EIA Scoping Report
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View of Bell weir on the River Thames at Hythe End, from downstream of the Channel Section 1 outlet. River Thames Scheme - Capacity Improvements and Flood Channel Project Draft Environmental Impact Assessment Scoping Report for Consultation June 2017 Published by: Environment Agency Horizon house, Deanery Road Bristol BS1 5AH Email: enquiries@environment- agency.gov.uk www.environment-agency.gov.uk © Environment Agency 2011 Further copies of this report are available from our publications catalogue: All rights reserved. This document may be http://publications.environment- reproduced with prior permission of agency.gov.uk or our National Customer the Environment Agency. Contact Centre: T: 03708 506506 Email: enquiries@environment- agency.gov.uk. ii Quality Assurance Project name River Thames Scheme Capacity Improvements and Flood Channel Project –EIA Scoping Report Project 1B1S reference ENV_IMSE500260_0184 Date 16 June 2017 Version number P02 Author GBV – Kerry Quinton, Vicky Lutyens, Jenny Marshall-Evans, Gemma Carey, Andrew Todd, Chris Aylward & Enplan – Phil Russell-Vick Checking and Approvals Name Signature Title Date Version Kerry Quinton (Checker) <electronically checked> Principal Environmental 16.06.2017 P02 Scientist (GBV) Vicky Lutyens (Reviewer) <electronically reviewed> Chief Environmental Scientist 16.06.2017 P02 (GBV) Emma Booth (Approver) <electronically approved> Project Manager (GBV) 16.06.2017 P02 EIA Scoping Report | iii ---- This page has intentionally been left blank ---- EIA Scoping Report | iv Summary Purpose of this document This document is the Environmental Impact Assessment (EIA) Scoping Report for construction and operation of the River Thames Scheme (RTS) Capacity Improvements and Flood Channel (CI&FC) Project. The proposed project is being promoted by a partnership of organisations including the Environment Agency, Royal Borough of Windsor & Maidenhead, Surrey County Council, Elmbridge Borough Council, Runnymede Borough Council, Spelthorne Borough Council, London Borough of Richmond upon Thames, Royal Borough of Kingston upon Thames, Thames Water, the Department of Environment, Food and Rural Affairs (Defra), and Thames Regional Flood and Coastal Committee (RFCC). The purpose of this report is to provide details of the preferred option for the RTS CI&FC Project, and to present the findings of the scoping stage undertaken as part of the EIA process. The EIA is being completed under the Town and Country Planning (EIA) Regulations 2017 (SI 2017/ 571). The Project sits within a wider framework of activities being delivered under the RTS. The vision for the RTS is broad ranging and goes far beyond solely delivering flood protection. The vision for the RTS is: ‘PROTECTING our communities, SECURING our economy, ENHANCING our Thames’. Background The RTS CI&FC Project will provide flood relief to people, property and existing infrastructure within the River Thames catchment between Datchet and Teddington to the south west of Greater London. The sites of the Project are within the vicinity of the River Thames between Datchet and Desborough Island, at the existing Sunbury, Molesey and Teddington weirs and at Ham Lands (see Figure 0-1). Figure 0-1: Location of the RTS CI&FC project. The River Thames between Datchet and Teddington is one of the largest and most at risk developed but undefended floodplains in England. A major flood (a 1 in 100 flood (one per cent chance of happening in any given year)) would cause risk to life, put approximately 15,000 residential and commercial properties at risk, EIA Scoping Report | Summary v cause severe disturbance to local communities and disruption on both nationally and locally significant roads (with motorway traffic affected on the M3, M4 and M25) (see Figure 0-5). Flooding would also disrupt key rail routes and block access to internationally important infrastructure such as Heathrow Airport. Several major drinking water abstractions supplying south-east England, and up to 20 local electricity sub-stations would also be affected with a risk of flooding to the public sewage network, resulting in disruption to homes. Option development The Lower Thames Flood Risk Management Strategy (LTFRMS) considered a number of options to reduce flood risk. Investigations into technical feasibility, economic viability and environmental acceptability of different flood risk management approaches were undertaken, and the LTFRMS was the subject of a Strategic Environmental Assessment (Environment Agency, 2009). The LTFRMS concluded that the preferred approach to flood risk management is to improve conveyance and reduce flood risk through construction of a flood relief channel and capacity improvements in the River Thames downstream