Rooley Moor Wind Farm Chapter 7: Hydrology, … Report C532 Control of water pollution from...

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Rooley Moor Wind Farm Environmental Statement

Rooley Moor Wind Farm

Chapter 7: Hydrology, Hydrogeology and Geology

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7. Hydrology, Hydrogeology and Geology ..................................................................................................................................7-3

7.1 Introduction ..................................................................................................................................................................................7-3

7.2 Objectives ....................................................................................................................................................................................7-3

7.3 Statutory, Planning Policy, Legislation and General Guidance ....................................................................................................7-3

Statutory Planning Policy and Legislation ....................................................................................................................................7-3 7.3.1

General Guidance ........................................................................................................................................................................7-4 7.3.2

7.4 Consultation and Scoping ............................................................................................................................................................7-4

7.5 Methodology .................................................................................................................................................................................7-7

Baseline Determination ................................................................................................................................................................7-8 7.5.1

7.6 Baseline Conditions ...................................................................................................................................................................7-13

Study Area .................................................................................................................................................................................7-13 7.6.1

Climate and Topography ............................................................................................................................................................7-13 7.6.2

Statutory Designated Sites .........................................................................................................................................................7-13 7.6.3

Hydrology ...................................................................................................................................................................................7-14 7.6.4

Flood Risk ..................................................................................................................................................................................7-16 7.6.5

Geology and Peat ......................................................................................................................................................................7-18 7.6.6

Groundwater ..............................................................................................................................................................................7-20 7.6.7

Groundwater Dependent Terrestrial Ecosystems ......................................................................................................................7-21 7.6.8

Public Water Supplies and United Utilities Assets .....................................................................................................................7-23 7.6.9

Private Water Supplies (PWS) ...................................................................................................................................................7-24 7.6.10

7.7 Baseline Sensitivity ....................................................................................................................................................................7-25

Overall Surface Water Sensitivity ...............................................................................................................................................7-25 7.7.1

Overall Groundwater Sensitivity .................................................................................................................................................7-25 7.7.2

Overall Geology Sensitivity ........................................................................................................................................................7-25 7.7.3

7.8 Design Evolution ........................................................................................................................................................................7-26

7.9 Standard Practice Measures ......................................................................................................................................................7-26

Development of a Detailed Construction Method Statement (CMS) ..........................................................................................7-26 7.9.1

Development of a Construction Environmental Management Plan (CEMP) ..............................................................................7-26 7.9.2

Drainage Management Plan (DMP) ...........................................................................................................................................7-27 7.9.3

Water Quality Monitoring ............................................................................................................................................................7-27 7.9.4

Provision of an Environmental Clerk of Works (ECoW) .............................................................................................................7-28 7.9.5

7.10 Predicted Impacts ......................................................................................................................................................................7-28

Construction ...............................................................................................................................................................................7-28 7.10.1

Operation ...................................................................................................................................................................................7-33 7.10.2

Decommissioning .......................................................................................................................................................................7-35 7.10.3

7.11 Summary of Potential Impacts and Mitigation Measures ...........................................................................................................7-35

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7.12 Mitigation Measures ...................................................................................................................................................................7-41

Access Tracks ............................................................................................................................................................................7-41 7.12.1

Watercourse Crossings ..............................................................................................................................................................7-42 7.12.2

Wind Turbine Foundations and Hardstandings ..........................................................................................................................7-42 7.12.3

Substation Compound and Temporary Construction Compound ..............................................................................................7-43 7.12.4

Electric Cabling ..........................................................................................................................................................................7-43 7.12.5

Borrow Pits .................................................................................................................................................................................7-44 7.12.6

7.13 Residual Effects .........................................................................................................................................................................7-45

Construction ...............................................................................................................................................................................7-45 7.13.1

Operation ...................................................................................................................................................................................7-46 7.13.2

Decommissioning .......................................................................................................................................................................7-46 7.13.3

7.14 Cumulative Impacts ....................................................................................................................................................................7-46

7.15 Summary and Conclusions ........................................................................................................................................................7-48

Appendix 7.1: Private Water Supply Assessment

Appendix 7.2: Outline Peat Management Plan

Appendix 7.3: Peat Slide Risk Assessment

Appendix 7.4: Mining Risk Assessment

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7. Hydrology, Hydrogeology and Geology

7.1 Introduction

7.1. This chapter assesses potential impacts to identified hydrological, hydrogeological and geological and

receptors during the construction, operation and decommissioning of the development and outlines

mitigation measures required to reduce any identified potential impacts of the development.

7.2. Information provided within this chapter is based upon the results of a desk based study utilising

published resources, consultation with relevant stakeholders and statutory bodies, several site visits

and collected field data.

7.3. The chapter is primarily concerned with the Development Area (as described in Chapter 4:

Development Description, and shown in Figure 4.1 and land which is hydraulically connected to the

Development Area.

7.2 Objectives

7.4. Rooley Moor Wind Farm, and outlines mitigation measures required to control the predicted effects of

the Development. Potential effects to hydrology, hydrogeology and geology include:

Changes to drainage patterns;

Changes to flood risk;

Changes to the quality and/or quantity of surface water and groundwater;

Pollution of public water sources and/or private water supplies (PWS); and

Other changes to downstream watercourses including changes in erosion and deposition patterns.

7.3 Statutory, Planning Policy, Legislation and General Guidance

7.5. This assessment has been undertaken with regard to statutory and general guidance, and a range of

environmental legislation including the following:

Statutory Planning Policy and Legislation 7.3.1

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

Environmental Protection Act 1990;

Water Resource Act 1991;

Groundwater (England and Wales) Regulations 2009;

UK Water Quality (Water Supply) Regulations 2000 (amendment) Regulations 2007;

Freshwater Fish Directive (2006/44/EC);

Environment Act 1995;

Land Drainage Act 1991;

Environmental Damage (Prevention and Remediation) Regulations 2009;

Town and Country Planning Act 2012;

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Private Water Supply Regulations 2009;

Control of Pollution Act 1974; and

Contaminated Land (England) Regulations 2006.

General Guidance 7.3.2

National Planning Policy Framework, Department for Communities and Local Government (2012);

Environment Agency, Underground, Under Threat, Groundwater protection: policy and practice (GP3)

(2006);

Environment Agency, Piling and Penetrative Ground Improvement Methods on Land Affected by

Contamination: Guidance on Pollution Prevention (2001)

EA Pollution Prevention Guidance (PPG) Notes:

o PPG 1 General guide to the prevention of water pollution (2001);

o PPG 2 Above ground oil storage tanks (2004);

o PPG 3 Use and design of oil separators in surface water drainage systems (2006);

o PPG 5 Works in, near or liable to affect watercourses (2007);

o PPG 6 Working at construction and demolition sites (2003);

o PPG 21 Pollution incident response planning;

o PPG22 Incident Response – Dealing with Spills; and

o PPG23 Maintenance of Structures over Water.

CIRIA Report C532 Control of water pollution from construction sites (2001);

CIRIA Report C692 Environmental good practice on site (third edition) (2010); and

Construction Code of Practice for the Sustainable Use of Soils on Construction Sites (2009).

7.4 Consultation and Scoping

7.6. A summary of scoping and consultation responses in relation to this chapter is detailed in Table 7.1.

Copies of scoping responses received from the consultees can be found in Appendix 2.1.

Table 7.1 Scoping Responses

Authority Response Proposed Action

Environment

Agency (EA)

Flood Risk Assessment (FRA) should be

included.

FRA required – currently not included in

scope of works.

United

Utilities

Initial consultation highlighted concerns

around water quality both from construction

and long term running of the wind farm,

mainly related to colour and suspended

solids.

Water quality monitoring will be essential in

establishing a robust baseline for the

catchments around the wind farm. Peat

Majority of infrastructure to be located off

peat greater than 0.5m depth.

Coronation Power are working with UU and

have agreed that a joint approach to water

quality monitoring could support both the

development of the wind farm site and

assessment of ongoing peatland restoration

work being undertaken by UU. The

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discolouration of water supply is a key issue

for UU and presents an expensive on-going

problem to resolve. Any monitoring will need

to include for colour.

collaborative approach will look to share

data and rationalise monitoring and

sampling locations / regimes.

The Coal

Authority

Past coal mining activities and the presence

of surface coal resources should be

considered. This should take the form of a

risk assessment, together with mitigation

measures.

The location and stability of abandoned mine

entries should be considered and the extent

and stability of shallow mine workings,

outcropping coal seams, unrecorded mine

workings, minewater, hydrogeology and

mine gas should be considered.

Consider whether Coal Authority permission

is required to intersect, enter or disturb and

coal or coal workings during site

investigation or development work

If surface coal resources are present,

consider whether prior extraction of the

mineral resource is practicable and viable

Mining risk assessment has been

completed and is included as Appendix

7.4.

Lancashire

County

Council

The site is on Mineral Safeguarding Area

and survey work would need to prove peat

had been worked out and exhausted and

that any proposed development would not

damage the peat land resource.

A Mining Risk Assessment has been


7.4.

A Peat Management Plan (PMP), included

as Appendix 7.2 demonstrates that the

proposed development will not result in any

removal of peat from the site and highlights

restoration proposals for excavated peat.

Natural

England Impacts of development on hydrology

together with environmental and erosion

protection

Application falls within a priority habitat,

blanket peat

Requirements for EIA for wind farms on

peat greater than 0.5m provided in

“Investigating the impacts of wind farm

development on peatlands in England:

Part 1 Final Report”

Scope for mitigation of adverse impacts

and opportunities for improved peatland

management to be addressed

Design of the wind farm layout has avoided

peat over 0.5m in depth where possible as

demonstrated by evidence presented in the

Peat Slide Risk Assessment (PSRA)

included as Appendix 7.3. The EIA

assessment contained within this chapter

includes assessment of risk to peatland

resources with respect to potential changes

in hydrogeological regimes, while Chapter

8: Ecology assesses risk to peatland

habitat and Chapter 15: Other Issues

assesses any loss of peat as a function of

the overall carbon balance assessment for

the site.

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Compensation for adverse effects may

be possible through peat restoration

measures in the form of habitat

management plans

Functional components of the peat

system as a whole which includes areas

of non-active bog as well as active bog

should be considered.

Impacts on local geological sites should

be considered

Opportunities will be sought in conjunction

with UU for restoring peatland habitat as

detailed in Section 8.10.2 of Chapter 8:

Ecology.

Geological and hydrologically dependant

SSSIs have been identified within the

baseline and assessment reporting of this

Chapter.

Greater

Manchester

Ecology Unit

Comprehensive peat depth and quality

surveys required to inform layout of

turbines and access tracks and mitigate

for damage to peat

Mapping of bare peat, bare mineral

ground and areas partially vegetated

from aerial photographs

Develop a water accumulation indicator

map and wetness index using LiDAR

data

Ground truthing mapping and field

assessment to identify likely causes of

degradation and most appropriate

methods of remediating or restoring

Full details of measures to be taken to

mitigate any possible damage to peat

Hydrological studies should consider

potentially damaging impacts of drying

parts through increased drainage

Particular issues include:

o Constructing tracks on peat and

mineral soils

o Construction of turbine and crane

foundations on peat and mineral soils

o Dealing with surplus peat

o Dealing with surplus mineral

material/soils

o Installing trenches for HV cables

o Stream/drain crossing to avoid scour

and erosion

Surveys of peat depth and quality of peat

have been undertaken to inform PSRA

reporting and are presented in Appendix

7.3.

Best practice and mitigation measures

outlined in Section 7.12 will ensure residual

risk to peat is not significant.

Rochdale Council Should be cross referenced with ecology

chapter in relation to peatland condition

Impact on water quality from peat

The EIA assessment contained within this

chapter includes assessment of risk to

peatland resources with respect to potential

changes in hydrogeological regimes, while

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oxidisation and increased turbidity should

be assessed

Definition of deep peat being of a depth

of 2m or greater is flawed.

Reference should be made to

“Investigating the impacts of windfarm

development on peatlands in England:

Part 1 Final Report”

Account to be taken of existing

development at Scout Moor and lessons

learned from disturbance of substrate.

Flood Risk Assessment will be necessary

Coal Authority should be consulted for

mining records. BGS can also provide

relevant detailed information.

Baseline assessment should cross

reference Minerals and Waste DPD’s

covering the PDA, in particular Minerals

Safeguarding Areas.

Chapter 8: Ecology assesses risk to

peatland habitat and Chapter 15: Other

Issues assesses any loss of peat as a

function of the overall carbon balance

assessment for the site.

Mining risk assessment has been


7.4.

7.5 Methodology

7.7. This section outlines the methodology adopted to assess the effects impacts of the proposed

Development upon the local hydrological, hydrogeological, geological and peat environments.

7.8. The scope of the assessment is to identify:

Constraints on activities due to hydrology, hydrogeology, geology and peat;

Potential effects and risks associated with construction, operation and decommissioning activities that

can be controlled through best practice; and

The significance of residual effects.

7.9. Information provided within this chapter is based upon the results of a desk based study utilising

published resources, consultation with relevant stakeholders and statutory bodies and several site

visits during 2013 and 2014.

Table 7.2 Baseline Data Sources

Topic Source of data and information

Climate and

topography

Ordnance Survey mapping - Landranger Series (1:50,000)

Flood Estimation Handbook (FEH)

Surface water quality

and quantity

Rochdale Council and Rossendale Council

Environment Agency (EA)

United Utilities (UU)

Public water supplies, Rochdale Council and Rossendale Council

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Topic Source of data and information

Private water supplies

(PWS)

Property owners (information regarding private water supplies)

Fisheries Environment Agency (EA)

Groundwater

properties


Abesser, C, Shand, P. & Ingram, J, 2005. Baseline Report Series 18. The

Millstone Grit of Northern England. British Geological Survey Commissioned

Report No. CR/05/015N.

