DH had the aforementioned pond surveyed today, and because of the slope of the property, will be creating two ponds and two dams.  I thought it might be fun to do this experiment on water pressure with the children and study up on dams.  Meanwhile, we can go back every evening and document the progress of the pond.  I think they are trying to finish by the weekend.  A photo album would be a nice gift for the owner, no?