I've done a few benchmarks in VA, and have not seen this style of reference to a witness mark. I would guess it means from the pole, you will find the mark 29 feet away at a bearing of 15° N of E. In other words it is 75° on a 360° compass (E is 90° so 15° back towards N would be 90°-15°=75°)
I may be way off, but that would be my guess.
If you haven't done so, you might post in the BenchMark section of the forums. Those folks are very helpful.
Good luck.
TeacherMatt