HYDROGEOLOGY AND HYDROLOGY 13 - Über innogy · 13.1 This Chapter assesses the impacts of the proposed evelopment on d hydrogeology and hydrology (the water environment). The assessment

HYDROGEOLOGY AND HYDROLOGY 13

CONTENTS Introduction .............................................................................................................. 13-1 Approach and Methods ............................................................................................ 13-1

Study Area ........................................................................................................... 13-1 Effects Assessed in Full ....................................................................................... 13-2 Effects Scoped Out .............................................................................................. 13-2 Assessment Structure .......................................................................................... 13-3 Data Sources and Guidance ................................................................................ 13-4 Field Survey ......................................................................................................... 13-5 Consultation ......................................................................................................... 13-6 Good Practice Measures and Mitigation ............................................................ 13-11 Assessing Significance....................................................................................... 13-12 Residual Effects ................................................................................................. 13-15 Cumulative Effects Assessment ......................................................................... 13-15 Statement of Significance................................................................................... 13-16

Baseline Conditions ............................................................................................... 13-16 Hydrogeology ..................................................................................................... 13-16 Local Hydrology ................................................................................................. 13-24

Assessment of Effects ........................................................................................... 13-37 The Proposed Development Layout Considerations .......................................... 13-37 Good Practice Measures .................................................................................... 13-38 Construction Effects of the Proposed Development ........................................... 13-43 Operational Effects of Proposed Development .................................................. 13-48 Cumulative Effects Assessment ......................................................................... 13-50 Further Survey Requirements and Monitoring (if required) ................................ 13-50 Summary of Effects ............................................................................................ 13-51


HARRYBURN P a g e | 13-1 SLR Consulting Limited

INTRODUCTION

13.1 This Chapter assesses the impacts of the proposed development on hydrogeology and hydrology (the water environment). The assessment of impacts has been made on the basis of the proposed turbine and infrastructure layout as fully described in Chapter 3: Description of the Development.

13.2 It details the assessment undertaken to determine the potential effects of construction and operation of the proposed development on the current baseline hydrological and hydrogeological regimes (forming the water environment). It outlines the embedded good practice methods which have been incorporated into the design, and would be used during the construction and operation of the proposed development to prevent or reduce identified effects and risks.

13.3 Further mitigation methods to address any potential effects are proposed, where appropriate, and residual effects assessed.

13.4 This Chapter uses data and information presented in Chapter 11: Geology

and Peat to assess potential effects on peat and the effects of previous mining activity on the water environment.

13.5 In addition the assessment uses information and findings presented in

Chapter 9: Ecology to inform the assessment of potential effects on possible areas of Groundwater Dependent Terrestrial Ecosystems (GWDTEs) presented in this Chapter.

13.6 This Chapter should be read in conjunction with Chapter 2: Site Description

and Design Evolution, Chapter 5: Environmental Impact Assessment and Chapter 9: Ecology. Planning policies of relevance to this assessment are outlined in Chapter 4: Renewable Energy and Planning Policy.

APPROACH AND METHODS

Study Area

13.7 The ‘study area’ includes all of the proposed Site infrastructure. In addition, details of local water use and quality within a buffer of at least 5km from the proposed infrastructure have been considered. The Study Area encompasses the Site as well as bodies of water and their catchments which could potentially be affected by the construction and operation of the proposed development.

13.8 The study area for potential cumulative effects uses the catchments within the study area, with a maximum downstream distance of 5km from the proposed infrastructure. Beyond this 5km distance, any effect is considered to be so diminished as to be undetectable and therefore not significant.



Effects Assessed in Full

13.9 The following potential effects have been assessed in full:

• pollution risk, including potential effects on surface water and groundwater quality and public and private water supplies during construction and operation of the proposed development;

• erosion and sedimentation which could give rise to potential effects on surface water and groundwater quality and public and private water supplies during construction and operation of the proposed development;

• fluvial flood risk resulting from changes to runoff volumes and rates and modifications to natural and man-made drainage patterns during operation of the proposed development;

• potential effects upon the linkage between groundwater and surface water during construction and operation of the proposed development;

• potential effects on areas of possible GWDTE during construction and operation; and

• potential cumulative effects during construction and operation.

Effects Scoped Out

13.10 On the basis of the desk based and survey work undertaken, policy, guidance and standards, the professional judgement of the Environmental Impact Assessment (EIA) team, feedback from consultees and experience from other relevant projects, the following topic areas have been ‘scoped out’: • Increased flood risk caused by blockages to flow in watercourses during

operation and maintenance of the proposed development. These crossings would be subject to maintenance requirements under the Controlled Activities Regulations (CAR), flood risk onsite is negligible and the Development design ensures no critical infrastructure is located near watercourses.

• Increased flood risk during the operational phase as measures to control and manage potential increases in the rate and volume of runoff shed from site would be established during the construction phase of the proposed development. These measures would be subject to routine inspection during the operational phase of the development.

• Changes to public/private water supply yield as a consequence of changes to runoff rates and volumes during operation and maintenance of the proposed development as no significant alterations to runoff rates/infiltration or drawdown of the water table are anticipated during or as a consequence of construction.

• Potential cumulative effects in relation to public/private water supply yields during the operational phase as water requirements are low during operation and any change would not be discernible at the catchment level.

13.11 Areas covered by the proposed habitat management plan have also been

scoped out of the assessment as the proposals relate to land management approaches and practices that are common best practice (see Chapter 9:



Ecology). The assessment considers the proposed wind farm and its enabling infrastructure only.

Assessment Structure

13.12 The assessments of both the construction and operational phases have been structured around the consideration of the following potential effects on receptors: • pollution risk: potential effects on surface water and groundwater quality;

public and private water supplies; • erosion and sedimentation: potential effects on surface water and

groundwater quality; public and private water supplies; • fluvial flood risk: potential effects on flood risk both to the proposed

development and offsite effects during the operational phase only; • infrastructure and man-made drainage: potential effects on surface and

sub-surface drainage patterns (which could directly feed GWDTEs across the Site); and

• cumulative effects: potential effects of the proposed development in combination with those from other developments within the hydrological study area.

13.13 The contamination of surface water and groundwater caused by leakage and

spills of chemicals from vehicle use and construction and operational activities has the potential to lead to a pollution event. Deterioration of the quality of either surface water or groundwater may cause a potential effect on the status of the receiving water bodies and any public or private water supplies. The effects are assessed, using professional judgement, in terms of the frequency and duration of activities that have the potential to cause pollution together with the nature of the potential pathways linking the source of pollution to a receptor(s). The length of the pathway is a key factor in determining the risk of contamination with particular attention given to the potential occurrence of direct pollution to water bodies.

13.14 The potential for erosion and sedimentation mainly occurs during the construction phase of the proposed development. Potential causes include the transfer of sediment during rainfall events from exposed ground or stockpiled materials entering the watercourses. This can cause blockages in watercourses as well as a deterioration of water quality. The effects are assessed in the same way as for contamination events. The potential for an activity to cause erosion or sedimentation is based on a combination of the type of land cover, the nature of the activity, experience from other relevant projects, professional judgement and relevant guidance.

13.15 Increases in the potential flood risk to a receptor would be localised, resulting from increased runoff from areas of hardstanding, compacted ground or due to the under-sizing of water crossings. The effects are assessed using the good practice techniques and professional judgement. Scottish Environment Protection Agency (SEPA) and Scottish Government guidance on the design of water crossings are referred to as appropriate.



13.16 Water abstraction may be required during the construction phase of the proposed development. This may affect the quantitative status of waterbodies (either surface water or groundwater). The effect is assessed primarily on the proposed quantities of water required for abstraction as well as the duration of abstraction and management of abstracted water.

13.17 Identification of potential GWDTEs provide a visual means of assessing the nature of the underlying groundwater in the absence of extensive field investigation. Consequently, they are a valuable tool in assessing potential changes in groundwater flow. However, while GWDTES play a role in the interpretation of groundwater movement, the ecosystems themselves are subject to protection due to their ecological value. Given their various roles, effects on GWDTEs should be considered in both hydrology and ecology chapters. This chapter assesses the potential effect of the development upon the quality and quantity of groundwater supporting the GWDTE due to potential effects on sub-surface drainage patterns. A technical appendix has been prepared (see TA13.1) based on site inspection and investigation that has considered the occurrence of GWDTE at site.

Data Sources and Guidance

13.18 An initial desk study has been undertaken to determine and confirm the baseline characteristics by reviewing available information on hydrology and hydrogeology such as groundwater resources, licensed and unlicensed groundwater and surface water abstractions, public and private water supplies, surface water flows, flooding, rainfall data and water quality. This has also included a review of published geological maps, OS maps, aerial photographs and site specific data such as site investigation data, geological and hydrogeological reports and geological literature.

13.19 The following sources of information, including good practice guidance and legislation have been consulted in order to characterise and assess the hydrogeology and hydrology of the area within and surrounding the Site:

Legislation and Planning Policy

• Scottish Planning Policy (SPP), The Scottish Government, June 2014; • EC Water Framework Directive (2000/60/EC); • Water Environment and Water Services (Scotland) Act 2003; • Water Environment (Controlled Activities) Regulations 2011;Flood Risk

Management (Scotland) Act 2009; • The Private Water Supplies (Scotland) Regulations 2006; • Water (Scotland) Act 1980 (and amendments);

Guidance and Best Practice

• Land Use Planning System – SEPA Guidance Note 7, SEPA, May 2014; • Land Use Planning System – SEPA Guidance Note 31, SEPA, October

2014; • Control of Water Pollution from Linear Construction Projects – Technical

Guidance, C648, CIRIA, 2006;



• Good Practice during Windfarm Construction, Version 3, a joint publication by Scottish Renewables, Scottish Natural Heritage, Scottish Environment Protection Agency, Forestry Commission Scotland and Historic Environment Scotland, 2015;

• The SUDS Manual C753, CIRIA, 2015; • Environmental Good Practice on Site C650, CIRIA, 2005;

Data Sources

• Online British Geological Survey (BGS) drift and solid geology mapping; • British Geological Survey (BGS) Hydrogeology of Scotland, 1988; • SEPA Groundwater Vulnerability Map of Scotland, 2003; • BGS Hydrogeological Map of Scotland, 1998; 1:625,000 Scale; • SEPA Website (www.sepa.org.uk) for details of river quality, river basin

management plans and flood risk (it is noted these maps are licenced for non-commercial use only and for this reason floodplain maps have not be presented in this assessment);

• The Scotland’s Environment Website (www.environment.scotland.gov.uk) for details of the current status of surface water and groundwater quality and designated sites;

• Correspondence with Scottish Water to confirm the location of their assets near to Site; and

• Further correspondence beyond the initial consultation with SEPA regarding the hydrology, hydrogeology, water use (authorised abstractions, discharges and engineering activities) and flood risk of the area surrounding the Site.

Field Survey

13.20 The project hydrologists, hydrogeologists, geologists and ecologists have worked closely on this assessment to ensure that appropriate information is gathered to allow a comprehensive impact assessment to be completed.

13.21 Detailed Site visits and walkover surveys have been undertaken by the authors of this assessment on the following dates: • 1st, 4th and 5th April 2016 to identify presence of GWDTEs and assess

ground conditions; • 30th August 2016 to assess potential watercourse crossings and areas of

historic mining; and • 31st August 2016 and 1st September 2016 surface water sampling and

private water supply survey.

