fairport house, bursledon, river hamble · 2017. 1. 3. · fairport house, bursledon, river hamble...

Fairport House, Bursledon, River Hamble

Proposed Pontoon and Associated Mitigation

Supporting Statement and Water Framework

Directive Assessment

Compiled by Dr P Tosswell, Lymington Technical Services Ltd

Document 10549 Rpt2 Dec 2016

Lymington Technical Services Ltd 1

Contents

1. Site Location and Works 2

2. Required Consents 3

3. Proposed Use 3

4. Navigation 4

5. Method Statement 4

6. Protected Areas 5

7. Impacts on Protected Areas 5

8. Background to Water Framework Directive Assessment 6

9. WFD Assessment 7

9.1 Screening & Scoping Stage 9

10. WFD Impact Assessment & Mitigation 14

11. Summary 15


1. Site Location & Works

The proposed jetty and pontoon is located at Fairport House Hamble and shown in red on the

following image:

The proposed works consist of a package which includes mitigation work to improve the nearby

habitat conservation. The land where the jetty starts is used for dinghy storage and regular

usage. This area is indicated (approximately) by the magenta area and is in line with an

agreement between Natural England and the current owner.

The agreed use of this area is for boating activities associated with the River Hamble. This

includes the storage of craft and associated trailers and vehicles. Maintenance and access to all

of the existing slipways, boardwalks and boathouse are also permitted within this agreement.

The jetty is designed to have minimal impact (details follow) and the mitigation consists of

removal of an existing pontoon. This existing pontoon provides berthing for a vessel with access

over high water periods.

The green circle in the above image shows the existing pontoon to be removed. Removal of this

pontoon will reduce the usage of the access channels to an insignificant level. The green line

shows a channel that will have no practical use. Whilst an existing boathouse is also nearby the

practical need for this is negligible with the proposed pontoon.


The pontoon location is such that it will remain floating at all tidal levels of MLWS and above.

Access to the pontoon will be by an elevated jetty structure with a brow to the pontoon.

At this time no hydrographic data is available but that will be supplied in the near future (Jan

2017).

The access jetty is elevated to prevent flooding and to minimise impact on inter tidal habitat.

The jetty is supported on 4 pairs of tubular steel piles driven into the bed. The seaward end of

the jetty is supported by a cross beam on a larger tubular steel pile which also supports the

hinge of the brow. The bottom of the brow rests on a landing pontoon forming part of the main

pontoon. The pontoon is restrained by two tubular steel piles. This is all in accordance with

normal practice.

The access jetty structure will be formed from steel frames connected to the piles and decked

with an open grid grp decking. This has the additional advantage that there is very little

shadowing of the inter tidal habitat.

Drawing 10549/4 shows the proposed works.

2. Required Consents

These works require the following consents:

Marine Licence from the Marine Management Organisation (MMO)

Planning consent from Eastleigh Borough Council (EBC) (as works cross the MLW mark)

Harbour Works Consent from River Hamble Harbour Authority (RHHA)

Landowner consent – applicant and Crown Estates

Flood Defence Consent – excluded activity by virtue of MMO application

In order to meet application deadlines, the sequence will be RHHA, EBC, MMO.

3. Proposed Use

The pontoon is intended for the personal use of the land owner and is for leisure purposes. At

this stage, no vessel has been specified but the relatively shallow water at low tide would

preclude vessels larger than those on nearby moorings. This will replace the existing berth so

there is no increase in vessel numbers.

The frequency of use is difficult to estimate but it is likely to be similar to vessels on nearby

moorings.

For the avoidance of doubt no dredging is proposed as part of these works.


4. Navigation

The pontoon is located just seawards of the MLWS contour so that it will remain floating at all

states of tide.

As is clear from the earlier image and drawing the distance between the pontoon (and any

moored vessel) to the existing river moorings is no smaller than the existing gaps downstream

and upstream.

No rafting of vessels is proposed and there is no increase in moorings as this is balanced by the

removal of the existing pontoon.

Whilst the requirement for navigation lighting is determined by Trinity House as part of the

Marine Licence application it is not considered that any such lighting will be necessary or

required.

5. Method Statement

The works are in two distinct phases, marine and land.

Marine -

The pontoon and access brow will be installed from a spud legged crane barge using a vibro

hammer in accordance with usual practice.

The works will be undertaken at high water with the brow support pile being driven first. The top

of this pile will be fitted with a cross piece to support the upper end of the brow.

The pontoon will be floated into position and the two remaining piles driven.

