Appendix 7.2: Outline Peat Management Plan · 2014. 9. 5. · Outline Peat Management Plan V1 2 Investigating the impacts of wind farm development on peatlands in England: Part 1

Rooley Moor Wind Farm Environmental Statement

Appendix 7.2: Outline Peat Management Plan

Rooley Moor Wind Farm

CORONATION POWER

Outline Peat Management Plan

V1 | REV C

18th August 2014


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Rooley Moor Wind Farm

Project no: JE30481

Document title: Outline Peat Management Plan

Document no: V1

Revision: REV B

Date: 25 Jun 2014

Client name: Coronation Power

Project manager: Jo Moran

Author: Hannah Russell and Peter Skinner

File name: C:\Users\jmoran\AppData\Local\Microsoft\Windows\Temporary Internet

Files\Content.Outlook\NUF78R7K\Rooley_Moor_OPMP_revised_120814 FINAL (2).docx

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COPYRIGHT: The concepts and information contained in this document are the property of Sinclair Knight Merz (Europe) Limited (Jacobs). Use

or copying of this document in whole or in part without the written permission of Jacobs constitutes an infringement of copyright.

Document history and status

Revision Date Description By Review Approved

REV A 20/06/2014 First draft for practice review P Skinner M Brown -

REV B 25/06/2014 Revised draft for practice review H Russell M Brown M Brown

REV B 30/06/2014 Draft for client Comment H Russell E Romaine E

Romaine

Rev C 13/08/2014 Updates for revised layout H Russell C Stewart C Stewart


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Contents

1. Introduction ................................................................................................................................................ 1

1.1 Objectives ....................................................................................................................................................................................... 1

1.2 Policy and Guidance for Peat Management ................................................................................................................................... 1

1.2.1 Legislation and Guidance ............................................................................................................................................................... 1

2. Peat Conditions on Site ............................................................................................................................ 3

2.1 Definition of Peat ............................................................................................................................................................................ 3

2.2 Sources of Information .................................................................................................................................................................... 3

2.3 Description of Peat at Rooley Moor ................................................................................................................................................ 3

3. Avoidance, Minimisation, Handling and Reinstatement ....................................................................... 8

3.1 Introduction ..................................................................................................................................................................................... 8

3.2 Further minimisation before and during the construction phase ..................................................................................................... 8

4. Peat Balance .............................................................................................................................................. 9

4.1 Excavation and Reinstatement Volumes ........................................................................................................................................ 9

4.1.1 Turbine Foundations ..................................................................................................................................................................... 10

4.1.2 Crane Hardstandings .................................................................................................................................................................... 10

4.1.3 Construction Compound, Control Building and Substation ........................................................................................................... 11

4.1.4 New Access Tracks ...................................................................................................................................................................... 11

4.1.4.1 Floating Tracks ............................................................................................................................................................................. 11

4.1.4.2 Cut and Fill Tracks ........................................................................................................................................................................ 11

4.1.5 Borrow Pits.................................................................................................................................................................................... 11

4.1.6 Cable Trenches............................................................................................................................................................................. 12

4.2 Net Balance .................................................................................................................................................................................. 13

5. Excavation, Storage, Re-use and Restoration ..................................................................................... 14

5.1 Excavation .................................................................................................................................................................................... 14

5.2 Temporary Storage ....................................................................................................................................................................... 14

5.3 Bare Peat ...................................................................................................................................................................................... 15

5.4 Infrastructure Reuse ..................................................................................................................................................................... 15

5.4.1 Cut and Fill Access Tracks ........................................................................................................................................................... 16

5.4.2 Floating Access Tracks ................................................................................................................................................................. 16

5.4.3 Turbine Foundations and Hardstanding........................................................................................................................................ 16

5.4.4 Borrow Pits.................................................................................................................................................................................... 17

5.5 Reuse of Peat for Other Restoration Purposes ............................................................................................................................ 17


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1. Introduction

1 This draft Peat Management Plan (PMP) has been prepared as part of the Environmental Impact

Assessment (EIA) accompanying the planning application for Rooley Moor Wind Farm (the

‘Development’).

2 The draft PMP will be further developed and implemented subsequent to the Development receiving

planning consent. Further details and specific plans will be determined during the detailed design

process and once further site investigations have been undertaken. These details will then be included

in a PMP as a part of the appointed Principal Contractor’s detailed Construction Environmental

Management Plan (CEMP) for the Development. A draft CEMP is provided in Appendix 4.1 of this

Environmental Statement. The PMP addresses the management of peat during construction and

immediate restoration.

1.1 Objectives

3 Peat has been afforded significant consideration throughout the Rooley Moor Wind Farm design

process. This is in response to concerns raised by statutory and non-statutory stakeholders during the

scoping phase which identified impacts to peatlands as a concern. It is understood this is largely in

response to ‘lessons learned’ following the development of the Scout Moor Wind Farm, adjacent to the

proposed Rooley Moor Wind Farm.

4 The role of the PMP is to demonstrate that the management of peat excavated during construction of

the Development has been considered and will be treated appropriately during the construction

process. Together with the proposed Habitat Management measures (refer to Chapter 8: Non-Avian

Ecology) it presents mitigation measures that will minimise any impacts on peat, and assist the long

term habitat restoration and management plans for key peatland areas of the site, that are designed to

enhance the site through improvement of the ecological habitat.

5 The PMP outlines the overall design approach that has been applied to the Development to minimise

peatland disruption and aims to ensure that all further opportunities to minimise peat disturbance and

extraction during construction will be taken.

6 The PMP identifies appropriate and industry proven methods for the reuse of excess peat to restore

the effects of construction activities, without significant environmental or health and safety implications

and to reduce the release of carbon and minimise risk in terms of human health.

