I've spent the last week working on this set. Seems time consuming, but if you want it to look cool then you have to put in enough details until you are happy with the result. Plus, this set has to be used for multiple angles and shots, and so has to be a full 360° set. Which means enough detail from enough angles that I might want to use and no black space. For some shots you can get away with just building the straight 'on camera' set, not in this case. But I'm finally happy with the level of detail and I can add small changes in production if I need to.
I used a couple tricks in this to make life easier. Notice how the ground fades into the horizon color as objects become more distant. This gives depth to the image, plus I don't have to model a whole bunch of stuff in the distance because it wouldn't be visible anyway.
All the textures are created with procedural fractal noise, with multiple layers to add large scale and small scale variations to the texture. This is set to 'world space' coordinates, so that I don't have to worry about two objects having the same texture when I clone and move them, plus objects textured in this way will automatically blend in together when you put them side by side (such as in the case of two ground planes, for example)
A lot of the distant objects are simply modeled as silhouettes: the cranes, the hydro towers, even the chainlink fences. With the distance fade effect applied, these blend into the background but don't need to have as much surface detail themselves. The sketch effect I use also helps to add more detail to these objects, so there's a certain amount of detail that they need, but beyond that it's unnecessary.