NORTHAMPTON NORTH-WEST RELIEF ROAD · 1.3 scope of report 2 1.4 biodiversity net gain policy 2 2...

BNG MAY 2019 CONFIDENTIAL

Northampton County Council

NORTHAMPTON NORTH-WEST

RELIEF ROAD

Biodiversity Net Gain Assessment

Northampton County Council

NORTHAMPTON NORTH-WEST RELIEF ROAD

Biodiversity Net Gain Assessment

CONFIDENTIAL

TECHNICAL APPENDIX (V1) CONFIDENTIAL

PROJECT NO. 70045931

OUR REF. NO. BNG

DATE: MAY 2019

WSP

Kings Orchard

1 Queen Street

Bristol

BS2 0HQ

Phone: +44 117 930 6200

WSP.com

NORTHAMPTON NORTH-WEST RELIEF ROAD CONFIDENTIAL | WSP Project No.: 70045931 | Our Ref No.: BNG MAY 2019 Northampton County Council

QUALITY CONTROL

Issue/revision First issue Revision 1 Revision 2 Revision 3

Remarks First Issue

Date 30/05/2019

Prepared by Laura Homfray

Signature

Checked by Sarah Scott

Signature

Authorised by Jenny Merriman

Signature

Project number 70045931

Report number BNG

File reference

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CONTENTS

1 INTRODUCTION 1

1.1 BIODIVERSITY NET GAIN 1

1.2 PROJECT BACKGROUND 1

1.3 SCOPE OF REPORT 2

1.4 BIODIVERSITY NET GAIN POLICY 2

2 METHODOLOGY 4

2.1 OVERVIEW 4

2.2 BASELINE BIODIVERSITY UNIT CALCULATION 5

2.3 POST-DEVELOPMENT BIODIVERSITY UNIT CALCULATION 7

2.4 TEMPORAL RISK 9

2.5 CALCULATING THE CHANGE IN BIODIVERSITY UNITS AS A CONSEQUENCE OF THE

PROPOSED SCHEME 10

3 ASSUMPTIONS AND LIMITATIONS 12

3.1 BASELINE BIODIVERSITY AND LINEAR UNIT CALCULATION 12

3.2 POST-DEVELOPMENT BIODIVERSITY AND LINEAR UNIT CALCULATION 12

3.3 LIMITATIONS 13

4 RESULTS OF BASELINE BIODIVERSITY AND LINEAR UNIT

CALCULATIONS 14

4.1 OVERVIEW 14

4.2 AREA-BASED HABITATS 14

4.3 IRREPLACEABLE HABITATS 15

4.4 LINEAR HABITATS 16

5 RESULTS OF THE POST DEVELOPMENT BIODIVERSITY AND LINEAR

UNIT CALCULATIONS 17


6 SUMMARY OF RESULTS AND RECOMMENDATIONS 22

6.1 SUMMARY OF RESULTS 22

6.2 RECOMMENDATIONS 22

7 REFERENCES 24

TABLES

Table 2-1 – Habitat distinctiveness bands and scores 6

Table 2-2 – Habitat condition bands and scores 7

Table 2-3 – Defra spatial risk factor 8

Table 2-4 - Defra delivery risk factors 9

Table 2-5 – Delivery risk of created habitats 9

Table 2-6 - Temporal risk factors 10

Table 2-7 - Temporal risk for created habitats 10

Table 4-1 - Baseline BU of the Proposed Scheme: habitat lost 14

Table 4-2 - Baseline BU of the Proposed Scheme: habitat retained 15

Table 4-3 – Baseline hedgerow LU lost 16

Table 4-4 – Baseline hedgerow LU retained 16

Table 4-5 – Baseline watercourse LU lost 16

Table 4-6 – Baseline watercourse LU retained 16

Table 5-1 – Post-development – retained habitats 17

Table 5-2 – Post-development – created habitats 18

Table 5-3 – BU results summary 19

Table 5-4 – Hedgerow LU created post-development 19

Table 5-5 –Hedgerow LU retained from baseline 19

Table 5-6 – Hedgerow LU results summary 20

Table 5-7 – Watercourse LU created post-development 20

Table 5-8 –Watercourse LU retained from baseline 20

Table 5-9 – Watercourse LU results summary 21


Table 6-1 – Summary of results 22

APPENDICES

CIEEM, CIRIA AND IEMA UK BIODIVERSITY NET GAIN GOOD PRACTICE

PRINCIPLES FOR DEVELOPMENT

WSP BIODIVERSITY NET GAIN PROCESS

PHASE 1 MAPS:BASELINE AND POST-DEVELOPMENT


EXECUTIVE SUMMARY

Biodiversity Net Gain (BNG) is a quantitative, stepwise process which is applied to development and

results in an overall net gain in biodiversity after development. The principle behind it is that any

impacts from development to biodiversity need to be accounted for and compensated with equivalent

and additional gains. Applying the biodiversity net gain process to a development project provides

clear, quantifiable outcomes for biodiversity which are backed up by a robust evidence base.

WSP UK Ltd (‘WSP’) was commissioned in April 2018 to carry out ecology surveys, in support of the

planning application for a proposed relief road to the north-west of the town of Northampton, known

as the Northampton North-West Relief Road (NNWRR). This will involve the construction of a new

single carriageway that will connect the A5199 Welford Road to a proposed junction adjacent to

Dallington Grange Farm, hereafter referred to as the ‘Proposed Scheme’.

The Proposed Scheme has adopted the Defra metric to calculate baseline and preliminary post-

development biodiversity units (BU) and linear units (LU), to quantify biodiversity lost to the Proposed

Scheme and to provide an indication of the biodiversity which will be replaced through onsite

compensation. This information will be used to indicate whether the Proposed Scheme is likely to

meet no net loss or net gain for biodiversity.

This report aims to:

Establish the total number of baseline BU and LU at the Site of the Proposed Scheme;

Establish the total number of BU and LU which will be created, retained and/or enhanced under

landscape and ecological mitigation proposals at the Site of the Proposed Scheme; and

Determine whether the Proposed Scheme will result in a net loss, no net loss or a net gain for

biodiversity.

Results

The Proposed Scheme design will result in a net gain for biodiversity for area-based habitats (an

increase of 31.78 BU which equates to 34% net gain), a net loss for linear hedgerow habitats (a

decrease of 1337 LU which equates to a 46% net loss) and a net gain of linear watercourse habitats

(an increase of 1838m which equates to a 353% net gain). The results of the BNG assessment are

summarised in the table below.

Although there is a significant biodiversity net gain of BU and watercourse LU, the Proposed

Scheme cannot claim that it will deliver a net gain in biodiversity within the site boundary due

to the loss of Hedgerow LU.


Area

(Hectares) BU

Hedgerow Length (m)

Hedgerow LU

Length (m) or Watercourse

LU

TOTAL AREA-BASED HABITAT OR LINEAR

FEATURE AT BASELINE

41.10 93.82 1060 2900 520


FEATURE POST-DEVELOPMENT

41.16 125.60 1543 1563 2358

OUTCOME NET GAIN OF 34%

(+31.78 BU)

NET GAIN OF 46% (+483m)

NET LOSS OF 46%

(1337 LU)


Although there is a net increase in length of hedgerows of approximately 483m, there is an overall

loss of 1337 LU. Using the current metric it is difficult to deliver significant gains for even relatively

limited loss of linear units, without providing considerably more habitat (by length) than is lost. This is

because the current hedgerow metric does not have any weighting for habitat condition when hedges

are created post-development and the condition assessment for hedgerows does not account for

different levels of species richness. The metric for linear units is currently under review by Natural

England.

