5 environmental setting

5 Environmental setting

This chapter provides a broad overview of the natural and man-made environments in the area surrounding the Project. It sets the context for the detailed assessment of the key environmental issues (chapter 7) and other, less significant environmental issues (chapter 8) associated with the Project. 5.1 Traffic On the land sections of the cable routes, the cables would mostly be buried in road reserves. Accordingly, traffic disruption would temporarily be an issue during the cable laying process. Construction activities at the STSs, particularly Kurnell STS, would also have traffic impacts. The main features of the existing traffic network are as follows:

• Traffic volumes along the affected roads on the northern side of the Project are greatest along Military Road, west of Bunnerong Road, which carries about 440 vehicles in the weekday afternoon peak hour. • The highest traffic volumes are experienced along Anzac Parade on weekends, where daily traffic volumes can approach 7,400 per average weekend day. This reflects the popularity of the La Perouse precinct and surrounds for active and passive recreation. • There are about 170 weekday bus movements in and out of La Perouse via Anzac Parade, south of Bunnerong Road. • Traffic volumes along the affected roads on the southern side of the Project are greatest along Captain Cook Drive, west of Silver Beach Road, which carries about 300 vehicles in the weekday afternoon peak hour. • There are about 24 weekday bus movements in and out of Kurnell via Captain Cook Drive, Prince Charles Parade and other roads. • There are no signalised intersections within the Project areas on both sides of the Bay. 5.2 Noise The northern section of the Project area consists of the predominately residential areas of La Perouse, Phillip Bay and Chifley that are to the east of Bunnerong Road. In addition, an industrial, bulky goods storage area is located around Bunnerong STS. Whilst this area is industrial in nature, it does not exhibit the noise generating characteristics of nearby heavy industry and port operations at Port Botany. Major contributors to noise levels in the northern section include traffic on Bunnerong Road, wave and water noise and flights to and from Sydney Airport. The results of ambient noise monitoring indicated background noise levels along the northern section of the Project area were 43 to 47dBA. The southern section of the Project area at Kurnell is relatively flat in nature and residential areas are located adjacent to the heavy industry associated with the Caltex Oil Refinery. As such, noise in this area results from industrial noise and traffic on Captain Cook Drive. The results of ambient noise monitoring revealed that background noise levels along the southern section of the Project area were 48 to 52dBA.

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5.3 Botany Bay aquatic environment

5.3.1 Aquatic plants The aquatic plants in Botany Bay include algae, seagrass beds and mangroves. Salt marsh plants which grow in intertidal waters are found in extensive stands around Towra Point and in Quibray Bay and occupy an area of 157 hectares (Watford and Williams 1998).

Algae Phytoplankton are the plant component of plankton comprising microscopic plants ranging in size from about 2 to 300 µm, with a few reaching one millimetre length. Larkum (1981) estimated that the phytoplankton in Botany Bay contribute about 1.5 tonnes per hectare of biomass per year, or about 35 % of the total primary production of the Bay. The algae pest species (Caulerpa taxifolia) is reported to be widespread throughout the Bay.

Seagrass and mangroves Botany Bay supports extensive seagrass beds and intertidal mangrove stands, with the most recent mapping estimate (from 1995) being 624 hectares of seagrass and 423 hectares of mangroves (Watford & Williams 1998). Both seagrass beds and mangrove stands are recognised as playing important roles in estuarine community structure and function (NSW State Pollution Control Commission, 1978c, SPCC 1981c and Ecology Lab 2003a,b). These marine plants contribute a significant proportion of the primary production in estuaries, with detrital material produced by marine plants forming the base of a significant detrital food chain via benthic organisms and the fish that prey on them. Larkum (1981) estimated that the seagrass beds in Botany Bay alone produced about 25 % of the total primary production for the Bay. Seagrass beds and mangrove mud flats, root systems plus drainage creeks provide important nursery habitat for fish and prawns, including a large number of the commercially and recreationally important fish (NSW State Pollution Control Commission 1981c,d,e, Middleton et. al. 1984). The seagrass beds comprise a number of different species with the three main taxa being strap weed (Posidonia australis), eel grass Zostera or Heterozostera species - mainly (Zostera capricorni) and paddle weed species (Halophila spp.). All the Posidonia beds and about 90% of the Zostera meadows are located on the southern side of Botany Bay, with most of the meadows located in the Towra Point Aquatic Reserve and off Silver Beach, Kurnell. There is another large Zostera meadow in the northern embayment off Botany beach (URS 2003) and there are smaller, mainly Zostera, beds along the western side of the Bay, plus small, predominantly Halophila, beds in Frenchmans and Yarra Bays.