1.2 Policy and Guidance for Peat Management

1.2.1 Legislation and Guidance

7 Peat as a carbon landscape has the capacity to act as a carbon sink. The management of peat

therefore has implications for carbon emissions and climate change. The legislation and guidance

regarding climate change and carbon which is relevant to the management of peat includes:

The Kyoto Protocol (Ref. 1) and the Kyoto Protocol and National Accounting for Peatlands (Ref. 2);

The UK Climate Change Act (Ref. 3);

The Carbon and Water Guidelines, Carbon Landscapes and Drainage (Ref. 4);

Forests and climate change: UK Forestry Standard Guidelines, Forestry Commission (Ref. 5);

Scottish Environment Protection Agency (SEPA), Regulatory Position Statement – Developments on

Peat (Ref. 6);

Scottish Government, Guidance on Developments on Peatland – Site Surveys (Ref. 7);

Floating Roads on Peat, Scottish Natural Heritage (Ref. 8);

Guidance on the Assessment of Peat Volumes, Reuse of Excavated Peat and the Minimisation of

Waste, Scottish Renewables and SEPA (Ref. 9).

8 The following guidance specifically relates to wind farm construction and peatland restoration:


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Investigating the impacts of wind farm development on peatlands in England: Part 1 Final Report,

(Ref.10)

Best Practice Guidance to Planning Policy Statement 18 ‘Renewable Energy’, (Ref. 11);

Wind Farm Developments on Peat Land fact sheet. Scottish Government (Ref. 12); and

Good practice during wind farm construction, A joint publication by Scottish Renewables, Scottish

Natural Heritage, Scottish Environment Protection Agency, Forestry Commission Scotland (Ref. 13).

9 It is acknowledged that many of the publications listed above have been developed by the Scottish

Government; this is due to the recent increase in wind farm developments in upland areas with peat

and the need for legislation and guidance to mitigate negative impacts. The Scottish documents are

considered to be best practice within the UK and are therefore appropriate for use within this OPMP.


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2. Peat Conditions on Site

2.1 Definition of Peat

10 Peat is defined as the partially decomposed remains of plants and soil organisms which have

accumulated at the surface of the soil profile (Ref.14). Active peatlands are traditionally described

using a simple 2-layer model; the acrotelm including active peat vegetation and catotelm (Ref.15).

This simple two-layer conceptual understanding has been developed to aid a hydrological and

ecological understanding of peat ecosystems.

11 The acrotelm is the upper aerobic layer of peat and consists of living and partially decayed plant

material. It typically has a higher hydraulic conductivity than underlying peat and is defined with

relation to distance to the water table. Acrotelm thickness varies with topography - such as hummocks,

peat hags, hollows and with time, especially in drought periods or when it is drained. The catotelm

layer sits under the acrotlem and consists of highly decayed material and is significantly denser. It has

a very low hydraulic conductivity. Conditions are permanently anaerobic and anoxic because the

catotelm is permanently below the water table. The catotelm is less cohesive than the acrotelm layer

and is considered to be less suitable for storage and re-use.

2.2 Sources of Information

12 Assessment has been made of the areal extent, depths and structure of peat likely to be disturbed at

the Development site synthesising multiple data sources. Initially, peatland habitats on site were

identified through desk based studies reviewing published geological, hydrological and ordnance

survey mapping. Following the desk based studies, site walkover surveys were conducted by

ecologists and hydrologists in May 2012. Following on from these surveys, detailed peat probing was

conducted across the wind farm site on a 50m grid in June 2012. Peat cores were also obtained and

logged.

13 The data collected during the desk and field studies are presented within the Rooley Moor Wind Farm

main ES. A summary of the relevant chapters, documents and field studies used in the

characterisation of the peat for this OPMP are presented below;

Chapter 7 Hydrology, Geology and Hydrogeology – Rooley Moor Wind Farm ES

Chapter 8 Non-Avian Ecology – Rooley Moor Wind Farm ES.

Rooley Moor Wind Farm Peatslide Hazard and Risk Assessment Interpretive Report Vol 1 and 2 (June

2014), prepared by Jacobs.

Rooley Moor Wind Farm Peatslide Hazard and Risk Assessment Factual Report (June 2014),

prepared by Jacobs.

Peat depth probing and Peatslide risk assessment surveys carried out in October 2012 (250 survey

points) (see Appendix 7.3 of the ES); and

Water level measurements in peat (20 locations), peat depth probing (98 survey points) and peat core

analysis (64 peat core locations) April 2014.

14 Figures (1-10) of the PSRA Factual Report (ES Appendix 7.3) showing the distribution and depth of

peat across the site as well as all probe, core and dip-well locations sampled during the field work

phases of investigation are located in ES Appendix 7.3.

2.3 Description of Peat at Rooley Moor

15 The Development Area encompasses the eastern extent of an upland plateau which forms Rooley

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

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

ridge along the length of the Development Area. These peaks are Top of Leach located in the north of

the study area (474m aOD), Hammer Hill located in the centre of the study area (440m aOD) and Top

of Pike located in the south of the site (398m aOD)..


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16 These hills form the crest of a watershed which creates five surface water catchments. These

catchments ultimately drain to the River Irwell (north and west), the River Spodden (east) or Nadden

Brook (south) (see ES Figure 7.1). Several of the catchments contain United Utilities (UU) public

water supply reservoirs which receive surface water inputs from many of the watercourses located

within the upper parts of the catchments. A full and detailed description of the surface water

catchments within the Application Site is presented in Chapter 7 of the main ES. Consultation with UU

indicates that water quality in their public water supply reservoirs around Rooley Moor are suffering

from deteriorating water quality. The key issues relate to increasing dissolved organic content (DOC)

in water bodies; this is thought to be due to increasing rates of peat erosion on Rooley Moor and

adjacent Scout Moor.

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

from the FEH (Ref 16) indicating a moderately wet climate having the potential to exhibit a moderately

high runoff regime.

