Imported DWG site survey.out of level

I have imported a site survey into a new SKP doc and found that the imported component is not level, It appears to be sloping downward to the north at a small degree, say, 2 to 4 degrees, Before I moved the DWG image upward on the blue axis, it was cutting through the street plan loaded via Add Location. I will be contacting the surveyor but this raised the question, “Is there a way to determine definitively whether imports are level—the street map and the DWG image?”

I have to revise my question here, The site survey was level, while the street map was at an angle. At the moment I don’t know what’s what. I’m now wanting to know what is the preferred sequence for adding site survey, adding location and starting (or importing) the model. Is this covered on learn.sketchup or square one?