Drainwell

Sub-surface Drainage

As time progresses urban drainage systems are being more and more challenged by the increased run-off that is generated by increased urban densities. Approximately 15% of rainwater that falls on natural surfaces finds its way into waterways, but almost 90% of rainwater that falls on the house roofs and paved driveways finds its way into the local drainage system. the water volume that would otherwise be directed to ground water or natural stream flow is vastly diminished and our environment is being severely degraded.

As driveways are extended, outbuildings may be added, barbecue areas are developed and grassed areas may be replaced by feature paving. The impervious fraction of a residential site increases. Only a few decades ago, designers of residential drainage systems expected approximately 40% of rainwater that fell on a house site would find its way into their drain.

By installing stormwater detention systems on site we can protect the drainage infrastructure. Approximately 85% of the rainwater that falls onto open ground percolates into the soil. A significant portion of this makes its way to the water table, but our ground water reserves are being depleted because urbanisation reduces the inflow and the increased use of bores that are sunk to enable the watering of gardens, parks, playing fields and golf links.

Captured run-off may be used to water your own garden or shared with neighbours and can be circulated through the toilet flushing systems these are further options.

DRAINWELL systems retain the permability of natural surfaces. The trafficable area installed does not increase run-off when DRAINWELL systems are installed over a base of coarse gravel, the interception rate will be higher than that of the open fields. The DRAINWELL system may be installed as part of a stormwater detention or retention system. The stormwater interception may be allowed to drain into the subsoil and released at a slower rate to the local drainage system or it may be captured for reuse, being stored in the DRAINWELL structural storage system.

This system of stormwater storage may be designed to capture excess run-off.