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Mining Operations Under Residential Areas

Jamie Kneen Communications and Outreach Coordinator responsible for: strategic research, social media, and public engagement; our Africa program, environmental assessment, and uranium mining.

Prepared for MiningWatch Canada
By W.O. Mackasey
WOM Geological Associates Inc.

April 25, 2002

1.0 INTRODUCTION

WOM Geological Associates Inc. has been retained by MiningWatch Canada to conduct a review of Canadian policies and practices with respect to mining under residential areas. As part of the review MiningWatch Canada provided a list of mines and mining towns for WOM Geological Associates Inc. to assess if: a) mining operations had occurred under any residential areas and, b) any subsidence problems had occurred.

This study is based on the review of documents and other information supplied by government mining agencies, from various individuals and from the author's some forty years experience in the mining industry. The scope of the project did not allow for field work.

The first part of the report deals with the list of mines and mining towns submitted by MiningWatch Canada. The following parts review the current policies and practices applied to mining under residential areas in Canada.

2.0 A LIST OF MINES AND MINING TOWNS

The following list, which was submitted by MiningWatch Canada, contains comments on a) whether or not mining had occurred under residential areas and, b) the presence of any damage caused by subsidence due to mining operations. The mine names are based on local usage for the sites listed. Ownership of the sites has not been determined.

  • Garson Mine, Sudbury, Ontario: Stopes are located under Regional Road 86. Plans are to tight-fill the stopes using paste backfill to provide stability.
  • Madsen Red Lake Mine, Red Lake, Ontario: This mine is currently closed. No mine workings appear to be under the Madsen townsite. A crown pillar exists beneath the main access road to Madsen.
  • Dickenson Mine, Red Lake, Ontario: Based on the records available, it is not possible to learn if mining occurred under the Dickenson townsite.
  • Campbell Red Lake Mine, Red Lake, Ontario: The "A" gold zone extends under the NE corner of the Balmertown townsite. No information could be found on the impact of the "A" zone on the townsite. Approximately 20,000 tons of arsenic trioxide are presently stored in the underground workings. As part of mine Closure Plan requirements, the company has been conducting studies to deal with this material in the long term.
  • Pamour Mine, Timmins, Ontario: In 1957 a collapse of a crown pillar under Highway 101 left an open hole in the highway. In the 1990's, homes at the mine property were removed to allow for mine expansion. These homes were owned by the company.
  • Dome Mine, Timmins, Ontario: A company owned townsite was built on the mining property. These homes have since been removed to allow for expansion of the mining operation.
  • Main Mine, Flin Flon, Manitoba: There has been limited mining under the town. No cases of subsidence have occurred.
  • Sigma and Lamaque Mines, Val d'Or, Québec: These mines operated under parts of the town. No problems appear to have occurred.
  • Gaspé Copper, Murdochville, Québec: Some mining was done at depth under the town of Murdochville. There is no known impact on the town.
  • Copper Cliff, Sudbury, Ontario: Most of the mine workings underlie the mine property. Some drifts and cross cuts occur at depth under the north part of the Copper Cliff townsite and should have no impact on the surface. The 880 ore zone occurs at depth under the north part of the townsite. Closure Plan reports indicate that this zone is being backfilled.
  • Falconbridge Mine, Sudbury, Ontario: This mine has ceased to operate, but an active smelter is present at the site. The town is adjacent to the mine and smelter complex. Three levels of drifts run under the north part of the town and continue west with no impact on the town. There apparently was no mining done under the town.
  • Kirkland Lake, Ontario: Several gold mines operated in the area in the 1900's. The town was built because of mining activity. Most mine workings underlie company property and are fenced and capped to prevent inadvertent access. Recent studies at the abandoned Toburn Mine have found mine workings beneath town infrastructure. It would appear that this infrastructure was built on top of existing mine workings without regard for stability of the underlying crown pillars. A remedial work plan is being developed by the Ontario government.
  • Cobalt, Ontario: Many silver mines operated in vicinity of this town in the early 1900's. Homes and town infrastructure were built on top of existing mine workings with no regard for stability of underlying crown pillars. Subsidence problems existed in the town for many years. The Ontario government spent several millions of dollars in the 1980's and 1990's for geotechnical testing and remedial work.
  • East Malartic Mine, Malartic, Québec: Mining had been completed under the town resulting in problems. At the beginning of the 1980's, several homes had to be moved or demolished. Some streets in the town were damaged by subsidence.
  • Chibougamau, Québec: Major discoveries of copper orebodies were made in the 1950's. Much of the mining was under Dore Lake. Some dwellings were built at the minesites but were owned by the mining companies. The town of Chibougamau was built several kilometers to the west of the copper mines to house and serve the mine workers.
  • Glace Bay, Nova Scotia: Coal mines were established beneath Glace Bay in the early 1900's. Town infrastructure and dwellings have been affected by many subsidence problems over the years.
  • Creighton Mine, Sudbury, Ontario: All mine workings are within the mining property. There are no homes on the site. All company homes were removed from the nearby townsite in the 1900's.
  • Macassa Mine, Kirkland Lake, Ontario: There are no residential areas above this mine.
  • South Mine, Sudbury, Ontario: See comments for Copper Cliff. (The mine workings are interconnected.)
  • Wright Hargrave Mine, Kirkland Lake, Ontario: Most of the mine workings underlie company property. The mine was to be flooded after mining of the crown pillars. Much of the site will be water covered to closely follow the contours of the original lake - Kirkland Lake. Some workings underlie town infrastructure. Testing and remedial work has been completed for this area.
  • Lake Shore Mine, Kirkland Lake, Ontario: See comments for Wright Hargrave Mine. (The mine workings are interconnected.)
  • Frood-Stobie Mine, Sudbury, Ontario: All mine workings are within the mining property. There are no homes on the site.

