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The rare wildlife which could be disturbed by digging two huge trenches for offshore wind farms

PUBLISHED: 09:19 16 December 2017 | UPDATED: 14:01 16 December 2017

Rare species could be affected by the building of two huge cable trenches across Norfolk to connect offshore wind farms to the National Grid.

Rare species could be affected by the building of two huge cable trenches across Norfolk to connect offshore wind farms to the National Grid.


Fears have been raised that hedgerows and trees will be lost and animals' habitat's damaged when hundreds of acres of land are dug up to bury cables for the world's biggest offshore wind farms.

Norflok Hawker dragonfly. Picture: Ian GillNorflok Hawker dragonfly. Picture: Ian Gill

Around 2,000 acres of Norfolk land will be cut through to build two trenches up to 60 kilometres long for cables carrying power from the wind farms to the National Grid.

The energy firms behind the wind farms, Vattenfall and Orsted, said they would do all they could to return the land to how it was after the cables have been buried.

Vattenfall said its aim was to improve the local environment.

But, in day three of our special report into the wind farm plans, campaigners point out that it takes years for habitats to recover.

Water Vole. Picture: Gavin Bickerton-JonesWater Vole. Picture: Gavin Bickerton-Jones

There will also be a permanent impact on the landscape from building three new electrical substations and possibly relay stations in the countryside.

One trench, for a wind farm called Hornsea 3 being built by Danish firm Orsted, will run for 55km from Weybourne on the north Norfolk coast to Swardeston, south of Norwich.

The second, for two Vattenfall wind farms, will cut 60km across the countryside from Happisburgh in the north-east to Necton in the west.

Consultants for Vattenfall said in a report on the environmental impact that land dug up and habitats destroyed would be “reinstated following construction as far as possible”.

Pink-footed geese. Picture: Simon BamberPink-footed geese. Picture: Simon Bamber

North Norfolk MP Norman Lamb urged the government to stop being so “laissez-faire” about where companies dig trenches and build infrastructure for offshore wind farms.

“I think we are doing more harm to the countryside than we need to,” he said.

And he questioned why a new trench needed to be dug across Norfolk every time a wind farm came ashore.

“I personally am committed to offshore wind farms,” he said. “They are vital to our country’s future. But there is very little willingness (in government) to look at the impact on the countryside and communities.”

Badger. Picture: Ben Birchall/PA WireBadger. Picture: Ben Birchall/PA Wire

Two new substations will need to be built on farmland at Necton and hedgerows will be lost there.

One substation already at Necton will also need to be expanded into the River Wissey headwaters.

According to Vattenfall’s environmental consultants, that would mean the disturbance of surface water creatures and flood risk. It said “mitigation” would be put in place.

When picking the route for the underground cables, nature conservation sites were avoided where possible, Vattenfall’s consultants said. But the River Wensum’s special area of conservation will need to be crossed.

Desmoulin's Whorl snail. Picture: Wikimedia/Gilles San MartinDesmoulin's Whorl snail. Picture: Wikimedia/Gilles San Martin

The cable corridor for Orsted, up to 80 metres wide, will also need to cross the rivers Wensum, Tud and Bure.

It also needs to go through the River Glaven headwaters which, the Campaign for Rural England (CRPE) said was the “best river left” with a healthy population of the protected species native white-clawed crayfish.

The environment report for Vattenfall also said the Happisburgh to Necton cable would cause “direct effects” upon sites designated for their nature conservation including Wendling Carr, Paston Way and Knapton Cutting and Marriott’s Way.

This includes loss of habitats such as heathland, woodland, hedgerows, grasslands and ponds.

A crested newt. Picture: Wikimedia/Rainer TheuerA crested newt. Picture: Wikimedia/Rainer Theuer

Animals including badgers, bats, water vole, otters, great crested newts, desmoulin’s whorl snail, Norfolk hawker (a rare dragonfly) and protected flora are all expected to be disturbed while the substations and cable corridors are built.

Mitigation would include moving the animals and replacing their habitats.

The environmental report written for Orsted, meanwhile, said the work could have a “moderate to major adverse” impact on species and habitats. But that would be reduced through rerouting the cables 
and looking at the timing of the works.

It also said impacts on the environment included losing animal habitats such as hedgerows and watercourses, as well as possible disturbance of “notable species”.

Construction on Vattenfall's Vanguard project could begin as early as 2020-2021. Picture: VattenfallConstruction on Vattenfall's Vanguard project could begin as early as 2020-2021. Picture: Vattenfall

Two types of cables could be used in the trenches. One called Alternating Current (AC) would need wider trenches and a relay station on the route.

The other called Direct Current (DC) would need a narrower trench and no relay stations.

The CPRE urged both the companies to choose the DC option.

The campaign group also said in its response to Vattenfall’s consultation that there were seven ancient woodlands within 500 metres of the cable route, as well as ponds crucial for wildlife.

Happisburgh beach, where the proposed windfarm cables could be placed.
Picture: ANTONY KELLYHappisburgh beach, where the proposed windfarm cables could be placed. Picture: ANTONY KELLY

Sensitive areas such as river valleys and woodland could be dug under rather than through with a method called horizontal direct drilling. CPRE called on the firms to give that “careful consideration”.

•Read more here from our wind farm series

•What about sealife?

Map of underground cable corridors for the Vattenfall (blue line) and Orsted (red line) offshore wind farms. Image: ArchantMap of underground cable corridors for the Vattenfall (blue line) and Orsted (red line) offshore wind farms. Image: Archant

Birds wintering in Norfolk and breeding here will also be disturbed through habitat loss, the environment impact report said, with pink footed geese wintering on the coast most affected.

Out at sea, the report for Vattenfall said the turbines would only have “minor impacts” on marine mammals.

But when the Vattenfall project was looked at alongside the other wind farms being built at the same time by Orsted, it said there was potential to disturb the protected harbour porpoise with the noise of pile driving – used to drive poles into the ground for foundations of the turbines.

The porpoise is protected under EU law.

Similarly, with sea birds it said there would only be “minor impacts”, but again with the other wind farms taking place at the same time there was “potential for greater impact to occur”.

The environment report produced for Orsted said the main risk to birds at sea posed by the wind turbines was “collision mortality”.

•100 scientists looking at impact

A spokesman for Vattenfall said the firm had worked with nearly 100 scientists, environmental specialists and engineers to assess many of the ecological issues that people had told them about.

“Pre-eminent in their field, these specialists can advise on how to tackle these issues and improve the environment,” they said. “Armed

with that information, we will then collaborate with the

local people and interest groups to minimise impact and, importantly, set about improving the local environment.”

Chris Starkie, from the New Anglia Local Enterprise Partnership, said the regulations governing construction were “pretty comprehensive” in terms of the environmental impact.

Orsted, meanwhile, said it was developing a “Code of Construction Practice” for their contractors to follow to minimise the impacts from the building work.

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