Cross Keys Swing Bridge, Sutton Bridge, Lincolnshire

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Windfarms in the Greater Wash Area and the North Sea


Dec 22 2013

Centrica has sold its holding in the Race Bank Wind Farm

Dong Energy Power(UK), a Danish company, has bought the entire Race Bank Wind Farm Development management from Centrica for £50m. The Race Bank wind farm site is 17 miles off the North Norfolk Coast, off Blakeney Point.

All the marine consents are in place for the project to be built, subject to the new owners building a mechanism that will lay the cable from the tidal foreshore, across the marsh, through the sea wall for connection at the Walpole Substation. This means something that will do the work of a Nessie (see below), but hopefully without the damage Nessie caused to the marsh will be constructed. This is part of the agreed terms of the sale.

The reason for the sale is due to the Government’s change of policy regarding offshore wind farm subsidies and the final decision to build the wind farm depends on outcomes of these uncertainties. If it is built then it must be done before the end of 2017.


Oct 15 2013

Centrica Cable laying work for the East Lincs Wind Farm in the Wash Update - October 2013

The East Lincs Wind Farm became fully operational in September 2013. The cable route from the windfarm (off the East Lincs coast, near Skegness) comes ashore east of the Nene Estuary, through the marsh and sea defence wall, across farmland to the Walpole sub-station where it is connected to the National Grid.


Diagram showing approximate cable routes

During the cable laying process many problems were encountered and subsequently overcome and from these lessons have been learned.  The proposed Race Bank Wind farm has been subjected to several intensive geotechnical surveys (and others still on-going) to determine the best route for the cables. Three routes were looked at and the second of three proposed cable routes (Route 2) was chosen (see map) as the more suitable because it was considered that there would be less damage to the marsh surface from the cable-laying machinery required to carry out the work.  There would be fewer creeks to cross, which will require fewer flumes, which are pipes inserted into the creek to allow water to flow and prevent blockages, as well as providing a ‘bridge’ for vehicles crossing the creeks. This might also mean that fewer lengths of track-way (bog mats) would be necessary, covering a shorter distance across the marsh. Consequently there would be fewer vehicle movements to lay and recover flumes and track-way. Additionally, there would be less damage to creek banks, which means less creek reinstatement work afterwards.

It was cause for concern to the local population when the East Lincs Windfarm cable route had to go through the protective sea defence wall and consequently was breached in two places—one for each cable—to allow the cables to be connected to the Walpole Substation. Those concerns were exacerbated, after the work had finished, when a 20mm crack was detected at the base of the seaward side. However, reassurances have been given that the crack is being closely monitored by the civil engineers responsible for the work (Halcrow) and the Environment Agency.

Nevertheless, local concerns have been reawakened by the need to breach the sea defence wall again 500m to the east of the first breach in order to accommodate up to four cables from the proposed Race Bank Wind Farm. (See map for approximate position of the cable through the Wash and through the sea defence wall)

The concerns were recently addressed by Centrica representatives at the Sutton Bridge Parish Council Meeting on September 30th. Centrica said that at the last inspection (September) there was no sign of deterioration when their civil engineers (Halcrow) inspected the site in August. The next inspection will take place in June next year. If any changes are noted in the meantime then, together with the Environment Agency, measures will be taken to remediate this. There is an agreement with the company to monitor and undertake any necessary repairs to the structural integrity of the sea defence over a period of seven years.

In the meantime, Natural England is still monitoring the recovery of the marsh by undertaking regular ‘walkovers’.

The proposed start date for the Race Bank Wind Farm has been put back until mid 2015 until the Energy Bill passes through Parliament later this year. This has resulted in a delay seeking funding.


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July 28 2012

Centrica cable laying work for the East Lincs Wind Farm in the Wash Update - July 2012

Nessie III was successfully recovered from KP4 (3.8)(Kilometre point distance from shore) on Saturday, July 21st, after completing the trenching across the sandflats and mudflats of the intertidal area to KP8. Nessie III was demobilised and brought to Port Sutton Bridge on the Forth Guardsman. This vessel had been present throughout the trenching operations across the mudflats providing winch and tow support when needed.


Nessie III pictured at Port Sutton Bridge earlier before working on the marsh

All the remaining bog mats were recovered from the seaward side of the Big Tom Creek.

Although a large number of seals and their pups were seen on the sand banks, no seals were encountered during the consented working area. All those working in this area were advised what procedures to follow if seals were seen, including contact with the RSPCA at the East Winch Wildlife Centre

A cockle survey was carried out 21st/22nd July, taking samples on the high/ebb tides.
Magnet extensometers are to be installed shortly on the top of the sea bank to provide accurate readings of any changes in the sea defence wall during settlement.

