TRACTEBEL Engineering Limited 1st Floor Chertsey House, 61 Chertsey Road, Woking, Surrey GU21 5BN - UNITED KINGDOM tel. + 441483550859 [email protected] www.tractebel-engineering-gdfsuez.com FINAL REPORT
Our ref.: I/RA/14189/13.035/WGO Your ref.: Pro memoriam
Date: 31 May 2013 RESTRICTED
Employer : Ofgem
Project : LINCS Offshore Wind Farm
Subject : Review of the export cable installation costs
approval written prior without forbidden is parties third to
transmission or duplication ny
A .
TractebelEngineering Limited
Smart & Sustainable Infrastructure
CCS TLM trading under the brand name Tractebel Engineering Limited – Incorporated in England (registration number
7117985) with registered office 5-9 Eden Street, Kingston Upon Thames, Surrey KT1 1BQ, United Kingdom. VAT No: GB Thisdocument the is property of 992 5309 89
TABLE OF CONTENTS
1. EXECUTIVE SUMMARY ...... 5
1.1. Cost evaluation ...... 6
1.2. Connection point ...... 6
1.3. Project Planning...... 7
1.4. Cable installation and consents ...... 7
2. INTRODUCTION ...... 8
3. APPROACH ...... 8
4. CABLE ROUTE AND INSTALLATION ...... 9
4.1. Cable route and connection point ...... 9
4.2. Conclusions ...... 13 4.2.1. ‘The Wash’ site surveys ...... 15 4.2.2. Consents 19 4.2.3. Conclusions ...... 20
4.3. Project management ...... 21 4.3.1. Contingency planning ...... 21 4.3.2. Project decision making ...... 22
4.3.3. Managing contractors ...... 22 approval written prior without forbidden is parties third to 4.3.4. Participating contractors ...... 22 4.3.5. Conclusions ...... 24
5. CABLE INSTALLATION WORKS ...... 25
5.1. Introduction ...... 25 transmission or duplication ny . A . 5.1.1. Summary of events ...... 25
5.2. 2010 Nearshore cable installation using HDD ...... 26 5.2.1. Conclusions ...... 27
5.3. Chain Trenching and installation with rollers 2011 ...... 27 TractebelEngineering Limited 5.3.1. Cable Float in ...... 28 5.3.2. All-terrain Vehicle ...... 29 5.3.3. Use of Rollers ...... 30 5.3.4. Roller spacing ...... 30 5.3.5. Conclusions ...... 31 Thisdocument the is property of 5.4. Chain Trenching and float-in installation 2012 ...... 31
5.4.1. Standby UR101 ...... 31 5.4.2. Flume Pipe installation in 2011 & 2012 ...... 32 5.4.3. Conclusions ...... 32
5.5. Main cable installation ...... 33 5.5.1. Plough-incident ...... 33 5.5.2. Spare Export Cable Storage ...... 33 5.5.3. Anchor trials ...... 34 5.5.4. Conclusions ...... 34
5.6. Jointing works and post lay burial ...... 35 5.6.1. Conclusions ...... 35
5.7. Cable supply by Contractor ...... 35 5.7.1. Delay of Supply ...... 36 5.7.2. Storage costs spare cable ...... 37 5.7.3. Conclusions ...... 37
6. OVERVIEW OF CLAIMS ...... 38 6.1.1. Conclusions ...... 38
7. PROJECT COSTS ...... 39
7.1. Breakdown indicative transfer value July 2011 ...... 39
7.2. Breakdown status November 2012 ...... 39
7.3. Examples of variation orders ...... 41
7.4. Conclusions ...... 41 approval written prior without forbidden is parties third to
8. GENERAL CONCLUSIONS ...... 41
8.1. Connection point ...... 42
8.2. Project organisation ...... 42 transmission or duplication ny . A .
8.3. Installation methods and consents ...... 42
8.4. Outstanding claims ...... 43
8.5. Cost evaluation ...... 43 TractebelEngineering Limited
9. RECOMMENDATIONS ...... 44
10. REFERENCES ...... 45
11. APPENDICES – ALL APPPENDICES REDACTED ...... 47 Thisdocument the is property of
1. EXECUTIVE SUMMARY
The scope of this review was confined to the Lincs Export Cable installation costs and involved:
• An examination into the investigations undertaken as part of the pre-construction works regarding the options considered for the connection point, and an independent view on rationale for the selection of the connection of Walpole;
• An outline of where export cable installation costs have increased since the indicative valuation was set in July 2011;
• A rationale for each of the costs increases since the indicative was set in July 2011, and an independent view on the justification of these cost increases; and
• A summary and description of outstanding claims and contract variations that have arisen outside of the basic contract price and a view on the claim levels in
relation to the work and efficiency of the project management of the contract works.
The analysis covers documentation provided to the consultant between 21 December and 28 January 2013. In addition there were follow up discussions facilitated by OfGem with Centrica and a telephone conversation with Natural England. The events generated further documentation to which commentary has been added in this report. During the review Tractebel UK engaged closely with the developer and there was a constant communication and data-exchange between both parties. Having taken into account all of the information and data provided, Tractebel UK’s analysis concludes that £ xxxx m of the project’s cable installation cost overruns are
not economic and efficient. approval written prior without forbidden is parties third to This is based upon (1) The incorrect choice of Horizontal Directional Drilling (HDD) for cable installation in 2010 with the known geology of the Wash Area and (2) The lack of detailed planning prior to commencement of the 2011 work which
we believe could have resulted in the work being completed that year. transmission or duplication ny This high level figure has been derived even after some of the cost variations documentation had been provided. A detailed reconciliation, including whether any Engineering S.A. A S.A. Engineering
of the overrun costs had been successfully recovered through insurance claims has not been carried out in the agreed timescale. TractebelUK Thisdocument the is property of
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1.1. Cost evaluation
Tractebel UK concludes that although a high level project risk assessment was conducted, the developer should have undertaken more detailed contingency planning to evaluate whether different cable installation methods could have been chosen for the project and/or mitigations set in place. The undertaking of HDD installation without an intrusive survey was accepted by the developer. Unfortunately the 2010 Subocean HDD works were not successful. . If the original HDD installation method had been abandoned earlier (with a contingency plan already in place) the cable installation works which ran into 2012 could have been completed within the original 2011 planned timeframe. Therefore the duration and cost are not economically and efficiently incurred. The July 2011(Indicative Transfer Value) budget for the cable installation work was £85.4m and during the period of construction costs increased by £26.7m. The Subocean 2010 HDD costs equal to £ xxxx and the 2012 shore end works equal to £ xxxx totaling more than £16.6m but without agreement to carry out a detailed variation order analysis it has not been possible to reach a final figure. We therefore conclude that £15m of the £26.7m cost overrun can be classed as inefficient.
Tractebel UK recommends that further documentation needs to be provided and assessed to identify whether further cost increases can be challenged. Furthermore there are some insurance claims with various contractors which have yet to be resolved which could be in the developer’s favour. A view on the outcomes of these claims has not been part of this report and has not been included in the supportable (or not) cost overrun. These should be discussed between Ofgem and the developer.
1.2. Connection point approval written prior without forbidden is parties third to
Tractebel UK reviewed a report prepared for the developer by RPS Energy [36]. This focussed on the project’s onshore and offshore cable route options, grid connection considerations and the associated implications for the project’s costs. The report considered briefly the offshore cable installation but did not consider this
in depth when evaluating the preferred connection point. transmission or duplication ny The report considered 3 wind farms (Lincs Wind Farm (250MW), Race Bank (500MW) and Docking Shoal (500MW)) as a joint investment. The options for each project’s cable landing was not fully analysed and hence the most cost effective Engineering S.A. A S.A. Engineering
choice for each project individually may have not been identified. The developer suggests that a cable route investigation and development for the Lincs Wind Farm only would have been less economical for the project because: TractebelUK • Survey costs could be shared • Safety of navigation was considered as i) cables would be in one location; ii) the cables could all be located in the deep channel in the centre of the Wash thereby reducing the risk of anchor snagging • There would be fewer fisheries exclusion zones Thisdocument the is property of
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• There would be fewer landowners and therefore fewer commercial agreements. The 2006 study suggests that the key factor for grid connection was the availability of capacity in 2010. It is noted that at the time of awarding the cable installation scope (April 2010) the project’s time frame had scheduled to connect to the Grid by mid 2011 due to delays in the planning process after the application was submitted for consent.
1.3. Project Planning
The project’s offshore cable goes through ‘The Wash’ and a nearshore saltmarsh which, in particular, created significant challenges for the project. Tractebel UK concludes that a detailed local site conditions assessment focusing in on the offshore cable installation route through the saltmarsh should have been undertaken at an early stage in the project. Although Natural England did not permit an intrusive survey in the saltmarsh, Tractebel UK concludes that the local site conditions were not considered in detail when the project’s connection point was finalized. Tractebel UK notes that there seemed to be little or no contingency planning, risk assessment or mitigation procedures in place as the cable installation procedures
commenced. An important example of this is the original consent only permitted a Horizontal Directional Drilling (HDD) approach to be undertaken. The known risks associated with such an approach including the effect of the local site conditions were not identified at an early stage in the project planning and a contingency plan was not created and implemented. Successful project processes were in operation by completion of the project, for example, controlling project changes [12, 13] and managing contractor interfaces [39, 40, 41],
1.4. Cable installation and consents to third parties is forbidden without prior written approval written prior without forbidden is parties third to The project faced strict consenting arrangements imposed by the Marine Management Organisation (MMO) and Natural England. Nearshore works could only take place between 15 May and 31 of August and access on the saltmarsh would only be allowed with the explicit permission of Natural England. The project’s original consent was for a single installation approach based on HDD. This
choice whilst imposed on the project ruled out assessing alternative installation transmission or duplication ny methods. Tractebel UK concludes that the lack of awareness of the nearshore soil conditions in the saltmarsh was a contributing factor to the failure of the HDD approach. The project was forced to review the installation methodology with chain Engineering S.A. A S.A. Engineering trenching being the eventual selected method, which required modifications to the consent with Natural England. The failure of the HDD and subsequent changes to the installation methodology led to additional costs being incurred by the project. TractebelUK Tractebel UK concludes that awareness of the nearshore soil conditions should have led to the choice of a float–in technique being adopted in the first instance. Moreover a float-in cable landing is a standard offshore practice, which mitigates risks when the soil conditions pose concerns or are insufficiently known. When this methodology was eventually implemented on the project by another contractor the installation was successfully completed. Thisdocument the is property of
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2. INTRODUCTION
Ofgem are in the process of setting a Final Transfer Value (FTV) for the Lincs Offshore Transmission Assets. An Indicative Transfer Value (ITV) was set by Ofgem in July 2011. Since then the project has experienced an increase in the export cable design, supply and installation costs. As a consequence, Ofgem appointed Tractebel UK to undertake a technical review of the export cable cost increases. Tractebel UK has also investigated the project’s connection point evaluation, export cable route choice, the developer’s approach to project management and risk assessment, and the export cable installation nearshore and further offshore. During installation of the export cables for the Lincs Wind Farm (2010-2012) a number of events and delays occurred, mainly taking place in the nearshore section of the export cable route. In addition there were events and delays during the main cable installation, which took place further from shore, for example, jointing works and incidents during the load-out of the export cable and storage of a spare cable piece. (For detailed timeline see Appendix C). It should be noted that the original contractor for the export cable installation (Subocean) suffered insolvency (in the beginning of 2011). This resulted in different
contractual parties to be sought for the cable installation works. A number of the incidents occurred during the export cable installation which resulted in insurance claims. The outstanding claims are discussed in the report and an overview is provided of the status of the claims at the time of writing this report. The events that occurred during the export cable and supply installation were analysed further to form an independent view of where the costs have increased since July 2011 and if these increases are economic and efficient. Where possible an estimate of the impact of the events on the cost of the project was made. A review of the developer’s cost template was undertaken. A full breakdown of the cost movements was not provided by the developer. This report is based on information provided by the developer and subsequent discussions that took place involving Ofgem and the developer. approval written prior without forbidden is parties third to Tractebel UK concludes that a further detailed technical and financial review is recommended in some areas of cost increase [e.g. the revised Technip costs for Export Cable Installation of £ xx m and the transfer of non-OFTO costs to OFTO costs of £ xx m]. This could allow a fuller and complete understanding of all of the
cost variations which occurred. transmission or duplication ny Engineering S.A. A S.A. Engineering 3. APPROACH
This review was primarily based on information provided in the developer’s data TractebelUK room up to January 28th 2013, as well as information or clarifications received by e- mail, during telephone conference calls and face-to-face meetings, specifically covering:
• The latest cost template from the Lincs project (November 2012); • Relevant data room contents; Thisdocument the is property of
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• Centrica’s briefing on the Installation of the Lincs Offshore Wind Farm Subsea Export Cables – A brief history [34]; and • Additional information provided by Ofgem and the developer during the duration of the work programme. • Current costs were compared to the ITV which was set in July 2011, and based on the project’s November 2012 costs. • A phone conversation with Natural England and Centrica facilitated by Ofgem.