BGS UK Hydrogeology Viewer Available online at

http://mapapps.bgs.ac.uk/hydrogeologymap/hydromap.html Last accessed 20th

March 2014.

Solid and drift geology BGS GeoIndex Onshore online mapping

Bedrock geology (scale 1:50,000)

Superficial deposits (scale 1:50,000)

Faults and other linear features (scale 1:50,000)

Abstractions and

discharges


Rochdale Council and Rossendale Council

Baseline Determination 7.5.1

7.10. The methodology is based upon the collection of information from a wide variety of data sources

including published material and consultation with statutory bodies. Table 7.2 details the data sources

referred to throughout this assessment.

7.11. There are no relevant published guidelines or criteria for assessing and evaluating impacts on

hydrology, hydrogeology or geomorphology within the context of an EIA. This assessment is based on

a methodology derived from the Institute of Environmental Management and Assessment (IEMA)

guidance (2004) (Ref. 7-1). The methodology sets out a list of criteria for evaluating the environmental

impacts, as follows:

The type of impact (i.e. whether it is positive, negative, neutral or uncertain);

The policy importance of the resource under consideration on a scale of sensitivity (i.e. high, medium

or low) as defined within Table 7.3.

The magnitude of the impact in relation to the resource that has been evaluated, quantified using the

scale high, medium, low, or negligible defined within Table 7.4; and

The probability of the impact occurring based on the scale of certain, likely, unlikely, or rarely (Table

7.6 ).

Table 7.3 Definitions of Policy Importance and Sensitivity

Sensitivity Hydrological / hydrogeological / geological definition

High High environmental importance; international or national value including Ramsar sites;

Special Areas of Conservation (SAC); Special Protection Areas (SPAs); and Sites of

Special Scientific Interest (SSSIs);

WFD high/good ‘ecological status’

http://mapapps.bgs.ac.uk/hydrogeologymap/hydromap.html

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Sensitivity Hydrological / hydrogeological / geological definition

Public water supplies and principal or highly productive aquifers with high aquifer

vulnerability.

Nationally important fisheries containing protected species such as Freshwater Pearl

Mussel.

Areas with a high risk of flooding.

Medium WFD high/good ‘ecological and chemical status.’

Private water supplies.

Groundwater that supports highly dependent groundwater dependent terrestrial

ecosystems (GWDTE).

Areas with a moderate risk of flooding, with existing flooding being confined to areas

immediately adjacent to watercourses.

Highly productive aquifer with low to medium vulnerability or moderately productive

aquifers with high vulnerability.

Regionally important fisheries.

Pristine or active peat bog habitat; evidence that peat body has an intact hydrological

system/possibility that peat could recover to pristine status.

Low Low environmental importance (e.g. WFD poor/bad ‘ecological status’).

Low productivity/non aquifer.

Private water supplies located within the vicinity of a mains water supply or private

water supplies used for agricultural purposes and not for drinking water purposes.

Degraded fisheries or receptor not important for fisheries.

Low risk of flooding.

Groundwater that supports moderately dependent GWDTE.

Degraded or inactive peat; small isolated areas of peat; soil not sensitive to change,

e.g. degraded/grazed; shallow, evidence of widespread erosion. Significant active

land drainage has occurred resulting in ongoing dewatering of peat.

Table 7.4 Impact Magnitude Criteria

Receptor Magnitude

High Medium Low Negligible

Runoff regime Long term

irreversible change

in overall volume of

runoff from the

whole site and

changes to flow

paths and rates

resulting in change

in flood risk and

erosion potential.

Temporary change

in overall volume of

runoff from the

whole site and

changes to flow

paths and rates

resulting in change

in flood risk and

erosion potential.

Short term change

in volume of runoff

and changes to

flow paths and

rates in localised

areas of the site

resulting in change

in flood risk and

erosion potential to

localised areas

only.

No measureable

change in site

runoff regime

Surface water Measureable

change in water

Measureable

change in water

Measureable

change in water

No measureable

change in surface

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Receptor Magnitude


quality quality status with

respect to EQS for

more than one

month; long term

irreversible impact

on aquatic

ecosystems.

quality status with

respect to EQS for

less than one

month; temporary

impact on aquatic

ecosystems in the

medium term.

quality but no

change with

respect to EQS. No

significant impact

on aquatic

ecosystems.

water quality.

Water Supply Measurable

change in the

quality or volume of

the available

supply for

abstraction with

respect to The

Water Supply

Regulations;

leading to change

in water pressure

and/or in supply

volumes.

Measurable

change in the


the supply for more

than 1% of

samples with

respect to The

Water Supply

Regulations;

temporary visual

colouration change

and alteration to

sediment content.

Measurable

change in the


the supply for less

than 1%, but no

change with

respect to The

Water Supply

Regulations. No

change in pressure

or flow.

No measureable

change in water

supply.

Riverine flow

regime

Measurable

change in riverine

flows resulting in a

change in dilution

capacity or change

in flood risk for

watercourses or

water bodies

directly monitored

under the WFD.

Measurable

change in riverine

flows resulting in a

change in dilution

capacity or change

in flood risk for

smaller

watercourses or

water bodies, not

directly monitored

under the WFD.

Detectable change

in riverine flows but

no measurable

change in dilution

capacity or flood

risk.

No measureable

change in riverine

flow regime.

Geomorphology Permanent change

to geomorphology

over a large scale

including large

changes in erosion

and deposition

regimes.

Permanent change

in geomorphology

over a limited area

including some

changes in erosion

and deposition

regimes.

Temporary change

in geomorphology

over a limited area

including slight

changes in bed

morphology,

sedimentation

patterns and

erosion rates.

No change in

geomorphology.

Groundwater

flow regime

Irreversible or

permanent change

to the recharge,

flow or discharge of

groundwater. May

impact upon

Measurable

change to the

recharge, flow or

discharge of

groundwater. May

impact upon

Short term

reversible changes

to the recharge,

flow or discharge of

groundwater.

Impacts are limited

No measurable

change in the

recharge, flow or

discharge of

groundwater.

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Receptor Magnitude


licenced

groundwater

abstraction, water

supply to

ecosystem or

groundwater base

flow to a

watercourse such

that it impacts on

WFD criteria or

standards.

licenced

groundwater

abstraction, water

supply to

ecosystem or

groundwater base

flow to a

watercourse but

with no impact on

WFD standards.

Impacts affect

large or multiple

area(s).

to small discrete

areas.

Groundwater

Quality

Permanent or long

term (>one month)

change in

groundwater

quality with respect

to EQS for more

than one month.

Temporary change

in groundwater

quality, changing

site quality with

respect to EQS for

less than one

month.

Measurable but

temporary change

in groundwater

quality, but not

changing status

with respect to

EQS.

No measureable

change in

groundwater

quality.

Peat hydrology

/ Quality /

volume and

extent of peat

Significant

permanent

alteration to peat

hydrology resulting

in the change of

status of the peat

body.

Moderate alteration

to peat hydrology

resulting in

localised changes

in the status of

peat bodies. Any

changes are

largely temporary.

Minor alterations to

peat hydrology.

No measureable

change in peat

hydrology.

7.12. Professional judgement is used to assess the findings in relation to each of these criteria to give an

assessment of significance for each impact. This utilises the sensitivity of identified receptors (using

the criteria in Table 7.3) and the magnitude of potential impacts (using the criteria in Table 7.4).

Potential impacts are then evaluated as to whether they are considered to be of high, moderate, low,

or no significance. As a guide, a table has been developed whereby the combination of sensitivity and

magnitude give the significance of the potential impact (Table 7.5).

Table 7.5 Evaluation of Potential Impact

Receptor

Sensitivity

Magnitude of Impact

Negligible Low Medium High

High Not Significant Moderate Major Major

Medium Not Significant Minor Moderate Major

Low Not Significant Not Significant Minor Moderate

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7.13. The likelihood of potential impacts occurring is then assessed. To classify the probability of occurrence

for a potential impact it is necessary to understand how regularly a given event or outcome will come

to pass. This can be assessed in a number of ways including assessments based on historical data,

quantitative analysis, or experience from other similar sites. The likelihood of occurrence (Table 7.6 )

of potential impacts is then assessed against the criteria in ranging from a scale of rarely to certain.

Table 7.6 Definitions of Likelihood of Occurrence

Likelihood of occurrence Definition

Certain

Any consequence that is likely in the medium term and inevitable throughout

the assessment timescale. i.e. the consequence will happen if the

development goes ahead.

Likely There is a high probability that the consequence will be realized within the

lifetime of the development or duration of the activity.

Possible It is possible but unlikely that any consequence would arise during the

lifetime of the development.

Rarely There is a very low probability that any consequence will ever arise within the

lifetime of the development or duration of the activity.

7.14. The likelihood of significant impacts occurring is then combined with the evaluation of potential impacts to

assess likely significant impacts using the matrix in Table 7.7.

7.15. Typically, significant impacts assessed as minor, or less are considered not significant in terms of EIA.

Impacts evaluated as having a moderate or high significance are defined as significant for the purpose of the

EIA. If the assessment results in moderate or high significant impact, then additional mitigation measures

will need to be considered.

Table 7.7 Likely Significant Impact Matrix

Evaluation of

Potential Impact

Likelihood of Occurrence

Rarely Unlikely Likely Certain

Major Minor Moderate Major Major

Moderate Negligible Minor Moderate Moderate

Minor Negligible Negligible Minor Minor

Not Significant Negligible Negligible Negligible Negligible

7.16. The impacts recorded in highlighted cells are ‘significant’ in terms of the EIA Regulations (The Town

and Country Planning (Environmental Impact Assessment) Regulations 2011).

7.17. Mitigation measures to reduce the impact of any identified potential impacts identified to occur during

the construction, operation and decommissioning of the wind farm are then applied. The likelihood of

any residual significant impacts occurring after mitigation measures have been implemented is then

assessed using Table 7.6.

7.18. Table 7.7 is then used again to assess the residual likely significant impact.

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7.6 Baseline Conditions

Study Area 7.6.1

7.19. The Development Area mostly comprises open moorland across a high plateau. This study considers

impacts to hydrological, hydrogeological and geological receptors (including peat) within the

Development Area. Impacts to these receptors outside of the site boundary are considered for up to

2km, or further where a hydrological connection deems it necessary.

Climate and Topography 7.6.2

7.20. The average annual catchment rainfall for the area is approximately 1,510mm based on data obtained

from the FEH1, indicating a moderately wet climate having the potential to exhibit a moderately high

runoff regime.

7.21. The study area encompasses the eastern extent of an upland plateau which forms Rooley Moor,

Knowl Moor and Scout Moor. Much of the study area is elevated above 350 metres above ordnance

datum (m aOD) and encompasses three main peaks which form a north-south trending ridge along the

length of the Development Area. These peaks are;

Top of Leach located in the north of the study area, summit elevation 474m aOD;

Hammer Hill located in the centre of the study area, summit elevation 440m aOD; and

Top of Pike located in the south of the site, summit elevation 398m aOD.

7.22. These hills form the crest of a watershed which creates six surface water catchments; these are

described further below.

Statutory Designated Sites 7.6.3

7.23. There are no designated sites within the Development Area.

7.24. There is only one designated site within 1km of the Development Area, the Lee Quarry Site of Special

Scientific Interest (SSSI).

7.25. Lee Quarry is a large disused quarry on the south side of the Rossendale Valley, south of Bacup. The

quarry is a designated Geological SSSI because it is rich in trace-fossil assemblages and good

sedimentary features, making it of great importance to studies of late Carboniferous environments and

palaeogeography. Lee Quarry is now an important tourist attraction since being converted into a

purpose built mountain biking centre by Rossendale Borough Council. As the designation has no

hydrogeological or hydrological component and the quarry is located outside the Development area so

will not be impacted by wind farm activities. This feature is not considered further within this

assessment.

7.26. There is only one designated site within 2km of the Development Area; a Local Nature Reserve Site,

Healy Dell which is located approximately 1km from the Development Area in Spodden Valley on the

Rochdale-Whitworth border. The nature reserve has been designated for its natural beauty and

archaeological feature. No hydrological, hydrogeological or geological features have been identified as

relating to this designation and this feature is not considered further within this assessment.

1 FEH (Flood Estimation Handbook) CD-ROM 3 produced by the CEH (Centre for Ecology and Hydrology, 2009)

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Hydrology 7.6.4

Surface Water Catchments

7.27. The study area drains five surface water catchments. These catchments ultimately drain to the River

Irwell (north and west), the River Spodden (east) or Nadden Brook (south) (see Figure 7.1). Several of

the catchments contain United Utilities public water supply reservoirs which receive surface water

inputs from many of the watercourses located within the upper parts of the catchments. Outflow from

the reservoirs into the lower catchments is controlled by a series of sluice gates, these are further

described in Section 7.6.9.

Catchments draining to River Irwell

7.28. Cowpe Moss catchment is located towards the far north-west of the study area and contains the

Cowpe Moss reservoir, a raw water reservoir operated by United Utilities. The reservoir has been

constructed in the base of a very steep valley and is primarily fed by three, un-named surface water

sources which rise on the steep cliff above the reservoir. Ordnance survey mapping marks the

presence of numerous springs and wells above the reservoir, suggesting that groundwater may also

contribute water to the reservoir. Cowpe Reservoir also likely receives some runoff from the up

gradient Cowpe Moss area. The reservoir is stocked with trout and is a popular destination for local

angling groups and ultimately drains to the River Irwell located to the north. There are no surface

water courses which rise within Development Area and flow into Cowpe Moss catchment; the

Development Area runs along the watershed boundary of the catchment which means there is no

direct hydraulic connection between the site and Cowpe Moss catchment.