The Field 1 site behind the sea defence wall is due to be cleared within three weeks and returned to farmland.


Nessie III being overhauled in field 1 behind the sea defence wall in May 2012


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June 14 2012

Centrica Cable laying work for the East Lincs Wind Farm in the Wash Update - June 2012

Work on testing the infill on the breach continues to be regularly monitored. Turfing is expected to commence in mid-June and the installation of survey markers will be installed after turfing. The clay ramps will be removed shortly, leaving just a narrow strip to enable the removal of the steel steps and the eventual re-opening of the footpath.


Nessie V in postion on the mudflats

When the work on trenching and cable laying by Nessie III across the mudflats and the Big Tom Creek has been completed, Nessie will continue towards the point known as KP8 (kilometre point [8km] from the shore), its destination point. The methodology used to steady Nessie III by attaching steel tension (Dyneema) ropes from the front of Nessie III to the Forth Guardsman, proved successful until a slight hitch occurred when the Dyneema rope was damaged, resulting in a delay in trenching operations.


Samples of the piling used to reinforce the sea defence wall

Work was also temporarily stopped when one of the flume pipes inshore of Big Tom was dislodged, but this was removed and Nessie III was able to continue trenching at low tide.

The monitoring of the marsh and the creeks continues on a daily basis, and where a large area of standing water appeared recently, remedial action was taken by hand, to reconnect the area to a minor creek.


One of the guard vessels heading down the Nene towards the estuary to take up a position to warn shipping of the work being carried out.

As in all the work carried out during this year’s operations, all the Agencies involved have collaborated well, and hitches have been resolved quickly and efficiently, resulting in a smoother operation. Lessons from last year have been learned.


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May 22 2012

Centrica Cable laying work for the East Lincs Wind Farm in the Wash Update - Mid-May 2012

Following preparations that included:

the cable was actually floated in on the morning tide of May 7th to a point 25m from Nessie V which had been parked on the mudflats at the edge of the saltmarsh.

The process of laying of the timber track way (bogmats*) had been regularly monitored to make sure that it was stable and remained in position.  The rope that tied the mats together ensured that very little movement occurred. This proved to be important later (May 15th) when Nessie V reached the area of the ‘borrow pit’ close to the sea defence where the softness of the marsh and the weight of Nessie V moved the bogmats upwards as it moved forward. However, the movement was slight and bogmats settled back into position as Nessie V moved forward.


Nessie V approaching the bogmats

During 8th/9th May, the pillow floats that brought the cable across the mudflats were removed to allow the cable to sink to the sea bed. Flume pipes* were installed across the creek in-shore of Big Tom, a major creek and SAC designation feature and therefore protected

Nessie V began to track back across the saltmarsh within the consented corridor at 9.00am on Tuesday 15th May.  The conditions were very favourable: sunshine, a brisk wind that dried the marsh and allowed an almost perfect journey. A slight gouging creating a largish berm* on the left-hand trackside and some movement of the bogmats shortly afterwards were the only observable incidents.


Nessie V tilting to the left to create a berm


Work continues on lowering the level of the breach

Meanwhile the breach that was being lowered to the designated level was finished and Nessie V’s passage up the ramp on the seaward side, through the breach and down the landward side into Field One went effortlessly.




Nessie V going through the breach and down the landward slope

At 11.00am Nessie V arrived in Field 1 and halted close to Nessie III , which was then prepared to received the cable from Nessie V and begin its journey trenching and laying the cable. However, before this began, a detailed inspection of the cable took place.


Nessie V, and Nessie III ready to receive cable

Nessie III began to trench and lay the cable during the early afternoon of May 16th.  Where minor cracking in the trench was noted, it was ‘infilled’, using small tracking machines. On Thursday, May 17th, Nessie III tracked successfully across the salt marsh and will remain on the marsh before being dismantled after 21st May 2012.


Nessie III at the end of the journey, parked near the mudflats (18.5.12) (D. Smith)

Throughout the operations, there has been close monitoring of the condition of the salt marsh by the ecological team from RSK, a consultancy firm, working on behalf of Marine Management Organisation, Natural England & Centrica who have submitted daily reports to the relevant authorities.  Where problems have been noted, these have been dealt with quickly. 

For example when some flumed creeks filled with sediment they were cleared immediately by the contractors using hand-held spades.

When the bogmats were lifted, it was found that the vegetation had yellowed but that the rootmat was intact.  This had been protected by the geotex material membrane that had been laid beneath the bog mats. It prevented the vegetation being scraped.

