June 2008 Consultation on Thames Water s Draft Strategic Proposals for Sludge Management

Transcription

1 June 2008 Consultation on Thames Water s Draft Strategic Proposals for Sludge Management

2

3 Ltd _ EXECUTIVE SUMMARY Background Thames Water Utilities Ltd. (Thames Water) has developed high-level strategic proposals for sludge management/disposal in our region for the 25 years to The decision to carry out the strategy development was taken for the following reasons: (1) to provide a broad framework for our specific investment proposals, particularly in the period for the periodic review of our charges in 2009, and (2) to review the appropriateness of our current strategy (i.e. wherever possible recycle sludge to land) going forward, given the increasing costs and regulatory/other constraints arising from this outlet. Thames Water further decided to commission a voluntary, independent Strategic Environmental Assessment (SEA) of our proposed long-term strategy, carried out by consultants, Entec. This was to ensure that potential environmental, economic and social impacts were properly understood and accounted for in all stages of the strategy development. A key benefit of completing the SEA is that it involves formal stakeholder consultation and we were keen to ensure that consultation was carried out concurrently with the development of our proposed strategy. This approach was reviewed and approved by the Executive Management Team of Thames Water. In developing our proposals, the following objectives were adopted: To manage sludge so as not to endanger human health or harm the environment, by ensuring that all regulatory and legislative controls are met; To establish long term, secure and sustainable outlets; To ensure that sludge is managed on behalf of customers in a cost-effective and efficient manner, minimising the potential for impact from transport and odour; To have due regard to non-statutory Codes of Practice and industry guidance; To use the latest available information in formulating and implementing the strategy; and To encourage stakeholder participation in the development of the strategy. The strategic proposals cover all wastewater sludges produced at Thames Water sites and consider predicted sludge production up to 2035, over a 10 year and 25 year horizon. Current Strategy In the Thames Water region the quantities of sludge produced have risen in recent years. Similar increases are common to all regions in the UK and elsewhere in Europe, arising mainly as a result of population increases and from more stringent levels of wastewater treatment. The current sources and quantities of sludge produced are identified in greater detail in Section 2 of the full strategy document. Thames Water has always sought to adopt a variety of sustainable, beneficial and costeffective solutions to sludge management. The breakdown of outlets in 2006 is summarised in Figure 1 below.

4 Ltd _ Figure 1. Thames Water Outlets for Sewage Sludge % 1% Agriculture 36% Thermal with energy recovery Compost 62% Land Restoration A number of issues are impacting on the land recycling outlet and these have, in part, driven the need to review and revise the company-wide sludge strategy. The most notable constraints (legislative and practical), which affect potential outlets, are considered more fully in Section 3 of the strategy document but include: A gradual loss of available landbank in the region due to the reluctance of some parts of the supply chain to accept products grown on land treated with sludge; The impact of the Nitrates Directive (Nitrate Vulnerable Zones Regulations) that has reduced the volume of sludge able to be applied to most of the land in our region, with resulting implications on the available land-bank; and In addition, in the future, it is expected that there will be increasing competition for the available landbank from other fertilisers and organic resources such as composted material from Local Authorities ADAS/Grieve Strategic consultants were commissioned to complete a detailed review of landbank availability to inform our proposals, a summary of which is provided in Section 4 of the strategy document. Strategic Proposals General The main conclusions of our strategic vision are to favour processes that (a) maximise energy recovery and (b) minimise sludge volumes. Where there is suitable land bank availability, utilising the recycling to land outlet remains the favoured option. To help protect this outlet we anticipate investing in sludge treatment to improve product quality e.g. reduced odour and dry solids. However, in predominately urban areas, the use of thermal processes with energy recovery may be more appropriate, thus avoiding the increased environmental impact and costs of transporting the treated sludge to land. Further, more detailed conclusions include: Processes that enable the efficient extraction of energy from sludge should be adopted e.g. the installation of enhanced digestion or best practice thermal with energy recovery; The minimisation of vehicle movements on and off sites is also an important factor in identifying our preferred options. Reducing lorry movements will provide benefits in

5 Ltd _ minimising carbon footprint and environmental impacts through reducing fuel use and reducing the potential for nuisance to our customers; Techniques that minimise sludge volumes will also be adopted and this will provide benefits through: a) Reducing vehicle movements if the sludge is being recycled to land; b) Minimising the need to store sludge hence reducing the potential for odour nuisance; and In addition, should we be required to find alternative disposal routes as recycling to land becomes more restricted, then volumes for disposal will have to be minimised. In the longer term, the benefits of carrying out co-digestion with other wastes (e.g. municipal wastes) are attractive, particularly from the point of view of increasing energy production. However, the potentially negative impacts of increased traffic movements required to transport additional material on site and the increased operational complexity involved, would need to be assessed on a site-by-site basis. 10-year strategic recommendations Convert our main sludge treatment centres, where the primary disposal route is recycling to land, to enhanced digestion to increase energy production and minimise solids. Our preliminary view of sites that are projected for the installation of enhanced digestion in the next 10 years include Banbury, Basingstoke, Beddington, Bracknell, Camberley, Crawley, Didcot, East Hyde (Luton), Hogsmill, Little Marlow, Oxford, Riverside, Swindon and Witney. However, this selection will be reviewed on the basis of more detailed site-specific assessments. Although recycling to land remains our favoured option, we plan to reduce our current dependence on land bank in view of potential constraints on this outlet. This will be achieved in the short to medium term through solids reduction as a result of improvements to digestion. The impact this will have on our outlets is shown in Figure 2. Figure 2. Predicted Outlets for Sewage Sludge - 10 year recommendations* 1% 1% Agriculture 42% Thermal with energy recovery Bioenergy crops 56% Land Restoration * There is anticipated to be a relative increase in the proportion of sludge being treated by the thermal process due to increase in sludge production in East London based on population growth including urban regeneration. The reduction in the proportion of sludge recycled to land is as a result of solids reduction through enhanced digestion