7.29. Greens Moor catchment drains the north of the site and is the only catchment which does not contain

a reservoir. The main surface watercourse is Well Clough and associated tributaries which rises within

the Development Area and flows north and discharges directly into the River Irwell c.1km north of the

Development Area. Lower in the catchment, typically below an elevation of 360m aOD, numerous

springs are mapped as emerging from the steep hillside which in turn feed a network of small streams

that ultimately discharge into the River Irwell. The nearest spring is over 250m down gradient of the

northern tip of the site boundary. Several disused quarries are located on the mid slopes of Greens

Moor catchment, including the Lee Quarries and associated SSSI.

Catchments draining to River Spodden

7.30. Cowm catchment is located in the north-east of the study area, a small (0.38km2) lobe of the

Development Area extends into the catchment. The Cowm catchment contains the Cowm Reservoir;

the reservoir is a United Utilities asset and is currently used as a recreational space. It is not used for

water supply. The Cowm catchment is drained by several surface water courses, namely:

Walstead Clough which rises near Old Slink Stack near the top of the catchment within the application

boundary and flows directly into Cowm Reservoir;

Cowm Brook (and nearby, un-named watercourses) rise mid-way down the Cowm catchment, over

185m down gradient of the site boundary and flow towards the former quarrying area, Britannia

quarries. The Britannia quarries contain several, artificial water bodies within the flooded quarry

working areas.

7.31. As for the Cowpe Moss catchment, OS mapping indicates the presence of numerous groundwater

springs emerging on the steep mid-slopes of the catchment.

CPL PAGE 7-15


7.32. Spring Mill and Prickshaw catchment is located on the eastern side of the Development Area. The

catchment contains the Spring Mill Reservoir and the Prickshaw Reservoir, both United Utilities assets

operated as a public water supply. All surface water courses in the upper part of the catchment drain

into the reservoirs.

7.33. Spring Mill reservoir receives flow from:

the Prickshaw Brook which rises towards the top of the catchment, outwith the Development Area; and

The Fern Isle Brooks, which is a major tributary of the Prickshaw Brook and the confluence is located

approximately 300m up gradient of the reservoir. The headwaters of the Fern Isle Brook rise within

the Development Area near the disused Bagden Quarry.

7.34. The Prickshaw Reservoir comprises three small water bodies which are fed by one main, un-named

surface water course which rises within the Development Area near Prickshaw Slack.

Catchments draining to Naden Brook

7.35. Naden and Greenbooth Reservoir catchment is the largest of the study area catchments at 10km2

and drains into a series of reservoirs before discharging into the Naden Brook 1km to the south of the

Development Area. Much of the western half of this catchment is located within the Development

Area.

7.36. Little Ding and Ding Clough surface watercourses rise within the Development Area, just below the

disused Ding Quarry. Both streams flow due south and discharge into the Naden Higher Reservoir.

7.37. An un-named stream with five tributaries flows into the Naden Higher Reservoir on its eastern bank.

The headwaters of the stream rise within the Development Area;

7.38. An un-named stream flows into the Naden Middle Reservoir on its eastern bank. The headwaters of

the stream rise within the Development Area;

A small spring watercourses rises at Forsyth Brow, close to the Development Area and flows east and

discharges into the Greenbooth Reservoir;

A further two small spring fed watercourses rise at Forsyth Brow and flow south, ultimately discharging

into the Naden Brook 1km to the south of the Development Area.

Surface Water Quality

7.39. As part of the requirements for the Water Framework Directive (WFD), the EA has described the

general quality of watercourses within each river basin district and the pressures the water

environment faces. The study area falls within Irwell Catchment in the North West river basin district.

The surface watercourses identified within the Development Area have not been assessed by the EA

as they are too small, however, the three main receiving watercourses, the River Irwell, River Spodden

and Nadden Brook have been assessed and a summary of their current and future predicted status

(using criteria defined under the WFD) is presented in Table 7.7.

Table 7.7 Summary of Surface Water Quality2

WFD Parameter River Irwell River Spodden Naden Brook

Hydromorphological Status Heavily modified Heavily modified Heavily modified

2 Data from Environment Agency, available online at http://maps.environment-agency.gov.uk/wiyby/wiyby Last Accessed 20th

March 2014.

http://maps.environment-agency.gov.uk/wiyby/wiybyController?x=357683.0&y=355134.0&scale=1&layerGroups=default&ep=map&textonly=off&lang=_e&topic=wfd_rivers

CPL PAGE 7-16


WFD Parameter River Irwell River Spodden Naden Brook

Current Ecological quality Moderate Potential Moderate Potential Moderate Potential

Current Chemical Quality Good *DRA *DRA

2015 predicted ecological quality Moderate Potential Moderate Potential Moderate Potential

2015 predicted chemical quality Good *DRA *DRA

Overall Risk At risk At Risk At Risk

Biological Quality

Overall biological quality Poor *NA Moderate

Diatoms *NA Good *NA

Fish Poor Good Good

Macro-invertebrates Moderate Moderate

General Physico Chemical Quality

Ammonia High High High

Dissolved Oxygen High High High

pH High High High

Phosphate Good High High

Specific Pollutants Quality

Ammonia High High High

Copper High High High

Iron High High High

Zinc High High High

* DRA = Does Not Require Assessment

* NA = Not Assessed

7.40. In summary, chemical water quality for all three receiving watercourses is high despite only the River

Irwell requiring assessment for chemical quality.

Flood Risk 7.6.5

Fluvial Flood Risk

7.41. Indicative flood mapping published by the EA3 shows the Development Area is located entirely outside

the mapped floodplain, indicating that this risk is negligible.


March 2014.


CPL PAGE 7-17


Surface Water Flood Risk

7.42. Indicative surface water flood risk mapping published by the EA3 suggests the risk of flooding is

generally very low. Areas of medium and high surface water flood risk do occur within the

Development Area and wider study area; these areas are concentrated along existing surface water

flow paths and topographic lows such as gullies or former quarry areas.

7.43. During rainfall events, flows pass overland following topographic grades to gullies in peat, watercourse

channels or tributaries down-slope and eventually into the receiving catchment watercourses as

defined in the surface water section above. It is likely that once flows are in these channels, they will

travel relatively quickly off the steep hillsides. Potential exists for localised surface ponding of water

during or following these conditions; however, flooding is likely to be shallow and only inundate some

isolated low lying areas, for instance in the areas directly adjacent to watercourses.

Artificial Drainage Systems

7.44. The existing Rooley Moor Road public bridleway and other minor public paths cross several minor

watercourses within the Development Area. Culverts are generally used to convey flow under the

tracks, the majority of which were observed to be in good condition and free of debris. Plate 1 and

Plate 2 below detail an example of an existing crossing on Rooley Moor Road on a tributary of Higher

Naden Reservoir, at NGR 385745 418172.

Plate 1 Rooley Moor Road existing crossing Plate 2 View downstream from existing crossing

7.45. Topography and indicative flood risk mapping provided by the EA shows the Development Area to be

generally at low risk of inundation mainly limited to a risk during high rainfall conditions causing

overland flow and minor isolated ponding in some areas, particularly around areas which are saturated

under normal conditions, i.e. stream margins and boggy areas.

Tidal Flood Risk

7.46. The Development Area is over 350m above sea level at its lowest point; therefore this risk does not

apply.

CPL PAGE 7-18


Groundwater Flood Risk

7.47. Groundwater flooding is not considered to be a risk to the development. This is due to the steep

topography of the site and the relative depth to the regional water table (springs mapped from 360m

aOD), over 50m below the minimum site elevation.

Geology and Peat 7.6.6

Superficial Geology

7.48. British Geological Survey (BGS) 1:50,000 scale superficial mapping shows superficial deposits are

largely absent from much of the Development Area and there are large areas where the bedrock

outcrops at the surface. However, areas of superficial deposits have been mapped; Glacial Till

comprising stiff grey brown sandy silty clay with occasional gravel and cobbles is shown across the

very southern part of the Development Area and locally around Prickshaw in the south and east. A

small, isolated area of Head deposits is shown around the Rooley Moor Brow area comprising glacially

derived materials.

Bedrock and Structural Geology

7.49. The bedrock on site and in the wider study area comprises rocks from the Upper Carboniferous period

(Figure 7.2). The outcrop in the northern and central part of the Development Area comprises the

Namurian Millstone Grit (NMG) series which are overlain by the Westphalian Pennine Lower Coal

Measures (PLCM) in the southern part of the Development Area. Towards the north, the NMG is

faulted against the PLCM in a series of normal faults.

7.50. The NMG comprises a thick succession of interbedded sandstones, siltstones, mudstones and

subordinate thin coals and seat earths. The PLCM comprises alternating sandstone and shale strata

and several significant coal seams which were extensively mined in the past.

7.51. The study area is located on the crest of a large south-west trending open fold of the Rossendale

Anticline. The oldest rocks of the NMG are exposed in the core of the anticline in the centre of the site.

The bedrock geology is faulted by many north-west to south trending normal faults. These faults have

formed a series of graben and half graben blocks across the area.

Peat

7.52. BGS 1:50,000 scale superficial geological mapping shows the presence of peat deposits in the

northern, eastern and western areas of the site (see Figure 7.3). The southern half of the site is

mapped as being peat free. Peat probing was carried out across the study area at 348 locations on a

100m grid, the detailed results of this exercise are recorded in Appendix 7.3. The occurrences of peat

correspond well with published geological mapping. Recorded peat depths ranged from 0.0m to 2.1m,

where peat was encountered the average depth was between 0.5m and 1.0m depth. Some 123 peat-

free locations were identified, several of which were associated with spoil heaps or located in the

southern regions of the site. Peat depths of 1.75m or greater were recorded at eight locations,

predominantly located in the north of the site, north of Ding Quarry near the summit of Top of Lench

hill.

7.53. NVC mapping identified that the majority of the peat land in the Development Area was vegetated by

degraded/modified mire communities such as M20 and M25. Chapter 8: Ecology suggests that the

peat would have formerly been dominated by blanket mire vegetation. Blanket mire develops in areas

of high rainfall, and has an ombrogenous (that is, water-fed by rainfall) hydrological regime, however

due to the influence of continuous heavy grazing (perhaps coupled with burning and atmospheric

CPL PAGE 7-19


pollution) the original bog vegetation becomes modified to such to lower ecological value habitats.

Much of the peat land across the Development Area, south of Ding quarry, around Ding Clegg and

further east around Hamer Hill is therefore considered to be degraded.

7.54. The findings of the ecology study are supported by peat characteristic analysis; Von Post

humidification scores for the acrotelm were generally H6-H7, indicating moderately to highly

decomposed peat with a very indistinct plant structure. These scores are higher than would be

expected for a healthy, actively peat-forming acrotelm (which should be less decomposed) suggesting

that the acrotelm layer in the study area is degraded. The interpretation that the peaty acrotelm is

degraded across much of the site is reflected in the moisture Von Post scores which were typically B2-

B3, indicating a low to moderate moisture content in the peat. Dip-well levels from piezometers

installed in the peat around turbine locations indicate that average water table depth across the site is

0.25m, below the acrotelm layer. The acrotelm needs to be saturated in order to support the bog

plants which in turn form peat and help stabilise it.

7.55. Two larger areas of M3 bog pool communities were mapped to the north of Ding Quarry (12.36ha) and

on Brandwood Moor (13.3ha). According to the JNCC (2010)4, M3 is typically found in areas of shallow

peat in acidic environments and is commonly associated with eroded blanket mire in north-west f

Britain. It is reported to represent a seral stage in the redevelopment of active mire vegetation

disruption. Water levels in the peat in this area were at ground level, indicating total saturation through

the peat profile. In addition, some small bog pools were observed. In conclusion, these areas of peat

land represent active but not pristine areas bog with a relatively intact hydrological regime.

7.56. A comprehensive multi-factor approach was adopted to identify peatslide prone areas within the

Rooley Moor site. A total of 348 positions on a 100m grid pattern were examined in detail and the

results of the study were used to establish constraints to avoid areas identified as potentially

vulnerable to ground movements. Peat slide risk across the majority of the Development Area was

found to be low, however, some isolated areas of moderate risk were identified. No areas of high peat

slide risk were identified.

Quarrying and Mining

7.57. A separate Mining Risk Assessment Report5 (which is presented in Appendix 7.4) identified that the

Development Area and wider study area has been subjected to extensive mining and quarry activity in

the past. There are currently no active workings. The report found 33 recorded mine entries within the

Development Area; of these, only 6 have been treated or capped. The report also found evidence for

extensive coal mining of seams at numerous locations within the Development Area which have not

been officially recorded.

7.58. OS mapping shows numerous small sandstone quarries within the site boundary with larger quarries

located in the wider study area (such as Ding Quarry or Lee Quarry). Several of the smaller quarries

have been completely backfilled to an unknown standard whilst the rest remain open or partially

backfilled. The mining risk assessment found that the Development Area had an overall Medium to

High risk of mining related subsidence with respect to the Development. As such, all known and

suspected constraints relating to mining activity have been mapped and are shown in Figure 3.1.