Care was taken to ensure that wildlife and birds were protected.  During the operations a nesting pair of redshank were observed and while the birds themselves were seemingly unaffected by the work and noise on the saltmarsh, care was taken to ensure that the nest was undisturbed.

Red Shank
Redshank (©Ben Smith)

Work continues around the offshore substation in the Wash; on the inter-array cable, as well as the laying of the cable in the near shore area, which includes ‘fluming’ the Big Tom channel to enable this to occur without causing any damage.

*Glossary:
Bogmats—heavy duty thick wooden planks laid side by side to form a trackway for heavy vehicles moving across an unstable surface.

Flume pipes: heavy duty pipes made from plastic or metal of various sizes to channel water through unstable ground conditions. In this case, to protect the creeks from collapsing as the Nessies and other machinery passed over them.

Berm: a ridge or edge of soil that is pushed up and along a dug channel and forms a raised surface (edge). These can affect the flow of water in a marsh area, causing changes to occur.

Rootmat: the fibrous ‘matting’ created by growing plants


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May 3 2012

Centrica Cable laying work for the East Lincs Wind Farm in the Wash Update - May 2012

Work on bringing ashore the western cable from the East Lincs Windfarm is underway.  Despite the heavy rain during April and in particular, during last few days, Nessie V was able to go over the bank onto the sea marsh on a new course towards the mudflats where it is now parked. It was planned that the cable machine should go over on May 1st, but the marsh was too wet.  However, the wind and the sunshine today, (May 2nd) made the conditions suitable, allowing more time for the ground to dry out. Nessie V will remain on the mudflats until the cable can be wound onto the huge cable and tracked back across the marsh to be transferred to Nessie III.


New breach begins: the topsoil has been removed and the ramp installed to allow Nessie V to go over the sea wall


Bogmats have been laid over geofabric and are secured to minimise movement

Nessie III is the machine that digs a trench and lays the cable behind as it moves forward.

When the cable landing barge is in position but before the cable can be transferred certain anchor trials will be carried out before the barge is moved into position within the consented cable corridor. When in position, the cable will floated to the shore to be fed onto Nessie V

The whole process is being carefully monitored and controlled.


Nessie parked on the mudflats

As a result of the problems and difficulties encountered last year, lessons have been learned and so far the exercise has worked according to plan.  In addition, to make access easier for pedestrian visitors, a steel staircase has been erected close to the top of the bank where the breach will be made to enable people to view what is going on.  It is part of the diverted footpath that is the Sir Peter Scott footpath to West Lynn.

The diverted footpath on the landward side of the sea defence wall has been covered in part with straw to make access easier and safer for pedestrians.


Steps and diverted footpath

The steps looking from the landward side of the sea wall

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Feb 17 2012

Centrica Cable laying work for the East Lincs Wind Farm in the Wash Update - February 2012

In December 2011, the Lincs Wind Farm Ltd (Centrica) submitted an application to the Planning Department at South Holland District Council for work to be carried out during April to August, to bring ashore the second cable across the sea marsh, under the sea defence wall to the sub-station at the Walpole sub-station. Consultations have been sought from statutory bodies and members of the public wishing to make observations.

During the winter months work has continued in the Wash along the two main export cable routes and at the wind farm site itself. This involved repair to damaged cables, work associated with foundation installations (48 of the 75 have now been installed), carrying out trials and on-going work around the offshore substation.

Sutton Bridge Parish Council held an Extraordinary Meeting on Tuesday 14th February 2012 in order to listen to a presentation from the Lincs Wind Farm Ltd (Centrica) by Simon Gamage, (Consents & Environment Manager (Onshore), and to discuss the Parish Council’s response to the latest planning application for the second breach to the primary sea defence wall, north and east of the East Lighthouse.

Councillors and members of the public were able to ask questions and discuss with Simon Gamage and his engineer, Brendan Sheering, their concerns.  Two representatives from the Environment Agency (EA), Emma Kirk and Alistair Windler, were also present and made their concerns known,  as well as explaining their role in the consents process. Their function, as public ‘guardians’ for sea defence systems, involves stringent scrutiny of planning applications and the application of strict conditions that must be adhered to in order to give consents.

The supporting documents from the LWF Ltd planning application are available on the SHDC website for public viewing (Planning Application: H18-1024-11) and should be looked at.  The comprehensive details explain the methodology that LWF Ltd plan to adopt, which incorporates many significant modifications to the work carried out by them in 2011, and is based on the experience and problems encountered last year when working on the sea-defence wall, the sea marsh and the intertidal mudflats.

Simply, they are:

The Chairman of the King’s Lynn Joint Advisory Group to the Wash raised several important issues concerning the methodology to be used and the importance of LWF Ltd using local knowledge, which enabled councillors and members of the public to ask their own questions.

