Tom, Mike, and Tom,
We had a regional event here this winter - a lot of rainfall, at the very end of December, that froze before it had a chance to completely sheet drain off of some greens. The underlying soils were frozen solid, so there was no vertical evacuation of surface water to any types of drains unless they were open air risers that were not covered by leaves.
Bentgrass was not injured by this situation - only Poa annua was effected, and in varying degrees.
I spent the day today visiting courses that are maintained by veteren superintendents who have experienced this before on older golf courses that have, shall we say, quirky greens.
I saw several greens that actually have surface risers built in to them, and they worked. I would love to post pictures up here showing how cool this was, but I didn't think of asking permission.
Anyways, you gotta love the ingenuity of these superintendents.
One thing I did notice is a lot of caving in around the holes. But they assured me that this only happens on years when a lot of water flows through these surface risers. In the next few days they will be digging up around these holes, capping the drains for summer, replacing the eroded mix, and plugging the hole. You won't even know that there was a drain there all winter.
So Mr. Paul: I said that I would not expect one of these drains to drain a punch bowl greater than 1,000 sq ft.. Well today I saw one that was at least 2,500 sq.ft. So I was close.
Kinda.
Maybe there is one out there that is more than 2,500 sq.ft.? But even still, what you are proposing is something that you don't get to experiment with before hand. Boy that's a risk I would not take - unless maybe if it was on a deep sand vein.
The other thing is Myopia might be the best below grade bunkering in the world. To place a below grade green in there would be odd I think. Maybe not, but I'm having a hard time visualizing that.