2.1 SUBSIDENCE

In their mining text "Subsidence - Occurrence, Prediction and Control", B. N. Whittaker and D.J. Reddish state that: "The term subsidence as applied to the earth's surface normally refers to a surface point sinking to a lower level, and can include a structure settling into the ground or the ground itself lowering and carrying the structure with it, or even a surface layer collapsing into an underground cavity."

Although rare, subsidence due to mining operations has occurred in various parts of Canada and has been the result of rock mass failure mechanisms such as caving, raveling and strata failures. Notable cases of subsidence caused by rock mass failure have occurred in the municipal areas of Cobalt, Timmins and Windsor in Ontario and the Pictou County area of Nova Scotia. Subsidence, due to the settling of backfill in the former Moneta and Hollinger, produced many problems within the city of Timmins. Damage in mining municipalities has included cracked and distorted homes, and unstable openings near buildings or under roads. Although not yet damaged, many homes and buildings in residential areas have had to be moved or demolished because of unstable ground being detected by geotechnical testing.

2.2 DEALING WITH SUBSIDENCE

Damage or threat of damage by subsidence in Canadian residential areas has occurred primarily in areas of abandoned mines or at old operating mines that have since closed. Modern mining techniques developed over the last twenty years have eliminated or greatly reduced the risk of subsidence for those mineral deposits near or under residential areas in Canada. In the case of newly discovered mines, residential areas are built at locations remote from the minesites. Abandoned mine inventories are being created in Canada for use by planners in the creation of "official plans" for municipalities.

3.0 MINING IN CANADA

In Canada the management of natural resources comes under Provincial jurisdiction. The Federal government has responsibility for mining in the Territories. A multitude of policies and regulations thus occur at all three levels of government - federal, provincial and municipal. The following discussion of mining in Canada describes the general nature of policies and practices in Canada with specific Acts being mentioned in various examples. Laws and policies affecting mining are similar across Canada, with differences mainly reflecting the differing types of mineral deposits in the country. Detailed information can be found in published federal and provincial statutes.