One councillor asked an important question concerning the effect of making the reinstatement ‘better than’ the existing bank, siting his experiences in other places where a severe sea surge had demolished a ‘strong’ defence close to a less strong one, which resulted in serious flooding.

EA stressed the importance they place on sea defences, especially along the East Lincolnshire and East Anglian coastal areas and explained how regular monitoring takes place. Consequently, their consents involve very strict conditions being adhered to.

A member of the public recalled ‘how frightening’ the floods of January 1978 were when the sea surge resulted in extensive flooding in Sutton Bridge, which was cut off from Long Sutton, Tydd Gote and the swing bridge was not accessible because the water level had reached the base of the bridge itself.

The EA representative said that as a result of this, further strengthening (insertion of metal sheet piling) had been done and since then, no flooding had occurred in Sutton Bridge and that the bank had withstood the ravages of wind and weather.

Another member of the public asked if the agreed route corridor across the marsh would be adhered to, to avoid a repetition of ‘the mess’ left behind after the 2011 works had finished.  The marsh vegetation provides a valuable function in slowing down the passage of water.  Where the machines had travelled across the marsh, they had left bare mud and ridges (berms) which, if the vegetation doesn’t recover sufficiently enough, or if the mud is dispersed by tides over vegetation and restricts re-growth, could cause new channels to be opened up.

Simon Gamage said that they were still in negotiation with NE about the direction and corridor width of the course across the marsh.  This was part of a separate agreement to do with the flood risk assessment and which, while, parallel with Planning consents, was a separate issue and required  separate consents.

The Chairman of the PC said that he felt reassured by what he had heard, adding that however, he had no experience of past flooding to judge this by, as he was relatively new to the village.

He and another councillor then asked what benefit would ‘accrue’ to Sutton Bridge residents as a result of this worrying and disruptive work being carried out in their parish. Simon Gamage said that he was in on-going discussion with the Parish Clerk about this.

The Meeting ended with a suggestion that members of the public and representatives from the LWF Ltd and the Environment Agency to leave to allow the councillors to discuss among themselves their response to the Planning Application, which will be posted on the SHDC Planning Dept webpage.


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Dec 1 2011

Centrica Cable laying work for the East Lincs Wind Farm in the Wash Update - November 2011

At the Sutton Bridge Parish Council Meeting (29.11.2011), Simon Gamage and Glen Evertson (Centrica) gave an update on the work being carried out in the Wash, in the intertidal mudflats and on the marsh in respect of the East Lincs Wind Farm.

They confirmed that their proposed plan to lay the two cables this summer under the intertidal mudflats and the saltmarsh near the East Lighthouse, at Sutton Bridge was interrupted because of serious problems that occurred on the marsh, when the two cable-laying machines Nessie III and Nessie V got stuck. This means that work will continue next year (2012) and that new consents for the cable-laying have to be applied for. Negotiations for this are currently underway with the relevant authorities.

A summary of the work completed:

The new application for consents involves:

The Consents consultations include some amendments to the breaching methodology in light of the experience during the summer of 2011. These are:

In addition, there will be improved access to the top of the sea defence wall for pedestrians, which involves the installation of a temporary staircase on the landward side of the sea wall. This will be a big improvement as the only way up and down during the summer was hazardous to say the least.

Difficulty in descending from the sea bank
Difficulty in descending from the sea bank

Descending the hard way!
Descending the hard way!

The diversion this year involved pedestrians walking approximately a half mile along a rough ploughed field edge and then up a slope to the top of the sea bank.

The footpath diversion from the east
The footpath diversion from the east

Centrica came prepared to show plans of the reinstatement of the sea-defence walls but were unable to be viewed because of time limitations. We cannot show any of the diagrams until these have been seen by the relevant authorities.

Among the questions asked by Councillors and members of the public present were:

Q: Why did Centrica not foresee the problems with the underground creeks?
A: Centrica was not allowed by the authorities to carry out extensive bore-drilling on the sea marsh.

Q: The figure given for MGW capacity from windfarms: is this based on average use of turbine, or maximum?
A: average

Q: What is the state of play regarding the damaged cables in the Wash itself?
A: the damage to the western cable (factory damage) has been repaired by cutting out the damaged section and rejoining the two ends The eastern cable was damaged when too much slack was given during the cable laying process and the excess cable snagged and was damaged. This repair work is ongoing. Bad weather conditions in the Wash make this a tricky operation and slow the process down. Centrica expect the work to be completed by March 2012. In the meantime, the guard vessel Huntress of Grimsby is still on site to guard the unburied cable ends near KP8

Q: When will the wind farm be up and running and producing energy?
A: Turbine erection will commence in February and should be finished by the end of 2012

Q: When will Sutton Bridge start benefitting from reduced energy costs?
A: Great gales of laughter!!


