Development Consent Order Application Response to ExA’s First Written Questions: 8.11 Principal Issue: Dredging and Navigation The Infrastructure Planning (Examination Procedure) Rules 2010 November 2016 Silvertown Tunnel Response to ExA’s First Written Questions: Dredging and Navigation THIS PAGE HAS INTENTIONALLY BEEN LEFT BLANK Page 2 of 32 Silvertown Tunnel Response to ExA’s First Written Questions: Dredging and Navigation Silvertown Tunnel Development Consent Order Application Response to ExA’s First Written Questions: Dredging and Navigation Document Reference: 8.11 Internal Code: ST150030-PLN-ZZZ-ZZ-REP-ZZ-0141 Author: Transport for London Rev. Date Approved By Signature Description 0 15/11/2016 David Rowe (TfL For Deadline 1 Lead Sponsor) Page 3 of 32 Silvertown Tunnel Response to ExA’s First Written Questions: Dredging and Navigation THIS PAGE HAS INTENTIONALLY BEEN LEFT BLANK Page 4 of 32 Silvertown Tunnel Response to ExA’s First Written Questions: Dredging and Navigation Contents DN DREDGING AND NAVIGATION ................................................................... 6 DN.1 Question .................................................................................................... 6 Response ............................................................................................................... 6 DN.2 Question .................................................................................................... 8 Response ............................................................................................................... 8 DN.3 Question .................................................................................................. 12 Response ............................................................................................................. 12 DN.4 Question .................................................................................................. 14 Response ............................................................................................................. 14 DN.5 Question .................................................................................................. 16 Response ............................................................................................................. 16 DN.6 Question .................................................................................................. 17 Response ............................................................................................................. 17 DN.7 Question .................................................................................................. 19 Response ............................................................................................................. 19 DN.8 Question .................................................................................................. 20 Response ............................................................................................................. 20 DN.9 Question .................................................................................................. 22 Response ............................................................................................................. 22 DN.10 Question ............................................................................................... 23 Response ............................................................................................................. 23 DN.11 Question ............................................................................................... 25 Response ............................................................................................................. 25 DN.12 Question ............................................................................................... 26 Response ............................................................................................................. 26 DN.13 Question ............................................................................................... 30 Response ............................................................................................................. 30 Appendix A. Safeguarded Wharves Review .................................................... 32 Page 5 of 32 Silvertown Tunnel Response to ExA’s First Written Questions: Dredging and Navigation DN DREDGING AND NAVIGATION DN.1 Question (a) What is the maximum depth of dredging that would be required for the construction of the temporary jetty? (b) How would the maximum depth of dredge be secured in the dDCO? (c) What is the duration of the dredging and jetty construction activities? Response Response Part (a) DN.1.1 Clause 4.4.76 and Appendix B of the CMS (APP-046) envisage that up to 3m of material will be dredged from the river bed (including a 0.5m over dredge allowance). This is the depth that has been assessed in the ES. DN.1.2 But, as set out in the CMS (APP-046) the requirement for and exact depth of any dredging will not be known until after the completion of the detailed design of the temporary works. DN.1.3 Clause 7.3.37 of the CMS (APP-046) identifies that there are a number of options for configuring the ship and barge loading facilities and the specific details, including dredging depth, will be developed by the Contractor. DN.1.4 The Applicant is currently discussing the issue of dredging depth with the PLA. Response Part (b) DN.1.5 Controls on dredging depth are secured in the dDCO (APP-013) through the plan approval role contained within the protective provisions for the PLA and through the method statement approval mechanisms within the dDML (see the response to DN6). Response Part (c) Page 6 of 32 Silvertown Tunnel Response to ExA’s First Written Questions: Dredging and Navigation DN.1.6 The detailed envisaged programme of activities, including dredging and jetty construction, is presented in Appendix C “Envisaged Construction Programme” of the CMS (APP-046) The duration of dredging and jetty construction activities have been based on experience of projects of a similar nature and scale. The actual start and end dates for the activities may vary subject to the Contractor’s actual construction programme. The likely timing and durations of the dredging and jetty construction activities are as follows: Dredging is needed to create low water access to the jetty. To enable access to the full dredge envelope, dredging will be carried out prior to the jetty construction. Activity ST.1008 in the programme envisages that dredging is anticipated to last 30 calendar days. Jetty construction will start upon completion of dredging. The piled structure and commissioning is expected to take 70 days to complete. This work is shown as activity ST.1010. Activity ST.1005 identifies river wall strengthening for jetty installation (if required). This pre-jetty construction work is anticipated to last for 20 days. As set out in CoCP (8.1.3), the Contractor’s construction programme will be agreed so that “Any planned (i.e. non-emergency) dredging work must avoid the period of June-August inclusive.” Page 7 of 32 Silvertown Tunnel Response to ExA’s First Written Questions: Dredging and Navigation DN.2 Question During the proposed dredging and jetty construction, would any other users of the river be impacted? Please provide details and estimated timescales for each activity/river user that would be impacted. Response DN.2.1 Construction of the jetty at Thames Wharf (if selected by the Contractor) will entail dredging of the river bed in the vicinity of the proposed jetty, piling and other works requiring barge or other marine plant access, and working within the river ('Jetty Construction'), and is envisaged to take place from December 2019 to March 2020. DN.2.2 The interface between these construction works and organisations operating from the existing Thames Wharf, and other organisations using the river Thames, has been recognised and addressed by the Applicant. DN.2.3 The development of the envisaged construction methods, the Reference Design and development of the dDCO provisions have been informed by user engagement and consultation, navigable interest surveys of users of the river Thames, and particularly close and continuous liaison with the PLA and GLA (as owners of the adjacent land) throughout Scheme development. DN.2.4 The use of the river (including use by marine equipment required for the Scheme’s construction activity) is controlled by the PLA. In TfL’s extensive engagement with the PLA on such issues, the need for a Navigational Interests Risk Assessment has been identified as a mechanism by which PLA can ensure risks of marine use on the river are adequately controlled. DN.2.5 Whilst usually prepared and submitted to PLA closer to commencing river use, TfL have prepared a draft of this document, known as the 'Navigation Issues and Preliminary Risk Assessment ('NIPRA') (APP-054) and submitted this with the DCO application to reflect the preliminary design stage, having discussed its contents with the PLA. DN.2.6 Together the NIPRA, the dDCO and specifically the Protective Provisions for the benefit of PLA, address the need to maintain operation of all navigable interests in the Thames. Page 8 of 32 Silvertown Tunnel Response to ExA’s First Written Questions: Dredging and Navigation DN.2.7 The Applicant is seeking powers through the dDCO for the construction of a jetty and for the re-use of the Thames Wharf NAABSA berth (not always afloat but safe aground) to enable the Applicant to fulfil its commitments