3.1 THE RIGHT TO OBTAIN AND HOLD MINING LANDS

Mining lands tenure can normally be held in the form of staked, leased and patented claims. Exploration is sometimes granted through concessions or exploratory licences of occupation. Rules and regulations for acquiring and holding mining lands are controlled by legislation such as provincial mining acts.

3.1.1 Bounty of Nature

Canadian mining laws have been influenced by the "Bounty of Nature" principle. Established in the 1700's, the"Bounty of Nature" principle suggests that minerals and forests should belong to the public. All mineral deposits (known or undiscovered) would thus belong to the Crown. If, for example, a prospector or mining exploration company discovered a mineral deposit, they may, through legislation, be granted tenure for a limited period of time (usually a 21-year lease). The prospector or mining exploration company would find though, that the mining lands have two types of status: "Surface Rights" and "Mining Rights". This separation of rights appears to have flowed from the "Bounty of Nature" principle - allowing individuals to occupy the land surface without gaining title to any underlying mineral deposits.

If the prospector or mining exploration company were to acquire mining lands on "Crown (public) Land", the property would normally include "Mining Rights" and access to the "Surface Rights". If, however, the mining property was acquired on private land, tenure would usually be only for the "Mining Rights". Title for the "Surface Rights" could possibly be purchased from the "Surface Rights" owner.

A complicating factor has arisen in that there were periods in Canada where the "Bounty of Nature" principle was relaxed. During these times prospectors and mining exploration companies were allowed to bring their mining properties to full patent. Thus a company or individual could obtain complete ownership and title of both the "Surface Rights" and "Mining Rights". In practice, this has led to many mining companies, during or at the cessation of mining operations, to sell off the "Surface Rights". In some cases the purchasers of these "Surface Rights" would find their properties to be impacted by problems related to past mining operations.

3.1.2 "New" verus "Old" Mining Lands

Mining exploration and development projects can be directed to "New" mining lands - where no previous mining has occurred and no other individuals or companies have title. This generally would occur on Crown Land and be generated by new information on the geology and minerals of the area. Projects directed to "Old" mining lands would be the result of not only new information on the geology and the minerals, but possibly that "Old" mining lands have become available for exploration. The availability of the "Old" mining land could be the result of: a) the previous mining claims reverting to the Crown, or b) the company has negotiated a deal with the current "Mining Rights" holder.

3.1.3 Legal Implication Concerning Surface and Mining Rights

Laws governing rights and privileges of surface rights and mining rights holders have evolved over the years. Variations occur from province to province. Compensation by the mining rights holder for damage to the property of the surface rights holder is a common requirement. Deeds or title documents must be examined on a case by case basis to determine the exact rights and privileges for each property.

3.2 MINING RIGHTS IN EXISTING TOWNS

3.2.1 "New" Mining Lands

It is normally a very tedious procedure to acquire "New" mining lands in organized municipalities. Exceptions do occur where a municipality has previously designated certain tracts of land for mining/industrial use in their "Official Plans" under a Municipal Planning Act. In Ontario, a prospector or mining exploration company must obtain Ministerial consent to stake mining claims in subdivisions designated for residential purposes. Such consent is considered almost impossible to obtain.

3.2.2 "Old" Mining Lands

The situation is somewhat different for "Old" mining lands. Many mining towns across Canada have an existing fabric of mining claims on record where the "Mining Rights" are held under patent. Most, if not all, of these claims were acquired by prospectors and mining exploration companies during the initial discovery and development of a new mineral deposit. As the mining towns grew, pressure mounted to obtain land for homes and town infrastructure. "Surface Rights" were acquired, usually in piecemeal fashion, and towns gradually spread out on top of lands where the "Mining Rights" were controlled by other parties. The deeds for many, if not most, homes in mining towns show that the "Mining Rights" belong to someone else. In some cases, homes and infrastructure have been built on top of existing mine workings.

4.0 EXPLORATION PROJECTS

Mining exploration programs are generally conducted only on lands where the company or individual is in control of the "Mining Rights". To do otherwise introduces the risk that a second party could acquire the "Mining Rights" and thus benefit from the effort and expense put out by the first party.

