F. Geology & Hydrology ( PDF | 31.0 MB ) - RWE.com

Annex F 

Geology and Hydrology 

• F1 – Water Resources and Flooding: 

Legislation and Policy Context 

• F2 – Clocaenog Forest Wind Farm 

Peat Survey Report 

• F3 – National Soil Resources 

Institute Soil Site Reports - North 

and South 

• F4 – Flood Consequences 

Assessment – Clocaenog Wind 

Farm 

• F5 – Clocaenog Forest Wind Farm 

Private Water Supply Assessment 

• F6 – Methodology and reasons for 

choosing mineral sites

Annex F1 

Water Resources and 

Flooding: Legislation and 

Policy Context

F1 WATER RESOURCES AND FLOODING - LEGISLATION AND POLICY 

CONTEXT 

F1.1 THE WATER FRAMEWORK DIRECTIVE, ITS TRANSPOSITION INTO NATIONAL LAW 

AND ASSOCIATED REGIONAL AND LOCAL COMMITMENTS 

The Water Framework Directive (WFD, 2000/60/EC), currently being 

implemented in the UK, has the main objectives of protecting, enhancing and 

restoring Europe’s waters, with the aim of achieving ‘good’ status by 2015 (1) , 

establishing a baseline of no deterioration, and encouraging the sustainable 

use of water resources and the water environment. It should be noted that 

‘good’ status has not yet been defined across Europe. This introduces 

uncertainties at the current time with regard to the assessment of risks and the 

development of policies and measures aimed at progressing WFD objectives 

in this regard. 

The Water Environment (Water Framework Directive) (England and Wales) 

Regulations, 2003 represent the transposition of the requirements of the WFD 

into domestic law. The next few years will see significant changes to the ways 

in which the aquatic environment is managed and the methods by which 

activities affecting surface water and groundwater are controlled and 

assessed. 

River Basin Districts (RBDs) are defined under the Directive, eleven of which 

fall within England and Wales (3 within Wales, including cross borders 

districts). The Development area is split between the Dee RBD and the 

Western Wales RBD. Draft River Basin Management Plans (RBMPs) for the 

Dee and Western Wales RBDs were published by the Environment Agency 

(EA) for consultation in December 2008, with final versions published in 

December 2009. The RBMPs set out key pressures on the water environment 

which could prevent achievement of the WFD objective of ‘good status’ of all 

water bodies by 2015, and outline the actions that will be taken to address 

these pressures. Key pressures identified within the Dee and Western Wales 

RBDs include: 

• alien species; 

• commercial fisheries (shellfish); 

• mine waters; 

• diffuse pollution (from nitrates, pesticides, metals, phosphates, sediments, 

urban and transport pollution); and 

• point source pollution (including organic pollution, pesticides, 

phosphorous and sediments). 

(1) For surface waters 'good' ecological and chemical status by 2015, for groundwaters, 'good' qualitative and chemical 

status by 2015. 

ENVIRONMENTAL RESOURCES MANAGEMENT RWE NPOWER RENEWABLES LTD 

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The Environment Agency has also produced Catchment Abstraction 

Management Strategys (CAMS) for the Clwydd (March 2005) and the Dee 

(March 2008) catchments. The strategies introduce the principle of Water 

Resource Management Units (WRMUs) and Ground Water Management 

Units (GWMUs). The aim of the CAMS is to provide a framework for a 

consistent and structured approach to local water resources management, 

encouraging a balance to be found between the needs of abstractors and the 

needs of the aquatic environment. 

F1.2 ENVIRONMENTAL QUALITY STANDARDS, RIVER QUALITY OBJECTIVES, TARGETS 

AND THE GENERAL QUALITY ASSESSMENT 

River quality is one of the 68 indicators identified by the UK government’s 

sustainable development strategy: Securing the Future, launched in 2005, and is 

also one of the 20 indicators outlined within One Future – Different Paths: the 

UK’s Shared Framework for Sustainable Development, also released in 2005. 

The quality of watercourses in England and Wales is currently classified by 

the Environment Agency under the General Quality Assessment (GQA) 

scheme. Under this scheme, each watercourse is assessed separately upon its 

chemical, ecological (biological), aesthetic qualities and nutrient status. 

Additional details regarding these assessments are provided below. 

• Chemical Quality: based upon dissolved oxygen, biochemical oxygen 

demand (BOD) and ammonia concentrations, the watercourse is assigned 

one of six grades: A (very good) to F (bad). These parameters are 

considered to be the best indicators of the extent to which waters are 

affected by wastewater discharge and rural land runoff. 

• Biological Quality: based upon macro-invertebrate studies (an indicator 

of overall ecological health), one of the six grades A to F is assigned, as per 

Chemical Quality. 

• Aesthetic Quality: gives an indication of our perception of river quality 

through the assessment of various factors including the presence of litter, 

foam, oil, fungus, odour and colour. The grading system ranges from 

1 (good) to 4 (bad). 

• Nutrient Status: based upon phosphate and nitrate concentrations, which 

are most likely to be influenced by human activity. A grade of 1 (very 

low) to 6 (phosphates: excessively high, nitrates: very high) is assigned. 

In addition to the GQA, Environmental Quality Standards (EQSs) establish 

concentrations of specified substances and are either informal or statutory. 

Statutory EQSs are generally informed by the Dangerous Substances Directive 

and the Surface Waters (Dangerous Substances) (Classification) Regulations, 1997 

and 1998 (see below for further information). 


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After the GQA has been conducted, and in light of EQSs, River Quality 

Objectives (RQOs) are generally introduced. RQOs set targets to aid in the 

protection and improvement of river quality, based upon the River Ecosystem 

(RE) Classification. The RE classification specifies the uses a particular 

watercourse should ideally be able to provide, in terms, for example, of being 

suitable for supporting fish. The classification is based upon quality 

parameters defined within the Freshwater Fish Directive and consists of five 

classes: RE1 (high quality) to RE5 (low quality) with an additional unclassified 

level for watercourses suffering from considerable pollution. No legal 

requirements are directly associated with RQOs. 

Both EQSs and RQOs are based primarily upon chemical quality and are 

applied to particular watercourse reaches. 

F1.3 DANGEROUS SUBSTANCES DIRECTIVE (76/464/EEC), DAUGHTER DIRECTIVES AND 

THE SURFACE WATERS (DANGEROUS SUBSTANCES) (CLASSIFICATION) 

REGULATIONS, 1997 AND 1998 

The Directive and regulations detail the approach to be taken with respect to 

two categories of substances: List I and List II. Pollution by substances within 

List I must be eliminated, whilst pollution by List II substances must be 

reduced. Emission Limit Values (ELVs, also known as Uniform Emission 

Standards, or UESs) and EQSs have been established by a series of daughter 

Directives. EQSs for List II substances have been set by the UK within the 

Surface Waters (Dangerous Substances) (Classification) Regulations, 1997 and 1998. 

The Dangerous Substances Directive will be repealed by the WFD in 2013. The 

transition requires a daughter Directive, named the Priority Substances 

Directive, which is currently in proposal by the European Commission 

awaiting approval by Member States and the European Parliament. 

F1.4 URBAN WASTE WATER TREATMENT DIRECTIVE (91/271/EEC) AND THE URBAN 

WASTE WATER TREATMENT REGULATIONS, 1994 

Specific emission limits for discharges are established under the Urban Waste 

Water Treatment Directive. This Directive and the transposed regulations 

require emission standards or percentage reduction targets to be met for 

effluents (based upon BOD and suspended solids). 

F1.5 THE ENVIRONMENT ACT 1995, WATER RESOURCES ACT 1991 AND THE LAND 

DRAINAGE ACT 1991 

Under the Environment Act 1995 it is an offence to discharge poisonous, 

noxious or polluting material into any ‘controlled waters’ either deliberately 

or accidentally. Polluting materials include silt, cement, concrete, oil, 

petroleum spirit, sewage or other debris and waste materials. ‘Controlled 

Waters’ include all watercourses and water contained in underground strata. 


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Road drains and surface water gullies generally discharge into controlled 

waters and should be treated as such. 

The Water Resources Act 1991, together with changes under this Act by the 

Water Act 2003, requires consents to be obtained for any discharges to 

controlled waters. The Land Drainage Act 1991 states that consent (now known 

as Flood Defence Consent, FDC) will be required for works affecting drainage 

ditches along the route. Applications to the Competent Authority are 

required, which is generally the Environment Agency, but can, under some 

circumstances, be the controlling Internal Drainage Board (IDB). 

F1.6 THE FRESHWATER FISH DIRECTIVE (78/659/EEC) AND THE SURFACE WATERS 

(FISHLIFE) (CLASSIFICATION) (AMENDMENT) REGULATIONS, 2003 

The Directive and regulations aim to protect surface waters identified as being 

of suitable, or potentially suitable, quality for sustaining fish populations. 

Objectives and parameters for salmonid (1) and cyprinid (2) waters (and waters 

identified as being of potential suitability) are also set. The Surface Waters 

(Fishlife) (Classification) Regulations, 1997 represented the original transposition 

of the Directive in the UK. The 2003 amendment regulations transpose the 

Directive, which will be repealed in 2013 by the WFD. 

F1.7 THE GROUNDWATER DIRECTIVE (80/68/EEC) AND THE GROUNDWATER 

REGULATIONS, 1998 

Directive 2006/118/EC on the protection of groundwater against pollution 

and deterioration was provided for by Article 17 of the WFD. This Directive 

supplements the general rules for the protection of groundwater established 

through WFD in replacement of the Groundwater Directive (80/68/EEC). 

The new Daughter Directive sets safety values for various polluting 

substances, introducing criteria for quality standards, guidelines for the 

establishment of threshold values and procedures for assessing groundwater 

status. The Directive entered into force as of December 2008 with member 

states having a national transposition deadline of January 2009. The 

Groundwater Directive represents the third Directive set to be repealed by the 

WFD in 2013. 

F1.8 SOURCE PROTECTION ZONES 

The vulnerability of groundwater to pollution is dependent on the presence 

and nature of the overlying soils and drift deposits, the geology and the depth 

to the water table. This will determine the rate at which a contaminant can 

migrate into the water. The Environment Agency has identified Source 

(1) Salmonid is a term applied to waters suitable for supporting fish from the family Salmonidae. This family includes 

anadromous, or migratory, species including salmon and some species of trout. 

(2) Cyprinid is a term used to describe waters suitable for fish from the family Cyprinidae, which includes coarse fish such 

as carp, roach and tench. 


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Protection Zones (SPZs) across England and Wales to protect the quality of 

groundwater resources, primarily those used for public potable water 

supplies. Within SPZs there are inner and outer protection zones defined 

according to the above criteria. The Environment Agency’s approach to 

controlling and preventing the pollution of groundwater is set out in its Policy 

and Practice for the Protection of Groundwater (1998). 

F1.9 THE FLOODS DIRECTIVE (2007/60/EC) 

The Floods Directive came into force in November 2007. Member states have 

two years to transpose the Directive into National Law. Under the Directive, 

high level Flood Risk Assessments are required by the close of 2011, with 

flood hazard and impact maps being required by the close of 2013, and 

management plans by December 2015. Updates to these documents will be 

conducted every six years thereafter. 

The Floods and Water Management Bill, the transposition of the Floods 

Directive, is currently progressing through the House of Lords awaiting Royal 

Assent. Once adopted, the Act will transfer and alter a number of 

responsibilities with regards to the management of flood risk, including 

increasing the powers of the Environment Agency, transferring drainage and 

related flooding sources to Local Authorities, advancing controls on reservoir 

safety, and ending the automatic right to discharge to sewer for new 

development. 

F1.10 TECHNICAL ADVICE NOTE 15: DEVELOPMENT AND FLOOD RISK 

In Wales, Technical Advice Notes (TANs) have been developed to supplement 

Planning Policy Wales (PPW) and to provide guidance on a number of key 

issues and sensitivities. Of relevance to this assessment is TAN 15: 

Development and Flood Risk, 2004 (1) . The TAN introduces a precautionary 

framework, informed by a development advice map and associated 

‘development advice zones’ (A, B and C (C1 and C2)) which may be used to 

trigger planning tests in relation to flood risk. 

In July 2004 the Welsh Assembly Government published Development Advice 

Maps (DAMS) to accompany the latest version of TAN 15 – Development and 

Flood Risk. Only the DAMS, which accompany TAN 15, should be used to 

identify relevant planning zones and whether a site falls within them. 

The 2004 DAMS have since been superseded (September 2009) and the 

updated versions are currently unavailable. The level of risk assigned to the 

site is not, however, believed to have been altered. 

(1) ( ) TAN 15 may be viewed on the Welsh Assembly website at the following internet address: 

http://new.wales.gov.uk/docrepos/40382/4038231121/403821/403821/40382/403821/july04-tan15-e.pdf?lang=en 


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The maps are based on information provided by the Environment Agency and 

the British Geological Society. The maps contain three development advice 

zones which are attributed to different planning actions, see Table F1.1 below. 

Table F1.1 TAN15 Development Advice Zones 

Description of Zone Use within the precautionary framework 

A Considered to be a little or no risk of fluvial or coastal/tidal 

flooding 

B Areas known to have been flooded in the past evidenced by 

sedimentary deposits 

C Based on Environment Agency extreme flood outline, equal to or 

greater than 0.1% (river, tidal or coastal) 

C1 Areas of the floodplain which are developed and serviced by 

significant infrastructure, including flood defences. 

C2 Areas of the floodplain without significant flood defence 

infrastructure. 

F1.11 THE CIVIL CONTINGENCIES ACT, 2004 AND THE CLIMATE CHANGE ACT 2008 

The Civil Contingencies Act 2004 (Contingency Planning) Regulations 2005 affords 

powers and responsibilities to Category 1 and 2 Responders for significant event 

situations, which includes flooding in addition to matters such as terrorist 

threat. Responders have defined responsibilities under the Act, which 

represent compliance requirements. 

Requirements concerning adaptation to climate change, including flood risk 

adaptation, have also been introduced through the Climate Change Act 2008. 

Requirements for reporting on adaptation risks and capabilities are currently 

available in consultation draft for defined ‘Reporting Authority’ categories 

which include public and private bodies. 

F1.12 DENBIGHSHIRE COUNTY COUNCIL UNITARY DEVELOPMENT PLAN (2002) 

Development policies of relevance in terms of geology, water resources and 

flooding are listed below. 

• ENP 1: Pollution 

• ENP 3: Water Resources 

• ENP 4: Foul and Surface Water Drainage 

• ENP 6: Flooding 

• ENP 7: Unstable Land 

• ENP 8: Contaminated Land 


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F1.13 CLWYD STRUCTURE PLAN SECOND ALTERATION (CONWY VERSION) (1999) 

Development policies of relevance in terms of geology, water resources and 

flooding are listed below. 

• CONS 10: Planning permission will not be granted for development that is 

likely to have an adverse affect on the nature conservation or other 

scientific value of sites of special scientific interest. 

• CONS 18: Development will be allowed in coastal areas or areas adjacent 

to rivers, subject to other structure plan policies, unless one of the 

following apply: 

A. There would be an unacceptable risk to flooding. 

B. There would an unacceptable increase in the risk of flooding 

elsewhere. 

C. The capability of the coast to form a natural sea defence would be 

prejudiced. 

D. Additional public finance would be required for coastal or riparian 

defence works other than that necessary to protect existing 

investment. 

E. The development would adversely affect existing or new flood 

defence operations. 

F1.14 POLLUTION PREVENTION GUIDELINES 

Pollution Prevention Guidelines (PPGs) have been jointly produced by the 

environmental regulatory authorities within the UK. PPGs of relevance to this 

project are referenced below. 

• PPG01 General guide to the prevention of water pollution. 

• PPG05: Works and maintenance in or near water. 

• PPG06: Working at construction and demolition sites. 

• PPG20: Dewatering underground ducts and chambers. 

• PPG21: Pollution incident response planning. 


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Annex F2 

Clocaenog Forest Wind 

Farm Peat Survey Report

CONTENTS 

1 INTRODUCTION 1 

2 ASSESSMENT METHODOLOGY 2 

2.1 INTRODUCTION 2 

2.2 DESK STUDY 2 

2.3 FIELD SURVEY 3 

2.4 PEAT LOSS CALCULATIONS 4 

2.5 CONSULTATION 5 

3 RESULTS 6 

3.1 DESK STUDY RESULTS 6 

3.2 FIELD SURVEY RESULTS 13 

4 RECOMMENDED MITIGATION MEASURES 26 

4.1 INTRODUCTION 26 

4.2 PRE-CONSTRUCTION SURVEYS 26 

4.3 MICRO-SITING CONSIDERATIONS 26 

4.4 CONSTRUCTION GOOD PRACTICE 26 

APPENDIX 1 CCW CORRESPONDENCE 

APPENDIX 2 PHOTOLOG 

APPENDIX 3 DETAILED PEAT DEPTH MAPS

1 INTRODUCTION 

This report presents the results of a desk-based study and targeted peat depth 

survey conducted at the Clocaenog Forest Wind Farm site in Denbighshire 

and Conwy, North Wales. The study was undertaken to determine the extent 

of peat deposits in the vicinity of the proposed wind farm infrastructure, both 

to inform amendments to the site layout during the design stage, and to 

identify areas where mitigation measures are required to protect peatland 

habitats during construction and operation of the wind farm. 

The specific objectives of the peat assessment were to: 

• review existing information sources to identify potential areas of peat 

deposits across the site; 

• undertake a targeted peat survey of the site to ‘ground truth’ the existing 

sources of information and identify the extent of peat deposits in 

proximity to wind farm infrastructure; 

• inform amendments to the wind farm site layout to avoid impacting on 

peat deposits where possible; 

• calculate the approximate area and volume of peat that will be directly 

and indirectly impacted by the proposed scheme; and 

• identify areas where mitigation measures are required to prevent or 

reduce impacts to identified peat deposits. 

The remainder of this report is structured as follows. 

• Section 2 outlines the assessment methodology and the consultation 

undertaken to date with Countryside Council for Wales (CCW). 

• Section 3 presents the results of the desk-based study and field survey, and 

the calculations of direct and indirect peat loss as a result of wind farm 

construction. 

• Section 4 identifies the recommended mitigation measures to prevent and 

reduce impacts to the identified peat deposits. 

• Section 5 presents a summary of the results. 


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2 ASSESSMENT METHODOLOGY 

2.1 INTRODUCTION 

2.2 DESK STUDY 

The extent and depth of peat deposits across the development area was 

assessed through a combination of desk-based study and field survey work, 

using the methodologies outlined in Sections 2.2 and 2.3 respectively. 

Following completion of the peat survey and finalisation of the site layout, the 

approximate area and volume of peat that will be directly and indirectly 

impacted by the proposed scheme was calculated using the method outlined 

in Section 2.5. A summary of the consultation undertaken with Countryside 

Council for Wales (CCW) to agree the proposed survey methodology is 

presented in Section 2.6. 

The purpose of the desk study was to identify the potential extent of peat 

deposits across the development area based on existing information. As well 

as determining whether the peat resource on site was extensive (ie covering 

the majority of the development area) or limited to more localised areas, the 

desk study was used to identify areas where more targeted peat probing was 

required and to inform initial changes to the site layout (see Chapter 3 of the ES 

for further information regarding how the peat assessment has informed the 

final site design). The desk study covered the entire development area, to 

ensure that as much information was gathered as possible to inform 

alterations to the site layout. 

The desk-based study included a review of the following existing information 

sources: 

• British Geological Survey (BGS) 1:50,000 solid and drift geology map data 

to identify potential areas of peat deposits; 

• Cranfield University’s National Soil Resources Institute 1:250,000 National 

Soil Map data (1) to identify the distribution and characteristics of soil 

associations across the development area, in particular to identify any soil 

associations with an important peat element; 

• Ordnance Survey 1:25,000 and 1:50,000 map data to identify those areas 

which may be prone to peat accumulation (eg flatter slopes, valley 

bottoms, saddles between river catchments, gently sloping spurs); 

(1) National Soil Resources Institute (2009). Full Soils Site Report for location 301000E 356500N, 5km x 5km, National Soil 

Resources Institute. Cranfield University, access vua https://www.landis.org.uk/sitereporter/. 


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2.3 FIELD SURVEY 

• Phase 1 Habitat Survey results for the development area (Annex E) to 

locate any areas of identified bog habitat on the site, which could indicate 

significant peat accumulations; and 

• Aerial photography of the development area to identify areas where tree 

planting appears to have resulted in stunted growth which may indicate 

waterlogged soil conditions. 

Following completion of the desk-based study the areas likely to contain peat 

were identified and areas to be surveyed were selected. Those elements of the 

proposed wind farm site layout (including turbines, hardstanding areas and 

access tracks) that are located inside, or within approximately 100m, of 

potential peat deposits were included in the survey area. In addition, 

elements of the site layout which are located within soil associations which 

may contain an important peat layer were also included (see Section 3.1.3 for 

soil association descriptions). All accessible turbine locations were surveyed, 

regardless of proximity to potential peat deposits or location within peaty soil 

associations, in order to ‘ground truth’ the findings of the desk-based study to 

the greatest extent possible. 

A full list of those parts of the scheme included in the field survey is provided 

in Section 4. 

At each survey location, the following methodology was adopted. 

• For the proposed turbine locations, a 100m by 100m grid, centred on each 

turbine, was surveyed at a transect density of approximately 20m. This 

amounted to 36 hand augered probes per turbine. This survey area also 

included the proposed crane hardstanding areas. 

• For new access tracks located within potential peat deposits, the proposed 

track route was surveyed at 25m to 50m intervals, dependent on access 

constraints and whether any peat deposits were found in the area. Where 

accessible, three probes were taken across the proposed track route (ie 

centre of track and approximately 10m either side) at each survey point. 

In the event that peat deposits were identified, a wider pattern of lateral 

probing was undertaken on either side of the proposed track, in order to 

inform design of alternative access routes to avoid peat deposits. 

• For existing access tracks located within potential peat deposits, probes 

were taken at 50m intervals on both sides of the access track. Where 

access permitted, probes were taken at both 5m and 10m to 15m from each 

side of the track, to inform any road widening requirements and track-side 

cable routes. 


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• Each peat probing location was recorded with a hand-held GPS, and the 

measured depth of peat recorded to the nearest 10cm. Thicknesses greater 

than 0.5m were recorded as peat. 

• Peat was identified based on ease of probing and visual evidence of ‘peat’ 

recorded on the auger on removal from the probe location. 

• All drainage ditches encountered during peat depth surveying were 

mapped in order to ascertain the current extent of drainage, which may, in 

turn impact on the hydrology of the area and its suitability to support 

peat. 

Survey Limitations 

As the scheme is located within an area of Forestry Commission Wales (FCW) 

upland rotational forestry, there are parts of the site to which it is currently 

not possible to gain safe access without significant intervention (ie brashing 

and felling), due to the presence of dense forestry plantation. In these areas, 

where possible, peat probing was conducted at the closest available location to 

the proposed infrastructure to provide an indication of ground conditions that 

may be encountered at the site itself. In those areas where no nearby access 

was available, further surveying will be required prior to construction of the 

wind farm to ensure infrastructure can be micro-sited to avoid any previously 

unidentified significant peat deposits. In the absence of field survey data, 

results of the desk-based survey are referred to in order to provide a 

description of the likely ground conditions at the site. 

2.4 PEAT LOSS CALCULATIONS 

Following completion of the peat survey and confirmation of the final site 

layout (see Chapter 3 of the ES for details of how the peat assessment has 

informed the final site design), the approximate area and volume of peat that 

will be directly and indirectly impacted by the scheme was calculated. The 

calculations were undertaken following the guidance published by the 

Scottish Government in 2008 (1) and comprised the following steps. 

• Direct loss of peat was calculated based on the total area of peat that 

would be excavated as a result of the footprint of the proposed scheme (eg 

turbine foundations, crane hardstandings, access tracks and cable routes 

located within identified peat deposits). 

• Indirect loss of peat due to drainage around infrastructure components 

(such as access tracks and cable routes) was calculated assuming an 

average extent of drainage around each drainage feature. The extent of 

(1) Nayak, D.R., Miller, D., Nolan, A., Smith, P. and Smith, J. (2008). Calculating carbon savings from wind farms on 

Scottish peat lands - a new approach. Scottish Government, June 2008. 


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2.5 CONSULTATION 

drainage was estimated based on the observed ground conditions at the 

site and published research (see Section 3.2.4 for further details). 

Extensive and ongoing consultation has been undertaken throughout the EIA 

process with CCW to agree the scope and methodology of the peat 

assessment. Table 2.1 summarises the key consultation undertaken to date. 

Copies of all correspondence received from CCW are contained in Appendix 1 

to this report. 

Table 2.1 Summary of Consultation with CCW 

Nature of 

Consultation 

Scoping 

Opinion 

Letter 

consultation on 

peat survey 

methodology 

Further email 

consultation on 

peat survey 

methodology 

Meeting to 

discuss peat 

survey results 

Meeting to 

discuss ecology 

mitigation 

measures 

CCW 

Contact 

Dr David 

Hatcher 

Jonathan 

Gilpin 

Jonathan 

Gilpin 

Jonathan 

Gilpin and 

Pete Jones 

Jonathan 

Gilpin and 

Pete Jones 

Date Comments 

25/08/08 Confirmed that peat and remnants of peatland 

habitat are likely to be present under existing forest 

vegetation and that impacts on peat should be 

considered as part of the EIA. 

28/08/09 Provided specific comments on ERM proposed peat 

survey methodology (eg sampling density, peat 

probing equipment) which have been incorporated 

into the above field survey methodology. Also 

provided general recommendations on survey scope 

and justification for wind farm site layout. 

27/11/09 Additional email correspondence to clarify field 

survey requirements. 

18/12/09 Meeting held to discuss desk and field survey results 

and agree next steps. 

03/02/10 Meeting held to discuss mitigation measures to 

address predicted impacts on ecology, including 

impacts on peat and peatland habitat. 


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3 RESULTS 

3.1 DESK STUDY RESULTS 

3.1.1 Overview 

This section presents an overview of ground conditions, topography, 

vegetation cover and habitats across the development area, based on 

information derived from the desk-based study of existing information 

sources. 

3.1.2 Solid Geology 

The south of the development area is underlain predominantly by deposits of 

the Denbigh Grits Formation, ranging in thickness between 750 and 1500m. 

This formation comprises graptolitic (1) mudstones, siltstones, sandstones, 

mature grits and conglomerates. The north of the development area is largely 

underlain by deposits of the Upper Nantglyn Flags Group, up to 650m in 

thickness. This is comprised of regularly alternating thin mudstones and 

graptolitic muddy siltstones and laterally extensive Upper and Lower Mottled 

Mudstone beds. Both rock formations are of Silurian Age (c. 443.7 to 416 

million years ago). Figure 8.2, in Chapter 8 of the ES, shows the BGS mapped 

solid geology beneath the development area. 

3.1.3 Superficial Deposits 

3.1.4 Soil Type 

The BGS map indicates that the majority of the development area is underlain 

by glacial tills (boulder clay) of unknown thickness, while the higher parts of 

the development area (eg around Craig Bron-banog, Foel Frech and Foel Goch) 

have no superficial deposits. Alluvial sediments are found in the south of the 

development area along the Nant y Ffridd, River Clwyd and River Alwen 

valley floors, and to the north along the Afon Clywedog and Afon Corris 

valley floors. Localised deposits of peat occur along the valley of Nant 

Llyfarddu (from SJ 003 524 to SJ 023 535) and in smaller pockets in the north 

and west of the development area. Figure 8.3, in Chapter 8 of the ES, shows the 

BGS mapped distribution of superficial deposits across the development area. 

According to the NSRI 1:250,000 soil map data, three soil associations are 

present within the development area. Hafren and Wilcocks 2 associations 

cover the majority of the development rea, with areas of the Brickfield 1 

association in the south (2) (3). Table 3.1 describes the key characteristics of each 

(1) Mudstones with evidence of the tube-like marine organisms, Graptolites. 

(2) National Soil Resources Institute (2009). Full Soils Site Report for location 301000E 356500N, 5km x 5km, Natiional Soil 

Resources Institute, Cranfield University. Accessed via https://www.landis.org.uk/sitereporter/. 

(3) National Soil Resources Institute (2009). Full Soils Site Report for location 301500E 352000N, 4km x 4km, Natiional Soil 

Resources Institute, Cranfield University. Accessed via https://www.landis.org.uk/sitereporter/. 


6

soil association, including the comprising soil series characteristics. The full 

NSRI Site Soil Report can be viewed in Annex D3 of the ES. 

Table 3.1 Soil Association Characteristics 

Hafren Brickfield 1 Wilcocks 2 

Description Loamy permeable upland 

soils over rock, with a 

wet peaty surface horizon 

and bleached subsurface 

horizon, often with thin 

ironpan. May include 

some peat on higher 

ground. Rock and scree 

locally. 

Comprising 

Soil Series 

Soil parent 

material 

Hafren (45%) – loamy 

material of lithoskeletal 

mudstone and sandstone 

or slate. 

Hiraethog (20%) – loamy 

material over lithoskeletal 


or slate. 

Wilcocks (10%) – loamy 

drift with siliceous 

stones. 

Other (25%) – other 

minor soils. 

Palaeozoic slaty 

mudstone and siltstone. 

Source: National Soil Resources Institute (2009) 

Slowly permeable 

seasonally waterlogged 

fine loamy and fine silty 

soils, some with wet 

peaty surface horizons. 

Brickfield (30%) – 

medium loamy drift with 

siliceous stones. 



stones. 

Greyland (10%) – 

medium loamy over 

clayey drift with siliceous 

stones. 

Cegin (10%) – medium 

silty drift with siliceous 

stones. 


minor soils. 

Drift from Palaeozoic 

slaty mudstone and 

siltstone. 

Slowly permeable, 

seasonally waterlogged 

loamy upland soils with a 

peaty surface horizon. 

Some very acid peat soils. 



stones. 

Crowdy (15%) – humified 

peat, up to 1m in 

thickness. 

Winter Hill (15%) – 

mixed eriophorum and 

sphagnum peat, up to 

1.2m in thickness. 

Hafren (10%) - loamy 

material of lithoskeletal 


or slate. 


minor soils. 

Drift from Palaeozoic 

sandstone, mudstone and 

shale. 

Figures 3.1 to 3.3 below show the profiles of the component soil series for each 

of the above soil associations. Figures 3.1 and 3.2 show that the soil series 

comprising the Hafren and Brickfield 1 soil associations are characterised by 

shallow (10cm to 20cm) surface peaty horizons, beneath which are layers of 

clay or sandy silt loam. Figure 3.3 shows that two of the Wilcocks 2 

comprising soil series (Wilcocks and Hafren) are also characterised by shallow 

(10cm to 20cm) surface peaty horizons, again with clay loam or sandy clay 

loam horizons beneath. The Crowdy and Winter Hill horizons, however, are 

characterised by deep peat horizons, 100cm to 120cm thick. The Crowdy soil 

series comprises dark brown or black stoneless, humified peat with a massive 

structure. The Winter Hill soil series comprises dark reddish brown or dark 

reddish grey semi-fibrous, Eriophorum-Sphagnum peat, with a moderate to 

weak coarse platy structure in the top 70cm and a massive structure in the 


7

lower horizon. From these soil series profiles, it can be seen that the Wilcocks 

2 soil association is the only one which includes soil series with an important 

peat element (ie the Crowdy and Winter Hill soil series). It is therefore 

considered likely that only those parts of the development area which are 

located within the Wilcocks 2 soil distribution may contain significant peat 

deposits. 

Cross reference of the NSRI soil distributions with BGS map data shows good 

correlation of BGS peat deposits within the Wilcocks 2 soil association, with 

almost all BGS peat deposits located within the Wilcocks 2 soil association. 

The only exception to this is an area of peat in a small valley depression 

approximately 175m to the south east of Turbine 2, located within the Hafren 

soil association. 

Figure 3.1 Hafren Comprising Soil Series Profiles 

Source: National Soil Resources Institute (2009) Full Soils Site Report for location 301000E, 

356500N, 5km x 5km, National Soil Resources Institute, Cranfield University. Accessed via 

https://www.landis.org.uk/sitereporter/. 


8

Figure 3.2 Brickfield 1 Comprising Soil Series Profiles 





9

Figure 3.3 Wilcocks 2 Comprising Soil Series Profiles 

3.1.5 Topography 




Peat formation occurs when plant material is inhibited from decaying fully by 

acidic and anaerobic conditions. It therefore tends to accumulate in poorly 

drained, waterlogged areas, where anaerobic conditions predominate. 

Consequently, certain topographic features with inhibited drainage are more 

prone to peat accumulation, such as flatter slopes, shallow valley bottoms, 

small depressions and hollows, saddles between river catchments and gently 

sloping spurs. 

Ordnance Survey 1:25,000 and 1:50,000 map data was studied to identify the 

areas which may be more topographically suited to peat accumulation. The 


10

development area is located along a ridge of hills stretching from Bryn Ocyn 

and Tir Mostyn in the north, through Foel Frech in the centre, to Craig Bronbanog 

in the south. Numerous watercourses intersect the development area, 

often located within steep-sided valleys and flowing at steep gradients 

unsuitable for peat accumulation. The sources of these watercourses are 

however generally located in flatter areas and small depressions where water 

tends to accumulate, and are suitable areas for peat formation. Cross 

reference with the BGS map data shows that all of the BGS mapped peat 

deposits are located in watercourse source areas, including a large (max 450m 

by 300m) deposit surrounding the Aber Waen-lydan source and a 2km long 

continuous peat deposit in the upper reaches of Nant Llyfarddu and an 

unnamed tributary of Afon Alwen. 

Not all watercourses draining the site have a BGS mapped peat deposit in 

their upper reaches and it is possible that these areas may hold previously 

unidentified peat deposits. Other areas which could be suitable for peat 

accumulation include spurs and other flatter parts of the site. The potential 

for peat accumulation based on topographic features is considered in more 

detail for each turbine location in Section 3.2. 

3.1.6 Phase 1 Habitat Survey 

The results of the Phase 1 Habitat Survey and NVC survey (see Annex E of the 

ES) were reviewed to locate any areas of identified peat-forming mire habitat 

or plant communities within the development area, which could be an 

indication of significant peat accumulations and active peat bog. It should be 

noted, however, that the majority of the development area is characterised by 

coniferous plantation and therefore the vegetation survey results will only 

indicate areas of peatland that have not been previously planted over. 

The Phase 1 Habitat survey did not identify any mire habitat within the 

development area. Mire habitat includes: blanket bog; raised bog; wet and 

dry modified bog; acid, neutral or basic flushes; bryophyte dominated spring; 

and valley, basin and flood plain mires. Parts of the development area have, 

however, been classified as acid dry heathland, where ericoid species 

constitute greater than 25% of the shrub layer (and there is less than 30% tree 

cover). Clearance of previous coniferous plantations has created micromosaics 

of habitats within the heathland, with the undulating micro 

topography resulting in the colonisation of depressions by species such as: 

Sphagnum mosses, hare’s tail cotton-grass, sedges and rushes (ie species 

thriving in the wet); and on the raised areas by heather, bilberry, heath 

bedstraw and wavy hair-grass. Although some of these species indicate the 

presence of underlying peat in certain areas, the NVC results suggest that the 

wider habitat should still be considered as heath habitat. 

