Hornsea Offshore Wind Farm Project One List of Tables Table 1: Areas of physical disturbance...

S5810.2 18923112 1 GMM

Hornsea Offshore Wind Farm

Project One

Clarification Note relating to the In-combination impacts of the

onshore cable connection on the features of the Humber Estuary

SPA and Ramsar site

Appendix V to the Response submitted for Deadline IV

Application Reference: EN010033

22 April 2014

1

Hornsea Offshore Wind Farm

Project One

Clarification note relating to the in-combination impacts of the onshore cable connection on the

features of the Humber Estuary SPA and Ramsar site

March 2014

2

SMart Wind Limited

11th Floor

140 London Wall

London

EC2Y 5DN

Tel 02077765500

Email [email protected]

Document title Clarification note relating to the in-combination impacts of the

onshore cable connection the features of the Humber Estuary

SPA and Ramsar site

Document Reference UK04-050209-CLR-0001

Status FINAL

Version 0.4

Date 21/03/2014

Project name Hornsea Offshore Wind Farm, Project One

Client SMart Wind Ltd. on behalf of Heron Wind Limited, Njord Limited and Vi

Aura Limited (together the ‘Applicant’)

Authorisation

Signed Chris Jenner

For SMart Wind Ltd on behalf of Heron Wind Limited, Njord Limited and Vi

Aura Limited (together the ‘Applicant’)

Date/Print Name 21/03/2014

Position Consents Manager

3

Table of Contents

1 CLARIFICATION NOTE relating the in-combination impacts of the onshore cable connection the features of the Humber Estuary SPA and Ramsar site ......................................................................................................... 5

1.1 Introduction ............................................................................................ 5

1.2 In-combination assessment with Tetney Sea Line Replacement Project 5

1.3 Intertidal Construction Activities ............................................................ 6

1.4 In-combination construction scenarios .................................................. 7

1.5 In-combination assessment ................................................................. 13

1.6 Conclusions ......................................................................................... 37

1.7 References .......................................................................................... 37

4

List of Tables

Table 1: Areas of physical disturbance associated with construction activities for Project One and Project Two ............................................................................................. 8

Table 2: Construction schedules for possible in-combination scenarios for the installation of the Project One and Project Two export cables. .............................................. 10

Table 3: Assessment of effects from in-combination construction scenarios on dunlin ............ 15

Table 4: Assessment of effects from in-combination construction scenarios on grey plover .... 18

Table 5: Assessment of effects from in-combination construction scenarios on ringed plover ................................................................................................................... 20

Table 6: Assessment of effects from in-combination construction scenarios on oystercatcher ....................................................................................................... 23

Table 7: Assessment of effects from in-combination construction scenarios on knot ............... 25

Table 8: Assessment of effects from in-combination construction scenarios on sanderling ..... 28

Table 9: Assessment of effects from in-combination construction scenarios on curlew ............ 30

Table 10: Assessment of effects from in-combination construction scenarios on bar-tailed godwit .................................................................................................................. 32

Table 11: Assessment of effects from in-combination construction scenarios on common tern ...................................................................................................................... 36

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1 CLARIFICATION NOTE RELATING THE IN-COMBINATION IMPACTS OF THE ONSHORE CABLE CONNECTION THE FEATURES OF THE HUMBER ESTUARY SPA AND RAMSAR SITE

1.1 Introduction

1.1.1 This clarification note has been prepared in respect of the application for a

development consent order (DCO) to the Secretary of State under the Planning

Act 2008 (‘the Application’) by SMart Wind Ltd on behalf of Heron Wind Limited,

Njord Limited and Vi Aura Limited (the ‘Applicant’) for the Hornsea Project One

Offshore Wind Farm (‘Project One’).

1.1.2 Natural England submitted a relevant representation to the Planning Inspectorate

(PINS) on 24th October 2013. They raised a number of points relating to impacts

of construction activities in the intertidal area on the Humber Estuary SPA and

Ramsar site in the Habitat Regulations Assessment (HRA) Report (Section 6).

The Applicant met with Natural England for discussions on these issues on 5th

November and 2nd December 2013.

1.1.3 The Royal Society for the Protection of Birds (RSPB) also raised issues in

relation to the impacts of construction activities on the Humber Estuary SPA and

Ramsar site (email from RSPB, dated 12th September 2013). The Applicant met

with RSPB, to discuss these issues, on 11th September, 7th November and 4

December 2013.

1.1.4 A clarification note was produced by the Applicant in response to Natural

England’s and RSPB’s concerns and submitted in the Applicant’s response to

Deadline 2 on the 20th January 2014 (Appendix T). The note addresses the

effects of Project One alone on the features of the Humber Estuary SPA and

Ramsar site.

1.1.5 Natural England raised concerns within their written representation received by

the Applicant on the 20th January 2014 regarding the potential for in-combination

effects on the features of the Humber Estuary SPA and Ramsar site from Project

One and Hornsea Project Two.

1.1.6 This clarification note provides further information on the potential in-combination

effects that may occur as result of the installation of the export cables for Project

One and Hornsea Project Two and the Philips Tetney Sea line replacement

project on the features of the Humber Estuary SPA and Ramsar site.

1.2 In-combination assessment with Tetney Sea Line Replacement Project

1.2.7 The potential effects of the intertidal construction works associated with Project

One have been assessed in combination with those predicted to arise from

Tetney Sea Line Replacement Project. Phillips 66 Ltd proposes to replace a 4.5

6

km section of the onshore crude oil pipeline from an offshore buoy to Tetney

Tank Farm (RPS 2014). The landfall for the Phillips 66 pipeline is at Northcoates

Point to the north of Horseshoe Point. The intertidal works for the Phillips 66

pipeline will be within 1 km of those for Project One export cable.

1.2.8 Due to the proximity of the Phillips 66 pipeline to the landfall site of Project One,

works are likely to affect many of the same bird species using the intertidal area

as Project One. There is potential for an in-combination effect as a result of

habitat disturbance and loss, and species disturbance and displacement.

1.2.9 The construction works for the Phillips 66 pipeline are programmed to take place

between June 2014 and September 2015 (RPS 2014), although this is subject to

consent. If this timetable were to be followed for the Phillips 66 pipeline and

intertidal works on Hornsea Project One began at the earliest likely timescale of

April 2016, then there would be no overlap in construction activities.

1.2.10 There is no predicted overlap in construction timescales between the Phillips 66

pipeline and the cable landfall for Project One, so there will be no cumulative

disturbance impacts with respect to those birds using intertidal habitat.

1.2.11 Intertidal works for the Phillips 66 pipeline will result in temporary disturbance to

intertidal habitats. These habitats have been assessed as having low sensitivity

to the impacts of pipeline construction, with their infaunal and epifaunal species

having high rates of recovery i.e. recovery within months of disturbance (RPS

2014). Given the intertidal habitats temporarily disturbed by Phillips 66 pipeline

works are expected to recovery prior to the intertidal construction works of

Project One export cable, no cumulative impact of habitat loss for intertidal is

predicted.