of the new flood relief channel. The project partners have worked together to identify how the preferred strategic option could be implemented, and to develop the outline designs for the preferred option. Preferred option The main components of the Project (see Figure 0-1) include: A 14.6km flood relief channel, split into three sections (Channel Sections 1 (Figure 0-2), 2 and 3); Capacity improvement works at Desborough Cut, Sunbury, Molesey and Teddington weirs (see Figure 0-4); A flood storage area at Ham Lands; Modifying the Thames Water abstraction regime from the River Thames to reduce the peak flows during floods; and Associated features including: flow and water level control structures, flood embankments, site compounds, materials reprocessing sites, landscape enhancement areas and areas of habitat creation. Extensive consultation has been carried out as part of developing the outline designs for the preferred option with the following key stakeholders: Project partners and internal stakeholders; Statutory authorities and consenting bodies; Landowners and operators; Businesses; Community groups and homeowners; and Representative groups (e.g. recreation, wildlife and conservation groups). Existing environmental conditions The Project is located in the Thames Valley, historically an open floodplain of flat grazing lands with scattered historic parklands on the higher ground. However, the character is now increasingly dominated by: Settlements, including: Datchet; Wraysbury; Staines; Chertsey; Sunbury; East Molesey; and Teddington; EIA Scoping Report | Summary vi Transport links such as the M25, M4 and M3 motorways, and railways; and Land uses including Heathrow Airport, Thorpe Park, lakes left from past mineral workings, raised landfills and vast raised reservoirs. Several lakes are used for water sports including fishing, sailing, diving and swimming. Areas of floodplain are used for walking where open to the public or grazing of livestock where privately owned. The River Thames catchment is an area of high archaeological importance. It has been a focus for human activity from the earliest humans to the present day. As a result the area contains a wealth of heritage features, such as ancient monuments, important buildings and buried archaeological remains. The area is very important for biodiversity. Several of the large lakes at Wraysbury are internationally designated for overwintering birds, a hay meadow at Thorpe (see Figure 0-3) is nationally designated for rare plants and insects, and the area contains many other protected species (both land and water based). As well as the River Thames, in the study area there are over 20 rivers and streams and over 40 man-made lakes and reservoirs. Also, the groundwater in the area is an important source of drinking water. Project activities and potential effects The Project will involve many activities during its construction and operation which have the potential to cause beneficial or adverse environmental effects. Major activities during construction such as digging the flood relief channel, upgrades to Thames weirs and building flood banks could cause temporary disturbance to local residents, businesses and users, biodiversity and archaeological remains. In operation, the flood relief channel may cause adverse effects to the water quality of lakes it goes through, with knock on effects on biodiversity and users. Nevertheless, the Project also has the potential for beneficial effects through improved flood protection, greater public access, and creation of habitats and landscape features. Scope of the EIA A preliminary assessment of environmental effects as a result of implementing the RTS CI&FC Project has been carried out. The assessment took into consideration mitigation measures to avoid or reduce effects, which have been incorporated into the outline design as part of an iterative design process. Where the potential for significant effects is uncertain, for example due to uncertainties about the final design, working methods, or the findings of ongoing surveys, as a precaution the relevant environmental topics and receptors are included in the scope of the EIA. The assessment identified that the topics scoped into the EIA are: Air quality and climatic factors; Biodiversity; Cultural heritage, archaeology and built heritage; Landscape and visual amenity; Population (including noise, vibration and land use); Soils and geology (including contaminated land); Surface water, groundwater and Water Framework Directive; and Traffic and transport. It is proposed to scope out of the EIA the Natural Resources and Waste topic and the vulnerability of the project to the risks of major accidents and/or disasters. The potential for cumulative effects with other projects was also considered within