Detecting antimony and arsenic
concentrations in the water column
of Wild Cattle Creek
Final Report
June 2015
Darren Ryder and Sarah Mika
Attachment 9.8 A
ii
Detecting antimony and arsenic concentrations in
the water column of Wild Cattle Creek
Final Report
June 2015
A/Prof. Darren Ryder and Dr Sarah Mika
School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351
This report should be cited as:
Ryder, D. and Mika, S. (2015). Detecting antimony and arsenic concentrations in the water column of
Wild Cattle Creek. Final Report. University of New England, Armidale.
Project contact:
Associate Professor Darren Ryder
School of Environmental and Rural Science
University of New England, Armidale, NSW, 2351
Email: [email protected]
Cover Photo: Wild Cattle Creek (S. Mika, 2013).
iii
Acknowledgements
Clarence Valley Council and Coffs Harbour City Council provided support and financial contributions
to this project.
Seven private landholders supported this project by allowing Bellingen Shire Council to access
waterways through their properties for sampling. Bellingen Shire Council appreciates their
cooperation and local knowledge.
Daan Schiebaan (Manager Sustainable Environment and Waste) and Jane Eales (River and
Biodiversity Projects Officer for Bellingen Shire Council), carried out the field sampling and organized
the transport of water samples to the NATA accredited Environmental Analysis Laboratory at
Southern Cross University, Lismore. Like all event-based sampling programs, it is difficult to manage
resources around unpredictable events and Daan and Jane achieved this.
iv
Table of Contents
Acknowledgements .............................................................................................................. iii
Table of Contents ................................................................................................................. iv
Summary ............................................................................................................................... v
1.0 Introduction ................................................................................................................ 1
1.1 Background ................................................................................................................... 1
1.2 Scope ............................................................................................................................. 1
1.3 Objectives ...................................................................................................................... 1
2.0 Study design and methods .......................................................................................... 2
2.1 Study design .................................................................................................................. 2
2.2 Sampling schedule ......................................................................................................... 7
2.3 Monitoring of contaminants .......................................................................................... 8
2.4 Field methods ................................................................................................................ 9
2.5 Laboratory methods ...................................................................................................... 9
3.0 Results ....................................................................................................................... 10
3.1 Antimony (Sb) .............................................................................................................. 10
3.2 Arsenic (As).................................................................................................................. 11
3.3 Contaminant relationships with discharge ................................................................... 12
3.4 Other heavy metals ..................................................................................................... 12
3.5 Reach-scale export of contaminants ............................................................................ 14
4.0 Summary of main findings, management issues and recommendations .................. 16
4.1 Main findings ............................................................................................................... 16
4.2 Recommendations ....................................................................................................... 17
References .......................................................................................................................... 19
UNE Draft Wild Cattle Creek Anitimony and Arsenic Report 2015
v
Summary
Bellingen Shire Council resolved to undertake independent water quality testing in response to the
proposed Anchor Resources’ antimony mine on Wild Cattle Creek in the Bellingen Shire. The aim of
the monitoring program was to collect baseline information on the concentrations of Antimony (Sb)
and Arsenic (As) originating from the site of the proposed mining operations adjacent to Wild Cattle
Creek.
It is unknown whether contaminants are transported short distances resulting in localized impacts,
or large distances and exported from the Wild Cattle Creek catchment to the broader Clarence
catchment. Therefore, five (5) sample locations were established including sites upstream and
downstream of the impact site on Wild Cattle Creek, one site on White’s Creek within the area
impacted by past mining, and an upstream-downstream pair on the Bielsdown River to mimic the
upstream-downstream pair of sites on Wild Cattle Creek. Net gains/losses between these two points
act as a control and can be compared to the paired ‘impact’ sites on Wild Cattle Creek.
Samples for Arsenic and Antimony were collected from surface water samples at Sites 1 to 4 on six
(6) occasions and Site 5 on four (4) occasions between 2 May 2014 and 13 February 2015. Sample
collection was targeted at different discharge levels to identify if mobilization and transport of
contaminants were linked to rainfall and discharge events. The range of discharge captured during
the study ranged from 16th to 84th percentile flows.
Results
Background concentrations of Sb and As are below the Australian guideline values for
healthy aquatic ecosystems of 9 μg/L and 24 μg/L respectively in the Bielsdown River and in
Wild Cattle Creek upstream of historic and proposed mine inputs.