Due to the limitations of the current metric, enhancements of linear habitats that have been proposed

as part of the Proposed Scheme are not captured. Biodiversity enhancement of hedgerows as part of

the Proposed Scheme include increasing the species-richness of existing hedgerows and providing

species-rich hedgerow to replace species-poor hedgerow.

It is important to recognise that the quantification of biodiversity units is one of a number of factors to

be considered when assessing the impact of each stage on biodiversity.

WSP recommends the following next steps for the BNG assessment of NNWRR:

The BNG assessment is re-run once the temporary works layout information is available to ensure

that any impacts resulting from the construction of the Proposed Scheme are captured and

quantified.

The BNG assessment is re-run based on the final landscape plan for the Proposed Scheme.

To avoid re-running the BNG calculations multiple times, the calculations should be re-run once

when the final landscape plan and temporary works layout information is available.

The client should continue to explore any other options to avoid impacts to and create more

hedgerow habitats.

Contact name Laura Homfray

Contact details +44 1179 306195 | [email protected]

NORTHAMPTON NORTH-WEST RELIEF ROAD CONFIDENTIAL | WSP Project No.: 70045931 | Our Ref No.: BNG MAY 2019 Northampton County Council Page 1 of 25

1 INTRODUCTION

1.1 BIODIVERSITY NET GAIN

1.1.1 Biodiversity net gain (BNG) is the end result of a process applied to infrastructure development so

that overall, there is a positive outcome for biodiversity. The process itself follows the mitigation

hierarchy, which sets out that everything possible must be done to first avoid and then minimise and

restore / rehabilitate losses of biodiversity on site. Only as a last resort, residual losses are

compensated for using biodiversity offsets, which are distinguished from other forms of mitigation in

that they are off the development site and require measurable conservation outcomes.

1.1.2 Adopting a BNG approach can account for biodiversity losses not fully covered by legal and planning

systems. Whilst some species are extensively protected, many are not; with the consequence that

development can be ‘legally compliant’ but still result in biodiversity loss. The BNG approach guards

against this, enabling development to contribute towards the national and global target of halting

biodiversity loss by 2020 and towards local and national strategies for conserving and enhancing

wildlife.

1.1.3 For BNG to be used appropriately and to generate long-term gains for nature, the good practice

principles established by the Business and Biodiversity Offset Programme (BBOP) can be used.

These principles have been established in the context of UK development by the Construction Industry

Research and Information Association (CIRIA), the Chartered Institute for Ecology and Environmental

Management (CIEEM) and the Institute of Environmental Management and Assessment (IEMA) (see

Appendix A). The BNG process for the Northampton North-West Relief Road (NNWRR) assessment

adheres to these principles.

1.2 PROJECT BACKGROUND

1.2.1 WSP UK Ltd (‘WSP’) was commissioned in April 2018 to carry out ecology surveys, in support of the

planning application for a proposed relief road to the north-west of the town of Northampton, known

as the Northampton North-West Relief Road (NNWRR). This will involve the construction of a new

single carriageway that will connect the A5199 Welford Road to a proposed junction adjacent to

Dallington Grange Farm, hereafter referred to as the ‘Proposed Scheme’.

1.2.2 The Proposed Scheme comprises an approximately 1.6km single two-lane carriageway (Route Option

‘11’) connecting two proposed junctions, the Dallington Grange Roundabout (in the south) and the

Sandy Lane Roundabout (in the north). Furthermore, the development will include the construction of

a new bridge crossing the River Nene that will connect the Sandy Lane Roundabout to a third

proposed junction, the Brampton Lane Roundabout.

1.2.3 The Proposed Scheme will also encompass approximately 30ha of surrounding land required to

facilitate construction and is hereafter referred to as the ‘Site’. This area will include construction work

areas, borrow pits, and flood mitigation, as well a shared cycle/footway along the west of the proposed

road and flood and drainage provisions.

1.2.4 It is understood the planning application for the Proposed Development will be submitted in June 2019.

1.2.5 The Proposed Scheme has adopted the Defra metric 2012 to undertake baseline and preliminary

post-development biodiversity unit (BU) and linear unit (LU) calculations to quantify the biodiversity

which will be lost to the Proposed Scheme and provide an indication of the biodiversity which will be


replaced through onsite compensation once the Proposed Scheme has been built. This information

will be used to indicate whether the Proposed Scheme is likely to meet no net loss or net gain for

biodiversity.

1.2.6 The Defra metric will be used to assess the biodiversity impacts and opportunities of the Proposed

Scheme. This assessment will inform avoidance, mitigation and compensation measures designed to

mitigate for habitat loss due to the Proposed Scheme. This includes informing habitat restoration and

reinstatement proposals as well as new habitat creation. The Defra metric is also required to evaluate

progress towards achievement of the target of net gain or no net loss. This information will provide a

quantitative benchmark to inform the size and type of habitat compensation requirements as a result

of habitat lost to the Proposed Scheme

1.3 SCOPE OF REPORT

1.3.1 This report aims to:

Establish the total number of baseline BU and LU at the Site of the Proposed Scheme;

Establish the total number of BU and LU which will be created, retained and/or enhanced under

landscape and ecological mitigation proposals at the Site of the Proposed Scheme; and

Determine whether the Proposed Scheme will result in a net loss, no net loss or a net gain for

biodiversity.

1.3.2 Please note that the BNG report does not cover requirements of the Proposed Scheme arising from

potential impacts on protected species and designated sites. This information will be covered within

the ecology chapter of the Environmental Statement (ES) for the Proposed Scheme.

1.4 BIODIVERSITY NET GAIN POLICY

1.4.1 The appraisal has been compiled with reference to the following relevant nature conservation

legislation, planning policy and the UK Biodiversity Framework from which the protection of sites,

habitats and species is derived in England.

The Natural Environment and Rural Communities (NERC) Act 2006;

The UK Post-2010 Biodiversity Framework (2011-2020) (JNCC and DEFRA, 2012);

Biodiversity 2020: A strategy for England’s wildlife and ecosystem services (DEFRA, 2011);

UK Biodiversity Action Plan (UKBAP)1;

The National Planning Policy Framework (NPPF) 2019 (DCLG, 2012);

NATIONAL PLANNING POLICY FRAMEWORK

1.4.2 Although not currently a legal obligation, the revised National Planning Policy Framework (NPPF)

(2019) refers to biodiversity and environmental net gains in the following paragraphs:

Transport Infrastructure

1 The UK BAP has now been replaced by the UK Post-2010 Biodiversity Framework, however, it contains useful

information on how to characterise important species assemblages and habitats which is still relevant.


• Paragraph 102. “Transport issues should be considered from the earliest stages of plan-making

and development proposals, so that:

d) the environmental impacts of traffic and transport infrastructure can be identified assessed

and taken into account – including appropriate opportunities for avoiding and mitigating any

adverse effects, and for net environmental gains.”

Planning decisions

• Paragraph 118 “Planning decisions and planning policy should a) encourage multiple benefits

from both urban and rural land … and taking opportunities to achieve net environmental gains

- such as developments that would enable new habitat creation.”