1.3 Intertidal Construction Activities

1.3.12 Details of the intertidal construction work for Project One have previously been

described in the following documents:

• The Project Description; Volume 1, Chapter 3, PINS Doc ref No (7.1.3);

• The Habitats Regulation Assessment (HRA) Report (PINS Doc ref No 12.6); and

• The Clarification Note Relating to the Impacts of the Export Cable Installation on Intertidal Birds and the Humber Estuary SPA and Ramsar Site’ (Appendix T of the Applicant’s response to Deadline 2).

1.3.13 Of particular relevance was the clarification note, which contained more detailed

information on proposed construction methodologies and timings associated with

the installation of the export cable.

1.3.14 At this stage, there is no detailed information (i.e., preliminary environmental

information or formal application) publicly available in relation to Project Two. In

order to undertake a meaningful in-combination assessment, information is

required on the sequence of construction work and the nature of the works

7

themselves. Given that no such information is available, for the purposes of this

assessment it has been assumed that the intertidal construction works of Project

One and Project Two will use similar techniques and that the potential effects of

each project will be the same. The Project Two cable corridor is proposed to run

just to the north of Project One cable corridor (see Vol. 1 Chapter 3, Figure 3.14

of the Project One ES (PINS Doc ref No 7.1.3)). As both projects progress, an

increasing level of detail is being made available, although the key remaining

uncertainty is timing. In both cases, the detailed design and implementation of

the construction work will still be dependent on design finalisation by the

appointed contractor.

1.4 In-combination construction scenarios

1.4.15 Based on the assumption that Project Two activities will be similar to those of

Project One all cable installation works at the landfall site, Horseshoe Point,

Lincolnshire, will take place between 1st April and 30th September in a given

year. It has been assumed installation of the Project Two export cable will be

completed in two phases as proposed for Project One.

• Phase One works will be confined to the upper shore in the vicinity of the

sea wall (see Figure 1 and HRA Report Figure 6.1, Doc Ref No 12.6), and

will comprise the drilling of holes and installation of up to four ducts

through the sea wall. During the drilling and installation of each duct, most

work will take place on the landward side of the sea wall. Activity in the

intertidal area is likely to be limited to 2-3 days per duct, associated with

the excavation pit where the drill emerges in the intertidal area and the

installation of ducts.

• Phase Two Up to four cables will be laid and buried through the intertidal

area. During Phase 2, the construction activities will require a barge,

cables and associated machinery (required to spool cables through ducts

in the sea wall and install cables along the intertidal area) to be present in

the intertidal area. Construction works, vehicle movements, and resting of

a barge (dimensions will be 150 m long and 50 m wide) at low tide will be

restricted to the export cable route corridor. Anchor placement for a barge

(up to 9 anchors) would be within the temporary working areas identified

either side of the export cable corridor and this will be the only activity in

the temporary working area.

One cable will be laid at a time through the intertidal area within the export

cable corridor. Installing and burying the cables in the intertidal area is

estimated at 7-10 days per cable. The preparation work, demobilisation

and reinstatement will take place during normal working hours and mainly

during daylight. The cable pull-in will be a 24 hour (round the clock)

operation.

Cables would be buried by trenching, ploughing or jetting. Much of the

cable laying in the intertidal will occur during dry periods – trenching or

8

ploughing during low tide. Trenching and ploughing may temporarily affect

a corridor of up to 40 m width. Jetting will take place in water depths >3 m

and not at other tidal states; it will only occur in the lower shore

(approximately one quarter of the intertidal route) due to shallow water

depths in the remainder of the intertidal even at high water. The indicative

working area for laying one cable through the intertidal area, a strip of

40m width

Table 1: Areas of physical disturbance associated with construction activities for Project One and Project Two

Physical area of disturbance

Project One Project Two

HDD exit pit

(Phase 1 only)

HDD exit pit= 30m x 30m

= 900m2

4 HDD pits = 3600m2

0.36ha

HDD exit pit=30m x 30m =

900m2

Up to 6 HDD pits (SMart

Wind, 2012) = 5400m2

0.54ha

Export cable corridor 2.34km of cable in the

intertidal in a 40m corridor

= 93600m2

9.36 ha

2.56km of cable in the

intertidal in a 40m corridor

= 102400m2

10.24ha

Temporary working

corridor (for placement

of anchors and

movement of personnel)

Approximately 58.86 ha

(588,604 m2)

Approximately 58.86 ha

(588,604 m2)

1.4.16 The potential impacts arising from construction in each phase are identified

below:

Noise and visual disturbance from construction activities

• Phase One The main source of noise disturbance during Phase 1 of the

works will be the drilling of ducts under the seawall (drill rig and diesel

generator). Predicted noise disturbance from Phase 1 works in relation to

birds is described in HRA Report paragraph 6.3.39 (Doc Ref No 12.6).

Noise levels are predicted to be of an acceptable level (i.e., one that is not

predicted to cause displacement of birds) at a maximum range of 250 m

from the works. Any potential noise associated with HDD works on the

landward side of the sea defences will be screened by the sea defences

which is likely to reduce the potential impact distance on birds using

9

intertidal areas so any potential noise disturbance will be confined to less

than 250 m

• Phase Two Disturbance to the intertidal corridor will not be continuous

through the period April to September, there will be gaps of several weeks

with no or minimal disturbance. Evidence presented by Cutts et al. (2009)

from repair work to a pipeline in the Humber Estuary has shown that

disturbed birds (within 100 m) are likely to return within a short time frame

once disturbance ceases, potentially within 30 minutes, and with no

evidence of effects on numbers during surveys the following week,

emphasising the short-term nature of any impacts.

Worst-case estimates of construction noise associated with Phase 2 cable

installation (tracked excavators deployed in the intertidal area) indicate

that levels would fall to levels which would not be predicted to displace

birds at just over 100 m from operations (see paragraphs 6.3.37 to 6.3.52

of the HRA Report).

Potential indirect impacts of construction activity on prey availability

1.4.17 Owing to winter storms, and therefore a periodically high energy environment,

intertidal sediments in the study area are liable to be mobile and therefore the

main intertidal biotopes recorded in this area tend to be reasonably resilient

following physical disturbance (Volume 2 Chapter 2 of the ES: Benthic subtidal

and intertidal ecology, Doc Ref No 7.2.2).

1.4.18 The maximum adverse scenario from any construction activity is that impacted

sediments along each export cable corridor are expected to return to original

condition within approximately 3 months post-construction (Volume 2 Chapter 2

of the ES: Benthic subtidal and intertidal ecology, Doc Ref No 7.2.2).

1.4.19 Given the uncertainty in the construction programme for Project Two and how

this may interact with Project One, the following scenarios have been envisaged

for the purposes of this assessment:

A. Concurrent construction: Project One and Project Two are constructed simultaneously;

B. Overlapping construction: The construction of Project Two overlaps with the construction of Project One construction (i.e., it is staggered), but based on the consenting schedule, the overlap is limited to a one season (April to September), during which there will be work on both projects;

C. Sequential construction: Project Two is constructed following construction of Project One, which in practice means there would be a 6 month break in construction, over the intervening winter period; and

D. Independent construction: Project Two is constructed after the construction of Project One, with an interval of between one and several years.

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1.4.20 Based on the scenarios identified above and considering the phased construction of each project, approximate construction schedules have been summarised in Table 2.