4. CABLE ROUTE AND INSTALLATION
4.1. Cable route and connection point
For the purposes of this report Tractebel reviewed the RPS Engineering report dated 22nd May 2007 (EOR0515-1 rev 5: Cable Route Alternatives Study for Lincs, Race Bank and Docking Shoal Offshore Wind Farm Developments, [36]). The report describes the Lincs Wind Farm connection to the onshore grid.
The report is based on information available only between January and March 2006. Tractebel UK notes that at the time of writing the report the developers goal was to have the wind farm operational in 2010 (to meet the Government’s 2010 targets for 10% of electricity supplied in the UK to be provided from renewable sources). This meant that the grid connection had to be available within that timescale. The RPS report considered three wind farms (Lincs Wind Farm, Race Bank and Docking Shoal, ‘Round 2 projects’) with a total capacity of 1250MW, of which 250MW was required for the Lincs project. The developer’s desire was for the offshore export cables of the three wind farms to be combined in an onshore corridor of 50 m. Tractebel UK concludes that considering the Lincs Wind Farm in isolation may have resulted in a more optimal offshore routing outcome for that location. For approval written prior without forbidden is parties third to example, a landing point for Lincs to the West near the landing of the Inner Dowsing and Lynn, while the cable landing for Race Bank and Docking Shoal could be chosen East of the Wash and should have been assessed in further technical detail taking into account the cable installation difficulties that could be expected in the Wash. ny duplication or transmission transmission or duplication ny The developer has explained that a cable landfall close to Lynn and Inner Dowsing was not feasible as: •
There was no capacity within the existing Distribution Network Operator’s A S.A. Engineering
network • A new 400kV substation would be required and would not be delivered in
time. Furthermore this would involve around 50-60km of overhead lines which TractebelUK would be unlikely to receive consent • To route to Walpole from a Skegness landfall would involve a significant consents from of landowners. The eventual cable route involved only 10 onshore landowners Thisdocument the is property of
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The developer added that the solution to aggregate the Lincs, Race Bank and Docking Shoal cables would result in shared development costs; minimal environmental impact; minimal disruption to fishermen, shipping; and synergies with onshore landowners.
Following discussions The Environmental Impact Assessment [44] was provided but does not generate any supporting arguments for this decision. In addition to the RPS report, the developer undertook further studies which considered the project’s connection options. The Econnect Consulting report [45] reviewed, amongst other things, the RPS report as well as the electrical studies performed by Mott MacDonald [46], [47] and a construction report by Mott MacDonald. The analysis focussed on the electrical and grid connection issues (including electrical losses). The RPS report [36] recommended that further analysis should be conducted for the most feasible connection option based upon technology, infrastructure requirements and environmental factors. In addition this report commissioned by the developer considered 11 route options, (see Appendix A), where next to the availability to connect to the Grid, the following factors were mainly considered:
• the costs of the offshore and onshore cables related to the size and length, • the complexity of the cable laying (mainly onshore), • the possible network reinforcement works needed onshore to allow for a connection in 2010
Table 1 provides a high level overview of the routes that were considered with a description and the conclusions that were reached on each of these options. Table 1: Description route alternatives
Onshore Offshore Total Summary RPS Evaluation Option Description of route distance distance distance
of the route approval written prior without forbidden is parties third to (km) (km) (km) -Bicker Fenn Substation extension was indicated to be needed to accept all 3 Wind Farms (1,25GW). Unclear what additional needs were Landfall North of
for LINCS only (250MW) transmission or duplication ny Skegness, running to 1 44.31 12.55 56.86 -possible long delays in Bicker Fenn Station connection offers were not (underground cables) seen as a driver to dismiss Engineering S.A. A S.A. Engineering
this option, rather traffic delays and cable lengths losses being less
economically viable TractebelUK Landfall South of Skegness, running to Same remarks as option 1 2 44.31 12.55 56.86 Bicker Fenn Station (see above) (underground cables) Thisdocument the is property of
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Onshore Offshore Total Summary RPS Evaluation Option Description of route distance distance distance of the route (km) (km) (km) Landfall North of Skegness, connection to Not applicable for Lincs 3 National grid in Skegness - - - Wind Farm and running to Bicker Fenn Station via overhead lines -Similar remarks as for options 1 and 2 (see above), Landfall South of overhead lines and a new Skegness, connection to 400kV substation at 4 National grid in Skegness 44.31 12.55 Skegness would need to be and running to Bicker Fenn constructed. Station via overhead lines - Offers posed risk of late connection (2012) -This is the shortest onshore route, but has a large offshore section through the Cable route through the Wash internationally 5 Wash, running to Walpole 10.07 40.41 50.48 designated area. substation -Walpole substation can accommodate the full 1,25GW from Lincs, Race Bank and Docking Shoal -construction of new substation required along the Running the offshore River Humber 6 cables North towards the 0 56.22 56.22 -cable length losses were Humber indicated as making this option less economically viable -No available grid capacity Landfall at North Norfolk at Sall substation.
Coast (vicinity approval written prior without forbidden is parties third to -Construction of additional 7 Weybourne) and onshore 18.89 56.84 75.73 overhead lines appeared route towards Sall needed and it was expected substation that the public would object. Landfall at North Norfolk Existing 132kV Kings Lynn Coast (vicinity Thornham) station would need 8 17.65 28.06 45.71 and onshore route towards upgrading and the need for transmission or duplication ny Kings Lynn overhead lines was indicated Landfall at North Norfolk Coast (vicinity Long cable lengths resulting Engineering S.A. A S.A. Engineering 9 Weybourne) and onshore 69.81 56.84 126.65 in high electrical losses route towards Walpole substation Landfall at North Norfolk Major reinforcement needed TractebelUK Coast (vicinity to ensure grid connection, 10 Weybourne) and onshore 69.81 56.84 126.65 moreover also the length of route towards a new the cables would lead to high substation electrical losses Thisdocument the is property of
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Onshore Offshore Total Summary RPS Evaluation Option Description of route distance distance distance of the route (km) (km) (km) The main driver to dismiss Landfall at North Norfolk this route was the additional Coast (vicinity engineering through onshore 11 Hunstanton) and onshore 54.74 28.06 82.8 marshland (areas with high route towards Walpole water table) and the longer substation cable lengths Landfall at North Norfolk Coast (vicinity This is an alternative from 11*1 Hunstanton) and onshore 34.58 28.06 62.64 route 11 route towards Walpole substation
One of the key issues discussed in the RPS report [36] is the availability of a grid connection in 2010, which was assessed on capacity being available at Walpole, Bicker Fenn, Sall and Kings Lynn. For the connections around Skegness (closest option for Lincs), Central Network East (CNE) stated that they did not have sufficient capacity to accommodate any of the developer’s projects. The developer had applied for connections to the National Grid, but it was indicated that this would require the construction of a new 400kVsubstation at Skegness, which may take some time to progress given the extent of consents required. This was considered as a limiting factor since a connection would be needed prior to 2010. Therefore, a connection towards Skegness was not considered further by the developer. At Walpole sufficient capacity was available without the need for reinforcement of the substation or additional scope of works. All other options considered were indicated to require upgrades to the substations or the substation’s electricity connection. Route option 5 (through the Wash) was the chosen route. The report confirms that the Walpole substation provided the grid availability by 2010 for all 3 wind farms without reinforcement works and the cable route being the shortest distance. The RPS report suggested that if there would be a need to minimize the
length of the offshore route through the Wash, option 11/11* provided the best approval written prior without forbidden is parties third to alternative. However, a risk assessment on choosing to minimize the length of the offshore cable route was not provided.
EVALUATION OF ROUTES
The onshore routes for Options 5 and 11/11* are discussed in the [RPS report. transmission or duplication ny Options 1 and 2 were not further assessed due to cable transmission losses analysis [47]. A solution to this could have been a larger, but more expensive and maybe later delivered cable. This would have the advantage of a shorter less expensive Engineering S.A. A S.A. Engineering offshore routing. The financial and technically assessment of this architecture choice was not carried out. TractebelUK
1Route 11 runs further inland (Eastern option), while route 11* runs parallel to the coastline Thisdocument the is property of
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Tractebel UK concludes that the options 1 and 2 appear suitable for the Lincs Wind Farm (250MW) only as the Lynn and Inner Dowsing projects have their offshore cables on land nearby. In addition the project team would have benefited from the experience and lessons learnt from works previously undertaken in that area. When assessing route 11*, it appears that the landing points that were investigated were Hunstanton and Brancaster. However, due to the environmental sensitivity of the coastline, the eroding nature in the vicinity of Holme, this option was considered unsuitable for cable burial. Options 9 and 10 considered a landfall immediately 30 kilometres east of Brancaster. These options were considered unviable due to the cable length being in excess of 100 kilometres for the Lincs Wind Farm. Tractebel UK notes that a cable landing in between Brancaster and Weybourne was not further investigated. The RPS report concludes that a section of the Norfolk Coast is accreting (as also stated in the Appendix B describing the regional physical constraints) and landfall in the vicinity of Brancaster or slightly East of Brancaster would not have encountered erosion. Although the coast between Brancaster and Weybourne also provides challenges, there are roads cutting through to the shore end side, indicating possibilities for an onshore cable route. Although the shorter route would have resulted in a more difficult landfall the important cable burial would have not been impossible.
The remaining routes to be considered were thus option 5 and 11. Route option 11 concentrated on a landfall between Hunstanton and Heacham and this option was detailed and weighed against route option 5 via an impact assessment. Route option 5 scored better, as it was stated that the cable installation would have a smaller negative impact since there would be a shorter onshore cable route. The option 11 route also scored less positive mainly due to the fact that an archaeological site was present on the onshore route. For option 5, the vicinity of an offshore archaeological site was not mentioned in the assessment. The developer has explained that options 1 and 2 involved a 2015 grid connection which was too late for the Lincs project. Option 11 was not selected as various stakeholders requested that the cables should be located in the deep navigation approval written prior without forbidden is parties third to channel in the centre of the Wash to avoid interaction with anchors and fishing activities.
