The Silvertown Tunnel Order 2018

Structural integrity of flood defences

55.—(1) Prior to commencing the first authorised work likely to impact a flood defence and at least at the same time as submitting any submissions for approval in respect of the first specified work under paragraph 56, TfL must prepare at its own expense and provide to the Agency (for its approval where stated below), the following documents in the corresponding order (but nothing precludes TfL from submitting more than one document to the Agency at a time)—

(a) a schedule of defects existing in the flood defences including, where reasonably practicable, a description of the magnitude of any defect;

(b) a survey plan, for approval by the Agency, to include details of any further surveys and intrusive investigations of the flood defences proposed to be undertaken by TfL to inform the detailed design process, construction methodology and mitigation proposals;

(c) an assessment report, to—

(i) include details of the structural integrity of the flood defences in light of any proposed authorised works;

(ii) include asset control limits of any sections of the flood defences;

(iii) identify any sections of the flood defences requiring protective works by reason of the authorised works; and

(iv) identify any section of the flood defences that are not a fit for purpose flood defence,

such report to be based on the findings of the additional surveys carried out by TfL under the survey plan under paragraph (b), the schedule of defects provided under paragraph (a) and any available historical information;

(d) a mitigation design report (or reports), for approval by the Agency, to include details of the protective works identified by the assessment report provided under paragraph (c) that—

(i) are necessary before; or

(ii) may be required to be implemented as an action under the emergency preparedness plan provided under paragraph (f) during or after,

the construction of the authorised development and that such details will—

(aa) be sensitive to the foreshore and hydraulic regime; and

(bb) not prevent the relevant sections of the flood defences being raised to TE2100 levels in future and such standards being maintained;

(e) an instrumentation and monitoring plan, for approval by the Agency, to include, in respect of the flood defences—

(i) details of monitoring locations (which must be established having regard to the asset control limits);

(ii) details of monitoring in respect of scour of any flood defence within the Order limits;

(iii) the frequency of monitoring (which must, as a minimum, be until—

(aa) the rate of settlement experienced by the flood defences directly attributable to the authorised development ceases or is less than or equal to 2 millimetres per annum; or

(bb) the period of 2 years has expired following the completion of the authorised development (whichever is later); and

(iv) the minimum amount of baseline monitoring; and

(f) an emergency preparedness plan, for approval by the Agency, to include details as to what actions TfL will take, including the implementation of any mitigation identified in the mitigation design report (or reports) approved under paragraph (d), in respect of the asset control limits identified in the assessment report provided under paragraph (c), including timescales and the hierarchy of actions.

(2) TfL must implement and act in accordance with the approved structural integrity plans.

(3) Any protective work identified as being required by the structural integrity plans is to be treated as a specified work for the purposes of this Part of this Schedule.

(4) Following completion of the authorised development, TfL must prepare at its own expense and provide to the Agency, a completion report, to include details of—

(a) any modifications or mitigation measures to be implemented in respect of the flood defences;

(b) illustrations in respect of the interactions between ground movement relating to the flood defences and construction activities;

(c) actual ground movement in respect of the flood defences compared to predicted ground movement;

(d) the results of a post-construction defects survey but only in relation to any differences identified when compared to the schedule of defects provided to the Agency under sub-paragraph (1)(a);

(e) any remedial works undertaken by TfL to the flood defences; and

(f) final as-built drawings and plans of the parts of the authorised development situated within 16 metres of a flood defence.