7.59. Areas with historical mining activity have in some cases led to a decrease in groundwater quality; as

shown in

4 National Vegetation Classification: field guide to mires and heaths. Joint Nature Conservation Committee (2010). Available online

at http://jncc.defra.gov.uk/pdf/mires_heaths.pdf Last accessed 18/06/14. 5 Mining Risk Assessment Report: Rooley Moor Wind Farm. Prepared by SKM, March 2012.

http://jncc.defra.gov.uk/pdf/mires_heaths.pdf

CPL PAGE 7-20


7.60. Plate 3, below. Groundwater springs contaminated with ferric iron deposits colloquially known as

‘ochre’ are observed emerging within the study area.

Groundwater 7.6.7

Aquifers

7.61. The EA online mapping tool6 indicates that no Source Protection Zone’s (SPZ) are located within the

Development Area or wider study area.

7.62. There are no superficial aquifers located within the Development Area, however, superficial aquifers

are identified along the River Spodden, River Irwell and Nadden Brook watercourses, these likely

comprise recent alluvial deposits.

7.63. EA mapping shows that the bedrock beneath the Development Area is a Secondary A aquifer. This

classification refers to both the NMG series and the PLCM formation. A secondary A aquifer

classification refers to permeable layers of rock capable of supporting water supplies at a local rather

than strategic scale. In some cases these aquifers can form an important source of baseflow to rivers.

7.64. The NMG forms a multi-layered aquifer system in which persistent, thick sandstone horizons act as

separate aquifers with intervening mudstones and shales acting as aquicludes and aquitards7. The

sandstones are generally well cemented and groundwater storage and transport is restricted largely to

joints and fractures.

7.65. A number of perched water tables occur in the multi-layered aquifer system meaning that the depth to

groundwater within the aquifer at any location is difficult to define. Springs are reported to be common

at the base of sandstone layers and at junctions between shale and sandstone horizons7. Numerous

springs and wells are mapped on the hillsides below Rooley Moor (and the main development area)

suggesting that this is an important spring line.

7.66. The PLCM formation is described8 as a moderately productive, multi-layered aquifer. As for the NMG,

it is the sandstone layers which form aquifers and springs are common features.

Groundwater Quality

7.67. The EA online mapping tool 9 indicates that groundwater within the NMG and PLCM has been

assessed under the WFD as having ‘good’ quantitative status. The predicted quantitative status

remains good for 2015. The qualitative status is assessed under the WFD as being ‘poor’, with this

assessment remaining for 2015. Based on observations made during site visits, it is considered likely

this status is related to the mine workings in the area and the impact on groundwater quality.

7.68. The water quality in areas which have been mined is often poor as oxidation of sulphurous mine water leads to the creation of conditions for Acid Mine Drainage (AMD) and the formation of characteristic ochre deposits. This was observed at a spring which emerges at Snipe Barn Farm to the east of the Rooley Moor Development Area (see Error! Reference source not found. below). However, in areas


March 2014 7 Abesser, C, Shand, P. & Ingram, J, 2005. Baseline Report Series 18. The Millstone Grit of Northern England. British Geological

Survey Commissioned Report No. CR/05/015N. 8 BGS UK Hydrogeology Viewer Available online at http://mapapps.bgs.ac.uk/hydrogeologymap/hydromap.html Last accessed 20th

March 2014. 9 Data from Environment Agency, available online at http://maps.environment-agency.gov.uk/wiyby/wiyby Last Accessed 17th June

2014


http://mapapps.bgs.ac.uk/hydrogeologymap/hydromap.html


CPL PAGE 7-21


naffected by mining, water quality is often very good and many springs are utilised locally as potable private water supplies.

Plate 3 Ochre deposits in spring at NGR 387186 416374

Groundwater Dependent Terrestrial Ecosystems 7.6.8

7.69. The Water Framework Directive (WFD) establishes a framework for the protection of groundwater

which prevents further deterioration and protects and enhances the status of groundwater dependent

terrestrial ecosystems and wetlands regardless of whether they are designated or not. Good

groundwater status (both quantitative and chemical) with respect to wetlands and groundwater is

dependent upon there being no ‘significant damage’ to Groundwater Dependent Terrestrial

Ecosystems (GWDTE) caused by alterations to either the flow of groundwater or groundwater

quality. The impact to GWDTE within the Development Area therefore needs to be considered within

this ES.

7.70. There is no specific guidance relating to the identification and assessment of GWDTE habitats on

wind farms in England. As a result, GWDTE habitats on Rooley Moor have been identified using

methodologies outlined in UK Technical Advisory Group (UKTAG, 2009)10 and SEPA’s LUPs11

best

practice guidance for identifying GWDTE and assessing those that are at risk of significant damage.

7.71. The methodology can be summarised as follows; both guidance documents advocate the

identification of GWDTE through National Vegetation Classification (NVC) mapping of the proposed

development area. Detailed NVC mapping of the development area has been undertaken and is fully

10 Guidance on the identification and risk assessment of groundwater dependent terrestrial ecosystems Version 5, Annex 1 (2009)

Available online at http://www.wfduk.org/resources%20/risk-assessment-groundwater-dependent-terrestrial-ecosystems: Last accessed 16th June 2014 11 Land Use Planning System SEPA Guidance Note 4, version 6. Issued March 2012.

http://www.wfduk.org/resources%20/risk-assessment-groundwater-dependent-terrestrial-ecosystems

CPL PAGE 7-22


reported in Chapter 8: Ecology. Once the mapping has been collated, each NVC community is

assigned a groundwater dependency score.

7.72. The UKTAG (2009) guidance gives NVC communities a score between 1 and 3 on a scale of likely

groundwater dependency with the following definitions:

1. High. Strong dependency on groundwater discharge from bedrock or superficial aquifers at the

majority of sites;

2. Moderate. Likely to be some dependency on groundwater discharge at most sites – either direct

from recognised aquifers or indirectly as recharge from minor aquifers in superficial deposits.

Water from other sources (surface runoff, overbank flooding, etc) may also be very important; and

3. Low. Groundwater discharge usually irrelevant. Site fed by other water sources. This may also

include components of ombrogenous systems with intrinsic groundwater systems fed by rain such

as blanket bog. NVC communities with a score of 3 have not been taken forward in this

assessment as they are not considered to be GWDTE.

7.73. Those habitats which have a GWDTE score of 1 or 2 and are located within 250m of borrow pits and

turbines and/or 100m of access tracks and construction compounds are considered to be ‘at risk’ from

the proposed development and therefore require assessment within an ES and may require mitigation

to offset impacts. The sensitivity of these habitats is considered in Table 7.8.

7.74. NVC mapping has identified wetland plant communities such as mires, acidic flushes and bogs within

the development area, these are typically located in the northern half of the site in areas underlain by

varying thicknesses of peat deposits. The majority of the northern portion of the site is covered in M20,

M25 and M3 habitats which are peat forming bog and mire communities and are sustained by

rainwater inputs. By definition, these habitats are not groundwater dependent. In amongst the areas of

bog and mire habitats, small acidic flushes (M6) and rush pasture (M23) plant communities have been

mapped. These communities are considered to have some groundwater dependency and are

identified as GWDTE in Table 7.8.

7.75. Non wetland plant communities such as U4, U5 grassland and U20 bracken dominate in the southern

portion of the site where peat is thin or absent.

Table 7.8 GWDTE habitats within Development Area

NVC

Category

Description UKTAG 2009

GWDTE

Score

M6 –

flush/mire

Sixteen discrete flushes of M6 covering an area of 6.26ha have been mapped

within the Development Area. The M6 mostly forms discrete flushes orientated

parallel to slope contours. All the occurrences of M6 are coincident with peat

deposits suggesting outflow/seepage from this habitat is important in

maintaining saturation. Other inputs will come from direct rainfall recharge,

hillside runoff and shallow groundwater fluxes.

The main exception is a 2.2ha polygon containing M6 and M3, an

ombrogenous bog pool habitat near Prickshaw Slack. It is unlikely this M6

receives significant groundwater inputs and is likely sustained rising and

falling water levels within the peat body.

1 = High

M23 – rush

pasture

Five flushes of M23 covering an area of 2.5ha have been mapped within the

Development Area. These flushes are orientated parallel to slope contours to

the east and west of the existing Rooley Moor track. These habitats have

2 = Moderate

CPL PAGE 7-23


NVC

Category

Description UKTAG 2009

GWDTE

Score

formed in gullies and shallow valleys where surface water runoff flows are

concentrated. Peat depths beneath these habitats are generally low (<50cm)

so groundwater seepage is likely to be an important source sustaining these

habitats.

A 4.9ha area of M23/M25 has also been mapped. M25 is not considered to be

GWDTE at this site and it is noted that both the M23/M25 polygons have

formed over deeper peat which has an ombrogenous regime and are by

definition, not groundwater dependent.

M25 – mire The UKTAG 2009 guidance considers M25 to have a low likelihood of

dependence on ground water movement; though in some circumstances

moderate dependency is possible. The M25 within the Development Area is

typically associated with peat deposits <50cm which have formed as part of

an ombrogenous regime. M25 is widespread across the development area

and is more associated with peat deposits than localised areas (like M6 and

M23) which are more likely to be fed by groundwater seeps and flushes. It is

considered that the M25 in the development area has a low groundwater

dependency.

3 = Low

U6 -

grassland

The UKTAG 2009 guidance considers U6 to have a moderate dependency on

groundwater.

2 = Moderate

M3 – bog

pool

community

UKTAG 2009 considers this wetland habitat to have a low dependency on

groundwater as it forms as part of an ombrogenous bog regime.

3 = Low

M20 – raised

mire

M20 blanket bog is considered to have a low likelihood of dependence on

groundwater movement (UKTAG 2009).

3 = Low

U4 –

grassland

Not a wetland habitat. Located in south of site where peat deposits are

absent.

Not Wetland

habitat so not

classified.

U5 –

grassland

Not a wetland habitat. Located in south of site where peat deposits are

absent.

Not Wetland

habitat so not

classified.

U20 Bracken

community

Not a wetland habitat. Not Wetland

habitat so not

classified.

7.76. Given the local, small scale nature of the possible sensitive GWDTEs, the sensitivity of GWDTEs

within the application boundary is considered to be Medium.

Public Water Supplies and United Utilities Assets 7.6.9

7.77. There are no public water supplies located within the Development Area; however, the site sits

between five reservoir catchments (see Figure 7.1) which are United Utilities (UU) assets supplying

drinking water to Rochdale, Rawtenstall and Bacup. These reservoirs are:

CPL PAGE 7-24


Greenbooth Reservoir,

Naden Reservoirs (#3),

Spring Mill Reservoir,

Prickshaw Reservoirs;

Cowm Reservoir (although understood to currently not be supplying drinking water); and

Cowpe Reservoir and Cragg High Level Tank.

7.78. In addition to the reservoirs, UU have an extensive network of silt traps and settling structures within

the reservoir boundaries. These structures are generally restricted to the north of the site area

between Cowpe Reservoir and Cragg High Level Tank. There is also a culvert structure feeding

Cowm Reservoir from Walstead Clough in the east.

7.79. Consultation with UU indicates that deteriorating raw water quality is a concern for all reservoirs. It is

understood that this is due to increased erosion of peaty soils from the Rooley moor area leading to

soiley runoff into the reservoirs. UU are actively restoring peatland within their reservoir catchments,

including land within or downgradient of the Development Area.

7.80. The sensitivity to public water supplies is considered to be High.

Private Water Supplies (PWS) 7.6.10

7.81. Properties with PWS within the located within 3km of the Development Area were identified through

consultation with Rochdale County Council (RCC) and Rossendale Borough Council (RBC)

undertaken in 2014; the consultation identified 144 properties with registered PWS. Due to the number

of properties identified, a separate PWS study was completed with a view to establishing which

supplies may have a direct hydraulic connection with the Development and which properties could be

scoped out at an early stage. The PWS Assessment is presented as Appendix 7.1 of this chapter.

7.82. The assessment identified the following PWS as being potentially at risk from the Development. These

properties are identified on Figure 7.1.

Table 7.9 PWS at Risk from Proposed Development

PWS ID Property (ies) supplied by

Source

Source

Type

Description

2 Doldrums Farm and Jubarn Well Council has advised this property is supplied by a

well, abstraction volume <10m3/d. No response

received to questionnaire issued April 2014. The

exact nature of the source is unknown but a

conservative assumption would be that the well is

fed by a shallow spring which received some surface

water runoff.

14 Snipe Barn Spring Property is supplied by two sources. Source 1 is

spring which emerges on the hillside above the

property, this spring also receives hillside runoff.

This source is used for livestock and is directed into

Prickshaw Dams.

The second source which provides domestic water

to Snipe Barn has been scoped out in the

CPL PAGE 7-25


assessment due to the groundwater source being

hydraulically remote from any influence of the

proposed development.

15 Broadley Fold and Tobey

Cottage

Spring Spring source taken below Prickshaw Dams.

Supplies Broadley Fold and possibly Tobey

Cottages.

17 Lower Dunisbooth Cottage Spring Property is supplied by a shallow well intercepting a

spring. The well is located 15m upgradient of the

property and the supply is gravity fed into a holding

tank which supplies the house. There is no water

treatment. The source of the spring is unknown. The

owner has stated the water contains a lot of iron and

has ochre (orange) deposits in it.

23 House O’Th Hill Spring Spring See below.

24 Lower Fold Head Farm,

1 Fold Head Cottages,

3 Fold Head Cottages

Fold Head Farm

Spring Spring up gradient of Fold Head Farm, supplies

other local properties. Spring emerges from hillside

above property. The spring flows along an open

channel and receives surface water runoff, including

House O’Th Hill.

7.7 Baseline Sensitivity

7.83. The overall sensitivity of surface water, groundwater and geology are influenced by the sensitivity of

individual receptors. This is summarised below.

