Wagga Wagga City Council Wagga Wagga and North Wagga Murrumbidgee River Levee Upgrade Review of Environmental Factors
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Fpitch Wagga Wagga City Council Wagga Wagga and North Wagga Murrumbidgee River Levee Upgrade Review of Environmental Factors 7 August 2013 Acknowledgement Wagga Wagga City Council has prepared this document with financial assistance from the NSW Government through its Floodplain Management Program. This document does not necessarily represent the opinions of the NSW Government or the Office of Environment and Heritage. GHD | Report for Wagga Wagga City Council - Wagga Wagga and North Wagga Murrumbidgee River Levee Upgrade, 23/14536 | i Executive summary This report is subject to, and must be read in conjunction with, the limitations set out at the end of this report (page 163) and the assumptions and qualifications contained throughout the report. The proposal Wagga Wagga City Council proposes to upgrade the Wagga Wagga and North Wagga Wagga levees along the Murrumbidgee River, including the Main City Levee, North Wagga Wagga Levee and East Street (Bank Two) Levee. The proposal is required to increase the level of flood protection for residents and businesses of Wagga Wagga. The proposal would raise the Main City Levee to provide flood protection for up to a 100 year average recurrence interval (ARI) flood event, and would raise the North Wagga Wagga Levee and East Street (Bank Two) Levee to provide flood protection for up to a 20 year ARI flood event. Key features of the proposal include: Constructing the following levee types, with average increases in height of 66 centimetres to 83 centimetres: – Embankment levees – Sheet pile levees – Concrete wall levees – Hybrid levees (embankment/sheet pile, embankment/gabion wall and embankment/box culvert) Constructing spillways to enable large floods (higher than the proposed level of flood protection) to enter the protected areas in a controlled manner Upgrading levee crossings that are lower than the design flood protection level, or that require structural improvement. These would include crossings for the Great Southern Railway, several major roads, and a number of minor roads and access roads. Need for the proposal Wagga Wagga and North Wagga Wagga have been subject to a history of flooding. Floods have caused considerable damages, financial loss and disruption. Council seeks to upgrade the levees to comply with its policies for flood protection. Options considered Options for managing flood risks have included: Flood modification measures that modify the flood’s physical behaviour Property modification measures that modify the existing land use or buildings and development controls for future development GHD | Report for Wagga Wagga City Council - Wagga Wagga and North Wagga Murrumbidgee River Levee Upgrade, 23/14536 | ii Response modification measures that modify the community’s response to the potential hazards of flooding. The proposal was recommended (WMA Water 2009a) as one of a suite of measures selected from all three categories for implementation as part of the Wagga Wagga Floodplain Risk Management Plan. It was classified as high priority. The flood modification measures considered included: Flood mitigation dams Retarding basins and on-site detention Bypass floodways Channel improvement works Construction of new eastern industrial levee Upgrades of Main City Levee, North Wagga Wagga Levee and East Street (Bank Two) Levee Vegetation management. The Wagga Wagga Floodplain Risk Management Study concluded that for Wagga Wagga, levees are the most appropriate flood modification measure to protect existing development. No other flood modification measures have the potential to provide the levels of flood protection that the proposed levee upgrades would provide. Statutory and planning framework State Environmental Planning Policy (Infrastructure) 2007 permits development for the purpose of flood mitigation work to be carried out by or on behalf of a public authority without consent. The proposal is for the upgrade of levees and constitutes flood mitigation work undertaken on behalf of a public authority. It can therefore be assessed under Part 5 of the Environmental Planning and Assessment Act 1979. Development consent is not required. Community and stakeholder consultation The local community and key stakeholders such as the Environment Protection Authority, Department of Primary Industries – Fishing and Aquaculture, Office of Environment and Heritage and Aboriginal stakeholders have been consulted on the proposal. Issues raised are addressed in this review of environmental factors. Community consultation would continue through display of this review of environmental factors for community input. Any submissions received would be considered in finalising the details of the proposal. Environmental benefits and impacts Beneficial effects of the proposal would include: The proposal would increase the level of flood protection for Central Wagga Wagga from the current 60 year ARI level of flood protection to the 100 year ARI level of flood protection, and for North Wagga Wagga from the current 17 year ARI level of flood protection to the 20 year ARI level of flood protection GHD | Report for Wagga Wagga City Council - Wagga Wagga and North Wagga Murrumbidgee River Levee Upgrade, 23/14536 | iii The proposal would increase the level of flood protection for 2,000 buildings in Central Wagga Wagga and for 91 buildings in North Wagga Wagga The proposal would reduce the impacts of flooding on land uses in the study area, including residences, businesses, roads, utilities and recreational land uses It has been predicted that raising the Main City Levee would reduce the average annual damages of Central Wagga Wagga ($1,406,900) by up to 55 per cent (WMA Water 2009a). The main adverse effects of the proposal would include: Removal of about 1.1 hectares of River Red Gum forest, which provides habitat for flora and fauna, including a number of threatened and migratory species listed under the TSC Act and EPBC Act Potential for soil erosion and sedimentation impacts to the Murrumbidgee River Small increases in flood depth and velocity at properties outside the levees in floods greater than the 60 year ARI flood level Construction noise and vibration impacts on nearby buildings and land uses – noise and vibration would be above the relevant construction criteria for receivers immediately adjacent to the proposal site Potential for a reduction in air quality caused by the generation of dust Long-term visual impacts through increasing the heights of the levees. Views of the Murrumbidgee River and surrounding countryside may be reduced or blocked at a number of properties Potential impacts on non-Aboriginal heritage through the relocation of a monument to the construction of the Main City Levee that was built in 1960 and a flood height gauge that may have been used for historic flood measurements, subject to approval A range of other changes in amenity and environmental risks including land use, traffic and access, socio-economic and waste. The adverse environmental effects would be minimised through the implementation of safeguards and management measures outlined in this review of environmental factors. Justification and conclusion A number of options for the proposal have been considered, with input from community and stakeholders. The identification of the preferred option took into account social, environmental and economic factors. The proposal would result in both positive and negative impacts. Safeguards are identified in this review of environmental factors to manage and mitigate the identified negative impacts. On balance, it is considered that the adverse environmental impacts of the proposal are outweighed by the beneficial effects and that the proposal is therefore justified. This review of environmental factors concludes that the proposal is unlikely to have a significant impact on any species, population or ecological community listed under the Threatened Species Conservation Act 1995. A species impact statement is not therefore required. This review of environmental factors finds that the proposal is unlikely to have a significant environmental impact and therefore an Environmental Impact Statement is not required. GHD | Report for Wagga Wagga City Council - Wagga Wagga and North Wagga Murrumbidgee River Levee Upgrade, 23/14536 | iv Approval from the Minister for Planning and Infrastructure under Part 5.1 of the Environmental Planning and Assessment Act 1979 would not be required. This review of environmental factors finds that the proposal is unlikely to have a significant impact on any matter of national environmental significance listed under the Environment Protection and Biodiversity Conservation Act 1999. A referral to the Commonwealth Department of Sustainability, Environment, Water, Population and Communities is not therefore required. GHD | Report for Wagga Wagga City Council - Wagga Wagga and North Wagga Murrumbidgee River Levee Upgrade, 23/14536 | v Table of contents 1. Introduction ............................................................................................................................... 1 1.1 Proposal identification ..................................................................................................... 1 1.2 Purpose of this report ...................................................................................................... 2 2. Need and options considered .................................................................................................... 5 2.1 Strategic need for the proposal