Well well well, I can say, it actually really depends on where you locate...
You are right, if it happens at 東江, it's obviously an issue to HK...
Frankly, 5000 tons of disposal is around 400 loads. Assume you are doing it in a working week (80 Lds per day @ 12.5 metric tons per load), you need a least 1 excavator and I assume there are 10 trucks involved (the more the drivers, the tougher to keep it secret)... I would say it very well depends on the inspection of local authority, and also the self conduct of truck drivers...