18 Peat depth probing carried out by Jacobs personnel in October 2012 and April 2014 has been used to

produce a detailed peat depth plan for the Application Site (see Figure 10 of the PSRA Factual

Report). The plan shows the presence of peat deposits in the northern, eastern and western areas of

the Application Site. The southern half of the Application Site is mapped as being peat free (


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Table 1 Summary of Peat Characteristics Data

1) Infrastructure 2) Core Location

Average Von Post Humification (H) and

Moisture (B) Scores Average Depth to Water

(m) Acrotelm Catotelm

Met Mast C21, C24 H6 B2 H10 B3 -

New Track C7, C14, C25 H5 B2 H9 B4 -

Track Upgrade C0, C1, C2, C3, C4, C5,

C6 H6 B3 H9 B3 0.05

Turbine 1 C9, C12, C30, C31, C32 H6 B2 H9 B3 0.30

Turbine 2 C8, C33, C34, C35 H6 B3 H9 B3 0.50

Turbine 3 C10, C42, C43, C44 H5 B2 H9 B4 -

Turbine 4 C11, C13, C29 H6 B3 H9 B2 0.55

Turbine 5 C18, C19, C36, C37,

C38 H6 B2 H9 B2

0.33

Turbine 6 C15, C20, C39, C40,

C41 H5 B2 H8 B4

-

Turbine 7 C16, C17, C45, C46,

C47 H6 B3 H9 B4

0.42


Turbine 9 C48, C49, C50 H7 B2 H10 B3 0.50



Turbine 12 C27, C28, C60, C61,

C62, C63 H6 B3 H9 B3

0.00

NOTES (-) indicates no water level data recorded for this location

Detailed description of Von Post scores is presented in Appendix 1

20 In summary, acrotelm thickness measures in core samples ranged from 0m to 0.25m with an average

thickness of 0.1m, across much of the site the peat profile appeared quite degraded. Average water

table depth based on two rounds of water level monitoring indicated average water table depth is

0.25m across the site although there were spatial variations. Water levels were highest around turbine

T11 and T12 in the north of the Application Site. Readings were taken in late spring and seasonal

variations should be expected.

21 Chapter 8 Non-Avian Ecology reports the findings of National Vegetation Classification (NVC)

mapping of the Development Area (see ES Figure 8.3. The survey identified that the majority of the

peat land in the Development Area was vegetated by degraded/modified mire communities such as

M20 Eriophorum vaginatum blanket mire and M25 Molinia caerulea-potentilla erecta mire. Chapter 8:

Non-Avian Ecology suggests that the peat land across Rooley Moor would have formerly been

dominated by blanket mire vegetation. Blanket mire develops in areas of high rainfall, and has an

ombrogenous (that is, rainfall fed) hydrological regime; however, the influence of continuous heavy

grazing (perhaps coupled with burning and atmospheric pollution) the original bog vegetation has

become modified to such to lower ecological value habitat. Much of the peat land across the

Development Area, south of Ding Quarry, around Ding Clegg and further east around Hamer Hill is

therefore considered to be degraded.

22 The findings of the ecology study (see Chapter 8: Non-Avian Ecology) are supported by peat

characteristic analysis; Von-Post humidification scores for the acrotelm were generally H6-H7,


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indicating moderately to highly decomposed peat with a very indistinct plant structure. These scores

are higher than would be expected for a healthy, actively peat-forming acrotelm (which should be less

decomposed) suggesting that the acrotelm layer in the study area is degraded. The interpretation that

the peaty acrotelm is degraded across much of the site is reflected in the moisture von post scores

which were typically B2-B3, indicating a low to moderate moisture content in the peat. Dip-well levels

from piezometers installed in the peat around proposed turbine locations indicated that average water

table depth across the site was 0.25m below the acrotelm layer, across the duration of the study. The

acrotelm needs to be saturated in order to support the bog plants which in turn form peat and help

stabilise it.

23 Two larger areas of M3 Eriophorum angustifolium bog pool communities were mapped to the north of

Ding Quarry (12.36ha) and on Brandwood Moor (13.3ha) (See ES Figure 8.3). According to the JNCC

(2010) (Ref 17), M3 is typically found in areas of shallow peat in acidic environments and is commonly

associated with eroded blanket mire in north-west of Britain. It is reported to represent a seral stage in

the redevelopment of active mire vegetation. Water levels in the peat in these areas were at ground

level, indicating total saturation through the peat profile and an intact hydrological system. In addition,

some small bog pools were observed.

24 No active subsurface drainage pipes were identified in the peat profile during the peat probing

surveys, however, erosional features were observed around the periphery of the active M3 covered

peat to the north of Ding Quarry. Despite this area being the most eroded area of peat, NVC surveys

by ecologists also identified this as the best example of blanket bog in the study area.

25 Erosion in this area of peatland appears to have been caused by significant overland flow across the

peat which is located on the plateau up slope. It may have been exacerbated through drawdown

caused by the loss of peat below the main peat lense as a result of the excavation of Ding Quarry.

Hagging has also occurred where the water flowing across the bog has caused erosion and

subsequent slumping of the overlying peat (see Plate 1 and Plate 2).

Plate 1 Erosion Channel at NGR 385230 419248

Plate 2 View looking to area down gradient of erosion

channel at NGR385088 419192

26 In summary, peat lands are located in the north, east and west of the Development Area; the south is

largely peat free. Much of the peat was found to relatively dry, the active acrotelm layer was typically

thin and water levels were found to be below the main acrotelm layer. Land use such as burning,

grazing and hill walking is thought to have contributed to the degradation of the peat resource here.

Two areas of active peat containing M3 habitat were identified, both areas are located in the north of

the site north of Ding Quarry and around Top of Leach Hill. These areas of active bog were not

considered to be pristine and significant erosion features were noted down gradient of the lense of

peat near Ding Quarry.


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3. Avoidance, Minimisation, Handling and Reinstatement

3.1 Introduction

27 The OPMP has been developed as part of an iterative process with the findings of an initial peat

balance analysis being utilised to further optimize the wind farm design. This has been done in order

to prevent the unnecessary excavation or disturbance of peat.

28 As outlined in the main ES, the wind farm layout avoids development in areas with peat soils greater

than 1.0m depth as far as possible. However, there are a number of constraints at the site, including

utilities and watercourses, which has meant some infrastructure has had to be located on areas with

peat.

29 In these instances, the volume of peat excavated has been further minimised through design

measures such as the inclusion of a floating track design in areas with deeper peat.

3.2 Further minimisation before and during the construction phase

30 In addition to the optimizing work already carried out, the disturbance of peat resulting from the

construction of the tracks, crane harstandings and foundations will be minimised as much as

practicably possible.

31 Utilising all the data collected to date and throughout the construction process, the Principal

Contractor (and / or Designer) will implement methods to minimise the volumes of excavated peat.

Appropriate handling and storage of excavated materials will be undertaken such that their integrity

and subsequent reuse is not jeopardised.

