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Corlacky Hill Wind Farm

Environmental Statement

Volume 2: Main Report

Chapter 10: Geology and Water Environment

Chapter 10 – Page 1

10. Geology and Water Environment

Introduction

Terms of Reference

10.1 This chapter considers the likely significant effects on the receiving hydrological, geological

and hydrogeological environments, associated with the construction, operation and

decommissioning of the Proposed Corlacky Hill Wind Farm, hereafter referred to as ‘the

Proposed Wind Farm Development’.

10.2 Assessment techniques used are aimed at identifying hydrological, hydrogeological and

geological constraints within the Preliminary Boundary, hereafter referred to as ‘the Site’,

including areas in which development should be avoided and areas in which additional

mitigation measures are required.

10.3 This chapter is supported by:

• Technical Appendix 10.1: Water Framework Directive Assessment;

• Technical Appendix 10.2: Geology & Water Environment Consultation Records;

• Technical Appendix 10.3: Abstraction Records;

• Technical Appendix 10.4: Peat Slide Risk Assessment;

• Technical Appendix 10.5: Peat Management Plan; and

• Figures 10.1 – 10.5 which are referenced within the text where relevant.

Statement of Authority

10.4 The assessment has been carried out by McCloy Consulting Ltd.; an independent

environmental consultancy specialising in the water environment, with specialist knowledge

of hydrological and hydrogeological assessments, sustainable drainage systems (SuDS),

drainage, river modelling and flood risk assessment.

10.5 McCloy Consulting has ongoing involvement in numerous geology and water environment

studies and SuDS projects across the UK and has developed a particular expertise in surface

water management for wind farms. The company has successfully designed a number of

SuDS/silt management solutions for wind farms in accordance with current best practice

guidance. The primary personnel responsible for undertaking this hydrology assessment are:

• Nicola Bradley BEng (Hons) MSc - Environmental Engineer with experience in the

preparation of geology and water environment assessments and environmental

monitoring for a number of onshore wind farms and for onshore wind energy projects in

the UK and particularly Northern Ireland;

• Kyle Somerville BEng (Hons) CEng MIEI - Chartered Engineer specialising in the fields of

engineering hydrology, surface water management, groundwater screening assessments

and geology assessments. He has provided technical input to planning applications for

over 20 onshore wind farms in Northern Ireland and has been responsible for planning

and construction-phase surface water management design and monitoring for a number

of the largest onshore wind farm developments in the UK, including particular

experience of upland sites in environmentally sensitive watersheds.

Complementary Assessments

10.6 The majority of potential effects arising due to wind farms are caused by construction

activities; therefore reference should be made to Chapter 2: Proposed Development for

information regarding detailed construction proposals.

10.7 Changes to the hydrological / hydrogeological regime may create resultant effects on

ecology with hydrological dependant ecosystems such as fisheries and peat. Therefore this

chapter is further supported by:

• Chapter 6: Vegetation & Peatland;

• Chapter 7: Terrestrial Fauna;

• Chapter 9: Fisheries;

Legislation and Planning Policy

10.8 Environmental planning policy and industry best-practice guidance relevant to an

assessment of hydrology and the water environment are summarised in Table 10.1 and the

following sections.

Relevant European and National Planning Policy

Table 10.1: Relevant European and National Planning Policy

Legislation

EU EU Water Framework Directive (2000/60/EC)

Groundwater Daughter Directive to the Water Framework Directive (2006/118/EC)

Priority Substance Daughter Directive to the Water Framework Directive (2008/105/EC)

Freshwater Fish Directive (2006/44/EC)

Environmental Liability Directive (2004/35/EC)

Dangerous Substances Directive (2006/11/EC)

UK UK Environmental Standards and Conditions Phase 1 and Phase 2 (UK TAG 2008)

NI Control of Pollution (Oil Storage) (Amendment) Regulations (NI) 2011

Drainage (Environmental Impact Assessment) Regulations (NI) 2006

Environmental Liability (Prevention and Remediation) (Amendment) Regulations (NI) 2009

Groundwater Regulations (NI) 2009 / Groundwater (Amendment) Regulations (NI) 2014

Nature Conservation and Amenity Lands (NI) Order 1985

Private Water Supply Regulations (NI) 2009 / Private Water Supply (Amendment) Regulations (NI) 2010






Legislation

Surface Waters (Dangerous Substances) (Classifications) Regulations (NI) 1998

The Drainage (NI) Order 1973 / The Drainage (Amendment) (NI) Order 2005

The Environment (NI) Order 2002

The Fisheries (NI) Act 1966

Water Act (Northern Ireland) 1972 / The Water (NI) Order 1999

Water Supply (Water Quality) Regulations (NI) 2007 / (Amendment) Regulations (NI) 2010

Water Environment (Water Framework Directive) Regulations (NI) 2003

Water Framework Directive (Priority Substances and Classification) (Amendment) Regulations (NI) 2012

Sustainable Development Strategy, “Everyone's Involved" (2010)

Regional and Local Planning Policy

10.9 The Site has been reviewed in relation to local planning policy specific to geology and the

water environment. A detailed planning policy and legislation review is included within

Chapter 1: Introduction and Planning Policy.

Magherafelt Area Plan 2015

10.10 The Site lies within Mid Ulster District Council area; the current area plan is Magherafelt

Area Plan 20151. The plan contains limited information regarding planning policy related to

the geology or water environments; or specifically to wind farms.

10.11 The Countryside Assessment technical supplement2 provided details of the sensitivity of

designated sites within the council area and outlines the scale of importance as summarised

in Table 10.2.

Table 10.2: Designations Summary

Scale of Importance Designation Type Designated By

INTERNATIONAL Nature Conservation Importance

RAMSAR Sites Convention on Wetlands of International Importance1975

Special Protection Areas

Special Areas of Conservation

European Commission Directive on the Conservation of Wild Birds (79/409/EEC)

The Conservation (Natural Habitats, etc.) Regulations ( NI ) 1995

NATIONAL Nature Conservation Importance

Nature Reserves, National Nature Reserves, Marine Nature Reserves

Areas of Special Scientific Interest

Nature Conservation and Amenity Lands (NI ) Order 1985

LOCAL Nature Conservation Importance

Sites of Local Nature Conservation Importance and Earth Science Interests / Assets

Northern Ireland Council Area Plans

1 Planning Service (2011) Magherafelt Area Plan. Available: http://www.planningni.gov.uk/index/policy/development_plans/devplans_az/magherafelt_web2.pdf [Accessed 08/02/2016]

2 Planning Service (2011) Magherafelt Area Plan: Countryside Assessment. Available: http://www.planningni.gov.uk/index/policy/development_plans/devplans_az/magherafelt_2015/magherafelt2015-techsupp-countryside.pdf [Accessed

08/02/2016]

PPS15 – Revised Planning and Flood Risk

10.12 Revised PPS15 sets out planning policies to "minimise flood risk to people, property and the

environment", emphasising sustainable development and the conservation of biodiversity.

The policy refers to the use of SuDS to minimise effects on the receiving water environment.

10.13 The policy notes that development proposals facilitating sustainable drainage would be

considered favourably by the planning authority; as such a sustainable drainage approach

would be adopted by the Proposed Wind Farm Development.

Guidance on Conservation of Geological Features - Earth Science Conservation Review

10.14 The Earth Science Conservation Review (ESCR) is the means whereby areas of geological

interest in Northern Ireland are assessed to determine their importance to science and

hence to earth science conservation.

10.15 The objective of the ESCR is to define systematically all earth science localities (geological

and/or geomorphologic) in Northern Ireland. The overall aim of the process is to encourage

conservation of such areas to protect them from potential threats such as landfill, changes

to natural systems and coastal defence work.

Industry Guidelines

10.16 The Pollution Prevention Guidelines (PPGs), published by the Northern Ireland Environment

Agency (NIEA) in conjunction with the Environment Agency for England and Wales, and the

Scottish Environment Protection Agency (SEPA) include the documents referred to below.

Guidance notes relevant to the Proposed Wind Farm Development include:

• PPG01 Understanding Your Environmental Responsibilities: Good Environmental Practice;

• PPG02 Above Ground Oil Storage Tanks;

• PPG03 Use and Design Of Oil Separators in Surface Water Drainage Systems;

• PPG04 Treatment and Disposal of Sewage where no Foul Sewer is Available;

• PPG05 Works and Maintenance in or near Water;

• PPG06 Working at Construction and Demolition-sites;

• PPG07 The Safe Operation of Refuelling Facilities;

• PPG18 Managing Fire, Water and Major Spillages;

• PPG20 Dewatering Underground Ducts and Chambers;

• PPG21 Pollution Incident Response Planning;

• PPG26 Drums and Intermediate Bulk Containers.

10.17 Other relevant industry guidance includes:

• BS6031 - Code of Practice for Earthworks (2009);

• CIRIA C523 - Sustainable Urban Drainage Systems; Best Practice Manual (2001);

• CIRIA C532 - Control of Water Pollution from Construction Sites (2001);

• CIRIA C692 - Environmental Good Practice on-Site (2010);

• CIRIA C609 - Sustainable Drainage Systems: hydraulic/structural/water quality (2004);

http://www.planningni.gov.uk/index/policy/development_plans/devplans_az/magherafelt_web2.pdf






• CIRIA C697- The SuDS Manual (2007);

• CIRIA C689- Culvert Design and Operation Guide (2010);

• Environment Agency Policy: Technical Guidance on Culverting Proposals (1999);

• DEFRA Good Practice Guide for Handling Soils (2000);

• DEFRA Code of Practice for Sustainable Use of Soils on Construction Sites (2009);

• PPS 18 Renewable Energy and supplementary Planning Guidance;

• DOE / NIEA - Water Feature Surveys: A Guide to EIA and Planning Considerations (2015);

• DOE / NIEA - Water Feature Surveys: Wind Farms and Groundwater Impacts (2015).

Scope of Assessment

10.18 This report assesses the effects of the Proposed Wind Farm Development on hydrology and

surface water quality, hydrogeology and groundwater quality and geological features. The

assessment covers construction, operation, maintenance and decommissioning phases.

10.19 The report identifies and assesses the potential effects on the following:

• Existing natural and artificial drainage patterns

• Runoff rates and volumes

• Flooding and impediments to flows

• Surface water dependant ecosystems including hydrological units of peat bog

• Hydrogeological patterns

• Water quality of surface water and groundwater

• Usage of surface water and groundwater including abstractions

• Aquifer systems and their vulnerability

• Existing solid geology and superficial geology

• Structural geology of the area and its environs.

10.20 In order to quantifiably assess the preceding, this report:

• Outlines relevant policy relating to the water and geological environment;

• Summarises and responds to consultations provided in response to scoping requests to

inform particular requirements of the assessment;

• Provides baseline information and identifies sensitive receptors;

• Identifies potential likely effects, including potential likely cumulative effects;

• Assesses the significance of any adverse effects and resulting impacts based on the

magnitude of the impact and the sensitivity of the receptors;

• Discusses management of design evolution and detailed mitigation measures;

• Provides a residual impact assessment;

• Discusses cumulative effects of the Proposed Wind Farm Development in conjunction

with other proposed and existing developments in the vicinity.

Consultation

10.21 Formal consultation to form opinion and requirements with regards to the hydrological and

geological environments was sought from local and regional organisations as summarised

within. Consultation took the form of a proposed scope of this assessment and a request for

any amendment or additional requirements sought by the consultee.

10.22 A summary of the specific requests made by the various consultees is included in the

following table and input provided that was specific to the Proposed Wind Farm

Development is included in the subsequent baseline assessment.

Table 10.3: Consultee Summary

Consultee Summary of Response Addressed in Assessment

Local Council Causeway Coast and Glens

Provided addresses of 16 properties with a registered private water supply within 5 km of the Site.

10.96-10.106

Mid-Ulster Provided addresses of 25 properties fed by 11 private water supplies within 5 km of the Site. Advised that information is not held as to the source of the supply.

10.96-10.106

Department of Agriculture and Regional Development (DARD)

Sea, Fisheries and Environment

Confirmed that they had no issues or concerns from an aquaculture aspect.

Advised that it is an offence under Article 47 of the Fisheries Act (NI) 1966 to cause pollution which is subsequently shown to have a deleterious effect on fish stocks.

10.108-10.109

Rivers Agency Confirmed the area highlighted contains no designated watercourses but is affected by a number of undesignated watercourses as per the Drainage (N. Ireland) Order 1973.

Advised if during the course of development a watercourse is uncovered which was not previously evident they should be advised and; any proposals (temporary or permanent) in connection with the development which involve interference with any watercourse require written consent of Rivers Agency.

Noted Rivers Agency do not hold a database of records in relation to undesignated watercourses and therefore advised consultation with Ordnance survey or site inspections. For undesignated watercourses responsibility for maintenance rests with the landowners / riparian.

Confirmed Rivers Agency do not hold any floodplain survey information for the area highlighted.

10.60

10.83-10.85

Department of Culture Arts and Leisure (DCAL)

Inland Waterways and Fisheries

Advised that the Clady River is an index river informing DCAL policy in relation to the Department’s Salmon Management Strategy and the recent salmon conservation measures; and consistently exceeds its conservation level for salmon since monitoring of adult salmon returns began in 2011.

10.108-10.109

Department of Enterprise Trade and Investment (DETI)

Geological Survey of Northern Ireland

(GSNI)

An initial inspection of 1:10,000 geological maps in respect to the Proposed Wind Farm Development confirmed a large proportion of the Site is underlain by peat on top of glacial till and below the superficial deposits the bedrock is composed of Baroney Glen sandstone and Dungiven sandstone formations.

Noted that records indicate no mine workings nearby and recommend the ES includes a Peat Slide Risk Assessment.

10.47-10.52






Consultee Summary of Response Addressed in Assessment

Northern Ireland Environment Agency (NIEA)

Natural Heritage

NIEA response recommended that a description of the following should be included within the water and hydrology assessment:

Topography, geology, soils and water environment of the Site and surrounding area;

Water environment of the area - running and static surface waters, groundwater, estuaries, coastal waters / sea, run-off and drainage;

Hydrology, water quality and use of any water resources that may be affected by the development (e.g. water supply, fisheries, angling, bathing, amenity, navigation, effluent disposal);

Consequences of changes to the hydro-geological system of the area on peatland, rivers, streams, flushes and wetland habitats.

Clear identification of areas of active peat and intact peat in the EIA.

For sites hydrologically connected to a designated site, NIEA advised buffers of at least 50 m are provided to watercourses in which there should be no infill, disturbance, construction activity or material storage.

Throughout

Water Management Unit

Provided information on surface freshwater quality, groundwater / hydrogeology, Water Framework Directive data and abstraction licences downstream of the Site.

10.75-10.77

10.96-10.106

Drinking Water Inspectorate

Indicated six private drinking water supplies and 16 dairy farms using private water supplies within 10 km of Site.

