NORTHAMPTON NORTH WEST RELIEF ROAD · 2020-06-15 · Northamptonshire County Council NORTHAMPTON NORTH WEST RELIEF ROAD Water Framework Directive Assessment CONFIDENTIAL TYPE OF DOCUMENT

R1 MAY 2020 CONFIDENTIAL

Northamptonshire County Council

NORTHAMPTON NORTH WEST

RELIEF ROAD

Water Framework Directive Assessment

Northamptonshire County Council

NORTHAMPTON NORTH WEST RELIEF ROAD

Water Framework Directive Assessment

CONFIDENTIAL

TYPE OF DOCUMENT (VERSION) CONFIDENTIAL

PROJECT NO. 70058029

OUR REF. NO. R1

DATE: MAY 2020

WSP

8 First Street

Manchester

M15 4RP

Phone: +44 161 200 5000

WSP.com

NORTHAMPTON NORTH WEST RELIEF ROAD CONFIDENTIAL | WSP Project No.: 70058029 | Our Ref No.: R1 May 2020 Northamptonshire County Council

QUALITY CONTROL

Issue/revision First issue Revision 1 Revision 2 Revision 3

Remarks

Date

Prepared by

Neil Burrows

Signature

Checked by Lucy Rushmer

Signature

Authorised by Helena Parsons

Signature

Project number

Report number

File reference


CONTENTS

1 INTRODUCTION 1

1.1 INTRODUCTION 1

1.2 STUDY AREA 1

1.3 INTRODUCTION TO THE WATER FRAMEWORK DIRECTIVE 3

2 METHODOLOGY 5

2.1 DATA COLLECTION 5

2.2 WFD ASSESSMENT PROCESS 10

2.3 LIMITATIONS AND ASSUMPTIONS 10

3 WFD SCREENING AND SCOPING 11

3.1 STAGE 1: WFD SCREENING 11

3.2 STAGE 2: WFD SCOPING 14

4 WFD IMPACT ASSESSMENT 16

4.1 BASELINE CONDITIONS 16

4.2 CATCHMENT CHARACTERISTICS 20

4.3 RHS RESULTS AND BASELINE CHARACTERISTICS AGAINST WFD SURFACE

WATER QUALITY ELEMENTS 21

4.4 IMPACT ASSESSMENT 29

5 CONSTRUCTION IMPACTS 47

5.1 POTENTIAL CONSTRUCTION IMPACTS 47

5.2 CONSTRUCTION MITIGATION 49

6 CONCLUSION 51


7 REFERENCES 52

TABLES

Table 2-1 – Habitat Modification Score (HMS) for Level of Modification 6

Table 2-2 – Habitat Quality Assessment (HQA) Classes and Descriptors 7

Table 3-1 – WFD screening of activities 12

Table 3-2 - WFD scoping of the Proposed Development’s activities against WFD quality

elements 14

Table 4-1 – WFD Status of the Brampton Branch – Lower potentially impacted by the

Proposed Scheme (source EA, 2020a) 16

Table 4-2 - WFD Status of the Church Brampton Arm potentially impacted by the Proposed

Scheme (source EA, 2020b) 17

Table 4-3 - Environment Agency Classification for Nene Mid Lower Jurassic Unit

Groundwater Body (source: EA, 2020c) 19

Table 4-4 – RHS indices for the River Nene 23

Table 4-5 – Numbers of fish caught on 06/06/2019 during a 3-run electric fishing survey of

the River Nene 24

Table 4-6 – Gudgeon Gobio gobio and dace Leuciscus leuciscus population and density

estimates for the River Nene, calculated using the Carle and Strub method. The probability

of an individual fish being captured during each sampling run, along with the standard error

and lower and upper confidence intervals of the population estimate are also displayed 25


Brampton Brook, presented in order of abundance 25

Table 4-8 – RICT WHPT classifications of survey locations at River Nene 26

Table 4-9 – RICT WHPT classifications of survey locations at River Nene and Brampton

Brook 26

Table 4-10 – Pressures, potential impacts and associated mitigation for works to the

impacted watercourses and downstream water bodies (Source: Annex IV: Flood Risk

Management, UKTAG, 2008) 29

Table 4-11 – Operational impacts on the WFD quality elements on the Brampton Branch –

Lower (GB105032045390) water body. Activities that are not expected to have an adverse

impact on each quality element receptor are omitted 31

Table 4-12 - Operational impacts on the WFD quality elements on the Church Brampton

Arm (GB105032045380) water body 42


Table 4-13 – Compliance assessment of the Proposed Scheme against WFD Status 45

Table 5-1 – Potential construction impacts on the water bodies 47

FIGURES

Figure 1-1 – General Arrangement of the Proposed Scheme 2

NORTHAMPTON NORTH WEST RELIEF ROAD CONFIDENTIAL | WSP Project No.: 70058029 | Our Ref No.: R1 May 2020 Northamptonshire County Council 1 of 52

1 INTRODUCTION

1.1 INTRODUCTION

1.1.1. This Water Framework Directive assessment (WFDa) has been prepared in order to assess the

risks to the water environment posed by the Northampton North West Relief Road hereafter referred

to as the ‘Proposed Scheme’. The Proposed Scheme interacts with a number of watercourses

throughout its length: thus, each activity associated with the Proposed Scheme, such as

watercourse crossings, culverts and outfalls, will be assessed against the biological, physico-

chemical and hydromorphological quality elements that comprise the WFD.

1.1.2. The Proposed Scheme comprises a single carriageway road of approximately 1.5km in length which

runs along a north-south alignment to the west of the River Nene and is referred to as the NWRR

Mainline. To the north, it would connect to Sandy Lane via a new roundabout, before connecting to

the A5199 Welford Road. To the south the Proposed Scheme crosses Brampton Brook and the

railway line before connecting to a new roundabout, east of Grange Farm, which would provide

access to the proposed Dallington Grange residential development.

1.1.3. From the new roundabout to the north, a second element of the Proposed Scheme, hereafter

referred to as the Causeway, will cross the River Nene parallel to the A5119, re-joining the A5119

via a second roundabout at Brampton Lane.

1.2 STUDY AREA

1.2.1. The study area is located northwest of Northampton and includes the River Nene and Brampton

Brook (a tributary of the River Nene) watercourses. The watercourses belong to separate WFD

water bodies: Brampton Branch – Lower (GB105032045390) and Church Brampton Arm

(GB105032045380) respectively; both of which could be potentially adversely impacted by the

Proposed Scheme. The two water bodies sit within the Brampton Brach operational catchment, the

Nene management catchment and the Anglian river basin district. The study area is shown in Figure

1.1.

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FIGURE 1.1 - GENERAL ARRANGEMENT OF THE

PROPOSED SCHEME

AP

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This map is reproduced from Ordnance Survey material with

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Northamptonshire County Council: Licence No. 100019331.

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INFRASTRUCTURE


1.3 INTRODUCTION TO THE WATER FRAMEWORK DIRECTIVE

1.3.1. An impact assessment of any works/modifications to water bodies in the UK is required under the

European Union’s Water Framework Directive (2000/60/EC). The WFD is transposed into law in

England and Wales by the Water Environment (Water Framework Directive) (England and Wales)

Regulations 2017. Compliance with the WFD legislation is required for permitting of the Proposed

Scheme.

1.3.2. The primary aim of the WFD is to improve/maintain the Ecological Status/Potential of all water

bodies and to prevent deterioration in status of the water bodies and their associated WFD quality

elements. Ecological Status/Potential is determined by a suite of biological, physico-chemical and

hydromorphological quality elements. This WFD assessment aims to establish the baseline

conditions, evaluate potential impacts of the Proposed Scheme and assess compliance against

WFD objectives.

1.3.3. The overarching objective of the WFD is for surface water bodies in Europe to attain overall ‘Good

Ecological Status’ (GES) or ‘Good Ecological Potential’ (GEP). GES refers to situations where the

ecological characteristics show only a slight deviation from natural/near natural conditions. In such

a situation, the biological, chemical, physico-chemical and hydromorphological conditions are

associated with limited or no human pressure. Artificial and heavily modified water bodies have a

target to achieve GEP, which recognises their important uses, whilst ensuring the quality elements

are protected as far as possible.

1.3.4. The WFD sets several objectives including:

Prevent deterioration in status for water bodies;

Aim to achieve good biological and good surface water chemical status in water bodies. For

those water bodies that did not achieve GES by 2015, alternative objectives have been set by the

Environment Agency where water bodies have been allocated a target date for compliance of

either 2021 or 2027. The target date set for each water body takes into consideration measures

that are practicably achievable for achieving GES or GEP;

For water bodies that are designated as artificial or heavily modified, the objective is to achieve

GEP. Those artificial/heavily modified water bodies that did not achieve GEP by 2015 need to

achieve compliance by 2021 or 2027;

Where is it considered either technically infeasible or disproportionately expensive to achieve

GES or GEP by 2021 or 2027, alternative objectives have been set for the water body, such as a

target to achieve Moderate status;

Comply with objectives and standards for protected areas, where relevant; and,

Reduce pollution from priority substances and cease discharges, emissions and losses of priority

hazardous substances.

1.3.5. Where a new modification, change in activity or change to a structure on a water body is proposed,

a WFD assessment needs to consider whether the proposed alteration would cause deterioration in

the Ecological Status or Potential of any water body. For heavily modified/artificial water bodies,

proposed new modifications, or changes to activities or structures, may also result in WFD mitigation

measures or actions, set to help a water body achieve GES/GEP, being ineffective. This could result

in the water body failing to meet GES/GEP. Where a WFD assessment concludes that deterioration

or failure to achieve GES/GEP may occur, an Article 4.7 assessment would be required, which

makes provision for deterioration of status provided that certain stringent conditions are met.


1.3.6. The purpose of this WFD assessment is to evaluate the potential operational impacts arising due to

the proposed diversion of the Brampton Branch - Lower (GB105032045390) and Church Brampton

Arm (GB105032045380) water bodies. The potential construction impacts are also evaluated due to

the potential effects they may have upon the status of WFD quality elements.

1.3.7. The assessment methodology used here is based on guidance provided by the Planning

Inspectorate Advice Note 18: The Water Framework Directive. This guidance outlines a three-stage

process to WFD assessment: screening, scoping, and impact assessment.

STAGE 1: SCREENING

1.3.8. Screening is required to identify activities which have the potential to result in deterioration of a

water body or fail to comply with the objectives of that water body. Screening also serves to identify

those proposed activities (e.g. proposed construction methods) that are required to be taken through

to scoping, and those activities that are unlikely to result in the deterioration of the water body.

STAGE 2: SCOPING

1.3.9. Scoping is required to identify risks to receptors from a project’s activities, based on the relevant

water bodies and their water quality elements (including information on status, objectives, and the

parameters for each water body). Potential risks to hydromorphology, biology (habitats and fish),

water quality, WFD protected areas and invasive non-native species should be assessed. The

scoping stage identifies which elements need to be carried forward to Stage 3.

STAGE 3: IMPACT ASSESSMENT

1.3.10. Where assessment has been considered necessary at scoping stage, an impact assessment is

carried out for each receptor identified as being at risk in terms of potential deterioration or non-

compliance with its specific objectives as set out in the River Basin Management Plan as a result of

the project. Where the potential for deterioration of water bodies is identified, and it is not possible to

mitigate the impacts to a level where deterioration can be avoided, the project would need to be

assessed in the context of Article 4(7) of the WFD.


2 METHODOLOGY

2.1 DATA COLLECTION

DESK STUDY

A desk-based study was carried out to inform the WFD assessment, reviewing the existing

information of the Proposed Scheme and study area to develop a baseline for the catchments,

watercourses and surrounding areas. The following data sources were used for the desk study:

contemporary OS maps;

geology and soil maps;

current aerial photography;

Environment Agency ecology data;

historic maps;

designated areas data;

hydrological information; and,

WFD status and objectives from the 2015 Anglian River Basin Management Plan for cycle 2 data.