Export of Sb from White’s Creek was observed on all four sampling occasions. Each
exceedance was more than two orders of magnitude above the guideline value of 9 μg/L
with a mean water column concentration of 400 μg/L. This indicates contamination that may
originate from historic mining.
Export of As from White’s Creek was observed on all four of the sampling occasions. Each
exceedance was more than double the guideline value of 24 μg/L with a mean water column
concentration of 113.8 μg/L. This indicates contamination that may originate from historic
mining.
Export of Sb (≥ guideline value of 9 μg/L) or As (≥ guideline value of 24 μg/L) from Wild Cattle
Creek to the Nymboida River was not observed during the study. This indicates that
contaminants remain within Wild Cattle Creek between its confluence with White’s Creek
and the downstream site on Wild Cattle Creek (Site 4). These contaminants may be
associated with sediment deposits. The potential for these sediments and their associated
contaminants to move downstream into the Nymboida River is unknown.
There was no clear correlation between contaminants and discharge at Site 5 (White’s
Creek) despite the sampling program capturing a range of discharges.
UNE Draft Wild Cattle Creek Anitimony and Arsenic Report 2015
vi
Recommendations
Improve the spatial (additional sites) and temporal (time period, range of discharge, and
replication of percentile flows) design of the monitoring program. This will improve the
understanding of White’s Creek as a point source contributor of contaminants, and improve
understanding of the relationships between concentrations of contaminants in the water
column and discharge.
Include water column (soluble) and suspended and benthic (insoluble) sediments as sources
of contamination.
Include in situ measurements of water column pH, conductivity, dissolved oxygen and
temperature to assist in determining the processes driving peak contaminant mobilization
and transport.
Install a hydrometric gauge in Wild Cattle Creek, with a priority at the downstream reach to
enable quantification of exported contaminant loads to the Nymboida River.
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
1
1.0 Introduction
1.1 Background
Bellingen Shire Council (BSC) resolved on 28 November 2012 to undertake independent water
quality testing in response to the proposed Anchor Resource’s antimony mine (the Bielsdown
Project) on Wild Cattle Creek located 12 km north of Dorrigo, west of the mid north coast New South
Wales. Anchor Resources’ exploration license (EL 6388) includes the historic small-scale antimony
mine on Wild Cattle Creek which was discovered in the late 1800s and mined until the 1970s. The
Bielsdown Project is in the Bellingen Shire but Wild Cattle Creek is a tributary of the Nymboida River
that flows via the Mann River into the Clarence River. As such, any contaminant issue affects three
Local Government Areas (LGAs): Bellingen Shire Council (BSC), Coffs Harbour City Council and the
Clarence Valley Council.
BSC has initiated a monitoring program with the purpose of collecting baseline information on the
concentrations of Antimony (Sb) and Arsenic (As) originating from the site of the Anchor Resources
proposed mining operations adjacent to Wild Cattle Creek. This includes the historic mine inputs.
This program has been supported by Coffs Harbour City Council and the Clarence Valley Council.BSC
has engaged the University of New England (UNE) to design the monitoring program, train BSC staff
in field sample collection procedures, and interpret and report on the data analysed by a NATA
accredited laboratory (Environmental Analysis Laboratory, Southern Cross University, Lismore).
1.2 Scope
This report describes the monitoring program undertaken by BSC as designed and trained by UNE
(Section 2.0). The data as supplied to UNE by the NATA accredited lab (via BSC) are reported in
Section 3.0 and appropriate interpretations are provided along with the relevant data. The main
findings of this monitoring program as well as recommendations for future monitoring are presented
in Section 4.0.
1.3 Objectives
1. Provide information regarding background concentrations of Sb and As in Wild Cattle
Creek including inputs from the historic mine site.
2. Clearly describe the monitoring program undertaken and recommend improvements in
the spatiotemporal resolution for future monitoring.
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
2
2.0 Study design and methods
2.1 Study design
The aim of the monitoring program was to collect baseline information on the concentrations of Sb
and As originating from the site of the proposed mining operations adjacent to Wild Cattle Creek
(Figure 2.1). It is unknown whether these contaminants are transported very short distances
resulting in localized impacts, or large distances and exported from the Wild Cattle Creek catchment
to the Nymboida River and broader Clarence catchment. Thus, the monitoring program was
designed to test both of these spacial scales (Figure 2.2 and Tables 2.1 and 2.2). Sites were located
with the following purpose:
Site 1 is the upstream sampling location on Bielsdown River.