6 Ltd _ Provide additional sludge treatment capacity for our large East London treatment works at Beckton and Crossness to deal with population growth and refurbishment of existing assets. This is likely to be additional thermal capacity with energy recovery. Towards the end of the 10-year period ( ) we will undertake a further strategic review of the current capacity of treatment/outlets employed, location and number of sludge centres in the Region, in order to inform the next 15-year investment programme. 25-year strategic recommendations Our strategy for the period will be informed by the outcome of an updated strategic review and on assessment of landbank availability. However, it is anticipated that our main proposals will be to: o Maintain recycling to land where the landbank availability allows o Introduce thermal units with energy recovery at large urban sites impacted by land-bank constraints o Introduce co-digestion with municipal waste where capacity exists or it can be deployed Further development of sludge management proposals It should, however, be stressed that these preferred treatment/outlet options should not be regarded as site-specific recommendations. For developments at specific sites, the preferred options would need to be reconsidered in order to check that the assumptions made here are still valid. In progressing favoured options, it is recognised that some of these may fall within the scope of the Environmental Impact Assessment (EIA) Regulations. This high level assessment of sub-regional areas will contribute to future assessments but further detailed work on a sitespecific basis may be required to take any preferred option forward.

7 CONTENTS 1. INTRODUCTION THE ROLE OF THAMES WATER WHAT IS SLUDGE? PURPOSE OF THE STRATEGIC PROPOSALS STRATEGIC OBJECTIVES & SCOPE BUSINESS PLANNING METHODOLOGY INTEGRATION OF THE STRATEGIC PROPOSALS WITH THE SEA SLUDGE PRODUCTION, TREATMENT CAPACITY & HEADROOM SLUDGE LOADINGS TREATMENT CAPACITIES SLUDGE PRODUCTION REGULATION OVERVIEW INTRODUCTION SUMMARY OF KEY LEGISLATION AND NON-STATUTORY GUIDANCE REVIEW OF PLANS AND PROGRAMMES TREATMENT OPTIONS, CURRENT & FUTURE OUTLETS FOR SLUDGE AGRICULTURE NON-AGRICULTURAL OUTLETS ENERGY BASED OUTLETS LANDFILL OPTIONS ASSESSMENT METHODOLOGY ASSESSMENT OF OPTIONS SELECTION OF POTENTIAL TREATMENT/OUTLET OPTIONS PHASE SELECTION OF POTENTIAL TREATMENT/OUTLET OPTIONS PHASE FURTHER DEVELOPMENT OF SLUDGE MANAGEMENT PROPOSALS DETAILED ASSESSMENT OF SUB-REGIONAL AREAS INTEGRATED IMPLEMENTATION STRATEGY FOR EAST LONDON EAST LONDON (THERMAL DESTRUCTION WITH ENERGY RECOVERY) EAST LONDON (DIGESTION) MOGDEN (WEST LONDON) MAPLE LODGE SOUTHERN REGION WESTERN REGION (DIGESTION) SOUTH-EAST REGION (LIME) WESTERN REGION (LIME) WEST LONDON NORTH LONDON NORTH EAST PROVINCES MAIN CONCLUSIONS GLOSSARY 63 APPENDICES