FIELD SURVEY

Geomorphology/Hydromorphology Walkover Survey

2.1.1. No geomorphology walkover survey has been undertaken at the time of writing due to work and

travel restrictions. See section 2.3.

RIVER HABITAT SURVEY

Field Survey

2.1.2. River Habitat Surveys (RHS) were completed by two accredited RHS surveyors (FA023E & FA067)

on 27 June 2019.

2.1.3. Surveys were carried out using standard methodology as detailed in the RHS Field Survey

Guidance Manual: 2003 Version (Environment Agency, 2003) to characterise the physical habitat

character, structure and degree of morphological modification of the River Nene and Brampton

Brook.

2.1.4. Two RHS were conducted. One of 500m between SP 73441 65326 and SP 73385 64868 along the

River Nene and one of 700m between SP 72704 64208 and SP 73480 64247 along Brampton

Brook. Survey locations were chosen to capture the proposed locations of the river crossing points.

2.1.5. Measurements were taken for the following variables as part of the survey:

A. General field survey details;

B. Predominant valley form;

C. Number of riffles, pools and point bars;

D. Artificial features;

E. Physical attributes of the left and right bank, and channel;

F. Bank top land-use and vegetation structure;

G. Channel vegetation types;

H. Land-use within 50m of bank top;

I. Bank profiles;


J. Extent of trees and associated features;

K. Extent of channel and bank features;

L. Channel dimensions;

M. Features of special interest;

N. Choked channel;

O. Notable nuisance plant species; and,

P. Overall characteristics.

2.1.6. The measurements for variables E., F. and G. were taken in the form of 10 spot-checks. These

consisted of 10 survey points 50m apart with a 1-10m survey plot across the river depending on the

type of measurement.

2.1.7. The remainder of the measurements were taken either as part of the 500m stretch which aims to

identify any features observed within the 500m survey area, but not falling within the 10 spot-check

locations or the single survey point at 1 location on a straight or uniform section of the river to

measure more detailed physical attributes of the river. GPS co-ordinates for all spot check locations

were recorded to aid further assessment in the future if required.

2.1.8. Photographs were taken throughout the survey at the spot check locations, at each occurrence of

habitat modification (such as bridges and bank reinforcement) and to record any other features of

interest noted within the vicinity of the river corridor.

Indices

2.1.9. Several indices were calculated from the features recorded including, Habitat Modification Score

(HMS) and Habitat Quality Assessment (HQA).

2.1.10. The HMS was calculated by scoring all the modifications recorded on the RHS, for example: those

features that are not naturally formed. These modifications are graded depending on the level of

alteration and impact they have on the watercourse, for example, brick/laid stone scores 50 at each

spot check where it is recorded. The modifications recorded in the RHS are totalled and the overall

value is given a score. The HMS was then converted into a Habitat Modification Class (HMC), which

is on a scale from 1-5, see Table 2-1 below:

Table 2-1 – Habitat Modification Score (HMS) for Level of Modification

HMS Score HMC Class Description

0-16 1 Pristine/semi-natural

17-199 2 Predominantly unmodified

200-499 3 Obviously modified

500-1399 4 Significantly modified

1400+ 5 Severely modified

2.1.11. The HQA scoring system provides an indication of the diversity and ‘naturalness’ of the physical

(habitat) structure of a site, including both the channel and river corridor. The HQA score was


determined by the presence and extent of habitat features of known wildlife interest recorded during

the field survey. Additional points reflect the variety of substrate, flow-types, in-channel vegetation

(affected by the presence of fluvial features), and the extent of trees and semi-natural land-use

adjacent to the river. Points are added together to provide the HQA.

2.1.12. The HQA Class was calculated by comparing the HQA score for a site with 150 most similar sites

from the first baseline survey dataset. These 150 sites are identified as closest to a site based on a

principal component analysis (PCA) plot. The PCA plot was derived using a site’s map-based data

(gradient, altitude, distance from source, altitude of source).

2.1.13. The HQA score was then placed in an HQA class based on the comparison with the 150 closest

sites selected. There are five HQA classes as detailed in Table 2-2 below:

Table 2-2 – Habitat Quality Assessment (HQA) Classes and Descriptors

AQUATIC MACROINVERTEBRATE SAMPLING

Field Survey

2.1.14. Aquatic macroinvertebrate sampling was carried out on 9 May 2019. Samples were collected by two

suitably qualified aquatic ecologists with over 15 years of combined sampling experience.

2.1.15. Samples were collected from four locations; two from the River Nene (SP 73466 65343 and SP

73439 65292) and two from Brampton Brook (SP 73441 64263 and SP 73212 64201).

2.1.16. Aquatic macroinvertebrate samples were collected using standard three-minute kick sampling of all

in-channel habitats in proportion to their occurrence using a standard sampling net (1mm mesh).

This is followed by a with a one-minute timed search following the Environment Agency (2017)

procedure, which conforms to BS EN ISO 10870:2012 Water Quality – Guidelines for the selection

of sampling methods and devices for benthic macroinvertebrates in fresh waters (British Standards

Institute, 2012).

2.1.17. A standardised field sheet was completed to include details of channel and bank physical habitat

(material of banks and substrates, flow types, physical processes, bank structure), riparian land use

and potential sources of anthropogenic stress. Measurements of conductivity, water temperature,

dissolved oxygen and pH were also obtained at each sampling location.

HQA Class Description of Habitat Quality

1 Very high

2 High

3 Fair

4 Poor

5 Very poor


2.1.18. Samples were placed in one-litre sample pots, preserved in Industrial Denatured Alcohol (IDA) on

site and transported to the laboratory for sorting and identification to Taxonomic Level 5 (TL5), in

adherence with Environment Agency (2014) procedures.

Whalley, Hawkes, Paisley and Trigg (WHPT)

2.1.19. The WHPT metric (WFD-UKTAG, 2014) is based on the tolerance of different aquatic

macroinvertebrates to organic pollution. Each aquatic macroinvertebrate family is assigned a score

from -1.6 to 13, depending on their tolerance to pollution and abundance category (on a continuous

scale, -1.6 is for highly abundant pollution-tolerant taxa, 13 is for highly abundant pollution-intolerant

taxa) and an overall score is produced from the total. The WHPT index is widely used to determine

the ecological water quality of running waters and specifically the detection of organic pollution. As

such, any extrapolation of other water quality pressures should be undertaken with caution.

2.1.20. The Average Score Per Taxon (ASPT) is derived from the WHPT index. By dividing the total WHPT

score by the number of scoring taxa present (NTAXA), the average score per taxon can be

calculated. This metric is more easily comparable with other sites and permits an assessment of

biological water quality that is less influenced by the presence of a greater proportion of low scoring

taxa or sampling effort than the overall WHPT score. In both the case of WHPT score and ASPT,

higher scores indicate better ecological quality.

River Invertebrate Classification Tool (RICT)

2.1.21. RICT determines the ecological condition of a given location based on a comparison of aquatic

macroinvertebrate communities observed at each study site with communities observed at reference

sites (Davy-Bowker et al, 2008).

2.1.22. RICT reference sites are deemed to be as close as possible to pristine conditions and not impacted

by environmental stressors such as pollution, habitat modification or flow stress.

2.1.23. Reference sites provide an expected aquatic macroinvertebrate community score for that river type.

The observed aquatic macroinvertebrate community score at a given study site is divided by the

expected community score.

2.1.24. Reference and bias adjustments are then applied to obtain the Ecological Quality Ratio (EQR) which

can be compared against WFD-related quality class boundaries.

Water Framework Directive (WFD) Classification

2.1.25. The WFD uses the pollution sensitivity (WHPT ASPT) and aquatic macroinvertebrate richness

(WHPT NTAXA) EQR scores to determine whether a watercourse meets Good Ecological Status, as

required under the Directive.

2.1.26. There are five ecological status classes: Bad, Poor, Moderate, Good and High.

2.1.27. Where an aquatic macroinvertebrate community is recorded at, or above Good Ecological Status,

then biological or physical pressures including flow and pollution are not assumed to be affecting

aquatic ecology.

2.1.28. Watercourses failing to meet Good Ecological Status for aquatic macroinvertebrates may be

influenced by a variety of stressors, and EQRs can be interrogated to determine the likely cause of

failure to meet Good Ecological Status.


ELECTRIC FISHING

Field Survey

2.1.29. The fish communities of the River Nene and Brampton Brook were surveyed on 5 June and 6 June

2019 respectively by using standard electric fishing methodologies. The survey was carried out by

suitably surveyors with over 30 years of combined electric fishing experience.

2.1.30. The River Nene was surveyed between SP 73430 65305 and SP 73411 65221. Brampton Brook

was surveyed between SP 73453 64269 and SP 73360 64243.

2.1.31. Electric fishing is the term applied to a process that establishes an electric field in the water in order

to capture fish. When exposed to the field, most fish become oriented toward the anode and as the

density of the electric field increases as they swim toward it. In close proximity to the anode, they

are temporarily immobilised.

2.1.32. Electric fishing followed a standard electric fishing method and technique following guidelines

developed by the Environment Agency (Beaumont et al., 2002; EA, 2001; EA, 2007) and which

conformed to British Standard BS EN 14011:2003 Water Quality – Sampling of Fish with Electricity

(British Standards Institution, 2003).

2.1.33. Measurements of conductivity, water temperature, dissolved oxygen and pH were obtained at each

survey location prior to sampling.

2.1.34. Electric fishing of an 87m long section of the River Nene was carried out by a three-person fishing

team, two of which waded the watercourse whilst sampling with hand-held electrodes, powered by a

generator/control box system. A third surveyor removed immobilised fish from the electrical field with

the use of a dipnet.

2.1.35. A 97m long section of Brampton Brook was surveyed by a two-person fishing team, one of which

waded the watercourse whilst sampling using an E-Fish 500W Backpack System. The second

surveyor removed immobilised fish from the electrical field with the use of a dipnet.

2.1.36. Surveyed sections of both watercourses were isolated using stop nets and fished multiple times until

a depletion of fish was noted. Sampled fish were transferred to an aerated container from which they

were identified to species level.

2.1.37. Small fish species, including as 3-spined stickleback Gasterosteus aculeatus, bullhead Cottus gobio,

minnow Phoxinus phoxinus and stone loach Barbatula barbatula, are not efficiently sampled by

electric fishing techniques. Therefore, such species, referred to as minor species, were not counted

and measured during electric fishing surveys. This approach is consistent with EA electric fishing

survey methods.

2.1.38. All fish other fish were counted and measured from the tip of their snout to the end of the middle

caudal fin rays (fork length (FL)). Once processed, all fish were returned safely to the watercourse.

2.1.39. After electric fishing had been completed, a fish habitat survey was carried out. This survey included

an assessment of water depth; channel, bank and bed widths; flow, substrate composition; and bank

characteristics of the watercourse. The vegetation types present, along with percentage canopy

cover and percentage fish cover, were also recorded.


Fish population estimation

2.1.40. Fish population estimates were calculated using the Carle and Strub method (Carle and Strub,

1978) within “Removal Sampling 2” data analysis software (Seaby and Henderson, 2007).

2.1.41. This method is considered to give an accurate estimate of fish population size providing the

following criteria are met:

The catching procedure must not lower (or increase) the probability of a fish being caught;

The population must remain stable during the trapping or catching period; there must not be any

significant natality, mortality (other than by the trapping) or migration. The procedure must not

disturb the fish so that they flee from the area;

The population must not be so large that the catching of one member interferes with the catching

of another; and,

The chance of being caught must be equal for all fish.

