So at 12:23 PM local time, which is solar noon here, I had a 6' 2x4 positioned precisely east/west vertical at the precise middle of the south edge of the pad and its center aligned with a nail in the wood concrete form. Being solar noon and the 2x4 east/west vertical, the long shadow it cast was precisely north, south and I marked the top middle of the shadow with an 8P nail. Removing the long 2x4, I wrapped a string around the nail in the south form board and ran it out from there, over the 8P nail and to the north wood concrete form board where I put another nail. I then got out my Grandpa's old chalk string dispenser (he was a builder and carpenter), put the hook over the south nail, reeled out the string, wrapped it tightly around the north nail and then proceed to snap a precise N/S chalk line. Finally, I snapped diagonal lines from corner to corner. The intersections of the lines were within a half inch of each other. Taking some measurements and assuming the N/S line is accurate, I determined the pad itself to be quite square and no more than .3 degrees off of due N/S. Not bad!! Holding the old reel chalk line dispenser in my hand (which has to be about 100 years old) I also took a moment to say hello to my Grandpa. I felt a little choked up actually.
Next I wrestled the 150 pound pier onto the pad, marked the centers of the bottom flange edges, walked it over to the chalk lines, lined everything up and drew lines around the bottom flange and inside the bolt holes.
Next I'll remove the pier.