Strathfield to Hornsby Power Supply Upgrade Review of Environmental Factors

7.7. Aboriginal heritage

7.7.1. Existing Environment

A search of the Aboriginal Heritage Information Management System (AHIMS) was undertaken on 14 April 2014 for each of the power room and padmount substation locations and for the aerial works from to Hornsby. A buffer of 200 metres was used and six items were identified within proximity to the Proposal area. One item is located within the rail corridor at Cheltenham.

7.7.2. Potential impacts

An item at Cheltenham is located within the rail corridor where ETTT works are currently being undertaken. This item has been destroyed by ETTT works and is no longer within the rail corridor at this location. The Proposal therefore would not impact on this item. The other five items would not be impacted by the Proposal.

The study area and rail corridor has been substantially modified by urban development and associated surface disturbance in addition to the rail infrastructure. The risk therefore of encountering any unknown Aboriginal heritage items is considered to be low.

7.7.3. Mitigation measures

To manage the potential of encountering unknown aboriginal heritage items, the following mitigation measure would be implemented to minimise impacts during construction: Should Aboriginal heritage items be uncovered all work in the vicinity would cease and the Project Manager and TfNSW staff would be notified immediately. OEH would be notified in accordance with the National Parks and Wildlife Act 1979 . The local Aboriginal Land Council would be notified and an assessment by an archaeologist would be arranged to determine the significance of the objects and any other requirements before work resumes.

7.8. Hydrology and water quality

7.8.1. Existing environment

Surface water

The proposed aerial works would be undertaken from Devlins Creek to Hornsby and therefore would not cross the River between West Ryde and Rhodes. The padmount substations and power rooms at Rhodes and West Ryde are located over 900 metres from the banks and no works would be undertaken near the waterway. A number of smaller creeks are also located along the Proposal. The waterways include Waitara Creek, and Byles Creek. Terry’s Creek and Devlins Creek traverse the Proposal area between Beecroft and Eastwood and Powell’s Creek and are adjacent to the rail corridor at Rhodes and Concord West ( Figure 7-1 and Figure 7-2 ). The Proposal is located within the larger Harbour Catchment Management Authority area. Normanhurst, Pennant Hills, Beecroft and Eastwood are located in the Catchment and West Ryde, Rhodes and Concord West are located in the Parramatta

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River Catchment. Hornsby falls within the / sub catchment of the Hawkesbury-Nepean catchment.

Groundwater

The surrounding topography suggests that groundwater would flow towards the waterways flowing across and adjacent to the site i.e. Powell’s Creek and Parramatta River. Groundwater is also expected to flow towards Terry’s Creek, Devlins Creek, Camp Creek, and Scout Creek.

A search of the NSW Natural Resources Atlas (NRA) database identified no registered groundwater wells within the study area. Thirty eight wells are registered within a one kilometre radius of the site with depths ranging between 4m – 180m.

Water Quality

The quality of surface water runoff in the vicinity of each power room and padmount substation and along the proposed aerial works from Devlins Creek to Hornsby is expected to only be fair to poor. This is a result of existing impacts to surface water quality, including runoff from residential properties, local roads and rail corridor infrastructure.

7.8.2. Potential impacts

Construction phase

Water quality The highest risk to water quality during construction would result from ground disturbance during construction, including: x Construction upstream of waterways or drainage lines x General earthworks, including stripping of topsoil and excavation x Movement of heavy vehicles and machinery across exposed earth. The potential impacts of unmitigated construction activities on receiving surface waters include: x Increased sedimentation and elevated turbidity levels of nearby creeks from exposed soil during site disturbance and movement of construction vehicles, particularly following rainfall events x Increased sedimentation of downstream watercourses, which can reduce light penetration, smother aquatic life and affect the ecosystems of downstream sensitive waterways, wetlands and floodplains x Increased levels of nutrients, metals and other pollutants, transported via sediment to downstream watercourses x Contamination of downstream waterways from spills of chemicals, heavy metals, oil and grease, and petroleum hydrocarbon from construction machinery x Pollution of downstream watercourses from increased litter from construction activities x Tannin leachate from clearing and mulching.

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Groundwater The borehole search identified groundwater levels between 4 and 180 metres below ground level. Maximum excavation levels for the Proposal are expected to be no more than 2 metres. The potential for impacts on groundwater from the Proposal are therefore considered to be negligible.

Operational phase

The Proposal would not result in any change to the drainage regime, nor would it substantially increase the amount of impervious surfaces within drainage catchment areas. As a result, the Proposal would not result in any impacts to hydrology or water quality during operation.

7.8.3. Mitigation measures

Construction

Water quality A soil and water sub-plan would be prepared as part of the CEMP. It would include measures to reduce or avoid erosion and sediment as a result of construction activities (see Section 8.2 ).

Groundwater Should groundwater be encountered during construction activities, appropriate management measures such as water testing, dewatering, temporary water storage and treatment facilities would be implemented to manage any groundwater that seeps into excavations.

7.9. Land use, social and visual amenity

7.9.1. Existing environment

Land use

The existing land uses at the Proposal area and surrounds are described in Section 2.1 . The majority of the Proposal is located within an existing rail corridor with surrounding land use along the length of the Proposal dominated by residential development with areas of commercial and recreational uses. There are minimal works outside the rail corridor. This work includes a section of trenching through a car park at Pennant Hills Station for underground cabling and relocation of poles outside the rail corridor on private land at Normanhurst.

Visual amenity

The Proposal area extending from Hornsby to Strathfield is primarily within the existing rail corridor. The visual landscape is dominated by railway infrastructure in the near view catchment with residential development dominating the mid to distant view catchments. The mid to distant catchments include vegetation primarily in the form of mature trees. As the works are contained to the rail corridor and adjacent land, there would be views of the works from trains using the corridor and Concord West, Rhodes and Pennant Hills railway station platforms. Views of the proposed works would also be possible from adjacent local roads and pedestrian walkways (see Plate 10 to Plate 14 ). Views of proposed works at West Ryde,

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