If I get this right, Donkin Mine management, and our provincial Department of Labour, are calling in world-renowned ground control experts to assess the Donkin geology and shine a light on how Kameron Collieries can best proceed after its 12th roof fall.
Scott Nauss, senior director of inspection and compliance for the Nova Scotia Department of Labour, says that the Donkin Mine roof-bolting plan has progressed from 8 foot- to 12 foot- and now to 20 foot-bolts and the monitoring devices, known as tell-tales, have been doubled in number. I see, that despite those ever-increasing measures, the roof falls continue unabated. I am not surprised. To steal a line from Yogi Berra – it’s déjà vu all over again.
As some readers may remember, the Phalen Mine suffered a similar fate in the deepest sections of the mine ending with the boondoggle known as the 8 East roof control disaster. Devco’s roof control plan started off with straps, short bolts and tell-tales, then longer bolts and more tell-tales, then longer cable bolts and even more tell-tales with closer spacing. They tried resin, grout, tensar mesh, cable trusses, supplementary steel-sets and bolts rammed into the sides of the level to no avail. Near the end, the miners joked that there was enough steel in the 8 East bottom level to keep Sysco operating.
The combination of predictable and preventable factors continued to challenge the skills and courage of our bare-faced miners and ultimately, the UMWA and Devco agreed to call in the experts from away. What they told us was not unexpected – “the monitoring and support activities at Phalen were superior to almost any mine in North America.” The miners, who risked their lives everyday in recovery efforts, saw first hand that Mother Nature didn’t care.
Miner underground posing with coal digger, 1 December 1987. (Photo by Owen Fitzgerald, Beaton Institute, Cape Breton University)
In October 1998, the UMWA retained the services of Christopher Mark, Ph.D., P.E., of the National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory, Disaster Prevention and Response Branch. He is a world-renowned expert on ground control. Dr. Mark spent a week in Cape Breton studying the Phalen Mine situation and wrote a comprehensive report which I have in front of me right now. I copied his report for the media and politicians so Mr. Nauss should have access to both the UMWA and Devco expert reports on roof control in a submarine coal mine.
Dr. Mark identified a number of contributing factors relevant to the Phalen dilemma: 1) the depth of mining and vertical stress; 2) multiple seam interactions; 3) weak roof geology; 4) horizontal stress; 5) entry widths and 6) time, entry profile and weathering of rock. His report was very interesting but his parting words were the key takeaway for me: “If they keep doing what they’re doing, they’ll keep getting what they’re getting.” He was right – on 13 September 1999 Devco announced the closure of Phalen Mine for “safety reasons” related to uncontrollable roof falls. I provide Dr. Mark’s words of wisdom to Kameron Collieries – free of charge.
Granted, Kameron Collieries operates a room-and-pillar mine on the Harbour Seam, not a longwall mine on the Phalen seam, but don’t those words of wisdom seem fitting after 12 roof falls at Donkin Mine? Further, the 11 coal seams in the Sydney coal field, share a common geological history and the Donkin Block contains all 11 seams and the same geological characteristics. Is Donkin somehow different than Phalen, Lingan or Prince Mines with respect to the failure of roof bolts to secure weak roof? I’m thinking not, but two more local examples can help make the retrospective point:
1) Local mining experts will recall that the Lingan ‘A’ room-and pillar section operated in the shallow workings of the Harbour seam between 1978 and 1983. The roof-bolting support system in Lingan ‘A’ was abandoned in favor of steel-arches, booms and legs in the deeper sections of Lingan Mine. I worked there — the steel supports were a long-term success.
2) A brief foray into roof bolting in the shallow sections of Prince Mine in the 1970s, failed due to poor geology in the Hub seam. Until it closed in 2001, Prince Mine relied successfully on steel booms and legs for stable roof control – I worked there too and saw the long-term benefits of steel supports first hand.
There is good reason why Donkin’s two main tunnels have survived, without major roof control problems, for more than three decades – the tunnels are supported by steel rails – not roof bolts.
So, what does all this mean? In short: the deeper you go underground, the less likely roof bolts will survive Mother Mature’s geologic forces; steel arch rails and steel beams and legs have proven to be better suited to long-term roof stability in Cape Breton’s submarine coal mines and you only get so many chances to do something the right way.
Some of my old mining buddies put the Donkin situation more bluntly: “She’s the wrong pit for roof bolts, boys.” I agree with their expertise.
And after 12 roof falls — I think Mother Nature agrees too.
Steve Drake, 4th generation Cape Breton coal miner
New Waterford