8

9 Ltd _ 1. INTRODUCTION 1.1 The Role of Thames Water Thames Water Utilities Ltd (Thames Water) is the UK s largest regulated water and wastewater services company based on number of properties served. We have over 8 million clean water and over 13.5 million sewerage customers, which is nearly a quarter of the total population of England and Wales. The region within which we provide regulated water and sewerage services occupies about 13,750 km 2 and encompasses more than 9% of the total area of England and Wales. Thames Water serves London with the consequent very high concentrations of traffic and economic activity around the clock and our regulated business area reaches as far as Cirencester in the west, Dartford in the east, Banbury in the north and Haslemere in the south. We have a responsibility to supply clean, safe drinking water and to collect, treat and safely return society s wastewater to the environment. Thames Water is a privately owned business with a duty to deliver all of its activities in compliance with relevant regulations and at a cost that delivers value to our customers. The supply of water to our customers involves abstracting water, treating it to strict drinking water quality standards and then distributing it to customers premises through our network of pipes or mains. Water is abstracted from surface sources, such as rivers or via reservoirs, or from underground sources, via wells and boreholes. We use reservoirs to store untreated raw water and underground service reservoirs for treated water, in order to maintain supply. Providing sewerage services involves the collection, treatment and disposal of sewage. Sewage is collected through our network of sewers and moved, by gravity or pumping, to sewage treatment works where it is treated. The bulk of Thames region s sewers are combined surface water and foul water systems, taking wastewater from domestic, trade and commercial customers as well as runoff from roads and roofs. Collection and treatment of these wastewaters is regulated through the Urban Wastewater Treatment Directive and associated Regulations. The relevant legislative requirements have driven extensive investment in wastewater treatment in recent years to ensure that appropriate treatment is delivered for the vast majority of Thames Water region s population, with the remainder being largely individual settlements with private septic tank arrangements. In addition to this, trade inputs to the wastewater system have been subject to increasingly stringent, rigidly enforced trade effluent discharge consents in order to protect both the quality of the water discharged from wastewater treatment works and to maintain the quality of the residual sludge. 1.2 What is sludge? Sludge is produced as an unavoidable natural by-product of the processes used in both wastewater treatment works and water treatment works, and comprises the solids removed during the treatment processes Wastewater Treatment Works Sludge Sludge from wastewater treatment works is primarily the organic by-product of the biological treatment of wastewater, formed during the settlement of the breakdown products of the treatment process. Wastewater treatment works operate biologically active processes and sludge is the natural product of this process. It should be emphasised that sludge is not untreated faecal matter, nor is it an industrial or hazardous waste. When appropriately treated and managed it does not present a risk to the environment or human health and it can be safely recycled to provide a benefit to society and the environment - sewage sludge resulting from the treatment processes is predominately recycled to land, acting as a fertiliser or incinerated and used for power generation. 8

10 Ltd _ Thames Water treats around 2,8000 million litres of sewage per day from households, businesses and industry in the Thames Water region. There are two basic forms of sludge produced from the treatment of wastewater raw primary sludge (consisting largely of faecal material) and secondary sludge (a living culture of organisms that help remove contaminants from wastewater before it is returned to rivers or the sea). Wastewater is initially collected as a liquid containing typically 0.1% dry solids (DS). It is then dewatered to typically 3-5% DS for efficiency of treatment and transported to one of 37 sludge treatment centres. Here the sludge is further treated via mechanical, biological or chemical processes prior to recycling. Typically Thames Water will manage liquid sludge at between 1% and 5% DS and caked sludge at around 25% DS. The sewage sludge is transformed into treated products (also known as biosolids) using a number of treatment processes such as digestion, thickening, dewatering and lime stabilisation. With respect to the recycling of sludge to agricultural land, two levels of sludge treatment are defined: Conventional treated sludge - Processes that are capable of reducing the microbiological content of sludge by 99%. The most common form of treatment is anaerobic digestion, where sludge is digested at a temperature of around 35 o C for several days, followed by a further period of maturation. Enhanced treated sludge - Processes that are capable of virtually eliminating ( % removal) any pathogens that may be present in the sludge. Processes such as thermal drying the sludge, lime treatment or pasteurisation followed by digestion are capable of achieving this. Whilst the drive to improve wastewater treatment standards has led to a significant improvement in the quality of Thames region s streams and rivers, this has in turn resulted in wastewater treatment works producing more sludge. As this drive for water quality improvement is continuing, in addition to anticipated increases in the population served, we expect the quantity of sludge produced in the Thames region to continue to increase for the foreseeable future Water Treatment Works Sludge Water treatment produces much smaller volumes of sludge than wastewater treatment - around 19,000 tonnes dry solids annually. With respect to water treatment processes, coagulants are added to the untreated water that assist silt and other fine particles to settle out. The resulting water treatment sludge is thickened to around 2-3% DS and then dewatered to a 20-25% DS cake by pressing or centrifuging. Much of this sludge is discharged to sewer and treated within a wastewater treatment works therefore, water treatment works sludge will not be considered separately but as part of the Sludge Strategy for wastewater treatment sludge. Water treatment sludge is a very different material to sewage sludge being largely inert, but containing useful trace elements and carbon that are beneficial to soils, when the product is recycled to land. 1.3 Purpose of the Strategic Proposals These strategic proposals (the sludge strategy) have been developed to address the current and future requirements for the management of sludge in the Thames Water region. It will form a framework within which Thames Water s investment, operational and planning decisions will be made and takes into account key contextual factors including: Changes in the quantity of sludge produced; Regulatory requirements and changes in the way that legislation controlling current sludge outlets is implemented; and 9