13.22 The field work has been undertaken in order to:

• verify the information collected during the desk and baseline study; • allow appreciation of the Site, determine gradients, access routes, ground

conditions, etc., and to assess the relative location of all the components of the proposed development;



• undertake a visual assessment of the main surface waters and identify and verify private water supplies;

• identify drainage patterns, areas vulnerable to erosion or sediment deposition, and any pollution risks;

• collect surface water samples for baseline quality purposes; • assess areas of potential GWDTE; and • visit any potential watercourse crossings and prepare a schedule of

potential watercourse crossings.

13.23 The desk study and field surveys have been used to identify potential development constraints and have been used as part of the Site iterative design process.

13.24 The data obtained as part of the desk study and collected as part of the field work has been processed and interpreted to complete the impact assessment and recommend mitigation measures where appropriate.

Consultation

13.25 The scope of the study has been determined through a combination of professional judgement, reference to relevant guidance documents and consultation with stakeholders.

13.26 Consultation for the proposed development was undertaken with statutory and non-statutory bodies during 2016 as set out in Chapter 6: Scoping. The outcome of the relevant consultations with regards the water environment is summarised in Table 13-1.



Table 13-1: Summary of Consultation Responses with Respect to the Water Environment

Consultee Summary of Consultation Comment / Action

Taken

Marine Scotland (Scoping Response June 24th 2016)

“The developer should consult the following website http://www.gov.scot/Topics/marine/Salmon-Trout- Coarse/Freshwater/Research/onshoreren which describes activities associated with wind farm construction, operational and decommissioning stages of the development that may impact fish populations and fisheries.”

Consulted and mitigation measures in accordance with guidance proposed.

“Site characterisation surveys of the water quality of watercourses (hydrochemistry) including turbidity, flow stage data- and macroinvertebrates) likely to be impacted both within and downstream of the proposed development area, should be carried out”.

Surveys have been completed by fisheries specialists and hydrologists. Water sampling also completed.

“The water quality monitoring programme should also consider any effects associated with the historical lead mining that has been carried out in the proposed development area”.

See baseline conditions text. A review of the extent of historic mining has been completed and baseline water quality sampling undertaken.

“MSS suggests that any potential cumulative impacts are included in the monitoring programmes, particularly in the selection of control sites”.

Cumulative assessment completed.

“Although environmental conditions, legislation and best practices may differ at the time of decommissioning MSS advises the developer to consider the potential impacts of decommissioning on water quality and fisheries in the Environmental Statement (ES)”.

Decommissioning plan would be prepared prior to decommissioning.

Marine Scotland (2nd November 2016)

“We encourage full details of all proposed monitoring programmes to be presented in the Environmental Statement along with a consideration of potential cumulative impacts of adjacent developments on water quality and fish populations, particularly in the selection of control sites”.

As above.

Scottish Water (24th June 2016)

“There is Scottish Water infrastructure located close to the proposed development and we recommend that the

Location of infrastructure confirmed and

http://www.gov.scot/Topics/marine/Salmon-Trout-





Consultee Summary of Consultation Comment / Action Taken

developer confirms the location of this infrastructure and makes early contact with our Asset Impact Team (AIT) to discuss any potential conflicts. Particular consideration should be given to access roads and pipe crossings”.

informed site design. Measures to safeguard Scottish Water infrastructure are given in the CEMP.

“All of Scottish Water’s processes, standards and policies in relation to dealing with asset conflicts must be complied with”.

“All detailed design proposals relating to the protection of Scottish Water’s assets should be submitted to the AIT for review and written acceptance”.

“Works should not take place on-site without prior written acceptance by Scottish Water”.

“Annex 1 includes a list of precautions to be taken when working within the vicinity of Scottish Water assets. This list of precautions is not exhaustive but should be taken into account as the development progresses through the planning and development process”.

“It should be noted that the development will be required to comply with Sewers for Scotland and Water for Scotland 3rd Editions 2015, including provision of appropriate clearance distances from Scottish Water assets”.

South Lanarkshire Council (SLC) (Scoping Phase 15th July 2016)

Roads – Flood Risk Management “We would require sustainable drainage design and flood risk to be scoped in. The application requires to provide Flood Risk Assessment and SuDs proposals for the site this is due to the proposed development covering a large area and in close proximity to a number of watercourses. There are properties downstream of the development and the Council needs to ensure that there will be no detrimental impact from the proposal and associated infrastructure. Portions of the site are clearly shown on the SEPA Fluvial and Pluvial maps at a number of return periods. We would welcome early discussion on these matters”.

Flood risk assessment prepared and outlines SuDS measures specified. Measures proposed would be included in the site CEMP.

SEPA (29th June 2016)

“Hydrogeology There is a legacy of historic metal mining in the area and subsequently there is

Mining assessment prepared (see Chapter 11, TA11.3).




concern regarding the potential for interaction between the development and historic mine features.

The EIA should present the proximity of site infrastructure to former mine workings and assess any associated water environment impacts which may result from development. As such the developer should assess the extent of former underground mine workings and associated surface mine wastes; it would be advisable to provide a buffer around these features and avoid placing any development infrastructure in formerly mined areas. If site infrastructure is proposed to be located close to mine features, then the associated water environment impacts must be fully characterised to facilitate future reviews by SEPA.

Baseline water quality completed and specific mining mitigation measures specified.

Special consideration will need to be given to possible impacts to PWS and GWDTEs. Unless it can be demonstrated that works will not adversely impact PWS, GWDTEs and the wider water environment it is likely SEPA will require that the development be redesigned to mitigate against risks.

PWS and GWDTEs assessed and considered in this assessment. Mitigation measures specified where required.

The EIA must include specific assessment of how works, foundations, tracks and other features will impact on the historic mine features. The risk to the wider water environment will need to be assessed and in particular any risks to Private Water Supply (PWS) and Ground Water Dependent Terrestrial Ecosystems (GWDTEs). We would note that surface waters in the area (near Leadhills) are already impacted by metal contaminants due to mine wastes and further detrimental impact should be avoided.

As above.

We would recommend the inclusion of groundwater management and mine water management details be included in a construction environmental management document. This should assess the risk from intercepting mine features and detail the steps to be taken should the applicant/developer a) excavate made ground from mine workings and/or b) encounter perched water within mine workings

Scope of required investigations given.




Engineering Activities in the Water Environment River crossings should be minimised and avoided if possible when designing the road layout of the site. If water abstractions or dewatering are proposed, a table of volumes and timings of groundwater abstractions and related mitigation measures must be provided.

Watercourse crossings have been minimised. A CAR application would be made for any water abstraction.

Proposed watercourse crossings should be designed to accommodate the 1 in 200 year event / 0.5% Annual Exceedance Probability (AEP) flows, or information provided to justify smaller structures. If it is thought that the development could result in an increased risk of flooding to a nearby receptor then a Flood Risk Assessment must be submitted in support of the planning application

1:200 year design standard has been specified.

GWDTE are protected under the Water Framework Directive and therefore the layout and design of the development must avoid impact on such areas.

GWDTE risk assessment has been prepared and considered in this assessment (see TA13.1).

Existing Groundwater Abstractions Excavations and other construction works can disrupt groundwater flow and impact on existing groundwater abstractions. The submission must include: map demonstrating that all existing groundwater abstractions are outwith a 100m radius of all excavations shallower than 1m and outwith 250m of all excavations deeper than 1m and proposed groundwater abstractions. If the minimum buffers above cannot be achieved, a detailed site specific qualitative and/or quantitative risk assessment will be required.

It has been shown that minimum buffers have been achieved and the nearest abstraction is more than 500m from the proposed infrastructure.

Scottish Natural Heritage (21st June 2016)

None related to the water environment

No further action required.

Wanlockhead Community Council

“Field Surveys must cover the entire Site, and where negative environmental effects can arise beyond the Site boundary, these areas must also be surveyed.”

Detailed review of mining legacy has been completed and supplemented with water quality monitoring and considered in this



Consultee Summary of Consultation Comment / Action Taken assessment.

“The local community would like reassurance through an extensive quantitative survey of metal pollution in soil on all parts of the proposed Site, where vegetation and soil will or may be disturbed or removed, and where soil disturbance (and metal pollution) could impact either directly or indirectly, on a water course (including first order streams) or the air quality. This in order to establish the full nature, extent and degree of the contamination present, and fully assess the further health risks to local habitats, species and communities as a result of enhanced metal pollution”.

Areas of historic mining have formed development constraint and site specific mitigation measures have been presented in the CEMP.

Good Practice Measures and Mitigation

13.27 Any potential effects of the proposed development on the water environment identified by the assessment have been addressed and mitigated by the Site design and the application of good practice guidance to be implemented as standard during construction and operation to prevent, reduce or offset effects where possible. As such a number of measures would form an integral part of the construction process and these have been taken into account prior to assessing the likely effects of the proposed development. Where appropriate, further more tailored mitigation measures have been identified prior to determining the likely significance of residual effects.

13.28 Good practice measures would be applied in relation to pollution risk, sediment management, peat management and management of surface runoff rates and volumes. This would form part of the Construction and Environmental Management Plan (CEMP) to be implemented for the proposed development and would be prepared prior to construction, a draft of which is provided in Technical Appendix 3.1: Draft Construction and Environmental Management Plan.

13.29 The final CEMP would include details and responsibilities for environmental

management onsite for Site environmental aspects and would outline the necessary surface water management, oil and chemical delivery and storage requirements, waste management, traffic and transport management and would specify monitoring requirements for waste water, water supply including an Environmental Incident Response Plan (EIRP) and all appropriate method statements and risk assessments for the construction of the proposed development.



Assessing Significance

13.30 The significance of potential effects of the proposed development has been assessed by considering two factors: the sensitivity of the receiving environment and the potential magnitude of impact, should that effect occur.

13.31 The assessment methodology has also been informed by experience of carrying out such assessments for a range of wind farm and other developments, knowledge of the water environment characteristics in Scotland and cognisance of good practice.

13.32 This approach provides a mechanism for identifying the areas where mitigation measures are required and for identifying mitigation measures appropriate to the significance of potential effects presented by the proposed development.

13.33 Criteria for determining the significance of effect are provided in Table 13-2,

Table 13-3 and Table 13-4.

Sensitivity

13.34 The sensitivity of the receiving environment (i.e. the baseline quality of the receiving environment) is defined as its ability to absorb an effect without a detectable change and can be considered through a combination of professional judgement and a set of pre-defined criteria which is set out in Table 13-2. Receptors in the receiving environment only need to meet one of the defined criteria to be categorised at the associated level of sensitivity.



Table 13-2: Criteria for Assessing Sensitivity of Receptor

Sensitivity Definition

High • SEPA Water Framework Directive Water Body Classification: High-Good or is close to the boundary of a classification: Moderate to Good or Good to High;

• receptor is of high ecological importance or National or International value (e.g. Site of Special Scientific Interest (SSSI), Special Area of Conservation (SAC), habitat for protected species) which may be dependent upon the hydrology of the Development Area;

• receptor is at high risk from flooding above 0.5% Annual Exceedance Probability (AEP) and/or water body acts as an active floodplain or flood defence;

• receptor is used for public and/or private water supply (including Drinking Water Protected Areas;

• groundwater vulnerability is classified as high; and • if a Groundwater Dependent Terrestrial Ecosystem is present and

identified as being of high sensitivity.

Moderate • SEPA Water Framework Directive Water Body Classification: Moderate or is close to the boundary of a classification: Low to Moderate;

• receptor is at moderate risk from flooding (0.1% AEP to 0.5% AEP) but does not act as an active floodplain or flood defence; and

• moderate classification of groundwater aquifer vulnerability.

Low • SEPA Water Framework Directive Water Body Classification: Poor or Bad;

• receptor is at low risk from flooding (less than 0.1% AEP); and • receptor not used for water supplies (public or private).

