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I don't know of any civil engineer who would have approved that drainage "system" - it looks like it has been put in as an afterthought by the contractor. If it is drainining a reasonable section of track it should be an approved system similar to that which is used on motorways, which is usually a system of slot drains and off-line catchpits, connected via 225 diameter RCRRJ pipes (or bigger, NZTA use 300 dia min these days).
The catchment area needs to be calculated, and then the flows calculated for the 10 year storm event - a normal catchpit will give you 27 litres/sec input flow but with a slot drain you can double that. That golf ball sized hole (which will block in no time at all) would give you only about 7 l/s even at a 10% gradient! You don't need much rain to get that to pond, and there is no overland flow path if it blocks, so it is simply not safe. I wonder if that is why the FIA would not grant it a Grade 2 licence?
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