5.3.2 Fish and benthic fauna The zooplankton component of the plankton comprises microscopic and small invertebrate and vertebrate (mainly larval fish) fauna. The zooplankton, including larval fish form a significant proportion of the grazers which feed on phytoplankton and they, in turn, become an important food source for older fish. Whilst there have been no published studies found on the ecology of the invertebrate zooplankton of Botany Bay, there are numerous studies of the ichthyoplankton of Botany Bay. This is probably due to the assumed important relationship between the distribution and fate of the ichthyoplankton and the eventual distribution and abundance of fish of commercial and recreational importance:

Fish and sharks There have been a number of studies of the fish and mobile invertebrate fauna of soft sediment sea beds in Botany Bay. The NSW State Pollution Control Commission, 1981c,d,e described eight main habitat types for Botany Bay and found that these habitat types supported 229 fish species. The

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diversity of the Bay's fish fauna was attributed to the complexity and variety of these habitats. The Bay was considered important primarily as a fish nursery area, with juveniles accounting for two-thirds of the commercially and recreationally valuable fish sampled (NSW State Pollution Control Commission, 1981e). Zostera seagrass beds, particularly those on the south side of the Bay which were closely linked with Posidonia seagrass beds and mangrove forests, provided an exceptionally important nursery habitat.

Benthic fauna There have been few studies of the shallow intertidal benthic communities of Botany Bay. Those that have been done related to the sandy shallows adjacent to dredging operations and the northern embayment seagrass beds; Penrhyn Estuary; Foreshore Beach and Towra Beach. A number of studies have been conducted of the deeper muddy and sandy habitats of the Bay. NSW State Pollution Control Commission, assessed the macro-benthic fauna of dredged and un-dredged sea beds in 1976 (NSW State Pollution Control Commission 1979f, Jones 1981, Jones and Candy 1981). Some of the conclusions of the studies relevant to this Project were as follows:

• The dredged areas generally had lower species numbers. • The abundance of benthos in dredged areas was either equal to or higher than the corresponding un-dredged area. • The dredged sites in the entrance channel, closest to the proposed cable route, supported a more diverse and abundant fauna than adjacent undredged sites and the difference was attributed to the greater depth of the dredged area compared to the surrounding un-dredged area, and which was consequently less subject to disturbance from wave activity (Jones and Candy 1981).

5.3.3 Marine mammals and reptiles There are a number of whales and dolphins which occur in shallow coastal waters off Botany Bay (Baker 1983). Whilst a large number of cetacean species is known from strandings (National Parks and Wildlife Service Southern Region records) only a few species are commonly sighted in the locality (Marine Pollution Research 1998, The Ecology Lab 2003a,b):

5.3.4 Sea, shore and wading birds Within the Project area, seasonally visiting sea birds such as the Australian gannet and the little tern feed on small fish prey over the shallow waters of the Bay. Waders and other shorebirds forage for invertebrates on intertidal sand spits and mudflats from time to time, and at high tide roost on low-lying, sparsely vegetated sandy areas above the high water mark in Quibray Bay and around Towra Point (Pegler 1997, Straw 1992. SMEC 2003), Little penguins are known from the waters of Botany Bay. With regard to shore and wading bird usage of the Bay, Pegler (1997), in her retrospective survey of 50 years of wader bird research, noted that within Botany Bay, Eastern Curlews roost in salt marsh and on structures associated with oyster leases, Whimbrels commonly roost in mangroves and Bar-tailed Godwits range freely around the Bay. Straw (1992) noted that generally, few small waders utilise the southern shores of Botany Bay. Whilst the Towra Point Spit Island is the main roost in Botany Bay for the Bar-tailed Godwit up to 500 have been recorded roosting on the Bay northern shoreline, which is also a major feeding area for this species. Further, the main roost in Botany Bay for the Pied Oystercatcher over time has been the Towra Point Spit Island. Over recent years, the National Parks and Wildlife Service have conducted wader and shorebird surveys around Botany Bay (see review in SMEC 2003). Data obtained from these surveys indicate that Silver Beach itself has not, at least in the last ten years, been used as a roost by waders or other shorebirds, probably due to disturbance plus unsuitable roosting site characteristics. The western end of Silver Beach is used infrequently for feeding by Pied Oyster Catchers from time to time and Sooty Oyster Catchers are generally seen on the rocky shores at Inscription Point and further south around the coastal rocky

