How the Structural Design and Systems were Determined by the Soils in the Area

So the structural design and systems that were selected for this project really comes down to the soils that we're up against in North Dakota. As mentioned this project is inside of the Red River Valley, which used to be part of the Lake Agassiz basin. And you can see right around here is where the project is located. We're essentially in what was the bottom of a extremely deep lake before and it left a bunch of sediment. Hundreds and hundreds of feet of sediment on pretty much the entire valley. So when we go to do a structural design system that tends to be something we're up against in this part of the country.

And because of the massive weight of a water treatment plant, all the cast in place concrete, as well as the weight of the water inside there. We were really up against a challenge on how to get that supported on the soils. Typically in this part of the country it comes down to a few solutions that we would use. Is a spread footing, where there's a big matte slab that goes out so there's enough lateral pressure being put down on the soils that it can support the building. The other option we looked at were geo piles, is basically where they take a big auger and drill really far down into that soil and then they compact gravel inside of it.

It essentially makes a big stone pier. And then the other option, which was utilized for this project, is a driven pile where they take a wide flange piece of steel and they hammer it into the ground. And the risk with that one, and what we actually ran into, is that sometimes the soil is so soft that when they go in and they do that it's essentially like throwing a pen into a cup of water at a restaurant and the pen will veer off, or the pile will veer off in the soil, because it went in too fast.

But given how many piles and the scale of the project it was the most economical solution. So there's miles worth of steel piles driven into the ground and that really composes what the whole structural foundation system is made out of. From there on up we're looking at slab on grade construction in the basement with your kinda typical concrete foundation walls. And those once they get above grade actually serve to be the tank walls as well. And then to skin the building we ended up using structural precast wall panels as well as structural precast Ts.

And the advantage to that is, given the nature of a water treatment plant, and the clear spans that are required without dropping columns down inside of the basins, that material really lent itself well to achieving that structurally. As well as gave us some design freedom to express an architectural idea on the outside of the building. We were able to play with the pattern and colors and really give life to a water treatment plant, which is not typically a project that would get a lot of architectural treatment along the way.

The other thing to note is that the administrative portion, which is what is shown right here, is framed with just traditional steel framing. And the reason we wanted to do that was to give the operators who work at this plant full time, they're there day and night, give them the opportunity to bring in a lot of natural light. And we house their lavatories and we house their break room, and there's an exercise room in there. And it really becomes a nice break from the rest of the plant which is primarily enclosed and steel framing allowed us to achieve that.

Log in to access files