Rame Head Environmental Impact study: Review of Evidence
Report to Marine Management Organisation
Institute of Estuarine and Coastal Studies University of Hull
25th February, 2011
Author(s): Michael Elliott & Krysia Mazik
Report: YBB168-F-2011
Institute of Estuarine & Coastal Studies (IECS) The University of Hull Cottingham Road Hull HU6 7RX UK
Tel: +44 (0)1482 464120 Fax: +44 (0)1482 464130
E-mail: [email protected]
Web site: http://www.hull.ac.uk/iecs
Client: Marine Management Organisation
Rame Head Environmental Impact study: Review of Evidence
Reference No: YBB168-F-2011
For and on behalf of the Institute of Estuarine and Coastal Studies
Approved by: Nick Cutts Signed Position: Deputy Director Date: 25th February, 2011
This report has been prepared by the Institute of Estuarine and Coastal Studies, with all reasonable care, skill and attention to detail as set within the terms of the Contract with the client.
We disclaim any responsibility to the client and others in respect of any matters outside the scope of the above.
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Rame Head Environmental Impact study: review of evidence Client: Marine Management Organisation
TABLE OF CONTENTS
TABLE OF CONTENTS ...... I
1. EXECUTIVE SUMMARY ...... 1
2. INTRODUCTION...... 7 2.1. Background...... 7 2.1.1. Rame Head ...... 7 2.2. Aims and objectives...... 9 2.3. Approach ...... 10
3. SELECTION OF DISPOSAL SITES, REGULATION AND MONITORING OF DISPOSAL AT SEA...... 12 3.1. Site selection ...... 12 3.2. Regulation and Licensing ...... 12 3.3. FEPA Licence conditions for the Rame Head disposal site ...... 13 3.4. Monitoring and Management ...... 16 3.4.1. Management of disposal at sea – Underlying Principles ...... 17 3.4.2. Cefas monitoring and research ...... 20
4. DREDGING PRACTICES IN THE PLYMOUTH AREA AND DISPOSAL PRACTICES AT RAME HEAD. THE LOCAL CONTEXT...... 24 4.1 Dredging practices ...... 24 4.2. Tamar and Plymouth Sound Estuaries Complex and the TECF Dredging Protocol 25 4.3. Whitsand Bay and the Rame head Disposal site ...... 26 4.3.1. Disposal activities ...... 26
5. REVIEW OF EVIDENCE ...... 29 5.1. Hydrodynamics and sediment dynamics in the Rame Head – Whitsand Bay area. 29 5.1.1. Current Patterns and Wave Climate ...... 29 5.1.2. Sediment Transport and Behaviour of Material at the Disposal Site ...... 33 5.1.3. Sediment Characteristics within and around the Disposal Site...... 38 5.1.4. Turbidity and siltation ...... 39 5.1.5. Increased Turbidity and Siltation at the HMS Scylla Wreck Dive Site ...... 40 5.1.6. Siltation of the Beach and Rocky Reefs at the Eastern Side of Whitsand Bay (Polhawn Cove)...... 41 5.2. Contaminants in Sediments ...... 43 5.2.1. METALS ...... 45 5.2.2. Organometals ...... 47 5.2.3. Polycyclic aromatic hydrocarbons (PAH) ...... 48 5.2.4. Synthetic organics ...... 48 5.2.5. Radionuclides ...... 49 5.2.6. Recommendations ...... 50 5.3. Litter on the beach and at the dive sites ...... 50 5.4. Sediment microbial health - Beggiatoa ...... 51
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5.5. Ecological understanding ...... 52 5.5.1. Impacts on the Marine Benthic Communities ...... 52 5.5.2. Sediment bioassays ...... 53 5.5.3. Cellular bioassays and contaminant concentrations in mussel tissue (Mytilus spp.) ...... 54 5.5.4. Health of Marine Organisms ...... 56 5.5.5. Colonisation on HMS Scylla ...... 56 5.5.6. FISH ...... 57 5.6. Socio-economic aspects and impact on the local economy ...... 59 5.7. Public health issues, aesthetic impacts and public perceptions ...... 61 5.8. Timing of disposal ...... 64 5.9. Alternatives to disposal at Rame Head ...... 64 5.9.1. Site Relocation ...... 64 5.9.2. Alternatives to disposal at sea...... 65 5.10. Adequacy of the Science & Monitoring...... 67
6. DISCUSSION, RECOMMENDATIONS AND CONCLUSIONS ...... 70 6.1. Future Practices and Recommendations ...... 79 6.2. Conclusions ...... 80
7. REFERENCES ...... 82
APPENDICES ...... 88 Appendix 1. Acknowledgements ...... 88 Appendix 2. Reasearch and monitoring studies at Rame Head and Whitsand Bay...... 90 Appendix 3. Metal concentrations ...... 92 A3.1 Arsenic ...... 92 A3.2 Cadmium ...... 94 A3.3 Chromium ...... 96 A3.4 Copper ...... 98 A3.5. Mercury ...... 100 A3.6. Lead ...... 102 A3.6. Zinc ...... 104
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1. EXECUTIVE SUMMARY
Dredging, and the disposal of dredged material, are activities essential to the maintenance of navigable waterways and to the construction and operating of ports and harbours. The activities must comply with the OSPAR Convention, relating to north-western Europe, and the global London Protocol of 1972. The disposal of dredged material at sea is subject to strict regulation under licences granted under the Food & Environmental Protection Act 1985, the Coast Protection Act 1949 (CPA) and/or the Marine Works (Environmental Impact Assessment) Regulations 2007. These controls cover maintenance (relocation of settled material from channels and berths) and capital (creation of new harbour facilities or deeper channels) dredging.
