Are Your Bunkers Measuring Up?

If you own or manage a golf course, you will generally have to deal with the building or rebuilding of a quality bunker. While it might seem exciting to “be on the beach” the challenges of the sand are not the only challenges associated with the infamous hazard. There is a lot to be aware of when you select the sand for your course. Otherwise, you might be hearing complaints from your golfers about how hard, how soft or how unplayable the sand is. So what does make a bunker great in quality and playability?

The majority of bunker sand comes from beaches, river beds, and igneous and sedimentary rock deposits. But experts say there are few places in the United States that have natural sand deposits that meet specifications for great bunker sand and that finding it is very difficult.

However, the U.S. Golf Association lists the following main factors to carefully consider when selecting bunker sand:

Particle Size – The playability of sand is significantly determined by its particle size. Determining the particle size distribution of a sand sample is fairly precise and is the primary means for evaluating the potential impact of the bunker sand on the agronomics of the green. As a general guideline, the majority of sand used in bunkers, about 75% or more, should fall in a medium-coarse range (0.25 mm – 1.00 mm). The remainder (0.05 mm – 0.25) should remain in the medium-fine to very fine range. Silt and clay (particles below 0.05 mm) should be kept to a minimum.

Particle Shape & Penetrometer Value – Playing quality and maintenance is under a strong influence of the shape of the sand particles. Particle shape might be the most important factor of all. The shape is classified by examining both the relative sharpness of the particle’s edges and the overall shape of the particle itself. Angular sands, rather than round sands, are preferred for bunkers. The shape will have great affect on the potential for a ball to bury. The penetrometer reading (the potential for a fried egg lies) has been the test of choice.

Crusting Potential – Crusting is the formation of a thin (typically 1/4 to 1/8) inch layer of dried, stiff sand on the surface of the bunker. Crusting is directly related to the percentage of silt and clay in the sand and can severely decrease the playing quality of the bunker.

Chemical Reaction & Hardness – This determines the makeup and stability of sand as particles can change in shape and size due to wear.

Infiltration Rate – Infiltration rate refers to the sand’s ability to drain after rain or irrigation. Bunker sand should have a minimum infiltration rate of 20 to 30 inches per hour.

Color – Bunker sands are generally chosen for their color. Although subjective, most golfers like the look of soft white sand contrasting with lush green grass. However, on a brighter day, white sand can cause significant glares. But, while color is aesthetically important, performance criteria should be a greater factor.

Playability – Also extremely subjective, the playability of a bunker will differ from player to player. Most tour professionals and low handicappers prefer firmer sand because it allows the players who have developed a clubhead speed to put a spin on the ball. Higher handicappers tend to prefer softer sand.

While unfortunately not all golfers like the same sand, a good rule of thumb for whatever type of sand you use on the course is to keep play in a consistent manner. When adding sand to an existing bunker, perform the same work on all the bunkers.

Overall, experts say the most important part of selecting sand is to have a complete bunker sand analysis performed by an accredited laboratory on all the characteristics. The laboratory will need a one-gallon sample of dry sand to perform a test, which ranges from $100 to $200 per sample.

Finally, other factors that have nothing to do with the make-up of the sand but need to be considered for playing quality include: length of time the sand has been in the bunker, depth of the sand, design, maintenance and raking.