5.2.2.9
Subterranean Invertebrate Fauna Assessment Results
Figure 5‐30 shows all records of subterranean fauna collected in the Mid‐West and Geraldton areas
compiled from previous Ecologia surveys, the WA Museum database, DEC reports and other
published journal articles.
Subterranean fauna have been found in 16 of the 30 land systems occurring within the Study Area
(Table 5‐22). Subterranean fauna have also been found in 12 additional land systems within the Mid‐
West that do not occur within the Study Area (refer to Appendix 2c). The Mileura system harboured
the largest subterranean fauna records (146 records), followed by Cunyu (44 records), both land
systems of which are within the Study Area.
Subterranean fauna were also recorded from three of the ten soil landscape systems that occur
within the Study Area (Table 5‐22). Of these ten soil landscape systems, the Tamala soil landscape
system had the most records, with four records of stygofauna and four records of caves where
subterranean fauna have been collected. Subterranean fauna were also found in four additional soil
landscape systems within the Geraldton area that do not occur within the Study Area (refer to
Appendix 2c). However, most of these records were from within caves where subterranean fauna
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had been collected but did not include the accurate number of species as the numbers included
cave‐dwelling fauna that is not obligate troglofauna or stygofauna.
Most of the records reviewed for both the land systems and soil landscape systems were of
stygofauna, with 270 records compared to 43 troglofauna records. Of these, 219 stygofauna records
and 40 troglofauna records were from land systems/soil landscape systems occurring within the
Study Area. Nine records referred to caves where subterranean fauna had been collected and
possibly consisted of both troglofauna and stygofauna (Table 5‐22).
Table 5‐22 Subterranean fauna records from land and soil landscape systems within Study Area
Description
Records of
Stygofauna
Records of
Troglofauna
Land System
Challenge
Gently sloping gritty and sandy-surfaced plains with granite outcrops and minor
breakaways, supporting mulga and some halophytic shrublands.
2
Cunyu
Calcreted drainage zones on hardpan; alluvial plains with raised calcrete platforms
dissected by major flow zones and channels, supporting variable mostly non-halophytic
shrublands and calcareous shrubby grasslands.
36
8
Gabanintha
Ridges, hills and footslopes of various metamorphosed volcanic rocks (greenstones),
supporting sparse acacia and other mainly non-halophytic shrublands.
12
Joseph
Undulating yellow sandplain system supporting dense mixed shrubland with patchy
mallees
1
Jundee
Hardpan wash plains with variable dark gravely mantling and weakly groved
vegetation; minor sandy banks; supports scattered mulga shrublands
1
Kalli
Elevated, gently undulating red sandplains edged by stripped surfaces on laterite and
granite; tall acacia shrublands and understorey of wanderrie grasses (and spinifex
locally).
5
Mileura
Saline and non-saline calcreted river plains, with clayey flood plains interrupted by
raised calcrete platforms supporting diverse and very variable tall shrublands, mixed
halophytic shrublands and shrubby grasslands.
131
15
Nerramyne
Undulating plains of sandy-surfaced laterite and weathered granite with low remnant
plateaux, breakaways and rises supporting acacia shrublands.
1
Pindar
Loamy plains surrounded by sandplain supporting York gum woodlands.
1
Sherwood
Extensive, gently sloping stony and sandy plains on granite and gneiss below saline
footslopes of lateritised breakaways and outcrops of weathered rock; mainly supports
scattered mulga shrublands with understorey non-halophytic and halophytic shrubs.
2
Tallering
Prominent ridges of banded ironstone, dolerite and sedimentary rocks supporting
bowgada and other Acacia shrublands.
2
2
Tindalarra
Very gently inclined hardpan wash plains with narrow drainage lines and fairly saline
narrow tributary drainage floors; supports tall mixed acacia shrublands with patchy
wanderrie banks and narrow tracts of snakewood and bluebush; a major wash system
in the Greenough River catchment
11
Violet
Gently undulating gravely plains on greenstone, laterite and hardpan, with low stony
rises and minor saline plains; supports mulga and bowgada-dominate shrublands, with
dense mulga groves and patchy halophytic shrublands
2
Weld
Rugged ranges and ridges of mainly Archaean metamorphosed sedimentary rocks;
supports acacia shrublands; major system of the Weld Range and Jack Hills.
8
Yandil
Flat hardpan wash plains, extensively uniform and carrying light to moderate mantles of
small pebbles and gravels; occasional wanderrie banks and groves; supports mulga
shrublands, but widely degraded.
