FOR THE PROTECTION OF THE HARBOUR AUTHORITY  PART 5 “accumulation” means any accumulation of silt or other material (including any materials used  to construct the authorised development) which constitutes an impediment to navigation at or  in the approaches to Lowestoft Harbour;  53.  For the protection of the harbour authority the provisions of this Part of this Schedule, have  effect unless otherwise agreed in writing.  54.  In this Part of this Schedule—  “erosion” means any erosion of the bed or banks of the lake or any quay or jetty or other  structure of whatever nature within Lowestoft Harbour;  “plans” includes sections, descriptions, drawings, specifications, proposed method statements  and hydraulic information, including but not limited to information as to the discharge of  water and materials;  “port land” means any land in Lowestoft Harbour held by the harbour authority for the  purposes of its statutory undertaking; and  “specified work” means any tidal work or any other work or operation authorised by this  Order on port land or which may affect port land or navigation in respect of Lowestoft  Harbour of the functions or the harbour authority in relation to the operation of Lowestoft  Harbour.  55. —(1) The undertaker must not, under the powers conferred by this Order, temporarily  possess, acquire or use, or acquire new rights over, port land without the consent of the harbour  authority.  (2) The undertaker must not exercise the powers conferred by article 17 (authority to survey and  investigate land) or the powers conferred by section 11(3) (powers of entry) of the 1965 Act in  respect of any port land without the consent of the harbour authority.  (3) The powers conferred by article 29 (power to override easements and other rights) do not  apply to any rights held by the harbour authority for the purpose of its statutory undertaking,  except with the consent of the harbour authority.  (4) The consent of the harbour authority under this paragraph must not be unreasonably  withheld but may be given subject to reasonable conditions.  (5) If the harbour authority fails to express its refusal or approval of any request for a consent  under—  within 30 days of such a request having been delivered to it, and the harbour authority has not  requested an extension of time to give its consent from the undertaker prior to the expiration of the  30 days which the undertaker has granted, acting reasonably, such a request is deemed to have  been refused by the harbour authority.  (6) If the harbour authority fails to express its approval of any request for a consent under sub- paragraph (1), (2) or (3) at the expiration of the extension of time granted by the undertaker under  sub-paragraph (5), such a request is deemed to have been refused by the harbour authority.  (2) Any approval of the harbour authority under this paragraph—  (a) sub-paragraph (1) in respect of temporary possession powers;  (b) sub-paragraph (2); or  (c) sub-paragraph (3),  (a) must not be unreasonably withheld;  (b) may be given subject to such reasonable requirements as the harbour authority may make  for the protection of Lowestoft Harbour and navigation within Lowestoft Harbour and the  141 56. —(1) At least 56 days before commencing the construction or maintenance of any specified  work, the undertaker must submit to the harbour authority plans of that work for its approval. 