The International Marine Contractors Association has published new guidance on cable burial for offshore wind farms.
The ‘Guidelines for the Measurement of Depth of Burial’ (IMCA S 029) is aimed at both the offshore renewables and offshore oil and gas industries, and looks at the different methods of measuring the depth of burial of subsea cables and pipelines together with factors influencing the depth of burial.
It also includes measuring the thickness of an embankment of crushed rock on top of a pipeline or cable; and provides guidance on measurement of depth of lowering – including explanation of the difference between lowering and burial or cover.
Subsea pipelines and cables are commonly buried in the seabed or covered with crushed rock to give them protection from anchoring and bottom trawling, said IMCA.
They can also be buried/covered to maintain an operating temperature and, in the case of pipelines, to be restrained from upheaval buckling.
Some pipelines and cables are left exposed on the seabed to permit thermal expansion or left in an open trench designed to protect the line from passage of an anchor or trawl.
‘Depth of Burial’ or ‘Depth of Cover’ becomes a contractual requirement and therefore needs to be measured with equipment and procedures that produce results of known accuracy. IMCA S 029 gives clarity to this important topic, said IMCA.
Technical director Stephen Peet said: “Like all IMCA guidance this new document has been produced by a specially convened working group from members of the Offshore Survey Division – all experts in the field.
“The 67-page document,, which looks at the different methods of measuring the depth of burial of subsea cables and pipelines together with factors influencing the depth of burial, is relevant for both offshore renewables and offshore oil and gas.”