UXO risk in large marine construction projects

Transkript

1 UXO risk in large marine construction projects Requirements to UXO risk assessement Jens Colberg-Larsen Energinet.dk Dato - Dok.nr. 1

2 Agenda Requirements to UXO risk assessement 1. Why is the marine UXO risk relevant to Energinet.dk Projects Seabed activities 2. How do we (try to) manage the marine UXO risk Desk Study Risk Assessment 2

3 Energinet.dk Danish TSO Transmission System Operator Energinet.dk own and operate The high voltage electricity transmission grid The gas transmission grid Energinet.dk is responsible for Maintaining and building new international power connections Building platform and export cables for offshore wind farms Developing new Danish offshore windfarms towards tender for license 3

4 Offshore projects Completed Examples: SK4 (2013) Lillebælt (2013) Anholt Export Cable (2012) Dato - Dok.nr. 4

5 Offshore projects Ongoing Examples: Kriegers Flak Wind farm Horns Rev 3 Wind farm Nearshore Wind Farms COBRA Konti-Skan 1 Øresund, 400 kv Anholt Ø Dato - Dok.nr. 5

6 Construction activities Mechanical interaction with seabed Cable projects: Jetting, Trenching, Ploughing, Diving, Geotechnical investigations, Anchoring Platform and Wind turbines: Jack-up, Pilling, Dredging, Geotechnical investigations, Anchoring 6

7 Construction activities Cable protection by use of a high-pressure ROV Preparing a cable trench 7

8 Construction activities Jack-up Subsea cable ploug 8

9 The UXO threat Mines, Bombs, Artillery, Dumpings, Work in prohibited zones need special procedure (DMA) The Builder / Developer must investigate threats and restrictions prior to offshore activities (DMA, Announcement 1351, 29/11/2013 on offshore works and marine safety) Restricted area Prohibited area 9

10 UXO Desk Study Purpose Manage risk and assess costs Content Investigation of potential UXO pollutions Mitigation plan Risk Assessment Output Report, Charts and GIS deliverables Use Project planning Potential mitigation Project risk management Contractors Authorities 10

11 Requirements Study of UXO pollution Nature of UXO polluting activity Mining, Bombing, Firing practice areas, Wreck, When WWI, WWII, Recent, Charateristics of the UXO items Dimensions, Nominal charge, Material (Fe), Trigger, Expected condition, Where Geographical limitation of pollution, GIS Assessment of migration and burial Effects of dynamic seabed 11

12 Consequence Requirements Risk Assessment For each type of seabed interaction the risk must be evaluated for every identified UXO item that pose a threat to the area of investigation. The purpose of the risk assessement is to help decide When to react When to accept the risk intiate mitigating activities on a transparent data basis Common approach to use a risk matrix Risk = P X C Risk unacceptable Risk tolarable (ALARP) Risk acceptable Probability 12

13 Consequence Requirements Risk Assessment Consequence Human casualties and costs Company dependent Probability Theoretical Number of incidents pr. time (estimate from UXO consultant) Probability Probability Operational Spatial density of UXO items Activity type seabed interaction Other factors?? Geographical correlation 13

14 What we don t want Seabed operations not advisable Anchoring not advisable Questions? 14

15 BEK (DK) Offshore arbejder og sejladssikkerhed 15

16 Tilladelse til arbejde i forbudsområder (SFS) I Søfartsstyrelsens (SFS) bekendtgørelse nr. 135 af 4. marts 2005 om forbud mod sejlads, ankring og fiskeri mv. i visse områder i danske farvande, er der visse områder af danske farvande fare på grund af udlagte miner og andre sprængstofholdige genstande. For at Søfartsstyrelsen kan give dispensation fra forbuddet mod sejlads i sådanne områder skal denne procedure følges: 1. Den korridor i forbudsområdet som skal undersøges i forbindelse med et kommende kabelarbejde, skal indledningsvis forundersøges og kontrolleres for udlagte miner og andre sprængstofholdige genstande. En plan for denne forundersøgelse og arbejdsmetode skal sendes til SOK/Minørtjenesten for godkendelse, med kopi til Søfartsstyrelsen. Koordinaterne for korridoren skal angives i datum WGS 84 og der skal gives oplysninger om det til formålet anvendte skib eller fartøj. 2. Når SOK/Minørtjenesten skriftligt har godkendt forundersøgelsesplanen, med kopi til SFS, kan SFS give tilladelse til, at der sejles i korridoren med det formål at foretage en undersøgelse for udlagte miner og andre sprængstofholdige genstande. Ved fund af eventuelle genstande følges retningslinjerne fra SOK/Minørtjenesten. Forundersøgelsen skal endvidere angive i hvilken dybde under havbunden der er undersøgt. 3. Resultaterne af forundersøgelsen sendes til SOK/Minørtjenesten som herefter skal godkende, at der efterfølgende kan foretages sejlads med større skibe, eventuelle mere dybdegående kabelundersøgelser i området samt efterfølgende arbejder i havbunden til den undersøgte dybde. Søfartsstyrelsen vil herefter skriftligt meddele tilladelse til, at der sejles i korridoren for at udføre de planlagte arbejder. 16