2.2 WFD ASSESSMENT PROCESS

2.2.1. The sequence of the WFS compliance assessment is summarised below:

Step 1: Identify potential generic operational impacts of the Proposed Scheme on

hydromorphological quality;

Step 2: Site specific assessment of the proposed Scheme against biological, physico-chemical

and hydromorphological quality elements;

Step 3: Assessment of proposed options against WFD status objectives; and,

Step 4: Assessment of the Proposed Scheme against other EU legislation.

2.2.2. Whilst the assessment of potential construction impacts is not required as part of a WFD

assessment, these impacts may have detrimental impacts on the WFD quality elements and

construction periods may sometimes be of long duration (i.e. several years). Thus, construction

impacts are considered, along with mitigation to reduce or eliminate potential impacts on the water

body and WFD quality elements.

2.3 LIMITATIONS AND ASSUMPTIONS

2.3.1. The progression of this report has, at the time of writing, been affected by the 2020 Covid-19

pandemic. Cancellation of site visit meant it was not possible to arrange a geomorphological

walkover survey before planning submission; therefore, the baseline condition of the

hydromorphological quality elements has been assessed based on site photographs and online

resources (LiDAR data, historical maps, WFD data etc.). The RHS of Brampton Brook was not

completed to the method specification due to the watercourse being inaccessible for part of the

survey stretch. Consequently, Brampton Brook data was unable to be analysed for the RHS indices

described in the methods section (see section 2.1).

2.3.2. Ecological survey data is typically valid for 12 – 18 months unless otherwise specified, for example if

conditions are likely to change more quickly due to ecological processes or anticipated changes in

management (CIEEM, 2019).


3 WFD SCREENING AND SCOPING

3.1 STAGE 1: WFD SCREENING

3.1.1. The purpose of the WFD screening stage is to identify the extent to which the Proposed Scheme

may affect WFD water bodies that lie within the zone of influence of the Proposed Scheme.

SCREENING OF WATER BODIES

3.1.2. The Brampton Branch - Lower (GB105032045390) WFD water body, would be directly impacted by

the Proposed Scheme due to a range of activities that would interact with the local watercourse

network. Therefore, this WFD water body is screened in for further assessment. The Church

Brampton Arm (GB105032045380) WFD water body would also be directly impacted by the

Proposed Scheme due to a range of activities that would interact with the local watercourse network.

Therefore, this WFD water body is screened in for further assessment.

3.1.3. The downstream water body is the Nene - conf Brampton Branch to conf Ise (GB105032045050)

WFD water body. This is considered sufficiently far downstream to avoid impacts of the Proposed

Scheme and is therefore screened out of further assessment.

3.1.4. The groundwater body that underlies the study area is the Nene Mid Lower Jurassic Unit

(GB40502G402400) WFD groundwater body. Activities relating to the construction and operation of

the Proposed Scheme have been assessed in terms of their potential impact upon this groundwater

water body. There are anticipated impacts at the water body scale, therefore assessment of impacts

to groundwater is scoped in.

SCREENING OF ACTIVITIES

3.1.5. The Proposed Scheme comprises the key activities listed below and the screening process is

presented in Table 3-1.

One River Nene bridge crossing;

Two attenuation basins;

One flood embankment;

One Brampton Brook crossing;

One new outfall to main river;

One ordinary watercourse diversion; and,

Vegetation clearance.


Table 3-1 – WFD screening of activities

Activity Description Screening Outcome

Justification

Brampton Branch – Lower (River Nene)

Highway embankments

Engineering works for new highway embankments to support the road alignment. The excavation of material from the proposed floodplain compensation storage areas is proposed to be utilised.

Out The proposed highway embankments are not expected to have an impact upon WFD quality elements therefore this activity is screened out for further assessment.

Bridge crossing A new bridge crossing the Brampton Branch of the River Nene (28m wide with soffit level of 67.6m AOD).

In The proposed bridge crossing has the potential to impact upon a number of WFD quality elements therefore this activity is screened in for further assessment.

Flood Storage Area A

Flood Storage Area A: Offline; West of NWRR Mainline – connected to Nene floodplain through scheme via flood relief culvert. 473230E, 264305N. Base level 63.9m AOD. Plan area approximately ~1700m2.

Out

Discharge the basin will be 5l/s. the size of the basins would likely have negligible effect to groundwater flow in the wider catchment and therefore negligible effect to baseflow to receiving surface water features.

Outfall One outfall discharging treated water from the balancing pond at the causeway to the River Nene.

In Outfalls have the potential to impact upon a number of WFD quality elements and are therefore scoped in for further assessment.

Flood Embankment

Location: approximately 473546E, 263930N to 473816E, 263899N. Embankment crest height varies west to east from 65.5m AOD to 65.3m AOD; approximately 0.5% AEP (200yr) maximum flood level +600mm in the location, before the bund was input. Embankment crest width is 4-5m wide. Embankment side slopes are approximately 1:5.

In The proposed flood embankment has the potential to impact upon a number of WFD quality elements therefore this activity is screened in for further assessment.

Ordinary watercourse diversion

Proposed ordinary watercourse diversion around new flood embankment to retain flow path once construction is completed. Location: from proposed outfall of attenuation

In The ordinary watercourse diversion into the River Nene would potentially impact upon a number of


pond at approximately E473615, N264014 to 473738E, 263982N. Diversion base is approximately 1m wide flat at the bed. Upstream bed level is 62.5m AOD and downstream is 65.3m AOD. This is based very approximately on the adjacent reach of River Nene which has a gradient of about 1:300.

WFD quality elements; therefore, this activity is scoped in for further assessment.

Vegetation clearance

Vegetation clearance is required to facilitate construction of the Proposed Scheme.

In Vegetation clearance would potentially impact upon a number of WFD quality elements; therefore, this activity is scoped in for further assessment.

Three Borrows Pits

Excavated pits, material from which may be used for construction

Out No anticipated impacts on WFD receptors

Church Brampton Arm (Brampton Brook)

Brampton Brook crossing

Brampton Brook bridge: Length 52m, design height 2.8m from bed, design width 7m with abutments set back from bank top on each bank.

In The Brampton Brook crossing would potentially impact upon a number of WFD quality elements; therefore, this activity is scoped in for further assessment.

Flood Storage Area B

Flood storage Area B: Offline; connected to Nene Floodplain and Brampton Beck by area of lowered ground. 473417E, 264067N.Side slope adjacent to railway and scheme is set to 1:7 down to level of 63.51m AOD. Base dropped to 62.51m AOD to provide required volume. Plan area is approximately ~21,000m2

Out Discharge the basin will be 5l/s. the size of the basins would likely have negligible effect to groundwater flow in the wider catchment and therefore negligible effect to baseflow to receiving surface water features.


3.2 STAGE 2: WFD SCOPING

3.2.1. The WFD scoping stage defines the level of detail required for further WFD assessment. This

includes identifying risks to the WFD receptors from the Proposed Development’s activities. The

scoping stage assessment is presented in Table 3-2.

Table 3-2 - WFD scoping of the Proposed Development’s activities against WFD quality

elements

WFD Quality Element Risk to Receptor (Yes/No)

Scoping Outcome Reasoning

Biological Quality Elements

Fish Yes A number of activities associated with the Proposed Scheme have the potential to adversely impact fish; therefore, this quality element is scoped in for further assessment.

Invertebrates Yes A number of activities associated with the Proposed Scheme have the potential to adversely impact Invertebrates; therefore, this quality element is scoped in for further assessment.

Macrophytes and phytobenthos combined

No No known technical solution is available.

Physico-chemical Quality Elements

Thermal Conditions Yes The proposed scheme may have an impact on this quality element; therefore, it is scoped in for further assessment.

Oxygenation Conditions Yes The proposed scheme may have an impact on this quality element; therefore, it is scoped in for further assessment.

Salinity Yes The proposed scheme may have an impact on this quality element; therefore, it is scoped in for further assessment.

Acidification Status Yes The proposed scheme may have an impact on this quality element; therefore, it is scoped in for further assessment.

Nutrient Conditions Yes The proposed scheme may have an impact on this quality element; therefore, it is scoped in for further assessment.

Hydromorphological Quality Elements

Quantity and Dynamics of Water Flow

Yes The proposed scheme may have an impact on this quality element; therefore, it is scoped in for further assessment.


WFD Quality Element Risk to Receptor (Yes/No)

Scoping Outcome Reasoning

Connection to Groundwater Bodies


River Continuity Yes The proposed scheme may have an impact on this quality element; therefore, it is scoped in for further assessment.

River Depth and Width Variation Yes The proposed scheme may have an impact on this quality element; therefore, it is scoped in for further assessment.

Structure and Substrate of the River Bed


Structure of the Riparian Zone Yes The proposed scheme may have an impact on this quality element; therefore, it is scoped in for further assessment.


4 WFD IMPACT ASSESSMENT

4.1 BASELINE CONDITIONS

WFD STATUS - SURFACE WATER

4.1.1. The WFD status the Church Brampton Arm (GB105032045380) and Brampton Branch – Lower

(GB105032045390) WFD water bodies is provided in Table 4-1 and Table 4.2 respectively.

Table 4-1 – WFD Status of the Brampton Branch – Lower potentially impacted by the

Proposed Scheme (source EA, 2020a)

Water Body ID GB105032045390

Water Body Name Brampton Branch – Lower1

Water Body Type River

Water Body Area* 35.421 km2

Hydromorphological Designation Not designated artificial or heavily modified

Overall Ecological Status Poor

Current Overall Status Poor

Status Objective (overall) Poor

Justification for not Achieving Good Status by 2015 Disproportionate burdens; No known technical solution is available


Overall Biological Quality Element Status Objective Poor

Fish Good

Invertebrates High

Macrophytes Poor


Ammonia (Phys-Chem) High

Dissolved oxygen Good

1 https://environment.data.gov.uk/catchment-planning/WaterBody/GB105032045390

https://environment.data.gov.uk/catchment-planning/WaterBody/GB105032045390



pH High

Phosphate Poor

Temperature High

Overall Physico-Chemical Quality Element Status Objective

Good by 2027

Specific pollutants High (2014)

Triclosan High (2014)

Manganese High (2014)

Copper High (2014)

Iron High (2014)

Zinc High (2014)

Chemical

Overall Chemical Status Good

Overall Chemical Quality Element Status Objective Good by 2015

Priority substances Does not require assessment

Priority hazardous substances Does not require assessment


Hydromorphology Supporting Elements Status Supports Good

Hydrological regime Supports Good

Table 4-2 - WFD Status of the Church Brampton Arm potentially impacted by the Proposed

Scheme (source EA, 2020b)


Water Body Name Church Brampton Arm2

Water Body Type River

2 https://environment.data.gov.uk/catchment-planning/WaterBody/GB105032045380




Water Body area* 29.485km2

Hydromorphological Designation Not designated artificial or heavily modified

Overall Ecological Status Moderate

Current Overall Status Moderate

Status Objective (overall) Moderate

Justification for not Achieving Good Status by 2015 No known technical solution is available


Overall Biological Quality Element Status Objective Moderate

Fish N/A

Invertebrates Good

Macrophytes Moderate


Ammonia (Phys-Chem) High

Dissolved oxygen High

pH High

Phosphate Poor

Temperature High

Overall Physico-Chemical Quality Element Status Objective

Good by 2027

Specific pollutants High (2014)

Triclosan High (2014)

Manganese High (2014)

Copper High (2014)

Iron High (2014)

Zinc High (2014)

Chemical

Overall Chemical Status Good



Overall Chemical Quality Element Status Objective Good by 2015

Priority substances Does not require assessment

Priority hazardous substances Does not require assessment


Hydromorphology Supporting Elements Status Supports Good

Hydrological regime High

WFD STATUS - GROUNDWATER

4.1.2. The Nene Mid Lower Jurassic Unit is designated as a drinking water protected area and is utilised

throughout the catchment for small local, private water supplies. The overall classification for Cycle

2 (2016) is good, with good quantitative status and good chemical status. Details are provided in

Table 4.3.