• Paragraph 170 “Planning policies and decisions should contribute to and enhance the natural

and local environment by: … d) minimising impacts on and providing net gains for biodiversity”

• Paragraph 174 “To protect and enhance biodiversity and geodiversity plans should b) ... identify

and pursue opportunities for securing measurable net gains for biodiversity.”

• Paragraph 175 “When determining planning applications, local planning authorities should apply

the following principles: d) … opportunities to incorporate biodiversity improvements in and

around developments, especially where this can secure measurable net gains for

biodiversity.”

LOCAL POLICY

1.4.3 Northamptonshire County Council has the following target within the Northamptonshire Biodiversity

Action plan (BAP) 2015-2020 (p38) “Ensure that all relevant new developments lead to a net gain in

biodiversity through on or off site mitigation with consideration of BAP targets”.

1.4.4 The Northamptonshire BAP 2015-2020 states that “The BAP should guide the planning decision

process to ensure priority habitats and species are conserved, and that development leads to a net

gain in biodiversity in accordance with the National Planning Policy Framework”.


2 METHODOLOGY

2.1 OVERVIEW

2.1.1 The method applied followed the six steps of WSP’s BNG process (see Appendix B for the full six step

process). The work set out in this report is covered by step two. The relevant sections of step two are

provided below:

STEP 2 INITIAL BIODIVERSITY ASSESSMENT

i. Survey baseline habitats and their condition. Ideally, a habitat condition assessment is

undertaken during Phase 1 Habitat survey. If Phase 1 Habitat data has been collected prior to

initiating the BNG process, condition assessment can be undertaken either:

a. Retrospectively through interpretation of Phase 1 target notes, consultation with

surveyors, or employing a number of assumptions; or

b. During an additional site visit.

ii. Identify irreplaceable habitat. Following Defra guidance, irreplaceable habitats within the

Proposed Scheme boundary must be identified and excluded from the biodiversity unit

calculations.

iii. Calculate baseline biodiversity units using the biodiversity metric. This calculation

includes all habitats (minus irreplaceable habitats) within the Proposed Scheme boundary prior

to development and is informed by Phase 1 Habitat data and results of the condition

assessment. The baseline biodiversity unit calculation may be run on a number of scheme

options if the scheme is at options appraisal stage.

iv. Calculate post-development biodiversity units using the biodiversity metric. This

calculation accounts for all of the proposed habitats (including retained habitats and habitats

lost or created as a result of the development) within the Proposed Scheme boundary post-

development. The calculation excludes irreplaceable habitats. The calculation is informed by

scheme design, landscape plans, and proposed ecological mitigation. The assessment is

based upon the target state (type, size and condition) of habitats being created.

v. Produce an ‘Initial Biodiversity Assessment’ report. The report sets out the BNG process

in the context of the Proposed Scheme and includes the method and results of initial baseline

and post-development biodiversity unit calculations.

IRREPLACEABLE HABITATS

2.1.2 Following Defra guidance, irreplaceable habitats have been excluded from this biodiversity unit

calculation. It is important to note that BNG or no net loss cannot be achieved for the scheme as a

whole if there is a negative impact on an irreplaceable habitat.

LINEAR HABITATS


2.1.3 Defra recognise that hedgerows are a very important feature in terms of biodiversity value: ‘‘Their

contribution, by area, to biodiversity in the landscape is far greater than even the most biodiversity

rich habitats’’ (Defra, 2012a). Hedgerows and watercourses therefore cannot be treated as other area-

based habitats and are considered in terms of LU rather than BU; both are arbitrary units which are

not directly comparable with each other.

2.2 BASELINE BIODIVERSITY UNIT CALCULATION

EXTENT AND SOURCES OF BASELINE HABITAT DATA

2.2.1 Identification of baseline habitats was based on a digitised Phase 1 Habitat layer (WSP, 2019). The

BNG calculation covered all habitats (linear and non-linear) within the Scheme footprint (for a map of

the Proposed Scheme extent and Phase 1 Habitat survey data please see Appendix C of this report).

The following Phase 1 Habitat typologies present within the Scheme footprint which, in the context of

BNG, are not considered ‘habitats’ were excluded:

→ Fence; and

→ Hardstanding/buildings.

2.2.2 Although these habitat typologies do not generate BU, they have been included within the tables

presented in subsequent sections to understand the area in hectares that they occupy relative to the

Proposed Scheme as a whole.

2.2.3 Rivers, streams and dry ditches are included in the BNG assessment as linear features. For the

baseline and post-development biodiversity unit calculation, running water or ditches are expressed

simply as a length in metres.

2.2.4 For area-based habitats, hectares are reported to two decimal places. However, for linear habitats,

length is reported to the nearest metre. The reason for this is that 0.01 of a linear unit is equivalent to

reporting to 1cm. This level of detail is superfluous for the purposes of a preliminary BNG assessment.

2.2.5 The Phase 1 Habitat survey was undertaken following Joint Nature Conservation Committee (JNCC,

2010) survey methodology, and are reported in full within the NNWRR Preliminary Ecological

Assessment report.

DEFRA BIODIVERSITY UNIT CALCULATION

2.2.6 A baseline biodiversity unit calculation was completed for all areas of permanent and temporary land

take within the operational footprint of the Scheme. Habitat area or length, distinctiveness and

condition were used to calculate baseline BU and LU, providing a measure of the biodiversity on site

before development. This calculation is in accordance with Defra’s technical paper, guidance for

developers and guidance for offset providers (Defra 2012 a, b and c). This is the standard metric

used for calculating BU and LU in the UK.

2.2.7 Distinctiveness and condition are given numerical ‘scores’ which are multiplied, together with hectares

(ha) or length in metres (m) of habitat to give the number of baseline BU or LU:

Distinctiveness x Condition x Area (ha) = BASELINE BIODIVERSITY UNITS

Length (m) x Condition = BASELINE LINEAR UNITS


DISTINCTIVENESS

2.2.8 Habitat distinctiveness is defined as a collective measure of biodiversity and includes parameters such

as the number and variety of species found within the habitat (richness and diversity), how rare the

species are, and how many species the habitat supports that are not common elsewhere.

2.2.9 To determine habitat distinctiveness, Phase 1 Habitat types were transposed into the standard habitat

distinctiveness typology and bands issued by Defra (‘the Defra habitat type’). For some habitat types,

multiple distinctiveness bands can apply, depending on the quality of the habitat. Decisions on which

distinctiveness band to assign were based on criteria listed in Appendix C of the Building Research

Establishment’s (BRE) Guidance Note 36: BREEAM, CEEQUAL and HQM Ecology Calculation

Methodology – Route 2.

2.2.10 Appendix C of the BRE Guidance Note 36 spreadsheet contains information which can be used to

match each Phase 1 Habitat type to a Defra habitat type, enabling consistent assessment of

distinctiveness for all habitat parcels

2.2.11 The Defra distinctiveness bands and associated scores are described in Table 2.1.

Table 2-1 – Habitat distinctiveness bands and scores

DISTINCTIVENESS BAND

DISTINCTIVENESS SCORE

HABITAT TYPES INCLUDED

High 6

Habitats of principle importance or habitats which meet the criteria to qualify as habitats of principle importance (JNCC, 2011). This excludes ancient woodland and other habitats

which are irreplaceable.

Medium 4

Other semi-natural habitats that do not fall within the scope of habitats of principle importance definitions, i.e. all other areas

of woodland (e.g. non-native coniferous plantation), other grassland (e.g. species poor semi-improved), uncultivated

field margins, road verge and railway embankments (excluding those that are intensively managed).