Not Sensitive • receptor would not be effected by the proposed development e.g. lies within a different and unconnected hydrological / hydrogeological catchments.

Magnitude

13.35 The potential magnitude of impact would depend upon whether the potential effect would cause a fundamental, material or detectable change. In addition the timing, scale, size and duration of the potential effect resulting from the proposed development are also determining factors. The criteria that have been used to assess the magnitude of impact are defined in Table 13-3.



Table 13-3: Criteria for Assessing Magnitude of Impact

Magnitude Criteria Definitions

Major Results in loss of attribute

Fundamental (long term or permanent) changes to the baseline hydrology, hydrogeology and water quality such as: • wholesale changes to watercourse channel, route, hydrology

or hydrodynamics; • changes to the site resulting in an increase in runoff with flood

potential and also significant changes to erosion and sedimentation patterns;

• major changes to the water chemistry; and • major changes to groundwater levels, flow regime and risk of

groundwater flooding.

Medium Results in impact on integrity of attribute or loss of part of attribute

Material but non-fundamental and short to medium term changes to baseline hydrology, hydrogeology and water quality, such as: • some fundamental changes to watercourses, hydrology or

hydrodynamics. Changes to site resulting in an increase in runoff within system capacity;

• moderate changes to erosion and sedimentation patterns; • moderate changes to the water chemistry of surface runoff

and groundwater; and • moderate changes to groundwater levels, flow regime and risk

of groundwater flooding.

Low Results in minor impact on attribute

Detectable but non-material and transitory changes to the baseline hydrology, hydrogeology and water quality, such as: • minor or slight changes to the watercourse, hydrology or

hydrodynamics. • changes to site resulting in slight increase in runoff well within

the drainage system capacity; • minor changes to erosion and sedimentation patterns; • minor changes to the water chemistry of surface runoff and

groundwater; and • minor changes to groundwater levels, flow regime and risk of

groundwater flooding.

Negligible Results in an impact on attribute but of insufficient magnitude to affect the use/integrity

No perceptible changes to the baseline hydrology, hydrogeology and water quality such as: • no alteration or very minor changes with no impact to

watercourses, hydrology, hydrodynamics, erosion and sedimentation patterns;

• no pollution or change in water chemistry to either groundwater or surface water; and

• no alteration to groundwater recharge or flow mechanisms.

Significance of Effect

13.36 The sensitivity of the receiving environment together with the magnitude of the impact determines the significance of the effect, which can be categorised into level of significance as identified in Table 13-4. This also takes into account good practice measures implemented and embedded as



part of the design and construction of the proposed development and use of professional judgement where appropriate.

13.37 The table provides a guide to assist in decision making. However, it should not be considered as a substitute for professional judgment and interpretation. In some cases, the potential sensitivity of the receiving environment or the magnitude of potential impact cannot be quantified with certainty and therefore professional judgement remains the most robust method for identifying the predicted significance of a potential effect.

13.38 The characteristics of the impacts are described in terms of direct / indirect,

temporary (revisable) / permanent (irreversible), together with timescales (short, medium, long term).

Table 13-4: Significance of Effect

Magnitude of Impact

Sensitivity

High Moderate Low Not Sensitive Major Major Major Moderate Negligible

Medium Moderate Moderate Minor Negligible

Low Moderate Minor Minor Negligible

Negligible Negligible Negligible Negligible Negligible

Residual Effects

13.39 A statement of residual effects, following consideration of any further specific mitigation measures where identified, is then given.

Cumulative Effects Assessment

13.40 The assessment also considers potential cumulative effects associated with other wind farm developments within the same surface water catchments.

13.41 A cumulative effect is considered to be the effect on a hydrological or hydrogeological receptor arising from the proposed development in combination with other proposed developments which are likely to affect surface water and groundwater.

13.42 Proposed developments (consented and in planning) within the same

catchment as the Site and within a distance of 5km from the proposed development have been considered.

13.43 Cumulative effects are considered using the same methodology as for effects

of the proposed development in isolation.



Statement of Significance

13.44 The water environment assessment concludes with a Statement of Significance associated with the proposed development. Effects of ‘major’ and ‘moderate’ significance are considered to be ‘significant’ in terms of the EIA Regulations.

BASELINE CONDITIONS

13.45 The Site location and local hydrological and hydrogeological setting is shown on Figure 13.1.

13.46 A detailed assessment of the soils and geology at and near Site, including historic mining activity, is given in Chapter 11: Geology and Peat. Summary details are presented below to provide context for the description of hydrogeological conditions.

Hydrogeology

13.47 With reference to Chapter 11: Geology and Peat, it has been shown that there is limited or no superficial geology, with bedrock at or close to the surface. Peat has been recorded, in a number of areas within the Site notably Harryburn Brae, Dun Moss and Peat Hill and Bulmer Moss. A few localised peaty areas occur to the south at Toddle Moss and close to the Site entrance.

13.48 Where present, areas of superficial deposits comprise primarily glacial till, which is indicated on lower ground around close to Elvanfoot and on some of the slopes. It would appear there is no glacial till on the tops of the hills, with just localised peat and peaty gleys overlying shallow rock. Alluvial deposits of silt, sand and gravel are regionally present in the valley areas of the watercourses to the south and east of the Site.

13.49 The bedrock geology, at surface and beneath the superficial deposits across

the Site, comprises Lower Palaeozoic (Ordovician) sedimentary rocks from the Leadhills Supergroup and predominantly the Portpatrick Formation which is part of the Scaur Group. These rocks are described in the British Geological Survey (BGS) Memoir for the area as greywackes, i.e. poorly sorted turbidite sandstones with a mud matrix, which are interbedded with siltstones and sandstones.

13.50 The BGS GeoIndex website shows that there are no active mines or quarries

within the vicinity of the Site. There is extensive evidence of historic mining and prospecting within the Site, particularly to the south west towards Leadhills and Wanlockhead, beyond the Site boundary. The mineralisation found in the area is associated with mineral veins, which are narrow and steeply dipping and primarily trend in a north north west to south south east orientation.

13.51 A number of areas of historic mining activity have been identified and are

detailed in Technical Appendix TA11.3 - Mining Desk Study Report (see



Chapter 11: Geology and Peat). In summary there is no mining in the east of the Site and proposed turbines have avoided areas of known historic mining. At isolated and discrete locations in the west of the Site the proposed wind farm access track passes near known historic mine shafts or areas that have been disturbed by mining. Required mitigation in these areas is discussed in Chapter 11 and later in this Chapter.

Aquifer Characteristics and Recharge Mechanisms

13.52 A description and hydrogeological classification of the geological units at the Site are presented in Table 13-5.

13.53 Extracts of the Groundwater Vulnerability Map of Scotland is presented on Figure 13.2 and an extract of the Hydrogeological Map of Scotland which presents the regional hydrogeology with local features is presented on Figure 13.3.

13.54 Review of the Groundwater Vulnerability Map (Figure 13.2) suggests that the

uppermost aquifer is classified as having a Class 4 vulnerability which falls towards the middle and upper end of the scale which ranges from least vulnerable (1) to most vulnerable (5). This means groundwater is potentially vulnerable to those pollutants not readily absorbed or transformed.

13.55 Review of the Hydrogeological Map of Scotland (Figure 13.3) confirms that much of the Site is underlain by impervious rock generally without groundwater except at shallow depth.

13.56 The Met office maintains a rain gauge at the Wanlockhead Youth Hostel,

located approximately 5km to the south west of the study area. A review of data for the period (1981 to 2010) indicates an average annual rainfall of 1,311mm.

13.57 SEPA provided rainfall data for a rain gauge maintained at Garls Craig, Deer

Reservoir (SEPA), located approximately 12km to the south east of the study area. A review of the data for the period 2006- 2015 indicates an average annual rainfall of 1810mm.

13.58 It is considered that there are a number of baseline factors that would inhibit

groundwater recharge at Site include, which include the following:

• steeper topographic gradients present in parts of the Site would encourage the formation of surface water runoff;

• the underlying glacial till deposits and peat deposits would inhibit infiltration owing to their characteristic low bulk permeability; and

• the underlying bedrock (where it is not weathered or fractured) generally displays a low permeability that would limit groundwater recharge.



Groundwater Levels and Flows

13.59 SEPA has confirmed that it does not maintain any groundwater level monitoring sites within a 5km radius of the Site and does not hold any other historical groundwater level data.

13.60 Review of aquifer characteristics confirms that groundwater may be present within the more sandy/gravelly horizons within the glacial till, and within near surface weathered zones, fractures or fault zones within the bedrock deposits. There may also be groundwater present within historic and abandoned mine workings.



Table 13-5: Hydrogeological Characteristics of Geological Units at the Site

Period Geological Unit

Hydrogeological Characterisation Hydrogeological Classification and Groundwater Vulnerability

Pleistocene to Recent

Peat Where not degraded or eroded, characteristically wet underfoot and dominated by Sphagnum. Typically peat consists of two layers: the upper very thin (up to 30cm) acrotelm layer contains upright stems of Sphagnum mosses and allows relatively free water movement and the lower catotelm layer comprising the thicker bulk of peat where individual plant stems have collapsed. Water movement in the catotelm layer is very slow and normally the water table in a peat never drops below the acrotelm layer.

Not classified.

Alluvium The deposits are predominantly silt and clays with some pebbles and rocks. Groundwater storage and movement typically limited by small regional extent of this unit. Regionally, groundwater flow will be limited by the variability of these deposits and consequently any groundwater yields are normally low Clay within this unit acts as an aquitard to the more permeable gravelly lenses and will hinder/prevent large scale groundwater movement. Local differences in thickness, material type and its sorting can realise a considerable range in hydraulic conductivity. Commonly in hydraulic continuity with nearby watercourses and can support locally important potable water supplies.

Intergranular flow. High productivity. Considered to be highly vulnerable due to potential rapid groundwater movement and shallow depth to groundwater. Vulnerability Class 4.

Glacial Till Sand and gravel horizons within this unit are capable of storing groundwater, although their lateral and vertical extent realises a variable and often small groundwater yield. Clay within this unit acts as an aquitard to the more permeable sand and gravel lenses and will hinder/prevent large scale groundwater movement. Regionally, groundwater flow will be limited by the variability of these deposits and consequently any groundwater yields are normally low.

Intergranular flow mechanisms dominate Not classified confirming low productivity Considered to be vulnerable due to shallow depth to groundwater.

Ordovician Kirckolm Formation

Sandstone/siltstone turbidite sequence Generally without groundwater except at shallow depth. Highly indurated rocks

Fracture Flow dominant



Period Geological Unit

Hydrogeological Characterisation Hydrogeological Classification and Groundwater Vulnerability

with limited groundwater in near surface weathered zone and secondary fractures or rare springs

Low productivity Considered to be highly vulnerable to pollution on account of the dominance of fracture flow and generally limited superficial cover. Vulnerability Class 4.

Moffat Shale Group

Black and grey shale and tuff Generally without groundwater except at shallow depth. Highly indurated rocks with limited groundwater in near surface weathered zone and secondary fractures or rare springs.

Portpatrick Formation

Greywacke and siltstone turbidite succession. Sandstone units have numerous andesite lithoclasts Generally without groundwater except at shallow depth. Highly indurated rocks with limited groundwater in near surface weathered zone and secondary fractures or rare springs.

Shinnel Formation (Leadhills Supergroup)

Wacke sandstone and siltstone turbidite succession Generally without groundwater except at shallow depth. Highly indurated rocks with limited groundwater in near surface weathered zone and secondary fractures or rare springs.