Table 4-3 - Environment Agency Classification for Nene Mid Lower Jurassic Unit

Groundwater Body (source: EA, 2020c)

Water Body Classification Nene Mid Lower Jurassic Unit (GB40502G402400)3

2016 Cycle 2 Objectives

Overall Water Body Good No known objectives to improve current status

Quantitative Good Good by 2015

Quantitative Status element Good Good by 2015

Quantitative Saline Intrusion Good Good by 2015

Quantitative Water Balance Good Good by 2015

Quantitative GWDTEs test Good Good by 2015

Quantitative Dependent Surface Water Body Status

Good Good by 2015

Chemical Good Good by 2015

Chemical Status element Good Good by 2015

3 https://environment.data.gov.uk/catchment-planning/WaterBody/GB40502G402400

https://environment.data.gov.uk/catchment-planning/WaterBody/GB40502G402400


Water Body Classification Nene Mid Lower Jurassic Unit (GB40502G402400)3

2016 Cycle 2 Objectives

Chemical Drinking Water Protected Area

Good Good by 2015

General Chemical Test Good Good by 2015

Chemical GWDTEs test Good Good by 2015

Chemical Dependent Surface Water Body Status

Good Good by 2015

Chemical Saline Intrusion Good Good by 2015

4.2 CATCHMENT CHARACTERISTICS

4.2.1. The River Nene flows in an approximately north to south direction from its source at Arbury Hill,

Northamptonshire, from a maximum elevation of 206 mAOD draining a catchment area of 233 km2.

Two unnamed tributaries of the main Nene branch are impounded by large reservoirs –

Ravensthorpe and Hollowell, and Pitsford, the latter being the most significant. A third, unnamed

tributary joins the Nene before Brampton Brook joins at SP 73478 64426. Catchment landcover is

comprised predominantly of arable farmland and grassland (54% and 29% respectively) with small

parcels of woodland (9%) and urban extent (8%) occupying the remainder.

CATCHMENT GEOLOGY AND SOILS

4.2.2. A review of the BGS Geoindex Webtool (BGS, 2020) 1:50,000 data indicates that catchment

geology is dominated Northampton Sand Formation which is comprised of sedimentary sandstone,

limestone and ironstone deposits formed approximately 170 to 174 million years ago in the Jurassic

Period. However, the river corridor is underlain with Whitby Mudstone formation deposits –

sedimentary bedrock formed approximately 174 to 183 million years ago in the Jurassic Period.

4.2.3. Superficial geology along the River Nene and Brampton Brook corridors is dominated by alluvial and

river terrace deposits. The ground investigation undertaken by WSP in May 2018 along the NWRR

Mainline found the superficial alluvial deposits to be between 2.5m and 5.3m thick. The alluvium was

predominantly described as gravelly clay or clayey gravel with layers of sand also present.

4.2.4. The ground investigation undertaken by WSP in January 2019 to the north of the railway in the

vicinity of the flood storage replacement areas revealed the superficial alluvial deposits to be

between 1.7m and 4m in thick. The alluvium was predominantly composed of sand or sandy clay,

becoming more clayey with depth (usually below 2.5m below ground level (BGL)), and often a

gravelly layer is encountered at base of the alluvium.

4.2.5. This ground investigation also focussed on the area to the south of the railway in the vicinity of the

highway balancing ponds. Again, alluvium was encountered, ranging between 1m and 5.7m thick,

thickest in the southern part of the Proposed Scheme. The composition of the alluvium varied

between gravelly sand, gravelly clay, clayey sand or sandy clay occasionally underlain by clayey

gravel below which the weathered bedrock was encountered.


CATCHMENT HYDROLOGY

4.2.6. Catchment hydrology is defined by low rainfall within the catchment, with annual average values for

the periods 1941-1970 and 1961-1990 of 642mm and 648mm respectively. The flow regime of the

main river Nene is influenced by three reservoirs that attenuate flow and ultimately disrupt the

natural hydrological regime. Brampton Brook, however, presently exhibits a fairly natural flow

regime, through there are a number of existing culverts that probably influence flows. Flow within the

River Nene is also influenced by insurgence of groundwater that originates from the Nene Mid

Lower Jurassic Unit groundwater body that underlies the scheme. The Base Flow Index (BFI) for the

catchment is 0.58 indicating moderate groundwater influence.

HISTORICAL CHANNEL CHANGE

4.2.7. Comparative analysis of the historic and contemporary mapping records reveals that the River Nene

and Brampton Brook, local to the proposed site of works, have largely remained morphologically

stable since the mid-19th Century. This, however, is not necessarily reflective of the natural

geomorphic character of the system, and instead suggests that anthropogenic influences on the

surface hydrological networks have existed since before formal mapping survey was undertaken.

Both watercourses have been profoundly modified from their original planform – which probably

consisted of a network of interconnected, sinuous channels – into a homogenous, single-thread

channel system. Nevertheless, both historic and contemporary maps of the area show discrete

reaches of channel, that have been less intrusively impacted by anthropogenic pressures and thus

provide a glimpse of the natural planform of the local river network – particularly the River Nene. In

addition, land adjacent to the River Nene displays evidence of former channels and paleo-

meanders, manifested as scars on the floodplain. Such areas, too, have not changed significantly in

the intervening decades since the earliest available Ordnance Survey data; thus, the morphology of

the system may be classed as a passively meandering, or slow anastomosing.

4.3 RHS RESULTS AND BASELINE CHARACTERISTICS AGAINST WFD

SURFACE WATER QUALITY ELEMENTS

BIOLOGICAL QUALITY ELEMENTS

River Habitat Survey

River Nene

4.3.1. A summary of the RHS indices produced for the River Nene are presented in


4.3.2. Table 4-4.

4.3.3. The HMS scores for the River Nene place the site into HMS Class 5 (Severely Modified). The HMS

sub-scores which scored highly in the calculation are; the HMS Resectioned Bank Bed sub-score,

HMS Realigned sub-score and HMS Bridges sub-score.

4.3.4. A baseline HQA class was not able to be calculated indicating that there are no comparable

reference sites for the River Nene.


Table 4-4 – RHS indices for the River Nene

Site Survey Reach HMS Score HMS Class

River Nene

Downstream Extent: SP 73385 64868

Upstream Extent: SP 73441 65326

3210 5

4.3.5. The survey of the River Nene identified one riffle and two pools within the 500m stretch, with the

channel exhibiting a shallow vee form which was obviously realigned and over-deepened for more

than 30% of the survey section.

4.3.6. The plant community visible along the survey section included; emergent broad-leaved herbs,

emergent reeds/sedges/rushes/grasses/horsetails, amphibious species, submerged broad-leaved,

submerged fine-leaved and filamentous algae. Elodea (waterweed) was observed in the mid-

channel.

4.3.7. No features of species interest were noted during the survey along the River Nene.

Brampton Brook

4.3.8. The survey of Brampton Brook identified one riffle within the stretch of watercourse surveyed. The

channel exhibited a shall vee form which was over-deepened, over-widened and had undergone

realignment.

4.3.9. The plant community visible along the survey section included; liverworts/mosses/lichens, emergent

reeds/sedges/rushes/grasses/horsetails and amphibious species. The invasive non-native species

Himalayan balsam Impatiens glandulifera was observed during the survey.

4.3.10. Sections of Brampton Brook were inaccessible along the survey stretch. Consequently, it was not

possible to calculate RHS indices for this watercourse.


Fish

River Nene

4.3.11. A total of seven fish species were caught during a 3-run survey of a 87m long section. The fish

species caught included dace Leuciscus leuciscus, pike Esox lucius, roach Rutilus rutilus and

gudgeon Gobio gobio, with gudgeon being the most abundant species recorded (Table 4-5).

4.3.12. The minor species sampled consisted of bullhead, stone loach and minnow.

Table 4-5 – Numbers of fish caught on 06/06/2019 during a 3-run electric fishing survey of the

River Nene

Species Latin name Run 1 Run 2 Run 3 Total

Gudgeon Gobio gobio 22 3 2 27

Dace Leuciscus leuciscus 11 3 3 17

Roach Rutilus rutilus 1 1 0 2

Pike Esox lucius 1 0 0 1

Bullhead* Cottus gobio - - - -

Stone loach* Barbatula barbatula - - - -

Minnow* Gasterosteus aculeatus - - - -

Total 35 7 5 47

*minor species which were caught but not counted or measured in accordance with Environment Agency electric fishing

methods.

4.3.13. The expected numbers of dace and gudgeon caught for each sampling run, as predicted by Carle

and Strub method, is a good fit to the survey data. This would indicate that the Carle and Strub

method is likely to provide a reliable estimation of the population size.

4.3.14. The estimated population size of gudgeon within the 87m long survey section was 18 (SE = 1.40)

with lower and upper 95% confidence intervals of 17 and 21 respectively (Table 4-6). The density of

gudgeon per m2 was estimated to be 0.20.

4.3.15. The estimated population size of dace within the 87m long survey section was 28 (SE = 1.80) with

lower and upper 95% confidence intervals of 27 and 32 respectively (Table 4-6). The density of dace

per m2 was estimated to be 0.30.

4.3.16. The probability of an individual gudgeon being caught during each sampling run was 0.70 and the

probability of an individual dace being caught during each sampling run was 0.6 (Table 4-6). These

both exceed 0.40, the rate of sampling efficiency required to give a robust estimate of population

size (Stewart et al., 2019).


Table 4-6 – Gudgeon Gobio gobio and dace Leuciscus leuciscus population and density

estimates for the River Nene, calculated using the Carle and Strub method. The probability of

an individual fish being captured during each sampling run, along with the standard error

and lower and upper confidence intervals of the population estimate are also displayed

Carle and Strub method output Gudgeon Dace

Probability of capture 0.7 0.6

Estimated population 28 18

Standard error 1.8 1.4

Lower 95% confidence interval 27 17

Upper 95% confidence interval 32 21

Estimated number of fish per m2 0.3 0.2

Brampton Brook

4.3.17. A total of four fish were caught during a 3-run survey of a 97m long section of Brampton Brook

consisting of three stone loach and one bullhead (Table 4-7).


Brampton Brook, presented in order of abundance

Species Sample 1 Sample 2 Sample 3 Total

Stone loach 2 1 0 3

Bullhead 1 0 0 1

Total 0 0 0 0

Aquatic macroinvertebrates

River Nene

4.3.18. River Invertebrate Classification Tool analysis was performed to produce WFD status classifications

for macroinvertebrates for both River Nene survey locations (Table 4-8).

4.3.19. The data indicates that the macroinvertebrate assemblages within the River Nene are not adversely

affected by stressors such as pollution, flow pressures and anthropogenic activities. This is reflected

in the WHPT NTAXA and WHPT ASPT EQR scores, which were only slightly below expected

reference conditions.


4.3.20. The River Nene achieved overall High status upstream of the proposed crossing point and Good

downstream. Despite both sites failing to meet an expected number of 26 WHPT scoring taxa, the

EQR values both achieved High status. The ASPT score is the limiting factor for the downstream

site achieving High status (5.45 compared to an expected 5.77) lowering the EQR value.

Table 4-8 – RICT WHPT classifications of survey locations at River Nene

Site Index Score EQR Class Confidence of Class (%)

Overall classification

River Nene - Upstream

WHPT-APST

5.64 0.97 High 47.82

High WHPT-NTAXA

19 0.80 High 48.90

River Nene -Downstream

WHPT-APST

5.45 0.94 Good 56.28

Good WHPT-NTAXA

21 0.88 High 73.76

Brampton Brook

4.3.21. River Invertebrate Classification Tool analysis was performed to produce WFD status classifications

for macroinvertebrates for both Brampton Brook survey locations (Table 4-9).