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shores (BioNet Search 2006). Towra Beach, Quibray Bay and Pelican Point are utilised by Eastern Curlews and Whimbrels as high tide roost sites. Taren Point, Quibray Bay and Pelican Point are utilised by Eastern Curlews and Whimbrels for foraging at low tide. Bar- tailed Godwits roost in high numbers at Sandringham Bay and Penrhyn Bay and Pied Oyster Catchers roost in relatively high numbers at Towra Beach and Taren Point.

5.3.5 Threatened and endangered species or populations Searches of threatened species data bases identified 80 threatened or endangered species pertinent to this Project. These comprise 15 sea birds, 21 wader and shore bird species, 12 cetaceans (whales and dolphins), three reptiles (turtles and sea snakes), four sharks and 25 fish (mainly seahorses and pipe fish). Environmental Impact Statements (EISs) on two recent Botany Bay projects, namely the Towra Point Spit Rehabilitation Project and the Port Botany Expansion Project, have considered the likely impact of those projects on threatened or endangered species in or around Botany Bay. Based on a consideration of the species list compiled for this Project against the reviews provided in these two EISs, only one endangered species, the Black Rock Cod, could be expected to reside in the Project area.

5.3.6 Sediment quality Whilst there have been numerous studies of sediment contaminants throughout Botany Bay, these have generally been located away from the entrance channel, as the work was concerned with major infrastructure projects such as the airport runway and port developments. With respect to the proposed cable route across Botany Bay, Pollution Research (1993) collected two sediment samples from the entrance channel within the Project area; one from the non-dredged seafloor south of the dredged entrance channel and one from the dredged entrance channel. The results are summarised in Kinhill (1990a). Sediments were analysed for nine metals, a number of organochlorides, total petroleum hydrocarbons (TPH), nutrients and total organic carbon (TOC). Comparison of the results against ANZECC/ARMCANZ (2000) criteria for sediment contamination indicates that all of the listed compounds which were sampled had concentrations well below the recommended guideline values. Cardno Lawson Treloar (2006) summarised the results of analyses of seven sediment cores taken from the bed of the Bay in a range of locations relevant to the dredging undertaken for construction of the third runway at Sydney Airport reported in Kinhill (1991). The analyses included heavy metals and organochlorines. All metal concentrations were well below the recommended ANZECC/ARMCANZ (2000) guideline values. Organochlorine concentrations for the majority of sea bed sediments in the tested area were below detection limit. However, some surface samples showed elevated levels, including chlordane, dieldrin and DDT (Dichloro-Diphenyl-Trichloroethane). None of the sample sites with higher levels were near the Project area.

5.3.7 Water quality General Bay water quality is mediated by the tidal and wind mixing of relatively clean oceanic waters and the discharge waters draining the 1,100 square kilometre catchment of the Bay. The catchment is largely cleared (more than 75%) and is highly industrialised, containing about 15% of Australia's industries (Dames & Moore 1995). The largest inflows to the Bay are the Georges and Cooks Rivers. These rivers discharge the major sediment and nutrient loads to the Bay and, following wet weather, contribute other pollutants such as trace metals (NSW State Pollution Control Commission 1979d). Mill Stream and Penrhyn Estuary also contribute contaminated runoff water containing faecal, chlorinated organics and trace metals to the northern embayment during storms. Several water quality studies were undertaken during the construction of the third runway on behalf of Baulderstone Hornibrook Dredeco Parallel Runway Consortium, to meet the contractual arrangements with regard to the Federal Airports Corporation's comprehensive Environmental Monitoring Program. Dames and Moore undertook monthly water quality sampling from December 1992 to June 1994. Water samples were obtained from 10 monitoring sites; five within the dredging area and five outside the dredging area. Sites

