maw01 cable risk assessment hazard workshop...the findings of this workshop will then be used to...

MAW01 Cable Risk AssessmentHazard Workshop

Anatec

8th-9th November 2018

Introduction Ørsted are carrying out a Cable Burial Risk Assessment (CBRA)

for the export and inter-array cables associated with the BayState Wind Offshore Wind Farm.

The aim of this workshop is to provide a qualitativeassessment of the potential hazards to the cables and get keylocal stakeholder input.

Provide an overview of the approach/process being followed.

The findings of this workshop will then be used to inform thequantitative risk assessment. This will include the risk fromvessel anchors and any other key hazards identified (e.g. riskfrom fishing gear).

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AgendaItem Description

1 Welcome and Introductions

2 Project Overview & Workshop Methodology Description

3 Review of Baseline (inc. marine traffic survey data)

4 Discussion of Potential Hazards for each Cable Zone

5 AOB / Close out

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Project Overview

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Guidance BOEM – Offshore Electrical Cable Burial for Offshore Wind

Farms on the OCS Includes guidance on burial depth vs capacity, special considerations,

route selection, navigation risk assessment, cable protection

BOEM – Offshore Wind Submarine Cable Spacing Guidance

DNV/GL – RP0360 – Subsea Power Cables in Shallow Water.

Carbon Trust Guidance for carrying out Cable Burial Risk Assessment

COP Guidelines Provides guidance on information requirements for a COP for OCS

renewable energy activities on a commercial lease. Nothing directlyrelated to cables

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CBRA Methodology (Carbon Trust) Cable Routeing

Desktop study, suitable landfall, minimise cable length Avoid busy shipping areas, anchorage areas, dredging areas

Collation of Data Natural – Geophysical and geotech surveys, bathymetry, metocean data Anthropogenic – AIS data, fishing data, navigational charts, recreational data, UXOs

Assessment of Seabed Conditions Seabed features, mobile sediment, soil density

Quantitative Risk Assessment (where deemed necessary) Probabilistic assessments of risk to cable from vessel anchors (anchor dragging,

emergency anchoring) and from fishing gear Used with anchor and fishing gear penetration models to provide burial

recommendations

Burial Depth Recommendations

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Hazard Review Process

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Identify Hazard

Identify Causes

Identify Mitigations

Rank by frequency and consequence

Agree Residual Level

of Risk

Cable Interaction Hazards

The following list presents potential hazards to the cable : Fishing gear snags on cable

Anchored vessel drags anchor onto cable

Vessel suffering engine failure anchors onto the cable

Vessel inadvertently anchors onto the cable

Foundering vessel sinks onto or damages cable

Dredging activity damages cable or causes cable(s) to become exposed

Military activities damage the cable(s)

Recreational activities damage the cable(s)

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Natural Hazards

The following list presents potential natural hazards to thecable : Seabed mobility causes cable to become exposed

Seabed obstructions/boulders

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3rd Party Requirements The following issues also require to be considered with respect

to cable burial: Bridges

Dredged / Maintained Channels

Electromagnetic Effects (Navigation and Organisms)

Moorings for recreational craft

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Sample Causes The following provides a sample of potential causes to the

hazards: High levels of fishing activity

Vessels at anchor near cable

Bad weather

High levels of shipping - emergency/inadvertent anchoring risk

Dredging activity

Out of date charts

Recreational activity

Military activity

Sand waves / ripples

Human error

UXOs / seabed obstructions

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Risk Ranking Methodology

Rank Frequency

1 Negligible

2 Extremely Unlikely

3 Remote

4 Reasonably Probable

5 Frequent

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The definitions presented in the following table will be used to evaluate the “frequency of occurrence” for each impact:

Risk Ranking Methodology

Rank Description People Property Environment Business

1 Negligible No injury No damage No effect No impact

2 Minor Minor injury Minor damage Minor effect Minor impact

3 Moderate Major injury Moderate damage

Moderate effect

Considerableimpact

4 Major Single fatality Major damage Major effect Major national impact

5 Serious Multiple fatalities

Extensive damage

Extensive effect

Major international impact

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The definitions presented in the following table will be used to evaluate the “severity of consequence” for each impact:

Risk Assessment for Burial Recommendations

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Determination of the consequence (consequence ranking)

Determination of acceptable risk criteria (e.g. for a seriousconsequence the acceptable frequency may be extremelyunlikely)

Quantification of likelihood for different burial depths Recommend the depth needed to meet the acceptable risk criteria

(where feasible).