4.3.22. The biological metrics downstream in Brampton Brook indicate that the macroinvertebrate

community is negatively affected by stressors, and this reflected in the WHPT ASPT EQR score.

4.3.23. Brampton Brook achieved overall Good status upstream of the proposed crossing point and

Moderate downstream. The downstream site supported a higher number of WHPT scoring taxa

however failed to meet the expected ASPT score for this site (5.32 compared to 6.38) resulting in a

lower EQR value. Both the upstream and downstream sites either met or exceeded the expected

number of taxa for a watercourse of this habitat type resulting in High classification for this metric.

Table 4-9 – RICT WHPT classifications of survey locations at River Nene and Brampton

Brook



Brampton Brook -Upstream

WHPT-APST

5.43 0.86 Good 48.56

Good WHPT-NTAXA

21 1.09 High 97.26

WHPT-APST

5,32 0.83 Moderate 67.31 Moderate




Brampton Brook - Downstream

WHPT-NTAXA

22 1.18 High 99.32

PHYSICO-CHEMICAL QUALITY ELEMENTS

4.3.24. No specific baseline data on the physico-chemical quality elements has been gathered, nor is

available at the time of writing; however, Tables 4.1 and 4.2 summarise the current status of each

quality element for the Brampton Branch – Lower and Church Brampton Arm respectively.

Nevertheless, potential impacts to each element have been assessed in Table 4.11 and Table 4.12.

HYDROMORPHOLOGICAL QUALITY ELEMENTS

Quantity and Dynamics of Flow

River Nene

4.3.25. The quantity and dynamics of flow within the River Nene appear to be suppressed both by the

extensive management of the river local to the proposed site of works (e.g. channel straightening

and consolidation a multi-thread anastomosing system, into a single thread channel), but also

catchment-wide pressures; for example the large reservoirs that attenuate flow and sediment and

agricultural development and local land-use which comprises of improved grassland. Consequently,

there is a lack of diverse flow patterns and hydraulic complexity within the River Nene, with glide and

ponded water dominating flow structure within a grossly over-depended channel.

Brampton Brook

4.3.26. Brampton Brook is similarly profoundly altered from its natural form, having been extensively

straightened throughout most of its length: the brook flows through Brampton Heath Golf Course

where it is especially modified. Consequently, the flow in the Brampton Brook is higher than would

be expected, due to a significant proportion of its length having been removed through channel

straightening and consolidation to a single channel.


River Nene and Brampton Brook

4.3.27. Groundwater was encountered in the superficial deposits during a Ground Investigation carried out

by WSP. In the proposed flood storage replacement areas the groundwater was found to be

between 1.4mBGL and 2.9mBGL. In the vicinity of the proposed highway balancing ponds the

groundwater level in the superficial deposits was encountered at between 1mBGL and 3mBGL.

Groundwater was also encountered in the underlying sandstone at 2.8mBGL and 3.9mBGL in this

area.

4.3.28. The monitoring data indicate groundwater levels between 0.95mBGL -1.38mBGL in the Whitby

Mudstone Formation. The measured water levels from the deeper borehole installations indicate

groundwater at approximately 3.7mBGL - 3.9mBGL in the sandstone. The shallower borehole

installation was dry and did not record groundwater. Data indicate the groundwater level at

approximately 1mBGL in the alluvium.


4.3.29. Given the shallow groundwater levels, it is expected that the baseflow of the surface water bodies is

in high connectivity with the groundwater body. Available groundwater level data are insufficient to

describe groundwater flow directions and horizontal and vertical hydraulic gradients. It is considered

likely that the superficial deposits and bedrock aquifers are in hydraulic continuity, and groundwater

flow direction being generally towards the river.

River Continuity

River Nene

4.3.30. Continuity within the River Nene is disrupted both longitudinally and laterally. There are a number of

existing in-channel structures along the length of the Nene, in addition to foot, road and rail bridges,

old mills and mill leats, all of which disrupt the natural flow and sediment transport dynamics through

the system. As previously described, the river has been profoundly altered through a wide range of

anthropogenic pressures at varying temporal and spatial scales. The floodplain bears the scars of

the river system’s natural form, alluding to the natural, anastomosed style of river. The channel has

since been confined predominantly to a single channel with significantly reduced sinuosity (though

some bifurcated sections remain). Extensive channel straightening has resulted in an over-deep

river system that does not connect with its floodplain as frequently as it would under natural

conditions.

Brampton Brook

4.3.31. Longitudinal and lateral connectivity are also significantly disrupted within Brampton Brook.

Extensive channel straightening has similarly resulted in a grossly over-deep channel that does not

connect with its floodplain as frequently as it would under natural conditions. The process of channel

straightening appears to be particularly evident at the downstream section of the brook, with steep,

near-vertical banks that are susceptible to gravitational erosion processes.

River Depth and Width Variation

River Nene

4.3.32. Width and depth variation within the River Nene appear to be limited, again owing to the significantly

modified condition of the channel. Alternating sediment berms create some variation in width. Depth

variation is difficult to assess based on the available information at the time of writing; however, it is

likely that natural depth variation has similarly been repressed by a long history of river management

practices.

Brampton Brook

4.3.33. Brampton Brook is similarly very limited in width and depth variation. The straight, over-deep

character of the river creates an extremely homogeneous riverine habitat composition. Depth is also

difficult to gauge based on the available information at the time of writing, but there appears to be

little natural variation.


River Nene

4.3.34. It is not possible to make a detailed assessment of the river bed characteristics of the River Nene

based on the information that is available at the time of writing. However, the superficial geology

record, in addition to the passively meandering style of river and its setting within the lowland areas


of the catchment suggest that the natural substrate is comprised of sands and small to medium

gravels.

Brampton Brook

4.3.35. Similarly, the bed character of Brampton Brook cannot be ascertained in the absence of geomorphic

appraisal. Anecdotal evidence suggests the substrate composition is coarser than the River Nene;

however, this could be a symptom of persistently high velocity resulting from the near-perfectly

straight channel winnowing out smaller particles. This will be considered at the detailed design

phase.

Structure of the Riparian Zone

River Nene

4.3.36. The structure of the riparian zone appears to be homogenous and largely devoid of good quality

riparian habitat. Again, this is probably a result of historical land management practices destroying

habitat. There are, however, small clusters of deciduous trees that offer occasional riparian habitat

and cover for fish; in addition to the previously mentioned sediment berms, which, owing to frequent

inundation, support a range of vegetation and thus animal species.

Brampton Brook

4.3.37. Brampton Brook is similarly devoid of riparian habitat. The reach through Brampton Heath gold

course is especially degraded; however, the over-deep nature of the channel probably means that

any riparian habitat is very low functioning.

4.4 IMPACT ASSESSMENT

STEP 1: POTENTIAL GENERIC OPERATIONAL IMPACTS OF THE PROPOSED

SCHEME ON WFD QUALITY ELEMENTS

4.4.1. Potential pressures and impacts of the Proposed Scheme have been identified along with

embedded mitigation measures and are presented in Table 4-10. The proposed mitigation thus

forms the basis of this assessment.

Table 4-10 – Pressures, potential impacts and associated mitigation for works to the

impacted watercourses and downstream water bodies (Source: Annex IV: Flood Risk

Management, UKTAG, 2008)

Pressure Sub-pressures

Potential Impacts Mitigation Measures

Online Structures

Brampton Brook Crossing

Bridge crossing

Outfalls

Loss of morphological diversity and habitat.

Hard protection and associated impacts.

Impediment to fish/mammal passage and ecological connectivity.

Loss of aquatic, marginal and riparian habitat.

The Brampton Brook crossing would have, a natural bed and abutments set back from the bank top. Hard protection would be constructed from natural material where possible. Plunge pools would be incorporated at culvert outlets to limit scour, dissipate energy and maintain channel stability. Riparian and aquatic habitat would be replaced and compensated.


Pressure Sub-pressures

Potential Impacts Mitigation Measures

Initiation of geomorphic response Bridge scour protection would be designed sympathetically to natural processes.

Channel modification

Ordinary watercourse diversion

Loss of morphological diversity

Reduction/increase in channel length

Loss of aquatic, marginal and riparian habitat

The realigned channel would have a variety of desirable features incorporated into its design using existing features as a template for its design. Appropriate channel length would be achieved through a sinuous design. This would control the gradient of the channel and further promote hydraulic variability. The channel would be seeded with an appropriate seed mix to create a varied riparian zone.

Floodplain alteration

Flood embankment

Loss of floodplain habitat

Creation of floodplain habitat and wetland

Water quality

Road drainage Fish and invertebrate mortality through fine sediment release and introduction of harmful compounds.

Sustainable Drainage Systems (SuDS) would remove harmful silts and compounds derived from highway drainage and prevent them from entering the local surface water and ground water bodies.

Vegetation clearing

Loss of riparian and floodplain habitat

Loss of marginal and riparian habitat. Loss of floodplain habitat functioning

Riparian vegetation and trees would be replaced elsewhere through compensatory habitat creation. Green engineering approaches would be sought where river banks could be left susceptible to erosion.

STEP 2: SITE SPECIFIC ASSESSMENT OF THE PROPOSED SCHEME AGAINST WFD

QUALITY ELEMENTS

The site-specific impacts of the Proposed Scheme on the biological, physico-chemical and

hydromorphological quality elements of the water bodies are provided in Table 4.11 and Table 4.12.


Table 4-11 – Operational impacts on the WFD quality elements on the Brampton Branch – Lower (GB105032045390) water body.

Activities that are not expected to have an adverse impact on each quality element receptor are omitted

Quality Element Potential Impact Mitigation

Water body ID GB105032045390

Water body name Brampton Branch – Lower


Composition and Abundance of Benthic Invertebrate Fauna

Bridge crossing Bridge abutments and bed scour protection measures have the potential to impact on river flow dynamics, substrate and river bed, the proposed development may therefore lead to localised change in the nature of the benthic invertebrate habitat brought about by the bridge structure. Outfalls Acute introduction of contaminated road run-off (metals, oils, road salt) after heavy rainfall events could cause mortality of pollution sensitive species. Prolonged introduction of these substances may reduce future potential for invertebrate diversity. Potential increase in fine sediment loads due to scour of bed and banks following outfall installation and operation. This may impact also upon water quality. These impacts may affect benthic invertebrate fauna habitat.

Bridge crossing Riparian habitat creation would be implemented elsewhere to offset the loss of invertebrate habitat at the proposed bridge structure location. The bridge abutments will be set back from the bank tops to avoid flow constriction and knock-on adverse effects. Outfalls Embedded mitigation within the design of the outfalls would ensure water quality standards are met. The HEWRAT assessment conducted by WSP demonstrates a sufficient reduction in key pollutants so as not to adversely impact upon water quality within the River Nene. The incorporation of filter drains and detention basins would ensure compliance with WFD water quality objectives, where the HEWRAT assessment identified that mitigation was required to manage the risk of sediment bound pollutants and solutes. In addition, spillage risk assessment calculated that the probability of a spillage event with the potential to pollute watercourses occurring was to an acceptable level across the scheme (<0.5% for each outfall). Outfalls would be designed to control the risk of scour to the bed and banks, thus preventing the increase in fine sediment load and associated pollutants.



Ordinary watercourse diversion Loss of morphological diversity and habitat. Changes to the flow regime as a result of the proposed channel diversion could result in the loss of substrates and sediments that are important for invertebrates. Vegetation clearance The removal of trees along the banks of the River Nene

could lead to a reduction in the deposition of organic

matter into the channel, therefore, reducing food supply

for a range of macroinvertebrate species. Channel

shading also provides shelter from predators. Additional

light penetration may encourage macrophyte growth in

the channel.