Low 2

Improved grassland, arable fields (excluding any uncultivated margins), built up areas, domestic gardens, regularly disturbed

bare ground (e.g. quarry floor, landfill sites etc.), verges associated with transport corridors.

2.2.12 For some habitat types, multiple distinctiveness bands can apply, depending on the quality of the

habitat. Decisions on which distinctiveness band to assign were based on criteria listed in Appendix

C of the BRE Guidance Note 36.

2.2.13 All hedgerows are assumed to be of High distinctiveness because the vast majority of hedgerows will

meet Habitat of Principle Importance (HPI) criteria. For this reason, distinctiveness is not included as

part of the linear unit calculation. This follows the approach set out by Defra.

CONDITION

2.2.14 Condition, in the context of BNG, is defined as the quality of a particular habitat. For example, a

habitat is in poor condition if it fails to support the rare or notable species for which it is valued, or if it

is degraded as a result of pollution, erosion, invasive species or other factors.


2.2.15 The Defra metric requires habitat condition to be assessed using the system presented in Natural

England's Farm Environment Plan (FEP) manual.

2.2.16 Habitat condition scores were assigned based on the criteria in Table 2.2.

Table 2-2 – Habitat condition bands and scores

CONDITION BAND CONDITION SCORE CRITERIA FOR

ASSIGNING CONDITION

Good 3 Any habitat which passes

all the FEP criteria.

Moderate 2 Any habitat which fails

one FEP criterion.

Poor 1 Any habitat which fails

two or more FEP criteria.

2.2.17 As primary habitat condition assessment data was not available, habitat condition was assigned

through interviews with the Phase 1 surveyor who undertook a retrospective condition assessment of

the site.

DERIVING THE TOTAL NUMBER OF BASELINE BIODIVERSITY UNITS

2.2.18 Following the scoring of all habitat parcels for habitat distinctiveness and condition, the total number

of baseline BU will be calculated for each area-based habitat (including those assumed for arable field

margins).

2.2.19 The scores generated by each individual habitat parcel will then be summed to provide the total

number of BU generated by the baseline habitat parcels. It is important to set out the BU for the

individual habitats so that these can be compared with the post-development BU for the same habitat

type.

2.2.20 The number of baseline LU present should be calculated for linear habitats (keeping hedgerows and

watercourses separate).

2.3 POST-DEVELOPMENT BIODIVERSITY UNIT CALCULATION

2.3.1 BU and LU resulting from landscape and ecological mitigation designs for the scheme, including newly

created and retained habitats, are referred to as post-development BU / LU.

LINEAR HABITATS

2.3.2 In the post-development unit calculation, linear habitats have been kept separate from units calculated

for area-based habitats; this mirrors the approach for baseline unit calculations. The risk factors

described below are only applicable to the area-based habitat calculation. They are not included in

the calculation for linear habitats. This is because the risks associated with creating linear features

are considered to be taken into account within the condition multiplier used to calculate the baseline

LU.

2.3.3 The post-development LU from the hedgerows and watercourses created are expressed simply as a

length in metres.


Length (m) = POST-DEVELOPMENT LINEAR UNITS

APPLYING RISK FACTORS TO THE POST-DEVELOPMENT CALCULATION

2.3.4 Post-development BU are calculated in a similar way to baseline BU. However, in addition to area,

condition and distinctiveness of the proposed habitats, the key risks to delivery are taken into account

through incorporation of risk factors. The Defra metric sets out three risk factors: distance from scheme

(spatial risk); time taken for created or enhanced habitats to reach target condition (temporal risk);

and how difficult it is to create or enhance any given habitat (delivery risk).

SPATIAL RISK

2.3.5 The spatial risk is the risk associated with delivering compensation for the loss of a habitat at a

distance from that loss. The further from the site of the loss, the greater the risk. Spatial risk has not

been included in the preliminary post-development calculation as it is assumed that habitat

compensation and retention will be delivered within the Proposed Scheme’s footprint or within the

same ecological network as the loss occurs.

Table 2-3 – Defra spatial risk factor

LOCATION OF HABITAT CREATION OR ENHANCEMENT

RISK FACTOR

Habitat being created or enhanced is within 500m of the area of loss or in the same ecological network identified in a local (county or equivalent) biodiversity, green infrastructure or offsetting strategy.

1

Habitat type being created or enhanced contributes to and is in a location identified within a local (county or equivalent) biodiversity, green infrastructure or offsetting strategy.

0.67

Habitat being created or enhanced is not making a contribution to local (county or equivalent) biodiversity, green infrastructure or offsetting strategy.

0.50

DELIVERY RISK

2.3.6 Delivery risk is the risk associated with the difficulty to create or restore any specific habitat. Appendix

1 of Defra’s Technical Paper (2012a) provides an indicative guide to broad categories of risk for

different habitats. For habitat types not listed in Defra’s guidance, Appendix C of the BRE Guidance

Note 36 was used to determine the appropriate level of delivery risk. This was informed by delivery

risk levels assigned to similar habitat types by Defra. Tables 2.4 and 2.5 show risk factors assigned

to each level of delivery risk and type of habitat on this scheme.


Table 2-4 - Defra delivery risk factors

DIFFICULTY OF RECREATION OR RESTORATION

DELIVERY RISK FACTOR

Very High 0.10

High 0.33

Medium 0.67

Low 1.00

Table 2-5 – Delivery risk of created habitats

JNCC HABITAT TYPE DIFFICULTY OF RECREATION

DELIVERY RISK FACTOR

A1.1.1 Broadleaved woodland – semi-natural Medium 0.67

A1.1.2 Broadleaved woodland – plantation Low 1

B2.2 Neutral grassland – semi-improved Low 1

B5 Marsh/marshy grassland Medium 0.67

F2.1 Marginal vegetation Low 1

G1 Standing water Medium 0.67

J1.2 Cultivated/disturbed land – amenity grassland Low 1

J4 Bare ground Low 1

2.4 TEMPORAL RISK

2.4.1 In delivering compensation for loss of habitats, the timing of impact may not coincide with the new

habitat reaching the required quality or level of maturity which could result in loss of biodiversity for a

period of time. This risk is accounted for by applying a ‘temporal risk’ multiplier to the biodiversity unit

calculations.

2.4.2 Defra has no set guidance on the time taken to reach a specific condition for each habitat type.

Therefore, this information was taken from Appendix C of the BRE Guidance Note 36 as outlined in

Tables 2.6 and 2.7.