Site 2 is the downstream sampling location on Bielsdown River. Together, Site 1 and
Site 2 act as control sites for naturally occurring longitudinal (upstream-downstream)
changes. This upstream-downstream pair mimics the upstream-downstream pair of
sites on Wild Cattle Creek (Sites 3 and 4), being the same distance apart, comprising
similar geomorphology and land use, and effected by the same climatic conditions. Net
gains/losses between these two points can be compared to the paired ‘impact’ sites on
Wild Cattle Creek.
Site 3 is on Wild Cattle Creek located upstream of lease EL 6388 (that is, upstream of
the confluence of White’s Creek and Wild Cattle Creek).
Site 4 is on Wild Cattle Creek located downstream of the confluence of White’s Creek
and Wild Cattle Creek. The difference in concentrations between Site 3 and Site 4 is the
net gains/losses from all land uses (natural and human) between these two points. The
concentration at Site 4 defines the concentration of contaminants exported from Wild
Cattle Creek into the Nymboida River.
Site 5 is located at the end of White’s Creek and quantifies local-scale runoff to Wild
Cattle Creek. BSC’s River and Biodiversity Projects Officer received consistent feedback
from land holders and other members of the community that it was important to
include this location. Site 5 was then included in the following four sampling occasions
after Council sought advice from UNE.
From the design of the monitoring program, a contaminant impact from the proposed mine is
detected if:
The net gain in contaminants between the upstream site (Site 3) and downstream site
(Site 4) on Wild Cattle Creek are higher than that found between the upstream site
(Site 1) and downstream site (Site 2) on the Bielsdown River.
The concentrations (and net export) of contaminants are higher at the downstream
site on Wild Cattle Creek (Site 4) than the downstream site on the Bielsdown River
(Site 2).
Concentrations of contaminants discharged from White’s Creek (Site 5) are higher
than those recorded for Wild Cattle Creek upstream of the confluence with White’s
Creek (Site 3).
Figure 2.1 The location and extent covered by Anchor Resources’ exploration license EL 6388 (supplied by BSC).
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
4
Figure 2.2 The location of monitoring sites. Site 5 is on White’s Creek.
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
5
TABLE 2.1 Site locations for water column sampling in Wild Cattle and White’s Creeks and the
Bielsdown River.
Site
Number Location and Purpose Easting (m E) Southing (m S)
1
Upstream control site on Bielsdown River: detect
background concentrations of Sb and As input in
nearby river system to demonstrate natural
longitudinal change in the absence of a mine.
470496 6652401
2
Downstream control site on Bielsdown River: detect
background concentrations of Sb and As export in
nearby river system to demonstrate natural
longitudinal change in the absence of a mine.
472204 6655280
3
Upstream control site on Wild Cattle Creek: detect
background concentrations of Sb and As input above
EL 6388 mine lease.
474597 6655746
4
Downstream impact site on Wild Cattle Creek: detect
concentrations of Sb and As exported to the
Nymboida River from EL 6388 mine lease and
upstream.
472727 6656912
5
End-of-system impact site on White’s Creek: detect
export from White’s Creek subcatchment including
historic mine area in Wild Cattle Creek catchment.
473496 6656647
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
6
TABLE 2.2 Photos of the sampled sites.
Site 1: the upstream control site on the Bielsdown River.
Site 2: the downstream control site on the Bielsdown River.
Site 3: the upstream control site on Wild Cattle Creek
Site 4: the downstream impact site on Wild Cattle Creek.
Site 5: impact site on White’s Creek.
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
7
2.2 Sampling schedule
The monitoring program was designed to encompass a range of discharge magnitudes to determine
the contribution of background concentrations of contaminants in the catchment in comparison to
the local mobilization and transport of contaminants from the historic and proposed mine site. As
such, the monitoring program was designed to sample a range of discharges and percentile flows,
and opportunistically sample runoff events to capture the higher discharges. Sampling was therefore
intended to include multiple seasons within a 12-month period (Table 2.3).
Because Wild Cattle Creek and White’s Creek are ungauged, the monitoring program based its
discharge triggers on the Bielsdown River gauge at Charlestead (number 204071; 472165.1 mE,
6655248.1 mS (Zone 56J)) as representative of discharge percentiles in the study river. This gauge
has a catchment area of 131 km2. Rainfall and discharge are shown in Figure 2.3. The first three
months of the study period were characterized by low rainfall and decreasing discharge while the
last six months of the study period were characterized by regular small rainfall and runoff events
(Figure 2.3).
