Managing Sand Moisture: A guide to understanding bunker performance

Bunker performance hinges on precise sand management, with moisture content playing a pivotal role in playability and maintenance. While USGA guidelines provide a reliable framework for selecting and installing sand, maintaining its quality over time remains a significant challenge. Issues like contamination, sand movement, and natural degradation often lead to poor infiltration, wet floors, and escalating maintenance costs. Fortunately, solutions are emerging to address these problems, helping superintendents preserve bunker sand performance and maintain consistent, high-quality playing conditions.

Analysing sand

The USGA guidelines for particle size distribution can be plotted on a curve that illustrates how any given sand compares to the range recommended, and therefore show the sand’s ability to drain or hold moisture.

Bunker Sand within USGA Recommendations for Particle Size Distribution: 

However, once sand is installed in bunkers after a renovation, the quality of the sand and consistency of the original specifications deteriorate rapidly. Infiltration is drastically reduced. In this case, the curve would fall outside the range recommended by the USGA.

Bunker Sand with Accumulated Fines = Poor Infiltration:

Sand performance declines over time, due to the following factors:

1. Sand movement within the bunker:  the sand on the faces is not consistent with the sand on the floor; particles move and shift from maintenance practices, drainage, erosion, etc.
2. Contamination:  bunkers are like atmospheric filters on the golf course; they collect debris and sediment and organics that work their way into the sand, drastically reducing infiltration but also have a major negative impact on playability.  This is a major cause of wet floors in bunkers, as the fine particles affect the infiltration rate.
3. Sand degradation over time:  Sand changes over time naturally as result of the items listed above and due to weathering.

In all cases above, sand quickly changes from the original USGA spec to something completely different.  

Contamination of sand with fine particles leads to:

• Severely reduced infiltration
• Wet floors
• Inconsistent moisture
• Layering within the bunker sand column
• Discolouration of sand (dirty)
• Poor playability
• Player dissatisfaction

Costs and headaches escalate rapidly; in many cases superintendents are left with no alternative than to remove existing sand and replace it or top up sand repeatedly over several seasons to achieve the desired playability performance and the functional characteristics that would be consistent with the original sand in the bunkers.  Both options are expensive and neither provides a solution to prevent the problem from occurring again.

The Capillary Washbox

The Capillary Washbox provides superintendents with a built-in sand management tool to reduce the effects of accumulated sediment and organics and allows superintendents to return and maintain bunker sand to within USGA guidelines. 

Easy to use, the washbox allows maintenance staff to wash their bunker sand to remove fine particles, simulating the same effect as new sand. While this is highly effective for maintenance, it is critical for playability performance, reducing factors such as wet bottoms resulting from accumulated organics and fine particles, and ensuring consistency for players. 

Washed Sand equates to:

• Improved infiltration
• Consistent moisture
• Consistency in the sand column
• Clean sand and colour
• Improved playability
• Happy players!