4.2. Conclusions
transmission or duplication ny
Following the analysis of the RPS report Tractebel UK notes that the offshore cable installation and the related risks are not described as a major concern in this report. Engineering S.A. A S.A. Engineering However, in Offshore Wind projects, Tractebel UK notes that offshore cable installation (including landfall and Offshore Substation Platform works) is typically
the package where the majority of the construction incidents, delays occur and is the TractebelUK main cause of cost overruns. Thisdocument the is property of
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The offshore cable installation works are complex in nature and are more than other disciplines dictated by the experience level of the contractor performing these works. Moreover, dedicated cable installation vessels and barges are heavily booked during the good weather periods and day rates are high. The latter results in the fact that any delays encountered have a high cost impact, especially in comparison with onshore works. Onshore cable works apply well known techniques, are less weather dependent and avoid vessel/barge standby costs when facing an unexpected delay.
SELECTED ROUTE Option 5 was chosen as the route selected to link the 3 wind farms Lincs, Race Bank and Docking Shoal to land as this was the shortest export cable installation route to the substation at Walpole. This route runs through ‘The Wash’ with strict consenting arrangements, the presence of a shipping lane as well as dedicated anchoring areas. If in the initial stage and based on the known challenges of working in a saltmarsh area, the offshore cable routes had been further investigated and risk assessed, a route option avoiding the many challenges of an offshore cable installation through ‘The Wash’ could have been chosen in order to mitigate the overall project’s risk. The Lincs Wind Farm project was considered in conjunction with Race Bank and Docking Shoal and a key factor was the availability of a grid connection in 2010.
However, at the time of awarding the cable installation scope to Subocean on 22/04/2010, the project’s time frame had scheduled completion of the cable installation and connection to the grid by mid 2011 due to delays in other parts of the consenting process. Tractebel UK has not seen any review or analysis of risk weighting between the on shore and offshore cable routes selections.
RISK ASSESSMENT As the offshore cable is the critical connection from a Wind farm to the Grid, the offshore cable installation works should be well planned and risk assessed to
minimise construction difficulties. Tractebel UK notes that the project’s cable approval written prior without forbidden is parties third to installation risks appear to have not been taken into consideration during the analysis of the different onshore connection points. For an offshore cable the management of the installation is much more difficult than for an onshore cable, since the risks are much higher. For example:
• Day rates of onshore equipment are much lower than day rates of offshore transmission or duplication ny vessels; and • Offshore works involve consideration to tidal, currents and wave impacts that can complicate installation and lead to standby costs which can lead to Engineering S.A. A S.A. Engineering significant project cost increases. Given the specific site conditions along the envisaged cable route through ‘The Wash’ (in a saltmarsh) the shipping lanes, the anchorage areas, the presence of firing TractebelUK ranges (and thus risk of unexploded ordnance in the vicinity), an early risk identification and mitigation plan would have been necessary. Such analysis may have minimised cable installation difficulties and reduced the project’s cost overruns. Thisdocument the is property of
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Compared to a detailed onshore route investigation, Tractebel UK has been presented with little detail describing the risks related to the offshore cable installation. It is unclear how these risks were evaluated in the design stage of the project and whether mitigations were put in place by the developer when signing the installation contracts with the different contractors. Tractebel UK is unable to locate an early project risk assessment that considers the offshore cable installation, this is of concern given that the export cable installation is typically the cause of budget overruns on wind farm projects.
PREVIOUS EXPERIENCES Tractebel UK notes that the nearby Lynn and Inner Dowsing projects land their export power cable close to Skegness with a short offshore cable installation route. Tractebel UK was advised (but without documentation) that even for the single Lincs project connection these routes (options 1 and 2) were rejected by the developer due to lack of capacity. Previous experience is an important factor which should have been included in the evaluation of the cable routing especially for the Lincs project in isolation. Knowledge was gained and lessons-learned were available from these already executed cable installations. Awareness about the previous experience with the
already installed wind farms would have been valuable and does not appear to have been utilised during the planning or implementation.
OFFSHORE CABLE ROUTE INVESTIGATION For option 11 the erosional sedimentary regime at the onshore landing site was seen as non viable and therefore this route was rejected. However later investigation performed by the developer indicated that an archaeological exclusion zone and that the River Nene channel was mobile in vicinity of the offshore cable corridor for the selected route option 5. This could result in cable exposure if the channel would pass over this cable route. This
information was further examined in documents [48], [49] and [50], but was not approval written prior without forbidden is parties third to considered in the earlier RPS engineering document and therefore could have altered the cable route assessment outcome.
4.2.1. ‘The Wash’ site surveys
The project’s site surveys which were available (in the data room, later uploaded or transmission or duplication ny mentioned in other documents) before and during the construction phase of the export cables of the Lincs Offshore Wind Farm are chronologically listed in Table 2, followed by a brief summary of these documents. Engineering S.A. A S.A. Engineering
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Table 2: Overview of site surveys
Title report Author Date
Geophysical Survey For Proposed Lincs Offshore Wind May-05 EMU Ltd Farm
Geophysical Investigations at the Proposed Race Bank & May 2007 Docking Shoal Wind Farm Sites with associated cable EMU Ltd route corridors – Section 4: Greater Wash area cable route survey2
Saltmarsh Walkover Survey Centrica January 08
Interim Report 1: Lincs Offshore Wind Farm - (Saltmarsh Harrison Geotechnical August-08 and Landfall Sections) Engineering
Acoustic Surveys for the Proposed Lincs Offshore Wind October 08 EMU Ltd Farm Sites3
Geotechnical report LINCS wind farm export cable route March-09 Fugro survey laboratory and in situ data final report
Geotechnical Design Report Ramboll Wind September-09
Geotechnical Interpretative Report Export Cable Shore December-09 Geomarine Ltd Approach4
Export route sediment transport study HR Wallingford March-10
HDD Works – Trafficability Assessment Geomarine Ltd October-10 /Subocean
to third parties is forbidden without prior written approval written prior without forbidden is parties third to DESCRIPTION OF DOCUMENTS
• By May 2005, a preliminary geophysical survey was conducted by Emu Ltd. Geophysical investigation methods entail the techniques to acquire soil information without making physical contact with the soil itself (e.g. seismic
investigation, bathymetric soundings and magnetometer survey). This transmission or duplication ny covered the Lincs Wind Farm site in the offshore area between ‘The Wash’ and the Humber. This report focuses on the wind farm and export cables. The survey of the export cable trajectories did not come closer to shore than Engineering S.A. A S.A. Engineering
KP2, since marine spreads were used to conduct the investigation. TractebelUK
2Uploaded on 24/01/2013, detailed review within the timescale of the project no more possible
3Uploaded on 24/01/2013, detailed review within the timescale of the project no more possible
4Uploaded on 30/01/2013, reviewed after issuing draft report Thisdocument the is property of
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• In January 2008 a saltmarsh walkover survey was performed by the developer. Information about this survey, other than a map, could not be found in the data room. After consulting with the developer they confirmed that the survey could not be traced. This is an important document since it provides details about the site conditions at an early stage of project development. • The report by xxxxxxxxxxxx (2008) concentrates on the Saltmarsh and landfall sections. This investigation consists of a desk study, a geophysical, and an intrusive investigation. The latter gathering soil information by sampling from boreholes and/or trial pits. • The geotechnical report by xxxx was completed in March 2009 and focused on the export cable route. This comprised of 51 piezocone penetration tests (PCPTs) at 41 locations and 18 Vibrocores at 17 locations. Cone penetration testing is a method to determine geotechnical soil parameters (e.g. resistance, friction,..) in order to determine the soil stratigraphy, whereas vibrocoring is a procedure for obtaining long, well-preserved cores. These soil samples can be further investigated in laboratories. The sample VC/CPT 02 was found closest to shore, located approximately 3.5 km from the first sea defence. • In September 2009, xxxxxxx prepared a preliminary geotechnical design report, for the development of the Lincs Offshore Wind Farm. This report
investigated the 69 wind turbine generator locations. • The geotechnical interpretative report prepared by xxxxxxxxx (2009) investigated the section of the proposed route that lies on the intertidal area consisting of 4 km of saltmarsh and mudflats. They were contracted to focus in particular on the section KP0.67 - KP3.0. xxxxxx carried out 7 cone penetration tests, 4 ballcone penetration test and 6 trial pits. Additionally, they compared their findings with the xxxxx (2008) and xxxx (2008) reports • xxxxxxxxx report (2010), referred to a geotechnical assessment of the bearing capacity of the soils with reference to all-terrain vehicles (ATV) tests carried out on the mudflats and the potential settlement of proposed vehicles. The considered area extended from KP 1 to KP 3. • The report prepared by xxxxxx (2010), investigated historical bathymetrical data and survey data for the landfall section to advice on route selection in approval written prior without forbidden is parties third to the cable corridor between KP 3.5 and KP 8. The purpose of this report was to investigate the risks of cable exposure as a consequence of sea bed level changes and channel migrations.
EVALUATION OF DOCUMENTS ny duplication or transmission transmission or duplication ny Tractebel UK considered the site investigation reports listed above, in particular, the reports which considered the nearshore section (KP0 - KP 1). Xxxxxxxxx report of August 2008, explains that three investigation methods were undertaken: a desktop Engineering S.A. A S.A. Engineering study; a geophysical investigation, (comprising resistivity tomography, seismic reflection and magnetic/metal detection) ; and an intrusive investigation, existing of laboratory testing (chemical, geotechnical and thermal resistivity) of borehole samples. TractebelUK Based on this analysis, the following conclusions were reported in relation to the directional drilling beneath the Saltmarsh / landfall section (see table 3 below): Thisdocument the is property of
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Table 3: Geotechnical considerations/hazards [17]
The stratigraphy thus consists of variable alluvial deposits, underlain by alluvial sands. At around -12 to - 15m aOD (above Ordnance Datum), a layer of Glacial Till (slightly gravelly clay) was identified. In view of the planned HDD works the report identified the presence of a variety of soil types: the Alluvial Sand characterized by saturated collapsible soils and the Glacial till, comprising very stiff soils and gravelly cohesive deposits (occasionally cobbles). These conclusions were based on the sampling from a total of five cable percussion holes (BH2, BH9, BH11, BH12 & BH13) and a single trial pit (TP1) located in the landfall area (see Appendix H). In the saltmarsh area, indicated as a zone unavailable for access and thus for intrusive investigation methods, findings were based on remote geophysical investigation techniques (i.e. resistivity tomography and seismic reflection, see Appendix I). Based on the review of all site survey reports provided, Tractebel UK concludes that the xxxxxxx report (2008) is the only report which described the area where the HDD operations failed. This geotechnical survey covered the land route including both sea defence structures by means of intrusive investigation techniques; however, there was no consent available from Natural England for vehicular access or approval written prior without forbidden is parties third to intrusive investigation of the saltmarsh. Consequently only remote (resistivity and seismic) survey techniques were undertaken on the saltmarsh. These kinds of analysis have a limited penetration depth (seismic) and limited accuracy (resistivity) and should be confirmed by borings.