TABLE 2.3 Sampling regime for field collection of water column contaminants in Wild Cattle and
White’s Creeks and the Bielsdown River.
Sampling Event Date Discharge (ML/day) Percentile Flow
1 02/05/2014 113.9 78th
2 01/09/2014 329.8 24th
3 02/10/2014 91.2 84th
4 18/12/2014 91.2 84th
5 16/01/2015 175.2 50th
6 13/02/2015 456.3 16th
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
8
Figure 2.3 Daily rainfall (mm/day) at Dorrigo (BOM gauge number 59144) and discharge (ML/day) of
the Bielsdown River for the study period May 2014 to February 2015 (Office of Water stream gauge
at Charlestead (gauge number 204071)).
2.3 Monitoring of contaminants
Soluble forms of antimony (Sb) as trivalent or pentavalent form, and arsenic (As) are often found
together from geological parent material and are mobilized in water. They can also occur as less
soluble species adsorbed onto clay or soil particles and sediments, and can be transported with flow
as part of the suspended sediment load in rivers.
Concentrations of Sb in surface water in natural systems range from 0.1 to 0.2 μg/L, although they
are rarely measured as part of routine water quality testing. Testing for these via a NATA accredited
laboratory will provide analyses with detection limits of 1 μg/L. The low reliability trigger value for
maintaining healthy aquatic ecosystems is 9 μg/L (ANZECC 2000b, Table 2.4). This value was derived
from ecotoxicological data on five taxonomic groups and should only be used as an indicative interim
working value (ANZECC 2000b). The trigger value for Sb in drinking water is 3 μg/L (NHMRC, NRMMC
2011, Table 2.4). For As, the high reliability trigger value to maintain healthy aquatic ecosystems is
24 μg/L and the trigger value for drinking water is 10 μg/L (Table 2.4). Given that Wild Cattle Creek
flows into the Nymboida River upstream of the town water supplies, it is worth noting drinking
water guidelines as well as the guidelines for maintaining healthy aquatic ecosystems.
0
20
40
60
80
100
120
140
0
500
1000
1500
2000
2500
3000
3500
Apr-14 Jun-14 Jul-14 Sep-14 Nov-14 Dec-14 Feb-15
Dis
char
ge (M
L/d
ay)
Discharge
Sampling occasion
Rainfall (mm/day)
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
9
TABLE 2.4 Trigger values of antimony, arsenic and other metals for drinking water and to maintain
healthy aquatic ecosystems.
Contaminant Australian Drinking Water
Guideline (NHMRC, NRMMC 2011)
Healthy Aquatic Ecosystems
(ANZECC 2000a,b)
Antimony (Sb) Health consideration value
3 μg/L
Low reliability trigger value
9 μg/L
Arsenic (As) Health consideration value
10 μg/L
High reliability trigger value
24 μg/L
Aluminium (Al) Aesthetic consideration value
200 μg/L Health consideration under review
Moderate reliability trigger value
55 μg/L at pH > 6.5
Low reliability trigger value 0.8 μg/L at pH < 6.5
Iron (Fe) Aesthetic consideration value
300 μg/L
Canadian guideline trigger value
300 μg/L
Manganese
(mn)
Aesthetic consideration value
100 μg/L
Moderate reliability trigger value
1700 μg/L
Zinc (Zn) Aesthetic consideration value
3000 μg/L
High reliability trigger value
8 μg/L
2.4 Field methods
Samples were collected at near surface (0.2 to 0.3 m depth) using a hand-held sampling pole to
ensure that samples were collected at least 1.5 m from the river bank edge. Duplicate 1-L PET
bottles were thrice rinsed in sample (river water) and filled. These were immediately placed in an
esky and transported back to Council. They were stored in the dark below 4 °C until transport to the
NATA accredited laboratory (Environmental Analysis Laboratory, Southern Cross University,
Lismore).
2.5 Laboratory methods
Samples were filtered in the laboratory (0.45 μg GF/C glass fibre filter paper. Samples were then
stabilized with nitric acid (HNO3) for the analysis of cations. Soluble basic cations (manganese Mn2+)
and acidic cations (aluminium Al3+ and Iron Fe2+) were analsyed by inductively coupled plasma
optical emission spectroscopy (ICP-OES) and metals including antimony (Sb) and arsenic (As) were
analysed by inductively coupled plasma mass spectrometry (ICP-MS) as per APHA (2012) “Standard
Methods for the Examination of Water and Wastewater”.