Table 2-6 - Temporal risk factors

Table 2-7 - Temporal risk for created habitats

HABITAT TYPE YEARS TO TARGET

CONDITION

TEMPORAL RISK FACTOR

A1.1.1 Broadleaved woodland – semi-natural 32+ 0.33

A1.1.2 Broadleaved woodland – plantation 20 0.71

B2.2 Neutral grassland – semi-improved 10 0.71

B5 Marsh/marshy grassland 5 0.83

F2.1 Marginal vegetation 2 0.93

G1 Standing water 0 1

J1.2 Cultivated/disturbed land – amenity grassland 2 0.93

J4 Bare ground 0 1

2.5 CALCULATING THE CHANGE IN BIODIVERSITY UNITS AS A

CONSEQUENCE OF THE PROPOSED SCHEME

2.5.1 The following formula is used to calculate the change in BU as a consequence of the Proposed

Scheme:

POST-DEVELOPMENT BIODIVERSITY UNITS – BASELINE BIODIVERSITY UNITS = CHANGE

IN BIODIVERSITY UNITS

2.5.2 If this resulting score is negative there is a net loss in biodiversity for area-based habitats. If the score

is close to zero (with the post-development units being within 95%-104% of the baseline units) there

YEARS TO TARGET CONDITION

TEMPORAL RISK FACTOR

Under 1 year 1

1 0.97

2 0.93

3-5 0.83

6-10 0.71

11-15 0.59

16-20 0.50

21-25 0.42

26-30 0.35

32+ 0.33


is no net loss of biodiversity for area-based habitats. If there is an increase in the BU of 5% or more

the project is capable of delivering net gain for biodiversity for area-based habitats. The percentage

should be rounded to the nearest whole percentage point.


3 ASSUMPTIONS AND LIMITATIONS

3.1 BASELINE BIODIVERSITY AND LINEAR UNIT CALCULATION

3.1.1 The following assumptions were made for the baseline biodiversity unit and linear unit calculations.

DISTINCTIVENESS

All G1 Standing water is assumed to be of High distinctiveness, in line with Appendix C of the BRE

guidance.

All hedgerows are assumed to be of High distinctiveness because the vast majority of hedgerows

will meet the Habitat of Principal Importance criteria. For this reason, distinctiveness is not included

as part of the linear unit calculation. This follows the approach set out by Defra.

CONDITION

3.1.2 Where no primary condition information was available, the following assumptions were made:

All hedgerows with the exception defunct hedgerows were assigned a condition rating of Good.

Defunct hedgerows were assigned a condition rating of Moderate because by nature of being

defunct will fail one criterion of the FEP condition assessment.

3.2 POST-DEVELOPMENT BIODIVERSITY AND LINEAR UNIT CALCULATION

3.2.1 The following assumptions were made for the post-development biodiversity unit and linear unit

calculations.

STANDING WATER

All G1 Standing water is assumed to be of Medium distinctiveness, this is a deviation from Appendix

C of the BRE guidance because not all G1 Standing water will be created for the purpose of ecological

mitigation and therefore may not be a High distinctiveness habitat.

TARGET CONDITION

It is assumed that Low distinctiveness habitats will reach Poor condition.

Target conditions for Medium and High distinctiveness habitat types have been assigned using

expert judgment and knowledge of the Proposed Scheme.

• It is assumed that created A1.1.1 Broadleaved semi-natural woodland and F2.1 Marginal

vegetation will reach Moderate condition.

• It is assumed that created G1 Standing water is a drainage feature for the Proposed Scheme.

The drainage will not be designed for the purpose of ecological mitigation. Therefore, it is

assumed that the created G1 Standing water will reach Moderate condition.

• It is assumed that created A1.1.2 Broadleaved woodland – plantation and B2.2 Neutral

grassland – semi-improved will reach Good condition.

BARE GROUND

An area of 12.54 hectares of habitat has been categorised as J4 Bare ground post-development. This

is because it is currently unknown what will happen to this habitat area because it falls within the

boundary of another proposed development as well as the footprint of the Proposed Scheme. It is


likely that the area will be cleared for construction or creation of new habitat. Although other areas of

J4 Bare ground are assigned units in the baseline, this area is not assigned any post-development

units. The reason for this decision is that undisturbed J4 Bare ground has some biodiversity value, but

it is likely that this habitat will be disturbed due to construction and will therefore not be a suitable

habitat.

TEMPORARY CONSTRUCTION IMPACTS

There are currently no temporary compound locations or site plans for the construction areas. It is

assumed, as a precautionary approach, that any area of habitat which is proposed within the

landscape plan is cleared during construction and then created from scratch. Therefore, all proposed

post-development habitats which are not retained are created from scratch rather than enhanced.

SPATIAL RISK FACTOR

It is assumed that habitat compensation, enhancement or retention will be delivered within the

Proposed Scheme’s footprint or within the same ecological network as the loss occurs. Therefore, the

spatial risk factor is not included within the post-development biodiversity unit calculations.

3.3 LIMITATIONS

3.3.1 The BU and LU calculations do not account for indirect impacts that may happen to habitats outside

of the Proposed Scheme footprint. Given all required construction compounds and accesses are

included in the Proposed Scheme, this limitation is unlikely to have any effect on the BNG calculations.

3.3.2 The baseline BNG calculations are based on the Phase 1 Habitat survey data whereas the post-

development BNG calculations are based upon the detailed landscape plan. Therefore, it is possible

that minor discrepancies exist between the areas of retained habitat post-development and the

baseline habitats. Any discrepancies will not change the overall outcome of the BNG assessment.

3.3.3 The post-development habitat map was drawn up from the CAD plan into GIS and as a result there is

a minor discrepancy of 0.06 hectares between the area of the baseline and post-development footprint

of the Proposed Scheme.


4 RESULTS OF BASELINE BIODIVERSITY AND LINEAR UNIT

CALCULATIONS

4.1 OVERVIEW

4.1.1 Tables 4.1, 4.2 and 4.3 show the baseline habitat types and the number of BU and LU attributed to

existing habitats within the Proposed Scheme footprint. For a Phase 1 map of the Proposed Scheme’s

baseline habitats, please refer to Appendix C.

4.2 AREA-BASED HABITATS

Table 4-1 - Baseline BU of the Proposed Scheme: habitat lost

JNCC HABITAT TYPE DISTINCTIVENESS

SCORE CONDITION

SCORE AREA (HA

to 0.01) BU

A1.1.1 Broadleaved woodland – semi-natural

High (6) Poor (1) 0.01 0.06

A1.1.2 Broadleaved woodland – plantation

Medium (4) Poor (1) 0.02 0.08

A2.1 Dense scrub Medium (4) Poor (1) 0.37 1.48

A2.2 Scattered scrub Medium (4) Poor (1) 0.03 0.12

A3.1 Broadleaved parkland/ scattered trees

Medium (4) Good (3) 0.21 2.52

A3.3 Mixed parkland/ scattered trees

Medium (4) Good (3) 0.04 0.48


Medium (4) Moderate (2) 0.04 0.32

B6 Poor semi-improved grassland Low (2) Poor (1) 11.14 22.28

C3.1 Other tall herb or fern – Ruderal/ ephemeral

Low (2) Poor (1) 2.02 4.04

F2.1 Marginal vegetation High (6) Moderate (2) 0.05 0.6

J1.1 Arable land Low (2) Poor (1) 15.34 30.68

J1.3 Ephemeral/ short perennial Low (2) Moderate (2) 0.05 0.2

J1.3 Ephemeral/ short perennial Low (2) Poor (1) 0.23 0.46

J4 Bare ground Low (2) Poor (1) 0.16 0.32

J5 Hardstanding N/A N/A 1.04 0.00

TOTAL 30.75 63.64


Table 4-2 - Baseline BU of the Proposed Scheme: habitat retained


SCORE CONDITION

SCORE AREA (HA

to 0.01) BU


High (6) Moderate (2) 0.00 0.00

A1.1.2 Broadleaved woodland - plantation

Medium (4) Poor (1) 0.33 1.32




Medium (4) Good (3) 0.03 0.36




Medium (4) Poor (1) 0.03 0.12





Low (2) Poor (1) 1.39 2.78

F2.1 Marginal vegetation High (6) Good (3) 0.04 0.72


G1 Standing water High (6) Moderate (2) 0.04 0.48

G1 Standing water High (6) Poor (1) 0.04 0.24


J1.2 Amenity grassland Low (2) Poor (1) 0.01 0.02




TOTAL 10.35 30.18

4.3 IRREPLACEABLE HABITATS

4.3.1 No irreplaceable habitats were identified within the red line boundary of the Proposed Scheme.


4.4 LINEAR HABITATS

4.4.1 Tables 4.3 and 4.4 show that there is a total of 2900 LU (1060m) of hedgerow on site of which 30 LU

(10m) will be retained and 2870 LU will be lost.

