5. Alternatives. 5.1 Introduction

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1 5. Alternatives 5.1 Introduction Chapter 4 of this Statement identifies the need, which will be met by the proposed development, the development itself described in detail in Chapter This Chapter explains the consideration that has been given to the identifiable alternative ways to meeting that need, leading to the conclusion that the proposed development at Deephams Sewage Works is the most appropriate way in which the need should be met. ES Chapter 4 details the consideration of alternatives in the EIA process These considerations include an assessment of the strategic options available, the sites and technologies that could be utilised under the most suitable strategic options, the most suitable site and technology and the most suitable means of delivering that selected technology at the preferred site. In seeking to summarise this assessment this Chapter covers the following matters: i. Assessment Methodology ii. Doing Nothing iii. Strategic Options (Site Assessment Stage 1) iv. Identification of Sites (Site Assessment Stage 2a) v. Identification of Technologies (Site Assessment Stage 2b) vi. Identification of Preferred Site (Site Assessment Stage 3) vii. Phase 1 Consultation (Site Assessment Stage 4a) viii. Early Contractor Involvement & Selection (Site Assessment Stage 4b) ix. Phase 2 Consultation (Site Assessment Stage 4a) x. Post Consultation Scheme Adaptation & Finalisation (Site Assessment Stage 5) xi. Summary Given the scale of the development proposed, the essential nature of the need for the development, and the resultant capital expenditure and environmental and land use planning management implications associated with it, arriving at a firm suite of development proposals has been a necessarily lengthy process. Documenting this process are a number of key Deephams Sewage Works Upgrade technical reports, which are listed below and available in full on the Thames Water Deephams website ( or on CD Rom on request: Assessment Methodology: Public consultation version (June 2012) Strategic Options Review: Stage 1 Report (June 2012) Site Assessment: Stage 2a Report (June 2012) Treatment Options Assessment: Stage 2b Report (June 2012) Identification of Preferred Site: Stage 3 Report (June 2012) Phase 1 and Phase 2 Consultation Feedback Reports (Dec 2012, June 2014) Statement of Community Involvement (June 2014) Adams Hendry Consulting Limited Page 60 Planning Statement Final for Submission June 2014

2 5.2 i. Assessment Methodology The assessment methodology was informed by internal technical discussion and external consultation with specialist stakeholders, incorporating a specially convened Stakeholder Forum, as set out in Section 6 of this Statement. The assessment process, shown on Figure 5.1 below and described in detail in the Assessment Methodology Report, firstly allowed for an initial review of strategic options for meeting the need for the upgrade to be undertaken. From this, an assessment of treatment options was undertaken, alongside an assessment of potential development sites. A more detailed assessment of a shortlist of sites was then undertaken to enable the preferred site to be identified. The preferred site was then published for a first phase of public consultation and stakeholder engagement. Figure 5.1 The Assessment Methodology Alongside, and following on from, the first phase of consultation further scheme design development work and treatment option assessment work was carried out to confirm the feasibility of the preferred site and treatment technology options for delivering the upgrade. A second phase of public consultation was then held on pre submission development proposals, the outcomes of which fed into a final adaptation of the scheme prior to submission of the planning application. 5.3 ii. Doing Nothing As explained in Chapter 4, the alternative course of action of doing nothing has been considered and rejected. Under these circumstances the improvements to water quality within Salmons Brook and the River Lee, compliance with regulations and policy, increased treatment capacity and development of a sewage works in Adams Hendry Consulting Limited Page 61 Planning Statement Final for Submission June 2014

