Grading a lot is sort of like opening a gift from Forrest Gump - you never know what you're going to get. In our case, after a little scraping, it became fairly obvious that some kind of dwelling once stood here, because all kinds of strange things popped up. This lot has been vacant for decades, but we'd heard it was once a record store way back when. I have no idea how you can actually check on that. At a quick glance, we could see a decomposed mattress and dozens of wood boards, splintered and burned. The GC called out the engineer to come check it out, because you don't want to pour the foundation for a three story home on questionable soil. Decaying building contents qualifies under the category of questionable.
So Day 3 rolls around and the GC gives Andrew a call to let him know that there is going to be more moving of dirt than they thought, and about the foundation engineer coming to check it out. He knows we'll be snooping around at some point during the day - our offices are about 1.5 minutes from the construction site, so surprise visits are inevitable.
Before the Grand Dig, the plan was that a large amount of dirt was going to have to be hauled away. Turns out, we have the opposite problem. We're having to remove all the charred debris and replace it with soil which has stability. Andrew runs by during lunch, and there is a 6-8 foot deep hole in the ground where our house should be. I'm keeping my fingers crossed that they don't find any decaying body parts, because I'm not sure how we would handle that. Can a house be haunted by ground ghosts? Whatever building was once there was obviously burned down. Now the contractor is attempting to separate the "good soil" from the rotting debris in an attempt to limit the amount of soil which needs to be brought in from elsewhere.
The one good thing is that this is not an extra cost to us. Before we finalized the plans, the Builder brought in a geotechnical company to do soil borings and test the soils' stability. It is therefore the Builder's responsibility to plan (i.e. pad their estimate) for such possibility as much as is reasonably possible.