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DAY 67 - APRIL 27, 2010

April-27-10

OMB Rockfort Hearing for April 27th, 2010

Alex Naudts (grout curtain specialist for the CCC) continued:

  • Slides 46 and 47: Is cost estimating part of the work you do?
    --Yes
  • Is it more expensive to grout under flow than non flow?
    -–Yes
  • Do you, in designing a grout curtain take into consideration environmental conditions?
    -- Yes we always do. Location plays a big role.
  • The proposal is to commence mining in the dry. What in your opinion are the consequences of putting the grout curtain in after mining has started?

    --Some of the grout will enter into the excavation, it will be more difficult, and there will be a number of other issues with some of the fancier grouts.
  • Refer now to McCook-the lessons learned report.  Did you compare the program at McCook with the program at Rockfort?
    --Yes I compared the data in each.
  • Are the two projects comparable?
    --There are important differences. The affected permeability was 11 Lugeons. They started where Rockfort wants to end up.  They were able to use a reasonable cement grout. Length of curtain was different. Amount of grout used was 23 times less than that used at Rockfort.
  • If the grout curtain at Rockfort is completed in non-flow conditions, how long will it take to do the curtain?
    --It will depend on number of rigs. About 30 years to install the grout curtain.
  • What is your opinion as to the likely response time to failures?
    --In my experience, you have to first determine where the blowout is, there could be much drilling involved. Must resort to bitumen and that would be roofing bitumen- could take up to 3 to 4 months.
  • What in your opinion will be going on during that time?
    --Water will be coming in, the water table will go down, one could let the quarry flood and allow an equilibrium and then use cement grouting.
  • Have you had any experience with the impact of blasting on the grout curtain? What has your experience been?
    --On the Rideau Canal there was blasting to remove some debris.  The effect of the blast was devastating – fissures were created very far away. The permeability was higher than it was originally.
  • Have you had experience with any ground water recharge systems?
    --I could not design a system but I could give you my opinion based on experience.
  • The question of the cost of installing the grout curtain – Slide 37:
    • Scenario 1: Installation of grout curtain before any mining starts – $45 million for construction of a grout curtain with a 10 Lugeon value.  Got bids from 3 companies and they were all within the 42 million to 56 million dollar range.
      Interventions: approximately 2 million dollars per each time.
    • Scenario 2: Under flow conditions- approximately 134 million, cost to maintain and repair the grout curtain -25 million dollars but over the life of the mine it could be as high as 2 billion dollars.
    • Scenario 3: Install a grout curtain of 1 Lugeon or less before mining – cost would be about 90 million dollars and for maintenance of grout curtain during mining would be 22 million dollars. Scenario 3 is the best case from a risk aspect.
  • Exhibit 107: Starting on page 2- you have expressed 9 opinions- do these continue to represent your opinions?
    --Yes they do.
  • Page 10:
    --I agree that as a general concept that a properly installed grout curtain installed under non-flow conditions can be effective in lowering the water table under 3 conditions. I still agree.

  • Page 12: Is scenario 3 more like a barrier than a curtain?
    --They are very much the same.
  • In that regard is it more like McCook?
    --Yes.
  • Page 16: Illustrates what grouting under flow conditions involves.
    --There is a velocity of the water at which the cement can not remain in tact.
  • Page 23: Discussion of the effect of blasting on grout curtains: Are these your words?
    -–Yes.
  • Page 25: Does this section contain your analysis of the grout testing?
    --No it is just a description of the grouting.
  • Page 27:
    -- I am not aware of any successful reinjection /recharge in a quarry.
  • Page 5, Opinion #9:
    --Rezoning ought not to be given and a license not issued until after there is proof of concept.

