Glyn Rhonwy Pumped Storage Development Consent Order
Environmental Statement Volume 1: Non Technical Summary
PINS Reference EN010072
Document No. 6.01
Regulation 5(2)(a) and Infrastructure Planning (Environmental Impact Assessment) Regulations 2009
Author AECOM
Revision Date Description
0 October 2015 Submission Version Glyn Rhonwy Pumped Storage 6.01 Non-Technical Summary Development Consent Order Volume 1
Revision Date of Comments Author(s) Checker Approver No. Issue
October 0 Final Issued Various CA DR 2015
August / September Working Draft Various CA DR 2015
October 2015 Glyn Rhonwy Pumped Storage 6.01 Non-Technical Summary Development Consent Order Volume 1 Contents
EXECUTIVE SUMMARY
CHAPTER 1 INTRODUCTION
CHAPTER 2 APPROACH TO EIA & CONSULTATION
CHAPTER 3 DESIGN EVOLUTION AND ALTERNATIVES
CHAPTER 4 PROJECT DESCRIPTION
CHAPTER 5 SUMMARY OF ENVIRONMENTAL IMPACT ASSESSMENT Figures
FIGURE 1.1 SITE LOCATION PLAN
FIGURE 1.2 ORDER LIMITS
FIGURE 3.1 ECOLOGICAL DESIGNATIONS
FIGURE 3.2 LANDSCAPE DESIGNATIONS
FIGURE 3.3 SNOWDONIA NATIONAL PARK AUTHORITY
FIGURE 3.4 SITE DESCRIPTION
FIGURE 3.5 DESIGN REVIEW 1
FIGURE 3.6 DESIGN REVIEW 2
FIGURE 3.7 DESIGN REVIEW 3
FIGURE 3.8 DESIGN REVIEW 4
FIGURE 3.9 DESIGN REVIEW 6
FIGURE 3.10 DESIGN REVIEW 7
FIGURE 3.11 DESIGN REVIEW 8
FIGURE 4.1 DEVELOPMENT OVERVIEW
FIGURE 4.2 INDICATIVE ROUTE OF ELECTRICAL CONNECTION
FIGURE 5.1 ZONE OF THEORETICAL VISIBILITY
FIGURE 5.2 CUMULATIVE DEVELOPMENTS
October 2015 Glyn Rhonwy Pumped Storage 6.01 Non-Technical Summary Development Consent Order Volume 1 Abbreviations & Glossary
2012 ES The previously submitted ES
AGL Above Ground Level
AOD Above Ordnance Datum
AQMP Air Quality Management Plan
BOCC Birds of Conservation Concern
BPM Best Practicable Means
BS4142 British Standard – Method for Rating Industrial Noise Affecting Mixed Residential and Industrial Areas
BS7445 British Standard- Description and Measurement of Environmental Noise
CADW The Welsh Government's Historic Environment Service
CCW Countryside Council for Wales (now NRW)
CEMP Construction Environmental Management Plan
CoCP Code of Construction Practice
CTMP Construction Traffic Management Plan
DCO Development Consent Order
DECC Department of Energy & Climate Change
Development The proposed 99.9MW Glyn Rhonwy Pumped Storage Facility
DMP Dust Management Plan
DNO District Network Operator
EIA Environmental Impact Assessment
EN-1 Overarching National Policy Statement for Energy
EN-3 National Policy Statement for Renewable Energy Infrastructure
EN-5 National Policy Statement for Electricity Networks Infrastructure
EP Environmental Permit
EP Environmental Permit
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ERFMP Emergency Response and Flood Risk Management Plan
ES Environmental Statement
ES The Environmental Statement for the Glyn Rhonwy Pumped Storage DCO
FCA Flood Consequences Assessment
GAPS Gwynedd Archaeological Planning Service
GC Gwynedd Council
GI Ground Investigation
Ha / ha Hectare
HASP Halth and Safety Plan
HDPE High Density Poly-ethylene
Headpond Upper reservoir
HGV Heavy Goods Vehicle
HMP Habitat Management Plan
HRA Habitat Regulation Assessment
Hz Hertz
ICP Independent Connection Provider kv Kilovolt – measure of electrical current
LCA Landscape Character Area
LHA Local Highway Authority
LSE Likely Significant Effect
LVIA Landscape & Visual Impact Assessment
LWS Local Wildlife Site m Metres m3 Cubic metres
MTAN Minerals Technical Advice Note
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MW Mega Watts – measure of energy, one million watts
MWh Mega Watt Hours – measure of energy generated in hours
NMP Noise Management Plan
NPS National Policy Statement
NRW Natural Resources Wales (formally EAW and CCW)
NSIP Nationally Significant Infrastructure Project
NSR Noise Sensitive Receptor
NTS Non-Technical Summary
NVC National vegetation Classification
PC Principal Contractor
PEIR Preliminary Environmental Information Report
Penstock The pipe connecting the headpond to the power house
PINS Planning Inspectorate
Power House Containing the combined pump/turbines
PPP Pollution Prevention Plan
PPW Planning Policy Wales
PRoW Public Rights of Way
Q1 Quarry 1- Chwarel Fawr
Q2 Quarry 2- Chwarel Cefn Du
Q3 Quarry 3- Cook
Q4 Quarry 4- Ddol
Q5 Quarry 5- unnamed but known locally as Gideon Quarry (previously known as Glynrhonwy)
Q6 Quarry 6- Glyn Rhonwy (also locally known as Mancer Quarry)
Q7 Quarry 7- Unnamed and is a smaller quarry excavated between and to the south of Glyn Rhonwy (Q6) and the former munitions store (Q8). It
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has been used to dispose of slate waste and has more established vegetation colonising its base than other quarries at the site.
Q8 Quarry 8 former WWII munitions store (known locally as the bombstore)
QBC Quarry Battery Company Ltd
SAC Special Area of Conservation
SNP Snowdonia National Park
SNPA Snowdonia National Park Authority
SoCC Statement of Community Consultation
SoS Secretary of State
SP Scottish Power
SPH Snowdonia Pumped Hydro Ltd or “the Applicant”
Spillway Infrastructure A discharge point from the headpond and a joint discharge/abstraction point from the tailpond
SSSI Site of Special Scientific Interest
SUDS Sustainable Urban Drainage Systems
T&CPA application The planning application submitted under the Town & Country Planning Act for the 49.9MW scheme as approved by GC
T&CPA Town and Country Planning Act 1990
TA Traffic Assessment
Tailpond Lower reservoir
Tailrace The pipe connecting the power house to the tailpond
TAN Technical Advice Note
TBM Tunnel Boring Machine
The Act The Planning Act 2008
The Applicant Snowdonia Pumped Hydro (SPH) Ltd
The Approved Scheme The approved 49.9MW scheme Glyn Rhonwy Pumped Storage facility
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TPO Tree Protection Order
TWL Top Water Level
UDP Unitary Development Plan
UXO Unexploded Ordnance
V Volt
WFD Water Framework Directive
WG Welsh Government
WMP Waste Management Plan
WTMP Water Management Plan
ZTV Zone of Theoretical Visibility
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October 2015 Glyn Rhonwy Pumped Storage 6.01 Non-Technical Summary Development Consent Order Volume 1
EXECUTIVE SUMMARY
Introduction
This Non-Technical Summary (NTS) accompanies a Development Consent Order (DCO) application which has been submitted by Snowdonia Pumped Hydro (SPH – hereafter referred to as “the Applicant”) for the construction and operation of a pumped storage scheme with an output capacity of 99.9 megawatts (MW) at the Glyn Rhonwy and Chwarel Fawr quarries, near Llanberis (hereafter referred to as ‘the Development”).
The Development exceeds 50MW installed output capacity, and is therefore designated as a Nationally Significant Infrastructure Project (NSIP) under the Planning Act 2008 (“the Act”). The application for the DCO is submitted to the Planning Inspectorate and will be determined by the Secretary of State for Energy & Climate Change (SoS).
Environmental Impact Assessment
EIA is the process of identifying, evaluating and, where possible, mitigating the likely significant environmental effects of a proposed development. It promotes the early identification and evaluation of the potentially significant environmental effects of a proposed development and enables appropriate mitigation (that is measures to avoid, reduce or offset significant adverse effects) to be identified and incorporated into the design of a development, or commitments to be made to environmentally sensitive construction methods and practices.
The Infrastructure Planning (Environmental Impact Assessment) Regulations 2009 (as amended) (the EIA Regulations) apply in the case of applications under the Planning Act 2008. The EIA Regulations require an Environmental Impact Assessment (EIA) to be carried out to determine the likely significant effects of a proposed development on the environment.
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The results of the EIA also ensure that decision makers such as the SoS and statutory consultees such as planning authorities, in this case Gwynedd Council, as well as other interested parties, including local communities, are aware of a development’s environmental effects so that these may be considered before a decision is taken on whether or not the development should be approved.
An Environmental Statement (ES) reports the findings of the EIA. The ES which accompanies the application for the DCO has been prepared by AECOM on behalf of the Applicant.
The methodology section within individual technical chapters of the ES sets out the criteria used in judging the significance of effects and the process that has been undertaken to gather baseline information and predict the likely effects and their magnitude.
Mitigation measures are actions that are implemented to reduce the significance of an environmental effect. Should a likely significant effect remain after the implementation of mitigation measures, this is known as a significant residual effect.
Pre-Application Consultation
Under the Planning Act 2008, the Applicant is required to undertake formal consultation with the local community and stakeholders to allow them to find out more about the Development, and give the Applicant their views on the proposals in line with the requirements of the Act. Formal statutory consultation was conducted during February and March 2015. Comments and responses received from the consultation stage were reviewed and considered in finalising the proposed scheme and the final ES to be submitted with the DCO application.
Purpose of this NTS
This document provides a Non-Technical Summary (NTS) of the ES including setting out the evolution of the Development as well as describing the results of the EIA to allow readers to understand the likely significant effects of the Development would be, both adverse and beneficial, and the
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proposed mitigation measures to avoid or minimise adverse effects, where appropriate.
The NTS summarises the ES and is structured as follows:
x Chapter 1 – Introduction
x Chapter 2 – Approach to EIA & Consultation;
x Chapter 3 – Design Evolution & Alternatives
x Chapter 4 - Project Description
x Chapter 5 – Summary of Environmental Impact Assessment
x Chapter 6 - Conclusions
Submission
The SoS will consider the ES and all other relevant technical information, as part of their responsibilities for determining the application. They will also take into account any representations made by interested parties during the examination of the application.
Further Information and Consultation
Additional copies of this NTS can be requested free of charge, and are available from the project website (www.snowdoniapumpedhydro.com). A Welsh language version of this NTS is available on the project website and hard copies are available upon request.
The ES is available on the project website (www.snowdoniapumpedhydro.com) and can be inspected at several locations as detailed in Table 1.
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Table 1 Inspection Venue Details Location & Address Copy available Opening Times Llyfrgell Llanberis One inspection hard Tuesday 1400-1800, Library, Ffordd Capel copy and electronic Thursday 1000-1200 and Coch, Llanberis, LL55 copies available 1300-1700, Friday 1400- 4SH 1800. Gwynedd Council One inspection hard Monday – Friday 0840- Headquarters, Castle copy and electronic 1700 Street, Caernarfon, copies available LL55 1SE Caernarfon Library, Electronic copies Monday and Tuesday 0930 Pavilion Hill, available – 1900, Wednesday 0930 Caernarfon, LL55 1AS – 1300 Waunfawr Surgery, Electronic copies Monday, Tuesday & Liverpool House, available Thursday 0800-1830 Waunfawr, LL55 4AG Deiniolen Library , Ty Electronic copies Monday 1500-1800, Elidir, High Street, available Wednesday 1400-1700, Deiniolen, LL55 3HR Friday 1000-1200.
Copies of the ES and DCO submission are available on request and will be charged at £250 for a printed hard copy (including appendices) and £5 for an electronic copy on CD/DVD.
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1 INTRODUCTION
1.1 Introduction
1.1.1 This document is the non-technical summary (NTS) of the Environmental Statement (ES) for the Glyn Rhonwy Pumped Storage Development Consent Order (hereafter referred to as the “Development”). The ES has been submitted in four volumes. This NTS is Volume 1 with the remaining volumes as follows:
x Volume 2 – Main Text (Document Ref: 6.02)
x Volume 3 – Appendix (Document Ref: 6.03)
x Volume 4 – Figures & Photomontages (Document Ref: 6.04)
1.1.2 The Final ES has been produced to accompany the Development Consent Order (DCO) Application under the Planning Act 2008 (“the Act”). The Development exceeds 50 megawatts (MW) capacity and is therefore classed as a Nationally Significant Infrastructure Project (NSIP) which requires the consent of the Secretary of State (SoS) through the approval of a DCO under the Act. The decision of whether or not to grant the DCO will be made by the Secretary of State for Energy and Climate Change (“SoS”). If the DCO is granted, the decisions on the detailed approvals under the conditions in the DCO (known as “Requirements”) will be made by Gwynedd Council (GC).
1.1.3 The Development will require a number of other consents in addition to the DCO (for example permission to abstract water from Llyn Padarn to fill the reservoir) which are not dealt with in this document, but are explained in Document 5.04 “Details of Other Consents and Licenses” and within the technical chapters of the ES, as appropriate.
1.1.4 The location of the Development is shown on Figure 1.1.
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1.1.5 This NTS gives an overview of the Development, including the need for the project, the alternatives that have been considered and a description of the Development itself. This NTS also provides an overview of the conclusions reached in the ES. Feedback received during the pre-application consultation process has helped to inform the detail of the Development and to further refine the EIA. The full and detailed findings of the EIA have been presented in the ES.
1.1.6 This document is a summary (in non-technical language) of the ES for the Development. The ES and the accompanying NTS have both been prepared in accordance with Regulations 2 and 10 of the Infrastructure Planning (Environmental Impact Assessment) Regulations 2009 (as amended) (the ‘EIA Regulations’).
1.2 The Applicant
1.2.1 Snowdonia Pumped Hydro Limited (“SPH”) is the applicant for this DCO. The company is a subsidiary of the Quarry Battery Company Limited (“QBC”) which seeks to develop disused quarry systems into pumped storage facilities.
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1.3 Planning History
1.3.1 The Development is located approximately 1.5km north west of Llanberis, as shown on Figure 1.1.
1.3.2 QBC was granted planning permission (Ref: C12/1451/LL) by GC on the 19th February 2014 for the construction and operation of a 600MWh (megawatt hours) pumped storage scheme, with an output capacity of 49.9MW, at the Glyn Rhonwy and Chwarel Fawr quarries, near Llanberis. The permission was granted under the Town & Country Planning Act 1990 (T&CPA). An application (Ref: C15/0308/15/DA) for a non-material amendment (NMA) (was submitted in March 2015 to correct an inaccuracy in the plans listed under Condition 2 of the extant permission. The application was approved on 6th May 2015 and Condition 1 of the NMA approval lists the approved plans correctly.
1.3.3 An EIA was undertaken of the approved scheme and the T&CPA application was accompanied by an Environmental Statement.
1.3.4 Subsequent to the grant of planning permission under the T&CPA, SPH has been established as a subsidiary of QBC to take the Glyn Rhonwy scheme forward.
1.3.5 Due to changes in the energy market, the decision was taken to increase the capacity of the approved scheme to 99.9MW. As the capacity of the scheme is above 50MW, it falls under the definition of a NSIP and therefore requires a DCO under the Act, rather than Planning Permission under the T&CPA. The 99.9MW proposal is referred to throughout this document as ‘the Development’.
Terminology
1.3.6 The following terminology is used throughout this NTS (and the ES):
x The ‘approved scheme’ refers to the approved 49.9MW Glyn Rhonwy Pumped Storage facility;
x ’T&CPA application’ refers to the planning application submitted under the Town & Country Planning Act for the 49.9MW scheme as approved by GC;
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x The ‘2012 ES’ refers to the previously submitted ES;
x ‘The Development’ refers to the proposed 99.9MW Glyn Rhonwy Pumped Storage facility;
x ‘The Development site’ refers to land within the red line site boundary or the “Order Limits” shown in Figure 1.2 of the NTS below;
x ‘Order Limits’ refers to the red line site boundary; and
x ‘The Applicant’ refers to Snowdonia Pumped Hydro Limited (SPH).
1.3.7 Further details of the Development can be found in Section 4 of this NTS and in Chapter 4 Project Description of the ES.
1.4 Concept of Pumped Storage
1.4.1 Pumped storage is a method of generating electricity at times of peak demand at short notice. This is achieved by releasing water from an upper reservoir, which passes through a turbine, into a lower reservoir. Water is then pumped back up during periods of low demand. The water is then stored in the upper reservoir ready for the next time of peak demand. More
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detail is provided in Chapter 4 Project Description of the ES and in section 4 of this NTS.
1.5 Background & Need for the Development
1.5.1 The electricity supply network in the UK relies on the generation of electricity from several sources, more traditionally through baseload thermal generation plants such as coal, gas and also nuclear. These generators all provide power to keep the national grid at a steady 50 Hertz (Hz), essential to the smooth operation of electrical equipment throughout the UK.
1.5.2 At times of peak demand, pumped storage has the ability to provide electricity quickly. Pumped Storage systems are able to start extremely rapidly from cold start and even quicker from standby mode, in some cases achieving full power within 15 seconds.
1.5.3 Compared to thermal power stations, which can take several hours to reach full generating capacity, pumped storage has the ability to store and generate large quantities of energy, making such facilities the most flexible of all grid-scale electrical generation technologies.
1.5.4 Pumped storage is not a form of renewable energy as it requires energy to pump the water back up from the lower reservoir to the upper reservoir, ready for the next supply of energy to the electricity network. This happens at night when abundant cheaper electricity can be utilised.