The lack of mire habitat within the development area indicates that, although 

there may be peat deposits beneath the coniferous plantation forest and 

beneath the heathland habitat, the site cannot be considered to hold important 

active peatland habitat (ie there are no areas characterised within the survey 


11

y their peat-forming vegetation). It is clear that the habitat within the 

development area has been highly modified by the planting and management 

of coniferous trees since the early 20 th Century (1) , with associated impacts on 

peat deposits and peat habitat arising from: 

• loss of peat-forming vegetation communities to coniferous forestry 

plantation; 

• installation of drainage ditches to drain waterlogged and peaty soils, 

drying out existing peat deposits and altering the hydrology of the upper 

soil layers; 

• damage to peat deposits from mechanical plant movements during felling 

operations; 

• application of fertilisers and pesticides, modifying plant communities 

beneath the forest canopy and along roadside verges; and 

• construction of forest roads through existing peat deposits, altering their 

hydrological connectivity and fragmenting deposits. 

It should also be noted that, although it may be possible to restore parts of the 

development area with significant underlying peat deposits to active bog, the 

current Forestry Design Plan consists of continued forestry over the majority 

of the site. As a result, construction of the wind farm will not impact on any 

mire habitat, or potential mire habitat, when viewed in comparison to ongoing 

forest operations which do not include peatland restoration. Peat deposits 

within the development area should therefore be considered valuable in terms 

of their existing carbon stores, rather than as active peatland habitat. Annex C 

of the ES details the results of the carbon balance assessment undertaken for 

the scheme. 

3.1.7 Vegetation Cover 

Aerial photographs of the development area were consulted to identify any 

areas where tree planting appears to have failed or resulted in stunted growth, 

as this may indicate waterlogged soil conditions or underlying peat deposits. 

Due to the varying age and species composition of trees across the forest, 

however, it was not possible to identify any areas of stunted or failed tree 

growth. This method is therefore not considered to be appropriate for 

identifying areas of peat beneath the existing forest canopy. 

(1) Planting of Clocaenog Forest began in 1905 prior to the creation of the FCW in 1919, who now manage the forest on 

behalf of the Weslh Assembly Government. 


12

3.2 FIELD SURVEY RESULTS 

3.2.1 Overview 

As a result of the desk-based survey, it was concluded that those elements of 

the proposed site layout (including turbines, hardstanding areas and access 

tracks) located inside, or within 100m, of BGS mapped peat deposits should be 

included in the field survey area. Elements of the site layout located within 

the areas mapped by NSRI as Wilcocks 2 soil association were also included. 

In addition, all accessible turbine locations were surveyed, regardless of 

proximity to potential peat deposits or location within the Wilcocks 2 soil 

association, in order to ‘ground truth’ the results of the desk based study to 

the greatest extent possible. 

Sections 3.2.2 and 3.2.3 provide the results of the peat survey for the proposed 

turbine locations and access tracks respectively. Figures 3.4 and 3.5 can be 

referred to for an overview of the field survey results across the development 

area as a whole. 

3.2.2 Turbine Locations 

Table 3.2 details the results of the peat depth survey for each turbine location. 

A total of 14 turbines, out of the proposed 32, were included in the field 

survey. The remaining 18 turbines were inaccessible due to the presence of 

dense forestry. In the absence of field survey data at these locations, results of 

the desk-based survey have been utilised to provide a description of the likely 

ground conditions at the site. A photolog of turbine locations is provided in 

Appendix 2. Detailed peat depth maps for each surveyed turbine location are 

provided in Appendix 3. 

The survey results have identified that two turbine locations (Turbines 11 and 

19) are located within peat deposits. An additional two turbine locations 

(Turbines 2 and 4) are located in close proximity to peat deposits. All four 

turbines are all located in areas which are currently planted with commercial 

forestry and are planned to remain afforested as part of the ongoing Forestry 

Design Plans. Impacts should therefore be considered in terms of loss of 

carbon stores rather than loss of mire habitat 

Calculations of the total area of peat that will be lost directly, and indirectly, as 

a result of construction of these turbines and associated crane hardstanding 

areas are presented in Section 3.2.4. 


13

Table 3.2 Peat survey results at proposed turbine locations 

BGS superfiical 

deposits and 

underlying bedrock Topography 

Turbine NSRI Soil 

Number Association 

1 Wilcocks 2 Glacial till over Elwy 

formation mudstone, 

siltstone and 

sandstone 

2 Hafren Glacial till over Elwy 


siltstone and 

sandstone 

3 Hafren Glacial till over Elwy 


siltstone and 

sandstone 

4 Wilcocks 2 No superficial 

deposits. Nantglyn 

Flags mudstone and 

siltstone bedrock. 

Significant peat 

deposit to W, S and SE 

of turbine and 

hardstanding. 


deposits. Nantglyn 



6 Hafren Glacial till over 

Nantglyn Flags 

mudstone and siltstone 

Flat. Nearest 

watercourse 140m 

NE 

Slopes gently NE 

towards nearest 

watercourse, 100m 

NE 

Slopes very gently 

SE towards track. 

Nearest 


N. 

Slopes very gently 

S towards 


SW. 

Slopes gently SE 

towards track, 

nearest 


S. 

Slopes NW. 

Clywedog 

reservoir 175m 

NW 

Phase 1 

Habitat 

Survey 

Coniferous 

plantation 

Forestry 

crop 

Sitka 

spruce 

Heathland Sitka 

spruce 

Coniferous 

plantation 

Recently 

felled 

Coniferous 

plantation 

Coniferous 

plantation 

Sitka 

spruce 

Sitka 

spruce 

Sitka 

spruce 

Sitka 

spruce 

Plant Field Survey Peat 

year Completed present Results 

1957 Yes. Access to parts No BGS/NSRI map data and peat depth survey 

of survey area 

confirm no peat within 50m of turbine. See 

restricted by fallen 

trees 

Figure 3.6 in Appendix 3. 

2007 Yes. Access to parts Yes Field survey results suggest that NW of the 

of survey area 

survey area is free of peat deposits, while the 

restricted due to 

SW of the survey area includes some shallow 

ground conditions 

(



deposits and 

Number Association underlying bedrock Topography 

7 Wilcocks 2 Glacial till over Slopes gently NW 

Nantglyn Flags to nearest 

mudstone and siltstone watercourse, 60m 

NW. 

8 Hafren Glacial till over 




deposits. Lower 

Nantglyn Flags Group 

mudstone. Peat 

deposit to E. 

10 Hafren/ 

Wilcocks 2 

Glacial till over 



11 Wilcocks 2 Peat and glacial till 

over Nantglyn Flags 


12 Wilcocks 2 Glacial till over 






Slopes gently E 

towards track. 

Nearest 


S 

Slopes gently to 

velley bottom SW, 

nearest 


SW. 

Slopes gently N 

towards 


NW 

Fairly flat, slopes 

very gently to NE. 

Nearest 


north, although a 

thin (40 - 50m) 

riparian strip 

crosses survey 

area in SW/NE 

direction. 

Slopes steeply SE. 

Nearest 


SW. 

Slopes SE. nearest 


SE of turbine 

centre 

Phase 1 

Habitat 

Survey 

Coniferous 

plantation 

Coniferous 

plantation 

Forestry 

crop 

Sitka 

spruce 

Sitka 

spruce 

Heathland Sitka 

spruce 

Coniferous 

plantation 

Coniferous 

plantation 

Coniferous 

plantation 

Coniferous 

plantation 

Sitka 

spruce 

Sitka 

spruce. 

Open 

area/ 

riparian 

zone 

Sitka 

spruce 

Sitka 

spruce 



1956 Yes. Access 

No Survey confirms no peat at turbine location or 

restricted in NW 

crane hardstanding. Small, shallow peat 

corner due to dense 

deposits present towards north and west in 

forestry. 

valley bottom surrounding the watercourse. See 

Figure 3.11 in Appendix 3 for exact location of 

identified peat. 

1972 Yes No BGS/NSRI map data and peat depth survey 




confirm no peat within 50m of turbine. BGS 

mapped peat deposit approximately 55m east of 

turbine does not extend into turbine micrositing 

zone. See Figure 3.13 in Appendix 3. 

1998 No - not accessible Desk study 

suggests 

no peat 

BGS/NSRI map data suggest no peat 

1998 Yes. Access restricted 

due to dense forestry. 


suggests 

no peat 

Yes Limited access to survey area due to dense 

forestry. Measurements taken confirm presence 

of peat up to 1.27m to W of original turbine 

location. As a result, turbine has been relocated 

as far as possible E, but still located on the edge 

of shallow peat. See Figure 3.14 in Appendix 3 for 

detailed peat survey results. 



confirm no peat within 50m of turbine. Peat 

depths up to 0.7m recorded along southern 

edge of survey area, in flat and waterlogged 

collection area for nearby watercourse. See 

Figure 3.15 in Appendix 3.


Phase 1 

Turbine NSRI Soil deposits and 

Habitat Forestry Plant Field Survey Peat 

Number Association underlying bedrock Topography Survey crop year Completed present Results 

14 Wilcocks 2 Glacial till over Slopes gently Coniferous Sitka 1990 No - not accessible Desk study BGS/NSRI map data suggest no peat 

Nantglyn Flags towards S, nearest plantation spruce 

suggests 

mudstone and siltstone watercourse 60m 

SW 

no peat 

15 Hafren No superficial Slopes NE, nearest Coniferous Sitka 1995 No - not accessible Desk study BGS/NSRI map data suggest no peat 

deposits. Nantglyn watercourse 190m plantation spruce 

suggests 



NE 

no peat 

16 Hafren No superficial Slopes gently NE, Coniferous Sitka 1990 No - not accessible Desk study BGS/NSRI map data suggest no peat 

deposits. Nantglyn nearest 

plantation spruce 

suggests 

Flags mudstone and watercourse 345m 

no peat 

siltstone bedrock. N 

17 Hafren Glacial till over Slopes NE. Coniferous Sitka 2000 No - not accessible Desk study BGS/NSRI map data suggest no peat 

Nantglyn Flags Nearest 


suggests 

mudstone and siltstone watercourse 155m 

NW. 

no peat 

18 Hafren No superficial Slopes E. Nearest Coniferous Sitka 1990 No - not accessible Desk study BGS/NSRI map data suggest no peat 

deposits. Nantglyn watercourse 700m plantation spruce 

suggests 



S 

no peat 

19 Hafren No superficial Slopes gently Coniferous SS/NS 2002 Yes. No access to Yes Area SW of turbine location surveyed as no 

deposits, but peat southwards plantation 

turbine location itself. 

access to turbine itself. Peat depth up to 2.2m 

deposit 60m S of towards the 

Area 150m SW 

found in area marked on BGS map. Peat found 

turbine centre. nearest 

surveyed to confirm 

to extend further NW than edge of BGS marked 


presence and extent 

deposit, approx 100m further extent, although 

S 

of BGS peat deposit. 

becomes progressively shallower with distance 

from BGS marked deposit (see Figure 3.16 in 

Appendix 3). Considered likely that peat 

deposits in the turbine area may also extend 

beyond the BGS marked deposits to the south. 

20 Hafren No superficial Slopes SE, nearest Coniferous Sitka 1994 No - not accessible Desk study BGS/NSRI map data suggest no peat 

deposits. Nantglyn watercourse 400m plantation/h spruce 

suggests 



SE 

eathland 

no peat 

21 Hafren No superficial Slopes SE, nearest Coniferous SS/NS 1994 No - not accessible Desk study BGS/NSRI map data suggest no peat 

deposits. Denbigh grits watercourse 500m plantation 

suggests 

mudstone, siltstone 

and sandstone 

SE 

no peat


Phase 1 

Turbine NSRI Soil deposits and 

Habitat Forestry Plant Field Survey Peat 

Number Association underlying bedrock Topography Survey crop year Completed present Results 

22 Hafren No superficial Slopes S, nearest Coniferous Sitka 1994 Yes. Access restricted No Turbine centre not accessible due to forestry. 

deposits. Denbigh grits watercourse 200m plantation/ spruce 

due to dense forestry 

Measurements to south of survey area show no 

mudstone, siltstone S 

heathland 

in centre and N of 

peat. See Figure 3.17 in Appendix 3. 

and sandstone 

turbine. 

23 Hafren No superficial Slopes NE, nearest Coniferous Sitka 1992 No - not accessible Desk study BGS/NSRI map data suggest no peat 

deposits. Denbigh grits watercourse 375m plantation spruce 

suggests 


and sandstone 

N 

no peat 

24 Wilcocks 2 Glacial till over Slopes steeply Coniferous Sitka 1993 No - not accessible Desk study BGS/NSRI map data and steep topography 

Denbigh grits NW, nearest plantation spruce 

suggests suggest no peat 

mudstone, siltstone watercourse 150m 

no peat 

and sandstone. Peat 

deposit 105m NW of 

turbine centre. 

N 

25 Wilcocks 2 No superficial Flat, nearest Heathland Open n/a Yes No BGS/NSRI map data and peat depth survey 

deposits. Denbigh grits watercourse 600m 

heathland 



and sandstone 

N 


26 Wilcocks 2 No superficial Slopes N steeply, Heathland Open n/a Yes No BGS/NSRI map data and peat depth survey 

deposits. Denbigh grits nearest 

heathland 


mudstone, siltstone watercourse280m 


and sandstone N 

27 Wilcocks 2 Glacial till over Flat, nearest Coniferous Sitka 1996 No - not accessible Desk study BGS/NSRI map data suggest no peat 

Denbigh grits watercourse 430m plantation spruce/ 

suggests 

mudstone, siltstone SE 

Norway 

no peat 

and sandstone. 

spruce 

28 Hafren Glacial till over Slopes NW, Coniferous Sitka 1998 No - not accessible Desk study BGS/NSRI map data suggest no peat 

Denbigh grits nearest 


suggests 


no peat 

and sandstone. S 

29 Hafren Glacial till over Slopes gently SW, Coniferous Sitka 1996 No - not accessible Desk study BGS/NSRI map data suggest no peat 



suggests 


no peat 

and sandstone. SW 

30 Brickfield 1 Glacial till over 

Denbigh grits 


and sandstone. 

Slopes steeply SW, 

nearest 


W 

Coniferous 

plantation 

Sitka 

spruce 


suggests 

no peat 

BGS/NSRI map data suggest no peat


deposits and 

underlying bedrock Topography 

Phase 1 

Habitat 

Survey 

Coniferous 

plantation 


Number Association 

31 Hafren No superficial Slopes gently W, 

deposits. Denbigh grits nearest 


and sandstone W 

32 Brickfield 1 Glacial till over Slopes steeply SE, Coniferous 


plantation 


and sandstone. SE 

Forestry 

crop 

Sitka 

spruce 




suggests 

no peat 


SS/NS 1991 No - not accessible Desk study 

suggests 

no peat 

BGS/NSRI map data suggest no peat

3.2.3 Access Tracks 

Figures 3.4 and 3.5 show the results of peat probing undertaken along the sides 

of existing and proposed access tracks. Table 3.3 below details the sections of 

track where peat was recorded during the field survey, as well as those 

inaccessible sections of track which, based on the results of the desk-based 

survey, are likely to be located within peat deposits. 

The results show there are seven sections of track where peat deposits have 

been identified. In two of these cases it has been established that any road 

widening requirements and cable routes can be designed to avoid any impact 

on the peat deposits. In the remaining five cases it is considered likely that it 

may not be possible to avoid the identified peat deposits due to other existing 

constraints. 

Calculations of the total area of peat that will be lost directly, and indirectly, as 

a result of construction of these access track sections and cable routes are 

presented in Section 3.2.4. 

ENVIRONMENTAL RESOURCES MANAGEMENT NPOWER RENEWABLES LTD 

19

Table 3.3 Existing and new access tracks in close proximity to peat deposits 

Track 

Section 

Existing 

access track 

to Turbine 1 

and 

northern 

substation 

Access track 

to Turbine 4 

Public road 

section 

between 

Turbine 7 

spur and 

Turbine 5 

spur 

Length 

of track 

surveyed 

NSRI soil 

Association 

BGS superficial 

deposits and 

underlying 

(m) 

bedrock 


Elwy formation 


and sandstone 


deposits and peat 

deposits over 


mudstone and 

siltstone bedrock 

200 Wilcocks 2 River terrace 

deposits and 

alluvium over 


mudstone and 


Topography Phase 1 

habitat 

survey 

Mostly flat, 

slopes gently 

downwards to 

N 

Coniferous 

plantation to S 

and E of track 

Heathland 

elsewhere. 

Flat Coniferous 

plantation to 

N. Scrub and 

recently felled 

to S. 

Slopes 

downwards 

from N and S 

to valley 

bottom and 

watercourse 

Coniferous 

plantation to 

E and W. 

Small area of 

marshy 

grassland to E 

near 

watercourse. 

Field Survey 

Completed 

Yes. Probing 

undertaken to both 

sides of existing access 

track at 5m and 15m 

from track edge. 

Yes. Probing 



track where access 

allowed. 

Yes. Probing 


sides of public road, 

adjacent to road (5m) 

only due to access 

constraints. 

Results Potential peat avoidance 

measures 

No peat deposits along 

majority of track. Three 

records of >0.5m peat depth 

to E of existing track, along 

60m stretch approximately 

100m N of Turbine 1 (see 

Figure 3.6 in Appendix 3). 

Small peat flush associated 

with watercourse to the NE. 

Peat degraded as adjacent to 

existing track and afforested. 

Desk study suggests existing 

access track crosses 

approximately 125m of peat 

to E of Turbine 4. Field 

survey did not identify any 

peat along sides of track. 

No peat deposits along 

majority of road. Two 

records of >0.5m peat depth 

along 50m stretch to W of 

road adjacent to watercourse 

at valley bottom. See Figure 

3.21 in Appendix 3. 

Existing track N of Turbine 1 

may require widening to 

accommodate transformer 

delivery to the substation. 

Cables require to be routed 

along the E of existing track 

due to forestry felling 

constraints and to reduce 

cable/track crossover. No 

available peat avoidance 

options for cable route. 

Any road widening and 

underground cables required 

will be routed along N of 

track to reduce any indirect 

impact on known peat deposit 

to S of Turbine 4 

The land to the E of the public 

road is not owned by FCW 

and is therefore not available 

for use. An existing electricity 

cable also runs along the E of 

the road. Cables will 

therefore be required to be 

routed along the W of the 

public road for legal reasons. 

No peat avoidance options for 

cable route. 

Residual 

loss of 

peat 

60m 

length to 

E of 

existing 

track 

None 

50m 

length to 

W of 

public 

road

Track 

Section 

Existing 

access track 

to W of 

Turbine 11 

Adjusted 

access track 

corner to S 

of Turbine 

11 

Access track 

junction 

between 

turbines 22, 

23 and 26 

New access 

track section 

at junction to 

Turbine 26 

Length 

of track 

surveyed 

NSRI soil 

Association 

BGS superficial 

deposits and 

underlying 

(m) 

bedrock 

450 Wilcocks 2 Glacial till and peat 

deposits over 


mudstone and 


100 Wilcocks 2 Glacial till and peat 

deposits over 


mudstone and 



deposits, glacial till 

and peat deposits 

over Denbigh grits 


and sandstone 

50 Wilcocks 2 Peat deposits over 

Denbigh grits 


and sandstone 

Topography Phase 1 

habitat 

survey 

Slopes gently 

N 

Slopes gently 

N 

Slopes 

downwards 

from W and E 

to depression 

around 

watercourse 

near junction 

Slopes down 

to N 

Coniferous 

plantation 

Coniferous 

plantation 

Heathland, 

marshy 

grassland and 

coniferous 

plantation 

Coniferous 

plantation 

Field Survey 

Completed 

No. Access 

constrained due to 

dense forestry. 

No. Access 

constrained due to 

dense forestry. 

Yes. Probing 



track where access 

allowed 

Yes. Probing 

undertaken along 

proposed route of 

access track 

Results Potential peat avoidance 

measures 

Desk study suggests existing 

access track crosses edge of 

peat deposit approx 90m in 

length on both sides of track. 

Probes in south of deposit 

suggest peat

3.2.4 Peat Loss Calculations 

Direct and indirect loss of peat as a result of construction has been calculated 

based on the survey results outlined in Section 3.2.2 and 3.2.3 above and using 

the methodology outlined in Section 2.4. 

To facilitate calculation of indirect loss due to drainage, the extent of drainage 

has been estimated based on the observed ground conditions in the 

development area and published research. Artificial drainage can result in a 

reduction in the level of the water table within peat deposits, which in turn 

may lead to a loss of habitat structure and loss of carbon from the 

accumulated peat. The reduction in water level will be greatest closest to the 

drainage feature and will decrease rapidly with distance, depending on 

hydraulic conductivity. The Scottish Government (1) guidance gives a range of 

drainage extent of between 1.5m and 50m depending on hydraulic 

conductivity. For the scheme in question it is considered that, as the peat on 

site has already been substantially modified by forestry activities (such as tree 

planting, installation of drainage and deep ploughing) the water table will 

already be significantly lowered within the peat and is unlikely to be further 

affected by the majority of construction works, except for deep excavations (eg 

for turbine foundations). A maximum extent of drainage of 15m has therefore 

been used in the calculations of indirect loss, based on research undertaken in 

a drained, tree-covered bog in Quebec (2) . 

Table 3.4 shows the total area and volume of peat that will be lost directly and 

indirectly as a result of the scheme, broken down per infrastructure 

component located within, or in close proximity to, an identified peat deposit. 

It should be noted that the exact locations of crane hardstanding areas, road 

widening requirements and cable routes will not be confirmed until the 

detailed design stage, and the turbine locations will have a mirco-siting 

allowance of up to 50m. The routing of spur roads to the final turbine position 

will also be determined during detailed design. As a precautionary approach, 

the peat loss calculations have therefore assumed the maximum possible 

encroachment of infrastructure within identified peat deposits, in order to 

provide a reasonable ‘worst case’ estimate of total peat loss. 

(1) Nayak, D.R., Miller, D., Nolan, A., Smith, P. and Smith, J. (2008). Calculating carbon savings from wind farms on 

Scottish peat lands - a new approach. Scottish Government, June 2008. 

(2) Prevost, M., Belleau, P. and Plamondon, A.P. (1997). Substrate conditions in a treed peat land: Responses to drainage. 

Ecoscience 4, 543-544. 


22

Table 3.4 Peat Loss Calculations 

Infrastructure 

component 

Calculation details 

Turbine 2 Total turbine and hardstanding 

construction area 60 x 40m, of which 

up to 40 x 40m may be located 

within shallow (

Infrastructure 

component 

Access track 

junction 

between 

turbines 22, 

23 and 26 

New access 

track section 

at junction to 

turbine 26 

Total area (m 2) 

Total area (ha) 

Total volume (m 3) 

3.2.5 Summary of Results 

Calculation details 

Approx 200m of existing track 

through peat deposit, no widening 

required. Up to 7.1m width for up to 

four cable arrays to south of track. 

7.1m total width. Peat max 1.5m 

deep. 

Approx 30m of new track, half of this 

overlaps with cable arrays route 

described above, therefore 15m 

additional length of track through 

peat deposit up to 1.5m deep. Road 

up to 10m wide on corner. Plus 7.1m 

width for up to four cable 

arrays.17.1m total width 

Direct loss by 

excavation 

Area 

(m 2) 

Volume 

(m 3) 

Indirect loss 

through drainage 

impacts 

Area 

(m 2) 

Volume 

(m 3) 

1420 2130 3000 4500 

256.5 384.75 450 675 


24 

8533 

0.85 

9371.25 

13020 

1.30 

14745 

The peat survey results for Clocaenog Forest Wind Farm can be summarised 

as follows. 

• The desk study identified localised peat deposits along the valley of Nant 

Llyfarddu watercourse in the south of the development area, and in 

smaller pockets in the north and west of the development area, shown on 

BGS superficial geology maps of the area. 

• NSRI soil map data suggested that the Wilcocks 2 soil association, 

covering parts of the development area especially in the north, may 

contain soil series with an important peat element (namely the Crowdy 

and Winter Hill soil series). 

• Cross reference of available data sources found good correlation between 

the BGS mapped peat deposits, peaty soil types and suitable topography 

for peat accumulation. 

• The Phase 1 habitat survey did not identify any areas of mire habitat 

within the development area suggesting that, although there may be peat 

deposits beneath the coniferous plantation forest and heathland habitat, 

the site does not currently hold active peatland habitat (ie there are no 

areas characterised by their peat-forming vegetation). Peat deposits 

within the development area should therefore be considered valuable in 

terms of their existing carbon stores, rather than as active peatland habitat.

• Field surveys were undertaken at all accessible turbine locations to 

confirm the findings of the desk study and to identify any additional peat 

deposits. Out of the 14 turbines surveyed, peat was only found in close 

proximity to four turbines. The results also showed generally good 

correlation with the desk-based study, with one additional localised peat 

deposit identified through the field survey at Turbine 2. Based on the 

results of the desk-study and field survey, it is considered unlikely that 

peat deposits will be present at the remaining 18 turbine locations, 

although check surveys should be undertaken following felling to confirm 

this. 

• Peat probing undertaken along existing and proposed access tracks 

located within the Wilcocks 2 soil association shows good correlation with 

the desk study results. Four sections of existing track (totalling 400m in 

length) and two sections of new track (totalling 60m in length) are located 

within identified peat deposits. 

• The total direct loss of peat resulting from construction of the wind farm 

has been calculated to be an area of approximately 0.85ha, with a total 

volume of 9371.25m 3 peat. 

• The total indirect loss as a result of drainage has been calculated to be an 

area of approximately 1.30ha, with a total volume of 14,745m 3 peat. 

• It should be noted that the exact locations of crane hardstanding areas, 

road widening requirements and cable routes will not be confirmed until 

the detailed design stage, and the turbine locations will have a mircositing 

allowance of up to 50m. The routing of spur roads to the final 

turbine position will also be determined during detailed design. As a 

precautionary approach, the peat loss calculations have therefore assumed 

the maximum possible encroachment of infrastructure within identified 

peat deposits, in order to provide a reasonable ‘worst case’ estimate of 

total peat loss. In some case, it may be possible during detailed design to 

further micro-site the turbines and associated infrastructure to avoid 

encroaching into peat deposits. Section 4 below outlines the recommended 

mitigation measures to ensure there is no additional loss of peat from the 

scheme and, where possible, to reduce the loss reported above. The 

significance of peat loss in terms of its value as a resource is considered 

further in Chapter 8 of the ES. 


25

4 RECOMMENDED MITIGATION MEASURES 

4.1 INTRODUCTION 

In order to minimise the potential direct and indirect peat loss resulting from 

the scheme, the following mitigation measures should be incorporated into 

the site layout and design, and will be implemented during construction. 

4.2 PRE-CONSTRUCTION SURVEYS 

Peat depth check surveys should be undertaken at the remaining 18, currently 

inaccessible, turbine locations following tree felling and prior to 

commencement of construction, to confirm the results of the desk-based study 

and locate any previously unidentified peat deposits in close proximity to 

turbine locations. 

4.3 MICRO-SITING CONSIDERATIONS 

Site infrastructure, including turbine foundations, crane hardstandings, access 

tracks and cable routes, will be micro-sited to avoid identified peat deposits 

where possible. For example, turbine locations will have a 50m micro-siting 

allowance and may be able to be relocated outwith identified peat deposits. 

Similarly, crane hardstandings can be orientated to minimise their direct and 

indirect impact on peat. The routing of spur roads will depend on the final 

turbine location and will be designed to avoid peat deposits where possible. 

Where possible, access tracks will be widened and cable arrays laid on the side 

considered least likely to impact on any nearby peat deposits. 

4.4 CONSTRUCTION GOOD PRACTICE 

Peat deposits in close proximity to site infrastructure will be fenced off during 

construction to avoid vehicles from tracking over and damaging the soft 

ground. 

Dewatering of turbine foundations will be avoided where possible to prevent 

the additional drawdown of water levels in the surrounding soil and peat 

deposits. 

Any peat that is excavated will be placed in areas identified as suitable to 

receive it in order to minimise any permanent loss. These areas may include 

former forest drains, or areas that are wet enough to maintain the hydrological 

integrity of the peat, without damaging any underlying mire vegetation. 


26

Appropriate construction techniques, such as frequent cross drains, will be 

used to ensure hydrological connectivity remains in any areas of peat crossed 

by new access tracks. 


27

Appendix 1 

CCW Consultation

c~_ 

~ 

.... ~ 

Cyngor Cefn Gwlad Cymru 

Countryside Council for Wales 

Cyngor Cefn GwladCymru 

Countryside Council for Wales 

Anfonwch eich ateb atIPlease reply to: Dr David Hatcher 

FfOnffel: 01352 706600 FfacsIFax: 01352 752346 

Gareth Leigh 

BERR 

Energy Group 

1 '1ictoria Street 

London 

SWIH OET 

Dear Gareth Leigh, 

Ebost/Email: d.hatcher@ccw.gov.uk 

Rhanbarth y Gogledd - Swyddfa' r Wyddgrug 

North Region - Mold Office 

Glan y Nant, Uned 19 / Glan y Nant, Unit 19 

Pare Busnes Yr Wyddgrug / Mold Business Park 

Ffordd Wrecsam / Wrexham Road 

Yr Wyddgrug / Mold 

Sir Y Fflint / Aintshire 

CH7 lXP 

Ein cyfi'Our ref: DHlMMJ/SHOI52/1123202 

Eich cyfN our ref: 

SCOPING OPINION FOR WINDF ARMIWIND TURBINE DE'lELOPMENT AT CLOCAENOG FOREST 

25.9.08 

Thank you for your letter of 18 August 2008 seeking the Countryside Council for Wales' (CCW) comments on the 

information that should be included in an Environmental Impact Assessment for the above proposed development. 

Thank you also for agreeing to extend the consultation period. 

In discharging its functions under Section 130 of the Environmental Protection Act 1990 the Countryside Council 

for Wales (CCW) champions the environment and landscapes of Wales and its coastal waters as sources of natural 

and cultural riches, as a foundation for economic and social activity, and as a place for leisure and learning 

opportunities. CCWaims to make the environment a valued part of everyone's life in Wales. 

Please note that our comments are without prejudice to any comments we may wish to make when consulted on any 

subsequent applications or on the submission of a more detailed scoping report or the full Environmental Statement. 

At the time of any application approval there may be new information available which we will need to take into 

account in making a formal response to DBERR. These comments include those matters CCW consider will need to 

be taken into consideration as part of an Environmental Impact Assessment (EIA). 

The EIA for this development should include sufficient information to enable the DBERR to determine the extent of 

any environmental impacts arising from the proposed scheme on protected species and other nature conservation, 

countryside and landscape interests. CCW considers the proposed scope of sections of the document where no 

comment has been made to be acceptable. Our detailed comments on the scoping document are included in the 

attached Annex I. However, we would like to take this opportunity to draw your attention to the following 

comments at the outset:- 

Lywodraeth Cynulliad Cymru ~!t(W-.d- 

Welsh Assembly Sponsored Government by ,.I(. 'Y~ 

Gofalu am natur Cymru - ar y fir ae yn y mar· Caring for our natural heritage - on land and in the sea 

Noddir gan ~~r ~ 

. Prif Swyddfa/Headquarters 

MAES-Y-FFYNNON, PENRHOSGARNEDD, BANGOR ll57 2DW FFONfTEl: 01248385500 FFACS/FAX: 01248355782 

http://www.ccw.gov.uk

CCW are of the view that the impacts of grid connections and transport links should be 

covered in the EIA for the proposed development as they both have the potential for 

significant impacts on landscape and nature conservation interests beyond the boundary of the 

proposed development and outside Strategic Search Area A. 

Appendix 1 of the scoping document outlines the Proposed Development Area Boundary for 

the scheme. However CCW is aware that part of this area has also been reserved as a 

mitigation/compensation area in relation to another wind farm development under a 'Planning 

Obligation by Unilateral Undertaking'. We advise the boundary for the proposed scheme be 

checked for any errors. 

If you would like to discuss any aspect of this response, please do not hesitate contact me. 

Yours sincerely 

Dr D R Hatcher 

North Region Casework Officer 

Casewrok Team 

Ene!. Annex I: CCW Scoping advice for Clocaenog Forest Wind Farm 

Rosemary Thomas - Welsh Assembly Government 

Ro Loveland - Welsh Assembly Government

ANNEX I: THE COUNTRYSIDE COUNCIL FOR WALES' (CCW's) SCOPING ADVICE 

FOR AN ENVIRONMENTAL IMPACT ASSESSMENr (EIA) FOR THE PROPOSED 

WINDFARM AT CLOCAENOG FOREST 

GENERAL COMMENrS 

The Environmental Impact Assessment (EIA) should include sufficient information to enable 

DBERR to determine the extent of any environmental impacts arising from the proposed 

scheme on ecological and landscape interests and the public's access to the countryside. 

Evaluation of the impacts of the scheme should include: direct and indirect; secondary; 

cumulative; short medium and long term; permanent and temporary; positive and negative, 

impacts of the construction operation and decommissioning phases (including those of 

ancillary developments), on the nature conservation resource, landscape and public access. 

COMMENTS ON THE SCOPING OPINION REQUEST 

Please note that the comments below refer to the Clocaenog Forrest Windfarrn - EIA Scoping 

Opinion Request, Reference No. NRL/OOI/BAG. CCW considers the proposed scope of 

sections of the document where no comment has been made to be acceptable. 

Ancillary Development 

These comments are generally confmed to Sections 5 and 6 of the submitted document (Ref 

NRL/OOI/BAG) which specifically relate to a proposed scoping opinion request. However, 

we note that in Section 4, Description of the Wind Farm, in paragraph 4.3.8 Grid Connection 

it is stated that "The Environmental Statement will contain as much information as possible 

regarding the grid connection, such as the grid connection point and a possible route 

corridor ... ". 

CCW considers the connection to the National Grid to be an ancillary development. While the 

grid connection may be constructed and operated by a different developer and could be 

assessed as a separate project, it is inextricably linked to the original project. The cumulative 

impacts of the project and its ancillary developments could potentially be significant. If an 

ancillary development is not included in the assessment, the Environmental Statement may 

not identify silch a degree of adverse impact and would therefore not fully reflect the 

environmental impacts of the whole project. If insufficient information is available to allow 

an assessment, this should be reported in the Environmental Statement to ensure that it is 

considered as part of the decision-making process. 

Other types of ancillary development that should be considered where possible in the 

Environmental Assessment, be they on or off site, include: access roads, electricity substations, 

quarries or borrow pits for the supply of materials, construction compounds and 

disposal sites. 

