First a bit of background info.
When the course was built in 1912, the priority for play was to provide good conditions during the summer months. The winter months were spent playing on links courses.
With this in mind, the greens were constructed to retain moisture.
The greens have a band of hard impermeable material at a depth of 500 -600mm. This traps moisture in the profile and increases the chance of water-logging during periods of wet weather. Below this (on many greens) is good quality sand.
To try and improve this situation, we drill holes (1200mm deep) across the putting surface. These holes are 90mm wide (same as a hole cup), so are easily repaired.
This pic shows the hole cut ready for drilling, with a board in place to prevent damage and aid cleaning.
The above pic shows the dark, heavier soil below the turf roots.
This pic shows the sand below being removed (this is the back tier of the 10th green).
Once the sand and soil is removed and the hole cleaned out, we fill up to 250mm from the top with a 5mm gravel. This is then covered with 150mm of sand and then the plug is replaced.
As you can imagine this is a slow, labour intensive job. The 10th green took 3 people, 3 days to complete. We have carried out this process on the 1st, 2nd, 9th, 10th, 11th & 16th greens so far, concentrating on the areas which flood or hold water.
We will do as many areas as we can before the start of the season.