11 Ltd _ The perception of sludge and the outlets employed by the public, regulatory authorities and commercial organisations. The strategy considers the quantities of sludge that will be produced by Thames Water as a consequence of wastewater treatment processes up to a planning horizon of Thames Water has responsibility for the management of the sludge produced in the course of these wastewater operations. As such Thames Water seek to manage the production, treatment and recycling of sludge by adopting sustainable, secure and cost effective methods and outlets. In developing an appropriate strategy, it must be recognised that sludge production is a direct consequence of human activity. Equally the outlets selected for the recycling or disposal of sludge can also have direct or indirect effects on society. It is therefore essential that the public, regulatory authorities and other stakeholders have an understanding of the issues affecting sludge management and can contribute to the approach to finding the most appropriate solutions to the management of sludge in the Thames region. In order to develop sustainable, secure and cost-effective solutions, this strategy aims to look beyond immediate operational issues and will inform long-term strategic decisions and investment plans. However, it must also be recognised that circumstances may continue to change in future and therefore the strategy will be reviewed at appropriate intervals to ensure its continued relevance. 1.4 Strategic Objectives & Scope Thames Water treats large volumes of sludge on a daily, weekly, monthly, annual basis. The volumes are such that only tried and tested technology can be used as the waste stream cannot simply be switched off given its origin, or stored for a long periods of time given its nature and volume. Thames Water cannot expose itself to the risk of investing in unproven or innovative technology, particularly in the short term, which may not work. Equally, Thames Water is subject to financial regulation by Ofwat. The regulator sets the charges Thames Water may make to its customers. This has regard to the capital investments Thames Water needs to make but Ofwat will broadly favour proven affordable solutions. The consequence of the nature and volume of the waste stream, and the financial regulation Thames Water is subject to, means it can only invest in proven, robust and affordable treatment/outlet options. In developing and implementing the strategy, Thames Water will adopt the following strategic objectives: To manage sludge so as not to endanger human health or harm the environment, by ensuring that all regulatory and legislative controls are met; To establish long term, secure and sustainable outlets; To ensure that sludge is managed on behalf of customers in a cost effective and efficient manner, minimising the potential for impacts from transport and odour; To have due regard to non-statutory Codes of Practice and industry guidance; To use the latest available information in formulating and implementing the strategy; and To encourage stakeholder participation in the development of the strategy. The strategy covers all wastewater sludges produced at Thames Water sites and considers sludge production up to 2035 over a 10 year and 25 year horizon. We further decided to commission an independent, voluntary Strategic Environmental Assessment (SEA) of our 10

12 Ltd _ long-term strategy (carried out by the consultants, Entec) which has been completed concurrently, with the plan to ensure that the environmental, social and economic effects of the strategy, and its alternatives, are properly evaluated. In addition, ADAS/Grieve Strategic were commissioned to complete a detailed review of landbank availability (the area of agricultural land available for recycling treated sewage sludge) to inform our strategic proposals. It is important to note that this strategy does not attempt to develop site-specific recommendations but rather to set out our broad preferred approaches at a sub-regional level. 1.5 Business Planning Our investment programme for , agreed with our economic regulator Ofwat in 2004, includes no specific investment on sludge treatment assets other than that required to maintain existing asset condition. We did, however, set out a broad strategy for sludge management and this is set out below. The strategy set out here updates this. The Thames Water Business Plan for included the following main sludge related elements: Our strategy, in line with Government policy, is to focus on recycling to agricultural land. Currently we recycle around 60% of sludge to agricultural land with the remainder put to beneficial use through the generation of energy in our two Sludge Powered Generators. We have put in a great deal of effort over the past 3-4 years (alongside other companies and Water UK), to try to improve communication with our stakeholders to ensure that the recycling outlet remains available to us. Indeed, the focus of our investment was to ensure that the agricultural land outlet remained viable. We do not envisage a major change in our use of the recycling to land option in the short term. However, it is clear that this outlet remains vulnerable to external pressures and, in particular, to media scares and individual stakeholder concerns, regardless of the good science and safety record underpinning the practice. Thus, whilst we remain confident in the viability of the agricultural outlet, we are reviewing alternatives with a long-term aim of reducing our dependence on this outlet. Few feasible alternatives are currently available. However, the most promising with respect to the sustainability of the outlet and relative cost, is the thermal of sludge with energy recovery. We have had preliminary discussions on this subject with the major power producers in the UK and they did express an interest. Whilst it is technically feasible to co-fire sludge in a coal or oil fired power station, some issues remain to be resolved, notably in the design of suitable sludge reception facilities and the control of emissions from the plant. Discussions have indicated that it is unlikely to be cost effective to burn sludge in existing power stations, largely because of the expense of retro-fitting necessary emissions control equipment. Therefore we do not anticipate making extensive use of this outlet in the short term (before 2010). Investment will be made at existing wastewater treatment works and sludge treatment facilities to deal with additional quantities of sludge production. Where sludge treatment already exists, the level of treatment currently installed will be maintained. 1.6 Methodology The work undertaken to develop this Sludge Strategy has been structured to produce an analysis of potential outlets for sludge up to the 2035 horizon. A range of outlets have been identified and considered including: a) Those that are currently used or have been used in the past; b) Those that have been previously proposed as realistic outlets; and 11

