A typical Australian residential project may require various external surface water drainage systems. These could potentially be installed in the driveway, in front of the garage door, along paths and at building entrances. These drainage systems will often be referred to as channel drains, strip drains, trench drains or slot drains. In most cases this terminology is interchangeable, however some manufacturers may use it to differentiate between subtle differences in their product range.
New developments are designed to direct surface water away from dwellings through section topography. Some local authorities may also encourage the capture of surface water runoff from impermeable surfaces (the driveway) so as not to have large volumes of water washing across pavements. Positioning a channel drain along the edge of the property boundary and driveway will capture the water being directed away from the house, collecting it and transferring it into the local authority’s stormwater system.
Some sections on hillsides may have the fall in their land directing surface water towards their property. In this case a trench or channel drain can be installed partway down the drive, or in front of the garage and house, to catch surface water before it enters the property.
For the practical use of a garage space a level entry is required, allowing vehicles or equipment to enter and exit the garage. Therefore, a channel drain might be needed across the entrance. It is best practice to implement a small change between the internal floor level of the garage and external surface. A small ramp into the garage that would still allow vehicle access while also directing rainwater and surface water away from the opening. The channel itself will be installed into the external driveway surface. For load rating requirements, a full concrete surround is needed. Pulling the drainage channel away from the floor slab of the garage allows for this and provides room for the ramp to be installed.
Different grate designs provide different attributes. Grate total open area will impact the hydraulic performance of the system, larger individual openings are less prone to blockages from debris but may present safety concerns for catching bicycle tyres or need to be heelproof. Grate materials will affect load class ratings but may also impact aesthetics due to reactions from the environment.
Channels themselves come in a range of widths and depths allowing for a higher flow rate and better hydraulic performance. The location of the outlet can improve flow rates, a vertical outlet in the bottom of the channel provides improved hydraulic performance over a horizontal outlet at the end of the channel. Further to that increasing the number of outlets in the channel can improve its efficiency.
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