Failure to consider the impacts of ancillary development linked to this proposed development 

is likely to render the EIA incomplete as it will not have considered all associated impacts of 

the proposal. 

Proposed Development Area 

Part of the land in Appendix 1 shown as being within the Proposed Development Area 

Boundary forms part of a mitigation or compensation area, established in relation to the Tir 

Mostyn and Foel Goch Windfarrn Development under a 'Planning Obligation by Unilateral

Undertaking'. Within this document the developer is obliged to undertaken various measures 

that include habitat enhancements and monitoring programmes within the area concerned. 

We therefore ask whether the boundary indicated is correct as to undertake the proposed 

development at this location would appear to breach a covenant to which the local planning 

authority and the National Assembly for Wales, among others, are signatories? 

Section 5.1 The Environmental Statement 

The topic Ecology and Ornithology: this implies that only ecology and ornithology are to be 

considered under this heading. If other species or species groups are to be considered here we 

feel it would be better to change the title to something more inclusive such as Ecology and 

Wildlife. 

A section entitled Grid Connection could be included here or it could be a sub-heading under 

a Ancillary Development title. 

Section 6.4 Landscape and Visual 

Para 1 - This states that the Mynydd Hiraethog SSSI is a landscape designation - this is 

incorrect. We wondered if this was a reference to the Denbigh Moors Landscape 

Conservation Area as identified in the Hobhouse Report Cmd 7121 (1947). 

Section 6.6 Ecology and Ornithology 

As stated above in relation to Section 5.1 we suggest that this title is changed to encompass 

other species groups 

Non-statutory Nature Conservation Sites - The EIA should consider the potential effects of 

the proposed development on sites of local or regional nature conservation importance. Full 

details about the location, extent and nature conservation interest of such sites may be 

obtained ITom the local planning authorities. 

If non-statutory nature conservation sites are likely to be affected by the proposed 

development, the Environmental Statement should include all of the measures that will be 

implemented to ensure that there will be no overall loss of the local nature conservation 

resource 

Vegetation / Habitats: We would prefer to see a reference to 'Habitat of conservation interest' 

rather than 'More interesting habitats' 

Peat/Peatlands: Either in this section or in Section 6.8, under a heading such as Soils or 

Geomorphology, there should be a section on peat and/or peatland habitats. CCW has some 

low definition mapping information indicating that peat and remnants of peatland habitat are 

likely to be present within the proposed development boundary under the existing forest 

vegetation. 

CCW regards potential damage to peat or peatland habitats as a key issue. Peat is an essential 

substrate for certain plant communities but forms very slowly, perhaps lcm in 10 years 

(peatlands, http://www.peatlandsni.gov.uklformation/index.htm. © Crown copyright 2004), 

so any loss is difficult to mitigate. 

Peat is also known to be a carbon 'sink', therefore as general guidance, CCW recommends 

that developers should outline measures which, by aiding more extensive or substantial peat 

accumulation, demonstrably offset all losses resulting from the development, and furthermore

that these are 'climate-proofed' for the life of the windfarm. A methodology for quantifying 

carbon loss (and any carbon gain resulting from habitat mitigation) was published by the ! 

Calculating Carbon Savings from Wind Farms on Scottish Peat Lands - A new Approach. 

Scottish 

Wales. 

Executive, Government June (Nayak, 2008.). D.R., ThisMiller, processD., should Nolan, be A., undertaken Smith P. for& all Smith applications J. (2008). in \ 

Development on and around peat has the potential to cause direct damage through disturbance 

or indirect damage through the effects of changes to hydrology. This may lead leading to 

drainage and drying out which would allow the peat to oxidise and decay. 

We are developing some general guidance for assessing the impact of windfarm 

developments on peatland habitats in Wales and will send a copy of this to you when details 

have been finalised. In the mean time we would advise that the EIA should be based on any 

existing information, such as Cranfield University's national soils data, with a further 

comprehensive survey concerning the extent, depth and condition of peat deposits across the 

site. Peat depth maps showing the extent and depth of peat deposits should be produced so 

that they can overlay Phase 1 habitat survey maps. We recognise that there is uncertainty as to 

how some of these issues are best investigated and their impacts quantified. We would 

therefore welcome the opportunity to discuss this with if necessary. 

In general, we would expect that disturbance and/or destruction of peat would be avoided as 

far as possible, and where it was not possible, such impacts would be minimised. We would 

also recommend that opportunities to halt the deterioration of existing degraded peat and/or to 

restore active peat forming vegetation are exploited as part of a strategic environmental 

management plan for the site. 

We would also draw to your attention that mire habitats are also likely to be encountered 

within the proposed development area. 

Fauna 

With regard to specific species, in addition to those mentioned clarify and to survey methods 

proposed we would add: 

Red Squirrels - We consider that the main issue here is not where the squirrels are, but 

understanding the impact the turbines will have on the viability of the population taking into 

account cumulative impacts over the longer term and also the impact on connectivity across 

the site. 

Pine marten - the Vincent Wildlife Trust Survey (please contact CCW for further details) 

didn't identify any positive scats at this location, but wasn't undertaken in ideal conditions and 

therefore is not definitive. We therefore recommend that surveyors of this site collect any 

likely scats and, if necessary to give adequate site coverage, undertake transects specifically 

for such scats, so that they can be identified by DNA analysis. 

Common Toad - No reference is made to this species but is needs to be considered in the ES. 

Reptiles - Their presence is a material planning issue. We therefore suggest that the scope of 

the ES includes assessments of reptile species likely to be affected. 

Water voles - We can confirm that we are aware of upland water vole populations within and 

in the environs of Clocaenog. 

Badgers - Sett and bait marking surveys will be required.

Section 42 and LBAP Species/Habitats - In addition to the species and habitats mentioned 

above and in your proposal, consideration should also be given to any species listed under 

Section 42 of the Natural Environment & Rural Communities Act 2006 or included within the 

Local Biodiversity Action Plans of Denbighshire and/or Conwy councils 

Bats 

Research indicates that bats are affected by wind turbine developments and the re is 

increasing evidence that a number of bat species are present at upland sites. We would refer 

you to Natural England's interim guidance on 'Bats and Onshore Wind Turbines' (May 

2008) and the Eurobats guidance. Therefore, we recommend that desk studies and field 

surveys are undertaken to establish: 

The presence of roosts within the development site and within 2km of the development site; 

The significance of any roosts identified within the development site and within 2km of the 

development site; 

Whether there are any key bat flight lines from roosts within 2km of the development towards 

the development site; and 

Bat flight-lines through the development site and bat foraging areas within the development 

site. 

M.\.~~e.~C). fo\' blits should be carried out in accordance with 'Bat Surveys: Good Practice 

Gcid~k~~~~~~~~~~~~~-=-'-="==~~--~~ 

conditions (ie. avoiding cold, wet and windy weather). Survey methodology used must 

provide a good baseline and be repeatable in post-development monitoring. 

Activity surveys should identify specific species and record flight behaviour, the height above 

ground that observed bats were seen, and the proximity of observed bats to landscape features 

used as commuting corridors. Frequency division and time expansion equipment must be 

used. 

Weare aware that there are buildings that could accommodate bats in Clogaenog. FC have 

also bat boxes within Clocaenog Forest and these need to be considered as well as possible 

sites in the surrounding area. 

Bats and their roosts are legally protected under the Habitats Regulations 1994 (as amended). 

Developments likely to compromise the legal protection afforded bats will invariably require 

a licence from the Welsh Assembly Government to do so lawfully. Further details about the 

legislation afforded bats (a European Protected Species) and the relevant licensing provisions 

are provided in Appendix 1. 

If bats or their roosts are likely to be affected by the proposed development, the 

Environmental Statement will need to include comprehensive details of the all the mitigation 

that will be put in place to maintain the favourable conservation status of the population(s) 

concerned. This should follow guidance provided in English 

rd 

Nature's 'Bat Mitigation 

Guidelines' (2004) and JNCC's 'Bat Worker's Manual' (3 Edition, 2004). 

ADDITIONAL INFORMATION REQUIRED 

Further information is required on the following aspect of the proposed development

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

Land take requirements and other physical features of the project including 

site layout 

Procedures for good working practices; 

Resource use, including waste, minerals and energy; 

Identification of appropriate pollution contingency and emergency measures; 

Timing of all works and contingency plans should slippage in the programme 

occur; 

Details of construction works including methodology, location and extent of 

construction sites, construction access/working corridors and stock piling 

sites; 

Quantity and content of any discharges from the development site; 

Details of the disposal of any surplus material e.g. material displaced from 

constructing bases or access roads. 

Maintenance requirements of structures. 

Maintenance of any habitats within the site; 

Details of all ancillary developments 

POTENTIAL MITIGATION AND ENHANCEMENT MEASURES 

With respect to nature conservation interests that could be affected by the scheme, it is only 

possible at this stage to advise on general mitigation measures. We would welcome the 

opportunity to discuss this issue in greater detail as the scheme progresses. In order of 

priority, the scheme should seek to: 

i. avoid damage to interests within the area that will be affected by the proposed 

development; 

ii. mitigate any damage that cannot be avoided; and 

iii. compensate for any unavoidable damage that cannot be mitigated for. 

The Environmental Statement should include a detailed description of all the measures that 

will be implemented to avoid, mitigate and if necessary, compensate for any significant 

adverse effects on the environment. These measures should be relevant and proportionate to 

the nature and scale of the likely adverse impacts. Such measures could include ensuring that 

disposal of any excavated soil/rock is not stored or spread over sensitive habitats, the micro 

siting of turbines, moving location of access roads, and changing the timing of construction to 

avoid sensitive periods for species (Eg. breeding season). 

With reference to Strategic Search Areas, TAN 8 states that: 

• 'there could be opportunities to enhance, extend or re-create habitats of wildlife and 

landscape interest. These opportunities should be grasped' . 

• 'With such extensive application sites there will very often be opportunities for 

developers to mitigate for any potential ecological damage and preferably enhance 

current wildlife habitats' 

CCW will seek site enhancements for biodiversity; proposals for biodiversity enhancements 

within the Environmental Statement may be accepted prior to determination but must be a 

statement of intent for measures that will be implemented. This should include broad 

statements/prescriptions on habitat enhancements for restoration of individual habitats in 

poor/degraded condition and proposed enhancements to benefit protected and/or priority 

species. 

MONITORING AND SURVEILLANCE DURING AND POST CONSTRUCTION

We recommend the inclusion of details of a monitoring programme covering all protected 

species affected by the scheme relating to both construction and operational phases of the 

development. 

Monitoring must be linked to appropriate contingency plans. It may be necessary to amend 

construction procedures if the monitoring programmes identify adverse impacts linked to 

construction or post construction activities and CCW would wish to be consulted in such an 

event. Scottish Natural Heritage (SNH) is in the process of developing generic guidance on 

this subject. 

WIDER ISSUES 

Cumulative impacts 

In assessing the potential impacts of the proposed development on ecological and landscape 

interests, the EIA should consider the potential cumulative impacts of this wind energy 

development along with: 

• Other wind energy developments in the area that already exist or have planning 

permission; and 

• Proposals for other wind energy developments in the area that are in the public 

domain (ie. those that are presently under consideration in the planning system). 

We would refer the developer to DBERR (Gareth Leigh) and the Denbighshire and Conwy 

planning authorities for comprehensive information in this respect. 

Recreational interests 

The EIA should address key recreational users that use any public rights of way (public 

footpaths, bridleways etc) including any nationally recognised and local routes that traverse 

the application site or land near to it. The EIA should take regard to TAN 8 with respect to 

distance from turbines to public rights of way (Appendix C, para 2.25-2.27). 

With regards to bridleways, horse riders and wind turbines, the British Horse Society 

Guidance recommends a minimum of 200m separation between turbines and bridleways, with 

ideally 3 times the height of the turbine separation. 

We would recommend that you liaise with the Public Rights of Way officers at Denbighshire 

and Conwy councils regarding public rights of way and the potential impacts of this proposal 

on local routes. 

Co-operating with other windfarm developers in the area 

As there are other proposals for windfarm developments in the area, we would strongly 

encourage the developer and their advisers to work with the developers (and their advisers) of 

these others proposals in obtaining and sharing survey information, designing layouts, 

providing sufficient information about cumulative impacts, and developing surveillance and 

monitoring plans for construction and operational phases of the development. 

In our view, a collaborative approach would be the most effective way of developing 

comprehensive and coherent surveillance and monitoring plans for the construction and 

operational phases of several adjoining wind farms. A collaborative approach may also 

reduce costs (Eg. of surveys and monitoring) and assist in progressing applications through 

the planning system (Eg. by ensuring that sufficient information accompanies each 

application).

Period between planninl? pennission and commencement of construction works 

If several years may elapse between the granting of planning pennission and the 

commencement of construction works, we would recommend that appropriate ecological field 

surveys are undertaken during this period to repeat and update those undertaken to inform the 

EIA and inform the developer of any change of circumstances, for example, with respect to 

protected species. We recommend that this aspect is covered in the Environmental Statement 

for the proposals. 

Deviation from policy 

If the proposed development will deviate from national and/or local policy, full justification 

should be provided for this deviation in the Environmental Statement.

APPENDIX 1: 

EUROPEAN PROTECTED SPECIES - LEGISLATIVE PROTECTION 

European Protected Species include: 

• Great crested newt (Triturus cristatus) 

• Common otter (Lutra /utra) 

• all British bats 

The animals themselves and the places they use to rest and breed are legally protected under 

the Wildlife and Countryside Act 1981 (as amended) and the Conservation (Natural Habitats 

&c.) Regulations 1994 (as amended) - known as the Habitats Regulations 1994 (as amended). 

Under Regulation 39 of the Habitats Regulatisns (as amended): 

A person commits an offence if he or she 

(a) deliberately captures, injures or kills any wild animal of a European protected 

speCIes; 

(b) deliberately disturbs 1 animals of any such species in such a way as to be likely 

significantly to affect i) - the ability of any significant group of animals of that 

species to survive, breed, or rear or nurture their young, or ii) the local distribution or 

abundance of that species; . 

(c) deliberately takes or destroys the eggs of such an animal 

(d) damages or destroys a breeding site or resting place of such an animal 

Under S.9(4)(b) and (c) the Wildlife and Countryside Act 1981 (as amended): 

A person commits an offence if he/she intentionally or recklessly 

• disturbs any such animal while it is occupying a structure or place which it uses for 

shelter or protection; or 

• obstructs access to any structure or place which any EPS animal uses for shelter or 

protection. 

Where the legal protection afforded European protected species under the Habitats 

Regulations is likely to be compromised by a proposed development, the development may 

only proceed under a licence issued by the National Assembly for Wales (NA W). Under 

Regulation 44(1) of the Habitats Regulations, NA W may issues licences for the purposes of: 

'preserving public health or public safety or other imperative reasons of overriding 

public interest including those of a social or economic nature, and beneficial 

consequences of primary importance for the environment. ' 

Furthermore, a licence can only be issued by NA W if the following two conditions are also 

met: 

• That there is 'no satisfactory alternative', and that 

• 'the development will not be detrimental to the maintenance of the population 

of the species concerned at a favourable conservation status in their natural 

range' . 

In addition, regulation 3(4) of the Habitats Regulations 1994 requires all local planning 

authorities in exercise of their functions, to have regard to the provisions of the Habitats 

Directive in so far that they might be affected by those functions. 

1 For further information on this offence, please refer to "Disturbance and protected species: understanding 

and applying the law in England and Wales: A view from Natural England and the Countryside Council for 

Wales." CCW, Bangor 

http://new.wales.gov.uk/depc/ecm/habitats/Disturbance of protected sp 1.pdf?lang=en

APPENDIX 2: LEGISLATION CONCERNING BADGERS 

Badgers and their setts are protected under the Protection of Badgers Act 1992. Legal 

protection makes it an offence to; 

• wilfully kill, injure, take, possess or cruelly ill-treat a badger, or attempt to do so; 

• intentionally or recklessly interfere with a sett. 

Sett interference includes disturbing badgers whilst they are occupying a sett, as well as 

damaging or destroying a sett or obstructing access to it. If the proposed development is 

likely to compromise the legal protection afforded badgers, a licence will be required from the 

Countryside Council for Wales. 

APPENDIX 3: LEGISLATION CONCERNING WATER VOLES 

Water voles receive legal protection under Section 9 of the Wildlife and Countryside Act 

1981 as amended 

• Intentionally kill, injure or take (capture) a water vole; 

• Possess or control a live or dead water vole, or any part of a water vole or anything 

derived from a water vole; 

• Intentionally or recklessly damage, destroy or obstruct access to any structure or 

place which a water vole uses for shelter or protection 

• Intentionally or recklessly disturb a water vole while it is occupying a structure or 

place which it uses for shelter or protection; 

• Sell, offer or expose for sale, or have in one's possession or transport for the purpose 

of sale, any live or dead water voles, or any part of a water vole or anything derived 

from a water vole; 

• Publish any advertisement, or cause any advertisement to be published, which is 

likely to be understood as conveying that a person buys or sells, or intends to buy or 

sell, any of the above things. 

There is no provision for licensing the intentional destruction of water vole burrows for 

development. All reasonable efforts must be made to avoid committing an offence.

CADEIRYDD/CHAIRMAN: JOHN LLOYD JONES OBE PRIF WEITHREDWR/CHIEF EXECUTIVE: ROGER THOMAS 

Anfonwch eich ateb at/Please reply to: Ken Perry Rhanbarth De a Dwyrain / South & East Region 

Ffôn/Tel: 01686 613400/01686 613400 Tŷ Ladywell / Ladywell House 

Ffacs/Fax: 01686 629556 Stryd y Parc / Park Street 

Ebost/Email: k.perry@ccw.gov.uk Y DRENEWYDD / NEWTOWN 

SY16 1RD 

Ms. Heather Eadie Ein cyf/Our ref: Clocaenog WF id 1080139 

Edinburgh Office 

Eich cyf/Your ref: 

Norloch House 

36, Kings Stables Rd 

Edinburgh 

EH1 2EU 23 rd July 2009 

Dear Heather Eadie, 

CLOCAENOG WINDFARM – CCW RESPONSE ON PEAT DEPTH SURVEY OUTLINE 

METHODOLOGY 

Thank you for giving the Countryside Council for Wales (CCW) the opportunity to comment on your 

proposed outline peat depth survey methodology received by e-mail on the 21/7/09 for the proposed 

Clocaenog Windfarm. 

We strongly support your aim of seeking to design the development away from peat features this, in 

CCWs opinion, being one of the prime objectives of such a study, others would include assessment of peat 

stability, hydrological impact and carbon balance. 

In addition to our original scoping advice we provide the response below to steer you at the earliest stage 

as to the level and detail of effort CCW expect from studies aimed at avoiding the impacts of windfarms 

upon peatland bodies. We note that from the studies carried out to date you conclude that the peatland 

habitats are relatively small and distributed in pockets across the site. Annexe I below contains further 

detailed comments in response to your above consultation. 

We are concerned at this stage that the outline peat depth survey methodology does not make any 

reference (beyond avoiding peat) to the following issues, which we consider any peat survey and 

assessment work should cover: 

A clear overall statement of the priority questions that the study will address: Some of which are 

mentioned in our second paragraph above. 

Peat as a design constraint: The study must provide sufficient information to demonstrate how the 

windfarm has been designed to avoid peat. Peat depth survey work must include all areas proposed for 

infrastructure as well as areas beyond where, as a minimum, survey should focus on locations that 

topographically appear suitable for its formation. Peat depth should be recorded to actual depth or the 

Gofalu am natur Cymru - ar y tir ac yn y môr • Caring for our natural heritage - on land and in the sea 

Prif Swyddfa/Headquarters 

MAES-Y-FFYNNON, PENRHOSGARNEDD, BANGOR LL57 2DW FFÔN/TEL: 01248 385500 FFACS/FAX: 01248 355782 


nearest 10cm rather than < or > 0.5m and should also be recorded at habitat boundaries. Bog with ~ 0.5m 

of peat with ericoid or graminoid cover should be recorded as peatland. 

If turbines or infrastructure are proposed on peat a justification should be given as to why it has not been 

possible to avoid this and why alternatives locations were considered unsuitable. Therefore suitable and 

detailed mitigation scheme should be advanced to describe how adverse impacts on peat will be limited 

and avoided. 

Description of impacts: There should be sufficient data to enable calculation of the predicted habitat 

losses and carbon losses and savings (for the full lifecycle of the development) resulting from the project 

we refer you to the Scottish Executive 2008 methodolgy (Nayak et al 2008). The study should provide the 

necessary information required to describe the hydrology, extent, type and quality of any peatland habitats 

which may be damaged/destroyed by the proposed development to include the predicted level of damage. 

Design of mitigation: The study should provide information to enable impacts on peat to be minimized. 

Information will be required on physical characteristics of peat around and beyond turbines or 

infrastructure to assist in the design of any measures to reduce hydrological impacts on peat. Peat depth is 

a useful aid to scoping the need for hydrological assessments. An understanding of the hydrology of the 

peat bodies on site is essential and how the development activities will be likely to impact directly and 

indirectly (including beyond the immediate physical infrastructure footprint) upon the hydrology and peat 

body. It will be necessary to quantify potential impacts and demonstrate them in the impact assessment, 

this information being critical for the mitigation scheme and restoration proposals. 

Compensation and enhancement: The extent and depth of peat should also be assessed across the wider 

site to provide information to support strategic consideration of peatland compensation (restoration and 

enhancement) proposals that will be described in the strategic Habitat Management Plan over and above 

any proposed mitigation. CCW believe such proposals are compliant with para, 2.22, TAN 8 July 2005 & 

Para, 5.2.7 Planning Policy Wales March 2002. These measures should be implemented to compensate for 

direct biodiversity and carbon losses and also for the long term benefit of biodiversity and the mitigation 

of climate change impacts. Predictions should be made for any potential gains in area or quality of 

peatland habitats and on carbon balance. 

Assessments of peatland vegetation and condition: Should be characterised in accordance with NVC 

methodologies and Turner 2006 categorisations to help assess peatland resource and pinpoint areas for 

potential restoration. Habitats referable to blanket bog can occur on shallower peat of 35cm and such areas 

must be included in the impact and restoration assessment process. 

Habitat quality is only one of the criteria that should be used to assess the potential for peatland habitat 

restoration see Table 1 below for the other criteria: 

Table 1: 

Criterion Rationale 





Peat depth Peat depth is some refection of the suitability of a given location for 

peat development (although obviously it also depends on the 

duration of peat accumulation). Deeper peats are likely to be more 

resilient to the effects of drainage, and offer better potential for 

hydrological restoration, not least because of the availability of deep 

humified peat for dam construction. 

Slope Flat or gently sloping expanses of bog offer better and easier 

prospects for hydrological restoration. Such areas are also more 

likely to support pools resulting from the construction of peat dams. 

Size of peat body All things being equal, larger expanses of peat are likely to have 

more potential for developing the natural hydrological and 

ecological functions associated with active (peat-forming) mires. 

They will also be more resilient to climate change. Larger mires 

have more potential for developing/exhibiting a range of microform 

Character of 

existing drains 

types (e.g. pools, hummocks etc). 

Heavily drained areas offer a greater challenge for restoration than 

un- or lightly-drained expanses of bog. Note though that modern 

restoration techniques are effective for even the most heavily 

modified areas. We recommend all drainage ditches are mapped. 

Vegetation cover Within the context of domination by purple moor-grass Molinia 

caerulea, areas of bog supporting oligotrophic species usually 

associated with less modified mires will be of especial significance. 

Two groups of species can be identified; in increasing order of 

conservation importance these are: 

(i) widespread species which indicate acidic perennially wet peats, 

including Eriophorum angustifolium, Scirpus cespitosus, Sphagnum 

fallax, S. subnitens, (ii) species indicative of more strongly 

oligotrophic conditions and stable hydrological regimes, including 

Eriophorum vaginatum, Drosera rotundifolia, Sphagnum 

cuspidatum, S. papillosum, S. capillifolium and S. tenellum. 

The presence of any ericoids (excluding Vaccinium myrtillus) is 

another positive criterion. 

Bog mosses (Sphagna) are of especial indicator value because as a 

group they are easily recognised and also indicative of wet 

conditions. The group I Sphagna are mildly minerotrophic and 

would not usually be regarded as typical blanket bog elements. Their 

relative frequency in south Wales probably reflects past and ongoing 

atmospheric nutrient deposition, and their presence may aid the 

Nature of conifer 

cover (where 

present) 

establishment of more oligotrophic Sphagna 

An open, patchy or stunted conifer canopy may reflect the very 

conditions conducive to bog survival and continued development, 

and will also have resulted in less modification of surface 

vegetation. 





Peat depth surveys must inform the risk assessment for the potential of peat slide and also peat stability. 

It would be sensible to make these assessments in conjunction with peat depth. Peat stability analysis 

should include both blanket and flush peats. Key factors relevant to peat stability are listed below: 

Table 2. 

Factor Significance 

Peat thickness Peat instability is more likely where deposits exceed 1 m 

thickness, although slides on shallower deposits are known. 

Slope Slope provides a gravitational driver for slides. 

Rainfall Intense rainfall can cause significant and relatively rapid 

increases in pore water pressure and this is believed to be a 

Context within peat 

body 

Surface & sub-surface 

hydrology 

significant trigger mechanism for slides. 

Peat at the edge of the main peat body may be especially 

susceptible to movement, especially where adjacent to 

marked breaks of slope. This is relevant to many 

developments where track crossings have been routed 

towards the edge of the peat body to minimise wider 

hydrological effects. 

Drains create steep hydraulic gradients and cause localised 

zones of peat weakness. Peat pipes enable the rapid transfer 

of water within the peat body, and can result in temporary 

surcharging of some areas with water during or after intense 

rainfall. Alterations to both surface and sub-surface 

hydrology may result from windfarm construction. 

Surface loading Excavated peat and imported road base material may each 

contribute to this. 

We hope that these comments have been useful. Please contact myself or David Hatcher if you wish to 

discuss this response. 

Yours Sincerely, 

Jonathan Gilpin 

FC Windfarm Casework Officer 

cc. 

David Hatcher CCW 

Richard Ninnes CCW 





Annexe 1: 

1.1 

Overview (limited extent of peat): 

Whilst it may be the case that peat is of relatively limited distribution at this site, it will nevertheless be 

important to confirm this by checking peat depths outside its known extent and wherever windfarm 

infrastructure is planned or possible. It’s also important to note that some of the soil associations mapped 

at Clocaenog may include series with an important peat element – for example the Wilcocks 2 association 

includes both the Crowdy and Winter Hill deep peat series. 

Survey methodology 1.2: 

Bullet point two (peat depths 20 m spacings at turbine locations): 

This is adequate for the purposes of defining whether peat is present, but a denser sampling pattern should 

be used if peat is found to support decisions on micro-siting. 

Bullet point three (Peat depths along new access tracks located on peat): 

Our first point must be that we expect any such overlaps to be avoided. Our internal guidance establishes 

a presumption against infrastructure on peat, and this is also the basis of current policy development with 

partners in Wales. Any overlap will need to be subject to detailed assessment and the case for alternatives 

fully considered. The sampling intensity prescribed here is inadequate. We suggest a 25 m linear 

sampling interval as minimum and a wider pattern of lateral probing (dependent on topography – but 

possibly as wide as 100 m). It is in the developer’s interest to do this because our response to any overlap 

of new track infrastructure on peat will be to ask for evidence to guide decisions over alternative 

alignments which avoid or lessen the impact on peat. Access through the forest may limit the extent of 

peat probing on certain parts of the proposed track routes restricting peat assessment and all attempts 

should be made to obtain this data. 

Bullet Point 4 (widening of existing tracks on peat): We would expect widening to be confined to areas 

with mineral soil or, at worst, organo-mineral profiles. A 100 m sampling interval is unlikely to be 

suitable for this purpose – we suggest 25 m as a minimum, with closer spacing at locations with peat and 

where widening is deemed necessary to try and push widening schemes off the peat as far as possible. A 5 

m spread is also too wide at locations where peat is known or suspected to occur as it might miss it 

altogether. We suggest 2.5 m intervals in such cases. 

The comments above about sampling effort are also applicable to mitigation. Should overlap with peat 

occur, then CCW should ask for an estimate of the carbon cost to act as a target for compensatory 

mitigation elsewhere in the site. Peat depth is the easiest relevant parameter to measure, and the use of 

probing enables the rapid acquisition of a reasonable amount of depth data. 





Bullet point five (use of peat probing): 

This is an acceptable method. Drain rods tend to be flexible and a 3m length might be unwieldy. We 

suggest using a T handle and 1 m extension rod from an augering kit (see 

http://www.vanwalt.com/hand_augers-groundwater-soil-sampling-auger.htm) as this is safe and easy to 

use. Also, it enables an auger head to be used to calibrate rod-probing – it’s very important to check that 

what feels like peat from probing actually is. The GPS may not work well with extensive surrounding 

forestry – you should check this is likely to be viable first. 

Bullet point six (production of peat maps): The production of peat information relating solely to impacts 

will hamper discussions on mitigation involving peat elsewhere within the site. As a minimum, we expect 

the developer to check on the possible presence of peat within locations which are topographically suitable 

for its formation. Polygons demonstrating extent of variable peat depths would be preferred with the 

proposed infrastructure layouts and/or micro-siting possibilities overlaid on to it. 





Yours sincerely 

Name 

Title 

Enc 

cc. 





Sarah, 

Clocaenog Wind Farm peat assessment. 

Thanks you for your consultation on the outstanding peat assessment work 

and methodology. I have highlighted in bold under the relevant bullet points 

of your e-mail our response to your proposals. 

CCW estimate by overlaying the NRSI data over SSSA, A that there 

is supposedly 450ha of peat on the site. 

Survey work 

• We have surveyed the areas around 5 turbines located in close proximity 

to peat deposits identified on the BGS mapping data of the site, and will 

survey a further 10 turbines located within areas identified as the 

Wilcocks 2 soil association (which includes the Crowdy and Winter Hill 

deep peat series). Access issues are likely to constrain the surveying at 6 

of these turbine locations (due to extremely dense forest) and dependant 

on access we could undertake some limited probing as close as possible 

to the turbine, but may have to accept that there is no available access at 

some of these sites. 

We appreciate the difficulties, but if pre-construction surveys (presumably post 

planning consent?) could include the identification of peat deposits in the relevant areas 

of infrastructure and if it's possible to get access then, then why not now? CCW will 

have to assume there is potentially a peat impact for unsurveyed locations – that carries 

a risk as without the data to determine otherwise the impact assessment is not complete 

and does not iteratively inform the design of the development (to minimise impacts) a 

requirement of the EIA process. The above is by all accounts a very minimal 

sample of turbine locations on the site and CCW would recommend peat 

probing/angering at more sites than this. 

• Surveying has been/will be undertaken using the methodology previously 

provided, updated to take account of the recent comments from CCW. 

• We will also survey all new access tracks located within close proximity to 

known peat deposits, or within the Wilcocks 2 soil association (again 

assuming access is possible).

It would be useful to define what is meant by ‘close’. A lot depends on context, but 

probably anything within a 100 m of known peat deposits should be checked – especially 

if the apparent boundary of the peat is based on BGS/NRSI. 

• We do not propose to survey the areas surrounding existing tracks within 

the Wilcocks 2 soil association as, having been out on site, it is clear that 

the presence of the existing tracks has already had a significant impact on 

the surrounding habitat (e.g. fragmentation of peatland areas, drainage 

and drying out of peat deposits close to tracks), and further widening of 

existing tracks is unlikely to result in significant impacts to already 

degraded peat. It is considered that survey effort would be more 

valuable if focussed on areas currently free of track infrastructure, which 

can still be protected from any potential impact from micro-siting of wind 

farm infrastructure. 

It would be wise to know the depth of peat that will be covered by widened track 

sections in order to do the carbon calculations. Depending on how much widening is 

necessary, unless every section of the existing tracks is walked, it won’t be possible to 

assess that widening won’t result in further degradation. If for the most part existing 

tracks will be fit for purpose and there will only be a need to widen the track at 

pinch-points and acute bends etc then it would be appropriate to focus efforts at 

these locations. 

• We do not propose to survey the remaining 17 turbine areas, as it is clear 

from BGS geological maps, NSRI soil maps and topography of the site 

that there are unlikely to be peat deposits in these areas. We have also 

undertaken a phase 1 habitat survey of the forest (excluding areas where 

forest is impenetrable). The peat habitats within the phase 1 habitat 

broadly correspond to the BGS maps. 

We advise you do at least some ground-truthing to check peat is indeed absent – BGS 

and NRSI are not infallible and while topography is often a good guide, it is possible to 

be caught out i.e. by finding unexpectedly deep peat on quite steep slopes, and 

conversely next to no peat on flat upland sites! 

• We cannot propose to survey the inaccessible turbine areas at this stage. 

A desk-based assessment of these areas will be included in the technical 

report. Pre construction surveys will be undertaken to inform the 

detailed design and if required, these will include the identification of peat 

deposits for these areas. Turbines and other infrastructure will be microsited 

to avoid or minimise any impact on any previously unknown peat 

deposits wherever practicable.

Again we appreciate the difficulties but if this is possible in pre-construction surveys 

(presumably post planning consent?) why not now especially, if they are likely to be on 

peat. There would be insufficient evidence prove the design of turbine locations has 

been steered away from peat impacts. Once the application is in there is much more 

limited scope to avoid peat. 

Ongoing work 

• Following completion of the field survey, the results will be used to advise 

on adjustments to the site layout where required and where possible so 

as to avoid or minimise loss of peat. Where this is not possible, 

justification will be given as to why not. 

The field survey will be very limited. Surely the only justification would be the 

limit of the survey work. 

• Where, in the unlikely event that infrastructure cannot be sited to wholly 

avoid areas of peat, the impact assessment will consider potential impacts 

due to direct loss of peat (e.g. carbon balance, loss of habitat, erosion, 

peatslide risk (considered to be negligible at this site), water quality 

impacts) and indirect impacts (e.g. due to changes in hydrology due to 

installation of drainage ditches, leading to drying out of peatland habitat). 

. 

How many turbines/infrastructure locations are under afforestation at present and are 

all those in open areas going to be assessed for impacts on peat? Hydrological impacts 

are here categorised as indirect, CCW would regard them as direct because they would 

be a direct consequence of the development. Why are drainage ditches anticipated? 

Any infrastructure on peat should be using methodologies which minimise drainage 

impacts as far as possible (i.e. floating roads). 

• Where required, mitigation measures will be provided to ensure the 

impact to peatland habitats is minimised. It should be noted that from 

field investigations to date, it is clear that forestry operations have led to 

significant degradation of areas of peat (e.g. extensive ditch networks 

have been created to drain waterlogged peaty soils, mechanical plant has 

tracked over/ damaged peat habitat, and the presence of commercial 

forestry over the site since 1905 has had a severe detrimental impact on 

peatland vegetation and habitat), and where possible measures will be 

put in place to improve the current habitat quality. This might include, 

for example blocking of drains to raise the water table. 

