Wambo Coal AEMR 2011-2012 - Peabody Energy

2011-2012 AEMR
Trigger levels for EC however have been derived
from historical monitoring data (using a minimum of
24 data points), where available, in accordance with
the Australia and New Zealand Environment and
Conservation Council Guidelines for Fresh and
Marine Water Quality (ANZECC Guidelines)
(ANZECC, 2000).
Additional surface water monitoring in natural
waterways (except Hunter River) is also undertaken
after rainfall events of more than 20 mm rain in 24
hours (12 am to 12 am). Mine water dams including
Eagles Nest Dam are also included in the surface
water monitoring program. The monthly surface
water quality results for the reporting period are
discussed below.
For the complete monthly surface water quality and
rainfall event sampling results during the reporting
period, please see Appendix 2C.
All surface water samples are monitored for pH and
Electrical Conductivity (EC) on a monthly basis.
Surface water samples from natural waterways
(except Hunter River) and mine water dams
including Eagles Nest Dam, South Dam and Chitter
Dam are also analysed for total dissolved solids
(TDS) and Total Suspended Solid (TSS). In
addition, monitoring of oil and grease concentrations
is also undertaken. Although monitoring of
additional mine water dam sites are not required
under the SWMP, mine water quality is undertaken
by WCPL for salt budgeting and for operational
purposes.
EC and pH are measured in the field while samples
are collected and analysed in the laboratory for
TDS, TSS, oil and grease. Surface water samples
are collected in accordance with AS/NZS
5667.4:1998 – Guidance on sampling from lakes,
natural and man-made and AS/NZS 5667.6:1998 –
Guidance on sampling of rivers and streams.
A number of surface water monitoring sites within
North Wambo Creek, South Wambo Creek and
Stony Creek were dry during the monthly sampling
regime and therefore no water samples could be
obtained.
Surface water monitoring undertaken in accordance
with SWMP indicated that WCPL’s mining
operations had minimal influence on the water
quality of the surrounding natural water courses
during the reporting period.
3.4.2.2 pH Analysis
The recorded pH values from the surface water
monitoring program during the reporting period are
presented graphically and tabulated in Appendix
2C.
The pH levels for the Eagles Nest Dam during the
2010-2011 reporting period were within the pH
criteria and ranged from 8.50 to 9.20. In general,
mine water quality within Eagles Nest Dam is
typically more alkaline than pH values of the
surrounding natural creeks and streams.
The recorded pH for the creeks and streams
surrounding the operation varied depending on
rainfall and volumetric flow.
Wollombi Brook recorded average pH values of
7.54, 7.73, 7.53 and 7.64 at surface water
monitoring sites SW01, SW02, SW03 and SW40
respectively. All monthly recorded pH values were
within the SWMP surface water quality criteria and
consistent with average pH result from the previous
reporting period.
South Wambo Creek and Stony Creek recorded
average pH values of 7.43, 7.63 and 6.88 at surface
water monitoring sites SW06, SW07 and SW08
respectively. All monthly recorded pH values were
within the SWMP surface water quality criteria and
consistent with average pH result from the previous
reporting period.
North Wambo Creek recorded pH average pH
values of 7.53 and 7.67 at surface water monitoring
sites SW05 and SW27 respectively. There were no
results obtainable at SW32 and only one result at
SW04 due to dry conditions within the creek at each
time of sampling during the reporting period. The
one sample obtained at SW04 returned a pH value
pH 8.00 and is within the SWMP surface water
quality criteria.
The recorded pH values monitored at SW39 and the
WRD surface water sites SW43 to SW46 (i.e.
Doctors and Longford Creeks) were within the
surface water quality criteria and consistent with
average pH result from the previous reporting
period.
3.4.2.3 Total Suspended Solids
The recorded TSS values from the surface water
monitoring program during the 2011-2012 reporting
period are graphically presented and tabulated in
Appendix 2C.
Variations in TSS for the Eagles Nest Dam during
the 2011-2012 reporting period were within surface
water quality criteria limits and ranged from