- 49 -
(L. MacDonald) Yes, in addition to what I think we explain as well in the
ACE Plan and elsewhere in respect to how weather-coded outages are often also tree
caused, but coded to the weather event in question, so it's at least that, and likely more,
depending on how the weather codes fall into trees.
And that range of tree-caused outages, Ms. MacDonald, has been a
relatively consistent level over the last 10 or more years?
(L. MacDonald) Subject to check, I think so, and again, depending on how
the weather relates to it. And if you want to point me to something, we can, ---
--- myself and my colleagues, talk more about that.
Mr. Goodine, Exhibit N-5, Responses to Board IRs, could we turn up Response to
Board IR-50(b), and just down at the bottom of that page, if we could see that graph? Okay.
So Ms. MacDonald, I was understanding that this graph, if you take out
the 2010 and 2014, or if you normalize those as significant events that occurred that’s
referenced in your evidence, that line, at approximately 25 percent is what I understood to
be a relatively consistent impact of trees on the system.
(L. MacDonald) Yes. Looking at it that way, you can definitely say that.
Okay. As you know, Ms. MacDonald, a significant amount of investment
has been made in vegetation management, in tree trimming, over at least the last 10 or 15
years, to the tune of millions and millions of dollars annually. Why is it that the impact that
we see of trees causing outages doesn’t seem to have changed, even though we've
invested the tens of millions of dollars that we have in that initiative?
(L. MacDonald) So broadly speaking, I would say that maintaining the level
-- perhaps it's a downward trend as well, if we look at it -- but is working in the context of
increasing occurrences and severity of those weather days that I spoke about in terms of
both the day itself that weather could be affecting the system as well as the stress in the
And so all of that taken together, we know that the frequency and the severity of
those events, the wind, for example, that causes -- typically causes the tree issues, have
been increasing, so in some ways, to be holding or slightly decreasing in terms of the
effects of that, as part of what we call maintaining and improving system performance in
the context of the increasing severity and frequency of the weather.
And going forward, Ms. MacDonald, I understand the company plans to
spend approximately $8 million in vegetation management tree trimming in the coming
years. Is that a sufficient amount, in the company's view, given the impact the trees are
having on our reliability?
(L. MacDonald) Well, we're constantly reviewing that, and if it becomes
apparent that we need to increase in a material way the size of one of those programmes,
we would bring that forward. But that is exactly the work that we're reviewing constantly,
in terms of the balance of our programme among vegetation management investment as
well as the other equipment related system-wide transmission distribution and feeder level