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
10
3.0 Results
3.1 Antimony (Sb)
The low reliability trigger value for antimony (Sb) to maintain healthy aquatic ecosystems is 9 μg/L
(Table 2.4). The detection limit of the NATA accredited laboratory is 1 μg/L. Concentrations of Sb in
the water column were below the detection limit (<1 μg/L) on all sampling occasions in the
Bielsdown River (Sites 1 and 2), and the upstream site on Wild Cattle Creek (Site 3). Sb was detected
at a concentration of 1 μg/L at the downstream site on Wild Cattle Creek (Site 4) on one sampling
occasion during low flows (02 October 2014).
In contrast, concentrations of Sb in the water column of White’s Creek (Site 5) exceeded the
guideline threshold on all four sampling occasions (Figure 3.1). Each exceedance was greater than
two orders of magnitude of the guideline threshold (mean exceedance of 400 μg/L). The highest
water column concentration of 543.5 μg/L was observed one month after the highest rainfall and
runoff event in August 2014 (Figure 2.2). This runoff event was preceded by a 3-month period of low
rainfall and discharge (Figure 2.3). Site 5 was not sampled in August 2014 when the largest rainfall
and runoff event occurred. However, there was very little rainfall and falling discharge between the
second and third sampling events (Figure 2.3), suggesting that the peak concentration of Sb
recorded for the fourth sampling event was residual from the August 2014 runoff event.
Figure 3.1 Mean concentrations of antimony (Sb, μg/L) in the water columns of the Bielsdown River (Sites 1 and 2), Wild Cattle Creek (Sites 3 and 4) and White’s Creek (Site 5). Concentrations at Sites 1 to 4 were at or below 1 μg/L on all sampling occasions. Percentile flow (blue line) is estimated from the Bielsdown River (Office of Water gauge 204071). The red line is the low reliability trigger value for maintaining healthy aquatic ecosystems.
0
10
20
30
40
50
60
70
80
90
100
0
50
100
150
200
250
300
350
400
450
500
550
600
Per
cen
tile
flo
w
Co
nce
ntr
atio
ns
of
An
tim
on
y (μ
g/L)
Site 1
Site 2
Site 3
Site 4
Site 5
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
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3.2 Arsenic (As)
The high reliability trigger value for arsenic (As) to maintain healthy aquatic ecosystems is 24 μg/L
(Table 2.4). The detection limit of the NATA accredited laboratory is 1 μg/L. Concentrations of As in
the water column were below the detection limit (<1 μg/L) on all sampling occasions in the
Bielsdown River (Sites 1 and 2). The background water column concentration in Wild Cattle Creek
(Site 3) only exceeded the detection limit on one sampling occasion with a concentration of 1 μg/L in
December 2014. At the downstream site on Wild Cattle Creek (Site 4), water column concentrations
of 1 μg/L were consistently observed (Figure 3.2).
In contrast, concentrations of As in the water column of White’s Creek (Site 5) exceeded the
guideline threshold on all four sampling occasions (Figure 3.2). Each exceedance was almost five
times the guideline value (mean exceedance of 113.8 μg/L). The pattern of exceedances differed
slightly from that of Sb. The highest concentration of As in the water column of White’s Creek was
observed in January 2015, after a series of several small rainfall and runoff events (Figure 2.3).
Figure 3.2 Mean concentrations of arsenic (As, μg/L) in the water columns of the Bielsdown River (Sites 1 and 2), Wild Cattle Creek (Sites 3 and 4) and White’s Creek (Site 5). Concentrations at Sites 1 to 4 were at or below 1 μg/L on all sampling occasions. Percentile flow (blue line) is estimated from the Bielsdown River (Office of Water gauge 204071). The red line is the high reliability trigger value for maintaining healthy aquatic ecosystems.
0
10
20
30
40
50
60
70
80
90
100
0
50
100
150
200
250
300
350
400
450
500
550
600
Per
cen
tile
flo
w
Co
nce
ntr
atio
ns
of
Ars
enic
(μ
g/L)
Site 1
Site 2
Site 3
Site 4
Site 5
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
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3.3 Contaminant relationships with discharge
Although the event-based monitoring regime sampled flows ranging from the 16th to 84th percentile
flows, four sampling events were not sufficient to determine correlations between antimony or
arsenic concentrations in the water column of White’s Creek (Site 5) and discharge (Figure 3.3).
