Minnesota,
Have you dug a test hole yet? If so, how far down until you hit the water table. If not, I recommend you dig one. Its free (minus a little sweat)and you will learn alot about the location of the water. Then you will be able to calculate how much dirt you will need to remove. If you are in a wetland you shouldn't have to dig much past 3' even as dry as it is. Its in ideal time for the test hole seeing as we are very very dry.
