When the excavation is finished, set up batter boards to locate the building lines and place the footing forms. See figure 3. The batter boards are leveled and placed at the same height with the aid of the transit, and set 1219 mm to1829 mm (4 to 6 feet) back of the excavation site. A plumb bob can be used to position batter board's string lines precisely over the nails in the corner stakes. If the two diagonal corners of the string line are equal, then the the building lines are square. The corner stakes are usually removed during excavation. Grade stakes can be placed at this time. 

A transit can also be used to locate the excavation building lines and place footing forms, as long as it can be placed over a reference point that is outside of  but close to the excavation. See figure 2 on page 2 "Setting Up Batter Boards".