For fishing activity Orsted will consider both Human Safety andeconomic consequences.

For anchor strike – the consequences are only considered tobe economic.

Design Burial Depths

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Interaction Hazards

Third Party Requirements

Natural Hazards

Design Depth

Cable Burial Design

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Mitigation Measures Mitigation measures to reduce level of risk from hazards could

include: Cable re-routeing (e.g. UXO)

Cable burial (CBRA Scope)

Other cable protection methods, i.e. rock placement/concrete mattress(where burial is not achieved)

Inspection and/or maintenance procedures

Stakeholder Engagement

Fisheries liaison

Notice to Mariners

Notices to fishermen

Monitoring of shipping activity

Charting of cable on nautical charts

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Cable Route Zones

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• Zone 1 (KP1 to 14) of theexport cable route intersectsthree maintained channelsinc. the Mt. Hope Bay mainship channel, Tiverton channeland the Brayton PointChannel.

• Channels have authoriseddepths of 35 ft MLLW (USACE).

• USACE have agreed cable tobe buried to 41 ft MLLW (Sept26th 2018).

• The anchored vessels is basedon 12 months of AIS fromAugust 2016 – July 2017.Recreational vessels are onlyvessel type recorded withinclose proximity to cable route.

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Zone 1 : Mount Hope Bay/Sakonnet River

• Stone Bridge Area – USACENavigation Project, 100ft wide,25ft deep channel.

• Bridge demolition date notdetermined, discussions withRhode Island DOT.

• Cable burial and scourmodelling will considerdynamic area.

• Known problematic area forcable burial due toconstruction debris.

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Zone 1 : Mount Hope Bay/Sakonnet River[Bridge Infrastructure]


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12 Months AIS (August 2016 – July 2017):

The figure above represents the vesseltype distribution of all AIS tracksintersecting Zone 1 of the export cable.


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12 Months AIS (August 2016 – July 2017) excluding recreational:

The figure above represents the DWTdistribution of vessel tracks (exc.recreational) intersecting Zone 1 of theexport cable route. Those estimated tobe < 500 include fishing vessels and smalltugs.


The deepest vessel draughts recorded intersecting the maintained channels are as follows: Tiverton : 6.7m (22 ft.) from the tug vessel Austin Reinauer

Mt. Hope Bay & Brayton Point: 10.5m (34 ft.) from the bulk carrier CSL Spirit

As mentioned previously, the authorised depths of the Tiverton & Mt Hope Bay channels is 35 feet.

The CSL Spirit was also the deepest draught recorded intersecting Zone 1 of the export cable.

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Zone 1 : Mount Hope Bay/Sakonnet River[Recreational]

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The figure above represents the lengthdistribution of all recreational tracksintersecting Zone 1 of the export cableroute.

Borden Light Marina:

Zone 1 : Mount Hope Bay/Sakonnet River[Key crossing point]

There were 12 unique commercialvessels (10 cargo and 2 chemicaloil tankers) recorded intersectingZone 1 on 44 occasions.

The cargo vessels included generalcargo and bulk carriers withdestinations set to Fall River, PortBrayton Point, etc.

The largest vessel was the 220m(~772 ft) bulk carrier, CSLTarantau, with a DWT of 71,279.

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Zone 1 : Mount Hope Bay/Sakonnet River[Sample vessels]

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CSL Tarantau (© MarineTraffic) was recorded intersecting Zone 1 whilst transiting in and out of Brayton Point between 15th

and 17th November 2016.

