Committee Report NSC

6.2

 
North Somerset Council

 

REPORT TO THE Planning and Regulatory committee

 

Date of Meeting: 25 JULY 2012

 

SUBJECT OF REPORT: National Grid - Weston Power Distribution link between Churchill and Weston

 

Town or parish: Puxton, Churchill, Banwell, Winscome and Sandford, Congresbury

 

Officer presenting: Graham Quick Local, Planning Team Leader

 

Key Decision: no

 

RECOMMENDATIONS

 

That National Grid be informed that:

 

(i) the proposed sub-station site west of Nye Road Sandford is the preferred site and any landscape and biodiversity impacts be mitigated by designing the whole sub-station as a Gas Insulated station with extensive landscaping and bat roosting features and swallow ledges;

 

(ii) the National Grid’s preferred option of Route B for overhead works with wooden poles is acceptable. Undergrounding would have significant extra landscape benefits but there would be severe considerations for archaeological and biodiversity interests which would have to be addressed if this option was chosen;  

 

(iii) it is critical that the character of the Mendip Hills Area of Outstanding Natural Beauty, the Tickenham Ridge and the open views across the levels from the settlements of Nailsea, Tickenham and Yatton are protected. In addition, any adverse impacts on archaeological/ biodiversity interests need to be taken into account when considering any undergrounding works.

 

1.               Summary of Report

 

The report sets out the latest National Grid consultation on the preferred route corridor for the Hinckley C Connection and why there is a need for a new sub-station and connections in the Churchill/Sandford area across the levels between the M5 and Sandford

 

2.               Policy

 

The 2008 Planning Act introduced a new planning system for applications to build nationally significant infrastructure facilities in England and Wales. The new system covers applications for major energy generation, railways, ports, major roads, airports and water and waste infrastructure. Under the new system, national policy on infrastructure will be set out in a series of new National Policy Statements (NPS).  The Secretary of State will examine and decide applications for new infrastructure development, using the criteria on national need, benefits and impacts set out in the NPS, and consideration of evidence put forward on potential local effects.

 

National Policy

 

The most relevant NPS is EN-5 on Electricity Networks where the use of the “Holford Rules” to guide the routing of overhead lines is recommended.  These state that routing should:

 

  • avoid altogether, if possible, the major areas of highest amenity value,

by so planning the general route of the line in the first place, even if total

mileage is somewhat increased in consequence;

  • avoid smaller areas of high amenity value or scientific interest by

deviation, provided this can be done without using too many angle towers,

i.e. the bigger structures which are used when lines change direction;

  • other things being equal, choose the most direct line, with no sharp

changes of direction and thus with fewer angle towers;

  • choose tree and hill backgrounds in preference to sky backgrounds

wherever possible. When a line has to cross a ridge, secure this opaque

background as long as possible, cross obliquely when a dip in the ridge

provides an opportunity. Where it does not, cross directly, preferably

between belts of trees;

  • prefer moderately open valleys with woods where the apparent height of

towers will be reduced, and views of the line will be broken by trees;

  • where country is flat and sparsely planted, keep the high voltage lines

as far as possible independent of smaller lines, converging routes,

distribution poles and other masts, wires and cables, so as to avoid a

concentration of lines or “wirescape”; and

  • approach urban areas through industrial zones, where they exist; and

when pleasant residential and recreational land intervenes between the

approach line and the substation, carefully assess the comparative costs

of undergrounding.

 

Although Government expects that the development of overhead lines will often be appropriate, it recognises that there will be cases where this is not so. Where there are serious concerns about the potential adverse landscape and visual effects of a proposed overhead line, these will have to be balanced against other relevant factors, including the need for the proposed infrastructure, the availability and cost of alternative sites and routes and methods of installation (including undergrounding).