10.96-10.106

Land and Groundwater

Recommended using the online GSNI Geoindex to source information on established groundwater regime, aquifer classification and groundwater vulnerability along with wetland / groundwater dependant ecology and surface / bedrock geology.

Confirmed that there are no licensed landfills within 5 km of the Site centroid and that there are no un-licensed landfills within 5 km of the Site centroid.

10.59

10.86-10.95

Assessment Methodology

Baseline Characterisation

10.23 This water environment and geology assessment has been undertaken using a qualitative

assessment based on experienced professional judgement and assessment of compliance

with statutory and industry guidance, including site visits for verification.

Study Area

10.24 Potential effects were considered within the study area defined as: the area within the

Preliminary Boundary (within which the planning application boundary lies) hereafter

referred to as the Site; and the wider geological and hydrogeological setting of the area.

10.25 The hydrological study area includes the downstream river reaches affected by the Site and

the surface water catchments draining the Site as defined by the relevant River Basin

Management Plans, Local Management Areas and Catchment Stakeholder Groups outlined

within Section 10.60 and as shown on Figure 10.1: Site Hydrology.

10.26 The hydrogeological and geological study area extends to the underlying aquifer catchments

and the extents of geological units.

Additional Areas Considered

10.27 Consideration has been given to potential likely significant effects in respect of the

proposed turbine delivery route and access route. Details of the work comprising junction

widening, passing bays and general road widening, and potential effects on the geology and

water environment are summarised within Chapter 11: Transport and Traffic.

10.28 A potential grid connection route is described within Technical Appendix 2.1: Assessment

of Potential Grid Connection. Although the grid route is not part of the Proposed Wind

Farm Development consideration has been given to potential likely significant effects.

Desk Study

10.29 The desktop study involved collation and assessment of the relevant information from the

following sources:

• Consultation responses (summarised in Table 10.3)

• Ordnance Survey raster and vector mapping in addition to aerial photography to assess

land use and environs and to identify water features and watercourse catchments

• The Geology of Northern Ireland – Our Natural Foundation, GSNI, Mitchell (2004)

• GSNI Geoindex (aquifers and aquifer vulnerability)

• GSNI 1:50,000 Bedrock Geology Map (Sheet 19 Maghera)

• NIEA Groundwater quality data and abstractions / discharges database

• NIEA Drinking Water Inspectorate and Water Management Unit data

• NIEA river quality data and natural heritage data

• CEH Flood Estimation Handbook (Version 3) for details of river catchment data

• Rivers Agency Flood Maps NI

• DCAL Inland Fisheries information.

Field Survey

10.30 A walkover survey was undertaken (18th March and 26th March 2015) with the purpose of

identifying / verifying existing natural and artificial site drainage characteristics and

hydrological features, and identifying the nature of superficial geology where visible.

10.31 The walkover survey incorporated the Site, with particular emphasis on areas affected by

preliminary turbine locations and known / mapped watercourses in order to fully assess

potential issues with regards to:






• New or upgraded watercourse crossings (bridges and culverts) required to facilitate the

proposed infrastructure;

• Disruption to watercourses through construction of roads/hard standing etc;

• Likelihood of adverse effects on surface water quality due to construction and operation

of wind farms;

• Potential for impact on natural geological conditions and groundwater movement /

quality.

Determination of Sensitivity, Magnitude, Likelihood and Significance

10.32 This assessment determines the nature, scale and significance of the effects of the Proposed

Wind Farm Development on the baseline (current) scenario in accordance with a

methodology stated within The Institute of Environmental Management and Assessment

guidance3.

10.33 The potential impact significance is defined by the combination of the sensitivity of the

receptor (Table 10.4) and the magnitude of the effect (Table 10.5). Following this an overall

impact significance is determined by considering the potential impact significance (Table

10.6) and the likelihood of the effect occurring (Table 10.7).

Sensitivity Criteria

10.34 The scale and sensitivity of the receiving environment (receptor) has been categorised on a

scale of “Very High” to “Low”. The sensitivity criteria used for this assessment are

presented in Table 10.4 and are based on:

• Vulnerability of a receptor to a particular pressure (degree of environmental response to

any particular effect); and

• The importance or ‘value’ of the receptor e.g. an area of international importance

should be considered more sensitive to effect than a local area of little or no

conservation value.

Table 10.4: Evaluation of Receptor Sensitivity Criteria

Scale / Sensitivity of the Environment (Receptor)

Definition of Criteria

International and / or Very High

Attribute has a very high quality / rarity at an international scale.

Geology / Soils

Important on a European or global level, e.g. World Heritage Site, Geopark, Ramsar Sites, Special Areas of Conservation (SAC), Special Protected Areas (SPA), Habitats Directive Sites or protected sites under EC legislation with respect to the geological environment.

Water Environment

Important on a European or global level, e.g. Ramsar Sites, SAC, SPA and Habitats Directive Sites with dependence on the water environment.

National and / or High

Attribute has a high quality and rarity at a national scale.

Geology / Soils

Important in Northern Ireland, e.g. Area of Special Scientific Interest (ASSI), with respect to the geological environment or protected site under UK or NI legislation.

Water Important in Northern Ireland, e.g. ASSI or National

3 Institute of Environmental Management and Assessment (2004) Guidelines for Environmental Impact Assessment.

Scale / Sensitivity of the Environment (Receptor)

Definition of Criteria

Environment Nature Reserve (NNR) with respect to the hydrological environment.

WFD classification of 'High' with the watercourse providing a nationally important resource or supporting river ecosystem.

Public water supplies and highly productive aquifers or local water supplies, including private water supplies where there is no alternative to private supplies.

Principal aquifer providing a nationally important resource.

Source Protection Zone 2 (Outer Source Protection Zone).

Regional and / or Medium

Attribute has a medium quality and rarity at a regional scale.

Geology / Soils

Site of regional geological importance.

Sites of Nature Conservation Importance in relation to earth science interest.

Water Environment

Important in the context of the region, e.g. catchment scale issues, main river within the catchment, local Nature Reserves or Sites of Local Importance for Nature Conservation (SLNCI).

WFD classification of 'Good' with the watercourse providing an important resource or supporting river ecosystem or upstream of a designated fishery.

Active floodplain area.

Designated fishery, catchment regionally important for fisheries.

Domestic private water supplies, located within vicinity of mains water supply or private water supplies used only for agricultural purposes and not drinking water.

Groundwater dependent terrestrial ecosystems in hydraulic continuity with the Site.

Principal aquifer providing a regionally important resource e.g. industrial use with limited connection to surface water.

Source Protection Zone 3 (catchment of groundwater source).

Local and / or Low

Attribute has a low quality and rarity at a local scale.

Geology / Soils

Areas with properties abundant on a local or regional scale or with little or no agricultural value.

Water Environment

WFD classification of 'Moderate' or less with the watercourse providing a locally important resource or supporting river ecosystem.

Domestic private water supplies, located within vicinity of mains water supply or private water supplies used only for agricultural purposes and not drinking water.

Groundwater dependent terrestrial ecosystems in hydraulic continuity with the Site.

Aquifer providing a locally important resource e.g. For agricultural or small-domestic supplies.






Magnitude of Effect

10.35 The magnitude of change / effect is influenced by the timing, scale, size and duration of

the hazardous effect; magnitude has been categorised on a scale of “High” to “Low” as

defined in Table 10.5.

Table 10.5: Evaluation of Magnitude of Effect Criteria

Magnitude of Effect / Description Definition of Criteria

High Fundamental change resulting in loss of an attribute and /or the quality and integrity of conditions.

River morphology / fluvial geomorphology

Significant and permanent change over large scale i.e. Large changes in erosion and deposition regimes.

Water Quality Potential high risk of pollution to surface water changing water quality status.

Water Supply Loss of local water supply or change in quality with respect to drinking water standards (DWS).

Flood Risk / Erosion Potential

Significant increase in risk due to a significant change in the proportion of hard standing and altered surface water flows.

Surface Water Dependant Ecosystem

Loss of or extensive change to a surface water dependant ecosystem or fishery.

Groundwater Significant change in groundwater levels, flow regime, groundwater quality or extensive change to an aquifer.

Geology / Soils Loss of the resource and / or quality and integrity of resource; severe damage to key characteristics, features or elements.

Medium Detectable change to conditions resulting in non-fundamental temporary or permanent consequential changes.


Detectable change to river morphology / fluvial geomorphology over a small scale i.e. some changes in erosion and deposition regimes.

Water Quality Potential medium risk of pollution to surface water, changing water quality status.

Water Supply Temporary loss of local water supply or minor change in quality of supply with respect to drinking water standards.


Detectable increase in flood risk and erosion potential due to a medium change in the proportion of hardstanding and altered surface water flows.


Partial loss or change to a surface water dependant ecosystem or fishery.

Groundwater Measurable change in groundwater levels, groundwater flow regime, groundwater quality or identifiable change to an aquifer.

Geology / Soils The site’s integrity would not be adversely affected, but the scheme may lead to a loss of or damage to key characteristics, features or attributes.

Low Results in minor effect on attribute of insufficient magnitude


Unquantifiable or unqualifiable change to river morphology / fluvial geomorphology.

Magnitude of Effect / Description Definition of Criteria

to affect the use or integrity.

Water Quality Minor deterioration in water quality unlikely to affect the most sensitive receptor or insignificant change in water quality conditions not exceeding those expected due to naturally occurring fluctuations.

Water Supply No change in pressure or flow to local water supply or minor change in quality of supply with respect to drinking water standards.


Minor changes in the proportion of hardstanding and altered surface water flows result in no detectable increase in flood risk and erosion potential.


Any measurable change in groundwater levels does not affect groundwater flow regime, groundwater quality with regards to DWS or result in any change to an aquifer.

Groundwater Minor alteration to one or more characteristics, features or elements or no observable effect

Geology / Soils No significant loss of or damage to key characteristics, features or attributes.

Impact Significance Criteria

10.36 The magnitude of effect and receptor sensitivity are combined to evaluate and qualify if an

impact is of high, moderate, low or negligible significance as outlined in Table 10.6.

Table 10.6: Evaluation of Potential Impact Significance

Scale / Sensitivity of the Environment

Effect Magnitude

Low Medium High

International / Very High Moderate High High

National / High Moderate Moderate High

Regional / Medium Low Moderate Moderate

Local / Low Negligible Low Low

Likelihood of Occurrence Criteria

10.37 The likelihood of the potential effects occurring is assessed based on historical data,

quantitative analysis and professional judgement based on relevant experience as shown in

10.38 Table 10.7.

Table 10.7: Evaluation of Likelihood of Occurrence

Likelihood of occurrence

Criteria

Certain Likely consequential effect in medium term and inevitable in long term (within the life of the development).

Likely Possible consequential effect in the medium term and likely but not inevitable in the long term.

Unlikely Unlikely that any consequential effect would arise within the lifetime of the development.

Rare It is unlikely that any consequence would ever arise.






Determination of Overall Impact Significance

10.39 Potential Impact Significance (Table 10.6) and Likelihood of Occurrence (

10.40 Table 10.7) are combined to determine an Overall Impact Significance as shown in the

matrix in Table 10.8.

Table 10.8: Evaluation of Overall Significance

Potential Significance Likelihood of Occurrence

Rarely Unlikely Likely Certain

High Minor Moderate Major Major

Moderate Minor Minor Moderate Major

Low Not Significant Minor Minor Moderate

Negligible Not Significant Not Significant Minor Moderate

Baseline Conditions

Site Description

10.41 The Proposed Wind Farm Development is located approximately 3 km to the west of

Swatragh, County L’derry and lies on the eastern slopes of Moneyoran Hill which has a peak

of approximately 414 mAOD and Carntogher which has a peak of approximately 464 mAOD.

The Application Boundary considered within this assessment occupies an area of

approximately 94 Ha.

Topography

10.42 Topography on the Site is dictated by the peaks of Moneyoran and Carntogher hills. Levels

fall from approximately 420 mAOD to 200 mAOD. The highest point of the Site is in the

south-west corner with land falling towards the Knockoneill River valley to the north-east;

topography dictates surface water catchments on the Site as summarised within Section

10.60 - 10.70. Slope gradients vary from 0o to 15o.

Land Cover

10.43 The principal habitat types found on the Site are upland blanket bog (the majority of which

is classified as degraded), wet heath (also degraded) and extensive areas of marshy, acid

and semi-improved grassland mosaics. The main land use on the Site is agricultural grazing.

Meteorological Data Summary

10.44 The Standard Percentage Runoff (SPR) is a parameter used in runoff and flood estimation,

which represents the percentage of total rainfall likely to contribute to direct runoff and

storm flows. For context, SPR values in the UK range from 2% (sand or chalk with slow

response / low runoff) to a maximum of 60% (peat bog with rapid response / high runoff).

10.45 A review of the Site in relation to Hydrology of Soil Types (HOST) class mapping indicates a

SPR of approximately 50 – 60 %, i.e. the general permeability of Site is low and catchments

are therefore likely to have a rapid response to rainfall events falling on open ground.

10.46 Rainfall data for the catchment extracted from Centre for Ecology and Hydrology Flood

Estimation Handbook at location centroid E321558 N327671 shows the Annual Average

Rainfall (1961 – 1990) is 1245 mm and Annual Average Rainfall (1941 – 1970) is 1376 mm.

Based on the Meteorological Office banding of annual average rainfall, the above statistics

indicate that rainfall in the area is within the 4th highest band of rainfall (1250-1500 mm) of

the nine bands; and the rainfall climate in the vicinity of the Site is similar to the UK

average and is typical for regions in the north-east of Northern Ireland.

Geology

10.47 The Site has been reviewed in relation to GSNI 1:50,000 series mapping (Maghera Sheet 19 -

Bedrock and Superficial Deposits), GSNI borehole data, Geoindex mapping, and additional

published information in order to determine potential geohazards that may restrict

development and identify existing geological features that may be adversely affected by the

Proposed Wind Farm Development.

Solid Geology

10.48 1:50,000 mapping indicates the composition of the upper bedrock varies across the Site;

• The upper bedrock within the south eastern portion of the Site (along the eastern and

southern boundaries) and land to the east of the Site is olivine basalt lava flows of the

Lower Basalt Formation.

• This is underlain by interbedded sandstone, siltstone and mudstone of the Barony Glen

Formation, the basalt does not extend across the centre of the Site and therefore the

Baroney Glen Formation Bedrock is the upper layer within the middle of the Site.

• Along the western boundary of the Site the upper bedrock comprises a variety of

metamorphic rocks. The upper bedrock within the central portion is psammite and

semipelite of the Dungiven Formation. This is underlain by metalimestone of the Bonds

Glen Limestone (exposed as the upper bedrock immediately north and south of the

psammite and semipelite) and underlain by psammite and semipelite of the Dart

Formation (exposed as the upper bedrock in the far north east and south east corners).