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Oct 27 2011

Centrica Cable laying work for the East Lincs Wind Farm in the Wash Update - October 2011

It is now just over a month since the work on the Marsh was finished for this season. Centrica will be returning next year to attempt the laying of the second cable across the marsh and inter-tidal mud flats from the East Lincs Offshore Wind Farm.

Work is still ongoing out in The Wash itself where the first 36 foundations and transition pieces have been installed. More installations are currently being carried out and Mariners are constantly updated on the work progress and advised to keep a safe working distance from these operations.

There were initial problems with laying the export cable under the sea bed between KPO and KP08 (these are reference points marking the kilometre distance from the shore). A guard vessel remains on site to guard the unburied cable ends near KP08.

Work is still being done on the site behind the sea defence wall behind the East Lighthouse at Sutton Bridge.


Photo 1 — the site from the reinstated sea defence wall

Photo 2 — the Reinstated sea defence wall with newly laid turf

Photo 3 — the coir fibre matting laid on the marsh side of the sea wall to protect against erosion.

Photo 4 — close up of the coir fibre matting.

Photo 5 — the marsh showing damage and surface water

Photo 6 — close up of the Marsh

The temporary footbridge across the drainage dyke behind the Sea defence wall has been removed and the farmer's field has now been restored and ploughed. The public footpath that runs along the top of the sea defence wall is now open and the temporary diversion has been removed.


Photo 7 — the sea bank footpath is now re-opened.

It is hoped that next year, when the footpath has to be diverted again to allow for the second under-marsh cable to be brought ashore, that a better provision for pedestrians and onlookers will be made. It is not reasonable to expect people to walk at least a kilometre along the rough field edge to ascend the sea wall by the slope. The barrier positioned at the top of this slope was clearly positioned to prevent pedestrians from gaining access to view the work being undertaken. As can be seen in photo 8, this does not taken into account the public's natural curiosity in wishing to watch what is going on.


Photo 8: Looking west along the sea wall, showing the distance to be walked in order to regain access to the sea wall footpath.

Centrica has now strengthened the secondary sea-fence wall after the reinstatement last year following the completion of the landward cable laying had slipped. This has been reinforced with similar piling as used in the main sea defence wall.


Photo 9 — the piling in place in the secondary sea wall


Photo 10 — the reinstated secondary sea wall

It is understood that Natural England will be in discussion with Centrica shortly to talk about their proposals for next year's operations.


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Sept 13 2011

Centrica Cable laying work for the East Lincs Wind Farm in the Wash Update - September 2011

 

All operations on the sea defence shall be completed by 31 August 2011 and the sea defence reinstated by that date unless agreed otherwise in writing by the Local Planning Authority. Reason: To prevent the potential disturbance to roosting passage and over wintering birds within a Special Protection Area. This Condition is imposed in accordance with advice within Planning Policy Statement 9 'Biodiversity and Geological Conservation'..

The deadline for Centrica work on the sea bank and the sea marsh was extended to allow Nessie V to come over the sea wall on September 1st on the evening low tide (8.40pm) Natural England consented to allow Nessie V to come back across the marsh on its original tracks and over the sea wall via the western ramp. Nessie V is still on the site and will be dismantled and removed by lorry.

Working in the dark
Photo-1: Working in the dark - Nessie V coming over the sea wall.

After Nessie V had returned, the work on recovering the flumes and matting from the marsh was carried out. (Photos 2, 3)

Removing the flumes
Photo-2: Removing the flumes

Removing the flumes
Photo-3: Removing the flumes

The next step was to reinstate the marsh according to an agreed plan with Natural England (Photos 4, 5, 6)

Reinstated marsh
Photo-4: Reinstated marsh

Reinstated marsh
Photo-5: Reinstated marsh

Reinstated marsh
Photo-6: Reinstated marsh showing Nessie III on the intertidal flats on the incoming tide

Nessie III remains out on the intertidal mudflats to complete the cable laying there. (12.9.11) When this work is finished, Nessie III will be brought back by barge, taken to Sutton Bridge, taken apart and sent back to Germany.

A number of problems occurred while trying to lay the cable under the marsh, which was the reason for the delay in completing on time. One was that Nessie III had difficulty progressing across the marsh with its many creeks and soft terrain and was stuck for a few days while waiting for a winch to come from Holland to be attached to Gerd Knoll and to keep Nessie III upright. The winch provided stability and was able to pull Nessie III if it encountered quicksand.

