RE: Next week11 Sep 2020 18:04
Hi napthman
If you go to the web site or better still Newcrest presentation you can see that that the High Grade Zone and breccias go straight down. To find the depth they have had to step out southwestwards to angle the drill. There is no ore body directly under the drill position.
I've been posting this since March that I believed this was the Decline position and will they be drilling anymore there well probably yes.
The Decline design is complex and will need detailed geological study involving drilling.
A complex system called Dubins paths links the 2 known points i.e. the start and finish. It finds the shortest route in 3D format using a Decline Optimisation Tool a DOT2 keeping a barrier between the decline and the ore body.
The Decline will start from a portal deep in the ground low enough to keep the roof of the tunnel stable , this depth will need to be found by drilling probably 50m deep or there abouts and may have a galvanised metal entrance covered with concrete.
Costs for drilling I found in 2008 were $4000 dollars per m , our decline is likely to be 3000m just to get to the top of the ore body at 6 degrees, so the costs are high and that software tool DOT2 can save a fortune.
The speed of the tunnel boring machines are dependent on what type is used and the rock type, a fast one can do 1 mile per week or 7 days, the slowest ones slower than a snail but that's installing concrete segments as well in unstable ground.
All brings back memory's of building the Dartford Tunnel, the compressed air thing wasn't good