10.49 Faults at rockhead and intrusions of Donald’s Hill Ignimbrite and Dolerite are noted along

the geological boundaries between formations. A syncline (fold) has formed within the

metalimestone bedrock within the north-west corner of the Site.

Soils and Drift Geology

10.50 1:50,000 mapping indicates lower lying areas to the north-east and east are overlain by till

(diamicton, clay to sand matrix, varied pebble to boulder content) with drumlins. There are






comparatively minor (in the context of the Site area) isolated areas of glaciofluvial deposits

of poorly sorted sand and gravel in the south-east corner of the Site.

10.51 Drift geology mapping indicates no significant areas of sand on the Site that could be

considered a geohazard and deposits are of widespread local abundance.

Peat

10.52 The south-western, higher area is overlain by peat and there is one area of peat flow shown

on the superficial geology mapping initiating in the extreme south-west corner and flowing

in a north-east direction. This area is part of the Carntogher SLNCI; designated due to the

presence of blanket bog. The Maghera Sheet 19 superficial deposits mapping indicates an

area of peat flow (mass movement of peat resulting from a bog burst) within the southwest

corner of the Preliminary Boundary but outside the Application Boundary; details of the

historic Bog Flow are outlined within Technical Appendix 10.4: Peat Slide Risk Assessment

(PSRA). Findings from the PSRA are summarised as follows:

• Peat depth across the site ranged from 0.5 m to 1.5 m with depths increasing to >2 m in

the south west of the Site.

• The Qualitative Risk Assessment identified areas of ‘Medium’ and ‘High’ risk locations

across the Site and the resulting Quantitative Risk Assessment indicated that the risk of

instability at these locations is acceptably low providing suitable construction

methodologies are established.

• The assessment concluded that the overall risk is ‘Very Low ‘to ‘Low’. Further

recommendations on construction methodologies and mitigation measures along with a

Preliminary Geotechnical Risk Register are provided within the Technical Appendix.

Agricultural Land Classification

10.53 DARD published a classification index for Agricultural Land Classification (ALC) in 1997 based

on a document “Agricultural Land Classification of England and Wales” published by the

Ministry of Agriculture and Fisheries and Food (now Department for Environment, Food and

Rural Affairs) in 1988. The index classifies agricultural land into five grades based on

climate, topography, soil, slope and altitude characteristics; with Grade 1 excellent quality

and Grade 5 very poor quality.

10.54 Using an ALC classification summary table4 along with available site information including

site walkover observations and gradients; the lower gradient regions on the Site would be

anticipated to be classified as Grade 3b (moderate quality) agriculture land with higher

regions classified as 5 (very poor). As such loss of the land would not be considered of

significant consequence in the context of the region.

4 DRD (2013) Appendix C7 Agricultural Land Classification in Northern Ireland. Available:

http://www.drdni.gov.uk/appendix_c7_agricultural_land_classification.pdf [Accessed 17/09/2015]

Radon

10.55 UK Radon interactive mapping indicates that a north western portion of the Application

Boundary is located within an area where 5-10% of homes are at or above the action level

(200 Bq/m3) and an area to the south is located within an area where 1-3% of homes are at

or above the action level. The Application Boundary is therefore within a “radon affected

area” and the occurrence of radon is potentially a constraint to permanent buildings as part

of the development (i.e. substation building).

Waste and Minerals

10.56 The GSNI Geoindex showed no mine shafts / adits or active quarries on or immediately

adjacent to the Site that could pose a constraint to development. It also showed that

although the Site is situated within a historic mining licence area it is not within a current

licensed area and new mining activity is unlikely.

10.57 The GBASE 1994-96 Survey indicated gold within the stream sediments of tributaries of the

Knockoneill River. However the Tellus Survey 2005 - 2006 recorded no gold within stream

sediments of the downstream rivers and no other mineral occurrences were recorded on or

immediately adjacent to the Site; therefore proposed mining activity is unlikely within the

vicinity of the Knockoneill River.

10.58 The Carntogher SLNCI and adjacent Carn – Glenshane Pass (ASSI / SAC) are classified as

Areas of Constraint on Mineral Developments; therefore proposed mining activities or

quarries within these designated areas is unlikely.

10.59 NIEA has confirmed that their records show no licensed or unlicensed landfills within 5 km of

the Site centroid. As such potential geohazards arising from this source are negligible.

Geology Summary

Table 10.9: Evaluation of Geohazards

Geohazard Type Applicable to Proposed Corlacky Wind Farm & Rational

Extractions N/A No mining / quarry activity on the Site and new mining activity unlikely within the vicinity of the Site.

Land Slip N/A Excluding Peat Slide (considered separately) no historic landslips have been mapped on the Site. Limited depths of superficial deposits indicate low risk.

Running Sand N/A No significant sand deposits recorded on the Site

Compressible Ground N/A

Bedrock is considered to have sufficient bearing capacity for development. Isolated areas of compressible ground may be present within till deposits.

Peat slide risk is considered separately.

Landfill N/A No licensed landfills on the Site, no illegal landfill activity on the site.

Radon Yes Areas within the Application Boundary are within a classified Radon Action Area.

http://www.drdni.gov.uk/appendix_c7_agricultural_land_classification.pdf






Catchment Hydrology

Surface Water Bodies

10.60 The Rivers Agency Map of Designations approved by Drainage Council (NI) indicated that

there are no designated watercourses on the Site; as such all watercourses on the Site are

subject to riparian ownership and maintenance only. No other surface water bodies (ponds /

loughs) were identified on the Site.

10.61 Walkover observations indicated that the natural hydrology of the Site and undesignated

water features consist of source streams of the Knockoneill River and areas of artificially

modified peat drains.

10.62 NIEA River Basin Management Plan boundaries indicate all water features on the Site

discharge to the Knockoneill River; consequently the Site and its downstream catchment are

situated within the Lower Bann Local Management Area (LMA) which is within the Lower

Neagh Bann Catchment Stakeholder Group and falls under the control of the Neagh Bann

River Basin District.

10.63 The designated reach of the Knockoneill River draining the Site begins approximately 2 km

downstream of the Site at Knockoneill Bridge and is a tributary of the designated Clady

River. The Clady River flows in an eastern direction; discharging to the River Bann, which

flows north and discharges to Portstewart Bay approximately 30 km north of the Site.

Watersheds

10.64 The following is based on a combination of desktop study and walkover survey observations.

Main stream reach lengths identified are as per OSNI 1:2,500 scale mapping, validated or

otherwise by means of visual survey during the walkover.

10.65 Site drainage can be divided into five surface water catchments as detailed in sections

10.66-10.70. Surface water catchment extents are shown on Figure 10.1: Site Hydrology.

Knockoneill River

10.66 The majority of the Site containing proposed turbines T3 – T10 would drain to the main

channel of the Knockoneill River which issues at the south-west corner of the Site and flows

in a north-east direction. Within this catchment:

• Proposed turbines T4 – T5 and surrounding infrastructure drain directly to the main

Knockoneill River channel;

• Proposed turbine T3 would drain to a tributary of the Knockoneill River (Northern

Tributary); source streams of which issue along the western boundary of the Site;

• Proposed turbines T6 – T10 and the area surrounding the sub-station and construction

compound would drain to a tributary of the Knockoneill River (Central Tributary); source

streams of which issue along the southern boundary of the Site.

10.67 The Knockoneill River leaving the Site flows east becoming the Beagh River at Swatragh and

discharging to Clady River at Dunglady Bridge approximately 10 km downstream of the Site.

Eastern Knockoneill Tributary

10.68 T11 and the eastern portion of the Site would drain to a tributary of the Knockoneill River

(Eastern Tributary). Source streams of which issue along the southern boundary of the Site

and flow in a north north-east direction before discharging to the Knockoneill River

approximately 1 km downstream of the Site.

Southern Knockoneill Tributary

10.69 An area in the south-east corner of the Site which would contain the proposed site entrance

would drain to a tributary of the Knockoneill River (Southern Tributary). Source streams of

which issue on the Site in the south-east corner and flow in an eastern direction discharging

to the Knockoneill River approximately 1.7 km downstream of the Site.

Green Water

10.70 The north-west corner of the Site containing T1 and T2 would drain to the Green Water.

Head waters of the Green Water issue west of the Site and flow eastward discharging to the

Knockoneill River at Knockoneill Bridge approximately 2 km downstream of the Site.

Site Influence on Catchments

10.71 Table 10.10 demonstrates the proportionate influence by area on the main catchments

identified as being downstream of the development in order to qualify the significance of

potential effects on the receiving catchment.

Table 10.10: Watercourse Catchment Influence by Area

Catchment Extent Upstream Catchment Size (km2)

Catchment Area within

the Site (km2)

% of Upstream Catchment

within the Site Watercourse Downstream Location

Knockoneill River Knockoneill Bridge 2 km downstream of Site

E 283939 N 408462

14.58 4.46 30.6%

Central Tributary Upstream of Discharge to Knockoneill

E 281255 N 408086

1.59 1.42 89.6%

Knockoneill River Immediately downstream of Site

E 281870

N 408479 4.10 2.99 73.1%

Northern Tributary

Upstream of Discharge to Knockoneill

E 281319

N 408254 0.59 0.31 52.6%

Eastern Tributary Upstream of Discharge to Knockoneill

E 283221

N 408472 1.51 0.79 52.4%

Southern Tributary

Upstream of Discharge to Knockoneill

E 283751

N 408176 2.21 0.35 15.8%

Green Water Upstream of Discharge to Knockoneill

E 281889

N 408507 3.27 0.33 10.0%






10.72 The Site is fully within the Knockoneill River Catchment when taken from the Knockoneill

Bridge; the Site influences 30.6% of this catchment. When sub- catchments are considered

individually the influence the Site potentially has on a catchment can be further qualified.

10.73 The Site has a minor influence on the Southern Tributary and Green Water (15.8% and 10.0%

respectively of the catchments influenced by the Site) and a moderate influence on the

Northern Tributary and Eastern Tributary (52.6% and 52.4% respectively). These catchments

also contain a smaller proportion of the proposed infrastructure with two turbines,

substation and construction compound proposed for these areas; indicating a lower

significance of potential effects on these receptors.

10.74 The Site has a larger influence on the Central Tributary as the catchment is almost fully

within the Site (89.6 %) and the main Knockoneill River Catchment (if taken from

immediately downstream of the Site and including all tributaries) would have 73.1% of its

area influenced by the Site. These catchments contain the majority of the proposed

turbines and infrastructure; indicating higher significance of effect on receptors.

Surface Water Quality

10.75 The following section is intended to provide a qualitative appraisal of existing surface water

quality in those waterbodies whose catchment the Proposed Wind Farm Development lies

within.

10.76 Following publication of the Water Framework Directive (Priority Substance and

Classification) Regulations (NI) 2011 (WFD) waterbodies are given a classification based on

annual average / percentile results from several individual monitoring stations. WFD

classification is a combination of chemical, biological and hydromorphological elements,

whereby the overall status is the lowest of the combined constituents. The quality

elements considered for WFD classification are: biological quality elements; general

chemical quality elements; specific pollutants; and hydromorphology.

10.77 For purposes of classification, under the WFD, watercourses draining the Site lie within the

Lower Bann Local Management Area and local NIEA water quality monitoring locations in the

vicinity of the Site are shown on Figure 10.3: Water Quality. WFD results are summarised

below with overall WFD classification for the waterbody draining the Site outlined within

Table 10.11 and classifications for individual monitoring stations contributing to the overall

WFD classification summarised within Table 10.11.

Table 10.11: Surface Water Body Classification

Waterbody Name

Waterbody WFD Classification WFD Objectives

2021 / 2027 2009 2010 2011 2012 2013 2014

Knockoneill River

Moderate Moderate Moderate Moderate Moderate Good Good

Table 10.12: Contributing Surface Water Stations Classifications

Station Name and Number

Grid Ref.

Station WFD Classification

2006 - 2008

2007 - 2009

2008 - 2010

2009 - 2011

2010 - 2012

2011 - 2013

F10915 Knockoneill River at Dunglady

E 289600 N 403700

Good High Moderate Moderate Moderate Moderate

F10405 Knockoneill River at Beagh

E 285500 N 406300

Moderate Moderate Moderate Moderate Moderate Moderate

Project Specific Water Quality Assessment

10.78 In addition to a review of water quality data held by statutory agencies, independent water

quality monitoring has been undertaken as part of this assessment to provide baseline water

quality standards within the immediate environs prior to any proposed development. The

baseline assessment collected and assessed representative samples of water from

watercourses draining the Site.

10.79 Monitoring locations comprised sample points along the Knockoneill River and the Green

Water and included control sample locations; ten water quality monitoring locations were

sampled during the baseline survey as shown on Figure 10.3: Water Quality.

10.80 Water quality results were measured for compliance against key parameter limits outlined in

the WFD and the UK Technical Advisory Group on the Water Framework Directive (UK

Environmental Standards and Conditions) 2008. In terms of key indicators of water quality

and / or pre-existing pollutants, chemical results obtained showed:

• Classifications of “High” or “Good” based on WFD standards for several chemical

parameters (pH, dissolved oxygen, ammoniacal nitrogen, orthophosphate and biological

oxygen demand) indicating good water quality;

• Levels within typically expected ranges for freshwater for the majority of other

chemical parameters (alkalinity, electrical conductivity, chemical oxygen demand,

nitrates, aluminium and iron) indicating good water quality.

10.81 Biological results had relatively high Biological Monitoring Working Party (BMWP) biotic

scores (calculated from the presence of key family groups) and high Average Score per

Taxon (ASPT) with samples containing taxa from family groups 1 – 3 (considered to be

pollutant intolerant species and a sign of good water quality). Overall quality ratio

calculated from the BMWP and ASPT scores resulted in a classification of ‘Excellent’ or

‘Good’ at all water quality sampling locations.

10.82 Water quality for watercourses draining the Site is generally consistent with the WFD status

of Good/Moderate for the downstream waterbody outlined in Section 10.775. Therefore

preservation of the baseline water quality results within the upper reaches would be

important at a local level to preserve the downstream NIEA classifications.

5 Note: Independent water quality parameter assessments were carried out at face value over one round of monitoring rather than annual average / percentile

as required under the WFD. The data is presented in order to give context to the water quality observed on site.






Flood Data

10.83 The Proposed Wind Farm Development was considered in relation to Flood Maps (NI) which

provide an indication of predicted flood extents for a 1% Annual Equivalent Probability (AEP)

fluvial flood and 0.5% AEP Surface Water Flood.