1.6 Introduction to the Development
1.6.1 The quarry system has been numbered from Q1 in the west to Q8 in the east, which can be seen in Figure 1.2:
x Quarry 1 (Q1) – Chwarel Fawr;
x Quarry 2 (Q2) – Chwarel Cefn Du;
x Quarry 3 (Q3) – Cook;
x Quarry 4 (Q4) – Ddol;
x Quarry 5 (Q5) – unnamed (known locally as ”Film Set Quarry”);
x Quarry 6 (Q6) – Glyn Rhonwy;
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x Quarry 7 (Q7) – unnamed; and
x Quarry 8 (Q8) – former WWII munitions store (known locally as “the bombstore”).
1.6.2 The Development utilises Q1 and Q6.
The Development
1.6.3 Pumped storage projects comprise of seven main elements:
x A headpond - upper reservoir;
x A tailpond - lower reservoir;
x A power house - containing the combined pump/turbines;
x A penstock - the pipe connecting the headpond to the power house;
x A tailrace - the pipe connecting the power house to the tailpond;
x Pumping station; and
x Spillway infrastructure – a discharge point from the headpond and a joint discharge/abstraction point from the tailpond.
1.6.4 The Development at Glyn Rhonwy comprises of the following permanent features:
x one headpond (Q1), its dam, access shaft and spillway to the Nant Y Betws;
x one tailpond (Q6), its dam, access shaft and spillway to Llyn Padarn;
x a pumping station at Llyn Padarn;
x a power house at Glyn Rhonwy Industrial Estate Platform 5 (south of Q6) with an underground turbine hall housing turbines with an electrical output of up to 99.9MW;
x a penstock (connecting Q1 to the power house); and
x a tailrace (connecting the power house to Q6).
1.6.5 The Development also incorporates temporary features such as temporary construction compounds and lay down areas at Q1 and Q6.
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1.6.6 Further details are provided in ES Chapter 4 Project Description and section 4 of this NTS.
1.7 The Planning Framework
1.7.1 The Department for Energy and Climate Change (DECC) has published a number of National Policy Statements (NPSs) in relation to energy infrastructure. These NPSs set out national policy against which proposals for NSIPs are assessed and determined. The DCO application for the Development will be determined in accordance with these policies.
1.7.2 The NPS of principal relevance to the proposed Development is the overarching NPS for Energy (NPS EN-1). This was published in 2011 and sets out national policy for energy infrastructure as defined by the Act. NPS EN-1 provides the primary basis for decisions on energy projects by the SoS. Consideration is also given to the NPS for Renewable Energy Infrastructure (2011) (NPS EN-3), and the NPS for Electricity Networks Infrastructure (2011) (NPS EN-5).
1.7.3 NPS EN-1 states that consideration may be given to planning policy outside the NPSs where it is important and relevant to the SoS's decision. Other national, regional and local planning policies have therefore been considered in the preparation of the ES as these may be relevant to the determination of the proposed DCO Application, including:
• Planning Policy Wales (PPW) (7th Edition, July 2014);
• Technical Advice Notes (TANs);
• Minerals Technical Advice Notes (MTANs) (2009)
• People, Places, Futures: The Wales Spatial Plan Update (July 2008);
• Mon a Menai Strategy Programme (2008)
• Gwynedd Unitary Development Plan (2009)
• Gwynedd Local Planning Authority Supplementary Planning Guidance: Development Brief Caernarfon Dependency Catchment Area
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• Emerging Anglesey and Gwynedd Joint Local Development Plan (Deposit Plan, 2014) and
• Glyn Rhonwy Development Plan and Implementation Strategy
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2 APPROACH TO EIA & CONSULTATION
2.1 Introduction
2.1.1 Environmental Impact Assessment (EIA) is the process of compiling, evaluating and presenting environmental information about the likely significant environmental effects of a Development. The assessment is designed to help produce an environmentally informed project. The early recognition of likely significant adverse environmental effects enables appropriate mitigation (e.g. measures to avoid, reduce or offset significant adverse effects) to be identified and incorporated into the design of a project; or what measures will be taken to protect the environment during construction and operation.
2.1.2 The EIA provides the decision maker and interested parties with information about the likely significant environmental effects of the project and proposed mitigation to assist with the determination of relevant applications.
Scoping
2.1.3 Scoping is a process which seeks to identify a suitable approach to the EIA based on the best information available at the time that a scoping opinion is sought.
2.1.4 The scope of the ES submitted with the DCO application has fully considered the conclusions of the 2012 ES, the conditions attached to the planning permission for the approved scheme and also the ongoing discussions with statutory consultees.
2.1.5 During early consultation with the statutory consultees and PINS, the Applicant sought to agree a scope directly with the statutory consultees, namely Gwynedd Council (GC), Natural Resources Wales (NRW), Welsh Government (WG), CADW, Snowdonia National Park Authority (SNPA) and Gwynedd Archaeological Planning Service (GAPS). Therefore, a letter setting out the proposed scope of the EIA for the Development was
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submitted to these parties on the 12th November 2015. In response to this letter, initial comments were provided by SNPA, NRW and GC. Following this initial dialogue, it was agreed with those parties that a formal request for a scoping opinion would be made to the SoS.
2.1.6 A request for a Scoping Opinion was submitted to the SoS on 5th January 2015, accompanied by a Scoping Report. The Scoping Report outlined which environmental topics were to be covered by the EIA and how the assessments were to be undertaken. The Scoping Opinion from PINS on the 13th February 2015 and is contained within ES Volume 3, Appendix 2.4.
Draft ES / Preliminary Environmental Information Report (PEIR)
2.1.7 As part of the statutory pre-application consultation for the Development under s47 of the Act, a Draft ES (February 2015) was prepared as Preliminary Environmental Information (PEI) and made available to consultees and the public during formal statutory consultation which commenced on 12th February 2015. The Draft ES presented the information gathered to date and provided the draft results of technical assessments as to the likely significant environmental and social effects, both positive and negative, of the construction, operation and decommissioning phases of the Development.
2.1.8 The Draft ES was sent either electronically or in hard copy to all identified s42 consultees on the 12th February 2015. Consultees were then given a minimum of 28 days to respond with any comments on the Development (which finished on the 13 March 2015). It was also available for viewing at a number of locations in the vicinity of the Development and at the public exhibitions held on the 27th and 28th February 2015. Full details of the consultation activities can be found in the Consultation Report (Document 5.01) and in the Summary of Consultation Report (Document 5.01.1).
2.1.9 The Preliminary Environmental Information Report (PEIR) is an intermediate step in the EIA process as required under the Act, and provides environmental information compiled by the Applicant at the time of publication, to enable consultees to develop an informed view of the Development. The PEIR assesses the likely environmental effects of the
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Development and identifies potential approaches to mitigation based on the environmental and social data collated at the time of publication, and outlines whether further assessment needs to be carried out.
2.1.10 Feedback received during the pre-application consultation process has helped to inform the detail of the Development and to further refine the EIA. The full results of the technical studies are provided in the Final ES, which accompanies the DCO application.
EIA
2.1.11 In accordance with EIA regulations, the EIA process for the Development incorporates the following main steps:
x Production of a Scoping Report to identify the likely significant effects (scoped in) and the proposed methodology for their assessment in line with relevant legislation, guidance and methods, and justification for any significant effects that are not likely (scoped out). The Scoping Report sought agreement of study areas, data sources, survey methodologies and terminology;
x Baseline surveys are undertaken to identify and describe the environmental character of the area that could potentially be affected by the Development. Where baseline data indicates major constraints to the Development, this information is to be provided to the design team immediately;
x Relevant natural and manmade processes that may change the character of the site are identified;
x Consideration is then given to the possible interactions between the Development and both existing and future site conditions. These interactions or impacts are assessed using set criteria based on accepted guidance and good practice;
x Using the initial designs of the Development, the likely significant environmental effects, both direct and indirect, can be established;
x Production of a Preliminary Environmental Information report for consultation purposes:
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x Recommendations are made to avoid, minimise or mitigate adverse effects and enhance positive effects. Alterations to the design will then be reassessed and the significance of likely residual environmental impacts ascertained; and
x Following statutory consultation, the results of the EIA in combination with the responses to the Scoping Opinion will be set out in an ES that will accompany the application for a DCO.
2.1.12 Feedback received during the previous consultation process in connection with the approved scheme and the ongoing pre-application consultation through the DCO process has helped to inform the design of the Development and the findings of and commitments made in the EIA.
2.2 Consultation
2.2.1 Effective pre application consultation is an important requirement of the Act, which requires applicants to consult with both technical (Section 42) and community (Section 47) consultees.
2.2.2 The Applicant has engaged in pre-application consultation with a number of statutory consultees, namely PINS, GC, GAPS, CADW and NRW, prior to the submission of the DCO. Table 2.1 outlines the meetings which have been held:
Table 2-1 Record of Meetings Date Attended by Issues discussed 15th October Gwynedd Council Intention to apply for DCO 2014 1st December Gwynedd Council DCO workshop including 2014 & Cadw discussions about the changes in red line boundary 2nd December Gwynedd Council, PINS site visit plus follow up 2014 NRW, PINS meeting with GC and NRW regarding introduction to the project and DCO process. Minutes taken. 22nd January NRW To discuss SI works and HRA 2015 Screening 9th March 2015 PINS To discuss progress on the DCO 26th March 2015 Horizon Nuclear To discuss cumulative effects Power 26th March to 16th NRW, GC & Informal meetings during
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Table 2-1 Record of Meetings Date Attended by Issues discussed July Gwynedd preliminary GI works. Archaeological Trust 30th March 2015 NRW & Gwynedd To discuss s42 responses from Council Gwynedd Council and NRW. NRW provided a formal response on the agenda and both parties also provided comments on the UXO report. Minutes taken. 15th May 2015 PINS To discuss progress on the project and draft DCO documentation 15th July 2015 NRW and To discuss results of the breeding Gwynedd Council bird and aquatic ecology surveys, UXO and amends to project description. Minutes taken. 16th September PINS To discuss progress on the 2015 project and draft DCO documentation
Public Consultation
2.2.3 Consultation with local people, businesses and organisations is also an essential part of the DCO process and has helped to influence the final designs of the Development.
2.2.4 Full details of the consultation that has been undertaken by SPH in connection with the Development are provided in the Consultation Report (Document 5.01) which records the consultation undertaken and its conclusions, in particular how it has influenced the Development and the Application.
2.2.5 Over 200 people attended the public exhibitions held on the 27th February 2015 in Caeathro and 28th February 2015 in Llanberis. Over 640 individual items of feedback from 639 unique correspondents were received as part of the s47 consultation.
2.3 Approach to Assessing the Significance of Effects
2.3.1 The following approach provides an overview of the assessment methodology. However, within individual technical chapters in the ES, the
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approach may differ due to topic-specific guidance, policies and legislation. Where this occurs, the variation in methodology is explained clearly and fully.
2.3.2 The determination of the significance of the likely environmental effects arising from the Development is a key stage in the EIA process. In order to assess the significance of an impact, it is necessary to establish the sensitivity or value of the receiving environment or receptor and the magnitude of the impact occurring, i.e. the scale, duration etc of the change to the existing conditions as a result of the Development. Assessment of significance for individual environmental topics will typically combine professional judgment with consideration of a number of factors:
x The sensitivity of the resource or environmental feature (known as 'a receptor') under consideration;
x The magnitude of the impact in relation to the degree of change which occurs as a result and whether the effect is temporary, permanent, and/or reversible.
2.3.3 Other factors include the type of effect, i.e. whether it is adverse, beneficial, neutral or uncertain; and the probability of the effect occurring based on the scale of certain, likely or unlikely.
2.3.4 The sensitivity of the baseline conditions is assessed according to the relative importance of existing environmental features on or near to the site, or by the sensitivity of receptors, which would potentially be affected by the Development. Table 2-2 lists the criteria for the determination of the sensitivity or value of receptors are established based on approved guidance, legislation, statutory designation and/or professional judgment.
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Table 2-2: Criteria for determining sensitivity of receptors Sensitivity Definition Very High The receptor has little or no ability to absorb change without fundamentally altering its present character, is of very high environmental value, or of international importance. High The receptor has low ability to absorb change without fundamentally altering its present character, is of high environmental value, or of national importance. Medium The receptor has moderate capacity to absorb change without significantly altering its present character, has some environmental value or is of national importance. Low The receptor is tolerant of change without detriment to its character, is low environmental value, or local importance. Negligible The receptor is resistant to change and is of little environmental value.
2.3.5 The magnitude of potential effects on environmental baseline conditions is identified through consideration of the Development taking into account the scale or degree of change from the existing baseline as a result of the effect. Consideration is given to the duration and reversibility of the effect as well as consideration of relevant legislative or policy standards or guidelines. Table 2-3 provides a general definition for determining the magnitude of a particular effect.
Table 2-3: Criteria for determining the magnitude of a particular effect Magnitude Definition High Total loss or major alternation to key elements / features of the baseline conditions such that post development character / composition of baseline condition will be fundamentally changed. Medium Loss or alteration to one or more key elements / features of the baseline conditions such that post development character / composition of the baseline condition will be materially changed. Low Minor shift away from baseline conditions. Changes arising from the alteration will be detectable but not material; the underlying character / composition of the baseline condition will be similar to the pre-development situation. Negligible Very little change from baseline conditions. Change is barely distinguishable, approximating to a “no change” situation.
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2.3.6 The general approach adopted in the assessment of significance, as it relates to sensitivity and magnitude, is outlined in Table 2-4 below. A combination of the magnitude of the impact under consideration and the sensitivity of the receiving environment determines the significance of effect. For some specialist topics, additional categories have been added where a greater level of definition is required. It should be noted that this general approach is a framework only, the significance of an effect is assessed on a case-by-case basis.
Table 2-4 Approach to Assessment of Effects
Magnitude Sensitivity
Very High High Medium Low Negligible
High Major Major Moderate Moderate Minor
Medium Major Moderate Moderate Minor Negligible
Low Moderate Moderate Minor Negligible Negligible
Negligible Minor Minor Negligible Negligible Negligible
2.3.7 The significance of the effects arising from the Development have been reported using a seven-point scale, as follows:
x Major Adverse, Moderate Adverse, Minor Adverse;
x Negligible; and
x Major Beneficial, Moderate Beneficial, Minor Beneficial.
2.3.8 Effects predicted to be Minor are considered to be manageable and such effects are considered to be ‘Not Significant’. Effects assessed as Moderate or Major are considered to be 'Significant'. When the residual significance of impacts is assessed this takes into account mitigation, i.e. the assessment applies to the residual effects of the project, which can be defined as any impact that would remain following the implementation of proposed mitigation measures.
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2.4 Structure of the ES
2.4.1 The ES reports the findings of the EIA and ensures that decision makers such as the SoS and statutory consultees such as planning authorities, in this case GC, as well as other interested parties, including local communities, are aware of a development’s environmental effects so that these may be considered before a decision is taken on whether or not the development should be approved.
2.4.2 The ES also contains a series of technical assessments which have assessed the potential for likely significant effects during the construction, operation and decommissioning of the Development. The scope of these technical assessments was presented within the Scoping Report submitted to PINS on the 5th January 2015 and consultation with interested parties and statutory consultees has shaped the scope of these assessments. Further detail on consultation can be found in Chapter 2 Approach to EIA & Consultation of the ES.
2.4.3 The structure of the ES is as follows:
x Introductory chapters including the approach to the EIA and consultation, the design evolution, the main alternatives considered, the project description, and planning policy (Chapters 1-5);
x Landscape Character and Visual Amenity(Chapter 6);
x Ecology (Chapter 7);
x Geology & Ground Conditions (Chapter 8);
x Water Resources (Chapter 9);
x Flood Risk (Chapter 10);
x Archaeology & Cultural Heritage (Chapter 11);
x Traffic & Transportation (Chapter 12);
x Noise and Vibration (Chapter 13);
x Air Quality (Chapter 14);
x Socio-economics (Chapter 15);
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x Environmental Management (Chapter 16);
x Cumulative Effects (Chapter 17); and
x Schedule of Mitigation (Chapter 18).
2.4.4 Additional documentation has been submitted with the ES as follows:
x Statement in respect of statutory nuisance (Document 5.02);
x European site appropriate assessment report, otherwise known as a Habitat Regulation Assessment (HRA) (Document 5.03);
x Details of other consents and licenses (Document 5.04); and
x Code of Construction Practice (CoCP) and associated management plans (Volume 3, Appendix 16.1).
2.4.5 The CoCP is the document that brings together all the construction phase mitigation measures proposed for the Development. It covers the management of a Principal Contractor’s (PCs) activities and those of any Sub-Contractors, and defines the minimum requirements that have to be met. It identifies the procedures required to minimise the impact of construction activities for the Development. It includes details of measures to be employed to ensure that no pollution incidents occur, that impacts on protected species / designated sites are minimised as far as possible, that archaeological features are identified and recorded, and that impacts on nearby residents are kept to an absolute minimum.
2.5 Cumulative and In-Combination Effects
2.5.1 The effects of the Development have been assessed in combination with two other developments in the vicinity of the Order Limits (i.e. ‘cumulative effects’). Consideration has been given to the Wylfa C New Nuclear Power Station and the Caernarfon to Bontnewydd bypass, but only in relation to socio-economic and traffic and transportation effects due to the distance between the Developments.
2.5.2 The effects of the Development on shared receptors have also been assessed (i.e. ‘combined effects’).
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2.5.3 In-combination effects (where two effects which are not significant could combine to result in a potential cumulative effect which is significant) have also been considered as part of the EIA and are discussed within each chapter of the ES (and summarised in Chapter 17 Cumulative Effects) and in Section 5 of this NTS.
