Not Your Grandfathers Mining Industry, Nova Scotia, Canada

Port Hood 1911 Flood

In 1911, the Port Hood coal mine was flooded with salty water. The mine extracted under the ocean floor so it was assumed that the water came from the sea above, but it took repeated investigations and several decades to determine the flood’s mysterious source.

The #1 (aka Tremain) slope/tunnel opened in Port Hood, Inverness County, in 1875 but lack of a good shipping point made mining unprofitable (The nearby Garson mine was also sometimes called the #1 but we refer in this write up to the Tremain mine.)

The #1 closed in 1878 after a boiler explosion but was reopened in 1900 by the Port Hood Coal Mining Company. A wharf was built in 1901 solving the shipping problem. The mine was taken over by the Port Hood-Richmond Railway and Coal Company in 1906.

A 1908 explosion killed ten men in the mine. Six were locals. Four had arrived so recently from Bulgaria that no one knew their first names or how to contact their families in Bulgaria.

About 2:00 p.m. on Thursday, June 22, 1911, the #1’s underground manager, Edward Doyle, was told that water was entering the mine. He immediately went to inspect the leak but, according to the Nova Scotia Department of Mines’ annual report for that year, he “found only a few drops coming from the roof, the quantity being so small that it could not be estimated. He did not consider the matter serious….”

Doyle thought the leak was just the small amount of water that often preceded a roof fall in the #1. Roof falls are a natural and common adjustment of the geology in underground mines. As cavities are hollowed out by mining, the rock above sometimes shifts or falls in order to accommodate the added stress created by the removal of the supporting rock below. Today, sophisticated technology is used to monitor for potential roofs falls and a variety of tools are used to prevent them, such as roof supports, steel netting that prevents rock from falling, and roof bolts which are huge (often 4-8 feet long) metal rods driven into the rock to hold it together.

Doyle believed a roof fall was imminent, and that the water inflow would stop after, as it usually did.

The mine’s general manager, R. J. Law, also went to see the leak. Law calculated that there were 941 feet of rock cover between the mine and the ocean floor in that part of the mine (No. 7 pillar, No. 1 balance off No. 5 north level). That is a lot of rock cover, far more than is ordinarily required to prevent sea water leaking into a submarine mine, so Law thought “everything was all right and that there was nothing to fear,” as the Department’s annual report put it.

Before leaving the mine at 6:00 p.m., Doyle told the night overman (boss) to pay particular attention to the area where the roof fall was expected. Not long after 6:00 p.m., Doyle was summoned back to the mine because the roof fall had taken place.

Instead of stopping, as Doyle had predicted, the leak had increased dramatically. It was later calculated that the initial inrush of water was at a rate of about 3000 gallons per minute.

Doyle sent for Law and they inspected the mine together. They found that water was already about a foot deep in the affected area. Pumps were brought in, but they could not keep up with the inflow.

Mine manger John Henderson arrived about 5:00 a.m. on Friday, June 23, and toured the mine with his colleagues. Water was still coming in from the mine’s roof (ceiling), the water level was rising quickly, and a stream three feet wide and one foot deep was running down a tunnel. They decided to build dams to contain the water.

Efforts were made to gather materials to build the dams, but the company had little, if any, on hand. Men also prepared the places where the dams would be located. However, the water was rising too quickly, and the plan to build the dams was abandoned at 11:00 a.m.

It was around this time that Department of Mines deputy inspector W. F. Davis was summoned by telegraph. He was underground inspecting the Inverness coal mine but when he reached surface, he found that the Inverness mine’s superintendent, J. McGillivray, had arranged for a train to take Davis to Port Hood.

Davis arrived in Port Hood about 2:00 p.m. and participated in discussions about the possibility of building five dams further back, in the hope that they would save the mine’s upper workings. Davis had mixed feelings: “I felt that owing to the great pressure that had to be contended with it would be impossible to construct anything in so short a time that would withstand the pressure. However, it appeared to be the only thing to do under the circumstances and it was considered advisable to try it.”

Davis was referencing the fact that the dams, built very quickly with improper materials, would have to withstand about 400 pounds of water pressure per square inch.

