Dominion No. 25

The Dominion No. 25 coal mine started and ended with challenges caused by water.

The mine was opened in 1941 on the outcrop of the Gardiner Seam at Gardiner Mines, Cape Breton.

The Gardiner Seam at this location had an average height of four feet. The coal was good quality, suitable for steelmaking. (There are two main types of coal: thermal coal, which is used to generate electricity, including half of Nova Scotia’s power; and metallurgical coal, which is used to make steel. Steel is mainly iron and carbon, and the carbon is derived from steelmaking coal).

All transportation and machinery in the mine were powered by electricity generated by a motor generator in the mine’s surface plant.

The coal was delivered to centralized loading stations by 30-inch-wide conveyor belts.

The main transportation system was by 20-ton Electric Trolley Locomotive, which used three locomotives to deliver the coal to the screening plant at surface.

Shortly after Dominion No. 25 opened, two men drowned on May 22, 1943, when miners accidentally broke through into the flooded workings of the Old Gardiner Mine. The Old Gardiner Mine opened in 1870 and was closed in 1893 after it was purchased by the Dominion Coal Company. During its somewhat intermittent life, the Old Gardiner Mine produced 132,995 long tons of coal.

An inquiry into the 1943 drownings found that the workings in the Old Gardiner Mine had advanced 325 feet beyond the location shown on the mine’s plans, which were a half-century old when No. 25 opened. As a result, the miners in No. 25 did not know that the old mine was in their path.

No. 25 closed because there was water in a geological fault about 60 feet above the coal seam. This caused a flood in the lower portion of the mine in 1954. The inflow of water increased between January 16 and March 18 that year from 100 gallons per minute to a maximum of 1954 gallons per minute. (The water inflow being the same figure as the year it occurred was an odd coincidence).

Extensive investigation underground and on the surface failed to locate the source of the water, or to isolate it from the rest of the mine. Given the quantity and relatively high pressure of the water inflow, the mine was closed for safety reasons.

When the mine opened in 1941, reserves were estimated to be 3.5 million tons of coal. When the mine closed on August 7, 1959, it had produced 2,071,639 long tons of coal from a working area of 128 acres.

The mine was reclaimed in the early 2000s, pictures below.

Today, mines and quarries are often reclaimed during operations and must be fully reclaimed shortly after extraction is done. Before even starting to mine, companies must get government approval of reclamation plans and post reclamation bonds (money in escrow, basically) that ensure funds are available to properly take care of sites.

Nova Scotia’s coal deposits started forming 300 million years ago when Nova Scotia had a tropical climate – tectonic plate movement had us in the middle of supercontinent Pangea, down around the equator.

Swamps contained dense vegetation that died, drifted to the bottom of the swamps and gradually formed peat—a soggy, sponge-like material. As the peat accumulated, the weight of the top layers compacted the lower layers by squeezing out water.

The peat was buried over time by sediments and ocean water. Deeper burial increased pressure and heat on the vegetation, causing chemical and physical changes, and pushing out oxygen. Over thousands of years, this turned the peat into the coal that still provides over half of Nova Scotia’s electricity.

Because of how it is compacted, it takes approximately 3-7 feet of plant material to form one foot of coal. A coal seam one-metre thick can represent 2,500 to 5,000 years of plant accumulation in ancient swamps.

Learn more about the Dominion Coal Company at