Obviously some degradation will have taken place, but restoration could secure a 

beneficial outcome on even badly degraded surfaces. Targetting of restoration areas will 

not be possible (to inform the ES) without a better understanding through survey of the 

current peat resource.

• If peat is identified through desk studies and field surveys, infrastructure 

will, wherever possible be sited to avoid peat. If in the unlikely event that 

this is not possible and it is considered that the loss or damage to peat 

results in a significant impact, then enhancement/compensation measures 

will be considered. These will need to be agreed in advance with Forestry 

Commission Wales. If required, areas of peat with greatest potential for 

restoration will be identified in the ES. If required, commitments would 

be made for the implementation of a Habitat Management Plan for the 

site, which could include commitments for: 

Comments as above. Any impact (not just significant) needs compensatory measures. 

Ultimately, we advise going the extra mile in terms of compensation owing to the 

benefits and message it conveys... 

• Further surveying (assuming access allows) of the full extent of identified 

peat deposits across the site, to identify areas most suitable for 

restoration/enhancement. This will include further peat depth surveys, 

mapping of drainage ditches and NVC classification of peatland habitats; 

We presume this is all proposed to happen post consent. If the ES identifies an impact, 

then compensatory measures need to be quantified in the ES so that we can judge their 

sufficiency in relation to the impact. A significant impact with no subsequent hard 

figures for what they are going to restore via compensation is something we’d obviously 

question. This would include assessments of carbon impacts. 

• Consultation with CCW and Forestry Commission Wales to agree ongoing 

measures for peatland habitat restoration across the Clocaenog Forest 

site; 

What options with a view to the long term management of peat and restored 

areas have been considered and offered by FCW at this stage? What hectarage 

might be available? 

• Monitoring of changes to peatland habitat following implementation of 

mitigation measures and compensation/enhancement measures.

Appendix 2 

Photolog of Survey 

Locations

1 PHOTOLOG OF SURVEY LOCATIONS 

Figure 1.1 Turbine 1 

Figure 1.2 Track between Turbine 1 and North Substation 


1


Figure 1.4 Track to Turbines 2 and 3 


2


Figure 1.6 Track to Turbine 4 


3




4

Figure 1.9 Track past Turbine 7 



5




6

Figure 1.13 Turbine 11 – Dense forestry, no access 

Figure 1.14 Turbine 11 – Open ground/scrub to south of turbine 


7

Figure 1.15 Track to East of Turbine 11 

Figure 1.16 Turbine 12 – no access 


8


Figure 1.18 Public Road between Turbines 13 and 14 


9

Figure 1.19 Turbine 15 - no access 



10


Figure 1.22 Turbine 22 – limited access 


11

Figure 1.23 Turbine 24 - no access 



12

Figure 1.25 Track past Turbine 25 



13



14

Appendix 3 

Detailed Results Figures

KEY: 

0.02m 

0.57m 

0.65m 

0.87m 

0.87m 

0.97m 

0.2 

0.12 

0.28m 

0.22m 

0.22m 

0.3m 

0.47m 

0.55m 

0.82m 

0.5m 

1.13m 

0.9m 

0.4m 

0.33m 

0.33m 

Development Area 

Turbine 

0.43m 

0.43m 

0.28m 

0.47m 

1.17m 

Sample Location 

Existing tracks 

Turbine 4 Turbine 1 

Turbine 2 

Turbine 3 

1.2m 

0.45m 

0.23m 

0m 

0.12m 

0.33m 

0.83m 

1.07m 

0.5m 

0.53m 

0.35m 

0.33m 

0.3m 

0.5m 

0.55m 

0.57m 

0.23m 

0.37m 

0.38m 

0.4m 

0.12 

Puiblic Road Section 

0.17 

0.12 

0.13 

0.67 

0.1 

0.15 

0.38m 

0.18m 

0.18 

0.32 

0.17 

1.23 

0.32 

Acces Track Peat Depth(m) 

0 - 0.25m 

0.25 - 0.5m 

0.5 - 0.75m 

0.75 - 1.0m 

1.0 - 1.25m 

1.25 - 1.5m 

0m 

0m 

0.27m 

0.23m 

0.17m 

0.23m 

0.27m 

0.32m 

0.18m 

Average Peat Depth(m) 

0.0 - 0.25 

0.25 - 0.5 

0.5 - 1.0 

1.0 - 1.5 

1.5 - 2.2 

0.32m 

0.28m 

0.3m 

0.28m 

0.25m 

0.22m 

0.37m 

0.25m 

0.33m 

0.12m 

0.22m 


Turbine 8 

0.23m 

0.35 

0.37 

0.3m 

0.2m 

0.07m 

0.47 

0.1 

0.35 

0.17 

0.12 

0.3m 

0.23m 

0m 

0m 

0.37m 

0.33m 

0.18m 

0.37m 

0.33m 

0.32m 

0.5m 

Superficial Geology 

Alluvial Fan Deposits 

Alluvium 

Peat 

River Terrace Deposits (Undifferentiated) 

Superficial Deposits Not Mapped 

[For Digital Map Use Only] 

Till, Devensian 

0 500 

Metres 

0.8m 

0.18m 

0.15m 

0.15m 

0.48m 

0.82m 

0.7m 

0.2m 

0.67m 

0.28m 

0.22m 

0.22m 

0.5m 

0.2m 

0.18m 

0.23m 

0.3m 

0.5m 

0.38m 

0.77m 

0.4m 

0.23m 

0.2m 

0.22m 

0.17m 

0m 

0.77m 

0.22m 

0.17m 

0.12m 

0m 

CLIENT: SIZE: TITLE: 

ERM 

Llandarcy House 

11A The Courtyard 

Llandarcy 

Swansea Bay, SA10 6EJ 

Tel: 01792 814907 

Fax: 01792 817396 

0.87m 

0.18m 

0.12m 

0.18m 

0.08m 

0.18m 

0.28m 

0.23m 

0.5m 

SOURCE: Reproduced from Ordnance Survey digital map data. © Crown 

copyright, All rights reserved. 2009 License number 0100031673. © BGS DigMap 

50-GB 

PROJECTION: British National Grid 

0.25 

0.2 

0.2 

0.15 

0.15 

0.2 

0.49m 

0.27m 

0.25m 

0.25 

0.15 

0.25 

0.1 

0.2 

0.25 

0.1 

0.1 

0.2 

0.25 

0.15 

0.2 

A3 Figure 3.4 

Peat Overview - North 

DATE: 29/06/2010 

DRAWN: MTC 

0.17m 

0.14m 

0.1m 

0.2 

0.1 

0.1 

0.15 

0.1 

0.15 

0.3 

0.1 

0.15 

0.2 

0.25 

0.15 

0.15 

0.14m 

0.15m 

0.22m 

0.2 

0.1 

0.1 

0.05 

0.2 

0.15 

0.2 

0.25 

0.2 

0.15 

0.25 

0.1 

Turbine 5 

0.19m 

CHECKED: HE 

APPROVED: AD 

0.25 

0.19m 

0.14m 

0.2m 

0.17m 

0.12m 

0.19m 

PROJECT: 0088650 

0.1m 

SCALE: As Scale Bar 

0.12m 

0.29m 

0.37m 

DRAWING: REV: 

Peat_Map _North_Rev.mxd 0 

0.2 

0.15 

0.15 

0.15 

0.2 

0.15 

0.15 

0.15 

0.15 

0.2 

0.1 

0.1 

0.1 

0.2 

0.15 

0.2 

0.1 

0.2 

0.2 

0.25 

0.35 

0.3 

0.25 

0.1 

0.1 

0.15 

0.2 

0.25 

0.15 

0.3 

File: 0088650_Clocaenog_Lead_EIA_SXD_JH\MAPS\PeatMaps\Update\Peat_Map _North_Rev.mxd

KEY: 

0.15m 0.08m 

0.2m 

0.28m 

0.18m 

0.23m 

0.1m 

0.19m 

0.27m 

0.14m 

0.17m 

0.17m 

0.15m 

0.1m 

0.1m 


Turbine 

0.12m 

0.19m 

0.2m 

0.14m 

0.17m 

0.24m 

0.2m 

Existing tracks 


0.73m 

0.1m 

0.07m 

0.14m 

0.17m 

0.2m 

0.19m 

0.14m 

0.14m 

1m 

Turbine 22 

0m 

0.2m 

0.07m 

0.13m 

Turbine 26 

Tracks Junction 

1m 

0.77m 

0.22m 

0.15m 

0.15m 

0.17m 

0m 

0.09m 

1.33m 

0.22m 0.07m 

0.75m 

0.4m 

0.13m 

0.3m 0.85m 

0.63m 

0.17m 

0.22m 

0.25m 

0m 

0.2m 

0.19m 

0.1m 

0.07m 

0.12m 

0.15m 


0 - 0.25m 

0.14m 

0.04m 

0.5m 

0.42m 

0.14m 

0.1m 

0.25 - 0.5m 

0.5 - 0.75m 

0.75 - 1.0m 

1.0 - 1.25m 

1.25 - 1.5m 

0.2m 

0.93m 

0.12m 

1.02m 

0.47m 

Average Peat Depth (m) 

0.0 - 0.25 

0.25 - 0.5 

0.5 - 1.0 

1.0 - 1.5 

1.5 - 2.2 

Superficial Geology 


Alluvium 

Peat 

River Terrace Deposits (Undifferentiated) 




0 500 

Metres 

0.25m 

0.5m 

0.47m 

0.37m 

0.1m 

0.19m 

0.15m 

0.17m 

0.14m 

0.2m 

0.77m 

0.6m 

0.87m 

0m 

0.14m 

0.15m 

0.17m 

0.17m 

0.2m 

1.97m 

2.2m 

0.9m 1.43m 

2.1m 

Turbine 25 

0.07m 

0m 

0.2m 

0.15m 

0.17m 

0.19m 

0.2m 

0m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 

1.63m 

0.09m 

0.22m 

0.2m 

0.35m 


copyright, All rights reserved. 2009 License number 0100031673. © BGS DigMap 

50-GB 


0m 

0m 

0m 

0.2m 

0m 

0.1m 

0.17m 

0.63m 

0.55m 

1.27m 

1.23m 

1.27m 

0.37m 

0.24m 

0.34m 

0.32m 

0.4m 

0.44m 

1.2m 

A3 Figure 3.5 

Peat Overview - South 

DATE: 29/06/2010 

DRAWN: MTC 

Turbine 11 

0.7m 

0.23m 

0.53m 

0.42m 0.68m 

0.2m 

0.19m 

0.45m 

0.72m 

0.45m 

0.33m 

0.5m 

0.32m 

0.5m 

0.35m 

0.44m 

0.65m 

CHECKED: HE 

0.5m 

APPROVED: AD 

0.45m 


0.4m 

0.5m 

0.29m 

0.47m 

0.39m 

0.65m 

0.24m 

0.27m 

0.29m 

0.32m 

0.22m 

0.4m 

0.32m 

0.42m 



0.6m 

DRAWING: REV: 

Peat_Map _South_Rev.mxd 0 

File: 0088650_Clocaenog_Lead_EIA_SXD_JH\MAPS\PeatMaps\Update\Peat_Map _South_Rev.mxd

KEY: 

TURBINE 1 

0.15 


Turbine 


with Peat Depth (m) 

50m Buffer 

100m Buffer 

0.13 

0.2 

0.23 

BGS Superficial Geology 


Alluvium 

Peat 

River Terrace Deposits 

(Undifferentiated) 

0.28 

0.07 

0.1 




0.62 

0m 

0m 

0.27m 

0.23m 

0.17m 

0.82 

0.23m 

0.27m 

0.32m 

0.18m 

1.25 

0.38 


0 - 0.25m 

0.25 - 0.5m 

0.5 - 0.75m 

0.75 - 1.0m 

1.0 - 1.25m 

1.25 - 1.5m 

0.52 

0.32m 

0.28m 

0.3m 

0.32 

0.78 

0.28m 

0.25m 

0.2 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1.0 

1.1 - 1.5 

1.6 - 2.2 

0.37m 

0.12m 

0.17 

0.22m 

0.25m 

0.33m 

0.22m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 


copyright, All rights reserved. 2009 License number 0100031673. 


A3 Figure 3.6 

Turbine 1 Average Peat Depth 

DATE: 23/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 

Peat_Depth_Turbine1.mxd 0 

File: 0088650_Clocaenog_Lead_EIA_SXD_JH\MAPS\PeatMaps\Update\Peat_Depth_Turbine1.mxd

KEY: 


Turbine 



50m Buffer 

100m Buffer 



Alluvium 

Peat 

TURBINE 2 






0.48m 

0.82m 

0.7m 


0.0 - 0.25 

0.25 - 0.5 

0.5 - 1.0 

1.0 - 1.5 

1.5 - 2.2 

0.5m 

0.38m 

0.77m 

0.4m 

0.77m 

0.28m 

0.23m 

0.5m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 




A3 Figure 3.7 


DATE: 29/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



KEY: 


Turbine 



50m Buffer 

100m Buffer 

TURBINE 3 



Alluvium 

Peat 



0.25m 

0.2m 

0.2m 

0.15m 

0.15m 

0.2m 




0.25m 

0.15m 

0.2m 

0.25m 

0.15m 

0.2m 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1.0 

1.1 - 1.5 

1.6 - 2.2 

0.3m 

0.1m 

0.15m 

0.2m 

0.25m 

0.15m 

0.15m 

0.2m 

0.25m 

0.2m 

0.15m 

0.25m 

0.1m 

0.15m 

0.15m 

0.15m 

0.2m 

0.1m 

0.1m 

0.2m 

0.25m 

0.35m 

0.3m 

0.25m 

0.1m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 




A3 Figure 3.8 


DATE: 29/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



KEY: 

TURBINE 4 


Turbine 



50m Buffer 

100m Buffer 



Alluvium 

Peat 



0.02m 

0.57m 

0.65m 

0.87m 

0.87m 

0.97m 




0.47m 

0.55m 

0.82m 

0.5m 

1.13m 

0.9m 

0.43m 

0.43m 

0.28m 

0.47m 

1.17m 

1.2m 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1 

1.1 - 1.5 

1.6 - 2.2 

0.45m 

0.23m 

0m 

0.12m 

0.33m 

0.83m 

1.07m 

0.5m 

0.53m 

0.35m 

0.33m 

0.3m 

0.5m 

0.55m 

0.57m 

0.23m 

0.37m 

0.38m 

0.4m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 




A3 Figure 3.9 


DATE: 09/03/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



KEY: 

TURBINE 5 


Turbine 



50m Buffer 

100m Buffer 



Alluvium 

Peat 



0.49m 

0.27m 

0.25m 




0.17m 

0.14m 

0.1m 

0.14m 

0.15m 

0.22m 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1.0 

1.1 - 1.5 

1.6 - 2.2 

0.19m 

0.19m 

0.14m 

0.2m 

0.17m 

0.12m 

0.19m 

0.12m 

0.1m 

0.29m 

0.37m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 




A3 Figure 3.10 


DATE: 29/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



KEY: 

TURBINE 7 


Turbine 



50m Buffer 

100m Buffer 



Alluvium 

Peat 



0.8m 

0.67m 

0.18m 

0.15m 

0.15m 




0.2m 

0.28m 

0.22m 

0.22m 

0.2m 

0.3m 

0.5m 

0.18m 

0.23m 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1.0 

1.1 - 1.5 

1.6 - 2.2 

0.2m 

0.23m 

0.22m 

0.17m 

0m 

0.22m 

0.17m 

0.12m 

0m 

0.87m 

0.18m 

0.12m 

0.18m 

0.08m 

0.18m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 






DATE: 29/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



KEY: 


Turbine 


with Peat Depth 

50m Buffer 

100m Buffer 

TURBINE 8 



Alluvium 

Peat 



0.1m 

0.2m 

0.1m 

0.1m 




0.25m 

0.25m 

0.2m 

0.1m 

0.1m 

0.15m 

0.1m 

0.15m 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1.0 

1.1 - 1.5 

1.6 - 2.2 

0.2m 

0.1m 

0.1m 

0.05m 

0.2m 

0.15m 

0.25m 

0.2m 

0.15m 

0.15m 

0.15m 

0.2m 

0.15m 

0.1m 

0.2m 

0.15m 

0.2m 

0.1m 

0.2m 

0.1m 

0.15m 

0.2m 

0.25m 

0.15m 

0.3m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 






DATE: 29/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



KEY: 

TURBINE 9 


Turbine 



50m Buffer 

100m Buffer 



Alluvium 

Peat 



0.28m 

0.22m 

0.22m 

0.3m 




0.4m 

0.33m 

0.33m 

0.38m 

0.18m 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1.0 

1.1 - 1.5 

1.6 - 2.2 

0.23m 

0.3m 

0.2m 

0.07m 

0.3m 

0.23m 

0m 

0m 

0.37m 

0.33m 

0.18m 

0.37m 

0.33m 

0.32m 

0.5m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 






DATE: 29/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



0.63m 

0.55m 

KEY: 

TURBINE 11 


Turbine 



50m Buffer 

100m Buffer 

1.23m 

1.27m 

1.2m 

1.27m 

0.37m 



Alluvium 

Peat 






0.42m 

0.7m 

0.68m 0.53m 

0.58m 

Access Track Peat Depth(m) 

0 - 0.25m 

0.25 - 0.5m 

0.5 - 0.75m 

0.75 - 1.0m 

1.0 - 1.25m 

1.25 - 1.5m 

0.33m 

0.45m 

0.5m 

0.23m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 




DATE: 23/06/2010 

DRAWN: MTC 

0.45m 

CHECKED: HE 

APPROVED: AD 

0.4m 

0.17m 

0.5m 

0 40 

Metres 





DRAWING: REV: 

Peat_Depth_Turbine11_blobs.mxd 0 

File: 0088650_Clocaenog_Lead_EIA_SXD_JH\MAPS\PeatMaps\Update\Peat_Depth_Turbine11_blobs.mxd

KEY: 


Turbine 



50m Buffer 

100m Buffer 

TURBINE 13 



Alluvium 

Peat 



0.24m 

0.34m 

0.32m 

0.4m 

0.44m 




0.2m 

0.19m 

0.45m 

0.72m 

0.32m 

0.5m 

0.35m 

0.44m 

0.65m 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1.0 

1.1 - 1.5 

1.6 - 2.2 

0.5m 

0.29m 

0.47m 

0.39m 

0.65m 

0.27m 

0.32m 

0.4m 

0.42m 

0.24m 

0.29m 

0.22m 

0.32m 

0.6m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 






DATE: 29/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



KEY: 


Turbine 



50m Buffer 

100m Buffer 

0.47m 

0.25m 

0.37m 

TURBINE 19 

0.5m 

0.77m 

0.53m 

0.6m 

0.87m 



Alluvium 

Peat 



1.97m 

2.2m 




0.9m 

2.1m 

1.43m 

1.63m 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1.0 

1.1 - 1.5 

1.6 - 2.2 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 






DATE: 29/06/2010 

DRAWN: MTC 

0 50 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



KEY: 

TURBINE 22 


Turbine 



50m Buffer 

100m Buffer 



Alluvium 

Peat 



0.28m 

0.18m 

0.23m 

0.1m 




0.1m 

0.1m 

0.12m 

0.1m 

0.07m 


0.0 - 0.25 

0.25 - 0.5 

0.5 - 1.0 

1.0 - 1.5 

1.5 - 2.2 

0m 

0.07m 

0.13m 

0.1m 

0.07m 

0.12m 

0.15m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 






DATE: 29/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



KEY: 


Turbine 



50m Buffer 

100m Buffer 

TURBINE 25 



Alluvium 

Peat 






0.1m 

0.19m 

0.15m 

0.17m 

0.14m 

0.2m 

0m 

0.14m 

0.15m 

0.17m 

0.17m 

0.2m 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1.0 

1.1 - 1.5 

1.6 - 2.2 

0.07m 

0m 

0.2m 

0.15m 

0.17m 

0.19m 

0.2m 

0.09m 

0m 

0.22m 

0.2m 

0.35m 

0m 

0m 

0m 

0.2m 

0m 

0.1m 

0.17m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 






DATE: 29/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



KEY: 

TURBINE 26 


Turbine 



50m Buffer 

100m Buffer 



Alluvium 

Peat 



0.19m 

0.27m 

0.14m 

0.17m 

0.17m 

0.15m 




0.19m 

0.2m 

0.14m 

0.17m 

0.24m 

0.2m 

0.14m 

0.17m 

0.2m 

0.19m 

0.14m 

0.14m 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1.0 

1.1 - 1.5 

1.6 - 2.2 

0.2m 

0.22m 

0.15m 

0.15m 

0.17m 

0m 

0.09m 

0.17m 

0.22m 

0.25m 

0m 

0.2m 

0.19m 

0.14m 

0.04m 

0.5m 

0.42m 

0.14m 

0.1m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 






DATE: 29/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 



KEY: 

0.15m 

0.08m 


Turbine 



0.2m 

TRACKS 

JUNCTION 



Alluvium 

Peat 






0.73m 

1m 

1m 

0.77m 

0.22m 

0.07m 


0.0 - 0.25 

0.26 - 0.5 

0.51 - 1 

1.1 - 1.5 

1.6 - 2.2 

1.33m 

0.75m 

0.4m 

0.3m 

0.63m 

0.85m 

0.13m 

0.2m 


ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 




DATE: 29/06/2010 

DRAWN: MTC 

0.93m 

CHECKED: HE 

APPROVED: AD 

0.12m 


Tracks Junction 

Average Peat Depth 

1.02m 

0 50 

Metres 



DRAWING: REV: 

Peat_Depth_TracksJunction.mxd 0 

File: 0088650_Clocaenog_Lead_EIA_SXD_JH\MAPS\PeatMaps\Update\Peat_Depth_TracksJunction.mxd

KEY: 

0.2 

0.12 


Turbine 



100m Buffer 

PUBLIC ROAD 

SECTION 

0.67 

Access Track Peat Depth(m) 

0 - 0.25m 

0.25 - 0.5m 

0.5 - 0.75m 

0.75 - 1.0m 

1.0 - 1.25m 

1.25 - 1.5m 

0.12 

0.13 

0.15 

0.18 

1.23 

0.1 

0.32 

0.17 

0.37 



Alluvium 

Peat 



0.47 




0.35 

0.35 

0.32 

0.1 

0.17 

0.12 

0.12 

0.17 

Area Not Within 



ERM 



Llandarcy 


Tel: 01792 814907 

Fax: 01792 817396 





Public Road Section 

Between Turbine 5 and 7 

DATE: 29/06/2010 

DRAWN: MTC 

0 40 

CHECKED: HE 

APPROVED: AD 

Metres 



DRAWING: REV: 

AreaBetweenT5andT7.mxd 0 

0.72 

File: 0088650_Clocaenog_Lead_EIA_SXD_JH\MAPS\PeatMaps\Update\AreaBetweenT5andT7.mxd

Annex F3 

National Soil Resources 

Institute Soil Site Reports - 

North and South

National Soil 

Resources Institute 

Soils Site Report 

Full Soil Report 

Clocaenog North 

National Grid Reference: SJ0100056500 

Easting: 301000 

Northing: 356500 

Site Area: 5km x 5km 

Prepared by 

authorised user: 

Heather Eadie 

ERM Ltd 

16 July 2009 

© Cranfield University (NSRI) 2008. All rights reserved.

National Soil Resources Institute 

Citations 

Citations to this report should be made as follows: 

Disclaimer 

Page 2 of 58 

National Soil Resources Institute (2009) Full Soils Site Report for location 301000E, 

356500N, 5km x 5km, National Soil Resources Institute, Cranfield University. 

Accessed via https://www.landis.org.uk/sitereporter/. 

The report, modules and risk maps have been prepared by Cranfield University for 

you, the client. Whilst every care has been taken by Cranfield University to ensure 

the accuracy and completeness of the reports, modules and risk maps, the client 

must recognise that as with any such reports, modules and risk maps errors are 

possible through no fault of Cranfield University and as such the parties give no 

express or implied representations or warranty as to: 

( i ) the quality or fitness for any particular purpose of the report, modules or risk 

maps contained herein or of any design, workmanship, materials or parts used in 

connection therewith or correspondence with regard to any description or sample; 

or 

(ii) the accuracy, sufficiency or completeness of the report modules or risk maps 

provided herewith. In particular, there are hereby expressly excluded all 

conditions, warranties and other terms which might otherwise be implied (whether 

by common law, by statute or otherwise) as to any of the matters set out in 

paragraphs (i) and (ii) above. 

Cranfield University, its employees, servants and agents shall accept no liability for 

any damage caused directly or indirectly by the use of any information contained 

herein and without prejudice to the generality of the foregoing, by any 

inaccuracies, defects or omissions in the report, modules or risk maps provided.


About this report 

Page 3 of 58 

This Soils Site Report identifies and describes the properties and capacities of the 

soil at your specified location as recorded in the 1:250,000 scale National Soil Map 

for England and Wales. It has been produced by Cranfield University’s National 

Soil Resources Institute. 

The National Soil Map represents the most accurate comprehensive source of 

information about the soil at the national coverage in England and Wales. It maps 

the distribution of soil mapping units (termed soil associations) which are defined 

in terms of the main soil types (or soil series) that were recorded for each soil 

association during field soil survey. Each soil association is named after its 

principal soil series and these bear the location name from where they were first 

described (e.g. Windsor). Each of these soil associations have differing 

environmental characteristics (physical, chemical and biological) and it is by 

mapping these properties that the range of thematic maps in this report have 

been produced. 

Soil types and properties vary locally, as well as at the landscape scale. It is not 

possible to identify precisely the soil conditions at a specific location without first 

making a site visit. We have therefore provided you with information about the 

range of soil types we have identified at and around your selected location. 

Schematic diagrams are also provided to aid accurate identification of the soil 

series at your site. 

Whilst an eight-figure national grid reference should be accurate to within 100m, a 

single rural Postcode can cover a relatively large geographical area. Postcodes 

can therefore be a less precise basis for specifying a location. The maps indicate 

the bounded area the reports relate to. 

Your Soils Site Report will enable you to: 

• identify the soils most likely to be present at and immediately around your 

specified location; 

• understand the patterns of soil variation around your location and how these 

correlate with changes in landscape; 

• identify the nature and properties of each soil type present within the area; 

• understand the relevant capacities and limitations of each of the soils and how 

these might impact on a range of factors such as surface water quality. 

Provided that this Soils Site Report is not modified in any way, you may reproduce 

it for a third-party. 

For more information visit www.landis.org.uk/reports


Table of Contents 

Page 4 of 58 

1. SOIL THEMATIC MAPS ------------------------------------------------------------------------------------------------------------- 6 

a. Soil Spatial Distribution ------------------------------------------------------------------------------------------------------- 7 

b. Hydrology of Soil Type (HOST) ---------------------------------------------------------------------------------------------- 8 

c. Ground Movement Potential ------------------------------------------------------------------------------------------------ 9 

d. Flood Vulnerability ----------------------------------------------------------------------------------------------------------- 11 

e. Risk of Corrosion to Ferrous Iron ------------------------------------------------------------------------------------------- 12 

f. Pesticide Leaching Risk ------------------------------------------------------------------------------------------------------ 13 

g. Pesticide Runoff Risk -------------------------------------------------------------------------------------------------------- 14 

h. Hydrogeological Rock Type ------------------------------------------------------------------------------------------------ 15 

i. Ground Water Protection Policy (GWPP) Leaching ---------------------------------------------------------------------- 16 

j. Soil Parent Material ---------------------------------------------------------------------------------------------------------- 17 

k. Expected Crops and Land Use --------------------------------------------------------------------------------------------- 18 

l. Natural Soil Fertility ----------------------------------------------------------------------------------------------------------- 19 

m. Simple Topsoil Texture ----------------------------------------------------------------------------------------------------- 20 

n. Typical Habitats ------------------------------------------------------------------------------------------------------------- 21 

2. SOIL ASSOCIATION DESCRIPTIONS -------------------------------------------------------------------------------------------- 

MANOD 611c 

a. General Description --------------------------------------------------------------------------------------------------------- 23 

b. Distribution (England and Wales) ------------------------------------------------------------------------------------------ 23 

c. Comprising Soil Series ------------------------------------------------------------------------------------------------------- 23 

d. Component Soil Series Profile Diagrams ---------------------------------------------------------------------------------- 24 

e. Soil Properties - Charts ------------------------------------------------------------------------------------------------------ 25 

i. Soil Depth Information and Depths to Important Layers ------------------------------------------------------------- 25 

ii. Soil Hydrological Information ------------------------------------------------------------------------------------------- 27 

iii. Available Water Content (AWC) ------------------------------------------------------------------------------------- 28 

HAFREN 654a 









BRICKFIELD 1 713e 









22


WILCOCKS 2 721d 

Page 5 of 58 









3. TOPSOIL ELEMENT BACKGROUND LEVELS ------------------------------------------------------------------------------------a. 

Analyses Within a 15km Radius -------------------------------------------------------------------------------------------b. 

Analyses Within a 50km Radius -------------------------------------------------------------------------------------------c. 

National Analyses ----------------------------------------------------------------------------------------------------------- 

REFERENCES ------------------------------------------------------------------------------------------------------------------------- 58 

51 

52 

53 

54


1. SOIL THEMATIC MAPS 

Page 6 of 58 

This section contains a series of maps of the area surrounding your selected location, based on the 1:250,000 scale National Soil Map, 

presenting a number of thematic maps relating to the characteristics of the soils. These provide an overview of the nature and condition of 

the local soil conditions. It is these conditions that may be used to infer the response of an area to certain events (with the soil as a receptor), 

such as pollution contamination from a chemical spill, or an inappropriate pesticide application and the likelihood of these materials passing 

though the soil to groundwater. Other assessments provide an insight into the way a location may impact, by corrosive attack or ground 

movement, upon structures or assets within the ground, for example building or engineering foundations or pipes and street furniture. 

Soil is a dynamic environment with many intersecting processes, chemical, physical and biological at play. Even soils ‘sealed’ over by 

concrete and bitumen are not completely dormant. The way soils respond to events and actions can vary considerably according to the 

properties of the soil as well as other related factors such as land-use, vegetation, topography and climate. There are many threats facing 

our national soil resource today and forthcoming legislation such as the proposed Soil Framework Directive (SFD) (COM(2006) 232) will seek 

to identify measures aimed towards soil protection and ensuring the usage of soils in the most sustainable way. This report is therefore a 

useful snapshot of the soil properties for your given area, providing a summary of a broad range of ground conditions.


1a. SOILS - SPATIAL DISTRIBUTION 

SOIL ASSOCIATION MAP UNIT KEY 

MANOD 611c 

Well drained fine loamy or fine silty soils over rock. 

Page 7 of 58 

HAFREN 654a 

Loamy permeable upland soils over rock with a wet peaty surface horizon and bleached subsurface horizon, often with thin ironpan. 


Slowly permeable seasonally waterlogged fine loamy and fine silty soils, some with wet peaty surface horizons. 


Slowly permeable seasonally waterlogged loamy upland soils with a peaty surface horizon. 

Soil associations represent a group of soil series (soil types) which are typically found occurring together, associated in the landscape 

(Avery, 1973; 1980; Clayden and Hollis, 1984). Soil associations may occur in many geographical locations around the country where 

the environmental conditions are comparable. For each of these soil associations, a collection of soil types (or soil series) are recorded 

together with their approximate proportions within the association. Soil associations have codes as well as textual names, thus code 

‘554a’ refers to the ‘Frilford’ association. Where a code is prefixed with ‘U’, the area is predominantly urbanised (e.g. ‘U571v’). The soil 

associations for your location, as mapped above, are described in more detail in Section 2: Soil Association Descriptions.


1b. HYDROLOGY OF SOIL TYPE (HOST) 

HYDROLOGY OF SOIL TYPE KEY 

Page 8 of 58 

15 - Permanently wet, peaty topped upland soils over relatively free draining permeable rocks 

17 - Relatively free draining soils with a large storage capacity over hard impermeable rocks with no storage capacity 

24 - Slowly permeable, seasonally waterlogged soils over slowly permeable substrates with negligible storage capacity 

26 - Permanently wet, peaty topped upland soils over slowly permeable substrates with negligible storage capacity 

HOST CLASS DESCRIPTION 

The Hydrology of Soil Types (HOST) classification describes the dominant pathways of water movement through the soil and, where 

appropriate, the underlying substrate. Eleven drainage models are defined according to the permeability of the soil and its substrate 

and the depth to a groundwater table, where one is present (Boorman et al,1995). These are further subdivided into 29 HOST classes 

to which all soil series have been assigned. These classes identify the way soil water flows are partitioned, with water passing over, 

laterally through, or vertically down the soil column. Analysis of the river hydrograph and the extent of soil series for several hundred 

gauged catchments allowed mean values for catchment hydrological variables to be identified for each HOST class, The HOST 

classification is widely used to predict river flows and the frequency and severity of flood events and also to model the behaviour of 

diffuse pollutants (Hollis et al, 1995).


1c. GROUND MOVEMENT POTENTIAL 

GROUND MOVEMENT POTENTIAL KEY 

1 - Very low 

2 - Low 

3 - Moderate 

4 - High 

5 - Very high 

Page 9 of 58 

* If a High class is starred, a ‘Very High’ ground movement potential is likely to be achieved if these soils are drained to an effective 

depth of at least two metres. 

GROUND MOVEMENT POTENTIAL DESCRIPTION 

Clay-related ground movement is the most widespread cause of foundation failure in the UK and is linked to seasonal swelling and 

shrinkage of the clay. The content of clay within the soils of your selected area has therefore a direct bearing upon the likelihood of 

ground movement. 

Among the inorganic particles that constitute the solid component of any soil, clay particles are the smallest and defined as being 


Page 10 of 58 

also takes place from soil and plant structures, and the combination of evaporation from surfaces and transpiration by plants and trees 

is termed evapotranspiration. Thus, the layer of soil material down to 2m depth into which plants will root is critical when assessing the 

vulnerability of land to subsidence. 

Whenever soil moisture is continuously being replenished by rainfall, the soil moisture reserves will be unaffected by the removal of 

moisture by plants as there is no net loss. However, in many parts of Britain, particularly in the south and east, summer rainfall is small 

and is exceeded by evapotranspiration. Water reserves are then not sufficiently replenished by rainfall and so a soil moisture deficit 

develops. The water removed from a clayey soil by evapotranspiration leads to a reduction in soil volume and the consequent shrinkage 

causes stress in the soil materials leading in turn to stress on building foundations that are resting in the soil (Hallett, et al, 1994). 

The foundations themselves may then move and thus cause damage to building structures. This problem can be exacerbated by the 

fact that the soil beneath the structure may not dry out uniformly, so that any lateral pressure exerted on the building foundation is made 

effectively greater. This assessment identifies the likelihood of soil conditions being prone to ground movement given these other 

factors.


