We have to place some 12" wide x 54" deep reinforced grade beams. The final grade around the building will be about 8-12" below the top of footing elevation. It's clay predominantly but there could be some sandy patches. I'd like to avoid having to form the sidewalls and plan to earth form them. My only concern would be the foundation wall tops which need to be smooth on the sides and top. Has anyone done something similar with success? How did you kick back and form the top of the wall without caving in the top of the trench?