Figure 3.3 Mean concentrations of antimony and arsenic in the water column of White’s Creek (Site 5) in relation to percentile flow as estimated from the Bielsdown River gauge (Office of Water gauge 204071 used as a surrogate for Wild Cattle Creek).
3.4 Other heavy metals
The range and means of concentrations of other heavy metals analysed by the NATA accredited
laboratory as part of its analytical package are given in Table 3.1. Selenium (never observed above
the detection limit of 2 μg/L), mercury (never observed above the detection limit of 0.5 μg/L), zinc
and manganese did not exceed guideline values at any site on any sampling occasion. Water column
concentrations of iron exceeded aesthetic guideline values at both sites on the Bielsdown River
(Sites 1 and 2), and both sites on Wild Cattle Creek (Sites 3 and 4).
0
100
200
300
400
500
600
0 10 20 30 40 50 60 70 80 90 100
Co
nce
ntr
ati
on
(μg/
L)
Percentile flow
Antimony Concentration
Antimony Threshold
Arsenic Concentration
Arsenic Threshold
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
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TABLE 3.1 Range and means of concentrations (μg/L) of heavy metals in the water columns of Wild
Cattle and White’s Creeks and the Bielsdown River.
Metal Site 1 Site 2 Site 3 Site 4 Site 5
Aluminium 50-226
(121)
41-251
(115)
85-412
(209)
71-343
(186)
18-38
(26)
Iron 269-703
(525)
232-572
(452)
168-490
(305)
166-436
(279)
55-225
(142)
Manganese 6-23
(11)
5-14
(8)
3-13
(7)
3-14
(8)
32-345
(131)
Zinc 0-3
(1)
0-5
(1)
0-6
(2)
0-5
(2)
2-9
(4)
Without simultaneous measurement of water column pH, relationships between acidic or alkaline
conditions and aluminium mobilisation cannot be determined. In the 2012-2013 Ecohealth program
(Ryder et al. 2014), water column pH ranged from 7.35 to 9.33 in the Bielsdown River (mean = 8.12)
and 7.58 to 9.24 in Wild Cattle Creek (mean = 8.30). This suggests that the moderate reliability
trigger value for these systems is likely to be 55 μg/L for pH > 6.5, with a deleterious trigger of
100 μg/L (Table 2.4).
Aluminium (Al) concentrations in the water column exceeded deleterious levels of 100 μg/L on two
sampling occasions in both sites on the Bielsdown River (May 2014 and September 2014, Figure 3.4).
Concentrations of Al in Wild Cattle Creek exceeded 100 μg/L at both sites on four sampling occasions
(May, September and December 2014, and February 2015), with higher concentrations commonly
observed at the upstream site (Site 3) than downstream site (Site 4, Figure 3.4). Al concentrations
never exceeded the moderate reliablility trigger value of 55 μg/L for pH > 6.5 in White’s Creek
(Figure 3.4).
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
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Figure 3.4 Mean concentrations of aluminium (Al, μg/L) in the water columns of the Bielsdown River (Sites 1 and 2), Wild Cattle Creek (Sites 3 and 4) and White’s Creek (Site 5). Percentile flow (blue line) is estimated from the Bielsdown River (Office of Water gauge 204071). The red line is the moderate reliability trigger value of 55 μg/L for pH > 6.5 for maintaining healthy aquatic ecosystems.
3.5 Reach-scale export of contaminants
The monitoring program was designed to test the impact of the historic and proposed mine site on
contaminants in the water column through the following analyses:
Site 2 – Site 1: the background longitudinal patterns (upstream-downstream) of
contaminants in the water column of the Bielsdown River (control).
Site 4 – Site 3: the background longitudinal patterns (upstream-downstream) of Wild
Cattle Creek (impact).
Site 4 – Site 2: determines whether there are higher concentrations of contaminants
being exported from Wild Cattle Creek than the Bielsdown River.
Site 5 – Site 3: determines whether the concentrations of contaminants discharging
from White’s Creek (impact) are higher than background concentrations in Wild Cattle
Creek upstream of the confluence (control).