An important finding of the xxxx report however is the description of the presence transmission or duplication ny of collapsible soils and cobbles. This is indicated in the map of the Saltmarsh Walkover Survey (January 2008) where a short (but important) description of the soil conditions is given (Appendix J). The soil is described as soft to very soft mud Engineering S.A. A S.A. Engineering with a shallow anoxic layer. In relation to the placement of the rollers in 2011 by xxxxx no more information is
available, since the closest location where geotechnical investigation was done, TractebelUK other than the Harrison study, is at 3.5km from the seaward sea defence xxxxx. Thisdocument the is property of
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Xxxxxx (2009) produced longitudinal soil profiles of the planned cable trajectory based on the xxxxx (2008) and xxxxx (2008) reports and their own soil investigations. As illustrated in the figure below, Tractebel UK notes the lack of information between landfall (KP0) and KP1. Whereas the spacing between explorative locations is 500m or less in section KP1-KP4, the zone (KP0-KP1) meant to be crossed by HDD only contained soil information around the landfall (4 BHs), KP0.67 (CPT) and KP1.0 (CPT and trial pit). Thus in the zone where HDD attempts failed, there was no existing soil information. Like the other geophysical/technical reports, Geomarine reported also the consent restrictions of Natural England: “Trial pits were excavated where possible, no trial pits were permitted on the Saltmarsh as it is a site of Special Scientific Interest (SSSI)”.
Given that xxxx was in the possession of both xxxx and xxxx findings which could be field-tested by them, Tractebel UK concludes that xxxxx were best placed to judge the risks associated with a HDD solution. However, the report didn’t investigate the feasibility of the HDD itself. The report discussed the geotechnical aspects of (1) cable trenching options including jetting and ploughing; (2) use of a
jack up platform at the HDD exit, (3) provision of a hold back anchor should an approval written prior without forbidden is parties third to HDD rig or pull winch be located on the jack up platform; (4) grounding of the cable barge on the mudflats at some point between the HDD exit and KP3 and (5) tracking and manoeuvrability of earthmoving plant on the mudflats.
4.2.2. Consents transmission or duplication ny For the chosen cable route the landfall of the two export cables of the Lincs Offshore Wind Farm is located east of the mouth of the river Nene in the Wash. The export cables cross a saltmarsh area with an approximate length of 1 km and further an Engineering S.A. A S.A. Engineering inter-tidal area is present. Both areas are environmentally protected zones with important vegetation, mammals etc and is used as a resting area for migrating birds. This resulted in strict rules being put in place regarding the installation and TractebelUK operation of the two export cables, especially in the 1 km long saltmarsh area, such as
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• Minimal spatial and temporal presence • Minimal machinery and personnel passage. • Work to be limited to the amended annual consent period between May until early September.
With these limitations, installation via HDD was a mandated choice from an environmental point of view. The original FEPA Licence (33574/08/0, [4]) indicates that directional drilling should be used to install the drilled ducts under the sea defences at the landfall. It however does not dictate that directional drilling was to be done under the saltmarsh: "The two export cables will be buried approximately 50m apart as far as the intertidal area and reduce to 5m at the landfall through drilled ducts under the sea defences. The drilled ducts at the landfall will be constructed using directional drilling. The depth of the cable will be approximately between 1-3m depending on ground conditions. The main restrictions of the CPA consent (33574/08/0/CON, [5]) are that works can only take place between 15 May and 31 of August and that any access (by foot or vehicle) on the saltmarsh during cable installation work including directional drilling will only be allowed with the explicit permission of Natural England. These
restrictions are also mentioned in the FEPA consent. The relevant clauses from the FEPA consent are as follows: • 9.58 The Licence Holder will only undertake cable installation operations within the inter-tidal area between 15 May and 31 August • 9 59 The Licence Holder must ensure that access (by foot or vehicle) on the saltmarsh within the Wash SSSI during cable installation work, including directional drilling, will only be allowed with the express permission of Natural England. It is unclear what the developer applied for when seeking consents from the relevant Authorities. Tractebel UK notes that only a consent for the HDD to cross the saltmarsh and the sea defences was initially granted. approval written prior without forbidden is parties third to
4.2.3. Conclusions The selection of HDD without detailed knowledge about the local, but known to be challenging, geology created a risk which the developer implicitly accepted and ny duplication or transmission transmission or duplication ny which contributed to the resulting project delay and cost outcomes. A more extensive site investigation during the pre cable installation period may have led to an initial cost increase, but it is clear that with more comprehension of the site Engineering S.A. A S.A. Engineering conditions some events would have been anticipated and mitigated. This should have been prudent practice and becomes even more important when HDD is
considered. TractebelUK To be able to perform more geological investigations, the initial consents needed to be challenged further. This would have required further efforts before commencing the installation works, Tractebel UK concludes that this may have avoided project delays and increased costs. Thisdocument the is property of
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Tractebel UK notes the difficulties that the project faced and that the consenting arrangements imposed by Natural England created additional complexities.
4.3. Project management
When managing a project of this kind which involves an offshore cable installation with many challenges, early risk identification and the development of contingency plans including mitigations are of high importance. Furthermore, the decision making process within the project management structure when dealing with changes which have a cost impact is vital. Tractebel UK requested information on the project management structure and decision making processes. Responses are discussed below.
4.3.1. Contingency planning Tractebel UK notes that the project did not have in place a contingency plan for failure of the HDD cable installation campaign. The reason given for this by the developer was that only the HDD works were consented. Following the failure of HDD in 2010 Natural England modified their requirement to allow alternative installation methods to be performed. Tractebel UK asked the developer for an insight in the original method statements and the initial contingency plans in place prior to start of the cable installation works. One emergency and contingency plan was uploaded in the data room by the developer on 24/01/2013 (“Lincs Export Cable Inter-tidal Works: Emergency and Contingency plans,”[11]). The version that was provided and reviewed by Tractebel UK is the updated version for the 2012 cable installation works. The previous, original document is dated 11/07/2011., which was after the first attempt to install the rollers and before repositioning them (see chronological overview Appendix C). At that time
(11/07/2011) floating the cable had not been considered, which suggests that the approval written prior without forbidden is parties third to document made available had undergone revisions. The original document was not made available; therefore, it is not possible to comment further on what was considered in the original contingency plan. Another example of the lack of contingency planning is for the roller installation. After the incident of the nearshore export cable loop, the offshore marine equipment was demobilised from site to enable the contractor to prepare contingency transmission or duplication ny arrangements. Tractebel UK concludes that a float-in technique which is common in export cable landings should have been prepared during the risk assessment stage as
a potential alternative to avoid a shift in planning.On 24/01/2013 a mitigation plan A S.A. Engineering
was uploaded in the data room [14]. This document refers to the onshore cable installation only. Mitigation plans for the offshore cable installation were not made
available. This was pointed out to the developer when receiving this document but TractebelUK no additional information in this respect has been provided. Thisdocument the is property of
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4.3.2. Project decision making The decision making process for project changes were discussed during a conference call with the developer on 16/01/2013. Consequently, a number of documents were uploaded in the data room (controlling changes procedure [12] and controlling changes flowchart [13], see Appendix D). The objectives of these documents are described as follows:
• changes to the project scope, deliverables / interfaces, timescales, budgets or resources are formally defined, evaluated and approved prior to implementation
• the appropriate design documents and supporting information are updated and made available for reference The structure of these documents shows that a good project control system is currently in place. However, these documents date from 27/04/2012 and 18/09/2012, after most of the critical decisions on the project had been made. It is unclear how and when these processes were developed but is clear that the process evolved as the cable installation was being performed. The following was also communicated by the developer in a separate communication on the follow up, but also this does not provide clarity on the status at the start of the project: After the developer had reviewed the report, a controlling changes flowchart and
procedure dating from 05/02/2009 was uploaded in the data room (on 26/03/2013). These documents are similar to the above mentioned documents of 2012.
4.3.3. Managing contractors Tractebel UK was informed by the developer that interface meetings were held regularly between the participating contractors (xxxxxxxxx). Additional documents were made available (managing interfaces procedure [40], managing interfaces flowchart [41] and managing interfaces strategy document [39]). These documents are general documents that apply not only for the Lincs
Wind Farm project. The objectives of these documents are described as follows: approval written prior without forbidden is parties third to To ensure the delivery of a wind farm in which all interconnecting and/or interdependent subsystems and components connect together efficiently and effectively, thus enabling the operation of the wind farm systems. Like the project control change documents mentioned above, a good system appears
to eventually have been put in place. However, Tractebel UK concludes that it is transmission or duplication ny unclear whether these documents dates 15/11/2012 and 01/05/2012 are revisions of an older document. For the documents no earlier versions have been seen. Engineering S.A. A S.A. Engineering
4.3.4. Participating contractors
A short overview of the project’s participating contractors is provided below. TractebelUK Xxxxxx scope The scope for the installation of the export cables (and array cables) was awarded to xxxxxx after a tender process. Thisdocument the is property of
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The scope of work of xxxxx was divided into 3 work packages (Contract xxxxx [38]):
• WP1: Management, Engineering, Collection, Installation and Testing of Main Section of the Export Cables (KP8 to KP48), Collection & Installation of Collector and Array Cables, Construction of Transition Joint Bay and jointing to onshore cables, jointing the Nearshore section and the Main section of the Export Cables (KP8), pre-installation surveys, route clearance, pre-lay grapnel runs, cable protection, post installation surveys and cable storage facilities
• WP2 -a: 2 x 1000m Sea defence/saltmarsh Ducts, installed by Horizontal Directional Drilling (HDD) -b: Marine Support for HDD Operations
• WP3: Collection, Installation and Testing of Sea Defence and Nearshore sections of the Export Cables(from Sea Defence to KP8)
WP1 and WP2a were Lump Sum based, while for WP2b and WP3 a Provisional Sum was set (within which bought items to be charged at cost plus). Taking into account the uncertainties and challenges in the nearshore work and that the methodology was not fully developed at the moment of closing the contract, WP2
and WP3 were agreed to be subject to a combined cost cap.
Initially the following schedule for completion was foreseen:
• WP2: end of August 2010 • WP3: end of August 2011 • WP1: end of January 2012
Using the information in Appendix F, it has been possible to compare in detail the planned versus actual planning (status 24/06/2012) for the project. The first export cable was installed and tested by March 2nd 2012 (planned July 31st 2011), the th second export cable was installed and tested by late 2012 (planned August 20 approval written prior without forbidden is parties third to 2011). Xxxxxx scope After the insolvency of xxxxxxxx , xxxx took over the contract scope and a new cost plus (rather than lump sum) contract was signed on 7/03/2011. ny duplication or transmission transmission or duplication ny As a result of changes in the installation methods (abandoning HDD works, installation by chain trenching) part of the xxxxx scope was taken over by xxxx in 2011. When changing the export cable onshore pull-in method to floating, a new Engineering S.A. A S.A. Engineering
contract was signed with xxxxx Offshore. The installation of the second nearshore export cable in 2012, was awarded
following a tender process to xxxxx. The cable trenching contract was subject to an TractebelUK amendment to the contract with xxxxxx. Thisdocument the is property of
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The offshore jointing works were undertaken by xxxxx who supplied the marine spread, while xxxxx undertook the jointing work. The transition joint bay was contracted with xxxxxx. (Post lay burial (joint locations and remedial) was performed by xxxxxxxxxxxxx undertaking further burial works to achieve the export cable burial depth. An overview of the participating contractors related to the different installation works can be found in Appendix G.