Table 4-3 – Baseline hedgerow LU lost

JNCC HABITAT TYPE CONDITION SCORE LENGTH (to nearest m)

LU

J2.1.1 Hedges – intact – native species-rich

Good (3) 275 825

J2.1.2 Hedges – intact - native species-poor

Good (3) 429 1287

J2.2.1 Hedges – defunct – native species-rich

Moderate (2) 280 560

J2.3.2 Hedges – with trees – native species-poor

Good (3) 66 198

TOTAL 1050 2870

Table 4-4 – Baseline hedgerow LU retained


LU

J2.1.2 Hedges - intact - native species-poor

Good (3) 10 30

TOTAL 10 30

Table 4-5 – Baseline watercourse LU lost


LU

G2 Running water N/A 107 N/A

TOTAL 107 N/A

Table 4-6 – Baseline watercourse LU retained


LU


TOTAL 413 N/A

4.4.2 There is a total of 520m of watercourse on site. Of which, 413m will be retained and 107m will be lost.


5 RESULTS OF THE POST DEVELOPMENT BIODIVERSITY AND

LINEAR UNIT CALCULATIONS

5.1.1 Tables 5.1 and 5.2 show the BU of retained baseline habitats and the BU generated from created

habitats post-development. Table 5.3 shows a summary of the results of the area-based habitat BNG

assessment. Post-development there will be 125.60 BU within the Proposed Scheme’s footprint. Of

which, 95.42 BU is generated by newly created habitat and 30.18 BU by retaining baseline habitat.

Table 5-1 – Post-development – retained habitats


SCORE CONDITION

SCORE AREA (HA

to 0.01) BU


High (6) Moderate (2) 0.00 0.00

A1.1.2 Broadleaved woodland – plantation

Medium (4) Poor (1) 0.33 1.32




Medium (4) Good (3) 0.03 0.36




Medium (4) Poor (1) 0.03 0.12





Low (2) Poor (1) 1.39 2.78

F2.1 Marginal vegetation High (6) Good (3) 0.04 0.72


G1 Standing water High (6) Moderate (2) 0.04 0.48

G1 Standing water High (6) Poor (1) 0.04 0.24



J1.2 Amenity grassland Low (2) Poor (1) 0.01 0.02




TOTAL 10.35 30.18

Table 5-2 – Post-development – created habitats

JNCC HABITAT TYPE DISTINCTIVENESS TARGET

CONDITION DIFFICULTY

RISK TEMPORAL

RISK AREA (ha)

POST-DEVELOPMENT

BU


High (6) Moderate (2) Medium (0.67)

32+ yrs (0.33)

2.82 7.48

A1.1.2 Broadleaved woodland –plantation

Medium (4) Good (3) Low (1) 20 yrs

(0.5) 0.00 0.00

B2.2 Neutral grassland – semi-improved

Medium (4) Good (3) Low (1) 10 yrs

(0.71) 8.94 76.17

B5 Marshy grassland

Low (2) Poor (1) Medium (0.67)

5 yrs

(0.83) 0.86 0.96

F2.1 Marginal vegetation

High (6) Moderate (2) Low (1) 2 yrs

(0.93) 0.47 5.25

G1 Standing water Medium (4) Moderate (2) Medium (0.67)

0 yrs

(1) 1.73 5.36

J1.2 Cultivated/ disturbed land – amenity grassland

Low (2) Poor (1) Low (1) 2 yrs

(0.93) 0.14 0.2

J4 Bare ground Low (2) N/A Low (1) 0 yrs

(1) 12.54 N/A

J5 Hardstanding N/A N/A N/A N/A 3.33 N/A

TOTAL

fhafohaofh

30.83 95.42


Table 5-3 – BU results summary

Area (Hectares)

BU

BASELINE HABITAT LOST

30.75 63.64

BASELINE HABITAT RETAINED

10.35 30.18

TOTAL BASELINE AREA 41.10 93.82

POST-DEVELOPMENT HABITAT CREATED

30.83 95.42

TOTAL AREA POST-DEVELOPMENT

41.16 125.60

5.1.2 Tables 5.4 and 5.5 show the length of hedgerow created post-development and the hedgerow LU

retained in the baseline respectively. Table 5.6 provides a summary of the linear results of this

assessment. Post-development there will be 1563 hedgerow LU (1543m) within the Proposed

Scheme’s footprint. 1533 LU of watercourses will be created and 30 LU will be retained.

Table 5-4 – Hedgerow LU created post-development


LU

J2.1.1 Hedges – intact – native species-rich

N/A 1148 1148

J2.3.1 Hedges – with trees – native species-rich

N/A 385 385

TOTAL 1533 1533

Table 5-5 –Hedgerow LU retained from baseline


LU

J2.1.2 Hedges - intact - native species-poor

Good (3) 10 30

TOTAL 10 30


Table 5-6 – Hedgerow LU results summary

Length (m) Hedgerow

LU

TOTAL HEDGEROWS AT BASELINE

1060 2900

BASELINE HEDGEROWS LOST

1050 2870

BASELINE HEDGEROWS RETAINED

10 30

HEDGEROWS CREATED

1533 1533

TOTAL HEDGEROWS POST-DEVELOPMENT

1543 1563

5.1.3 Tables 5.7 and 5.8 show the length of watercourse created post-development and retained in the

baseline respectively. Table 5.9 provides a summary of the results of the watercourse assessment

Post-development there will be 2358m of watercourse habitats within the Proposed Scheme’s footprint

of which 55m will be culverted. The culverted area will result in a loss of biodiversity value of the linear

feature but this loss is not captured by the current linear metric which simply presents the watercourse

LU as a length in m. 1945m of watercourses will be created and 413m will be retained.

Table 5-7 – Watercourse LU created post-development


LU


TOTAL 1945 N/A

Table 5-8 –Watercourse LU retained from baseline


LU

G2 Running water (55m culverted) N/A 413 N/A

TOTAL 413 N/A


Table 5-9 – Watercourse LU results summary

Length (m) or

Watercourse LU

TOTAL WATERCOURSES AT BASELINE

520

BASELINE WATERCOURSES LOST

107

BASELINE WATERCOURSES RETAINED

413

WATERCOURSES CREATED

1945

TOTAL WATERCOURSES POST-DEVELOPMENT

2358


6 SUMMARY OF RESULTS AND RECOMMENDATIONS

6.1 SUMMARY OF RESULTS

6.1.1 Table 6.1 demonstrates that the Proposed Scheme design will result in a net gain for biodiversity for

area-based habitats (an increase of 31.78 BU which equates to 34% net gain), a net loss for linear

hedgerow habitats (a decrease of 1337 LU which equates to a 46% net loss) and a net gain of linear

watercourse habitats (a net gain of 1838 m which equates to a 353% net gain).

