It is an assumption, but its an assumption based on good...

It is an assumption, but its an assumption based on good evidence. It will not be until assay's come back that there is confirmation of the grade.

Regarding Diemen heap leach, there was drilling and associated assay's that established the expected grade within the Diemen pit. This material was moved to the heap leach and waste piles. Past owners documented the expected grade of the heap leach. Some unknown amount of Gold was recovered but nobody undertook the next step which was using a heap leach as a production method for further mining. From the volumes released, someone took further material from the heap leach and put it somewhere. One of possibilities is they did soils on the top of the heap leach, they came back with acceptable, grades and they took the top off the heap leach and took it to the mill along with the Tasman ore and some Laterite pit ore. If that's where the ore went, the top of Diemen heap leach went, it was probably well over 1g/t. The bottom may have collected more leach so who-know's what grade is there but test work confirmed only middling recovery rates from column leach tests (under ideal lab conditions). The other primary possibility for the volume differences is that some of the Diemen heap leach was shifted to a new location to assist site remediation efforts - if so, where?

Regarding Tasman, from the gold prices at the time, we know only grades above about 1.5g/t were economic to take offsite and process. They also knew that gold prices had been much higher in the past and there are references to the waste cut-off being 0.6g/t. We know that they took slices of ore/waste off Tasman because of the RL heights of all the TS1, TS2 and TS3 drill intercepts. If they were simply trying to get the known higher-grade sloping ore body, it probably wouldn't have been mined in large flat slices. Satellite pictures don't show an obvious southern high-use entry point to the secondary Tasman pile indicating it was created from the north. If it was created from the north, this occurred before the pit got particularly deep. The most likely candidate is laterite and other near-surface ore that wasn't at the 1.5g/t cut-off. Yep, its an assumption that the material below 0.6g/t made it to the primary waste landform. That 0.6g/t to 1.5g/t made it to the ore piles recently drilled and that ore over 1.5g/t was taken to the mill, but its an assumption that best fits the available facts.