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Windfarms in the Greater Wash Area and the North Sea
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:
- Installation of cable 1 to KP8 (Kilometre Point-measured from the shore)
- Remediation of Sea Defence fissures
- Reinstatement of Sea Defence Breach
- Installation of two Transition Joint Bays (in the compound behind the sea wall- where cables are connected and monitored)
- Agreement to a 5-year monitoring plan with the EA
- Agreement of a 5-yeart saltmarsh monitoring plan
- Installation of monitoring equipment
The new application for consents involves:
- an updated Cable Burial Management Plan to be submitted to the Marine Management Organisation (MMO), whose role is to oversee all marine activities for all UK waters (seas and rivers)
- obtaining Flood Consent from the Environment Agency (EA)
- Planning permission from South Holland District Council (SHDC)
- a Footpath Diversion Order from Lincolnshire County Council (LCC).
The Consents consultations include some amendments to the breaching methodology in light of the experience during the summer of 2011. These are:
- discussions with the EA to include 'lessons learned' and 2012 high-level methodology
- trenching methodology that will minimise the risk of fissures being created
- to have contingency measures in place to deal with any cracking that may occur.
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
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
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!!
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 |
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 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 |
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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.
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.
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)
Photo-2: 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)
Photo-4: Reinstated marsh
Photo-5: 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)
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)
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)
Photo-9: Partially reinstated bank (a)
Photo-10: Partially reinstated bank (b)
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)
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.
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)
Pic-1: The cable on the barge
Pic-2:
The pillow floats
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.
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.
Pic-5:
Nessie III about to climb through the breach
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.
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).
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
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.
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 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
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.
The 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:
- to drill deeper under the peaty layer 25m. into clay;
- ploughing the salt marsh, but this requires an EIA (Environmental Impact Assessment).
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
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.
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.
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.
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.
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.