3 North London that is fit for purpose would not be provided. Such an approach would lead to: Breaches of environmental permit consents and controls; Continued poor water and environmental quality in Salmons Brook and River Lee; Inadequate treatment capacity, both in terms of equipment and scale, for North London; Failure to comply with governing regulations and policy, and Failure of Thames Water to meet its statutory duties under Section 94(1) of the Water Industry Act Adopting the approach of doing nothing is therefore considered to be environmentally, socially and legally unsustainable. Accepting that some form of development is essential in order to meet the identified need, consideration was then given to the strategic options that could be used to work towards that objective. 5.4 iii. Strategic Options (Site Assessment Stage 1) Through internal workshops, Thames Water developed four strategic options for meeting the need for the development. These options were then discussed with stakeholders at the Deephams Stakeholder Forum. Each of the strategic options has to ensure that treatment of the sewage flows from the Deephams catchment is maintained throughout. These four strategic options were: Strategic Option 1: reduce or remove enough of the incoming flow to Deephams Sewage Works to permit each of the existing three treatment streams to be turned off and upgraded in turn via: o Sub Option 1A: Reduce flows at source o Sub Option 1B: Transfer Deephams flows by pipeline to another existing sewage works o Sub-option 1C: Split Deephams catchment and transfer flows from part of the catchment to another existing sewage works o Sub Option 1D: Split Deephams catchment and transfer flows from part of the catchment to a new sewage works Strategic Option 2: combine various options from Strategy 1 to reduce or remove incoming flow to Deephams Sewage Works. Strategic Option 3: build part of a new sewage works on another site and transfer flows between the new plant and the existing Deephams Sewage Works for treatment. Strategic Option 4: construct on Deephams Sewage Works A detailed review of the Strategic Options process is provided in the report Strategic Options Review: Stage 1 Report (June 2012) Subject to finding suitable sites, Strategic Option 3 of transferring flow from Deephams Sewage Works to new primary, secondary and tertiary treatment plant located on another site was considered feasible and was taken forward for further assessment. Similarly the fourth Strategic Option to reconfigure part of the existing Adams Hendry Consulting Limited Page 62 Planning Statement Final for Submission June 2014

4 Deephams site to enable construction of a new plant to treat part of the flow, while the existing primary and secondary treatment plant is either refurbished or demolished and rebuilt in phases was also taken forward for further assessment The option of implementing source control via SuDS (Option 1A) was rejected for the purposes of meeting the need for the project as it would not lead to a big enough reduction in flows to the sewage works in the time period required to facilitate taking one of the treatment streams out of service while it is upgraded. Option 1B was rejected due to the distance of the next nearest recipient sewage works (Rye Meads to the north or, and Beckton to the south) and the associated construction and energy costs associated with transferring flows and receiving treated effluent to maintain flows within Salmons Brook. Space at the recipient sewage works is also a key factor against this option Splitting the Deephams catchment flows (Option 1C) and transferring to other sewage works faced similar constraints in respect of transfer construction and energy costs and the availability of space at potential recipient sewage works, and was also discounted, whilst Option 1D was rejected as it did not perform as favourably as splitting flows and transferring via the Deephams inlet works to a new sewage works in close proximity to the current Deephams Sewage Works. As Option 2 comprised variations of options within option 1, each of which had been ruled out, this option was also rejected. 5.5 iv. Identification of Sites (Site Assessment Stage 2a) The conclusion of the Strategic Options assessment meant that the only viable options for meeting the need were to either provide a new physical upgrade of the sewage treatment infrastructure at the existing Deephams Sewage Works site, or at a new site. To enable these options to be considered alongside one another to establish the most appropriate means of meeting the identified need, a longlist of potential sites for the upgrade, including the Deephams Sewage Works site, was prepared for further assessment. The detailed identification of sites is provided in the report Site Assessment: Stage 2a Report (June 2012) This assessment included consideration of site size to ensure that options being considered genuinely had sufficient space to accommodate the minimum necessary development. Sites which could not provide that opportunity could not be deemed to represent suitable site alternatives It was also necessary to establish the appropriate area within which a search for sites should be undertaken. A key driver was that, irrespective of where the upgrade is developed, the main inlet pumping stations that deliver flows from the sewers feeding the Deephams Sewage Works, and the preliminary treatment works (inlet screens and screenings handling plant, grit removal and storm tanks), will remain on the existing Deephams Sewage Works site, together with the existing sludge treatment facilities. On that basis, any off-site works would need to be accompanied by provisions for the pumping of preliminary treated sewage from the existing site to the new site for full treatment, and the return of treated effluent and sludge to the existing Deephams Sewage Works. The energy required for pumping increases both with distance from the Deephams Sewage Works and with increases in elevation from the existing site. Furthermore, the greater the distance from Deephams, the longer the tunnel or transfer pipeline required, and so the greater the construction and maintenance costs and impacts. Adams Hendry Consulting Limited Page 63 Planning Statement Final for Submission June 2014