Crawford Group

Lava, chert, tuff and mudstone succession Generally without groundwater except at shallow depth. Highly indurated rocks with limited groundwater in near surface weathered zone and secondary fractures or rare springs.



13.61 Shallow groundwater may also be expected adjacent to the larger watercourses where alluvium is recorded and where deposits of sand and gravel will store and allow movement of groundwater in the valley floor. This groundwater is considered likely to be in hydraulic continuity with the watercourses.

13.62 The BGS state that groundwater flow in upland areas, typical of much of the

Site, tends to follow flow paths from high ground to adjacent valleys. It is considered, therefore, that groundwater flows are likely to follow surface runoff patterns by flowing towards watercourses.

13.63 With reference to Chapter 11: Geology and Peat, the historic mineral

workings have been shown to be discrete and to have exploited mineral veins. Groundwater levels or flow are therefore unlikely to be controlled by the historic mine workings.

Private Water Supplies, Groundwater Abstractions, Use and Quality

13.64 As part of this assessment, data requests were made to SEPA (licensed water abstractions), Scottish Water (SW) and South Lanarkshire Council (SLC) (private water supplies) for details of water use.

13.65 SEPA confirmed there were no licensed abstractions within a 5km radius of

the proposed development. Licensed abstractions are therefore not considered further in this Chapter. It should be noted that all abstractions less than 10 m3/day are authorised by General Binding Rules under the Water Environment (Controlled Activities) (Scotland) Regulations 2011 (CAR) and as such do not have to be registered with SEPA. Private water supplies are discussed below.

13.66 SW has confirmed that there are no SW drinking water abstraction sources

or wider drinking water catchments, which are designated as Drinking Water Protection Areas that may be affected by the proposed development.

13.67 SW has confirmed that they operate infrastructure close to the proposed

development. This is presented on Figure 13.1, and includes:

• a potable water pumping station close to Elvanfoot that lifts water in a high pressure trunk main to the west and Wanlockhead (this follows the route of the B7040 and the old mineral railway in the Elvan Water valley);

• a high water trunk main that runs northwards in the River Clyde valley; and

• local distribution mains within the settlement of Elvanfoot. 13.68 The proposed wind farm access track would pass over the River Clyde valley

high pressure trunk main and the proposed wind farm substation would be constructed close to the Wanlockhead high pressure trunk main. No development is proposed near the Elvanfoot distribution main (see Figure 13.1).



13.69 SLC has confirmed that there are ten private water supplies within a 5km radius of the Site. Details of these supplies are provided in Table 13-6. All supplies are Type B supplies which are private water supplies that serve only domestic premises with less than 50 people supplied, and provide less than 10 cubic metres of water a day. In addition, the source of the supplies has been confirmed by SLC as being predominantly from groundwater springs. Table 13-6: Summary of Private Water Supplies Within 5km of the Site –

South Lanarkshire Council

Supply Property Supplied Figure Ref. No.

Type Use No. of People Served

Glencaple Glencaple Farm PWS-01

Spring Domestic and non-dairy

2

Glencaple Farm Cottage

Spring Domestic 2

Lettershaws Lettershaws Farm PWS-02

Spring Farm and caravan site

20

Lettershaws Cottage Spring Domestic 4

Lettershaws Farm Cottage

Spring Domestic 1

Parkend Parkend PWS-03

Spring Domestic 3

The Hass The Hass PWS-04

Spring Domestic 1

North Shortcleuch

North Shortcleuch PWS-05


3

South Shortcleugh

South Shortcleugh PWS-06


2

Glenochar Glenochar Farm PWS-07

Spring Domestic 2

Glenochar Cottage Spring Domestic 2

Peden Pedengill PWS-08

Spring Domestic 4

Waterhead Waterhead Toll Cottage

PWS-09

Spring Domestic Not Reported

New Glendorch New Glendorch Cottage

PWS-10

Spring Domestic Not Reported

Colebrook Colebrook PWS-11

Mains Domestic Not Reported

13.70 As part of this assessment, properties within the catchments potentially

affected by the proposed development were visited in order to collect details



of their water source. A total of five properties were visited that were identified to lie within or adjacent to the water catchments in which Site infrastructure is proposed. Details of the properties visited are provided in Table 13-7. The location of the identified water sources are shown on Figure 13.1.

Table 13-7: Summary of Private Water Supplies Visited during Site Visit

Location NGR of Source

Type Distance and Direction from Nearest Proposed Infrastructure

North Shortcleuch

NS 92661 17806

PWS-05

Spring 662m to the south

Colebrooke NS 93022 22671

PWS-11

Scottish Water Mains N/A

Glencaple Farm + Lodge

NS 91967 21117

PWS-01

Soil Water (perforated field pipe)

1,671m to the north

Lettershaws NS 90296 20910

PWS-02

Surface Water 2,059m to the north-west

NS 89712 20600

Springs

NS 89723 20510

Springs

NS 89624 21246

Springs

NS 89906 21334

Springs

Waterhead NS 88419 18371

PWS-09

Spring 1,195m to the west

NS 88540 18666

Springs

New Glendorch

NS 88949 17432

PWS-10

Springs 1,319m to the west

13.71 Review of Figure 13.1 and Table 13-7 confirms that all of the water sources

are more than 500m from the proposed wind farm infrastructure and therefore more than the 100m and 250m buffers specified in SEPA guidance.

13.72 With reference to Figure 13.1, it is apparent that many of the water sources are to the north of the Glengonnar Water and thus are not in hydraulic continuity with the proposed development.

13.73 The private water supply survey has shown that potentially 3 properties have

water sources in the same surface and groundwater catchment as the proposed development:



• North Shortcleuch (PWS-05) which obtains water from a spring located 662m and downstream of the proposed wind farm access track. It is considered that without appropriate mitigation, the proposed development could impair this water source;

• New Glendorch (PWS-10) which has a spring water source 1319m from the proposed access track, although it is noted that the source is located to the west of a tributary of the Glengonnar Water, and is in a different sub-water catchment to the proposed development. This water source is therefore not considered at risk from the proposed development; and

• Glencaple (PWS-01) gathers shallow water using a perforated pipe above the farm and lodge. The pipe is located more than 1650m from the proposed development and is not in direct hydraulic continuity with the proposed development. This water source is therefore not considered at risk from the proposed development.

13.74 SEPA has confirmed that it does not hold any information regarding

groundwater quality, and sampling of groundwater within 5km of the Site is not undertaken by them.

13.75 Groundwater associated with Alluvium of the Upper Clyde Valley is classified by SEPA as ‘Good’.

13.76 The SEPA interactive mapping application1 classifies the bedrock

groundwater at the Site and in the wider area as 'poor' (2015) and reflects a classification for an area of 400 km2 e.g. much greater than the study area. The poor water quality is attributed to water in the Coal Measures and thus is not considered relevant to the proposed development as these deposits have been shown not be present within the Site.

13.77 It is expected that groundwater present within the upper weathered surface of the bedrock at the Site may be of good quality as much of the Site has been unmodified and there is little cover above the bedrock. Where there has been historic mining, locally there is potential for greater mineralisation of groundwater and groundwater quality to be impaired.

13.78 As noted in Leadhills Community Council scoping response report (June

2016) the presence of flooded abandoned mine workings in the area has been well documented as has the potential occurrence of elevated heavy metals in ground and surface water which has come in contact with mine workings or waste. As a consequence the water supply to Leadhills and Wanlockhead was replaced with an alternative source to ensure the wholesomeness of water to these communities – details of this Scottish Water infrastructure is provided above.

Local Hydrology

13.79 The proposed development lies within four surface water catchments which are shown on Figure 13.1 and comprise:

1 http://map.environment.scotland.gov.uk

http://map.environment.scotland.gov.uk/



• River Clyde: This watercourse is located to the east of the study area and flows towards the north. The tributaries of this watercourse drain the south and eastern parts of the study area; which is shown as two sub-catchments on Figure 13.1: River Clyde A and B.

• Glengonnar Water: This watercourse is located to the west of the study

area and flow towards the north / north east. It has a confluence with the River Clyde at Abington. The tributaries of this watercourse drain the north west of the study area.

• Shortcleuch Water, which turns into Elvan Water, is located to the south of

the proposed turbines and flow towards the east. The confluence of the Elvan Water and the River Clyde is at Elvanfoot.

13.80 Table 13-8 shows catchment descriptors from the Flood Estimation

Handbook (FEH) database for the Glengonnar Water and Elvan Water which can be used to describe the catchments anticipated response to rainfall. Descriptors are not given for the River Clyde A and B catchments as they are sub-catchments of the much larger River Clyde catchment.

Table 13-8: Catchment Descriptors for Principal Watercourses

Catchment Watercourse D/stream Point NGR

Area (km2)

SAAR (mm)

ALTBAR (mASL)

DPSBAR (m/km)

LDP (km)

Glengonnar Water

Glengonnar Water

NS 92450 22000

25.00 1422 405 206.6 12.17

Elvan Water

Elvan Water NS 95400 17500

24.53 1567 449 198.7 13.66

Notes: Grid reference of downstream maximum extent of catchment as denoted by ether the application boundary or confluence with another watercourse SAAR – surface average annual rainfall between 1941 and 1970 ALTBAR – mean catchment altitude (metres above sea level) DPSBAR – index of catchment steepness LDP – longest drainage path 13.81 SEPA has confirmed that it records mean daily flows for the River Clyde at

Abington. The mean daily flow for the period 1st July 2006 to 30th June 2016 is 10.66m3/s, with a minimum of 1.36m3/s (June 2010) and maximum of 198m3/s (November 2009).

13.82 The Site has no hydraulic connection with the River Tweed catchment.

Flood Risk Assessment and Surface Water Quality

13.83 Review of the SEPA Flood Map 200-year flood outline (i.e. the flood with a 0.5% chance of occurring in any single year) indicates that parts of the study area lies within this envelope and as such is potentially at medium to high risk of fluvial and surface water flooding. The areas indicated to be potentially at risk of flooding are mainly within or immediately adjacent to the footprint of existing watercourses and waterbodies.



13.84 The proposed turbines and associated infrastructure (substation and

construction compound) are shown to be outside / remote from areas potentially at risk of flooding.

13.85 SEPA has confirmed that they hold five records of historic flood events in the

area. These are summarised in Table 13-9.

Table 13-9: Summary of Historic Flood Events

Date Approximate Level

Location Details

12/12/1994 Street Level The breakout occurred under the Leadhills-Abbington road.

Following heavy rainfall there was a breakout of mine water from the abandoned mine workings on Leadhills. A large part of the railway and road were removed.

12/12/1994 Road Runoff Abington Hotel Abington -

12/12/1994 Fluvial / Run off

Medwyn Bridge A702 Closed at Medwyn Bridge

30/07/2002 Unknown / surface water

Carlisle Road, Abington SLC Category 3 - Flooding residential / commercial property

01/02/2004 Street Level Nithsdale - Wanlockhead - 7 Fraser Terrace -

Water flooding into garden - Pluvial flooding

13.86 SEPA has confirmed that they do not have any existing or proposed flood

defence measures in the study area.

13.87 Following review of the site setting, including the site hydrogeology and extent of the published floodplains it is concluded that the proposed wind farm infrastructure is not considered to be at risk of significant or frequent flooding from fluvial or groundwater sources. Measures are proposed to manage pluvial (overland flow) flood risk in the as part of the site design (see Good Practice Measures).

13.88 As part of the iterative design process for the proposed development the number of new watercourse crossings has been minimised. Three new watercourse crossing points would be required as part of the proposed development as shown on Figure 13.1:

• WC1: Over Elvan Water at NGR 291105, 617720; • WC2: Over tributary of Glengonnar Water at NGR 290239, 617703; and • WC3: Over a tributary of the River Clyde at NGR 295106 617674.

