[Don_Mahaffey]

Nowadays, almost all greens are built with internal drainage. Whether CA style or USGA, choker layer or not, whatever the greens mix, almost all greens constructed today have some sort of drainage tile installed. In most cases their is a trunk line running down the center of the green with lateral lines tied into the trunk line which exits at a low point and terminates wherever it can daylight. Does this change the way greens are designed? I got to thinking about this last January while we were constructing our putting green. It was tough to use one trunk line because our green had a lot of elevation changes and although we could have trenched at depths that would have allowed water to drain, we instead ran three different trunk lines out sideways instead of the normal one line running the length of the green. It seemed to make a lot of sense to me, but I had never seen it done or even heard of it. For instance, if you had a green that had a ridge across the middle with the front sloping toward the front and the back to the back, wouldn't it make more sense to have two different drainage systems rather then one? Is this done?

[Joe Hancock]

Don,

You just described a case of design impacting drainage. I also know you well enough to know that you know the answers to these questions!  

As long as all the low spots in modern green construction has drainage under them(and flowing downhill!), what difference would it make how many directions or trunklines are used to do it?(OK, cost would matter, but besides that...)

Have you had any rains lately that have got you thinking about this? Is rain even in the meteorologists vocabulary this time of year in your part o' Texas?

Happy salt flushin',

Joe

[Don_Mahaffey]

Joe,
I'm not sure it has to cost more as tile is cheap but trenching and shooting grades takes time ($$$).

Nope, no rain since June. Hot, dry, and breezy. You don't need a wet towel to clean your ball at my place

And yes, we're attempting to flush weekly along with verti drain going out every other week with 1/2" solids to 8". We're trying to keep everything moving down, but a few are turning funny colors.

[Jeremy_Glenn.]

Don,

Don't worry.  We use two (and sometimes three) exit points on all our greens we design.  One in the front, and another on one side.  

We try to avoid one exit point because we find that one exit point means that (obviously!) the entire green drains towards that point, thus concentrating all runoff water to that one area, which can lead to turf problems later on.

Of course, using two exit point does make the drainage system slightly more complex than a series of "V"'s running up the green.  For example, you don't want the main lines to curve too much, as it makes it more difficult to flush the system.  It's still pretty simple though, as I'm sure you found out.
____

One trick I use when designing greens is to design the drainage grid first.  It's avoids problems later on (designing a green that doesn't drain!! ), and it really helps define how and where the greens slopes to.

[Patrick_Mucci]

Don Mahaffey,

Don't current green drainage systems inhibit substantive alterations to those greens in the future ?

[Don_Mahaffey]

Patrick,
I'd think that in most cases substantive alterations to modern greens would require tearing it up and starting over. As you know, the attempt is to have the sub grade mirror the actually surface, thus creating a uniform depth root zone. You start moving the surface around and that uniformity is gone. Growing a green with 4 inches of rootzone in one spot and 18 inched in another would not be fun.

[bpwheeler]

Joe

I think you are right in saying it's the design impacting the drainage.

Don

Yes it's done.  In fact, we just finished construction on a new hole for a remodeling project we designed where we used two trunk lines because of the green contours.

If someone could help me out (since I am new at this!) I could post a picture showing the drainage.

Ben

[Don_Mahaffey]

OK, so now we know it's a techique to use multiple trunk lines and it appears that's not all that unusual. So why was I on three different construction sites last year and I never saw it done. So maybe the better question is, do some architects use internal greens drainage issues as a reason to build fairly flat, boring greens? And one more question, with the science available to us to measure the amount a certain rootzone will perc, and the drainage tile available to us, is it absolutly imperative that every part of the green must surface drain off the green? I built a green last year that has a small section that does not surface drain. We spaced the tile closer together and made the mix a tiny bit thinner and so far so good. Don't we have the tools to throw some of the assumptions about modern greens construction out the window?

[Tyler Kearns]

Don,
     Up here in Canada, it is important to design greens that surface drain off the green. It prevents green damage in the spring when snow is melting but the ground is frozen or relatively impervious. It is thus also important to have the excess water exit the green at multiple points to limit potential damage to the turf on the green surrounds.

Tyler Kearns

[RT]

Don,

In theory the USGA guidelines gravel layer, above the subgrade, only has to have a "minimum" thickness of 100mm.  So on a wildly contoured green you could have one main trunk line, with attenedent feeder drains (5m on-center  ;)max spacing) in a typical herringbone pattern, on a uniformly pitched subgrade.

The greens mimicing contouring, at 300mm below can be done on varying the thickness of the gravel layer, as long as 100mm "minimum" gravel layer thickness is maintained above the subgrade.

[Jeff_Brauer]

Don,

Count me in the multiple trunk line group.  My only caveat, from experience, is that as long as the exit points are on the naturally low side of the green, the cost doesn't go up much.  On those few occaisions where we try to drain the green into the hillside, and not down it, then the amount of pipe running around the high side of the green adds up quickly.

The biggest reason we use multiple exits is that I have seen contractors set the trencher at 2 foot depth, and trench away, following any contour in their way, including the ridges, which just doesn't work out well, since pipe must continually go downhill for drainage.....

[A_Clay_Man]

Don- Could you elaborate on the funky colors you're getting? Are they all on the high points? Or is it a yellowish hue? or what?

Have you been getting the lightening we have?

[Lester George]

Don,

We design them everyday.  Is it done? Absolutely, positively!(no pun intended)

I have had as many as three exits and three differen drainage directions in one green.  Trying to force it all into one continuous herring-bone or grid just does do the job for greens with multiple levels.

Lester

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