4.1 PERMISSION TO EXPLORE

Permission to explore is generally automatic unless it is determined that the program could cause some impact to the environment. Exploration projects are subject to all existing environmental laws. Application for various permits triggers review by government officials. This would usually generate some conditions, such as to avoid damage to fish spawning grounds, etc.

4.2 ADVANCED EXPLORATION

Public notice, a Closure (reclamation) Plan and some form of financial assurance are generally required for advanced exploration projects. This type of exploration is defined under legislation and entails such activities as extensive trenching, shaft sinking, bulk sampling, construction of test mills, etc. The purpose of public notice is to remove the surprise element from the exploration venture and thus allow for timely public participation. The advanced exploration project would be subject to all existing environmental laws.

5.0 MINING OPERATIONS

Mining operations are generally only conducted on lands where the company or individual is in control of the "Mining Rights". Permission to start up mining operations is not automatic. The term "Mining Rights" refers only to the type land tenure. The holder of "Mining Rights" does not necessarily have "The consent to mine".

5.1 CLOSURE PLAN

Canadian mining laws now require some form of acceptable "Closure Plan" be prepared by the proponent before commencement of mining operations. The intent of a "Closure Plan" is to ensure that upon closing, a mine site will not pose any threat to public health and safety, or cause environmental damage. The Closure Plan is also to address rehabilitation and future use of the land.

Acceptance of a "Closure Plan" does not affect requirements under other statutes. For example, in Ontario a proponent must meet statutory requirements of many laws including: Mining Act, Forest Fire Prevention Act, Lakes and Rivers Improvement Act, Federal Fisheries Act, Public Lands Act, Occupational Health and Safety Act, Ontario Water Resources Act, Environmental Protection Act, Gasoline Handling Act, and the Planning Act.

The "Closure Plan" is in reality an "Opening Plan" as it requires a comprehensive technical and public review of the proposed mining operation before production can commence. The proponent must report on the current state and use of the land before the mine is developed. The "Closure Plan" must also state the intended use of the land when production ceases and must address all physical and chemical stability issues (such as subsidence and acid mine drainage concerns). It must also provide financial assurance to cover cost of rehabilitation.

5.2 INNOVATION

A number of practices have been developing over the years in Canada to end the legacy of mine hazards. Residential areas for employees of new mines are now at sites remote from the mining operation. Government mining agencies have begun creating databases to provide easier public access to information on mining lands. Land use planning reports map out areas of high mineral potential and areas of mine hazards. Municipalities are thus aware of zones not suitable for town development. Technical advances have been made for locating, measuring and testing abandoned workings. Cemented backfill techniques have been developed to provide stability by tight-fill of empty mine workings. Monitoring devices have become more sophisticated.

It is in the best interest of the mine operator to use modern methods to maintain stable mine workings and to be free of environmental problems. Uncontrolled rockbursts, caving and subsidence can cause serious injury or death to their workers possibly invoking severe penalties under health and safety legislation. In addition, collapse of mine workings could: damage equipment, cause dilution of ore or loss of an orebody, and incur expensive surface rehabilitation costs. Environmental damage could cause the temporary or permanent loss of operating permits, severe fines and very expensive cleanup costs. Legislative requirements exist for compensation to be made for any harm to the "Surface Rights".

6.0 MINING UNDER TOWNS

6.1 POLICIES AND STATUTES

Each Province or Territory has policies and statutes controlling mine development. A common theme in all jurisdictions is the maintenance of public heath and safety and protection of the environment, while promoting economic growth through development of mineral resources. The Federal Fisheries Act must be complied with in all situations - no matter what agreements may have been made at municipal and provincial levels. Federal Acts have legislative priority in Canada.

Having a single set of rules and regulations for mine development for use throughout the country would be very difficult. Each site has its own unique characteristics and setting: type of minerals, geology, size and geometry of the mineral deposit, rock strengths and structural features, value of the mineral deposit, amount and type of waste products, value of the surface and civic structures, type of ecosystem, etc.