32 An ecological clerk of works (ECOW) will be employed and prior to each phase of construction will

walk the site with engineers, pointing out areas of sensitive habitat and identifying where impact can

be reduced by minor movement of infrastructure within the micro-siting available. These areas will be

clearly marked with post and tape. The ecological clerk of works will also ensure that any micro-siting

does not lead to movements into more sensitive habitats.

33 All contractors will be made aware of the sensitivity of peat habitats. Contractors will be required to

work within the narrowest practical construction corridor when working in or near areas of peat, again

identified by the ECoW and incorporated into method statements.

34 All plans and method statements will be accompanied by justification of the final design and/or

construction methods identified by the Principal Contractor, including reasons for discounting

alternative methods. This is required in order to demonstrate that all avenues for avoiding hydrological

disruption and reducing the disturbance and excavation of peat have been considered.

35 The Principal Contractor will be required to ensure that excavated peat is reused on site in

landscaping and re-profiling works, to minimise visual impacts and facilitate habitat and ecological

restoration, improvement and enhancement.


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4. Peat Balance

4.1 Excavation and Reinstatement Volumes

36 Donaldson Associates have provided the peat excavation volumes and reinstatement volumes

associated with construction of the Development. These have been calculated based on the following

data and assumptions:

a contour map of assumed peat depth based on interpolation of values from probing and coring across

the site;

dimensions of the proposed areas for excavation for site infrastructure;

an estimated acrotelm depth of 0.10m across the site,

an assumption that the probe depth is representative of the actual depth of the peat,

Construction of ten new access tracks leading to turbines, track Nos 9 and 7 are floating tracks and

therefore will not result in any excavation;

The average peat depth at each turbine is 0.4m and the overall excavation for turbine foundations is

26m x 26m in plan;

The average peat depth at each crane hardstanding is 0.63m and the typical size is 45m x 28m;

5 no. laybys will be constructed along access tracks with an average peat depth of 0.3m; and

37 At this stage and based on the location of Development infrastructure in relation to peat depth and

topography it is calculated that all excavated peat can be re-used on site in landscaping/restoration

activities. Table 2 summarises the peat excavation and reinstatement volumes estimated by

Donaldsons, the full calculation sheet is presented in Appendix 2.

Table 2 Indicative Peat Balance

Donaldson ID Infrastructure

Average Peat Depth (m)

Excavated (m3)

Re-instated (m3)

A2 Access Track Upgrade 0.3 1,088 115

A4 Borrow Pit Road 2 0.1 718 1,958

A4 Road 2 0.0 - 1,069

A4 road 2 1.1 6,540 2,998

A4 Road 2 0.0 885

A4 Road 4 0.5 2,657 1,218

A4 Road 6 0.3 2,171 232

A4 Road 7 0.7 1,722 296

A4 Road 9 - Floating 0.7 - 575

A4 Road 3, 5, 8 & 10 T-Heads 0.9 7,140 3,570

A4 Road 7 - floating 0.6 - 486


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Donaldson ID Infrastructure

Average Peat Depth (m)

Excavated (m3)

Re-instated (m3)

A4 Temporary Road 0.3 710 203

A4 Met Mast Road 0.7 1,148 375

A5 New Access road Widening 0.5 2,830

A6 Met Mast 0.0 - 15

A7 Crane Hardstanding (x12) 0.5 7,515 234

A8 Laybys 0.5 420 420

B1 Construction Compound 0.0 -

E5 Control Building 0.3 807 2,301

C4 Turbine Foundations (x12) 0.5 4,032 1,550

F1 Borrow Pits 0.0 - 23,143*

Grand Total 44,094 44,094

NOTES * indicates figure estimated by Jacobs based on volume peat required to reinstate borrow pits with up to 1m peat. (-)Indicates no peat will be excavated at infrastructure

4.1.1 Turbine Foundations

38 During turbine construction, peat will be excavated to the substrate to make room for the concrete

turbine foundation, and for a small working area surrounding the foundation footprint. This initial

excavation will have a 20m diameter. Surrounding the excavation areas is a 1:2 gradient batter, the

plan area of which is determined by the mean peat depth at each turbine. Once excavated, the turbine

foundation is installed, occupying a foundation footprint, up to 20m in width.

39 Peat will be used to cap turbine foundations, full details regarding turbine foundation design are

presented in Chapter 4: Project Description of the main ES. In summary, the cap will comprise

approximately 150mm of topsoil or peat, which will either be flush with the existing ground surface, or

will form a raised mound between 300 and 500mm above the existing ground level, depending on the

depth of the foundation at each specific turbine location. Due to the sloping nature of the site, finished

ground level may have to be built up on the ‘downhill’ side of the foundation. This could be by up to 1-

1.5m depending on the severity of the slope.

40 A total of 4,032m3 of peat will be excavated from turbine foundations; it is estimated a total of 1,550m

3

will be reused in reinstatement and landscaping around the installed turbines. Therefore, there will be

a net excess of peat at turbine locations.

4.1.2 Crane Hardstandings

41 A crane hardstanding is required adjacent to each turbine for the purpose of turbine installation and

maintenance. Each crane pad has an area of 25m x 40m and will required the full excavation of peat

(where present) to substrate and replacement with rock is required to provide a suitably stable surface

for turbine placement.


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42 Once excavated, a small proportion of the peat will be re-used to batter the edges of platforms grading

the bases into the local landscape.

43 A total of 7,515m3 peat will be excavated from crane hardstanding foundations. It is estimated a total

of 234m3 will be re-used in reinstatement and landscaping. The surplus of 7,281m

3 will need to be re-

used elsewhere on site.

4.1.3 Construction Compound, Control Building and Substation

44 The construction compound and substation are all located in areas with no peat (i.e. average peat soil

depth is


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and borrow pit 2 has a surface area of 14,385m2, it is proposed that part of the restoration of the

borrow pits will use 23,143m3 peat material in addition to other soils excavated during wind farm

construction. Peat will be reinstated to a depth of


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4.2 Net Balance

53 The peat balance identifies that approximately 44,094m3 peat will be excavated on the Application Site

and sufficient capacity has been identified to re-use all of this peat on site in landscaping. As a result,

no surplus peat will be generated from excavation resulting in no net loss of peat on Rooley Moor as a

result of the construction of the wind farm.

54 The following section outlines illustrative methods for the handling and re-use of peat, which will be

subject to more detailed design ahead of construction.


