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Informational Letter IL 91-13

January 31, 1992

To: All Counties, Municipal Districts, Cities, Towns, Improvement Districts, and Regional Planning Commissions

IMPACT OF ABANDONED COAL MINES ON SURFACE DEVELOPMENTS

Over 2000 coal mines have operated in the Province of Alberta since mining began in the 1850s. Except for the large surface mines operated during the past 25 years, most of the coal mines used underground mining techniques and were relatively shallow in depth (depths from 10 to 100 metres).

While the passage of time usually results in the eventual collapse and stabilization of the ground over these underground mines, the process is unpredictable. In certain areas of the Province subsidence, either in the form of depressions or open holes, still occurs 40 to 50 years after the termination of mining. Fortunately such occurrences have resulted in very little property damage, but they have created considerable concern with respect to future public safety and property damage. The ERCB believes it is extremely important that any development over abandoned underground coal mines takes into account the presence of previous mines and makes an assessment of the hazard which these mines could present to property or to safety of the public.

In 1985 the ERCB published a "Coal Mine Atlas" (ERCB 85-45) which included information as to the location of all known abandoned mines in the Province. This information is based on microfiched plans of the mines, copies of which can be obtained through the ERCB's Information Services Section (297-8190) in Calgary.

The ERCB recommends that the Coal Mine Atlas be used by anyone involved in surface development or in the approval of surface development as an initial check to ascertain if a particular parcel of land is underlain by an abandoned underground coal mine. If necessary, verification and more detail are available by use of the microfiched plans or the ERCB/Municipal referral system. It is the ERCB's belief that, once the existence of an abandoned mine is verified, the developer and/or the development approval authority must take reasonable steps to establish whether or not this mine would result in any constraints to the proposed development.

In the interest of assisting development approval authorities and ultimately the individual developers in identifying the location of abandoned mines, the ERCB is prepared to supply mylar overlays of the mines or, alternatively, composite mine/town or municipality maps. These will be available on request at a price equivalent to the ERCB's costs.

Should you be interested in this service, or require further information, please contact Barry Stewart (297-8519) in the ERCB Coal Department in Calgary.

[Original signed by]

B.F. Bietz
Board Member