Drainage on a push-up green for a dummy

[Tim Gallant]

I am the dummy


I have been looking back through old threads trying to find out more information on XGD systems, and I keep seeing that they are used on classic, predominately push-up green sites. Why is this the case?


Looking at their (XGD) site, it also mentions that it lowers the water table for any green. I presume that this is the level that water sits at after watering / rain, so in theory, the lower the level, the less chance a green has of flooding / having puddles?


Apologies if this is trivial - sadly my course maintenance knowledge is lacking! But I know there are 1600 of the most knowledgable chaps here to help!

[Alan FitzGerald CGCS MG]

The XGD/TDI drainage systems are used predominately on push up greens. While they sound like something really special all they really are regular drain lines. That is not to knock the procedure or the companies, they do excellent work, however that is the simple definition of what is going on, which in turn makes it easier to understand how it works. The difference is that both companies are very meticulous during the drainage operation: the sod is removed by hand, laid out in order so it goes back exactly where it was. Rather than using stone, the trench is filled with a free draining modified soil/sand so the turf can still grow healthily over the lines. All the work is done by hand so I guess the best definition is for these systems is surgical drainage.


Push up greens are built on native soils or in some cases a modified soil. There are a lot of variables in soil type and therefore the soils drainage characteristics with this type of construction. A links course would generally have a push up green but since it is predominately sand it will drain well so adding drainage probably isn't necessary. Obviously if there was heavy clay used then the need for drainage is essential.


From what I've seen it seems like before irrigation systems were practical the thought process was for the greens to hold water so they wouldn't dry out and die. Also remember that the turf requirements/standards were not what they are now so the fact they held water wasn't as much of an issue from an agronomic point and the benefit was they didn't dry out as fast.


So the XGD type systems add drainage to greens that otherwise wouldn't have them. Once the greens have drainage they are no longer waterlogged and the result is healthier turf. Of course this helps greatly with surface drainage (which answers the second question as the bottom of the drain is now the level of the water in the green). The sod on the lines should be aerated so there are channels from the surface to the new drains to help facilitate/speed up the surface drainage. While there will be some subsurface drainage laterally through the soil to the drains it largely depends on the drainage characteristics of the soil. That is when you see drill and fill machines etc being used to modify the existing soil so the water internally can get to the drains more easily.


If a USGA spec (or California) green has been maintained properly it should drain properly for it's life as it is sand based so the water can move true it easily. XGD can be used on these greens also but it generally is not done as drainage issues on a sand based green are usually at or near the surface. Breaking through a non draining layer (by agressive aeration/drill and fill/dryject etc) is easier than adding drains as you are creating channels through the problem back to the drains underneath. However if something more serious like the drain tile failed or the gravel layer on the USGA spec green plugged up, then XGD systems would help get them draining and save rebuilding.

[Tim Gallant]

Alan,

Thank you very much for the detailed response. It certainly makes sense, and I can understand why there wouldn't be a need to put drainage into sand-based courses (ie. links).


Architecturally speaking, how many run-off areas does one need to consider for a non-sand based green? So say there is a strong storm that dumps 1" of rain in 20 minutes. How quickly will a XGD green absorb this water, and how much will start to run-off?

[Justin VanLanduit]

Alan,

Thank you very much for the detailed response. It certainly makes sense, and I can understand why there wouldn't be a need to put drainage into sand-based courses (ie. links).


Architecturally speaking, how many run-off areas does one need to consider for a non-sand based green? So say there is a strong storm that dumps 1" of rain in 20 minutes. How quickly will a XGD green absorb this water, and how much will start to run-off?

We installed XGD in 2010 to all of our 16 native pushup greens.  It's been phenomenal for us.  We had greens that we couldn't mow after .25" of rain, we can now see 1-2" and be able to go out and mow those greens.  Not right away but maybe an hour or so after the rain has stopped.  To your question regarding the 1" in 20 minutes, I'd say a good amount of that will runoff.  That is a very heavy rainfall in a short amount of time so the top area of surface would be saturated immediately and the rest would puddle and run.  Maybe .5" of that would make it into the profile.

[Alan FitzGerald CGCS MG]

Alan,

Thank you very much for the detailed response. It certainly makes sense, and I can understand why there wouldn't be a need to put drainage into sand-based courses (ie. links).


Architecturally speaking, how many run-off areas does one need to consider for a non-sand based green? So say there is a strong storm that dumps 1" of rain in 20 minutes. How quickly will a XGD green absorb this water, and how much will start to run-off?

Tim,


I've seen similar results to what Justin described so the drains make a big difference.


As for run off, Justin makes some good points on what occurs during a downpour. In a heavy rain scenario like that even a USGA green will puddle up briefly as it can't handle that amount of water at once. I'm sure the architects have their opinions on how many run offs a green (or any surface needs) but the rule of thumb is the water should have a way off the green; each break should have positive surface drainage away from the green site (and preferably not into a bunker.....) Surface drainage should be considered for sand based greens also, as the less water that has to drain through the soil/sand, the better.


The amount of precipitation that an XGD type system can handle largely depends on the drainage material used to fill the drain lines, along with the percolation rate of the existing soil. The higher the percolation rate of the drainage layer the more/quicker it will drain. However the material also has to sustain growth while not drying out quickly, so using a straight sand isn't the best option. Even using a modified sand, it's not unusual to have the XGD lines appear in the summer when they dry down quicker than the native soils.


As I mentioned in the last post the other limiting factor is the percolation rate of the existing soil. The drains will help move water from the surface but any water that soaks into the existing soil will take longer to move laterally into the drains. The more modified the native soil is, the more it will speed up drainage.


Lastly the thing that limits any drainage system is the slowest draining layer in the profile. If the native sod is replaced on top of the XGD type systems and not aerated it will still only drain at, or close to the original rate; that is why it is essential to aerate it once it knits so there are channels through it into the free draining soil.

[Tim Gallant]

Justin and Alan,

Really appreciate you taking the time to post. I can honestly say I am better educated now on this type of drainage, and surface drainage in general.


Alan, you are correct, I have been to courses where I could see, what I now know to be the XGD lines, slightly more dried out.