Site information paper information Site Putney Bridge Foreshore Introduction Currently, untreated sewage regularly overflows into the River Thames from London’s Victorian sewerage system via combined sewer overflows (CSOs). The proposed Thames Tunnel would intercept these overflows through the use of a new storage and transfer tunnel, which would link west London and Abbey Mills Pumping Station. The sewage flow would then be transferred to Beckton Sewage Treatment Works via the Lee Tunnel. The reduction in untreated sewage entering the River Thames would bring long-term benefits for the environment and users of the River Thames. In order to deliver the project we need a number of sites along the route and this document identifies our current preferred site at Putney Bridge Foreshore. Key facts Local authority: Wandsworth CSO name: Putney Bridge CSO spill volume in an average year: 68,000m³ (equivalent to approximately 27 Olympic swimming pools) Site type: CSO site Duration of main construction works: Approximately three and a half years. Thames Tunnel 1 Putney Bridge Foreshore Section 1: Introduction and site information We are proposing to use the foreshore of the River This site information paper sets out our proposals at Thames, to the west of Putney Bridge, for this Putney Bridge Foreshore. We have also produced project construction work and to accommodate permanent information papers, which cover overarching topics structures required to operate the main tunnel. The site relating to the project. Where we consider that a project would be used to connect the existing local CSO, known information paper is particularly relevant, we have as the Putney Bridge CSO, to the main tunnel. highlighted this in a related documents box. At the end of this site information paper is a list of other documents, The location of the site is shown in Figure 1A. The site is which may be of interest and a glossary of terms. located in the foreshore of the River Thames, between Putney Pier and Putney Bridge. It is also north of the junction of Lower Richmond Road and Embankment. The site is within the Putney Embankment Conservation Area. Beyond Lower Richmond Road to the south are residential Related documents: properties. To the south east is Putney High Street (A219) and Grade II* listed St Mary’s Church. The site includes Build the existing slipway, which is located to the west of Putney Bridge. A temporary, replacement slipway would be constructed for the duration of our Putney Bridge CSO construction works. This would be located approximately 300m west of Putney Bridge, close to the business premises of Chas Newens Marine. The location of the replacement slipway is shown in Figure 1A. 2 Introduction Draft limit of land to be acquired or used Proposed tunnel route – centreline HAMMERSMITH & FULHAM Local authority boundary Existing sewer Embankment Existing CSO Putney Pier Lower Richmond Road Putney Bridge Putney Bridge CSO Waterman’s Green St Mary’s WANDSWORTH Church t e e r t S Putne h y Bridg y Hig e R oad Putne N Figure 1A: Putney Bridge Foreshore location plan 3 Putney Bridge Foreshore How we chose this site What we proposed at phase one consultation What we are proposing at phase two consultation Through our site selection process, we identified four We have considered the comments from phase one possible shortlisted sites to intercept the Putney Bridge consultation, feedback from ongoing engagement and CSO. At phase one consultation, which was held between new information; and undertaken further technical work. September 2010 and January 2011, we presented these We still consider that Putney Bridge Foreshore upstream sites: of Putney Bridge, should be our preferred site because it would not have a direct effect on the setting of the Grade • Foreshore, end of Brewhouse Lane II* listed St Mary’s Church, it would have better vehicular • Foreshore, adjacent to Putney Bridge and access than the sites to the east and would avoid a St Mary’s Church pedestrian area. • Junction of Lower Richmond Road and Putney Embankment • Putney Bridge Foreshore. The location of the site is restricted by the configuration Related documents: of the Putney Bridge CSO, which splits into two outlets beneath the southern arch of the Putney Bridge. Since Q&A Consultation both outlets need to be intercepted, the interception point cannot be located inland and therefore a site in the foreshore of the River Thames is required. Site selection Putney Bridge Foreshore was identified as our preferred site at phase one consultation. 