 

EN5 states that the impacts and costs of both overhead and underground options vary considerably between individual projects. Therefore, each project should be assessed individually on the basis of its specific circumstances and taking account of the fact that Government has not laid down any general rule about when an overhead line should be considered unacceptable. Consent, however, should only be refused for overhead line proposals in favour of an underground or sub-sea line if the benefits from the non-overhead line alternative will clearly outweigh any extra economic, social and environmental impacts and the technical difficulties are surmountable.


 

Local Policy

 

There is no Council policy on the siting of overhead electricity lines although the North Somerset Replacement Local Plan and Core Strategy contains policies that seek to protect residents from harmful environmental effects and also protect the landscape from inappropriate development.

 

Previous Committee resolutions

 

When the initial consultation on three possible route corridor options took place the Planning and Regulatory Committee on 26 November 2009 resolved:

 

(i) that bearing in mind any overland route would cross open countryside and close to residential properties and would therefore impact on landscape, ecology, an Area of Outstanding Natural Beauty and Sites of Special Scientific Interest, the National Grid is recommended to fully investigate the option of routing the lines along the seabed of the Bristol Channel as no explanation has been given as to why this route has not been considered;

 

(ii) that subject to the above and subject to consideration of routing of cables next to the M5 motorway having been considered and there being no other option than to put up overhead lines and pylons, the Council’s preferred option is Option 1A, replacing the 132 KV line through the district with a 400 KV line, with the undergrounding of the overhead line route through the Mendip Hills Area of Outstanding Natural Beauty; and

 

(iii) that the National Grid be requested to continually involve the Council in the process of determining the exact alignment of the overhead lines, the siting of new pylons and the process of removing existing pylons.

 

Following complaints about the lack of information on why the possibility of either a seabed or undergrounding route did not form part of the options, National Grid undertook further consultation in 2010 setting out additional information on these two approaches. This matter was discussed again at the Planning and Regulatory Committee on 21 July 2010 when it was resolved that:

 

(i)         None of the options put forward by National Grid are acceptable on the grounds that they will have an unacceptable impact on the countryside, natural environment and residents of North Somerset;

 

(ii)        National Grid is requested to continue to explore ways of overcoming the technical difficulties of subsea connections on the transmission network;

 

(iii)       The environmental consequences of the export of large amounts of electricity on the rural countryside are brought to the attention of Central Government.

 

3.               Details

 

Background

 

National Grid has a statutory obligation to connect new electricity generators to its system. National Grid have received an application from British Energy Generation Limited (now part of EDF Energy) to connect a 3600MW nuclear power station at Hinkley Point by September 2017.

 

 

The power station would comprise two 1800MW European Pressurised water reactors (EPR). It would be one of the largest single generators connected to the National Grid system and, as a result, extensive reinforcement and upgrading to the network in the region is needed to accommodate the extra power and ensure system security

 

Churchill to Weston Western Power Distribution Link

 

In September 2011 following extensive consultation National Grid announced their preferred route corridor for the proposed Hinkley Point C Connection. This involves removing the Western Power Distribution (WPD) 132kV overhead line between the existing substations at Bridgwater and Avonmouth. As a result of these proposals, National Grid need to carry out additional work in North Somerset to maintain the local electricity supplies and ensure that local homes and businesses remain connected.

 

In National Grid’s public consultation during 2009 and 2010 it was explained that they would need to build a new substation near Churchill, and approximately 4km of new connection to connect the new substation to the proposed Hinkley Point C Connection. During the consultation they received a lot of feedback asking them to consider alternative options in this area.

 

Since then, National Grid and WPD have been working together to identify options (see Plan below) to ensure that safe and reliable electricity supplies can be maintained once the existing 132kV WPD line is removed.  Their proposal to maintain electricity supplies to WPD and its customers is:

 

·      To build a new substation in an area to the west of Nye Road, north of Sandford. Out of the options considered, this option would remove the need to build more new 400kV connections in addition to that already proposed for the new Hinkley Point C Connection. The size of the substation would be approximately 200m x 140m, however this is subject to further technical study.

