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Port Development and the Reuse of Port Development and the Reuse of Dredged Material in the Stour and Orwell Dredged Material in the Stour and Orwell

EstuariesEstuaries

Dr Andrew BirchenoughDr Andrew Birchenough

Dr Chris VivianDr Chris Vivian

The Centre for Environment, Fisheries & Aquaculture ScienceThe Centre for Environment, Fisheries & Aquaculture Science

UKUK

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Harwich HavenHarwich Haven

SSSI – SSSI – Site of Special Scientific Interest

SPA – SPA – Special Protection Area

Ramsar - Ramsar - wetlands of international importance

Source: HR Wallingford

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Harwich Haven Ports and DevelopmentHarwich Haven Ports and Development

• Approach Channel Deepening (1998-2000)Approach Channel Deepening (1998-2000)– Port of Felixstowe & Harwich International Port

• Capital dredge to improve navigationCapital dredge to improve navigation– -12.5m CD to -14.5m CD– 18Mm3 of dredged material (mud, sand gravel, clay)

• Subsequent port development projects e.g. Subsequent port development projects e.g. Trinity III Terminal – completedFelixstowe South Redevelopment – completed Bathside Bay - consented

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• Environmental Impact AssessmentEnvironmental Impact Assessment

• ‘‘Appropriate Assessment’Appropriate Assessment’– Reg 48 Conservation (Natural habitats &c.) Regulations Reg 48 Conservation (Natural habitats &c.) Regulations

1994.1994.

– Assess implications of proposed development for the Assess implications of proposed development for the designated status of ‘European sites’ (SPA).designated status of ‘European sites’ (SPA).

– Drives the need to develop appropriate Drives the need to develop appropriate mitigation mitigation andand compensation measurescompensation measures in light of predicted effects. in light of predicted effects.

Environmental Assessment of Projects Environmental Assessment of Projects

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Effects of Port Development & Capital Effects of Port Development & Capital Dredging ProjectsDredging Projects

• Effects on tidal propagationEffects on tidal propagation– Change in cross sectional area of an estuary system can Change in cross sectional area of an estuary system can

change the way a tidal wave propagates change the way a tidal wave propagates – Increase or decrease in intertidal exposureIncrease or decrease in intertidal exposure

• Effects on erosion/accretion rates of intertidal Effects on erosion/accretion rates of intertidal areasareas– Wave reflectionWave reflection– Increasing depths of dredged channelsIncreasing depths of dredged channels– Changes to current speed or directionChanges to current speed or direction

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Approach Channel Deepening Approach Channel Deepening Effects Effects on hydraulic and sedimentary regimeon hydraulic and sedimentary regime

• Increase in intertidal erosionIncrease in intertidal erosion– Approx. 2.5ha yr –1

– Muddy material trapped in deepened channel.– Maintenance dredging result in fine material being lost

from the estuary system.

• Decrease in tidal rangeDecrease in tidal range– Decrease in exposure of approx. 4ha intertidal area.

MitigationMitigation

CompensationCompensation

Mitigation and Compensation MeasuresMitigation and Compensation Measures

• Required to gain the necessary consents for development Required to gain the necessary consents for development projects to offset the impacts on the estuarine systemprojects to offset the impacts on the estuarine system

• Also a requirement under national and international Also a requirement under national and international legislation to re-use dredged material, disposal at sea last legislation to re-use dredged material, disposal at sea last option option

• A number of mitigation and compensation measures have A number of mitigation and compensation measures have been employed on Stour and Orwellbeen employed on Stour and Orwell

7Source: Suffolk Coasts and Heaths ANOB

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Sediment ReplacementSediment Replacement(mitigation measures)(mitigation measures)

• Subtidal placement of fine materialSubtidal placement of fine material– Fine sediments that were dredged during the maintenance

dredging campaigns have been placed on the seabed and act as a feed of material into the estuary system

• Water Column Recharge Water Column Recharge

Source: Harwich Haven AuthoritySource: Harwich Haven Authority

– Maintenance dredgings are discharged from the dredger at certain Maintenance dredgings are discharged from the dredger at certain defined locations within the estuary system adjacent to intertidal areas defined locations within the estuary system adjacent to intertidal areas

– Redistribute sediment to provide an increased supply to intertidal areasRedistribute sediment to provide an increased supply to intertidal areas

– Deposits made under specific tidal conditions that encourage material to Deposits made under specific tidal conditions that encourage material to disperse over intertidal areas disperse over intertidal areas

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Water Column RechargeWater Column Recharge

Source: Harwich Haven Authority

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Managed RealignmentManaged Realignment(Compensatory Measure)(Compensatory Measure)

• Compensating for Compensating for unmitigable ‘loss’ of unmitigable ‘loss’ of intertidal areaintertidal area

• Managed RealignmentManaged Realignment– Creation of 16.5 ha of additional Creation of 16.5 ha of additional

intertidal area on the Orwell intertidal area on the Orwell estuary as compensation for the estuary as compensation for the effects of the Approach Channel effects of the Approach Channel Deepening Deepening

Source: Harwich Haven Authority

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Habitat enhancement and protectionHabitat enhancement and protection

• Habitat enhancement schemes– Higher ecological value intertidal habitat – Increased stability of flood defences

Source: Harwich Haven Authority

Source: Harwich Haven Authority

Management Of The Mitigation And Management Of The Mitigation And Monitoring CommitmentsMonitoring Commitments

• Large number of mitigation and monitoring commitments required through the port development projects

• Harwich Haven Authority (HHA) Harwich Haven Authority (HHA) the port authority are responsible for:– compliance with the actions set out in the compensation packages, – the mitigation measures proposed as part of the EIA process and – the conditions of consents for development

• To assess compliance with those commitments and annual ‘Compliance Monitoring Compliance Monitoring Report’ Report’ is produced

• In addition an ‘Annual Report’ Annual Report’ is produced which– details the findings of the research and monitoring that has been undertaken during

the previous year – considers the ongoing consequences, if any, of development for the health, state

and integrity of the estuarine system

• Process overseen by a Regulators GroupRegulators Group

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Management Of The Mitigation And Management Of The Mitigation And Monitoring CommitmentsMonitoring Commitments

• Regulators / Advisors Group Regulators / Advisors Group – Established with the authority to make decisions regarding the

refinement of the mitigation and monitoring programme

– Comprises of regulators Marine Management Organisation Natural England, Environment Agency and non-statutory organisations.

– Co-ordinate all mitigation and monitoring activities in the estuary system.

– Open exchange of information and the establishment of a consultative forum.

– A culture of shared responsibility, between operators, regulators and NGOs, has consequently arisen.

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For more information For more information

• Chris Vivian (chris.vivian@cefas.co.uk)

• Andrew Birchenough (andrew.birchenough@cefas.co.uk)

• Harwich Haven Authority

Information on the estuaries, Regulators Group and links to the Annual Reports

(http://www.hha.co.uk/index.html)

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