4.3.5. Conclusions Tractebel UK concludes that the developer has now established good project management controls. It is also clear that there was an evolution of the developer’s approach to project management during the project. Tractebel UK notes that the project faced a number of issues which required decision making under time pressures and alternatives were often not examined thoroughly. For example, when HDD and the use of rollers failed, these difficulties could have been prevented if alternatives were set out at an earlier stage with risks being identified and mitigated. It should be noted that daily activity reports, incident reports, root cause analysis etc,
could have provided a clear understanding of the project management during the cable installation and how the board was informed about incidents. Such documents were requested but were not made available during the writing of this report. The insolvency of xxxxxx and the change in cable installation methodology, led to 4 new contracts (xxxxxxxxxxxxxxx). Tractebel UK notes that the xxxxxxx contract was sourced on a cost plus base, placing more financial risks with the developer. The scope of the jointing works increased due to incidents offshore and was not part of the original scope of xxxxxx contract (3 unplanned joints were needed, KP18, KP44 and KP 44.4). The increase in contractual parties required additional interface management by the developer. This created additional complexities and risks for the
project if one of the contracting parties is unable to keep to their planned timetable. approval written prior without forbidden is parties third to Although appointing different contractors for different scopes can lower the initial project’s cost, the project management interface will create challenges resulting in high level of interface management. Tractebel UK believes that by this decision the developer has raised the risk on cost increases within the Lincs Wind Farm.
transmission or duplication ny Engineering S.A. A S.A. Engineering
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5. CABLE INSTALLATION WORKS
5.1. Introduction
During the installation of the export cables of the Lincs Wind Farm (2010-2012) a number of delays and/or incidents occurred. These events mainly took place in the nearshore section of the cable route. This nearshore section runs from a sea defence embankment (Kilometre Point 0, KP0), through a saltmarsh (KP1) over an inter- tidal area which is 8 km long (KP8). The region forms part of 'The Wash' and is of high environmental importance. The planned consent window for the nearshore activities was from 15th May to 31st August but was amended each year (see Appendix C: The Time Line of Events) A map that gives an overview of the cable corridor can be found in Appendix E.
5.1.1. Summary of events The sequence of the events is described below:
•
2010: To cross the saltmarsh, Horizontal Directional Drilling (HDD) was the chosen installation method to avoid direct impact to the saltmarsh vegetation. After several attempts it seemed that the ground was too soft to have a stable borehole. This installation method was finally abandoned due to the soil conditions. The consent window of that year was lost and moreover the contractor (xxxxxx) faced insolvency, resulting in an early closure of this contract and necessitating the developer to set-up a new contract (xxxxxxx).
• 2011: The consenting authorities (Natural England, MMO), agreed to a revised installation methodology using chain trenching. The installation of the export cable took place on a barge (UR101) with an All-Terrain Vehicle (Nessie V) using rollers tracking over the nearshore area. However, when the ATV started to pull the cable, a loop occurred, due to allowing too much cable to leave the barge approval written prior without forbidden is parties third to while the pulling over the onshore installed rollers faced difficulties. After evaluating the situation, it was decided that the most favourable way to restart the operation was to cross the saltmarsh by floating the cable to shore. This led to preparing a revised methodology (which is a common technique in export cable landings), resulting in new contractors and further cost increases.
Tractebel UK notes that due to subsequent delays (for example, the trenching transmission or duplication ny vehicle Nessie III that got stuck) only one of the two nearshore cables could be installed during the consenting window of 2011.
Engineering S.A. A S.A. Engineering
• 2012: For the installation of the second nearshore cable, the developer used the float-in technique that was eventually successful in 2011. These works were
undertaken by a different contracting party (xxxxxx xxx). During this installation TractebelUK there were delays caused by a late installation of the flume pipes (to cross creeks). Thisdocument the is property of
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Besides the nearshore installation delays, there were also further delays and incidents during the main cable installation (plough incident) and the jointing works (beam failure during redeployment after jointing works), as well as incidents during the load-out of the export cable (cable damage during the Factory Acceptance Test) and storage of a spare cable. Furthermore as mentioned above due to the insolvency of the original contractor for cable installation (xxxxxx), different contractors participated in the installation works. This led to a higher level of interface management for the developer and a higher risk for (consequential) delays when one contractual party cannot keep to their planning timetable. All the above have led to cost increases and project delays. In Appendix C a time-line of the different events is given per activity.
5.2. 2010 Nearshore cable installation using HDD
To install the first 1000m of the export cables which cross the sea defence and the saltmarsh, HDD was the planned methodology, even though no detailed geotechnical investigation data was available in the saltmarsh area. The HDD works were executed by a marine spread with drilling equipment on two barges.
Between April and September 2010, six HDD attempts were performed, with drilling taking place offshore and onshore. These attempts failed in the unexplored saltmarsh zone (hole collapse, drilling rig got stuck , see progress diagram of the HDD works Appendix K, [2], failure of the HDD occurred on each occasion under the saltmarsh). HDD is a good method of installation when sensitive land areas have to be crossed, without disturbing the surface. However, it is important that soil conditions are well known before commencing such works, since unexpected bottom soil conditions can lead to loss of drill mud and early collapse of the drilled hole. Stability of the drill hole, at least until the power cable is pulled through the predrilled hole, is essential. Execution of HDD without a detailed soil survey to the depth of drilling constitutes a project risk. approval written prior without forbidden is parties third to This guidance is also confirmed by the later provided reports from xxxxxxxxxxxx [43] where it is stated: “It is recommended that one borehole should be taken at three different locations along the duct path during ground investigation studies prior to installation in order to establish the exact geotechnical parameters of the local ground conditions.” transmission or duplication ny And Engineering S.A. A S.A. Engineering
“It is recommended that at least 3 test bores be undertaken at the salt marsh area as part of the Marine Route Survey prior to drilling. Dependent on the test result data xxxxxxxxx would recommend the use of HDD technology for the Centrica Wash
project.”(Tractebel UK underlining) TractebelUK These reports were made available by the developer on 26/03/2013 and 21/03/2013.
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After the 3rdattempt to install the drilled duct there was a meeting held between the developer, xxxxxx and Natural England to discuss the installation difficulties. From the minutes of meeting [6], it’s clear that alternative installation methods were suggested by the developer / xxxxxx, however, Natural England confirmed they were unwilling to deviate from a HDD solution. This demonstrates that the developer (and xxxxxxx) took action when it was clear that HDD would fail. Nevertheless, as also indicated in the minutes of the meeting, it was acknowledged by the developer that the request for an intertidal trial (to see if an excavator was non intrusive) in 2010 had been submitted to Natural England, but it was too late to be carried out before the end of that year. Tractebel UK concludes that early engagement with Natural England to obtain a consent to explore the area by means of intrusive investigation methods could have been a useful precautionary step in managing risks. Tractebel UK notes that the xxxxxx report ([17], see 4.2.2.1) identifies the presence of collapsible soils and cobbles, and therefore could be seen as an early warning for the possible failure of the HDD.
5.2.1. Conclusions Execution of HDD without a detailed soil survey to the depth of drilling constitutes
a high project risk. Tractebel UK concludes that the developer could have challenged the consenting authorities to obtain permission for a geotechnical survey. This would have allowed the developer and its contractors to inform the Authorities of the associated installation risks. Furthermore, since there was no geotechnical information about the saltmarsh available, the risk for an unsuccessful HDD campaign needed to be anticipated and alternative installation methods should have been prepared and discussed with the licensing Authorities up front. Tractebel UK was informed by the developer, that there was no contingency plan for the HDD works since the consent prescribed HDD drilling under the sea defense structure. Due to the unsuccessful HDD campaign in 2010, a new methodology and thus further engineering needed to be performed which led to a project cost increase. approval written prior without forbidden is parties third to Furthermore with the spread of the drilling equipment on the two barges, the initial cost of xxxxxx increased, costs that later on proved to be excessive. Cost impacts of the above can be seen in the first row of the overview table under section 5. ny duplication or transmission transmission or duplication ny
5.3. Chain Trenching and installation with rollers
2011 A S.A. Engineering
After the failure of the HDD campaign in 2010 and xxxxxx collapse, alternative installation methods were discussed with a number of parties (authorities, TractebelUK contractors). Following several meetings with the licensing Authorities consent was granted for chain trenching. In conjunction with the contractor xxxxxx, modifications were made to an existing cable trenching vehicle (xxxxx) and a new cable laying vehicle was developed (xxxxxx). Thisdocument the is property of
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For the nearshore cable-installation, the xxxxxxx installation methodology was based on rollers to be placed in the inter-tidal area to transfer the cable from the grounded position of the cable lay barge to the xxxxx vehicle. This new installation method did however not maintain the planned timing of the project and a number of difficulties were encountered, as described below.
5.3.1. Cable Float in The alternative methods focussed on different burial alternatives (see Table 4, [2]).As indicated in Table 4, the Trench Duct was the most favourable option. To transfer the cable from the UR101 (the nearshore cable installation barge), to the xxxxx, however, only the installation of rollers along the route was considered. Tractebel UK was informed by the developer, that the experience of the contractors (xxxxx and xxxxxx) was followed at that point. As mentioned in the history review document, the float-in method and the use of rollers are both widely used for subsea power cable landings. Cable float-in is a typical landfall cable pull-in technique. Following the failure of HDD a risk matrix was created by the developer for the alternative options as shown below in table 4 [2]:
to third parties is forbidden without prior written approval written prior without forbidden is parties third to
Table 4: Developer Option Matrix after failed HDD campaign of 2010
transmission or duplication ny Taking into account the difficult work conditions (saltmarsh, very poor surface soil strength) and the fact that a disturbance of/access to the ground was limited by Engineering S.A. A S.A. Engineering consent arrangements, Tractebel UK concludes that the float-in method should have been considered by the developer at an earlier stage and not only in reaction to the failure of the marine spread with rollers. The float-in method is an environmental more friendly installation approach but it is understood from the developer that it TractebelUK had concerns over whether there was sufficient water depth to facilitate this solution. Thisdocument the is property of
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Furthermore it was mentioned in the history overview [34] that at the time of the loop (July 2011) during the first attempt with the rollers, ‘it had been seen first-hand by both the contractors and the client representatives just how little wave or current action there typically was in the inter-tidal area’. Taking into account that already a year of activities (2010) occurred on site before starting to use the rollers, it seems that the float-in method should have been recommended or at least discussed with the contractors by the developer prior to the start of the works in 2011.The Saltmarsh Walkover Survey of January 2008 (see Appendix J,[3]) also gave an indication of the soft to very soft mud being present. According to the developer floating of the cable was not considered as the consent window (15/05-31/08) was outside the high tides in Spring/Autumn and it was estimated that there would not be sufficient water along the cable route. It was considered by the developer that floating would be more costly, time consuming and constitutes a greater project risk. Tractebel UK concludes that the float-in method was prematurely abandoned (it wasn’t even part of a contingency plan). Moreover the Mean High Water level has been indicated on drawings (see Appendix H) to be near to the first embankment, thus providing sufficient floatation means. This was also proven by the fact that the method was eventually successfully performed.
5.3.2. All-terrain Vehicle After the consent for chain trenching was granted, there were trials conducted with the xxxxx. According to the xxxxx contract, first trials were undertaken in Germany. There is no information about the site conditions in Germany, so it’s not possible to evaluate if these trials were of relevance when working in ‘The Wash’ area. Tractebel UK understood these trials were undertaken to demonstrate that the xxxxx was able to cross creeks. The first trials performed at the site of Lincs on 17/05/2011 were unsuccessful, since the ground was found to be much softer than anticipated. After recovery of the All Terrain Vehicle (ATV), the support vessel (xxxxxxx) returned to port and contingencies were prepared (18/05/2011). The developer advised of a contingency approval written prior without forbidden is parties third to plan but this was not revealed to Tractebel UK. Nevertheless it took 10 days to be able to resume works (not taking into account the delay due to the advice from Natural England to stop the works until the 6th of June 2011). During operations on 23/08/2011 at KP1.048, xxxxx got stuck. To provide tow
assistance a winch was required on the GKS. Operations were stopped for 6 days. transmission or duplication ny It’s unclear if this was a risk that was taken into account before the start of the operations. Since during trials it was confirmed that the site conditions were very soft, this event should have been anticipated. Engineering S.A. A S.A. Engineering
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5.3.3. Use of Rollers A first attempt to place the rollers was made on 08/07/2011. The rollers were placed from the same support vessel (GKS) as the vessel from which xxxx was launched for the trials. The trials with xxxx in the inter-tidal area started on 17/05/2011. The first trial failed and a second (successful) attempt was made between 09/06/2011 and 13/06/2011. Roller placement commenced on the 8th of July 2011, one and a half months after the GKS first came on site. First deployment failed due to the extremely soft soil conditions (after HDD works). After that a route change was agreed and the rollers were repositioned on 15 and 16/07/2011. Since it was known that the working area provided challenges and access to the inter-tidal area was only consented (prior to negotiated changes) between the 15th of May and the 31st of August, it is not clear why time was lost before starting to place the rollers or why deployment of the rollers and the xxxx was not performed simultaneously.