3
Yanganoo
Almost flat hardpanwash plains, with or without small wanderrie banks and showing
variable development of weak groving; supports mulga shrublands; the most extensive
system in survey area.
4
Soil Landscape System
Dartmoor
Level to gently undulating plain and weakly dissected long slopes, much as a relic
drainage network
1
7
Northampton
Narrow valleys with gently undulating to rolling rises and low hills with an integrated
drainage pattern. Rocky outcrops common on hillcrests with long gentle slopes and
alluvial terraces associated with local rivers. Forms much of drainage basin of
Chapman, Bowers, Oakajee and Buller Rivers
1
Tamala
Low hills parallel to the coast, extending 4 km inland and 3 to 7 km wide. Western units
are moderately inclined to steep, sometimes cliffed to the sea. South of Geraldton they
form low hills with relic dune lobes and some limestone outcrop. No drainage lines
except on lithified western faces. Units have been breached by rivers and streams at
several locations
4
4 caves where
species been
collected
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5.2.2.10
Suitability of groundwater for stygofauna
Aquaterra installed eight monitoring bores within the Study Area to measure water chemistry and
quality (Aquaterra 2009b). Based on the pH levels and conductivity of the groundwater in each
monitoring bore, predictions have been made as to whether the groundwater within the bores may
provide suitable habitat for stygofauna. All bores were within 100 km of existing records of
subterranean fauna and most bores showed pH and conductivity (EC) levels suitable for stygofauna.
Table 5‐23 summarises the water chemistry results of the eight monitoring bores.
Table 5‐23 Monitoring bores that may contain subterranean fauna
Bore ID
Field EC
(mS/cm)
pH
Likelihood of
stygofauna
Reasons
52_MB1
7.9
8.2
Possible
pH & conductivity are within suitable parameters
102_MB1 12.2
4.2 Unlikely
Conductivity
is
within suitable parameters, however pH is
comparatively low
249_MB1
2.5
8.5
Possible
pH & conductivity are within suitable parameters
300_MB1 >39
7.0 Possible
Conductivity
is high, however pH is suitable
368_MB1
2.9
-
Unable to comment
Insufficient data
400_MB1
-
-
Unable to comment
Insufficient data
400_MB2
-
-
Unable to comment
Insufficient data
408_MB1
3.5
7.4
Possible
pH & conductivity are within suitable parameters
Geraldton
Geraldton
OakajeeOakajee
MeekatharraMeekatharra
KalbarriKalbarri
Mount MagnetMount Magnet
MullewaMullewa
Jack HillsJack Hills
Weld RangeWeld Range
Figure No:
CAD Resources File No:
Drawn:
CAD Resources
02
0
Scale
MGA94 (Zone 50)
6900000mN
200000mE
40km
7000000mN
7100000mN
6900000mN
7000000mN
7100000mN
300000mE
400000mE
500000mE
600000mE
700000mE
200000mE
300000mE
400000mE
500000mE
600000mE
700000mE
g1660_Pub_PER_R_F005.dgn
LEGEND
Existing Rail Network
Major Road
Watercourse
Coastline
Topography
Notes:
Troglofauna and Stygofauna supplied by Ecologia Environment
Groundwater Bores supplied by Aquaterra
Troglofauna
Stygofauna
Project Area
Groundwater
Investigation Bore
Recorded Subterranean
Invertebrate Fauna
Figure 5-30 Location of recorded subterranean invertebrate fauna
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5.2.3
Surface Hydrology
5.2.3.1
Surface Hydrology Assessment
A desk‐based review of surface hydrology was completed in 2009 by Aquaterra (2009a; Appendix 3),
which involved the following:
reviewing available aerial photography, published reports and data on surface water
resources, and reconciling this information with rail alignment options; and
defining surface water drainage patterns and characteristics within the Study Area.
5.2.3.2
Surface Hydrology Assessment Results
Surface hydrology within the Study Area can be categorised as follows:
external – drainage from catchments discharging to the Indian Ocean via rivers or other
watercourses; and
internal – drainage that, under normal flow conditions, discharges to the inland regional
system of salt lakes.
External drainage is more typical of the western sector of the Study Area, while internal drainage is
more typical in the east. For example, between Meekatharra and Wiluna, a system of generally
north south drainage lines, creeks and other watercourses drain surface flows into numerous salt
lakes (Aquaterra, 2009a, Appendix 3) (Figure 5‐31).