13 Ltd _ c) Those that are commonly used elsewhere in the UK and Europe. For the purposes of developing this strategy, the range of potential outlets considered has been restricted to those that have the potential to form principal outlets. Potential minority, subsidiary or contingency outlets may then be considered in the context of the agreed overall strategy. In order to assess the risks associated with the range of outlets considered, options have been assessed with regard to their likelihood of providing a sustainable, secure, cost effective outlet over the life of the strategy. The methodology by which this has been carried out is described in more detail in Section 5. The strategy has been developed by considering a number of regional areas, due to the different circumstances across the Thames Water operational areas (e.g. in terms of sludge production, population distribution, topography, agricultural practices and current operational facilities). The defined regions and sludge production in each area are described in Section 2. The strategy development for wastewater sludges comprised the following key activities: Data gathering and validation, including analysis of; a) Existing and future sludge production b) Sources and existing outlet routes for Thames Water c) Constraints affecting potential outlets, including legislative, commercial, environmental and practical constraints; Identification of areas to be adopted for strategy development; Identification of the range of outlet options to be considered; Internal workshops to agree options and the method of assessing sustainability/security risk; Assessment of selected options, based on sustainability/security risk, using the information regarding potential outlets; Presentation of the results of the assessment for each area and production of strategy recommendations for each area; and A sensitivity analysis undertaken to double-check that the accepted methodological approach is appropriate. The methodology from the wastewater sludge treatment/outlet options assessment is detailed in Section 5 and the results from the assessment are summarised in Section 6. Appendix 4 details the sensitivity analysis undertaken. 1.7 Integration of the Strategic Proposals with the SEA The SEA process envisages early and continual, interaction between the preparation of the strategy and the SEA, from the generation of objectives through to scoping, assessment of impacts, consideration of alternatives and through to final reporting. A technical specialist from Entec was involved in developing and commenting on the methodological approach attached to the strategy from Summer Entec validated our method of assessment and provided supporting specialist advice on the operational performance of sludge management options not currently present within Thames Water's operational area such as pyrolysis and gasification. This assisted in providing a comparative strategic level assessment of the options within each sludge sub-region. Entec also helped facilitate an external workshop on 30th November 2007 to explain the SEA objectives, the scope of the study, and the intended approach to the assessment of impacts 12

14 Ltd _ attached to the options within the draft strategy. This allowed the objectives of both documents to be compared as detailed in section 3.2 of the SEA. The SEA has benefited the strategic proposals in that the compilation of the SEA assessment matrices (see Appendix C of the Entec SEA Environmental Report) has allowed the high level environmental performance of the initial preferred options to be assessed across the eleven sludge catchment areas. The scope of the SEA's objectives (see Section 3.2 of the SEA Environmental Report) has achieved consistent consideration of all aspects of environmental impacts, from biodiversity and landscape issues through to energy use & climate change. The SEA matrices will also be helpful to Thames Water in assisting future decision making within the life time of the Strategy and provide a point of reference to the development of specific proposals at particular locations. 13

15 Ltd _ 2. SLUDGE PRODUCTION, TREATMENT CAPACITY & HEADROOM Not all sludge is treated on the site of origin a number of sites have been designated as sludge centres which act as regional hubs treating both indigenous as well as imported sludge from nearby satellite sites. Due to day-to-day operational constraints, it is possible that sludge from satellite sites may be processed at a secondary location, sometimes through alternative treatment technologies. However, by calculating sludge loads from a population equivalent base for all sites, the net effect of this variation is zero. The location of our current sludge centres is illustrated in Figure Sludge Loadings Sludge loading is calculated using the per capita sludge figure of 80g sludge/head/day for standard non-chemically assisted treatment. This value is then adjusted depending on process type (Table 1). Table 1. Sludge loading design parameters per capita Type Total g/head/day Primary g/head/day SAS g/head/day Current Generic 80 Filters Crude Sewage Activated Sludge Settled Sewage Activated Sludge Biological Nutrient Removal Pre-Precipitation Filters Simultaneous Precipitation Activated Sludge Simultaneous Crude Activated Sludge Pre-Precipitation Activated Sludge Wastewater sludge loading figures in Table 2 are listed per sludge centre and are the sum of indigenous sludge and sludge imported from satellite sites. They are subdivided into the following treatment types and display sludge production from 2006 with expected growth until 2035: Mesophillic Anaerobic Digestion; Lime treatment; Thermal with energy recovery; and Composting. The quantities listed in Table 2 are considered to be sufficiently accurate for the development of the Sludge Strategy, but will be reviewed in more detail when considering future project feasibility and implementation at specific sludge centres. The quantities detailed in Table 2 are derived from Thames Water s Strategic Overview of Long-term Assets and Resources (SOLAR) database of current and projected population equivalents. Data in the SOLAR database comes from flow and load surveys carried out by Thames and Local Authority Development Plans, which detail projected population growth per area. It includes population equivalent data for trade effluent and cess loadings in addition to the residential and commuter populations. Future loadings until 2021 are based on Local Authority growth projections, taking into consideration such variables as new development and housing density. Data beyond 2021 has been linearly extrapolated to provide best future estimates. No specific allowance has been made for additional sludge arising from currently unknown changes in legislation, treatment standards, customer behaviour or other factors, such as the impact of Local Authority waste strategies. 14

