There are two ways in which the excessive water accumulated through rains can be discharged from lawns, parks and golf courses:
Subsurface Drainage – This method is also mentioned to sometimes as internal drainage. In this method the water enters the soil by means of percolation or infiltration. This water that is in excess is then collected in drains which contain many plastic pipes with a lot of perforations. The water is then discharged into large water systems like lakes, creeks, rivers, etc.
Subsurface Runoff – The other name for this method of removal of water is Surface Drainage. In this method sudden accumulation of water which is in excess, resulting from a heavy downpour or continuous storms, etc is removed with the help of a surface gradient. The surface gradient helps in discharging the excess water from elevated areas to low lying areas.
However, incessant rains cause the areas that lie low to be flooded especially when the soil has poor water absorption properties. Open areas that are large should be sloped by at least 1 to 3 percent. Water will then be redirected to specific storm drain systems through these slopes. For golf courses, house lawns and public parks located in tropical areas which are prone to heavy and incessant rains and storms for longer period of times, the best suited method is to combine both these methods.
An internal drainage system is constructed by excavating and laying down the drains in the direction in which the water needs to be drained. This is carried out only after the sub-grade surface is properly smoothened and adequately compacted. For those areas which need to be kept dry most of the time, a drain with dimensions of 1 meter length x 0.40 meter width x 0.30 meter height with a spiral pipe made out of PVC that is perforated and measures 10 cm are in turn lined by 20 to 30 mm size of pea gravels or crushed gravel is recommended. In case of a secondary drain line, a 0.5 meter length x 0.30 meter width x 0.30 meter height fitted with a 10 cm long PVC pipe with perforations and lined with 20 to 30 mm size of pea gravel or crushed gravel is highly recommended.
There is also an additional option of including a tertiary drain which is as big as the secondary drain without the PVC pipe with perforations may also be constructed so as to feed into the drain. Storm drains are usually built of concrete in a depressed basin as these are meant to carry the main drain. The storm drains are also inundated with manholes between specific distances. It is recommended that the storm drains are reinforced with a grilled frame made of steel in order to provide added security.
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