1d. FLOOD VULNERABILITY 

FLOOD VULNERABILITY CLASS KEY 

0 - Major risk 

1 - Minor risk 

Page 11 of 58 

FLOOD VULNERABILITY DESCRIPTION 

The inundation of properties by flood water can occur in a number of circumstances. Surface run-off can collect on low-lying land from 

upslope following heavy rainfall. More commonly rivers, lakes and/or the sea extend beyond their normal limits as a result of prolonged 

or intense rainfall, unusually high tides and/or extreme wind events. Water damage to properties and their contents is compounded by 

the deposition of sediment suspended in the flood waters. The spatial distribution of such waterborne sediment (or alluvium as defined 

in soil science) is one basis upon which land that has been subject to historical flooding can be mapped, and this forms a basis for 

present-day flooding risk assessment. 

Both riverine and marine alluvium are identified as distinct soil parent materials within the British soil classifications. Combining soil map 

units that are dominated by soil series developed in alluvium across Great Britain identifies most of the land that is vulnerable to 

flooding. This assessment does not account for man-made flood defence measures, showing instead the areas where once water has 

stood.


1e. RISK OF CORROSION TO FERROUS IRON 

RISK OF CORROSION TO FERROUS IRON KEY 

1 - Non-aggressive 

2 - Slightly Aggressive 

3 - Moderately Aggressive 

4 - Highly Aggressive 

5 - Very highly Aggressive 

6 - Impermeable Rock 

Page 12 of 58 

* If a class is starred, it is assumed that there are moderate amounts of sulphate in the soil. If there is abundant sulphate present, the 

soil may be one class more aggressive. Conversely, if there is very little sulphate, the soil may be one class less aggressive to 

buried ferrous iron. 

RISK OF CORROSION TO FERROUS IRON DESCRIPTION 

Buried iron pipes and other infrastructure corrode at rates that are influenced by soil conditions (Jarvis and Hedges, 1994). Soil acidity, 

sulphide content, aeration and wetness all influence the corrosivity of the soil. These factors are used to map 5 major classes of relative 

corrosivity.


1f. PESTICIDE LEACHING RISK 

PESTICIDE LEACHING CLASS KEY 

I1n - Deep loamy soils over hard non-porous rocks - no groundwater present 

L p - Upland peaty soils over a variety of subsrtates, some with deep groundwater 

Page 13 of 58 

L q - Impermeable soils over soft substrates of low or negligible storage capacity that sometimes conceal groundwater 

bearing rocks at depth 

PESTICIDE LEACHING CLASS DESCRIPTION 

The natural permeability and water regime of soils are influential in determining the fate and behaviour of pesticides applied to the crop 

and soil surface (Hollis et al, 1995). A system of vulnerability assessment was devised as part of the national system for Policy and 

Practice for the Protection of Groundwater. This divided soils into three primary vulnerability classes. 

H - Soils of high leaching capacity with little ability to attenuate non-adsorbed pesticide leaching which leave underlying groundwater 

vulnerable to pesticide contamination. 

I – Soils of intermediate leaching capacity with a moderate ability to attenuate pesticide leaching. 

L - Soils of low leaching capacity through which pesticides are unlikely to leach. 

The primary classes have been further subdivided into nearly forty subclasses. These subclasses, with their descriptions, are mapped 

above. These classes do not account for differences in land cultivation, which can also have a significant impact on pesticide behaviour.


1g. PESTICIDE RUNOFF RISK 

PESTICIDE RUNOFF RISK KEY 

Page 14 of 58 

P2h - Upland peaty soils with high or very high run-off potential. Not normally farmed and probably with a high adsorption 

potential 

S2m - Soils with high run-off potential but moderate adsorption potential 

S3m - Soils with moderate run-off potential and moderate adsorption potential 

PESTICIDE RUNOFF RISK DESCRIPTION 

The physical properties and natural water regime of soils influence the speed and extent of lateral water movement over and through 

the soil at different depths (Hollis et al, 1995). At as result, soils can be classed according to the potential for pesticide run-off. Five 

runoff potential classes are identified for mineral soils and a further two for peat soils. The mineral soil classes are further subdivided 

according to the potential for pesticide adsorption.


1h. HYDROGEOLOGICAL ROCK TYPE 

HYDROGEOLOGICAL ROCK TYPE KEY 

22 - till and compact Head 

7 - hard, but deeply shattered non-arenaceous rocks 

Page 15 of 58 

HYDROGEOLOGICAL ROCK TYPE DESCRIPTION 

The hydrogeological classification of the soil parent materials provides a framework for distinguishing between soil substrates according 

to their general permeability and whether they are likely to overlie an aquifer. Every soil series has been assigned one of the 32 

substrate classes and each of these is characterised according to its permeability (being characterised as permeable, slowly 

permeable or impermeable). For further information, see Boorman et al (1995).


1i. GROUND WATER PROTECTION POLICY (GWPP) LEACHING 

GWPP LEACHING CLASS KEY 

Page 16 of 58 

I1 - Soils of intermediate leaching potential which have a moderate ability to attenuate a wide range of diffuse source 

pollutants but in which it is possible that some non-adsorbed diffuse source pollutants and liquid discharges could 

penetrate the soil layer 

L - Soils in which pollutants are unlikely to penetrate the soil layer either because water movement is largely horizontal or 

because they have a large ability to attenuate diffuse source pollutants 

GWPP LEACHING CLASS DESCRIPTION 

The Ground Water Protection Policy classes describe the leaching potential of pollutants through the soil (Hollis, 1991; Palmer et al, 

1995). The likelihood of pollutants reaching ground water is described. Different classes of pollutants are described, including liquid 

discharges adsorbed and non-adsorbed pollutants.


1j. SOIL PARENT MATERIAL 

SOIL PARENT MATERIAL KEY 

130 - Palaeozoic slate, mudstone and siltstone 

131 - Palaeozoic slaty mudstone and siltstone 

57 - Drift from Palaeozoic sandstone. mudstone and shale 

59 - Drift from Palaeozoic slaty mudstone and siltstone 

Page 17 of 58 

SOIL PARENT MATERIAL DESCRIPTION 

Along with the effects of climate, relief, organisms and time, the underlying geology or 'parent material' has a very strong influence 

on the development of the soils of England and Wales. Through weathering, rocks contribute inorganic mineral grains to the soils 

and thus exhibit control on the soil texture. During the course of the creation of the national soil map, soil surveyors noted the parent 

material underlying each soil in England and Wales. It is these general descriptions of the regional geology which is provided in this 

map.


1k. EXPECTED CROPS AND LAND USE 

EXPECTED CROPS AND LAND USE KEY 

Page 18 of 58 

160 - Moorland and grassland habitats, of moderate grazing value; recreation; coniferous woodland; stock rearing and dairyi 

200 - Stock rearing and woodland in uplands; some dairying and cereals in Devon and Cornwall with woodland on slopes. 

211 - Stock rearing on permanent grassland and wet moorland of moderate and good grazing value. 

226 - Stock rearing on wet moorland of moderate grazing value and some permanent grassland; coniferous woodland; recre 

EXPECTED CROPS AND LAND USE DESCRIPTION 

Individual soils are commonly associated with particular forms of land cover and land use. Whilst the soil surveyors were mapping 

the whole of England and Wales, they took careful note of the range of use to which the land was being put. This map shows the 

most common forms of land use found on each soil unit.


1l. NATURAL SOIL FERTILITY 

NATURAL SOIL FERTILITY KEY 

12 - Very low 

5 - Low 

Page 19 of 58 

NATURAL SOIL FERTILITY DESCRIPTION 

Soil fertility can be greatly altered by land management especially through the application of manures, lime and mineral fertilisers. 

What is shown in this map, however, is the likely natural fertility of each soil type. Soils that are very acid have low numbers of 

soil-living organisms and support heathland and acid woodland habitats. These are shown as of very low natural fertility. Soils 

identified as of low natural fertility are usually acid in reaction and are associated with a wide range of habitat types. The moderate 

class contains neutral to slightly acid soils, again with a wide range of potential habitats. Soil of high natural fertility are both 

naturally productive and able to support the base-rich pastures and woodlands that are now rarely encountered. Lime-rich soils 

contain chalk and limestone in excess, and are associated with downland, herb-rich pastures and chalk and limestone woodlands.


1m. SIMPLE TOPSOIL TEXTURE 

SIMPLE TOPSOIL TEXTURE KEY 

1 - Clayey 

2 - Loamy 

3 - Peaty 

4 - Sandy 

Page 20 of 58 

SIMPLE TOPSOIL TEXTURE DESCRIPTION 

Soil texture is a term used in soil science to describe the physical composition of the soil in terms of the size of mineral particles in the 

soil. Specifically, we are concerned with the relative proportions of sand, silt and clay. Soil texture can vary between each soil layer 

or horizon as one moves down the profile. This map indicates the soil texture group of the upper 30 cm of the soil. ‘Light’ soils have 

more sand grains and are described as sandy, while ‘heavy’ soils have few sand grains but a lot of extremely small particles and are 

described as clayey. Loamy soils have a mix of sand, silt and clay-sized particles and are intermediate in character. Soils with a 

surface layer that is dominantly organic are described as Peaty. A good understanding of soil texture can enable better land 

management.


1n. TYPICAL HABITATS 

TYPICAL HABITATS KEY 

17 - Seasonally wet pastures and woodlands 

Page 21 of 58 

18 - Steep acid upland pastures dry heath and moor; bracken gorse and oak woodlands 

6 - Grass moor and heather moor with flush and bog communities in wetter parts 

7 - Grass moor and some heather with flush and bog communities in wetter parts 

TYPICAL HABITATS DESCRIPTION 

There is a close relationship between vegetation and the underlying soil. Information about the types of broad habitat associated 

with each soil type is provided in this map. Soil fertility, pH, drainage and texture are important factors in determining the types of 

habitats which can be established. Elevation above sea level and sometimes even the aspect - the orientation of a hillslope - can 

affect the species present. This map does not take into account the recent land management or any urban development, but 

provides the likely natural habitats assuming good management has been carried out.


2. SOIL ASSOCIATION DESCRIPTIONS 

The following pages describe the following soil map units, (soil associations), in more detail. 

MANOD 611c 


Page 22 of 58 

HAFREN 654a 






The soil associations are described in terms of their texture and drainage properties and potential risks may be identified. The 

distribution of the soils across England and Wales are provided. Further to this, properties of each association’s component soil series 

are described in relation to each other. Lastly, schematic diagrams of each component series are provided for greater understanding 

and in-field verification purposes.


MANOD (611c) 


a. General Description 

Well drained fine loamy or fine silty soils over rock. Shallow soils in places. 

Bare rock locally. Steep slopes common. 

The major landuse on this association is defined as stock rearing and 

woodland in uplands; some dairying and cereals in devon and cornwall with 

woodland on slopes. 

b. Distribution (England & Wales) 

The MANOD association covers 5372km² of England and Wales which 

accounts for 3.55% of the landmass. The distribution of this association is 

shown in Figure 1. Note that the yellow shading represents a buffer to 

highlight the location of very small areas of the association. 

c. Comprising Soil Series 

Multiple soil series comprise a soil association. The soil series of the 

MANOD association are outlined in Table 1 below. In some cases other 

minor soil series are present at a particular site, and these have been 

grouped together under the heading 'OTHER'. We have endevoured to 

present the likelihood of a minor, unnamed soil series occuring in your site 

in Table 1. 

Schematic diagrams of the vertical soil profile of the major constituent soil 

series are provided in Section D to allow easier identification of the particular 

soil series at your site. 

Page 23 of 58 

Figure 1. Association Distribution 

Soil Series Description Area % 

MANOD (Mj) medium loamy material over lithoskeletal mudstone and sandstone or slate 50% 

DENBIGH (Dg) medium loamy material over lithoskeletal mudstone and sandstone or slate 20% 

POWYS (Ph) loamy lithoskeletal mudstone and sandstone or slate 10% 

OTHER other minor soils 20% 

Table 1. The component soil series of the MANOD soil association. Because absolute proportions of the comprising series in this association vary from location to location, 

the national proportions are provided.


MANOD (611c) 


d. MANOD Component Series Profiles 

Page 24 of 58


MANOD (611c) 


Page 25 of 58 

e. Soil Properties 

This section provides graphical summaries of selected attribute data available for the component series in this association. The blue 

bars of the graphs presented in this section describe the range of property values for all soils across England and Wales. 

Superimposed on these graphs are the values for the component soil series in this association. This has been done to provide the 

reader with an understanding of where each property for each series sits within the national context. 







the national proportions are provided. 

e(i). Soil Depth Information and Depths to Important Layers 

Depth to rock A mean depth to bedrock or very stony 

rubble which has been assigned to each soil series 

based on observed and recorded soil 

profiles. 

Depth to gleying, the presence of grey and ochreous 

mottles within the soil, is caused by intermittent 

waterlogging. A mean depth to gleying has been 

assigned to each soil series based on observed and 

recorded soil profiles. The definition of a gleyed layer is 

designed to equate with saturation for at least 30 days in 

each year or the presence of artificial drainage. 

Figure 2. Depth of soil to Rock 

Figure 3. Depth of Soil to Gleying


MANOD (611c) 


e(i). Soil Depth Information and Depths to Important Layers continued 

Depth to slowly permeable layer (downward 

percolation) A mean depth to a layer with lateral 

hydraulic conductivity of


MANOD (611c) 


e(ii). Soil Hydrological Information 

Integrated air capacity (IAC) is the total coarse pore 

space (>60 µm diameter) to 1 m depth. This size of 

pore would normally be air-filled when the soil is fully 

moist but not waterlogged. A large IAC means that 

the soil is well aerated. This will encourage root 

development and, provided near surface soil structure is 

well developed, will allow rainfall to percolate into the 

ground thus mitigating against localised flooding. 

Standard Percentage Runoff (SPR) is the 

percentage of rainfall that causes the short-term 

increase in flow seen at a catchment outlet 

following a storm event. The values associated with 

individual soil series have been calculated from an 

analysis of the relationships between flow data 

and the soils present within the catchment for several 

hundred gauged catchments. 

Base flow index is calculated from daily river flow data 

and expresses the volume of base flow of a river as 

a fraction of the total flow volume. The values associated 

with individual soil series have been calculated from 

an analysis of the relationships between flow data and 

the soils present within the catchment for several 


Figure 6. Integrated Air Capacity 

Page 27 of 58 

Figure 7. Standard Percentage Runoff 

Figure 8. Base Flow Index


MANOD (611c) 


e(iii). Available Water Content 

Page 28 of 58 

Available water content for plants varies depending on a number of factors, including the rooting depth of the plants. Described 

below are differing available water contents for cereals, sugar beet, grass and potato crops, as well as a generic available water value 

to 1 m depth. 

Available water (by crop) Available water content to 1 

m for the specified soil series between suctions of 5 and 

1500kPa. 

Available water for grass represents the water that is 

available to a permanent grass sward that is able to root 

to 100cm depth. 

Figure 9. Available Water (by crop) 

Figure 10. Available Water for Grass


MANOD (611c) 


e(iii). Available Water Content continued 

Available water for cereal represents the water that is 

available to a cereal crop that is able to root to 

120cm depth. 

Available water for Sugar Beet represents the water 

that is available to a sugar beet crop that is able to 

root to 140cm depth. 

Available water for Potatoes represents the water 

that is available to a potato crop that is able to root to 

70cm depth. 

Page 29 of 58 

Figure 11. Available Water for Cereal 

Figure 12. Available Water for Sugar Beet 

Figure 13. Available Water for Potatoes



Loamy permeable upland soils over rock with a wet peaty surface horizon 

and bleached subsurface horizon, often with thin ironpan. Some peat on 

higher ground. Rock and scree locally. 

The major landuse on this association is defined as moorland and grassland 

habitats, of moderate grazing value; recreation; coniferous woodland; stock 

rearing and dairying on improved ground. 


The HAFREN association covers 1530km² of England and Wales which 






HAFREN association are outlined in Table 2 below. In some cases other 




in Table 2. 




Page 30 of 58 

HAFREN (654a) 

Loamy permeable upland soils over rock with a wet peaty surface horizon and bleached subsurface horizon, often with thin 

ironpan. 



HAFREN (HN) loamy material over lithoskeletal mudstone and sandstone or slate 45% 

HIRAETHOG (Hi) loamy material over lithoskeletal mudstone and sandstone or slate 20% 

WILCOCKS (Wo) loamy drift with siliceous stones 10% 


Table 2. The component soil series of the HAFREN soil association. Because absolute proportions of the comprising series in this association vary from location to location, 



Page 31 of 58 

HAFREN (654a) 


ironpan. 

d. HAFREN Component Series Profiles


HAFREN (654a) 

Page 32 of 58 


ironpan. 

















profiles. 











Page 33 of 58 

HAFREN (654a) 


ironpan. 






Page 34 of 58 

HAFREN (654a) 


ironpan. 





























Page 35 of 58 

HAFREN (654a) 


ironpan. 




to 1 m depth. 



1500kPa. 







Page 36 of 58 

HAFREN (654a) 


ironpan. 




120cm depth. 






70cm depth. 






Slowly permeable seasonally waterlogged fine loamy and fine silty soils, 

some with wet peaty surface horizons. 

The major landuse on this association is defined as stock rearing on 

permanent grassland and wet moorland of moderate and good grazing value. 


The BRICKFIELD 1 association covers 458km² of England and Wales which 






BRICKFIELD 1 association are outlined in Table 3 below. In some cases 

other minor soil series are present at a particular site, and these have been 



in Table 3. 




Page 37 of 58 

BRICKFIELD 1 (713e) 




BRICKFIELD (Br) medium loamy drift with siliceous stones 30% 


GREYLAND (gJ) medium loamy over clayey drift with siliceous stones 15% 

CEGIN (Ca) medium silty drift with siliceous stones 10% 


Table 3. The component soil series of the BRICKFIELD 1 soil association. Because absolute proportions of the comprising series in this association vary from location to 

location, the national proportions are provided.


d. BRICKFIELD 1 Component Series Profiles 

Page 38 of 58 


Slowly permeable seasonally waterlogged fine loamy and fine silty soils, some with wet peaty surface horizons.



Page 39 of 58 














location, the national proportions are provided. 





profiles. 


































Page 41 of 58 














Page 42 of 58 





to 1 m depth. 



1500kPa. 










120cm depth. 

Page 43 of 58 








70cm depth. 





WILCOCKS 2 (721d) 



Slowly permeable seasonally waterlogged loamy upland soils with a peaty 

surface horizon. Some very acid peat soils. 

The major landuse on this association is defined as stock rearing on wet 

moorland of moderate grazing value and some permanent grassland; 

coniferous woodland; recreation. 


The WILCOCKS 2 association covers 667km² of England and Wales which 






WILCOCKS 2 association are outlined in Table 4 below. In some cases 




in Table 4. 




Page 44 of 58 




CROWDY (CJ) humified peat 15% 

WINTER HILL (WH) mixed eriophorum and sphagnum peat 15% 



Table 4. The component soil series of the WILCOCKS 2 soil association. Because absolute proportions of the comprising series in this association vary from location to 





d. WILCOCKS 2 Component Series Profiles 

Page 45 of 58




Page 46 of 58 


















profiles. 













































Page 48 of 58 







Page 49 of 58 



to 1 m depth. 



1500kPa. 












120cm depth. 






70cm depth. 

Page 50 of 58 





3. TOPSOIL ELEMENT BACKGROUND LEVELS 

TOPSOIL ELEMENT BACKGROUND LEVELS KEY 

- NSI sample points 

- Report area 

- 15 km radius - local area 

- 50 km radius - regional area 

TOPSOIL ELEMENT BACKGROUND LEVELS DESCRIPTION 

Page 51 of 58 

The National Soil Inventory (NSI) covers England and Wales on a 5 km grid and provides detailed information for each intersect of the 

grid. Collectively NSI data are statistically representative of England and Wales soils. The original sampling was undertaken around 

1980 and there were partial resamplings in the mid-1990s. The most up-to-date data is presented here. 

Analysis of the NSI samples provides detailed measurements of over 20 elements from the soils, in addition to pH. This data is 

summarised over three areas to provide you with an understanding of how your site, and your data for it, sits within the local, regional 

and national context. 

Where available, the soil element levels are compared with the Soil Guideline Values and where a soil sample we have analysed has 

been found in excess of the SGV guidelines for "residential with plant uptake" land, this is displayed in red in the tables which follow. 

SGV levels are provided for the following elements: lead, selenium, nickel, mercury, chromium, cadmium and arsenic. 

In the following pages, a number of analyses of the topsoil are provided. The majority of analyses have been performed on the full 

compliment of sample points, however, in some areas, for some elements, only a few samples were analysed as part of subsequent 

programmes. In order to present the full suite of possible datasets, and accurately convey the validity of the data, the number of actual 

measured samples is stated for each analysis. Care should be taken where the number of samples is disproportionately low.


3a. Analyses Within a 15 km Radius (26 Sample Points) 

Page 52 of 58 

ANALYSES SAMPLES MEAN MIN MAX ST. DEV 

pH (PH) 26 5.1 3.6 6.3 0.9 

Carbon (CARBON) 26 11.0 2.5 54.5 14.0 

Aluminium (AL_ACID) 26 28,549.5 2,061.0 42,056.0 12,526.4 

Arsenic (AS_ACID) 14 3.7 0.8 5.6 1.5 

Barium (BA_ACID) 26 181.2 23.0 505.0 121.9 

Calcium (CA_ACID) 26 2,051.0 152.0 7,296.0 1,772.7 

Cadmium (CD_ACID) 26 0.7 0.0 2.1 0.5 

Cadmium (Extractable) (CD_EDTA) 26 0.2 0.0 0.6 0.1 

Cobalt (CO_ACID) 26 9.4 0.4 16.7 5.6 

Cobalt (Extractable) (CO_EDTA) 26 0.7 0.1 2.1 0.5 

Chromium (CR_ACID) 26 46.5 2.1 133.3 33.3 

Copper (CU_ACID) 26 17.2 4.3 32.8 6.7 

Copper (Extractable) (CU_EDTA) 26 4.3 1.4 12.9 2.8 

Flouride (F_ACID) 21 43.5 0.0 131.2 38.9 

Iron (FE_ACID) 26 33,474.6 2,862.0 56,320.0 15,058.5 

Mercury (HG_ACID) 13 0.0 0.0 0.1 0.0 

Potassium (K_ACID) 26 5,319.3 507.0 9,358.0 2,492.9 

Potassium (Extractable) (K_NITRATE) 26 95.2 38.0 215.0 36.0 

Magnesium (MG_ACID) 26 4,755.6 514.0 11,067.0 3,254.7 

Magnesium (Extractable) (MG_NITRATE) 26 90.3 34.0 276.0 66.4 

Manganese (MN_ACID) 26 738.8 21.0 1,903.0 568.4 

Manganese (Extractable) (MN_EDTA) 26 84.9 3.0 338.0 75.9 

Molybdenum (MO_ACID) 24 2.2 0.0 17.0 3.3 

Sodium (NA_ACID) 26 289.8 97.0 720.0 126.0 

Nickel (NI_ACID) 26 22.1 1.3 44.4 13.4 

Nickel (Extractable) (NI_EDTA) 26 0.9 0.3 2.1 0.5 

Phosphorus (P_ACID) 26 1,073.3 507.0 2,541.0 433.8 

Phosphorus (Extractable) (P_OLSEN) 26 21.9 8.0 93.0 17.6 

Lead (PB_ACID) 26 65.8 37.0 143.0 28.5 

Lead (Extractable) (PB_EDTA) 26 16.9 6.3 36.4 8.2 

Selenium (SE_ACID) 14 0.5 0.0 1.2 0.4 

Strontium (SR_ACID) 26 15.2 0.0 30.0 8.5 

Vanadium (V_ACID) 24 35.2 0.0 62.9 19.8 

Zinc (ZN_ACID) 26 84.7 23.0 173.0 40.7 

Zinc (Extractable) (ZN_EDTA) 26 4.8 1.1 15.4 3.0 

for units, see Analyses Definitions (p56)


3b. Analyses Within a 50 km Radius (234 Sample Points) 

Page 53 of 58 


pH (PH) 229 5.1 3.3 7.6 0.9 

Carbon (CARBON) 233 11.9 1.0 57.4 14.3 



Barium (BA_ACID) 232 155.7 11.0 672.0 94.4 




Cobalt (CO_ACID) 232 11.8 0.4 321.8 24.1 



Copper (CU_ACID) 232 18.9 1.3 96.3 10.7 



Iron (FE_ACID) 232 29,458.2 2,862.0 83,515.0 15,636.8 



Potassium (Extractable) (K_NITRATE) 228 131.3 25.0 1,450.0 120.1 



Manganese (MN_ACID) 232 1,133.8 16.0 35,738.0 2,779.9 

Manganese (Extractable) (MN_EDTA) 232 129.4 1.0 2,347.0 207.5 


Sodium (NA_ACID) 232 405.4 86.0 2,209.0 337.3 

Nickel (NI_ACID) 232 19.7 1.3 71.7 13.5 


Phosphorus (P_ACID) 232 935.2 87.0 2,541.0 397.9 


Lead (PB_ACID) 232 113.3 24.0 2,388.0 236.6 

Lead (Extractable) (PB_EDTA) 232 40.4 3.6 1,322.9 120.6 




Zinc (ZN_ACID) 232 97.0 12.0 2,125.0 151.7 




3c. National Analyses (5686 Sample Points) 

Page 54 of 58 


pH (PH) 5,630 6.0 3.1 9.2 1.3 

Carbon (CARBON) 5,672 6.1 0.1 61.5 8.9 

Aluminium (AL_ACID) 5,677 26,775.3 491.0 79,355.0 12,772.2 

Arsenic (AS_ACID) 2,729 4.6 0.0 110.0 5.7 

Barium (BA_ACID) 5,677 150.0 7.0 3,840.0 159.5 

Calcium (CA_ACID) 5,677 13,768.7 0.0 339,630.0 37,785.0 

Cadmium (CD_ACID) 5,677 0.7 0.0 40.9 1.0 

Cadmium (Extractable) (CD_EDTA) 5,655 0.5 0.0 85.0 3.0 

Cobalt (CO_ACID) 5,677 10.6 0.0 567.0 13.7 

Cobalt (Extractable) (CO_EDTA) 5,655 1.1 0.0 26.5 1.2 

Chromium (CR_ACID) 5,677 38.9 0.0 2,339.8 43.7 

Copper (CU_ACID) 5,677 22.6 0.0 1,507.7 36.8 

Copper (Extractable) (CU_EDTA) 5,655 6.4 0.3 431.4 11.1 

Flouride (F_ACID) 3,320 58.5 0.0 6,307.9 186.2 

Iron (FE_ACID) 5,677 28,147.8 395.0 264,405.0 16,510.5 

Mercury (HG_ACID) 2,159 0.1 0.0 2.4 0.2 

Potassium (K_ACID) 5,677 4,727.7 60.0 23,905.0 2,700.2 

Potassium (Extractable) (K_NITRATE) 5,609 182.0 6.0 2,776.0 151.6 

Magnesium (MG_ACID) 5,677 3,648.1 0.0 62,690.0 3,284.1 

Magnesium (Extractable) (MG_NITRATE) 5,609 146.0 1.0 1,601.0 147.5 

Manganese (MN_ACID) 5,677 777.0 3.0 42,603.0 1,068.8 

Manganese (Extractable) (MN_EDTA) 5,654 159.4 0.0 3,108.0 188.6 

Molybdenum (MO_ACID) 4,417 0.9 0.0 56.3 2.0 

Sodium (NA_ACID) 5,677 323.3 17.0 25,152.0 572.3 

Nickel (NI_ACID) 5,677 25.4 0.0 1,350.2 29.2 

Nickel (Extractable) (NI_EDTA) 5,655 1.6 0.1 73.2 2.0 

Phosphorus (P_ACID) 5,677 792.1 41.0 6,273.0 433.9 

Phosphorus (Extractable) (P_OLSEN) 5,604 27.4 0.0 534.0 25.5 

Lead (PB_ACID) 5,677 73.3 0.0 17,365.0 280.6 

Lead (Extractable) (PB_EDTA) 5,655 27.8 1.2 6,056.5 119.7 

Selenium (SE_ACID) 2,729 0.6 0.0 22.8 0.8 

Strontium (SR_ACID) 5,677 42.3 0.0 1,445.0 67.8 

Vanadium (V_ACID) 4,428 41.0 0.0 854.4 33.9 

Zinc (ZN_ACID) 5,677 90.2 0.0 3,648.0 104.4 

Zinc (Extractable) (ZN_EDTA) 5,655 9.6 0.5 712.0 24.6 



SOIL GUIDELINE VALUES (SGV) 

Page 55 of 58 

Defra and the Environment Agency have produced soil guideline values (SGVs) as an aid to preliminary assessment of potential 

risk to human health from land that may be contaminated. SGVs represent ‘intervention values’, which, if exceeded, act as 

indicators of potential unacceptable risk to humans, so that more detailed risk assessment is needed. 

The SGVs were derived using the Contaminated Land Exposure Assessment (CLEA) model for four land uses: 

1. residential (with plant uptake / vegetable growing) 

2. residential (without vegetable growing) 

3. allotments 

4. commercial / industrial 

SGVs are only designed to indicate whether further site-specific investigation is needed. Where a soil guideline value is exceeded, 

it does not mean that there is necessarily a chronic or acute risk to human health. 

The values presented in this report represent those from a number of sample points ( given in the "Samples" column in each 

table) providing local, regional and national background levels. Figures which appear in red indicate that a bulked sample from 

20m surrounding a sample point, has at a past date, exceeded the SGV for the ‘residential with plant uptake’ land use. 

It is always advisable to perform site specific investigations. 

More details on all the SGVs can be found on the Environment Agency Website. 

All units are mg/kg which is equivalent to parts per million (ppm) 

SUBSTANCE 

LEAD 

SELENIUM 

NICKEL 

MERCURY 

CHROMIUM 

CADMIUM (pH 6) 



ARSENIC 

RESIDENTIAL WITH 

PLANT UPTAKE 

450 

35 

50 

8 

130 

1 

2 

8 

20 

RESIDENTIAL WITHOUT 

PLANT UPTAKE 

450 

260 

75 

15 

200 

30 

30 

30 

20 

ALLOTMENTS 

450 

35 

50 

8 

130 

1 

2 

8 

20 

COMMERCIAL / 

INDUSTRIAL 

750 

8000 

5000 

480 

5000 

1400 

1400 

1400 

500


ANALYSES DEFINITIONS 

PH (pH) 

pH of soil measure after shaking 10ml of soil for 15 minutes with 25ml of water 

Page 56 of 58 

CARBON (Carbon) 

Organic Carbon (% by wt) measured either by loss-on-ignition for soils estimated to contain more than about 20% organic carbon or by dichromate 

digestion. 

AL_ACID (Aluminium) 

Total Aluminium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

AS_ACID (Arsenic) 

Total Arsenic concentration (mg/kg) determined by Hydride Atomic Absorption Spectrometry (AAS), extracted into hydrochloric acid after digestion with 

nitric acid and ashing with magnesium nitrate 

BA_ACID (Barium) 

Total Barium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CA_ACID (Calcium) 

Total Calcium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CD_ACID (Cadmium) 

Total Cadmium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CD_EDTA (Cadmium Extractable) 

Extractable Cadmium concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 

0.05M EDTA at pH 7.0 for 1h at 20 deg. C and then filtering 

CO_ACID (Cobalt) 

Total Cobalt concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CO_EDTA (Cobalt Extractable) 

Extractable Cobalt concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 


CR_ACID (Chromium) 

Total Chromium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CU_ACID (Copper) 

Total Copper concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CU_EDTA (Copper Extractable) 

Extractable Copper concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 


F_ACID (Flouride) 

Flouride extracted with 1mol / l sulphuric acid and determined by Ion Selective Electrode (ISE) 

FE_ACID (Iron) 

Total Iron concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

HG_ACID (Mercury) 

Total Mercury concentration (mg/kg) determined by Hydride Atomic Absorption Spectrometry (AAS), digested in a nitric/sulphuric acid mixture 

K_ACID (Potassium) 

Total Potassium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

K_NITRATE (Potassium Extractable) 

Extractable Potassium concentration (mg/l) determined by shaking 10ml of air dry soil with 50ml of 1.0M ammonium nitrate for 30mins, filtering and then 

measuring the concentration by flame photometry


ANALYSES DEFINITIONS continued 

Page 57 of 58 

MG_ACID (Magnesium) 

Total Magnesium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

MG_NITRATE (Magnesium Extractable) 

Extractable Magnesium concentration (mg/l) determined by shaking 10ml of air dry soil with 50ml of 1.0M ammonium nitrate for 30mins, filtering and then 

measuring the concentration by flame photometry 

MN_ACID (Manganese) 

Total Manganese concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

MN_EDTA (Manganese Extractable) 

Extractable Manganese concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml 

of 0.05M EDTA at pH 7.0 for 1h at 20 deg. C and then filtering 

MO_ACID (Molybdenum) 

Total Molybdenum concentration (mg/kg) determined by Atomic Adsorption Spectrometyr (AAS) in an aqua regia digest 

MO_EDTA (Molybdenum Extractable) 

Extractable Molybdenum concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml 


NA_ACID (Sodium) 

Total Sodium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

NI_ACID (Nickel) 

Total Nickel concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

NI_EDTA (Nickel Extractable) 

Extractable Nickel concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 


P_ACID (Phosphorus) 

Total Phosphorus concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

P_OLSON (Phosphorous Extractable) 

Extractable Phosphorus concentration (mg/l) determined by shaking 5ml of air dry soil with 100ml of 0.5M sodium bicarbonate for 30mins at 20 deg.C, 

filtering and then measuring the absorbance at 880 nm colorimetrically with acid ammonium molybdate solution 

PB_ACID (Lead) 

Total Lead concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

PB_EDTA (Lead Extractable) 

Extractable Lead concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 


SE_ACID (Selenium) 

Total Selenium concentration (mg/kg) determined by Hydride Atomic Absorption Spectrometry (AAS), extracted into hydrochloric acid after digestion with 


SR_ACID (Strontium) 

Total Strontium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

V_ACID (Vanadium) 

Total Vanadium concentration (mg/kg) determined by Atomic Adsorption Spectrometyr (AAS) in an aqua regia digest 

ZN_ACID (Zinc) 

Total Zinc concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

ZN_EDTA (Zinc Extractable) 

Extractable Zinc concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 0.05M 

EDTA at pH 7.0 for 1h at 20 deg. C and then filtering


REFERENCES 

Page 58 of 58 

AVERY, B.W. (1973). Soil classification in the Soil Survey of England and Wales. Journal of Soil Science, 24, 324-338. 

AVERY, B.W., (1980). Soil classification for England and Wales. Soil Survey Technical Monograph No.14, Harpenden, UK. 

BOORMAN, D.B, HOLLIS, J.M. and LILLEY, A. (1995). Hydrology of Soil Types: a hydrologically-based classification of the soils of the UK. 

Institute of Hydrology Report No.126, Wallingford, UK. 