13.89 As part of this assessment the proposed crossing points were visited. Crossing point WC1 is over a tributary of the Elvan Water near T9 is shown in Photograph 13-1. Crossing point WC2, which is over a tributary of the



Glengonnar Water near T12, is shown in Photograph 13-2. The crossing over the River Clyde tributary (WC3) is shown in Photograph 13-3.

13.90 Details of the design of the proposed watercourse crossings is given later in

this Chapter see Good Practice Measures (Watercourse Crossings).

13.91 As shown in Photographs 13-1 - 13-3, the watercourses are small, and less than 0.5m deep and 0.5m wide. Spoil was evident near to WC2 and it is possible that the watercourse channel has developed in an historic mineral working / exploration area.

13.92 As stated in Chapter 11 (Geology and Peat) site investigation would be

required at this location before any development could take place to confirm the nature and extent of any mine workings so that appropriate design and mitigation measures can be developed to ensure structural integrity and protection of water resources.

Photograph 13-1: Proposed Water Crossing 1 (WC1)





13.93 SEPA has classified watercourses in terms of their quality as part of their River Basin Management Planning. Classifications of the principal watercourses at the Site are shown in Table 13-10. All watercourses are classified as having a Moderate or Good overall status.

Table 13-10: SEPA Surface Water Quality Classification

Monitoring Location Overall Status

Confidence Year Overall Ecological Status

Overall Chemical Status

River Clyde Moderate High 2013 Moderate Pass

Glengonnar Water Moderate Good 2013 Good Fail

Elvan / Shortcleuch Water Good High 2013 Good Pass 13.94 Poor chemical status is recorded in the Glengonnar Water near to the Site.

SEPA report that the poor water quality is attributable to historic mining and quarrying of minerals. This is consistent with the scoping response report submitted by Leadhills Community Council that highlighted a 2012 study that assessed water quality in the Glengonnar Water and confirmed that samples of sediment from the floodplain soils and from the watercourse channel “all showed significant levels of lead, zinc, cadmium, plus copper and nickel”.

13.95 To further characterise surface water quality, water monitoring was undertaken by SLR during field investigations in September 2016. Eight points were visited in order to assess water quality upstream and downstream of the proposed development. Details are presented in Table 13-11. Monitoring locations are presented on Figure 13.1.



Table 13-11: SLR Surface Water Quality Monitoring Points

Monitoring Location

NGR Watercourse Surface Water Catchment

Location

SW1 NS 292202, 621816

Glengonnar Water Glengonnar Water

Main river, downstream in catchment. Downstream of T1, T4, T5, T7, T8, T9, T10, T12, T15, T16, T17

SW2 NS 295335, 618486

Collins Burn / Harry Burn

River Clyde A

Tributary of River Clyde. Downstream of T2 and T3.

SW3 NS 293972, 617254

Elvan Water Elvan Water Main River, downstream in catchment. Down-stream of T13, T14, T18 and T19

SW4 NS 292522, 620746

Lang Slack / Glencapple Burn / Hershaw Burn / Raven Gill / Dry Cleuch

Glengonnar Water

Tributary of the Glengonnar Water. Downstream in catchment. Upstream of SW1

SW5 NS 292369, 617079

Elvan Water Elvan Water Main River. Downstream of T13, T14, T18 and T19. Upstream of SW3

SW6 NS 292787, 617547

Shortcleuch Burn Elvan Water Tributary of Elvan Water. Upstream of SW3

SWC1 NS 288896, 618103

Glengonnar Water Glengonnar Water

Control point Upstream of study area

SWC2 NS 290733, 616150

Elvan Water Elvan Water Control point Upstream of study area

13.96 The results for the surface water quality monitoring are presented in Table

13-12 and compared to the Environmental Quality Standards (EQS). Review of the data collected shows:

• dissolved oxygen (DO) concentrations were recorded above the Minimum

Allowable Concentrations (MAC) of 7mg/L at all eight monitoring points indicating good water quality;

• the majority of the monitoring points show good water quality and determinand concentrations below EQS;



• elevated concentrations of cadmium (Cd), lead (Pb) and zinc (Zn) were recorded at monitoring points SW1 and SWC1. SWC1 also recorded elevated copper (Cu). Both points monitor water quality of the Glengonnar Water – these elevated levels are consistent with the poor water quality recorded by SEPA as part of their River Basin Management planning;

• when comparing water quality along the Glengonnar Water, higher concentration of the majority of determinands are recorded at the upstream monitoring point SWC1 (e.g. closer to the areas of known previous mining); and

• elevated manganese (Mn) was recorded at SW2 (on Harry Burn in the east of the Site). It is noted that manganese is commonly associated with poorly drained soils.

13.97 The monitoring data collected confirms that reported by SEPA and Leadhills

Community Council and that historic mining impairs water quality in the Glengonnar Water. Water quality in the lower reaches of the Glengonnar Water and in the east of the site records better water quality and is likely to reflect the lack or absence of mining further east.

Fisheries

13.98 As part of the baseline assessment historical fish survey data was reviewed by Clyde River Foundation for two sampling locations on the Elvan Water and two on the Glengonnar Water. Full details are provided in Chapter 9: Ecology. In summary, the data shows that:

• stable multiple year classes (ages) of brown trout were present at all sites

in all years; • the trout densities found during the surveys are typical for upper Clyde

tributaries; • brook lamprey was recorded only at one site on one occasion, on the

Elvan Water; • one North American signal crayfish was captured from the Elvan Water; • salmon, eel and migratory lampreys are absent from the study area due to

Stonebyres Falls near Lanark (a naturally occurring series of bedrock steps) which acts as a natural barrier and prevents the movement from the sea to the study area.



Table 13-12: SLR Surface Water Quality Results (September 2016)

Determinand Unit EQS SW1 SW2 SW3 SW4 SW5 SW6 SWC1 SWC2 AA MAC

Total Alkalinity (as CaCO3) mg/l 46.5 41 39 44 41.5 62.5 60 34.5 Ammoniacal Nitrogen as N mg/l <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 BOD, unfiltered mg/l <1 <1 <1 <1 <1 <1 <1 <1 Chloride mg/l 250 11.7 3.8 6.4 5.3 5.9 5 15.6 5.7 COD, unfiltered mg/l <7 14.7 <7 <7 <7 <7 <7 10.4 Nitrate as N mg/l 0.229 <0.0677 <0.0677 <0.0677 0.0735 0.111 0.423 <0.0677 Nitrate as NO3 mg/l 50 1.01 <0.3 <0.3 <0.3 0.326 0.493 1.87 <0.3 Nitrogen, Total mg/l <1 <1 <1 <1 <1 <1 <1 <1 Oxygen, dissolved mg/l <7 10.3 9.92 10.2 10.5 10.5 10.1 10.6 10.5 pH pH Units 6 - 9 7.53 7.49 7.62 7.63 7.76 7.57 7.62 7.48 Sulphate mg/l <2 <2 <2 <2 <2 <2 5.9 <2 Sulphide mg/l <0.01 <0.01 <0.01 0.034 <0.01 <0.01 <0.01 <0.01 Total Suspended solids mg/l 25 <2 <2 3 <2 <2 <2 <2 <2 Arsenic (Dissolved) mg/l <0.00051 <0.00051 <0.00051 <0.00051 <0.00051 <0.00051 <0.00051 <0.00051 Boron (Dissolved) mg/l 2 <0.005 0.00847 <0.005 <0.005 <0.005 0.00583 0.00501 <0.005 Cadmium (Dissolved) mg/l 0.00008 0.00045 0.000224 <0.00008 <0.00008 <0.00008 <0.00008 <0.00008 0.000864 <0.00008 Calcium (Dissolved) mg/l 13 8.61 9.87 9.87 10.4 13.3 18.8 8.85 Chromium (Dissolved) mg/l <0.0012 <0.0012 <0.0012 <0.0012 <0.0012 <0.0012 <0.0012 <0.0012 Cobalt (Dissolved) mg/l 0.003 0.1 <0.00015 0.000372 <0.00015 <0.00015 <0.00015 <0.00015 0.000239 <0.00015 Copper (Dissolved) mg/l 0.001 <0.00085 <0.00085 <0.00085 <0.00085 <0.00085 <0.00085 0.00152 <0.00085 Iron (Dissolved) mg/l 1 0.0426 0.209 0.0192 0.0223 <0.019 0.0201 0.0295 <0.019 Iron, Ferric mg/l <0.05 0.209 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 Iron, Ferrous mg/l <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Lead (Dissolved) mg/l 0.0012 0.014 0.019 0.000201 <0.0001 <0.0001 0.000109 0.000145 0.147 0.000239 Magnesium (Dissolved) mg/l 3.49 3.56 2.76 3.9 2.66 5.34 3.4 2.16 Manganese (Dissolved) mg/l 0.123 0.00925 0.16 0.00567 0.00283 0.00116 0.00365 0.0624 0.00178 Mercury (Dissolved) mg/l <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 Nickel (Dissolved) mg/l 0.004 0.034 0.000773 0.0013 <0.00044 <0.00044 <0.00044 <0.00044 0.00138 <0.00044 Potassium (Dissolved) mg/l <1 <1 <1 <1 <1 <1 <1 <1 Selenium (Dissolved) mg/l <0.00081 <0.00081 <0.00081 <0.00081 <0.00081 <0.00081 <0.00081 <0.00081 Zinc (Dissolved) mg/l 0.0119 0.0161 0.0042 <0.0013 <0.0013 0.00999 <0.0013 0.0925 0.00276 Iron (Total) mg/l 0.0608 0.316 0.0436 0.025 <0.024 0.0563 0.0408 <0.024 Note: AA: Annual Average. MAC: Maximum Allowable Concentration (Minimum for Dissolved Oxygen). Highlighted cells indicate water quality standard exceeded.



Licensed Discharges

13.99 SEPA holds records for numerous CAR licences within the study area. Those within a 5km radius are summarised in Table 13-13 and shown on Figure 13.1.

13.100 It is noted that the majority of the discharges are directly to land, and are not

within the application boundary. Two of the discharges (CAR-55 and CAR-57) fall within the application boundary however are located within River Clyde B catchment and remote from the proposed development. Both are for the disposal of sheep dip.