Overall Surface Water Sensitivity 7.7.1

7.84. The sensitivity of the surface water environment in the Cowpe Moss, Cowm, Spring Mill and

Prickshaw and Naden and Greenbooth catchments is considered to be High. This is primarily due to

the presence of surface water reservoirs used for public water supply.

7.85. The sensitivity of water receptors in the Greens Moor catchment and the sensitivity of surface water

PWS around the site are considered to be Medium due to the sensitivity of PWS in this catchment.

7.86. Whilst it is recognised differing receptors within the Development Area have different sensitivities, a

conservative approach has been taken and an overall High sensitivity rating will be used in the

assessment for all surface water receptors.

Overall Groundwater Sensitivity 7.7.2

7.87. The overall sensitivity of the groundwater environment to the Development is considered to be

Medium. This is because of the good quantitative status and poor qualitative status of the NMG and

PLCM aquifers. This classification also includes the presence for multiple PWS sourced from

groundwater springs/wells around the site.

Overall Geology Sensitivity 7.7.3

7.88. The overall sensitivity of the geological environment to the Development is considered to be Medium.

In summary, this is primarily due to presence of peat up to 2.1m depth. Much of this peat is degraded

although some active areas have been identified.

CPL PAGE 7-26


7.8 Design Evolution

7.89. The baseline assessment identified a variety of important features related to hydrology, hydrogeology

and geology within the study area that are sensitive to potential adverse impacts from the

Development. As a result it was recognised at an early stage that avoidance of certain areas of the

Development Area would be necessary to avoid significant impacts. Of key importance during the

design stage was;

The maintenance of a 50m buffer around identified watercourses so as to minimise the potential for

pollution of streams and rivers through sediment mobilisation or by spills or leaks of fuel, concrete or

other substances;

The maintenance of a 500m buffer around all public water supply reservoirs so as to minimise the

potential for pollution of streams and rivers through sediment mobilisation or by spills or leaks of fuel,

concrete or other substances;

Maintaining a safe topple distance from all United Utilities infrastructure;

The siting of infrastructure off areas with deeper peat (<50cm) where possible ;

The siting of infrastructure off areas of highly groundwater dependent habitat; and

The early identification of the sources of PWS within the study area also helped avoid these important

and sensitive receptors. PWS sources were identified and tracks have been positioned at least 100m

from the sources and excavations at least 250m away.

7.9 Standard Practice Measures

7.90. Standard practice measures will be implemented during construction across the Development Area,

and for the construction of specific components of the Development. Some of the key best practice

guidelines are referred to in Section 7.3, Policy, Legislation and Guidance. These have been taken

into account when assessing the potential impact and the likelihood of significant environmental

impacts and effects.

7.91. Such site-wide measures will include the following components:

Development of a Detailed Construction Method Statement (CMS) 7.9.1

7.92. Prior to construction commencing, a CMS will be produced outlining specific construction

methodologies to be used for the construction of all components including foundations, tracks,

watercourse crossings, laydown areas and buildings, taking into account the method of excavation

and the location for placing and storing excavated material to ensure that these operations do not give

rise to slope or site instability. A CMS will be provided with the Construction Environmental

Management Plan (CEMP).

Development of a Construction Environmental Management Plan (CEMP) 7.9.2

7.93. Prior to construction commencing, a detailed CEMP will be produced. A draft CEMP has been

prepared as part of this application and is presented as Appendix 4.1. Good working practices and

measures to protect the water environment in accordance with those set out within the EA and

CIRIAs’ PPG notes will be implemented. The Principal Contractor will be responsible for ensuring that

the plan is adhered to during construction. As well as a commitment to and details of best practice,

this will address specific mitigation measures (in addition to standard practice measures). This

CPL PAGE 7-27


document will be presented Rochdale Council, Rossendale Council, the EA and United Utilities for

their approval, prior to construction commencing.

7.94. Specific elements with direct relevance to this chapter that will be included in the CEMP are:

Emergency and Incident Response Plan for any pollution events/spills;

An inventory of pollution sources associated with construction and specific pollution prevention;

Measures to reduce the likelihood of contamination from identified sources to downgradient surface

watercourses from fuels, oils and other contaminants. Control measures described in EA PPG notes

and CIRIA guidance will be formalised within the CEMP;

A waste management plan;

Proposed measures for noise management;

Watercourse crossing plans; and

Details of excavation and reinstatement.

Drainage Management Plan (DMP) 7.9.3

7.95. There is potential for the generation of turbid or coloured runoff from works areas throughout the

Development Area including the construction of turbines, tracks, watercourse crossings, borrow pits,

buildings and other infrastructure to enter surface watercourses and waterbodies particularly via

drainage channels or watercourses that are directly adjacent to or downgradient of works. Therefore a

DMP will be put in place, which will form part of the CEMP. An outline DMP has been prepared and is

presented as Appendix 4.4. This will provide a range of site-wide measures to reduce the generation

of sediment laden or coloured runoff and transport of any runoff to watercourses. Further specific

mitigation measures which are in addition to best practice measures outlined in this section will be

included in this plan.

7.96. The DMP will consist of the following:

A series of plans presenting the site infrastructure, existing natural drainage patterns and man-made

drainage structures;

Geology for assessment of likely permeability and infiltration;

Sensitive receptors including distance to watercourses, PWS;

Topography;

A description of the drainage considerations, sensitive areas of the site, procedures and control

structures to be employed for the various sections of the site;

A layout of the required drainage arrangements, upgradient diversion channels, culvert frequency,

H bars on tracks, check dams, silt fencing and other sediment control structures; and

An appendix of the methodology for the installation of the sediment control structures.

Water Quality Monitoring 7.9.4

7.97. Water quality will be monitored upstream and downstream of key construction works prior to, during

and following construction. Monitoring locations will take account of the construction of watercourse

crossings, access tracks, turbine foundations and borrow pits and will also take place at control sites

(outside the influence of works). A robust baseline of water quality in surface watercourses/drainage

channels downstream of construction works will be established prior to construction commencing. The

CPL PAGE 7-28


purpose of this is to provide a comparison of ‘natural’ conditions against conditions potentially

impacted by construction. Regular monitoring during construction and in the early phases of operation

will be used to ascertain whether there are impacts occurring to watercourses and whether

implemented mitigation measures are being effective. During the early phase of operation, monitoring

will continue to assess the quality of watercourses, comparing against baseline data. The plan will

include specific actions to be taken upon triggering environmental standards.

7.98. An agreement in principal has been reached with UU over the proposed water quality monitoring and

how this monitoring can interface with and mutually enhance and/or be enhanced by proposed and

ongoing water quality monitoring in support of peat restoration schemes sponsored by UU. More

detail about the peatland restoration schemes are contained within Chapter 8: Ecology.

Provision of an Environmental Clerk of Works (ECoW) 7.9.5

7.99. An ECoW will be appointed to undertake/manage the following tasks during construction:

Implementation of peat minimisation protocol (refer to the outline PMP in Error! Reference source

not found.);

Oversee the implementation of the Habitat Management Plan (HMP) (refer to the outline HMP in

Chapter 8: Ecology);

Operate permit to dig and permit to pump systems, etc;

Water quality monitoring;

Emergency response;

Monitor drainage and sediment control; and

Monitor and ensure compliance with best practice guidance.

7.100. In addition to the above key best practice tools, individual infrastructure best practice and standards

are discussed below.

7.10 Predicted Impacts

7.101. When assessing predicted impacts of the Development standard practice measures that will be

incorporated into the construction of the wind farm have been taken into account. In addition the

measures that were taken during the design phase to avoid areas sensitive to potential impacts have

significantly reduced the potential impacts arising from the Development.

7.102. Whilst the incorporation of these measures/design features helped to reduce the magnitude or

likelihood of some potential impacts occurring, it was not possible to avoid all potential impacts. The

potential significant impacts of the Development during construction, operation and decommissioning

prior to specific mitigation measures being applied are summarised in Table 7.12.

Construction 7.10.1

Access Tracks

7.103. The Development incorporates an estimated 6.8km of new tracks. With the exception of watercourse

crossings, new sections of access tracks have been located a minimum distance of 50m from the OS

mapped watercourses on the site. The construction of watercourse crossings will be within this buffer

and the risks associated with these works are addressed in the Watercourse Crossings (Section 0)

section below. New tracks are proposed to be constructed within the following catchments:

CPL PAGE 7-29


Spring Mill and Prickshaw;

Naden and Greenbooth;

Cowm; and

Greens Moor;

7.104. There are no new tracks proposed in the Cowpe Moss catchment.

7.105. Construction of access tracks and their continued use during the construction phase may potentially

generate turbid runoff, which could follow topographic grades to surface watercourses and associated

receptors. Any potential impacts to surface watercourses are expected to be localised and short term

only. Pollution prevention and sediment and drainage control measures described in EA PPG notes

and CIRIA guidance will be formalised within the CEMP; a draft CEMP is presented as Appendix

4.1.The contractors will be required to comply with this document. The document will specifically

outline how surface water runoff will be managed during construction. Design of drainage will seek to

mimic existing local surface water runoff regimes, such that there will be no change in quantity of

runoff into downstream receiving watercourses.

7.106. The routes of access tracks are confined to the top of sub-catchment areas, crossing watershed areas

of the sub-catchments identified above. Construction of access tracks and their continued use during

the construction phase may potentially generate turbid runoff, which could follow topographic grades

to surface watercourses, waterbodies and associated receptors, resulting in a temporary decrease in

water quality. Any potential effects to surface watercourses are expected to be localised and short

term only. Design of drainage as outlined in Appendix 4.4 will seek to mimic existing local surface

water runoff regimes, such that there will be no change in quantity of runoff into downstream receiving

watercourses.

7.107. The access tracks are located well over 100m from all PWS, however, there may be some impacts to

water quality at PWS. The source of the impacts will be restricted to the upgraded section of the

existing track as no new tracks are proposed directly upgradient of PWS supplies.

7.108. Overall, the peat slide risk across the site is generally low, however, localised medium risk areas of

peat instability have been identified (see Figure 12 of Appendix 7.3) and adequate control measures

will need to be incorporated during construction works to protect any vulnerable watercourses. A peat

slide caused as the result of access track construction could result in the release of peat sediments

into down gradient watercourses. Tracks will be either of ‘excavated’ type tracks, (estimated 5.0km)

constructed on areas with less than 1.0m depth or ‘floating’ type tracks (estimated 1.8km) constructed

on areas of peat greater than 1.0m depth. This track design minimises the volume of peat excavated

during construction, minimises the mobilisation of peat fines from excavation areas and preserves

unimpeded subsurface flow.

7.109. The track layout has been designed to avoid areas of active peat, however total avoidance has not

been possible. The new access track is proposed in areas of active bog to provide access to turbines

T18, T16, T15 and T14. The track could disrupt hydraulic continuity within the bog habitat, resulting in

indirect loss down gradient of the track. These indirect losses of habitat could occur if hydraulic

continuity is not maintained down gradient of the access track.

7.110. The access track layout has avoided all areas of highly groundwater dependent habitats (M6).

Upgraded sections of access track along Rooley Moor road to cross areas of M23, moderately

dependent GWDTE. The presence of tracks can disrupt shallow groundwater flows, impounding water

on the upgradient side of track, resulting in indirect habitat loss up to 100m from tracks. However, as

this M23 is already located on either side of the track, this suggests its presence is unaffected or even

enhanced by the presence of the track. One area of new track, near water crossing no.4 (see Section

CPL PAGE 7-30


0) will bisect a flush of M23 which leads onto a flush of M6. Mitigation will be required to ensure

hydraulic continuity is maintained at this point and maintain GWDTE habitats down gradient.

7.111. Furthermore, indirect loss of the above mentioned habitats could occur as a result of the access track

construction. Impacts relating to direct loss of ecological habitat are covered in Chapter 8: Ecology.

Watercourse Crossings

7.112. There are a total of two new and one upgraded watercourse crossing proposed to be constructed over

surface watercourses and drainage channels within the Development Area, shown on Figure 7.1 and

described in Table 7.10. These crossings are proposed in the following catchments:

Table 7.10 Proposed and Upgraded Water Crossings

Crossing

ID

Type Location

(NGR)

Catchment Description

1 Upgraded 386948

416085

Spring Mill and

Prickshaw

Upgraded watercrossing beneath existing Rooley

Moor Road. No direct discharge to reservoir.

2 New 385631

418048

Naden and

Greenbooth

New crossing over stream which discharges

directly into the Naden and Greenbooth Reservoir.

3 New 385665

418086

Naden and

Greenbooth

New crossing over stream which discharges

directly into the Naden and Greenbooth Reservoir.

Upgradient of crossing 2.

7.113. During the construction of all watercourse crossing culverts, potential impacts include:

Constriction of fluvial flow resulting in increased flood risk;

Disturbance to stream banks and/or substrate which could lead to increased erosion and local

changes to fluvial geomorphology, direct loss or damage to aquatic habitats or species or a local

increase in suspended sediment concentrations causing a temporary decrease in local water quality;

Disturbance to stream banks and shallow groundwater flows, resulting in indirect loss or degradation

to adjacent/down gradient GWDTE habitats;

Sediment contamination of the watercourse from plant movement near the works; and

Spillages or leaks of other contaminants such as fuels or oils which could enter the watercourse.

Wind Turbine Foundations and Crane Hardstandings

7.114. The Development includes the construction of 12 wind turbines and associated crane hardstandings.

Turbines are proposed to be constructed in the following surface water catchments:

Naden and Greenbooth catchment (9);

Watershed of Naden and Greenbooth and Spring Mill and Prickshaw catchment (1); and

Greens Moor catchment (2).