Ordinary watercourse diversion The channel diversion would be designed to mimic natural habitat form and function. In addition, the channel diversion has been included to avoid a culvert structure through the proposed flood embankment, which would have degraded habitat within the ordinary watercourse. Vegetation clearance Trees and plants would be compensated elsewhere. Riparian planting would be implemented to offset the loss of cover habitat to invertebrates.

Composition, Abundance and Age Structure of Fish Fauna

Bridge crossing Bridge abutments have the potential to impact on river flow dynamics, substrate and river bed, the proposed development may therefore impact to fish movement and behaviour. Outfalls Acute or prolonged introduction of contaminated road run-off (metals, oils, road salt) has potential to reduce water quality for fish. Potential increase in fine sediment loads due to scour of bed and banks following outfall installation and operation. This may impact also upon water quality. These impacts may affect fish habitat.

Bridge crossing The bridge abutments would be set back from the channel’s top of banks. In addition, the expected impacts of the bridge would therefore be offset through habitat creation elsewhere within the redline boundary, as near to the region of lost habitat as practicable. Outfalls Embedded mitigation within the design of the outfalls would ensure water quality standards are met. The HEWRAT assessment conducted by WSP demonstrates a sufficient reduction in key pollutants so as not to adversely impact upon water quality within the River Nene. The incorporation of filter drains and detention basins would ensure compliance with WFD water quality objectives, where the HEWRAT assessment identified that mitigation was required to manage the risk of sediment bound pollutants and solutes. In addition, spillage risk assessment calculated that the probability of a spillage event with the potential to pollute watercourses occurring was to an acceptable level across the scheme (<0.5% for each outfall).



Ordinary watercourse diversion Loss of morphological diversity and habitat. Changes to the flow regime as a result of the proposed channel diversion could result in the loss of substrates and sediments that are important for juvenile fish Vegetation clearance The removal of trees along the banks of the River Nene

could lead to a reduction in cover for fish from predation.

Tree removal could result in greater light penetration and

encourage macrophyte growth.

Outfalls would be designed to control the risk of scour to the bed and banks, thus preventing the increase in fine sediment load and associated pollutants. Ordinary watercourse diversion The channel diversion would be designed to mimic natural habitat form and function. In addition, the channel diversion has been included to avoid a culvert structure through the proposed flood embankment, which would have degraded habitat within the ordinary watercourse. Vegetation clearance Trees and plants would be compensated elsewhere. Riparian planting would be implemented to offset the loss of cover habitat to fish.

Physico-Chemical Quality Elements

Thermal Conditions Outfalls There is potential for an increase in biochemical oxygen demand as a result of increased road run-off entering the River Nene. The potential for additional sediment load due to the risk of scour of the bed and banks may also alter oxygenation conditions.

Outfalls Embedded mitigation within the design of the outfalls would ensure water quality standards are met. The HEWRAT assessment conducted by WSP demonstrates a sufficient reduction in key pollutants so as not to adversely impact upon water quality within the River Nene. The incorporation of filter drains and detention basins would ensure compliance with WFD water quality objectives, where the HEWRAT assessment identified that mitigation was required to manage the risk of sediment bound pollutants and solutes. In addition, spillage risk assessment calculated that the probability of a spillage event with the potential to pollute watercourses occurring was to an acceptable level across the scheme (<0.5% for each outfall). Outfalls would be designed to control the risk of scour to the bed and banks, thus preventing the increase in fine sediment load and associated pollutants



Vegetation clearance The removal of trees along the banks of the River Nene could lead to a temporary reduction in channel shading; potentially resulting in an increase in water temperature during summer months. Impacts are likely to be localised.

Vegetation clearance Riparian planting would be implemented to provide cover to aquatic organisms. Plug plants would be used where possible to have an instant positive impact. Wider tree planting would also be implemented replacing those lost during construction with native species.

Oxygenation Conditions

Bridge crossing Increased fine sediment and road runoff pollution could adversely impact upon the oxygenation conditions local to the proposed site of works. In addition, shading from the proposed bridge would likely limit plant growth, which could have knock-on effects and influence diurnal variation in oxygen levels. Outfalls There is potential for an increase in biochemical oxygen demand as a result of increased road run-off entering the River Nene. The potential for additional sediment load due to the risk of scour of the bed and banks may also alter oxygenation conditions. Vegetation clearance Loss of channel shading may result in local increases in temperature which may, in turn, affect oxygen levels.

Bridge crossing Inclusion of drainage balancing ponds and filter drains would reduce the impacts on oxygenation conditions within the River Nene. Outfalls Embedded mitigation within the design of the outfalls would ensure water quality standards are met. The HEWRAT assessment conducted by WSP demonstrates a sufficient reduction in key pollutants so as not to adversely impact upon water quality within the River Nene. The incorporation of filter drains and detention basins would ensure compliance with WFD water quality objectives, where the HEWRAT assessment identified that mitigation was required to manage the risk of sediment bound pollutants and solutes. In addition, spillage risk assessment calculated that the probability of a spillage event with the potential to pollute watercourses occurring was to an acceptable level across the scheme (<0.5% for each outfall). Outfalls would be designed to control the risk of scour to the bed and banks, thus preventing the increase in fine sediment load and associated pollutants Vegetation clearance Riparian planting would be implemented to provide cover to aquatic organisms and provide shading. Plug plants would be



used where possible to have an instant positive impact. Wider tree planting would also be implemented replacing those lost during construction with native species.

Salinity Bridge crossing There is potential for an increase in salinity as a result of salt used on the road in winter. Outfalls There is potential for an increase in salinity as a result of salt used on the road in winter.

Bridge crossing Inclusion of drainage balancing ponds and filter drains would reduce the impacts on increased salinity within the River Nene. Outfalls Embedded mitigation within the design of the outfalls would ensure water quality standards are met. The HEWRAT assessment conducted by WSP demonstrates a sufficient reduction in key pollutants so as not to adversely impact upon water quality within the River Nene. The incorporation of filter drains and detention basins would ensure compliance with WFD water quality objectives, where the HEWRAT assessment identified that mitigation was required to manage the risk of sediment bound pollutants and solutes. In addition, spillage risk assessment calculated that the probability of a spillage event with the potential to pollute watercourses occurring was to an acceptable level across the scheme (<0.5% for each outfall). Outfalls would be designed to control the risk of scour to the bed and banks, thus preventing the increase in fine sediment load and associated pollutants.

Nutrient Conditions Bridge crossing Increased fine sediment input from the road may adversely impact upon the nutrient conditions locally. Outfalls There is potential for an increase in ammonia and nitrates as a result of increased road run-off entering the River Nene.

Bridge crossing Inclusion of drainage balancing ponds and filter drains would reduce the impacts on nutrient conditions within the River Nene Outfalls Embedded mitigation within the design of the outfalls would ensure water quality standards are met. The HEWRAT assessment conducted by WSP demonstrates a sufficient reduction in key pollutants so as not to adversely impact upon water quality within the River Nene. The incorporation of filter drains and detention basins would ensure compliance with WFD water quality objectives, where the HEWRAT assessment



identified that mitigation was required to manage the risk of sediment bound pollutants and solutes. In addition, spillage risk assessment calculated that the probability of a spillage event with the potential to pollute watercourses occurring was to an acceptable level across the scheme (<0.5% for each outfall). Outfalls would be designed to control the risk of scour to the bed and banks, thus preventing the increase in fine sediment load and associated pollutants.



Bridge crossing Bridge abutments can impart a constriction effect on flow which can lead to bed scour and bank erosion up/downstream of the structure. Outfalls The proposed outfalls may initiate bed scour downstream and would discharge drainage water, thereby

having the potential to impact upon the watercourse

quantity and dynamics of flow within the River Nene. Flood embankment The embankment could constrict flow and increase velocity at out-of-bank flow events; however, impacts are expected to be negligible. This will be confirmed at the detailed design phase through geomorphological appraisal. Ordinary watercourse diversion Loss of morphological diversity and habitat. Changes to the flow regime as a result of the proposed channel diversion could result in the loss of hydraulic complexity associated with high functioning aquatic habitat.

Bridge crossing Appropriate bed scour protection will be designed at the detail design phase with input from geomorphologists to ensure no local adverse impacts on sediment transport and erosional and depositional processes. Outfalls Sufficient scour protection (scour pools and protected bed and

banks) would be incorporated into the outfall structure in order

to mitigate potential scour. Discharge from the outfalls would be

at equivalent greenfield runoff rates. Flood embankment None required. Ordinary watercourse diversion The channel diversion would be designed to mimic natural habitat form and function. In addition, the channel diversion has been included to avoid a culvert structure through the proposed flood embankment, which would have degraded habitat within the ordinary watercourse. The specific design of the channel



Vegetation clearance Loss of vegetation could lead to localised bank erosion, the product of which could lead to excessive deposition and geomorphic response elsewhere, leading ultimately to an impact on the quantity and dynamics of flow.

diversion will be informed by a geomorphology walkover survey at the detailed design phase to identify the habitat template upon which the channel design will be based. Vegetation clearance Vegetation would be compensated with habitat creation and riparian planting elsewhere.


Bridge crossing Construction of sheet piling along the banks and bed scour protection could limit groundwater connectivity locally.

Bridge crossing There is no opportunity to use alternative bridge scour protection construction methods, therefore riparian habitat improvements would be developed elsewhere. The scour protection would be designed as a porous layer to ensure no loss in groundwater connectivity. This will be undertaken at the detailed design phase.

River Continuity Bridge crossing Construction abutments could eliminate lateral connectivity locally. Improper construction of scour protection could also limit longitudinal connectivity in terms of sediment transport processes. Outfalls Outfalls may limit lateral connectivity locally. Longitudinal connectivity may also be disrupted at higher flows, albeit locally. Flood embankment The flood embankment may constrict flow at higher out-of-bank flows, thereby limiting longitudinal and lateral connectivity across the floodplain.

Bridge crossing The bridge abutments would be constructed around 6m back from the bank tops. However, riparian habitat improvements would be developed elsewhere in the redline boundary. The bed scour protection would be designed accordingly to avoid impacts to sediment transport processes. This will be undertaken at the detailed design phase. Outfalls Outfalls would be designed using best practice: i.e., avoidance of protrusion of the structure; setting back of the outfall if possible, use of green engineering to limit scour and erosion. Flood embankment The flood embankment has been set back from the bank top as far as possible (>8m). The impacts of the flood embankment will be assessed through geomorphological appraisal at the detailed



Ordinary watercourse diversion Improper design of the watercourse diversion could lead to loss of longitudinal and lateral connectivity. Vegetation clearance Loss of riparian vegetation would reduce floodplain roughness and potentially promote greater flow conveyance across the floodplain and within the channel.

design phase; however, impacts could be offset through floodplain habitat creation. Ordinary watercourse diversion The channel diversion would be designed to mimic natural habitat form and function. In addition, the channel diversion has been included to avoid a culvert structure through the proposed flood embankment, which would have degraded habitat within the ordinary watercourse. The specific design of the channel diversion will be informed by a geomorphology walkover survey at the detailed design phase to identify the habitat template upon which the channel design would be based. Vegetation clearance Vegetation would be compensated with habitat creation and riparian planting elsewhere.

River Depth and Width Variation

Bridge crossing The bridge’s sheet-piled banks would be set at the same width as the current channel; however, the banks would be replaced completely with hard engineering. In addition, general scour may lead degradation of the bed. Outfalls River bank and bed scour could result from improper design of the outfall, which, in turn, could lead to geomorphic responses such as accelerate bank erosion and bed scour. Ordinary watercourse diversion

Bridge crossing The bed scour protection would be designed accordingly to avoid impacts to sediment transport processes. This will be undertaken at the detailed design phase. Riparian habitat improvements would be implemented to offset the loss of river bank. Outfalls Sufficient scour protection (scour pools and protected bed and banks) would be incorporated into the outfall structure in order to mitigate potential scour and erosion. The outfall would be designed using best practice such as avoiding structure protrusion, appropriate alignment and use of green engineering where possible. Ordinary watercourse diversion



Loss of morphological diversity and width and depth variation. Vegetation clearance Removal of riparian and bankside vegetation could leave river banks susceptible to erosion, which, in turn could lead to accelerated geomorphic adjustment.