5.3.4. Roller spacing For the pull-in of the nearshore export cable a roller spacing of 9.5m was used, based on previous experience of xxxxx handling another subsea power cable in
Germany. As mentioned above, when the xxxx started pulling the export cable from the barge (UR101) along the pre-positioned rollers, a cable loop occurred. In the history overview it is mentioned that after the loop the roller spacing was called into question. The cable was allowed to go slack between the rollers, which is the result of paying-out too much cable from the barge while the pulling over the onshore installed rollers faced difficulties. This interface risk should however been mitigated by clear communication between the different contractors. For example, monitoring of the tensioner read-outs and the cable departure angle at the chute of the barge (angle measurement tool at the cable chute, continuous visual check at the chute, etc.) should have led to an all stop being called on the cable installation barge.
One of the documents available in the data-room is a document from xxxxxx approval written prior without forbidden is parties third to describing the cable installation and handling parameters [1]. In this document the expected cable stiffness range and related behaviour is listed. In the same document of xxxx a maximum allowable unsupported cable span is mentioned. For a cable were no tension is applied, centre distance of cable rollers is mentioned to be as short as 1 - 1.5m for the Lincs export cable. It is mentioned in the history overview
that during load-out at xxxx a roller spacing was used of 3m (i.e. cable under transmission or duplication ny tension). We understand that the developer’s client representatives were present during the load out, a roller spacing of 10m as suggested by xxxxx should have been followed and insisted upon by the developer during review of the method Engineering S.A. A S.A. Engineering statements. Tractebel UK has reviewed a report of Longitude Engineering [10] describing simulations that were made of the spread for the pull-in of the cable from the grounded barge at KP2.4 to xxxxxx. The simulations had the goal to investigate TractebelUK cable tensions, bend radius and loads on the cable rollers. A quick review (note that we only received this document amongst others on 24/01/2013) of the report shows that no evaluation was made about the roller set up, nor the stability of the rollers in the Wash area. The set up with roller spacing of 10m was used as input data and was not challenged. Thisdocument the is property of
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5.3.5. Conclusions The float-in method is a standard landfall cable pull-in technique which should have been considered at an earlier stage and not just in reaction to the failure of the marine spread with rollers. Taking into account the difficult work conditions (saltmarsh, very poor surface soil strength) and the fact that a disturbance of/access to the ground was to be limited as much as possible; the float-in method would have been the preferred choice at the start of installation. Due to the time lost during operations, only one nearshore cable could be installed in 2011. Hence installation works were extended into 2012. This meant additional contracts (e.g. xxxxx ) and an amendment to the xxxxxxx contract. If detailed planning including risk assessment had been carried out prior to 2011 work being started it is believed that all work could have been successfully completed removing the need for any installation work in 2012 In addition these delays caused the previously planned joint at KP8 of the second export cable (EC2) had to be postponed requiring 2012 mobilisation to complete. Furthermore due to the second nearshore cable being loaded on the UR101 but not installed , this barge could not be demobilised after installing part of the array cables (winter 2011-2012, see also discussion below).
5.4. Chain Trenching and float-in installation 2012
For the nearshore campaign of 2012 a tender process for the Cable Landing Contractor led to a different contractor (xxxxx instead of xxxxx in 2011) to be appointed. This also resulted in a different grounding barge than the UR101.
5.4.1. Standby UR101 After the installation of the first nearshore export cable in the summer of 2011, the to third parties is forbidden without prior written approval written prior without forbidden is parties third to UR101 started the installation of the array cables. It is unclear how long the installation of the array cables took and how long the UR101 was on stand-by before the 2012 export cable campaign (with the second nearshore export cable on board). But in an early summary of variation orders of xxxxx reference is made to variation order 26 (VO 26) referring to UR101 actuals from July to the winter close down. In the project timetable of September 2012 the installation of the inter-array cables with the UR101 is mentioned to be 80% complete. In the timetable of October 2012 transmission or duplication ny it is no longer mentioned. Further explanation was asked by the developer and apparently not all array cables Engineering S.A. A S.A. Engineering could be installed during the summer campaign of 2011, since not all cables were supplied (see also section 5.8) Stand-by of UR101 is therefore assumed to have been from December 2011 until March 2012 when preparation towards commencement TractebelUK of outstanding installations could commence. Thisdocument the is property of
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5.4.2. Flume Pipe installation in 2011 & 2012 Installation of the flume pipes at ‘Big Tom’ creek in 2011 was done by the support vessel of xxxxxx (shallow water barge, xxxxxx), together with the deployment of the rollers from that same barge. As mentioned in the storyboard for the Lincs nearshore installation of 17/03/2011 [7], it was the intention to recover this temporary crossing after the second cable installation was completed. Since the second nearshore export cable could not be installed in 2011 (due to closing of the consent window), we assume that the flume pipes were recovered as was foreseen in 2011. From the presentation to MMO/NE/EA on the 9th of November 2011 [9] it is clear that the initial plan for the 2012 installation of the flume pipes was to install them approximately from the 4 – 7 May. However in the history overview it was stated that unsuccessful attempts to install the flume pipes were undertaken on the 20thand 21st of April 2012, with the eventual installation occurring on 5 June. The reason given for these changes in plan dates was the preference for flume pipes installation around the spring tides. For the nearshore campaign 2012 other support vessels were used for the trenching operations (xxxxxxxx). As mentioned in the history overview these support vessels were contracted and managed directly by the developer.
Tractebel UK concludes that by contracting directly with the landing vessels risks of delays are transferred from the contractor to the developer. As such when the support vessels did not complete some works to the schedule stand-by costs for other contractors can be claimed from the developer. Although some costs may be transferred to the support vessel contractor, it is most likely that s an increase in spend will occur in such a situation. Furthermore following the consent timeout period the remobilizing of the workforce in 2012 meant a loss of delivery momentum. Finally during operations on the 10thof June 2012 there was also a failure from the
tow assist rope of the xxxxxx. It took 9 days before a new tow rope was produced. approval written prior without forbidden is parties third to This seems however another event that should have been anticipated. This scenario however is not described in the Emergency & Contingency Plans for the inter-tidal works of 2012 [11].
5.4.3. Conclusions ny duplication or transmission transmission or duplication ny Compared to the event during the 2010 and 2011 cable installation campaigns, the delivery of the 2012 schedule went with little incident. However xxxxxx left site as a result of the flume pipes not being installed and had to come back at a later stage. Engineering S.A. A S.A. Engineering Due to reinforcements needed to the flume pipes, installation works were delayed. Some of the Lessons learned from the similar 2011 installation will have been lost since different support vessels were contracted by the developer in 2012. TractebelUK Thisdocument the is property of
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5.5. Main cable installation
5.5.1. Plough-incident The main cable installation was done by simultaneously laying and burying by ploughing. During installation of Export Cable 2 (EC2), the first cable that was installed) a plough incident occurred at KP18.374. The cause of this incident is not properly controlled cable pay-out rate during a transitional operation, where harder seabed conditions had been encountered. The plough team was reducing the vertical angle of tow wire pull on the plough, meaning a drop in plough speed. When at that specific moment the speed of feeding the cable isn’t dropped simultaneous, there is a risk of the cable getting trapped behind a skid of the plough. Since speed and tensions both of the plough and the cable are monitored, as well as the entrance angle of the export cable at the plough’s bellmouth, the cause could be evaluated as a human error of the plough operator. This can never be fully excluded during operations and in our opinion can thus be evaluated as an incident. Similar plough incidents have already occurred on other projects as well. Note that the plough incident is also an (outstanding) CAR insurance claim.
5.5.2. Spare Export Cable Storage An ITT was issued only on the 12th October 2011 for the storage of the excess cable lengths (estimated as 3.5km), which appears rather late considering that the installation of the main cable was expected to finish a month later. On the other hand it was not until the 12th of October 2011 that the load out at xxxxx (cable supplier) was finished and thus a good estimation of the excess cable lengths could be made. The tendering process was relative short and 2 days after ending the installation of the main export cables (18th of November 2011) the xxxx could deliver the cable to the successful bidder xxxxxxx. This fortunately made the standby time for the
xxxxxx a minor cost. approval written prior without forbidden is parties third to The question was raised to the developer why wet storage of the cable was not considered, which is a common technique. The developer replied that since the site was completely dependent on consents this was not an option. However, the windfarm concession area could have been considered and cable storage should have been contractually set from the beginning. Even when taking into account the cable supplier’s length margins and an estimate of the minimum cable length needed transmission or duplication ny (without taking into account cable snaking and with the knowledge that at the cable route alter courses the route cannot exactly be followed thus corners are cut within
the cable corridor), a judgement on spare cable lengths could have been made at an A S.A. Engineering
earlier stage. We believe that only in a late phase of the cable installation the storage of a spare TractebelUK cable or excess cable length was considered. Thisdocument the is property of
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For information, we noticed that according to [1] a special made steel reel for holding up to 400m export cable, main section, for transportation and storage was delivered by xxxxxx. We assume that this reel was used to store the 300m spare that was offloaded from the UR101 at Sunderland between 30th March and 31st March 2012 (after transloading the 300m spare from the Discoverer onto the UR101 on the 16th and 17th October 2011). In any case the reel from xxxxx wouldn’t have been sufficient for storage of the excess cable lengths.
5.5.3. Anchor trials The cable corridor which was chosen runs through the Wash and passes anchorage locations as Boston Anchorage, Kings Lynn Anchorage and Sutton Bridge &Wisbech Anchorage. At these locations vessels are allowed to anchor and wait for entering a port in the Wash area. Although originally set forward by the harbour authorities, achieving a cable burial depth of 5m between KP8 to KP20 is highly challenging to impossible. The developer opted to perform anchor trials in order to assess the expected maximum penetration of anchors being deployed. The aim was to demonstrate that a 3m deep export cable burial would suffice in order to avoid anchor damage and achieve agreement from the harbour authorities, since at that time there was a lack of consent for a 3m burial between KP8 and KP20.
It appears that the first anchor trial with the tug boat xxxxxxx (April-May 2011, facing a lot of Weather Down Time), had to be repeated by a dedicated DP2 dive support vessel (DP Reel). These trials appear to be performed at a late stage and were not indicated at the start of the project. However, as this was important not only during the installation stage, but also during the later operation and maintenance phase of these export cables transmitting the full power from the wind farm to the shore, this risk was known from the start when the cable corridor was chosen and should have been mitigated prior to contracting the export cable works.
