How we chose our preferred sites

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Alexis Bishop
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1 Counters Creek storm relief sewer How we chose our preferred sites The site selection process In order to meet the need to reduce sewer flooding in the Counters Creek catchment area of west London, we have responded to the difficult challenge of finding potential construction sites within a densely developed urban environment. Because all of the sites that may be suitable for construction are located close to residential areas, there will inevitably be some impacts on local residents, businesses and communities. Throughout our site assessment and scheme selection process we have, and will continue to, work hard to limit and avoid these impacts wherever possible. Considering these potential impacts has been central to the process we have used to assess and select our potential construction sites. We developed a site selection process to assess and identify the most suitable locations for the following range of construction sites required to deliver the proposed storm relief sewer: Drive shaft site(s) Reception shaft site(s) Interception shaft site(s) Sewer outfall connections or new sewer outfalls A pumping station Construction compounds The site selection methodology follows a multi-stage process, with some stages taking place at the same time, as shown in Figure 1 overleaf. The site selection methodology was published during our phase 1 consultation, and we have asked for feedback on the process we have used to identify construction sites at each stage of our public consultations.

2 How we chose our preferred sites Stage 1 Strategic Options Review Establish strategic options and identify selected strategy (reported in the Strategic Options Report) Stage 2a Site Assessment Site search & identification of longlist of potential sites (reported in the Longlist Assessment Report) Stage 2b Route Options Assessment Assessment of routes to deliver the strategic sewer (reported in the Emerging Route Options Report) Stage 3 Identification of Preferred Route and Sites Assessment of shortlist of sites (reported in the Shortlist Assessment Report) / Assessment of retained shortlist sites (reported in separate Site Suitability Reports) / Assessment of emerging preferred strategic sewer route option (reported in the Emerg ing Route Options Report Identification of Strategic Sewer Preferred Route Option and Sites (reported in the Preferred Option and Sites Report) Stage 4a Public Consultation Two stages of public consultation and stakeholder engagement Stage 4b Ongoing Scheme Design and Development Ongoing scheme design and development to reflect public consultation feedback, engineering design work and assessment outcomes Figure 1 Stage 5 Selection of Scheme for Planning Application Selection of the scheme for submission of the planning application for permission to build the strategic sewer Counters Creek site selection process How we chose our phase 1 sites Initially, we used a computer model to identify how the sewer system works in the Counters Creek catchment. From this, we identified where flows in the existing sewers need to be collected by the proposed storm relief sewer. The new sewer needed to be made large enough to store a large quantity of sewage flows. The flows could then be pumped gradually back into the existing sewer system for treatment after the storm. However, during intense storms, the large rainwater volumes would fill up the proposed storm relief sewer. The sewage would therefore need to be able to overflow into the River Thames or into the recently approved Thames Tideway Tunnel. We therefore needed a site next to the River Thames. We developed a site selection process to assess and identify the most suitable locations for the construction sites required to build the proposed storm relief sewer, taking account of a wide range of issues including: The need to connect into the existing sewer system The need to connect into identified strategic sewers at the point of most benefit Avoiding existing housing, hospitals and schools Keeping disruption to a minimum in the areas we need to work Keeping additional noise created by our proposed construction sites to a minimum Where possible, avoiding areas that are important to the local community Using modes of transport that minimise disruption for the local community Avoiding existing and planned infrastructure Restricting the number of construction sites Where possible, avoiding sites within areas of protected status, such as heritage sites Finding areas of land that could be used at a reasonable cost 2 Counters Creek storm relief sewer

