Pre Application Consultation

On 6 December 2019 we launched our pre-application consultation on proposals to remove pylons across the Dwyryd Estuary and place the connection in a tunnel underground.


We’ve been working closely with local technical stakeholders, including the Snowdonia National Park Authority, Gwynedd Council, Cadw, Natural Resources Wales and the National Trust, as well as landowners and independent landscape consultants, to develop our plans. This has included many detailed ecological and engineering surveys and identifying potential routes for the new underground connection.

We want to make sure that we take on board the views of local people and wider stakeholders before we submit our planning application. As part of this consultation we’re making copies of documents available locally and online. These documents are where you can find out more and have your say on our proposals.

Until 10 January 2019, a complete copy of our pre-application documentation will be available on this page. We’ve also made all the documents available to view in Snowdonia National Park Authority Office, Penrhyndeudraeth, LL48 6LF so people can look at our plans in more detail.

We’ll be holding a public event on between 2pm and 8pm on 11 December 2019 at the Snowdonia National Park Authority Offices, LL48 6LF. This will be an opportunity for you to come along and view our documents and speak to members of the National Grid VIP team. We hope to see you at the event, there’s no need to make an appointment so please come along at a time convenient to you.

Feedback on the draft application can be submitted online here, via email or via mail FREEPOST VISUAL IMPACT PROVISION.

If you have questions about our work or would like any information please contact our community relations team on 0800 019 1898, email

Please note, given the technical nature of some of our documents, these are only available in English.