4 Construction Section 2: Construction Construction activities Construction activities are required to intercept the Figure 2A illustrates the below ground infrastructure CSO. We would construct an interception chamber to proposed. These activities would take place within the intercept the CSO. A connection culvert would link the area indicated by the red line in Figure 1A, in five main interception chamber to a drop shaft (approximately phases, lasting approximately three and a half years in 37m deep) through which flows would pass down to total. The main construction activities at this site are set a short connection tunnel. This would then join to the out in Table 2.1. main tunnel. Connection culvert Existing overflow sewer Construction Short connection tunnel Valve chamber Existing Interception overflow to river chamber Drop shaft Main tunnel Figure 2A: Illustration showing typical elements of below ground infrastructure 5 Putney Bridge Foreshore Phase 1 Advance works Site setup Table 2.1: Main activities during construction phases Figure reference Figure 2C Figure 2D Typical working hours Varies Standard Utilities connected ü Utilities diverted or protected ü Temporary slipway constructed ü Site cleared ü Temporary works in River Thames constructed ü Site facilities and access set up ü Drop shaft excavated and built Short connection tunnel excavated and built Above and below ground structures constructed Mechanical and electrical equipment installed Temporary works in the River Thames removed Main construction activities Main construction Temporary slipway removed Site restored and landscaped Temporary site facilities removed Our typical working hours are expected to be: * Standard working hours would also include, subject to Standard: 8am-6pm weekdays, 8am-1pm Saturday* agreement with the local authority: – a short period (up to one hour) before works start and Extended standard: 6pm-10pm weekdays, 1pm-5pm Saturdays after they have finished to allow our workers to Continuous: 24 hours a day, seven days a week** prepare for work and check the site. Varies: Working hours for advanced works will – equipment and machinery maintenance could also depend on the nature of the works and will take place 1pm-5pm Saturday and 10am-4pm be agreed with the local authority Sunday. ** The main activities taking place 24 hours a day are below ground or within an enclosure. 6 Construction Phase 2 Phase 3 Phase 4 Phase 5 Drop shaft Tunnelling Construction Completion of construction of other works and site structures restoration Figure 2E Figure 2E Figure 2F – Standard Continuous Standard Standard ü ü ü ü ü ü ü ü Related documents: Build Managing construction 7 Putney Bridge Foreshore Site layout and construction phases Figures 2C, 2D, 2E and 2F show how the site might be • Since phase one consultation, this site has moved laid out during the construction phases, which are set further west, away from Putney Bridge, to ensure out in Table 2.1 and Figure 2B. These layouts have been the listed bridge is protected. Moving the site further informed by the size of the infrastructure proposed, west also allows us to minimise the footprint of the the construction methods required and the location permanent works after construction and retain the of neighbouring buildings and structures. They have alignment of the existing slipway. also been developed to minimise effects on the local The site layouts are indicative only, and the contractor community and environment. Particular factors at this site may arrange the site in a different way, depending on that have influenced the layout are as follows: the chosen construction methods, provided that any • Since phase one consultation, a temporary replacement environmental effects are appropriately managed and slipway is now proposed upstream of the site, that the main construction activities are undertaken approximately 300m west of Putney Bridge, to ensure within the red line shown in Figure 1A. that recreational and commercial river users are not adversely affected during construction. Year 1 Year 2 Year 3 • Timber hoarding is proposed on Waterman’s Green to limit our worksite to the western part and provide protection from construction for users of Waterman’s Advance works P1 P3 P5 Green. The vaults emergency access would be P2 P4 maintained and their use unaffected should existing planning permissions to convert them into cafes or restaurants be implemented. Figure 2B: Construction timeline showing approximate duration of works in phases (P) 8 Construction HAMMERSMITH & Maximum extent of FULHAM construction site for advance works Jack up barge servicing Site hoarding piling operations Cofferdam Temporary Local authority boundary cofferdam to enable construction Site support/welfare of slipway Internal site road Site access Slipway Existing Thames Path Thames Path diversion WANDSWORTH N Figure 2C: Illustrative advance works construction plan 9 Putney Bridge Foreshore HAMMERSMITH & Maximum extent of FULHAM construction