3 The need to be able to pump excess storm flows into the River Thames during intense storms when the storage capacity of the new storm relief sewer is used up. River sites which also offered an opportunity to connect into the Thames Tideway Tunnel were also a consideration We also identified two search areas: m either side of our anticipated route for the proposed storm relief sewer to search for potential construction sites m either side of our anticipated route for the proposed storm relief sewer to search for potential support compounds to serve the construction site Using these search areas we identified a longlist of 200 sites and assessed them against engineering, environment, property and planning criteria. Following that assessment we rejected 118 of the longlist sites from further consideration as we believed that they were unsuitable due to engineering, environment, property or planning constraints. This left 82 sites for further assessment as part of our short list assessment process. As we worked through our shortlisted sites it became necessary to revise our search areas to take account of the following changes: Confirming that our construction sites needed to be within 15m of the point where we would need to connect into each existing sewer, in order to minimise construction work A better understanding of where we needed to connect into the Hammersmith Storm Relief Sewer (Duplication Branch) and the Counters Creek Mainline Sewer The need to avoid construction and piling work in the Earls Court Regeneration Area The need to avoid the Westfield Shopping Centre The need to avoid the National Grid London Power Tunnel These further reviews and refinement of our search area reduced the number of potential sites from 82 to 20 shortlist sites for assessment. During this shortlist assessment, we used a more detailed range of engineering, environment, noise, planning, property and transport criteria. This resulted in us completing detailed Site Suitability Reports on 12 sites (or combinations of sites). For more detail on the criteria we used to assess potential sites during our longlist and shortlist assessment stages, please see our Longlist Report and Shortlist Report on our website - Preferred site Kensington Olympia car park Five Star Car Wash Shepherd s Bush Upper Addison Gardens Mund Street Cremorne Wharf Depot, Lots Road, Chelsea Proposed use of site Proposed for two drive shafts to launch the tunnel boring machines to drive to the south (Cremorne Wharf Depot), and to the north (Five Star Car Wash and Upper Addison Gardens), and an interception shaft to connect into the Hammersmith storm relief sewer. Proposed site to connect into the Hammersmith storm relief sewer (Brook Green Branch) and to receive the tunnel boring machine driving from the Kensington Olympia car park. Proposed for an interception shaft to connect into the North Kensington and Counters Creek sewers and to receive the tunnel boring machine driving from the Kensington Olympia car park. Proposed for an interception shaft to connect into the North End sewer. Proposed for an interception shaft to connect into the Walham Green sewer and the Low Level no. 1 sewer, a reception shaft to receive the tunnel boring machine driving from the Kensington Olympia car park, and the construction of a pumping station and storm outfall to the River Thames. Table 1 The five preferred construction sites consulted on during our phase 1 consultation Counters Creek storm relief sewer 3

4 How we chose our preferred sites This allowed us to identify our five preferred sites (see Table 1 on page 3 and Figure 2) for consultation through our phase 1 consultation process held between November 2014 and February A key finding from this consultation was that the proposed preferred drive site, the car Kensington Olympia car park, would not be available for us to use as a drive site because of the planned increase in usage of the car park by the land owners to facilitate events at Kensington Olympia. Feedback from land owners and the community requested that we review and consider alternative sites to the Five Star Car Wash, Upper Addison Gardens and Mund Street sites. In February 2015, we also learned that Crossrail 2 had revised its safeguarded route in Chelsea, which allowed us to reduce the depth of the proposed storm relief sewer in this location. This meant that we were able to propose a tunnel route without a change in level and therefore construct the main tunnel using a single drive, rather than the two tunnel drives we had previously proposed. 4 Counters Creek storm relief sewer

5 Shepherds Bush Westfield Shopping Centre Shepherds Bush 4 2 Goldhawk Road HAMMERSMITH Olympia London 1 KENSINGTON AND CHELSEA High Street Kensington KENSINGTON venscourt Park West Kensington Earls Court Gloucester Road South Kensington Barons Court HAMMERSMITH AND FULHAM 3 Earls Court Exhibiton Centre Fulham Broadway Stamford Bridge 5 BARNES Parsons Green Existing sewers Counters Creek sewer Walham Green storm relief sewer Hammersmith storm relief Duplication North End sewer North Kensington storm relief sewer Hammersmith storm relief Brook Green Low Level No 1 sewer Proposed storm relief sewer 1 Proposed construction sites The proposed Counters Creek storm relief sewer Figure 2 Our phase 1 consultation preferred construction sites Counters Creek storm relief sewer 5

