Find lowest surface point for template fill at given slope

I would like to find the lowest point on a surface for a template end condition.  The fill end condition, as best as I can determine, will stop at point 1 (see image). I want to hit the lowest point along the fill slope, point 3 (see image).  I had a criteria that could do this in the the old Geopak, but I can't figure out how to do this in ORD.  This is done to cut through the irregularities in the existing ground and restore the foreslope to the desired condition.  Any suggestions?