Groundskeepers for the clay courts for the French Open tennis championship are being forced to drench the courts with a mixture of water and salt to prevent them from cracking.
The temperatures in Paris, France, have soared to over 30 degrees Celsius since the start of the tournament in mid-May with peaks of over 35 degrees witnessed. Head of Court Maintenance, Philippe Vaillant even called the experience “unprecedented”.
In addition to the players, the heat also affects the courts themselves which are made of clay. To ensure the 18 tournament courts as well as the 15 practice courts continue providing an adequate ball bounce and grip for the players, the 200+ groundskeepers soak the courts each night to recharge the different layers. In doing so, they hope the water will rise up again during the next day, thereby maintaining the integrity of the surface.
The Roland Garros clay court construction is 80 centimetres high and consists of five layers: large stones, gravel, a sport-technical layer made of volcanic-rock residue, limestone, and finally, a thin layer of crushed brick that gives the court its colour.
“The crushed brick layer is 3 to 5 millimetres thick,” Vaillant said. “The most important part is the limestone layer underneath. That’s the actual playing foundation. The crushed brick is mainly there for colour and as a material that provides some sliding ability and an important visual contrast, since the limestone is almost white.
Light watering
“This limestone layer must remain moist at all times,” he added. If not, the court would become slippery, and, as such, dangerous to the players. “It’s compacted crushed stone maintained through water supply. If we let it dry out too much, the courts could crack. We have to stay vigilant.
“We spread calcium chloride over the courts in flake form in the morning. It melts on contact with water and helps retain surface moisture. And of course, the court dries out because of player movement.”
During matches, courts are watered between each set, something groundskeepers do not normally do under standard temperature conditions.
“This light watering reactivates the calcium chloride that remains in the crushed brick layer,” Vaillant explains. “We only apply it in the morning, roughly one 25-kilogram bag per court.”
Re-use of water
Watering each court requires 1 cubic metre of water per court. A tank beneath Court 7 holds enough rainwater that has been collected throughout the year, to water the green spaces at Roland Garros. However, French health and safety regulations currently prevent this water being used for watering the courts as well.
“But a decree has just been signed allowing sports surfaces to be watered with rainwater,” Vaillant points out. “So we now have a project to collect rainwater in order to water the courts. The construction department is working on the project.”