Cross examination:

  • You have been successful in grouting under flow conditions?
    --Yes.
  • Grouting under flow conditions is technically feasible?
    --Yes.
  • Your concerns are environmental, financial and duration?
    --Yes.
  • Environmental considerations are always present?
    --Yes …I have sometimes polluted.
  • AMP from 2009 is not listed – did you review it?
    --The lists indicate what I reviewed.
  • You never met with Dr. Bruce and CRA?
    --No I never met with them.
  • All grouting is going under flow conditions… I am going to suggest that this is wrong.
    There is no such thing as mining under flow? Let us not split hairs---- There is very minor flow.
  • Phase 1 creates no significant flow?
    --Yes
  • Are you saying the test conditions are inadequate?
    --Yes
  • Are you aware that Dr. Bruce disagrees?
    --He is allowed his opinion….Prove the model on a scale model.
  • Are you aware of the requirements in this province for installing recharge systems?
    --No sir.
  • Slide 34-What’s missing?
    -- Environmental testing.
  • If the grout washes out will the PH of the water not go up and will the environmental testing not acknowledge it?
    --Yes.
  • If the grout curtain starts to erode the recharge wells will pick this up?
    --Yes sir.
  • Any wash out during construction will be temporary?
    --Yes.
  • You talk about being concerned about bacteria?
    --Yes.
  • You raise the specter of Walkerton?
    --Yes.
  • Is this not alarmist?
    --No.
  • Wash out of the grout will go against the flow and reach the wells?
    --Yes.
  • Are you aware that treatment is recommended by Halton Hills for wells in the area?
    --No I am not.
  • Did you hear the evidence of why the 10 Lugeon curtain was selected?
    --No I did not.
  • Dr. Bruce talked about the same steps as you have in your slides 1-4?
    --Yes.
  • Slide 7: Dr. Bruce is proposing using balanced grouting?
    --Yes.
  • Slide 9: I am suggesting that your statistical analysis is worthless! The statistical analysis is based on only 2 projects.  Your numbers are highly biased!
    --No sir these projects were very similar to Rockfort.
  • The failures you looked at in slide 9-were they both damns?
    --Yes.
  • Was there a different type of rock?
    -- It was not limestone.
  • Slide 14: Various grouts to choose from?
    --Yes.
  • Concrete is used all the time?
    --Yes.
  • Looking at slide 20: do you have a reference for the Gibson equation?
    --I believe so, somewhere in my report. He lived a long time ago in France. On slide 20 I'm comparing two situations where it is dangerous to use average permeability.
  • You say a conduit flow could be 3-9,000,000 cubic meters/minute?
    -- Yes in an unlimited aquifer.
  • That's a lot of water – that means the quarry could fill up in 3 days?
    --Yes, I've seen it happen in mines.
  • How much water flows in the credit river?
    --Naudts does a quick calculation – about 7.3 cubic meters per second.
  • You're not far off, but do you think that's a realistic inflow?
    --Yes, I've seen it happen at Cominco.
  • Do you know how much groundwater is flowing on site?
    --No, not off-hand.
  • On slide 36 you refer to a statistical analysis--was that the same analysis as on Lower baker and Stewartville?
    --Yes.
  • Looking at slide 40--when did you get these quotes of the grout curtain?
    --Jan-Feb of last year.
  • None of these were done on a contract basis?
    --No it is common to do it on a unit-by-unit basis. I took the numbers from the grout demonstration.
  • I put to you that Dr Bruce's design was very different from the test?
    --Yes.
  • You are aware that Dr Bruce worked on the McCook project?
    --Yes.
  • Did you talk to him about it?
    --No, and I believe he was a subcontractor.
  • You agree that the cost to grout Mc Cook was 120$ per meter?
    --yes, on a unit rate basis (note: sort of like an hourly rate metaphor)?
  • Phase 2 was 128$ per meter?
    --Yes, but again on a unit rate basis
  • You are assuming a unit rate--not a lump sum?
    --It's my experience, that's usually what the Army Corps of Engineers does.

Re-direct questions by Mr. Webb (for CCC) of Mr. Naudts:

  • You were asked about the monitoring that is to occur--are you aware of any report done assessing the risk of the erosion of the grout curtain?
    --I am not aware of any.
  • If there was erosion would it all go into the quarry or could some of it escape?
    --Yes, some grout can escape as in Hollandsas it happened.
  • Are you aware of any reports from the appellant having to do with statistical failures?
    --No sir.
  • I there is a breach of the curtain, will it take all of the water that is available?
    --It will start drawing further and further because the breach is the lowest hydraulic gradient point and over time it drains to that low point.

Testimony begins tomorrow (Wed) with Warren Sorenson, Planner for the CCC.