Editor: Thank you for publishing my letter entitled, ‘More needs to be done in tackling the undermining issue’ in your paper dated Nov. 24.
In the fourth paragraph of my letter I mistakenly wrote, Consequently it is impossible to mitigate to a 100 per cent level of safety as a representative of Quantum Place claimed recently in a Council meeting. No engineer worth their salt would make that claim.
On checking the video of the council meeting, I found this claim was not made by the representative of QuantumPlace and I do apologize to QuantumPlace for this mistake on my part. It also occurs to me the paragraph might be read as a criticism of the engineers from Quantum or Golder Associates working on the project. That was certainly neither my meaning nor my intent.
Since 2001, I’ve not had any undermining mitigation or assessment involvement with Three Sisters. My body of work still forms part of the base of knowledge used today in the mitigation of undermining, including a presentation to the NRCB in 1992.
I explained then how development of mined zones was feasible in medium constraint zones where “building would generally be allowed in this area depending on the economic viability of the (mitigation) work. High constraint zones were noted to be possible for some types of development depending on the economics of (mitigation) work.
In a more recent meeting that I attended on Aug. 18 2016, with QuantumPlace and Golder, they explained that a greater technical understanding of undermining has developed since my involvement in Three Sisters lands. To begin, each participant provided a description of his experience relevant to undermining, mitigation and construction. The main discussion centred on Golder’s past use and experience of;
Stabilization of mine workings by injecting a paste consisting of cement, water and graded fill in two stages to ensure a high proportion of filled space and minimum voids (note that I directed the first use of paste injection into abandoned mine workings in Canmore on the Homesteads property in 1996).
Structural modification of foundations and structures to accept limited surface movement above mine workings without mitigation (I have no personal experience in this area).
Risk assessment procedures which determine the degree of risk remaining after either of the above two options have been employed. During my 10 years as director of Norwest’s work for Three Sisters Golf Resorts, from 1990 to 2001, I employed similar risk assessment technology.
I understand these new learnings are based on hundreds of boreholes plus many more studies, field assessments, site reconnaissance work and physical mitigation work undertaken by acknowledged undermining experts.
The Aug. 18 meeting highlighted the complex issue of how to develop on mined land and of the consequences to everyone if not carried out with due regard for safety. I look forward to seeing additional information from TSMV so our community can be informed and better understand the scope, processes and associated risks and the ways in which TSMV propose to effectively and safely develop those parts of their property which are affected by undermining.
As I understand it, Three Sisters Mountain Village is committed to and bound by a strong, independent, mitigation process established under provincial regulation and that they will continue to apply new learnings to the mitigation of undermining on the Three Sisters lands.
Gerry Stephenson,
Canmore