The brow will then be craned into position.

These works will be undertaken over high water periods to minimise any impacts on navigation.

This also has the advantage that any feeding wildfowl will be some distance away as the mudflats

will be covered.

Land -

The land work comprises the driving of the jetty support piles and the construction of the elevated

walkway. In terms of plant this is a much smaller operation than the marine phase and the works

will have to be conducted when tidal access is possible.

The works will be undertaken using small tracked plant operating over crawler mats to protect the

inter tidal areas.


Mitigation –

The existing pontoon will be removed at high water with a small launch. The pontoon may form

part of the new structure or will be sold.

6. Protected Areas

Hackett’s Marsh LNR (1009285) – this is south of the site and primarily a saltmarsh habit. It is an

important feeding area for waders and wildfowl.

Ramsar Site – Solent & Southampton Water (UK11063). Ramsar sites are wetlands of international

importance. This particular site is designated for the habitats that support wintering wildfowl and

breeding gull and tern populations (JNCC). Overlays SPA & SSSI. The works above MLW are within

this area.

Site of Special Scientific Interest (SSSI) – Lincegrove and Hackett’s Marshes (1080734). The

condition is unfavourable recovering. There is a wider concern (Natural England) regarding erosion

of the saltmarsh. Overlays SPA & Ramsar. The works above MLW are within this area.

Special Protection Area (SPA) – Solent and Southampton Water (UK9011061). SPAs are sites of

importance for rare and vulnerable birds as well as migratory birds. For this SPA the main threats

are pollution, fishing, water quality, leisure (JNCC). Overlays SSSI & Ramsar. This covers the works

above MLW.

The Special Area of Conservation (SAC) – Solent Maritime (UK0030059). SACs are sites designated

areas to ensure the conservation of important habits and species. This area is of importance for

estuaries, Spartina swards and Atlantic sea meadows. For this SAC the main threats are pollution,

fishing, water quality, leisure (JNCC). Overlays all the above sites.

WFD Estuarine and Coastal Water Bodies Cycle 2 GB520704202800 Southampton Water

Coastal Sensitive Areas – Eutrophic – Hamble Estuary UKENCA123 (Nitrate sensitivity).

WFD Habitats – higher sensitivity – saltmarsh

7. Impacts on Protected Areas

This section summarises the key points, details of the mitigation are provided as part of the WFD

assessment. In order to meet RHHA submission deadlines we have not yet been able to discuss

these details with Natural England but this is intended.

LNR – The works are outside of this area but the proposed mitigation has the potential to offer

improvement due to a lowering of human activity nearby.


Ramsar – Whilst the works are within this protected area the proposed mitigation offers a direct

improvement to the habitat.

SSSI – Whilst the works are within this protected area the proposed mitigation offers a direct

improvement to the habitat.

SPA – Whilst the works are within this protected area the proposed mitigation offers a direct

improvement to the habitat. There will be no increase in threat from pollution, fishing or water

quality. The threat from leisure (human activity) is lessened by removal of the existing pontoon.

SAC – Whilst the works are within this protected area the proposed mitigation offers a direct

improvement to the habitat. There will be no increase in threat from pollution, fishing or water

quality. The threat from leisure (human activity) is lessened by removal of the existing pontoon.

WFD – Covered in WFD assessment

8. Background to Water Framework Directive Assessment

The purpose of a Water Framework Directive (WFD) assessment is to determine whether the

proposed works will compromise the attainment of a WFD objective or result in the deterioration

of the current ecological status of the relevant waterbodies.

The EA have released (Dec 2016) a new version of ‘Clearing the Waters for All’ and this version is

followed here.

The process consists of 3 stages –

Stage 1 – The Screening Stage

This stage is used to identify activities which need to be considered further (i.e. excludes those

which do not require further assessment). Activities conducted between 2009-2014 are excluded

as they would have been covered by the River Basin Management Plan (RBMP) evidence collection

process. This typically applies to maintenance activities including dredging.

Stage 2 – The Scoping Stage

This stage identifies the potential risks to the following receptors:

Hydromorphology

Biology – fish habitats

Biology – fish

Water quality

Protected areas

Stage 3 – Impact Assessment

This stage examines whether the activity will have a significant non-temporary effect on each

receptor.


9. WFD Assessment

The assessment uses the new (Dec 2016) online EA tables which are reproduced in the following

pages.

In order to improve clarity the water body data from Catchment Data Explorer is reproduced

below.

The Catchment Data Explorer provides data updated 31:03:16.