CLAYDEN, B and HOLLIS, J.M. (1984). Critieria for Differentiating Soil Series. Soil Survey Technical Monograph No.17, pp159. Harpenden, 

UK. 

HALLETT, S.H., KEAY, C.A., JARVIS, M.G. and JONES, R.J.A. (1994). INSURE: Subsidence risk assessment from soil and climate data. 

Proceedings of the Association for Geographic Information (AGI). National Conference Markets for Geographic Information. Birmingham. 

16.2.1 - 16.2.7. 

HOLLIS, J.M. (1991). Mapping the vulnerability of aquifers and surface waters to pesticide contamination at the national and regional scale. 

In: Pesticides in Soils and Water, BCPC Monograph No.47, 165-174. 

HOLLIS, J.M., KEAY, C.A., HALLETT, S. H., GIBBONS, J.W. and COURT, A.C. (1995). Using CatchIS to assess the risk to water resources 

from diffusely applied pesticides. In: British Crop Protection Council monograph No. 62: Pesticide movement to water, 345-350 

JARVIS, M.G and HEDGES, M.R. (1994). Use of soil maps to predict the incidence of corrosion and the need for iron mains renewal. Journal 

of the Institution of Water and Environmental Management 8, (1) 68-75. 

PALMER, R.C., HOLMAN, I.P., ROBINS, N.S. and LEWIS, M.A. (1995). Guide to groundwater vulnerability mapping in England and Wales. 

National Rivers Authority R and D Note 578/1/ST. 

To view the glossary visit: www.landis.org.uk/sitereporter/GLOSSARY.pdf 

For a list of further reading visit: www.landis.org.uk/sitereporter/FURTHER_READING.pdf 

For more information visit: www.landis.org.uk/reports 

GIS DATASETS: 

The GIS data used in the creation of this report is available to lease for use in projects. 

To learn more about, or acquire the GIS datasets used in the creation of this report, please contact the National Soil Resources Institute: 

nsridata@cranfield.ac.uk 

+44 (0) 1234 75 2978 


Cranfield University 

Bedfordshire 

MK43 0AL 

United Kingdom 

www.landis.org.uk

National Soil 

Resources Institute 

Soils Site Report 

Full Soil Report 

Clocaenog South 

National Grid Reference: SJ0150052000 

Easting: 301500 

Northing: 352000 

Site Area: 4km x 4km 

Prepared by 

authorised user: 

Heather Eadie 

ERM Ltd 

16 July 2009 

© Cranfield University (NSRI) 2008. All rights reserved.


Citations 

Citations to this report should be made as follows: 

Disclaimer 

Page 2 of 58 

National Soil Resources Institute (2009) Full Soils Site Report for location 301500E, 

352000N, 4km x 4km, National Soil Resources Institute, Cranfield University. 

Accessed via https://www.landis.org.uk/sitereporter/. 

The report, modules and risk maps have been prepared by Cranfield University for 

you, the client. Whilst every care has been taken by Cranfield University to ensure 

the accuracy and completeness of the reports, modules and risk maps, the client 

must recognise that as with any such reports, modules and risk maps errors are 

possible through no fault of Cranfield University and as such the parties give no 

express or implied representations or warranty as to: 

( i ) the quality or fitness for any particular purpose of the report, modules or risk 

maps contained herein or of any design, workmanship, materials or parts used in 

connection therewith or correspondence with regard to any description or sample; 

or 

(ii) the accuracy, sufficiency or completeness of the report modules or risk maps 

provided herewith. In particular, there are hereby expressly excluded all 

conditions, warranties and other terms which might otherwise be implied (whether 

by common law, by statute or otherwise) as to any of the matters set out in 

paragraphs (i) and (ii) above. 

Cranfield University, its employees, servants and agents shall accept no liability for 

any damage caused directly or indirectly by the use of any information contained 

herein and without prejudice to the generality of the foregoing, by any 

inaccuracies, defects or omissions in the report, modules or risk maps provided.


About this report 

Page 3 of 58 

This Soils Site Report identifies and describes the properties and capacities of the 

soil at your specified location as recorded in the 1:250,000 scale National Soil Map 

for England and Wales. It has been produced by Cranfield University’s National 

Soil Resources Institute. 

The National Soil Map represents the most accurate comprehensive source of 

information about the soil at the national coverage in England and Wales. It maps 

the distribution of soil mapping units (termed soil associations) which are defined 

in terms of the main soil types (or soil series) that were recorded for each soil 

association during field soil survey. Each soil association is named after its 

principal soil series and these bear the location name from where they were first 

described (e.g. Windsor). Each of these soil associations have differing 

environmental characteristics (physical, chemical and biological) and it is by 

mapping these properties that the range of thematic maps in this report have 

been produced. 

Soil types and properties vary locally, as well as at the landscape scale. It is not 

possible to identify precisely the soil conditions at a specific location without first 

making a site visit. We have therefore provided you with information about the 

range of soil types we have identified at and around your selected location. 

Schematic diagrams are also provided to aid accurate identification of the soil 

series at your site. 

Whilst an eight-figure national grid reference should be accurate to within 100m, a 

single rural Postcode can cover a relatively large geographical area. Postcodes 

can therefore be a less precise basis for specifying a location. The maps indicate 

the bounded area the reports relate to. 

Your Soils Site Report will enable you to: 

• identify the soils most likely to be present at and immediately around your 

specified location; 

• understand the patterns of soil variation around your location and how these 

correlate with changes in landscape; 

• identify the nature and properties of each soil type present within the area; 

• understand the relevant capacities and limitations of each of the soils and how 

these might impact on a range of factors such as surface water quality. 

Provided that this Soils Site Report is not modified in any way, you may reproduce 

it for a third-party. 

For more information visit www.landis.org.uk/reports


Table of Contents 

Page 4 of 58 

1. SOIL THEMATIC MAPS ------------------------------------------------------------------------------------------------------------- 6 

a. Soil Spatial Distribution ------------------------------------------------------------------------------------------------------- 7 

b. Hydrology of Soil Type (HOST) ---------------------------------------------------------------------------------------------- 8 

c. Ground Movement Potential ------------------------------------------------------------------------------------------------ 9 

d. Flood Vulnerability ----------------------------------------------------------------------------------------------------------- 11 

e. Risk of Corrosion to Ferrous Iron ------------------------------------------------------------------------------------------- 12 

f. Pesticide Leaching Risk ------------------------------------------------------------------------------------------------------ 13 

g. Pesticide Runoff Risk -------------------------------------------------------------------------------------------------------- 14 

h. Hydrogeological Rock Type ------------------------------------------------------------------------------------------------ 15 

i. Ground Water Protection Policy (GWPP) Leaching ---------------------------------------------------------------------- 16 

j. Soil Parent Material ---------------------------------------------------------------------------------------------------------- 17 

k. Expected Crops and Land Use --------------------------------------------------------------------------------------------- 18 

l. Natural Soil Fertility ----------------------------------------------------------------------------------------------------------- 19 

m. Simple Topsoil Texture ----------------------------------------------------------------------------------------------------- 20 

n. Typical Habitats ------------------------------------------------------------------------------------------------------------- 21 

2. SOIL ASSOCIATION DESCRIPTIONS -------------------------------------------------------------------------------------------- 

MANOD 611c 









HAFREN 654a 


















22



Page 5 of 58 









3. TOPSOIL ELEMENT BACKGROUND LEVELS ------------------------------------------------------------------------------------a. 

Analyses Within a 15km Radius -------------------------------------------------------------------------------------------b. 

Analyses Within a 50km Radius -------------------------------------------------------------------------------------------c. 

National Analyses ----------------------------------------------------------------------------------------------------------- 

REFERENCES ------------------------------------------------------------------------------------------------------------------------- 58 

51 

52 

53 

54


1. SOIL THEMATIC MAPS 

Page 6 of 58 

This section contains a series of maps of the area surrounding your selected location, based on the 1:250,000 scale National Soil Map, 

presenting a number of thematic maps relating to the characteristics of the soils. These provide an overview of the nature and condition of 

the local soil conditions. It is these conditions that may be used to infer the response of an area to certain events (with the soil as a receptor), 

such as pollution contamination from a chemical spill, or an inappropriate pesticide application and the likelihood of these materials passing 

though the soil to groundwater. Other assessments provide an insight into the way a location may impact, by corrosive attack or ground 

movement, upon structures or assets within the ground, for example building or engineering foundations or pipes and street furniture. 

Soil is a dynamic environment with many intersecting processes, chemical, physical and biological at play. Even soils ‘sealed’ over by 

concrete and bitumen are not completely dormant. The way soils respond to events and actions can vary considerably according to the 

properties of the soil as well as other related factors such as land-use, vegetation, topography and climate. There are many threats facing 

our national soil resource today and forthcoming legislation such as the proposed Soil Framework Directive (SFD) (COM(2006) 232) will seek 

to identify measures aimed towards soil protection and ensuring the usage of soils in the most sustainable way. This report is therefore a 

useful snapshot of the soil properties for your given area, providing a summary of a broad range of ground conditions.


1a. SOILS - SPATIAL DISTRIBUTION 

SOIL ASSOCIATION MAP UNIT KEY 

MANOD 611c 


Page 7 of 58 

HAFREN 654a 






Soil associations represent a group of soil series (soil types) which are typically found occurring together, associated in the landscape 

(Avery, 1973; 1980; Clayden and Hollis, 1984). Soil associations may occur in many geographical locations around the country where 

the environmental conditions are comparable. For each of these soil associations, a collection of soil types (or soil series) are recorded 

together with their approximate proportions within the association. Soil associations have codes as well as textual names, thus code 

‘554a’ refers to the ‘Frilford’ association. Where a code is prefixed with ‘U’, the area is predominantly urbanised (e.g. ‘U571v’). The soil 

associations for your location, as mapped above, are described in more detail in Section 2: Soil Association Descriptions.


1b. HYDROLOGY OF SOIL TYPE (HOST) 

HYDROLOGY OF SOIL TYPE KEY 

Page 8 of 58 

15 - Permanently wet, peaty topped upland soils over relatively free draining permeable rocks 

17 - Relatively free draining soils with a large storage capacity over hard impermeable rocks with no storage capacity 

24 - Slowly permeable, seasonally waterlogged soils over slowly permeable substrates with negligible storage capacity 

26 - Permanently wet, peaty topped upland soils over slowly permeable substrates with negligible storage capacity 

HOST CLASS DESCRIPTION 

The Hydrology of Soil Types (HOST) classification describes the dominant pathways of water movement through the soil and, where 

appropriate, the underlying substrate. Eleven drainage models are defined according to the permeability of the soil and its substrate 

and the depth to a groundwater table, where one is present (Boorman et al,1995). These are further subdivided into 29 HOST classes 

to which all soil series have been assigned. These classes identify the way soil water flows are partitioned, with water passing over, 

laterally through, or vertically down the soil column. Analysis of the river hydrograph and the extent of soil series for several hundred 

gauged catchments allowed mean values for catchment hydrological variables to be identified for each HOST class, The HOST 

classification is widely used to predict river flows and the frequency and severity of flood events and also to model the behaviour of 

diffuse pollutants (Hollis et al, 1995).


1c. GROUND MOVEMENT POTENTIAL 

GROUND MOVEMENT POTENTIAL KEY 

1 - Very low 

2 - Low 

3 - Moderate 

4 - High 

5 - Very high 

Page 9 of 58 

* If a High class is starred, a ‘Very High’ ground movement potential is likely to be achieved if these soils are drained to an effective 

depth of at least two metres. 

GROUND MOVEMENT POTENTIAL DESCRIPTION 

Clay-related ground movement is the most widespread cause of foundation failure in the UK and is linked to seasonal swelling and 

shrinkage of the clay. The content of clay within the soils of your selected area has therefore a direct bearing upon the likelihood of 

ground movement. 

Among the inorganic particles that constitute the solid component of any soil, clay particles are the smallest and defined as being 


Page 10 of 58 

also takes place from soil and plant structures, and the combination of evaporation from surfaces and transpiration by plants and trees 

is termed evapotranspiration. Thus, the layer of soil material down to 2m depth into which plants will root is critical when assessing the 

vulnerability of land to subsidence. 

Whenever soil moisture is continuously being replenished by rainfall, the soil moisture reserves will be unaffected by the removal of 

moisture by plants as there is no net loss. However, in many parts of Britain, particularly in the south and east, summer rainfall is small 

and is exceeded by evapotranspiration. Water reserves are then not sufficiently replenished by rainfall and so a soil moisture deficit 

develops. The water removed from a clayey soil by evapotranspiration leads to a reduction in soil volume and the consequent shrinkage 

causes stress in the soil materials leading in turn to stress on building foundations that are resting in the soil (Hallett, et al, 1994). 

The foundations themselves may then move and thus cause damage to building structures. This problem can be exacerbated by the 

fact that the soil beneath the structure may not dry out uniformly, so that any lateral pressure exerted on the building foundation is made 

effectively greater. This assessment identifies the likelihood of soil conditions being prone to ground movement given these other 

factors.


1d. FLOOD VULNERABILITY 

FLOOD VULNERABILITY CLASS KEY 

0 - Major risk 

1 - Minor risk 

Page 11 of 58 

FLOOD VULNERABILITY DESCRIPTION 

The inundation of properties by flood water can occur in a number of circumstances. Surface run-off can collect on low-lying land from 

upslope following heavy rainfall. More commonly rivers, lakes and/or the sea extend beyond their normal limits as a result of prolonged 

or intense rainfall, unusually high tides and/or extreme wind events. Water damage to properties and their contents is compounded by 

the deposition of sediment suspended in the flood waters. The spatial distribution of such waterborne sediment (or alluvium as defined 

in soil science) is one basis upon which land that has been subject to historical flooding can be mapped, and this forms a basis for 

present-day flooding risk assessment. 

Both riverine and marine alluvium are identified as distinct soil parent materials within the British soil classifications. Combining soil map 

units that are dominated by soil series developed in alluvium across Great Britain identifies most of the land that is vulnerable to 

flooding. This assessment does not account for man-made flood defence measures, showing instead the areas where once water has 

stood.


1e. RISK OF CORROSION TO FERROUS IRON 

RISK OF CORROSION TO FERROUS IRON KEY 

1 - Non-aggressive 

2 - Slightly Aggressive 

3 - Moderately Aggressive 

4 - Highly Aggressive 

5 - Very highly Aggressive 

6 - Impermeable Rock 

Page 12 of 58 

* If a class is starred, it is assumed that there are moderate amounts of sulphate in the soil. If there is abundant sulphate present, the 

soil may be one class more aggressive. Conversely, if there is very little sulphate, the soil may be one class less aggressive to 

buried ferrous iron. 

RISK OF CORROSION TO FERROUS IRON DESCRIPTION 

Buried iron pipes and other infrastructure corrode at rates that are influenced by soil conditions (Jarvis and Hedges, 1994). Soil acidity, 

sulphide content, aeration and wetness all influence the corrosivity of the soil. These factors are used to map 5 major classes of relative 

corrosivity.


1f. PESTICIDE LEACHING RISK 

PESTICIDE LEACHING CLASS KEY 

I1n - Deep loamy soils over hard non-porous rocks - no groundwater present 

L p - Upland peaty soils over a variety of subsrtates, some with deep groundwater 

Page 13 of 58 

L q - Impermeable soils over soft substrates of low or negligible storage capacity that sometimes conceal groundwater 

bearing rocks at depth 

PESTICIDE LEACHING CLASS DESCRIPTION 

The natural permeability and water regime of soils are influential in determining the fate and behaviour of pesticides applied to the crop 

and soil surface (Hollis et al, 1995). A system of vulnerability assessment was devised as part of the national system for Policy and 

Practice for the Protection of Groundwater. This divided soils into three primary vulnerability classes. 

H - Soils of high leaching capacity with little ability to attenuate non-adsorbed pesticide leaching which leave underlying groundwater 

vulnerable to pesticide contamination. 

I – Soils of intermediate leaching capacity with a moderate ability to attenuate pesticide leaching. 

L - Soils of low leaching capacity through which pesticides are unlikely to leach. 

The primary classes have been further subdivided into nearly forty subclasses. These subclasses, with their descriptions, are mapped 

above. These classes do not account for differences in land cultivation, which can also have a significant impact on pesticide behaviour.


1g. PESTICIDE RUNOFF RISK 

PESTICIDE RUNOFF RISK KEY 

Page 14 of 58 

P2h - Upland peaty soils with high or very high run-off potential. Not normally farmed and probably with a high adsorption 

potential 

S2m - Soils with high run-off potential but moderate adsorption potential 

S3m - Soils with moderate run-off potential and moderate adsorption potential 

PESTICIDE RUNOFF RISK DESCRIPTION 

The physical properties and natural water regime of soils influence the speed and extent of lateral water movement over and through 

the soil at different depths (Hollis et al, 1995). At as result, soils can be classed according to the potential for pesticide run-off. Five 

runoff potential classes are identified for mineral soils and a further two for peat soils. The mineral soil classes are further subdivided 

according to the potential for pesticide adsorption.


1h. HYDROGEOLOGICAL ROCK TYPE 

HYDROGEOLOGICAL ROCK TYPE KEY 

22 - till and compact Head 

7 - hard, but deeply shattered non-arenaceous rocks 

Page 15 of 58 

HYDROGEOLOGICAL ROCK TYPE DESCRIPTION 

The hydrogeological classification of the soil parent materials provides a framework for distinguishing between soil substrates according 

to their general permeability and whether they are likely to overlie an aquifer. Every soil series has been assigned one of the 32 

substrate classes and each of these is characterised according to its permeability (being characterised as permeable, slowly 

permeable or impermeable). For further information, see Boorman et al (1995).


1i. GROUND WATER PROTECTION POLICY (GWPP) LEACHING 

GWPP LEACHING CLASS KEY 

Page 16 of 58 

I1 - Soils of intermediate leaching potential which have a moderate ability to attenuate a wide range of diffuse source 

pollutants but in which it is possible that some non-adsorbed diffuse source pollutants and liquid discharges could 

penetrate the soil layer 

L - Soils in which pollutants are unlikely to penetrate the soil layer either because water movement is largely horizontal or 

because they have a large ability to attenuate diffuse source pollutants 

GWPP LEACHING CLASS DESCRIPTION 

The Ground Water Protection Policy classes describe the leaching potential of pollutants through the soil (Hollis, 1991; Palmer et al, 

1995). The likelihood of pollutants reaching ground water is described. Different classes of pollutants are described, including liquid 

discharges adsorbed and non-adsorbed pollutants.


1j. SOIL PARENT MATERIAL 

SOIL PARENT MATERIAL KEY 

130 - Palaeozoic slate, mudstone and siltstone 

131 - Palaeozoic slaty mudstone and siltstone 

57 - Drift from Palaeozoic sandstone. mudstone and shale 

59 - Drift from Palaeozoic slaty mudstone and siltstone 

Page 17 of 58 

SOIL PARENT MATERIAL DESCRIPTION 

Along with the effects of climate, relief, organisms and time, the underlying geology or 'parent material' has a very strong influence 

on the development of the soils of England and Wales. Through weathering, rocks contribute inorganic mineral grains to the soils 

and thus exhibit control on the soil texture. During the course of the creation of the national soil map, soil surveyors noted the parent 

material underlying each soil in England and Wales. It is these general descriptions of the regional geology which is provided in this 

map.


1k. EXPECTED CROPS AND LAND USE 

EXPECTED CROPS AND LAND USE KEY 

Page 18 of 58 

160 - Moorland and grassland habitats, of moderate grazing value; recreation; coniferous woodland; stock rearing and dairyi 

200 - Stock rearing and woodland in uplands; some dairying and cereals in Devon and Cornwall with woodland on slopes. 

211 - Stock rearing on permanent grassland and wet moorland of moderate and good grazing value. 

226 - Stock rearing on wet moorland of moderate grazing value and some permanent grassland; coniferous woodland; recre 

EXPECTED CROPS AND LAND USE DESCRIPTION 

Individual soils are commonly associated with particular forms of land cover and land use. Whilst the soil surveyors were mapping 

the whole of England and Wales, they took careful note of the range of use to which the land was being put. This map shows the 

most common forms of land use found on each soil unit.


1l. NATURAL SOIL FERTILITY 

NATURAL SOIL FERTILITY KEY 

12 - Very low 

5 - Low 

Page 19 of 58 

NATURAL SOIL FERTILITY DESCRIPTION 

Soil fertility can be greatly altered by land management especially through the application of manures, lime and mineral fertilisers. 

What is shown in this map, however, is the likely natural fertility of each soil type. Soils that are very acid have low numbers of 

soil-living organisms and support heathland and acid woodland habitats. These are shown as of very low natural fertility. Soils 

identified as of low natural fertility are usually acid in reaction and are associated with a wide range of habitat types. The moderate 

class contains neutral to slightly acid soils, again with a wide range of potential habitats. Soil of high natural fertility are both 

naturally productive and able to support the base-rich pastures and woodlands that are now rarely encountered. Lime-rich soils 

contain chalk and limestone in excess, and are associated with downland, herb-rich pastures and chalk and limestone woodlands.


1m. SIMPLE TOPSOIL TEXTURE 

SIMPLE TOPSOIL TEXTURE KEY 

1 - Clayey 

2 - Loamy 

3 - Peaty 

4 - Sandy 

Page 20 of 58 

SIMPLE TOPSOIL TEXTURE DESCRIPTION 

Soil texture is a term used in soil science to describe the physical composition of the soil in terms of the size of mineral particles in the 

soil. Specifically, we are concerned with the relative proportions of sand, silt and clay. Soil texture can vary between each soil layer 

or horizon as one moves down the profile. This map indicates the soil texture group of the upper 30 cm of the soil. ‘Light’ soils have 

more sand grains and are described as sandy, while ‘heavy’ soils have few sand grains but a lot of extremely small particles and are 

described as clayey. Loamy soils have a mix of sand, silt and clay-sized particles and are intermediate in character. Soils with a 

surface layer that is dominantly organic are described as Peaty. A good understanding of soil texture can enable better land 

management.


1n. TYPICAL HABITATS 

TYPICAL HABITATS KEY 

17 - Seasonally wet pastures and woodlands 

Page 21 of 58 

18 - Steep acid upland pastures dry heath and moor; bracken gorse and oak woodlands 

6 - Grass moor and heather moor with flush and bog communities in wetter parts 

7 - Grass moor and some heather with flush and bog communities in wetter parts 

TYPICAL HABITATS DESCRIPTION 

There is a close relationship between vegetation and the underlying soil. Information about the types of broad habitat associated 

with each soil type is provided in this map. Soil fertility, pH, drainage and texture are important factors in determining the types of 

habitats which can be established. Elevation above sea level and sometimes even the aspect - the orientation of a hillslope - can 

affect the species present. This map does not take into account the recent land management or any urban development, but 

provides the likely natural habitats assuming good management has been carried out.


2. SOIL ASSOCIATION DESCRIPTIONS 

The following pages describe the following soil map units, (soil associations), in more detail. 

MANOD 611c 


Page 22 of 58 

HAFREN 654a 






The soil associations are described in terms of their texture and drainage properties and potential risks may be identified. The 

distribution of the soils across England and Wales are provided. Further to this, properties of each association’s component soil series 

are described in relation to each other. Lastly, schematic diagrams of each component series are provided for greater understanding 

and in-field verification purposes.


MANOD (611c) 



Well drained fine loamy or fine silty soils over rock. Shallow soils in places. 

Bare rock locally. Steep slopes common. 

The major landuse on this association is defined as stock rearing and 

woodland in uplands; some dairying and cereals in devon and cornwall with 

woodland on slopes. 


The MANOD association covers 5372km² of England and Wales which 






MANOD association are outlined in Table 1 below. In some cases other 




in Table 1. 




Page 23 of 58 










MANOD (611c) 


d. MANOD Component Series Profiles 

Page 24 of 58


MANOD (611c) 


Page 25 of 58 

















profiles. 











MANOD (611c) 







MANOD (611c) 



























Page 27 of 58 




MANOD (611c) 



Page 28 of 58 



to 1 m depth. 



1500kPa. 







MANOD (611c) 





120cm depth. 






70cm depth. 

Page 29 of 58 






Loamy permeable upland soils over rock with a wet peaty surface horizon 

and bleached subsurface horizon, often with thin ironpan. Some peat on 

higher ground. Rock and scree locally. 

The major landuse on this association is defined as moorland and grassland 

habitats, of moderate grazing value; recreation; coniferous woodland; stock 

rearing and dairying on improved ground. 


The HAFREN association covers 1530km² of England and Wales which 






HAFREN association are outlined in Table 2 below. In some cases other 




in Table 2. 




Page 30 of 58 

HAFREN (654a) 


ironpan. 










Page 31 of 58 

HAFREN (654a) 


ironpan. 

d. HAFREN Component Series Profiles


HAFREN (654a) 

Page 32 of 58 


ironpan. 

















profiles. 











Page 33 of 58 

HAFREN (654a) 


ironpan. 






Page 34 of 58 

HAFREN (654a) 


ironpan. 





























Page 35 of 58 

HAFREN (654a) 


ironpan. 




to 1 m depth. 



1500kPa. 







Page 36 of 58 

HAFREN (654a) 


ironpan. 




120cm depth. 






70cm depth. 






Slowly permeable seasonally waterlogged fine loamy and fine silty soils, 

some with wet peaty surface horizons. 

The major landuse on this association is defined as stock rearing on 

permanent grassland and wet moorland of moderate and good grazing value. 


The BRICKFIELD 1 association covers 458km² of England and Wales which 






BRICKFIELD 1 association are outlined in Table 3 below. In some cases 




in Table 3. 




Page 37 of 58 













d. BRICKFIELD 1 Component Series Profiles 

Page 38 of 58 


Slowly permeable seasonally waterlogged fine loamy and fine silty soils, some with wet peaty surface horizons.



Page 39 of 58 



















profiles. 


































Page 41 of 58 














Page 42 of 58 





to 1 m depth. 



1500kPa. 










120cm depth. 

Page 43 of 58 








70cm depth. 








Slowly permeable seasonally waterlogged loamy upland soils with a peaty 

surface horizon. Some very acid peat soils. 

The major landuse on this association is defined as stock rearing on wet 

moorland of moderate grazing value and some permanent grassland; 

coniferous woodland; recreation. 


The WILCOCKS 2 association covers 667km² of England and Wales which 






WILCOCKS 2 association are outlined in Table 4 below. In some cases 




in Table 4. 




Page 44 of 58 













d. WILCOCKS 2 Component Series Profiles 

Page 45 of 58




Page 46 of 58 


















profiles. 













































Page 48 of 58 







Page 49 of 58 



to 1 m depth. 



1500kPa. 












120cm depth. 






70cm depth. 

Page 50 of 58 





3. TOPSOIL ELEMENT BACKGROUND LEVELS 

TOPSOIL ELEMENT BACKGROUND LEVELS KEY 

- NSI sample points 

- Report area 

- 15 km radius - local area 

- 50 km radius - regional area 

TOPSOIL ELEMENT BACKGROUND LEVELS DESCRIPTION 

Page 51 of 58 

The National Soil Inventory (NSI) covers England and Wales on a 5 km grid and provides detailed information for each intersect of the 

grid. Collectively NSI data are statistically representative of England and Wales soils. The original sampling was undertaken around 

1980 and there were partial resamplings in the mid-1990s. The most up-to-date data is presented here. 

Analysis of the NSI samples provides detailed measurements of over 20 elements from the soils, in addition to pH. This data is 

summarised over three areas to provide you with an understanding of how your site, and your data for it, sits within the local, regional 

and national context. 

Where available, the soil element levels are compared with the Soil Guideline Values and where a soil sample we have analysed has 

been found in excess of the SGV guidelines for "residential with plant uptake" land, this is displayed in red in the tables which follow. 

SGV levels are provided for the following elements: lead, selenium, nickel, mercury, chromium, cadmium and arsenic. 

In the following pages, a number of analyses of the topsoil are provided. The majority of analyses have been performed on the full 

compliment of sample points, however, in some areas, for some elements, only a few samples were analysed as part of subsequent 

programmes. In order to present the full suite of possible datasets, and accurately convey the validity of the data, the number of actual 

measured samples is stated for each analysis. Care should be taken where the number of samples is disproportionately low.


3a. Analyses Within a 15 km Radius (27 Sample Points) 

Page 52 of 58 


pH (PH) 27 5.0 3.6 6.3 0.8 

Carbon (CARBON) 27 12.7 2.6 54.5 15.3 



Barium (BA_ACID) 27 158.5 23.0 441.0 101.5 




Cobalt (CO_ACID) 27 10.0 0.4 31.9 6.9 



Copper (CU_ACID) 27 15.9 4.3 30.9 5.7 



Iron (FE_ACID) 27 32,572.9 2,862.0 56,320.0 15,448.3 



Potassium (Extractable) (K_NITRATE) 27 95.3 38.0 215.0 36.2 



Manganese (MN_ACID) 27 709.0 21.0 1,903.0 561.0 

Manganese (Extractable) (MN_EDTA) 27 74.0 3.0 338.0 66.8 


Sodium (NA_ACID) 27 321.8 97.0 799.0 160.7 

Nickel (NI_ACID) 27 21.5 1.3 60.0 14.2 


Phosphorus (P_ACID) 27 1,037.3 507.0 1,685.0 334.1 


Lead (PB_ACID) 27 69.4 26.0 143.0 33.0 

Lead (Extractable) (PB_EDTA) 27 17.5 6.3 36.4 8.7 




Zinc (ZN_ACID) 27 78.0 23.0 153.0 36.9 




3b. Analyses Within a 50 km Radius (252 Sample Points) 

Page 53 of 58 


pH (PH) 247 5.1 3.3 7.6 0.9 

Carbon (CARBON) 251 11.6 1.0 57.4 13.9 



Barium (BA_ACID) 250 168.3 11.0 1,488.0 139.2 




Cobalt (CO_ACID) 250 11.8 0.4 321.8 23.3 



Copper (CU_ACID) 250 18.9 1.3 96.3 10.6 



Iron (FE_ACID) 250 29,616.7 2,862.0 83,515.0 15,643.3 



Potassium (Extractable) (K_NITRATE) 246 130.0 25.0 1,450.0 116.8 



Manganese (MN_ACID) 250 1,117.2 16.0 35,738.0 2,684.2 

Manganese (Extractable) (MN_EDTA) 250 129.3 1.0 2,347.0 200.9 


Sodium (NA_ACID) 250 410.6 69.0 2,209.0 339.2 

Nickel (NI_ACID) 250 19.9 1.3 71.7 13.5 


Phosphorus (P_ACID) 250 934.1 87.0 2,541.0 394.2 


Lead (PB_ACID) 250 110.0 24.0 2,388.0 228.4 

Lead (Extractable) (PB_EDTA) 250 38.9 3.6 1,322.9 116.3 




Zinc (ZN_ACID) 250 97.3 12.0 2,125.0 147.3 




3c. National Analyses (5686 Sample Points) 

Page 54 of 58 


pH (PH) 5,630 6.0 3.1 9.2 1.3 

Carbon (CARBON) 5,672 6.1 0.1 61.5 8.9 

Aluminium (AL_ACID) 5,677 26,775.3 491.0 79,355.0 12,772.2 

Arsenic (AS_ACID) 2,729 4.6 0.0 110.0 5.7 

Barium (BA_ACID) 5,677 150.0 7.0 3,840.0 159.5 

Calcium (CA_ACID) 5,677 13,768.7 0.0 339,630.0 37,785.0 

Cadmium (CD_ACID) 5,677 0.7 0.0 40.9 1.0 

Cadmium (Extractable) (CD_EDTA) 5,655 0.5 0.0 85.0 3.0 

Cobalt (CO_ACID) 5,677 10.6 0.0 567.0 13.7 

Cobalt (Extractable) (CO_EDTA) 5,655 1.1 0.0 26.5 1.2 

Chromium (CR_ACID) 5,677 38.9 0.0 2,339.8 43.7 

Copper (CU_ACID) 5,677 22.6 0.0 1,507.7 36.8 

Copper (Extractable) (CU_EDTA) 5,655 6.4 0.3 431.4 11.1 

Flouride (F_ACID) 3,320 58.5 0.0 6,307.9 186.2 

Iron (FE_ACID) 5,677 28,147.8 395.0 264,405.0 16,510.5 

Mercury (HG_ACID) 2,159 0.1 0.0 2.4 0.2 

Potassium (K_ACID) 5,677 4,727.7 60.0 23,905.0 2,700.2 

Potassium (Extractable) (K_NITRATE) 5,609 182.0 6.0 2,776.0 151.6 

Magnesium (MG_ACID) 5,677 3,648.1 0.0 62,690.0 3,284.1 

Magnesium (Extractable) (MG_NITRATE) 5,609 146.0 1.0 1,601.0 147.5 

Manganese (MN_ACID) 5,677 777.0 3.0 42,603.0 1,068.8 

Manganese (Extractable) (MN_EDTA) 5,654 159.4 0.0 3,108.0 188.6 

Molybdenum (MO_ACID) 4,417 0.9 0.0 56.3 2.0 

Sodium (NA_ACID) 5,677 323.3 17.0 25,152.0 572.3 

Nickel (NI_ACID) 5,677 25.4 0.0 1,350.2 29.2 

Nickel (Extractable) (NI_EDTA) 5,655 1.6 0.1 73.2 2.0 

Phosphorus (P_ACID) 5,677 792.1 41.0 6,273.0 433.9 

Phosphorus (Extractable) (P_OLSEN) 5,604 27.4 0.0 534.0 25.5 

Lead (PB_ACID) 5,677 73.3 0.0 17,365.0 280.6 

Lead (Extractable) (PB_EDTA) 5,655 27.8 1.2 6,056.5 119.7 

Selenium (SE_ACID) 2,729 0.6 0.0 22.8 0.8 

Strontium (SR_ACID) 5,677 42.3 0.0 1,445.0 67.8 

Vanadium (V_ACID) 4,428 41.0 0.0 854.4 33.9 

Zinc (ZN_ACID) 5,677 90.2 0.0 3,648.0 104.4 

Zinc (Extractable) (ZN_EDTA) 5,655 9.6 0.5 712.0 24.6 



SOIL GUIDELINE VALUES (SGV) 

Page 55 of 58 

Defra and the Environment Agency have produced soil guideline values (SGVs) as an aid to preliminary assessment of potential 

risk to human health from land that may be contaminated. SGVs represent ‘intervention values’, which, if exceeded, act as 

indicators of potential unacceptable risk to humans, so that more detailed risk assessment is needed. 

The SGVs were derived using the Contaminated Land Exposure Assessment (CLEA) model for four land uses: 

1. residential (with plant uptake / vegetable growing) 

2. residential (without vegetable growing) 

3. allotments 

4. commercial / industrial 

SGVs are only designed to indicate whether further site-specific investigation is needed. Where a soil guideline value is exceeded, 

it does not mean that there is necessarily a chronic or acute risk to human health. 

