A combined kerb drainage system must be considered where the minimum longitudinal gradient of a carriageway is less than 1 in 100 for flexible surfaces and less than 1 in 80 for block paved surfaces.
There should be a rodding access at head of the system with periodic outlets as required and an outfall that uses a propriety sumped gully unit. The system should be able to be cleansed in the same manner of a standard gully (with a gully sucker).
A commuted sum is required to cover any additional maintenance where a combined kerb drainage system is used.
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Figure 53: Example of a combined kerb and drainage system