10.84 Areas of fluvial flooding are predicted on the Site along the banks of the significant

watercourse channels. Areas of pluvial (surface water) flooding are predicted on the Site

along the banks of significant and minor watercourse channels. Isolated areas of surface

water flooding were noted in lands between the Central Tributary and Eastern Tributary and

along the southern boundary of the Site corresponding to isolated low points and issues /

headwaters of water features.

10.85 PPS15 states development will not be permitted within the 1% AEP fluvial floodplain

therefore flood extents would pose a constraint to development. Flood extents are shown

on Figure 10.1: Site Hydrology. Mitigation of flood risk is described in subsequent sections.

Hydrogeology

Groundwater Body

10.86 The Site is situated within the Coleraine-Kilrea Groundwater Body area (UKGBNI4NB001).

This groundwater body is defined by surface water catchments and the coastline to the

north. It is an area of central lowland comprising of predominantly agricultural land with

some larger population centres. Depth to water is variable but generally shallow;

approximately <10 m.

Bedrock Aquifers

10.87 The bedrock aquifer underlying the south east corner of the Site is classified as Bm(f)

indicating the aquifer has moderate productivity potential, intergranular porosity is

negligible and fracture flow is dominant and the aquifers have mostly short flow (tens to

hundreds of meters) with some regional flow. Bm(f) is consistent with palaeogene basalt.

10.88 The bedrock aquifer underlying the north west of the Site is classified as Bl(f) indicating the

aquifers have limited productivity potential and negligible intergranular porosity and flow

can occur within the upper weathered zone and some limited fracture flow can occur within

the upper 30 m. Bl(f)is common within dalradian rocks.

Superficial Aquifers / Aquifer Risk Ratings

10.89 Geoindex mapping indicates no superficial aquifers on the Site or within the downstream

catchment of the Knockoneill River. Minor isolated areas of glaciofluvial deposits of poorly

sorted sand and gravel (indicated on superficial geology mapping) likely to contain confined

lenses of groundwater are noted in the south-east corner and centre of the site.

10.90 Areas to the south-west of the Site (corresponding to areas of peat) and higher areas within

the catchment have a higher vulnerability. Central areas of the Site have a vulnerability of

4a where there is non-aquifer sand and gravel cover. The Site and most of the Knockoneill

Catchment have a vulnerability classification of “2” indicating low vulnerability.

Springs / Seepages

10.91 Historical NIEA Mapping6 shows springs at the head waters of the central tributary and

southern tributary on the 1829-1835 series and 1901-1957 series. The review of historic

springs indicates no other significant watercourses or features other than those mapped

within this chapter.

Boreholes / Wells

10.92 GSNI Geoindex indicates no recorded boreholes on the Site.

Groundwater Quality

10.93 For purposes of classification, under the implementation of the WFD the groundwater body

underlying the Site is the Coleraine-Kilrea Groundwater Body which falls within the Neagh

Bann River Basin District; initial characterisation of which was undertaken in 2012.

10.94 NIEA Water Management Unit (WMU) consultation indicated that no groundwater monitoring

points exist within 5 km of the Site. In the absence of groundwater monitoring results in the

immediate vicinity of the Site, the NIEA River Basin Monitoring Plan provided groundwater

quality information as summarised within Table 10.13;

Table 10.13: Groundwater Body Classification

Waterbody Name and Number WFD Classification WFD Objectives

2014 2021 2027

UKGBNI4NB001 – Coleraine-Kilrea Poor Poor Poor

Contaminated Groundwater

10.95 NIEA Guidance7 recommends identifying potential areas of saline or contaminated

groundwater based on historic land use. The baseline assessment aims to identify the

potential for any existing contaminated or low quality groundwater at the Site as its

presence could dictate construction methods required. NIEA Historical Land Use mapping

noted the following historic activities in the vicinity of the Site:

• Quarry and lime kilns (ceramics, cement and asphalt manufacturing work) near the

ponds to the north of the Site.

• Lime kilns (ceramics, cement and asphalt manufacturing work) during the 1980s and

1930s near at Corlacky Road / Corlacky Hill junction along the boundary of the Site.

6 NIEA (2015) Map Viewer Historic Six Inch Series. Available: http://maps.ehsni.gov.uk/SixInchSeries/Default.aspx [Accessed 08/02/2016]

7 NIEA (2015) Water Feature Surveys: A Guide to EIA and Planning Considerations. Available:

http://www.planningni.gov.uk/index/advice/northern_ireland_environment_agency_guidance/water_features_surveys.pdf

[Accessed 08/02/2016]

http://maps.ehsni.gov.uk/SixInchSeries/Default.aspx

http://www.planningni.gov.uk/index/advice/northern_ireland_environment_agency_guidance/water_features_surveys.pdf






Abstractions

10.96 Consideration has been given to the potential for the Proposed Wind Farm Development to

affect downstream water use (abstractions). Abstraction data has been obtained from a

number of sources, as follows:

• NIEA: WMU provided information on current licensed abstractions including public water

supplies within 5 km of the Site;

• NIEA: Drinking Water Inspectorate (DWI) has provided information on private water

supplies registered with the Inspectorate under The Private Water Supplies Regulations

(NI) 2009, including private drinking supplies and agricultural (dairy farm) supplies

within 5 km of the Site;

• Mid-Ulster Council and Causeway Coast and Glens Council provided addresses of

properties within 5 km of the Site which have a private water supply (PWS).

10.97 Guidance relating to abstraction constraints has been sought from the following UK sources:

• WMU recommendations of a 250 m buffer to development around any spring, well or

borehole used for public or private drinking water.

• SEPA Guidance Note 4 which indicates that roads, tracks and cable trenches associated

with wind farm development must be situated greater than 100 m from any abstraction

points and foundations must be situated greater than 250 m from any abstraction points.

10.98 Abstractions have therefore been screened for further investigation where they are within

500 m of the Site i.e. twice the recommended buffer to offer a conservative appraisal.

Surface Water Abstractions

10.99 A review of all information obtained from WMU and DWI indicates that no recorded surface

water abstractions are located within the identified screened area.

10.100 All other registered abstractions identified by the consultees lie sufficiently down gradient

of the Site so as not to fall within the conservative screening assessment and / or are

outwith the hydrological catchments affected by the Proposed Wind Farm Development.

Groundwater Abstractions

10.101 For purposes of determining the area affected by any potential effect on groundwater, it is

assumed that groundwater flow direction reflects local topography. A review of all

information obtained indicates that no groundwater abstractions exist within the screened

area.

10.102 All other groundwater abstractions identified by the consultees lie sufficiently down

gradient of the Site so as not to fall within the conservative screening assessment and / or

are outwith the hydrological catchments affected by the Proposed Wind Farm Development.

Other Abstractions

10.103 Mid-Ulster District Council and Causeway Coast and Glens District Council provided

addresses of 41 properties which are served by a PWS within 5 km of the Site. Two of the

properties registered as having a PWS are situated within the 500 m screening area. The

location of the point of abstraction of the PWS and the type/source was not provided by the

council; the points of abstraction were assumed to be at / immediately adjacent to the

property location.

Property Assessment

10.104 The various consultees indicated that they do not hold a definitive database of individual

properties served by a private water supply. Therefore in order to ensure a robust

assessment this assessment has screened properties not served by a Northern Ireland Water

(NIW) mains supply (based on review of NIW asset information) in order to further identify

properties potentially served by a local unrecorded abstraction.

10.105 A review of property data (comprising 78 properties as recorded by the Applicant in its

internal screening surveys) using NI Water Mains data and topography data identified ten

properties within the vicinity of the Site and down gradient of construction, which were

potentially not connected to mains:

• Two properties were mains connected and three properties were derelict /

uninhabitable; and therefore eliminated as a potential constraint.

• The remaining five properties were confirmed as being served by a PWS. This included

two boreholes located within the south east corner of the preliminary boundary which

were identified as serving adjacent properties as part of this assessment. Locations of

the properties and wells serving them are shown on Figure 10.2: Abstractions; all are

within the Knockoneill Catchment and within 500 m of the Site.

10.106 Mitigation is discussed in full within Section 10.161; however generally as a precautionary

measure potential private water supplies are identified as a constraint to construction: a

buffer of 250 m between the abstraction point and The proposed turbines and infrastructure

was incorporated into the design evolution of the Proposed Wind Farm Development, as

described in Chapter 3: Design Evolution & Alternatives. All abstractions considered and

proposed buffers are shown on Figure 10.2: Abstractions; and abstraction data received

from consultees is contained within Appendix 10.3: Abstraction Records.

Eco-Hydrology and Water Dependant Habitats / Wetlands

10.107 In scoping the water environment assessment in consultation with NIEA, priority habitats

recommended for investigation include active blanket bog and spring / flush areas.

Consideration has been given to local surface water and groundwater dependant ecosystems

and habitats dependant on or prone to change due to variation in surface water and

groundwater patterns on the Site within Chapter 06: Vegetation & Peatland. No further

consideration is given to those aspects within this chapter.






Fisheries

10.108 A full fisheries assessment is included within Chapter 9: Fisheries and is intended to qualify

the significance of water quality on and downstream of the Site to habitats and fish

populations. The Fisheries Assessment concluded that the Knockoneill River, Knockoneill

Tributary and the Green Water within the Preliminary Boundary had high sensitivity in

relation to fisheries potential / presence of key species with remaining on-site tributaries

determined to have medium or low sensitivity.

Water Framework Directive – Fisheries Classification

10.109 Following the repeal of Directive 2006/44/EC ‘on the quality of freshwaters needing

protection or improvement in order to support fish life’, commonly known as the Freshwater

Fish Directive; watercourses in Northern Ireland are classified by the WFD as outlined within

Section 10.75. NIEA Water Management Unit data showed that the Knockoneill River is

designated as a protected area under the WFD due to the presence of economically

significant species; this is considered when informing the sensitivity of watercourses.

Designated Sites

10.110 Environmental receptors such as Special Protected Areas (SPA), Special Areas of

Conservation (SAC), Areas of Special Scientific Interest (ASSI), Sites of Local Nature

Conservation Importance (SLNCI), Nature Reserves (NR) and Earth Science Conservation

Review sites (ESCR) have been investigated as part of this assessment. Assessed designated

sites are detailed below and shown on Figure 10.4: Designated Sites.

10.111 Designated sites were identified based on datasets available from NIEA at the time of the

assessment and the datasets were screened to identify:

• Hydrological sites with sensitivities to the water environment that are connected to the

Site, i.e. Sites which lie in the upstream catchment of or are on downstream

streamlines of the watercourses draining the Site;

• Terrestrial sites of geological importance on or immediately adjacent to the Site.

10.112 Terrestrial sites with ground or surface water dependant habitats are not included within

this assessment; sites are considered in Chapter 06: Vegetation & Peatland if required.

There are no areas of Earth Science Interest identified within or immediately adjacent to

the Preliminary Boundary.

Carn and Glenshane Pass SAC and ASSI

10.113 The Carn and Glenshane designated site is immediately adjacent to the Site. Surface water

catchments indicate that the Site drains eastwards and therefore the designated site is not

within the downstream catchment and not at risk from potential significant effects which

might occur as a result of the Proposed Wind Farm Development. Refer to Chapter 6:

Vegetation & Peatland for further information.

Baseline Summary and Receptor Sensitivity

10.114 The baseline assessment identified the receptors which have the potential to demonstrate

sensitivity to the Proposed Wind Farm Development; the receptors and their sensitivity /

value are summarised within Table 10.14. Sensitivity is based on the baseline assessment

and determined in accordance with the rationale previously described in Table 10.4.

Table 10.14: Receptor Sensitivity

Type Receptor Sensitivity Rational

Geological Soils / Drift Deposits Local / Low Site with little geological value or of widespread local abundance. Loss of the land on the Site would not be considered significant in the context of the region.

Hydrological On-Site and Downstream Knockoneill River

Regional / Medium

On-site watercourse has high fisheries sensitivity.

Upstream of the Clady River; a designated Salmonid watercourse under the FFD with populations of Salmonids, brown trout, European eel and Atlantic salmon.

WFD Classification of ‘Moderate’.

Approximately 73.1% of catchment influenced by Site.

On-Site Central Tributary

Regional / Medium

On-site watercourse has low fisheries sensitivity.

Upstream of the Knockoneill River which has a WFD Classification of ‘Moderate’.


Northern and Eastern Tributaries

Local / Low On-site watercourse has low fisheries sensitivity.


Approximately 52.4% and 52.6% of the northern and eastern catchments respectively influenced by Site.

Southern Tributary Local / Low On-site watercourse has low fisheries sensitivity.



On-Site Green Water Local / Low On-site watercourse has high fisheries sensitivity.



Hydro-Geological

Groundwater / Aquifers

Local / Low Minor isolated areas of glaciofluvial sand/gravel deposits.

Aquifer with limited productivity.

Groundwater WFD Classification and 2027 objective of “Poor”.

Used on a local scale for private water supplies in the vicinity of the Site.

Terrestrial Tracks, turbines and associated buildings.

Local / Low Proposed infrastructure prone to damage including potential for water damage of electrical infrastructure in a flood event; potential for structural damage of access infrastructure in the event of hydraulic incapacity.






Predicted Environmental Effects

Preamble

10.115 This section describes the potential likely effects on hydrological patterns and water quality

on the Site, and in the downstream environment, that have the potential to arise in the

absence of mitigation, during the following development phases of the Proposed Wind Farm

Development:

• Wind farm construction;

• Wind farm operation and maintenance;

• Wind farm decommissioning.

10.116 During each of these phases a number of activities will be undertaken, some of which will

have the potential to modify hydrological regimes and affect water quality on the Site and

in the downstream environment. Due to the nature of the Site and work undertaken,

hazards and associated effects will be similar for each phase, with an increased likelihood

during the construction phase due to the nature of the work undertaken.

10.117 Measures to prevent or reduce impacts are identified in the following sections, after which

residual effects post-application of mitigation are assessed.

Components Contributing to Predicted Environmental Effects

Activities Associated with Construction, Operation and Decommissioning

10.118 During construction, the Proposed Wind Farm Development comprises construction of

infrastructure which would be likely to cause change to local hydrology and water quality,

comprising earthworks, plant movements with associated use of lubricants and fuel oils,

spoil handling and placement of aggregates and cementitious materials, and dewatering

associated with construction of temporary compounds, turbine foundations, building

foundations, access tracks, and cable trenches.

10.119 The operational phase of the Proposed Wind Farm Development over the designed operating

life (estimated to be 25 years) would cause runoff from access tracks, turbine bases and

hard standings via drainage features; and would cause presence of onsite welfare facilities

with waste arising and potentially storage and use of oils, fuels and lubricants on-site.

10.120 Activities associated with the decommissioning phase at the end of the operating design life

are generally as per those for the construction phase, whereby activities associated with

decommissioning comprise earthworks, plant movements with associated use of lubricants

and fuel oils, spoil handling and placement of aggregates and cementitious materials, and

dewatering associated with removal of turbines, buildings, hard standing areas and buried

structures followed by reinstatement and restoration of ground cover.