6 How we chose our preferred sites How we chose our interim engagement new and alternative sites Between February and May 2015 we completed a review of all the sites we had previously assessed to identify if any should be re-assessed. We also reviewed all the feedback we had received to identify any new sites put forward by respondents, and completed a review ourselves to establish any new sites that should be considered. The outcomes of this work were: The assessment of 24 longlist sites resulted in us identifying 16 sites for further shortlist assessment Having assessed this shortlist, we further tested 10 of the shortlisted sites by completing Site Suitability Reports for these sites. This process confirmed that each of these sites was suitable for use. One of these sites, an interception point to the north of the Kensington Olympia car park site, had already been consulted on during our phase 1 consultation. We then consulted on nine new and alternative construction sites as part of an interim engagement process held in May and June 2015, as shown in Table 2 below and in Figure 3. Feedback from the interim engagement process identified concerns about a number of the sites, which we had consulted on, in particular: Land to the south of Gwendwr Road Rifle Close and Edward Woods Town Park Land at Swanscombe Road and Norland House Sulgrave Road Hammersmith Grove Astrop Terrace Junction at Barons Court Road A number of additional alternative sites were also suggested in the consultation responses we received, and we took the opportunity to consider these through a further round of site assessment work. Potential site Land to the south of Gwendwr Road Junction at Barons Court Road Rifle Close and Edward Woods Town Park Land at Swanscombe Road and Norland House Holland Gardens Addison Crescent Sulgrave Road Hammersmith Grove Astrop Terrace Proposed use of site Possible alternative to Mund Street to connect into the North End Sewer. We could also connect into the Brook Green Sewer from this site (Land to the south of Gwendwr Road). Possible alternative to Mund Street to connect into the North End Sewer. We would also need to connect into the Brook Green Sewer. Possible alternative to Upper Addison Gardens to connect into the existing Counters Creek sewer. Possible alternative to the Kensington Olympia car park (Maclise Road) to connect into the Hammersmith Storm Relief Sewer (Duplication branch). Possible alternative to Upper Addison Gardens to connect into the existing Counters Creek sewer. Possible alternative to the Kensington Olympia car park (Maclise Road) to connect into the Hammersmith Storm Relief Sewer (Duplication branch). Possible alternative to Upper Addison Gardens to connect into the existing Counters Creek sewer. Possible alternative to Upper Addison Gardens to connect into the existing Counters Creek sewer. Possible alternative to Five Star Car Wash to connect into the Hammersmith Storm Relief Sewer and the Goldhawk Road sewer. This site was also proposed as a reception shaft to remove the tunnel boring machine and a drive site for a smaller sewer connection to the west. New interception identified through engineering modelling to connect into the Brook Green Sewer Grove Road Branch one of two alternatives consulted on. New interception identified through engineering modelling to connect into the Brook Green Sewer Grove Road Branch one of two alternatives consulted on. Table 2 The nine new and alternative sites consulted on during the interim engagement 6 Counters Creek storm relief sewer

7 Shepherds Bush Westfield Shopping Centre Shepherds 10 Bush Goldhawk Road KENSINGTON AND CHELSEA High Street Kensington 3 HAMMERSMITH 7 Olympia London 6 KENSINGTON Ravenscourt Park 6 West Kensington Earls Court Gloucester Road South Kensington Baron s Court HAMMERSMITH AND FULHAM Earls Court Exhibiton Centre 16 Fulham Broadway Stamford Bridge BARNES Parsons Green 10 Existing sewers Counters Creek sewer Walham Green storm relief sewer Hammersmith storm relief Duplication North End sewer North Kensington storm relief sewer Hammersmith storm relief Brook Green Low Level No 1 sewer Brook Green sewer Brook Green sewer Grove Road branch 8 Proposed storm relief sewer Phase 1 consultation route of the proposed Counters Creek storm relief sewer New and alternative construction sites 6 The new and alternative sites Our phase 1 proposed construction sites 1 Kensington Olympia car park 2 5* Car Wash Shepherds Bush 3 Mund Street 4 Upper Addison Gardens 5 Cremorne Wharf on Lots Road Figure 3 Our interim engagement new and alternative construction sites Counters Creek storm relief sewer 7

8 How we chose our preferred sites Further site selection work In response to the feedback that we received and as a result of ongoing project development, we repeated the longlist, shortlist and site suitability testing stages of our site selection methodology. This was to ensure we were able to identify a robust project proposal for our phase 2 consultation process and ultimately for submission as part of our planning applications. We also continued our investigations into the opportunities offered by a connection into the Thames Tideway Tunnel and reviewed our hydraulic analysis of the sewer network. This meant we were able to improve the hydraulic performance of the proposed storm relief sewer and remove the need to connect into of some of the smaller sewers. This meant that we no longer needed to connect into the Brook Green Sewer Grove Road Branch in the Hammersmith Grove area, the North End Sewer under North End Road, and the North Kensington storm relief sewer in the Addison Road area. We still need to build an access shaft near North End Road at Talgarth Road and Trevanion Road, and work to connect into the existing Counters Creek sewer at Holland Villas Road and Lower Addison Gardens is also still necessary. Our work also identified that we were unlikely to be able to use the interim engagement sites we suggested at Holland Gardens and at Addison Crescent due to the location of the existing sewer being beneath the property line along Holland Villas Road, which would result in considerable highway work and disruption within Holland Road. We therefore considered a further alternative site in this area at the junction between Holland Villas Road and Lower Addison Gardens. How we chose our preferred sites ahead of our phase 2 consultation The feedback from the interim engagement process identified concerns about a number of the sites which we had consulted on. We have taken the opportunity to consider these concerns and other alternative sites suggested by respondents through the interim engagement process, alongside our ongoing scheme development and modelling work. We also looked at an alternative site to connect into the existing Counters Creek sewer. We completed further longlist and shortlist assessment work between July and October 2015 and concluded that we should prepare Site Suitability Reports for two additional potential construction sites. We also updated Site Suitability Reports for two sites that we considered as part of the phase 1 consultation and interim engagement processes (Tesco Superstore car park, Shepherd s Bush Road and Maclise Road car park and woodland adjacent to Kensington Olympia Station) to reflect potential changes to how we propose to use these sites. We also completed further updating work on our proposals for the use of the Cremorne Wharf Depot site. In November and December 2015 we raised awareness of the five preferred construction sites (shown in Figure 4) we are considering to seek planning permission for ahead of our phase 2 consultation in early Table 3 on page 10 summarises the role of each of the sites. 8 Counters Creek storm relief sewer