16 Ltd _ 2.2 Treatment Capacities Digestion capacities are calculated as ranges, which give a conservative capacity and a stressed maximum available capacity to meet the required standards for the control of pathogens and provide acceptable product quality. This range is generated from a model that considers factors such as effective digester volumes; feed dry solids and hydraulic retention times; volatile solids loading from proportions of primary and surplus activity sludge; amount and type of secondary storage. It is clear from the figures that our current digestion capacity is limited and plants are operating at or close to their maximum. Lime treatment capacities are also expressed as a range. This is calculated on a known throughput over a normal 8-hour working day and a 24-hour working day. Assumptions are made on actual working hours based on down times associated with start up and shut down times, to give a range based on 8 hrs to 18 hrs operation per day. Sludge Powered Generator capacities are expressed as a range from a 24-hour 365-day operation, to a more achievable level, which incorporates maintenance shutdowns. 2.3 Sludge Production As a data check, the calculated sludge loading figures for 2006 were compared to the measured annual sludge mass removed from each site. It is important to remember that calculated sludge loading is a pre-treated annual mass and sludge hauled to land is a posttreated annual mass. A total value for 2006 actual digested sludge hauled to farm is expected to be between 45% and 60% of calculated pre-treated sludge mass. This takes into account known variables: Expected in digesters (35%); Consented solids in final effluent (calculated from known data); and An estimated +/- 16.6% combined error (+/- 15% sludge hauled to farm, +/- 5% percapita sludge loads and +/- 5% in SOLAR figures). For lime treatment, the mass of sludge recycled should increase by approximately 5% through lime addition. A total value for 2006 actual limed sludge hauled to farm is expected to be between 95% and 110% of calculated pre-treated sludge mass. This takes into account known variables: Consented solids loss in final effluent; and An estimated +/- 16.6% combined error (+/- 15% sludge hauled to farm and +/- 5% per-capita sludge loads and +/- 5% in SOLAR figures). 15

17 Ltd _ Table 2. Wastewater sludge loading figures per sludge centre* Sludge Centre AMP4 Conservative capacity (85% EDV & 5% DS) TDS/year Sludge Loading tds/year Sludge to Land tds/year Projected Sludge loads, tonnes dry solids per year (tds/year) Thames Valley Mesophilic Anaerobic Digestion All sites capacities include AMP4 Upgrades Ascot 1,143 1, Aylesbury 7,804 5,273 5,552 5,866 6, Banbury 4,174 4,542 4,713 4,751 4, Basingstoke 5,567 5,768 5,957 6,112 6, Beddington 7,821 10,786 11,085 11,301 11, Bishops Stortford 3,171 2,399 2,844 2,906 2, Bracknell 4,158 3,697 3,683 3,820 3, Camberley 3,411 4,490 4,553 4,614 4, Chertsey (Cambi) 9,472 10,708 10,732 10,796 10, Cranleigh Crawley 2,495 5,634 5,863 6,059 6, Deephams 26,515 27,148 27,493 27,730 28, Didcot 1,740 1,879 2,007 2,271 2, East Hyde (Luton) 3,463 4,711 4,839 5,144 5, Haslemere Hogsmill 9,560 11,787 12,023 12,267 12, Maple Lodge 26,705 20,087 20,298 20,541 20, Mogden (Prepasteurisation) 82,733 58,797 60,322 61,474 62, Oxford 6,335 8,559 8,904 8,999 9, Reading (Prepasteurisation) 13,335 8,702 8,890 9,089 9, Rye Meads 22,604 16,927 17,843 18,627 19, Slough 12,103 11,140 11,360 11,437 11, Swindon (Acid 7,825 9,051 9,564 10,098 10, Phase Digestion) Wargrave 4, ,166 4,372 4, Woking 2, , Others 3676 Subtotal Digestion 268, Lime 8 hr operating capacity tds/year Basingstoke 2417 Farnham 4,942 5,942 6,159 6,335 6, Guildford 4,530 6,892 6,946 7,006 7, Earlswood 3,594 4,207 4,266 4,382 4, Fleet 2,471 4,410 4,491 4,495 4, Newbury 4,118 3,643 3,771 3,862 3, Bicester 1,498 1,652 1,722 1,797 1, Wantage Batch 2,548 2,567 2,668 2, Witney 1,498 3,439 3,593 3,655 3, Subtotal Liming 22,

18 Ltd _ Composting Theoretical max tds/year Little Marlow 4,550 5,382 5,429 5,459 5, Sub total Composting Sub Totals (Non-East London) East London Mesophilic Anaerobic Digestion Long Reach 22,044 24,674 24,968 25,509 26, Thermal Destruction Design capacity if 100% operational tds/year Total sludge throughput 2006 (tds/year) Beckton 71, , , , , Crossness 38,325 56,940 57,487 59,382 61, Liming Beckton Batch 3310 Crossness 29, Sub total East London 160, , , , , , , , ,167 Waste Water Totals tds/year *The quantities listed above are considered to be sufficiently accurate for the development of the Sludge Strategy and are a snapshot as of mid These will be reviewed in more detail when considering future project feasibility and implementation at specific sludge centres. 17