The cable under the marsh was finally buried and Nessie V was able to return to the compound behind the sea bank, beyond the East Lighthouse. This occurred one day later than the deadline of August 31st.  It has now been connected to the land cable, which was laid last year. (Photo 7)

The buried cable after joining
Photo-7: The buried cable after joining

During this process, the cable, which contained fibre optics, was exposed near an inspection hut to enable 24-hour monitoring of the condition of the cable throughout its entire length. When the cable was finally in place, a pit was dug and a brick-lined chamber was built at the point where the marsh cable was joined to the land cable. (Photo 8)

The brick chamber where the cables are joined
Photo-8: The brick chamber where the cables are joined

The infilling of the breach began on Sunday 4th September and has been reinstated apart from the turf layer on top. It was reinforced with plastic pile sheeting and a special bonding material. When this has been completed, work will begin on reinforcing the inner sea bank which was breached last year, and not very well reinstated after the land cable was laid. (Photos 9, 10, 11)

Partially reinstated bank
Photo-9: Partially reinstated bank (a)

Partially reinstated bank
Photo-10: Partially reinstated bank (b)

Partially reinstated bank
Photo-11: Nearly there...

In the meantime, the public footpath had to be moved nearer to the site because the farmer needed to plough the field. (Photo 12)

The footpath has been moved
Photo-12: The footpath has been moved.

Problems also occurred with the cable route under the Wash and the effects of this on the local fishing industry and the three ports, and which concerned the safety of navigation in this area and the impact on cockle and shrimp beds. It was not until these issues had been resolved that work was allowed to go ahead.

Work is still ongoing in the Wash itself and in a few weeks’ time work will begin again at the main site to install the second export cable. The work to connect this to the land cable via the marsh will not begin again until next Spring.  In the meantime a lot of re-thinking, in the light of this year’s experience, will have to be done.


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Aug 18 2011

Centrica Cable laying work for the East Lincs Wind Farm in the Wash Update - August 2011

After a failed attempt to bring the cable ashore from the barge (Pic-1) using rollers at low tide, to connect with Nessie V, moored on the edge of the salt marsh and the intertidal mudflats, Centrica eventually used pillow floats on a high tide. (Pic-2) This was a slower process because of the need to use high tides to float the floats and the cable, and because of the weight of the cable and the maximum pulling capacity of Nessie V. However, the cable was finally reeled onto Nessie V on Sunday August 14th . Nessie V then began to re-cross the marsh laying the cable in its planned route. (Pic-3)

The cable on the barge
Pic-1: The cable on the barge

The pillow floats
Pic-2: The pillow floats

Nessie V on the marsh
Pic-3: Nessie V on the marsh

Before this could begin, work started on taking the top 2.5 metres from the sea defence wall to allow Nessie to pass through. (Pic-4). Soil samples were taken at equal depths as the soil was removed, to ensure that the same quality of soil is replaced. The spoil heap was then covered with protective plastic sheeting.

The breach and cable
Pic-4: The breach and cable

The next stage was to connect the cable on the ground to Nessie III, which is the cable-laying trencher machine. (Pic-5) This digs a deep trench 6 metres below the surface, laying the cable in its wake. It was backfilled up to the breach with the soil that was extracted using two diggers. Nessie III passed through the breach, continuing to dig the trench. This trench was not backfilled as Natural England wished the process to happen naturally using the tides and time. Unfortunately, at some time during its passage across the marsh Nessie III got stuck in one of the many creeks that drain the marsh. (Pic-6) The problem was sorted by bringing Nessie V onto the marsh to assist by lifting the cable to ease the weight, which allowed Nessie III to be righted.

Nessie III about to climb through the breach
Pic-5: Nessie III about to climb through the breach

Nessie III stuck on the marsh
Pic-6: Nessie III stuck on the marsh

To complete its work, Nessie III must continue to the edge of the marsh, where it will travel across the inter-tidal mudflats towards the barge that has the next load of cable on board. The barge will be floated back out to deep water, with Nessie III following and repeating the process, digging trench 6 metres deep and laying the cable in the seabed as it goes.

In the Wash itself, work has already begun on laying the cable from the wind farm substation and the two cables will link up and be joined and buried beneath the seabed. The land connection, which was installed last year, is in the process of being made ready to be linked up once the cables have been laid in the seabed and under the marsh and intertidal mudflats.