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3 DESIGN EVOLUTION AND ALTERNATIVES
3.1 Surrounding Environment
3.1.1 The Development is located approximately 1.5km north west of Llanberis and 11km south east of Caernarfon, as shown in Figure 1.1 of the NTS. It is located on the slopes of Cefn Du, centred at National Grid reference SH 56268 60660.
3.1.2 The site is located within, and in close proximity to, environmentally designated sites; Llyn Padarn to the east is a Site of Special Scientific Interest (SSSI), as shown in Figure 3.1.
3.1.3 The Development site itself is within a Landscape Character Area (LCA) (designated for its historical landscape) and also within Dinorwig Landscape of Outstanding Historical Interest, as shown in Figure 3.2.
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3.1.4 The site is located approximately 1km outside of Snowdonia National Park (SNP), this is shown in Figure 3.3.
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3.1.5 The Development site encompasses a series of disused quarries, the Glyn Rhonwy Industrial Estate platforms and an area adjacent to Llyn Padarn, all within the boundary of GC. This is shown in Figure 3.4.
3.1.6 The Development covers an area of approximately 91.24ha.
3.1.7 The site’s physical characteristics include a number of quarry pits, slate tips, a mature plantation woodland, rough grazing land and road network leading to Glyn Rhonwy Industrial Estate platform in the south and off the A4085 in the north. Ffordd Clegir separates two of the lower quarries and also forms the western boundary of the Glyn Rhonwy Industrial Estate. This is shown in Figure 3.4.
3.1.8 Water has collected in two of the quarries. Bathymetric surveys undertaken in Q6 have recorded the depth at approximately 17m. Q1 is estimated to be approximately 7m deep.
3.1.9 The slopes around the quarries are built up with slate waste and interspersed with the remains of outhouses and quarry workings, scattered over grazing land. The neighbouring land is mainly agricultural, although
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there is an industrial estate between Glyn Rhonwy and Llyn Padarn, an area of commercial forestry to the south west, and a large industrial complex to the south of the site towards Llanberis.
3.1.10 A former World War II munitions store (Q8) is not included within the Order Limits but is within close proximity to the Development.
3.1.11 Several Public Rights of Way (PRoW) cross the Order Limits in addition to Ffordd Clegir (translated as Clegir Road) which bisects the quarry system. Several individual properties are located on Ffordd Clegir with the nearest properties approximately 400m away in Clegyr and Pen-draw. Additional dwellings and properties are located approximately 1-2 km to the north west of the Order Limits in Gallt-y-Celyn, Pen-y-Bwlch and Bwlch. The settlement of Waunfawr is located approximately 2 km to the west of Q1 and the main centre of Llanberis located approximately 1.5km from Q6. Further detailed information is provided in Chapter 4 Project Description of the ES.
3.1.12 Although development of the Glyn Rhonwy industrial site has provided improved access – including public access – access to the site is restricted by locked gates and the quarries themselves are fenced off. The site is used for informal (unauthorised) leisure activities and there is evidence that forced access has been gained. Some quarries and buildings including the Industrial Estate itself have been known to suffer vandalism in the form of tipping, graffiti and damage to the fencing, which has facilitated (unauthorised) access.
3.2 Design Evolution
3.2.1 The Development has evolved in two principal stages. The first design evolution related to the approved scheme, with the second evolution taking place following the grant of permission for the approved scheme in advance of the submission of the DCO. This was in response to the Electricity Market Reform which meant that the approved scheme was unlikely to be deliverable with an output capacity of 49.9MW and that an increased capacity would be required.
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Approved Scheme - Review 1: Initial Design prepared for report to accompany formal Scoping Request to Gwynedd Council (November 2011)
3.2.2 The initial design was based upon technical requirements of the pumped storage scheme together with development constraints including proximity to residential dwellings and designated sites, and incorporated three dams at Q1, Q2 and Q6 with heights of 12m, 26m and 17m above ground level (AGL) respectively. An alternative option was considered which comprised an increase in the height of the dam at Q1 to 15m AGL, thereby avoiding the need for a dam at Q2, and a reduced dam height at Q6 of 8m AGL.
3.2.3 The overland penstock route was to be routed on the northern side of the Cook (Q3) and Dhol (Q4) quarries to avoid protected birds. The penstock would be up to 2000m long with two 2.5m diameter pipes.
3.2.4 The power house was to be located on the western side of Ffordd Clegir in Q5. The location of site compounds and access tracks was undetermined.
3.2.5 The use of Llyn Padarn as a tailpond was considered but was discounted on the basis that it is designated as a SSSI and is a popular recreational destination. The scheme at Design Review 1 is shown in Figure 3.5 below
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Approved Scheme Review 2: Engineering review following survey works (April 2012)
3.2.6 The principal change as part of Design Review 2 was the removal of the dam at Q2. The engineering review identified the potential to provide approximately 1,100,000m3 of storage in Q1 meaning that the three dams initially proposed were not required. In addition, the engineering review also identified that significant engineering and geotechnical stabilisation works would be required at Q2 and Q5, in addition to the ecological constraints identified in Q5. As a result, dams were only required at Q1 (headpond) and Q6 (tailpond) which would be 25m above ordnance datum (AOD) and 15m AOD high respectively.
3.2.7 The proposed location of the power house was moved (from the munitions store) to Platform 5 of the Glyn Rhonwy Industrial Estate.
3.2.8 Two penstock / tailrace construction methods to transfer water from Q1 to Q6 were still being considered at this stage – one above ground and one below ground. Design Review 2 is shown in Figure 3.6 below.
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Approved Scheme - Review 3: Review following stakeholder consultation (July 2012)
3.2.9 It was determined that the penstock for the approved scheme should be constructed by underground tunnel excavation. The route, established at Design Review 2, would be used, albeit along a more direct underground route between Q1 and Q6. The open cut construction option was discounted following consultation with regulators.
3.2.10 The location of the spillway pipe from Q6 to Llyn Padarn was still subject to landownership discussions, specifically related to the bombstore (Q8). A location for the pumping station was identified at a small inlet adjacent to the public car park.
3.2.11 It was agreed that the excess material excavated from Q1 and Q6 would stay onsite and be landscaped into the existing spoil mounds at Q1, to avoid any adverse effects from transportation offsite through Waunfawr.
3.2.12 The scheme at Design Review 3 is shown in Figure 3.7 below.
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Approved Scheme - Review 4: Final design for planning approval (August 2012)
3.2.13 The construction method for the penstock was confirmed as underground tunnel excavation, removing the need for any above ground excavation.
3.2.14 Two dams were proposed; one at Q1, approximately 25m above existing ground levels and 510m long (at the longest point), and a second at Q6, approximately 15m above existing ground levels and 215m long (at the longest point). The power house for the approved scheme was located on Platform 5 of the Glyn Rhonwy Industrial Estate.
3.2.15 The location of the pumping station was confirmed as being at National Grid ref SH 57250 61192 on the banks of Llyn Padarn due to the deeper water and minimal effect on the car parking areas in this location.
3.2.16 The location of the spillway was confirmed as being to the south and south east of Q8, outside of the bombstore, and therefore reducing the impact on the former munitions store. The scheme at Design Review 4 (the approved scheme) is shown in Figure 3.8 below
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DCO Development - Review 5: Engineering Review to increase output capacity to 99.9MW (December 2014)
3.2.17 It was confirmed that the output capacity of the Development could be increased to 99.9MW without any substantial changes being made to the principal elements of the approved scheme. The main changes included:
x More powerful turbines with a combined output capacity of 99.9MW located within the underground turbine hall. The turbine hall remained the same size as the approved scheme;
x If required, additional noise attenuation for the turbines was proposed to comply with any limits set by a DCO Requirement (as per planning conditions for the approved scheme); and
x A minor increase in the number of construction based deliveries to bring the larger turbines and associated infrastructure on to site. As the additional deliveries would have been to Q6, it was predicted that the A4086 road infrastructure would accommodate the slight increase in construction delivery traffic (particularly as the planning conditions relating to traffic mitigation and management for the approved scheme were to be reflected in DCO Requirements).
3.2.18 The Order Limits proposed for the Development at this stage comprised an area of 59.3ha which reflected the size of the redline boundary for the approved scheme, as shown in Figure 3.8 in this NTS.
DCO Development: Review 6: Design Review for report to accompany formal Scoping Request to SoS (January 2015)
3.2.19 The Order Limits around Q1 were increased to allow for construction activities around the new excess slate mounds to the south and an area to the north to accommodate potential quarry wall re-profiling.
3.2.20 The area around and including Q1 is registered as Common Land, so an application will be made to deregister the parts which will be permanently affected and fenced off. The land north and south of the penstock corridor and west of the Q1 construction compounds was identified as replacement land in terms of being a similar quality, size and access. The land was
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included in the Order Limits as land negotiations had not been concluded at the time; this was to ensure that powers could be sought under the DCO to compulsorily acquire rights over / ownership of this land if required. An additional area was also included for a potential replacement road to the power house.
3.2.21 The Order Limits around the penstock were widened to 114m to allow for flexibility in the underground penstock route due to the potential for dolerite intrusions which may be present.
3.2.22 The Order Limits were also extended to allow for flexibility in the location of the pumping station and its working area. The pumping station was still proposed to be constructed in the manner outlined in the 2012 ES (i.e. sunken design with a control box / kiosk above ground). The depth of the spillway infrastructure into Llyn Padarn remains 5m beneath the water level – this depth was previously agreed with the Countryside Council for Wales (CCW) (now NRW) as it would avoid any potential effects to Arctic Char by being above the thermocline, and also to recreational users.
3.2.23 As a result of the design review, the Order Limits increased from 59.3ha to 91.73ha. This was included within the Draft ES and is shown in Figure 3.9.
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DCO Development - Review 7: Engineering Review (February – March 2015)
3.2.24 Subsequent to the issue of the Draft ES (February 2015) as part of the consultation period, the Applicant undertook a final review of the temporary and permanent PRoW diversions required in connection with the DCO. This identified a need to extend the Order Limits by approximately 6ha to a total of 97.77ha, this is shown in Figure 3.10.
3.2.25 During the formal consultation period, the Applicant continued to carry out survey work of the land within the Order Limits. This included a full topographical survey of the access route to Q1 (Green Road) and the laser mapping of the Q1 and Q6 voids to prepare a more extensive and accurate picture of the site’s topography. Localised topographical surveys around the quarries were also completed to supplement the digital terrain and LiDAR mapping previously undertaken for the entire site.
3.2.26 In addition, the preliminary GI works were also being undertaken at this time. However the results of these investigations did not affect the Order Limits.
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DCO Development - Review 8: Final Design for DCO Application (August 2015)
3.2.27 Since the issue of the Draft ES in February 2015, a final series of further changes have been made to the Development design and the Order Limits. These have been made in response to comments received through the formal consultation process, and to also reflect a reduction in the extent of land take required for the DCO. Changes to the Development design have also occurred as a result of the extensive mapping and data collection exercise. The overall land area within the Order Limits was reduced to 91.24ha. Further details of the amendments made at this design review stage are provided below.
Increase in Storage Capacity
3.2.28 Since the submission of the Draft ES, the mapping of the quarry voids has identified the potential to increase the storage capacity from 1,100,000m3 to up to 1,300,000m3. This increase in potential storage capacity does not materially change the Development as consulted on in February 2015. Both GC and NRW were informed of this capacity change in a meeting held on the 15th July 2015.
3.2.29 The increase in reservoir capacity will deliver an increase in energy generating capacity from 600MWh to up to approximately 800MWh. The overall output capacity of the Development remains at up to 99.9MW (as the increased storage capacity will allow the facility to operate for a longer time period).
3.2.30 It must be noted that the increased storage capacity has not been achieved through any changes to the overall size of the dams or the above ground buildings (such as the power house). It is purely a result of the greater volume of the reservoirs being confirmed which increases the length of time the scheme can operate at its maximum output of 99.9MW.
Changes to Material Volumes
3.2.31 The detailed topographic and digital mapping survey also identified that whilst the void at Q1 is larger than previously estimated, Q6 is smaller than
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originally estimated. At Q6, this is due to the presence of a number of geological intrusions below the surface of the water identified through the bathymetric survey - these intrusions will need to be removed to create the reservoir at Q6. In order to provide the equivalent storage capacity in Q6 as Q1, up to approximately 650,000m3 of screened unsuitable material will need to be moved from Q6; all suitable virgin material will be used for the construction of the Q6 dam.
3.2.32 SPH therefore undertook a design review, under which alternative storage areas for spoil material were considered. It was considered that any potential storage would potentially have an adverse visual effect and be in closer proximity to residential dwellings and private water supplies. In addition, the lack of available space to store the excess material permanently in the vicinity of Q6 rendered this option unviable.
3.2.33 In full recognition of the previous commitment not to transport excess material through Waunfawr, it is therefore proposed that the excess material not utilised in the construction of the Q6 dam will be transported through the penstock with a conveyor. Excavation of the penstock utilises a conveyor for removal of excavated material, and this conveyor will be connected to run the full penstock length between Q6 and Q1 to carry material. This material will then be deposited within the proposed slate mounds at Q1.
3.2.34 The material excavated from Q6 will result in an increase in the volume of the slate mounds at Q1 from up to approximately 690,000m3 to up to approximately up to 935,000m3. However, the slate mounds still remain in the same orientation as approved previously and as per the photomontage of Viewpoint 2 Moel Eilio (see Volume 4 Figure 6.4b). The excess slate mounds will occupy a slightly larger footprint than previously proposed, but will remain 4m away from the nearest public right of way (and their associated permanent diversions), 10m away from the Nant Y Betws and 2m away from the Order Limits boundary in any other non-constrained areas. The use of detailed terrain data has confirmed that there is sufficient space to accommodate this increase and the landscape and visual impact assessment has confirmed that there are no additional effects.
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Changes at Q6 and Pumping Station
3.2.35 To enable the construction of the potential bifurcation valve, a secondary temporary access shaft and access tunnel will be sunk to enable excavation. This will be in addition to the main turbine shaft and tailrace but will not be used during operation and so will be removed after construction.
3.2.36 Whilst there was no change in the Order Limits, the location of the pumping station was moved further back from Llyn Padarn to an area of vegetation adjacent to the main car park. A secondary alternative location is also being investigated and is subject to ongoing discussions with utility companies regarding easements. This alternative location is immediately adjacent to the toilet block in front of the access to the bombstore. The DCO Work Plans have accounted for this flexibility should the secondary option be feasible from an easement and engineering perspective.
3.2.37 The scheme at Design Review 8 (the Development subject to the DCO application) is shown in Figure 3.11 below.
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3.3 Rochdale Envelope
3.3.1 As the Development has evolved since the grant of planning permission for the approved scheme, further investigation into the proposed engineering design has been undertaken. In light of this, sufficient flexibility has been built into the DCO to allow for the final design to reflect the most appropriate construction techniques identified for the delivery of the Development. This flexibility may be required to address unexpected constraints, such as ground conditions and alternative construction methods.
3.3.2 As certain aspects of the Development still require design flexibility, the DCO application, and therefore the EIA, is based on the application of maximum and, where relevant, minimum parameters or limits of deviation. These include the tunnelling method, the height of dams, the location of the pumping station, the horizontal and vertical alignment of the penstock, and the internal configuration of the power house. In light of this, it was necessary for the technical assessments to assess an ‘envelope’ within which the works will take place.
3.3.3 To remain in accordance with the EIA regulations it is essential that the parameters are as ‘“limited” as possible to ensure that the ‘likely significant effects’ are identified, rather than unrealistically amplified effects, which could be deemed to be unlikely. It was proposed to use maximum and minimum parameters for the Development in each relevant technical assessment.
3.3.4 The final Rochdale envelope parameters are provided in Table 4-1:
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Table 4.1 – Rochdale Envelope Parameters Area Description Maximum elevation of dam of 395m AOD to crest Plan width 150m and length 371m Q1 Max volume of 1,300,000m3 Max water level 392m AOD Excess Spoils Max combined volume of 935,000m3 Mounds To be tunnelled within 114m buffer and between a maximum elevation of 330m AOD to a minimum depth of 55m AOD Penstock Up to 1600m long within Order Limits (plan length) but potentially up to 1800m to allow for any underground deviations, and 4.5m internal diameter Tailrace Up to 160m long Tailrace, 4.5m internal diameter Maximum elevation of 156m AOD Plan width 95m and length 210m Q6 Max volume of 1,300,000m3 Max water level 154m AOD Power House 15m high to apex x 27m wide x 60m long Two underground turbines with maximum electrical output of up to Turbine Hall 99.9MW Volume of excavation approximately 100,000m3 Switchgear 10m high to apex x 18m wide x 30m long Transformer 7m wide x 7m long x Assumed to be 10m high 12m high to apex x 12m wide x 30m long GIS Substation Gas Insulated Pumping 1.6m high x 2m long x up to 0.8m deep Station
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3.4 Alternatives
Engineering Alternatives
3.4.1 Throughout the design evolution, alternatives have been considered. These are outlined in detail in Sections 3.6 – 3.7 of the Final ES and are summarised below:
x The use of Llyn Padarn as the tailpond – whilst the potential optimal solution in terms of engineering, this was discounted early in the scheme development due to its highly sensitive, environmental, ecological and social importance;
x An alternative to the movement of material offsite through Waunfawr resulted in the creation of the excess slate mounds and internal conveyor from Q6;
x The underground excavation of the penstock was confirmed on the basis of significantly adverse visual, environmental and archaeological effects from an open cut alternative;
x Routing of the underground penstock to avoid any potential geotechnical instability issues from drilling under existing slate mounds and close to quarries contained highly sensitive and protected ecological features; and
x Placement of the discharge outlet into Llyn Padarn above the thermocline to avoid any potential effects on the Arctic Char.
