Muskrat Falls and the North Spur controversy

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I am writing to express my concern about the safety of the hill forming the North Spur at Muskrat Falls, which will be reshaped into an “engineered dam” to contain the Muskrat Falls reservoir.

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The North Spur is both a curse and a blessing. It is a blessing because it creates a natural dam. It is a curse because it is not rock solid like the Southside Hills in St. John’s. It is moving and alive. It is underlain by quick clays that can liquefy when saturated or disturbed.

You may well be curious as to why I am interested in the project. For the past 63 years I have worked exclusively on 113 hydro projects, with my first field job in 1953 being the supervision of construction of dams and canals used to divert the headwaters of several rivers into the Cape Broyle River on the Avalon Peninsula.

Since then, I have worked on Churchill Falls, Gull Island and Cat Arm, concluding in 2001-2005 with annual reviews of dam safety of all the Churchill dams and those on the Island operated by Newfoundland and Labrador Hydro, with the Dyke Board. Hence my interest in Muskrat.

The North Spur is a natural hill 1,000 metres long connecting Spirit Mountain to the north shore at Muskrat Falls, which includes three layers of sand and two of marine clay, all resting on a foundation of marine clay. When the Muskrat reservoir is filled, this hill will form part of the dam containing the reservoir.

Marine clay is a type of clay found in coastal regions around the world. In the northern, deglaciated regions, it can sometimes be quick clay, which is notorious for being involved in landslides. Construction in marine clays thus presents a geotechnical engineering challenge.

Marine clay is present around the southern half of James Bay. This persuaded Hydro-Québec to by-pass development on the Nottaway River, moving instead 300 kilometres north to the La Grande, at considerable added expense for access and transmission.

Despite such challenges, Nalcor elected to build Muskrat Falls, where all the clay in the region around Muskrat consists of marine clay, and there are numerous quick clay slides on the north shore, both upstream and downstream of Muskrat, including three large slides on the downstream slope of the North Spur.

Dr. Stig Bernander has examined the Spur. He has extensive experience analysing quick clay landslides in Sweden, and has determined that when the water level in the North Spur is five metres below ground level, the natural dam has a safety factor of 1.43. However, when saturated, the safety factor drops to 1.09. This is what would be expected in view of the numerous quick clay landslides in the vicinity.

Nalcor intends to increase these factors by flattening the slopes, adding pump wells, placing an upstream impervious blanket to close off the upper sand layers, and building a cutoff wall filled with an impervious material to close off the lower sand layer. All reasonable measures. However, Bernander has questioned the use of a cutoff wall indicating that it may be detrimental to the safety factor.

If the North Spur dam fails, there is the likelihood of loss of life in Goose Bay and Happy Valley, and the river will divert to flow through the breach in the Spur.

If the North Spur fails, Muskrat Falls will disappear and be left high and dry. The Muskrat Hydro facility would become a stranded asset, with (if feasible) a repair cost well over several billion dollars. Power would be interrupted for at least several years.

Since the design of the North Spur dam is without precedent, and the consequences of a failure are catastrophic, it becomes imperative to have the design reviewed by an independent panel of experts — a review board, and I am glad to hear that Premier Dwight Ball and Natural Resources Minister Siobhan Coady have announced a review of the cost and schedule.

I sincerely hope that the review will be expanded to include the geotechnical design of the North Spur dam, since any remedial measures will impact the cost.

Jim Gordon, hydropower consultant

Pointe Claire, Que.

Organizations: Churchill, Newfoundland and Labrador Hydro, Dyke Board Hydro-Québec

Geographic location: Muskrat, Muskrat.The North Spur, Cape Broyle River Gull Island Cat Arm Spirit Mountain James Bay Nottaway River La Grande Sweden Goose Bay Happy Valley Claire, Que

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Recent comments

  • Sylvia J. Wilson
    July 08, 2016 - 23:24

    And after the fact they'll do a "study" and get recommendations and make sure "it never happens again". Too late then.

  • Unknown
    January 03, 2016 - 17:01

    When do they expect this to happen? Scary, if we're living in H.V.-G.B.

    January 03, 2016 - 10:23

    To Mr. Jim Gordon- If your info. & qualifications are correct, why were they not took into consideration when the prospect/design of this project was in its beginning? As a lot of kongable have sanctioned this project, why did you wait this long to put your 2 cents forward? Or are you being paid to help sabatash a project for Que. benefit ? Please respond-

    • Just Sayin
      January 04, 2016 - 15:59

      Mr Whalen, engineers in the 1960s knew this site had this sort of problem. Question is : Is the current design adequate to prevent, with a high degree of safety, a collapse and failure of this part of the natural dam? The onus is on Nalcor to assure the design is adequate, not an absolute guarantee, but to reasonable safety standards. Some very knowledgeable engineers has considerable doubts.

  • Jackie Adey
    January 02, 2016 - 21:03

    It's time our government really look into this before it goes any further!!

  • Wallace
    January 02, 2016 - 15:14

    Unfortunately, Dwight Ball is excluding the North Spur from review. The review is not one that will encompass safety as related to the north spur. The review is essentially to determine how much MORE money will be needed to finish the project and the timeline to which it can be done. These or this review is to determine how much more money we need to borrow as we will have to go the markets for this cash and a review may help us get a better rate of return.

  • Winston Adams
    January 02, 2016 - 11:13

    I welcome Jim Gordon going public in this way. I lack the experience of Mr Gordon, but I worked at Churchill Falls as an engineer in training, under experienced engineers building dams. After graduation as electrical engineer, I worked with Nfld Hydro in High voltage substation design and protection systems. I also have some mechanical experience as to how small disturbances by resonance at natural frequencies can make systems unstable. I am of the opinion that this quick clay issue is a very serious one, and should be reviewed by a panel of experts as proposed by Mr. Gordon

  • EDfromRED
    January 02, 2016 - 10:18

    Can you imagine the uproar if this dam threatened to just flood the basements of St. Johns residents? But no, those downriver from it in Labrador have their lives to lose. It seems to me that the NL Government and Media, hold native lives in contempt. Maybe they are looking forward to filming and photographing floating Native bodies so they can get commissions for National media Disaster coverage??

    • Angela
      January 02, 2016 - 19:23

      EDfromRED: I live in St. John's and I am very concerned for those who live downriver from this Dam IN LABRADOR. The frightening Muskrat Falls Project is quite the worry for all Newfoundlanders and Labradorians!

  • Maurice E. Adams
    January 02, 2016 - 07:51

    And even if the North Spur does not fail, with Nalcor's North Spur cut-off wall designed to prevent seepage from the area between the north bank reservoir and the Kettle Lakes area into the North Spur and thereby potentially increasing water saturation northwest of the North Spur cut-off wall, combined with the fact that the increased reservoir depth EXPONENTIALLY increases water seepage from the reservoir into the area just northwest of the North Spur cut-off wall, and given the presence of clay layers in this area northwest of and just outside the North Spur itself (combined with what appears to be downstream riverbed erosion flowing away from the Kettle Lakes gorge), then what studies, what evidence is there, that once the reservoir is filled the river will not then by-pass the North Spur and breach the north bank/Kettle Lakes area, with the results being essentially the same as a breach of the North Spur itself (see graphics at ), 13 September 2014 entry.

    • Maurice E. Adams
      January 04, 2016 - 08:29

      The above should have read ------------"...EXPONENTIALLY increases water 'pressure' from the reservoir...". Also, note that Natural Resources Canada previously stated that "Potential occurrence of large-scale earth flow not adequately considered in the assessment of bank stability..."