Table 2: Construction schedules for possible in-combination scenarios for the installation of the Project One and Project Two export cables.

Year 1 Year 2 Year 3 Year 4 … Year X Year Y Year Z

Scenario A Project 1 Phase 1 Phase 2

Project 2 Phase 1 Phase 2

Scenario B Project 1 Phase 1 Phase 2


Scenario C Project 1 Phase 1 Phase 2


Scenario D Project 1 Phase 1 Phase 2


Scenario A

1.4.21 It is assumed in this scenario that the Project Two export cable corridor runs to

the north of the Project One cable corridor (within the temporary working corridor

shown in Figure 1 of Appendix T). Scenario A assumes that the cable installation

for both projects occurs simultaneously with both phases occurring at the same

time over a two year period.

1.4.22 In this scenario there will be two lots of adjacent Phase 1 works carried out

(establishment of the site compounds and exit pits and the drilling and

installation of cable ducts from construction compounds underneath the seawall

up to 700 m out from the seawall), followed by two adjacent cable laying

operations across the intertidal area in the subsequent year, with cables being

laid alternately through the April to September.

1.4.23 A separate cable laying barge is identified for each development and it would not

be possible for both ships to operate safely in close proximity. Therefore only one

cable could be laid through the intertidal area at a time. In practical terms, in

order that Phase 2 cable laying for both Projects could be carried out over the

same summer period, it is assumed that each Project would alternate, although it

follows that disturbance from cable laying would be more continuous in nature

11

than for Project One alone. The 30 to 45 day intervals between the laying of

successive cables envisaged for Project One would not apply.

1.4.24 The maximum area of physical disturbance at any one time during Phase 1 and

2 of this scenario are shown in Table 1.

Scenario B

1.4.25 The location of the Project Two export cable remains unchanged. For Scenario B

it has been assumed that Project Two cable installation will follow Project One

and begin in year two so there will be one year of overlap. In this scenario Phase

One of Project Two may overlap with Phase Two of Project One (see Scenario B

row in Table 2). Phase 1 of Project Two being carried out over the same April to

September period as Phase 2 of Project One (i.e. the temporary compound and

drilling of ducts under the seawall to 100m-700 m works for Project Two being

done during the same period as the cable laying across the lower intertidal for

Project One).

1.4.26 Following the completion of Project One, Phase Two of Project Two would occur,

during this time there would be no works being carried out for Project One.

1.4.27 During Year 1 of this scenario the spatial extent of physical disturbance would be

no greater than for Project One alone. During Year Two, Phase 2 of Project One

would occur at the same time as Phase 1 of Project Two increasing the spatial

extent of disturbance. During Year 3, Phase Two of Project Two will be occurring

alone and therefore the spatial extent will be no greater than for Project One

alone.

1.4.28 The total duration of these works is greater than for Scenario A and are likely to

take place over a 3 year period (3 years of working between April and

September in each year).

1.4.29 As there is only potential for the Phase Two works of Project One to overlap with

the Phase One works of Project Two the spatial extent of disturbance will not be

double that of the Project One cable corridor, rather it will be equal to the

physical disturbance resulting from Phase Two of Project One (68.22ha) and

Phase One of Project Two (0.54ha).

Scenario C

1.4.30 Under this scenario there would be no overlapping works for Project One and

Project Two. Project Two would immediately follow the completion of Project One

with no gap (i.e Project One would complete in September and Project Two

would commence works the following April). Thus, the total duration of the works

would be increased to 4 years (i.e. Project One Phase One in Year 1, Project

One Phase 2 in Year 2, Project Two Phase One in Year 3 and Project Two

Phase 2 in Year 4).

12

1.4.31 The total area of habitat affected by the works at any one time is to be no greater

than for Project One alone. As the two projects will not be constructed

concurrently, there would be no simultaneous disturbance to birds within the

intertidal area from Project One and Project Two.

1.4.32 The total duration of these works is greater than both Scenario A and B and may

occur for up to 4 years (4 years of working between April and September).

Scenario D

1.4.33 Under this scenario there would be no overlapping works for Project One and

Project Two. It is assumed, however, that there will be a gap of some years

between the completion of Project One works and the commencement of Project

Two. The total duration of works would be similar to that of Scenario C but with a

larger period of inactivity between the two projects.

1.4.34 The in combination effects of habitat loss and disturbance under Scenario D are

likely to be similar to those under Scenario C with the only difference being that

the disturbance associated with Projects One and Two may be separated by

more than one year. Nonetheless the works would occur over a maximum period

of 4 years (four April to September working periods).

13

1.5 In-combination assessment

1.5.35 Assessment of the Project One on the features of Humber Estuary SPA and

Ramsar alone can be found in the HRA report with further information in

Appendix T of the Applicant’s response to Deadline 2. Figures 1 to 14 of

Appendix T show the distribution of key species within the intertidal area in

relation to the Project One export cable route.

1.5.36 The following section details the spatial distribution extent of each of the species

described in Appendix T and identified by Natural England in their Relevant

Representation. Based on the assumptions detailed in Tables 1 and 2, an

assessment of each scenario has been completed for each species.

Dunlin

1.5.37 Peak numbers of Dunlin within the cable route survey area were recorded in late

October (2,050 birds), outside the proposed working period for cable installation

(See Figure 2 of Appendix T). Within the working period (April to September), the

peak count was 1,300 birds at high tide (about 6 % of the SPA population based

on the most recent WeBS counts) in early April during the spring passage period.

1.5.38 The overall distribution of dunlin (Figure 2 of Appendix T) indicates that birds use

an extensive area of mudflats within the study area, with no indication of

concentrations at a particular area. The areas used by dunlin overlap with the

export cable corridor and the temporary working area for both Projects One and

Two but also include areas outside these zones.

1.5.39 Dunlin were recorded on the upper shore at high tide (Figure 11b of Appendix T),

the distribution data indicate that extensive areas of the upper shore are used

(Figure 2 and Figure 11b of Appendix T).

1.5.40 Dunlin are likely to avoid or be displaced from areas that are within 75 m of

intertidal construction activity (Cutts et al. 2009). Goss-Custard (2007) provides

flight distance maxima for (the distance at which birds take flight to a disturber, a

human intruder) dunlin of 163m.

Studies of the movements of wintering waders indicate that dunlin is one of the

species which show more extensive within-year movements within estuarine

systems (Rehfisch et al. 2003, Symonds et al. 1984). Mean recorded distances

for within-year movements between roosts are about 2-5 km, with a maximum of

about 24 km (Rehfisch et al. 2003). This suggests that dunlin recorded within the

study area during passage periods are capable of moving to alternative sites

including areas within the Tetney Marshes Nature Reserve and Donna Nook

Nature Reserve (situated respectively about 2 km to the northeast and 2 km

southwest of the intertidal cable construction areas). Both of these Nature

Reserves are managed to provide habitat and low levels of disturbance for

estuarine birds. Thus, should dunlin be displaced from the vicinity of the onshore

14

cable construction works area at high spring tides, it is predicted that they can

find alternative areas nearby.