 

·      To select one of four route corridors for a new 132kV connection from the new substation to the existing overhead line supplying Weston-super-Mare.

 

·      To construct a short connection between the existing 132kV overhead line that runs to the east of the existing Churchill substation, into Churchill substation itself.

 

·      An extension to Churchill 132kV substation.

 

National Grid have produced three reports which explain the options considered to maintain local electricity supplies once the WPD overhead line between Bridgwater and Avonmouth is removed.

 

Distribution System Options Report

 

This report considers five technical options for maintaining supplies to the local distribution network. The report concludes that a new substation close to the corridor of the Hinkley Point C Connection in the Sandford/Churchill area best addresses the technical, economic and environmental duties of National Grid and WPD.

 

Substation Siting Study

 

This report identifies three possible areas for the new substation in the Sandford/Churchill area:

(i) Adjacent to Churchill sub station

 

(ii) West of Nye Rd, Sandford

 

(iii) East of Nye Rd, Sandford   

 

 

 

The report concludes that an area to the west of Nye Road, to the north of Sandford would be the preferred area. The benefit of this option is that it would require no additional 400kV connections, and would have the least impact on the environment.  However it does note that if any new 400kv connection were to be undergrounded then the Churchill sub station option would be more environmentally suitable.

 

Route Corridor Study (WPD)

 

A new 132kV connection would be needed from the new substation to the existing overhead line connecting Weston-super-Mare. The report identifies four route corridors within which the new 132kV connection could be built. Route Corridor B would be the least environmentally constrained corridor for a new overhead line connection because it:

 

·        Contains the fewest environmental constraints; and

·        Would be the joint shortest route and is furthest from homes; and

·        Would allow the removal of approximately 1.2km of the existing

132kV overhead line that connects to Weston-super-Mare

 

There are two different types of overhead line supports that could be used for a new 132kV overhead line, either:

 

·        Two rows of wood poles (approximately 14 metres tall); or

·        One row of steel lattice pylons (approximately 26 metres tall).

 

Two rows of wood poles are preferred because they are smaller and would be easier to accommodate within the surrounding landscape. An alternative option would be to use underground cables. Undergrounding short sections of 132kV lines is considerably cheaper then undergrounding National Grid high voltage lines, however it is still significantly more expensive than using wood poles. If underground cables were used for the entire 132kV connection there would be little to choose between the corridors, but Route Corridor D would provide the opportunity to remove the greatest amount of the existing overhead line that connects to Weston-super-Mare.

 

Suggested response to National Grid

 

Comments on these various options are largely focused on their respective landscape, biodiversity and archaeological impacts. Very often these interests have conflicting priorities. For example undergrounding or substantial ground works can often benefit the landscape but can damage or destroy archaeological and biodiversity interests.

 

Sub station study

 

With regard to the siting of the sub-station, the west of Nye Road option is the most preferable option given that:

 

(i)  it would be sited immediately adjacent to the preferred 400 kV route corridor and there would not be any additional requirement for a 400 kV connection which would potentially involve the construction of very high pylons;

 

(ii) there are a number of agricultural/industrial buildings in the locality and the impact of a suitably designed sub station would not be so great as other locations in the more open countryside;

 

 

(iii) in common with other options the area is not archaeologically significant with only one site recoded in the Historic Environment Records;

 

The chosen site would need to be subject to a number of detailed studies including a traditional archaeological evaluation, bat activity survey (within the North Somerset and Mendip Bats Special Area of Conservation component at Banwell Ochre Caves) and a 'shadow' Habitats Regulations Assessment.

 

A Gas Insulated Switchgear sub station is far more preferable than an Air Insulated sub station option, as the majority of  equipment can be housed within a building that can be designed like an agricultural building so as to blend in with the surrounding environment and also contain features that assist bird nesting/bat foraging. National Grid are suggesting that the WPD equipment would be Air Insulated and it would be preferable if this could also be Gas Insulated even if it requires a larger building.