6.2 PLANNING FOR CLOSURE

Probably one of the most significant recent changes to mining law was introduced by the Carter Administration of the United States in the mid 1970's. The Surface Mining and Reclamation Act implanted the legal requirement of planning for closure prior to the start up of coal mining operations. A reclamation plan and bond had to be prepared as part of the permitting process. This concept has been adopted throughout Canada and applies to all mining operations. The United States has not been successful in passing similar legislation for hard rock (metalliferous) mining under the Federal mining act.

One of the most important parts of mine permit legislation in Canada is the requirement for public notice and consultation. The proponent of mine operations and government officials must allow for public discussion and review of closure plans with all stakeholders. Officials of all levels of government must then consider all concerns and suggestions that arise before giving the go ahead for mining operations.

6.3 CLOSURE PLAN REVIEW

The review of a closure plan could, for example, bring out concern for subsidence, acid mine drainage or threat to ground water quality in a town. Officials would then have to show to the stakeholders and government regulators that these concerns are addressed. For example, in the case of subsidence, the proponent could be required to commission geotechnical studies to first, determine if subsidence were likely to happen, and then outline what steps would be taken during mining operations to prevent subsidence. Such studies would be done by a "qualified person" under applicable legislation. In the Province of Ontario, this work would have to meet requirements of the Mine Rehabilitation Code of Ontario. Other concerns such as presence of xanthates or cyanide in tailings, or the acid generating potential of tailings would have to be reviewed and dealt with accordingly.

For example, during closure plan review of a mine with shallow stopes (within 30 meters of surface) the proponent would be expected to first, discuss the potential for subsidence, and then outline the approach used to prevent subsidence from happening. Information on rock mass characteristics (site geology, structural distribution, rock mass quality) would have to be collected. Rock mechanic specialists would conduct these studies by methods such as: geological mapping - noting shear zones, faults, joint patterns; drilling to determine rock quality and location of voids such as old mining workings; and using ground penetrating radar and other geophysical techniques to help locate suspected voids or old mine workings. Stability analysis techniques of numerical modelling, limit equilibrium equations and empirical approaches could be used to predict rock mass behaviour. This information would help determine the type of mining and backfill methods to be used. The backfill could be chemically treated to prevent toxic reagent and acid mine drainage problems.

7.0 CONSULTANT'S QUALIFICATIONS - DISCLAIMER

This study was conducted by William O. Mackasey of WOM Geological Associates Inc. Mr. Mackasey is a graduate geologist with more than 40 years experience in the Canadian mining industry. His educational background includes six years of academic training to obtain a B. Sc. and M. Sc. in geological sciences. Mr. Mackasey is a Fellow of the Geological Association of Canada, and a Member of the Canadian Institute of Mining and Metallurgy, the Canadian Land Reclamation Association and the Association of Geoscientists of Ontario.

The preparation of this report was undertaken with generally accepted professional scientific standards. However, no guarantee or warranty is provided as to structural or environmental status of the mines or towns listed in this report, nor of the interpretation of government policies or statutes. The comments or opinions are based solely on the review of written documents. Mr. Mackasey did not visit the mine sites as a result of this project, nor were there any scientific tasks or procedures undertaken by him. The comments and opinions are to the best of his knowledge based on forty years experience in the mining industry. Technical information on physical and chemical stability of the mine sites should be obtained from appropriate geotechnical engineers and environmental geochemical specialists. Interpretation of government policies and statutes should be obtained from appropriate legal specialists.

This study has been completed for the exclusive use of MiningWatch Canada. Any use which a third party makes of this study, or any reliance on or decisions to be made based on it, are the responsibility of such third parties. WOM Geological Associates Inc. accepts no responsibility for damages, if any, suffered by a third party as a result of decisions made or actions based on this study.

Original signed by William Mackasey

W.O. Mackasey, Director on behalf of
WOM Geological Associates Inc.
April 25, 2002

WOM Geological Associates Inc.
140 Crater Crescent
Sudbury, Ontario
Canada P3E 5Y8