15

Table 3: Assessment of effects from in-combination construction scenarios on dunlin

Scenario A Scenario B Scenario C Scenario D

Dunlin The spatial extent of disturbance is

greater for this scenario than the

effects of disturbance from Project

One alone. Given disturbance of

dunlin is likely to occur out to

maximum of 75m from Project One

alone the additional loss of available

habitat and disturbance that may

occur from Project Two occurring at

the same time is unlikely to result in a

greater effect.

Given the relatively limited extent of

habitat dunlin are predicted to be

disturbed or displaced from, the

‘recovery’ time for the return to the

habitat once the disturbance

mechanism is removed, is predicted to

be minimal. A study of curlew by

Zegers (1973, cited in Smit and Visser

1993) found that roost size returned to

normal 2-3 weeks after disturbance

from cannon netting at the same site

on two nights with a nine day interval.

Curlew is considered to be more

sensitive to disturbance by Cutts and

Allen (1999) and Smit and Visser

(1993). Cannon netting is likely to be a

more intensive disturbance event

(taken in isolation) than construction

disturbance from the Project. It is

therefore reasonable to assume that

The spatial extent of disturbance is

greater during Year 2 for this scenario,

where Phase 2 of Project One may

overlap with Phase One of Project Two.

Given disturbance of dunlin is likely to

occur out to maximum of 75m from

Project One alone the additional loss of

available habitat and disturbance that

may occur from Phase One of Project

Two (HDD exit pits) occurring at the

same time is unlikely to result in a

greater effect.

The duration of disturbance is 3 years

for this scenario. The increase in

duration will lead to disturbance to dunlin

occurring for an additional year (April-

September). This increase in duration is

unlikely to result in a greater effect,

phase 2 works for Project Two are

located away from the large

concentrations of dunlin on the intertidal

(Figure 2 Appendix T). As stated under

scenario A dunlin would be expected to

return to the area following cessation of

activities.

The spatial extent of this

scenario is no greater than for

Project One alone as works for

both Projects will not occur at

the same time.

The duration of disturbance is 4

years where Project Two follows

immediately after Project One.

As stated under Scenario B, the

main concentrations of dunlin

recorded during site surveys

were to the south of the Project 2 cable corridor. As stated

under scenario A dunlin would

be expected to return to the

area following cessation of

activities.

The spatial extent of this

scenario is no greater than

for Project One alone as

works for both Projects will

not occur at the same time.

The duration of disturbance

is unknown where Project

Two follows X years after

Project One. However, for

the purposes of this

assessment we can assume

as a worst case there is only

a one year break between

the two projects.

As stated under scenario A

dunlin would be expected to

return to the area following

cessation of activities.

16

dunlin numbers will return to the

construction corridor in a similar or

reduced timescale.

Conclusions No adverse effect from Scenario A No adverse effect from Scenario B No adverse effect from Scenario

C

No adverse effect from

Scenario D

17

Grey plover

1.5.41 Surveys of the cable landfall area recorded a peak of 885 birds on spring

passage in April (31% of the current SPA population, HRA Report (PINS

Document Reference 12.6) Figure F.67). The species was absent during surveys

from mid-June until September, with a smaller autumn passage (peak of 231

birds in October). Mean count data for grey plover in the Humber Estuary, 1999-

2009, presented in Cruikshanks et al. (2010), indicate that the pattern of peak

numbers in April and May is typical of this species in the Humber.

1.5.42 Within the Humber Estuary, grey plover has been identified as being particularly

sensitive to roosting disturbance, with the WeBS sectors overlapping the survey

area at Horseshoe Point being important within the estuary (Cutts et al., 2009).

The nearby saltmarshes may provide an important communal roost site in the

wider Tetney Marshes area (Cruickshanks et al. 2010).

1.5.43 Grey plover are likely to avoid or be displaced from areas that are within 124 m

of construction activity (Cutts et al. 2009), the flight distance threshold (the

distance at which birds take flight to a disturber, a human intruder) stated by

Goss-Custard (2007). A more recent review by Cutts et al. (2013), states that

efforts should be made to avoid high level disturbance closer than 200m to grey

plover, especially if it includes workers on the intertidal. Most studies of winter

movements have indicated that grey plover are not very mobile within estuaries

(Rehfisch et al. 2003, Symonds et al. 1984), although large itinerant flocks may

occur occasionally on British estuaries (Rehfisch et al. 1993) and a study of

radio-tagged grey plover wintering on the Tees Estuary found that some birds

frequently changed feeding sites at night, moving across the estuary from their

daytime feeding areas to mudflats not used during the day (Dugan 1981, cited

from Rehfisch et al. 1993). The mean within-year distances moved by adult grey

plovers on the Wash was 2.34 km for adults and 0.82 for juveniles (Rehfisch et

al. 1993).

18

Table 4: Assessment of effects from in-combination construction scenarios on grey plover


Grey plover The physical area disturbance will be

greatest during Year Two for this

scenario, when Phase Two for both

projects is occurring simultaneously

(137.32ha). Within the cable landfall

survey area, birds were mainly located

on the muddy substrates at some

distance from the sea wall and the

Phase 1 working area (Figure 3 of

Appendix T) and thus unlikely to be

affected by Phase 1 works. Most

records were also outside the export

cable convergence zone, suggesting

that disturbance from Phase 2

construction activities will not affect key

areas.

None of the grey plover records at high

tide overlapped with the export cable

convergence zone (Figure 11a of

Appendix T) During Phase 2, it is

predicted that any birds disturbed while

cable laying is ongoing in the intertidal

area could readily relocate within the

cable landfall study area, or move to

foraging and roosting areas nearby,

beyond disturbance distance from the

cable corridor.

The spatial extent of

disturbance is greater during

Year 2 for this scenario,

where Phase 2 of Project

One may overlap with Phase

One of Project Two

Given the majority of records

of grey plover were to the

south of Project One cable

corridor and beyond

disturbance distance of 200m advised by Cutts et al.

(2013), it’s unlikely there will

be any greater effect from

overlap of Project Two Phase

One works.

The increased duration of

disturbance to 3 years will

lead to an additional year of

disturbance on grey plover.

The additional year of works

will be located beyond 500m

from the majority of survey

records of grey plover.

The spatial extent of this scenario

is no greater than for Project One

alone as works for both Projects

will not occur at the same time.




As stated under scenario B the

majority of grey plover records are

located beyond the predicted

disturbance distance.


disturbance is unlikely to have an

greater effect, evidence suggests

birds will return to the area 2-3

weeks following cessation of

activity and benthic communities

will recover after 3 months

following completion if activity. In all

cases recovery is expected over

the wintering period (October-

March).





The duration of disturbance is

unknown where Project Two

follows X years after Project One.


disturbance is unlikely to have an





will recover 3 months following

completion if activity. In all cases

recovery is expected over the

wintering period (October- March).

Conclusions No adverse effect predicted from

Scenario A

No adverse effect predicted

from Scenario B

No adverse effect predicted from

Scenario C


Scenario D

19

Ringed plover

1.5.44 Ringed plover were recorded in the cable landfall study area throughout the year

(See Figures 4 of Appendix T), less regularly during surveys in spring and

summer, with peaks in September (120 birds, 7% of cited SPA population) and

December (100 birds). The September peak occurred during autumn migration,

which takes place from mid-July to early October; spring migration is from late

April to early June. With limitations to the spatial and temporal extent of

construction activities, as described in section 1.2 above, far fewer birds than the

peak population estimates are likely to be affected by disturbance.

