In Situ Contaminated Sediments Project Work Package 1A Report
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In Situ Contaminated Sediments Project Work Package 1A Report July 2017 Joint Water Evidence Programme In Situ Contaminated Sediments Project Work Package 1A Report Produced: February 2015 Funded by the Joint Water Evidence Programme. The Joint Water Evidence Programme comprises Defra and Environment Agency with partners including Natural England and Forestry Commission. This is a report of research carried out by Royal Haskoning DHV, on behalf of the Department for Environment, Food and Rural Affairs Research contractor: Royal Haskoning DHV Authors: Alison Hallas, Ian Dennis, Jamie Gardiner and Nicola Clay (Royal Haskoning DHV); and Paul Brewer, Mark Macklin and Simon Foulds (University of Aberystwyth) Publishing organisation Department for Environment, Food and Rural Affairs Nobel House, 17 Smith Square London SW1P 3JR © Crown copyright 2017 Copyright in the typographical arrangement and design rests with the Crown. This publication (excluding the logo) may be reproduced free of charge in any format or medium provided that it is reproduced accurately and not used in a misleading context. The material must be acknowledged as Crown copyright with the title and source of the publication specified. The views expressed in this document are not necessarily those of Defra. Its officers, servants or agents accept no liability whatsoever for any loss or damage arising from the interpretation or use of the information, or reliance on views contained herein. In Situ Contaminated Sediments Project Work Package 1A Report Document title: In Situ Contaminated Sediments Project – Work Package 1A Report Status: Final Report v1 Date: 16 March 2015 Project name: Developing the Evidence Base on the Need for Action to Address in-situ Contaminated Sediment in England Project number: 9Y1410 Client: Defra Client contact: Tracy Westell Reference: 9Y1410/R/303250/Lond Drafted by: Alison Hallas, Ian Dennis, Jamie Gardiner and Nicola Clay (Royal HaskoningDHV); and Paul Brewer, Mark Macklin and Simon Foulds (University of Aberystwyth) Checked by: Alison Hallas and Ian Dennis Date / initials check: 27 February 2015 Approved by: Nicola Clay Date / initials approval: NC 27 February 2015 Revised 17 March 2015 Checked by: Alison Hallas Approved by: Ian Dennis Date / initials approval: ID 17 March 2015 In Situ Contaminated Sediments Project – Work Package 1A Report 9Y1410/R/303250/Lond Final Report v1 ii Summary Project aims Defra is seeking to understand the magnitude of risks (e.g. to aquatic ecology and human health) or impacts (e.g. on the way that water bodies are managed) posed by contaminated sediment in England, as part of its work towards meeting its environmental objectives. In the context of this project, in-situ contaminated sediment is defined as: Chemically contaminated sediment within the water column, bed, banks and floodplain of a surface water body that has been transported alongside the normal sediment load and deposited by fluvial or coastal processes. This project considers the risk posed by non-agricultural diffuse pollution sources in England that result in the contamination of in-situ sediments (for example, contamination from toxic metals, hydrocarbons and surfactants). The scope encompasses both freshwater and marine sediments in England and extends to one nautical mile off-shore (the seaward limit of coastal waters under the Water Framework Directive (WFD) in England). Previous national strategies, including the 2007 Defra UK Strategy for Managing Contaminated Marine Sediments (CDMS), focussed on characterising the risks associated with contaminated sediments in the marine environment. However, while extensive research has been carried out in many locations (including as part of WFD implementation studies) and for particular sources of contamination (e.g. historical metal mining; Environment Agency, 2008) there has not been a comprehensive overview of sediment contamination on a national scale. This project seeks to build on the existing evidence base, drawing together information on the freshwater environment to complement that already gathered for marine waters. This project’s overall aim is to provide a sound evidence base on the contamination of in-situ sediments, which can underpin the development of tools and methods that will help Defra, the Environment Agency and other bodies engaged in regulation and protection of water quality. Legislative and environmental objectives A review has been undertaken of the wide variety of statutory and non-statutory controls pertaining to the management and control of in situ contaminated sediment. This includes legislation covering sediments as part of ecological status, as part of nature conservation, as wastes and as land affected by contamination, as well as legislation governing point source discharges, protection of shellfish, industrial emissions and urban wastewater treatment. Planning policy and environmental impact assessment can also influence how contaminated sediments are assessed and managed. There are currently no statutory sediment quality objectives for England. The requirement to mitigate or remediate in situ contaminated sediment will, therefore, depend upon the characteristics of each individual situation, the legal significance and any protection afforded to the impacted feature (local, national, European, etc.), and the weight of evidence supporting the contaminated sediment as being the cause of the observed impact. Unlike the legal provisions made for controlling risks from terrestrial contaminated land which is not being redeveloped under the planning regime (Environmental In Situ Contaminated Sediments Project – Work Package 1A Report 9Y1410/R/303250/Lond Final Report v1 iii Protection Act, 1990, Part 2A, as amended), there is no regime in force which requires public bodies, landowners or other parties to identify register and remediate contaminated sediment. Conceptual model for in-situ contaminated sediments A large number of contaminant linkages (source-pathway-receptor linkages) may result in receptors being exposed to contamination in sediment associated with a water body. A conceptual model is presented in Section 3 of this report which provides a simplified representation of the main catchment1 processes considered likely to be associated with the release, movement, transportation and deposition of contaminated sediment and the impacts associated with this sediment. The importance of each linkage will vary depending on local factors such as the nature and individual characteristics of the catchment, the reach of the catchment under consideration, and the location of the sediments in the freshwater, estuarine and marine environments. The linkages may also be affected by process such as flood events and climate change. Many activities that are carried out within river catchments, estuaries and coastal waters may also affect the linkages identified in the conceptual model. Sediments could be disturbed by a range of natural processes, including flood events, tidal movements and bioturbation, and anthropogenic activities such as capital and maintenance dredging programmes, propeller action from ships, boats and other vessels, construction activities, commercial and recreational fishing, A number of methods have been developed with the aim of controlling contamination before it reaches a water body, such as sediment traps; waste management controls and treatment of effluent discharges. A range of management techniques are also in use which are specific to contamination in sediments. These include removal by dredging, in situ stabilisation, sediment capping and ex situ remediation. A further suite of techniques is used routinely within catchments to control or influence the processes of sediment deposition and erosion within the system as well as extraction for commercial purposes (dredging of aggregates). The primary aim of these activities is to control the sediment itself rather than any contaminants associated with it, although they have significant overlap with the measures outlined above for remediation of contamination in sediments. These include activities in the water, such as dredging, desilting, scour prevention and engineering structures to prevent or encourage siltation, and activities on land such as engineering works to reduce erosion, setting back of flood defences to increase suspended sediment deposition on the floodplain, and beach replenishment. Potential substances of concern 1 Within this study a catchment is defined as an area of land from which surface water flows converge to exit at a single point, and as such represents the area that is drained by a particular body of water. This area includes the network of watercourses that drain into the water body as well as the land surface surrounding them. In addition to flows, the catchment also supplies sediment to the water bodies that are situated within it. The edge of a catchment is defined be an area of higher elevation, often referred to as a catchment boundary or watershed, that separates it from adjacent catchments. Catchments are hierarchical and nested in nature, with small catchments draining into larger catchments until they eventually drain into the sea. In Situ Contaminated Sediments Project – Work Package 1A Report 9Y1410/R/303250/Lond Final Report v1 iv A wide range of contaminants have the potential to have been released into the aquatic and/or sedimentary environment. These include contaminants which have, historically, frequently been tested for in environmental water and