Likely Significant Effects

10.121 The likely effects of the Proposed Wind Farm Development on the surface and ground water

environment prior to any avoidance or mitigation are summarised in the following sections.

Changes in Runoff and Flow Patterns

10.122 New temporary and permanent impermeable surfaces, as well as temporary compaction of

soils due to construction phase plant and site traffic movements, may cause increased rate

and volume of surface water runoff due to the reduced permeable area on the Site through

which rainfall can infiltrate. Impermeable surfaces will cause an increased “flashy” response

to rainfall events, with increased water velocities in new and existing drainage features. As

a consequence, the effect would be likely to cause temporary or permanent increases in

surface water runoff rates and volumes, leading to increased flood risk and increased

effects of erosion and scour in down gradient watercourses, affecting downstream

watercourses. Similarly loss of permeable areas is likely to cause reduced potential for

groundwater recharge affecting aquifers.

10.123 Significant excavations, in particular linear works such as access tracks, drainage ditches

and cable trenches are likely to act as barriers to runoff resulting in ponding, or

development of preferential flow routes, diverting surface water away from its current

route. As a consequence, temporarily or permanently redirected surface water flows may

to starve areas where water currently flows, or cause flooding of areas where water

currently does not flow.

10.124 Works to existing surface watercourses (such as installation of culverts or bridges) are likely

to cause an obstruction to flows and significantly alter conveyance capacities, with the

consequence of potentially causing temporary or permanent restrictions in watercourse

channels, affecting upstream water levels and increasing flood risk.

10.125 Ditch blocking as part of the habitat management plan has the potential to directly affect

stream morphology on the Site and in the upstream catchments during the operational

phase.

10.126 Significance of the identified potential effects is dependent on the particular catchment and

is considered in Table 10.21.

Silt / Suspended Solid Pollution

10.127 Temporary activities required to construct wind farm infrastructure would require

excavations, ground disturbance (due to excavations and trafficking), stripping and

excavation of peat and soils, and temporary spoil deposition. Exposed soils have potential

to release fine sediments in surface water runoff or where excavations come in contact with

surface watercourses.






10.128 Construction of access tracks and other hard standing areas would require importing,

handling and placement of aggregate, which would have the potential to release fine

sediments into surface water runoff or where tracks are built over surface watercourses.

10.129 Temporary surface water or shallow groundwater gathering in significant excavations has

the potential to be significantly polluted due to contact with excavated surfaces and

aggregates. Discharging of untreated water by pump or gravity would potentially cause

release of potentially heavily polluted effluent to watercourses.

10.130 As a consequence suspended sediments and debris entering watercourses would have the

potential to adversely modify stream morphologies, smother habitats and harm aquatic flora

and fauna.

10.131 Ditch blocking and peat placement as part of the habitat management plan has the

potential to cause release of silt / suspended solids effecting water quality (turbidity /

colour) during the construction phase.



Chemical Pollution of Surface Water and Groundwater

10.133 Temporary storage and use on the Site of chemicals, fuels and oils associated with

construction activity, and use of wet concrete and other cementitious material results in the

potential for these substances to enter the surface water environment through accidental

spillages, improper transport and refuelling or inappropriate storage and disposal

procedures, by gradual leakage or single failure of storage tanks or refuelling mechanisms.

Temporary presence of alum-based flocculants, (used to remove suspended solids from

surface water) if unregulated, has potential to enter surface waters.

10.134 Permanent presence of oils and lubricants associated with maintenance of turbines for the

life of the wind farm has a similar potential to enter the surface water environment.

10.135 Temporary and permanent wastewater effluent from temporary construction phase welfare

facilities and permanent substation building welfare facilities has the potential to enter

surface water or shallow groundwater.

10.136 As a consequence, chemical pollutants from construction activities, storage of materials, or

from coliforms from wastewater entering watercourses have the potential to adversely

affect water quality, with associated effects to potable supplies, fish and aquatic ecology.



Design Evolution: Avoidance Measures / Buffer Zones

10.138 The magnitude and significance of those effects determined as being likely to be a

consequence of the Proposed Wind Farm Development can be substantially reduced or

eliminated through sympathetic design to avoid those baseline receptors established

previously, with particular emphasis and concern in relation to fishery habitats.

10.139 This section identifies the avoidance measures imposed and subsequently identifies the

resulting magnitude and significance of residual effects. Additional mitigation is then

specified to further reduce or eliminate remaining effects.

10.140 Detail of the design evolution showing considerations made with regards to hydrology and

water quality management is presented in Chapter 3: Design Evolution & Alternatives.

10.141 The Proposed Wind Farm Development layout has evolved so that the design avoids conflict

with the water and geology environment, as demonstrated in the following sections.

Water Features

10.142 As a precautionary measure and in accordance with the guidance previously advocated by

NIEA Natural Heritage buffer (exclusion) zones to water features are adopted as constraints

to built development, and for incorporation as a construction buffer in relation to

permissible land uses in proximity to watercourses.

10.143 Impact avoidance and the design of mitigation have been developed in accordance with best

practice, using legislation and guidance as outlined in previous sections. Of particular

importance are the implications of the WFD and FFD. Mitigation for all water features aims

to preserve existing water quality ratings as a minimum.

10.144 Establishment of intact vegetated buffer zones between infrastructure and water features

allows:

• Protection of water quality by filtering runoff within riparian vegetation before it enters

the watercourse;

• Space for natural fluvial processes such as channel shape and planform adjustment

which help restore and maintain the natural dynamic balance of river systems and

associated habitats;

• Establishment of vegetation to stabilise banks and reduce soil erosion;

• Access for the maintenance and inspection of watercourses and for dealing with any

residual risk of pollution incidents; and

• Habitat for plants and animals to form part of a habitat network.

10.145 The sensitivity of the water feature, and the associated degree of protection it is afforded,

is primarily dependent upon:

• Environmental designations on the water feature or downstream environment;






• Fisheries or ecological potential in the water feature or in the downstream

environment;

• Water feature morphology (natural substrate or artificial channel, soil/ground type);

• Water feature size, capacity to convey water and hydrological potential (flows);

• Nature and topography of the surrounding land, i.e. wet, poorly drained soils and steep

slopes (>10°) would require greater protection;

• Sensitivity of the water feature, i.e. silts / nutrient enrichment / chemical pollution.

10.146 The rationale adopted in relation to water feature buffers is informed by NIEA Natural

Heritage guidance, which normally requests no infill, disturbance, construction activity or

storage of materials within 50 m of all natural watercourses. NIEA has indicated that

justification for buffer zones applied is the responsibility on the Applicant, while any

rationale for reducing the scale of the buffer zone must be demonstrated requiring the

submission of detailed information using a number of additional factors e.g. soil typology,

topography, size of watercourse and climatic conditions.

10.147 Additionally, NIEA in its Practice Guide to EIA and Planning Considerations8 outlines buffer

zones for water features (including surface watercourses) as per Table 10.15.

Table 10.15: NIEA Buffer Zones for Water Features

Water Feature Buffer Zone

Surface Watercourse 10 m (minimum detailed in PPG 5)

Water Feature (surface watercourse, spring, well, borehole)

used for Drinking Water (public or private) 250 m

Water Feature (surface watercourse, spring, well, borehole)

not used for Water supply (but could provide a preferential flow pathway) 50 m

Designated Wetland 250 m

10.148 Additional reference has been sought and taken into account from planning and policy

guidance adopted or promoted elsewhere in the UK. SEPA and Scottish Natural Heritage

(SNH) endorse guidance provided in Scottish Planning Advice as per Table 10.16. Additional

qualification notes that wet, poorly drained soils and steep slopes (>10°) will require a

larger buffer strip.

Table 10.16: SEPA / SNH Buffer Guidance

Width of Watercourse Width of Buffer Strip

Ditches 3 m

Less than 1 m 6 m

1-5 m 6-12 m

5-15 m 12-20 m

15 m+ 20 m+

8 NIEA (2015) Wind farms and Groundwater Impacts: A guide to EIA and Planning considerations. Available: http://www.planningni.gov.uk/index/advice/northern_ireland_environment_agency_guidance/wind_farms_and_groundwater_impacts-3.pdf [Accessed

08/02/2016]

10.149 Additional industry guidance relevant and similar in nature to the construction and

operational activities for the Proposed Wind Farm Development has been reviewed and

taken into account, in particular:

• Pollution Prevention Guidance (PPGs) in particular PPG5 ‘Works in or close to water’ –

recommends buffer strips of vegetation 5 – 10 m wide along site boundaries and river

banks to act as sediment filter.

• Best practice9 in relation to forestry works (in particular on upland and peat sites)

recommends riparian buffer reflecting stream size, with buffers from 5 – 20 m.

• Best practice10 in management of sediments and runoff from exposed ground in relation

to agriculture recommends buffers of up to 10 m in order to protect surface waters from

pollution by suspended solids, and nutrient enrichment by organic/inorganic fertilisers.

10.150 All water features (rivers, streams, drains and waterbodies) considered significant for the

purposes of this assessment and requiring application of a buffer to the Proposed Wind Farm

Development are shown on Figure 10.1: Site Hydrology and drainage management drawings

within Technical Appendix 10.1: Water Framework Directive Assessment.

Significant watercourses

10.151 Significant watercourses identified and requiring application of a buffer to the proposed

turbines and infrastructure are largely as per OS close scale vector mapping and were

subject to ground truthing on site. NIEA in its consultation response has stated its

preference that for upland sites 50 m buffers be provided to watercourses.

10.152 A 50 m buffer has been applied to the significant watercourses identified in the baseline

assessment, i.e. undesignated reaches of the Green Water and Knockoneill River and

undesignated Central and Eastern tributaries of the Knockoneill on the Site.

10.153 The drain along the western boundary of the Site has significant habitat within its

downstream catchment as it feeds the Green Water and drains the adjacent ASSI; however

the artificially excavated and diverted nature of the drain (cut laterally into the slope)

means that lands within the Site are downslope and cannot feasibly runoff into the drain. A

buffer of 20 m is applied the reaches of this drain, that buffer being defined by the distance

downslope of the drain at which ground levels relative to drain invert levels would cause it

to be impossible for there to be runoff to the drain.

9 Forestry Commission (2015) Managing Riparian Buffer Areas. Available: http://www.forestry.gov.uk/fr/INFD-6MVK4U [Accessed 08/02/2016]

10 DEFRA (2009) Protecting our Water, Soil and Air - A Code of Good Agricultural Practice. Available:

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69344%2Fpb13558-cogap-090202.pdf [Accessed 08/02/2016]

http://www.planningni.gov.uk/index/advice/northern_ireland_environment_agency_guidance/wind_farms_and_groundwater_impacts-3.pdf






Plate 10.17: Significant Watercourse Examples

Location Green Water Knockoneill River

Grid Ref. E 280543 N 408886 E 280982 N 408184

Photo Ref. GPSe-150326-141126.jpg DSC04824.JPG

Location Central Tributary Eastern Tributary

Grid Ref. E 280634 N 407110 E 281935 N 407816

Photo Ref. GPSe-150326-111600.jpg DSCF0313.JPG

Minor Watercourses

10.154 Reaches of watercourses at the upstream extents of a catchment and tributaries where the

catchment area was less than 0.25 km2 were considered as minor and given reduced buffers.

Minor watercourses were given buffers of 10 m based on SEPA and SNH guidance previously

referenced and sensitivity criteria outlined within Section 10.149 above.

10.155 Headwaters of the Knockoneill Tributaries and Green Water were classified as minor and

given a 10 m Buffer.

Plate 10.18: Minor Watercourse Examples

Location Northern Tributary Headwaters of Central Tributary

Grid Ref. E280883 N 408463 E 281359 N 406993

Photo Ref. GPSe-150326-143311.jpg DSCF0233.JPG

Location Southern Tributary Headwaters Unnamed Knockoneill Tributary

Grid Ref. E 282473 N 407077 E 280768 N 408078

Photo Ref. DSCF0105.JPG DSCF0408.JPG

Other Drainage Features

10.156 All other minor drainage features (mapped or otherwise) comprising; dry or partially dry

agricultural ditches, ephemeral drains, grips, peat cuttings or other drainage features are

considered insignificant in the context of site hydrology and habitat potential.






10.157 Such features would be managed during and following construction by means of diversion

and/or temporary blocking (with prior settlement features upstream of and outwith the

drainage channel), using filtration check dams or similar, in order to prevent residual

indirect potential pollution downstream caused by connectivity to downstream waterways.

Plate 10.19: Other Drainage Features Examples

Location Man-Made Drainage Northern Catchment Peat Cutting Central Catchment

Grid Ref. E 280227 N 407949 E 280421 N 406816

Photo Ref. DSCF0450.JPG GPSe-150326-113250.jpg

Location Drains Southern Catchment Peat Cutting Central Catchment

Grid Ref. E 282401 N 407420 E 280731 N 406626

Photo Ref. GPSe-150326-145743.jpg GPSe-150326-114406.jpg

Adopted Watercourse Buffers

10.158 Conservative minimum hydrological buffer zones are therefore adopted on the Site as

summarised in the Table 10.20 and imposed as shown on Figure 10.1: Site Hydrology. The

buffer widths adopted exceed those recommended in industry guidance; the allowance

provided gives due consideration to the nature of peat soil conditions on the Site,

antecedent weather, moisture and base flow and a significantly increased factor of safety in

all instances given the significance of fishery interests within downstream catchments.

Table 10.20: Minimum Hydrological Buffer Zones

Water Features Minimum Width of Buffer Strip

Significant Watercourses

(catchment >0.25 km2) 50 m / 20m As defined by topography - See Section 10.153 where drains are cut into slopes)

Minor Watercourses (catchment <0.25 km2) 10 m

Other Drainage Features Managed on-site by diversion / temporary blocking in accordance with PPGs.

10.159 Infrastructure designed to lie outwith stated hydrological buffer zones comprises those

elements of the works associated with significant earthworks and greatest potential for

spillage or leakage of chemical pollutants, i.e.:

• All turbine bases, crane pads and associated working areas;

• Temporary and permanent spoil storage areas; other than those areas where peat is to

be deliberately stored as part of the Outline Habitat Management Plan (Technical

Appendix 6.7).

• Enabling works compound, substation and construction compound, fuel and chemical

storage areas and any other platforms.

10.160 Access tracks are to lay outwith buffer zones; with the exception of unavoidable crossings of

water features. Careful consideration has been given to the routing of access tracks in order

to avoid crossings of watercourses and to avoid instances where roads run parallel to

watercourses over long distances.

Abstraction Buffers

10.161 In instances where the screening assessment of abstractions from surface and groundwater

has identified abstractions for private water supplies (Section 9.95), measures to protect

the private water sources have been imposed.