Alternatives to the site at Glyn Rhonwy
3.4.2 As required by the Overarching National Policy Statement for Energy (EN- 1) and as advised by the SoS in Section 2.56 of his Scoping Opinion (February 2015) consideration has been given to alternatives to the Development as proposed in the DCO application. The following section details why SPH selected the Glyn Rhonwy site for the Development over other potential locations.
3.4.3 The technologies, plant and construction methodologies to be used, where definable at this stage of the development process, are detailed within the following section in this NTS and ES Chapter 4 Project Description.
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Alternative construction methods and technologies to those assessed in the ES were considered; however, they have not been carried forward or selected for the final design for various reasons, typically due to their engineering inefficiency and non-compliance with best practice guidelines.
3.4.4 Sites suitable for pumped storage are limited by the need for specific physical characteristics. Importantly, pumped storage requires at least two or more quarries or reservoirs where water can be released from a high to a low elevation. An initial source of water is also required and sites need to be reasonably close to existing electrical connections.
3.4.5 The feasibility study work undertaken by the Applicant for the development of pumped storage included a detailed mapping exercise undertaken to examine the feasibility of pumped storage throughout Great Britain, against key indicators including:
x the geology, ground conditions and terrain;
x accessibility;
x safety and feasibility of construction;
x the physical shape and sizes of the reservoirs and requirements for dams;
x the distance between the reservoirs and the distance to the transmission grid;
x the environmental sensitivity of the site; and
x whether any impacts of the development could feasibly be designed out or mitigated.
3.4.6 This exercise identified a number of locations where pumped storage is considered feasible, including Glyn Rhonwy. However, Glyn Rhonwy was identified as a highly suitable location for pumped storage for several reasons:
x There are two quarries separated by a large height difference but geographically close to each other;
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x The local geology of the Llanberis Welsh Slates formation is a reasonably impermeable seam, the use of which has already been proven by the Dinorwig Pumped Storage facility; and
x The site is only 7km from a connection point to the electricity network, which, given the other critical criteria, is considered to be relatively close.
3.4.7 The Gwynedd Unitary Development Plan (UDP) (2001 - 2016) specifically identifies pumped storage (Policy C27) as a suitable use on the previously developed land at Glyn Rhonwy Redevelopment Site (Policy C6).
Do Nothing Scenario
3.4.8 Pumped storage provides fast response energy in times of peak demand. Without this ability to rapidly respond to peak demand the UK would rely increasingly on baseload thermal power stations and inflexible forms of renewable energy, such as wind, to provide energy whether it is required or not. This would lead to significant inefficiencies and unnecessary green house gas emissions through unnecessary burning of fossil fuels.
3.4.9 NPS EN-1 supports the use of technologies such as pumped storage under the classification of “electricity storage” to provide back up to an energy market increasingly supplied by less predictable renewable energy sources. Section 3.3.12 of NPS EN-1 states
‘There are a number of other technologies which can be used to compensate for the intermittency of renewable generation, such as electricity storage, interconnection and demand-side response, without building additional generation capacity. Although Government believes these technologies will play important roles in low carbon electricity system, the development and deployment of these technologies at the necessary scale has yet to be achieved. The Government does not therefore consider it prudent to solely rely on these technologies to meet demand without the additional back-up capacity. It is therefore more likely that increasing reliance on renewable will mean that we need more total electricity capacity than we have now, with a larger proportion being built only or mainly to perform back-up functions.’
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3.4.10 There are limited sites across the UK which are deemed suitable for pumped storage. Making use of the Glyn Rhonwy site to provide electricity storage capacity will make an important contribution to the delivery of a low carbon electricity system in the UK, as outlined in NPS EN-1. In a ‘Do Nothing Scenario’, this contribution would not be made.
Project Optimisation
3.4.11 This EIA assesses the worst case scenario by making reasonable assumptions based on current knowledge and engineering design. The engineering design has been undertaken and refined where possible based on the information gained to date and there will be elements which will be subject to detailed design and further site investigation works.
3.4.12 However there is also the potential for opportunities within the design for engineering improvements and optimisation. These are indentified as follows:
x Turbine Shaft - The turbine shaft as shown in ES Volume 4, Figure 4.11 is considered the maximum extent of excavation. However the turbine shaft can be optimised by excavating two smaller individual shafts or a thinner single shaft opening into a larger underground turbine hall. Therefore the assessment has been made on the worst case engineering option.
x Material to be excavated - The volume of material to be excavated has been derived using a bulking factor of 1.6. This is considered to be a conservative assumption and any lesser value would be considered an improvement.
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4 PROJECT DESCRIPTION
4.1 Development Overview
4.1.1 The Development will cover an area of 91.24ha. The Development consists of the following components:
x one headpond (Q1), its dam, access shaft and spillway infrastructure to the Nant Y Betws;
x one tailpond (Q6), its dam, access shaft and spillway infrastructure to Llyn Padarn;
x a pumping station at Llyn Padarn;
x a power house at Glyn Rhonwy Industrial Estate Platform 5 (south of Q6);
x a penstock (connecting Q1 to the power house); and
x a tailrace (connecting the power house to Q6).
4.1.2 Q8 does not form part of the Development but will be in close proximity to the Order Limits. This is shown in Figure 4.1 of this NTS.
4.1.3 Q7 is included within the Order Limits due to some localised reprofiling which may be needed around Q7 for the construction of the Q6 dam and continuation of the existing access road to the upper platforms. A retaining wall will be built to maintain structural integrity for the road. It is proposed not to infill or enter Q7 other than to seal connecting tunnels.
4.1.4 The following sections provide a description of the key components of the Development, construction methods and programme. These sections also highlight the status and progress of certain elements of the design including those that are subject to detailed design or those that have a lesser degree of flexibility. Working areas are allocated as per the submitted Works Plans (Document 2.04).
4.1.5 The Development is illustrated in Figures 4.1 to 4.16 within Volume 4 of the Final ES, and on the indicative plans, elevations and sections submitted as
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Documents 2.05 and 2.06. These drawings provide an indication of the Development proposed based on the parameters assessed within this ES.
Headpond – Q1
4.1.6 The headpond will be formed at Q1 by the construction of a dam across the south western side of the quarry. The headpond will have an approximate volume of 1,300,000m3 of water. The dam will have a maximum elevation of 395m AOD. The normal maximum operational water level is 392m AOD. The overflow level is 393m AOD which provides up to 1m of freeboard for operating water level fluctuations before any overflow (spilling) would occur. A further 2m of freeboard above the overflow is provided, primarily for wave action.
4.1.7 Externally, the dam will be landscaped using slate and profiled so as to appear similar to the slate mounds which surround the existing quarries. It is likely to have a slope of between 1:1 and 1:2 although this is subject to detailed design and agreement from the Construction Engineer appointed under the Reservoirs Act.
4.1.8 To make the quarry safe and operable as a reservoir, stabilisation and lining of the quarry may be required, once access has been made by battening platforms into the quarry sides.
4.1.9 Stabilisation works will include the remodelling and reprofiling of the current quarry edges to remove the fractured rock face and provide a smoother operational surface. The use of rock anchors in appropriate locations to stabilise the quarry sides will be undertaken as required. The quarry may also need to be lined to reduce or prevent water loss through natural seepage.
4.1.10 A freestanding combined overflow and relief valve outlet structure (or draw- off tower) will be constructed adjacent to the Q1 dam and within the reservoir. The overflow is provided in case of failure of the pump system or cessation of generation which would result in natural filling of the reservoir. The relief valve outlet (also commonly known as the 'scour' and shown on drawings as such) provides a means of draining the reservoir to the level of the base of the dam if required in an emergency situation.
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4.1.11 The spillway infrastructure to the Nant Y Betws will consist of two pipes – one 800mm diameter drainage pipe and a 400mm diameter scour pipe which will be within an enclosed spillway infrastructure channel.
Tailpond – Q6
4.1.12 The tailpond at Q6 will be formed by the construction of a dam across the north eastern end of the quarry following stabilisation and access works to make the quarry operationally safe and functional. The dam will have a maximum elevation of 156m AOD. Q6 would also hold a maximum volume of up to 1,300,000m3 of water. The maximum normal operational water level is 154m AOD. The overflow level is 154.5m which provides up to 0.5m of freeboard for operating water level fluctuations before any overflow (spilling) would occur. A further 1.5m of freeboard (above the overflow) is provided, primarily for wave action.
4.1.13 In a similar construction method to Q1, the dam at Q6 may potentially be lined and stabilised. The extent of the stabilisation works at Q6 may affect the existing slate mound to the north of Q6, hence why this precautionary approach to the extent of the Order Limits.
4.1.14 A freestanding combined overflow and relief valve outlet structure (or draw- off tower) will be provided within the Q6 reservoir. This would generally operate as per the overflow and relief valve (or ‘scour’) tower in Q1. The relief valve outlet or scour pipe also acts as a rising main for water abstraction from Llyn Padarn to Q6.
Removal of Water within the Quarries
4.1.15 Both Q1 and Q6 hold water within the existing quarry voids. Bathymetry surveys estimate a depth of 7m in Q1 and 17m in Q6. Water sampling for determining water quality has been undertaken within the quarries and more details are provided in ES Chapter 9 Water Resources.
4.1.16 Water in Q1 will be pumped out and discharged to Nant Y Betws. If required, the water will be passed through settlement lagoons and / or a ‘Siltbuster’ (or similar) to minimise the discharge of suspended solids. There is up to approximately 100,000m3 of water within Q6 which will be pumped
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out to the adjacent Llyn Padarn via a temporary pumping main. The rate and volume of any discharges will be undertaken in line with the required Environmental Permit.
Excavation of the Quarries
4.1.17 Approximately 550,000m3 will be excavated from Q1, most of which is expected to be utilised within the dam construction. Approximately 360,000m3 will be excavated from Q6, with approximately 90,000m3 to be utilised in the dam construction.
Stabilisation Works
4.1.18 The sides of the existing quarries Q1 and Q6 are potentially unstable and require stabilisation to allow the safe construction and operation of the reservoirs. Where rock excavation is required then stable slopes will be formed using controlled blasting, with localised remedial works as required. In other areas, stabilisation works will include the remodelling and reprofiling of the current quarry sides to form stable rock faces, excavation will either be by machinery or by controlled blasting or by a combination of these two methods.
4.1.19 Due to a combination of geological variations and previous quarry workings, Q1 will be stabilised by reprofiling. The south eastern side is to be retained as far as possible with any loose material removed.
4.1.20 Stabilisation works on the northern side of Q6 may have the potential to infringe on the existing slate mound further to the north of Q6. Detailed site investigation works will confirm if this existing mound is stable and also if any stabilisation works have the potential to affect it. Should stabilisation be required this would be achieved by removing the spoil mound area which could be at risk and temporarily relocating this to another area within the existing slate mound. Once stabilisation works are complete the area will be regraded and landscaped.
4.1.21 Other methods of stabilisation potentially include the following:
x Removal – removal or scaling of individual features;
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x Containment – localised containment using rock netting or rock traps (these can be permanent or temporary fences, ditches or stand-offs);
x Strengthening – localised reinforcement using rock anchors, bolts or dowels; and
x Support or protection – localised support using retaining walls, buttresses, sprayed concrete or anchored beams.
Unexploded Ordnance (UXO) & Sediment Remedial Works
4.1.22 There is documented evidence of the lower quarries being used historically for military bomb storage and disposal. The bombstore (Q8) was abandoned after the roof collapsed during World War II, but has been subsequently remediated by the former Welsh Development Agency. There are records of ordnance being disposed of in Q6 and also of a later remediation operation in the 1970s by the Ministry of Defence. However, there is the potential for unexploded ordnance (and also spent ordnance scrap) to be present in and around Q6. As part of the development, a recorded Ordnance Management Strategy will be undertaken in full consultation with the appropriate authorities in relation to any potential unexploded ordnance (UXO).
4.1.23 A UXO report is contained within ES Volume 3, Appendices 8.5 and 8.6 which provides further details, with an assessment contained within ES Chapter 8 Geology & Ground Conditions.
4.1.24 Sediment collection from Q1 and Q6 was attempted in May 2015, however, no discernible samples were collected due to the absence of any significant depths of sediment. Once drained, should there be any sediment at the base of the quarries, this will be tested and investigated for UXO and contamination. Depending on the level of potential contamination present or ordnance found, this will be remediated as, and if, required. It is not proposed to remove any contaminated sediments from the Development.
Quarry Lining Works
4.1.25 For the base of the quarries, one of the following two methods is intended to be employed (to be confirmed at detailed design):
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1. An impermeable High Density Poly-ethylene (HDPE) liner will be constructed in the base of the quarry. A sub-lining drainage system would be required to collect and discharge any leakage and groundwater. This will comprise of the following elements:
x Landforming of the base;
x A sub-lining drainage system;
x Underlying and overlying regulating layers;
x Impermeable liner;
x Overlying protection geotextile fleece; and
x Cover or protection layers.
This would prevent uplift pressures occurring during drawdown of the pond in generation and would allow the detection of leakage through the base; or
2. Pressure grouting of the base will be undertaken through boreholes in the base of the quarry. The grout would fill in any fractures within the rock mass and therefore reduce permeability.
4.1.26 It is likely that pressure grouting using cementitous grout will be the most appropriate method for the quarry side slopes. The requirement for side slope grouting will be confirmed by permeability testing following detailed site investigation works as part of the enabling stage.
Dam Footprints
4.1.27 The dams will be founded on sound bedrock. This requires any superficial deposits and existing quarry spoil to be removed prior to dam construction. The elevation of the bedrock profile is likely to be variable and will only be confirmed following stripping of the existing quarry spoil. Because of the difference between existing ground level and bedrock level, the roots of the dam will extend underground until they meet bedrock. Ground levels will be restored to at or about the existing ground levels (or as otherwise agreed) around the edges of the dams.
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Wave Action and Protection
4.1.28 The dams will have a concrete wave wall running along the crest that the upstream impermeable membrane will be tied into. Depending on the type of impermeable membrane used (i.e. if an HDPE geo-membrane is used), surface protection to the upstream face of the dam may be required through the placement of a layer of selected rock, able to resist wave action. This will be underlain by protective and regulating layers between the membrane and a gradation of materials comprising sand through to crushed rock.
Penstock & Tailrace
4.1.29 The penstock is a pipe which will convey the flow of water between the headpond and power house (and vice versa). The tailrace (or 'draft tube') is a pipe which will convey water from the power house to Q6 (and vice versa). The penstock will include a bifurcation in the approach to the power house, this is shown in Figure 4.1 of the NTS. These will both be tunnelled.
4.1.30 The penstock will be approximately 1600m long, stretching from Q1 to Q6 (as shown on Figure 4.1) and have an approximate internal diameter of 4.5m. The length may deviate to a total length of 1800m dependent on ground conditions.
4.1.31 The proposed excavation method is to use either a Tunnel Boring Machine (TBM) or drill and blast. However due to the presence of potentially doleritic intrusions within the bedrock, drill and blast may be used, or a combination of the two approaches. This will be confirmed upon instruction of a Principal Contractor (PC).
4.1.32 The outlet from Q1 is at an elevation of approximately 335m AOD (approximately 50m below current ground levels). Where the penstock enters the shaft for the turbine hall at the power house it is at an elevation of approximately 60m AOD (approximately 90m below current ground level) It should be noted that the elevation of the penstock may change underground during detailed design of the scheme dependent on the ground conditions and particular technical requirements, including the pump-turbines selected. Construction of the penstock is likely to take up to 12 months.
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Power House
4.1.33 The power house is an above ground building with offices, plant hall, crane(s), workshop, welfare facilities and a control room. This building is approximately 15m high to its apex, 60m long and 27m wide. The power house straddles the shaft that contains the turbine hall which houses the turbine-pumps and generators.
4.1.34 It is likely to be faced and roofed in slate but the final external design and appearance will be subject to a DCO Requirement. It is expected that the power house will be manned by up to approximately 35 people during normal operation. The turbine hall will house turbines with a combined net output capacity of 99.9MW. Due to the depth of the turbine hall, specialist heavy equipment will be needed to lift the turbine and associated infrastructure into position at depth.
4.1.35 The power house is also likely to contain the switchgear equipment which is required to connect the Development to the electricity network.
Pumping Station
4.1.36 The pumping station is required so that water may be abstracted from Llyn Padarn into Q6 in order to fill up the Development as part of the commissioning process and also to 'top up' levels, or discharge any excess water, during operation. The pumping station will only be operational when water is required to be pumped from Llyn Padarn into the Development and will not be operational when water is discharged to Llyn Padarn.
4.1.37 In response to consultation responses, the location of the pumping station has been located away from the edge of Llyn Padarn, within an area of vegetation adjacent to the car park. A secondary location is being investigated further back towards the existing toilet block and is subject to ongoing discussions with utility providers.
4.1.38 The pumping station will comprise of a below ground wet well, valve chamber and cable pit, and above ground control box / kiosk. The majority of the structure is below ground and can be located so as to avoid any areas normally used by users of the car park and lagoon area.
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4.1.39 The pumping station size will depend on the final location but will be completely underground and located at depth. A small above ground control box would be present and this is likely to be approximately 2m long by 1.6m high by up to 0.8m deep and would resemble a communications control box, most likely covered in British Standard 14-C-39 Green (subject to DCO Requirement). A manhole cover and grid plate is also required to gain access to the pumping station for maintenance purposes.
4.1.40 There would be no operational requirement for fencing around the control box and no operational lighting. The underground pumping station will be equipped with sufficient acoustic attenuation to minimise any disturbance above ground.