5 5.5.4 A threshold was therefore proposed as the cut-off boundary for the site search area that took account of the combination of these factors. The precise boundary was established in the Site Assessment: Stage 2a Report. Potential sites within this site search area were then identified, with only limited exclusionary criteria applied to ensure that an appropriately wide list of potential sites are available for assessment at the longlist assessment stage Potential sites within the site search area were assessed against defined property/legal, planning and environmental, and engineering criteria. The criteria ensured that a sufficiently broad base of information on the potential sites was collected and assessed to enable a shortlist of sites to be robustly formed. Key issues that could constrain or affect the development of treatment infrastructure on the sites were identified through this process. At this stage of the process, no design work was undertaken on potential sites This approach to site identification was presented to the Stakeholder Forum and Stakeholder workshops during the site selection and assessment process. Comments were invited on the approach being taken to ensure it reflected any Stakeholder views. Application of the site identification exercise resulted in 22 potential sites being included on the longlist, including the existing Deephams Sewage Works site. The 22 sites can broadly be grouped as sites in Thames Water s ownership or use (Deephams Sewage Works / Lower Hall), sites in existing industrial or employment use, and sites in use for formal or informal open space or recreation Application of the identified assessment criteria to each of the sites listed above enabled those sites which had the greatest potential to deliver either Strategic Option 3 or 4 to be identified. The full details of that assessment are reported in the Site Assessment: Stage 2a Report. Through this assessment it became clear that there were few identified sites within the Upper Lee Valley that could be considered suitable to accommodate the Upgrade. A sensitivity test of a wider area did not identify any other sites that had preferable characteristics and / or improved opportunities or fewer constraints when compared to the 22 identified sites. Further discussions through the Stakeholder Forum also did not identify any further sites that would be suitable for assessment as a new sewage treatment works From the assessment of the longlist sites against the assessment criteria, the following shortlist of sites was identified: Site 1 Deephams Sewage Works Site 6 Meridian Business Park Site 9 Lee Valley Leisure Complex Golf Course (Southern part) Site 11 Ardra Road North Industrial Area Site 15 Lower Hall The remaining sites included on the initial long list were rejected. The key issues identified for each of the shortlisted sites is reported in the Site Assessment: Stage 2a Report. 5.6 v. Identification of Technologies (Site Assessment Stage 2b) A process similar to the identification of sites was carried out alongside the site assessment work to first identify which technologies would be most appropriate for Adams Hendry Consulting Limited Page 64 Planning Statement Final for Submission June 2014

6 further assessment and to then provide an indicative scope of the use of those technologies at the identified shortlist sites Firstly, a strategic preliminary engineering assessment of potentially viable treatment options was carried out to consider sewage treatment options against factors that affect their suitability for the proposed development. The options considered included different technologies for primary treatment, secondary treatment, secondary settlement, tertiary treatment, and phosphorus removal. The full findings are provided in the Treatment Options Assessment: Stage 2b Report Technologies shaded green in Table 5.1 below were those assessed as having most potential for use in the Upgrade and used in the assessment of shortlist sites. Technologies shaded in orange were considered to have less potential than the preferred technologies and were not used in any further assessments. Technologies shaded in red were considered to not have potential for use in the proposed development. Table 5.1 Preliminary engineering assessment of treatment options Primary Treatment Options Secondary Treatment Options Secondary Settlement Options Tertiary Treatment Phosphorus Removal Options Conventional Primary Sedimentation Conv AS Conventional Activated Sludge Do nothing (unless in combination with MBR or Reed Bed or Bio-tower) Do nothing (unless in combination with MBR or Reed Bed) Biological Removal FOG Removal & Lamella Primary Sedimentation IFAS Integrated Fixed-film Activated Sludge Conventional Final Settlement Tanks Disc Filters Chemical Dose (AS Lane) BAFF Biological Aerated Flooded Filter Rapid Gravity Sand filters (RGF) Chemical Dose (Primary) SBR Sequencing Batch Reactors MBR Membrane Bioreactors AS + N-SAF Conventional AS with Nitrifying Submerged Filter Biotower + N-SAF (Filter works + N-SAF) Reed Bed 2 Stages of Reed Bed (horizontal flow then vertical flow Other Systems e.g. RBC, oxidation ditches Adams Hendry Consulting Limited Page 65 Planning Statement Final for Submission June 2014

