Not sure, 70-80 roots maybe. I wouldn't call this a drainage, it's really a steep ravine between two small mountains. There are various drainages going into the ravine. I've gotten them in the ravine, on top of the ravine and in the drainages. Regardless I haven't touched this thing. It's big, steep and hard to get around for an old man!
Sooner or later I'll hit a hot spot in there. We don't seem to have very big patches here in Vt. Then again I don't dig em unless they are at least 15yo. I se areas with 50-70 3 stem plants, but I don't dig more than 15 that are older roots. I have planted a lot of seed in the areas that are easy to get to and seem to be producing big root. I planted about 2-250 seeds today.