Table 13-13: CAR Licences to Discharge

Drawing Ref. No. CAR Licence No. Name Type Activity Distance from Site Infrastructure (m)

CAR-01 CAR/L/1000738 Abington Septic Tank CSO CSO 4220 CAR-02 CAR/L/1000711 Leadhills STW Final Effluent Discharge 2291 CAR-03 CAR/L/1000711 Leadhills STW Combined Sewer Overflow Discharge 2291 CAR-04 CAR/L/1000738 Abington Septic Tank Final Effluent Discharge 4220 CAR-05 CAR/L/1000743 Sludge treatment supernatent -- Discharge 8885 CAR-06 CAR/L/1000743 Instrumentation Reject Water -- Discharge 8885 CAR-07 CAR/L/1000752 Crawford STW Final Effluent Discharge 2719 CAR-08 CAR/S/1100158 The Hainings Final Effluent Discharge 3950 CAR-09 CAR/S/1038436 Wyndales Farm Treated effluent Discharge 2026 CAR-10 CAR/S/1094804 Clyde Windfarm Treated effluent Discharge 6476 CAR-11 GWR/W/3000767 Spango Farm Waste sheep dip Disposal 3078 CAR-12 CAR/S/1017060 Glendouran Waste sheep dip Disposal 3549 CAR-13 CAR/S/1017060 Glendouran Waste sheep dip Disposal 5024 CAR-14 CAR/S/1017060 Glendouran Waste sheep dip Disposal 5109 CAR-15 CAR/S/1017060 Glendouran Waste sheep dip Disposal 5077 CAR-16 GWR/W/3000394 Smith Gore Farm Management Waste sheep dip Disposal 7374 CAR-17 CAR/S/1024260 Overfingland Waste sheep dip Disposal 7467 CAR-18 CAR/S/1024260 Overfingland Waste sheep dip Disposal 7467 CAR-19 GWR/W/3000394 Smith Gore Farm Management Waste sheep dip Disposal 7383 CAR-20 GWR/W/3000345 Midlock Waste sheep dip Disposal 3852 CAR-21 CAR/S/1043284 Midlock Waste sheep dip Disposal 3104 CAR-22 CAR/S/1043284 Midlock site 1 Waste sheep dip Disposal 3871 CAR-23 CAR/S/1043284 Midlock site 2 Waste sheep dip Disposal 3925




CAR-24 CAR/S/1043284 Midlock site 3 Waste sheep dip Disposal 3781 CAR-25 CAR/S/1043284 Midlock site 4 Waste sheep dip Disposal 3843 CAR-26 CAR/S/1043284 Midlock site 5 Waste sheep dip Disposal 3787 CAR-27 CAR/S/1043284 Midlock site 6 Waste sheep dip Disposal 3760 CAR-28 GWR/W/3000345 Midlock Site A Waste sheep dip Disposal 3863 CAR-29 GWR/W/3000345 Midlock Site B Waste sheep dip Disposal 3916 CAR-30 GWR/W/3000345 Midlock Site C Waste sheep dip Disposal 3846 CAR-31 GWR/W/3000345 Midlock Site D Waste sheep dip Disposal 3767 CAR-32 GWR/W/3000345 Midlock Site A Waste sheep dip Disposal 3852 CAR-33 CAR/S/1056287 Auchengruith Site 18 Waste sheep dip Disposal 4569 CAR-34 CAR/S/1056287 Auchengruith Site 19 Waste sheep dip Disposal 4621 CAR-35 CAR/S/1063322 Kirkton Farm Waste sheep dip Disposal 1153 CAR-36 GWR/W/3000897 Castle Crawford Site A Waste sheep dip Disposal 2832 CAR-37 GWR/W/3000897 Castle Crawford Site B Waste sheep dip Disposal 2954 CAR-38 GWR/W/3000897 Castle Crawford Site C Waste sheep dip Disposal 3042 CAR-39 GWR/W/3000897 Castle Crawford Site D Waste sheep dip Disposal 3175 CAR-40 CAR/S/1083722 Castle Crawford Site 1 Waste sheep dip Disposal 2832 CAR-41 CAR/S/1083722 Castle Crawford Site 2 Waste sheep dip Disposal 2954 CAR-42 CAR/S/1083722 Castle Crawford Site 3 Waste sheep dip Disposal 3042 CAR-43 CAR/S/1083722 Castle Crawford Site 4 Waste sheep dip Disposal 3144 CAR-44 CAR/S/1083722 Castle Crawford Site 5 Waste sheep dip Disposal 3205 CAR-45 CAR/S/1083965 Eastertown Farm Site 10 Waste sheep dip Disposal 5023 CAR-46 CAR/S/1083965 Eastertown Farm Site 11 Waste sheep dip Disposal 5040 CAR-47 CAR/S/1088247 Nether Abington Farm Waste sheep dip Disposal 4831 CAR-48 CAR/S/1088247 Nether Abington Farm Site 1 Waste sheep dip Disposal 4147




CAR-49 CAR/S/1088247 Nether Abington Farm Site 2 Waste sheep dip Disposal 4166 CAR-50 CAR/S/1088247 Nether Abington Farm Site 3 Waste sheep dip Disposal 4072 CAR-51 CAR/S/1088247 Nether Abington Farm Site 4 Waste sheep dip Disposal 4052 CAR-52 CAR/S/1092469 Whelphill Farm Waste sheep dip Disposal 4954 CAR-53 CAR/S/1092469 Whelphill Farm Site 1 Waste sheep dip Disposal 4047 CAR-54 CAR/S/1092469 Whelphill Farm Site 2 Waste sheep dip Disposal 4064 CAR-55 CAR/S/1112483 Glenochar Farm Waste sheep dip Disposal 3562 CAR-56 CAR/S/1112483 Glenochar Farm Site 1 Waste sheep dip Disposal 4700 CAR-57 CAR/S/1112483 Glenochar Farm Site 2 Waste sheep dip Disposal 2742 CAR-58 CAR/S/1112487 Lowther Farm Waste sheep dip Disposal 2763 CAR-59 CAR/S/1112487 Lowther Farm Site 1 Waste sheep dip Disposal 2899 CAR-60 CAR/S/1112487 Lowther Farm Site 2 Waste sheep dip Disposal 2925 CAR-61 CAR/S/1112487 Lowther Farm Site 3 Waste sheep dip Disposal 2960 CAR-62 CAR/S/1090687 Clydes Burn Point A Impoundment 3894 CAR-63 CAR/S/1090687 Clydes Burn Point B Impoundment 3880



Receptor Sensitivity

13.101 Table 13-14 outlines the receptors identified as part of the baseline study, and their sensitivity based upon the criteria contained in Table 13-2. These receptors form the basis of the assessment, and as per the methodology, are used in conjunction with an estimate of the magnitude of an effect to determine significance.

13.102 There are two Sites of Special Scientific Interest (SSSI) in the vicinity of the

study area (Figure 13.3): Raven Gill and Leadhills / Wanlockhead (which consists of three component areas). Raven Gill is the only one that lies within the Site boundary.

13.103 Raven Gill is a geological SSSI. It displays rocks of demonstrably Arenig

Age (Lower Ordovician). The Site provides evidence that constrains the dating of sedimentation during the early Lower Palaeozoic in the Southern Uplands basin. It is not sustained by water and thus is not considered further in this Chapter. Potential effects on the SSSI are, however, considered in Chapter 11: Geology and Peat.

13.104 Leadhills / Wanlockhead SSSI relates to mineral veins and geology, and is

not sustained by water and thus is not considered further in this Chapter. The SSSI is hydraulically remote from the Site.

13.105 Potential effects on ground stability and mining are considered in Chapter 11

(Geology and Peat). The potential mobilisation of mining waste or potential to intercept flooded mine workings are considered in this Chapter (see pollution, erosion and sedimentation).

Table 13-14: Sensitivity of Receptors

Receptors Sensitivity Reason for Sensitivity Effects Assessed

for Construction and Operation

Private Water Supply at North Shortcleuch (PWS-05)

High Private water supply located close to proposed wind farm infrastructure.

Pollution, erosion and sedimentation.

Groundwater Moderate The region (beyond the Site) is designated as a Drinking Water Protection Zone under the Water Framework Directive.

Pollution, drainage and groundwater-surface water interactions.

River Clyde Moderate Watercourse and tributaries located within the hydrological study area with moderate WFD classification.

Pollution, erosion and sedimentation, flood risk, drainage and groundwater-surface water interactions.

Glengonnar Water Moderate Watercourse and tributaries located within the hydrological study area with moderate WFD classification.

Elvan Water High Watercourse and tributaries located within the hydrological study area with good WFD classification.



ASSESSMENT OF EFFECTS

13.106 The assessment of effects is based on information presented in Chapter 3: Description of the Development and is structured as follows:

• construction effects of the proposed development; • operational effects of the proposed development; and • cumulative effects of the proposed development, and other proposed wind

farms in the study area.

The Proposed Development Layout Considerations

13.107 The proposed development has undergone design iterations and evolution in response to the hydrological and hydrogeological constraints identified as part of the baseline studies and field studies so as to avoid and/or minimise potential effects on receptors where possible. This has included watercourse locations, areas of potential flooding, areas of historic mining (adits, shafts and spoil) and GWDTEs.

Buffer to Watercourses

13.108 In accordance with wind farm construction best practice guidelines, a 50m buffer has been applied between watercourses and any proposed construction activities or infrastructure was applied to those watercourses within the Site. .

13.109 The layout of the access track was designed to minimise the number of watercourse crossings across the Site. The locations of three proposed new crossings are shown on Figure 13.1 and details of the watercourse channels are presented in the Baseline Conditions above.

Groundwater Dependent Habitats

13.110 SEPAs wind farm planning guidance states a National Vegetation Classification (NVC) survey should be undertaken to identify wetland areas that might be dependent on groundwater. If potential GWDTEs are identified within (a) 100m of proposed excavations less than 1m deep (e.g. roads, tracks and trenches), or (b) within 250m of excavations deeper than 1m (e.g. excavated tracks, borrow pits and foundations), then it is necessary to assess how the potential GWDTEs may be affected by the proposed development.

13.111 SEPAs wind farm planning guidance has been used to inform the Site

design. 13.112 A summary of the habitat survey completed at the Site is provided in Chapter

9: Ecology along with a detailed NVC habitat plan. An assessment of the GWDTEs is presented in Technical Appendix 13.1: GWDTE, which comprised further field investigation and a programme of trial pitting. The trial pitting exercise did not prove the presence of groundwater and combined with a review of the site topography, meteorology, and geology it has been



concluded that areas identified onsite as being potentially moderately or highly groundwater dependent are likely to be sustained by incident rainfall and local surface water runoff rather than by groundwater. Accordingly, the buffers proposed in SEPAs GWDTEs guidance need not apply.

13.113 Measures, such as permeable access tracks and regular cross track drains,

have been proposed in Technical Appendix 13.1 (GWDTE) to safeguard existing water flow paths and maintain existing water quality. It is considered therefore that the water dependent habitats identified by the NVC mapping can be therefore sustained. This would be confirmed, in accordance with good practice, by the Ecological Clerk of Works (ECoW) at the time of the construction of the proposed development who would ensure existing surface water flow paths are maintained.

Areas of Historic Mining

13.114 The presence of mining at the site has been subject to detailed review and consideration. A mining risk assessment has been completed and site walkover surveys have been undertaken by experienced geologists and hydrogeologists. Mining has been considered as a development constraint in the site design.

13.115 No turbines, or other structures that require foundations, have been located in areas of known historic mining.

13.116 Access tracks have also been located, wherever possible, away from

previous mining areas. Where this has not been possible near to T12 and T13 and watercourse crossing WC2 further site investigation has been specified to inform site specific construction and mitigation measures to ensure ground stability and control erosion, sedimentation and pollution potential.

Good Practice Measures

13.117 Measures would be adhered to during the construction and operation of the proposed development. Good practice measures would be applied in relation to pollution risk, and management of surface runoff rates and volumes. This would form part of the final CEMP (see Technical Appendix 3.1: Draft Construction and Environmental Management Plan) to be implemented for the proposed development.

13.118 Key good practice measures are stated below and the assessment incorporates these measures as part of the proposed development. Any further specific mitigation which may be required to reduce the significance of a potential effect is identified in the assessment of likely effects during the construction and operation phases.

General Measures

13.119 As a principle, preventing the release of any pollution/sediment is preferable to dealing with the consequences of any release. There are several general



measures which cover all effects assessed within this chapter, details are given below.

13.120 Prior to construction, section specific drainage plans would be produced.

These would take into account any existing local drainage which may not be mapped and incorporate any section specific mitigation measures identified during the assessment.

13.121 Measures would be included in the final CEMP for dealing with

pollution/sedimentation/flood risk incidents and would be developed prior to construction. This would be adhered to should any incident occur, reducing the effect as far as practicable.