7 5.6.4 For the primary stage treatment both conventional and lamella primary tanks were considered to have potential for use as part of the upgrade. The secondary stage of treatment could be served by either Conventional Activated Sludge (CAS), Integrated Fixed-film Activated Sludge (IFAS), Biological Aerated Flooded Filter (BAFF) or Membrane Bioreactors (MBR) technologies. Tertiary and phosphorous removal options were selected as part of the overall treatment process design to meet the discharge consent Given the range of options available for the secondary treatment stage a further assessment process was carried out for the four preferred technologies: CAS, IFAS, BAFF and MBR. They were then developed into a conceptual generic layout to facilitate estimates of capital costs, operating costs and the associated outline construction programmes. These layouts, costs and programmes were then evaluated for each of the four technologies against a standard set of criteria As a result of the assessment, the secondary treatment options taken forward to be used as part of the process to identify the preferred site were: Conventional Activated Sludge (CAS) for the treatment of the entire flow Integrated Fixed-film Activated Sludge (IFAS) for the treatment of the entire flow, or parts of the flow (IFAS could reduce the required footprint when compared to CAS treatment) Membrane Bio Reactor (MBR) for the treatment of parts of the flow (there are concerns over MBR experience on a Deephams Sewage Works scale, and on energy and cost grounds, however the use of MBR could reduce the area of land required when compared to CAS treatment) 5.7 vi. Identification of Preferred Site (Site Assessment Stage 3) Having identified the Strategic Options and the sites at which the possible technologies could be employed to meet the need to upgrade to Deephams Sewage Works, a process of preferred site selection was commenced The outcome of the process was to further reduce the uncertainty surrounding the most appropriate means by which the proposed development could be delivered. This section summarises that process, which is reported in full in the report Identification of Preferred Site: Stage 3 Report. Assessment of the Shortlisted sites and technologies Preliminary design work was undertaken on each of the shortlist sites to enable the assessment work to be undertaken. This included the preparation of preliminary layouts showing the extent of the built development and the preparation of potential construction programmes. Due to their size or shape, some of the shortlisted sites may be capable of only accommodating a single treatment technology option, whereas others may be capable of accommodating a number of treatment options The decision on the number of preliminary layouts that were prepared for each site took account of the extent to which different treatment options were considered likely to give rise to significantly different assessment results on the shortlisted sites that may affect the selection of a preferred site. Adams Hendry Consulting Limited Page 66 Planning Statement Final for Submission June 2014

