My drains have ‘bumps’ in them that weren’t present when I designed them.

Symptoms:

A drain line was created with a set profile but when implementing it seems to have unexpected deviations. 

Cause:

Multiple drains were designed and have overlapping sections. The profile of a drain gets ‘overwritten’ by the profile of a subsequent drain.

Solution:

Design and implement one drain at a time. That way you will get exactly what is shown in the design step (if you always implement on the original surface for instance)

In the design step apply each drain individually rather than choosing the 'Apply all' option. Each subsequent drain should use the 'Design surface' as the surface to apply on rather than the original surface. In this way you are designing the drain profile on a surface that accounts for the effect of previous drain lines. Note that the order of drain design matters in this case.

Drive survey of drains individually instead of driving one drain to inevitably need to ‘split’ the drain where overlapping another drain.