0
10
20
30
40
50
60
70
80
90
100
0
50
100
150
200
250
300
350
400
450
500
550
600
Pe
rce
nti
le f
low
Co
nce
ntr
atio
ns
of
Alu
min
imu
m (
μg/
L)
Site 1
Site 2
Site 3
Site 4
Site 5
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
15
Because aluminium was the only contaminant consistently found outside of White’s Creek (Site 5),
the reach-scale analyses can only be performed for aluminium. There was a consistent longitudinal
loss in aluminium concentrations between the upstream and downstream control sites in the
Bielsdown River, with the only net gain in aluminium occurring in May 2014 (Site 2 – Site 1, Figure
3.5). Similarly, there was a consistent longitudinal loss in aluminium concentrations between the
upstream and downstream sites on Wild Cattle Creek, with the only net gain in aluminium occurring
in February 2015 (Site 4 – Site 3, Figure 3.5).
Wild Cattle Creek exported higher concentrations of aluminium than the Bielsdown River control on
all sampling occasions, with the largest difference coinciding with the largest runoff event (Site 4 –
Site 2, Figure 3.5). This may be partially explained by the four occasions that White’s Creek (Site 5)
was sampled, where White’s Creek had higher aluminium concentrations than the background
concentrations at the upstream site on Wild Cattle Creek (Site 5 – Site 3, Figure 3.5). However,
higher concentrations of aluminium were consistently observed in the water column of upstream
Wild Cattle Creek than upstream Bielsdown River (Site 3 – Site 1, Figure 3.5).
Figure 3.5 Net gains (positive values) or losses (negative values) of water column concentrations of
aluminium (Al, µg/L).
-200
-150
-100
-50
0
50
100
150
200
250
300
Ne
t ga
in (p
osi
tive
) or
loss
(ne
gati
ve) Site 2 - Site 1
Site 4 - Site 3Site 3 - Site 1Site 4 - Site 2Site 5 - Site 3
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
16
4.0 Summary of main findings, management issues and
recommendations
4.1 Main findings
Antimony
Background concentrations of Sb are below the low reliability trigger value of 9 μg/L in the
Bielsdown River and in Wild Cattle Creek upstream of historic and proposed mine inputs.
Export of Sb from White’s Creek was observed on all four sampling occasions (October and
December 2014, and January and February 2015). Each exceedance was more than two
orders of magnitude above the low reliability trigger value of 9 μg/L with a mean water
column concentration of 400 μg/L. This indicates contamination that may originate from
historic mining.
Export of Sb from Wild Cattle Creek to the Nymboida River was observed once during the
study (02 October 2014), but was below the trigger values for maintaining healthy
ecosystems and Australian drinking water standards (at 1 μg/L). This is despite significant
inputs from White’s Creek.
Arsenic
Background concentrations of As are below the high reliability trigger value of 24 μg/L in the
Bielsdown River and Wild Cattle Creek (only once exceeding the detection limit of 1 μg/L at
the downstream site on Wild Cattle Creek).
Export of As from White’s Creek was observed on all four sampling occasions (similar to Sb).
Each exceedance was approximately five times the guideline value of 24 μg/L with a mean
water column concentration of 113.8 μg/L. This indicates contamination that may originate
from historic mining.
No export of As from Wild Cattle Creek to the Nymboida River was observed during the
study, despite significant inputs from White’s Creek.
Contaminant relationships with discharge
There was no clear correlation between contaminants and discharge at Site 5 (White’s
Creek) despite the sampling program capturing a range of discharges.
Aluminium
Background concentrations of Al in the Bielsdown River exceeded the moderate reliability
trigger value of 55 μg/L for pH > 6.5 and the deleterious level of 100 μg/L on two sampling
occasions (May and September 2014).
Background concentrations of Al in Wild Cattle Creek exceeded the deleterious level of
100 μg/L on four sampling occasions (May, September and December 2014, and February
2015), with higher concentrations consistently observed at the upstream site.
Water column concentrations of Al in White’s Creek never exceeded the moderate reliability
trigger value of 55 μg/L for pH > 6.5.
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4.2 Recommendations
Spatial extent of monitoring
Two additional sites located on Wild Cattle Creek immediately upstream and downstream of
its confluence with White’s Creek should be added to the monitoring program. The purpose
of these sites is to provide an immediate control site upstream and an immediate impact site
downstream of historic and proposed mine inputs to improve analyses of White’s Creek as a
point source contaminant to Wild Cattle Creek.