8 5.7.5 On the Deephams Sewage Works site for example, different treatment technology options could result in different development areas being required, or construction programmes, as a result of the need to phase development alongside the existing operational works. On other sites where there would not be a phasing requirement, the differences between treatment technology layouts and programmes, and the impacts potentially arising from them, is more limited. For these sites a layout was shown for the treatment technology with the largest footprint compatible with the site The assessment of each shortlisted site enabled preliminary conclusions to be drawn on the potential impacts arising from the development of the upgrade on each site. The assessment criteria used through this process and the outcomes of that assessment are reported in the Identification of Preferred Site: Stage 3 Report. A summary of the assessment and its outcomes is presented below, as they were reported at that time. Site 1 Deephams Sewage Works: outcomes of assessment As an established sewage treatment works its continued use is an appropriate use for the Site, and the principle of developing the upgrade on the existing site is consistent with national, regional and local planning policies. All of the existing sewers within the catchment drain to the site and the consented discharge point for treated effluent is at the site. Upgrading the existing works will take advantage of this existing infrastructure and avoid the need for costly and complex pipeline transfers of sewage, effluent and sludge to and from Deephams. Redeveloping and upgrading the existing site is, however, technically challenging as the existing works must continue to function throughout construction works. There is only limited space available on the Site meaning that an upgrade would have to be built in a series of phases over a number of years. There are resulting risks to the ability to meet the current discharge consent requirements during this period. A multi-phased redevelopment is also more costly to build than a single phased build on an undeveloped site. The development would bring sewage treatment operations closer to some existing residential properties and other sensitive receptors. This will require further detailed assessment and the preparation of appropriate design solutions and the inclusion of any necessary noise, odour or other mitigation. The assessment indicates that the site would be suitable for whichever of the three treatment technologies considered is selected for the upgrade. Whilst consideration of the treatment options resulted in variations to the extent of the built development, construction programme and costs, there were no significant differences between the assessment outcomes for each option. Site 6 Meridian Business Park: outcomes of assessment As this site is in multiple ownership it would be necessary to acquire the land and relocate any existing uses before construction of the upgrade could commence, potentially through the use of a compulsory purchase order. Land acquisition costs and risks are both judged to be high and therefore have the potential to delay commencement of construction at best, or at worst to frustrate the delivery of the upgrade on this site. The site is also designated as Strategic Industrial Land and lies within one of LBE s place shaping priority areas, for which it is an important area of Adams Hendry Consulting Limited Page 67 Planning Statement Final for Submission June 2014

9 job opportunities. Use of the site for the proposed development will conflict with both of these designations incurring further compensatory requirements. The development of the upgrade on this site is assessed as leading to potential impacts on the environment and local community. It would introduce a new odour source into the Ponders End area, which would need to be controlled and mitigated to avoid odour impacts. The development of the upgrade would also be within close proximity of residential properties and a new Academy school and close to the Green Belt, LVRP and the Lee Valley Leisure Complex Golf Course. The layout prepared for this site indicates that there would be limited space available for any on site landscaping or other environmental mitigation. The site would not be capable of being screened from views, and flooding, nature conservation and other mitigation may have to be provided off site. There would also be a need to build transfer pipelines to and from this site to the existing Deephams Sewage Works for sewage, treated effluent and sludge, incurring additional financial costs and environmental impacts during construction. There would then be ongoing financial and carbon costs associated with pumping during the operation of the upgraded works. Site 9 Lee Valley Leisure Complex Golf Course (southern part): outcomes of assessment The entire site is owned by the Lee Valley Regional Park Authority and is in active use as a golf course and camp site. It forms part of the wider Lee Valley Leisure Complex, including the regionally important athletics centre. The Regional Park Authority has confirmed that it would not make the land available for development and would strongly resist any attempts to acquire it. It considers that there would be significant local, regional and national support for its opposition to the use of the site for the upgrade. A compulsory purchase order would be required to acquire the site which, given the views of the Regional Park Authority, has led to land acquisition risks being assessed as complex with the potential to delay or frustrate the development of the upgrade, with no clear sight of a successful land acquisition process. The site is therefore not readily available for the upgrade. The site is also within the Green Belt and Lee Valley Regional Park and it is in active open space/recreational use. The development of the upgrade on this site would conflict with national, regional and local planning policy that seeks to prevent inappropriate development within the Green Belt, to protect the Regional Park and to prevent the loss of designated Open Space. The development of the upgrade on this site is also assessed as leading to potential impacts on the environment and local community. Site 11 Ardra Road: outcomes of assessment As this site is in multiple ownership it would be necessary to acquire the land and relocate any existing uses before construction of the upgrade could commence, potentially through the use of a compulsory purchase order. Land acquisition costs and risks are both judged to be high and therefore have the potential to delay commencement of construction at best, or at worst to frustrate the delivery of the upgrade on this site. The site is also designated as Strategic Industrial Land and lies Adams Hendry Consulting Limited Page 68 Planning Statement Final for Submission June 2014

