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1.5 Site selection and alternatives ​

1.5.1 Overview ​

1.5.1.1 The Applicant has undertaken site selection process to identify the location of the Mona Offshore Wind Project infrastructure. The aim was to identify sites and routes that are environmentally acceptable, deliverable and consentable, whilst also enabling the benefits in the long term of the lowest energy cost to be passed to he consumer.

1.5.1.2 The process has taken account of environmental, physical, technical, commercial, and social considerations and opportunities as well as engineering requirements. Each stage of the site selection process forms part of an iterative design process undertaken to identify the most suitable locations and configuration for the Mona Offshore Wind Project infrastructure.

1.5.2 Identification of the Mona Array Area ​

1.5.2.1 The Crown Estate (TCE) launched the Offshore Wind Leasing Round 4 process in 2018. The Northern Wales and Irish Sea Bidding Area was one of four Bidding Areas identified by TCE through the Offshore Wind Leasing Round 4 process. The Mona Array Area was identified from within the Northern Wales and Irish Sea Bidding Area.

1.5.2.2 The Mona Offshore Wind Project extent was limited to the south by the requirement to maintain at least a 1nm offset from the International Maritime Organisation vessel routing measure (Liverpool Traffic Separation Scheme). The Mona Array Area was limited to the east by the presence of existing oil and gas infrastructure, the closest of which (Conwy platform, operated by Eni) is located approximately 1.8km from the Mona Array Area. The Mona Array Area extent was limited to the east and the south by the project decision to maintain a 10km offset from the Liverpool Bay SPA.

1.5.2.3 Further refinements to the Mona Array Area will be undertaken between PEIR and application for consent. The final Mona Array Area will be described in detail within the Environmental Statement that will accompany the application for consent.

1.5.3 Identification of the Mona Offshore Cable Corridor ​

1.5.3.1 National Grid Electricity System Operator (NGESO) coordinate changes needed to the electricity network to accommodate new offshore connections from offshore energy infrastructure. They determined that the preferred connection option representing the most optimal design (economic, efficient and co-ordinated) considering all criteria (i.e. technical, cost, environmental and deliverability) for the Mona Offshore Wind Project was a radial grid connection into Bodelwyddan Substation in North Wales.

1.5.3.2 One of the key considerations in the identification of onshore and offshore cable routing options was the identification of landfall options in the vicinity of the National Grid substation at Bodelwyddan. An initial search area was identified for the landfall between the towns of Llandulas and Prestatyn on the North Wales coast. The extent of the landfall search area was to accommodate feasible offshore export cable options and to avoid the ecological designations of the Dee Estuary SAC, SPA and Ramsar to the east, and the Menai Strait and Conwy Bay SAC to the west.

1.5.3.3 The Mona Offshore Cable Corridor was designed to avoid ‘hard constraints’ including existing offshore wind farms (Burbo Bank, Gwynt y Môr, Awel y Môr AfL area), an existing anchorage area, pipeline and cable infrastructure and the ‘Liverpool Bay’ marine aggregate extraction Area 457. In addition, it sought to specifically avoid interactions as far as possible with key ecological designations including the Dee Estuary SAC and SPA, Lavan Sands SPA and Anglesey Terns SPA. It looked to minimise interaction with ecological designations that could not be avoided, specifically Menai Strait and Conwy Bay SAC and the Liverpool Bay SPA.

1.5.3.4 Several potential route options for the Mona Offshore Cable Corridor were identified and were taken forward for further analysis and refinement. Routes were discounted due to technical feasibility and overlap with constraints.

1.5.3.5 The resulting Mona Offshore Cable Corridor which has been included in PEIR (Figure 1.1) overlaps with the following constraints:

  • Liverpool Bay SPA: this large site extends from the east coast of Anglesey to Morecambe Bay making crossing the site with the Mona Offshore Cable Corridor unavoidable
  • Menai Strait and Conwy Bay SAC: A small portion of the Mona Offshore Cable Corridor overlaps with the Menai Strait and Conwy Bay SAC. The Mona Offshore Cable Corridor avoids the mapped features of the SAC
  • Constable Bank Annex 1 Sandbank Feature: the Applicant has not been able to identify a route that avoids the Constable Bank whilst also avoiding designated reef features of the /Menai Strait and Conwy Bay SAC. The Applicant has ro uted the Mona Offshore Cable Corridor as far to the west as possible to avoid the admiralty charted Constable Bank feature
  • Sabellaria alveolata reef: The intertidal survey of the Mona Offshore Cable Corridor identified an extensive mature Sabellaria alveolata reef, an Annex 1 habitat at the landfall. The Applicant has mapped this habitat and has committed to maintaining a 50m buffer from the reef at its current extent.

1.5.4 Identification of the Mona Onshore Cable Corridor ​

1.5.4.1 Through reference to the identified area of search, combined with constraints analysis, a list of possible Mona Onshore Cable Corridor options were identified. The location of the Mona Onshore Cable Corridor is driven by the location of the Bodelwyddan National Grid substation and the location of the landfall to the proposed onshore substation site.

1.5.4.2 An iterative and multidisciplinary approach incorporating engineering, constructability, cost, environmental, landowner, community, and stakeholder considerations was used in the development of onshore cable route options. A series of internal Mona Offshore Wind Project team workshops were held to ensure each of the factors were considered effectively.