 

To compensate for any impact on bats and the landscape it is critical that compensatory tree and hedge planting on site with native shrub and tree species of local provenance are carried out to provide no net decrease (and ideally an increase) in the number of trees or the length of hedgerows on site.

 

WPD Corridor Study

 

Landscape

 

Given that the existing route passes through the area of high landscape value there would be significant landscape benefit in removing as many of the metal lattice towers as possible. If an overhead option was chosen this would favour the Corridors C and D or a combination of the two.  The use of timber poles for any new connection is the preferred option  

 

The preferred option from a landscape perspective would be to use the first part of Corridor D i.e. Weston-super-Mare end (subject to detailed routing to avoid the safeguarded Junction 21 Relief Rd) as far as the intersection with Corridor C and then switch to Corridor C. This would reduce the impact upon the River Banwell. This gives the greatest removal of existing towers and minimises the impact on the Puxton Park tourist attraction immediately to the north of the Corridor C connection point.  This also potentially reduces the impact upon the number of hedges and trees, the density of which generally increases near the river. Impact on residences should be low with careful route design within the two corridors suggested above.

 

Looking at the potential visual impacts, undergrounding would offer a solution to impacts in views from the AONB and locally.  It would allow any of the routes to be selected.  However detailed routing studies would need to then look at which route caused least harm to the landscape, particularly hedges and trees, as well as the other environmental criteria. A below ground connection commencing as close to the M5 junction as possible would be the favoured option in terms of the overall landscape improvement  (subject to appropriate mitigation for loss of hedgerow and trees). 

 

If an above ground option had to be selected, then a combination of Corridors C and D as described above, is preferable.


 

Heritage

 

Undergrounding is by far the least favourite option as far as heritage is concerned.

While recognising that the footprint of the proposed new 132 kv lines will be smaller than for a 400kv line any underground works will still be approximately 30 metres wide.   The effect of these engineering works, track laying, contractors compounds etc will be significant.

 

Generally, the shorter the line of new construction the better, as far as heritage is concerned. Unlike for some of the other interests, removing lines will almost certainly simply increase the damage caused by putting posts/towers in the first place.

 

On heritage grounds there is a mild preference for route A although other routes can be accommodated with appropriate safeguards.

 

Biodiversity

 

Corridors A and B are preferred to C and D on ecological grounds which have unavoidable impacts on two designated Wildlife Sites (policy ECH/14 in the Local Plan refers).  The precise route should avoid Wildlife Sites and the SSSI providing a suitable buffer of at least 5 metres (10 metres is preferable). Any undergrounding works would need to avoid designated Wildlife Sites and Sites of Special Scientific and ensure any sedimentation of watercourses caused by erosion and long term hydrological changes caused by excavation and reinstatement are avoided or minimised.

 

Highways

 

At the western end of Corridor D the proposed alignment of the route corridor would conflict with the current safeguarded route for the Junction 21 Relief Road. Any overhead or underground works would present a major obstruction to its delivery and should be avoided. Any alignment based on Route Corridor D therefore may have to be re-aligned to the east which would bring it closer to residential properties

 

To summarise, the National Grid’s preferred option of Route B for overhead works (preferably with wooden poles) is acceptable. Undergrounding would have significant landscape benefits but there would be severe considerations for archaeological and biodiversity interests which would have to be addressed.

 

Preferred Route Corridor Hinkley to Seabank

 

In addition to the above consultation on the Weston-Churchill WPD link, National Grid are seeking views on what areas/sites/features people value within the preferred route corridor running through North Somerset.  With the exception of the Tickenham Ridge around the Cadbury Camp Lane, the preferred route corridor follows the line of the existing 132 kV line and has been divided up into seven geographical areas. Through a web based interactive feedback tool the public can record what they value within the corridor. 