5.5.4. Conclusions Due to the plough incident a delay of 8 days for the installation of the main export cables occurred. Also additional jointing and post burial needed to be performed. approval written prior without forbidden is parties third to Indirectly this incident also led to another additional joint caused by a beam failure when deploying the jointed cable. At this moment it is unclear what the impact was of the anchor trials but they were found in a change note for an amount close to 1 million pounds sterling. ny duplication or transmission transmission or duplication ny Engineering S.A. A S.A. Engineering
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5.6. Jointing works and post lay burial
Jointing works and post lay burial of the export cables went rather smoothly, although some further burial works had and still have to be conducted to achieve an acceptable level of cable burial. The outstanding area is located along KP 44 (thus inside the wind farm concession area) and burial will be scheduled in 2013. The developer informed us that there is one location along the export cable route where the cable only had a 0.5m cover (chalk area) , while others mostly comprised covers or around 2-2.5m with a target that set the burial originally at 3m. If the authorities do not accept the current burial results, there is a risk of having an additional post- burial campaign along some routes. Where further cable trenching attempts would not be successful, local rock dumping by for instance a fallpipe vessel or mattress installation might be needed. During jointing operations, there has been one incident at KP18 due to a failure of the cable lifting beam of the xxxxxx while over-boarding the cable after jointing works completion. This resulted in an additional joint (double repair joint), since during the uncontrolled deployment the minimum bending radius (MBR) of the cable was not respected. This event is an (outstanding) insurance claim and in our opinion can be evaluated as an incident.
5.6.1. Conclusions An estimation of the cost of the burial works that are scheduled around KP 44 at the time of writing this report is indicated in the cost template of November 2012 (see section 5). Section 5 also provides more detail on the additional cost increases of the joints linked to the incidents under CAR evaluation. Due to the beam failure an extra joint needed to be performed. Also guard vessels were needed due to the fact that burial was not immediately performed due to several delays. Some of these costs are part of the breakdown of the cost template,
but could not clearly be appointed. approval written prior without forbidden is parties third to
5.7. Cable supply by Contractor ny duplication or transmission transmission or duplication ny On 19/02/2008 the contract for the supply of the cables was signed between xxxx and the developer.
The initial requirement for export cable was defined by the developer as: A S.A. Engineering
• 2 x 48,000m lengths of 132kV 630mm² cable (within which any cut point
between nearshore and main lay lengths to be advised if required) TractebelUK • 1 x 400m length of 132kV 630mm² cable as spare • 2 x 865m length of 132kV, 1200mm²Sea Defence Crossing cable (optionally to be factory jointed to the 630mm²lengths, a similar operation had been undertaken on the LID 33kV export cables). Thisdocument the is property of
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Due to changes in the installation methods, a different cable section to cross the Sea Defence was no longer necessary. Both export cables are of identical cross section with trefoil 132kV AC 630mm²conductors and incorporating a fibre optic bundle under single wire armour and yarn outer sheath. Both export cables were aimed to be manufactured before the 2nd half of 2010 (according to Approval For Commitment). In January 2009 a first contract amendment set the supply dates for the export cables as follows:
• Landfall section export cable 1 & 2 and main section export cable 1: within period of 60 days commencing on the 14th of July 2010 nd • Main section export cable 2: within period of 60 days commencing on the 22 September 2010
In July 2009 a second amendment was made to the contract, changing the key dates from 14/07/2010 to 03/05/2011 and from 22/07/2010 to 15/06/2011. A third contract amendment (February 2011) changed the supply dates as follows:
• Sea Defence section export cable 1: within a 15 day period commencing on 15/03/2011 • Nearshore section export cable 1: within a 60 day period commencing on 15/04/2011 • Main section export cable1: within a 60 day period commencing on 03/05/2011 • Sea Defence section export cable 2: within a 15 day period commencing on 15/03/2011 • Nearshore section export cable 2: within a 60 day period commencing on 15/04/2011 • Main section export cable 2: within a 60 day period commencing on 15/06/2011
5.7.1. Delay of Supply
During load out of main export cables 1 and 2 a cable fault was found. Visual approval written prior without forbidden is parties third to armour damage was noticed. After root cause investigation it was reported that the armour damage was a result of the factory acceptance tests (FAT’s, [23] and [24]). After complete visual inspection of the export cable 1, it was offloaded for a factory repair. For export cable 2 it was decided to perform an offshore joint (initially this would be done by (xxxxxx).
As a result of the discovery of the faults delays occurred in the installation and transmission or duplication ny associated standbys of vessels (xxxxxxxxx). Detailed events of the load out of the cables can be found in the overview in Appendix C. These delays were not only due to these cable faults, but also unavailable load out equipment which was the Engineering S.A. A S.A. Engineering responsibility of xxxxxxxx. As far as the cable faults concerned with the Quality Plan of the FAT and the sequence followed during these tests it appears not possible to notice the faults at an TractebelUK earlier stage before load out took place. Also a concern with the manufacturing procedures is that an earlier indication of the damage seems not possible. Thisdocument the is property of
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The Control Plan for Manufacture shows that there are no continuous checks (at 360° around the cable) on the different construction layers of the cable (where the problem had occurred) during manufacture. Only spot examinations were done. It was unclear if a representative of the developer was onsite monitoring the cable manufacturing continuously. Furthermore the root cause of the damage is not explained in the xxxxx Technical Report on the observed cable damage. There is only an assumption by xxxxx that the AC test has accelerated the burning/melting of the cable which was already faulty. However, it was not explained why, before FAT, there was already a weak point in the bedding (or possibly the semi-conductive PE layer). It is explained that the AC test during the FAT (even if passed as for EC2) has reached enough voltage to create an arc at the weak point and maintain the melting during the whole duration of the AC test. The question arises why for equivalent design and length, this problem had not occurred and why a system to control continuously the thickness of the different layers during the manufacture cannot be implemented.
5.7.2. Storage costs spare cable xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
5.7.3. Conclusions The part of the installation of the export cable that was most affected by the above mentioned delays was the scope of the xxxxxxx. Timetable of load out of the cable to this barge shifted from completion on 30/05/2011 to 21/06/2012 and eventually to 09/07/2011. Actual sail off of the xxxxxx from Halden (xxxxxx) was on 05/07/2011 with only one main export cable loaded. Due to the incident, Discoverer had to return second half of September 2011 to load-out the other main export cable. Also as a result of the cable fault and the delays, UR101 eventually left Halden with
only one nearshore cable loaded. Before performing operations the second nearshore approval written prior without forbidden is parties third to cable was spooled to the UR101 when the xxxxxxx arrived in Sunderland. Together with weather downtime another 15 days were lost for the xxxxxxx due to this transpooling. For the UR101 also some delays were thus encountered. On the other hand in relation to the trenching operations, the UR101 could not start the installation works, since the ATV’s were not ready on site. transmission or duplication ny Concerning the cable xxxxx there were some outstanding variation orders between the developer and Nexans. These pending variations were settled with a signed Engineering S.A. A S.A. Engineering agreement (addendum 4 to the contract) in December 2012. However the amount settled for is about £1.7m less than anticipated in the cost template of November 2012 (see section5), thus increasing further the project costs. TractebelUK Thisdocument the is property of
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6. OVERVIEW OF CLAIMS
In relation to the export cable installation the following incidents resulted in insurance claims:
• Plough incident at KP18 of 17/08/2011 • Beam failure during deployment of the joint at KP18 on 18/11/2011 • Pull-in incident nearshore east export cable (EC1) with Nessie V at KP2.2 on 18/07/2011 (cable loop) • Cable damage EC2 that occurred during FAT test and was noticed while the cable was loaded out on 10/05/2011 (joints KP44). For the plough incident and the beam failure incident full interim payments were received of £440,000 and £588,000. The claims that were set forward towards the CAR insurer were £3.78mand £1.57m, with the costs possibly being reallocated between these two incidents. The combined interim payments (£1,028,000) are incorporated in the cost template as part of the Jointing Works (see Appendix M). Concerning the nearshore pull-in incident a value of £2.9m was claimed for. As explained by the developer, the insurers are not convinced that the installation method used with rollers was correct in the given situation and discussions about the final amount are still on-going. The developer informed that an amount of £520,000had been set as possible to achieve. The EC2 cable damage claim was advised as £ xxxxm. The developer informed that based on the latest discussions with the loss adjuster a payment of xxxx is achievable. Negotiations with the cable supplier xxxxxx were also still ongoing. On 25/01/2012 Tractebel UK received a copy of the final settlement between xxxx and the developer dated from 21/12/2012.xxxxxxxxxxxxxxxxxxxxxxxxx. In Table 5 an overview of the claims is given. As can be seen currently there is a large difference between what was claimed for and what is expected to be recovered.
But negotiation with the CAR insurer is still ongoing. approval written prior without forbidden is parties third to The developer would also need to breakdown the claimed values in more detail, listing the contractual parties involved and support the costs with a technical background.
ny duplication or transmission transmission or duplication ny Table 5: Table redacted
6.1.1. Conclusions A S.A. Engineering
An overestimation of insurance payments is considered likely, which may result in a further cost increase. The exact amount of this increase is still to be determined, TractebelUK since there is not yet a definite settlement of the claims. With the available information we estimate that at least an increase of £xxxx m is to be expected (based on the expectations and the real settlement between the developer and Nexans). Thisdocument the is property of
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Furthermore all contractors have been paid except for Technip where according to the developer final account discussion are on-going and would only relate to a minor amount (estimated as £xxxxx). The developer is thus covering the amount not paid by the CAR insurer at this moment, while it should be challenged whether the contractors themselves should not bear these costs.
7. PROJECT COSTS
7.1. Breakdown indicative transfer value July 2011
Ofgem appointed Grant Thornton as financial advisers to perform an initial forensic accounting investigation to check on the completeness, accuracy and correct allocation of costs for the Lincs Wind Farm. In its letter of 13/07/2011 to the developer, Ofgem confirmed that the indicative transfer value for the Lincs project would be set on £85.4m for the submarine cable
costs, this value was confirmed by Grant Thornton to be derived as indicated in table below (Table 6).Reference is made to “Draft report to Ofgem on the offshore transmission second transition tender round – Ex ante cost review of LincsWind Farm transmission assets”[37].
Table 6: Table Redacted
7.2. Breakdown status November 2012
The cost template received from the developer updated for January 2013 indicates a approval written prior without forbidden is parties third to total value of £ xxxxxx for the submarine cable installation. This is an increase of £ xxx m since the ITV was set for the project. An overview of the cost increases is set out in Table 7.
ny duplication or transmission transmission or duplication ny Engineering S.A. A S.A. Engineering
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Table 7: Table Redacted to third parties is forbidden without prior written approval written prior without forbidden is parties third to ny duplication or transmission transmission or duplication ny Engineering S.A. A S.A. Engineering
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7.3. Examples of variation orders
7.4. Conclusions
As indicated in Table 7 Tractebel UK concludes that the HDD works in 2010 and the 2012 shore end works are costs that are not economically and efficiently incurred . At a high level these costs equate already to more than £ xx m of the project’s cable cost increases. This value was derived by summing the xxxx 2010 costs equal to £xxxxx and the 2012 shore end works equal to £ xxxxx In the pre-development stage of the project a detailed project risk assessment should have been conducted and contingency plans should have been developed. This may have led to different installation methods being chosen and/or mitigations set in place. The 2010 xxxxx works which was the attempted HDD approach did not
contribute to the final cable installation and the 2012 works would have remained within the original 2011 planning. Therefore Tractebel UK concludes that these
costs are not economically and efficiently incurred. Tractebel UK also concludes
that further cost increases are not supported by sufficient documentation and the developer should be further challenged by Ofgem to provide further technical
information to support the cost increases which were listed. The negotiated xxxx contract, which was based on a cost plus base instead of a lump sum did also not include the total original xxx scope for the cable installation (part of the scope went to xxxx ) and led to additional cost increases. Where a lump sum based contract ensures that the contractor is committing to an upfront fixed price and thus stands in for a number of risks, a cost plus based contract does not include this type of contractor’s commitment and the developer will face cost increases each time delays out of the developer’s control are arising
to third parties is forbidden without prior written approval written prior without forbidden is parties third to
8. GENERAL CONCLUSIONS
The analysis covers documentation provided to the consultant between 21 December
and 28 January 2013, updates provided on request during February and March, two transmission or duplication ny meeting held with Centrica and Ofgem in March and a telephone conversation with Natural England regarding the consent processes. During the review there was a constant communication and data-exchange between the Consultant, Ofgem and the Engineering S.A. A S.A. Engineering
developer. Based on the documentation that was available, following conclusions can be drawn.