Spillway Infrastructure
4.1.41 The spillway infrastructure contains an overflow from Q6 which will be connected to Llyn Padarn directly with an approximately 800mm diameter pipe. The spillway infrastructure also contains a combined scour and rising main as a separate pipe approximately 450mm in diameter.
4.1.42 The spillway infrastructure will be culverted under the Q6 dam and will be buried in an opencut trench for the full route to the pumping station and then to Llyn Padarn. The indicative route around the south side of the bombstore, and across the A4086, to the pumping station (which is bypassed by the overflow and relief or scour outlet) and then to Llyn Padarn is shown in Figure 4.1 of the NTS.
4.1.43 Valving will allow the relief or scour to discharge direct to Llyn Padarn (bypassing the pumping station). The purpose of the overflow is to discharge excess water collected within the reservoir(s) during operation. The purpose of the scour is to allow drawing-down of the water level in the reservoir to the base of the dam, including in an emergency situation. Any relief or overflow discharges will be gravity fed.
4.1.44 As part of the 2012 ES, it was agreed that spillway infrastructure would be screened to avoid any impacts to fish, be located above the thermocline, approximately 5m below the minimum recorded water survey level to avoid impacts to protected fish species, Arctic Charr, and impacts to recreational
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users. Surface buoys would mark the location of the pipe terminals. There will be a fine mesh screen on the pipes to prevent any wildlife, detritus or material from entering the pipe.
4.1.45 As it will be at depth, the working environment will be sheet piled to ensure a safe, water tight environment for the installation of the spillway infrastructure. This will be approximately 5m x 20m.
4.1.46 Where the spillway infrastructure enters Llyn Padarn through the tree line, the working width will be minimised as much as possible to minimise any impacts to tree root systems. A tree survey will be undertaken prior to construction commencing to microsite the pipe through this area. Any trees that are removed will be subject to mitigation measures outlined in the Habitat Management Plan (HMP).
4.1.47 Where construction enters Llyn Padarn, access around this immediate area will be temporarily restricted to maintain a safe environment to the users of Llyn Padarn. This is expected to last up to 12 weeks.
4.1.48 There are potentially two options for the construction of the spillway infrastructure into Llyn Padarn, as follows:
Option 1
4.1.49 Using the coffer dam area, as outlined above, the pipes will be “strung out” and sunk in place with pre-cast concrete weights.
4.1.50 Once the pipe is laid and the dry area reflooded, reinstated and coffer dam removed, access will be allowed. It is expected that this element of the construction of the pumping station and spillway infrastructure will be short and temporary in nature. It is paramount that the health of safety of the construction is managed correctly due to the nature of the works.
Option 2
4.1.51 A smaller coffer dam would be used but a small boat or barge would then be used to string out the pipes and then connect to the onshore pipework once the pipe is sunk using pre-cast concrete weights. Access to this area would again be temporarily restricted whilst these works are ongoing to maintain the health and safety of users and construction workers.
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4.1.52 Detailed information on the construction method is contained with section 4.6 of Chapter 4 Project Description of the ES.
Commissioning
4.1.53 Once the pumping station and spillway infrastructure is in place, pressure testing will be undertaken. This will be a temporary occurrence and last a few weeks. Once the Q6 reservoir is ready to receive water, the abstraction from Llyn Padarn will commence.
4.1.54 On the basis of 1,300,000m3 required, this will take 394 days on the basis of 3300m3 per day. An abstraction license has been granted on the basis of 1,100,000m3 and a variation to this license will be submitted to NRW prior to the start of the Examination in relation to the1,300,000m3 volume.
Programme
4.1.55 It is proposed not to work within the summer school holidays to minimise any significant adverse effects to users of Llyn Padarn and the lagoons. Outside summer school holidays, it is proposed to construct the overflow and pumping station sequentially to minimise any disturbance to users of Llyn Padarn and the lagoons. A small construction compound may be required but access for cycle and vehicle users on the shore will not be impeded, where necessary diversions will be implemented. It is not proposed to block off or sever any existing routes for Llyn Padarn users but some traffic management will be in place during critical activities.
4.1.56 There is no requirement for night time lighting during construction outside working hours other than for security purposes.
Electrical Connection
4.1.57 The Development will be connected to the electricity distribution system network via a new electrical connection. This will be exported from an onsite substation to an offsite connection terminating at Pentir. This is shown on Figure 4.2 of the NTS
4.1.58 This is likely to be a 132kV connection, which as associated development in Wales, will not be consented under the Act. It may be possible to complete the works under SP Manweb’s permitted development rights, or through the
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formal grant of planning permission under the Town and Country Planning Act 1990. Any application for the appropriate consents will be made by SPH, an Independent Connection Provider (ICP) or SP Manweb as appropriate. A high level cumulative assessment has been undertaken on the indicative route and this is assessed in ES Chapter 17 Cumulative Effects. This assessment is based on the current grid connection agreement which was applicable at the time of submission.
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4.1.59 SPH has committed to this connection being provided underground and the current grid connection offer being discussed with SP Manweb seeks an underground connection.
4.1.60 The switchgear building is adjacent to the power house and is also likely to be faced and roofed in slate. The final building materials and finishes will be subject to a DCO Requirement. The substation will contain 11kV and 400V electrical distribution equipment and will measure approximately 10m high, 18m wide and 30m long.
4.1.61 The external transformer compound will have provision for a single 11kV/400V transformer and two 11kV/132kV transformers for the 132kV electrical connection. Only the building required to house the substation equipment will be included within and authorised by the DCO.
Permanent Excess Slate Mounds
4.1.62 Up to two excess slate mounds will be created south of Q1 with a volume of up to 935,000m3. This will consist of a new slate tip to the south of the existing mound, and an extension to the existing mound.
4.1.63 Material will be generated from the excavation of the Q1 and Q6 quarries to form the headpond and tailpond reservoirs. This material will be crushed and graded with only suitable material utilised in the construction of the dam(s), with less suitable material used for landscaping purposes or incorporated into the new excess slate mounds south west of Q1.
4.1.64 Excess material generated at Q6 will be transported by a conveyor within the completed penstock for placement within the excess slate mounds.
Access
4.1.65 Access to Q1 will be via the existing unclassified road (known as the Green Road) from the A4086 and through Waunfawr. Upgrades will be made from the A4086 to the Q1 site compound with temporary access tracks from the compound to the quarry. These upgrades are classed as associated development and so will be subject to a planning application to Gwynedd Council. Based on dialogue with the Council to date, the road will retain its single track status with several passing places being constructed for vehicle
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movements. The improvements to Green Road will be undertaken before construction and then fully reinstated to adoptable road standards once construction is complete. Further detail can be found in ES Chapter 12 Traffic and Transportation.
4.1.66 Access to Q6 will be through the existing road network off the A4085 to within the existing Glyn Rhonwy Industrial Estate. Minor amendments may be made to the A4085 and Industrial Estate junction for delivery of plant and materials during construction although these will be reinstated post- construction, unless their retention is agreed with the Highways Authority.
4.1.67 Ffordd Clegir, which runs between Q5 and Q6, will not be used for any construction or operational traffic, although it may be subject to a temporary closure for health and safety reasons on critical activities. Advance notice will be given to the local residents, appropriate signage provided on the road, and approval of GC as Highways Authority will be gained prior to any works commencing.
4.2 Construction Phase
4.2.1 The construction phase is expected to last approximately 4 years from commencement of works. Table 4-1 outlines an indicative simplified programme of the Development. Please note that several activities have been incorporated together which in reality will be distinctly separate in the programme. A PC has not yet been appointed, and so it is envisaged that the following indicative construction sequence will be followed.
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Table 4-1 Indicative Construction Programme Phase Location Activity Year 1 Year 2 Year 3 Year 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 Enabling Works Q1 & Q6 Offsite access road improvements, creation of replacement temporary car park Establish construction compounds including fencing and security. Onsite general Mobilisation (and potential GI works) and site clearance Dewatering Q1 & Q6 Dewatering of quarries Reservoir Works Q1 Access made to quarry floor and reprofiling including blasting, drilling, lining, excavation and rock bolting and grout curtain construction Partial removal of existing spoil mounds and crushing of excavated materials Construction of dam Construction of scour tower, overflow / relief valves and spill, inlet / outlet works and chambers Placement of excess material in new slate mounds Construction of spillway infrastructure to Nant Y Betws Q6 Access made to quarry floor and reprofiling including blasting, drilling, lining, excavation and rock bolting and grout curtain construction Partial removal of existing spoil mounds and crushing of excavated materials UXO Remedial works Construction of dam and placement of excess material Construction of scour tower, overflow / relief valves and associated pipework, inlet / outlet works and chambers Fill reservoir from abstraction and rainfall Pumping Station Llyn Padarn Construction of spillway infrastructure to Llyn Padarn and pumping station Penstock Penstock Sink launch shaft from platform 5 Construction Excavation of penstock, bifurcation value and chambers Line tunnel Conveyor Setup and movement of material from Q6 to Q1 Power House Platform 5/6 Sink turbine shaft and construction of tailrace Glyn Rhonwy Lining works and fit out shaft infrastructure Industrial Construct power house superstructure, including crane and fit out power house Estate Install turbines and electrical infrastructure below ground and above ground. Test and commission De-mobilisation Q1 & Q6 Removal of site compounds and equipment from site. Reinstatement of access road improvement works.
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4.2.2 Site preparation and enabling works will be required prior to commencement of the main construction phase. These include:
x Highway improvements to be completed;
x PRoW diversions to be implemented;
x Potential secondary ground investigation (GI) works; and
x Mobilisation to site and establishment of temporary compounds.
4.2.3 Temporary construction buildings and laydown areas will be required. These will be located within the Order Limits and consist of offices, meeting rooms, a car park, storage and laydown areas for construction equipment and vehicles, and welfare facilities for workers. The indicative location of these temporary features is shown in Figure 4.1 of the NTS.
4.2.4 A variety of standard construction plant and equipment will be required as part of the construction activities and these include (but are not limited to):
x Low loaders – for delivery of plant and equipment;
x Moxy – dumper trucks for transportation of materials internally in quarries and externally to storage areas;
x Wheeled and tracked 360 Excavators - for excavations works;
x Mobile crushing and screening plant;
x Bulldozers;
x Graders;
x Compaction plant; and
x Cranes.
4.2.5 Other machinery and equipment may include, but not be limited to::
x Concrete batching plant;
x Welfare units and portacabins;
x Pipework (in sections);
x Temporary fencing;
x Generators (at Q1 for electrical supply unless locally available); and
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x Bowsers.
4.2.6 Should TBM be used as the penstock excavation method, this will be brought to site in a modular fashion on the back of a low loader.
4.2.7 The 2012 ES proposed a Construction Environmental Management Plan (CEMP) which the PC will be required to operate under. This has evolved into a CoCP submitted in support of the DCO Application. It will implement the mitigation measures identified within the 2012 ES, the planning conditions attached to the T&CPA permission for the approved scheme, and any additional measures identified in the ES. Further details are found in Chapter 16 Environmental Management of the ES.
4.2.8 Construction working hours will be 07:00 – 19:00 Monday to Friday and 07:00 – 13:00 Saturday. Where construction activities are required outside these hours, then this will be undertaken only with the prior approval of GC.
4.2.9 The number of construction staff on site will vary according to the construction phase and activities being undertaken, and will be confirmed by the PC upon instruction. However it is expected that up to 250 people will be employed during the construction phase at its peak, after which it will then generally decrease as construction is progressed through to the commissioning phase. However, this will be subject to the requirements of the PC and therefore could change.
4.2.10 Security lighting will be required within the Development during construction, especially on the temporary compounds and storage areas. This lighting will have due regard to nearby residential properties and sensitive habitats and species. Workplace lighting at the onsite temporary compounds will have due regard to UK guidelines on construction lighting, namely Health and Safety Executive guidance HSG38 Lighting at Work and also Bat Conservation Trust Statement on the Impact and Design of Artificial Light on Bats (May 2011).
4.2.11 Access around the two working areas and the existing and diverted PRoWs will be maintained during construction wherever possible to recreational and common land users. The car park at Q1 will be temporarily relocated near the temporary PRoW diversion so that these links can still be used.
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4.2.12 Temporary closures of the PRoWs may occur and access to land may be controlled during certain times in the construction phase for critical path activities such as blasting or drilling. This is due to health and safety for users, residents and the onsite workers. Appropriate signage will be deployed on all PRoW diversions and the appropriate notice provided for any closures.
4.2.13 In addition, the two working areas around Q1 and Q6 will have 24 hour security to prevent public access with appropriate fencing, signage, lighting and CCTV installed. There will no workers villages or overnight accommodation at either temporary compound during construction. The only 24 hour attendance will be security.
4.3 Operational Phase
4.3.1 The indicative operational lifespan of the Development is 125 years. The Development will have continuous operation throughout its lifecycle except for planned maintenance.
4.3.2 SPH estimate that approximately up to 35 people will be employed during the operational lifetime of the Development to perform operational and maintenance tasks. Therefore, operational traffic is limited to staff travel and delivery of ancillary materials and plant during the Development lifespan.
4.3.3 As per the construction phase, the operational lighting strategy will have due regard for residents, ecology and health and safety. It is proposed that this is agreed as part of a DCO Requirement.
4.3.4 Once the Development is fully commissioned with 1,300,000m3 of water, this will pass between Q1 and Q6 in order to provide the battery storage and generate electricity at peak times.
4.3.5 Operational discharges will be intermittent and dependant on rainfall and operational requirements. An essential component of any raised reservoir is the ability to lower the water level behind the dam (draw-down); emptying the reservoir to the point where there is no hydraulic load on the structure. For the purpose of reservoir safety this facility must be available at all times.
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4.3.6 At times of normal operation, the main and primary mechanism for draw down for the Q1 reservoir is through the penstock to Q6. The penstock pipe has the capacity to provide draw-down of the reservoir in approximately 7 hours at a rate in the order of 46 m3/s. This is more than adequate to serve the draw-down need for the Q1 reservoir.
4.3.7 At times of normal operation, the main and primary mechanism for draw down for the Q6 reservoir is through the penstock to Q1, using the turbines in the turbine house in pumping mode. However, because of the variables in operation and maintenance of the scheme, and the need to have a draw- down capacity at all times; it is considered prudent to include a facility to lower the reservoir independent of the penstock and powerhouse.
4.3.8 Therefore both dams provide a secondary method for draw down, with water being discharged to the Nant y Betws at Q1 and to Llyn Padarn at Q6. This will only occur if the penstock is unavailable. The relief valves are sized to allow the reservoir(s) to be drawn down to 50% of the volume impounded by the dam(s) within 7 days. These discharges would be controlled through the required discharge consent.
4.3.9 The relief valves are manually activated i.e. they will only be opened when the operator intervenes. Such intervention will only take place in one of two scenarios as follows:
a) when the there is a need to lower the water level behind the dam and the water cannot, for whatever reason, be drawn down through the penstock i.e. it would only be in an unusual situation when drawdown of the reservoir is required and this cannot be achieved through the penstock.
b) for maintenance; to ensure the valves are operational as part of the dam safety regime, it will be necessary from time to time to briefly operate the valves.
4.3.10 In short, emergency valve operation is considered an extremely unlikely situation and, other than infrequent small amounts for valve testing, are not part of the normal operation of the scheme and would be very unlikely, possibly never, in an unplanned situation.
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4.3.11 In the maintenance scenario (b above) the discharge would be managed as per the requirements of the discharge consent. In this scenario, the valve can be used in a controlled manner, when the flows in Nant-y-Betws and the Afon Gwyrfai are low enough to accept the flows from the reservoir without causing an increased risk of flooding from the watercourses.
4.3.12 No water is directly discharged into Llyn Padarn from the turbines.
4.4 Decommissioning
4.4.1 For the purposes of the EIA, it is assumed that decommissioning may occur after an indicative 125 year operational lifespan. The implications of decommissioning will be reviewed once it is evident the plant is approaching the end of its working life.
4.4.2 At the end of the 125 year operational life, the Development will be decommissioned:
x Assessment of any buildings that are to be removed, including ecology;
x Removal of all above ground structures, notably the power house;
x Water will be drained from Q1 to Q6 and released at an agreed rate and timescale through the appropriate licensing regime into Llyn Padarn;
x Pumping station will be removed, although the overflow pipework at Q6 will remain in situ after being sealed;
x Dams and access tracks to remain in situ;
x Security fences will remain although access through the dam structures will be secured;
x Penstock pipework between Q1 and Q6 will remain in situ and sealed; and
x Overflow pipework at Q1
4.4.3 It is proposed that due to the anticipated lifespan of the Development, a Decommissioning Plan will be required by the relevant authorities at the point of decommissioning this Development. This will therefore be a Requirement of the DCO.
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5 SUMMARY OF ENVIRONMENTAL IMPACT
ASSESSMENT
5.1 Introduction
5.1.1 The ES identifies the key environmental topics that have been assessed as part of the formal EIA process. These are as detailed in Section 2.3 of this NTS.
5.1.2 For each assessment topic, the ES describes the proposed approach to assessment, provides existing information on the local environment (the environmental ‘baseline’ of the surrounding area), and describes the potential effects on that environment during construction, operation and decommissioning.
5.1.3 The environmental topic areas reported on in the ES are summarised below.
5.2 Landscape Character and Visual Amenity
5.2.1 Chapter 6 of the ES contains an assessment of the landscape and visual effects of the Development. The LVIA has been informed by the production of a Zone Theoretical Visibility (ZTV) map for the quarry dams and slate tips, which was undertaken for the 2012 ES.