Pandemonium(© MarineTraffic) was recorded intersecting Zone 1 on multiple occasions. This vessel is 11m (36 ft.).

It is assumed vessels fishing for demersalspecies (e.g. monkfish) will operatedemersal gear. This type of gear poses thegreatest risk to subsea cables as gear istowed along the seabed.

The figure opposite presents the density ofvessels estimated to be engaged in fishingactivities based on vessel speed, however,this does not distinguish between slowmoving vessels entering / exiting harboursor ports.

A higher density of fishing was recorded atthe south of Zone 1.

No other demersal fishing operations wererecorded on VMS for 2015-2016 withinproximity to Zone 1 of the export cable.

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Zone 1 : Mount Hope Bay/Sakonnet River[VMS obtained from North East Ocean Data Portal]

VMS 2015 – 2016 : Monkfish

Fishing Satellite Data : 2011-2015 VMS[VMS obtained from Mid Atlantic Ocean Data Portal]

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Demersal Trawlers < 65 feet Demersal Trawlers > 65 feet

Boat DredgesThese demersal gears pose the highest risk to subsea cables as gear is towed along the seabed.Fishing gear can penetrate up to 0.3m (12 inches) in soft soil.Carbon Trust recommendation 0.6m (24 inches) burial depth.

Anything Missing ?

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• Baseline Data

• Hazards in Zone

• Causes

• Mitigation Measures

• There are no mainnavigational featureslocated within proximity toZone 2 of the export cable.

• The anchored vessels arebased on 12 months AISfrom August 2016 – July2017.

• Only recreational vesselswere recorded at anchorwithin Sakonnet River andthus pose a risk to thecable.

• Closest vessels were theRoseway & Lady Maryland,anchored approximately200m east of the cable.

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Zone 2 : Sakonnet River (KP 14 to 34)

Zone 2 : Sakonnet River

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Zone 2 : Sakonnet River[Recreational and Fishing]

Popular destinations for recreationalcraft include Pirate Cove Marina,Sakonnet Harbor and Flint Point Ledgeoff Third Beach where various vesselswere recorded at anchor.

There was one fishing vessel inparticular that made up 86% of thefishing tracks intersecting Zone 2. Thiswas the 25m (82 ft.) vessel Edna May.

The Edna May was recorded transitingup/down Sakonnet River to Tiverton.

No tracks were estimated to be activelyfishing however this vessel operateshandlines and polelines, thereforeshould not pose a risk to the cable.

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The figure above represents the lengthdistribution of all tracks intersecting Zone2 of the export cable route. The largestvessel was the passenger vessel AmerConstellation at 82m (269 ft) travelling toFall River.

The largest vessel recorded intersectingZone 2 was the passenger vessel AmerConstellation (seen opposite) at 82m(269 ft) travelling to Fall River.

This was recorded on the 6th June2017.

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Zone 2 : Sakonnet River[Largest vessel]

As before, the density presented isestimated to be vessels actively fishingbut may include vessels transiting inand out of harbours in Sakonnet River.

As with Zone 1, fishing for Monkfishwas recorded along Zone 2 of theexport cable route.

Higher density was seen to the north ofZone 2 with less activity recorded atthe south.

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Zone 2 : Sakonnet River[VMS obtained from North East Ocean Data Portal]

VMS 2015 – 2016 : Monkfish

Anything Missing ?

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• Baseline Data

• Hazards in Zone

• Causes


• KP 34 to 51.

• Brenton Point anchorage isapproximately 1.5-2nm westof the export cable route.

• Export cable intersectsBuzzards Bay TSS withNarragansett Bay TSSapproximately 6-7nm to thewest.

• Recommended vessel routefor deep draught vessels andtugs/barges transiting theRhode Island Sound,Narragansett Bay & BuzzardsBay.

