The combined height of the flue at 70m and the OD of the quarry floor at 95 m seem to indicate the outlet at 165m. Is this correct?

The stack is 70m heigh above the ground level.  The base of the quarry will be generally brought to 90m AOD (above ordnance datum). Note: 0m AOD is generally the mean sea level, therefore 90m AOD refers to the ground level being 90 above the mean sea level.  The stack will therefore be 160m AOD, however will be 70m tall or 70m above ground level.