Monday, 10 August 2015

SERIOUS FLAWS REVEALED IN CRUMMELL'S LETTER ON NORTH SPUR

Guest Post Written by Cabot Martin:

LETTER FROM MINISTER CRUMMELL REVEALS SERIOUS FLAWS IN NORTH SPUR DAM BREAK STUDY

The North Spur stability issue is the single greatest Risk to the Muskrat Falls Project.
Nalcor’s handling of this Risk has been neither sufficient nor timely.

Based on informed expert opinion, it is apparent that (quite apart from downstream safety issues), a North Spur collapse could lead to the loss of the Province’s entire multi-billion investment in the Dams and Generating Facilities presently being constructed at Muskrat Falls and the full abandonment of the Muskrat Falls site.

On July 2, 2015, I wrote the Minister responsible for Dam Safety, Hon. Dan Crummell on this issue; early last week I received an answer from the Minister dated July 30th , 2015.

In the meantime, Nalcor posted a North Spur Dam Break analysis by Hatch Consultants dated June 26,2015 on its website. 

On August 7th, I replied to the Minister’s letter as set out below.

It points out that he is using Dam Safety Guidelines that are simply not applicable  to cases like the North Spur.

Further that Nalcor has severely undermined the scope and validity of the Hatch June 26th North Spur Dam Break Study.

The public deserves to know that this matter is being properly handled. The Minister’s letter gave me no comfort in that regard. That is why this letter was written.


August 7, 2015

The Honourable Dan Crummell
Minister of Environment and Conservation
4th Floor, West Block
Confederation Building
St. John's, NL   A1B 4J6

Dear Mr. Minister:
Thank you for your letter of July 30,2015 in response to my urgent letter of July 2,2015 concerning the North Spur stability problem at the Muskrat Falls hydro project on the Lower Churchill River in Central Labrador.

Unfortunately I can draw no comfort from your reply as it is based on a number of serious misconceptions.

(1) The Canadian Dam Association (CDA) Dam Safety Guidelines you cite are not at all applicable to the geotechnical conditions at the North Spur. Nor can they provide a proper basis for either Nalcor’s North Spur engineering design or your Department’s safety review of Nalcor’s North Spur plans.

They are applicable to the North and South Concrete Dams on the other side of Muskrat Falls but not to the North Spur.

The CDA Dam Safety Guidelines have been developed and are applicable only to dam structures where all materials used in construction of the dam in question, from the foundations up, are known as to their physical strength, chemical composition and load bearing characteristics and have been engineered and specified by competent engineers in accordance with the Guidelines.

The North Spur is not like that at all – the North Spur is a highly variable, heterogeneous natural accumulation of sand and clay which contains unstable glacio-marine clays that  have a tendency to create landslides. The North Spur also contains many relatively thin sand lens mixed in with the glacio-marine clay – such sands can act as a “trigger sand ” and play an important role in setting off a landslide.

It is not surprising then, that I am reliably informed by a very experienced  hydro engineer that the CDA Dam Safety Guidelines do not apply and are not meant to apply to situations like the North Spur.

There is no way the CDA can be held responsible for Nalcor’s flawed North Spur plan.

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Consequently you should seriously review this matter with your officials and develop a more appropriate basis for the execution of your oversight and regulatory duties.
(2) The second misconception is just as serious.

You have cited a June 26, 2015 study by Hatch entitled “North Spur Dam Break Analysis”  as a basis for your approval of Nalcor’s current activities on the North Spur.

I note that neither the Joint Review Panel in 2010 nor the Minister and officials prior to their approval of Muskrat Falls river closing permits in the spring of 2013 had the benefit of this (or any other) North Spur Dam Break Study --- which came over two and a half years after project sanction.

In any event, this new Hatch 2015 North Spur Dam Break Study is very different in scope and in other aspects from the Muskrat Falls Dam Break Studies prepared by Hatch back in 2010 for the two concrete dams at Muskrat Falls (which were filed with the Joint Review Panel).

As noted below, I am preparing a detailed analysis of the Hatch 2015 North Spur Dam Break Study and will forward it at an early date.

For now, I wish to focus on the interference by Nalcor in the work of the consultant Hatch which is neatly summed up in a single sentence in the Hatch report :

“The assumed breach bottom elevation for the analysis was specified by NE-LCP to be 20.5 m,
which is the elevation of the top of the bentonite cutoff wall.” (Hatch 2015 North Spur Dam Break Study page 2 Section 2.1).

“NE-LCP” stands, of course, for Nalcor Energy –Lower Churchill Project.