10.162 Previously summarised NIEA Planning Considerations (Table 10.15) with regard to buffer

zones for water features indicated a 250 m buffer for any water feature (surface

watercourse, spring, well, borehole) used for public or private Drinking Water.

10.163 Conservative buffer zones of 250 m (clipped to the upstream catchment of the abstractions

based on 10 m DTM data) are therefore adopted for the two properties highlighted by the






local council (Section 10.103) and five PWS identified in the property assessment (Section

10.105) as shown on Figure 10.2: Abstractions.

Floodplains

10.164 All permanent structures have been located outside areas denoted as lying within the

1% AEP fluvial floodplain based on Flood Maps (NI) strategic level mapping.

10.165 Pluvial and fluvial flood extends noted along watercourses on-site (outlined within Section

10.83 and shown on Figure 10.1: Site Hydrology) do not extend beyond the extent of the

buffers established in Section 10.158 and therefore do not further constrain development.

10.166 Infrastructure is designed to ensure that conveyance of surface water flooding is not

impeded by means of providing drainage culverts / under track crossings where necessary.

Electrical infrastructure that would be susceptible to damage by floodwater is designed such

that it does not have potential to be affected by surface water flooding.

10.167 Areas of isolated surface water flooding generally coincide with source areas of on-site

water features or isolated low-points. Site drainage and culverts shall allow passage of local

surface flooding as considered within Technical Appendix 10.1: Water Framework

Directive Assessment and accompanying drainage management drawings.

Radon

10.168 The permanent sub-station building is sited within an area classified as having the lowest

band of radon potential (less than 1% of homes above the action level. However due to the

identified likelihood of elevated radon levels within other areas of the preliminary

boundary, design of permanent (for the design life of the development) buildings including

substation buildings will be informed by a site specific radon survey post-consent; the

building will incorporate measures appropriate to radon levels observed in accordance with

Building Research Establishment guidance11 and any supplementary requirement of local

Building Control.

Effect of the Development

10.169 Magnitude and likelihood of the environmental effects identified previously in the

qualitative analysis presented in Section 10.115 have been determined based on criteria

outlined within Sections 10.32 - 10.39 and taking into account the effect of avoidance

measures proposed.

10.170 The associated impact significance of these effects on the receptors affected (following the

implementation of avoidance and design measures proposed) has been determined in

accordance with the rationale previously described and the results are presented in

summary Table 10.21 overleaf.

11 BR413 Radon: Guidance on protective measures for new dwellings in Northern Ireland (BRE 2004)






Table 10.21: Potential Magnitude and Significance of Impacts to Receptors – Including effect of Avoidance

Receptor and Sensitivity

Effect and Magnitude Potential

Effect Significance

Likelihood Overall Effect

Significance Rationale

Soils / Drift Deposits

(Local / Low)

Ground Movement / Instability

Medium Low Unlikely Minor Land slip potential is negligible due to shallow depth of stiff-natured drift deposits. Considered separately within the Peat Slide Risk Assessment; a quantitative analysis determined that the overall risk is ‘Very Low’ to ‘Low’ on the site.

On-Site /Downstream Knockoneill River

Central Tributary

(Regional / Medium)

Changes in runoff and flow patterns

Low Low Certain Moderate Increased runoff from impermeable infrastructure would cause a minor effect, however the effect is considered to be of low magnitude due to the proportional area of the receiving catchments affected being insignificant, and would therefore not affect the water use (in terms of normal water flows and frequency and magnitude of flooding).

Introducing crossings at seven locations within channels on-site within the Knockoneill / Central Catchment would be likely to change or restrict channel capacity, with potential to cause a detectable but minor and localised increase in flood risk / flood levels upstream of the structure (i.e. on the Site itself).

Temporary and permanent infrastructure comprising linear works installed (drainage channels, cable routes etc) would be likely to cause minor and local change to runoff patterns on Site.

Qualitative appraisal of environmental effects arising is as described in Sections 10.122 - 10.126.

Silt / suspended solid pollution of surface waters

Medium Moderate Likely Moderate Temporary short-term construction activities within watercourses would be likely to cause a significant but temporary fundamental change in water quality in the immediate downstream environment.

Avoidance of watercourses by infrastructure would result in there being no direct discharge of silt laden runoff from infrastructure to watercourses other than at watercourse crossings. Filtration of runoff across intact riparian buffers is likely to sufficiently reduce concentrations of pollutants sufficiently that there would be no significant effect.

Remaining point discharges of runoff to watercourses at unavoidable crossings would be likely to cause a significant but temporary fundamental change in water quality in the immediate downstream environment during construction phase, and a detectable but minor change in water quality during the operational phase.


Chemical pollution of surface waters

Medium Moderate Likely Moderate Spillage of oils, chemicals, or cementitious material associated with temporary construction and arising due to improper site management would be likely to cause a fundamental but temporary change in water quality in the downstream environment.


On-Site Northern Tributary

(Local / Low)


Low Negligible Certain Moderate No turbines or watercourse crossings are proposed within this catchment.

Increased runoff from impermeable infrastructure would cause a minor effect, however the effect is considered to be of low magnitude due to the proportional area of the receiving catchments affected being insignificant, and would therefore not affect the water use (in terms of normal water flows and frequency and magnitude of flooding).

Temporary and permanent infrastructure comprising linear works installed (drainage channels, cable routes etc) would be likely to cause minor and local change to runoff patterns on the Site.



Medium Low Likely Moderate Temporary short-term construction activities within watercourses would be likely to cause a significant but temporary fundamental change in water quality in the immediate downstream environment.




Medium Low Rarely Moderate No permanent storage of oils, chemicals, or cementitious material associated with operational activities proposed within this catchment.

On-Site Eastern Tributary

(Local / Low)


Low Negligible Certain Moderate Increased runoff from impermeable infrastructure would cause a minor effect, however the effect is considered to be of low magnitude due to the proportional area of the receiving catchments affected being insignificant, and would therefore not affect the water use (in terms of normal water flows and frequency and magnitude of flooding).

Introducing structures (culverts) at one location within channels on-site within the Eastern Tributary Catchment would be likely to change or restrict channel capacity, with the potential to cause a detectable but minor and localised increase in flood risk / flood levels upstream of the structure (i.e. on the Site itself).

Temporary and permanent infrastructure comprising linear works installed (drainage channels, cable routes etc) would be likely to cause minor and local change to runoff patterns on the Site.









Effect Significance






Remaining point discharges of runoff to watercourse at unavoidable crossings would be likely to cause a significant but temporary fundamental change in water quality in the immediate downstream environment during construction phase, and a detectable but minor change in water quality during operation phase.



Medium Low Likely Moderate Spillage of oils, chemicals, or cementitious material associated with temporary construction and arising due to improper site management would be likely to cause a fundamental but temporary change in water quality in the downstream environment.


On-Site Southern Tributary

(Local / Low)


Low Negligible Certain Moderate No turbines or watercourse crossings proposed within this catchment.

Increased runoff from impermeable infrastructure would cause a minor effect, however the effect is considered to be of low magnitude due to the proportional area of the receiving catchments affected being insignificant, and would therefore not affect the water use (in terms of normal water flows and frequency and magnitude of flooding).

Temporary and permanent infrastructure comprising linear works installed (drainage channels, cable routes etc) would be likely to cause minor and local change to runoff patterns on site.







Medium Low Rarely Not Significant

No permanent storage of oils, chemicals, or cementitious material associated with operational activities proposed within this catchment.

On-Site Green Water

(Local / Low)


Low Negligible Certain Moderate Increased runoff from impermeable infrastructure would cause a minor effect, however the effect is considered to be of low magnitude due to the proportional area of the receiving catchments affected being insignificant, and would therefore not affect the water use (in terms of normal water flows and frequency and magnitude of flooding).

Introducing crossings at two locations within channels on-site within the Green Water Catchment would be likely to change or restrict channel capacity, with potential to cause a detectable but minor and localised increase flood risk / flood levels upstream of the structure (i.e. on the site itself).

Temporary and permanent infrastructure comprising linear works installed (drainage channels, cable routes etc) would be likely to cause minor and local change to runoff patterns on site.





Remaining point discharges of runoff to watercourse at unavoidable crossings would be likely to cause a significant but temporary fundamental change in water quality in the immediate downstream environment during construction phase, and a detectable but minor change in water quality during operation phase.



Medium Low Likely Moderate Spillage of oils, chemicals, or cementitious material associated with temporary construction and arising due to improper Site management would be likely to cause a fundamental but temporary change in water quality in the downstream environment.









Effect Significance




(Local / Low)

Alteration of Groundwater

Medium Low Unlikely Minor The nature of the Proposed Wind Farm Development has no potential to affect bedrock aquifers; no works are proposed that would require excavation to a significant depth within the bedrock. Significant dewatering with the potential for affecting groundwater levels is not anticipated.

Superficial aquifers are unlikely to be present, minor areas of glaciofluvial sand/gravel deposits were noted. Any dewatering would cause temporary insignificant change in the shallow water table of insignificant consequence due to the low / local value of the aquifer.

Chemical pollution of groundwater

Medium Low Likely Minor The majority of soils and sub soils (alluvium and till) are of low permeability and will generally mitigate through slow downward migration of pollution into deep groundwater. However a significant pollution event arising due to improper site management would be likely to cause detectable but temporary pollution to the aquifer. Significance is minor due to the low / local value of the aquifer.

Tracks, turbines and associated buildings.

(Local / Low)

Risk to occupants and infrastructure due to identified potential risk of flooding.

Low

Negligible Unlikely Not

Significant The Proposed Wind Farm Development has been designed to avoid areas of fluvial flooding and infrastructure is designed to be resilient to surface water flooding.

Risk to occupants due to identified risk of radon

Low Negligible Unlikely Not Significant

The proposed permanent substation has been located in an area of low radon potential and will be subject to a site specific radon survey to inform appropriate building mitigation.






Additional Mitigation Measures

All Phases

10.171 Additional mitigating measures over and above the avoidance and buffer zones previously

detailed are intended to reduce or prevent the residual significant hazards not fully

mitigated by the design evolution and avoidance, identified in the preceding Table: 10.22.

Site Drainage Management and SuDS Design

10.172 The Site will adopt a surface water management plan / site drainage design using the

principles of Sustainable Drainage, promoting the principles of on-site retention of flows and

use of buffers and other silt removal techniques. All drainage-related mitigation measures

proposed will be encompassed by a robust and proven Sustainable Drainage System (SuDS)

design which will be used to control drainage and silt management on the Site.

10.173 In summary, drainage will minimise modification and disruption of the existing hydrology by:

• Maintaining existing overland flow routes and channels. All existing natural flow paths

lateral to access roads will be maintained through the use of piped crossings under road

alignments at natural depressions and at regular intermediate intervals. The spacing of

cross drains will be specified at detailed design stage;

• Avoiding transporting rainfall runoff in long linear drainage swales by providing regular

channel “breakouts”, whereby water is encouraged to flow overland throughout the

Site, thus maintaining existing natural hydrological patterns;

• Reducing surface water flow rates and volumes by attenuating runoff from tracks and

hard standings “at source” by providing check-dams in swales, whereby the flow

velocity and rate of discharge is artificially reduced to mimic natural properties;

• Providing settlement ponds at turbine hard standing areas and other main surface water

discharge locations, where runoff from significant new impermeable areas is treated

and attenuated before being released overland;

• All swales, crossings and other hydraulic features will be engineered to ensure that

dimensions etc. are suitable to convey predicted flows and so prevent build-up of

surface water and / or flooding.

10.174 Drainage design will reduce chemical, silt and other suspended pollutant transport by

providing a “treatment train” of two to three stages of pollutant removal to all surface

water runoff, nominally by:

• Ensuring that drainage swales are designed to convey flows at a low velocity by using a

wide, flat bottomed drain;

• Providing settlement and filtration features in all linear drainage swales (check dams,

filtration dams) to reduce flow velocity and encourage settlement;

• Encouraging appropriate vegetation growth in the base of all linear drainage to provide

additional filtration to flows;

• Providing settlement ponds at turbine hard standing areas and other key discharge

locations in order to provide treatment to contaminated runoff prior to discharge;

• Discharging surface water runoff over undisturbed vegetated ground, hence allowing any

remaining silts and other pollutants to drop out of flows before entering the

watercourse (having the effect of polishing the runoff);

• Preventing the discharge of surface water runoff flows directly to existing watercourses

or drainage. All discharges are to be via SuDS and buffer zones which will act as a filter

strip, allowing deposition of suspended solids and other pollutants.

• Providing settlement features in water channels downstream of areas of peat infilling

and ditch blocking proposed as part of habitat management and enhancement planning.

10.175 Considerations specific to the proposed infrastructure elements are documented in the

detailed site specific drainage management / SuDS design - Technical Appendix 10.1:

Water Framework Directive Assessment and accompanying Drainage Management

Drawings.

Design and Construction of Watercourse Crossings

10.176 As noted previously, the number of watercourse and drainage crossings has been minimised

through the principle of avoidance at the layout design stage. Proposals submitted in

conjunction with this assessment indicate:

• Four crossings of hydrologically significant watercourses (two of which are considered

sensitive with respect to fisheries potential);

• Six crossings of minor watercourses.

10.177 Culverts will be designed to accommodate track crossings and minimise length of affected

channel in order to comply with Revised PPS15 policy FLD4.

10.178 Hydraulic design of crossings will be undertaken as per the guidance and requirements

provided in CIRIA C689 “Culvert Design and Operation Guide” (or other standard as may be

required by Rivers Agency in post-consent consultation), with primary parameters likely to

include:

• Width of the culvert will be greater than the width of the active drainage channel;

• Alignment of the culvert will suit the alignment of the drainage channel, i.e. preserve

the existing direction of flow;

• The slope of the culvert will not exceed the slope of the bed of the existing drainage

channel.

10.179 Detailed design of crossings will assume a hydraulic capacity requirement of 1% Annual

Equivalent Probability flow as a conservative measure. Detailed hydraulic design of culverts

and similar structures post permission is normal and accepted practice for wind farms in

Northern Ireland.






10.180 Fisheries shall be protected by adopting the guidance stated in Guidelines for Fisheries

Protection during Development Works as published by Loughs Agency (adopted in the

absence of specific guidance published by DCAL as the statutory agency with remit for

fisheries protection for the region affected).

10.181 Culvert form will be informed by the site specific fisheries assessment (Chapter 9:

Fisheries). In the two instances where fish passage is a requirement (crossing of Knockoneill

River and Central Tributary), culverts will be designed to ensure that the channel bed and

banks remain intact in order to preserve fisheries habitats and allow continued fish passage;

i.e. the structure will be a bottomless culvert. Elsewhere culverts shall be of a closed

conduit type. Typical design drawings for a bottomless culvert and closed culvert have been

provided as part of the planning application and are included as part of the Drainage

Management Drawings within Technical Appendix 10.1: Water Framework Directive

Assessment.

