Why Do Bunkers Wash Out? October 2, 2020 By USGA Green Section Staff

Severe washouts impact playability in the short and long term, and require significant amounts of staff time to repair. (USGA)

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It’s your biggest tournament of the year, but heavy rains were experienced last night and now the golf course is saturated. Worst of all, the bunkers have all washed out and are unplayable. The golf course superintendent said it will require more than 100 staff hours to restore them, and because some of the washouts were severe, the sand is now contaminated with soil. Playability is going to be impacted for days to come, and there may be long-term problems with sand quality and drainage due to the contamination. If this situation sounds familiar, you are not alone. This scenario plays out at courses every year, and while the short-term inconvenience of washouts is very significant, sand contamination may be the bigger long-term concern.

Bunkers that wash out frequently eat up resources, demoralize staff and are extremely detrimental to playability. Minor washouts may only require minimal staff time to repair, whereas major washouts may be very costly in the short and long term. Washouts negatively impact playability in several ways. There is the immediate disruption in areas that are completely unplayable. Then, following repair, sand that was replaced will be softer unless additional time is spent to compact it. Sand that becomes contaminated with soil due to washouts drains much more slowly and is likely to become crusty when it dries out. Even relatively minor contamination can impact playability and bunker performance to a level that is easily noticed by golfers. Washouts may also mix stones into bunker sand.

Almost any bunker can wash out under the most extreme weather conditions, but bunkers vary widely in the amount of sand movement they experience during normal and moderately heavy rains. Consistent washouts are usually a byproduct of poor surface and internal drainage. If the surrounding topography directs surface water into a bunker, washouts and some contamination can be expected frequently. Fortunately, topography can usually be graded to divert water around bunkers. This is a critical first step in preventing washouts.

Drainage within bunkers also is important, and bunker drainage systems should be designed to capture water before it builds up enough volume and velocity to move sand. Usually, this means arranging drains perpendicular to the slope of the bunker and placing them close together so they intercept water before sand is dislodged. Steeply sloped bunkers are also more prone to washouts depending on their slope, size, sand depth and the underlying soils. In some situations, it may be wise to install bunker liners along with internal drainage to reduce the threat of washouts and sand contamination.

If bunker washouts are a common problem at your favorite course, chances are the situation can be improved with renovations that address drainage and design issues. The investment required can be significant, but so are the costs associated with constant disruptions to play, washout repair and sand contamination. Addressing washout issues means normal playability can be restored faster after a rain event and allows the maintenance staff to spend more time on tees, greens and fairways. That’s a win for golfers, the superintendent and the facility as a whole.

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