10 within one of LBE s place shaping priority areas, for which it is an important area of job opportunities. Use of the site for the proposed development will conflict with both of these designations incurring further compensatory requirements. The development of the upgrade on this site is assessed as leading to potential impacts on the environment and local community. The development of the upgrade would be within close proximity of residential properties and close to the Green Belt and LVRP. Parts of the site are at risk of flooding and flood mitigation would be required to be provided either on or off site. As the site lies immediately adjacent the Deephams Sewage Works site, the transfer pipelines for sewage, treated effluent and sludge would only need to be short, incurring less additional financial costs and environmental impacts than the other shortlist sites. Site 15 Lower Hall: outcomes of assessment Although owned by Thames Water there would be a need to end the current waste processing operations at the site to build the upgrade. This issue aside there are no property costs or risks associated with the development of the upgrade at this site. As the site would not need to be acquired, and the upgrade could be built in a single phase, Lower Hall is the option that could deliver the upgrade in the shortest timescale, subject to securing consents for the scheme. However, the site is within the Green Belt and the LVRP and development of the upgrade on this site would therefore conflict with national, regional and local planning policy that seeks to prevent inappropriate development within the Green Belt and to protect the Regional Park. It would be necessary to justify why an exception to normal policies should be made in order to secure permission on this site. This would have to include consideration of the availability of alternative options including the options on the existing Deephams Sewage Works site. The development of the upgrade on this site is also assessed as introducing a new odour source into the local area, which would need to be controlled and mitigated to avoid odour impacts. It would also be within close proximity of residential properties and within the flat valley floor for which mitigation of visual impacts would be limited. Parts of the site are subject to nature conservation and flood risk constraints, and on or off site mitigation would be required, although consideration of the layout that has been prepared for this site shows that there would be very limited space available for any on site landscaping or other environmental mitigation. Identification of the preferred site The Deephams Sewage Works site is an existing operational site where sewage treatment processes have been undertaken for many years. The development of the upgrade on this site would be in compliance with planning policy. It would not involve the potential compulsory purchase of land, land acquisition costs and related risks to the timetable and delivery of the upgrade. This means that the use of the Deephams Sewage Works site for the upgrade has significant advantages over other shortlist sites. Provided that the challenges of upgrading the existing site alongside the continued operation of the existing works can be met, it was concluded that the preferred site Adams Hendry Consulting Limited Page 69 Planning Statement Final for Submission June 2014

11 for meeting the identified need for the proposed development is the existing Deephams Sewage Works site. Should the options for delivering the upgrade on the existing Deephams Sewage Works site prove not to be deliverable following further more detailed assessment, the Lower Hall site would be the next most appropriate site for delivering the upgrade. Owned by Thames Water and located adjacent to the Deephams site Lower Hall represents a more deliverable alternative than shortlisted sites 6 and 11, which themselves are judged to be more deliverable than site 9. Therefore, despite its location in the Green Belt and within the Lee Valley Regional Park, should the Deephams site not be able to progress those circumstances would form the basis of the very special circumstances in which such development in the Green Belt would need to receive favourable consideration The conclusion of the assessment, that the Deephams Sewage Works site was the preferred option for delivering the Upgrade was then taken forward as the basis for public consultation. 5.8 vii. Phase 1 Consultation (Site Assessment Stage 4a) The Phase 1 Consultation process is explained in more detail in Chapter 6 of this statement and also in the accompanying Statement of Community Involvement. The consultation period ran from 3rd July 2012 to 24th October While some community respondents were against the preferred option of developing the upgrade on the existing Deephams Sewage Works site, a significant majority supported this approach. There was clear support amongst the technical and statutory consultees for the options of upgrading on the existing Deephams Sewage Works site Analysis of the consultation responses led to the conclusion that the preferred site for delivering the Deephams Sewage Works Upgrade should be confirmed as the existing Deephams Sewage Works site. 5.9 viii. Early Contractor Involvement & Selection (Site Assessment Stage 4b) Once the decision had been made to seek to develop the Upgrade on the existing Deephams Sewage Works site, Thames Water selected design and build contractors to develop alternative designs for the Upgrade through a competitively tendered process from which one preferred contractor would be selected The documents prepared for the tender process set out the requirements for the design, construction and commissioning of the Upgrade on the existing sewage works site, alongside the requirement to work collaboratively with the project team to assist the production of the planning application. The aim from the outset was to address planning and environmental impacts through design from the tender stage onwards and the documents therefore provided both contractors with a list of environmental issues that needed to be considered in the development of their bid proposals. This list was based on preliminary identification of the likely sensitive environmental issues by the environmental and planning consultant team Environmental and sustainability criteria were used in the selection of the preferred bidder through a process which allowed the environmental team to challenge the Adams Hendry Consulting Limited Page 70 Planning Statement Final for Submission June 2014