5.2.2 Based on the ZTV, 12 representative viewpoints were agreed with Gwynedd Council (GC), Environment Agency Wales (now NRW) and Snowdonia National Park Authority (SNPA) as part of the 2012 ES. These 12 viewpoints have been used in the ES for the DCO, in order to present views of the Development in the landscape. The ‘worse case scenario’ is defined as the views from the most sensitive landscape and visual receptors with the highest visibility of the Development. The ZTV and locations of the 12 viewpoints can be seen in Figure 5.1 of the NTS. A number of photomontages were produced for these viewpoints, showing the Development as it will look when operational. These are shown in Volume 4, Figures 6.4a to 6.4l of Volume 4 of the ES.
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5.2.3 The landscape and visual effects have been assessed during the construction, operation and decommissioning stages with respect to:
x Landscape elements within the Development;
x Landscape designations and the Snowdonia National Park;
x LANDMAP aspects areas (geological, habitats, visual and sensory, historic and cultural);
x Views (visual amenity).
Effects during Construction
5.2.4 Construction elements and activities will have an adverse effect on the landscape around Llanberis and the Snowdonia National Park. This effect is however limited by the screening of the surrounding hills. Construction will affect views from Moel Eilio, the Llanberis Lake Railway, Cefn Du and Dinorwig. Screening by vegetation and the limited disruption on the underlying character or focus of the view mean these effects of the Development are limited.
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Effects during Operation
5.2.5 The visual amenity of walkers using Cefn Du will be moderately adversely affected by the permanent dam at Q1.
5.2.6 Mitigation measures have been integrated into the design as far as reasonably possible through excavation of the penstock rather than open trench pipe route; layouts to minimise the effects on vegetation; the reinstatement of landforms and vegetation and the use of natural screening to avoid direct views from sensitive viewpoints onto material storage and the power house. Permanent features and structures such as the power house will be clad with local materials, and dams and excess spoil mounds will use slate waste excavated on site to soften their features. Stone walls will be reinstated wherever necessary and fencing at Q1 and Q6 will be chosen to reflect existing fencing types.
Effects during Decommissioning
5.2.7 Decommissioning effects will be temporary and of a short duration. The elements of the Development to be removed at the decommissioning stage are described within ES Chapter 4 Project Description. The lifespan of the development is such that the landscape will have evolved during the 125 years and an appropriate restoration strategy will need to be developed reflecting the future character and visual amenity of the landscape. It is not considered that the landscape and visual effects during decommissioning would be greater than the residual effects assessed (in the LVIA) during summer year 15.
Conclusions
5.2.8 There will be No Permanent Significant effects on the LANDMAP Aspects, LCAs or landscape designations within the study area.
5.2.9 There will be a permanent Significant adverse residual effect on receptors at Viewpoint 7 (Cefn Du) due to the close proximity of the viewpoint to the dam and reservoir at Q1.
5.2.10 No Significant residual visual effects have been identified for the remaining viewpoints. This is due in part to the limited visibility of the components of
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the Development in the wider study area, with much screening provided by the topography of the study area and wooded nature of the area immediately surrounding the site. The mitigation measures proposed as an inherent part of the Development, notably the use of existing slate, will successfully integrate the development into the landscape context, further reducing its potential visual prominence.
5.3 Ecology
5.3.1 Chapter 7 of the ES contains an assessment of the effects of the construction, operation and decommissioning of the Development on sensitive ecological receptors.
5.3.2 To assess the current ecological conditions at the Development site, the following surveys and assessments have been undertaken:
x Consultation with the County Ecologist and NRW;
x Desk based study to identify sites of nature conservation and protected and priority species in the surrounding area;
x Extended Phase I Habitat Survey (which is a habitat classification study) for the majority of the Order Limits;
x Assessment of Bat Potential;
x Winter/Hibernation and Summer Bat surveys;
x Reptile Surveys;
x Amphibian survey;
x Great Crested Newts Habitat Suitability Assessment;
x Breeding Bird Habitat Suitability Assessment;
x Breeding bid surveys;
x Winter bird surveys;
x Badger surveys;
x Otter surveys;
x Invertebrate Habitat Suitability Assessment;
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x Habitat Regulations Assessment – Stage One: Screening;
x Freshwater surveys in Q1 and Q6 for diatoms, phytoplankton, invertebrates, fish and aquatic plants;
x Aquatic plant surveys for floating water plantain, spring quillwort and Canadian/Nuttall’s pondweed;
x National Vegetation Classification (NVC) Survey;
x Fungi and lichen surveys; and
x Arboricultural Assessment.
5.3.3 Further details are provided in the ES Chapter 7 Ecology and its accompanying appendices in Volume 3 of the ES.
Effects during Construction
5.3.4 The Development will have a permanent residual minor adverse effect on Llyn Padarn SSSI through the potential very small loss of lake bed habitat due to the pipe line connection to the lake bed. The effect on Llyn Padarn SSSI is deemed to be Not Significant.
5.3.5 The Development will have a permanent residual minor adverse effect on Bwlch-y-Groed Quarry Local Wildlife Site (LWS) through the loss of 9.0ha (21.9%) low value habitat due to the construction of the spoil heaps and Q1 dam. The effect on Bwlch-y-Groed Quarry LWS is deemed to be Not Significant.
5.3.6 The Development will have a permanent residual minor adverse effect on Coed Donen Las LWS and Llwyn Coed Heath LWS through the loss of 10.7ha (16.1%) and <0.001ha (0.001%) respectively of low value habitat due to the construction of the Q6 dam. The effect on both the LWS’s is deemed to be Not Significant.
5.3.7 The Development will have a permanent residual minor adverse effect on Pen Gilfach LWS through the loss of low value habitat to facilitate access for the construction of the pumping house and outlet pipes. The effect on Pen Gilfach LWS is deemed to be Not Significant.
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5.3.8 The Development will have a permanent residual minor adverse effect on Cefn Du LWS through the loss of 1.0ha (0.3%) low value habitat to facilitate the construction of a section of the Q1 dam. The effect on Cefn Du LWS is deemed to be Not Significant.
5.3.9 The Development will have a permanent residual minor adverse effect on broadleaved semi-natural woodland through the loss of 0.5 ha (10.7%) of habitat due to the enabling works for the provision of access to facilitate the construction of the pumping house and lake bed outfall, the construction of the pumping house, and a section of the Q1 dam. Due to the small loss of overall habitat and implementation of a CoCP, the effect on broadleaved semi-natural woodland is deemed to be Not Significant.
5.3.10 The Development will have a permanent residual minor adverse effect on coniferous woodland through loss of 8.0ha (72.7%) of negligible value habitat due to the creation of the permanent slate mounds. However, this area is managed plantation and has been subject to recent felling. The effect is therefore considered to be Not Significant.
5.3.11 The Development will have a permanent residual minor adverse effect on semi natural mixed woodland through the loss of habitat due to the enabling works for the provision of access to facilitate the construction of the pumping house and lake bed outfall. The effect on semi-natural mixed woodland is deemed to be Not Significant.
5.3.12 The Development will have a permanent residual minor adverse effect on dry heath / acid grassland through the loss of low value habitat due to the construction of the Q1 dam. The effect on dry heath / acid grassland is deemed to be Not Significant.
5.3.13 The Development will have a permanent residual minor adverse effect on standing water (oligotrophic water) through the loss of habitat due to the infilling with water of Q1 and Q6. The effect on standing water (oligotrophic water) is deemed to be Not Significant.
5.3.14 The Development will have a permanent residual minor adverse effect on the quarry habitat through the loss of habitat due to the infilling with water of
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Q1 and Q6. The effect on the quarry habitat is deemed to be Not Significant.
5.3.15 The Development will have a permanent residual minor adverse effect on the spoil habitat through the loss of negligible value habitat due to the creation of the two dams. The effect on the spoil habitat is deemed to be Not Significant.
5.3.16 The Development will have a permanent residual minor beneficial effect on the spoil habitat through the creation of approximately 8.85ha of spoil habitat. The effect on the spoil habitat is deemed to be Not Significant.
5.3.17 The Development will have a permanent residual minor adverse effect on the stone wall habitat through the loss of habitat. The effect on the spoil habitat is deemed to be Not Significant.
5.3.18 The Development will have a permanent residual minor adverse effect on the Tree Protection Order (TPO) designated area A5 through the loss of habitat. The effect on the TPO area A5 is deemed to be Not Significant.
5.3.19 The Development will have a permanent residual minor adverse effect on Arctic Charr through vibration. The effect on the Arctic Charr is deemed to be Not Significant.
5.3.20 The Development will have a permanent residual minor adverse effect on reptiles through the loss of habitat (removal of quarries, spoil, grassland, scrub and woodland). The effect on the reptiles is deemed to be Not Significant.
5.3.21 The Development will have a permanent residual minor adverse effect on the Schedule 1 of the Wildlife and Countryside Act bird species, and Birds of Conservation Concern (BOCC) Red and Amber List bird species through the loss of habitat (removal of potential nesting habitat through removal of quarries and woody habitats). Due to the availability of alternative habitat, and the timing and proximity of the construction activities of the Development. The effect on the Schedule 1 bird species, and BOCC Red and Amber List bird species is deemed to be Not Significant.
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5.3.22 Development will have a permanent residual minor adverse effect on bats from construction vibration, roost modification, loss of roosts in tunnels, isolation and fragmentation and operational lighting. The effect on the bats is deemed to be Not Significant. Development will have a permanent residual moderate adverse effect on bats from loss of tree roosts. The effect on the bats is deemed to be Significant.
5.3.23 Ecological mitigation measures are to include:
x enhancement of the existing tunnels and bat habitat to mitigate those lost as part of the Development,
x pre-construction surveys,
x the employment of an Environmental Clerk of Works,
x implementation of a Habitat Management Plan, and
x engineering solutions (such as the placement of the outlet into Llyn Padarn above the thermocline (which is a transition temperature layer between the mixed layer at the surface and a deep water layer within a water body) to avoid any adverse effects to fish, namely Arctic Charr
x proposed mitigation for bats is outlined the Bat Licence Application Method Statement.
Effects during Operation
5.3.24 Once operational, there will be a permanent loss of the quarry habitats in Q1 and Q6 but no other effects from day to day operation.
5.3.25 The Development will have a residual minor adverse effect on Afon Gwyrfai a Llyn Cwellyn Special Area of Conservation (SAC) through the alteration of the flow regime, alteration of temperature during the routine discharges, nutrient enrichment, and introduction of invasive species. The effect on Afon Gwyrfai a Llyn Cwellyn SAC is deemed to be Not Significant.
5.3.26 The Development will have a residual minor adverse effect on Llyn Padarn SSSI through the alteration of the hydrological regime, alteration of temperature during the routine discharges, nutrient enrichment, light spill,
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and pollution during routine maintenance. The effect on Llyn Padarn SSSI is deemed to be Not Significant.
5.3.27 Precautionary measures will ensure that no invasive species are transferred from Q6 into Llyn Padarn. In addition, should the water within Q6 be found to be contaminated, prior to discharge to Llyn Padarn, an Environmental Permit (EP) will be applied for and the appropriate treatment measures undertaken.
5.3.28 The Development is not expected to influence algal bloom in Llyn Padarn. Scour and wave action will be minimised by the design and siting of the outlet pipes
Effects during Decommissioning
5.3.29 The residual effects during decommissioning are likely to be similar to those identified during construction. However, due to the lifespan of the project (125 years) it is not currently possible to predict potential and residual effects on designated sites, habitats and species, as the baseline is likely to change over this period.
Conclusions
5.3.30 Implementation of the mitigation measures outlined will avoid or minimise the potential effects on the majority of the ecological receptors. The overall residual effect is assessed as minor adverse (excluding effects on bat tree roosts). Therefore the effects are considered to be Not Significant. The overall residual effect assessment on bat tree roosts only is assessed as moderate adverse. Therefore the effects are considered to be Significant in EIA terms. Mitigation measures have been incorporated in the design to minimise impacts on bats; these are outlined in the bat licence application. Other European Protected Species Licences will be applied for if required.
5.3.31 A No Significant Effects study (HRA screening assessment) was undertaken to identify what effects the Development could have on Natura 2000 sites in the surrounding area. This HRA Screening concluded that with the implementation of mitigation measures the Development will not have any Likely Significant Effects (LSE’s) on the integrity of Natura 2000
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Sites. Therefore, an Appropriate Assessment – Stage Two of the HRA process – was not required.
5.4 Geology
5.4.1 Chapter 8 of the ES contains an assessment on the geo-environmental characteristics within the Order Limits. It provides an assessment of the impacts of the Development on these characteristics during the construction, operational and decommissioning phases.
5.4.2 The study area has been set to incorporate all potential receptors that could be impacted (i.e. sensitive environments) and historical land uses that may have an impact on the Development (i.e. historical development in surrounding area, potentially contaminative permitted activities, etc).
Effects during Construction
5.4.3 The Development is not expected to adversely affect local geology or soils.
5.4.4 Slate waste, which is excavated, will be recycled into the dams at Q1 and Q6, however there will be an excess of slate waste from the Development of up to approximately 810,000m3. Approximately 650,000m3 will be derived from works at Q6 and will be incorporated into permanent slate mounds at Q1. Quarry reprofiling and general landscaping will disturb ground and there is the potential for the discovery of unidentified contaminated land or unexploded ordnance (UXO) (from previous use of part of the site as a munitions store).
5.4.5 If any residual ground contamination is discovered, this will be managed through appropriate remedial strategies developed with NRW and GC secured through a DCO Requirement.
5.4.6 An Ordnance Management Strategy will outline what happens if any unexpected ordnance or munitions are found.
Effects during Operation
5.4.7 The Development is unlikely to adversely affect local geology or soils during operation.
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Effects during Decommissioning
5.4.8 The Development is not expected to adversely affect local geology or soils during decommissioning as the dams will remain in situ.
Conclusions
5.4.9 The Development comprises the utilisation of former slate quarries excavated mainly into the Llanberis Slates Formation. Slate waste created from the works will be re-used on site as aggregate for the dams at Q1 and Q6 and in the stabilisation of slate mounds to the south of Q1.
5.4.10 The only nationally important geological feature in the area is part of the Afon Gwyfrai a Llyn Cwellyn SSSI, located to the west of the Order Limits. This includes a small exposure of a fluorite mineral working. As the location of the SSSI is upstream of the Development, this would not be affected by the Development.
5.4.11 Overall, it is concluded that effects of the Development on soils and geology will be Not Significant.
5.5 Water Resources
5.5.1 Chapter 9 of the ES contains an assessment of the potential effects of the Development on the surface water environment and water resources in the vicinity of the Development.
Effects during Construction
5.5.2 Private water supplies were identified and consulted upon as part of the 2012 ES. Due to the increase in the Order Limits, this consultation was repeated to identify any further private water supplies. The Development, however, is not expected to affect any private water supplies or water quality of the designated water bodies connected to the Development.
5.5.3 The construction phase of the Development presents a potential risk to water resources largely through the generation of runoff with high sediment loads. Pollution prevention measures would be implemented around all construction areas to prevent the direct discharge of silt laden runoff to surface watercourses. All site runoff would be directed through appropriate treatment systems before being discharged, potentially under consent from
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NRW. With mitigation measures being implemented impacts are predicted to be minor adverse with regards to Llyn Padarn and negligible for all other water bodies. Therefore this is considered to be Not Significant.
5.5.4 Good construction site management would be implemented through the CoCP to control potentially contaminative activities associated with the construction site operations. There is the potential for the accidental spillage or release of construction materials (such as cement, concrete, diesel or hydraulic fluid) directly into surface water drains and into the quarries in the vicinity of construction activities. Such materials may also become mobilised by surface runoff and eventually enter watercourses, drainage systems or groundwater and may result in a deterioration in water quality and pose a temporary minor adverse effect with regards to groundwater and all surface waters except Llyn Padarn, where a temporary localised moderate adverse effect is predicted due to its position downstream of the works and the need for works directly in the lake.
5.5.5 Water would be discharged to Llyn Padarn during the construction phase in Q6. Although there is no evidence that this water poses a risk to the lake, a programme of water quality monitoring would be implemented to determine any variations in the quality of the water discharged, and if necessary, treatment would be undertaken under an Environmental Permit and the discharge made under consent from NRW.
5.5.6 Following the completion of the works on Q6, water would be abstracted from Llyn Padarn to assist in the initial filling of the reservoir. The reservoir also would be filled through the storage of rainfall incident to the quarry and the surrounding area. A daily abstraction of 3300 m3 equates to approximately 0.00022% of the total lake volume per day or approximately a 3.4mm drawdown per day across the entire lake surface. It is considered that there would be no significant adverse effect of the abstraction on lake levels in Llyn Padarn. This is due to the hands off flow condition on the abstraction license, linked to levels in the downstream Afon Seiont. Consequently, it is considered that there would be no effect on aquatic receptors in the lake (including at its margins). Overall, the abstraction regime is not considered to have any significant impact on lake water levels
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(and therefore littoral habitat quality and extents) and/or water quality (as it is affected by changing water levels). Therefore, a negligible impact is predicted on Llyn Padarn from the short term abstraction of commissioning water and any future ‘top-up’ abstractions.
5.5.7 Precautionary monitoring at Llyn Padarn and post-construction consents and licenses regarding Llyn Padarn will be agreed in consultation with NRW. A Water Management Plan has been included within the CoCP which is found in Appendix 16.1 in Volume 3 of the ES.
5.5.8 It is concluded that with the implementation of the mitigation measures, the residual effects of the Development on water resources during the construction phase would be minor to negligible adverse and thus Not Significant.
Effects during Operation
5.5.9 During the operation of the Development, potential impacts on water resources would largely be restricted to the management of excess water from within the Development.