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5. Excavation, Storage, Re-use and Restoration

5.1 Excavation

55 Prior to any excavations, the Principal Contractor will produce a detailed Method Statement identifying

where and how excavated peat will be used in reinstatement or landscaping works. Specific

requirements for the excavation, handling, storage and reinstatement of peat will be outlined in this

Method Statement. The Principal Contractor will consider potential impacts on downstream

hydrological receptors and also the potential for instability issues with the excavated material. Some of

the requirements to be contained within this are outlined below.

56 Areas of peat within the footprint of excavation will have the top layer of vegetation stripped off as turf

prior to construction by an experienced specialist contractor. When excavating areas of peat,

excavated turves should be as intact as possible. Often it is easiest to achieve this by removing large

turves, the peat turf will be removed in 300mm layers in order to keep the peat intact.

57 Underlying catotelmic peat will then be removed and stored separately and kept damp following

procedures outlined in the Carbon and Water Guidelines (Ref 4).

58 Excavated peat turf and catotelmic peat will be handled so as to avoid cross contamination between

distinct horizons and ensure reuse potential is maximised.

59 Care will be taken when stripping and removing topsoil and peat turves and appropriate storage

methods used on site, i.e. excavated material will be stored in separate horizons and vegetation rich

top layers will be stored vegetation side up.

60 Classification of excavated materials will depend on their identified re-use in reinstatement works. At

this site it is anticipated that the material to be excavated will comprise peat (which may be sub-

divided into amorphous peat, fibrous peat, and turf), clay and mineral soils (subsoil and topsoil).

5.2 Temporary Storage

61 Excavated peat may need to be stored on site. A temporary shallow peat stockpile will be constructed,

within which the peat can be stored. For deeper peat deposits, the excavation will ensure that the top

vegetation and fibrous layers are kept separate from the deeper humic peat. When storing peat, the

peat profile will be maintained. These peat stores will be bunded using impermeable material (most

likely soils sourced from non-peat soil turbine excavations). The bunds will extend to a level above the

toe of the stockpiled material to provide restraint to surface runoff.

62 Excavated turves will be stored adjacent to the construction area in a way to ensure that they remain

moist and viable. Temporary peat storage areas should be in locations where the water table can be

kept artificially high such as ground hollows, slope toes, ditches and drains.

63 Temporary storage areas required for peat will be identified in the Principal Contractor’s Construction

Method Statement (CMS). This will describe any intended drainage, pollution prevention and material

stability mitigation measures that may be required.

64 The design and location of stockpiles, including incorporated drainage elements, will be agreed with

the ECoW and Geotechnical Consultant / Geotechnical Clerk of Works prior to excavation works

commencing.

65 Temporary peat storage areas will be located so that erosion and runoff is limited, leachate from the

material is controlled, and stability of the existing peatland in the vicinity is not affected. Excavated

material is to be stockpiled at least 50m away from watercourses. This will ensure that any wetting

required on stored peat does not runoff and discharge into adjacent watercourses. Suitable storage

areas are more appropriately sited in areas with lower ecological value and low gradient slopes.

Cleared areas of forestry are preferred to areas of higher ecological value or areas close to

watercourses.

66 In the event of drought conditions, a bowser of similar will be bought to site and stockpiled peat will be

sprayed to maintain high moisture contents and ensure the viability of the peat. Care will be taken to

ensure this does not result on erosion/washing out of stockpiled peat. An up-gradient cut off ditch will


V1 15

be installed around the edge of the storage bund in order to collect up-gradient surface water runoff

and divert water runoff from eroding the bund foot.

67 Any edges of cut peat that may remain exposed, or areas of peat excavation on steep slopes, will be

covered with geotextile or similar approved techniques. This will allow re-turfing and re-vegetation and

reduce erosion risks.

68 Haul distances of excavated peat will be kept as short as possible and as close to intended re-use

destinations to minimise plant movements in relation to any earthworks activity, including peat

management, in order to minimise the potential impact on the peat structure. It is important that

temporary storage is safe and keeps the material suitable for its planned reuse.

69 The handling and storage of peat will seek to ensure that excavated peat does not lose either its

structure or moisture content. Peat turves require particularly careful storage and wetting and to be

maintained to prevent drying out and subsequent oxidisation to ensure that they remain fit for re-use.

70 Stockpiling of peat will be in large volumes, taking due regard to potential loading effects. Piles will be

bladed off at the side to minimise the available drying surface area. Higher stockpiles are more likely

to become dewatered, while smaller piles expose a greater area to evaporation. Reducing mound size

may also increase likelihood of erosional losses as Particulate Organic Carbon (POC). Overall

volumes of stockpiling will be minimised and height and surface areas kept to a minimum.

71 When planning the temporary storage areas any additional disturbance areas will be minimised.

72 Transport of peat to temporary storage areas, restoration areas or designated spoil areas will be by

low ground pressure vehicles to avoid excessive compaction of the peat.

5.3 Bare Peat

73 A core aim will be to minimise the time any bare peat is exposed. The phasing of work will be carried

out so as to minimise the amount of total exposed ground at any one time. By stripping turf and

replacing as soon as possible after peat has been re-distributed there will be minimal areas of bare

peat.

74 Any peat areas that remain partially bare will be covered using geotextile or a similar method to stop

erosion. Any areas of bare peat, where vegetation is not re-growing, will be seeded with a seed

mixture obtained from the existing habitat. Areas where full recovery is complete will have fences

removed.

75 This approach has been shown to work on other peat sites and the turves re-grow quickly both

establishing vegetation and consolidating the peat. The re-vegetated areas will be monitored. Any

areas of bare peat, where vegetation is not re-growing, will be seeded with a seed mixture obtained

from the existing habitats on site.

5.4 Infrastructure Reuse

76 The Principal Contractor will be required to provide appropriate plant for undertaking all reinstatement

works such that no unnecessary disturbance of the ground surface occurs. In order to minimise

disturbance and damage to the ground surface, any mobile plant required for reinstatement and

landscaping works will be positioned on constructed access tracks, hardstanding areas or existing

disturbed areas wherever possible. The use of a long reach excavator for excavations and

reinstatement works is preferable as it enables sufficient room to allow initial side casting and

subsequent pulling back of turves over reinstated peat or soil.