The northern portion of the Study Area is characterised by an ephemeral drainage pattern within the
Murchison River catchment. This comprises an extensive drainage network covering an area of
about 82,000 km
2
(Figure 5‐31). The Murchison River discharges into the ocean at Kalbarri, 110 km
north of Oakajee. Water quality during flooding is fresh, but turbid, while low flows are brackish and
saline (Aquaterra, 2009a).
The Study Area extends over a number of episodic rivers and creeks including the Chapman River,
Greenough River, the Bangemall Creek, the Sanford River, and Ilkabiddy Creek, which flow only in
direct response to rainfall events. Flows in the smaller stream channels are typically of short
duration, and cease soon after the rainfall passes. In the larger river channels draining the more
extensive catchments, runoff can persist for several weeks and possibly months following major
rainfall events such as those resulting from tropical cyclones.
The catchments within the Study Area have been considerably modified by pastoralism, damming of
watercourses and mining practices (EPA, 2007c).
Figure 5-31 Overview of surface water drainage within the Study Area
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5.2.3.3
Significant Surface Hydrology Characteristics of the Study Area
Flood Events
1
The most intense rainfall and flooding events within the Study Area result from tropical cyclones.
Flooding is therefore sporadic and usually occurs in the cyclone season (summer). Several significant
flood events have occurred in recent years, including Cyclones Clare and Dominic in January 2009.
Widespread storms and flooding were experienced in the region resulting in the closure of several
roads, regional airstrips and the flooding of Yuin Station and some houses in Meekatharra. It is
estimated that these two events had an ARI in excess of 1000 years (Aquaterra, 2009a). The
magnitude of the consequent flooding was therefore also extremely rare.
Sheetflow
Overland flows occurring in areas where there are no defined channels, resulting in widespread
flooding of uniform depth, known as sheetflow. Sheetflow zones occur at various locations across the
Study Area with some vegetation communities, particularly Mulga (Acacia aneura) woodland, being
dependent on seepage from these surface water flows (Figure 5‐16) (ANRA, 2009). Mulga woodlands
are common throughout the northern sectors of the Study Area.
Defined areas of sheetflow were not able to be determined without more detailed site
investigations. These investigations will be conducted prior to construction to determine culvert
requirements (refer to Section 7.5).
5.2.4
Groundwater
Initial desktop assessments and field groundwater investigations of water demand, potential yield
and water quality available for construction purposes were undertaken in 2009 (Aquaterra 2010b;
Appendix 4). The objective of the desktop assessment was to identify water requirements during
Proposal construction and operation, and assess groundwater availability for this demand.
The groundwater potential along most of the Proposal Area in the interior zone of the Mid‐West is
low to moderate. Establishment of successful production bores with acceptable yields (1‐3 L/s)
within the Study Area will demand significant investment in exploration drilling, requiring access to
as many exploration targets as possible. The limited drilling programme conducted during Phase 1 in
2009 has shown approximately a 50% success rate for bores delivering above 3 L/s, but the prospect
exists that local supplies may not be found along some portions. In addition, a limited number of
targets exist within the Study Area and there is substantial risk that exploration holes will not be
successful in some areas. Therefore, groundwater investigations will also concentrate on developing
water supply borefields in areas of moderate to high groundwater yield potential, within
approximately 50 km of the Proposal Area (Aquaterra, 2010c).
5.2.4.1
Regional Hydrogeology
From a hydrogeological perspective, the Study Area may be divided into two broad zones – coastal
and interior, which includes the Northampton Block, the northern extent of the Perth Block, and the
Murchison Basin (Figure 5‐32).
In the coastal zone aquifers have been identified in weathered Proterozoic basement, consolidated
sediment and coastal limestone. The Tamala marine limestone and associated alluvial deposits are
highly permeable and have the potential to form significant aquifers. Groundwater in the coastal
1
A 100 year ARI flood is a definition of a flood that has a 1% chance of occurring in any given year. Therefore an ARI in excess of 1000 years
refers to a flood that has a 0.1% chance of occurring in any given year (BoM, 2001).
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zone is mainly brackish ranging from 1,000‐3,000 mg/L of Total Dissolved Solids (TDS). Although
bores in the Tamala limestones offer supply potential, this aquifer system may already be over‐
allocated, this may constrain or complicate licensing approvals required to abstract this water.