5.5.10 The spillway from Q6 initially would form the spillway infrastructure from Llyn Padarn to assist in the filling of Q6. The outfall will be fitted with a diffuser head to help disperse flows and avoid scour of the lake bed immediately in front of the outfall. The intake and outfall will be positioned at least 5 m below the average minimum annual water level so as to avoid impacts on lake users, and above the thermocline. Although the loss of lake bed to new structures has been minimised, in accordance with the assessment criteria a permanent moderate adverse effect is predicted. There would also be a residual effect of moderate adverse effect on the Nant-y-Betws stream due to the potential culverting of two short sections of this watercourse to provide access for the PRoW diversions.
5.5.11 The spillway infrastructure will be constructed from both Q1 and Q6 to provide a controlled discharge from the two quarries to manage excess water. It is proposed that under normal operation excess water would discharge from Q6 to Llyn Padarn, rather than from Q1 to the Afon Gwyrfai
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via the Nant-y-Betws, although the facility at Q1 would be utilised should it not be possible to use the Q6 spillway or transfer water from Q1 to Q6.
5.5.12 It is considered that a negligible effect would occur from discharges to Llyn Padarn (including bathing waters) and the Afon Gwyrfai. However, due to the smaller size of the Nant-y-Betws stream and its lower dilution potential, a minor adverse effect is predicted, despite the extremely low frequency of discharges to this watercourse - although this is unlikely due to the preference during operation to discharge from Q6 to Llyn Padarn. However, a review of available water quality data and the proposed operation of the Development does not give rise to any concerns and No Significant adverse impacts are predicted.
5.5.13 Sealing of Q6 potentially may block existing drainage pathways between the quarries. This could cause flooding in Q5, which could have adverse ecological impacts. Subject to further detailed investigations, it may be necessary to provide a water management scheme in Q5, potentially involving dewatering, to maintain an acceptable water level in Q5. Maintenance of an appropriate water level in Q5 will minimise ecological impacts and have an adverse minor residual impact on surface water flow.
Effects during Decommissioning
5.5.14 The Development is not expected to affect private water supplies or water quality of the designated water bodies connected to the Development during decommissioning. The draining of Q6 will be undertaken via the Decommissioning Plan agreed with the appropriate regulators at that time and water will be gradually released into Llyn Padarn so as not to cause any adverse effects.
Conclusions
5.5.15 As a result of the geological conditions of the area, it is considered that groundwater does not form an important contribution to regional or local water resources.
5.5.16 There are a number of private water supplies in the vicinity of the Development. As the Development will have no impact on groundwater
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flow, and the fact that Q2 and the adjacent area of the slate spoil heap will not be disturbed by the Development, it is concluded that the existing private supplies will not be affected.
5.5.17 The construction phase of the Development presents a potential risk to water resources largely through the generation of runoff with high sediment loading (potentially containing elevated levels of aluminium), the risk from chemical spillages, and in the short term from the discharge of dewaters from Q1 and Q6. Mitigation measures would be implemented around all construction areas to prevent the direct discharge of contaminated runoff to surface watercourses.
5.5.18 It is concluded that with the implementation of the mitigation measures, the impacts of the Development on water resources during the construction phase would be minor to negligible adverse and are therefore Not Significant.
5.5.19 Following the completion of construction, impacts on water resources would be limited to those associated with the effective management of excess water in the system. Excess water would be discharged from Q6 to Llyn Padarn replicating the current flows. No Significant adverse impacts are predicted.
5.5.20 New crossings for the PRoW diversions over the Nant-y-Betws and two of its tributaries, together with the diversion of one tributary would result in a permanent effect of moderate adverse significance, which is considered Significant. However these are short crossings and any effects will be temporary in nature during the short construction of the culverts.
5.5.21 The results of an assessment under the WFD have shown that the Development is compliant with the objectives of the WFD and associated proposed mitigation measures for Llyn Padarn, Afon Seiont and the Afon Gwyrfai.
5.5.22 Other than the possible need to include a water management system in Q5 and the short crossings on the Nant-y-Betws, it is concluded that the operation of the Development would have negligible impacts to water
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resources receptors other than a minor effect on the Afon Gwyrfai via the Nant-y-Betws. No Significant effects on water resources are predicted.
5.6 Flood Risk
5.6.1 Chapter 10 of the ES contains an assessment of the flood risk presented by the Development.
Effects during Construction
5.6.2 The Development will not increase the risk of local flooding resulting from construction activities. Activities and events that have been assessed as part of the Flood Consequences Assessment (FCA) include working within the floodplain, restriction of flow by mud or debris, a temporary increase in impermeable areas, fluvial flooding and flooding from overland flow and groundwater. Implementation of an Emergency Response and Flood Management Plan, incorporated into the CoCP, and the installation of temporary Sustainable Drainage Systems (SuDS) will result in negligible effects on receptors from these construction activities and events. Upon the implementation of mitigation measures, the risk of flooding is reduced to a negligible effect, and therefore Not Significant.
Effects during Operation
5.6.3 The Development will not increase the chance of local flooding. Reservoir safety design and construction standards, in line with the Reservoirs Act 1975, will ensure that dam breach risks are minimised to acceptable levels.
5.6.4 In addition to compliance with legislation relevant for the construction maintenance and monitoring of dams and reservoirs, in the unlikely event of a breach, the topography and large areas of land surrounding the site will limit flow reducing negative effects. The Emergency Response and Flood Risk Management Plan, which will be developed in conjunction with NRW and GC, will ensure that an effective and coordinated response to any emergency can be implemented to further mitigate the potential consequences of such an event.
5.6.5 Overall, it is considered that the residual effects during operation of the Development, assuming appropriate design and management, including
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implementation of the mitigation measures, will result in No Significant effects.
Effects during Decommissioning
5.6.6 During decommissioning the dams will be slowly drained into Llyn Padarn in agreement with NRW. The emptying of the dams will be managed by agreement with NRW through discharge consent.
5.6.7 Once the dams have been emptied, there will be no risk of a breach of the dams or a flooding event.
Conclusions
5.6.8 There are potential risks during construction and operation from groundwater flooding, pluvial flooding and flooding from existing drainage which require consideration within the detailed design of the site, the buildings, the surface water drainage systems and the reservoirs.
5.6.9 The assessment demonstrates that it is possible to mitigate the identified risks through the application of appropriate site management at the construction stage, appropriate design principles at the detailed design stage, and appropriate system management principles in operation. The mitigation measures outlined in the CoCP are designed to protect the users of the development, the development itself, and off-site properties from the effects of flooding.
5.6.10 The FCA has set out the guiding principles by which the design will be undertaken to ensure that there is no unacceptable increase in flood risk from the Development. It is therefore considered that effects during construction, operation and decommissioning will be Not Significant.
5.7 Cultural Heritage and Archaeology
5.7.1 Chapter 11 of the ES contains an assessment which identifies the potential effects that the Development may have on archaeological and cultural heritage resources.
5.7.2 The assessment has collated data from online sources and databases, historic mapping and other documentary sources. A site visit was also undertaken in October 2014, as well as extensive consultation under with
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GAPS and CADW. The assessment of the archaeological and cultural heritage sites within a 1km study area identified a total of 329 recorded assets.
Effects during Construction
5.7.3 It is anticipated that all effects on heritage assets will be restricted to the construction phase with 24 assets or groups of assets likely to be wholly or partially affected by the Development. The majority of these assets are associated with the slate extraction industry in the area, and the construction of the reservoirs and associated dams will result in the total loss of a number of assets. The re-modelling of spoil heaps and construction of new spoil heaps will also result in the loss or partial loss of further assets, as will the construction of access tracks, work compounds, and associated infrastructure.
5.7.4 There is potential for previously unrecorded archaeological features to be present within the Order Limits, although this is considered to be limited to areas currently occupied by spoil heaps. Following consultation with the Senior Planning Archaeologist at GAPS and archaeological advisor for GC, further archaeological investigation will be required within the Order Limits. This will inform the requirement for additional archaeological mitigation.
5.7.5 Mitigation is likely to comprise building recording, landscape survey, archaeological excavation and recording, and archaeological monitoring. This work will be agreed with the Senior Planning Archaeologist at GAPS and will provide a record of the affected assets. The Development will have a permanent residual moderate adverse effect and will therefore have a Significant effect on archaeology and cultural heritage.
Effects during Operation and Decommissioning
5.7.6 There are not expected to be any adverse effects on remaining archaeological features and cultural heritage assets during operation or decommissioning. Should any additional heritage assets be identified as part of any new amended Development, proposed extensions or remodelling after the proposed site becomes operational, they would be subject to an additional planning application.
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Conclusions
5.7.7 Effects on heritage assets are expected to be restricted to the construction phase of the Development, however they will have a Significant adverse effect on heritage assets. Mitigation works will be agreed with GC to provide a record of the affected assets.
5.8 Traffic and Transportation
5.8.1 Chapter 12 of the ES considers the traffic impact of the Development during the construction, operation and decommissioning phases. The scope of assessment was discussed and agreed with GC (as Local Highway Authority (LHA)) as part of the 2012 ES. Further discussions have taken place with the LHA during the preparation of the DCO application in relation to the upgrade to the Green Road to Q1.
5.8.2 A baseline of existing conditions has been established which analyses traffic flow data and accessibility for all modes of transport in order to accurately assess the effects of the Development on the local transport network.
Effects during Construction
5.8.3 During the construction phase, access will be required to both sides of the quarry system, Q1 on the Waunfawr side (west) and Q6 on the Llanberis side (east) of the site.
5.8.4 Traffic movements during construction include additional vehicle movements from workforce, deliveries and abnormal loads. Traffic requirements during operation of the facility will be restricted to staff commuting and site maintenance, and therefore will be concentrated at the Glyn Rhonwy (Q6) end of the Development.
5.8.5 A Construction Traffic Management Plan (CTMP) will schedule heavy goods vehicle (HGV) movements and abnormal loads to minimise delays for other road users; detailing how traffic will be managed and how pedestrian and cyclist movements will be safely managed in the event of closures and/or diversions to routes during construction. The CTMP will be part of the CoCP.
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5.8.6 The number of HGVs associated with construction traffic is likely to have an adverse, but temporary, effect on the local highway network, and therefore the programming of such movements will be subject to restricted periods of the day and working week.
5.8.7 A community liaison group will be formed to facilitate communication between the PC and local residents.
5.8.8 The CTMP will also promote sustainable travel to the site and detail measures to control traffic to site and minimise effects to the surrounding communities.
5.8.9 The CoCP also contains both an Air Quality Management Plan and a Dust Management Plan which will be implemented to reduce dust emissions from construction traffic locally.
5.8.10 Slate waste will be re-used on site wherever possible minimising movement of material off site and reducing the need to import materials for dam and track construction.
5.8.11 The Development is predicted to have No Significant adverse effects during construction.
5.8.12 Minor highway improvements will be carried out on Green Road from Waunfawr to Q1. As associated development, these improvements do not form part of the DCO application but will be subject to a planning application under the T&CPA.
Effects during Operation
5.8.13 During operation, it is not expected that there will be significant vehicle trips required to and from the Development on a daily basis. Only those needing to operate the facility or perform routine maintenance are expected to require travel to the site. Therefore there are no adverse effects predicted, which is considered to be Not Significant.
Effects during Decommissioning
5.8.14 During decommissioning it is not expected that there will be significant vehicle trips required to and from the Development on a daily basis and therefore there are no adverse effects expected.
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Conclusions
5.8.15 The findings of the traffic assessment demonstrate that all traffic can be accommodated on the local road network without compromising existing traffic levels.
5.8.16 The Traffic and Transport chapter within the ES outlines that the Development will result in a temporary increase in traffic volume on the surrounding network. However mitigation measures have been identified to reduce the potential traffic effect – this includes improvement to the road network to Q1 and implementation of a CTMP.
5.8.17 The Development therefore accords with the relevant local, regional and national planning policy guidance in that it is accessible by a range of modes other than the private car. The CTMP will also assist in complying with the relevant guidance by encouraging use of alternative modes to minimise single occupancy car trips to the site.
5.8.18 The internal site layout provides for pedestrian movement both within the Development and through the site to the surrounding area, where achievable.
5.8.19 It is concluded that traffic effects from the construction, operation and decommissioning of the Development are Not Significant.
5.9 Noise
5.9.1 Chapter 13 of the ES contains an assessment of the noise and vibration impacts of the Development. The assessment provides an update to that carried out on the approved scheme in the 2012 ES.
5.9.2 The study area for noise and vibration has been defined as the distance around the site where potential effects of noise from construction and operation phases may be expected. In consultation with GC, agreement was made on six residential receptor locations for the monitoring of existing ambient and background noise levels. Noise monitoring has been repeated at the six monitoring locations from the 2012 survey and at two additional locations, a caravan park which is currently under construction and Surf Lines (commercial/leisure premises). For the April 2015 surveys, 24-hour
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unattended noise surveys were carried out at locations surrounding the Development site. Supplementary attended noise monitoring was conducted during daytime, evening and night-time periods. Survey locations are presented in Figure 13.1 in Volume 4 of the ES.
5.9.3 Baseline noise monitoring was conducted at these locations to establish the existing noise environment and determine representative background noise levels at the surrounding Noise Sensitive Receptors (NSRs) near to the Development site.
5.9.4 Measurements have been conducted in accordance with the principles of BS 7445-1:2003 'Description and Measurement of Environmental Noise Part 1: Guide to Quantities and Procedures' and BS 4142:2014.
Effects during Construction
5.9.5 Noise and vibration limits are predicted to be temporarily exceeded during construction in some locations because of activities including surface plant, tunnel drilling and blasting, and traffic, giving rise to potential temporary significant effects to localised properties. However, levels of vibration generated are unlikely to cause cosmetic damage to structures. Based upon a preliminary assessment of potential noise from surface plant during the construction phase, it is considered that effects of up to major adverse could arise without mitigation. Such effects should be minimised where possible by adopting Best Practicable Means, a CoCP and a Noise Management Plan (NMP), and the setup of a local liaison group, to specifically identify potential effects and appropriate mitigation based upon site specific information as the project progresses. Once specific and exact construction methods are known by a contractor, an assessment should be undertaken to determine a more accurate noise assessment.
5.9.6 Significance of construction traffic noise and vibration effects has been considered for representative NSRs. Construction traffic effects can be mitigated through management methods, road maintenance and ongoing monitoring and would be anticipated to result in short term effects (less than 5 years). This would result in effects that are no greater than minor adverse at the worst affected NSRs and therefore are considered Not Significant
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Effects during Operation
5.9.7 During operation, noise and vibration effects potentially result from turbines and generators; transformers and switchgear; the workshop and pumping station. However due to the underground or enclosed nature of these components combined with appropriate building design and materials, the Development is predicted to result in negligible effects on NSRs, and therefore is considered Not Significant. Noise control and mitigation measures will be finalised during detailed design in order to ensure that airborne noise emissions from operational plant will achieve suitable operational limits following guidance from BS 4142.
Effects during Decommissioning
5.9.8 As the quarries and dams will remain in situ, no blasting or crushing will be required and it is considered that the effects will be negligible and therefore Not Significant.
Conclusions
5.9.9 Based upon a preliminary assessment of potential noise from surface plant during the construction phase, it is considered that effects of up to major adverse could arise without mitigation. Such effects should be minimised where possible by adopting Best Practicable Means (BPM), a CoCP and a NMP, and the setup of a local liaison group, to specifically identify potential effects and appropriate mitigation based upon site specific information as the project progresses. Once specific and exact construction methods are known by a contractor, an assessment should be undertaken to determine a more accurate noise assessment.
5.9.10 Construction traffic effects can be mitigated through management methods and therefore are considered Not Significant.
5.9.11 Effects during operation and decommissioning will be Not Significant.
5.10 Air Quality
5.10.1 A qualitative assessment was conducted to determine the potential dust effects during the construction phase of the Development, with reference to
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proposed activities, duration of works, baseline conditions and proximity of potential sensitive locations.
Effects during Construction
5.10.2 Dust emissions are likely to be caused by construction activities including drilling, blasting, rock bolting, bulk excavation, crushing of excavated material and partial removal of existing spoil heaps.
5.10.3 The effect of construction dust will be mitigated through the methods outlined in both the Air Quality Management Plan (AQMP) and Dust Management Plan (DMP) within the CoCP, which are based on best practice guidelines. Before starting work, potential dust generating activities will be identified and good site planning and management will prevent unnecessary dust generation, for example through the use of wheel wash facilities, road sweepers and speed restrictions.
5.10.4 Where appropriate, dust generating activities will be undertaken off-site, however, where this is not possible these activities will be located away from residential properties.
5.10.5 The Llyn Padarn SSSI is located adjacent to where the outlet and pumping station will be constructed, but is over 100m from other construction activities. However, this is a wet environment, and so the risk of effects due to dust were considered to be negligible and not significant (no other designated ecological sites are located with 100m of the Development site).
5.10.6 Based on the proximity of the nearest sensitive receptor and potential dust emission class, the risk of effects during the earthworks, construction works and track-out was considered to be a likely, major, adverse effect, if no mitigation measures are adopted.
5.10.7 General mitigation measures are recommended to be used in conjunction with more detailed, activity specific measures. Mitigation measures include the preparation and implementation of a Dust Management Plan which will be used in conjunction with more detailed, activity specific measures such as onsite monitoring. The overall significance of the residual effects are determined to be a likely, minor, adverse effect for both human and
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ecological exposure. Overall the Development effects will be Not Significant, with regard to air quality.
5.10.8 The potential effects due to road vehicle emissions during the construction phase were also assessed and deemed to be Not Significant.