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were monitored for Secchi depth and turbidity, as measures of possible dredging related plumes, dissolved oxygen, nutrients, trace metals (Cu, Ni, As, Hg, Pb and Cr) and various organic compounds; Total Petroleum Hydrocarbons (TPH), Total Oils and Grease (TOG), Polynuclear Aromatic Hydrocarbons (PAH) and Organo-chlorides (OC). Whilst the results were not published, they were summarised in Dames & Moore (1995). 5.4 Terrestrial flora and fauna The potential to disturb terrestrial flora and fauna due to the Project is essentially restricted to work at the STSs, as elsewhere road reserves would be trenched to accommodate the feeders.

Bunnerong subtransmission substation Forty plant species were identified from the site inspections of Bunnerong STS. Almost half of the plants detected were introduced species. Three species declared as weeds under the Noxious Weeds Act 1993 (NSW) were identified on the site. These were: Bitou Bush (Chrysanthemoides monilifera); Pampas Grass (Cordateria selloana); and Lantana (Lantana camara). Sunshine Wattle (Acacia terminalis ssp. Terminalis) was identified as a potential subject Threatened Species for the Bunnerong STS site, however, no specimens were identified during the assessment. Site inspection confirmed the presence of the Eastern Suburbs Banksia Scrub Endangered Ecological Community (ESBS EEC) at Bunnerong STS. Its distribution was found to be as recorded by the NSW Department of Environment and Conservation (2004a, 2004b, 2006b). Other patches of vegetation on the site have been previously identified as regrowth (Total Earth Care 2006). A general fauna survey of the site revealed that the Project is unlikely to affect any of the threatened species which had been ascertained from threatened species databases.

Kurnell subtransmission substation The Kurnell STS sits on reclaimed land. A general flora survey of the subject land revealed a very low species diversity comprising only approximately 10 species, along with a variety of weeds and introduced grasses. The most common weeds are Bitou Bush (Chrysanthemoides monilifera) and Lantana (Lantana camara). Most of the native plants occurring on the elevated ‘pad’ of land appear to be planted, although some specimens may be regrowth from the neighbouring natural vegetation communities. Within the currently fenced compound, the only vegetation present is a mown grass area. The northern and south western concrete bund revetment boundaries front onto vegetation that conforms to Coastal Salt Marsh Endangered Ecological Community and is continuous with and includes the mangrove wetland vegetation forming part of the adjacent Towra Point Nature Reserve and RAMSAR designated wetland. This vegetation merges with Swamp Sclerophyll Forest vegetation on the eastern boundary where it is influenced by the creek line on the eastern side of the property. The area to the front of the STS compound fronting Captain Cook Drive, where works are proposed as part of the Project, contains a number of species. These include scattered Swamp Mahogany (Eucalyptus robusta) and Swamp Oak (Casuarina glauca). Where the drainage line north of the STS extends beneath Captain Cook Drive from the oil refinery opposite, a stand of juvenile and/or root sucker regrowth of Casuarina glauca exists, which is contiguous with the mature street front stand. Both of these species are elements of the Swamp Sclerophyll Forest Endangered Ecological Community. However, it appears that they are intentional streetscape plantings undertaken at the time of the original land reclamation and STS development. A general fauna survey of the site revealed that the Project is unlikely to affect any of the threatened species which had been ascertained from threatened species databases. However, whilst no Green and Golden Bell Frogs (Litoria aurea) have been observed on the site, given the proximity of other recent records, there is potential for the species to utilise the creek and drainage lines from time to time.

