1 Port Development and the Reuse of Dredged Material in the Stour and Orwell Estuaries Dr Andrew Birchenough Dr Chris Vivian The Centre for Environment, Fisheries & Aquaculture Science UK

2 Harwich Haven SSSI – SSSI – Site of Special Scientific Interest SPA – SPA – Special Protection Area Ramsar - Ramsar - wetlands of international importance Source: HR Wallingford

3 Harwich Haven Ports and Development Approach Channel Deepening ( )Approach Channel Deepening ( ) –Port of Felixstowe & Harwich International Port Capital dredge to improve navigationCapital dredge to improve navigation –-12.5m CD to -14.5m CD –18Mm 3 of dredged material (mud, sand gravel, clay) Subsequent port development projects e.g.Subsequent port development projects e.g. Trinity III Terminal – completed Felixstowe South Redevelopment – completed Bathside Bay - consented

4 Environmental Impact AssessmentEnvironmental Impact Assessment ‘Appropriate Assessment’‘Appropriate Assessment’ –Reg 48 Conservation (Natural habitats &c.) Regulations –Assess implications of proposed development for the designated status of ‘European sites’ (SPA). –Drives the need to develop appropriate mitigation and compensation measures in light of predicted effects. Environmental Assessment of Projects

5 Effects of Port Development & Capital Dredging Projects Effects on tidal propagationEffects on tidal propagation –Change in cross sectional area of an estuary system can change the way a tidal wave propagates –Increase or decrease in intertidal exposure Effects on erosion/accretion rates of intertidal areasEffects on erosion/accretion rates of intertidal areas –Wave reflection –Increasing depths of dredged channels –Changes to current speed or direction

6 Approach Channel Deepening Effects on 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. Mitigation Compensation

Mitigation and Compensation Measures Required to gain the necessary consents for development projects to offset the impacts on the estuarine systemRequired to gain the necessary consents for development projects to offset the impacts on the estuarine system Also a requirement under national and international legislation to re-use dredged material, disposal at sea last optionAlso a requirement under national and international legislation to re-use dredged material, disposal at sea last option A number of mitigation and compensation measures have been employed on Stour and OrwellA number of mitigation and compensation measures have been employed on Stour and Orwell 7 Source: Suffolk Coasts and Heaths ANOB

8 Sediment Replacement (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 RechargeWater Column Recharge Source: Harwich Haven Authority

–Maintenance dredgings are discharged from the dredger at certain defined locations within the estuary system adjacent to intertidal areas –Redistribute sediment to provide an increased supply to intertidal areas –Deposits made under specific tidal conditions that encourage material to disperse over intertidal areas 9 Water Column Recharge Source: Harwich Haven Authority

10 Managed Realignment (Compensatory Measure) Compensating for unmitigable ‘loss’ of intertidal areaCompensating for unmitigable ‘loss’ of intertidal area Managed RealignmentManaged Realignment –Creation of 16.5 ha of additional intertidal area on the Orwell estuary as compensation for the effects of the Approach Channel Deepening Source: Harwich Haven Authority

11 Habitat enhancement and protection Habitat enhancement schemes –Higher ecological value intertidal habitat –Increased stability of flood defences Source: Harwich Haven Authority

Management Of The Mitigation And Monitoring 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 Compliance Monitoring Report’To assess compliance with those commitments and annual ‘Compliance Monitoring Report’ is produced Annual Report’In addition an ‘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 Regulators GroupProcess overseen by a Regulators Group 12

Management Of The Mitigation And Monitoring Commitments Regulators / Advisors GroupRegulators / 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. 13

For more information Chris Vivian Andrew Birchenough Harwich Haven Authority Information on the estuaries, Regulators Group and links to the Annual Reports ( 14