The Tyee, a local Vancouver newspaper at this link, with some amazement recognizes with regard to the Morgenstern, Vick, and Van Zyl panel:
In the probe the government has set up, there is mandated virtually no investigation of the role of the mining or environment ministries. There are 14 terms of reference, 13 of which deal strictly with the collapse itself, one of which may be interpreted as giving the panel members the right to look at the government’s role if they feel so inclined.
It does not take brain surgery to recognize that this panel is unsuited to look at any regulatory role the government should have played. That’s not their bag. They are picked for their skills at investigating mining methods, not regulation enforcement.
To look at a government role and the law and regulations requires a specific sort of person, and it’s difficult to think of anyone suited other than a highly experienced lawyer or judge. To even begin to know the right questions requires a training that a scientist doesn’t, by nature, have. He or she may be highly skilled and trained, but not for this purpose.
I looked up the scope of work for the panel. Here it is:
The purpose of the panel is to investigate into and report on the cause of the failure of the tailings storage facility that occurred on Aug. 4, 2014, at the Mount Polley mine in B.C. The panel will report on the cause of the failure of the tailings storage facility at the Mount Polley mine. In addition, the panel may make recommendations to government on actions that could be taken to ensure that a similar failure does not occur at other mine sites in B.C.
The panel is authorized, as part of its investigation and report, to comment on what actions could have been taken to prevent this failure and to identify practices or successes in other jurisdictions that could be considered for implementation in B.C.
Scope of Review
In its report, it is expected the panel will:
- identify any mechanism(s) of failure of the tailings storage facility;
- identify any technical, management, or other practices that may have enabled or contributed to the mechanism(s) of failure. This may include an independent review of the design, construction, operation, maintenance, surveillance and regulation of the facility;
- identify any changes that could be considered to reduce the potential for future such occurrences.
In conducting its investigation and in order to prepare its report into the cause of the failure of the tailings storage facility at the Mount Polley mine, the Panel may, at its discretion, and as it deems necessary, examine some or all of the following in respect of the Mount Polley mine in B.C.:
- geotechnical designs of the dams and structures associated with the TSF, including both intact and breached embankments, and including both the original design and all lifts of the embankment structure;
- the adequacy of geotechnical investigations completed throughout design and operation of the facility;
- interpretation of results of geotechnical investigations and associated laboratory testing;
- patterns, trends, and relationships in instrumentation behaviour;
- interpretation of instrumentation and performance data in relation to dam behaviour;
- whether or not dam instrumentation and monitoring was consistent with standards of practice;
- appropriateness of methods and input parameters for geotechnical analyses;
- materials, methods, procedures, and quality assurance/quality control practices for dam construction and modification, and a determination with respect to whether or not construction was completed in general conformance with the design;
- water balance and water quality as they relate to the TSF breach;
- operational procedures and planning for tailings deposition and water management;
- inspection and surveillance procedures and implementation;
- the engineer of record’s field reviews to ensure that construction was in conformance with design;
- regulatory oversight by the Ministry of Energy and Mines and the Ministry of Environment; and
- other matters the Panel deems appropriate to be examined.
Precisely. The panel is intended to tell geotechnical and tailings engineers what went wrong, be it design, construction, or operation. The panel may comment on regulatory oversight with respect to the engineering, but I doubt if it is intended to look into regulatory and policy procedures. Indeed Messrs. Morgenstern, Vick, and Van Zyl are not the best people to do that. That undoubtedly falls outside of their scope of experience and competence.
All this debate set me thinking, so to relieve the pressure, I sketched the following which shows my current favorite explanation for failure. I wonder if there was not a change of foundation conditions at the corner. On one side the foundation materials were good and stiff and on the other side a bit softer. Hence there would have been differential settlement leading to embankment cracking.
As I wrote in a previous posting:
Now take a look at the photo below, obviously taken some time after the first one. They are still discharging tailings from the north side and they are still creating a fan beach with its crest near the corner that failed.
Now I see something very interesting on this photo. Notice that the fan beach of tailings seems to be bounded to the left of the fan by a topographic rise–the kind of green area on the left hand side of the white tailings. Now draw a line along the intersection of the green (vegetation?) and the white tailings. Draw the line upwards, and it goes through the dike or embankment and seems to continue on the downstream side of the embankment.
Is this “line” a distinct topographic break–maybe there was a cliff along that line and that is why the tailings fan did not rise up above it. Maybe there was a bedrock break along that line—so to the left, the foundation was solid. And maybe to the right of the line, the foundation was soft soil—and the foundation had a tendency to settle when loaded.
We will know someday. So to pass the time I compiled the following fault tree of possible failure modes. Set to do this by the previous posting where I wrote:
At this link is a great Master thesis recently completed by Genki Taguchi, a student of the University of British Columbia. Dirk Van Zyl supervised the thesis. And if that link does not work, here is a second link. A great job by both. And a document which should become required reading by all in tailings. The thesis is call Fault Tree Analysis of Slurry and Dewatered Tailings Management – A Framework.
As Dirk was the supervisor, he may choose to adopt this approach for the panel. It will be fun to see.