1.5.45 Responses of ringed plover to disturbance are reported as similar to those of

dunlin, with displacement likely within distances of 100-200 m from construction

activities (Cutts and Allen 1999, Goss-Custard 2007, Cutts et al. 2009). At

distances of over 100m from activity birds however rarely show signs of a

behavioural response, with avoidance of high level disturbance from construction

works advised from within 50m of ringed plover (Cutts et al. 2013).

1.5.46 Surveys of the cable landfall indicate that at all tidal states (Figure 4, Figures 11-

14 of Appendix T) ringed plovers were mainly recorded on the upper shore, with

most records outside and to the north and west of the export cable for both

Projects One and Two. Thus there is no indication from the survey data that the

area where construction activities will take place overlaps with preferred foraging

or roosting habitats for this species.

20

Table 5: Assessment of effects from in-combination construction scenarios on ringed plover


Ringed

Plover

The area of physical disturbance is

greatest for this scenario totalling

0.9ha in year one and 137.32ha in

year.

Construction activities during Phase

1 may effectively exclude birds from

areas of the upper shore or inland

within about 250 m of the drilling

works associated with the sea wall,

during the short (7 day) periods that

drilling and duct installation is

ongoing but the distribution of this

species at high tide suggests there

are alternative areas which can be

used (Figure 11a of Appendix T).

During Phase 2, ringed plovers may

avoid areas in the export cable route

convergence zone within about 100

m of works while cable laying is

ongoing through the intertidal area.

However, the distribution of this

species recorded during surveys

(Figure 3 of Appendix T) suggests

that alternative areas are available

for feeding and roosting within the

cable landfall survey area. During

the short and spatially limited

periods of disturbance which will be

associated with construction

activities, it is most likely that any

displaced birds will be able to move

to nearby areas rather than being

The spatial extent of disturbance is

greater during Year 2 for this

scenario, where Phase 2 of Project

One may overlap with Phase One of

Project Two. During Year two the

total physical area of disturbance

equals 70.36ha.

There were a number of records of

ringed plover recorded in the upper

intertidal close to the location of the

Phase 1 works for Project Two.

However, as stated in scenario A

distribution of this species at high

tide suggests there are alternative

areas which can be used (Figure

11a of Appendix T).

Ringed plover are likely to be

foraging on the more abundant and

smaller age/size classes of the

invertebrate communities represented e.g. Hydrobia ulvae,

small polychaetes and amphipods.

For this suite of waterbird species,

the duration of ‘habitat loss’ as an

indirect result of construction works

is suggested to be much less than 3

months post-construction, during

which the extent of loss will be ever

diminishing









disturbance is unlikely to have a






completion of activity. In all cases


wintering period (October-

March).





The duration of disturbance is

unknown where Project Two

follows X years after Project One.


disturbance is unlikely to have a






completion of activity. In all cases


wintering period (October-

March).

21

displaced further afield.

Conclusion No adverse effect predicted from

Scenario A


Scenario B


Scenario C


Scenario D

22

Oystercatcher

1.5.47 Surveys of the cable landfall area in 2011/12 show that, compared with the

winter period, generally low numbers of oystercatchers were present between

April and September, the proposed period for intertidal works (HRA Report

Figure F.54, Doc Ref No 12.6). Between April and September, peak numbers

were 436 individuals (during a lowering tide) in early July (around 12% of the

cited and current SPA populations), and 850 in mid-September (24% of the SPA

population).

1.5.48 The proposed cable landfall lies between Horseshoe Point and Grainthorpe,

which has been identified as an important feeding area during much of the year

within the context of the Humber Estuary SPA. Birds tend to establish high tide

roosts close to key feeding areas (Catley, 2000).

1.5.49 The literature review by Goss-Custard (2007) reports for oystercatcher a

maximum flight distance threshold of 250m in response to a human intruder. Of

more pertinence is Cutts et al. (2013) review of the literature and field

observations, much relating to the Humber Estuary, which advises a potential

zone of influence from high level disturbance construction works of up to 200m.

1.5.50 Distribution data (Figure 5 of Appendix T) indicate that the preferred habitats for

oystercatcher within the survey area were creeks and cockle beds to the south

and east of the export cable routes from Projects One and Two. The distribution

data suggests these preferred areas are largely outside the area affected by

construction activities associated with cable laying operations..

23

Table 6: Assessment of effects from in-combination construction scenarios on oystercatcher


Oystercatcher The area of physical disturbance is

greatest for this scenario totalling 0.9ha in

year one and 137.32ha in year.

There are few records from the upper

shore in the vicinity of Phase 1 works and

the majority of records are 100 to 200 m

distant from the cable export corridor

(Figure 5 of Appendix T) so that limited

displacement of feeding birds would be

predicted due to construction disturbance.

Given the majority of records of

oystercatcher were to the

south of Project One cable

corridor there is unlikely to be

any greater effect from the

overlap of Project Two

activities.

The majority of oystercatcher

records were on the creeks to

the south Project One,

disturbance effects from Project

Two are likely to be less than

from Project One on this

species.


disturbance under this scenario

is unlikely to cause any greater

disturbance due to the location

of Project Two works away from

preferred habitat for this

species.

The majority of oystercatcher

records were on the creeks to

the south Project One,

disturbance effects from Project

Two are likely to be less than

from Project One on this

species.


disturbance under this scenario

is unlikely to cause any greater

disturbance due to the location

of Project Two works away from

preferred habitat for this

species.

Conclusions No adverse effect predicted from Scenario

A No adverse effect predicted

from Scenario B No adverse effect predicted

from Scenario C No adverse effect predicted

from Scenario D

24

Knot

1.5.51 During surveys of the cable landfall area, peak numbers of knot were recorded in

in November (HRA Report, Figure F.21), outside the proposed working period.

Between April and September, the peak count of knot was 420 in mid-September

(autumn passage, lowering tide) representing 2% of the Humber SPA population.

With limitations to the spatial and temporal extent of construction activities, as

described in section 1.2 above, far fewer birds than the peak population

estimates are likely to be affected by disturbance.

1.5.52 Birds were located widely within the survey area (Figure 6 of Appendix T), with

some of the largest flocks were found well below mean high water mark at low

tide (Figure 13b of Appendix T). At high tide, knot were recorded using the upper

shore, probably roosting (Figure 11b of Appendix T).

1.5.53 Noise modelling predicts that knot (and other estuarine birds) may avoid or be

displaced from areas within approximately 250 m of the construction activities

associated with drilling of ducts through the sea wall (HRA Report, section

6.3.39). At other times and locations during the working period, noise modelling

predicts knot may avoid or be displaced from areas within approximately 100 m

of the construction activities, This is also the minimum distance at which Cutts et

al. 2013 advises intertidal construction work with high level visual disturbance to

be from Knot.

