Wambo Coal AEMR 2011-2012 - Peabody Energy

2011-2012 AEMR
United Collieries Piezometers
The United Collieries network of piezometers
displayed largely static water levels for most of the
reporting period. All piezometers except P1, P12
and P13 were not sampled in February due to
access issues at the time. P5 and P18 both
periodically exceeded maximum depth to water
value. P11 has remained dry throughout this and
the previous reporting period. The December 2011
result for P6 was outside the minimum depth to
water criteria.
The remaining sites remained within their respective
depth to water criteria for the 2011-2012 reporting
period. Significant rainfall events during the middle
of the reporting period were likely influencing
increases in water levels at the corresponding time.
3.5.2.2 pH
The results for pH analysis of the groundwater
monitoring network are provided graphically and
tabulated in Appendix 2D.
The pH values for groundwater in wells GW02,
GW09 and GW11 remained within the GWMP
trigger levels during the reporting period with pH
values averaging from 6.88 to 7.89.
GW08 had a single value slightly outside of
minimum criteria in 2011-2012. The groundwater
wells GW02 and GW11 located on the Brosi’s
property are subject to the ANZECC criteria for
“Raw Waters for drinking purposes subject to
coarse screening”. GW02 was just outside of the
pH range of 6.5-8.5 in August 2011. This value is
similar to those recorded by the 100 series
piezometers in the ‘Wambo Creek Alluvium’. GW11
was within the ANZECC pH range of 6.5-8.5 for the
whole monitoring period.
All pH values recorded during the 2011-2012
reporting period for the 100, 200 and 300 series
remained within the pH trigger limits except for one
value recorded at P315. The value of pH3.7
obtained at P315 in February 2012 was not able to
be verified with further sampling due to accessibility
issues. Ongoing monitoring in the next reporting
period will identify if the water quality is returning
back within the water quality criteria.
3.5.2.3 Electrical Conductivity
The results for EC analysis of the groundwater
monitoring network are provided graphically and
tabulated in Appendix 2D.
Groundwater wells GW08 and GW11 remained for
the most part within their respective GWMP trigger
levels for EC during the reporting period. Low
rainfall in July and August 2011 may have
contributed to the elevated EC at GW02 in August
2011. The average EC for GW02 and GW11 was
574 uS/cm and 417 uS/cm respectively. The
recorded EC at GW09 has remained below the
minimum EC criterion of 1500S/cm since
December 2010. Average EC of GW09 for this
reporting period was 471 uS/cm.
The measured EC in the 100 and 200 piezometer
series remained relatively static during the reporting
period. The measured EC for P114 was the only
100 or 200 series piezometer with EC values above
the groundwater quality criteria for the reporting
period. Further monitoring demonstrated EC
concentrations for P114 began returning to previous
concentrations. The EC results recorded in the
2011-2012 reporting period for both the 100 and
200 piezometer series were consistent with EC
results recorded in the 2010-2011 period.
The measured EC in the 300 series piezometers
during the reporting period showed some
fluctuations. All the measured EC values at P301
fell below their minimum EC trigger level of
8500S/cm with an annual average of 2788S/cm
and a minimum EC valve of 2130S/cm for
February 2012. The April 2012 sampling event at
P301 showed a periodic increase in EC to
4,040uS/cm. The EC results recorded in the 2010-
2011 reporting period for the 300 piezometer series
were generally consistent with EC results recorded
in the 2009-2010 period.
Most of the United Collieries monitored piezometers
generally remained within their respective EC
criteria levels during the reporting period. The
remainder of United’s piezometers returned EC
values well below their respective minimum EC
trigger levels. The EC results recorded in the 2011-
2012 reporting period for the United Collieries
piezometers were consistent with EC results
recorded in the 2010-2011 period.
All pH values recorded during the 2011-2012
reporting period for the United Collieries
piezometers remained within their respective pH
trigger limits as listed in Table 3.2.
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