13.122 The final CEMP would contain details on the location of spill kits, would

identify 'hotspots' where pollution may be more likely to originate from, provide details to site personnel on how to identify the source of any spill and state procedures to be adopted in the case of a spill event. As identified in the draft CEMP, a specialist spill response contractor would be identified to deal with any major environment incidents.

13.123 A wet weather protocol would be developed. This would detail the

procedures to be adopted by all staff during periods of heavy rainfall. Tool box talks would be given to engineering/construction/supervising personnel.

13.124 Roles would be assigned to different engineering/construction/supervising

personnel and the inspection and maintenance regimes of sediment and runoff control measures would be adopted during these periods. In extreme cases, the above protocol would dictate that work onsite may have to be temporarily suspended until weather/ground conditions allow.

13.125 Similarly, best practice and manufacturer’s guidance would be used during

construction, installation and operation of the component parts of the proposed substation (inc. the proposed battery storage). Best practice measures that would be used to mitigate potential impacts are detailed below.

Water Quality Monitoring

13.126 The four surface water sub-catchments have been highlighted as being at risk of potential construction effects due to the nature of works within the catchments as well as their high sensitivity. Water quality monitoring during the construction phase would be undertaken, to ensure that none of the tributaries of the main channels are carrying pollutants or suspended solids. Monitoring would be carried out at a specified frequency (depending upon the construction phase) on these catchments.

13.127 The monitoring programme would make specific reference to the areas of

historic mining and the potential for the proposed construction works to disturb mining waste. The monitoring programme would be used to confirm the efficacy of the pollution mitigation measures deployed.



13.128 This monitoring would continue throughout the construction phase and immediately post construction. Monitoring would be used to allow a rapid response to any pollution incident as well as assess the impact of good practice or remedial measures. Monitoring frequency would increase during the construction phase if remedial measures to improve water quality were implemented. Detailed water quality monitoring plans would be developed during the detailed design (SLC, SEPA and the Clyde River Foundation would be consulted on the plan) and the agreed plan would form part of the final CEMP.

13.129 The water monitoring schedule would include parameters commonly

associated with mining and mining waste (such as lead, zinc, cadmium, copper and nickel.

13.130 The performance of the good practice measures would be kept under constant review by the water monitoring schedule, based on a comparison of data taken during construction with a baseline data set, sampled prior to the construction period.

Pollution Risk

13.131 Good practice measures in relation to pollution prevention would include the following:

• refuelling would take place at least 50m from watercourses and where

possible it would not occur when there is risk that oil from a spill could directly enter the water environment. For example, periods of heavy rainfall or when standing water is present would be avoided;

• foul water generated onsite would be managed in accordance with best practice and be drained to a sealed tank and routinely removed from Site;

• drip trays would be placed under vehicles when parked which could potentially leak fuel/oils;

• areas would be designated for washout of vehicles which are a minimum distance of 50m from a watercourse;

• washout water would also be stored in the washout area before being treated and disposed of;

• if any water is contaminated with silt or chemicals, runoff would not enter a watercourse directly or indirectly without treatment;

• water would be prevented as far as possible, from entering excavations; • procedures would be adhered to for storage of fuels and other potentially

contaminative materials in line with the Water Environment (Oil Storage) (Scotland) Regulations 2006, to minimise the potential for accidental spillage (e.g. stored in 110% bunded storage facilities); and

• a plan for dealing with spillage incidents would be designed prior to construction, and this would be adhered to should any incident occur, reducing the effect as far as practicable. This would be included in the final CEMP.

13.132 Site investigation (e.g. trial pitting and/or boreholes) would be undertaken

prior to any construction works where excavation would be required to establish the wind farm and it would inform detailed design and construction



methods to ensure pollution risk is considered prior to construction. These methods would be specified in the final CEMP.

13.133 Where foundations or slabs are required, for example at turbine foundations, below transformers and battery storage units at the substation, site investigation would be undertaken to confirm ground conditions and inform the detailed design of these components, thereby limiting the potential for ground instability and pollution risk.

13.134 During the detailed design, areas of potential historic mining would be clearly

delineated and where construction works might intercept these a tool box of pollution control measures would be specified in the site CEMP to ensure sediments and potential remobilisation of contaminants would not occur. The efficacy of these measures would be assessed by routine inspection and water quality monitoring. Further details of erosion and sedimentation control measures that could be deployed are given below.

Erosion and Sedimentation

13.135 Good practice measures for the management or erosion and sedimentation would include the following:

• all stockpiled materials would be located outwith a 50m buffer from

watercourses; • stockpiled material would either be seeded or appropriately covered; • water would be prevented as far as possible, from entering excavations

through the use of appropriate cut-off drainage; • where the above is not possible, water that enters excavations would pass

through a number of settlement lagoons and silt/sediment traps to remove silt prior to discharge into the surrounding drainage system. Detailed assessment of ground conditions would be required to identify locations where settlement lagoons would be feasible;

• clean and dirty water onsite would be separated and dirty water would be filtered before entering the stream network;

• if the material is stockpiled on a slope, silt fences would be located at the toe of the slope to reduce sediment transport;

• the amount of ground exposed, and time period during which it is exposed, would be kept to a minimum and appropriate drainage would be in place to prevent surface water entering deep excavations;

• a design of drainage systems and associated measures to minimise sedimentation into natural watercourses would be developed - this may include silt traps, check dams and/ or diffuse drainage;

• silt/sediment traps, single size aggregate, geotextiles or straw bales would be used to filter any coarse material and prevent increased levels of sediment. Further to this, activities involving the movement or use of fine sediment would avoid periods of heavy rainfall where possible; and

• innogy’s construction personnel and the Principal Contractor would carry out regular visual inspections of watercourses to check for suspended solids.



Flood Risk

13.136 It is proposed to adopt Sustainable Drainage Systems (SuDS) as part of the proposed development.

13.137 SuDS techniques aim to mimic pre-development runoff conditions and balance or throttle flows to the rate of runoff that might have been experienced at the Site prior to development. Good practice in relation to the management of surface water runoff rates and volumes and potential for localised fluvial flood risk would include the following:

• drainage systems would be designed to ensure that any sediment,

pollutants or foreign materials which may cause blockages are removed before water is discharged into a watercourse;

• onsite drainage would be subject to routine checks to ensure that there is no build-up of sediment or foreign materials which may reduce the efficiency of the original drainage design causing localised flooding;

• appropriate drainage would attenuate runoff rates and reduce runoff volumes to ensure minimal effect upon flood risk;

• where necessary, check dams would be used within cable trenches in order to prevent trenches developing into preferential flow pathways; and

• as per good practice for pollution and sediment management, prior to construction, section specific drainage plans would be developed and construction personnel made familiar with the implementation of these.

13.138 Further information on ground conditions and drainage designs would be

provided in the final CEMP.

Water Abstractions

13.139 Abstraction of water for construction activities is proposed from a suitable source yet to be identified. An application for a CAR Licence would be submitted to SEPA and managed through the regulation of the CAR Licence. Should a suitable source not be identified, a water bowser would be used.

13.140 Good practice that would be followed in addition to the CAR Licence

regulations includes:

• water use would be planned so as to minimise abstraction volumes; • water would be re-used where possible; • abstraction volumes would be recorded; and • abstraction rates would be controlled to prevent significant water depletion

in a source.

Watercourse Crossings

13.141 Three new water crossings are required during the construction phase and would remain in place during the operational phase. Their locations are shown on Figure 13.1.



13.142 Good practice in relation to water crossings involves the following aspects:

• the appropriate crossing type would be identified from SEPAs best practice guidance and would take into account any ecological and hydrological constraints; and

• the crossing would be sized and designed so as to minimise effect upon flood risk (sized to accommodate at least the 200 year flow).

Construction Effects of the Proposed Development

13.143 Construction activities, as set out in Chapter 3: Description of the Development, have the potential to affect hydrological receptors and these are assessed below.

13.144 The assessment assumes that good practice (see Good Practice Measures,

above) would be applied throughout construction and the levels of predicted magnitude are based on this assumption.

Predicted Effects

Pollution Risk

13.145 During the construction phase, there is the potential for a pollution event to affect surface water bodies impacting on their water quality. This would have a negative effect on the receptor and the resulting degradation of the water quality would impact on any aquatic life and private water supplies abstracting from the watercourse.

13.146 Pollution may occur from excavated and stockpiled materials during Site

preparation. Contamination of surface water runoff from machinery, leakage and spills of chemicals from vehicle use and the construction of infrastructure also have the potential to affect surface water bodies. Potential pollutants include sediment, oil, fuels and cement.

13.147 The risk of a pollution incident occurring would be managed using good

practice measures as detailed above. Many of these practices are concerned with undertaking construction activities away from watercourses and identifying safe areas for stockpiling or storage of potential pollutants that could otherwise lead to the pollution of watercourses.

13.148 The baseline assessment has shown that the proposed development would

be located in the catchments of the River Clyde, Glengonnar Water and Shortcleuch / Elvan Water and their smaller tributaries. Fisheries data has shown the presence of trout in these watercourses.

13.149 After consideration of good practice measures the magnitude of a pollution

event within the surface water sub-catchments is considered Negligible following adherence to good practice measures. With good practice measures, the duration of a Negligible magnitude event could vary from short to longer term.



13.150 The potential effect of a Negligible magnitude event on watercourses of moderate (the River Clyde and Glengonnar Water) and high (the Elvan Water) sensitivity would be of negligible significance. No further mitigation measures are required.

13.151 The groundwater bodies extending beyond the study area are very large

when compared to the area of proposed development. Any effects are judged not to be detectable beyond the study area. Potential pollution events occurring during the construction of the turbines or any hardstanding would be of Negligible magnitude as they would be controlled by good practice measures and would be subject to some attenuation in the soils before reaching groundwater. Should pollutants reach the groundwater the scale of the effect would be low in relation to the overall groundwater body. The effect to groundwater, which has been assigned a moderate sensitivity, is therefore assessed as having negligible significance. No further mitigation measures are required.


13.152 Site traffic during the construction phase has the potential to cause erosion and increase in sedimentation loading during earthworks, and due to increased areas of hard-standing and such features as stockpiles, tracks and excavations etc., which could be washed by rainfall or inappropriate site practices, into surface water features. This has the potential to reduce the surface water quality, increase turbidity levels, reduce light and oxygen levels and effect ecology including fish populations. After consideration of good practice measures, the magnitude of impact to the receptors is assessed as Negligible and therefore with the moderate and high sensitivity receptors described above, the significance of effect without mitigation is assessed as negligible and no further mitigation measures are required.

13.153 Excavations, construction of hardstanding, diversion of drainage channels

and construction of water crossings are the key sources of sediment generation. Adherence to good practice measures would ensure that any material generated is not transported into nearby watercourses.

13.154 ‘Location specific’ good practice measures would be specified in the final

CEMP and be identified on site by the site ECoW to control the amount of fine sediment that could potentially enter a watercourse if not managed appropriately. These measures would potentially include cut-off drainage, sediment traps and sumps.

Flood Risk

13.155 Construction of hardstanding including the substation, construction compound and turbine bases would create impermeable surface areas. This would lead to a relatively small increase in the total impermeable surface area of the Site causing negligible increases in runoff rates and volumes within four surface water sub-catchments.



13.156 The proposed access track crosses a tributary of the Glengonnar Water (WC2),a tributary of Elvan Water (WC1) and a tributary of the River Clyde (WC3)which are presented on Figure 13.1. The greatest risk of localised flooding would be at these locations where any blockage would reduce the ability of the channel to convey water leading to short duration, localised flooding.