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5.5 Heritage

5.5.1 Historical context Botany Bay has iconic heritage status. It is the site of Captain Cook’s landing and effectively the starting point of European settlement in Australia and the huge changes that were to follow for indigenous Australians. Botany Bay, Kurnell and La Perouse are to many the most historic localities in Australia. The earliest observations of Aborigines at Botany Bay were made in April and May of 1770 by Captain James Cook and Joseph Banks. They noted the presence of Aboriginal camps in a number of locations and also that the Aborigines did not live in large groups but were dispersed along the perimeter of the bay. Within a short period of time after European settlement, the Sydney Aboriginal population was greatly reduced as a result of two epidemics, most probably smallpox. The first outbreak of the disease is believed to have killed 50 per cent of the Aboriginal population (Collins 1798, Ross 1988, Tench 1961, Turbet 1989). In 1895, seven acres and six and half perches was gazetted as a ‘Reserve for the Use of Aborigines’ – (AR 22358). A number of changes to the size and location of the Reserve occurred over the years and by 1976 it had been developed by the Housing Commission as an Aboriginal Housing project. In September 1985, Yarra Bay House was handed over to the La Perouse Local Aboriginal Land Council for use as its office. European settlement in the Botany Bay area occurred by extension from Port Jackson (Pringle 1979). Land grants were made to Europeans from the 1820s onwards. From about 1820, troops were stationed on the La Perouse headland to control shipping in Botany Bay. Early industries in the Botany Bay area included the production of shell lime, wool scours, tanneries, market gardening, boat building and, of course, fishing. La Perouse has had a long association with recreation and tourism. As early as the 1830s the area was a location for society picnic parties from Sydney. The Sir Joseph Banks Hotel established a long history of sporting recreation and in its heyday it boasted a jetty with bathing houses, five cinder running tracks and a grandstand and stadium that seated several thousand people. The effects of the Great Depression of the 1930s were felt all over Australia. Unable to pay rents or mortgages, the only alternative was to set up a makeshift home in one of Sydney’s many unemployment camps. One of these, Happy Valley, was established at La Perouse. Suburbia slowly moved southwards from Maroubra after the Second World War. The tramline was removed in the 1960s and a new ring road around the headland was constructed.

5.5.2 Heritage items Given the historical context set out above, it is not surprising that the Project area and its surrounds contain quite a number of heritage items. A search of heritage databases and field inspections revealed the following:

• There are 15 previously recorded Aboriginal places located in close proximity to the Project area, none of which would be directly affected by the Project. No additional Aboriginal sites or objects were located during the field survey of the Project. However, one new potential archaeological deposit was identified on the Kurnell peninsula which would be impacted by the Project. This site would be investigated, assessed and appropriate action taken in respect of it prior to any project-related works being carried out in the area.

• There are 25 European historic sites located in close proximity to the study area. Twenty three are previously recorded sites and there were two new sites, the ‘First Fleet Marine’ Restaurant and Boatshed Building, and St John Fisher Catholic Church, identified during this assessment. Parts of two of the previously recorded sites, Prince Charles Parade and Captain Cook Drive would be impacted by this

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project. However, the impacts on the heritage significance of the items are considered to be minor. 5.6 Visual amenity The main impacts of the Project from a visual perspective would derive from new buildings at the Kurnell STS and the temporary establishment of the horizontal directional drilling rig at La Perouse. The proposed works at the Kurnell STS would be additional structures at an existing substation site. The surrounding landscape is a mix of mangrove community on the western side of Captain Cook Drive and industrial, with the Caltex refinery nearby on the eastern side of Captain Cook Drive. The topography is predominately level. A well established planting of Eucalyptus robusta and Casuarina glauca is growing in the front of the Kurnell STS and provides an effective screen to the vehicles travelling along Captain Cook Drive. The tree planting is consistent with the vegetation that exists along the Captain Cook Drive streetscape, especially on the western side of the roadway. The La Perouse area is a highly significant cultural landscape which serves as one of Sydney’s major regional recreational amenities. Its landscape is of high visual quality, consisting of maintained open grassland that is fringed by the native vegetation of the Botany Bay National Park and open to uninterrupted vistas towards the Botany Bay waterways and Kurnell coastline. A series of historically significant, accessible and well preserved structures including the sandstone fort on Bare Island and the sandstone turret structure on the La Perouse peninsula provide important cultural landmarks that are unique to the regional landscape. 5.7 Geology, topography and soils

