The first design project that I’ve gotten to be involved in from the start at my work is a tiny 25 MW power plant in Greenville, TX. These little natural-gas powered reciprocating are meant to be turned on and off depending on the need, and are mostly there to keep blackouts from happening during the hot summer months (think Air Conditioning in Texas in August!)
These little engines (I say little, but each out weighs around 1/3 million pounds) are great, and I’m really glad there’s a whole lot of power companies out there that want them… I’ve got a job because of it!
I’ve gotten to be involved with this project in Texas from the start and learned about a particularly unique problem that this plant had. It turns out that there’s a small strip of land running North to South in Texas with a special kind of clay soil. Apparently when this clay gets wet it swells up like a sponge and has been causing problems to foundations all up and down this strip. Who knew that a little wet clay could literally crack concrete and raise entire buildings?! And of course, our site lays right in the middle of that area.
The way that we solved it was to drive piles deep down into the ground underneath the foundations. The piles are basically tubes of concrete 1 1/2 ft in diameter with steel reinforcing that extend 30 to 40 feet into the ground, past this troublesome layer of clay. The building foundations then sit on these piles, with a gap in between the foundation and the soil, so that when the soil does get wet and expand, it won’t push against the bottom of the foundation. Think of a building on stilts.
I was put in charge of designing both the piles and the foundation slabs for this project, and I just got some pictures of the crews laying the concrete itself. I quickly realized that one of the scarier things in the world is to see something that you designed getting built. I had some nightmares, naturally, of President Obama visiting the project site and having the foundation collapse then me being taken to an underground bunker and getting interrogated by the CIA, then the KGB, then Al Qaeda. I think there was a talking Kangaroo and one of the Transformers in there too… it was a weird nightmare.
Here are some pictures:
An overhead shot of the building foundation and concrete formwork being put in. The large slab in the middle is a separate piece of reinforced concrete that the engine itself sits on. That mat is close to 3 ft thick!
There’s only 6 inches of those piles showing here, but they extend into the ground almost 40 feet. The concrete slab will be poured right over the tops of the piles after the rebar has been bent down. Interesting to note that after the project is finished, no one will ever even see or know that those piles are there!
You can see the finished slab on the right next to the man to give you a sense of scale as to how thick the foundation is!
The bottom layer of reinforcing steel is laid down. A top layer will be put in close to the top of the concrete, and the concrete will be poured in around it.
Another thing that was neat for me to realize is how well I recognized everything in the picture. I worked with this design for a very long time and became intricately involved with all the small details of the site. I knew the design so well and had pictured it so many times in my head that I instantly recognized what I was looking at… because again I had seen it so many times in my mind. When I first started working as an engineer, I thought it was odd when I heard more veteran structural engineers talk about their work and about their designs. I paid particular attention to the verbs they used when conversing with other people. “I built a structure over here to blah blah blah”. Or, “Hey Kevin, I need you to put in a ladder over here to to the access platform.” or “what grade steel are you going to use to build this pipe support?”
Well of course, we engineers don’t actually build these structures, we don’t go out with a hammer and a wrench and physically erect the steel and pour the concrete! But these guys are so good at what they do, they literally see every aspect and tiny detail in their mind long before it physically gets built. I had an epiphany when I saw this foundation being built: seeing pictures of the physical concrete didn’t give me a better understanding of the structure, because I already knew where every edge, every pile, every piece of steel, and every construction joint was going to be. I had drawn up the structure in my mind so many times while we designed it that I wasn’t surprised at all when I saw my design actually built. I understand a little better why these elder engineers use the verbs they do: in their mind they really are building these structures.
I went from that mode of thinking straight into thinking about the earth and its creation, how it was spiritually created long before it was physically created. And I thought that the spiritual creation would have been worthless without the physical creation, and vice-versa. I think the creation of the earth is one of the more significant miracles of Christ… but that’s another long discussion, and Naomi complains that my posts are too long as it is…
Besides, I need to get some sleep so I can wake up, go to work tomorrow, and build some more steel structures in my mind!