Analyzing different types of bunker sands

Karl Danneberger

As a preteen, our family vacations consisted of arduous cross-country trips in a 1963 Chevrolet Bel Air station wagon. Our vacations originated in Illinois and spread to destinations in the West and Southeast.

At the time, one of my hobbies was collecting soil samples. I can’t remember why I was interested in soil, but I would collect a sample from each state we visited. If we were in Nebraska, my dad would stop along the highway or in a town, I would collect a small soil sample with a spoon and place it in a glass vial, labeling it with the state’s name. We would then continue our journey.

The 1963 Chevy Bel Air didn’t have air conditioning or a radio. There was not much to do in the back seat. I spent a lot of time staring at those glass vials containing soil samples. I often wonder what I was thinking during all those miles, but I do remember the variation in color from the red clay of Georgia to the dusty gray of Death Valley, the shape and texture of the “black gold” of Iowa to the rocks of Wyoming.

I was in Cairo, Egypt, a couple of years ago and came across a young person in a market outside my hotel. I noticed he was holding a jar of sand, so I asked him about it. He told me he had collected it from the banks of the Nile.

Sand collecting, who would have thought? Actually, there are societies of sand collectors, including the International Sand Collectors Society. As described on Wikipedia, a sand collector is an arenophile, or “sand lover.” The word does not exist in the Merriam-Webster dictionary. It must be a relatively new description. Fascination with sand centers on the variety, color, mineralogy and location. The most desired sands are the rarest. Some of the rarest are found at Pitcairn Island and Easter Island. The black and green sands found in Hawaii are so rare that collection is prohibited.

Sand is widely used in golf course management for green construction, topdressing and in bunkers. Superintendents’ interest in sand is technical. Their primary focus is on the size, distribution and shape. Sand is distributed into five classes based on size, ranging from very coarse sand to very fine sand. The importance of sand-size distribution is well understood. Sand shape, however, often is glossed over. It is described in two terms — angular or round.

We use two geometrical parameters, sphericity and roundness, to describe the shape of sand grains. The terms are not synonymous. Sphericity is a measure of how close the shape of the sand approaches that of a sphere. Roundness describes the sharpness of a grain’s corners and edges regardless of shape. Sphericity and roundness are determined visually. From the Krumbein roundness test, or Riley sphericity index, one matches the sand shape with what appears in these charts. The sand shape falls into one of six categories, from very angular to well rounded.

“Round” sand is not just round. Round is either well rounded, rounded or subrounded, while angular could range from very angular to angular to subangular. Like sand-size distribution, sand shape is best described by an accurate description.

Sand angulairty affects firmness of a putting green surface. The more angular the sand and associated lower sphericity, the more adhesion that occurs among the sand particles. Adhesion increases as the edges of the particles grab the surface and bind together. As management practices move to providing firmer putting green surfaces, the degree of angularity in a sand topdressing material becomes a factor.

Vacations are like sand, everyone knows what they are. However, you do not really know the characteristics of each, until you look closer. Vacations improve over time, but I wish I could take one more trip in that 1963 Chevy Bel Air station wagon.