Gentlemen:
I would really like to know how a pushup green which is fitted with a drainage system compares to one without drainage and compares to a USGA green? My course has pushup greens which were retrofitted with a drainage system - is this really worthwhile? It is my understanding that changing the contours of the green could be difficult because of the drainage system - is that correct?
Cheers, Jerry
Jerry,
Sorry it took me awhile to get back to this question you asked me answer. I took the lady up to Santa Barbera wine country for the weekend and she made me swear I wouldnt spend any time on GCA talking about sand and dirt
The difference between a soil pushup with and without a drainage system compared to a USGA spec or modified green....
The biggest difference is in the gravel layer and its function in the green.
With a soil push-up the super is at the mercy of how well the green drains based on the existing soil characteristics. Always praying that water will shed off the surface drainage contours and that infiltrating water will perk at a decent rate.
A soil push-up with internal drainage is even better. The internal drainage pipes create lines of differing pressures where water is always naturally working towards because water will always follow the path of least resistance. The water works itself into the drainage lines instantly escaping the greens profile and becoming irrelevant to the greens health.
Weve already killed the USGA beast on this thread enough, we all know how that works and why its good by now. But there is the difference between the USGA and a push-up with drains...
The gravel layer. The gravel layer is not there just to separate the sand from the drain lines. It acts as a pressure equalizer across the green creating a consistent water perk rate across the green profile. All of the larger macropres between the gravel bits creates a substantial difference in hydraulic pressure in the profile pulling any tertiary water in the profile down into the pipes where it becomes irrelevant to the greens health. Consistently across the green.
Where this differs with a push-up is that the push-up doesnt have this equalizer underneath to draw water down. The perk rate of the water is just dependent on the existing soil characteristics. It could perk fast, it could perk slow. It will probably perk at different rates across the greens profile. But the drainlines do improve this. Not as well as a USGA, but it is an improvement than having nothing at all.
There is a retrofitting method used on soil push-up greens that hasnt been mentioned on here yet and Im kicking myself in the ass for not bringing it up. Its such a genius way of keeping the original push-up green while optimizing drainage both on the surface and internally. I really think this method is a stroke of genius and its one of those things like the post-it note that you wish you came up with. I think so highly of this that I will start another thread on it.
Its called "XGD" external greens drainage. Ill start another thread with its link. I think youll be surprised by its portfolio. Genius, absolutely genius.