1.5.54 Wintering knot are highly mobile between feeding and roosting areas on the

Humber, in response to weather conditions, tidal conditions or disturbance (Allen

et al., 2003) and in the outer estuary large intertidal movements occur between

feeding and roosting areas on the north and south shores (Catley, 2000). Studies

of the movements of overwintering waders on estuaries found that knot was the

most mobile species, with mean between roost movements of 15.4-17.7 km and

a maximum of 35 km in the Moray Basin (Rehfisch et al. 2003). It has been

suggested that the mobility of knot within and between estuaries may be a

strategy to identify several potentially suitable feeding sites, in case food sources

from one site are reduced (Rehfisch et al. 1993).

25

Table 7: Assessment of effects from in-combination construction scenarios on knot


Knot A relatively small area of the upper

shore will be affected with no works

elsewhere in the intertidal area. While

knot have been recorded close to the

Phase 1 works area, and may roost in

this area at high tide (Figure 11b of

Appendix T), the distribution data

indicate that birds also use several

areas of the upper shore (Figure 6 and

Figure 11b of Appendix T) and could

occupy areas beyond disturbance

distance from construction activities

without being displaced from the area.

In relation to Phase 2 works for both

Projects in the intertidal area, there is

some overlap between the distribution

of knot and the export cable

convergence corridor but also an

indication that this species makes use

of areas to the south and east of the

working area (Figure 6 of Appendix T).

Given the limited temporal and spatial

extent of works associated with cable

laying, it is likely that any disturbed

birds can relocate within the local area.

In the absence of disturbance, knot are

expected to re-occupy areas in between

periods of construction activity

The overlap of works in Year 2 may

cause increased disturbance to knot

using the upper intertidal, although the

distribution data indicate that birds also

use several areas of the upper shore

predominantly away from where Phase 2

works will be occurring for Project One

and could occupy areas beyond

disturbance distance from construction

activities without being displaced from

the area.

In relation to Phase 2 works for Project

2, the Project 2 cable corridor is located

beyond the likely disturbance distance of

100m for knot and so disturbance effects

are likely to be less than for Project One

alone.

Given the limited temporal and spatial

extent of works associated with cable

laying, it is likely that any disturbed birds

can relocate within the local area. In the

absence of disturbance, knot are

expected to re-occupy areas in between

periods of construction activity

The majority of knot records

were to the south of the

Project 1 cable corridor and

beyond the disturbance

distance of likely effect from

Project 2 cable corridor. The

effect of Project Two cable

activities is likely to cause less

disturbance than Project One.


disturbance under this

scenario is unlikely to cause

any greater disturbance due to

the location of Project Two

works away from preferred

habitat for this species

As for scenario C the

disturbance effect from

Project Two alone is likely to

be less than for Project One.

The increased gap between

the two projects compared to

scenario C will further

enhance the recoverability of

benthic communities and

ensure birds return to the

area following the cessation

of Project One activities.

26


Scenario A No adverse effect predicted from

Scenario B No adverse effect predicted

from Scenario C No adverse effect predicted

from Scenario D

27

Sanderling

1.5.55 Sanderling were recorded sporadically within the cable landfall area during

surveys in 2011/12 (HRA Report, Figure F.46 Doc Ref No 12.6). Peak numbers

were present in January (150 birds, 15% of the most recent WeBS count for the

Humber Estuary), outside the proposed working period. Between April and

September the highest count was 21 birds in late August, 2% of the most recent

WeBS count for the Humber Estuary. With limitations to the spatial and temporal

extent of construction activities, as described in section 1.2 above, far fewer birds

than the peak population estimates are likely to be affected by disturbance.

1.5.56 All sanderling records within the cable landfall survey area between April and

September were on the upper shore to the northwest of the cable route

convergence zone (Figure 7 of Appendix T). The Tetney to Horseshoe Point

WeBS core count sector (which overlaps with the cable landfall survey area)

recorded a peak of 158 birds in May 2010 although the location of these birds is

unknown.

1.5.57 Potential disturbance distances for roosting birds have not been found although

sanderling will show 100% response to people approaching relatively close,

within 30m (Cutts et al. 2009). As a species tolerant of moderate and high level

visual disturbance, Cutts et al. (2013) advises the potential zone of influence

from visual construction works to be up to 50m.

28

Table 8: Assessment of effects from in-combination construction scenarios on sanderling


Sanderling The distribution of sanderling records

within the cable landfall study area,

mainly on the upper shore to the north

and east of the cable route (Figure 7 of

Appendix T), indicates that birds are

using areas several hundred metres

from Phase 1 drilling activities.

Assuming the distribution reflects the

favoured areas of the birds at

Horseshoe Point in the vicinity of the

sea wall, then little or no disturbance to

sanderling is predicted during Phase 1

of construction works. A few of the

sanderling records overlap with the

cable route convergence zone (Figure

7), suggesting some displacement of

sanderling from this area may occur

during Phase 2 for Project One. Given

the limited temporal and spatial extent

of works associated with cable laying, it

is likely that any disturbed birds can

relocate within the local area while

construction is ongoing in the intertidal

area

As stated in scenario A sanderling

records were mainly on the upper

shore closer to the seawall. Phase 1

works for both projects are likely to

cause limited disturbance to this

species.

Year 2 of works under this scenario is

unlikely to cause any greater

disturbance as the Project one cable

corridor is located away from the

majority of sanderling records. Some

displacement may occur during the

Phase 2 works for Project Two but

this is likely to be minor given the

limited number of records on the

lower intertidal.

The duration of disturbance under

this scenario maybe up to 4 years.

Assuming the distribution reflects

the favoured areas of the birds at

Horseshoe Point in the vicinity of

the sea wall, then little or no

disturbance to sanderling is

predicted during Phase 1 of

construction works for either

Projects.

A few of the sanderling records

overlap with the cable route

convergence zone for Project One

but there were no records in the

Project Two cable route indicating

minimal disturbance during Phase

2 of Project 2.

As under scenario C

disturbance will be minimal

on this species.

The increased recovery

period between projects

will ensure recoverability of

benthic communities and

the long term effects on

sanderling populations will

be no greater than for

Project One alone.


Scenario A


Scenario B


Scenario C


from Scenario D

29

Curlew

1.5.58 Surveys at the cable landfall site recorded curlew in most months in 2011/12,

with a peak flock size of 74 birds in late September 2011, about 2% of the cited

and current SPA populations (HRA Report, Figure F.60). Birds were recorded

throughout the intertidal part of the survey area with no suggestion of preference

for particular areas (Figure 8 of Appendix T).

1.5.59 The peak count recorded in the cable landfall survey area coincides with autumn

curlew passage. This commences in mid-June with peak counts later in the

month and throughout July (Allen et al. 2003). Numbers on the Humber Estuary

continue to build-up to peaks in August or September, with smaller numbers of

birds remaining on the site to over-winter. Spring migration is reported from early

March to late May, although numbers recorded are far smaller than in autumn.

Small numbers of curlew remain on the Humber during mid-summer and these

birds may be young, non-breeding adults (Catley, 2000).