Table 6-1 – Summary of results

Area

(Hectares) BU

Hedgerow Length (m)

Hedgerow LU

Length (m) or Watercourse

LU


FEATURE AT BASELINE

41.10 93.82 1060 2900 520


FEATURE POST-DEVELOPMENT

41.16 125.60 1543 1563 2358

OUTCOME NET GAIN OF 34%

(+31.78 BU)


NET LOSS OF 46%

(1337 LU)


6.1.2 Although there is a very significant biodiversity net gain of area-based habitats and

watercourse LU, the Proposed Scheme cannot claim that it will deliver a net gain in biodiversity

within the site boundary due to the loss of Hedgerow LU.

6.1.3 Although there is a net increase in length of hedgerows of approximately 483m, there is an overall

loss of 1337 LU. Using the current metric it is difficult to deliver significant gains for even relatively

limited loss of linear units, without providing considerably more habitat (by length) than is lost. This is

because the current hedgerow metric does not have any weighting for habitat condition when hedges

are created post-development and the condition assessment for hedgerows does not account for

different levels of species richness. The metric for linear units is currently under review by Natural

England.

6.1.4 Due to the limitations of the current metric, enhancements of linear habitats that have been proposed

as part of the Proposed Scheme are not captured. Biodiversity enhancement of hedgerows as part of

the Proposed Scheme include increasing the species-richness of existing hedgerows and providing

species-rich hedgerow to replace species-poor hedgerow.

6.1.5 It is important to recognise that the quantification of biodiversity units is one of a number of factors to

be considered when assessing the impact of each stage on biodiversity

6.2 RECOMMENDATIONS

6.2.1 WSP recommends the following next steps for the BNG assessment:


The BNG assessment is re-run once the temporary works layout information is available to ensure

that any impacts resulting from the works are captured and quantified.

The BNG assessment is re-run based on the final landscape plan for the Proposed Scheme.

To avoid re-running the BNG calculations multiple times, the calculations should be re-run once

when the final landscape plan and temporary works layout information is available.

The client should continue to explore any other options to avoid impacts and create more linear

habitats. The client should also continue to emphasise the enhancements of linear habitats that

have been proposed as part of the ES in the BNG report and that these are not captured by the

current metric.


7 REFERENCES

Business and Biodiversity Offsets Programme (BBOP). (2012). BBOP Principles on

Biodiversity Offsets. Available: http://bbop.forest-trends.org/documents/files/bbop_principles.pdf

BRE Group. (2018). GN36 BREEAM, CEEQUAL and HQM Ecology Calculation Methodology –

Route. Available: https://bregroup.com/brebreeam/wp-content/uploads/sites/3/2018/06/GN36-

v0.0-BREEAM-CEEQUAL-HQM-Ecology-Calculation-Methodology-Route-2.pdf

CIEEM, CIRIA & IEMA. (2016). Biodiversity Net Gain: Good practice principles for development.

https://www.iema.net/assets/newbuild/documents/IEMA%20Biodiversity%20Net%20Gain.pdf

Department for Communities and Local Government. (2018). Revised National Planning

Policy Framework. Available:

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/fil

e/740441/National_Planning_Policy_Framework_web_accessible_version.pdf

Department for Environment, Food and Rural Affairs (Defra). (2011). Biodiversity 2020: A

strategy for England's wildlife and ecosystem services. Available:

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69446/pb13583-

biodiversity-strategy-2020-111111.pdf .

Department for Environment, Food and Rural Affairs (Defra). (2012a). Technical Paper: the

metric for the biodiversity offsetting pilot in England. Available:

https://www.gov.uk/government/publications/technical-paper-the-metric-for-the-biodiversity-

offsetting-pilot-in-england

Department for Environment, Food and Rural Affairs (Defra). (2012b). Biodiversity Offsetting

Pilots: Guidance for offset providers. Available:


bio-guide-offset-providers.pdf

Department for Environment, Food and Rural Affairs (Defra). (2012c). Biodiversity Offsetting

Pilots: Guidance for developers. Available:


bio-guide-developers.pdf

Department for Transport. (2014). National policy statement for national networks. Available:

https://www.gov.uk/government/publications/national-policy-statement-for-national-networks

Highways England. (2015). Our plan to protect and increase biodiversity. Available:

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/441300/N150146_-

_Highways_England_Biodiversity_Plan3lo.pdf

JNCC. (2010). Handbook for Phase 1 Habitat Survey: a Technique for Environmental Audit.

Natural England. (2010). Higher Level Stewardship Farm Environment Plan (FEP) Manual

Technical Guidance on the completion of the FEP and identification, condition assessment and

recording of HLS FEP features. Third Edition. NE. Peterborough.

Northamptonshire Local Nature Partnership (2016) Northamptonshire Biodiversity Action Plan

2015 -2020 (3rd Edition). Available:

https://www3.northamptonshire.gov.uk/councilservices/environment-and-

planning/planning/planning-policy/archaeology-biodiversity-and-

landscape/documents/PDF%20Documents/Northamptonshire%20BAP%202015-2020.pdf

http://bbop.forest-trends.org/documents/files/bbop_principles.pdf

https://bregroup.com/brebreeam/wp-content/uploads/sites/3/2018/06/GN36-v0.0-BREEAM-CEEQUAL-HQM-Ecology-Calculation-Methodology-Route-2.pdf

https://bregroup.com/brebreeam/wp-content/uploads/sites/3/2018/06/GN36-v0.0-BREEAM-CEEQUAL-HQM-Ecology-Calculation-Methodology-Route-2.pdf

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https://www.gov.uk/government/publications/technical-paper-the-metric-for-the-biodiversity-offsetting-pilot-in-england

https://www.gov.uk/government/publications/technical-paper-the-metric-for-the-biodiversity-offsetting-pilot-in-england

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69530/pb13742-bio-guide-offset-providers.pdf

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69530/pb13742-bio-guide-offset-providers.pdf

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69528/pb13743-bio-guide-developers.pdf

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69528/pb13743-bio-guide-developers.pdf

https://www.gov.uk/government/publications/national-policy-statement-for-national-networks

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https://www3.northamptonshire.gov.uk/councilservices/environment-and-planning/planning/planning-policy/archaeology-biodiversity-and-landscape/documents/PDF%20Documents/Northamptonshire%20BAP%202015-2020.pdf




The European Commission. (2011). Our life insurance, our natural capital: an EU biodiversity

strategy to 2020. Available:

http://ec.europa.eu/environment/nature/biodiversity/strategy/index_en.htm

Internal References

WSP (2017). North-west relief road. Preliminary Ecological Appraisal. WSP UK Limited.

Birmingham, UK.

WSP (2018a). NNWRR Bat Crossing Point Survey Report. WSP UK Limited. Birmingham, UK.

WSP (2018b). NNWRR Breeding Bird Mitigation Report. WSP UK Limited. Birmingham, UK.

WSP (2018c). NNWRR Hedgerow Survey Report. WSP UK Limited. Birmingham, UK.

WSP (2018d). NNWRR. Preliminary Ecological Appraisal. WSP UK Limited. Birmingham, UK.

WSP (2018e). NNWRR Protected Species Survey Report - Badger Survey Report. WSP UK

Limited. Birmingham, UK.

WSP (2018f). NNWRR Protected Species Survey Report - Barn Owl Survey Report. WSP UK


WSP (2018g). NNWRR Protection Species Survey Report – Bat Surveys. WSP UK Limited.