77 Excavated catotelmic peat will only be used in restoration works where the topography allows straight

forward deposition with no pre-treatment or containment measures and without risk to the

environment. Suitable scenarios may be present in those disturbed areas where the natural or the

receiving topography profile allows such use (for example in turbine foundation excavations).

78 Reinstatement of vegetation will be focused on natural regeneration utilising peat vegetated turves. To

encourage stabilisation and early establishment of vegetation cover, where available, peat turves or

other topsoil and vegetation turves in keeping with the surrounding vegetation type will be used to

provide a dressing for the final surface.


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79 Consideration will also be given to the impacts of poor drainage control in any areas where peat is

used in reinstatement, for instance, track verges and reinstatement of construction compounds.

80 Any reinstatement and re-profiling proposals will consider, and mitigate against, identified significant

risks to environmental receptors. In particular, in areas of replaced peat, water management will be

considered in the Principal Contractor’s Construction Method Statements to ensure that as far as

possible an appropriate hydrological regime is re-established within areas of disturbance. Particular

attention will be paid to maintaining hydrological continuity and preventing the creation of preferential

subsurface flow paths (for instance within backfilled cable trenches).

81 Any surplus peat will spread in areas identified by the geotechnical clerk of works in conjunction with

the ecological clerk of works as suitable.

5.4.1 Cut and Fill Access Tracks

82 When constructing tracks rapid restoration of track verges will be undertaken as track construction

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

allow quicker re-vegetation and soften visual landscaping of the road edges

83 The majority of the site’s access tracks will be constructed using a cut and fill methodology. Excavated

peat from cut and fill sections of access tracks will be used for dressing the side slopes of track

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

84 Track edges and passing places would be reinstated post construction through the removal of capping

material and the reuse of peat turves. Where peat turves are used to reinstate track edges this will be

done in a manner to ensure works tie in with the surrounding topography, landscape and ground

conditions. Where gradients permit, peat edges may be built up slightly above the road level to reduce

visual effects from the surrounding area if it is necessary to limit track visibility.

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

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

water, so natural drainage can be maintained as much as possible. This will be achieved by using

suitably graded stone in track base construction so as to permit flow through the track. The design of

the semi-permeable tracks will try and mimic the natural permeability of the peat so that the tracks

themselves do not become rapid flow paths from one side of the track to the other.

5.4.2 Floating Access Tracks

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

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

transmittance of water resulting in the ponding of water up gradient of tracks and derogation of water

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

pipes/cross-drains constructed at regular points through the track. As for the cut and fill track drainage,

the design of the track drainage will mimic natural peat permeability so as not to create rapid flow

paths and exacerbate peat erosion.

5.4.3 Turbine Foundations and Hardstanding

87 Peat will be replaced around the turbine base excavations, and re-turfed. Peat will be spread over the

areas disturbed by construction activities, around the crane hardstandings, rotor assembly

hardstandings and other areas used in the construction phase.

88 The re-vegetation of temporary hardstanding areas will depend on the identified reinstatement use

and associated vegetation character bounding the areas of restoration, with the aim being to match

turves and topsoil to similar ground conditions. Where appropriate, excess peat turves could be used

for screening bunds, landscaping or as part of the Outline Habitat Management Plan (see Chapter 8)

in conjunction with reseeding. The seed mix used on site would be agreed with the ECoW, Natural

England and local authorities and would use local native species akin to the local ecological baseline.

89 It is envisaged that the majority of the excavated peat materials will be reused for the purpose of

borrow pit restoration, which will be restored to create bog habitats. The final size of the borrow pits


V1 17

have yet to be confirmed and are provisional estimates based on the aggregate requirement for the

scheme.

5.4.4 Borrow Pits

90 Borrow pit reinstatement using excavated peat will depend on the final restoration profiles of the

borrow pit areas and will be subject to the ground conditions close to borrow pits (to be confirmed in

the final PMP).

91 The borrow pit design will allow for unconsolidated peat to be used at depths of up to 1m for

restoration purposes.

92 The Contractors Method Statement will provide information on intended final restoration profiles and

method statement for how this is to be achieved, the likely volumes of material required in addition to

peat, where the material is to be sourced and hydrology design to create and maintain peat wetland

status.

93 Borrow pit design will take account of medium and long term restoration objectives relating to habitat

and environment. In particular they will be designed such that water levels within the restored habitat

can be maintained at ground level, to allow water-logged conditions to be maintained. This can be

achieved by excavating the borrow pits downslope where possible, allowing the downslope worked

face to retain high water levels within the restored area thus preventing peat drying out.

94 Catotelmic peat will be reused within the borrow pits to create the desired profile and this will be

surfaced with acrotelmic material (turves) where available or reseeded to the local environment and

habitats. This approach encourages rapid vegetation regeneration, preventing desiccation and carbon

losses from the peat used in the restoration.

95 The final design will also take into consideration the stability of the emplaced peat materials and

include any additional measures i.e. stabilistation, required to ensure there are no residual risks to the

environment or human health resulting from peat slides.

5.5 Reuse of Peat for Other Restoration Purposes

96 Rooley Moor forms part of a Drinking Water Protected Area (DWPA) under Article 7 of the Water

Framework Directive. The most relevant objective (to this project) for DWPA is to ensure necessary

protection in the DWPA with the aim of avoiding deterioration in water quality in order to reduce the

level of purification treatment required in producing drinking water. As a result of this UU are seeking

match funding through a LIFE fund bid, in order to seek money to undertake remedial and

enhancement works on Rooley Moor and the adjacent moors, Scout Moor and Knowl Moor.

97 Due to this proposal being put forward, working with United Utilities and providing funding to form part

of the match funding for the LIFE bid will be the preferred option as a holistic approach, uniformly

undertaken across all of the contiguous moorlands (which are predominantly common lands); is

undoubtedly the most sound approach to take. However, in the event that LIFE funding is not realised,

the basis of an Outline Habitat Management Plan (OHMP) is presented in Chapter 8: Non-Avian

Ecology which will be implemented within the Development Area. A summary of the parts of the plan

which involve the re-use of peat in restoration works on Rooley Moor is presented below.

