Thread: my engineer friend & I compare BC Hydro's vague photos of its construction of cofferdams with independent photos.(Cofferdams are secondary dams to divert the Peace River into tunnels & away from the work site so the #SiteC dam can be built) https://twitter.com/sitecproject/status/1287789437523460097 #bcpoli

What does this photo from @sitecproject's tweet actually show? Engineer: "Pretty obvious Hydro's photo is useless..that's not clearly related to a cofferdam. They should be embarrassed to show that." Is the only purpose of this photo to minimize the sheer size of the Peace River?

Here are 2 aerial photos of same area at #Site, taken by a local pilot friend: "Hydro's photo would've been taken from the centre right on the south bank about where that excavator is sitting. Start of cofferdam is the little finger in the river which the river is washing away. "

Note: the twin #SiteC river diversion tunnels are in an arc inside the North bank of the Peace River. You can see the upstream entrances to these tunnels in photos here, and in this previous thread. https://twitter.com/Lidsville/status/1285996554671669249

Now, some remarks and questions re: what we can see of these #SiteC cofferdams so far from these overhead shots, which are about the only way we can see what's being done at #SiteC. Props to this pilot! Because @BCHydro can't BS its way out of these photos.

Engineer: "That little "finger" in the aerial shot is made with large rocks, with a dozer pushing them into the river to start the cofferdam. The previous BC Hydro photo shows something entirely different...don't have a clue what it is, and can't see any large rocks." Compare:

..Engineer: "They can add to those rocks & try to make the cofferdam much wider and stronger. But I don't know what is inside - if there's anything to seal it - but that's the start of the upstream cofferdam. But no way they'll get anywhere with the river flowing like it is now."

"Why didn't the upstream coffer dam start further upstream, curved to smoothly turn the river toward tunnel entrances? That'd help w/ the momentum problem. Now it starts just downstream of the entrances creating a pocket, making it more likely the river'll overtop the cofferdam"

..Did this location of the upstream cofferdam result "from thinking the river flow would be close to zero, and this was more convenient or shorter, with no significant river flow to deal with"? But the river is in full flood now, due to unusually heavy rains.

For whatever reason, "Hydro didn't react to the changing river dynamics from all that unexpected rain. The Peace has a relatively steep gradient here which keeps the speed up, and it's a very large volume of water. They can't proceed as if this very high river isn't there."

The next musings from my engineer friend are quite long so I've screenshot them. He wants to emphasize he's just a concerned onlooker asking Qs, & has no information about BC Hydro's #SiteC design thinking is (and BC Hydro's ongoing opacity here is part of the problem). #bcpoli

Interestingly, another contact just messaged me in response to this thread. He is very experienced in construction & knows the Peace region. He's talking about contractors here, partly where ballooning costs come in when you're fighting a losing battle with nature. #SiteC #bcpoli

I could go on but I'll just end with this apt point from @billsqueegee on BC Hydro's and @sitecproject's vague communication-by-twitter vs. their TWO overdue quarterly #SiteC reports. If anyone has questions for me or my sources, just ask. https://twitter.com/billsqueegee/status/1287799268921622529 #bcpoli

One PS from engineer: As your construction friend says, the cofferdam must be solidly built. That means a large, wide-tracked crane that is assembled on shore and will work its way along the cofferdam...

.."Any soft spot, or one weakened by the water, will be a disaster... and driving piles is similar to a small earthquake from the shockwave of the heavy diesel-powered hammer hitting the pile and propelling itself upward." And we already know the shale at #SiteC is unstable.

This tweet got unhooked from the thread, so I'll add it in here. https://twitter.com/Lidsville/status/1288219130777096192

ICYMI: even back in 2017 BC Hydro knew it wouldn't make its Sept. 2019 river diversion deadline due to geotechnical problems, meaning extra billions. And that was BEFORE the extra $2bn @jjhorgan announced when he passed the dam! Now Hydro'll miss 2020 too. https://www.alaskahighwaynews.ca/site-c/site-c-river-diversion-delayed-bc-hydro-says-1.23057046

Hydro will no doubt blame missing the #SiteC river diversion this year on historic water levels. But that’s a trap for them, because it'll betray the fact that BC govt & BC Hydro made #SiteC plans without taking long-predicted, climate change-caused weather havoc into account.

So, @PRHydroPartners has blocked me on Twitter again... Don't those corporations work for us at #SiteC? #bcpoli

@bruceralston @jjhorgan @bchydro @sitecproject