Georgetown Kentucky Wastewater Treatment Plant Structural Design Error

[bimr]

Some “$5 to $6 million of concrete” has been poured at the site, but apparently there are concerns an engineering miscalculation may have resulted in the plant’s foundation thickness not strong enough to hold under certain conditions.

GRW Engineering of Lexington, the company that provided engineering specs for the plant, has retained another Lexington engineering firm to do an inspection, but city and GMWSS officials want a company with more experience on sewage plants and is more independent than the company retained by GRW. Officials have said the engineering firm hired by GRW indicates additional concrete can be poured on top of the existing slab, but GMWSS officials are skeptical and fear the existing concrete may need to be removed and the foundation restarted in order for the building to remain structurally sound.

Link

 

[FacEngrPE]

This will be a financial disaster for someone. The stop work order at this stage is actually a good thing, as the farther into a job like this the harder it is to fix. Now the bill is only say 6 million.

If the foundation weakness was not found out until the plant was in service, a foundation failure would result in an inability to treat sewage for long enough that it would be huge trouble.

 

[spsalso]

It appears the city has hired their own expert, whose loyalty will be to them (the check-writers). An excellent move.


spsalso


Always remember: "The required construction is neither complex nor unusual." Ronald O. Hamburger

 

[JedClampett]

I would expect a mistake like this from a company that doesn't normally do water containing structures, but from GRW's website this seems to be in their wheelhouse.
From someone who reviews these designs regularly, the walls should be at least the same thickness in inches as the number of feet of water they retain. And the foundation should be at least two inches thicker than the walls.
It might be a case of reducing the foundation thickness away from the walls too soon.
This is a regular nightmare for us in the biz.

 

[bones206]

This link has some video of the site:

https://www.wkyt.com/2021/10/26/pot...-halts-work-georgetowns-new-wastewater-plant/

Honestly, the proportions do not look grossly undersized from where I'm sitting. Seems like a fixable issue even if they are a bit under capacity.

 

[Alistair_Heaton]

I think the mayor in the interview instead of saying "environmental catastrophe" should have said "shit everywhere".

Would have delivered the message to the voter in a more concise manner for the stoppage of work.

What concrete do you use for these farms? C20 or C30 or is it some special mix.

 

[bones206]

Here's a table from ACI 350-06, "Code Requirements for Environmental Engineering Concrete Structures". I've generally used 4,500 psi as a minimum.

 

[Alistair_Heaton]

That's roughly C30 under the metric system. Nothing that special

 

[ldeem]

I wonder what made them question the design after starting work?

 

[spsalso]

What a great question!

Since the "questioning" happened after part of the structure was already up, I do wonder if "some guy" asked why the walls were so thin. And "another guy" thought that needed an answer.


spsalso

 

[dik]

I'd have used w/c of 0.4 for all those conditions.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Alistair_Heaton]

I suspect it maybe one of the concrete lorry drivers commenting that other jobs they have have been on the sections were much thicker.