7.115. To reduce the potential for turbid runoff or other contaminants such as fuels or oils (used in

construction) from entering surface watercourses, wind turbines and associated crane hardstandings

have all been located a minimum distance of 50m away from all OS mapped watercourses. The wind

turbines will be supported on concrete foundations, measuring up to 3m in depth and up 20m width,

(see Figure 4.3). Construction of the turbine foundations will involve the excavation of peat and

CPL PAGE 7-31


subsoil, which will either be bunded and stored prior to the in-situ casting of a steel-reinforced

concrete slab. Surplus peat will be used for habitat restoration (see the outline PMP in Appendix 7.2),

and to batter the edges of tracks and platforms, or landscaping local to each turbine. Excavation areas

will have sides that are 'battered' back to ensure that they remain stable during construction. Each

foundation is expected to require approximately 390m3 of concrete and 55 tonnes of steel reinforcing.

Hardstanding areas will be constructed adjacent to each turbine, orientated to make best use of

topography and prevailing wind conditions, with an area of approximately 25m by 40m (33m by 40m, if

turbine is located at the end of an internal track).

7.116. There is potential for concrete spillages during turbine foundation construction, which could migrate

into groundwater or to down gradient surface water features. Concrete is highly alkaline and corrosive

and any spillage can adversely affect water quality. Concrete is only mobile for a short period of time

before it sets and therefore the potential for migration of concrete into groundwater would only occur

for a short duration until it begins to set.

7.117. The areas of unconfined bedrock aquifers may be at risk of contamination from concrete in the event

of a spillage. The potential risk will be confirmed by an intrusive ground investigation prior to works

commencing. Controls will be required to prevent mobilisation of any concrete spills overland to

surface water features and into groundwater.

7.118. It is recognised that not all turbines are situated on topographical high points and some turbine

locations will be subject to ephemeral surface runoff pathways which will convey runoff during rainfall

events during construction. A draft Drainage Management Plan (DMP) is presented as Appendix 4.4

and a final DMP will be presented post consent, prior to any construction activity. This document will

describe how to manage flows across the Development Area during construction and this will include

management of flows at each turbine location, during and post construction. This plan will take into

account the potential for flows from up gradient areas as well as managing runoff from the turbine

location. Design of drainage will seek to mimic existing local surface water runoff regimes, such that

there will be no change in quantity of runoff into downstream receiving watercourses.

7.119. When excavating for construction of the turbine foundations, it is possible that groundwater will be

encountered. Excavations may need to be dewatered to lower groundwater levels and ensure that wet

working and direct contact of cement material with groundwater does not occur. This will mean that

there is potential for loss of recharge and interruption of existing groundwater regimes in the

immediate locality.

7.120. The impact on any PWS is not expected to be significant as the placement of turbines has avoided

PWS sub-catchment areas.

7.121. The PSRA (Appendix 7.3) identifies areas of moderate peat slide risk located close to Clegg ding,

Red Pits and the Top of Leach; these have been largely avoided where practical. Turbines T4 and T8

are located in areas of moderate peat slide risk and turbine T10 is located on the up gradient

periphery of an area of moderate risk. A peat slide in this location has the potential to cause a release

of peat sediments into the Naden and Greenbrook catchment resulting in a significant reduction in

surface water quality. Additional mitigation will be required to reduce the risk of peat slide in this area.

7.122. The majority of turbines have been located off areas of deeper peat and active bog. The placement of

turbines T18, T16, T15 and T14 are in areas of M3 bog pool community which is considered to be

active. The placement of the turbines will result in direct loss of habitat (considered in Chapter 8:

Ecology). During the construction phase, turbine foundation excavations will locally dewater the peat

body and physically deteriorate the peatland structure leading to erosion and runoff pf peat mater into

downstream water bodies. The continued presence of turbines during the operational phase will also

result in disruption to hydraulic continuity in the peat body. Mitigation will be required to ensure

CPL PAGE 7-32


disruption to this habitat is minimised and secondary impacts, such as peat drying and erosion are

effectively managed.

7.123. The placement of turbines has avoided all moderate and highly groundwater dependent habitats and

therefore there will be no impact to these receptors.

Electric Cables

7.124. Electric cables for the Development will be installed within small trenches (approximately 1.8m wide

and 0.5m deep) that will run alongside the access tracks. The majority of the cable route will be

located on bedrock, with some shorter sections crossing areas of peat.

7.125. There is potential for cable trenches to transport turbid water from works areas to drainage channels

and surface watercourses down gradient.

Substation Compound and Control Building

7.126. The proposed location of the control building and substation compound is shown on Figure 4.9. The

building will be situated within a 35m x 25m compound, incorporating car parking and storage yard.

The control building and substation compound will be located in the south of the site and built directly

onto the PLCM bedrock, there is no peat in this area. As a result, there will be no significant impact on

peat.

7.127. Both the substation and control buildings are located over 50m up gradient of the nearest watercourse

which flows towards the east through the Snipe Barn Farm PWS sub-catchment. During the

construction phase, excavation of bedrock and soils stripping may generate sediment laden runoff.

Furthermore, any spillages of concrete or other contaminants such as fuel or oils may impact upon

groundwater quality.

7.128. It is unlikely that the excavation of foundations would result in any significant dewatering as foundation

depths are estimated to be up to a maximum of 1.0m below ground level.

Temporary Construction Compound

7.129. An indicative layout for the construction and laydown compound is shown in Figure 4.10. The

compound will have dimensions of approximately 85m x 65m. The area will be prepared by carefully

stripping soil and peat in accordance with best practice guidance, laying down geotextile material and

then a working surface of stone. The stripped material will be stored adjacent to the site for

subsequent use in reinstatement and screening.

Borrow Pits

7.130. Borrow pits will be constructed to provide stone for the wind farm infrastructure. No stone will be

bought onto site. The proposed borrow pit locations have been selected because of their morphology,

accessibility from existing or new access tracks, orientation and the expected proximity of rock to the

surface. It is proposed to construct two borrow pits, details are listed in Table 7.12 below.

Table 7.11 Borrow Pit Details

Borrow Pit ID Location Surface Area Max Depth Volume Extracted

Borrow Pit 1 386458, 416930 250m x 68m 3.5m 40,000m3

Borrow Pit 2 386104, 417915 137m x 105m 7m 60,000m3

CPL PAGE 7-33


7.131. Without appropriate mitigation measures the construction of borrow pits results in the following

potential to impacts to water resources by:

Excavating and disruption of peat resources;

Disruption of groundwater storage and flow through excavation below the water table;

Generation of suspended solids to surface water;

The disruption to established drainage patterns through extraction/stockpiling activities; and

Surging of surface run off which has collected in excavated borrow pit areas.

7.132. Upon completion, the borrow pits will be partially reinstated. This will involve the reworking of faces to

stabilise them, partial infilling with surplus material and landscaping with peat (where there was

originally peat habitat) and soils excavated during the wind farm construction. There may also be the

potential for environmental enhancement by creating small wetlands or other desirable habitats.

Operation 7.10.2

7.133. This section provides a summary of potential impacts prior to mitigation measures being implemented,

but on the basis that good site practices will be employed. It is based on an assessment of activities

that will occur during the operational phase of the Development which are presented below.

7.134. The potential impacts (and the likelihood of them occurring) to identified sensitive receptors during the

operational phase are summarised in Table 7.12, along with an assessment of their significance.

Access tracks and Watercourse Crossings

7.135. The tracks are designed to last for the life of the Development and only limited maintenance is

envisaged during operation. The tracks will be constructed from compressed aggregate, which could

be eroded by surface water over time. There will be low volumes of traffic throughout the operational

phase (see Chapter 12 Access, Traffic and Transport).

7.136. Potential effects during operation of the Development from the presence of access tracks and

watercourse crossings include:

Increased sediment loading in surface watercourses from runoff from tracks caused by traffic

movement or the erosion of tracks;

The potential for spills and leakages of potentially polluting substances such as fuels and oils from

plant and vehicles which could migrate to surface watercourses or groundwater;

Increased flood risk due from watercourse crossings and tracks; and

Change in local groundwater flow regimes with may reduce recharge to sensitive areas located down

gradient of tracks.

7.137. The likelihood of spillages or leaks of fuels or oils will be much reduced during the operational phase,

compared with during construction. Sources will be limited to fuel from vehicles visiting the

Development Area, lubricants and oils used in the turbines substation and transformers and foul

drainage produced by the limited numbers of staff visiting the application site. To further reduce the

likelihood of spills occurring and to reduce any impacts if spills do occur, similar best practice

measures that were applied during construction will be implemented.

7.138. All tracks and watercourse crossings are outside floodplain areas, however their presence has the

potential to increase flood risk during the operational phase. The presence of tracks will slightly

decrease the overall permeability of the Development Area, resulting in slight increases in runoff rates

CPL PAGE 7-34


during rainfall events. However, even when combined with other hardstanding areas within the

Development Area, the increase in hardstanding area represents negligible proportion of the total area

of the surface water catchments within and downstream of the application site. Therefore, the

presence of tracks is unlikely to result in a measurable increase in surface water runoff rates from the

Development Area.

7.139. Watercourse crossings have the potential to constrict the watercourses resulting in flows backing up

and increasing the risk of flooding upstream. The design of watercourse crossing culverts will reduce

the likelihood of channels becoming constricted or crossings becoming blocked, with the actual design

of crossings to be agreed at the detailed design stage.

Control Building, Substation and Hardstanding Areas

7.140. Potential impacts from the control building, substation building and hardstanding areas during

operation are not considered to be high or likely. The buildings will be visited infrequently during

operation of the wind farm and are located outside of a floodplain area. The small quantity of sewage

arising from visits of maintenance staff will be stored in septic tanks and removed periodically by a

licensed contractor.

7.141. Rainwater collection systems would be installed to provide water for flushing which, if necessary,

would be topped up with water brought to site in containers. Excess rainwater falling on the roof of the

buildings will be discharged to an infiltration drain or other SUDS based drainage system around the

compounds. The buildings will not be of a size to intercept significant quantities of water and no

impact is expected to groundwater/surface water at the application site.

7.142. No impacts are anticipated as a result of the presence of this infrastructure.

Wind Turbines, Foundations and Crane Hardstandings

7.143. The physical presence of turbine foundations may locally change groundwater flow regimes. Runoff

over turbine bases will be directed back to undisturbed ground using toe drains where necessary, and

there will be a negligible loss of recharge. Cut-off drains will also be used to direct runoff to ground.

These measures will be designed not to act as preferential migration pathways.

7.144. The impact on any PWS is not expected to be significant as the placement of turbines has avoided

PWS sub-catchment areas.

7.145. In addition there is the potential to decrease the water quality of down gradient surface watercourses

due to spills or leaks from oil or other potentially polluting substances. However, the likelihood of this

occurring is low and volumes of any spills are not expected to be substantial. To reduce the likelihood

of spills or leaks from turbines, each turbine will be designed with fluid catch basins and containment

systems to prevent accidental releases from leaving the nacelle. Any accidental gear oil or other fluid

leaks from the wind turbines would be contained inside the towers as they are sealed around the

base, with the entrance situated above ground level.

7.146. The design of the foundations will ensure that there are no water quality impacts to downstream

surface watercourses or groundwater from the use of concrete. Foundations will be constructed using

sulphate resistant concrete, which will ensure no degradation or subsequent pollution when in contact

with acidic water during the lifetime of the Development.

7.147. The reinstatement of the turbine foundation area (comprising back filling the foundation area over the

subsurface foundations with excavated soil and re-vegetating to allow for the natural infiltration of

surface water) will assist in the reinstatement of groundwater recharge mechanisms and will ensure

no significant change to overall groundwater regimes.

CPL PAGE 7-35


Borrow Pits

7.148. Borrow pits will have been decommissioned and partially reinstated in the construction phase so no

impact is expected during this phase.

Decommissioning 7.10.3

7.149. The Development will have a planned operational life of up to 25 years. At the end of this period,

unless permission for continued operation as a wind farm is granted, it will be decommissioned. The

ultimate decommissioning methods will be agreed with Rochdale Metropolitan and Rossendale

Borough Councils and other appropriate regulatory authorities (e.g. DEFRA, Natural England). The

site will be reinstated post decommissioning through a programme of habitat restoration, in

accordance with an agreed decommissioning plan.

7.150. It can be anticipated the decommissioning process will comprise:

Wind turbines: To be dismantled, removed from the site and disposed of appropriately;

Foundations: The majority will be left in-situ. The top metre of the base will be removed and disposed

of appropriately. The area re-surfaced with topsoil or peat and restored appropriately;

Underground cabling: These will be left in-situ or removed for recycling;

Access tracks and hardstandings: These will be left in-situ to be used by the landowner;

Water Crossings: these will be left in suit as they are integrated into access tracks;

Anemometry masts: These will be dismantled, removed from the site and disposed of appropriately.

The foundations will remain in-situ. The top metre of the base will be removed, disposed of

appropriately, then covered with top soil or peat and restored;

Site access: All access tracks will be left in-situ; and

Wind farm control building, substation and compound: The equipment will be removed and disposed

of appropriately. The building will be demolished and the material removed from the site. The top 1m

of the foundations will be removed then covered over with topsoil or peat and restored appropriately.

7.151. Potential impacts during the decommissioning phase will reflect the impacts predicted for construction,

however substantially less activity is anticipated during this period. There will be some limited

earthworks associated with the removal of turbines, buildings and the anemometry masts. The

removal of site infrastructure has the potential to cause a temporary decline in water quality from the

generation of turbid runoff migrating to down gradient surface watercourses and associated receptors,

and it is assessed that the likely potential impact would be moderate.