The values presented in this report represent those from a number of sample points ( given in the "Samples" column in each 

table) providing local, regional and national background levels. Figures which appear in red indicate that a bulked sample from 

20m surrounding a sample point, has at a past date, exceeded the SGV for the ‘residential with plant uptake’ land use. 

It is always advisable to perform site specific investigations. 

More details on all the SGVs can be found on the Environment Agency Website. 

All units are mg/kg which is equivalent to parts per million (ppm) 

SUBSTANCE 

LEAD 

SELENIUM 

NICKEL 

MERCURY 

CHROMIUM 




ARSENIC 

RESIDENTIAL WITH 

PLANT UPTAKE 

450 

35 

50 

8 

130 

1 

2 

8 

20 

RESIDENTIAL WITHOUT 

PLANT UPTAKE 

450 

260 

75 

15 

200 

30 

30 

30 

20 

ALLOTMENTS 

450 

35 

50 

8 

130 

1 

2 

8 

20 

COMMERCIAL / 

INDUSTRIAL 

750 

8000 

5000 

480 

5000 

1400 

1400 

1400 

500


ANALYSES DEFINITIONS 

PH (pH) 

pH of soil measure after shaking 10ml of soil for 15 minutes with 25ml of water 

Page 56 of 58 

CARBON (Carbon) 

Organic Carbon (% by wt) measured either by loss-on-ignition for soils estimated to contain more than about 20% organic carbon or by dichromate 

digestion. 

AL_ACID (Aluminium) 

Total Aluminium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

AS_ACID (Arsenic) 

Total Arsenic concentration (mg/kg) determined by Hydride Atomic Absorption Spectrometry (AAS), extracted into hydrochloric acid after digestion with 


BA_ACID (Barium) 

Total Barium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CA_ACID (Calcium) 

Total Calcium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CD_ACID (Cadmium) 

Total Cadmium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CD_EDTA (Cadmium Extractable) 

Extractable Cadmium concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 


CO_ACID (Cobalt) 

Total Cobalt concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CO_EDTA (Cobalt Extractable) 

Extractable Cobalt concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 


CR_ACID (Chromium) 

Total Chromium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CU_ACID (Copper) 

Total Copper concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

CU_EDTA (Copper Extractable) 

Extractable Copper concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 


F_ACID (Flouride) 

Flouride extracted with 1mol / l sulphuric acid and determined by Ion Selective Electrode (ISE) 

FE_ACID (Iron) 

Total Iron concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

HG_ACID (Mercury) 

Total Mercury concentration (mg/kg) determined by Hydride Atomic Absorption Spectrometry (AAS), digested in a nitric/sulphuric acid mixture 

K_ACID (Potassium) 

Total Potassium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

K_NITRATE (Potassium Extractable) 

Extractable Potassium concentration (mg/l) determined by shaking 10ml of air dry soil with 50ml of 1.0M ammonium nitrate for 30mins, filtering and then 

measuring the concentration by flame photometry


ANALYSES DEFINITIONS continued 

Page 57 of 58 

MG_ACID (Magnesium) 

Total Magnesium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

MG_NITRATE (Magnesium Extractable) 

Extractable Magnesium concentration (mg/l) determined by shaking 10ml of air dry soil with 50ml of 1.0M ammonium nitrate for 30mins, filtering and then 

measuring the concentration by flame photometry 

MN_ACID (Manganese) 

Total Manganese concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

MN_EDTA (Manganese Extractable) 

Extractable Manganese concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml 


MO_ACID (Molybdenum) 

Total Molybdenum concentration (mg/kg) determined by Atomic Adsorption Spectrometyr (AAS) in an aqua regia digest 

MO_EDTA (Molybdenum Extractable) 

Extractable Molybdenum concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml 


NA_ACID (Sodium) 

Total Sodium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

NI_ACID (Nickel) 

Total Nickel concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

NI_EDTA (Nickel Extractable) 

Extractable Nickel concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 


P_ACID (Phosphorus) 

Total Phosphorus concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

P_OLSON (Phosphorous Extractable) 

Extractable Phosphorus concentration (mg/l) determined by shaking 5ml of air dry soil with 100ml of 0.5M sodium bicarbonate for 30mins at 20 deg.C, 

filtering and then measuring the absorbance at 880 nm colorimetrically with acid ammonium molybdate solution 

PB_ACID (Lead) 

Total Lead concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

PB_EDTA (Lead Extractable) 

Extractable Lead concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 


SE_ACID (Selenium) 

Total Selenium concentration (mg/kg) determined by Hydride Atomic Absorption Spectrometry (AAS), extracted into hydrochloric acid after digestion with 


SR_ACID (Strontium) 

Total Strontium concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

V_ACID (Vanadium) 

Total Vanadium concentration (mg/kg) determined by Atomic Adsorption Spectrometyr (AAS) in an aqua regia digest 

ZN_ACID (Zinc) 

Total Zinc concentration (mg/kg) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) in an aqua regia digest 

ZN_EDTA (Zinc Extractable) 

Extractable Zinc concentration (mg/l) determined by Inductively Coupled Plasma Emission Spectrometry (ICP) after shaking 10ml of soil with 50ml of 0.05M 

EDTA at pH 7.0 for 1h at 20 deg. C and then filtering


REFERENCES 

Page 58 of 58 

AVERY, B.W. (1973). Soil classification in the Soil Survey of England and Wales. Journal of Soil Science, 24, 324-338. 

AVERY, B.W., (1980). Soil classification for England and Wales. Soil Survey Technical Monograph No.14, Harpenden, UK. 

BOORMAN, D.B, HOLLIS, J.M. and LILLEY, A. (1995). Hydrology of Soil Types: a hydrologically-based classification of the soils of the UK. 

Institute of Hydrology Report No.126, Wallingford, UK. 

CLAYDEN, B and HOLLIS, J.M. (1984). Critieria for Differentiating Soil Series. Soil Survey Technical Monograph No.17, pp159. Harpenden, 

UK. 

HALLETT, S.H., KEAY, C.A., JARVIS, M.G. and JONES, R.J.A. (1994). INSURE: Subsidence risk assessment from soil and climate data. 

Proceedings of the Association for Geographic Information (AGI). National Conference Markets for Geographic Information. Birmingham. 

16.2.1 - 16.2.7. 

HOLLIS, J.M. (1991). Mapping the vulnerability of aquifers and surface waters to pesticide contamination at the national and regional scale. 

In: Pesticides in Soils and Water, BCPC Monograph No.47, 165-174. 

HOLLIS, J.M., KEAY, C.A., HALLETT, S. H., GIBBONS, J.W. and COURT, A.C. (1995). Using CatchIS to assess the risk to water resources 

from diffusely applied pesticides. In: British Crop Protection Council monograph No. 62: Pesticide movement to water, 345-350 

JARVIS, M.G and HEDGES, M.R. (1994). Use of soil maps to predict the incidence of corrosion and the need for iron mains renewal. Journal 

of the Institution of Water and Environmental Management 8, (1) 68-75. 

PALMER, R.C., HOLMAN, I.P., ROBINS, N.S. and LEWIS, M.A. (1995). Guide to groundwater vulnerability mapping in England and Wales. 

National Rivers Authority R and D Note 578/1/ST. 

To view the glossary visit: www.landis.org.uk/sitereporter/GLOSSARY.pdf 

For a list of further reading visit: www.landis.org.uk/sitereporter/FURTHER_READING.pdf 

For more information visit: www.landis.org.uk/reports 

GIS DATASETS: 

The GIS data used in the creation of this report is available to lease for use in projects. 

To learn more about, or acquire the GIS datasets used in the creation of this report, please contact the National Soil Resources Institute: 

nsridata@cranfield.ac.uk 

+44 (0) 1234 75 2978 


Cranfield University 

Bedfordshire 

MK43 0AL 

United Kingdom 

www.landis.org.uk

Annex F4 

Flood Consequences 

Assessment – Clocaenog 

Wind Farm

WHS Dundee 

Flood Consequences Assessment – Clocaenog 

Wind Farm 

Laurelbank 

2 Dudhope Street 

Dundee 

DD1 1JU 

www.hydrosolutions.co.uk 

November 2009 

Final Report

Flood Consequences Assessment – Clocaenog 

Wind Farm 

For and on behalf of 

Wallingford HydroSolutions Ltd. 

Prepared by: Andrew Black 

Approved by: Andy Young 

Position: Director 

Date: 13 November 2009 

Final Report to ERM 

Copyright © Wallingford HydroSolutions Ltd. 2009 

This report has been prepared by 

Wallingford HydroSolutions with all 

reasonable skill, care and diligence 

within the terms of the Contract 

with the client and taking account of 

the resources allocated to it by 

agreement with the client. 

We disclaim any responsibility to 

the client and others in respect of 

any matters outside the scope of 

the above. This report is 

confidential to the client and we 

accept no responsibility of any 

nature to third parties to whom this 

report, or any part thereof, is made 

known. Any such party relies on the 

report at their own risk.

Executive Summary 

This report presents a Flood Consequences Assessment for the proposed 

development of a wind farm and associated infrastructure at Clocaenog 

Forest, Denbighshire. The proposed areas of hard standing cover a total 

of 10 ha in a distributed site extending to a length of approximately 9 km 

along a forested ridge. The site envelope does not include any properties 

which are at risk of flooding. Given this background, the focus of the 

report is to assess the likely effects of the development on runoff from the 

existing site, and the measures which may be necessary to control any 

excess runoff. 

Hydrological assessments were carried out on two small sub-catchments 

of the Afon Alwen which could potentially be affected by change in runoff 

from the site. Institute of Hydrology Report 124 and the ReFH 

spreadsheet tool were used to assess runoff rates and volumes in order 

that the required volumes of storage could be estimated. 

Required storage capable of holding the additional runoff from the 

development site coupled with climate change in a 100-year design 

scenario was estimated as 679m 3 . This is a very small volume in the 

context of the runoff which would be generated from the natural 

catchments draining the site, and indeed the Flood Estimation Handbook 

considers that the runoff from the catchments would remain essentially 

rural. It is concluded that no storage needs to be provided to attenuate 

an imperceptible increase in flood risk, but that enhancement of riparian 

vegetation and/or creation or restoration of wetlands would provide some 

attenuation benefits in tandem with other gains such as habitat provision 

and sediment trapping. The effects of forest clear felling were reviewed 

through a literature search, and considered as not likely to cause any 

increase in flood response in downstream areas. Nevertheless, the 

recommended riparian enhancements would serve to provide attenuation 

in the event of some localised increases in runoff rates occurring. 

i

Contents 

Executive Summary ................................................................. i 

Contents................................................................................ ii 

List of Figures........................................................................ iii 

List of Tables......................................................................... iii 

1 Introduction ........................................................................ 1 

1.1 Objectives ..................................................................... 1 

1.2 Report Structure............................................................. 3 

1.3 Sources of Information .................................................... 4 

2 Description of the Site........................................................ 5 

2.1 Background Information .................................................. 5 

2.2 Existing Site Description .................................................. 5 

2.3 Proposed Site Development.............................................. 8 

2.4 Catchment Delineation .................................................. 11 

2.5 Site Infiltration Test ...................................................... 14 

3 Review of forest impacts on flood generation....................... 16 

4 Flood Consequences Assessment ....................................... 20 

4.1 Potential Sources of Flooding.......................................... 20 

4.2 Environment Agency Flood Map ...................................... 21 

4.3 Current Flood Risk ........................................................ 22 

5 Surface Water Runoff Assessment...................................... 23 

5.1 Background Information ................................................ 23 

5.2 Summary of Methods .................................................... 24 

5.3 Calculation of Existing Greenfield Runoff Rates.................. 28 

5.4 Assessment of Increase in Runoff following Development ... 29 

5.5 Outline Surface Water Drainage Strategy – Overview......... 31 

5.6 Construction ................................................................ 34 

6 Conclusions .................................................................. 35 

References........................................................................... 37 

ii

List of Figures 

Figure 1 Figure to illustrate distinction between runoff to be stored 

vs runoff allowed to discharge at greenfield rates ........................ 3 

Figure 2 Site photographs ....................................................... 6 

Figure 3 Location of proposed turbines and catchment boundaries 9 

Figure 4 Location of proposed turbines, catchment access tracks 

and enclosing catchment boundaries........................................ 10 

Figure 5 Infiltration test equipment at Hafren soil type site ........ 14 

Figure 6 Extract from Environment Agency flood risk map.......... 21 

List of Tables 

Table 1. Classification of feature types and associated impermeable 

and semi-permeable extents in the proposed development ......... 13 

Table 2. Pre-development catchment characteristics and response 

.......................................................................................... 28 

Table 3 Post-development characteristics and response: 

impermeable areas................................................................ 29 

Table 4 Post-development characteristics and response: semipermeable 

areas ................................................................... 30 

iii

1 Introduction 

1.1 Objectives 

Wallingford Hydrosolutions Ltd has been commissioned by ERM to 

undertake a Flood Consequence Assessment (FCA) to support the 

planning application for the proposed development of a wind farm situated 

at Clocaenog Forest, approximately 13km south of Denbigh, Wales. 

TAN 15 Development and Flood Risk states that “particular flooding 

consequences may not be acceptable for particular types of development.” 

Therefore a flood consequences assessment has to be undertaken at the 

proposal stage. This is to ascertain whether the proposed development 

will increase the risk of flooding. Developments that are designed without 

regard to flood risk may endanger lives, damage property, cause 

disruption to the wider community and damage the environment. CIRIA 

(2004) Funders Report provides the current guidance on development and 

flood risk. This identifies several key aims for a development to ensure 

that it is sustainable in flood risk terms. These aims are as follows: 

1. the development should not be at a significant risk of flooding 

and should not be susceptible to damage due to flooding; 

2. the development should not be exposed to flood risk such that 

the health, safety and welfare of the users of the development, 

or the population elsewhere, are threatened; 

3. normal operation of the development should not be susceptible 

to disruption as a result of flooding; 

4. safe access to and from the development should be possible 

during flood events; 

5. the development should not increase flood risk elsewhere; 

6. the development should not prevent safe maintenance of 

watercourses or maintenance and operation of flood defences; 

7. the development should not be associated with an onerous or 

difficult operation and maintenance regime to manage flood risk. 

The responsibility for any operation and maintenance required 

should be clearly defined; 

1

8. future users of the development should be made aware of any 

flood risk issues relating to the development; 

9. the development design should be such that future users will not 

have difficulty obtaining insurance or mortgage finance, or in 

selling all or part of the development, as a result of flood risk 

issues; 

10.the development should not lead to degradation of the 

environment; and 

11.the development should meet all of the above criteria for its 

entire lifetime, including consideration of the potential effects of 

climate change 1 . 

Some of the criteria listed above apply more to residential or light 

commercial developments rather than to a wind farm situation. Item 

numbers 4 and 9 in particular do not apply in this case. As a development 

for the generation of energy from renewable sources, the proposal 

represents an initiative aimed at addressing the need to tackle climate 

change. In the context of the flood mitigation policy outlined in the Dee 

and Conwy & Clwyd Draft Catchment Flood Management Plans, the 

proposals also offer an opportunity to mitigate against future increases in 

flood risk by providing storage capacities which include an allowance for 

climate change. 

This report evaluates the potential flood risks to the proposed 

development while taking into account the sustainability aims that are set 

out by the guidance. It also outlines the mitigation requirements including 

a conceptual drainage strategy in accordance with SUDS guidance to 

ensure that flood risk to the surrounding area is not increased. 

Dialogue with the Environment Agency identified the following objectives 

which should be met by the plans for the proposed development: 

1 CIRIA (2004) Funders report CP/102 Development and Flood Risk – 

Guidance for the Construction Industry 

2

Runoff rates under 100-year storm to be kept at existing rates and 

should mitigate the runoff-enhancing effects of the wind farm 

development and the effects of climate change. 

Climate change is assumed to amount to a 20% increase in the total 

volume of runoff under the design hydrograph. We illustrate our 

understanding of the requirement by means of Figure 1 below: 

Additional volume 

due to development 

Additional volume 

due to climate 

change 

Greenfield runoff 

volume (100-year 

event) 

Volume to be 

stored/attenuated 

Volume to be able 

to discharge at 

greenfield rates 

Figure 1 Figure to illustrate distinction between runoff to be 

stored vs runoff allowed to discharge at greenfield rates 

As will be discussed, the construction of the wind farm will also include 

significant clear felling of the current coniferous plantations on the 

development site. In addition to meeting the Environment Agency’s 

requirements above, the FCA also considers both the short term and long 

term potential impacts of clear felling on catchment flood response. 

1.2 Report Structure 

This Flood Consequences Assessment has the following report structure: 

• Section 2 focuses on the development site and its present features 

together with the description of the proposed wind farm 

development. 

3

• Section 3 presents a review of the effects of forestry and forest 

clearance on downstream flood risk. 

• Section 4 is the Flood Risk Assessment. This looks at the current 

flood risk from all potential sources as well as any information on 

historic flooding. 

• Section 5 constructs a sustainable drainage strategy appropriate to 

the results of Section 4 and which the proposed development must 

put in place to prevent an adverse impact on the local surface water 

runoff regime. 

• Section 6 presents a summary and set of conclusions. 

1.3 Sources of Information 

The study makes use of the following source information: 

• Nextmap 50m resolution elevation data 

• TAN15: Development and Flood Risk 

• Denbighshire SFCA 

• Conwy and Clwyd and River Dee draft CFMPs 

• National Soil Resources Institute Soils Site Report 

• Detailed plans of the proposed wind farm 

• FEH CD-ROM and other FEH products 

4

2 Description of the Site 

2.1 Background Information 

The area of land covered by hard standing areas for the proposed 

development is approximately 10ha and will include 32 wind turbines and 

associated infrastructure. The site area is currently used for coniferous 

forestry, some of which it is proposed will be clear felled. 

A site visit was carried out on the 22-23 July 2009 to visually inspect the 

surface water features, to obtain an understanding of the topography, 

soils and geology of the site and to view any present water drainage 

pathways. An infiltration test was also carried out at this time to 

independently validate soil infiltration behaviour provided in a soils report. 

2.2 Existing Site Description 

The site extends along a ridge of approximately 10 km in length to the 

east of Llyn Brenig Reservoir. The ridge reaches elevations of 500 m OD 

and is almost entirely covered in a Forestry Commission plantation. There 

is a mixed geology on the site consisting of slates, shales and grits, giving 

rise to ground slopes of 5-10%, and partly overlain by glacial tills. 

Figure 2 provides photographs illustrating characteristics of the proposed 

development site. 

5

Channel draining SW from Clocaenog 

Forest near Tal y Cefn Isaf 

Forest drainage ditch near Ty-nant 

in south of Clocaenog Forest 

Figure 2 Site photographs 

6 

Forest drainage ditch near Ty-nant 

in south of Clocaenog Forest 

Clearing within forest area – 

naturally wet ground presenting 

opportunities for future enhanced 

wetland storage of water

Steep channel with forest debris 

close to southern margin of forest 

near Cefn Rofft 

Clywedog Reservoir, maintained as 

a fishing lake 

Figure 2 continued Site photographs 

7 

Steep side-slopes and dense 

bracken adjacent to tributary of 

Afon Clywedog 

Gentle relief and clear felled area 

above Clywedog Reseroir 

A mix of soil types is found on the site, characterised as follows, with no 

one type predominating:

Manod: Well drained fine loamy or fine silty soils over rock. 

Hafren: Loamy permeable upland soils over rock with a wet peaty surface 

horizon and bleached subsurface horizon, often with thin ironpan. 

Brickfield 1: Slowly permeable seasonally waterlogged fine loamy and 

fine silty soils, some with wet peaty surface horizons. 

Wilcocks 2: Slowly permeable seasonally waterlogged loamy upland soils 

with a peaty surface horizon. 

The mix of types found gives rise to an expectation that some natural 

flashiness will occur in heavy rainfall events, and indeed will be 

accelerated by the gradients, particularly to the south of the site where 

these are steepest. 

2.3 Proposed Site Development 

The proposed wind farm extends to approximately 10 hectares of 

impermeable and semi-permeable surfaces and compromises: 

• 32 wind turbines 

• Access tracks 

• Contractors compound 

• Switching room 

• Crane pads 

• Permanent meteorological mast 

As well as the necessary construction work, a programme of forest clear felling will 

also be required as part of the development. Figure 3 and Figure 4 show the 

proposed turbine locations and site layout in the context of seven natural catchment 

areas which drain the site in its totality. 

8

Figure 3 Location of proposed turbines and catchment boundaries 

9

Figure 4 Location of proposed turbines, catchment access tracks 

and enclosing catchment boundaries 

10

2.4 Catchment Delineation 

An assessment of the areas draining from each impermeable or semi- 

permeable area to watercourses surrounding the site was derived by 

overlaying the site boundary and extent of impermeable areas provided 

from detailed plans of the proposed development onto the catchment 

boundaries derived for each water course. Impermeable surfaces were 

considered to encompass: 

• Turbine foundations 

• Substation and compounds 

Semi-permeable surfaces were considered to encompass: 

• Access tracks 

• Crane hardstanding areas 

• Construction compound 

• Switch room building 

• Anemometer foundation 

• Cable runs 

In Section 5 below, we outline drainage proposals for the site and the 

means by which SUDS may be implemented. Meantime, the assumptions 

associated with the lists above are as follows: 

Impermeable surfaces 

Turbine foundations are associated with a 100% runoff factor, i.e. worst 

case scenario given that these are formed of solid concrete (although 

some modest storage will be present in the soil overlay above them and 

indeed some local infiltration measures may be installed immediately 

downslope). SUDS will be implemented around the switch room buildings 

but, nevertheless, since the building roof and walls themselves will be 

impermeable and despite SUDS to diffuse the runoff from these surfaces, 

the same 100% runoff is assumed. 

11

Semi-permeable surfaces 

For the access tracks, crane hardstanding areas, construction compound 

and anemometer foundation, all of these surfaces are formed of 

unconsolidated aggregate which provides some storage capacity itself, 

allows some infiltration, and will be drained by SUDS solutions. We 

therefore assume that rainfall falling on these features will be able to 

infiltrate locally (note that the largest areas are as tracks which are by 

their nature distributed features) and will contribute to site runoff at the 

greenfield rates. 

Table 1 shows the extent of proposed hard standing areas which would 

drain into the north-west and south-east catchments. 

12

Outfall grid 

reference 

Total 

catchment 

area (km 2 ) 

Impermeable 

surfaces 

Turbine 

foundations 

(m 2 ) 

Substation 

and 

compounds 

(m 2 ) 

Total 

impermeable 

area (m 2 ) 

Total 

impermeable 

area (%) 

Semipermeable 

surfaces 

Widening of 

existing 

access tracks 

(m 2 ) 

New spur 

roads (m 2 ) 

New tracks 

(m 2 ) 

Civils site 

compounds 

(m 2 ) 

Crane 

hardstanding 

areas (m 2 ) 

Total semipermeable 

area (m 2 ) 

Total semipermeable 

area (%) 

Afon Afon Afon Afon Afon 

Afon Afon Alwen Alwen Alwen Alwen Alwen 

Clywedog Clwyd 1 2 3 4 5 

SJ SJ SH SH SH SJ SJ 

058579 039509 985560 988519 989518 005489 011488 

28.57 9.79 1.52 5.53 2.91 3.88 2.03 

3780 360 180 0 720 540 180 

8125 8125 0 0 0 0 0 

11905 8485 180 0 720 540 180 

0.04 0.09 0.01 0.00 0.02 0.01 0.01 

21888 2956 9 744 6491 1823 1800 

7833 609 0 0 1660.08 1192 0 

1189 2618 0 0 0 1925 0 

2500 2500 0 2500 0 0 0 

18480 1760 880 0 3520 2640 880 

51891 10443 889 3244 11671 7580 2680 

0.18 0.11 0.06 0.06 0.40 0.20 0.13 

Total 

impermeable 

+ semipermeable 

area (%) 

0.22 0.19 0.07 0.06 0.43 0.21 0.14 

Table 1. Classification of feature types and associated impermeable and 

semi-permeable extents in the proposed development 

13

2.5 Site Infiltration Test 

Two infiltration tests were undertaken as part of the site visit, in order to 

gain independent evidence of the rate of infiltration. The tests were 

conducted following United Nations FAO guidelines, which involve forcing 

two concentric cylinders into the soil surface, filling both with water, then 

monitoring and maintaining levels until evidence of a steady rate of 

infiltration is obtained. Figure 5 illustrates a test under way. 

Figure 5 Infiltration test equipment at Hafren soil type site 

14

Tests were attempted at two sites with contrasting infiltration 

characteristics: 

• Hafren soil type – test grid ref SJ 01466 54664 – corresponding to 

HOST Class 15 “permanently wet, peaty topped upland soils over 

relatively free draining permeable rocks”. The test result was 60 

mm/hour, which was a relatively high value and is compatible with 

the soil description. 

• Wilcocks 2 soil type – test grid ref SJ 00290 57470 – corresponding 

to HOST Class 26 “permanently wet, peaty topped upland soils over 

slowly permeable substrates with negligible storage capacity”. This 

soil would be expected to have a lower infiltration rate than the 

Hafren soil. The area selected for testing was extensively covered 

by plantation forestry and clear-felled areas. The test 

demonstrated very high rates of infiltration, sufficiently high that it 

was impossible to supply water quickly enough to establish a steady 

rate of infiltration (through the application of >100mm of water 

depth). This was thought to be at least partly a result of the 

density of tree roots in the soil, providing enhanced infiltration 

capacity, though it is likely to have also reflected an inability to fully 

drive the cylinders into the soil, again due to root effects. While 

perhaps not reflecting conditions in the lower levels of the soil, the 

result was a surprise given the soil description, and provides an 

unverified suggestion that the current land use may have increased 

the water-holding capacity of the soil (which would accord with 

some published results – see Section 3 below). 

15

3 Review of forest impacts on flood generation 

As stated, significant forest clearance will be needed on the site as part of 

the development of the proposed wind farm. A review of the effects of 

forest felling on surface runoff and catchment flow regimes is therefore 

presented in this section, in order to contribute to a better understanding 

of the possible effects of the proposal on downstream flood risk. 

The short term impacts upon the surface runoff and catchment flow 

regimes are that the felling will have an initial impact upon the catchment 

water balance. Forest canopies intercept incoming rainfall, and 

subsequent evapotranspiration from the canopy partly removes it from 

the catchment, back into the atmosphere. The removal of the canopy will 

hence result in higher rainfall inputs to the system, resulting in higher 

surface runoff and thus a rise in the annual flow. The largest impact will 

occur in the short term before vegetation begins to grow, but will be a 

function of the extent of felling that occurs in a catchment. 

In a catchment with 6.5% proposed felling (as at Afon Clywedog, having 

the highest proportion of proposed felling for any of the catchments 

covered by the Clocaenog proposal), a canopy capacity not exceeding 

3mm of rainfall and a design rainfall of 57mm in a 100-year storm, the 

excepted change in direct precipitation resulting from the felling would be 

in the order of 

3 mm × 0. 

065 

57mm 

= 0.3% (or 0.2mm) across the catchment as a whole. 

The initial impact of the clear felling may also lead to increased flood 

peaks, with the removal of the interception process and while the 

drainage network is still in place, offering a fast-response preferential 

routing through the catchment. This impact will reduce over time as 

vegetation grows increasing interception and the drainage network slowly 

fills in with organic material. This impact could be reduced by drain 

blocking across the site. 

16

The long term impacts on the surface runoff and catchment flow regimes, 

with regards to both low flows and floods, are in fact to return these to a 

condition approaching the natural state (potentially subject to some drain 

blocking) and may hence be considered a hydrological benefit. There is a 

common misunderstanding that plantations reduce flood peaks and hence 

that removal of forest cover will increase flood peaks. Studies during the 

1960s and 1970s almost invariably did show flood peak increases after 

felling. However more recent studies have shown the observed increases 

in flow peaks after felling were due more to the felling operations than to 

the absence of the trees. Severe damage was caused to the ground 

surfaces during felling operations in these earlier studies (heavy 

machinery rutting and compacting the soil) which led to the generation of 

surface runoff and preferential routing through the catchment. This 

highlights the importance of achieving minimum soil disturbance during 

felling operations. These early studies also generally only examined small 

events, whereas recent studies have shown the impact on large events 

was much smaller. 

Soil water storage capacity is an additional factor. Drainage ditches will 

tend to lower water tables, leading to increases in the volume of water 

which can initially be stored after rainfall occurs, thereby attenuating flood 

response (Newson, 2009). Root systems may also increase the storage 

capacity of a soil (Ward & Robinson, 2000). 

Improvements in felling operation practices (as outlined particularly in the 

Forests and Water Guidelines: Forestry Commission, 2003) have led to 

great reductions in the adverse downstream impacts of felling operations 

on water and sediment. A range of catchments of a variety of sizes were 

studied draining the large Hafren Forest during felling over a 20 year 

period. These found a significant increase in baseflows but did not detect 

a change in peak flows (Robinson and Dupeyrat, 2005). Many other 

recent studies (eg Breschta et al. 2000, McDonnell, 1999 and Wright et al. 

1990) have also found little or no impact on peak flows following felling. 

17

Scientific evidence does support a link between deforestation and 

flooding, but only at a local scale and for small events. In small 

catchments, after forest clearance, peak discharge and stormflow volume 

may increase due to the effect of increase in soil wetness. The 

hydrological response of small catchments to rainfall depends on the 

hydraulic conductivity, rainfall intensity and duration, soil water storage 

capacity and slope morphology. Experimental attempts to find a link 

between forests and larger scale, or severe flooding, have failed to yield 

such links (Kaimowitz, 2004). 

In conclusion, felling using current guidelines should have a relatively 

limited impact on flood risk downstream. This is confirmed by the Conwy 

and Clwyd draft CFMP, which states that “upland forestry is unlikely to 

affect downstream flood risk”. The Denbighshire County Council Strategic 

Flood Consequence Assessment takes a similar line: “Even potentially 

large scale schemes such as the possible deforestation of some of the 

upper Clwyd catchment for development of a wind farm is unlikely to have 

much impact on runoff and flooding at key receptors downstream. Land 

management and flood generation has been the subject of R&D project 

FD2114 under the Defra/Agency R&D Programme (Defra/EA, 2004). The 

Phase 1 report from this project concluded that: ‘(the effects of land 

management practice at a broad scale) on runoff generation have not 

been clearly established although significant local changes at the field 

scale have been found. The difficulty in obtaining consistent evidence of 

the effects of land use change on downstream flood response at 

catchment and major sub-catchment scales suggests that, at this level, 

any effect is probably relatively moderate’”. 

Sediment mobilisation may cause flooding problems at a local or larger 

scale. Control of sediment generation and mobilisation is discussed within 

the Hydrology section of the Environmental Statement supporting the 

planning application. 

18

4 Flood Consequences Assessment 

4.1 Potential Sources of Flooding 

CFMP Policy guidance states that when carrying out an FCA the following 

flooding mechanisms should be considered: 

• Fluvial flooding 

• Tidal flooding 

• Flooding from rising/high groundwater 

• Surface water 

• Flooding from artificial drainage systems 

• Flooding due to infrastructure failure 

Each of these is considered in the following sub-sections. There is no 

evidence of any flooding problems on the site, and accordingly no Level 2 

FCA is considered to be necessary. 

Fluvial Flood Risk 

The site is located at high altitude, with the only connection between the 

development and watercourses being at small culvert crossings. All 

turbines are planned for sites above the level at which flooding would 

occur. Risks relating to culvert crossings will be managed by using the 

appropriate guidance for design and installation, in consultation with the 

Environment Agency. 

Tidal Flood Risk 

The site is over 300m above sea level at its lowest point, so this risk does 

not apply. 

Ground Water 

The site is over 300m above sea level at its lowest point, so this risk does 

not apply. 

Surface Water 

The moderate permeability of some of the soils on the site gives rise to 

the possibility of surface runoff in the event of extreme rainfall and/or 

saturated antecedent conditions. Drainage will be provided to make 

appropriate provision for this eventuality. 

20

Flooding from Artificial Drainage Systems 

The site is not threatened by flooding from any artificial drainage systems. 

Turbine locations will be sufficiently above flood levels of road/track 

drainage, and any new crossings of minor watercourses will follow best 

practice as per Environment Agency requirements. 

Flooding due to infrastructure failure 

No infrastructure is being proposed as part of the development which 

would lead to the risk of flooding if a failure occurred. 

4.2 Environment Agency Flood Map 

The Agency’s flood map (Figure 6) shows a number of areas of fluvial 

flood risk downstream of the development site in various directions, 

emphasising the importance of ensuring that site runoff rates do not 

exceed greenfield levels. 

In the south-west of the development site, there is one area of fluvial 

flood risk. This lies in Afon Alwen catchment No. 2 which contains no 

turbines and a short length of track. The map gives no indication of flood 

risk to the development. 

Figure 6 Extract from Environment Agency flood risk map 

21

4.3 Current Flood Risk 

In summary, the proposed development site is not considered to be at any significant 

risk of flooding as the annual probability of any flooding affecting the development 

itself is less than 1 in 1000 years (

5 Surface Water Runoff Assessment 

5.1 Background Information 

Table 1 shows details of seven catchments draining from the site. These 

are the smallest enclosing catchments to capture all the runoff from the 

site, but are themselves never less than 99.58% unaffected (in area 

terms) by the areas of hardstanding, foundations and buildings. In these 

circumstances, analyses of the hydrology of the whole catchments will be 

affected only marginally by the proposed developments. 

Assessments of the impact of development on flood risk will all take a 

similar form. Accordingly, analyses are presented for two typical 

catchments (with 4 and 3 proposed turbines respectively) for Afon Alwen 

catchment No.s 3 and 4 (see Table 1) with a view to achieving a high- 

level understanding of the size of hydrological impact to be expected and 

the types of mitigation to be warranted. 

Analyses are presented in the following sub-sections for the Afon Alwen 

catchment No.s 3 and 4 with catchment areas of 2.91 and 3.88 km 2 and 

total (impermeable + semi-permeable) areas of 0.43 and 0.21% of 

catchment areas respectively. Of the seven catchments, these two have 

the second and third largest numbers of proposed turbines. It should be 

noted that the Flood Estimation Handbook specifies that a catchment with 

an URBEXT catchment descriptor value of less than 2.5% of the 

contributing area would have a flood regime that is indistinguishable from 

the rural flood regime. URBEXT comprises a combination of urban and 

suburban extents. Using standard rules of thumb for the fraction of urban 

areas covered by impermeable surfaces (0.3) and the relationship 

between URBEXT and the Flood Studies URBAN descriptor, the sum of 

impermeable and semi-permeable surfaces within these catchments would 

represent URBEXT values of 1.8% and 1.4%. Thus, even at these small 

scales, the post development flood response is unlikely to be significantly 

different from the rural flood response. 

