Conventional Block Paving

Block Paving - Conventional

Surface water from conventional block paved driveways can be directed onto a border, rain garden, lawn or a soakaway. This is achieved by creating an average slope or fall of 50mm towards the rain garden chosen rather than using traditional gullies and drains leading to sewers. The driveway should be sloped away from the house and rain gardens and soakaways positioned at least 3 metres distance from buildings.

RAIN GARDENS are created by forming a depression to allow the collected water enough time to soak into the subgrade. Rain gardens with appropriate planting offer the extra benefit of attractive and robust green spaces. Complimentary gravel or cobbles can be used as decorative features around the plants to reduce the evaporation of water. Rain gardens

should not have mulch on the surface as this will float when water collects on it. Concrete dished channel blocks can help to collect and direct the water towards the rain garden.

Where ground conditions demand, such as in clay soils, rain gardens can have stone filled trenches below them to increase the storage capacity and allow water to soak into the ground more easily.

Rain Garden or graveled area with infiltration into the ground

Rain garden or graveled area with trench infiltration into the ground

Rain garden or graveled area with trench and pipe to drain away or for water harvesting

SOAKAWAYS are a similar idea except that water is piped into an underground chamber or gravel filled trench and allowed to soak into the ground. Soakaways can be located along the edges of conventional block paved driveways or beneath the garden area adjoining. Water is collected here and allowed to soak into the subgrade. On clay soils, it may be necessary to connect to the house roof water drain. The aggregate used for the soakaway must have open voids in it and no fine material. Water should flow freely into it. There is also potential to direct water from rain gardens to the urban drainage system (permission may be required) or to rainwater harvesting for re-use. As a rule of thumb, a pipe will be required if it takes a water filled 300mm x 300mm x 300mm pit more than 11 hours to empty.

Water from conventional driveways is directed onto a rain garden

NB - Water should never be directed to a neighbours garden or property.