1.5.60 Cutts et al. (2009) study reported unhabituated birds behaviourally responding to

third party disturbance e.g. taking flight, from a distance of up to 275 m, whilst

the literature review by Goss-Custard (2007) provides a range from an outlying

lower limit of 38 m to an upper limit of 339 m. However of the twenty studies

reviewed by Goss-Custard (2007), only one recorded a flight distance greater

than 213 m. As a species considered to be wary of moderate and high level

visual disturbance, Cutts et al. (2013) advises the potential zone of influence

from visual construction works to be up to 300m.

1.5.61 Within the cable landfall survey area, there are no records of curlew on the

upper-shore close to the proposed working area for Phase 1 of cable

construction activities (Figure 8 of Appendix T). Thus there is no indication that

this part of the shore is important for curlew or that disturbance from Phase 1

construction activities will displace individuals of this species.

1.5.62 Curlew were recorded using intertidal areas which overlap with the export cable

route convergence zone so Phase 2 activities could displace some birds. The

wide distribution of curlew over the intertidal mudflats within the survey area

suggests that birds could relocate within the study area.

30

Table 9: Assessment of effects from in-combination construction scenarios on curlew


Curlew Curlew is probably one of the most

sensitive of all waterbirds to

disturbance. For the purposes of

assessment, a precautionary potential

disturbance zone of up to 300m has

been assumed for this. This is based on the findings of Cutts et al. (2013), for

which much of the literature and field

observations reviewed were from the

Humber Estuary. Curlew are widely and

comparatively evenly distributed in the

study area.

A maximum of 137.32ha of physical

disturbance will occur at any one time

under scenario A between April and

September. However extensive areas

of similar habitat exists in which to

forage outwith of the disturbed area,

therefore an adverse effect on this

species is not predicted.

Curlew were recorded using

intertidal areas which overlap with

the export cable route

convergence zone so Phase 2

activities could displace some

birds. The wide distribution of

curlew over the intertidal mudflats

within the survey area suggests

that birds could relocate within

the study area.

A maximum of 70.36ha of

physical disturbance will occur in

Year 2 when Phase 1 works from

Project Two will overlap with

Phase 2 works for Project One.

The increase duration of disturbance is

unlikely to lead to an adverse effect on

curlew. A study of curlew by Zegers

(1973, cited in Smit and Visser 1993)

found that roost size returned to

normal 2-3 weeks after disturbance

from cannon netting at the same site

on two nights with a nine day interval. .

Curlew are predators of the larger

size/age classes of invertebrate prey.

The recovery in prey availability in

impacted areas is likely to be slower as

a consequence of the larger size class

and/or restrictive prey species. The

export cable corridor for both Projects

will bisect foraging areas frequented by

highly mobile foraging flocks. The

duration of ‘habitat loss’ indirectly from

cable-laying activity in the study area

can be expected to last as much as

three months post-construction of an

export cable during which time the

extent of loss will be ever diminishing.

The habitat would be expected to

recover after each working period and

curlew return to the area.

The recovery period

following cessation of works

on Project One as worst

case could be one year.

This will enable full

recovery of benthic

communities and no long

term effects on the curlew

population are predicted.


Scenario A


Scenario B


Scenario C


from Scenario D

31

Bar-tailed godwit

1.5.63 During surveys of the cable landfall area, peak numbers of bar-tailed godwits

were recorded between October and March, outside the proposed working

period. The peak count was nearly 800 birds in late November (HRA Report

12.6, Figure F.6), representing 29% of the cited Humber Estuary SPA population,

or 13% of the most recent WeBS core count population for the Humber Estuary.

These numbers are consistent with advice from Natural England that there is a

low tide roost of 400-600 bar-tailed godwits on the upper-shore overlapping with

the cable export route convergence zone.

1.5.64 Within the period April to September, bar-tailed godwits were recorded in smaller

numbers (less than 100 birds) in April and early May and in September, but were

absent between late May and August. The peak count was close to 100 birds in

late September, representing about 2% of the most recent WeBS count for the

Humber Estuary. This indicates the presence of spring and autumn passage

birds in the area. The largest numbers of birds were recorded on the upper-shore

with a small number of records overlapping with the export cable route

convergence zone (Figure 9) but also many records at distances of several

hundred metres from this area.

1.5.65 For bar-tailed godwit, Cutts et al. (2009) study reported unhabituated birds

behaviourally responding to third party disturbance e.g. taking flight, from a

distance of up to 163 m, whilst Goss-Custard (2007) review found the maxima

flight distance threshold (the distance at which birds take flight to a disturber, a

human intruder) to be 219m. As a species considered tolerant of moderate and

high level visual disturbance, Cutts et al. (2013) advises the potential zone of

influence from visual construction works to be up to 200m.

1.5.66 Based on predictions in Smit and Visser (1993), bar-tailed godwits may be

displaced at distances of about 100m from human movements. In the Firth of

Forth and the Moray Basin, studies have shown that bar-tailed godwits ranged

more widely than most other species (Rehfisch et al. 2003, Symonds et al.

1984), reflecting flexibility in habitat choice (within estuarine mudflats). A model

of the quality of the Humber Estuary for shorebirds (Stillman et al. 2005)

predicted that a 2-8% reduction in intertidal area would reduce survival rates in

bar-tailed godwit – indicating a sensitivity of this species to habitat loss. Thus for

this species, the availability of suitable alternative habitat nearby for any

disturbed birds to move to is important.

32

Table 10: Assessment of effects from in-combination construction scenarios on bar-tailed godwit


Bar-tailed

godwit None of the birds recorded during

cable landfall surveys are close

enough to the works area for Phase 1

of cable installation to indicate that

drilling and associated activities will

not cause significant disturbance

(Figure 9 of Appendix T). There is

the potential for Phase 2 activities

within the cable export convergence

corridor to displace some bar-tailed

godwits from possible roosting (and

foraging) areas. However it is most

likely that any disturbed birds could

relocate within a few hundred metres

of the construction activities

The Project Two export cable corridor

is located to the north of the main

areas of usage of bar-tailed godwit. The overlap of Phase 1 works for

Project two and Phase 2 works for

Project two are unlikely to cause

increased disturbance given the

distribution of birds within the

intertidal away from the location of

Phase 1 works.

Bar-tailed godwit are specialist

feeders. The recovery in prey

availability in impacted areas is likely

to be slower as a consequence of the

restrictive prey species. The duration

of ‘habitat loss’ indirectly from cable-

laying activity in the study area can be

expected to last as much as three

months post-construction of an export

cable during which time the extent of

loss will be ever diminishing. The

increase duration of works under this

scenario are unlikely to affect the

recoverability of benthic habitats in

the long term.

As stated under scenario A Phase 1

works are unlikely to cause significant

disturbance. The Phase 2 works of

Project One may displace birds from

possible roosting and foraging sites

however its like birds could relocated

within a few hundred metres of

activities.

The extended duration of works under

this scenario is unlikely to prevent

birds returning to the area. A study of

curlew by Zegers (1973, cited in Smit

and Visser 1993) found that roost size

returned to normal 2-3 weeks after

disturbance from cannon netting at

the same site on two nights with a

nine day interval. Curlew is

considered to be more sensitive to

disturbance by Cutts and Allen (1999)

and Smit and Visser (1993). It is

therefore reasonable to assume that

bar-tailed godwit numbers will return

to the construction corridor in a

similar or reduced timescale.