23

Analyses are not presented for the larger two catchments, with 28.6 and 9.79 

km 2 catchments respectively. These catchments could be subdivided into 

several smaller catchments with developed fractions still less than 1% of total 

catchment area. The scale of these large catchments is at odds with the 

scales at which the effects of development might be most pronounced (say 

2km 2 or less), before they are combined with the runoff response of other 

catchments. 

5.2 Summary of Methods 

The National SUDS Working Group Interim Code of Practice for 

Sustainable Drainage Systems (2004) recommends methods according to 

catchment area. The catchments in question are the areas of proposed 

development found in each of the two catchments described above. The 

guidance recommends that Institute of Hydrology Report 124 be used for 

areas of less than 50 ha, which includes both development areas on this 

site. Since the guidance was published, the ReFH Revitalised Flood 

Hydrograph has been published and has become the most recent guidance 

for design flood estimation. ReFH is gaining a reputation for good 

performance even in small catchments of less than 50ha, and benefits 

from being built on robust physical principles which apportion event 

rainfall into storm flow and base flow components, and having been 

developed and calibrated on a very large data set. The ReFH has the 

added value that it yields a design hydrograph together with the 

generating storm rainfall profile; both key requirements for estimating 

runoff volumes. 

The key priority for this report is to be able to reliably assess greenfield 

runoff rates and then assess the additional runoff which would be 

attributable to the proposed development and climate change which is 

expected to progress through the present century. 

While Report 124 is specifically targeted on small catchments, it suffers a 

number of weaknesses: 

24

• The calibration data are drawn only from sites in and around the 

Thames corridor covered by the Cheynes radar located in the 

Chiltern Hills – runoff response in the north and west of Britain is 

thought to be quite different 

• Its estimation of QBAR is highly sensitive to values of SOIL (subject 

to a power index of 2.17) and may therefore lead to unreliable 

estimates 

• The SOIL index is obtained by reference to a crude assessment of 

Winter Rainfall Acceptance Potential on a 5-class scheme 

Greenfield peak runoff rates were calculated using the small catchment 

statistical method specified within IH Report 124, in conjunction with the 

growth curves factors specified within the NERC Flood Studies 

Supplementary Reports 2 and 14. The objective in estimating a greenfield 

runoff rate is to ascertain a best estimate of local runoff rates in the 

vicinity of the development. Given the distributed nature of the 

development within the sub catchments the sub catchment area was used 

within the assessment with the model output expressed as runoff rates 

per unit area to facilitate scaling to the impermeable development 

extents. As discussed a key catchment descriptor within the method is the 

soil class(es) as characterised by the Winter Rainfall Acceptance Potential 

(WRAP) map (NERC, 1975) and defining the SOIL index. This is an 

extremely coarse map which is mapped at a scale of 1:625,000 and as 

such does not contain sufficient information for determining local soil and 

underlying substrate permeability at small catchment scales. 

The selection of appropriate WRAP soil class values for the catchments 

was informed by the WRAP class descriptions and local soil maps coupled 

within the results of the infiltration tests. For the purposes of defining 

runoff rates for this assessment the soil permeability classes and 

substrate classes within the Hydrology of Soil Types (HOST) classification 

(Boorman et al., 1994) were used to guide soil class selection. The HOST 

classification has replaced the Winter Rainfall Acceptance Potential map in 

all current flood estimation procedures. 

25

WRAP fractional extents of 0.75 WRAP2 and 0.25WRAP4 were used. There 

was a good correspondence between the Report 124 and ReFH estimates 

of Q(n) for all return periods. Based on this outcome the analysis was 

based on the ReFH simulated hydrographs. This choice also benefited 

from significant consultation and discussion with the developers of the 

ReFH methodology at the Centre for Ecology & Hydrology in Wallingford. 

The method is summarised thus: 

1. Assess the impermeable fraction of the catchment. 

This was done using the results presented in Table 1 above. 

2. Obtain design rainfall profile 

The Interim Code of Practice for Sustainable Drainage Systems (National 

SUDS Working Group, 2004, p48) recommends use of a 6 hour storm 

duration. The ReFH Spreadsheet Tool, which post-dates the SUDS 

guidance, was used to generate the ordinates of the storm profile using 

the FEH Depth Duration Frequency rainfall model. For the present study, 

the tool was interpreted as recommending a 0.5-hour time step and, 

because an odd number of multiples of the time step were required, a 6.5 

hour storm duration was specified. 

The profile is generated for winter conditions given the low values of 

URBEXT which applies to the whole of the development area (irrespective 

of whether greenfield or developed situations). 

3. Obtain catchment characteristic data for the smallest available 

enclosing catchment 

This was done using the recently released FEH CD-ROM Version 3, 

providing the most up to date values available, and rescaled for the 

required catchment area. The URBEXT value was set to zero in order to 

perfectly represent greenfield conditions (not dissimilar to existing 

conditions in either catchment given the present lack of development). 

26

4. Obtain peak flow and total hydrograph volume for greenfield 

and developed scenarios 

This was also done using the ReFH Spreadsheet Tool for 1-, 30- and 100- 

year events. Peak flows (in m 3 /s and l/s/ha), and total runoff volume 

were tabulated for the greenfield scenario for each return period. 

Developed scenario runoff volumes were found by assessing the additional 

runoff arising from the impermeable surfaces in each catchment, 

assuming 100% runoff from impermeable surfaces and infiltration from 

semi-permeable surfaces. Runoff volume and peak flow for the 

impermeable surfaces were based on scaling total runoff from those 

surfaces by 120% to allow for the effects of climate change. 

This analysis was repeated for the semi-permeable extents as although it 

might be anticipated that these would generate runoff at the greenfield 

rate, the trackways represent the majority of the semi-permeable extents 

and these will be actively drained to maintain track stability and minimise 

trackway erosion. Thus, the actual runoff, although treated locally through 

drains discharging to the catchment surface, will be more akin to 

permeable (greenfield rate) runoff. 

5. Assess change in peak flow and runoff volumes between rural 

and developed situations. 

The mitigation to be required was obtained using the results from the 

preceding step. 

27

5.3 Calculation of Existing Greenfield Runoff Rates 

Application of the method with the catchment descriptors shown produced 

model outputs as per Table 2. 

Afon Alwen No. 3 Afon Alwen No. 4 

Storm duration used (hr) 6.25 6.25 

Time step used (hr) 0.25 0.25 

Assumed urban fraction 0.000 0.000 

Catchment area (ha) 291 388 

Tp (hr) 1.27 1.49 

Q1 (m 3 s -1 ) 1.883 2.191 

Q1 (l s -1 ha -1 ) 6.470 5.646 

Q1 runoff event volume (m 3 ) 32428 41825 

Q30 (m 3 s -1 ) 5.859 6.717 

Q30 (l s -1 ha -1 ) 20.134 17.311 


Q100 (m 3 s -1 ) 7.635 8.729 

Q100 (l s -1 ha -1 ) 26.238 22.497 


Table 2. Pre-development catchment characteristics and response 

28

5.4 Assessment of Increase in Runoff following 

Development 

Application of the method for the return periods, impermeable areas, 

semi-permeable areas and design rainfalls shown yielded model outputs 

as shown in Table 3 and Table 4. 

29 

Afon Alwen 

No. 3 

Afon Alwen 

No. 4 

Return period (yr) 1 30 100 1 30 100 

Impermeable area (m 2 – Table 1) 720 540 

Design rainfall (mm) 13.0 42.5 56.9 12.9 42.3 56.8 

Runoff volume off impermeable 

area, inc 20% increase for climate 

change (m 3 ) 

Greenfield runoff volume from 

impermeable area predevelopment 

and without climate 

change (m 3 ) 

Increase in volume from 

impermeable area (m 3 ) 

11.3 36.7 49.2 8.4 27.4 36.8 

7.4 21 27 5.7 16.1 20.6 

3.9 15.7 22.2 2.7 11.3 16.2 

Table 3 Post-development characteristics and response: impermeable 

areas

Afon Alwen No. 3 Afon Alwen No. 4 

Return period (yr) 1 30 100 1 30 100 

Semi-permeable area (Table 1 

– m 2 ) 

11,671 7,580 

Design rainfall (mm) 13.0 42.5 56.9 13.0 42.5 56.8 

Runoff volume off semipermeable 

area (m 3 182 596 796 117 385 516 

) 

assuming 120% PR (allowing 

for climate change) 

Greenfield runoff volume from 

semi-permeable area predevelopment 

and pre-climate 

change (m 3 120 340 438 80 226 289 

) 

Increase in volume from semipermeable 

area (m 3 ) 

62 256 358 37 159 227 

Table 4 Post-development characteristics and response: semi-permeable 

areas 

This analysis shows that the amounts of additional runoff attributable to 

the development of impermeable surfaces in the catchment are very small 

in absolute amounts, being only 22.2m 3 for the Afon Alwen No. 3 

catchment and 16.2m 3 for the No 4. catchment in the 100-year + climate 

change scenario. The much larger areas of semi-permeable surfaces are 

reflected in larger corresponding volumes in the 100-year + climate 

change scenario: 358 and 227 m 3 for the No 3 and No 4 catchments 

respectively. For both types of surface, a worst-case scenario of 100% 

runoff is assumed (+ climate change allowance). The general approach to 

managing these volumes of runoff are set out in the following paragraphs. 

Linearly scaling the above analysis from the planned 1260 m 2 of 

impermeable surfaces in Afon Alwen catchments 3 and 4 to the 22,010 m 2 

for the site as a whole (Table 1), the total storage to be provided for the 

entire development would be 679 m 3 . 

30

5.5 Outline Surface Water Drainage Strategy – 

Overview 

The proposed drainage strategy is outline only and is not intended as a 

detailed design. The object of the strategy is to ensure that additional 

volumes of runoff generated from the areas of hard standing in the 

development do not increase downstream risks. This is required to be 

achieved in two ways: 

• for impermeable surfaces, appropriate storage is required using 

SUDS features such as ponds and wetlands; 

• for semi-permeable surfaces, local infiltration should be utilised by 

implementing best practice trackway drainage solutions designed to 

dissipate flow onto low-gradient slopes close to source areas. This 

will prevent sediment transport towards watercourses as well as 

achieving runoff infiltration. 

For the impermeable surfaces, the required storage of 679 m 3 (Section 

5.4 above) represents a very modest requirement. In the context of an 

extreme flood draining to Denbigh (named in the draft CFMP) or Ruthin, 

the effect of the storage would be indistinguishable from the runoff 

response from the catchment in its existing state (equivalent to sub- 

millimetre changes in peak water level). Provision of such storage would, 

however, normally require excavation/construction works (presumably in 

each major catchment draining the site), which would in each case 

mobilise sediment and pose a threat to aquatic habitats. Ideally, such 

storages would be located off-line (away from watercourses themselves) 

in order to reduce these risks, but this approach is likely to increase the 

number of sites at which works were required, again increasing risks to 

the environment. 

Given these risks, we suggest two alternative responses to the minimal 

flood risks presented by the impermeable surfaces of the proposed 

development: 

31

1. Do nothing – on the grounds that the environmental consequences 

of the environmental interventions required to provide storage 

would not be justified by the small benefits to downstream flood 

risk; or 

2. Implement some riparian enhancements to watercourses draining 

runoff from the development site, e.g. creation or restoration of 

wetlands, or of riparian woody vegetation. This would be expected 

to lead to some flow attenuation effect, albeit one which may be 

difficult to quantify accurately, but would also lead to benefits in 

terms of biodiversity, water quality and conservation objectives, 

and landscape aesthetics. Measures ought to be low cost to install 

and maintain. 

The latter option appears attractive from an environmental perspective 

but would be contingent on cooperation of relevant landowners. The 

former option is considered justifiable given the insignificant change in 

flood risk presented by the development, but the latter may be a course 

of action which the developer would wish to promote if considered 

practical. 

For the semi-permeable surfaces, correct design of the drainage is an 

important element in maintaining the continued stability of peat, 

minimising erosion and the potential for pollution of the watercourses 

draining the site. The following principles are to be included within 

construction method and design of the access tracks and associated 

drainage ditches: 

• The depth of individual drainage ditches will be kept to the 

minimum necessary to allow free drainage of the tracks, and drain 

lengths should be minimised to avoid disruption of natural drainage 

directions. The use of swales should be considered where practical. 

Direct drainage into existing watercourses should be avoided as far 

as possible to ensure that sediment and runoff from disturbed 

ground is not routed directly into watercourses. 

32

• Larger historical drains will be piped directly under the track 

through appropriately sized drainage pipes or culverts. Where 

appropriate, a shallow, lateral drainage ditch will be cut along the 

uphill side of the access tracks to intercept the natural run off. This 

lateral drain will be piped under the track at regular intervals 

through correctly sized cross drains away from watercourses. 

Elsewhere, the cross drainage pipes will out-fall into a shallow 

drainage ditch cut directly downhill as a fan, and at minimum slope 

until the bottom of the ditch reaches the natural surface level. The 

drained water will hence be dispersed at low velocity onto the 

hillside where the runoff will be attenuated and the sediment 

trapped by the natural vegetation. 

• The camber of the tracks will be set to encourage surface water to 

drain to the up slope side drainage ditch. Where appropriate, a 

second lateral drainage ditch on the down slope side of the access 

track may catch additional runoff from the track itself. This lateral 

ditch will also outfall into the drainage ditches cut directly downhill 

from the cross drains. 

• In cases where the tracks must run significantly downhill, 

transverse drains (‘grips’) will be constructed where appropriate in 

the surface of the tracks to divert any runoff down the road into the 

down-slope drainage ditch. 

Infiltration trenches/soakaways or other measures promoting infiltration 

will serve all areas of hardstanding and will also be provided locally below 

each turbine base, subject to local conditions. 

Guidance on forest felling, particularly in relation to sediment mobilisation 

and transport, is provided in the hydrology section of the Environmental 

Statement supporting the planning application. Following this guidance, 

which is based on the Forests and Water Guidelines, will ensure that 

appropriate mitigation is achieved. 

33

5.6 Construction 

Appropriate methods will need to be employed during the construction 

phase (prior to the installation of a fully operational system) to mitigate 

against potential downstream risks. These methods may include the 

provision of temporary off-line storage ponds/basins, which could act as 

settlement ponds. 

34

6 Conclusions 

This FCA has assessed the full spectrum of potential flooding risks relating 

to the proposed wind farm development. There is no property at risk of 

flooding on the site, though there are downstream properties at risk. The 

focus is therefore to ensure that rates of runoff under extreme rainfall do 

not lead to any increase in flood risk downstream. 

Two catchments were selected as being illustrative of the magnitude of 

change in runoff response likely following development. In each of the 

two catchments selected, the impermeable areas covered by foundations 

and buildings were found to be approximately 0.02% and 0.01% of the 

Afon Alwen No 3 and No 4 catchments respectively – only very small 

proportions of their respective catchments. Semi-permeable surfaces 

extended to larger areas (0.40 and 0.20% respectively) of the two 

catchments. In the context of the Flood Estimation Handbook guidance, 

these catchments in the post development flood regime would not be 

considered to be significantly different from the current rural flood regime. 

Runoff volumes from the impermeable areas in a 100-year + climate 

change scenario extend to a modest 38m 3 for the two catchments 

combined, given the small areas of impermeable surfaces involved. For 

the site as a whole, the total volume required is 679 m 3 . We consider this 

to be a very small volume in the context of the three main catchments 

draining the site (Afon Clywedog, Afon Clwyd and Afon Alwen) which 

presents an imperceptible risk to downstream property. We therefore 

conclude that no storage is required, particularly given the possible risk of 

environmental damage in providing it, but suggest that the provision of 

enhancements to riparian vegetation or wetlands downstream may be the 

most appropriate course of action given the benefits to biodiversity and 

water quality to be expected as well as attenuation of flood flows. Runoff 

from semi-permeable surfaces would be subject to infiltration techniques 

which would be expected to fully mitigate any increases in downstream 

flood risk. 

35

On the basis of a literature review, forest clear-felling is not expected to 

lead to increases in flood risk. The provision of riparian enhancements 

should help mitigate any increases which might occur as a result of this 

land use change. It should also be noted that effects tend to dissipate 

with time. 

36

References 

Boorman, D.B., Gannon, B., Gustard, A., Hollis, J.M. and Lilly, A. 1994. 

Hydrological aspects of the HOST classification of soils. Report 

prepared for MAFF. Institute of Hydrology. Wallingford 

Breschta, R.L., Pyles, M.R., Skaugset, A.E. and C.G. Surfleet 2000. 

Peakflow responses to forest practices in the western Cascades of 

Oregon, USA. Journal of Hydrology, 233: 102-120. 

CIRIA (2004) Funders report CP/102 Development and Flood Risk – 

Guidance for the Construction Industry, CIRIA 

CIRIA 697 (2007) The SUDS Manual, CIRIA 

CIRIA 103 (2004) Interim code of practice for Sustainable Drainage 

Systems, CIRIA 

Defra/EA (2004) Review of impacts of rural land use and management on 

flood generation. R&D Technical Report FD2114/TR 

Forestry Commission, 2003. Forests and Water Guidelines. Fourth Edition. 

Forestry Commission. 

Kaimowitz, D. 2004. The great flood myth. New Scientist, 19 June p19. 

Marshall, D.C.W. and Bayliss, A.C. (1994) Flood Estimation for small 

catchments. Institute of Hydrology Report 124, Wallingford. 

McDonnell, M. 1999. The drainage behaviour of afforested and clearfelled 

peatlands. Unpublished Master Engineering Science thesis. National 

University of Ireland, Galway. 

Newson, M (2009) Land, Water and Development, 3 rd edition. Routledge: 

London. 

PPS25, (2006), Planning Policy Statement 25: Development and Flood 

Risk, Local Government and Communities. 

NERC (1975) Flood Studies Report, 5 volumes, London. 

NSRI (2009) Soils Site Report No. 28482852. National Soil Resources 

Institute, Cranfield University. 

37

Robinson, M. and Dupeyrat, A. 2005. Effects of commercial timber 

harvesting on streamflow regimes in the Plynlimon catchments, mid- 

Wales. Hydrological Processes, 19: 1213-1226. 

Ward, R C and Robinson, N (2000) Principles of Hydrology, 4 th edition. 

McGraw-Hill, Maidenhead. 

Wright, K.A., Sendeck, K.H., Rice, R.M. and R.B. Thomas. 1990. Logging 

effects on streamflow: storm runoff at Caspar Creek in NW California. 

Water Resources Research, 26: 1657-1667. 

38

Annex F6 

Methodology and reasons 

for choosing mineral sites

Clocaenog 

Methodology and reasons 

for choosing mineral sites 

Land & Mineral 

Management Ltd 

01 June 2010

Notice 

Clocaenog 

Methodology and reasons for choosing mineral sites 

This report was produced by Land & Mineral Management Ltd for RWE for the 

specific purpose of outline selection of borrow pit locations for Clocaenog Wind 

Farm 

This report may not be used by any person other than RWE without express 

permission. In any event, Land & Mineral Management Ltd accepts no liability 

for any costs, liabilities or losses arising as a result of the use of or reliance upon 

the contents of this report by any person other than RWE 

Report Version Control 

Version Date Author / Checked by Change Description 

1.0 12-05-10 LL Document created 

1.1 24 -05-10 LL / JS (RWE) Amended 

1.2 01-06-10 LL Final

Clocaenog 

Methodology for mineral sites 

Initial Work 

Forestry Commission Wales commissioned an Aggregate Potential Study in June 

2006 from Halcrow Group Limited which concluded that FCW landholdings in 

Strategic Search Area A had aggregate potential, suitable for use in constructing 

tracks. 

Prior to Land & Mineral Management’s involvement, ERM Consulting carried out a 

desk-based assessment of potential borrow pit locations within the Clocaenog Forest 

Wind Farm development area. A copy of this report is included in Appendix 1. 

The initial assessment for suitable locations took the form of assessment of locations 

from current and old OS maps showing potential previous mineral extraction areas, 

building on the previous work done by ERM. 

The geology of the wider area was also considered and it was concluded from this 

that the availability of stone should not be a significant constraint, although local 

areas of peat should be avoided. Geological information confirmed that all of the 

search area appeared to have useable quality stone, with minimal overlying 

deposits. 

This information was combined with the constraints which were already known from 

an ecological perspective and also the buffer zones surrounding the turbines 

themselves. FCW’s concerns about removal of trees in specific areas were an 

additional factor. 

This exercise identified eight potential sites which were assessed to provide an 

adequate distribution of resources across the project area. 

A site visit was undertaken to assess each of the potential sites. This resulted in 

several sites being discarded and several other additional sites being identified. 

Initially the sites were identified numerically. The original borrow pit locations 

considered and those added later (following the site visit) are shown on the plan in 

Appendix 2. 

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Those discarded from the first stage assessment were: 

Borrow Pit 3 was considered to have little merit as it was a flat site, with little 

opportunity to screen the extraction, with awkward access to the rest of the 

development, and with no visible stone or evidence of previous workings to 

guarantee security of resource. 

Borrow Pit 5 was in close proximity to Borrow Pit 4 and on balance Borrow Pit 4 

appeared a more suitable location. Since locating two borrow bits so closely made 

little operational sense and could result in a cumulative impact issue, the decision 

was made to continue to consider only one borrow pit in this location and Borrow Pit 

4 was preferred. 

A site visit was carried out on the 10 th December 2009 to look at the potential 

borrow pit locations and how they might be worked operationally and also to 

consider the suitability of the rock. Following the site visit, an appraisal of suitability 

was made in general terms based on the method and direction of working which 

could be used at each potential borrow pit location and visibility, accessibility, 

provision of adequate working space and ability to meet likely stone requirements 

throughout the construction programme. 

The local topography at each site was used to influence direction of working to 

maximise available stone while minimising the footprint of the extractive area. In 

conjunction with this work, a civil engineering company experienced in mineral 

extraction, including establishing borrow pits, and wind farm track construction 

inspected the Clocaenog site on the 26 th January 2010 and considered the proposals 

in terms of tonnages required, timings and constraints. They did not identify any 

issues which would prevent the exploitation of the sites identified in the exercise 

described below. 

This exercise resulted in discarding Borrow Pit 2, as the visual impact of working this 

site was considered to be very high, with also potential issues on safety as it would 

have had plant working close to an access road with a steep drop. The footprint of 

the borrow pit would also have been large in relation to the potential stone yield. 

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Borrow Pit 7 showed signs of previous working, although it was overgrown and had 

limited exposed faces. It was considered that a small scale working may have been 

possible in this location, but ultimately this location was discounted due to its 

proximity to the anemometry mast and the turbulence that a quarry in this location 

would cause. 

Borrow Pit 8, a site suggested as being potentially suitable by staff at Forestry 

Commission Wales, showed extensive and recent signs of stone extraction and was 

initially thought to have good potential because of the accessibility of the stone due 

to the topography. However, consideration of the direction in which it could be 

worked and further discussions with Forestry Commission Wales regarding sensitive 

trees (Red Squirrel habitat) as well as the fact that the borrow pit may encroach on 

the micrositing area for the closest turbine combined to relegate this site to a fall 

back option. 

However in considering Borrow Pit 8, an alternative location to the south, off the 

same access track was identified. This site, although still relatively close to a 

turbine, offered a good reserve of stone with a limited extraction area, by working 

with the relatively steep local topography. Another benefit of this location was that 

the trees are due to be felled to facilitate the wind farm development so the need for 

additional felling would be reduced. Further consideration of the site confirmed that 

it would potentially offer a maximum depth of 30m, but result in a minimal visual 

impact. This site became Borrow Pit 10. 

Borrow Pit 9 was a new location identified on the site visit as being just to the west 

of the development area, and clearly a quarry which had been used in recent years. 

It had potential to be a good site with good access, well screened, substantial 

working areas and a potential for further extraction. However subsequent 

discussions with Forestry Commission Wales identified the location as Chapel Quarry 

and that it was not available for this project. 

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Liaison with FCW 

A number of discussions were held between Jeremy Smith (Npower Renewables) 

and Andrew Maberley Jones (Forestry Commission Wales) which covered wind farm 

stone requirements, FCW’s initial views on approach (number of borrow pits, scale, 

dispersion, approach in terms of ownership of mineral rights), FCW’s preferences in 

terms of potential locations, and fulfilling the requirements of FCW’s mineral 

guidance. 

The final approach to borrow pits reflects these discussions. 

Final Outcome 

Further work was done on the four sites which remained out of the original ten. 

These have been re-named, as A – D. 

In terms of design, this included a more accurate assessment of the extractive area 

and establishing the potential reserves each had to offer. This included creating 

cross sections for each borrow pit which provided a valuable insight into the 

landform which would be created at each site. In parallel, these preferred locations 

were provided to ERM Consulting for assessment via the Environmental Impact 

Assessment process – the findings being included in the Environmental Statement – 

and nothing in either of these exercises resulted in any further sites being discarded 

and the process was considered to have been completed at the identification of four 

sites more than capable of meeting the need for stone anticipated through the life of 

the development. 

The locations of the final four preferred borrow pits are shown on the plan in 

Appendix 3. 

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4

1.1 OVERVIEW 

CLOCEANOG WIND FARM 

BORROW PIT SEARCH MEMORANDUM 

ERM was asked by NPower Renewables Ltd (NRL) to identify potential 

borrow pit locations on the Clocaenog Forest Wind Farm site. This memo 

details the search criteria used to identify the most suitable search areas for 

borrow pit locations, and provides the results of a site visit to identify specific 

borrow pit locations. 

1.2 SEARCH CRITERIA 

1.2.1 Rock Type 

Two main rock types have been identified on site from British Geological 

Society (BGS) 1:50,000 Geology Maps. The north of the site comprises deposits 

of the Upper Nantglyn Flags Group, up to 650 m in thickness, while the south 

of the site comprises deposits of the Denbigh Grits Formation, ranging in 

thickness between 750 m and 1,500 m. 

Evidence of disused quarries (used to construct forestry access tracks) in both 

rock types, suggests that they may also be suitable for wind farm road 

construction. However, it should be noted that the load bearing requirements 

of wind farm access tracks (up to 72 tonnes travelling weight of large 

construction cranes (1) ) is significantly greater than that of forestry access roads 

(44 tonnes design load (2) ). It is therefore recommended that further 

geotechnical investigation is undertaken to confirm the suitability of rock for 

providing road aggregate material, prior to final selection of a suitable borrow 

pit location. 

1.2.2 Existing Quarries 

The optimum location for borrow pits will be existing and/or disused 

quarries on site where rock has previously been excavated to construct forest 

access tracks. Some of these quarries may still contain sufficient quantities of 

easily accessible rock to provide for the material requirements of wind farm 

construction. Forestry Commission Wales has provided the locations of 

quarries previously used to construct forestry access tracks. These quarries 

should be considered for suitability prior to identification of new borrow pits 

through the search criteria discussed below. 

(1) SNH (2005), Constructed Tracks in the Scottish Uplands 

(2) Forestry Commission (2003), Road Specification with reference to the DfT Design Manual for Roads and Bridges 

(DMRB) 

ENVIRONMENTAL RESOURCES MANAGEMENT NPOWER RENEWABLES 

1

1.2.3 Rock Exposures 

The majority of the site is overlain by glacial till (boulder clay) deposits of 

unknown thickness, while the higher parts of the site (eg around Craig Bronbanog, 

Foel Frech and Foel Goch) have no superficial deposits (i.e. rock is 

exposed at the ground surface). Alluvial sediments are found to the south of 

the site along the Nant y Ffridd, River Clwyd and River Alwen valley floors, 

and to the north along the Afon Clywedog and Afon Corris valley floors. 

Localised deposits of peat occur along the valley of Nant Llyfarddu (from SJ 

003 524 to SJ 023 535) and in smaller pockets to the north and west of the site. 

The optimum siting of borrow pits is in areas where the rock is exposed at the 

surface, to reduce the requirement for excavation of overburden material 

before the underlying bedrock can be accessed. Figure 1 identifies the broad 

areas of search where there are limited superficial deposits (i.e. rock is 

exposed or close to the ground surface). 

1.2.4 Steeper Slopes 

Sloping ground tends to be overlain by thinner soils and thinner layers of 

superficial deposits, thereby reducing the requirement to excavate overburden 

material before the underlying bedrock can be accessed. Steep slopes also 

allow direct access into the rock face from the side, as opposed to excavating 

down from above. 

1.2.5 Proximity to Existing/Proposed Access Tracks 

Ideally the borrow pits should be located adjacent to existing access track 

infrastructure, or in close proximity to proposed new tracks, to avoid the need 

to construct additional new tracks. Combining proximity to access tracks with 

steep slopes will provide the optimum location, where the borrow pit can be 

accessed directly on the upslope side of an existing track. 

1.2.6 Proximity to Surface Watercourses and Springs 

An appropriate buffer should be applied to surface watercourses, springs and 

standing water bodies to reduce the risk of sediment pollution originating 

from surface water runoff flowing over exposed ground/excavations. As a 

minimum the buffer zones should reflect those recommended in the Forest 

and Water Guidelines, as set out in Table 1.1. 


2

Table1.1 Forest and Water Guidelines Recommended Riparian Buffer Zones 

Surface watercourse Recommended buffer 

Channel > 2 m wide 

20 m 

Lakes and reservoirs 

Channel 1 – 2 m wide 

Channel < 1m 

Channel

Figure 1.1 Borrow pit search areas and recommended locations 


4

Table 1.2 Borrow pit search areas 

Search Area Suitability Notes Photo 

A Suitable 

B Not suitable 

Steep sloping area to north and west of forest track in area of Upper 

Nantglyn Flags bedrock with limited superficial deposits. Location of 

existing FCW borrow pit B1 (see Table 1.2). Ideal location for extension to 

existing borrow pit or creation of new borrow pit. 

Sloping area to west of public road and south of forest track in Upper 

Nantglyn Flags bedrock. Not ideal as not very steep sloping and no 

obvious rock exposures.

Search Area Suitability Notes 

Hill slope to north of public road in Upper Nantglyn Flags bedrock. 

Photo 

C Suitable 

Existing FCW borrow pit was not found during site visit as area is now 

reforested. Potential new borrow pit location identified to east of search 

area (see Table 1.2, B3). 

Area to north of Foel Frech summit in Upper Nantglyn Flags bedrock. No 

No photo 

D Not suitable steep slopes or rock exposures, very close to bird hide/viewpoint on Foel 

Frech and black grouse areas? 

No photo 

E Not suitable 

F Not suitable 

G Suitable 

H Suitable 

I Suitable 

Area to south of Foel Frech summit in Upper Nantglyn Flags bedrock. No 

steep slopes or rock exposures, very close to bird hide/viewpoint on Foel 

Frech and black grouse areas? 

Area to northwest of existing forest track in Upper Nantglyn Flags 

bedrock. No steep slopes or obvious rock exposures. 

Area to west of existing forest track in Upper Nantglyn Flags bedrock. 

Ideal location for potential borrow pit due to steep slopes adjacent to 

track. Avoid going too far north in search area due to presence of two 

private water supplies (17 and 18). 

Rock exposure around summit of Craig Bron-bannog in Denbigh Grits 

bedrock. Existing FCW borrow pit B6 located in south of this area. 

Potential to expand this borrow pit or open a new one, ideally in south of 

search area where slopes are steeper. 

Area to east of existing forestry track in Denbigh Grits bedrock. Large 

existing, disused FCW borrow pit B7 may have potential to be expanded. 

No photo 

See B4 and B5 in Table 1.2 

See B6 in Table 1.2 

See B7 in Table 1.2

Table 1.3 Recommended borrow pit locations 

Name Easting Northing Search Area Notes Photo 

B1 301841 357403 A 

B2 302010 357467 A 

Existing large borrow pit to north of forest track. Ideal 

for northern borrow pit, provided enough rock available 

and FCW allow use for wind farm. 

Potential borrow pit area northeast from existing 

quarry.


B3 301464 354694 C 

Potential area for new borrow pit, to northwest of forest 

track where it leaves public road 

B4 302565 354284 G 

B5 302541 354124 G 

Potential area for new borrow pit, to west of existing 

track on reasonably steep-sided slope 

Potential area for new borrow pit, to west of existing 

track on reasonably steep-sided slope 

No photo


B6 301846 351413 H Existing borrow pit on south side of Craig Bron-banog 

B7 300679 351949 I Existing borrow pit near proposed turbine location

© Copyright npower renewables Ltd. No part of this map may be reproduced without prior permission 

0 445 − 890 1,780 Metres 

LEGEND 

Original borrow pit locations and those 

identified at the site visit. 

Created by: 

JMS Checked by: 

Content custodian: 

The content of this map can only be modified with 

the consent of the above named person 

Reproduced by permission of Ordnance Survey 

on behalf of HMSO. © Crown Copyright 

and database right 2006. All rights reserved. 

Ordnance Survey Licence number 100018338 

npower renewables 

Third Floor 

Reading Bridge House 

Reading Bridge 

Reading 

RG1 8LS 

T +44 (0)118/95 92 440 

F +44 (0)118/95 92 526 

I www.npower-renewables.com 

Sheet size: A3 Scale of original: 1:30,406 

Site: Clocaenog Forest Wind Farm 

Date: 

A 

1/6/10 Rev: 

Title: Appendix 2 - Original borrow pit locations 

and those identified at the site visit 

GIS File Reference: JS/Appendix_2

360000 .000000 

359000 .000000 

358000 .000000 

357000 .000000 

356000 .000000 

355000 .000000 

354000 .000000 

353000 .000000 

352000 .000000 

351000 .000000 

300000 .000000 

7 

.000000 

7 

D 

301000 .000000 

.000000 

302000 .000000 

C 

A 

.000000 

B 

303000 .000000 

.000000 

304000 .000000 

.000000 

305000 .000000 

.000000 

306000 .000000 

− 

Kilometers 

0 0.35 0.7 

Legend 

SSA A - Development Boundary 

SSA A Borrow Pit Operational Areas 

SSA A Existing Tracks 

SSA A New Spur Roads 

SSA A New Tracks 

7 SSA A Permanent Met Masts 

SSA A PMM Hardstandings 

SSA A Substation or Civils 

SSA A On Site Cabling 

Created by: Checked by: Date: Rev: 

Content custodian: 

The content of this map can only be modified with 

the consent of the above named person 

Reproduced from Ordnance Survey 

digital map data (c) Crown Copyright 2010. 

All rights reserved. Licence number 0100018338. 

Unit 22 

Technium Sustainable Technologies 

Baglan Energy Park 

Central Avenue 

Port Talbot 

SA12 7AX 

Sheet size: A3 

Site: 

JAP 

npower renewables 

JS 

28.05.10 

T +44 (0)1639 816180 

F +44(0)1639 816051 

I www.npower-renewables.com 

Scale of original: 

1:25,000 

Clocaenog Wind Farm (SSA A) 

Borrow Pits 

Operational Location Plan 

Title: 

Borrow Pit A (Grid Ref = 301897, 357586) 

Operational Site Site Area = 3.92 ha 

Extraction Site Surface Area = 3.03 ha 

Volume of minerals to be extracted =

F. Geology & Hydrology ( PDF | 31.0 MB ) - RWE.com

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