The term “breach bottom elevation” is the lowest point to which a North Spur slide and the resulting freed river will together cut the North Spur down in the event of failure.
In other words , Nalcor has “specified” (ie. imposed)  a very critical  restriction on Hatch , namely that the down cutting will end when the river gets to the top of the bentonite cutoff wall at +20.5 m above sea level from which it will flow in an “overtopping” mode ( presumably as if the bentonite wall will act as a dam of some sort).
No engineering studies are offered in support of this idea.

This is obviously ludicrous as the bentonite cutoff wall on the upstream side of the North Spur as proposed would be a relatively slender structure, not seated in bedrock and designed only to prevent upstream seepage.

The bentonite cutoff wall cannot possibly withstand the enormous forces associated with a North Spur failure and consequent river release. It will be quickly swept away.

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I am informed by an experienced hydro engineer that the consequences of a North Spur failure,

“from a financial perspective would be unimaginably catastrophic”  due to the very large
expenditure required for a repair due to erosion of the Spur clay foundation down to below sea level. …”

He continued:

“The cost would be so high, that a more economical alternative would likely be to abandon the site and spend the repair moneys on a re-design and construction of the Gull Island Dam, taking advantage of the lower tailwater level resulting from a dam break in the North Spur to increase the capacity.”

In other words, your position (seeking to refute mine) that “the river cutting a new channel and by-passing Muskrat Falls is extremely unlikely” is simply not correct based on the advice of a very experienced hydro engineer very familiar with Lower Churchill Hydro projects.

Indeed that very senior hydro engineer informs me that in the event of a North Spur failure, the down cutting at the location of the North Spur (which will of course disappear) will continue to a depth of      -10m to -20m ie 10 to 20  meters below sea level.

That is 30 to 40 m below Nalcor’s “specified” limit.

As the Hatch Report itself repeatedly emphasises, the  “breach bottom elevation” is probably the most critical variable in its analysis governing what it thinks will happen if the North Spur fails --- governing everything from Width of Breach to Peak Wave to Warning Time ( and thus to Loss of Life downstream).

To impose a + 20.5 m deepest cut restriction on Hatch in such a critical matter is simply wrong and not in the public interest.

I am preparing, with the assistance of others, further comments on a number of points in your letter of reply but you can understand me when I say that getting clarity on the two points set out above is key to completing that analysis.

Which brings me to my closing point.

Your letter refers to the work of the Joint Review Panel as being somehow relevant to the problematic position we all now face. You should be aware that while the Joint Review Panel had the benefit of a Dam Break Study for the concrete dams at Muskrat Falls it did not have a Dam Break Study for the North Spur which was only completed on June 26,2015.

So I take no comfort there either.


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Indeed I find it passing strange that a proper full Dam Break Study for a North Spur collapse case was not before the Joint Review Panel and has never been the subject of a public review process with all relevant geotechnical information being made public especially where it deals with Quick Clay and landslide potential.

I urge you immediately change that.

And as Minister responsible for Dam Safety, I respectfully suggest you engage the public via an open and transparent process on the North Spur stability/Dam Break issue -  something it has never had.

If we, as a society, demand documentation and public review to protect the environment, why not apply the same approach to Dam Safety, workplace safety, human life downstream and the multi-billion dollar loss of our investment in the Muskrat Falls generating facility currently under construction ?
Sincerely,

Cabot Martin
151 Waterfordbridge Road
St. John’s , NL
A1E 1C7

Cc Mr Jamie Chippett  Deputy Minister Department of Environment and Conservation

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3 comments:

  1. The report references 20.5 meters, which is about 15 meters above the downstream water level, and about 65 meters above the deep pool located just downstream of Spirit Mountain. So in the dam break analysis they have been told to consider failure of the top half only?

    The Minister should direct Nalcor to release the report which recommends the 20.5 m elevation.

    Why is not all of this information public?

    What is there to hide?

    Why does our Government always just parrot what Nalcor state...

    What must be remembered is that there is no other example in the world where a geological feature like the North Spur is being used as a Natural Dam. Are the classical geotechnical empirical models still applicable?

    ReplyDelete
  2. It is strange that Hatch did not include a sensitivity for a failure of the North Spur beyond the 20.5 meter cut off.

    The disclaimer from Hatch at the front of the document clearly states they have provided no comment on the suitability of the Client supplied data.

    What is the probability of failure of the North Spur?

    ReplyDelete
  3. The North Spur is like the sword of Damocles. While the probability of collapse in any particular year may be low, it will eventually let go with no warning. An earth tremor, failure of the pumping system designed to keep water levels in the spur low, desalination of the clay caused by pumping out water that gets replaced with fresh rain water changes the chemistry of the clay allowing it to liquify, a few years of unusually heavy rains, or just plain back luck. Why would anyone sane person accept such catastrophic risks when there are so many alternatives to Muskrat Falls in the first place?

    ReplyDelete