13.157 To mitigate this risk, the drainage design would ensure management of any

increase in runoff volumes for a 1 in 200 year return period at the detailed design stage. During the construction phase, the good practice measures would be in place to prevent materials entering watercourses and to ensure that man-made drains and blockages do not lead to bank erosion and localised flooding.

13.158 Adherence with good practice measures including appropriate drainage

design and compliance with the final CEMP would limit potential effects to being local and short duration and so of negligible magnitude.

13.159 It is proposed that any rainwater and limited groundwater ingress which

collects in the turbine excavations during construction would be stored and attenuated prior to controlled discharge to ground adjacent to the excavation.

13.160 Attenuation of runoff generated within the proposed turbine excavations

would allow settlement of suspended solids within the runoff prior to discharge in accordance with 'Site control' component of the SuDS 'management train'.

13.161 The potential effect of a short term increase in runoff on the hydrological

receptors is therefore assessed of negligible significance. No further mitigation is therefore required.

13.162 The magnitude of the increase in impermeable area is not sufficient to have a

measurable effect on groundwater levels, as the extent of the impermeable area is insignificant compared to the extent of the underlying geology and groundwater. Therefore, groundwater flood risk is not considered in this assessment.

Infrastructure and Man-made Drainage

13.163 During the construction period, drainage would be required to ensure construction areas are workable and not saturated. In particular, drainage, some of which would be temporary, would be required around turbine working areas, the construction compound and substation to manage surface flows. Excavation of turbine foundations may require temporary de-watering for the period of the foundation build. These drainage activities may lead to temporary changes, in the water table surrounding these construction activities (where de-watering is required below the level of the natural water-table).

13.164 As construction of proposed infrastructure is required through the buffers

associated with potential GWDTEs, there is potential to disrupt water



contributions to these habitats. However, Technical Appendix 13.1: GWDTE demonstrates that the areas of potential GWDTE are sustained by surface water rather than groundwater and that the construction of the proposed development would have no long term effect on any potential GWDTE habitat.

13.165 The potential effect of the proposed development on groundwater and areas

of potential GWDTE is not considered to change during the operation of the proposed development and therefore has not been considered under operational effects.

13.166 Excavations associated with construction works (e.g. cut tracks, turbine

bases foundations, cable trenches etc.) can result in local lowering of the water table. This is important in areas of peat deposits (e.g. T7), where the water table is characteristically near the ground surface (e.g. where the excavations are likely to intercept the groundwater table) and/or areas where there are groundwater dependent water supplies. The fieldwork and baseline studies have confirmed there are only isolated peat deposits identified within the study area, around the summits of Harryburn Brae and Peat Hill in the north of the Site.

13.167 Dewatering associated with construction of turbine foundations is commonly

temporary and dewatering following construction would not be required. Cable laying, without appropriate mitigation measures, can also lower high groundwater levels and provide a preferential drainage route for groundwater movement that can lead to local and permanent drying of soils/superficial deposits and / or water supplies.

13.168 The design of the proposed development has avoided areas of ecological or

habitat interest wherever possible. Furthermore, the underlying bedrock has little groundwater and therefore limited or little dewatering is likely to be required. There remains potential, however, for local dewatering of soils near cable trenches and turbine bases, without incorporation of mitigation measures.

13.169 Private water supplies from groundwater have been identified and a

groundwater source at North Shortcleuch has been proven to be potentially in hydraulic continuity with the proposed development (see Private Water Supplies, Groundwater Abstractions, Use and Quality).

13.170 Development of the access tracks could affect the quantity and quality of

water that drains to the North Shortcleuch water source. The magnitude of potential effect on the associated private water supply is assessed as Medium. Given it is a High sensitivity receptor the potential effect is of medium significance.

13.171 The sensitivity of groundwater (and habitat that may be dependent on

groundwater) receptor has been assessed as being Moderate. However, as discussed above and as a consequence of the site geology, the extent of any dewatering would be very small. Without mitigation the magnitude of impact is assessed as Negligible and therefore the potential significance of effect of



changing groundwater levels and flow due to dewatering is considered negligible significance and requires no further mitigation.

Water Abstraction

13.172 During the construction of the proposed development, water may be abstracted for uses such as dust suppression, vehicle washing and welfare facilities. The volume of water and mitigation required would be regulated through CAR and therefore the magnitude of an effect on groundwater-surface water interactions is considered Negligible. The significance of effect is therefore negligible.

Proposed Mitigation

13.173 With the exception of the North Shortcleuch private water supply source, there are no predicted significant effects under the terms of the EIA Regulations. Other than the good practice measures that the developer would implement as standard (and as described above), no specific mitigation, during construction, is therefore identified to be required.

13.174 Prior to construction of the proposed access track near to the North Shortcleuch private water supply, a programme of baseline water monitoring would be completed to confirm baseline water quantities and quality. These data would be used to assess the suitability of the water source and provide a monitoring record to which monitoring data collected during construction and operation of the wind farm can assessed.

13.175 It is noted that as the North Shortcleuch private water supply is located more

than 500m from the proposed infrastructure and as a consequence of the proposed best practice measures no impact on the private water supply is predicted; the proposed monitoring, which would be specified in the final CEMP, would be used to confirm this. The CEMP would also specify trigger levels and action plan should a variance of water be recorded compared to baseline conditions.

13.176 With this mitigation in place, which it is expected would be secured by an

appropriately worded planning condition, the magnitude of impact is assessed as Negligible and therefore the potential significance of effect on the North Shortcleuch private water supply is considered negligible and requires no further mitigation.

Residual Effects

13.177 No significant residual effects on surface water or groundwater receptors are predicted during the construction period of the proposed development.



Operational Effects of Proposed Development

13.178 During the operational phase of the proposed development, routine maintenance of infrastructure and tracks would be required across the Site. This may include work such as maintaining wind farm tracks, maintaining drainage paths and turbine maintenance.

13.179 Should any maintenance be required onsite during the operational life of the

project which would involve construction type activities; mitigation measures would be adhered to along with the measures in the final CEMP to avoid potential effects.

Predicted Effects

Pollution Risk

13.180 The possibility of a pollution event occurring during operation is very unlikely. There would be a limited number of vehicles required onsite for routine maintenance and innogy’s operational presence. Storage of fuels/oils onsite would be limited to the hydraulic oil required in turbine gearboxes and this is bunded to 110% bund capacity to prevent fluid escaping.

13.181 Based upon this, the potential risk associated with frequency, duration and

likelihood of a pollution event is low. It is therefore anticipated that the magnitude of a pollution event during the operational phase of the development would be Negligible, as no detectable change is likely to occur. Therefore, the significance of a pollution event during the operational phase of the development is predicted to be negligible for all receptors. No mitigation is therefore required.


13.182 During the operation of the development, it is not anticipated that there would be any excavation or stockpiled material, reducing the potential for erosion and sedimentation effects.

13.183 Immediately post-construction, newly excavated drains and track dressings

may be prone to erosion as any vegetation would not have matured. Appropriate design of the drainage system, incorporating sediment traps, would reduce the potential for the increased delivery of sediment to natural watercourses. Potential effects from sedimentation or erosion during the operational phase are considered to come from linear features on steeper slopes, where velocities in drainage channels are higher. Immediately post-construction, flow attenuation measures would remain and be maintained to slow runoff velocities and prevent erosion until vegetation becomes established.

13.184 The likelihood, magnitude and duration of a potential erosion and

sedimentation event occurring within the surface water catchments would be negligible following adherence to good practice measures. Therefore, the



potential effect on these high sensitivity receptors is of negligible significance. No mitigation is therefore required.

13.185 Should any non-routine maintenance be required at the sections of track

crossing wet areas (defined visually onsite by a contractor or operational personnel) there would be potential for erosion and sedimentation effects to occur due to the existence of disturbed material. Should this type of activity be required, then the good practice measures as detailed for the construction phase would be required on a case by case basis. Extensive work at water crossings/adjacent to the water environment may require approval from SEPA under the CAR (depending upon the nature of the activity).

Fluvial Flood Risk

13.186 The risk of an effect on fluvial flood risk arises as a result of a potential restriction of flow at a permanent water crossing following intense rainfall. In accordance with good practice routine inspection of the culverts at the Site would be undertaken, reducing the likelihood of a blockage occurring. In the unlikely event of a blockage any flooding would be localised and the magnitude of impact is assessed as Negligible, and thus the significance of effect is assessed as negligible, and no further mitigation is identified to be required.

Infrastructure and Man-Made Drainage

13.187 Operation of the proposed development requires limited activities relative to the construction phase.

13.188 The magnitude of a potential effect on groundwater and sub-surface flows as

a result of the proposed access tracks, permanent hardstanding and associated drainage would be negligible on the overall groundwater body due to the dispersed nature of the proposed hardstanding and the low bulk permeability of the soils and geology at site. The significance of effect is negligible. No further mitigation is required.

Proposed Mitigation

13.189 As there are no predicted significant effects under the terms of the EIA Regulations, other than the good practice measures (see Good Practice Measures) that innogy implement as standard, no specific mitigation, during operation, is required.

Residual Effects

13.190 No significant residual effects on surface water or groundwater receptors are predicted during the operational period of the proposed development.



Cumulative Effects Assessment

13.191 This section considers the potential cumulative hydrological effect of the proposed development taking into consideration other wind farm developments within the same hydrological catchments as the proposed development and within 5km of any proposed infrastructure. Any developments which are outwith the study area are not considered.

13.192 The proposed development lies within the sub-catchments of the River Clyde

Shortcleuch / Elvan Water and Glengonnar Water. There is no existing or proposed wind farm development in these catchments; cumulative effects in these catchments are not considered further.

13.193 It is recognised that there are consented wind farms in the catchment of the

River Clyde upstream of the Site e.g. Clyde and North Lowther, and that the proposed development lies within sub-catchments of the River Clyde. However Clyde and North Lowther wind farms do no lie in the same sub-catchments and are located sufficiently far away from the proposed development that any cumulative effects associated with these developments is unlikely to be discernible in the River Clyde.

Further Survey Requirements and Monitoring (if required)

13.194 This Chapter has demonstrated that the potential impacts of the proposed development that have been assessed are not likely to have significant effects on the study area’s hydrological receptors. The lack of significant effects relates primarily to the proposed ‘Good Practice Measures’, proposed water quality monitoring and the iterative design process (Chapter 3: Description of the Development), which effectively act as ‘designed-in’ mitigation.

13.195 No other further surveys or monitoring is considered necessary.



Summary of Effects

13.196 A summary of effects and proposed mitigation measures required to reduce the potential effects to acceptable levels are identified in Table 13-15.

Table 13-15: Summary of Residual Effect after Mitigation

Potential Effect

Significance of Effect before Mitigation

Proposed Mitigation / Enhancements

Significance of Residual Effect

Pollution, Erosion and Sedimentation

Construction

Negligible - Moderate

None required above good practice techniques and water quality monitoring Monitoring of the North Shortcleuch PWS

Negligible

Operation

No additional mitigation measures required.

Cumulative

There are no predicted cumulative effects of the development within the hydrological study area.

Statement of Significance

13.197 This chapter has assessed the likely significance of effects of the proposed development on the hydrology, hydrogeology.

13.198 The proposed development has been assessed as having no significant

effects following adoption of good practice measures and specific mitigation measures. There are also no potential cumulative effects with any other developments.

HYDROGEOLOGY AND HYDROLOGY 13 - Über innogy · 13.1 This Chapter assesses the impacts of the proposed evelopment on d hydrogeology and hydrology (the water environment). The assessment

Documents