5.7.1 Regional geology Botany Bay is part of a structural depression termed the Botany Basin that lies within the Permo-Triassic Sydney Basin. Bedrock in the Botany Bay area is dominated by Triassic- aged Hawkesbury Sandstone, which typically comprises medium to coarse grained quartz sandstone with minor shale and laminate beds. Basaltic dykes are common intrusions into bedrock in the northern Botany Bay area. The eroded bedrock surface is overlain in most areas by Quaternary sediment deposits up to 80 metres thick. On land, these Quaternary deposits are predominantly aeolian (wind- blown) sediments composed of fine to medium grained quartzose sands with occasional cemented layers associated with former soil horizons, and include large north-south oriented dune ridges at Kurnell and on the north side of Botany Bay (Johnson et. al. 1997, Roy 1983). Within the Bay, four main stratigraphic units have been recognised which encompass a range of sediment types (Roy 1983, Hann 1985). The upper three units are of relevance here. From upper to lower, they are:

• Loose estuarine sand to muddy sand with some shells, varying from two to seven metres thick except where removed by dredging. • Dense to very dense, fine to medium-grained, well-sorted quartzose sand and minor silty sand (mainly of aeolian origin), with discontinuous peat/organic mud lenses and indurated sand layers, up to 30 metres thick. • Very stiff to hard clay with some peat and shelly sand beds.

Significant areas of filling exist in the Botany Bay area, predominantly around the Bay shorelines where land has been reclaimed. Filling materials include sandy dredge spoil obtained from the Bay and inter-dune swamps and boiler ash from Bunnerong Power Station (McNally & Branagan 1998).

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A major north-west to south-east palaeodrainage system extends along the north-eastern edge of the Bay and offshore via the Bay entrance (Johnson et. al. 1997). A steep sided bedrock channel beneath the Bay entrance reaches a maximum depth of 110 metres below sea level.

5.7.2 Local geology, topography and soils Local geology, topography and soils are considered below for the three discrete sections of the proposed cable route. These are:

• the La Perouse land section, running from Bunnerong STS at Matraville to Botany Bay National Park on the La Perouse headland • the Botany Bay marine section running from La Perouse to Silver Beach at Kurnell • the Kurnell Land section, running from Silver Beach to the Kurnell STS on Captain Cook Drive.

La Perouse land section Topography within La Perouse land section is slightly undulating, with elevations ranging from approximately eight to 30 metres relative to AHD. Topographic relief is greatest towards La Perouse Headland. Geologically, the proposed cable route traverses Quaternary dune sand deposits from Bunnerong STS to the intersection of Bunnerong Road with Woomera and Yarra Roads. It is inferred that these dune deposits overlie sandstone bedrock, at depths ranging from two to 12 metres below ground. Within the former Bunnerong Power Station site (Lot 100 Military Road; immediately to the east of the current Bunnerong STS) up to one metre of fill comprising sand and coal waste/ash occurs at the surface, overlying natural sand (Douglas Partners 1990). The remainder of the route, from the intersection of Bunnerong Road with Woomera and Yarra roads to the La Perouse Headland, is Hawkesbury Sandstone, which is commonly exposed at the surface. Bedrock is expected within one metre of the ground surface in this section. This section also crosses an east-west trending igneous dyke approximately 200 metres north of the entrance to Botany Bay National Park. Such dykes are typically one to three metres wide and weather to clay near the surface (Herbert 1983).

Botany Bay marine section Within Botany Bay, there are large areas where the natural bathymetry has been altered by dredging to provide shipping channels and turning basins for ships to access Port Botany and the oil refinery wharf at Kurnell. Along the proposed cable route, the sea bed is approximately RL -15 metres within 300 metres of the shore at La Perouse, and increases to a maximum depth of around RL -20 metres in the vicinity of the dredged shipping channel. The sea bed along the route gradually shallows from the south-east of the shipping channel to Silver Beach, Kurnell. Marine geological studies suggest that Quaternary sediment deposits of varying thickness cover bedrock across much of Botany Bay. In the vicinity of the cable route, surficial sediments are Holocene estuarine bay deposits composed of fine to medium grained sand with some shells (Hann 1985). These overlie thick Pleistocene dune sand deposits with minor peat at depths of two to 10 metres below the sea bed. Below the shipping channel where dredging has occurred the Holocene estuarine bay deposits may be very thin or absent. Bedrock morphology along the proposed cable route in Botany Bay consists of a steep- sided bedrock palaeochannel with a bottom depth of approximately RL -100 metres, flanked to the south by a platform at RL -10 metres AHD (Johnson et. al. 1977). More recent seismic investigations in an area just west of the cable route and north of the refinery wharf indicate bedrock occurs at least 24 metres below the sea bed in that area (Douglas Partners 2002). In general, it appears from the available data that bedrock is buried by at least 10 metres of sediment from just offshore of Astrolabe Cove, with the possible exception of the vicinity of Grid Reference 335490/6236407 (approximately 1.5 kilometres