The channel diversion would be designed to mimic natural habitat form and function. In addition, the channel diversion has been included to avoid a culvert structure through the proposed flood embankment, which would have degraded habitat within the ordinary watercourse. The specific design of the channel diversion would be informed by a geomorphology walkover survey at the detailed design phase to identify the habitat template upon which the channel design would be based. Vegetation clearance Vegetation will be compensated with habitat creation and riparian planting elsewhere. Where vegetation is removed and unable to be replaced, appropriate bank erosion protection would be


Bridge crossing Flow constriction could lead to bed scour and thus alter the substrate composition and character. Outfalls The proposed outfalls may initiate bed and bank scour around and downstream of the structure, thereby having the potential to increase fine sediment load within the channel and increase silt both within the River Nene and downstream receiving water bodies. Flood embankment The embankment could constrict flow and increase velocity at out-of-bank flow events. Substrate sampling has not been undertaken at the time of writing to confirm the size

Bridge crossing Appropriately designed scour protection will be developed at the detailed design phase with input from geomorphologists to ensure geomorphic processes are not adversely impacted. The protection will be designed to avoid protrusion above existing bed level and impeding sediment transport. The scour protection engineering will be overlain with natural bed material. Outfalls Sufficient scour protection (scour pools and protected bed and banks) would be incorporated into the outfall structure in order to mitigate potential scour, thereby mitigating the risk of increased fine sediment load. Flood embankment Floodplain wetland habitat creation would be developed at the detail design phase.



calibre and therefore shear strength of local bed material; however, impacts are expected to be negligible. This will be confirmed at the detailed design phase through geomorphological appraisal. Ordinary watercourse diversion Improper design of the watercourse diversion could lead to loss of morphological diversity and degradation of the structure of the river bed. Vegetation clearance Removal of riparian and bankside vegetation could leave river banks susceptible to erosion, which, in turn could lead to accelerated geomorphic adjustment, the result of which could be fine sediment accumulation on the channel bed.

Ordinary watercourse diversion The channel diversion would be designed to mimic natural habitat form and function. In addition, the channel diversion has been included to avoid a culvert structure through the proposed flood embankment, which would have degraded habitat within the ordinary watercourse. The specific design of the channel diversion would be informed by a geomorphology walkover survey at the detailed design phase to identify the habitat template upon which the channel design would be based. Vegetation clearance Vegetation will be compensated with habitat creation and riparian planting elsewhere. Where vegetation is removed and unable to be replaced, appropriate bank erosion protection would be implemented using green engineering approaches where practicable.

Structure of the Riparian Zone

Bridge crossing Loss of riparian habitat through construction of hard engineered banks. Outfalls Loss of riparian habitat through construction of the outfall.

Bridge crossing Riparian planting and habitat creation would be implemented elsewhere along the River Nene to compensate the loss of habitat at the bridge crossing location. This would be implemented within the redline boundary and as close to the lost habitat as practicable. Outfalls Riparian planting and habitat creation would be implemented elsewhere along the River Nene to compensate the loss of habitat at the outfall location.



Ordinary watercourse diversion Improper design of the watercourse diversion could lead to loss of morphological diversity and degradation of the structure of the riparian zone. Vegetation clearance Removal of vegetation could potentially destroy rare instances of riparian habitat, which, at present is largely degraded along the study reach.

Ordinary watercourse diversion The channel diversion would be designed to mimic natural habitat form and function. In addition, the channel diversion has been included to avoid a culvert structure through the proposed flood embankment, which would have degraded habitat within the ordinary watercourse. The specific design of the channel diversion would be informed by a geomorphology walkover survey at the detailed design phase to identify the habitat template upon which the channel design would be based Vegetation clearance Vegetation will be compensated with habitat creation and riparian planting elsewhere. Where vegetation is removed and unable to be replaced, appropriate bank erosion protection would be implemented using green engineering approaches where practicable.


Table 4-12 - Operational impacts on the WFD quality elements on the Church Brampton Arm (GB105032045380) water body


Water body ID GB105032045380

Water body name Church Brampton Arm


Composition and Abundance of Benthic Invertebrate Fauna

Brampton Brook crossing The installation of a crossing would result in the direct mortality of invertebrates, and the loss of morphological diversity and habitat.

Brampton Brook crossing The crossing would be designed using best practice with retention of the natural bed and banks to ensure gravels are retained, a low flow channel to ensure ecological connectivity, and sufficient conveyance capacity to avoid surcharging.

Composition, Abundance and Age Structure of Fish Fauna

Brampton Brook crossing The proposed crossing would have a significant impact upon the fish communities present in Brampton Brook. Potential for loss of biological continuity resulting in interference with fish population movements and blocking the exchange of individuals among populations, reducing gene flow and disrupting the ability of "source" populations to support declining populations nearby.

Brampton Brook crossing The crossing would be designed using best practice with retention of the natural bed and banks to ensure gravels are retained, a low flow channel to ensure ecological connectivity, and sufficient conveyance capacity to avoid surcharging. The proposed crossing would also be designed to facilitate successful fish passage and include adequate swimming space, adequate depth of water, appropriate water velocity, and no physical or behavioural barriers.

Physico-Chemical Quality Elements

Thermal Conditions No anticipated impacts None required

Oxygenation Conditions No anticipated impacts None required

Salinity No anticipated impacts None required

Acidification Status No anticipated impacts None required

Nutrient Conditions No anticipated impacts None required





Brampton Brook crossing The proposed crossing would have a significant impact upon the quantity and dynamics of flow within Barrow Brook, through increased velocity and surcharging during high flow events, which would have implications for sediment transport processes, and adversely impact upon ecological connectivity; e.g., fish passage.

Brampton Brook crossing The crossing would be sized so as not to surcharge during the design flood events. This includes both sufficient structure diameter and gradient, a depressed invert and natural substrate and banks.


Brampton Brook crossing The crossing could disconnect the Brampton Brook from the underlying groundwater body as it passes through enclosed concrete structure.

Brampton Brook crossing The crossing would be design with a 500mm natural bed to allow for interactions with groundwater and mimic where practicable natural processes.

River Continuity Brampton Brook crossing The proposed crossing would severely impact upon river continuity within Brampton Brook. Lateral connectivity within low structures is completely lost as open channel flow is replaced by a closed system. This has implications for longitudinal connectivity, as surcharging during high flow events would likely result in sediments being flushed through the system at an unnatural rate due to increased gradient and velocity.

Brampton Brook crossing The crossing would be sized so as not to surcharge during the design flood event. This includes both sufficient structure diameter and gradient, a depressed invert and natural substrate and banks. Lateral connectivity would be improved downstream of the structure to compensate the loss of lateral interaction processes.

River Depth and Width Variation Brampton Brook crossing The channel is currently narrow and over-deep for much of its length. The proposed crossing would not solve this issue; however, it has been designed to have as minimal an impact as possible.

Brampton Brook crossing The crossing structure has been designed to accommodate the design flood (200yr+65%CC) without surcharging and the natural bed would be retained, therefore width and depth variation would remain similar to baseline.


Brampton Brook crossing The proposed crossing could change the structure and substrate of the river bed, which could increase velocity and alter sediment transport/deposition capacities.

Brampton Brook crossing The crossing structure has been designed to accommodate the design flood (200yr+65%CC) without surcharging and the natural bed would be retained, therefore structure and ubstrate of the river bed would remain similar to baseline.



Structure of the Riparian Zone Brampton Brook crossing The proposed structure would result in loss of riparian habitat and vegetation die-back. This could destabilise the banks and cause an adverse morphological response downstream.

Brampton Brook crossing Riparian planting and habitat creation would be implemented downstream of the structure to compensate the loss of habitat at the bridge crossing location. This would be implemented within the redline boundary and as close to the lost habitat as practicable. The banks underneath the structure would be protected using an appropriate erosion control measure (to be developed at the detailed design phase).

NORTHAMPTON NORTH WEST RELIEF ROAD CONFIDENTIAL | WSP Project No.: 70058029 | Our Ref No.: R1 May 2020 Northamptonshire County Council Page 45 of 52

STEP 3: ASSESSMENT OF THE PROPOSED SCHEME AGAINST WFD OBJECTIVES

The compliance of the Proposed Scheme would be determined based upon an assessment against

the following objectives relating to the biological, physico-chemical and hydromorphological quality

elements:

Does the Proposed Scheme cause deterioration in the Ecological Potential or Status of a body of

surface or ground water?

Does the proposed Scheme compromise the ability of the water body to achieve Good Ecological

Status or Potential?

Does the proposed Scheme cause a permanent exclusion or compromise achievement of the

WFD objectives (e.g. mitigation measures) in other water bodies within the same RBD?

Does the proposed Scheme contribute to the delivery of the WFD objectives (e.g. mitigation

measures)?

The WFD compliance assessment for the proposed Scheme is summarised in Table 4-13.

Table 4-13 – Compliance assessment of the Proposed Scheme against WFD Status

Water body ID GB105032045390 GB105032045380 GB40502G402400

Water body name

Brampton Branch Lower Church Brampton Arm Nene Mid Lower Jurassic Unit

Deterioration in the status/potential of the water body

Biological: It is not envisaged that the

Proposed Scheme would

cause a deterioration in the

status/potential of the

water body for biological

elements.

Physico-chemical: It is not envisaged that the


cause deterioration in the


water body for the physico-

chemical quality

elements due to the

proposed embedded

mitigation.

Hydromorphological: With embedded and

essential mitigation in

place, the Proposed

Scheme is unlikely to

cause deterioration of the

current

hydromorphological status

of the water body.

Biological: It is not envisaged that the



status/potential of the water

body for biological

elements.

Physico-chemical: It is not envisaged that the


cause deterioration in the


water body for the physico-

chemical quality

elements due to the

proposed embedded

mitigation.

Hydromorphological:

With embedded and

essential mitigation in

place, the Proposed

Scheme is unlikely to cause

deterioration of the current

hydromorphological status

of the water body.

It is not envisaged that the




groundwater body. The

mitigation proposed in this

report would sufficiently

neutralise the local impacts

to groundwater so as not to

impact upon the

groundwater body.

Ability of the water body to achieve Good

The Proposed Scheme

and mitigation would not

prevent the implementation

of WFD mitigation

The Proposed Scheme and

mitigation would not


of WFD mitigation

The Proposed Scheme and

mitigation would not


of WFD mitigation


Ecological Potential/Status

measures towards the

waterbody’s objectives. measures towards the

waterbody’s objectives. measures towards the

waterbody’s objectives.

Impact on the WFD objectives of other water bodies within the same RBD

No downstream or upstream impacts are anticipated associated with the preferred option and the mitigation measures proposed

No downstream or upstream impacts are anticipated associated with the preferred option and the mitigation measures proposed

No impacts are anticipated

associated with the

preferred option and the

mitigation measures

proposed

Ability to contribute to the delivery of the WFD objectives

Yes Yes Yes

STEP 4: ASSESSMENT OF THE PROPOSED SCHEME AGAINST OTHER EU

LEGISLATION

4.4.2. Article 4.9 of the WFD requires that “Member States shall ensure that the application of the new

provisions guarantees at least the same level of protection as the existing Community legislation”.

4.4.3. The Nitrates Directive is relevant to the assessment of new modifications. Any potential change in

the nutrient dynamics due to the scheme is most likely due to changes in the sediment regime. No

sources of nitrates would be introduced to the water body as part of the scheme. Therefore, no

separate assessment is required for nitrates.