As stated under scenario B bar-tailed

godwit are specialist feeders,

however the increase duration of

works under this scenario are unlikely

to affect the recoverability of benthic

habitats in the long term, especially

given each phase of each project will

Similar to scenario C but

with a longer recovery

period between cessation

of Project One activities.

The increased time

between each project will

be beneficial to the

recoverability of benthic

habitats.

33

disturb different areas of the intertidal

at different times.


Scenario A


Scenario B


Scenario C

No adverse effect

predicted from Scenario D

34

Common tern

1.5.67 The Horseshoe Point area has been identified by Natural England to be a

common tern roost site in late summer, likely coinciding with birds on southward

migration. There are two SPAs further north on the east coast of England which

have the greatest likelihood of hosting common terns that may roost in the

vicinity of the cable landfall site. The two sites considered in the current

assessment are the Coquet Island SPA and Farne Islands SPA. Common tern is

not a qualifying feature of the Humber SPA.

1.5.68 The potential for LSE in relation to disturbance during cable installation has been

identified for common tern, based on advice from Natural England that the

species was found roosting on passage (in late summer, between July and

September) near the cable landfall site in numbers that are potentially significant

in the context of the Coquet Island and Farne Islands SPA populations.

1.5.69 Information provided by Natural England indicates that the roosting area used by

terns is to the north and east of the cable landfall export zone, with some overlap

with the temporary working area to the north of the cable zone but extending into

the intertidal area north of the temporary working area. The availability of this

area will be dependent on tide state as it includes parts of the shore below mean

high water, indicating that common terns must also have alternative roost sites.

1.5.70 Common terns were recorded infrequently during surveys of the cable landfall

area, with all records on the upper shore north of the export cable route

convergence zone (Figure 10 of Appendix T). However the numbers of roosting

terns would be expected to be highest at dusk, whereas estuarine surveys were

carried out at varying times throughout daylight hours. The use of the intertidal

area by terns between July and September may be sporadic, and often most

frequent in congregations from dusk onwards, which may be missed by surveys.

1.5.71 Most scientific studies of disturbance to terns have concentrated on breeding

colonies, so the translation of results to roosting birds on passage may be

limited. Terns can be relatively resistant to human activity in close proximity (for

example a large breeding colony persists within the Imperial Lock Dock SPA,

Edinburgh) within the busy port of Leith. Studies of disturbance to breeding

colonies suggest that buffer zones of 100-200m would minimise any negative

impacts of human activities and prevent displacement of common terns (Camey

and Sydeman, 1999, Rodgers and Smith 1995, Erwin 1989).

1.5.72 Phase 1 of the works, in the vicinity of the sea wall, is at least 500m distant from

the areas used by roosting terns (e.g. see tern records on Figure 10) so no

disturbance is predicted.

1.5.73 Common tern roosts in the vicinity of the cable landfall will occur around low tide

and at dusk and into the night during late summer. This will be outside the

daylight working hours of Phase 2 works (except for a short (c. 12 hours) period

of cable pull-in across the intertidal area, see section 1.2 above). Thus

disturbance to the intertidal area will be negligible during the time that common

35

terns are likely to be present. In addition all information on the location on tern

roosts indicates that these are to the northwest of the cable export convergence

zone and that roosting terns can be accommodated within areas beyond the

likely disturbance distance of 100-200m. Further, roosting terns are most likely to

be post-breeding adults, likely accompanied by fledged juveniles, so no impacts

on the productivity of SPA populations at Coquet Island or the Farne Islands are

not predicted.

36

Table 11: Assessment of effects from in-combination construction scenarios on common tern


Common

tern

Most scientific studies of disturbance to terns have concentrated on breeding colonies, so the translation of results to roosting birds on passage may

be limited. Terns can be relatively resistant to human activity in close proximity (for example a large breeding colony persists within the Imperial

Lock Dock SPA, Edinburgh) within the busy port of Leith. Studies of disturbance to breeding colonies suggest that buffer zones of 100-200m would

minimise any negative impacts of human activities and prevent displacement of common terns (Camey and Sydeman, 1999, Rodgers and Smith

1995, Erwin 1989).

Phase 1 of the works for both Projects, in the vicinity of the sea wall, is at least 500m distant from the areas used by roosting terns (e.g. see tern

records on Figure 10) so no disturbance is predicted.

Common tern roosts in the vicinity of the cable landfall will occur around low tide and at dusk and into the night during late summer. This will be

outside the daylight working hours of Phase 2 works for both Projects (except for a short (c. 12 hours) period of cable pull-in across the intertidal

area, see section 1.2 above). Thus disturbance to the intertidal area will be negligible during the time that common terns are likely to be present. In

addition all information on the location on tern roosts indicates that these are to the northwest of the cable export convergence zone and that

roosting terns can be accommodated within areas beyond the likely disturbance distance of 100-200m.

As common tern roosts will not be affected by construction works from either project the timescales associated with each scenario are irrelevant and

no effect is predicted.


Scenario A


Scenario B


Scenario C


Scenario D

37

1.6 Conclusions

1.6.74 The potential effects of the intertidal construction works associated with Project

One have been assessed in combination with those predicted to arise from

Project Two. There is uncertainty about the timing of the works associated with

Project Two so different scenarios have been assessed to consider the full range

of potential interaction between the two projects.

1.6.75 In Scenario A it is assumed that the works will occur concurrently and, as a

consequence, the duration of works will be no longer than that predicted for

Project One alone. The extent of disturbance arising from the works will be

greater though due to the larger working area and greater level of activity

expected. In Scenarios C and D the works are sequential and so the level of

disturbance in any year is no greater than that for Project One alone. The

duration of works will be longer (4 years in each case, compared to 2 years for

Project One alone), the difference in these scenarios being the length of time

between the conclusion of Project One and the commencement of Project Two.

Scenario B assumes some overlap of the works in the two projects. The duration

of works is longer than for Project One alone (3 years) but less than that for

sequential construction scenarios. The level of disturbance assumed in this

scenario is variable. In years 1 and 3 it is the same as that for Project One alone,

in year 2 it will be greater reflecting a larger working area and greater level of

activity arising from the concurrent construction of Project One and Two.

1.6.76 The effects of these scenarios on bird species that are features of the Humber

Estuary SPA and that have a reliance on the intertidal habitats potentially

affected by these works have been systematically assessed. There is no

indication that an adverse effect on any of these features is likely to arise as a

consequence of the construction of Project One together with Project Two under

any of the scenarios considered. In all cases the extent of disturbance is

relatively low and temporary in nature. There is evidence to suggest that

intertidal birds recover quickly from disturbance and are likely to return to areas

shortly after any activity causing disturbance ceases. There will be gaps in

activity that will allow birds to continue to make use of habitats once construction

works cease. In some scenarios these gaps will comprise months or even years

without any construction activity. In none of the scenarios is any permanent loss

of habitat predicted.

1.6.77 On this basis it is concluded that there will be no adverse effect on the intertidal

bird interest features of the Humber SPA arising from Project One alone or in

combination with any other plan or project (including Project Two).

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