Decommissioning - Navigation

• Petroleum Act 1998
• Petroleum Act 1987
• Coast Protection Act 1949
• Continental Shelf Act 1964

• UN Convention on the Continental Shelf 1958
• Food and Environment Protection Act 1985 (FEPA)

• Revised Guidance Notes on the Decommissioning of Offshore Oil and Gas Installations and Pipelines

The Guidance Notes are intended to help companies understand their liabilities and the process for approval of decommissioning programmes. They have been updated to take account of both the experience gained since 2006 and the relevant decommissioning provisions in the Energy Act 2008.

It is the Operator's responsibility to notify change in status of decommissioned installations and pipelines so that mariners may be advised and appropriate amendments made to charts.

In addition the Hydrographic Office Radio Navigation Warnings (RNW) section should be contacted 24 hours in advance of offshore activity concerning the removal and tow of platforms, FPSOs and other surface structures. The RNW section will provide information on details required.

There are also specific marking and notification requirements where concrete installations, footings of a steel installation or a pipeline remain in place (see Performance Standards).

Also see Performance Standards for requirements around Safety Zones.

Notifications must be made in writing to:

The United Kingdom Hydrographic Office
Seabed Data Centre (Offshore Installations)
Admiralty Way
Taunton
Somerset
TA1 2DN

Hydrographic Office Radio Navigation Warnings (RNW) section can be contacted 01823 353448 or navwarnings@btconnect.com

6 weeks in advance of change in status of decommissioned installations and pipelines

Radio Navigation Warnings - 24 hours in advance of tow

Where it is agreed that a concrete installation, or the 'footings' of a steel installation, or pipeline should remain in place the operator must ensure that the position (horizontal datum to be stated), surveyed depth and dimensions of the remains are forwarded immediately to the Hydrographic Office, for inclusion on Admiralty charts. 

It is the operator’s responsibility to install and maintain navigational aids for any remains of concrete installations that project above the surface of the sea. The nature of the navigational aids to be employed should be discussed with DECC, the relevant lighthouse authorities and with interested parties such as fishermen and other mariners. It is the operator's responsibility to ensure the maintenance of any such navigational aids. Details of the action to be taken to advise mariners and mark any remains should be included in the Decommissioning Programme; the Hydrographic Office should be kept informed.

Drill cuttings accumulations will only be marked on Admiralty charts if it is considered that they present a danger to surface navigation or alter the charted seabed depth significantly. In such cases they would be recrded as a 'foul' or 'shoal depth'. Details of any cuttings piles that may fall into this category should be discussed with the Hydrographic Office.

Upon completion of decommissioning operations, appropriate surveys should be undertaken to identify and recover any debris located on the seabed, which has arisen from the decommissioning operation or from past development and production activity. The area to be covered is likely to vary from case to case but the minimum required will be a radius of 500 m around the location of the installation or any remains.

Following the removal of any debris, independent verification of seabed clearance should be obtained. The usual method of achieving this is to engage a fishing vessel to carry out a trawl of the area and to issue a certificate of seabed clearance. Any debris removal activities and any subsequent trawl of the area will need to take account of the presence of drill cuttings.

Section 36 of the Coast Protection Act 1949 makes non-compliance with the requirements of Section 34 or any conditions imposed within consents granted an offence. The Minister of Transport may serve notice to remove works or make alterations within a stated period (not less than 30 days).