10.182 Consultation and approval will be sought from all relevant parties as required by the

Department of the Environment Surface Waters Alteration Handbook (December 2013),

including Rivers Agency in particular, at the pre-construction detailed design stage for all

works in and affecting watercourses and drains, as per the requirements of Schedule 6 of

the Drainage (Northern Ireland) Order 1973 and subsequent amendments.

Water Quality Monitoring

10.183 A water quality monitoring program will be implemented to monitor effects on the

hydrological and groundwater regime and water quality during the infrastructure

construction, operation and decommissioning phases of the wind farm in order to:

• Demonstrate that the mitigation measures and surface water management is performing

as designed;

• Provide validation that the in-place mitigation measures are not having an adverse

effect upon the environment;

• Indicate the need for additional mitigation measures to prevent, reduce or remove any

effects on the water environment, such as additional temporary settlement or filtration

structures or short term flocculant dosing to suit observed Site conditions.

10.184 The monitoring would be informed by existing baseline data gathered at the pre-planning

stage as presented in the baseline Section 10.78 of this assessment.

10.185 It is intended that the water monitoring extent, duration and frequency will be agreed with

the DOE Planning or the relevant regulating body (nominally NIEA WMU) post consent and

will nominally consist of physicochemical and biological monitoring. The extent, duration

and frequency of the monitoring will be proportionate to the level of activity and perceived

risks.

Construction and Decommissioning Phases

10.186 During all phases the site manager will ensure that mitigation measures as identified within

this assessment are fully implemented and that activities are carried out in such a manner

as to prevent or reduce effects. The following construction / decommissioning phase-

specific measures will be implemented. The following sections should be read in

conjunction with the construction management information provided within Chapter 2:

Proposed Development.

Pollution Prevention Guidance

10.187 To ensure best practice on site and to help avoid pollution release to watercourses and

groundwater, the following NIEA Pollution Prevention Guidance (PPGs) will be adhered to:

• PPG01 Understanding Your Environmental Responsibilities - Good Environmental

Practices

• PPG02 Above Ground Oil Storage Tanks

• PPG03 Use and Design of Oil Separators in Surface Water Drainage Systems

• PPG04 Treatment and Disposal of Sewage where no Foul Sewer is available

• PPG05 Works and Maintenance in or near Water

• PPG06 Working at Construction and Demolition Sites

• PPG07 Refuelling Facilities

• PPG18 Managing Fire Water and Major Spillages

• PPG20 Dewatering Underground Ducts and Chambers

• PPG21 Pollution Incident Response Planning

• PPG26 Drums and Intermediate Bulk Containers.

10.188 Key requirements for control of chemical pollution risk are identified in the above guidance

and will include the following:

• Storage – all equipment, materials and chemicals on the Site will be stored away from

any watercourse (i.e. outwith previously stated buffer zones). Chemical, fuel and oil

stores will be sited on impervious bases in accordance with PPG2 and within a secured

bund of 110% of the storage capacity, within the lay down area.

• Vehicles and refuelling – standing machinery will have drip trays placed underneath to

prevent oil and fuel leaks causing pollution. Refuelling of vehicles and machinery will be

carried out on an impermeable surface in designated areas, well away from any

watercourse or drainage ditches (i.e. outwith previously stated buffer zones) and will

adhere to best practice as detailed in PPG7.

• Maintenance – on site maintenance to construction plant will be avoided in all

practicable instances, unless vehicles have broken down necessitating maintenance at

the point of breakdown. Suitable measures in accordance with a pollution prevention

plan will be put in place prior to commencement of maintenance in this instance.

• Cement and concrete batching – Preference shall be given to construction techniques

that do not require use of cementitious materials where suitable practicable






alternatives exist. When concrete / cement are used, concrete batching will not be

permitted on Site. Wet concrete operations will not be carried out within watercourses

or adjacent to watercourses. Measures to prevent discharge of alkaline wastewaters or

contaminated storm water to watercourses will be outlined in a detailed Pollution

Prevention Plan for the Site to be approved by NIEA before commencement of works.

Wastewater spillage will be minimised by using settling tanks and recycling water.

• Mess and welfare facilities will be required during construction and decommissioning

and will be located at the construction compound. Foul effluent disposal shall be via

chemical facilities with periodic tankered removal by a licensed waste haulier for

licensed offsite disposal (i.e. there shall be no emission on Site).

Pollution Prevention Plan

10.189 A detailed Pollution Prevention Plan (PPP) will be implemented and monitored by the site

manager as part of a full Construction & Decommissioning Method Statement (CDMS) for the

project, to be agreed with DOE Planning at the pre-construction stage. Although this will be

of particular importance during construction, it will apply to potentially polluting activities

during all phases of the Proposed Wind Farm Development.

10.190 The detailed PPP will be produced following consultation and agreement with NIEA, and all

appropriate personnel working on the Site will be trained in its use. As a minimum, the PPP

will comply with Pollution Prevention Guidelines (in particular PPG21: Pollution Incident

Response Planning) and best practice as advocated by CIRIA. The PPP will identify site-

specific measures and incorporate a Pollution Incident Plan, which will include emergency

contact details, details of spill kits on the Site and instructions on actions in case of spillage

/ emergency.

Construction in the vicinity of Watercourses

10.191 The following procedures apply to the general construction activities either within the

watercourses or in defined watercourse buffer zones:

• Due consideration will be given to the prevailing ground and weather conditions when

programming the execution of the works in order to ensure that in-channel works are

undertaken during periods of predicted low flow and low rainfall in order to minimise

contact with water.

• Ensure that roadside drains do not discharge directly into watercourses, but rather

through a riparian buffer area of intact vegetation as denoted on design drawings.

Construction of Watercourse Crossings

10.192 Measures for in-stream works including watercourse crossings will be as per the guidance

stated in Guidelines for Fisheries Protection during Development Works as published by

Loughs Agency (adopted in the absence of specific guidance published by DCAL as the

statutory agency with remit for fisheries protection for the region affected).

10.193 Construction of watercourse crossings will be programmed to coincide with periods of

predicted low flow in the affected channel (determined by rainfall and would generally

coincide with summer months) and adhere to working period restrictions imposed.

Construction will be strictly as per the design for each identified watercourse crossing and

will fully implement all SuDS and additional mitigating measures proposed at the detailed

design stage. For purposes of outline design, the proposed mitigation will include:

• Installation of silt fences parallel to the watercourse channel in the vicinity of the

proposed crossing;

• Installation of small cut-off drains to prevent natural surface runoff entering area of

construction activity;

• Installation of filtration or other silt entraining features within the watercourse channel

immediately downstream of the works location;

• Use of over pumping where deemed appropriate.

Electrical Cable

10.194 Due consideration will be given to the prevailing ground conditions and season when

programming the execution of cable trench excavations in order to ensure works are

undertaken during periods with predicted low rainfall and elevated shallow groundwater

levels in order to reduce the likelihood of runoff entering the excavations.

10.195 Excavation of cable trenches will be carried out over short distances, with frequent

backfilling of trenches to minimise opportunity for the ingress of water into open trenches,

temporary silt traps will be provided in longer trench runs and on steeper slopes and spoil

will be stored in line with a spoil management plan, which will be produced as part of the

CDMS at the pre-construction stage.

10.196 Cable crossings of watercourses shall use a raised cable tray to bridge the river channel,

with supports and footings constructed outwith the river channel. No plant shall be

permitted within watercourse channels when undertaking such works.

Excavations and Spoil Management

10.197 Soil and subsoil excavation and movement will be undertaken in accordance with best

practice guidelines such as Good Practice Guide for Handling Soils (MAFF, 2000) in order to

minimise potential for silt laden runoff from spoil and excavations. Areas of stockpiled spoil

including stored peat:

• will not be permitted within previously identified watercourse buffer zones; and

• will not be permitted to obstruct the flow of overland surface water with specific

drainage to spoil mounds to be provided.

10.198 Material produced from excavations on the Site will be reused where reasonably practicable

in the reinstatement of the Site. Excavated materials will be separated into rock material,

subsoil, reusable peat and vegetated sod material and will be stored in the designated

temporary stockpile zones, under the supervision of a geotechnical expert. These materials






will be reused where possible to re-grade slopes, and to re-vegetate and stabilise the sides

of access tracks and hard standing areas.

10.199 Spoil drainage will be designed on a bespoke basis for spoil storage areas to allow controlled

dewatering and prevent washout of suspended solids to the receiving water environment.

As part of the detailed CDMS a spoil management strategy will be developed by the

appointed competent contractor for the development. Outline designs for drainage

arrangements for temporary spoil areas are shown on the Drainage Management Drawings

within Technical Appendix 10.1: Water Framework Directive Assessment.

Ditch Blocking and Peat Placement for Habitat Enhancement

10.200 In the Outline Habitat Management Plan (Technical Appendix 6.7) areas for ditch blocking

and areas of re-profiling using excavated peat have been proposed in areas where the effect

could have no offsite hydrological effect (by raising water levels or impeding drainage such

that water would divert or back-up onto 3rd party lands). The effect of impeded drainage

would be limited to lands under control of the applicant. Drainage channels affected have

been determined not to be of significant aquatic habitat value.

10.201 It is anticipated that ditch blocking methods would depend upon local conditions at any

given location. A number of techniques for maintaining the water levels in the drains

associated with the flushes may be used and would typically comprise the installation of a

barrier (e.g. (piled) plastic corrugated sheets or drop board sluice or installation of pipe

dams, in conjunction with backfilling with site-won peat). Methods will comply with best

practice guidance12.

10.202 Downstream water quality that may otherwise be affected by release of peat in runoff

would be protected by adopting spoil handling methods as set out in Sections 10.197 to

10.199. In particular, the channel(s) downstream of the blocked areas would have

temporary filtration features (i.e. silt fences or clean drainage stone dams) installed in the

channel in order to filter or settle solids, until such time as the level of washout had

receded.

Dewatering of Excavations

10.203 Turbine base foundations will be on bedrock or other hard strata above bedrock (to be

confirmed by detailed site investigation prior to detailed design); therefore deep

excavations within bedrock and the associated bedrock aquifer are not anticipated and

dewatering below the bedrock aquifer groundwater table is therefore not anticipated.

10.204 Shallow groundwater (e.g. in areas of glaciofluvial sand/gravel deposits) or rainfall runoff

collected in excavations will be discharged via settlement ponds or filter strips prior to

entry to the receiving water environment. Any settlement lagoons or filter strips associated

with dewatering will be regularly inspected, particularly after periods of heavy rainfall and

12 Armstrong A1, Holden J, Kay P, Foulger M, Gledhill S, McDonald AT, Walker A.. (2009). Drain-blocking techniques on blanket peat: A framework for best practice. Journal for Environmental Managers. Vol. 90

prior to periods of forecast heavy rainfall. Maintenance (to clear blockages or remove silt)

will be carried out in periods of dry weather where practicable. Maintenance requirements

are further considered in Technical Appendix 10.1: Water Framework Directive

Assessment.

Dust Management

10.205 Loose track material generated during the use of access tracks and the construction

compound will be prevented from reaching watercourses by maintenance to surface water

drainage systems installed at aggregate based hard standing areas. In dry weather dust

suppression methods such as by dust suppression bowser will be employed.

Borrow Pits

10.206 For the avoidance of doubt, no borrow pits are proposed at the Site, therefore associated

pollution risks associated with rock extraction activities are not a consideration.

Maintenance of Pollution Prevention Measures

10.207 All SuDS and additional pollution prevention measures installed will be subject to a regular

maintenance regime for the life of the construction phase in order to maintain functionality

of all features. This will comprise:

• Unblocking of drains;

• Maintenance of access road and other hard standing surfaces;

• Replacement of filtration features;

• Removal of silt build-up from settlement and filtration features.

Mitigating Measures - Operational Phase

10.208 Mitigation of the effects of the wind farm development will comprise the following:

• Ensure best practice is adhered to on the Site and avoid pollution release to

watercourses by incorporating NIEA Pollution Prevention Guidance notes into

management policy.

• In the event that permanent welfare facilities are installed as part of control building /

substation facilities, foul effluent will be disposed of through the use of sealed cesspools

or chemical facilities with periodic tankered removal by a licensed waste haulier for

licensed offsite disposal (i.e. there shall be no emission on the Site).

• Cyclical maintenance of permanent SuDS drainage features installed during the

construction phase, including unblocking of drains, maintenance of access road and

other hard standing surfaces, and removal of silt build-up from settlement features. An

outline maintenance programme is included in Technical Appendix 10.1: Water

Framework Directive Assessment.






Commentary on Proposed Development

Off-Site Route Improvement Works

10.209 Information made available in relation to route improvement works outlined the

requirement for widening at two junctions, eight passing bays and general running width

widening along Corlacky Road to permit abnormal deliveries.

10.210 Details of the assessment of potential impact of access works on the geology and water

environment are included within Chapter 12: Traffic and Transport. The desktop

assessment concluded that given the short duration of construction and limited localised

areas of disturbance proposed during the route improvement works it is considered that

there would be no significant effect to geology or the water and environment.

On-Site Works

10.211 Table 10.22 summarises the potential impact of infrastructure to be installed as part of the

Proposed Wind Farm Development following adoption of the preceding mitigation for the

design phase. All turbines and infrastructure are outside the recommended buffers (aside

from watercourse crossings) as described in Chapter 3: Design Evolution & Alternatives.

Table 10.22: Commentary on Infrastructure Elements

Infrastructure Element

Commentary / Specific Mitigation Implemented Mitigated Impact

Magnitude

Access Track Track is orientated in accordance with the guidance provided by the peat slide risk assessment for the Site, minimising risks to the soil and water environment.

Track is orientated to cause least possible disruption by crossing watercourses perpendicular to the watercourse channel.

Track is aligned to minimise constructed length within watercourse buffer zones.

Runoff from track hardstanding to be attenuated and treated in trackside swales / check dams.

All existing watercourse paths to be maintained; culverts to be designed to ensure no restriction or diversion to flows.

Minor / Negligible

Permanent Control room & Substation Compound

Contaminated runoff from excavations, hardstanding and roof areas will be treated to remove silts / suspended solids as part of the drainage management plan for the Site using SuDS techniques prior to discharge.

Runoff from new hardstanding and roof areas will be managed using SuDS techniques to attenuate, control and treat flows.

Located >65 m from nearest watercourse.

Permanent chemical welfare facilities to be provided to negate requirement for any foul effluent discharge from the Site.

Minor / Negligible

Temporary Enabling Works Compound



Located >60m from nearest watercourse.

Minor / Negligible

Infrastructure Element

Commentary / Specific Mitigation Implemented Mitigated Impact

Magnitude

Temporary Construction Compound



Located >65 m from nearest watercourse.