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Zone 3 : Sakonnet River – Buzzards Bay TSS

• There was an average of one uniquevessel at anchor every two days inthis zone (based on unique vesselsper day).

• Cargo vessels represented over half(66%) of vessels.

• The majority of vessels broadcast adestination of Providence.

• Two vessels were recorded at anchorat locations outwith the designatedanchorage area as shown opposite.

• The pusher tug, Coho, broadcast adestination of St Johns on the 8th

January 2017.

• The bulk carrier, Bulk Beothuk,broadcast a destination of Providenceon the 21st & 22nd February 2017.

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Zone 3 : Sakonnet River – Buzzards Bay TSS[Anchored Vessels]

Zone 3 : Sakonnet River - Buzzards Bay TSS

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The figure above represents the mainvessel type distribution of all AIS tracksintersecting Zone 3 of the export cable.

Zone 3 : Sakonnet River - Buzzards Bay TSS[DWT and Length]

The majority of recreational vessels did notbroadcast a destination however some examplesrecorded include Newport, Nantucket, Martha’sVineyard, Sag Harbour, etc. The figure aboverepresents the length distribution of allrecreational tracks intersecting Zone 3 of theexport cable route.

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The figure above represents the DWT distribution of vessel tracks (exc. Recreational & fishing) intersecting Zone 3 of the export cable route.

Zone 3 : Sakonnet River - Buzzards Bay TSS Majority of commercial tracks (ex

tugs/fishing) are associated with thenorthbound lane of the NarragansettBay TSS to the west of the cable.

There was a total of 115 uniquecrossings of Zone 3 from commercialvessels.

Commercial vessels intersecting Zone 3of the cable range in size from 7,000DWT to 56,600 DWT.

The majority of cargo vesselsintersecting Zone 3 were eitherrefrigerated cargo ships or vehiclecarriers.

These intersecting vessels broadcastdestinations such as Boston, St. John,etc.

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It can be seen from the figure, thatthere is a high density of tugs utilisingthe recommended route.

There are also some vessels utilisingthe Buzzards Bay TSS to the south ofthe recommended route.

An average of 5 unique tugs per dayintersect Zone 3 of the cable route.

These are largely pusher tugs involvedin tug/tow operations.

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There were a total of 1,070 uniquecrossings of Zone 3 by fishing vessels.

Majority of vessels appear to betransiting through the study area asopposed to engaged in fishingoperations.

Wide range of vessels sizes fromapproximately 40 to 160 ft. (hydraulicdredgers ESS Pride & ESS Pursuit).

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Zone 3 : Sakonnet River - Buzzards Bay TSS[VMS obtained from North East Ocean Data Portal]

VMS 2015 – 2016 : Monkfish VMS 2015 – 2016 : Scallop

Overall there is a low density of monkfish fishing is observed along Zone 3. Higher activity seen to the south.

A small area of scallop dredging takes place at the north of Zone 3 with larger areas of activity seen to the east and west of the cable.

Anything Missing ?

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• Baseline Data

• Hazards in Zone

• Causes


• KP 51 to 94)

• Zone 4 of the export cable route intersects the Narragansett Bay military operating area.

• In addition, the route intersects a seasonal speed restriction zone (speeds < 10 knots). This applies to vessels over 65 ft. during November to April.

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Zone 4 : Buzzards Bay TSS – Cable End

Zone 4 : Buzzards Bay TSS – Cable End

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Zone 4 : Buzzards Bay TSS – Cable End[Type and Length]

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The figure above represents the lengthdistribution of all tracks intersecting Zone4 of the export cable route. The largestvessel was the passenger vessel Europa 2at 226m (~741 ft) travelling to Oak Bluff.

The largest vessel was the passengervessel Europa 2 at 226m (~741 ft)travelling to Oak Bluff.

This vessel has a DWT of 5,285 t.

This vessel was recorded intersectingZone 4 of the export cable on 29th

September 2016.