12 Deephams Sewage Works Upgrade two contractors designs and make further improvements to the final submitted tender proposals. The successful contractor was appointed in December 2013 and the design for the Upgrade has since been developed iteratively with the project team Thames Water has reviewed different ways of delivering the proposed Upgrade, including giving consideration to alternative potential phasing of development. The Upgrade planning application involves the sequential demolition and construction of Streams A and B, and the decommissioning and removal of the then redundant Stream C, although part of Stream C will be converted to storm tanks. The Upgrade will be technically challenging to deliver, particularly as the works must operate throughout the Upgrade, and continue to meet the terms of the Environment Agency s Environmental Permit that controls the discharges from the site. These factors, together with the need to ensure the health and safety of Thames Water operational staff and the contractor teams constructing the Upgrade, have informed Thames Water s decisions on phasing Whilst alternative phasing strategies could potentially be employed for example by changing the Streams to be demolished and rebuilt these are considered to represent additional engineering and operational challenges during the duration of the construction works that would place additional risks on the project s ability to meet the requirements of the Environment Agency s Environmental Permit. Thames Water considers that the proposed phasing and layout in the Upgrade planning application represents the most appropriate means of delivering the Upgrade As noted in paragraph above, two contractors submitted designed and costed proposals for the Upgrade. The scheme from the unsuccessful contractor is illustrated in Figure 5.2 below. Figure Alternative scheme from unsuccessful contractor not selected Adams Hendry Consulting Limited Page 71 Planning Statement Final for Submission June 2014

13 5.9.7 The unsuccessful contractor s scheme would have involved a single phase of new construction work, involving the demolition of the existing wastewater Stream A and construction of two new treatment streams. New treatment streams would have been predominately on the existing Stream A footprint, but also extending further to the north, east and west than the current treatment infrastructure. The alternative design would have concentrated sewage treatment infrastructure onto a smaller footprint on the site, however this alternative would have reduced the physical separation with the residential properties in Picketts Lock Lane as a result. Following construction of the two new treatment streams, existing Streams B and C would have been decommissioned and demolished, leaving a large area within the site available for future Thames Water use ix. Phase 2 Consultation (Site Assessment Stage 4a) The Phase 2 Consultation process is explained in more detail in Chapter 6 of this statement and also in the accompanying Statement of Community Involvement. The overwhelming majority of the responses supported the Upgrade proposals. Although many support the proposed significant reduction in odour emissions that was set out in the phase 2 consultation material, both the LBE and a number of local residents sought a further reduction in odour emissions from the site x. Post Phase 2 Consultation Scheme Adaptation & Finalisation (Site Assessment Stage 5) In response to the feedback from the phase 2 consultation, the petition submitted to the LBE, and meetings of LBE s Overview & Scrutiny Committee, prior to the submission of the planning application Thames Water committed to implementing additional odour mitigation measures to further reduce odour emissions, a significant change from the position on which the phase 2 consultation was based Thames Water also engaged in discussions with LBE, the GLA, EA and other stakeholders as part of the finalisation of the planning application proposals and the details of the design and mitigation of any impacts xi. Summary The preparation of the Upgrade planning application has included extensive consideration of alternatives, as summarised in this Chapter. This has included potential alternative strategic solutions, alternative sites, alternative technologies, and alternative designs and mitigation measures The conclusion of all of this work is that the Upgrade proposals that are submitted in this planning application are the most appropriate of the alternatives considered. Adams Hendry Consulting Limited Page 72 Planning Statement Final for Submission June 2014