Oil containment facility to be provided.

Temporary chemical welfare facilities to be provided to negate requirement for any foul effluent discharge from the Site.

Minor / Negligible

All Turbines Contaminated runoff from excavations and earthworks will be treated to remove silts / suspended solids as part of the drainage management plan for the Site using SuDS techniques prior to discharge.

Runoff from new hardstanding areas will be managed using SuDS techniques to attenuate, control and treat flows.

Turbine foundation formation level is bedrock; no requirement for piled foundations or excavation in bedrock, with associated increased risk to aquifer, Is anticipated.

Minor / Negligible

T1 Turbine base and associated crane pad located >60 m from nearest watercourse.

Minor / Negligible

T2 Turbine base located > 60 m from nearest watercourse and associated crane pad located > 30 m from nearest minor watercourse.

Minor / Negligible

T3 Turbine base and associated crane pad located > 50 m from nearest watercourse.

Minor / Negligible


Minor / Negligible


Minor / Negligible


Minor / Negligible


Minor / Negligible


Minor / Negligible


Minor / Negligible

T10 Turbine base and associated crane pad located > 30 m from nearest minor watercourse.

Minor / Negligible


Minor / Negligible






11.9.6 Mitigating Measures and Residual Effects

10.212 The following table details the assessed impact magnitude, likelihood and associated

significance as a function of the matrix stated previously of all receptors identified as

previously having an unmitigated impact significance greater than ‘nil’ or ‘not significant’.

10.213 Note that assessment of peat slide and blanket bog impacts are excluded from this

assessment and are assessed separately in Technical Appendix 10.4: Peat Slide Risk

Assessment and Chapter 6: Vegetation & Peatland.






Table 10.23: Potential Magnitude and Significance of Impacts to Receptors (Post-Mitigation)

Receptor and Sensitivity Effect and Mitigated Magnitude Potential Effect

Significance Likelihood

Overall Mitigated Effect Significance

Rationale

Soils / Drift Deposits

(Local / Low)

Ground Instability Low Negligible Rarely Not Significant Infrastructure designed to incorporate Peat Stability; Land slip potential is considered Negligible.

On-Site / Downstream Knockoneill River

Central Tributary

(Regional / Medium)


Low Low Rarely Not Significant Surface water runoff from the Site will not cause a change in downstream hydrological conditions following mitigation to attenuate site runoff.

Sympathetic design of infrastructure layout in relation to disruption / diversion of existing surface water and overland runoff routes results in no quantifiable change in runoff patterns on the Site.


Low Low Rarely Not Significant Surface water management to control silt in proximity to watercourses at all phases is likely to result in no permanent change and no significant temporary change in conditions exceeding natural or pre-existing conditions.


Low Low Rarely Not Significant Pollution prevention measures proposed to control chemical pollution at all phases is likely to result in no permanent or temporary change in conditions exceeding natural or pre-existing conditions.

On-Site Northern, Eastern and Southern Tributaries

(Local / Low)


Low Negligible Rarely Not Significant Surface water runoff from the Site will not cause a change in downstream hydrological conditions following mitigation to attenuate site runoff.



Low Negligible Rarely Not Significant Surface water management to control silt in proximity to watercourses at all phases is likely to result in no permanent change and no significant temporary change in conditions exceeding natural or pre-existing conditions.


Low Negligible Rarely Not Significant Pollution prevention measures proposed to control chemical pollution at all phases is likely to result in no permanent or temporary change in conditions exceeding natural or pre-existing conditions.

On-Site Green Water

(Local / Low)


Low Negligible Rarely Not Significant Surface water runoff from the Site will not cause a change in downstream hydrological conditions following mitigation to attenuate site runoff.



Low Negligible Rarely Not Significant Surface water management to control silt in proximity to watercourses at all phases is likely to result in no permanent change and no significant temporary change in conditions exceeding natural or pre-existing conditions.


Low Negligible Rarely Not Significant Pollution prevention measures proposed to control chemical pollution at all phases is likely to result in no permanent or temporary change in conditions exceeding natural or pre-existing conditions.


(Local / Low)

Alteration of Groundwater Medium Low Rarely Not Significant Deep excavations within bedrock and the associated bedrock aquifer are not anticipated and dewatering below the bedrock aquifer groundwater table is not anticipated.

Chemical pollution of groundwater

Low Negligible Rarely Not Significant Pollution prevention measures at all phases is likely to result in no permanent or temporary change in conditions exceeding natural or pre-existing conditions.






Cumulative Effects

10.214 An assessment has been undertaken of the cumulative effect on geology and the water

environment of the Proposed Corlacky Hill Wind Farm in conjunction with other known wind

farms and other significant developments in planning, construction or operation at the time

of the application.

10.215 The assessment aims to determine potential for cumulative impact within the hydrological

and hydrogeological setting of the Site caused by an accumulation of similar developments.

The hydrological and hydrogeological setting of the Site for the purposes of the assessment

is the downstream Knockoneill River, Beagh River and Clady River catchments as identified

on the NIEA Water Framework Directive interactive catchment mapping website and shown

on Figure 10.5: Cumulative Assessment.

10.216 Coordinates of wind farms within 40 km of the Proposed Corlacky Hill Wind Farm

Development were provided; two developments outlined within Table 10.24 were identified

within a similar hydrological catchment to the Proposed Corlacky Hill Wind Farm. Single

turbine wind developments are excluded as not having potential to significantly adversely

affect the water or geological environment individually or cumulatively.

Table 10.24: Cumulative Assessment

Wind Farm Centroid No. Of

Turbines Status

Distance between nearest Turbines

Brockaghboy E281035 , N410865 15 Consented 0.9 km

Brockaghboy Extension E281614 , N409345 4 Consented 1.4 km

10.217 Areas of the Brockaghboy and Brockaghboy Extension sites drain towards the Knockoneill

River via the Green Water and an unnamed tributary; discharging to the Knockoneill River at

two locations along the Knockoneill Road approximately 350 m and 1.5 km downstream of

the Site as shown on Figure 10.5: Cumulative Assessment.

10.218 As no likely significant residual water environment or geological effects are predicted

arising from the development of the Proposed Corlacky Hill Wind Farm, there is no potential

significant cumulative effect to water or the geological environment in conjunction with any

other pre-existing or proposed development.

Summary and Conclusions

10.219 This assessment identifies the potential geological, hydrological, and hydrogeological

impacts, including surface and groundwater quality of the Proposed Wind Farm

Development. It summarises the relevant legislation and guidance and provides appropriate

baseline information, enabling the potential effects to be identified.

10.220 Aspects of the design, construction and operation of the Proposed Wind Farm Development

that may potentially impact on the receiving geological and water environment have been

identified and the pathways for impacts assessed. It has been determined that without

mitigation the Proposed Wind Farm Development would be likely to cause adverse impacts

of moderate significance primarily driven by the sensitivity of fisheries interests on and

shortly downstream of the Site. As such, informed by the baseline assessment and pathways

identified, mitigation integrated as part of outline design and proposed during construction

phase includes:

• Avoidance of water features based on baseline constraints mapping;

• Design of site elements to minimise impact on the geological and water environment;

• Implementation of a comprehensive surface water management plan comprising the use

of SuDS (drainage) and silt management in order to prevent pathways for pollution;

• Construction phase pollution prevention procedures in accordance with NIEA

requirements and guidance.

10.221 Monitoring of the effect of the Proposed Wind Farm Development on the water environment

and fisheries habitat will be provided through physicochemical and biological water quality

monitoring. Implementation of the mitigation proposed eliminates or reduces the potential

significance to all receptors to “not significant”.

10.222 There is no likelihood of significant cumulative impacts over and above any pre-existing

effect caused by existing or consented wind development.






List of References, Figures and Appendices

References

British Geological Society (1996) Hydrogeology of Northern Ireland.

British Geological Society (2005) EU Water Framework Directive: groundwater-dependent terrestrial ecosystems in Northern Ireland. Available: http://nora.nerc.ac.uk/11263/1/CR05069N.pdf [Accessed 08/02/2016]

Centre for Hydrology and Ecology Wallingford (2009), Flood Estimation Handbook and Associated Software Version 3.

CIRIA (1997) Culvert Design Guide Report No. C168; Construction Industry Research and Information Association, London.

CIRIA (2006) Control of Water Pollution from Linear Construction Projects, Report No C648, Construction Industry Research and Information Association.

CIRIA (2006) Control of Water Pollution from Linear Construction Projects - Site guide. Report No C649, Construction Industry Research and Information Association.

CIRIA (2007) The SUDS Manual, Report No C697, Construction Industry Research and Information Association.

CIRIA (2010) Culvert Design and Operation Guide Report No. C689; Construction Industry Research and Information Association.

CIRIA, Wilson, S., Bray, R. And Cooper, P. (2004), Sustainable Drainage Systems – Hydraulic, Structural and Water Quality Advice Report No. C609.

Cruickshank (1997) Soil and Environment: Northern Ireland.

Department of Agriculture and Rural Development and Rivers Agency (2014), Flood Maps (NI). Available : http://riversagency.maps.arcgis.com/apps/webappviewer/index.html?id=fd6c0a01b07840269a50a2f596b3daf6 [Accessed 08/02/2016]

Department of Enterprise Trade and Investment (2016) Mining and Exploration Activity. Available: https://www.detini.gov.uk/sites/default/files/publications/deti/1601-Minerals-License-Map_4.pdf [Accessed 08/02/2016]

Department of the Environment for Northern Ireland (1993), River and Estuary Quality in Northern Ireland: Report of the 1991 Survey.

Environment and Heritage Service and National Museums and Galleries of Northern Ireland (Unknown), Geological Sites in Northern Ireland - Earth Science Conservation Review. Available: http://www.habitas.org.uk/escr/ [Accessed 08/02/2016]

Geological Survey of Northern Ireland (1997) 1:250,000 Solid Geology map of Northern Ireland 2nd Edition.

Geological Survey of Northern Ireland (2001) 1:50,000 Bedrock Geology Map (Sheet 19: Maghera).

Geological Survey of Northern Ireland (2001) 1:50,000 Superficial Geology Map (Sheet 19: Maghera).

Geological Survey of Northern Ireland (2010) GeoIndex. Available: http://mapapps2.bgs.ac.uk/GSNI_Geoindex/home.html [Accessed 08/02/2016]

Geological Survey of Northern Ireland (2014) Minerals Promotion Pack. Available: https://www.bgs.ac.uk/gsni/minerals/downloads/GSNIFlyers.pdf [Accessed 08/02/2016]

Highways Agency (2006) Design Manual for Roads and Bridges Volume 4, Section 2: Drainage.

Holden, J., Kirkby, M.J., Lane, S.N., Milledge, D.G., Brookes, C.J., Holden, V. And McDonald, A.T. (2008), Water Resources Research, Volume 44 (6) - Overland flow velocity and roughness properties in peatlands.

Met Office (2014) UK Mapped Climate Averages. Available: http://www.metoffice.gov.uk/climate/uk/averages/ukmapavge.html [Accessed 08/02/2016]

Ministry of Agriculture, Fisheries and Food (1988) Land Classification in England and Wales. Available:

http://webarchive.nationalarchives.gov.uk/20130402151656/http://archive.defra.gov.uk/foodfarm/landmanage/land-use/documents/alc-guidelines-1988.pdf [Accessed 08/02/2016]

Natural Environment Research Council (1974) Flood Studies Report.

Northern Ireland Environment Agency (2009) GQA Biological Classification System. Available: http://www.ni-environment.gov.uk/water-home/quality/rivers/river_results/gqabiolexpln.htm [Accessed 26/06/2015]

Northern Ireland Environment Agency (2009) GQA Chemical Classification System. Available: http://www.ni-environment.gov.uk/water/quality/rivers/river_results/gqachemexpln.htm [Accessed 26/06/2015]

Northern Ireland Environment Agency (2009) River Monitoring Results. Available: http://www.ni-environment.gov.uk/water-home/quality/rivers [Accessed 26/06/2015]

Northern Ireland Environment Agency (2010) River Basin Plan Interactive Map. Available: http://maps.ehsni.gov.uk/wmuviewer/ [Accessed 08/02/2016]

Northern Ireland Environment Agency (2015) Wind Farms and Groundwater Impacts: A Guide to EIA and Planning Considerations. Available: http://www.planningni.gov.uk/index/advice/northern_ireland_environment_agency_guidance/wind_farms_and_groundwater_impacts-3.pdf [Accessed 08/02/2016]

Office of Public Sector Information (1973) Drainage (Northern Ireland) Order.

Public Health England (2015) UK Radon Action Level Map. Available: http://www.ukradon.org/information/ukmaps [Accessed 08/02/2016]

Rivers Agency (Unknown) Estimation of Flood Peaks in Northern Ireland Rivers from Catchment Characteristics - Rivers Agency Design Note.

Rivers Agency (2014) Map of Designations Approved by Drainage Council (NI). Available: http://riversagency.maps.arcgis.com/apps/webappviewer/index.html?id=28b901c557054dd488953180d2309903 [Accessed 08/02/2016]

Scottish Executive (2000) River Crossing and Migratory Fish: Design Guidance.

Wallingford (1994) Flood Estimation for Small Catchments - Institute of Hydrology Report No IH124.

Additional references identified in specific footnotes.

Figures

• Figure 10.1: Site Hydrology

• Figure 10.2: Abstraction Locations

• Figure 10.3: Water Quality Monitoring

• Figure 10.4: Designated Sites

• Figure 10.5: Cumulative Assessment

Appendices

• Appendix 10.1: Water Framework Directive Assessment and Drainage Management

Drawings

• Appendix 10.2: Consultation Responses

• Appendix 10.3: Abstraction Records

• Appendix 10.4: Peat Slide Risk Assessment

• Appendix 10.5: Draft Peat Management Plan

http://nora.nerc.ac.uk/11263/1/CR05069N.pdf

http://www.habitas.org.uk/escr/

http://www.metoffice.gov.uk/climate/uk/averages/ukmapavge.html

http://webarchive.nationalarchives.gov.uk/20130402151656/http:/archive.defra.gov.uk/foodfarm/landmanage/land-use/documents/alc-guidelines-1988.pdf

http://webarchive.nationalarchives.gov.uk/20130402151656/http:/archive.defra.gov.uk/foodfarm/landmanage/land-use/documents/alc-guidelines-1988.pdf

http://www.ni-environment.gov.uk/water-home/quality/rivers/river_results/gqabiolexpln.htm

http://www.ni-environment.gov.uk/water/quality/rivers/river_results/gqachemexpln.htm

http://www.ni-environment.gov.uk/water-home/quality/rivers

http://www.ni-environment.gov.uk/water-home/quality/rivers

http://maps.ehsni.gov.uk/wmuviewer/



http://www.opsi.gov.uk/psi/






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