If resources only permit one extra site to be included, it should be the site immediately
downstream of the confluence of White’s Creek and Wild Cattle Creek. Currently, Sb and As
are exported from White’s Creek to Wild Cattle Creek at concentrations exceeding guidelines
for maintaining healthy aquatic ecosystems. However, Wild Cattle Creek was not observed
to export Sb and As to the Nymboida River, suggesting these contaminants may be stored
within Wild Cattle Creek between its confluences with White’s Creek and the Nymboida
River.
If resources permit, additional sites should be located on Wild Cattle Creek between the
confluence with White’s Creek and the current Site 4 (Table 2.1). The purpose of these sites
would be to locate potential contaminant slugs accumulating in Wild Cattle Creek. This
improvement to the spatial resolution of sampling would benefit from the addition of
sediment sampling to see if contaminants are being adsorbed onto fine-grained sediments in
depositional areas (see Additional Variables below).
Temporal extent of monitoring
This study comprised six sampling events with White’s Creek (Site 5) sampled four times.
Although these six sampling occasions covered a large range of flows (16th to 84th percentile
flows), it is clear that the temporal intensity of sampling needs to be increased to assess
relationships between contaminants and discharge. Additional sampling events should be
included as the flow events occur.
Sampling events should target flows greater than 200 ML/day to increase the rigor of
relationships between contaminants and discharge.
Sampling events should also target low flows to examine potential mobilization of
contamiants into the water column during low oxygen conditions where stream sediments
become hypoxic or anoxic (see additional variables).
Additional variables
This study comprised water column samples only. To increase the rigor of assessments of
potential contamination, sediment samples should be taken simultaneously to water column
samples. These sediment samples should focus on fine-grained sediments (silts and clays) in
depositional areas where adsorbed contaminants potentially accumulate.
The addition of sediment samples (insoluble contaminants) with water column suspended
(insoluble contaminants) and (soluble contaminants) samples will enable investigation of the
relevance to contaminant mobilisation of the timing, frequency and duration of low flow and
high flow events, as well their magnitude.
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Including in situ measurements of water column pH, conductivity, dissolved oxygen and
temperature, particularly pH and dissolved oxygen will assist in determining the processes
driving peak contaminant mobilization and transport. These variables are relatively
inexpensive to measure using a commercial water quality probe. Alternatively, BSC may
consider installing a datalogger at the end-of-system site at White’s Creek (Site 5) to
measure water level, pH, temperature and dissolved oxygen. This would provide greater
temporal resolution of the processes commonly driving contaminant mobilization and allow
BSC to time sampling events when they know exceedances are occurring.
The load of contaminants retained or transported through Wild Cattle Creek into the
Clarence catchment is important to quantify. This current study relies on a surrogate gauge
in the Bielsdown River for discharge. It is strongly recommended that a hydrometric gauge
be installed on Wild Cattle Creek, with a priority at the downstream reach to enable
exported loads to be quantified.
UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015
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References
American Public Health Association (APHA). (2012). Standard Methods for the Examination of Water
and Wastewater. 22nd Edition, Eds: E.W. Rice, R.B. Baird, A.D. Easton and L.S. Clesceri. APHA,
Washington D.C.
Australian and New Zealand Environment and Conservation Council (ANZECC). (2000a). Volume 1.
Australian and New Zealand Guidelines for Fresh and Marine Water Quality: The Guidelines.
http://www.environment.gov.au/water/quality/publications/australian-and-new-zealand-
guidelines-fresh-marine-water-quality-volume-1.
Australian and New Zealand Environment and Conservation Council (ANZECC). (2000b). Volume 2.
Australian and New Zealand Guidelines for Fresh and Marine Water Quality: Aquatic Ecosystems –
Rationale and Background Information. http://www.environment.gov.au/water/quality/
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National Health and Medical Research Council (NHMRC) and Natural Resource Management
Ministerial Council (NRMMC). (2011). Australian Drinking Water Guidelines Paper 6 National Water
Quality Management Strategy. National Health and Medical Research Council, National Resource
Management Ministerial Council, Commonwealth of Australia, Canberra.
Ryder, D., Mika, S., Richardson M., Burns, A., Veal, R., Schmidt, J. and Osborne, M. (2014). Clarence
Catchment Ecohealth Project: Assessment of River and Estuarine Condition 2014. Final Technical
Report to the Clarency Valley Council. University of New England, Armidale.