Environmental Effects during Operation
5.10.9 The Development will produce negligible emissions to air during operation and will therefore be Not Significant.
Environmental Effects during Decommissioning
5.10.10 The Development will produce negligible emissions to air during decommissioning and will therefore be Not Significant.
Conclusions
5.10.11 Overall the Development effects will be Not Significant, with regard to air quality.
5.11 Socio-Economics
5.11.1 Chapter 15 of the ES contains an assessment of the potential socio- economic, access, and amenity effects of the Development on:
x Socio-economics: the local communities and associated economies in the vicinity of the Development; and
x Tourism and Recreation: Tourist/visitor attractions as well as recreational land uses such as visitor centres and walking or cycling routes.
5.11.2 The study area defined takes into account potential receptors of effects such as local communities that could be affected by the scheme, local tourism operators and recreational users (such as users of Public Rights of Way (PRoW), cycleways and areas of high public amenity value).
Effects during Construction
5.11.3 At the peak of construction there will be approximately 250 construction staff onsite, although on average there will be about up to 100 construction staff at any one time and dependant on the build programme.
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5.11.4 There will be direct and indirect positive effects to the local economy during the construction phase from increased employment activities and indirect benefits through increased use of facilities in the area, such as accommodation and restaurants. There will be direct inward investment due to use of local services and employment. SPH, or the PC as appropriate, will hold "meet the buyer" events to encourage local businesses to engage with the construction tender process. It is considered that employment opportunities will have a temporary regional minor beneficial impact. The Development is likely to have a temporary local, minor, beneficial impact on the local economy.
5.11.5 During the construction phase, tourism facilities located alongside the A4086, A4085 and the minor road leading to Q1 are likely to be temporarily affected by construction traffic during the construction period. Recreational activities involving public access in the immediate vicinity of the site will experience a temporary, local, minor adverse impact during this phase of development.
5.11.6 Any decrease in tourist visitor numbers due to the construction activities will only be temporary in nature.
5.11.7 A CTMP will be produced to ensure there is minimal disruption to community and tourist traffic during the construction phase. SPH will work with the local communities and businesses within villages such as Waunfawr, Croesywaun and Groeslon to ensure the phasing of the construction works minimises any negative effects on the local communities.
5.11.8 Mitigation measures will include temporary closures and diversions of PRoWs, permissive routes and open access land within the Order Limits to ensure safety to recreational users during the construction period. These temporary and permanent diversions will be secured through the DCO process. There is likely to be a temporary, local minor adverse impact during construction on the Green Road affecting villages such as Waunfawr, Croesywaun and Groeslon due to upgrading the access road.
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Effects during Operation
5.11.9 During the operational phase, 20-35 jobs will be created and the Development will have a number of net benefits on the local and regional economy.
5.11.10 There will be negligible effects to socio-economic receptors during Operation, effects are therefore Not Significant.
Environmental Effects during Decommissioning
5.11.11 There will be negligible effects to socio-economic receptors during decommissioning, effects are therefore Not Significant.
Conclusions
5.11.12 There are no Significant adverse effects on socio-economic receptors expected throughout the life cycle of the Development. There will be some likely localised temporary minor beneficial effects on receptors due to increased expenditure in the region during construction and potential localised temporary minor adverse effects on tourism routes and points of interest.
5.12 Environmental Management
5.12.1 Chapter 16 of the ES describes the Applicant's proposals for the environmental and waste management strategy. This strategy has been developed into an outline CoCP which will be developed further at the detailed design stage, subject to written approval from GC and NRW. The CoCP provides a framework to ensure that the appropriate environmental management practices are adopted during construction of the Development. This will ensure that environmental effects are minimised and mitigation measures, as described in the ES, are implemented.
Construction
5.12.2 The aim of the CoCP is to provide a framework of minimum standards to ensure:
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x Mitigation measures identified in the ES are implemented and that there is an agreed approach to identifying mitigation for any unexpected environmental effects that occur during construction;
x The adoption of good construction practices;
x That the PC and other subcontractors are complying with environmental legislation and statutory consents; and
x That the PC and other subcontractors comply with auditing, environmental monitoring, environmental inspections and reporting requirements.
5.12.3 The CoCP sets out a variety of control measures for managing the potential environmental effects of construction works including control and management of noise, dust, surface water runoff, waste and pollution control.
5.12.4 The CoCP includes the following topic specific environmental management plans:
x Water Management Plan (WTMP) – provided as outline in the CoCP;
x Pollution Prevention Plan (PPP) – provided as outline in the CoCP; and
x Construction Traffic Management Plan (CTMP) - provided as outline in the CoCP.
5.12.5 These plans will be finalised and agreed with GC and NRW through the submission of the finalised CoCP which will be submitted and agreed prior to construction commencing in accordance with a DCO Requirement.
5.12.6 Further plans which will be written under the CoCP in conjunction with the PC in line with DCO Requirement 6 include:
x Dust Management Plan (DMP)
x Waste Management Plan (WMP)
x Reinstatement/Landscape Plan;
x Noise Management Plan (NMP);
x Waste Management Plan (WMP);
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x Emergency Response and Flood Risk Management Plan (ERFRMP);
x Habitat Management Plan (HMP);
x Breeding Bird Method Statement; and
x Silt Management Plan;
5.12.7 Other plans required as per Requirement 7 are as follows:
x Air Quality Baseline Monitoring Plan;
x Materials Management Plan;
x Ordnance Management Strategy;
x Archaeological Compensation and Enhancement Strategy;
x Land Discovery Strategy;
x Health & Safety Plan (HASP); and
x Bio Security Plan.
5.12.8 Some construction activities may be noisy, such as blasting and ground preparation works. Due consideration will be given to the timings of such works and also the methods to mitigate any potential noise impacts.
Operation
5.12.9 The site will be subject to the operators’ Environmental Policy and subject to regular monitoring and auditing. The Development will also have a health, safety and environmental integrated management system assured under relevant standards. The management system will incorporate environmental control procedures, which will be regularly independently audited and certified.
5.12.10 Waste generation during the operational phase will be minimal, resulting mainly from maintenance activities and will either be recycled using the onsite recycling facilities or, where this is not possible, be disposed offsite.
Decommissioning
5.12.11 At the time of decommissioning, a Decommissioning Plan will be developed in consultation with the necessary bodies to ensure that works are undertaken in compliance with all relevant legislation and regulations.
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Conclusions
5.12.12 All mitigation measures outlined in the ES will be developed into a full CoCP, which will be subject to detailed design and then agreed and finalised with GC, NRW, CADW and GAPS. These will include several other management plans to cover water, waste, transport, noise, dust, flood risk and waste which will be finalised with the PC is instructed and prior to construction works starting.
5.13 Cumulative Effects
5.13.1 Chapter 17 of the ES identifies and outlines the cumulative effects associated with the Development, both for intra-project (in-combination) and inter-project effects.
5.13.2 Cumulative effects can be defined as the effects on the environment that result from incremental changes caused by the combination of the Development together with other reasonably foreseeable future actions.
Intra-project (In-combination) effects
5.13.3 For the purpose of this assessment, consideration has been given to “in- combination effects” between environmental topics and also the potential for ‘shared receptors’ that may be affected by the different components of the Development, such as a local resident that could be affected by dust, noise and traffic disruption during the construction of a scheme, with the result being a greater nuisance than each individual effect alone.
5.13.4 In-combination effects were considered in relation to how effects may interact and whether combining individual effects may enhance the overall effect on a receptor.
5.13.5 There are unlikely to be any intra-project effects from the operation and decommissioning phases of the Development and so these are not considered further.
5.13.6 For the construction period, shared receptors identified included local communities, ecological features and water bodies. The cumulative effects of traffic and construction works on noise levels and air quality were considered. Through the application of mitigation measures, which will be
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secured in the CoCP and its various management plans, it is considered that the intra-project combined effects are negligible and minor.
5.13.7 These are therefore unlikely to add to the overall significance of proposed effects of the Development and therefore are considered to be Not Significant.
Inter-project effects
5.13.8 A review of the planning applications and proposed developments within the area around the Development was undertaken to scope in the developments that were considered to constitute ‘major development’ schemes. Cumulative developments are shown in Figure 5.2 of the NTS.
5.13.9 The sources of potential cumulative effects in the vicinity of Glyn Rhonwy have been identified as:
x The electrical connection and the switchgear station to connect the Development to the electricity distribution system (to be developed and owned by SP Manweb);
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x The construction of Wylfa Newydd Nuclear Power Station and its associated infrastructure and developments; and x The construction of the Caernarfon to Bontnewydd bypass. 5.13.10 The main source of potential cumulative effects in the vicinity of the site was identified as Wylfa C New Nuclear Power Station. Traffic and Transport, and socio-economic effects were considered.
5.13.11 However, due to the distance between the two developments, the staggered timing of enabling and peak construction periods of both developments, plus the potential alternative means for Wlyfa Newydd to reduce traffic volumes if required, there are also no cumulative effects anticipated on local road networks including the A5.
5.13.12 Cumulative effects may arise through the upskilling of businesses in the region to work in the construction of low carbon energy developments such as Wylfa Nuclear Power Station. Therefore this is anticipated to be a minor beneficial cumulative effect.
5.13.13 Due to the substantial distance between Wylfa Newydd Nuclear Power Station and the Development, there are no cumulative effects anticipated on tourism or recreational receptors.
5.13.14 Presuming appropriate mitigation is adopted during the construction of the Caernarfon to Bontnewydd Bypass, such as diversions and warnings to road users, and the scale of construction activities, these potential effects will be minimised. As the works will also be temporary, in-combination effects on the local highway network are likely to be minor adverse. However, the local investments resulting from these developments are likely to have minor beneficial effects.
5.13.15 The electrical connection was also considered. Through early pre- application discussion and at the request of GC and NRW, a high level assessment on the current known details and route of the electrical connection has been undertaken.
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Electrical Connection
5.13.16 As the electrical connection will be underground, it is unlikely that there will be any significant adverse effects on the surrounding landscape. In addition, due to the size, location, scale and nature of the Development and the electrical connection, it is likely that these will be viewed as a single construction project.
5.13.17 It is considered that due to these elements, the construction of the electrical connection would not be seen from the wider landscape, nearby settlements or indeed by the majority of the visual receptors. In addition, the excavation for the electrical connection would only require a shallow trench and therefore it is unlikely that there would be any need for any tree removal. Therefore in combination with the power house, this is considered a negligible effect.
5.13.18 The narrow trench and confined working area will minimise the production of dust during the installation. Dust is therefore considered to have no potential for cumulative effects.
5.13.19 However, it is recognised that there may be some adverse effects to the local communities on the A4244 whilst the connection is being installed into the highway verge from disruption and disturbance from the works. It is recognised that there may be a perception that these construction works will be of the same magnitude of the repair works to the 400kv connection to the Pentir substation for the Dinorwig scheme. It is not possible to provide details at this stage about the duration of construction works or the method of installation. An initial grid connection offer statement prepared by SP Manweb considers disruption to have a temporary minor adverse effect. This is considered Not Significant.
5.13.20 It is considered that No Significant effects resulting from the Development and the electrical connection for the Development, the Wylfa Newydd Nuclear Power Station or the Caernarfon to Bontnewydd Bypass will occur.
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5.14 Summary
5.14.1 This NTS outlines the findings and conclusions of the EIA for the Development which were reported in the ES which accompanied the DCO application. Sensitive receptors have been identified and potential environmental effects of the Development assessed by competent professionals in line with best practice for their specific technical topic.
5.14.2 Where necessary and reasonably practical, mitigation measures (detailed in full in ES Chapter 18, Schedule of Mitigation) have been committed to reduce the significance of the effects of the Development.
5.14.3 Following the implementation of the identified mitigation measures during the construction, operation and decommissioning of the Development, residual effects have been assessed and are summarised in Table 5-1 below.
5.14.4 In addition to stand-alone technical assessments, inter and intra project cumulative effects of the Development have been assessed, however none were found to be significant.
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Table 5-1. Summary of ES Significance of Effects Topic Significance of Effects within the ES for the Development Landscape There are no fundamental changes to the above ground structures or features of the Development in Character and comparison to the approved scheme and therefore the number of receptors has not changed. There will be Visual Amenity No Permanent Significance effects on the LANDMAP Aspects, LCAs or landscape designation in the study area. There will be a Significant adverse residual effect on the receptors at Viewpoint 7. These findings are consistent with the effects identified in the 2012 ES. Ecology The overall residual effect ecological impact assessment is assessed as minor adverse (excluding effects on bat tree roosts). Therefore the effects are considered to be Not Significant in EIA terms. The overall residual effect assessment on bat tree roosts only is assessed as moderate adverse. Therefore the effects are considered to be Significant in EIA terms. Mitigation measures have been incorporated in the design to minimise impacts on bats; these are outlined in the bat licence application. Although the Final ES conclusions have been supplemented with additional survey data, these findings are consistent with the effects identified in the 2012 ES. A No Significant Effects Report has been prepared (Document 5.04) and this has concluded that there are No Significant Effects to any Natura 2000 sites Geology and It is considered unlikely that any major sources of ground contamination would be identified. Overall it is Ground Conditions concluded that the Development would have No Significant impacts on soil and geology during construction, operation or decommissioning. The management of any UXO will be dealt with as per DCO Requirement 7 for the Ordnance Management Strategy. This is consistent with the findings of the 2012 ES Water Resources Appropriate mitigation measures will be implemented through the abstraction license and the updated WFD assessment and water balance model has concluded that the impacts of the Development on water resources during the construction phase would be negligible, and therefore Not Significant. Sealing of Q6 may potentially block existing drainage pathways which may result in flooding in Q5.
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Table 5-1. Summary of ES Significance of Effects Topic Significance of Effects within the ES for the Development Therefore, subject to further detailed investigations a water management system may need to be included. Other than this it is concluded that the operation of the Development would have negligible effects (Not Significant) on water resources receptors With the exception of the Q5 drainage, this is consistent with the findings of the 2012 ES Flood Risk There are potential flooding risks during construction and operation from groundwater flooding, pluvial flooding and flooding from existing drainage. Overall it is considered that, if appropriate mitigation measures are implemented, the residual impacts will be of negligible effect and Not Significant. The reservoirs will be designed in line with the requirements of the Reservoir Act and therefore the potential for breach will be minimised. Therefore there is no change to the operational effects and these are still considered to be Not Significant. This is consistent with the conclusions of the 2012 ES. Archaeology and This assessment has been updated to incorporate changes including amendments in the Order Limits. While Cultural Heritage the impacts on the archaeology and cultural heritage of the site are of the same nature, the wider area of the Order Limits has resulted in a larger number of sites that potentially could be impacted by the Development. As a result the Development will have a significance of effect of moderate adverse on archaeology and cultural heritage and will therefore be Significant. DCO Requirement 7 outlines the requirement to implement an archaeological enhancement and compensation scheme. However the overall conclusion is still consistent with the 2012 ES. Traffic & The Development will result in an increase in traffic volume on the surrounding network and the main Transportation construction access points have not changed since the approved scheme. However mitigation measures, such as the CTMP, have been identified to reduce the potential traffic effect. Therefore it is concluded that traffic effects from the construction and operation of the Development are Not Significant. This is consistent with the conclusions of the 212 ES.
October 2015 Glyn Rhonwy Pumped Storage Development Consent 6.01 Non Technical Summary Order Volume 1
Table 5-1. Summary of ES Significance of Effects Topic Significance of Effects within the ES for the Development Noise Residual effects during construction are still expected to range from negligible (Not Significant) to moderate adverse (Significant) during construction and it has been concluded that once specific and exact construction methods are known by a contractor, an assessment should be undertaken to determine a more accurate noise assessment. A NMP will be implemented during construction. It is still expected that potential effects during operation will be negligible and therefore Not Significant. This is consistent with the conclusions of the 2012 ES. Air Quality Due to changes in assessment procedures, significance criteria and mitigation controls have been updated. However the overall Development effects are still considered to be Not Significant with regards to air quality. It is still expected that potential effects during operation will be negligible and therefore Not Significant. This is consistent with the conclusions of the 2012 ES. Socio-Economics There will be direct and indirect beneficial effects to the local economy during the construction phase from increased employment activities and indirect benefits through increased use of facilities in the area. The construction phase is likely to cause an increase in traffic along the A4086 and A4085. A CTMP will mitigate as far as is reasonably practicable any disruption caused by traffic generated during the construction phase and therefore the impact will be Not Significant. Other management plans will be implemented such as the NMP and DMP. In addition the Environmental Clerk of Works will maintain a communication programme to inform local residents of the main construction activities such as blasting and abnormal loads. Works at Llyn Padarn will be timed to avoid summer school holidays to minimise any disruption to users. Health and Safety will be paramount during the main spillway infrastructure and pumping station works. Minor diversions may be in place but access will not be impeded. The car park area will still be in use by users.
October 2015 Glyn Rhonwy Pumped Storage Development Consent 6.01 Non Technical Summary Order Volume 1
Table 5-1. Summary of ES Significance of Effects Topic Significance of Effects within the ES for the Development The pumping station will not have any operational lighting or fencing, and only an above ground kiosk / control box will be visible. Through the consultation period. The location of the pumping station has been relocated further back from Llyn Padarn. Therefore it is considered that effects during operation are considered to be Not Significant This is consistent with the conclusions of the 2012 ES. Cumulative and In- The Development has been cumulatively assessed against Wylfa C New Nuclear Power Station for traffic combination Effects and socio-economic effects. There are expected to be No Significant cumulative effects should the construction of both projects coincide. The inter-project effects were also considered for the construction of the electrical connection and the Caernarfon to Bontnewydd Bypass. No Significant effects were noted. There are expected to be No Significant in-combination effects for the Development.
October 2015