At this point, something unusual happened. The men refused to build the dams unless the Department of Mines guaranteed that they would be paid. The men were perhaps concerned that if the flood shut the mine down, they might not get paid for this difficult and potentially dangerous work.

Davis and other provincial government officials were doubtful that the dam-building plan would be successful, but the government nonetheless agreed to make sure the men would be paid and that the cost of the materials would be covered. Their overriding concern was to save the mine.

Work on the dams started about 3:00 p.m. on Friday, June 23. However, by midnight on Sunday, June 25, the water had risen to where the dams were being built and work had to be abandoned. The men now focussed on removing equipment and materials from the mine, and pumps, boxes, rails and pipes were hauled out.

Efforts to save the mine ceased.

The flood water eventually accomplished what human hands could not – it caused the main tunnel’s walls and roof to cave in, and the mud and rock created a dam that contained the water.

One of the first things deputy inspector Davis did when he arrived onsite on the Friday was taste the flood water. Like everyone else, he found it to be salty and assumed the water was leaking from Port Hood’s harbour, through cracks in the surrounding geology, into the mine. All the senior mine and government staff agreed that it was sea water.

However, a suggestion was subsequently made that the water could have come from Little River, which was above the mine workings. In the hope that the mine could be saved, boreholes were drilled at surface in the second half of 1911 to learn more about the geology overlying the mine and to figure out where the flood water had come from.

This attempt to solve the mystery was unsuccessful.

Two years later, the 1913 Department of Mines annual report detailed additional investigations. Tide levels in Port Hood harbour and fluctuations in the flood water were measured every half hour for a week to see if there was a correlation between the two. The results were inconclusive.

Measurements were made to determine whether there were correlations between changes in Little River’s water levels and the water in the mine. There was no apparent connection. Water tests also found that the flood water contained much more salt than the water in Little River, so investigators decided Little River was not the flood’s source.

The pond on the beach by Little River was also investigated but it, too, was not salty, so it was rejected as the source of the flood water.

The 1913 investigators came to the same conclusion everyone did in 1911 – the water was travelling through cracks in rock from the ocean to the mine.

But they were wrong. Over three decades went by before another investigation solved the mystery of the #1’s flood.

In 1942, the Department of Mines did some work rehabilitating the main tunnel so the flood could be studied. However, subsequent bootleg mining undid the rehabilitation work and left the tunnel in disrepair again.

The 1947 Department of Mines annual report said roof supports had been removed by the bootleggers and the main tunnel was partly filled with had 3-4 feet of clay and old timber in its first section. Past that, parts of the roof had caved in at several points.

This made it more difficult for the Department of Mines to accomplish its goal in 1947: “to determine whether or not the break which allowed the inflow of water in June 1911, had been sealed by silt in the intervening years.”

The main tunnel was cleaned up and roof supports were installed to make the mine safer. A small amount of tunnelling was also done, and pumps were operated for about four weeks. Several times, the pumps made progress on lowering the water level, only to have increases in inflow raise water levels again.

It was obvious that the cracks that caused the flood in 1911 were still allowing large amounts of water to enter the mine. Pumps were removed on June 28 and the water level rose 125 feet in just 18 hours.

Department of Mines staff also took water samples from the mine and Port Hood harbour. The results revealed that the source of the water was something no one had thought of in 1911-13: “From these analyses it is readily apparent that while Port Hood sea water contains less salt than average sea water (probably owing to dilution by fresh water from Little River) the mine water contains more than twice as much salt as the average sea water. The analyses support the theory that the water which is entering the mine has an underground source and passes over beds of salt in its course through the strata.”

In other words, the flood water was much too salty to be from the ocean. It was groundwater, not connected to the ocean or Little River, and it was salty because it absorbed salt as it interacted with rock underground.

Water contains minerals because it absorbs them from the rock it interacts with. This can be good and bad. Minerals are essential to health and we get many important minerals from water.

However, this process of minerals leaching into water can also cause concentrations of minerals that are a health risk. For example, many Nova Scotia wells contain amounts of uranium and arsenic that exceed drinking water guidelines because all Nova Scotia rock contains uranium and arsenic and they often leach naturally into groundwater. That is why it is important to test well water.