19 Figure 3. Thames Water Sludge Treatment Centres

20 3. REGULATION OVERVIEW 3.1 Introduction The production, treatment and consequent recycling, reuse or disposal of sewage sludge is controlled by a substantial amount of legislation. This legislation and non-statutory codes of practice and guidance are summarised below. This strategy will only consider legislation relevant for England, as the area of sludge production, consequent treatment and outlet is only likely to be within areas controlled by English legislation. It is possible for sewage sludge to be taken beyond the Thames Water region for treatment/disposal and, in theory, this movement is only limited by the distance involved. The legislation considered will impact sewage sludge at different stages of the process - the production/primary treatment, the movement/intermediate treatment and the final recycling/disposal process. All of these stages will be considered in this section. 3.2 Summary of key legislation and non-statutory guidance Driver Urban Waste Water Treatment (England and Wales) Regulations 1994 (SI 1994 No. 2841) implementing the Urban Waste Water Treatment Directive (UWWTD) 91/271/EEC Waste Framework Directive 75/442/EEC (as amended) Sludge (Use in Agriculture) Regulations 1989 implementing the Sewage Sludge Directive 86/278/EC The Safe Sludge Matrix 1998 (3rd edition 2001) Impact on Sludge Due to practical implementation of the Directive, and the cessation of sea disposal, sewage sludge quantities requiring disposal have increased due to the increased level of wastewater treatment and tighter discharge consents. This Directive forms the backbone of most of current legislation and sets the framework for waste management and most significantly defines the waste hierarchy as the hierarchy of all waste management options. The Directive is currently being revised - the effect of this revision will be felt through most of the forthcoming UK legislation. These Regulations lay down the requirements for applying sewage sludge to agricultural land and are supported by a Code of Practice, which details all aspects of sludge recycling to land. The regulations set permissible limits for soil concentrations and rates of annual additions of Potentially Toxic Elements (PTEs). The allowable limits for Zn, Cu and Ni in soils vary with the ph of the soil. There are no restrictions on the concentrations of PTEs in sludge. This voluntary agreement made between the UK water and sewage operators and the British Retail Consortium came into force in 1998 (revised in 2001). The matrix requires strict microbiological controls on the quality of Sludge and the correct procedures to be adopted for its application to agricultural land used to grow food crops. The provisions of the Matrix go beyond the requirements of the Sludge (Use in Agriculture) Regulations as they currently stand. It was originally envisaged that the Safe Sludge Matrix would be incorporated into the Revised Sludge (Use In Agriculture) Regulations and Code of Practice for Agricultural Use of Sewage Sludge. These amendments have been delayed and are still not embedded into the regulations. 19

21 Driver The Nitrates Directive (91/676/EC) and The Action Programme for Nitrate Vulnerable Zones Regulations 1998 Waste Management Licensing (WML) Regulations 1994 (as amended 2005) The Pollution Prevention and Control (PPC) (England and Wales) Regulations 2000 (as amended) (implementing EU Directive 96/61/EC and 2000/76/EC) Waste Incineration Directive (WID) 2000/76/EC implemented by the Waste Incineration Regulations (S.I No. 2980) Environmental Permitting (England & Wales) Regulations 2007 Impact on Sludge The Nitrates Directive aims to tackle pollution of waters caused by nitrogen from agricultural sources. This limits application of nitrogen (and hence the amount of sludge) able to be applied to land in designated Nitrate Vulnerable Zones (NVZs). The Action Programme establishes NVZs inside which organic manure and sludge applications are limited and also includes soil type and application date restrictions to reduce the risk of diffuse nitrate pollution of watercourses. The impact of this is the need to find more land suitable for recycling sludge and the increased number of sites designated as NVZ will effectively reduce the amount of land available to spread sludge. Defra are currently consulting on revisions to these regulations it is expected that these will come into force during These Regulations state that anyone who proposes to deposit, recover or dispose of a controlled waste must hold a licence issued by the Environment Agency. Thames Water has a responsibility, under the duty of care, to ensure its wastes are only passed on to companies that hold an appropriate waste management licence (WML). There is a range of exemptions for activities with environmental benefits, but certain conditions apply. Most importantly, sewage sludge being applied to land is exempt provided it can be shown to demonstrate benefit to agricultural land or ecological improvement. Further exemptions allow sludge to be stored on site prior to agricultural land application, land reclamation and forestry. PPC applies an integrated approach to the regulation of certain industrial activities. Emissions to air, water and land plus a range of environmental effects are considered together. The EA set permit conditions that include a wide range of energy, waste and raw material efficiency measures. The permit also includes emission limit values and emission monitoring requirements for pollutants likely to be emitted from the installation in significant quantities and measures to prevent accidents and limit their environmental consequences. Permits are required for facilities from which sludge goes for disposal, or at which sludge is dried, gasified or burnt. These regulations put in place permit conditions on such plants and force onerous controls on these operators. Impacts on all thermal processes for the thermal of wastewater sludge. The disposal of sewage sludge by incineration or gasification/pyrolysis is required to meet the standards specified by the Waste Incineration Directive given in Annex I & V and emission limit values for discharges of wastewater from the cleaning of exhaust gases given in Annex IV. For co-incineration, fuel substitution in power generating plant or cement manufacture the emissions limits are given in Annex I & II. These regulations came into force in April 2008 and introduce a single environmental permitting and compliance regime to apply in England and Wales. This regime streamlines and combines Waste Management Licensing (WML) and Pollution Prevention and Control (PPC) to create a single environmental permit with a common approach to permit applications, maintenance, surrender and enforcement. These regulations will follow the format of PPC regulations but with a two-tiered approach. The WML permitted process will be changed into a simplified PPC permit format, although the PPC permit sites are not expected to change. 20