 

A lot of environmental information has already been provided to National Grid through officer/member representation on the various thematic groups and Community Forums. However this consultation stage does represent another opportunity for the Council to put forward its views to National Grid on how important it is to preserve the character of the Mendip Hills Area of Outstanding Natural Beauty, the Tickenham Ridge and the open views across the levels from the settlements of Nailsea, Tickenham, and Yatton.

 

Although extensive undergrounding will limit the landscape impact there are significant implications for archaeological and biodiversity interests from undergrounding. The width of any undergrounding for a 400kV line can be up to 55 metres (nearly twice the width of the M5) and will also involve the construction of construction compounds and access tracks. Although the land can be restored there are still environmental concerns in that trees cannot be planted along its length and sealing end compounds (30m x 80m) are required at either end. In addition any archaeological and biodiversity interests would be disturbed and there could be significant effects on the drainage regime especially on the levels. It is possible that mitigation works to offset any such adverse effects can be negotiated once a detailed alignment is known.  

 

It is anticipated that the detailed alignment for the 400kV connection will be subject to public consultation in November 2012, prior to the submission of a Development Consent Order to the Planning Inspectorate in 2013 .The detailed alignment will set out what parts (if any) of the route will be undergrounded and the approximate positioning of pylons and cables.

 

4.               Consultation

 

Public consultation took place between 6 June and 23 July 2012. Four local exhibitions were held at:

 

Winscombe Community Centre Monday 18 June, 2:00pm – 8:00pm

Banwell Village Hall Friday 22 June, 2:00pm – 8:00pm

Banwell Village Hall Friday 29 June, 2:00pm – 8:00pm

Banwell Village Hall Saturday 7 July, 10:00am – 4:00pm

 

In addition members were invited to briefing sessions on 12/13 June and newsletters have been delivered to affected households. Two parish cluster meetings relating to the Weston- Churchill Link were also arranged by National Grid in March and May.

 

5.                Financial Implications

 

There are no financial implications.

 

6.                RISK MANAGEMENT

 

Any delay in agreeing a preferred route corridor and the sub station siting could result in a consequential delay for National Grid in submitting their application in late 2013.

 

7.                Equality Implications

 

No equality implications.

 

8.                Corporate Implications

 

At this stage the exact siting of the required infrastructure is not known and therefore any implications for the Council’s land and buildings is unknown.

 

9.                Options considered

 

National Grid has put forward a number of options for consideration

 

 

Author

 

Graham Quick Local Planning Team Leader 01934 426177

 

Background Papers

 

Route Corridor Study

Strategic Options Report

Strategic Options Report Additional Information June 2010

Statement of Community Consultation

Hinkley Point C Connection consultation zone map

Map 1: Hinkley Point Power Station, Bridgwater, Woolavington and Highbridge

Map 2: Mendip Hills AONB, Weston-super-Mare, Yatton, Congresbury and Nailsea

Map 3: Clevedon, Portishead, City of Bristol and Avonmouth

Connecting Hinkley Point C - An overview (DVD)

Connecting Hinkley Point C - The technical challenges (DVD)

High Voltage Direct Current electricity – technical information (Factsheet)

How we develop major projects (Factsheet)

Electric and Magnetic Fields (EMFs) (Factsheet)

Planning Act 2008 (Factsheet)

The Energy Challenge (Factsheet)

National Grid and the Electricity Market (Factsheet)

Undergrounding (Factsheet)

High Voltage Direct Current (HVDC) electricity (Factsheet)

Working with You: Information for landowners and occupiers (Factsheet)

Undergrounding high voltage electricity transmission: The technical issues

Undergrounding policy: Approach to new connections

Electric and Magnetic Fields: the facts

The Holford Rules

National Grid’s commitments when undertaking work in the UK: Our stakeholder, community and amenity policy

Distribution System Options Report

Substation Siting Study

Route Corridor Study (WPD)

 

All of these documents are available on National Grids website  www.nationalgrid.com