1.5.4.3 At this stage of the proposed development of the Mona Offshore Wind Project, it has been noted that the Mona Onshore Cable Corridor would pass through the Llanddulas Limestone and Gwrych Castle Wood SSSI and ancient woodland. It is recognized that open-cut trenching through this would likely result in:

  • Cutting through SSSI woodland resulting in a likely significant ecological impact and additional scrutiny on site selection
  • A permanent change to the woodland within the Gwrych Castle Historic Park and Garden (i.e. removal of it) which would require compensatory land to be replace the losses
  • A very visible permanent change to the woodland resulting in a significant visual impact from the coastal footpath and A55 as trees cannot be planted over the onshore cable route
  • A potential significant impact associated with a change to the historic setting of the Gwrych Castle.

1.5.4.4 As a responsible developer, the Applicant has made the early commitment to use trenchless techniques (HDD, micro-tunnelling, auger boring, etc. yet to be determined) to avoid these potential impacts.

1.5.4.5 Following detailed investigation of the section of the Mona Onshore Cable Corridor between the Abergele Road and Glascoed Road crossroad to the Bodelwyddan National Grid substation a number of significant utilities (such as high pressure gas main, water mains and overhead lines) have been identified that mean that a straight route cannot be optimized.

1.5.4.6 As such, the Mona Onshore Cable Corridor as assessed in the PEIR contains optionality that will be refined following formal consultation. Within the identified Mona Proposed Onshore Development Area, emerging routes of ~100m are identified. At the point of final application, a single route of ~70m will be defined which incorporates the results of ongoing studies, and feedback received during consultation.

1.5.4.7 Following consultation on the PEIR, the Mona Onshore Cable Corridor will be reviewed and a final option produced for the Mona Offshore Wind Project and its EIA to be set out in the Environmental Statement.

1.5.5 Identification of Mona Offshore Wind Project onshore substation options ​

1.5.5.1 The guiding principles for locating the project’s onshore substation are to achieve an economic and efficient connection (i.e. as close as possible to the National Grid connection point) whilst taking into account environmental. The onshore substation area of search was initially defined as a 3km buffer around the grid connection point at Bodelwyddan National Grid Substation.

1.5.5.2 The 3km buffer was subsequently expanded to 5km following engineering review of the maximum electrical distance between the Mona Offshore Wind Project onshore substation and the National Grid substation. This also increased the potential number of areas to site the onshore substation as part of the site selection process. Hard constraints (e.g. areas of infrastructure, landfills, roads, railways, overhead lines, etc.) were plotted and removed from the onshore substation area of search.

1.5.5.3 Five onshore substation search zones were identified with zone boundaries coinciding with the perimeters of hard constraint areas. An appraisal of each zone was made. Only Zone 5 was retained for further assessment, the other four having been discounted from further consideration.

1.5.5.4 Key areas removed from the area of search were the city of St. Asaph with its associated Conservation Area and listed buildings, as well as the Main River (Elwy), and its associated Flood Zones 2 and 3 to the east. The south boundary was refined to avoid a further stretch of the River Elwy and its associated flood zones, along with the Coedwigoedd Dyffryn Elwy/Elwy Valley Woods SAC, Coedydd ac Ogofau Elwy a Meirchion SSSI and the Lower Elwy Valley Historic Landscape, which encompasses scattered listed buildings and Scheduled Monuments.

1.5.5.5 The area of search (Zone 5) then formed the basis for the selection of available parcels of land to site potential onshore substations for site selection consideration. In parallel with the Scoping phase of the Mona Offshore Wind Project, in March to June 2022, a long list of onshore substation zones within the overall area of search was identified.

1.5.5.6 Following statutory stakeholder consultation and further engineering analysis, discounting of the long list resulted in seven options comprising the short-list for the onshore substation. This short-list of onshore substation options was used to form the basis of a target onshore substation consultation that ran from Monday 26 September 2022 until Monday 07 November 2022. The targeted consultation was designed specifically to seek feedback on the shortlisted locations; intending to combine the ongoing environmental assessment and technical studies with local knowledge to help narrow the location for the onshore substation for PEIR assessment. The intention of the consultation was to select one or more preferred onshore substation location(s) which would be the subject of PEIR to feed into the selection of a preferred onshore substation for the Environmental Statement. Events were held at Bodelwyddan Village Hall, as well as an online webinar, and feedback forms were available on the Mona Offshore Wind Project website – with the potential to email, use a written feedback form or freephone call.

1.5.5.7 Following consultation responses, a further review of the preferred onshore substation options was undertaken. Following the discounting of the options outlined in the long list, the following two options comprise the preferred option(s) for the onshore substation: Onshore substation option 2 and Onshore substation option 7.

1.5.5.8 Two preferred zones were considered, relative to one another, to determine preferred options for PEIR assessment and consultation. Further consideration was given to matters such as topography, access, landscape framework/ screening, hydrology and ground conditions, with a particular focus on heritage, ecology, and LVIA assessment. No conclusion has been drawn on the preferred onshore substation option for the Mona Offshore Wind Project. The indicative onshore substation areas provided for the purposes of PEIR will be further refined, subject to further site investigation, technical design work, ongoing EIA analysis, and any feedback received during the formal consultation at the PEIR stage. A decision will be made post-PEIR of the preferred onshore substation option, with an announcement to be made in mid-late 2023.

1.5.6 Next steps ​

1.5.6.1 The Applicant will continue to develop and refine the project design as it progresses towards the final application for Development Consent and beyond this as it moves towards construction. The Mona Offshore Wind Project is currently at Stage 4 in the design process. Up to this point, the Applicant has engaged with a range of stakeholders in refining the project and identifying suitable options among the alternatives considered.

1.5.6.2 As the Mona Offshore Wind Project progresses past the statutory consultation stage, the Applicant will continue engagement with stakeholders, via the Expert Working Groups (EWGs) and other consultation as necessary. The Applicant will continue to keep stakeholders informed about the project design as it continues to evolve, and the selection process for preferred options where they remain in consideration.