9.1 Screening & Scoping Stage - WFD Tables for activities in estuarine and coastal waters

Works take place in or affect more than one water body, complete a template for each water body – single water body

Works include several different activities or stages as part of a larger project, complete a template for each activity as part of your overall WFD assessment – not significantly different as mitigation is included

Activity Description, notes or more information

Applicant name Mr Mark Keeling

Application reference number (where applicable) n/a

Name of activity Fairport House Jetty and Pontoon

Brief description of activity Installation of tubular steel piles to support jetty and restrain pontoon. Removal of existing pontoon.

Location of activity (central point XY coordinates or national grid reference)

449244,109230

Footprint of activity (ha) 55m2 (0.0055 ha)

Timings of activity (including start and finish dates) Dependent upon licence issue

Extent of activity (for example size, scale frequency, expected volumes of output or discharge)

One off installation along with removal of structure for mitigation

Use or release of chemicals (state which ones) No

Water body1 Description, notes or more information

WFD water body name Southampton Water

Water body ID GB520704202800

River basin district name South East

Water body type (estuarine or coastal) Transitional

Water body total area (ha) 3091.32

Overall water body status (2015) Moderate

Ecological status Moderate

Chemical status Fail

Target water body status and deadline Moderate by 2015

Hydromorphology status of water body Supports good by 2015

Heavily modified water body and for what use Yes


Higher sensitivity habitats present Yes - saltmarsh

Lower sensitivity habitats present Yes – soft sediment

Phytoplankton status High with good by 2015

History of harmful algae No

WFD protected areas within 2km Yes

Specific risk to receptors -

Section 1: Hydromorphology

Consider if hydromorphology is at risk from your activity.

Use the water body summary table to find out the hydromorphology status of the water body, if it is

classed as heavily modified and for what use.

Consider if your activity: Yes No Hydromorphology risk issue(s)

Could impact on the hydromorphology (for example morphology or tidal patterns) of a water body at high status

Requires impact assessment

Impact assessment not required

No

Could significantly impact the hydromorphology of any water body



No

Is in a water body that is heavily modified for the same use as your activity



No

Record the findings for hydromorphology and go to section 2: biology.

Section 2: Biology

Habitats

Consider if habitats are at risk from your activity.

Use the water body summary table and Magic maps, or other sources of information if available, to

find the location and size of these habitats.

Higher sensitivity habitats 2 Lower sensitivity habitats 3

chalk reef cobbles, gravel and shingle

clam, cockle and oyster beds intertidal soft sediments like sand and mud

intertidal seagrass rocky shore

maerl subtidal boulder fields


mussel beds, including blue and horse mussel subtidal rocky reef

polychaete reef subtidal soft sediments like sand and mud

saltmarsh

subtidal kelp beds

subtidal seagrass

2 Higher sensitivity habitats have a low resistance to, and recovery rate, from human pressures. 3 Lower sensitivity habitats have a medium to high resistance to, and recovery rate from, human pressures.

Consider if the footprint4 of your activity is:

Yes No Biology habitats

risk issue(s)

0.5km2 or larger

Yes to one or more – requires impact assessment

No to all – impact assessment not required

No

1% or more of the water body’s area No

Within 500m of any higher sensitivity habitat

Yes

1% or more of any lower sensitivity habitat

No

4 Note that a footprint may also be a temperature or sediment plume. For dredging activity, a footprint is 1.5 times the dredge area.

Fish

Consider if fish are at risk from your activity, but only if your activity is in an estuary or could affect

fish in or entering an estuary.

Consider if your activity: Yes No Biology fish risk

issue(s)

Is in an estuary and could affect fish in the estuary, outside the estuary but could delay or prevent fish entering it or could affect fish migrating through the estuary

Continue with questions

Go to next section No

Could impact on normal fish behaviour like movement, migration or spawning (for example creating a physical barrier, noise, chemical change or a change in depth or flow)



No

Could cause entrainment or impingement of fish



No


Record the findings for biology habitats and fish and go to section 3: water quality.

Section 3: Water quality

Consider if water quality is at risk from your activity.

Use the water body summary table to find information on phytoplankton status and harmful algae.

Consider if your activity: Yes No Water quality

risk issue(s)

Could affect water clarity, temperature, salinity, oxygen levels, nutrients or microbial patterns continuously for longer than a spring neap tidal cycle (about 14 days)



No

Is in a water body with a phytoplankton status of moderate, poor or bad



No

Is in a water body with a history of harmful algae



No

Consider if water quality is at risk from your activity through the use, release or disturbance of

chemicals.