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8.1. Connection point
The route selected to link the 3 wind farms Lincs, Race Bank and Docking Shoal to land and connect to the existing grid, was the shortest total route towards the substation at Walpole. Considering: • offshore cable installation as a critical step, • overall project risk assessment, • consideration of the Lincs Wind Farm project as a stand-alone project, •
time frame scheduled for being operational, • previous experience with already installed offshore wind farms, another cable route could possibly have been selected for the Lincs Wind Farm.
8.2. Project organisation
• Concerning risk identification and mitigation or contingency plans based on
the information received and the documents that were reviewed, it seems that initially these were not fully in place and only developed during the
project. Nevertheless in the documents relating to the end of the installation works it also seemed that only limited events were considered. • Concerning the decision making process for project changes, it is clear and it was confirmed by the developer that throughout the project changes notes have evaluated from simple documents to more extensive documents in the end. • For the management of interfaces according to the developer regularly
interface meetings were held between the participating contractors. The
documents that were made available (just as the documents received concerning above topics) related to later stages of the project. to third parties is forbidden without prior written approval written prior without forbidden is parties third to All together it seems that good project management is currently in place, but it is also clear that there was an evolution of the management during the project. An overall impression is that during the project a lot of decisions had to be and were made under time pressure and alternatives were often not examined thoroughly. ny duplication or transmission transmission or duplication ny 8.3. Installation methods and consents
• It appears that the consents had been very restrictive at the start of the works Engineering S.A. A S.A. Engineering and in addition there were shortcomings in the performed pre-investigation surveys. It is clear that with more comprehension of the site conditions some
events would have been better anticipated and mitigated. TractebelUK • Execution of the HDD, without a detailed soil survey to the depth of drilling constituted a project risk. When taking that risk alternative installation methods should have been prepared and discussed with the licensing Authorities up front. The initial selection was drilling from offshore to onshore plus the drilling equipment was located on two barges. In both cases these choices increase the installation costs Thisdocument the is property of
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• As a consequence to the unsuccessful HDD campaign in 2010, a new methodology and thus further engineering needed to be performed which led to a cost increase. • Next to the unsuccessful HDD campaign in 2010, xxxxxxxx entered administration in the first quarter of 2011 and a new contract for the installation of the export cables (and others) needed to be signed. In addition this contract had a cost plus basis instead of a lump sum basis. Although this occurred in the first quarter of 2011 it appears however that this impact was not included in the indicative transfer value which was set in July 2011. • The installation methodology was reviewed with chain trenching being the eventual method selected (requiring modifications to the consent). The chain
trenching was successful but for the pull-in process with the use of rollers another alternative (float-in, a typical landfall cable pull-in technique) was eventually to be used. • Due to the time lost during operations, only one nearshore cable could be installed in 2011. Hence additional installation works were needed in 2012. • Compared to previous works, the impact of the 2012 installation works itself
were minimal. However it is noted that lessons learnt from the 2011 installation may have been lost since different support vessels and
contractors were contracted by the developer in 2012.
• For the main cable installation there was a plough incident, leading to delays and additional jointing and post burial works. There are still some burial
works to be performed. This of course also led to cost increases. • Next to the cable installation there were also some issues with the supply of the cable which have caused delays of the project. Additional costs due to the cable faults were the subject for an agreement between the developer and the cable supplier.
8.4. Outstanding claims
Taken into account the outstanding amounts in the cost template that are indicated as approval written prior without forbidden is parties third to expected to be received, it seems that an overestimation of insurance payments is considered likely and a cost increase is to be expected. The exact amount of this increase is still to be determined, since there is not yet a definite settlement of the claims. xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx ny duplication or transmission transmission or duplication ny
8.5. Cost evaluation Engineering S.A. A S.A. Engineering
The original July 2011 budget for the work was £xxxx and during the period of builds the cost increased by £ xxx TractebelUK More documentation and analysis is needed to assess the full xxxx overrun but on a high level more than £xxx of the increase is considered as costs that are not economically and efficiently incurred . In addition the balance of the pending insurance claims should be further challenged, since the developer currently risks bearing over £ m. Thisdocument the is property of
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9. RECOMMENDATIONS
The review is based on • The information available in the data room, • A conversation with Natural England facilitated by the developer and Ofgem • Later information supplied by the developer and Ofgem.
Appendix N gives an overview of the documents that were consulted in the data
room. The available documentation is not complete. To further evaluate the cost increase since July 2011 general documents demonstrating the situation at certain incidents (for instance daily progress reports) as well as documents directly related to the cost templates (variation orders etc.) are missing.
To completely understand each cost increase in detail and to be able to evaluate whether or not specific costs can be justified, it is highly recommended to go into
more detail with the developer.
to third parties is forbidden without prior written approval written prior without forbidden is parties third to ny duplication or transmission transmission or duplication ny Engineering S.A. A S.A. Engineering
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10. REFERENCES
1. Installation / handling parameters 630mm² export cables, Nexans, 12/10/2010. 2. Lincs Landfall Options CREL NE meeting 051010 TO USE_LINCS.ppt, Centrica, 05/10/2010 3. Lincs Subsea Export Cables - Preliminary Route Engineering Report, Centrica, 28/09/2010 4. Food And Environmental Protection Act 1985: Part II (As amended) – Deposits in the sea in connection with marine constructions works, 1
January 2009 – Licence 33574/08/0 5. Coast Protection Act 1949: section 34 – Application by Centrica ( Lincs) Ltd installation of export power cable for Lincs Offshore wind farm, 21 October 2008, 33574/08/0/CON 6. Lincs HDD Works Meeting Minutes 18 Aug 10 - FINAL_LINCS 7. Storyboard – crossing inter-tidal area and saltmarshes, 17/03/2011,
Centrica 8. Natural England feedback on Lincs cable one installation works to
inform cable two installation methodologies
9. Storyboard for Planned Lincs Export Western Cable Nearshore Operations 2012, Centrica, 09/11/2011 10. Lincs offshore wind farm export cable nearshore pull-in, Longitude
Engineering, 05/04/2011 11. Lincs Export Cables Inter-Tidal Works: Emergency & Contingency Plans, Centrica, 28/11/2011 12. Controlling Changes, procedure, Centrica, 27/04/2012 13. Controlling Changes, flowchart, Centrica, 18/09/2012 14. Mitigation in the event of HDD breakout, Siemens, 04/04/12 (as built)
15. Geophysical Survey For Proposed Lincs Offshore Wind Farm, EMU
Ltd, 05/2005 16. Geophysical Investigations at the Proposed Race Bank & Docking
Shoal Wind Farm Sites with associated cable route corridors – Section approval written prior without forbidden is parties third to 4: Greater Wash area cable route survey, EMU Ltd, 05/2007 17. Interim Report 1: Lincs Offshore Wind Farm (Saltmarsh and Landfall Sections), Harrison Geotechnical Engineering, 08/2008 18. Acoustic Surveys For the Proposed Lincs Offshore Wind Farm Sites 19. Geotechnical report LINCS wind farm export cable route survey
laboratory and in situ data final report, Fugro, 03/2009 transmission or duplication ny 20. Geotechnical Design Report, Ramboll Wind, 09/2009 21. Export Route sediment transport study, HR Wallingford, 03/2010 22. HDD Works – Trafficability Assessment, Subocean, 10/2010 Engineering S.A. A S.A. Engineering 23. Lincs Export Cables – Technical note, Centrica (LN-E-EN-020-0117- 000000-008), 20/07/2011 24. Technical Report on the observed cable damage during load out of Lincs Export Cable 1 and 2, Nexans, 16/04/2012 TractebelUK 25. Inspection and test plan – export cables main and near shore section 1 and 2, Nexans, 15/10/2010 26. Inspection and test plan – export cables sea defence crossing section 1 and 2, Nexans, 03/02/2011 27. Inspection and test plan, fibre optical element – export cables, Nexans, 20/05/2010 Thisdocument the is property of
RA13035_Ofgem Lincs Cable Installation Cost Review_v8.0 45/48
28. Factory acceptance Test Procedure – Export Cable 1, Nexans, 19/02/2010 29. Factory acceptance Test Procedure – Export Cable 2, Nexans, 16/12/2010 30. Factory acceptance Test Procedure – Export Cables – Sea Defence Crossing Section 1&2, Nexans, 11/02/2011 31. Factory acceptance Test Report – Export Cable 1, Nexans, 24/11/2010 32. Factory acceptance Test Report – Export Cable 2, Nexans, 07/01/2011 33. Factory acceptance Test Report –Sea Defence Crossing Cable,
Nexans, 09/09/2011 34. Installation of the Lincs Offshore wind Farm Subsea Export Cables – A Brief History, Centrica, 17/09/2012 35. Lincs Subsea Export Cables – Preliminary Route Engineering Report, Centrica, 28/09/2010 36. Cable route alternatives Study for Lincs, Race Bank and Docking
Shoal Offshore Wind Farm developments, RPS Energy, 22/05/2007 37. Draft report to Ofgem on the offshore transmission second transition
tender round – Ex ante cost review of LincsWind Farm transmission assets
38. Contract for Offshore Installation of Export, Collector and Array Cables for Lincs Offshore Wind Farm, between Lincs Wind Farm
Limited and Subocean Limited, 22/04/2010 39. Management of Interfaces on Renewable Energy Projects – Strategy Document, Centrica, 01/05/2012 40. Managing Interfaces, Centrica, procedure, Centrica, 15/11/2012 41. Managing Interfaces, flowchart, Centrica, 15/11/2012 42. Centrica Round 2 Offshore Wind Farm (Lincs, Docking Shoal, Race Bank) – A review of export cable installation methodology,
techniques and tools, RES/AMEC, 16/08/2006 43. Desk top study Centrica R2 offshore wind farms construction
methodology review for submarine cable installation at proposed approval written prior without forbidden is parties third to shore end landing sites, Caldwell Marine International, 27/02/2003 44. Environmental Statement, Volume One: Offshore, RPS Group Plc, January 2007 45. Review of Connection Options for Lincs, Docking Shoal and Race Bank Wind Farms, Econnect Consulting 46. Electrical System Design Studies, Mott MacDonald, 3/02/2006 transmission or duplication ny 47. Transmission System Losses Assessment, Mott MacDonald, 21/04/2006 48. Wisbech Seabed Movement Study, HR Wallingford, 11/05/2011 Engineering S.A. A S.A. Engineering
49. Export route sediment transport study, HR Wallingford, January 2010 50. Wisbech channel variation, AMEC
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11. APPENDICES – ALL APPPENDICES REDACTED
to third parties is forbidden without prior written approval written prior without forbidden is parties third to ny duplication or transmission transmission or duplication ny Engineering S.A. A S.A. Engineering
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