I see your point and concern.
A third voice with multiple projects under their belt is always a good thing to have. The engineering firm who designed the facility can be viewed as having a vested interest in the project, since they will build or supervise the building of the facility.
A third party, even though they are being paid for their advice and opinion, will be viewed as having less interest in the completion of the project since their pay is not directly connected to the dry stack method's approval.
I believe this is mostly being done to provide the DRMS a source of working, verifiable projects using the dry stack systems and the consultants can also speak to seismic and avalanche concerns.
Using the dewatered tailings for backfill in the existing mines may also be something to consider further down the road. Stopping water leakage from one working to another seems to be another use for the tailings when mixed with binders. (It is used to backfill existing shafts, with a high rate of success.) That will stop Hennis's arguments about the source of the water quickly.
JMHO
Don't take my word for it, Do your own research! Then you will know it's true!
