Bramford – Twinstead 400kV Connection

National Grid
Suffolk and Essex

One of National Grid’s nationally significant infrastructure proposals is for a 30km connection between Bramford and Twinstead. The corridor crosses four river valleys: three are locally designated and the Box Valley is part of the Dedham Valley Area of Outstanding Natural Beauty.

TEP is the manager and co-ordinator of environmental impact assessment.  TEP advised on the requirements of the Planning Act 2008 and the Infrastructure Planning (EIA) Regulations. TEP produced a Route Corridor Study which identified the key planning and environmental constraints and opportunities. This study was informed by consultation with planning authorities, statutory consultees and local communities.

TEP is retained to take the project to full design and application for consent, identifying working methods and mitigation to avoid, reduce or compensate for adverse effects where possible, and to produce the required Environmental Statement.

TEP’s landscape architects, ecologists and heritage consultants provided detailed landscape, visual, ecological, arboricultural and historic environment assessment expertise. Effects on landscape character, views, biodiversity and on the historic environment were very important in the initial identification and assessment of route corridors and have continued to be strong influences in identifying and assessing the connection options.

The Landscape Assessment considered the character of the south Suffolk and Essex landscape, using published assessments and site survey. The assessment considered the “Holford Rules” for routing of transmission infrastructure and other published good practice.     The corridor was first considered as six ‘study areas’ of homogeneous landscape character. This allowed a second stage of assessment of the effects of connection options on the landscape.

The Visual Assessment considered views from public and private viewpoints.  Chartered Landscape Architects recorded baseline views and have considered the potential change to these views for each of the connection options.  Zone of Theoretical Visibility (ZTV) mapping is used to inform and verify the visual assessment.

The Ecological and Arboricultural Assessment involved detailed surveys for bats, great crested newts, breeding and wintering birds, reptiles, water voles, otters and dormice (the latter carried out by experts from Suffolk Wildlife Trust). At the detailed design stage, arboricultural surveys were carried out to inspect trees of particular interest and identify mitigation measures necessary for the creation of a corridor. A particular issue for detailed assessment was the ornithological interest of the Hintlesham Woods SSSI, managed by RSPB.

The historic environment assessment involved desk-based and field surveys to identify the heritage resources within the corridor and to enable an assessment of the effects of connection options on the historic environment. The assessment included the identification of areas of high archaeological potential so that a strategy could be developed for the identification, avoidance and mitigation of archaeological remains. The contribution made by setting to the significance of heritage assets was also assessed so that any likely indirect effects can be predicted. Of particular concern is the potential for an adverse effect on the setting of Grade I listed Hintlesham Hall, in response to which a detailed assessment has been undertaken by TEP.

As part of National Grid’s commitment to engagement, TEP facilitates local Thematic Groups which comprise specialists from the planning authorities and statutory consultees.  These groups provide information and constructive challenge to National Grid and are important in advising on the scope of the EIA.  Consultation with local communities has been an important element of the environmental assessment, meeting landowners, neighbours, objectors and campaigners in Community Forums and ‘drop-in’ events where experts are available to talk to individuals on specific issues.


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