98 The formation of peatland is reliant on a high water table, whether temporary or permanent. The

existing erosion features identified to the north of Ding Quarry will promote dewatering of upgradient

peat. In order to allow peat bog restoration, the lowering of the water table by the erosion gullies must

be significantly reduced. It is assumed that the water table can be restored in the gully areas via

blocking using peat, supported by dam structures.

99 A detailed gully blocking and reinstatement method statement will be agreed with Natural England and

UU prior to the commencement of construction. The details will be contained within the CEMP. The

most appropriate methods would be used, chosen on a site by site basis as described in the OHMP.

As described in the OHMP, the gullies will be blocked, often with blocks of intact peat, at regular

intervals along their length. This allows water tables to rise and the surface to be more water-logged

slowing down decomposition of organic matter and creating the wet conditions for Sphagnum

regeneration.


V1 18

100 There are however a number of considerations that must be taken into account when selecting the

dam material which include slope, drain size and exposure of mineral substrate. It is proposed to use

peat turves and fibrous material for ditch blocking. Peat turves will be placed over the top of dams to

promote regrowth of vegetation. No amorphous catotelm will be used for ditch blocking. Some

catotelm could be used in deeper furrows close to dam areas where will not be unsupported.

101 Estimates for peat volume re-use in gully blocking have not be included within the peat balance, the

anticipated volume of peat re-use in these features is likely to be circa 500m3, based on experience of

similar schemes.


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References

1. The Kyoto Protocol (1997)

2. Kyoto Protocol and National Accounting for Peatlands (2012);

3. The UK Climate Change Act (2008);

4. Carbon Landscapes and Drainage, 2012 ‘The Carbon and Water Guidelines’, www.clad.ac.uk;

5. Forestry Commission, 2011, ‘Forests and climate change: UK Forestry Standard Guidelines;

6. Scottish Environment Protection Agency (SEPA), Regulatory Position Statement – Developments on

Peat (2010);

7. Scottish Government, Guidance on Developments on Peatland – Site Surveys (2011);

8. Floating Roads on Peat, Scottish Natural Heritage (2010);

9. Guidance on the Assessment of Peat Volumes, Reuse of Excavated Peat and the Minimisation of

Waste, Scottish Renewables and SEPA

10. Investigating the impacts of windfarm development on peatlands in England: Part 1 Final Report.

Natural England Commissioned Report NECRO32.

11. Best Practice Guidance to Planning Policy Statement 18 ‘Renewable Energy’, August 2009;

12. Wind Farm Developments on Peat Land fact sheet. Scottish Government (June 2011)

13. Good practice during windfarm construction, A joint publication by Scottish Renewables, Scottish

Natural Heritage, Scottish Environment Protection Agency, Forestry Commission Scotland, Version 1,

October 2010.

14. JNCC Report 445 (2011) Towards an Assessment of the state of UK Peatlands. Available online at

http://jncc.defra.gov.uk/pdf/jncc445_web.pdf Last accessed 25th June 2014.

15. Clymo RS (1992). Models of Peat Growth. Suo, 43 (4-5) 127-136.

16. FEH (Flood Estimation Handbook) CD-ROM 3 produced by the CEH (Centre for Ecology and

Hydrology, 2009)

17. National Vegetation Classification: field guide to mires and heaths. Joint Nature Conservation

Committee (2010). Available online at http://jncc.defra.gov.uk/pdf/mires_heaths.pdf Last accessed

18/06/14.

http://jncc.defra.gov.uk/pdf/jncc445_web.pdfhttp://jncc.defra.gov.uk/pdf/mires_heaths.pdf


V1

Appendix 1. Peat Characteristics Data

Outline Peat Management Plan Peat Investigation Data

Core numberCore Depth (m)

Depth of peat with auger (m)

Peat depthAcrotelm

depthCatatelm

depthDry soil bulk

density

Organic Carbon Content

Acrotelm Catotelm Acrotelm CatotelmWell depth

(m)Water level after

1hr (m bgl)Water level

02/05/14 (m bgl)

m m m g/cm3 % H score H score B score B score m m mC0 0.10 0 0 0 0 - - - -C1 0.40 0 0 0 0 - - - -C2 0.10 0 0 0 0 - - - -C3 0.15 0 0 0 0 - - - -C4 0.20 0.2 0.2 0.05 0.15 6 10 2 2C5 0.40 0.4 0.4 0.05 0.35 6 9 2 3C6 0.70 0.7 0.7 0.15 0.55 0.28 52 5 9 3 3 0.5 0.1 0.05C7 0.35 0.35 0.35 0 0.35 - - - -C8 0.50 0.4 0.4 0 0.4 - - - - 0.52 Dry 0.76C9 0.45 0.3 0.3 0 0.3 - 9 - -C10 0.50 0.5 0.5 0.15 0.35 7 10 2 2 0.64 0.23 0.23C11 0.90 0.9 0.9 0.1 0.8 6 9 2 4 0.91 Dry 0.3C12 0.40 0.2 0.2 0.05 0.15 7 10 2 2C13 2.00 2 2 0.2 1.8 7 7 2 3C14 0.40 0.4 0.4 0.1 0.3 5 9 4 2C15 0.40 0.25 0.25 0.1 0.15 5 9 3 2C16 0.50 0.4 0.4 0.1 0.3 7 10 3 4 0.46 Dry 0.08C17 0.40 0.4 0.4 0.05 0.35 5 8 3 3C18 1.80 1.8 1.8 0.2 1.6 0.32 64 6 7 2 3 1.07 0.8 0.05C19 0.55 0.15 0.15 0.05 0.1 7 10 2 2 0.9 0.53 0.5C20 0.30 0.2 0.2 0.07 0.13 4 6 2 3C21 0.30 0.3 0.3 0.02 0.28 6 10 3 2C22 0.90 0.9 0.9 0 0.9 - 9 - 2 0.77 Dry 0.28C23 0.20 0.15 0.15 0.03 0.12 4 10 3 2C24 0.10 0.08 0.08 0.03 0.05 6 10 2 2C25 0.25 0.25 0.25 0.05 0.2 6 10 4 2C26 1.10 1.1 1.1 0.05 1.05 5 8 4 3 0.46 Dry 0C27 0.60 0.6 0.6 0.1 0.5 5 8 3 2 0.76 Dry 0C28 1.00 0.8 0.8 0.1 0.7 0.2 57 6 8 2 3 1.04 Dry 0.35C29 0.70 0.5 0.5 0.05 0.45 6 10 2 2 0.86 Dry 0.8C30 0.45 0.45 0.45 0.1 0.35 6 9 3 2C31 0.60 0.6 0.6 0.15 0.45 6 10 2 2 0.44 Dry 0.3C32 0.20 0.2 0.2 0.1 0.1 6 9 2 2C33 0.45 0.45 0.45 0.1 0.35 5 10 2 3C34 0.25 0.15 0.15 0.05 0.1 5 8 3 4C35 0.45 0.35 0.35 0.2 0.15 6 8 2 4C36 0.25 0.2 0.2 0.05 0.15 7 10 2 2

