columbia Archives and Records Service.

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.

1.9.3 Analytical data

Numerous samples of the Wellington Seam and associated coal beds have been collected for analysis by mine operators, in order to determine the marketability of the coal. Proximate analyses, consisting of determination of the moisture, volatile matter, fixed carbon and ash content of coals, were routinely done by mine operators, generally to establish whether the coal was sufficiently clean to be marketable. Total sulphur content and calorific value of the coal, although not strictly part of a proximate analysis, were often also reported, because they affected the marketability of the Wellington coal for specific end-uses such as steam generation or cement manufacture. Records of proximate, sulphur and calorific value analyses of the Wellington Seam are presented in Appendix II.

1.10 Study Methods

1.10.1 Surface mapping

Reconnaissance-scale geological mapping was done at scales varying from 1:6,000 to 1:20,000, using base maps and aerial photographs obtained from the Surveys and Mapping Branch of the British Columbia Ministry of Environment. Where possible, old mine entries and borehole sites were relocated, with the aid of survey notes (Hepburn, 1939) which were found in the British Columbia Archives and Records Service. Results of surface geological mapping are discussed in Chapter 2 of this study and presented on Map 1.

1.10.2 Underground mapping

Workings of Wolf Mountain Colliery were mapped in detail as part of this study prior to the closure of the mine in February of 1987. Because up-to-date plans were unavailable, the extent of the mine workings was surveyed by means of a Brunton compass and measuring tape, using existing control points in the mine roof wherever possible. The mine plan was constructed from the survey data, following standard conventions (National Coal Board, 1984). Geological features were mapped at a scale of 1:1,000, using photocopies of the mine plan. Geological features of the Wellington Seam at Wolf Mountain are discussed and illustrated in Chapter III of this study.

1.10.3 Underground section measurement

A total of 229 sections were measured of the Wellington Seam in the workings of Wolf Mountain Colliery. Sections were measured at nearly every junction within the mine, on approximately 20 metre centres. Additional sections were measured in areas of complex geology. Section locations are shown on Map 2, and the sections are presented in Appendix III of this report.

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).

1.10.4 Underground Sampling

Columnar samples of the Wellington Seam were collected at geological stations WM100, WM220 and WM222 within the workings of Wolf Mountain Colliery (Map 2). The sample sites were chosen to investigate compositional changes within the coal bed, both vertically at each site and horizontally between sites.

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.

1.10.5 Analytical Procedures

In the laboratory, the samples of coal and mudstone from the Wellington Seam were subdivided vertically into several plies. Each ply was then split into halves along its length. One half of each ply was crushed to pass a 1.18 millimetre sieve, and subsampled by coning and quartering to provide replicate samples for analysis. The other half of each ply was retained for later examination and resampling, if required.

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.



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