HVO 2009 Annual Environmental Management Report - Final

Coal & Allied – Hunter Valley Operations
West Pit Groundwater
West Pit bores were commissioned for sampling in August 2008. These sites are sampled quarterly with SWL
levels taken on a monthly basis subject to safe access. Interpretation of West Pit groundwater has been
based on sites; NPZ1, NPZ2, NPZ3, NPZ4 and NPZ5. Monitoring results for 2009 are shown in Table 41 and
Figure 66 to Figure 68.
Table 41: Groundwater Results from West Pit Groundwater’s for 2009
Location
EC (S/cm)
Average Min Max Average Min Max
pH
NPZ1 6,350 6,080 6,530 7.7 7.4 8.0
NPZ2 18,295 17,440 19,400 7.5 7.4 7.7
NPZ3 12,898 12,290 13,800 8.7 8.5 9.0
NPZ4 7,615 7,250 8,120 7.5 7.4 7.6
NPZ5 8,258 8,030 8,400 7.5 7.3 7.7
Groundwater Monitoring pH Results for West Pit Piezometers
Observed pH trends across the most sites were stable moving within a narrow range 7.0 and 9.0 pH units.
NPZ3 moved within a narrow range between 8.5 and 9 pH units. These bores appeared to have stabilised
since the last reporting period.
9.5
West Pit Groundwater pH Trends
9
8.5
pH(pHunits)
8
7.5
7
Jan 09
Feb 09
Mar 09
Apr 09
May 09
Jun 09
Jul 09
Date
Aug 09
Sep 09
Oct 09
Nov 09
Dec 09
NPZ1 NPZ2 NPZ3 NPZ4 NPZ5
Figure 66: West Pit Groundwater pH Trends
Groundwater Monitoring EC Results for West Pit Piezometers
The EC trends across the sites where consistent throughout 2009 indicating that the bores have stabilised.
Site NPZ2 consistently recorded the highest EC across site at an average of 18,295μS/cm, associated with
high salinity waters in the West Pit Barret coal seam. The lowest recorded EC was consistently present at
NPZ1 at an average of 6,350μS/cm.
AEMR 2009 115