Friday, October 24, 2014

Bunkers

 
As I mentioned in a previous post, we are removing the sand from the bunkers on #1 and #5 and replacing it with a different bunker sand.  If the green and golf committees like the new sand, we could possibly budget to replace the sand in all bunkers.  The sand for these bunkers is scheduled to be delivered on November 3rd.
 
Our bunkers are built to the "Billy Bunker" spec.  They are named after Billy Fuller, who designed this spec.  This means in every bunker, there is network of internal drainage and then capped off with a blanket of 2" of pea gravel, a liner so the gravel doesn't mix with the sand and finally, 2-4" of bunker sand.  The new Billy Bunker spec does not use a liner, rather a polymer is sprayed on the gravel that binds it together, yet remains porous.  During heavy rains, the excess water moves through the sand where the gravel acts as conduit to carry the water to the drain pipe.  This minimizes the sand washing on the faces.  In a climate like Highlands where we receive 100" of rain, this is much appreciated!
 
The downside of this spec, without getting into soil physics, is it creates a perched water table.  In short, the sand stays wet.  The SP55 bunker sand we use is also full of fine particles that packs really well.  Combine these two and we end up with very firm bunker sand.  This is great for fairway bunkers but not so great for greenside bunkers.  Hard sand is created when there are varying sand particle sizes.  Think of a bucket full of baseballs.  There is a lot of air space between the baseballs.  Now, fill all those voids with marbles, golf balls and BB's.  Things suddenly pack together and a firmer, poorly drain surface results.
 
The new bunker sand we are trying is very angular in shape.  Now think of sand like a pile of firewood.  If you simply throw it into a pile, it takes up a lot of space with a lot of air space in and around the wood.  Yet if we organize that pile of wood, we condense the space it consumes.  This is the equivalent of compacting sand.  The more angles on each grain of sand, the 'fluffier' the sand will be.  It also tends to be very stable.  Rounded sand, like beach sand, is very unstable.  Think about the feeling of walking across the beach.  It also moves very easily when the wind blows.  Rounded sand is usually to blame when you see 'fried egg' lies.  On the Old Course at St. Andrews, we used sand straight from the beach (shells and all) in the bunkers.  With as windy as it was there, I remember spending many days shoveling sand off the revetted bunker faces.  If angular sand was used, this wouldn't have been as much of an issue! 
 
 
Pea gravel layer beneath the liner