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Zone 4 : Buzzards Bay TSS – Cable End[Largest Vessel]

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Zone 4 : Buzzards Bay TSS – Cable End[VMS obtained from North East Ocean Data Portal]

VMS 2015 – 2016 : Monkfish VMS 2015 – 2016 : Multispecies (Groundfish)

Fishing activity for monkfish is carried out along the length of Zone 4 with higher density seen to the north.

Density of vessels fishing for groundfish is much lower than monkfish along Zone 4 of the cable.

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Zone 4 : Buzzards Bay TSS – Cable End[VMS obtained from North East Ocean Data Portal]

VMS 2015 – 2016 : Scallops VMS 2015 – 2016 : Surfclam & Quahog

This fishing is likely to be carried out by scallop or hydraulic dredgers. It can be seen there is a fairly high density of surfclam fishing at the northern end of Zone 4 whilst fishing for scallops is more common to the south.

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Trawl Scars

Anything Missing ?

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• Baseline Data

• Hazards in Zone

• Causes


• The inter-array cables liewithin the NarragansettBay military operatingarea.

• In addition, there is amilitary transit lane westof the array cables(approx. 20nm).

• The seasonal speedrestriction zone detailedfor Zone 4 of the exportcable also applies here.

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Zone 5 : Inter-array Cables


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The figure above represents the vesseltype distribution of all AIS tracksrecorded intersecting Zone 5 (arraycables).


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12 Months Fishing (August 2016 – July 2017):

12 Months Recreational (August 2016 –July 2017):

Zone 5 : Inter-array Cables[Length and DWT]

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The figure above represents the lengthdistribution of all fishing and recreationaltracks intersecting Zone 5. It is noted, noDWT information was available forfishing vessels.

The figure above presents the DWT ofthe passenger and ‘other’ vesselsrecorded intersecting Zone 5. It is notedDWT for recreational and fishing vesselsis not included due to limitedinformation.

Vessel Name Type DWT

Relentless Offshore 868

Atlantis Research/Survey 1,332

Neil Armstrong Research/Survey 1,472

CaribbeanPrincess

Cruise 8,418

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Zone 5 : Inter-array Cables[VMS obtained from North East Ocean Data Portal]

VMS 2015 – 2016 : Monkfish VMS 2015 – 2016 : Multispecies (Groundfish)

Fishing for both monkfish and groundfish occurs within proximity to the array cables as seen in the figures above.

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Zone 5 : Inter-array Cables[VMS obtained from North East Ocean Data Portal]

VMS 2015 – 2016 : Scallops VMS 2015 – 2016 : Surfclam & Quahog

Scallop dredging occurs within proximity to the array cables. This type of fishing is the greatest risk to the subsea cables as they are dragged along the seabed.

Fishing Satellite Data : 2011-2015 VMS[VMS obtained from Mid Atlantic Ocean Data Portal]

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Demersal Trawlers < 65 feet Demersal Trawlers > 65 feet

Boat DredgesThese demersal gears pose the highest risk to subsea cables as gear is towed along the seabed. Dredgers can penetrate to depths of 0.2m each operation.

Anything Missing ?

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• Baseline Data

• Hazards in Zone

• Causes


Thank you for attending.

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Other Small Craft Information relating to anchors used for fishing vessels, pilot vessels and

Coastguard ships in the area would be highly beneficial as publicly availableinformation is limited. However, if no information can be obtained, theassumptions made for recreational will be used.

The length distributions of these vessels within the baseline data are presentedbelow to give an indication of vessel sizes to better inform expert opinion.

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Vessel Length (ft.)

Pilot Fishing Coastguard

0-40 - - 16%

40-50 6% 1% 3%

50-60 57% 2% -

60-70 1% 13% 3%

70-80 36% 32% -

80-90 - 23% 17%

90-100 - 15% -

100-150 - 10% 22%

150-200 - 3% 2%

200-300 - - 35%

300-500 - - 3%

maw01 cable risk assessment hazard workshop...the findings of this workshop will then be used to...

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