Construction is my line of work if that's important to you and...

Construction is my line of work if that's important to you and if you don't see how the incomplete ponds, trenches and bores are an issue then it might be wise to do some more research on how the process works as that is how the Mined resource 'Brine' is extracted, without it the plant is a shinning pile of metal.
The 18mths refers to the 2nd train (H5 and H6) not being productive since they were completed 18mths ago so no additional quantity of harvest salts on rotation to the extent they have installed some additional baffles in the existing train 1 and reused the harvest ponds there but with a 66% quicker turn around which would indicate that evaporation rate is not a problem !!
The plant has been handed over as Practical Complete which is just a way of confirming that final payment is basically due but correct commissioning is about ultimately ironing out any issues with the running of the plant and then the process.
Could be any number of additional things going wrong as it is all new but they aren't saying so don't no why they haven't started production but moisture / quality of the salts is key and perhaps the weather isn't helping.
DYOR IMHO