9 Shepherd s Bush Westfield Shopping Centre 5 Goldhawk Road 3 KENSINGTON AND CHELSEA High Street Kensington 4 Olympia London KENSINGTON HAMMERSMITH Ravenscourt Park West Kensington Earls Court Gloucester Road South Kensington 2 Barons Court HAMMERSMITH AND FULHAM Earls Court Exhibiton Centre Fulham Broadway Stamford Bridge 1 BARNES Parsons Green Proposed storm relief sewer 1 Cremorne Wharf Depot, Lots Road, Chelsea 2 Land adjacent to Talgarth Road and Trevanion Road, Hammersmith 3 Maclise Road car park and woodland, adjacent to Kensington Olympia Station 4 A section of the car park at Tesco Superstore, Shepherd s Bush Road 5 Holland Villas Road at its junction with Lower Addison Gardens Figure 4 Our five preferred construction sites. Counters Creek storm relief sewer 9

10 How we chose our preferred sites Potential site Land adjacent to Talgarth Road and Trevanion Road Holland Villas Road at its junction with Lower Addison Gardens Tesco Superstore car park, Shepherd s Bush Road Maclise Road car park and woodland adjacent to Kensington Olympia Station Cremorne Wharf Depot, Lots Road, Chelsea Table 3 The five preferred sites for our phase 2 consultation Proposed use of site Proposed site for an access shaft to provide safe access to and from the proposed storm relief sewer during inspection and maintenance operations. Proposed for an interception shaft to connect into the existing Counters Creek sewer and to receive the tunnel boring machine driving a smaller tunnel from the south west (Maclise Road car park and woodland adjacent to Kensington Olympia Station). Proposed site for an interception shaft to connect into the Hammersmith Storm Relief Sewer (Brook Green Branch) and to receive the tunnel boring machine driving from the south (Cremorne Wharf Depot, Lots Road, Chelsea) Proposed for an interception shaft to connect into the Hammersmith Storm Relief Sewer (Duplication Branch), for a drive shaft to launch the tunnel boring machine to drive a smaller tunnel to the north east (Holland Villas Road) and for the provision of a permanent air management building. Proposed for a drive shaft to launch the tunnel boring machine to drive to the north (Tesco Superstore car park, Shepherd s Bush Road), and an interception shaft to connect into the Walham Green sewer and the Low Level No. 1 interceptor sewer and for the construction of a permanent pumping station. 10 Counters Creek storm relief sewer Counters Creek storm relief sewer 10

11 Counters Creek site selection process and outcomes Figure 5 shows a summary of our site selection process and the outcomes of each stage. Figure 5 - Counters Creek site selection process and outcomes Counters Creek storm relief sewer 11

12 Related documents The following documents are available at our drop-in sessions and to download from the document library on our website - Phase 1 consultation and engagement process Feedback from our phase 1 consultation and engagement process Phase 1 Consultation and Engagement Process Feedback Report Project information Being a good neighbour Environment Getting planning permission Have your say How we would build the proposed storm relief sewer Transport Timing Tunnel drive strategy Why we need the Counters Creek storm relief sewer Site information Cremorne Wharf Depot, Lots Road, Chelsea Land adjacent to Talgarth Road and Trevanion Road, Hammersmith Maclise Road car park and woodland adjacent to Kensington Olympia Station Holland Villas Road at its junction with Lower Addison Gardens Tesco Superstore car park, Shepherd s Bush Road Site Suitability Reports Cremorne Wharf Depot, Lots Road, Chelsea Land adjacent to Talgarth Road and Trevanion Road, Hammersmith Maclise Road car park and woodland adjacent to Kensington Olympia Station Holland Villas Road at its junction with Lower Addison Gardens Tesco Superstore car park, Shepherd s Bush Road Project contact details: Web: consultations@thameswater.co.uk Phone: , option 2 Ref: BB Postal address: Counters Creek sewer flooding alleviation scheme consultation, Freepost RTHE-CJYYCXCJ, 7 St Peter Street, Winchester SO23 8BW

Why we need the Counters Creek storm relief sewer

Counters Creek storm relief sewer Why we need the Counters Creek storm relief sewer The problem The sewer network we operate today has been much improved and vastly extended over the years and remains