22 Driver Part III of the Environment Protection Act 1990 (EPA), The Noise and Statutory Nuisance Act 1993, and Section 17 of the Environment Act 1995 Code of Practice on Odour Nuisance from Sewage Treatment Works 2006 The Landfill Directive (99/31/EC) Landfill Regulations 2002 The Hazardous Waste Regulations 2005 National Emissions Ceiling Directive (2001/81/EC) Directive 2001/77/EC on the promotion of electricity produced from renewable energy sources in the internal energy market. The Renewables Obligation Order 2006 (Statutory Instrument (SI) 2006 No. 1004) Impact on Sludge It is an offence to create a statutory nuisance and under section 79(1)(d) of the EPA the definition of statutory nuisance includes: " smoke, fumes or gases, dust, steam or smell emitted from premises so as to be prejudicial to health or a nuisance. Local Authority Environmental Health Departments have the power to serve an Abatement Notice on any person causing or likely to cause a statutory nuisance. The Code of Practice aims to provide a framework under the statutory nuisance regime within which the appropriate regulators and sewerage undertakers can operate, to minimise the likelihood and impact of nuisance from odours. The code provides practical advice and a framework for local authority Environmental Health Practitioners who enforce the statutory nuisance regime and sets out for the public what they can expect during an investigation of a complaint of odour nuisance from sewage treatment works. Sewage treatment works operators have the responsibility and ability to put in place the measures to control or abate odour problems from their plant. Landfills are categorised into one of three groups; inert, nonhazardous and hazardous. Waste is categorised into these groups by using the European Waste Catalogue (EWC codes). Hazardous and inert wastes must meet Waste Acceptance Criteria (WAC) which specifies a series of leachable, inorganic and organic parameters (these are maximum limits) in order to be accepted to landfill. Each waste stream must undergo periodic checks to ensure its compliance. As of October 2007, landfill sites are unable to accept untreated waste with the aim to encourage the recovery of waste and to reduce the impact of the waste. An increase in gate fees, reduction in void space available in England, limitations on the biodegradability of the sludge cake/pellets disposed of and the prevention of liquid sludge disposal mean that the disposal of sewage sludge to landfill should only be regarded as the final option. The term "Hazardous Waste" refers to waste that has toxic or dangerous properties. Hazardous waste is classified by its entry found in the European Waste Catalogue 2002 (EWC). These regulations should not affect sewage sludge, as it is not classified as a hazardous waste. Although, this may affect dedicated processing plants such as incineration or gasification/pyrolysis where the ash may be classified as a hazardous waste dependent upon its physical characteristics and composition. Establishes national emission limits for releases of NOx, SO 2, VOC and NH 3 from all sources and impacts most forms of sludge treatment. Promotes the generation and use of electricity from renewable sources. A Renewables Obligation Order is issued annually detailing the precise level of the obligation for the coming year-long period of obligation and the level of the buy-out price. This order provides a market based system giving increased financial returns from the generation of electricity from renewable sources when there is less renewable generating capacity than the obligation placed upon companies licensed to supply electricity. The order allows for the power generated from the co-firing of wastewater sludge with fossil fuels to receive Renewable Obligation Certificates (ROCs) up to 31st March 2009 without the introduction of biomass as energy crops. 21

23 Driver The Climate Change Levy (General) Regulations 2001 and subsequent related legislation. SI 2001 No.1139 The Climate Change Agreements (Energy-intensive Installations) Regulations Directive 2003/87/EC establishing a scheme for greenhouse gas emission allowance trading within the Community The Climate Change Bill (expected to receive royal assent in summer 2008) Impact on Sludge The climate change levy is a tax on the use of energy in industry, commerce and the public sector with additional support for energy efficiency schemes and renewable sources of energy. The aim of the levy is to encourage users to improve energy efficiency and reduce emissions of greenhouse gases. This reduces the levy on electricity used on energy efficient installations and which come from renewable sources. This directive essentially sets greenhouse gas emissions limits for installations to meet the Kyoto agreement. Installation may be given credits from performance better than specified limits, these credits may be traded against poor performing installation. There is a requirement to reduce carbon use/emissions through implementation of the Climate Change Act, with an increasing requirement to manage/reduce carbon footprint and an increasing focus on GHG emissions other than CO 2 i.e. N 2 O, CH 4 The requirements of the Climate Change Act will be statutory. 3.3 Review of plans and programmes The SEA Scoping Report (October 2007) and Appendix B of the SEA Environmental Report identifies and reviews other relevant plans, programmes, policies and strategies that are applicable to the Thames Water region. The review identifies the relationships between the proposed strategy and these other documents i.e. how the strategy might be affected by the published plans aims, objectives and/or targets or how the strategy could contribute to the achievement of any environmental protection and sustainability objectives. 22