Ann: Mackay SOP Project Update, page-30

No doubt you are dismissive of bores because RWD are toying with the idea.
Yes they are expensive.
Grade dilution is a real issue, as discussed in the Argonaut report and RWD hydrology/resource statement.
Bores potentially avoid the need to increase pond size and pump larger volumes to maintain output.
Just because AMN hasn't mentioned bores doesn't mean they don't have a role to play.
AMN and all the trench operations will have to deal with grade dilution. I'm guessing it can be dealt with by retrenching or increasing pond size or using bore supplementation or a combination of these.
Finally there is the issue of mine life.
Accessing the top 6 meters limits mine life. Accessing the full 100 meters plus offers a longer life.
The graphs on the Argonaut site show the interaction between grade, flows and both bores required or km of trench.
Lower grade operations are less suited to bores.