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offshore) at the northern edge of the RL -10 metres bedrock platform, where it may occur within five metres of the sea bed.

Kurnell land section At Kurnell the topography is relatively flat with a maximum elevation of four metres AHD on the proposed route. The geology of this section can be divided into three parts:

• a short section of modern beach sand deposits on Silver Beach • holocene tidal delta/beach-ridge sands (1.03 kilometres) • holocene tidal delta with areas of sandy filling on reclaimed tidal flats (0.47 kilometres).

The extent of the filled area was not able to be ascertained from field observations as these are not distinct from the surrounding sand flats. It appears that natural filling was used, probably from local sources. On the basis of numerous short water bores located beside the cable route, depth to bedrock is expected to consistently exceed four metres, and geophysical data suggests that bedrock ranges from about 10 to 30 metres below sea level. 5.8 Groundwater Below ground works would be a feature of this Project hence an understanding of the groundwater regime is important. An unconfined to semi-confined groundwater system known as the Botany Sands aquifer occurs in the Quaternary sand deposits of the Botany (Matraville) area. It has been used as a groundwater source since the nineteenth century and still supplies water to local industry. The sand beds are up to 35 metres thick in the area south-west from Kingsford to Botany Bay, with 15 metres of saturated sand on average. Groundwater flow in this area is generally to the south towards Botany Bay. In general, the salinity of the Botany Sands Aquifer is very low, ranging from 130 to 600µS/cm, except for sites close to the Bay where saltwater intrusion may occur. The pH is highly variable, ranging from 3.9 to 8.9, but the aquifer waters are typically acidic due to the effect of peaty lenses within the sand beds. Saline groundwater may occur in parts of the Kurnell route section as a result of the low elevation, proximity to the Bay, sandy substrate, and presence of reclaimed tidal flats. Brackish water has been recorded in a bore at Solander Street beside the cable route. The aquifer has been seriously contaminated by industry in some areas, including the Botany/Banksmeadow area to the west of Bunnerong STS. The cable route is separated from this area by a bedrock ridge that is expected to prevent the contaminant plume from moving eastwards into the Project area. Department of Natural Resources’ (DNR) mapping of Potential Acid Sulphate Soils (PASS) indicates a ‘low risk’ of PASS occurrence within Quaternary sands in two sections of the land route, a ‘high risk’ of PASS occurrence across Botany Bay, and ‘no risk’ in other areas. However, based on field observations of relatively clean sands, the PASS risk of the land sections is judged to be negligible to very low. Mud content of the estuarine sediments in eastern Botany Bay is reportedly less than 5%, suggesting that the PASS risk of these sediments is also very low. 5.9 Land use Figure 14 shows the major land uses on either side of the Bay in reasonable proximity to the Project area. The Project area and surrounds contain the following:

• Port Botany container terminal and associated warehousing • Botany Cemetery and crematorium • Matraville market gardens

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• Botany Bay bus depot • residential areas • Caltex refinery and wharf • National Park land on both sides of the Bay • aquaculture facilities at Silver Beach • recreational areas • Towra Point wetlands.

The waters of Botany Bay are used for a mixture of commercial and recreational pursuits. There is a fish farm lease adjacent to the Caltex’s Australian Oil Refinery Wharf. No commercial fishing is permitted within Botany Bay, with the exception of limited oyster plots and the fish farm. Recreational fishing is permissible in most other parts of the assessment area and adjacent waters. Recreational boating is popular throughout Botany Bay and Yarra Bay is used extensively by sailboarders. Yarra Bay and Silver Beach are also used by swimmers.

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Figure 14: Land uses

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