HVO 2009 Annual Environmental Management Report - Final

Coal & Allied – Hunter Valley Operations
2 OPERATIONS DURING THE REPORTING PERIOD
2.1 EXPLORATION AND RESOURCE UTILISATION
Resource utilisation at HVO is outlined below:
West Pit has an average stripping ratio of 5.5:1. This pit includes the Broonies seam down to the Barrett
seam;
Carrington Pit has an average stripping ratio of 3.5:1. This pit includes the Broonies, Bayswater,
Piercefield and Vaux seams;
Riverview Pit has an average stripping ratio of 6:1. This pit includes the Glen Munro, Woodlands Hill,
Arrowfield and Bowfield seams; and
Cheshunt Pit has an average stripping ratio of 4:1. This pit includes the Warkworth, Mt Arthur, Piercefield
and Vaux seams.
2.1.1 Current Exploration
During the reporting period, pre-production and exploration drilling was conducted at HVO as part of a
continuing regime to update and refine the geological models with new structural and coal quality data within
the existing mining lease.
A total of 75 open holes, 12 core holes and eight shallow piezometer holes were drilled in 2009 forming a total
of 14,036 metres of open-hole drilling and 1,799 metres of cored-hole drilling. All open holes have been
geophysically logged, with three of the cored holes unable to be geophysically logged to date due to seam
gas exiting the bore holes. This will be completed once the area is safe. Exploration sites have been
progressively rehabilitated in accordance with DII guidelines when equipment has become available.
Four separate exploration drilling campaigns were undertaken in 2009. Initially the focus for drilling was on
completing the West and Wilton Pits drilling programme within CML0004, ML1406 and ML1560, which
commenced in 2008. This drilling was focused on the enhancement of the resource classification of West and
Wilton Pits.
In addition a campaign was conducted in the Riverview West region within ML1634, CL398 and ML1489.
These holes were drilled to support resource knowledge for the new dragline boxcut by investigating the
potential for intrusions and faulting in the area. In total 27 holes were drilled consisting of 26 open holes and
one cored hole. Drill targets were formed from a ground magnetic survey, targeting potential dykes and sills in
the area. The drilling programme did not find any significant dykes or sills. This campaign will be extended in
2010, moving southward in a grid pattern to continue the investigation for possible intrusions affecting the coal
resource.
A groundwater campaign consisting of 12 holes was conducted on Auth435 and EL5418 during 2009. These
holes were drilled as part of a wider groundwater study targeted at developing a more comprehensive
understanding of the permeability of the alluvium across this area.
Nine of the piezometers were constructed using 65mm diameter CL12 pressure pipe with full slotting over the
alluvium, with gravel packing back to the surface from the base of the alluvium. Two of the remaining holes
had 31mm CL18 piezometers installed, set 20m below the base of the alluvium and capped back with one
metre gravel pack, then a 3/8 hole plug to the base of the alluvium (for water level dipping to assess pore
pressures). Hole 4039C was equipped with pore pressure transducers (vibrating wire line piezometer) in the
coal measures, instead of the standard standpipe piezometer arrangement.
The final drilling campaign for the year focused on the Cheshunt pit area within ML1634. Seven holes in total
were drilled, with three open holes and four fully cored holes. One of these cored holes was not completed in
2009 and will carry over into the 2010 exploration period.
AEMR 2009 27