[Yannick Pilon]

This is mostly a question for architects, superintendant, or people working in the golf course construction business, but anyone with some valuable input is welcomed to chip in.

Does anyone on this site have any experience on regrading the surface of USGA greens to modify slopes and change the surface drainage?  The reason I am asking is one of the clubs I am working with needs to re-sod a couple of USGA greens that were built a few years ago.  The plan, so far was to simply remove a 4-inch layer of mix along with the poa on the surface, add and mix-in a new 4 inch layer of mix on the surface, and re-sod the green with the new washed bentgrass.  Now, the superintendant would like to change the slopes in a few areas to improve the surface drainage and prevent ice damage, and we wonder what would be the best way to do this.

Some clubs in the Montreal area have done this recently, by simply reshaping the mix in the green cavities.  The results are apparently flawless, and don't present any problems.  However, doing this would have an impact on the 12-inch mix layer, raising it to 14 or 15 inches here and there, and possibly lower it to about 10 inches in other areas.

Would any of you have any idea if this is a potential construction or political suicide if the results are not up to the expectations, or just a simple and practical way of fixing a problem?  Excavating the entire mix and drainage stone layers and working on the subgrade to ensure a constant profile of these two layers sounds like a costly and technically difficult way to fix a fairly simple problem.  Or are we at an age where, as architects, we are better off sticking to the official specs of the USGA simply to protect our ass?

Your thoughts, please!

YP

[Jeff_Brauer]

I have done this with good results in Texas and on Bermuda greens.  I did it in Chicago years ago and it seemed to work fine for bent greens.  The USGA allows 10-14" of mix so if you have a constant 12" you can lower the ridges 2" and fill the lowest valleys 2" to reduce overall slope for today's green speeds, at least a bit.  I wouldn't attempt to radically reshape the contours, just flatten them for green speed.

If you have deeper mix, then it tends to drain faster, and shallower mix tends to drain slower. Thus, if the deeper mix is now at the bottom of greens it helps drainage, and if the shallower mix is on the humps, it slows drainage and reduces dry spots, at least in theory.

Now, I am not sure if raising the high spots is as good an idea, but I think it could be done.  You would probably have some dry spots that need attention. If low areas near the green swale exits are now shallower, you won't be cutting a pin in the last 10', but might want to make sure you have a "crow's foot" tile at the inside dish just to make sure that area doesn't hole water.

Just what is the slope in the areas that he wants to improve the drainage?  I think 1.5% would be enough, although I would like more in cold climates.

I am also not sure if it would be political suicide or not. That would vary by club.  But, in these times, I think if you presented the options as you describe and examples of where it has worked, and let them make the choice, it would be their call.  In this day and age, presenting a reasonable, lower cost option has to be appreciated, I would think.

I should add the disclaimer that I haven't got a clue about where you are talking about, the on site conditions, etc. and always, and especially, I could be wrong.  Certainly, on site advice would be far better than internet advice from someone who has never seen the real conditions.

[Adrian_Stiff]

My opinion is this; in the strictest of terms if you add or subtract anymore than 1 inch either way you wont have USGA greens if they follow a gravel and intermediate layer, although as we all know the spec has changed so much who really knows the meaning anymore. If you have a consistent 12", I think you be better to add rather than subtract ie add 3 inches but only ever borrow 1. Deeper areas 15"+ seem to work better on flatter areas, shallow areas on higher grounds are more likely to create drying out and possible hydrophobic soils, possibly if you can don't touch the high areas. I think this is the main area for concern.
Overall I wouldn't really want to sign this off professionally, but I have done this sort of thing and its worked pretty good.

[Lester George]

What Jeff said. 

If you get to moving more than a couple of tenths up or a couple of tenths down you can sustain most scrutiny in the profile and the supers are usually pretty good at managing it.  You start changing things 4 to 6 inches or more and I would recommend you take a look at changing the gravel layer to match.  Out side of that you can rest assured you are placing the noose around your own neck.

Lester

[Tom_Doak]

I would not do that.  I am not necessarily a believer in the perched water table effect of USGA greens on a contoured surface (especially on some of mine), but leaving the sand layer shallower in some places and deeper in others is bound to cause difficulties, and of course you as the architect would then get the blame for anything that ever happens on that green.

Of course, I think USGA greens construction is not really the best way to go in the first place, but if you are going to spend all that money you'd better do it by the book.

[Dick Kirkpatrick]

Yannick:

I have changed the top layer of USGA spec greens several times with success, always by adding material. The greens functioned the same as before the changes were made.

As others have said, I would not lower the rootzone material for any reason, if you need to slow down the slope on the green, do it by adding material. This should always be possible, but it may require much more material to do it.

Your process of removing the sod and rototilling the existing mixture before regrading does not sound good to me because you will likely lower the rootzone depth going over plateaus, etc. in doing this. If you rototill the mixture and then add material to the low areas instead of regrading, it should work well.

I would also have the client sign a waiver, which they should do as it is them that is saving the money.

[Yannick Pilon]

Thanks for the input guys.  This is all valuable information.

Any input from superintendants who might have done this either on their own, and or with the help of an architect?

Cheers.

YP

[Mike_Young]

If you regrade the surface only of a USGA green then it is no longer a USGA green

[Lyne Morrison]

Yannick – I contacted the usga with a similar query about 18 months ago. Having checked my records just now the advice states that "it is in the gravel layer that we want architects to make 'field changes' in contouring and never the rootzone.  The only restriction is the gravel must be at least 4" deep and even 3" is OK on occasion. The gravel layer can be any depth w/o affecting the rootzone performance.”

The Jan – Feb 2004 Greens Section Record has an article on Resurfacing Greens.

Cheers - Lyne

[Lyne Morrison]

There is a typo in the post above - it should read as Jan-Feb 2006

For those who are interested this is the link - http://turf.lib.msu.edu/2000s/2006/060101.pdf

Yannick - trust you received the details ok

cheers - Lyne

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