If your activity uses or releases chemicals (for example through sediment disturbance or building works) consider if:

Yes No Water quality

risk issue(s)

The chemicals are on the Environmental Quality Standards Directive (EQSD) list



No

It disturbs sediment with contaminants above Cefas Action Level 1



No

If your activity has a mixing zone (like a discharge pipeline or outfall) consider if:

Yes No Water quality

risk issue(s)

The chemicals released are on the Environmental Quality Standards Directive (EQSD) list

Requires impact assessment5


No

5 Carry out your impact assessment using the Environment Agency’s surface water pollution risk assessment guidance, part of Environmental Permitting Regulations guidance.


Record the findings for water quality go on to section 4: WFD protected areas.

Section 4: WFD protected areas

Consider if WFD protected areas are at risk from your activity. These include:

special areas of conservation (SAC) bathing waters

special protection areas (SPA) nutrient sensitive areas

shellfish waters

Use Magic maps to find information on the location of protected areas in your water body (and

adjacent water bodies) within 2km of your activity.

Consider if your activity is: Yes No Protected areas risk issue(s)

Within 2km of any WFD protected area6



Yes

6 Note that a regulator can extend the 2km boundary if your activity has an especially high environmental risk.

Record the findings for WFD protected areas and go to section 5: invasive non-native species.

Section 5: Invasive non-native species (INNS)

Consider if there is a risk your activity could introduce or spread INNS.

Risks of introducing or spreading INNS include:

materials or equipment that have come from, had use in or travelled through other water

bodies

activities that help spread existing INNS, either within the immediate water body or other

water bodies

Consider if your activity could: Yes No INNS risk issue(s)

Introduce or spread INNS Requires impact assessment


No

Summary

Receptor Potential risk to receptor?

Note the risk issue(s) for impact assessment

Hydromorphology No


Biology: habitats Yes Saltmarsh and Soft sediment

Biology: fish No

Water quality No

Protected areas Yes SPA, SAC, SSSI, Ramsar, LNR

Invasive non-native species No

10. WFD Impact Assessment & Mitigation

The assessment has identified potential risks to protected areas and biological habitats.

The proposed works are minor and of small scale and any such risks are considered to be low.

The installation works are over an intertidal and subtidal area in an area of existing high activity

by leisure vessels. In themselves the works and operation will have no significant impact on the

habitats nor the protected areas.

However, it is good practice to provide mitigation where possible to enhance the receptor areas.

As such the following mitigation measures are proposed:

The access jetty is elevated so no part will rest on the inter tidal habitat. This has the

advantage that light levels will be similar to those at present.

The decking on the access jetty will be of a grp grid style as this affords significantly

increased light penetration to the habitat. This is an approach that has been employed

for these reasons elsewhere.

The actual physical loss of inter tidal habit is from the jetty support piles and represents an

area of approximately 0.25m2 assuming an area of loss of Ø200mm for each support pile.

To provide additional mitigation for this small loss it is proposed to remove an existing

floating pontoon (which dries out) as shown on drawing 10549/4. This pontoon has an

area of 9m2 (excluding any moored vessel) which is far in excess of the loss.

As a result of the pontoon removal there will be a significant reduction in levels of human

activity in the main part of the saltmarsh area as vessel access will be relocated.

Marine piling and works to be undertaken over high water periods. This maximises the

distance to any feeding wildfowl. This is an approach that is widely accepted.

Marine piling to be undertaken using vibro-piling methods and this minimises any impact

and is also accepted good practice.

In the event that the marine piling requires percussion methods to reach design level

(considered unlikely) then the standard soft-start process will be employed.

Marine piling will only be undertaken during daylight hours

The land based works will be undertaken using small plant working on crawler mats to

protect the habitat. This is also standard practice and a widely accepted approach.


11. Summary

The proposed works are relatively small in scale and the floating pontoon is similar to many

elsewhere in this river.

The works have been designed with minimal environmental impact as a major consideration. The

designed in mitigation and accompanying removal produces a significant net benefit to the

protected areas.

The location of the works is in an already active area and will produce no increase in impact.

By following EA guidance and providing significant mitigation it is concluded that the proposal will

have no negative impact on the water body or any protected area.

In terms of each receptor the proposed mitigation will ensure that there is no deterioration of the

area. For the saltmarsh there is a pathway for the area to be improved as a direct result.

.

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fairport house, bursledon, river hamble · 2017. 1. 3. · fairport house, bursledon, river hamble...

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