7.152. There is also potential for minor impacts associated with a temporary decrease in water quality from

spills or leakage of fuels, oils or other potentially polluting substances from vehicular and plant

movement on site, the storage and use of chemicals and the maintenance of plant. To reduce the

likelihood of spills occurring and to reduce any impacts if spills do occur, similar best practice

measures that were applied during construction will be implemented.

7.11 Summary of Potential Impacts and Mitigation Measures

7.153. Potential impacts prior to mitigation during construction, operation and decommissioning are

summarised in Table 7.12 Summary of Predicted Impacts. An indication of whether additional

mitigation is required or not is also included.

CPL PAGE 7-36

Rooley Moor Wind Farm EIA

Table 7.12 Summary of Predicted Impacts

Activity Potential impact Receptor Sensitivity

of receptor

Magnitude of

potential

impact

Evaluation

of potential

impact

Likelihood

of

occurrence

Likely

potential

impact

Mitigation

required?

CONSTRUCTION

Construction

of site

infrastructure

A temporary decrease in

water quality from the

generation of turbid or

discoloured runoff

migrating to down

gradient surface

watercourses and

associated receptors

Surface water

(all surface

water

catchments)

High Moderate Moderate Possible Moderate

Construction

of

watercourse

crossings

Disturbance to stream

banks causing changes in

erosion rates and local

morphology

Surface water

(Springmill &

Prickshaw,

Naden &

Greenbooth

catchments

only)

High Medium Moderate Likely Moderate

Blockage or constriction of

watercourses causing an

increase in flood risk

Surface water

(Springmill &

Prickshaw,

Naden &

Greenbooth

catchments

only)

High Medium Moderate Possible Moderate

Construction

of

hardstanding

areas such as

Increase in runoff rates

causing an increase in

flood risk

Surface water

(all surface

water

High Low Minor Possible Minor

CPL PAGE 7-37



of receptor

Magnitude of

potential

impact

Evaluation

of potential

impact

Likelihood

of

occurrence

Likely

potential

impact

Mitigation

required?

tracks,

compounds,

turbine

foundations

and buildings.

catchments)

Vehicular and

plant

movement

onsite;

storage and

use of oils and

chemicals;

maintenance

of plant


water quality from spills or

leakage of fuels, oils or

other potentially polluting

substances

Surface water

(all surface

water

catchments)

High High Major Possible Moderate

Groundwater Medium Medium Moderate Likely Moderate

Construction

of the access

tracks and

turbine

foundations

Disruption of PWS

supplies

Groundwater

and Surface

water

Medium Medium Moderate Rarely Negligible

Disruption to peat

hydrology and consequent

degradation of peat

Geology Medium Medium Moderate Likely Moderate

Decrease in water quality

of watercourses located

down gradient of a peat

slide occurrence.

Surface water

(all surface

water

catchments)

High Medium Major Rarely Minor

Dewatering of

groundwater

in the

construction



generation of turbid runoff

migrating to down

Surface Water

(Springmill and

Prickshaw

only)

High Medium Major Possible Moderate

CPL PAGE 7-38



of receptor

Magnitude of

potential

impact

Evaluation

of potential

impact

Likelihood

of

occurrence

Likely

potential

impact

Mitigation

required?

of foundations

and borrow

pits

gradient surface water

receptors including PWS

Loss of groundwater

recharge and change of

local groundwater regimes

potentially causing indirect

loss of PWS

Groundwater Medium Medium Moderate Likely Moderate

Disruption to peat

hydrology and draining of

peat

Geology Medium High Moderate Likely Moderate

Excavation of

peat during

the

construction

of site

infrastructure

Disturbance and

degradation of peat Geology Medium Medium Moderate Likely Moderate

OPERATION

Vehicular use

of tracks and

watercourse

crossings /

other site

activities




migrating to down

gradient surface

watercourses and


Surface water

(all surface

water

catchments)

High Medium Major Rarely Minor




Surface water

(all surface

water

High Medium Moderate Possible Minor

CPL PAGE 7-39



of receptor

Magnitude of

potential

impact

Evaluation

of potential

impact

Likelihood

of

occurrence

Likely

potential

impact

Mitigation

required?


substances

catchments)

Groundwater Medium Low Low Rarely Negligible

Presence of

watercourse

crossings

Blockage or constriction of

watercourses causing an

increase in flood risk

Surface water High Low Moderate Rarely Minor

Presence of

turbine

foundations

Changes to local

groundwater flow regimes

resulting in drying out of

peat resources down

gradient

Geology Medium Low Minor Likely Minor

Changes to surface water

runoff patterns and rates

which could increase flood

risk

Surface water High Low Moderate Rarely Minor

Use of control

building and

substation





substances such as

sewage

Surface water High Medium Moderate Rarely Minor

Groundwater Medium Medium Low Rarely Negligible

Reinstatement

of Borrow pits

Reinstatement of borrow

pits with peat to create

new bog wetland areas

Geology Medium Medium Moderate Likely Moderate (positive

effect)

DECOMMISSIONING

Removal of

site




Surface water High Medium Major Possible Moderate

CPL PAGE 7-40



of receptor

Magnitude of

potential

impact

Evaluation

of potential

impact

Likelihood

of

occurrence

Likely

potential

impact

Mitigation

required?

infrastructure migrating to down

gradient surface

watercourses and


Vehicular and

plant

movement

onsite;

storage and

use of oils and

chemicals;

maintenance

of plant





substances

Surface water High Medium Major Possible Moderate

Groundwater Medium Medium Low Rarely Minor

CPL PAGE 7-41


7.12 Mitigation Measures

Access Tracks 7.12.1

7.154. Tracks will be either of ‘excavated’ type tracks (estimated 5.0km proposed), constructed on areas

with less than 1.0m depth of peat, or ‘floating’ type tracks (estimated 1.8km proposed) constructed

on areas of peat greater than 1.0m depth. This design of tracks is proposed in order to minimise

the volume of peat excavated during construction, minimise the mobilisation of peat fines from

excavation areas and preserve unimpeded groundwater flow.

7.155. Construction of access tracks and their continued use during the construction phase may

potentially generate turbid runoff, which could follow topographic grades to surface watercourses

and associated receptors. Any potential impacts to surface watercourses are expected to be

localised and short term only. Pollution prevention and sediment and drainage control measures

described in EA PPG notes and CIRIA guidance will be formalised within the CEMP. The

contractors will be required to comply with this document. The document will specifically outline

how surface water runoff will be managed during construction.

7.156. Trackside drains will be provided to control runoff from construction areas especially during heavy

rainfall events. Trackside drainage will comprise either buffer strips or infiltration trenches which will

be unlined to allow the standing water to infiltrate back into the ground. Tracks will have a camber

to encourage runoff adjacent to trackside drains. The drains will have the potentially to convey

entrained sediments within runoff and will discharge into a swale or buffer area of adequate

capacity to prevent discharge directly into any surface watercourse. There will be no direct

discharge of construction drainage to any existing watercourse.

7.157. To mitigate any potential reduction to groundwater recharge from track construction and to allow

the passage of any sub-surface flows, constructed tracks will comprise a semi-permeable surface

to allow some infiltration.

7.158. To limit potential pollution impacts from either hardcore and/or excavated material entering

watercourses, or increased sediment levels within surface water runoff, the principle contractor will

be required to adhere to measures and controls set out in the CEMP and PMP during construction.

These measures will include, but not be limited to:

Any excavated soil/peat that will be used in the construction of access tracks (e.g. to dress the

sides of the tracks once backfilled) are to be temporarily placed on the furthest side away from any

identified watercourse or drain;

The provision of buffer strips around watercourses or drainage channels on sections of track

adjacent to watercourse crossings;

Procedures during excavations and soil handling for both routine working and during any

environmental emergencies to control and mitigate both erosion and dust generation; and

Trackside ditches will be unlined to allow water to soak back into the ground resulting in no

significant loss to groundwater recharge.

7.159. The degree of disturbance and degradation of peat resources has been minimised in the design of

the track. This has minimised the direct loss of peat resources. Further details regarding the

excavation, storages and reinstatement procedures are presented in the outline PMP (Error!

Reference source not found.). The majority of the site’s access tracks will be constructed using a

cut and fill methodology. Excavated peat from cut and fill sections of access tracks will be used for

dressing the side slopes of track sections and potentially for landscape screening bunds. Peat

turves will also be replaced on constructed roadside drainage channel embankments where

possible. Only peat turf and fibrous peat is likely to be suitable for battering road verges. When

constructing tracks rapid restoration will be undertaken as track construction progresses.

Immediately following construction some turves will be replaced along the road edges to allow

quicker re-vegetation and soften the road edges

CPL PAGE 7-42


7.160. The design and construction of tracks on peat will be done in such a way so as to reduce impacts

on and maintain the existing peat hydrology at the site. The built track will allow for the

transmittance of water, so natural drainage can be maintained as much as possible.

7.161. Floating tracks avoid the need to excavate the peat and re-fill with imported rock. However, the

weight of the track structure can cause compression of the underlying acrotelm resulting in reduced

transmittance of water, resulting in pond of water upgradient of tracks and derogation of water

supply down gradient of tracks. Drainage through the floating track will be maintained using drains

constructed at regular points through the peat.

Watercourse Crossings 7.12.2

7.162. All watercourse crossings on site are considered to be minor crossings (i.e. narrow watercourse,

relatively flat gradients, low velocity flows), all of which will be crossed via culverts. It is proposed

these crossings will be formed from plastic or pre-cast concrete culverts, with the size based on the

calculation of peak flow from the upstream catchment to enable a 0.5% AEP flow (including an

allowance for climate change on future rainfall intensities) to be passed through the culvert. The

actual design of each culvert will be agreed at the detailed design stage, with all culverts designed

and constructed in accordance with EA and CIRIA good practice guidance and the designs agreed

with EA prior to construction. The design of each crossing will take into consideration overland flow

routing in the event of a blockage and to enable flow to be directed back into the watercourse

downstream of any obstruction.

7.163. It is proposed culverts will be embedded so that the base is at grade with the streambed or lower to

maintain bed form processes and minimise disruption to wildlife migration. The need for ledges to

enable the movement of mammals through the pipe will be assessed at the design stage and

incorporated as necessary.

7.164. Disruption to channel banks during the construction of crossings will be minimised by the use of

cofferdams and over-pumping if the channel exhibits potential for high flows during the construction

period. Pollution prevention measures as outlined in the CEMP will be implemented to reduce the

likelihood of sediment or other contaminants entering adjacent watercourses

Wind Turbine Foundations and Hardstandings 7.12.3

7.165. To reduce the potential for turbid runoff or other contaminants such as fuels or oils (used in

construction) from entering surface watercourses, wind turbines and associated crane

hardstandings have all been located a minimum distance of 50m away from all OS mapped

watercourses.

7.166. It is recognised however not all turbines are situated on topographical high points and some turbine

locations will be subject to ephemeral surface runoff pathways which will convey rainfall runoff

during rainfall events. A site drainage plan will be specified within the CEMP to manage flows

across the site and this will include management of flows at each turbine location, during and post

construction. This plan will take into account the potential for flows from up gradient areas as well

as managing runoff from the turbine location.

7.167. When excavating for construction of the turbine foundations, it is possible that groundwater will be

encountered. If this occurs, excavations will be dewatered to lower groundwater levels and ensure

that wet working and direct contact of cement material with the groundwater does not occur. This

will mean that there is potential for loss of recharge and interruption of existing groundwater

regimes in the immediate locality, potentially affecting sensitive peat habitats. Any water will be

pumped out and passed to a settling lagoon to allow suspended sediment to settle. Treated water

will be discharged to an area of vegetated ground designated for drainage allowing seepage into

the ground. There will be no direct discharge of pumped groundwater to adjacent watercourses or

drainage channels. Further details on this will be included within the CEMP and will be agreed with

the EA prior to construction commencing.

CPL PAGE 7-43


7.168. Excavations will remain open for the shortest time practical to limit the effect of any dewatering.

There will be no discernible overall loss of recharge to groundwater; however some areas will

experience minor localised change to flow regimes through excavations and the introduction of

turbine foundations. Recharge from drainage channels will compensate for localised reduction in

infiltration as a result of the presence of the foundations acting as a barrier to groundwater flow.

7.169. There is potential for concrete spillages during turbine foundation construction, which could migrate

into groundwater or surface water. Concrete is highly alkaline and corrosive and any spillage can

have adversely affect water quality. To minimise the likelihood of spillages, concrete will be brought

to site ready mixed and the wagons will enter and leave the site through a designated site

entrance, and all vehicle washouts will take place off-site. Temporary bunds will be placed

downslope of pouring operations to contain any spillages. In the event of a spillage, an incident and

emergency response plan will be initiated. This will be detailed in the CEMP.

7.170. It is understood that migration of concrete in groundwater can occur in highly fractured and fast

flowing groundwater environments (Environment Agency, 2001). Prior to pouring concrete within

turbine excavations, the degree of weathering or fracturing of bedrock will be assessed. If the

bedrock is highly fractured, it may be necessary to form a barrier within the excavation to ensure

liquid concrete does not come into contact with underlying groundwater. Either a geotextile liner or

a sand layer would restrict the flow of concrete into the surrounding groundwater. This will be

determined by an intrusive ground investigation prior to works commencing. It should be noted that

once concrete is poured it is only mobile for a short period of time before it sets and therefore the

potential for migration of concrete in such groundwater conditions would only occur for a short

duration until it begins to set.