Birmingham, UK.

WSP (2018h). NNWRR Protection Species Survey Report – Bat Surveys Summary. WSP UK


WSP (2018i). NNWRR Protected Species Survey Report - Great Crested Newt Survey Report.

WSP UK Limited. Birmingham, UK.

WSP (2018j). NNWRR Protected Species Survey Report - Kingfisher Site Appraisal Report. WSP

UK Limited. Birmingham, UK.

WSP (2018k). NNWRR Protected Species Survey Report - Otter and Water Vole Survey Report.

WSP UK Limited. Birmingham, UK

WSP (2018l). NWRR Protected Species Survey Report - Reptile Survey Report. WSP UK


http://ec.europa.eu/environment/nature/biodiversity/strategy/index_en.htm

Confidential

CIEEM, CIRIA AND IEMA UK

BIODIVERSITY NET GAIN GOOD

PRACTICE PRINCIPLES FOR

DEVELOPMENT

NORTHAMPTON NORTH-WEST RELIEF ROAD WSP Project No.: 70045931 | Our Ref No.: BNG MAY 2019 Northampton County Council

Confidential

WSP BIODIVERSITY NET GAIN

PROCESS


Step 1 – Set the Scope

i. Produce a biodiversity net gain (BNG) strategy. A short memo report setting out client

commitments to BNG, scope of the BNG work, and the proposed steps required.

ii. Workshop 1 or 1-2-1 meetings – strategy meetings. Early engagement with key

stakeholders, likely to include local conservation NGOs, local authorities and government

agencies such as Natural England. Early engagement is essential to present, discuss and

develop the BNG strategy; including setting the BNG good practice principles into a scheme

context and agreeing local priorities for biodiversity.

Step 2 – Initial Biodiversity Assessment

i. Survey baseline habitats and their condition. Ideally, a habitat condition assessment is

undertaken during Phase 1 Habitat survey. If Phase 1 Habitat data has been collected prior

to initiating the BNG process, condition assessment can be undertaken either a)

retrospectively through interpretation of Phase 1 target notes, consultation with surveyors, or

employing a number of assumptions; or b) during an additional site visit.

ii. Identify irreplaceable habitat. Following Defra guidance, irreplaceable habitats within the

scheme boundary must be identified and excluded from the biodiversity unit calculations. It is

important to note that biodiversity net gain or no net loss cannot be achieved for the scheme

as a whole if there is a negative impact on an irreplaceable habitat

iii. Calculate baseline biodiversity units using the biodiversity metric. This calculation

includes all habitats (minus irreplaceable habitats) within the scheme boundary prior to

development, and is informed by Phase 1 Habitat data and results of the condition

assessment. The baseline biodiversity unit calculation may be run on a number of scheme

options if the scheme is at options appraisal stage.

iv. Calculate post-development biodiversity units using the biodiversity metric. This

calculation accounts for all of the proposed habitats (including retained habitat and habitat lost

or created as a result of the development) within the scheme boundary post-development. The

calculation is informed by scheme design, landscape plans, and proposed ecological

mitigation. The assessment is based upon the target state (type, size and condition) of habitats

being created.

v. Produce an ‘Initial Biodiversity Assessment’ report. The report sets out the BNG process

in the context of the scheme, and includes the method and results of initial baseline and post-

development biodiversity unit calculations.

Step 3 – Detailed Scheme Assessment

i. Inform options appraisal. If baseline biodiversity units have been calculated for a number of

scheme options, results will be used to inform options appraisal.


ii. Inform the mitigation proposals. Results of biodiversity unit calculations performed under

Step 2 are used to inform the extent and habitat type of on-site ecological mitigation and

compensation land required for the scheme to meet no net loss or net gain targets.

iii. Update biodiversity unit calculations. Following finalisation of the scheme design and

ecological mitigation proposals, the biodiversity units are updated to reflect any changes.

Calculations may also be re-run if updated Phase 1 Habitat data becomes available.

iv. Estimate the biodiversity compensation required. The difference between baseline and

post-development biodiversity units indicates the number of units required for the scheme to

deliver no net loss or net gain for biodiversity. This in turn can be used to identify the extent

and habitat type of compensation required. A rough cost estimate for potential compensation

can be provided at this stage.

v. Workshop 2 – compensation/offset workshop. Work with stakeholders to gather

suggestions to identify candidate compensation sites and providers. These sites could be

offset sites, which are compensation sites that are situated outside the project boundary. This

workshop also provides an opportunity to update stakeholders on BNG progress.

Step 4 – Assessment of Candidate Offset Sites

i. Initial assessment of feasibility. Any candidate offset sites which are considered not feasible

for any reason are scoped out at this stage.

ii. Survey candidate offset sites to identify existing habitat type, extent and condition.

iii. Calculate potential biodiversity units deliverable by each candidate offset. Using the same

methods employed for calculating baseline and post-development biodiversity units for the

scheme as a whole, calculate baseline and post-development biodiversity units for offset sites

to determine potential biodiversity units deliverable.

iv. Hold one-to-one meetings with potential offset providers to:

a) Identify suitable locations for candidate offset sites and determine what habitats and

species they could support;

b) Determine how offsets can contribute to local biodiversity objectives and fit within

ecological networks;

c) Set out the type of agreement that would be acceptable to offset providers (e.g. long

term agreement for management of the land); and

d) Collate information to feed in to offset scoring templates and offset summary sheets.

v. Score candidate offsets using the offset scoring template. This takes into account ecological

factors, financial factors, and wider benefits and opportunities.


vi. Produce offset summary sheets describing each offset site in its present state and the

habitats and species the proposed offsets will support. Details of land ownership, access

provisions and proposed management agreements are also included in summary sheets.

vii. Panel review of potential offset sites to include relevant stakeholders. Decisions are made

as to which candidate offset sites to take forward.

Step 5 – Completion of Biodiversity Assessment

i. Final update of biodiversity unit calculations. If there have been changes to the scheme

design (including environmental mitigation proposals) since calculations were last updated,

biodiversity units are updated to reflect any changes.

ii. Workshop 3 – final workshop. A third stakeholder engagement workshop is recommended

to update all stakeholders on BNG progress since the last workshop, and inform them of any

decisions made.

iii. Produce a ‘Full Biodiversity Assessment’ report and associated GIS data. This will detail

the approach and outcomes of Steps 1 to 4, importantly, how the project has met the BNG

good practice principles. It will set out candidate offset sites and enable the client to decide

which offsets to support and whether to aim for no net loss or net gain.

Step 6 – Delivering Biodiversity Net Gain

i. Implement BNG during the construction phase. This will involve: updating the biodiversity

baseline; including BNG within construction documents; training key staff; reducing the time-

lag between losses and gains; acting on risks and opportunities; and collecting evidence and

data.

ii. Set up offsets. Once offset sites to be delivered have been selected, and fine details of the

scope of each offset agreed, legal agreements will be set up with offset providers to manage

offsets over a set time frame (generally between 15 and 30 years). Further information on the

agreement types can be provided on request.

iii. Monitor and report to ensure the offsets are delivered to the standard required. Monitoring

and reporting is undertaken at key points throughout the management agreement (e.g. once

every two or three years).

Confidential

PHASE 1 MAPS: BASELINE AND

POST-DEVELOPMENT

CONFIDENTIAL

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Bristol

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