4.4.4. The Freshwater Fish Directive was originally adopted in 1978 and was consolidated in 2006, then

repealed in 2013. Therefore, no separate assessment is required for fish and the Proposed Scheme

would be designed to mitigate impacts on fish.


5 CONSTRUCTION IMPACTS

5.1 POTENTIAL CONSTRUCTION IMPACTS

5.1.1. The WFD assessment does not require assessment of potential construction impacts on a water

body. This is because the impacts are temporary and do not permanently affect the water body.

However, construction impacts on fluvial geomorphology are considered in this section due to the

potential impacts of the construction activities of the Proposed Scheme on the water body.

POTENTIAL IMPACTS ON HYDROMORPHOLOGICAL QUALITY ELEMENTS

5.1.2. For the assessment of construction impacts, fluvial geomorphology has been separated into three

elements, the sediment regime, channel morphology and fluvial processes. An ecology element is

also included to outline potential impacts on habitats and species. Table 5.1 outlines the potential

impacts on these four elements during the construction of the Proposed Scheme. The main potential

impacts relate to an increase in fine sediment delivery, localised reduction in morphological diversity,

a change in natural fluvial processes and degradation of downstream water quality and potential

smothering of habitats. Required construction mitigation to control these impacts is presented in

Section 5.2.

5.1.3. In addition, weather conditions would also influence the severity of impacts. Many of these impacts

would worsen with intense or prolonged rainfall events during the construction phase.

Table 5-1 – Potential construction impacts on the water bodies

Source of Impact Potential Impacts and Mitigation

Suspended Solids Increased fine sediment supply to watercourses is likely to occur during construction works. This could result from: runoff from

vegetation-free surfaces

plant and vehicle washing

earthworks vegetation clearance

Sediment regime Construction impacts could include fine sediment release, which may cause detrimental impact. The risk of this occurring should be minimal if best practice and pollution prevention guidelines are followed. Potential impacts include changes to the water quality due to sediment release and smothering of ecological habitats. For the watercourse diversions, the channels would be created offline and the water diverted once constructed. Banks should be planted/seeded prior to diverting the water into the new channel. This would manage the risk of sediment release when flow is re-directed into the realigned channel.

Channel morphology No significant impact.

Natural fluvial processes No significant impact.

Ecology Construction impacts could include sediment release (and release of other pollutants), which may have a detrimental impact on aquatic ecology. The risk of this occurring should be minimised if best practice and pollution prevention guidelines are followed. Additionally, mitigation measures for specific ecological risks, such as fish species, should be adhered to and would be detailed in the Construction Environmental Management Plan (CEMP). Potential impacts include changes to the water quality due the sediment release, choking and smothering of ecological habitats such as gravels used for spawning, as well as changes in flow regime disturbing organic matter that provide food and habitat for macroinvertebrates. Construction activities should be planned to avoid the sensitive lifecycle stages of the fish present as detailed in the CEMP.


Source of Impact Potential Impacts and Mitigation

Vegetation clearance Vegetation clearance during construction could reduce the stability of the river channels, increasing the potential for erosion and associated sediment release. Sediment release is likely to be greatest where vegetation clearance is required on slopes and would be particularly significant where woodland clearance is required.

Sediment regime Potential impacts include changes to the water quality due to sediment release and smothering of ecological habitats. Potential impacts on the sediment regime due to fine sediment release during vegetation clearance should be minimised by following best practice and pollution prevention guidance for working in water bodies.

Channel morphology Vegetation removal would be required for the construction of the Proposed Scheme. Thus, construction impacts may cause destabilisation of existing morphological features such as riffles and gravel bars; however, these are presently rare in the existing River Nene and Brampton Brook.


Ecology Fine sediment release could choke sediments utilised by aquatic organisms (invertebrates, fish etc.). Increased suspended sediment load could adversely impact fish by reducing visibility, therefore impacting upon feeding habits. In addition, suspended sediment can irritate the gills of adult fish, and lead to mortality in younger fish. Potential impacts would be minimised by following best practice and pollution prevention guidance for working in water bodies.

Site compound areas

Sediment regime Construction impacts could include sediment release, which may cause detrimental impact. Potential impacts include changes to the water quality due to sediment release and smothering of ecological habitats. The risk of this occurring should be minimal if best practice and pollution prevention guidelines are followed.

Channel morphology No significant impact.


Ecology Construction impacts could include substance releases, which may cause a detrimental impact on aquatic ecology. Potential impacts include changes to the water quality due the substance release and smothering of ecological habitats and macrophytes. The risk of this occurring should be minimal if best practice and pollution prevention guidelines are followed. Additionally, mitigation measures for specific ecological risks, such as fish species, should be adhered to and would be detailed in the CEMP.

Water quality Construction impacts could include contaminant release from substances such as fuel or concrete during the construction of the flood embankment, culvert and realignment of the ordinary watercourse and activities in and around the site compound area. This could detrimentally impact the water quality and ecology downstream. Cement pollution could increase the pH and alkalinity in the water body, affecting aquatic life. The risk of this occurring should be minimal if best practice and pollution prevention guidelines are followed.


5.2 CONSTRUCTION MITIGATION

5.2.1. The objectives of the mitigation measures outlined in this section are to avoid/ prevent, reduce or

offset these impacts.

5.2.2. To prevent fine sediment entering the watercourses, construction activities should occur at least 8m

away from the watercourses where possible.

5.2.3. Potential Environmental Risks include:

Fuel/ oil spillage resulting in contamination of watercourse;

Contamination of watercourse with cement material;

Contamination of watercourse with chemicals; and,

Contamination of watercourse with sediments.

5.2.4. The release of potentially toxic compounds such as fuel, oils and chemicals could have a significant

impact in the vicinity and downstream of the construction site. Measures need to be in place to

prevent the accidental release of pollutants into the watercourse.

PREVENTION AND MITIGATION MEASURES

All operatives would be made aware of the need to protect the watercourse from contamination,

including EA and CIRIA guidance and legal obligations.

To prevent fine sediment entering the watercourses, construction activities should occur away

from the watercourses, where possible.

When construction activities, including stock piling and plant and vehicle washing, occur near a

watercourse they should be separated from the watercourse with barriers (e.g. sediment fences)

to prevent surface runoff from these sites entering the watercourse. Ideally, construction activities

should be at least 8m from the bank top of a watercourse.

Geotextile-material silt fences should be installed to filter suspended solids from runoff.

Timing of works must be carefully considered. If possible, the construction should be carried out

during periods of low flow and low precipitation (typically during summer months) to reduce the

risk of scour and erosion around structures and reduce runoff from the construction area.

The extent of vegetation clearance should be limited to the areas necessary to construct the beck

diversion and enhancements to reduce the amount of sediment released during clearance and

the potential release of sediment from bare ground following clearance.

The works should be carried out in accordance with established best practice.

Pollution spill kits should be kept on site. In the event of an incident these will be used.

Any soils contaminated will be removed immediately to a suitable landfill site.

Bins should be provided on site for debris.

Cleaning of tools and shuttering would be carried out in water not draining directly to the

watercourse.

In any event of expected heavy rain, pouring concrete, and other activities which increase the risk

of contaminating runoff, should not be undertaken.

Timing of construction works should be planned to avoid the sensitive lifecycle stages of the fish

present: brown trout spawning takes place between November and January with eggs likely to

remaining in April.

Sensitivity (to noise and vibration) of those fish species present should be considered to ensure

that appropriate construction methods can be implemented to minimise and avoid disturbance or

avoidance behaviour.


Sediment management and water quality monitoring should be included in the CEMP and be

implemented during any construction works with the potential to affect the watercourse, and plan

for appropriate remediation measures to ameliorate any adverse effects should they occur.

For the watercourse diversion, the channels should be created offline and the water diverted

once constructed. Banks should be planted/seeded prior to diverting the water into the new

channel. This would manage the risk of sediment release when flow is re-directed into the

realigned channel.


6 CONCLUSION

6.1.1. This WFD Assessment has been prepared by WSP on behalf of Northamptonshire County Council

to assess the impacts and to identify appropriate mitigation measures for the proposed works

associated with the Northampton NorthWest Relief Road.

6.1.2. This assessment concludes that the Proposed Scheme would not impact on the WFD status or

objectives of any associated surface water or groundwater bodies in close proximity to the Proposed

Scheme.

6.1.3. Furthermore, the Proposed Scheme would not prevent the achievement of the wider WFD

objectives in the Anglian RBMP and is not predicted to have an impact on any other water body

within the Anglian RBD or mitigation measures developed to achieve good status.


7 REFERENCES

Beaumont, W. R. C., Taylor, A. A. L., Lee, M. J. and Welton, J. S. (2002). Guidelines for Electric

Fishing Best Practice. Environment Agency R & D Technical Report W2-054/TR. Bristol,

Environment Agency.

BGS (2020). GeoIndex. British Geological Society. https://www.bgs.ac.uk/geoindex/. [Accessed May

2020]

British Standards Institution (2003). BS EN 14011:2003: Water Quality Sampling of Fish with

Electricity. London, BSI.

British Standards Institution (2012). BS EN ISO 10870:2012 Water Quality – Guidelines for the selection of sampling methods and Devices for Benthic Macroinvertebrates in Freshwaters. London, BSI. CIEEM (2019). Advice note on the lifespan of ecological reports and surveys. Chartered Institute of Ecology and Environmental Management. Available online: https://cieem.net/wp-content/uploads/2019/04/Advice-Note.pdf. [Accessed May 2020]

Davy-Bowker, J., Clarke, R., Corbin, T., Vincent, H., Pretty, J., Hawczak, A., Blackburn, J., Murphy,

J. and Jones, I. (2008). River Invertebrate Classification Tool. (SNIFFER project WFD72C).

Scotland & Northern Ireland Forum for Environmental Research. Edinburgh, Scotland, UK.

Environment Agency (2001). Electric fishing Code of Practice. EAS/6100/4/02. Environment Agency,

Bristol.

Environment Agency (2003). River Habitat Survey in Britain and Ireland, Field Survey Guidance

Manual: 2003 Version. Environment Agency, Bristol.

Environment Agency (2007). Technical reference material: WFD electric-fishing in rivers.

Operational instruction. Environment Agency, Bristol.

Environment Agency (2020a). Catchment Data Explorer: Brampton Branch - Lower. Environment

Agency, Bristol. https://environment.data.gov.uk/catchment-planning/WaterBody/GB105032045390.

[Accessed May 2020].

Environment Agency (2020b). Catchment Data Explorer: Church Brampton Arm. Environment

Agency, Bristol. https://environment.data.gov.uk/catchment-planning/WaterBody/GB105032045380.

[Accessed May 2020].

Environment Agency (2020c). Catchment Data Explorer: Nene Mid Lower Jurassic Unit.

Environment Agency, Bristol. https://environment.data.gov.uk/catchment-

planning/WaterBody/GB40502G402400. [Accessed May 2020].

Seaby, R. M. H. and Henderson, P. A. (2007). Removal Sampling 2. Pisces Conservation Ltd.,

Lymington, England.

UKTAG (2008) UKTAG Guidance on the Classification of Ecological Potential for Heavily Modified

Water Bodies and Artificial Water Bodies. Available at

http://www.wfduk.org/sites/default/files/Media/Classification%20of%20ecological%20potential%20for

%20HMWBs%20and%20AWBs_Final_310308TAG%20guidance.pdf

https://www.bgs.ac.uk/geoindex/





http://www.wfduk.org/sites/default/files/Media/Classification%20of%20ecological%20potential%20for%20HMWBs%20and%20AWBs_Final_310308TAG%20guidance.pdf

http://www.wfduk.org/sites/default/files/Media/Classification%20of%20ecological%20potential%20for%20HMWBs%20and%20AWBs_Final_310308TAG%20guidance.pdf

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