Friday, August 23, 2013

Are Colliery Dams As Dangerous As Claimed?

Assessment Made On Incomplete Knowledge?

Watching this Colliery Dam Drama for about ten months now has really been an eye opener as to how public safety concerns can be the catalyst for some questionable conclusions.

For example for months we have been told these two dams, impounding these two little ponds are the most dangerous in the province. Really? That sounds pretty serious, and really should be dealt with.

Until you start looking into how this conclusion was arrived at. To begin with, the middle dam was assessed for structural integrity on the assumption it was made of poor quality concrete and did not contain any rebar, in addtion to not being on bedrock. With those assumptions in place, an engineering firm stuck that data into their 'Dam Safety Modeling Super Computer Model DSM 10,000' and bingo, we are told these dams present a high risk as they 'could' fail with a 1 in 475 year chance! Now, I admit I am no rocket scientist but something which has 1 chance of occuring in 475 years doesn't really sound all that scary to me.

Something I have found most curious though, is that during the course of testing the structural integrity of the dams in order to let contractors know what they were dealing with in the demolition of these dams, it was found the dam had good quality concrete, contained rebar and it was set upon bedrock.

So, if the dams were given a 1:475 year chance of failing with faulty information about their construction, what would the new number be based on accurate information about their construction?

I repeat, I am not rocket scientist, but surely good concrete containing rebar set on bedrock has got to be stronger than crumbling old concrete without any rebar built on loose fill?


1 comment:

  1. Oh... and the Province also reports these are the SMALLEST dams in BC!

    I agree, Chicken Little screaming ' the sky is falling' is something from my childhood.

    -Tim McGrath


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