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Jul 24 2011

Centrica Cable laying work for the East Lincs Wind Farm in the Wash Update - July 2011

At the Parish Council Meeting of June 29th 2011, Simon Gamage, the Consents and Environmental Manager for Lincs Wind Farm Ltd (Centrica) outlined the proposed works to be carried out on the marsh and through the sea defence wall in order to connect with the seabed cables (not yet laid) and the land cables, which were laid last year (2010).

planned cable route
The planned Lincs landfall cable route. KP No.s indicate kilometres from the shore.
Above image was from Centrica's presentation to Sutton Bridge Parish Council

He explained that last year's attempt to use the horizontal drilling method on the sea marsh had failed and during the winter months, Centrica had looked at various methods to bring the cable ashore. They had finally decided to use two cable carrier/trencher machines, supplied by Christoffers (a German firm) that have been used successfully in Germany on a similar terrain. They are known as Nessie III and Nessie V.

Nessie III and Nessie V
Nessie III and Nessie V

Consents were granted for this work on June 20th 2011 and are subject to stringent relevant conditions. The work must finish by August 31st 2011. If it is not then the work will be demobilised and will continue next year. The consent and conditions can be seen on the SHDC website planning pages.


Nessie III and Nessie V parked in the compound prior to work being carried out.

It is a complex exercise to bring the cables ashore. One of the machines, Nessie V, has to be taken out to the cable supply ship, anchored offshore, where the cable will be transferred to the huge cable reel on board, brought back to the shore and the cable will be fed through rollers to the trencher machine: Nessie III. Then the trench will be dug and the cable laid and the trench back-filled as Nessie III advances.

Nessie V after the failed attempt to connect the cable to its wheel.
Nessie V after the failed attempt to connect the cable to its wheel.

In order to achieve this, both machines have to cross the sea defence wall, which involves taking Nessie V up a ramp and onto the marsh. Once Nessie V has returned with the cable on board, the ramp will be excavated to 2.5 m (mid point) so that Nessie III can pass over the sea bank and at the same time dig the trench, lay the cable and in-fill the trench. The front face of the sea defence bank will be protected with timber mats. Once Nessie III has passed they will begin rebuilding the sea wall. This is expected to take between 3-4 days. Recycled plastic piles will be inserted to prevent seepage and the sea bank will be reinstated higher to allow for settlement. The cable itself will be buried 6m in the ground under the sea defence bank and the dyke that runs parallel to the wall on the landward side. There will be 2-4 weeks between actual breaches.


Working on the ramps to enable the machines to go over the sea defence wall.

This work began on Monday July 18th. Unfortunately, the work ran into difficulties and has had to be postponed until August 1st. One of the difficulties was that Nessie V damaged the salt marsh as it went over the sea bank, gouging out deep channels with its caterpillar treads.

Nessie V
Nessie V making its way slowly across the marsh, after levelling out.

In order to make the place safe for walkers who normally use the wall, the existing path was diverted. It will be reinstated as soon as protection of the front face of the sea defence wall has been reinstated. The damaged salt marsh also has to be reinstated.


The bridge over the dyke, part of the diverted footpath


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Dec 4 2010

Offshore Wind Farms in The Wash
- Dec 2010 Update -

It is stating the obvious to say that offshore wind farms are more efficient than onshore wind farms simply because there is more space and more wind. Therefore it is not surprising that the size of the offshore wind farms and the turbines themselves are larger than their onshore counterparts. This suggests that larger turbines, and bigger wind farms, must produce more energy.

However, even taking into account wind turbines’ low annual total capacity of 27 per cent — because the wind does not blow all the time — very little of this electricity can be stored: it has to be generated precisely when it is needed. Lincolnshire seems to be a favoured place for developers to erect wind turbines — both onshore and offshore — partly because they consider the countryside to be ‘utilitarian’ and also there is relatively little opposition to developments. Unfortunately there is also relatively little wind in Lincolnshire. The developers argue that if wind farms are spread evenly around the country, this evens things out.

The Greater Wash area and the North Sea are attractive areas for developers. (see www.thecrownestate.co.uk for a map showing the Offshore Wind Round 3 Zones proposed developments.

In the Greater Wash area itself, Round 1 has seen the construction of two wind farms — the Lynn & Inner Dowsing wind farms off Skegness on the Lincolnshire coast.

Round 2&3 offshore wind farm (OWF) developments are getting larger. Some proposals in the pipeline, like the Triton Knoll development in the North Sea, are very large. Most of Round 3 wind farms are planned outside the 12mile territorial limit, and a few straddle this. Rotor diameters range between 44-110m and the number of turbines are from between 30-333. Thirty turbines occupy a total area of 10² km.

The work currently being undertaken in the Greater Wash on the East Lincs Offshore Wind Farm by Centrica is part of the Round 2 phase of wind farms. This is one of three further renewable projects: Race Bank and Docking Shoal.

