Friday, August 11, 2017
August 11, 2017
On Wednesday, August 9th, we performed a bit of surgery to the 14th green.
Lately we have been noticing a “wet” area on the back center slope of the green that does not dry down as well as the rest of the green. At first we thought the cause might be due to too much hand watering, or that the sprinklers were not functioning correctly. We found that neither of these are the case.
Understanding that the green was “expanded” sometime about 20 years ago to the back and to the left for the LPGA, Kevin, our assistant brought up the possibility that when the green was enlarged, perhaps the loop of pipe that feeds the irrigation heads may have been left as is and the expansion built over it. If so, the pipe could be leaking, causing the area to stay wet.
We began tracing wires and confirmed that the “loop” was still live, running underneath the green, and passing directly under the wet area.
Normally, when a green or tee is expanded, pipes are removed and a new loop is installed in the rough around it. The last thing anyone would want is a leak under a green or tee, or worse yet, a blow out that could wash it away. Why the loop was left to lie beneath the green is anyone’s guess at this time, since no one from that project is available to talk with.
Acting under this premise that there was a leaking pipe, we carefully removed the sod and dug down about 3 feet, exposing the live pipe. Running alongside of this pipe was the abandoned pipe from the previous irrigation system before the present one was installed in 1986. Over these two pipes was the metal pipe that was part of the first irrigation system, which I think might date back to the 1950’s or before that. Three generations of pipe underneath the green!
After carefully exposing the pipe and inspecting it, we found no leak at all. That was good news in some ways.
The answer to the wetness though, was in the soil profile, which our careful trenching had also exposed. In this area, we dug through layers of different types of soil and sand that have different physical properties, causing a perched water table.
Looking at the photo, beginning at the top, there are a few inches of sand that is from our present program of only using USGA spec sand to topdress and modify the soil to help it drain and to keep the surface dry and firm. You can also see the vertical channels of sand that are from the many standard aeration and drill and fills that we’ve performed over the years, which have helped increase the surface drainage, and create a healthy root zone. After this top layer, the problem becomes very apparent.
Directly under our sand is a layer of lighter colored sand which most likely was used when the extension was either sodded or seeded. I imagine it was sodded and this is the sand that the sod had been grown on at the sod farm or nursery. The next layer is a very heavy, tight, top soil. Under this is a cupped shaped sand lens, resting on a band of heavy, organic soil which I think possibly was the grade of the original rough. Beneath this organic soil is the subsoil. All in all, there are 5 layers of differing soil types that drain and hold water differently above the subsoil.
In most cases, a “pushup green” is built of soil, yet even back in 1923, it was understood to have at least a consistent 6” profile over coarse, drainable subsoil. Now, a green is built on a 12” deep sand mix that has been lab tested (preferably to USGA specs) for drainage, aeration, water holding capacity, organic matter, pore space, bulk density, etc , over a gravel blanket and drainage system.
Obviously, the green extension was made of many types of soils layered haphazardly over each other resulting in no chance of consistency and very poor drainage. I am not sure why this was done, or who did this, but at this point, it really doesn’t matter. It’s there, and always will be there unless the green is entirely rebuilt to spec.
I believe, as well as the two consultants I contacted for second opinions, is that the excess water is holding up in the sand area and cannot drain easily enough so that the water is backing up and maybe even wicking up the drill and fill channels.
The reason it became so evidently wet lately is because we’ve had so much rain - the 4.75” rain we had two weeks ago, followed by two more inches days later.
We thoroughly mixed all the soils that we had excavated finding the pipe, making it “consistent”, and used this to backfill the trench. We did not want to back fill the trench with something so different, such as our USGA spec sand, because then the trench would be too dry and act so very differently than the surrounding areas that another problem would be created! Hopefully, the water will find its way to this “mix” area and drain the surrounding area. Going forward, we may purchase a 2’ by 1” drill and create channels that go deeper than the drill and fill to break through the layers and improve drainage. This would be a very time consuming and labor intensive project, and would need to be a fall/ winter project.
As for having a live pipe under the green, we can either redesign and install an entire new greens loop in the winter, or leave it for now and keep our fingers crossed that it doesn’t blow, knowing we are planning to install an entire new irrigation system within the next 18 months.
For what it’s worth, this is a great example of how a green should not be built, and underscores the importance of our soil modification program that we started when I re- arrived here 14 years ago. Without all the aerations and the bi-annual drill and fill, conditions would have remained much worse, as I remember them. When I arrived here, my notes from that time document that this green was struggling with many bare areas throughout the extended area.
At the least, our soil modification/ topdressing programs cannot solve everything, but they have given all the greens a consistent mix on top and have provided improved drainage throughout most of the greens. We don’t struggle as much with poor turf, even under the circumstances that we found on 14 green.