Von Post H scores Von Post B scores Dipwell measurementsPeat depths and characteristics

Page 1 of 2

Outline Peat Management Plan Peat Investigation Data

Core numberCore Depth (m)

Depth of peat with auger (m)

Peat depthAcrotelm

depthCatatelm

depthDry soil bulk

density

Organic Carbon Content

Acrotelm Catotelm Acrotelm CatotelmWell depth

(m)Water level after

1hr (m bgl)Water level

02/05/14 (m bgl)

m m m g/cm3 % H score H score B score B score m m m

Von Post H scores Von Post B scores Dipwell measurementsPeat depths and characteristics

C37 0.50 0.3 0.3 0.05 0.25 7 9 2 2C38 0.85 0.85 0.85 0.25 0.6 0.38 50 5 9 2 3 0.62 Dry 0.45C39 0.35 0.2 0.2 0.1 0.1 4 9 4 2C40 0.45 0.4 0.4 0.1 0.3 5 9 3 2C41 0.40 0.4 0.4 0.1 0.3 6 9 3 2C42 0.30 0.3 0.3 0.05 0.25 5 8 3 2C43 0.13 0.1 0.1 0.03 0.07 4 10 4 2C44 0.45 0.4 0.4 0.02 0.38 6 8 2 2C45 0.90 0.9 0.9 0.15 0.75 0.24 66 7 10 2 3 0.69 Dry 0.7625C46 0.20 0.2 0.2 0.05 0.15 5 9 4 3C47 0.35 0.35 0.35 0.05 0.3 5 10 4 2C48 0.15 0.1 0.1 0 0.1 - 10 - 2C49 0.25 0.25 0.25 0.05 0.2 0.38 46 7 10 3 2C50 0.15 0.1 0.1 0 0.1 - 10 - 2C51 1.00 1 1 0.15 0.85 0.15 63 6 9 4 3 0.9 0.82 0.05C52 0.35 0.35 0.35 0.05 0.3 7 10 2 2C53 0.35 0.35 0.35 0.05 0.3 7 10 3 2C54 0.25 0.1 0.1 0.02 0.08 4 9 4 4C55 0.30 0.3 0.3 0.05 0.25 7 10 2 2C56 0.65 0.65 0.65 0.02 0.63 0.33 56 8 10 3 3 1.57 1.15 0.05C57 0.85 0.85 0.85 0.1 0.75 7 9 4 3 0.66 Dry 0C58 0.95 0.95 0.95 0.02 0.93 0.18 56 5 8 3 2 0.75 0.72 0C59 0.65 0.65 0.65 0.05 0.6 7 9 3 3C60 0.35 0.35 0.35 0.1 0.25 8 9 3 2C61 1.05 1.05 1.05 0.1 0.95 0.44 54 7 9 2 2C62 1.00 1 1 0.15 0.85 6 9 3 3 0.73 Dry 0C63 1.00 1 1 0.1 0.9 7 10 2 2

Average 0.52 0.47 0.47 0.07 0.40 0.29 56.40 5.93 9.14 2.72 2.47 0.76 0.62 0.25 STDEV 0.37 0.40 0.40 0.06 0.36 0.10 6.40 1.04 0.93 0.76 0.66 0.27 0.36 0.28 COUNT 64 64 64 64 64 10 10 54 58 54 57 20 7 20

Page 2 of 2


V1

Appendix 2. Peat Calculations

Von Post Humification and Moisture Scale for Peat Classification

H1Completely undecomposed peat which, when squeezed, releases almost clear water. Plant remains easily identifiable. No amorphous material present.

H2Almost entirely undecomposed peat which, when squeezed, releases clear or yellowish water. Plant remains still easily identifiable. No amorphous material present.

H3Very slightly decomposed peat which, when squeezed, releases muddy brown water, but from which no peat passes between the fingers. Plant remains still identifiable, and no amorphous material present.

H4Slightly decomposed peat which, when squeezed, releases very muddy dark water. No peat is passed between the fingers but the plant remains are slightly pasty and have lost some of their identifiable features.

H5Moderately decomposed peat which, when squeezed, releases very “muddy” water with a very small amount of amorphous granular peat escaping between the fingers. The structure of the plant remains is quite indistinct although it is still possible to recognize certain features. The residue is very pasty.

H6 Moderately highly decomposed peat with a very indistict plant structure. When squeezed, about one-third of the peat escapes between the fingers. The residue is very pasty but shows the plant structure more distinctly than before squeezing.

H7 Highly decomposed peat. Contains a lot of amorphous material with very faintly recognizable plant structure. When squeezed, about one-half of the peat escapes between the fingers. The water, if any is released, is very dark and almost pasty.

H8Very highly decomposed peat with a large quantity of amorphous material and very indistinct plant structure. When squeezed, about two-thirds of the peat escapes between the fingers. A small quantity of pasty water may be released. The plant material remaining in the hand consists of residues such as roots and fibres that resist decomposition.

H9Practically fully decomposed peat in which there is hardly any recognizable plant structure. When squeezed it is a fairly uniform paste.

H10 Completely decomposed peat with no discernible plant structure. When squeezed, all the wet peat escapes between the fingers.

B1 Dry peatB2 Low moistureB3 Moderate moisture contentB4 High moisture contentB5 Very high moisture content

Von Post Humidification scale

Von Post moisture scale

Documents

Appendix 7.2: Outline Peat Management Plan · 2014. 9. 5. · Outline Peat Management Plan V1 2 Investigating the impacts of wind farm development on peatlands in England: Part 1