I will say this, it's a really REALLY nice start, but it's very open which will scew how the game plays. Not a huge issue, all you need is some scatter to go on top (seperate pieces which you can change every game to give a bit of replayability), which is a cool project. You could make a pumping station, some selection of junk, Some Verticle pipes with smaller pipes running between them.
I would also suggest making some bridges to span the chasm as climbing down an back up again could slow down the game a lot