Application for Planning Permission

Application for Planning Permission

Environmental Summary English

Environmental Summary Welsh

Design Access Statement

East- Architectural – Proposed Roof Plan – Cilfor

East- Cilfor Shaft Site – Construction and Permanent Access Track

East- Eastern Tunnel Head House Building – E & W Elevations

East- Eastern Tunnel Head House Building – N & S Elevations

East- Proposed Cilfor SEC Elevation

East- Proposed Cilfor SEC Layout

East- Proposed Site Plan Eastern Tunnel Head House

Planning Application East Location Plan

Planning Application Location

Planning Application West Location Plan

West- Architectural – Proposed Roof Plan – Garth

West- Proposed Site Plan Western tunnel Head House

West- Western Tunnel Head House Building – E & W Elevations

West- Western Tunnel Head House Building – N & S Elevations

Chapter one

Chapter 1 Introduction

Figure 1.1 Overview

Figure 1.2 Consenting

Chapter two

Chapter 2 Project Description

Appendix 2A CEMP Part 1

Appendix 2A CEMP Part 2

Appendix 2A CEMP Part 3

Appendix 2B Report on EMF

Appendix 2C Options Appraisal

Figure 2.1 Combined

Figure 2.2 Combined

Figure 2.3 – Proposed Garth SEC Compound Elevation

Figure 2.4 – Proposed Garth SEC Compound – Cable Circuit Elevations

Figure 2.5 – Proposed Site Plan Western tunnel Head House

Figure 2.6 – Western Tunnel Head House Building – N & S Elevations

Figure 2.7 – Western Tunnel Head House Building – E & W Elevations

Figure 2.8 – Architectural – Proposed Roof Plan – Garth

Figure 2.9 – Proposed Site Plan Eastern Tunnel Head House

Figure 2.10 – Eastern Tunnel Head House Building – N & S Elevations

Figure 2.11 – Eastern Tunnel Head House Building – E & W Elevations

Figure 2.12 – Cilfor Shaft Site – Construction and Permanent Access Track

Figure 2.13 – Proposed Cilfor SEC Layout

Figure 2.14 – Proposed Cilfor SEC Elevation

Figure 2.15 – Architectural – Proposed Roof Plan – Cilfor

Chapter three

Chapter 3 Environmental Appraisal Process

Appendix 3A Screening Opinion

Appendix 3B Scoping Responses

Appendix 3C Embedded Mitigation

Chapter four

Chapter 4 Consultation

Chapter five

Chapter 5 Planning Policy

Figure 5.1 Planning Policy Designations

Chapter six

Chapter 6 Landscape & Visual Appraisal

Appendix 6A LVIA Methodology

Appendix 6B Landscape Character

Appendix 6C Viewpoint Appraisal

Appendix 6D Aboricultural Report

Figure 6.1 LVA Study Area

Figure 6.2 ZTV from Above Ground Operational Infrastructure

Figure 6.3 ZTV of Western THH

Figure 6.4 ZTV of Eastern THH

Figure 6.5 Comparative ZTV of 4ZC027 and 4ZC027R

Figure 6.6 ZTV of Existing Pylons to be Removed

Figure 6.7 Landform and Drainage S1

Figure 6.7 Landform and Drainage S2

Figure 6.8 Tree Cover

Figure 6.9 Settlements and Infrastructure

Figure 6.10 Recreation, Routes and Open Access Land S1

Figure 6.11 Landscape Character

Figure 6.12 Seascape Character

Figure 6.13 Viewpoints

Illustrative Photomontages

Chapter seven

Chapter 7 Terrestrial Ecology

Appendix 7A – Snowdonia Botanical Report 2019

Appendix 7B – Snowdonia Animal Report

Appendix 7C HRA and AA Report

Figure 7.1 Statutory and Non Statutory Designated Sites

Figure 7.2 Phase1 Habitat Survey

Chapter eight

Chapter 8 Archaeology and Cultural Heritage

Appendix 8A

Appendix 8B

Fig8.1 Heritage Constraints

Fig8.2 Designated Heritage Constraints

Fig8.3 Historic Landscape Characterisation

Chapter nine

Chapter 9 Water Resources

Figure 9.1 Snowdonia Main Surface Water Features

Figure 9.2 WFD River Transistional and Coastal Waterbody Status

Figure 9.3 Surface Water Abstractions

Appendix 9A Flood Consequences Assessment

Appendix 9B SuDS Strategy Report

Chapter ten

Chapter 10 Ground Conditions

Appendix 10A Relevant Legislation and Policy

Appendix 10B Historic map review

Figure 10.1 Area of Search

Figure 10.2 Superficial Geology

Figure 10.3 Bedrock Geology

Figure 10.4 Contamination

Figure 10.5 Sensitive Receptors

Chapter eleven

Chapter 11 Agriculture and Land Use

Figure 11.1 Snowdonia Soilscapes

Figure11.2 Snowdonia Predictive Agricultural Land Classification

Chapter 12

Chapter 12 Transport

Annex 12A Collision Data

Figure 12.1 Highway Link References

Figure 12.2 Construction Traffic Routes

Figure 12.3 Access Locations

Figure 12.4 Traffic Survey Locations

Figure 12.5 Public Rights of Way

Figure 12.6 Cycle Routes

Figure 12.7 Garth Visibility Splays

Figure 12.8 Cilfor Visibility Splays

Chapter thirteen

Chapter 13 Socio-economics and Tourism

Figure 13.1 Study Area

Figure 13.2 Tourism Hubs & Tourist Attractions

Figure 13.3 Recreational Activities

Chapter fourteen

Chapter 14 Noise & Vibration

Appendix 14.A Baseline Noise Data (1)

Appendix 14.B Construction Plant

Appendix 14.C Mitigation Options

Appendix 14.D Construction Noise and Vibration Predictions

Figure 14.1 Snowdonia Noise Receptors

Chapter fifteen

Chapter 15 Marine Physical Processes Chapter

Figure 15-1 Overview Dwryrd Estuary

Figure 15-2 Channel Migration over the Period 1889 to 2009

Chapter sixteen

Chapter 16 Marine Ecology

Appendix 16A Marine HRA

Appendix 16B Saltmarsh Survey

Figure 16-1 European and National Sites Screened in HRA Stage 1

Chapter seventeen

Chapter 17 Marine Archaeology

Appendix 17A – Marine archaeology Desk Based Assessment

Appendix 17B – Marine archaeology geophys review

Figure 17-1 Location of un-named wreck showing 100m archaeological exclusion

Chapter eighteen

Chapter 18 Cumulative

Chapter nineteen

Chapter 19 Health in Impact Assesment Signposting