Drainage system

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• Insights
• The choice of the pitch
• Fields in Natural grass
• Fields in Synthetic Turf
• Experience in the field
• FAQ - Hybrid grass
• Natural vs Synthetic
• Zeolite - mineral soil conditioner
• Cocopeat - organic soil conditioner
• Cork - elastic element
• Irrigation management
• Natural grass reinforcement
• Protection of synthetic turf
• Ground levelling
• Irrigation system
• Drainage system
• Slit-drains in the soil
• Drainage layer
• Growth medium
• Successful installation
• Renovating hybrid grass
• Gypsum calcium saves water

Drainage system

An effective drainage system is essential for modern playing fields. Immediately after levelling the ground and installing the irrigation system, the rainwater drainage network must remove excess water to maintain the air/water balance in the growing medium.

A good rule of thumb is to create a drainage network in the ground with interconnected trenches to channel excess rainwater that drains away by gravity to the drainage system. Drainage pipes filled with crushed stone must be installed in the trenches up to the top. In the case of low rainfall, the water that reaches the drains is dispersed in the trenches, slowly filtering through the soil before entering the pipes so that it does not burden the sewer system. As the intensity of the rainfall increases, the water level in the trenches rises and the excess water enters the micro-drilled pipes and flows to the sewer. The system is very effective, but in some cases attention must be paid to the risk of raising the underground water table because the water may also rise through the pipes temporarily flooding the field.

Above the drainage network, layers of crushed stone and sand of various thicknesses must be installed according to the project objectives. These layers must be highly draining in the case of modern fields so that rainwater filters quickly and then reaches the existing soil and is channelled into the drainage trenches.

Construction of drainage trenches

Within the soil, water moves vertically due to the forces of gravity but also horizontally due to capillary forces. Understanding the movement of water in the soil is therefore important in order to create a functional drainage system to allow water to infiltrate from the surface to the drainage system.

The drainage network system with connected trenches is a technique used in numerous sports field constructions in Italy. In the past, in most cases a filter layer of mixed sand and gravel was installed above the drainage trenches, followed by a layer of soil to cultivate natural grass. As is well known, soil is composed of a part of solid minerals such as sand, silt and clay and a part of empty spaces or pores where water and air circulate and biological activity develops. The pores are divided into micro-pores and macro-pores according to size and if the ratio between them is 1:1 then the soil is filtering and vital because all biological processes take place regularly.

After a certain amount of play, the puddles that form on the surface highlight the poor infiltration capacity of the soil. The main cause is intensive soil trampling, which compresses the macro pores on the surface when the soil is excessively wet, de-structuring it and producing mud. Soil with a high silt and clay content is more prone to constipation; the number of macro-pores where water drains and biological processes are significantly reduced.

In order to facilitate water infiltration, the soil must be tilled several times a year and in most cases a system of micro-drains must be installed to prevent water from pooling on the surface.