Wind-turbine towerThe 35km² East Lincs wind farm will consist of 75 turbines in a depth of between 10-15m water in the North Sea. The project, costing £725m, will generate 250MW of electricity annually. The rotor blades will be 58.5m long and the rotor will be 120m diameter. The maximum height to the tip of the blade will be 170m. In layman’s terms this is about the height of 23 double-decker buses.

The turbines will be spaced at a distance of 500m. The hub height will be 100m. The narcelle and the hub of the turbines will be installed on top of the turbine tower. This will be supported by a foundation attached to the seabed.

The offshore work to the east of the East Lighthouse at Sutton Bridge, which began in March 2010, stopped in the middle of September. The developers were given an extension to the consents because of the difficulties encountered in drilling under the salt marsh. Migrating birds use the Wash extensively during the winter period and would have been adversely affected by work, so the current work had to finish by this date. As a result of this set-back, Centrica are now exploring two options:

During April 2010 and August 2010 a substation will be erected to connect the wind farm with the national grid network. This will involve piling using an improved, less noisy method that also creates less vibration. More details are awaited.

Although the East Coast of England is a strategic area, there are limited high voltage power lines between Norwich and Walpole sub-station. Wind farms need to ‘hook’ into high level voltage, which is why Centrica is laying cables in the Wash. Two high-voltage cables are being installed from the landfall near the East Lighthouse to the new onshore substation site at Walpole (now completed). Work is expected to continue on cable-laying until June 2011.

Locally, the noise nuisance caused to residents of Sutton Bridge during the summer by the hovercraft transporting workers to the offshore, proved not to have disturbed the seal population, which were ‘pupping’ during this period. However, it did flush some birds. The two platforms that were anchored off-shore, to the east of the East Lighthouse landfall, did not greatly cause adverse disturbance.

Natural England, which monitors the effect of developments on the natural environment, has a dual role. On the one hand it supports and facilitates the generation of clean energy development in appropriate locations while at the same time it has a statutory remit to conserve and protect landscape and biodiversity. So it is important to avoid interest features in The Wash, such as the saballaria reef and ross worm reef. There are also important concerns about the Sandwich Tern, which is so intent on feeding that it does not seem able to avoid collisions with structures. Another important concern is the visual impact of wind farms on the North Norfolk Coast in particular.

As to the future, Round 3 off shore wind farms (OWF’s) would need to take up a considerable chunk of the North Sea off the East Coast of the UK (about 20nm offshore in 20m depth of water, or less. Although the proposed OWF’s in the 3 strategic areas will supply 7GW of power, this is less than the 2020 target of 10GW.

See www.power-technology.com/projects/centricalincs for further information.
For some interesting observations on the efficiency of windfarms, see an article in the Daily Telegraph by Andrew Gilligan, published on June 13 2010: www.telegraph.co.uk


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Aug 1 2010

Offshore Wind Farms in The Wash

Centrica Energy owns the two wind farms that can be seen from Hunstanton and other places along the North Norfolk coast. These are called the Lynn and Inner Dowsing wind farms. Together with partners DONG Energy and Siemens Project Ventures (SPV), a third wind farm, the Lincs Offshore Wind Farm is currently being developed. Two others are being planned for in the future: Race Bank and Docking Shoal, off Wells-next-Sea.

Round one (Lynn and Inner Dowsing) cables come ashore off Skegness. The cables for the Lincs Offshore Wind Farm are coming ashore just east of the East Lighthouse near Sutton Bridge.

Centrica Energy offshore wind farm cable route
The above map is hyperlinked to Centrica Energy's Race Bank Offshore Wind Farm
'Environmental Statement Non-Technical Summary' document dated January 2009

Work began in drilling under the salt marsh in early summer 2010. The method used is known as ‘horizontal directional drilling’. This method was chosen because of the sensitive nature of the salt marsh habitat: to avoid habitat loss and minimise physical disturbance to the salt marsh.

Barge loaded with equipment on the River Nene

In the late Spring of 2010, two work platforms, or rigs, were loaded with equipment at Port Sutton Bridge, before being towed out to a position just beyond the mouth of the River Nene. It is from these platforms that drilling operations have been taking place. In addition a land-base site has been constructed in the field on the land side of the sea bank, near the East Lighthouse.

Centrica  offshore cable rig

Centrica land-base site

When work began in the middle of May a hovercraft was used to transport workers to and from the rig in three shifts, morning and evening. This will continue until the end of August, when the drilling operations should be complete.

Hovercraft on the River Nene

In the meantime, work is in progress of laying two steel pipes to carry the cables across mainly agricultural land to the Walpole sub-station. Horizontal directional drilling will also be used to drill beneath the A17 road to avoid major traffic disruption. Extensive work is currently being carried out at the Walpole sub-station to increase its capacity.

Pipe laying across agricultural land


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