Sand-based Athletic Fields - Construction

Construction

Sand-based systems are composed of a sand-based root zone, a gravel layer, and a drainage system. Although the root zone of a sand-based system is mostly sand, amendments are often added to increase the organic matter content and add stability to the root zone. Peat moss is the most common root zone amendment used, but other inorganic amendments can also be used. Peat moss is used because it increases water and nutrient holding capacity and decreases bulk density. The most common ratio of sand to peat moss is 8:2. This ratio will allow a water holding capacity of 15 to 26% and increase nutrient holding capacity greatly.

100% sand root zones are used often and are more cost effective. Selection of the type of sand is very crucial. Sand suitable for a root zone should be a medium to coarse (0.15-1.0 mm) particle size and should have sub-angular or sub-rounded shape. If sub-angular sand is chosen, it can deter some insects from making their homes in the soil. The shape makes it harder for them to move around in the soil. Rounded sands are not suitable because they do not pack and cannot provide a firm enough seedbed. Angular sands are not suitable because they become too firm and can potentially cut into roots. Once a sand is selected and it is determined if an amendment will be used, the layout of the root zone profile must be determined.

In the United States, the most common specifications for constructing a sand-based system are laid out by the United States Golf Association (USGA). The specifications for a sand-based athletic field are the same as what is typically used for USGA golf greens. These specifications consist of a 12 to 16 inch sand root zone. The choice of sand type and the addition of an amendment depend on the designer. When an amendment is used, it must be thoroughly incorporated with the sand. The sand overlays a 4-inch gravel layer. This creates a perched water table above the gravel that helps keep the root zone moist during dry conditions. A drainage system should be installed below the gravel to carry excess water away from the field.