7.171. Measures of the disturbance and degradation of peat resources during and after the construction of

turbine foundations and hardstanding areas are detailed in the outline PMP (Error! Reference

source not found.). It is envisaged that the majority of the excavated peat materials from turbine

foundation excavations will be reused for the purpose of borrow pit restoration, which will be

restored to create bog habitats. Some peat will be replaced around the turbine base excavations,

and re-turfed. Peat will also be spread over the areas disturbed by turbine construction activities,

around the crane hardstandings, rotor assembly hardstandings and other areas used in the

construction phase. Where appropriate, excess peat turves may be used for screening bunds,

landscaping or as material for use as part of the HMP, in conjunction with reseeding.

Substation Compound and Temporary Construction Compound 7.12.4

7.172. During construction of the substation and temporary construction compounds, a surface layer of

vegetation and topsoil will be removed and a shallow foundation will be dug. The cleared area will

be filled with aggregate and then a temporary surface (e.g. geotextile) placed on top. During

construction, oil, fuel and other substances will be stored in a storage area within the compound.

The area will also be used as a base for refuelling of equipment.

7.173. Indicative floodplain mapping provided by EA shows that all infrastructure are completely within

areas of low risk of fluvial inundation. However, there may be localised surface water flows

(particularly during rainfall events) that may need to be diverted around this area. This will be

particularly important because oil, fuel and other substances will be stored within the building

temporary construction compound. Drainage management including the control of runoff in this

area will be included in the CEMP. Surface water flows in the area will be further managed by the

use of crushed and compacted granular stone in the foundations. This will allow water to infiltrate

the foundations, thereby reducing peak surface water flows from the area.

Electric Cabling 7.12.5

7.174. There is potential for cable trenches to transport turbid water from works areas to drainage

channels and surface watercourses down gradient. To prevent this, where possible, trenches will

be dug during dry weather. This will reduce the likelihood of any excavated material being

CPL PAGE 7-44


mobilised in the trenches. Sand will be placed in the trenches, with the cables placed over the top.

To prevent water tracking along trenches, clay plugs or appropriate plugging material will be used

in short (typically 1m) sections, with the distance between plugs dependent on the track slope.

7.175. Excavated material will then be replaced as quickly as possible to reduce the period of time that

trenches are open. While the trenches are open, impermeable barriers (made of clay or other

impermeable material) will be placed at intervals along the open length of the trench. This will

reduce the likelihood of trenches becoming preferential flow paths and their capacity to transport

turbid runoff to downstream

Borrow Pits 7.12.6

7.176. A system of drainage ditches or temporary interception bunds will be constructed to intercept any

surface run off from entering the borrow pit areas. Intercepted surface water runoff will be diverted

away to open ground and allowed to discharge. No intercepted/dewatered water will be allowed to

discharge directly to surface watercourses.

7.177. Consideration will be given to the stability of surface soils where collected surface

water/groundwater is diverted and water collected within borrow pit areas would be treated in the

same way. Furthermore, consideration will be given to ensure that water is not discharged to

ground directly up gradient or within the sub-catchment of sensitive PWS.

7.178. Where necessary, surface water and groundwater will be passed through temporary settlement or

silt traps before being discharged to ground (e.g. silt busters or settlement tanks). All interception

bunds and drainage ditches will be fully reinstated once extraction from the borrow pits is

completed. Water entering the borrow pits will need to be removed by either gravity drainage

design or pumping depending on the overall morphology of the pit. The general topography in the

areas identified is conducive to gravity drainage owing to the moderate to steep slopes. All

discharges of groundwater will follow advice set out in PPG 6: Working at Construction and

Demolition sites. If, following detailed design, dewatering of any of the borrow pits is considered

necessary, all dewatering would be designed in accordance with CIRIA guidance C532 entitled

“Control of Water Pollution from Construction Sites (2001)”

7.179. It is not anticipated that there will be widespread groundwater present when the borrow pits are

being excavated due to the elevation of the proposed structures relative to local springs. Any

collection and discharge of groundwater would be dealt with in a similar way to surface water;

being passed through a settlement trap before being discharged to ground. Prior to excavation of

the rock all surface soils and peat will be removed and stockpiled for use in the reinstatement of the

borrow pits. The stockpiles will be located and battered so as to limit instability and erosion. Silt

fences and mats will be used to minimise sediment levels in runoff from the stockpiles.

7.180. Following detailed design of the dewatering operations for any given borrow pit, the EA and the

local council will be consulted to confirm the environmental acceptability of any dewatering

proposals to be provided in the CEMP.

7.181. Prior to any construction or extraction taking place all details relating to the borrow pit will be

detailed in the CEMP that will be circulated to the EA and the local authorities for approval before

works can commence. This plan will detail how the Development would be constructed and all the

necessary mitigation measure to be put in place to mitigate environmental impacts. This would

include the general approach to the works and also site specific actions to deal with highlighted

risks. In addition this plan will document all environmental monitoring works and emergency

response procedures. This plan would typically include information such as:

An emergency response plan with key contact list for emergency services and emergency

procedures clearly defined;

A site drainage plan;

A site chemical product and waste inventory;

CPL PAGE 7-45


A site waste management plan;

A protocol of environmental monitoring procedures and employment of suitable qualified

environmental staff; and

Details on compliance with PPGs and CIRIA guidance and any imposed planning conditions.

7.182. Measures to the disturbance and degradation of peat resources during and after the construction of

borrow pits will be detailed in the PMP (Appendix 7.2). Borrow pit design, including design of the

restoration, will take account restoration objectives relating to habitat and environment. In particular

they will be designed such that water levels within the restored habitat can be maintained at ground

level, to allow water-logged conditions to be maintained. This can be achieved by excavating the

borrow pits downslope where possible, allowing the downslope worked face to retain high water

levels within the restored area thus preventing reinstated peat from drying out.

7.13 Residual Effects

7.183. Potentially significant impacts prior to mitigation (either moderate or high) (as described in Section

7.10) have been carried forward for the assessment of residual effects. Those impacts of minor or

negligible significance have not been taken forward to this stage. Likely potential significant

impacts (prior to mitigation) during construction are limited to only moderate impacts to surface

water and geology. During operation, likely potential significant impacts (prior to mitigation) are

limited to minor impacts on surface water, which are not considered to be significant and therefore

have not been brought forward to this section.

Construction 7.13.1

Surface Water

7.184. Likely significant potential effects prior to mitigation that were taken forward for the assessment of

residual effects to surface water include the following moderate effects:

A temporary decrease in water quality from the generation of turbid runoff migrating to down

gradient surface watercourses, downstream public water supply reservoirs and PWS which may

receive surface water runoff from the construction of site infrastructure;

Disturbance to stream banks causing changes in erosion rates and local morphology from the

construction of watercourse crossings; and

A decrease in water quality of watercourses located down gradient of a peat slide occurrence.

7.185. Following the implementation of mitigation measures, the likelihood of potential effects has been

reduced from moderate to minor and therefore no residual significant effects remain to surface

water during construction.

Geology


residual effects to geology include moderate effects to peat including:

The disruption to peat hydrology and consequent degradation of peat down gradient of access

tracks;

The disruption of peat hydrology and the draining of peat due to the dewatering of groundwater

during the construction of turbines and borrow pits; and

The disturbance and degradation of peat due to excavation of peat for the construction of site

infrastructure.

CPL PAGE 7-46



reduced from moderate to minor and therefore no residual significant effects remain to geology

during construction.

Groundwater

7.188. There are no likely significant potential effects taken forward for the assessment of residual effects

and therefore no residual effects to groundwater remain.

Operation 7.13.2

Surface Water

7.189. Prior to mitigation, there are potential moderate impacts to surface water from the vehicular use of

tracks and site activities during operation. After mitigation, the likelihood of potential impacts

occurring is reduced to possible and only minor residual effects are expected.

Groundwater and Geology

7.190. There are no significant negative potential impacts to groundwater or geology expected during

operation. Ecological enhancement and peatland restoration measures set out within the HMP

(Chapter 8: Ecology) and the restoration of the borrow pit areas are anticipated to result in a

moderate positive effect over time as ecology re-establishes.

Decommissioning 7.13.3

Surface Water


residual effects to surface water include moderate effects limited to a temporary decrease in water

quality from the generation of turbid runoff migrating to down gradient surface watercourses and

associated receptors from the removal of site infrastructure.


reduced from moderate to minor and therefore no residual significant effects remain to surface

water during decommissioning.

Groundwater and Geology

7.193. There were no significant negative potential effects to groundwater and geology taken forward for

the assessment of residual effects and therefore no residual effects to groundwater or geology

remain during decommissioning. Restoration measures set out within the HMP should continue to

enhance the ecological environment including peatland habitat throughout and beyond the

decommissioning phase.

7.14 Cumulative Impacts

7.194. The potential for cumulative effects relates to proposed or existing developments which are either

hydraulically connected to the Development Area, or which drain to the same receiving

environment. Potentially significant cumulative hydrological, hydrogeological or geological impacts

are usually only likely if wind farms are to be constructed/decommissioned at the same time as the

majority of potentially significant impacts occur during construction/decommissioning phase.

7.195. There are 42 wind farm sites either under construction or at the planning stages within 35km of

Rooley Moor. Of these, 18 wind farms are located in surface water catchments which drain to the

same surface water receptors as Rooley Moor. These are shown in Table 7.14 below.

CPL PAGE 7-47


Table 7.13 Wind Farms within same receiving surface water catchments

Wind Farm Name Status No. of Turbines Catchment

Reaps Moss Construction 3 River Irwell

Crook Hill Construction 12 River Spodden

Todmorden Moor Construction 5 River Irwell

Scout Moor Operational 26 Naden and Greenbooth

Reservoir, River Roch and

River Irwell

Scar End Farm Consented 4 River Irwell

Sillinghurst Farm Consented 1 River Irwell

Veterans Farm Consented 1 River Roch

Stand Lees Farm Consented 1 River Roch

Bottomly Bank Farm Consented 2 River Irwell

Height Side Farm Consented 1 River Irwell

Parrock Farm Consented 1 River Irwell

Crown Farm Consented 1 River Irwell

Gorpley Planning 4 River Irwell

Beet Farm Planning 1 River Roch

Under Brow Farm Planning 1 River Irwell

Wallsclough Planning 1 River Irwell

Scout Moor infill Scoping 6 Naden and Greenbooth


River Irwell

Scout Moor Northern

Extension

Scoping 16 Naden and Greenbooth


River Irwell

7.196. The magnitude of impact is likely to be highest in catchments where wind farms are in close

proximity. Scout Moor, Scout Moor infill and Scout Moor Northern wind farms are located within

5km of the Rooley Moor Wind Farm site, however, Scout Moor is operational and Scout Moor Infill

and Scout Moor Northern are only at scoping stages. It is highly likely construction will not have

started on these sites by the time the Rooley Moor construction phase ends, thus removing the risk

of significant cumulative impacts in the Naden and Greenbooth public water supply reservoirs,

Rivers Irwell and Roch.

7.197. The Todmorden, Reaps Moss and Crook Hill wind farms are all under construction. These wind

farms are located over 5km from the proposed Rooley Moor Wind Farm. As these wind farms are

under construction already, it is considered unlikely that there wold be any overlap in the

construction phase with Rooley Moot, resulting in no significant cumulative impacts.

7.198. The majority of the consented wind farms are single turbine developments on farms. Due to the

size of these developments and the relatively minor disruption they will cause, impacts to the water

and geological environments from these wind farms are likely to be negligible. Furthermore, the

CPL PAGE 7-48


small scale of the developments means construction will likely be completed by the time Rooley

Moor construction phase commences.

7.199. Two slightly larger wind farms, Gorpley and Scar End Wind Farm are in planning or have been

consented. The Hydrology, Hydrogeology and Geology EIA chapter for Gorpley and Scar End

Farm Wind farm have been reviewed. In both cases, no significant residual impacts were expected

following the implementation of appropriate mitigation. Both wind farms are within the River Irwell

catchment, however they are in separate subcatchments to the Rooley Moor Wind Farm and

situated over 5km from the Development Area. Due to distance of these sites from the

Development Area, the cumulative effects and resultant significance of impact on the hydrological

environment is not anticipated to be significant.

7.15 Summary and Conclusions

7.200. Overall the residual effects of the Proposed Development on the hydrological, hydrogeological and

geological environments following the implementation of avoidance and mitigation measures are

considered to be minor or less than minor. Residual impacts are limited to:

A temporary decrease in surface water quality during construction and to a lesser extent, during

decommissioning from the generation of turbid runoff migrating to down gradient surface

watercourses;

A temporary decrease in surface water quality during construction in the event of a peat slide

causing peat to migrate to down gradient into surface watercourses;

Disturbance to stream banks causing changes in erosion rates and local morphology during the

construction and potential removal of watercourse crossings; and

Disturbance, degradation and draining of peat during construction.

7.201. With the adoption of a comprehensive CEMP, the incorporation of standard good practice

techniques and with the avoidance measures already taken into account in the design of the

Development, the potential changes to surface water, groundwater and geological environments

are not predicted to be significant.

7.202. There is potential for cumulative effects to down gradient surface watercourses during construction

if the construction periods of the Scout Moor Infill and Scout Moor North projects coincide. As these

EIAs have yet to be written an assessment of cumulative impacts is not yet possible, however, it is

likely these wind farms will need to adopt similarly stringent mitigation measures to ensure no

significant impacts occur, resulting in no significant cumulative impacts.

7.16 References

7-1 Institute of Environmental Management and Assessment (IEMA) guidance (2004)

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