[javadog]

Your first task is to fire the contractor. If that's how he forms and pours concrete, he's too stupid, lazy or cheap to do anything correctly.

The first point I'm going to make is that before you start construction on the site, you need to get all of the site grading done. There are too many bad contractors that build first, then grade the site later.

Next, I don't have access to your soil testing report, if you have one, so I can't comment on what soil conditions you have there or what the structure looks like, any of the loads, etc. So this is just going to be generic advice.

The first thing you want to do is strip the topsoil to remove all organic matter down to inorganic materials that could be used as a base. Depending on the type of soil that you have on that site, you may wish to go deeper and replace soils that are not suitable with those that can be compacted. Whether the replacement is aggregate, sand or something else is up to you. This is then compacted thoroughly and forms are built on top of that. The form tops need to be at whatever elevation is appropriate for the design, the bottoms need to be sitting on the prepared subbase and ideally are a few inches lower than the finish grade needs to be when you're done. The base of the poured concrete needs to be level, the top can either be level or have a slight slope to allow for water drainage. After the concrete is poured, cured and the forms are stripped, then you can regrade the area around it to bring the finish grade back to the correct elevation.

If you have soil that is prone to movement from either varying moisture content or frost, then you want to extend the slab deeper, perhaps as deep as below the frost line in that area.

I don't particularly like that column I see in the background, I bet if I were to look at that site in person I'd find quite a number of things that are not done correctly.