The interior zone extends east from 85 km from the western edge of the Proposal, representing a
relatively remote and, from a groundwater perspective, poorly explored terrain. Geologically, this
area is characterised by two distinct Archaean geological terrains, gneiss and granitoid‐greenstone
(metavolcanics).
The lower Proterozoic basement outcrops extensively, but is overlain in places by relatively thin
Tertiary and Quaternary deposits, which are associated with both modern and palaeo‐drainages.
Small scattered areas of calcrete (Tertiary age) are exposed in depressions between drainage divides
and drainage channels. The greenstone belts generally trend in a north‐west to north‐north‐east
direction and are surrounded by several granitoid (mafic and ultramafic rocks) intrusions. These
intrusive rocks are highly deformed by structural features (e.g. faults and shears).
Calcrete, colluvium and valley‐fill alluvium form the main shallow aquifers in the area. Depths to
groundwater are typically shallow near the river channels and creeks, and there are a few semi‐
permanent pools where the groundwater table daylights in the Murchison River channel. Alluvial
streambed aquifers receive groundwater recharge during creek flow events (generally associated
with cyclones). Due to the relatively thin accumulations of alluvium, the groundwater storage
capacity is limited resulting in their quick replenishment and subsequent surface water runoff
volumes will be high.
Alluvial sediments derived from the ancient course of the rivers (palaeo‐channels) are often located
some distance from the current creek channel. Most of this older alluvium is unsaturated with the
water table occurring close to its base or in the underlying bedrock. Where they do extend a
reasonable depth below the water table, these older alluvial deposits can be significant aquifers.
The Archaean and Proterozoic basement has low intrinsic permeability. The groundwater potential of
basement rocks is typically associated with, and limited to, the development of weathering profiles
and/or structural deformation (e.g. faults, fractures). The contact of highly deformed dykes and
fractured basement may be a source of groundwater in some parts of the Study Area. The quality of
groundwater is highly variable throughout the area and increased salinity is observed towards
drainage lines. The groundwater salinity is expected to vary between 2,000‐7,000 mg/L (TDS) along
the Study Area, except for a few hypersaline areas.
In general, the groundwater yield potential is low to moderate along most of the Study Area in the
interior zone. The success rates of individual bores at exploration targets can be expected to be low
and the prospect exists that local supplies may not be found along some portions of the route.
The regional aquifer productivity and aquifer type for the Mid‐West Region is presented in Figure
5‐33 (Aquaterra, 2010b).
5.2.4.2
Existing Bores
A data search was conducted through the Department of Water (DoW) Water Resource Information
database in 2008 and 2009, for hydrogeological information, such as drilling depths, lithological logs,
water levels and water quality data, along the proposed rail alignment. This search returned a
considerable number of bores within the Study Area (Figure 5‐34), which mostly provide water for
station supplies.
The majority of bores in the area are either investigation, domestic or stock bores (current and
historic), and most of these exploit the groundwater reserves within the shallow alluvial aquifers,
utilising shallow, low‐yielding bores.
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A DoW data search was also conducted, to assess current licensed groundwater allocations in the
area (Figure 5‐35).
The largest groundwater allocation is from a fractured rock aquifer located south of Meka Station
and along the Sanford River, at the Western Queen Mine (owned by Mt Magnet Gold). It is
understood that the licensed allocation for this site is 3.7 GL/yr, however this mine is not currently
operational.
The remaining licences have average licence abstraction allocations of between 0‐20 L/s and,
according to the data supplied, tap the fractured rock, sedimentary rocks and alluvial sediments.
Existing groundwater abstraction information in the Perth Basin and Northampton Block has not
been assessed as part of Aquaterra’s report (2009b; Appendix 4), due to delays in receiving data from
DoW. However more recently DoW has advised that groundwater remains available for allocation
within both the Arrowsmith and Jurien Groundwater Areas of the Northern Perth Basin. In relation to
the East Murchison and Gascoyne Groundwater areas, these resources have a nominal allocation
limit and licences to access these resources are assessed on an impact basis using the department’s
state‐wide strategic and operational licensing policies and mining guidelines.
5.2.4.3
Groundwater Field Surveys
Phase 1 Survey
OPR implemented the first phase of its groundwater investigation programme on 4
th
November
2009. Nine targets were investigated at which a total of 21 exploration holes were drilled including
six production bores and eight as monitoring bores (Figure 5‐36).
Where a production bore was installed, an adjacent stygofauna and water quality monitoring bore
was also constructed.
Yield and water quality results from these groundwater investigations are detailed in Appendix 4.
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