The Rame Head dredged material disposal site, located in Whitsand Bay, off the SE coast of Cornwall, receives dredgings from the Tamar Estuary, including the channel, Dockyard and marina areas of Plymouth. The disposal site has been in use for over a century and has received materials from before present controls were implemented. Compared to many UK disposal sites, this site is not only very close to the coast but also to an area significantly dependent on tourism to support the local economy. Local stakeholders have raised concerns over the environmental impacts of the disposal activity and the impact on the local economy. Most significantly, the death of two divers on HMS Scylla was alleged to be due to poor water clarity and reduced visibility resulting from siltation within the vessel. Accordingly, these concerns have led to multidisciplinary monitoring of sediment transport, sediment contamination, particle size distribution and marine ecology carried out by Cefas (Centre for Fisheries and Aquacultural Sciences) since 2001. While this monitoring has cost an estimated £850-900k, and been accompanied by other studies from the University of Plymouth, the Marine Biological Association and the Plymouth Marine Laboratory, local stakeholders have concerns regarding the validity, objectivity and adequacy of this work. These concerns are sufficiently serious to have attracted the attention of the media and local Government.
Although any marine activity has the potential for environmental consequences, the economic importance of maintaining ports, harbours and navigable waterways is acknowledged, together with the importance of waterside developments in Plymouth which lead to the requirement for dredging. Such activities provide business, employment and tourism opportunities to the city. Applications for the renewal of dredging and disposal licenses are currently under consideration but due to the importance of the socio-economic and environmental issues which have been raised, the Marine Management Organisation (MMO) has requested an independent and objective review of the scientific data generated through monitoring and academic studies, together with information and views provided by local stakeholders.
The purpose of this review was to determine whether the original conditions under which licenses for disposal were granted remain valid and that the environmental effects remain tolerable. The review, carried out by Professor Mike Elliott and Dr Krysia Mazik of the Institute of Estuarine & Coastal Studies at the University of Hull, has focussed on the adequacy of the monitoring and the validity of the concerns.
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Concerns raised and an assessment of their significance
1. Increased siltation and turbidity at the HMS Scylla dive site is believed to have resulted in poor visibility and associated problems with safety and quality of the diving experience: As would be expected, silt has accumulated in areas of the vessel where there is little water movement. No evidence of increased turbidity at the disposal site or at the HMS Scylla site, in relation to disposal activities, has been found. Hydrographic and sediment transport modelling studies indicate that significant deposition of sediments originating from the disposal site is unlikely to occur on or around the vessel and that scour around the vessel may be a source of silt. HMS Scylla has been colonised by a mature invertebrate and algal community which is not indicative of excessive levels of silt in the water column. The number of comments from divers visiting the wrecks in the area does not indicate that they are deterred from diving in Whitsand Bay.
2. Siltation of the beach and rocky reefs at the eastern side of Whitsand Bay (Polhawn Cove) is reported to have significantly impacted the reef communities: Comparative photographs were provided to demonstrate the difference between the biological quality of the reefs in Heybrook Bay (east of Plymouth Sound) and Polhawn Cove (west of Plymouth Sound). Modelling studies indicate the potential for the onshore transport of sediments but also indicate that significant accumulation is unlikely in the long term. Furthermore, the reefs to the west of Plymouth Sound are naturally less diverse than those in the east due to residual current direction which is generally to the west. As a result, reduced salinity water and sediments are transported to the west and modelling studies indicate a potential for the deposition of sediment and contaminants within Whitsand Bay, particularly the eastern side (Polhawn Cove) where the degraded reefs have been reported. Therefore, silt is likely to accumulate in Polhawn Cove to some extent, regardless of the disposal activity. Scientific studies specifically investigating reef quality have not been carried out.
3. Sediment contamination is believed to be a problem, particularly in the Polhawn Cove area in the east of Whitsand Bay: Spatial comparison of contaminant data does indicate elevated concentrations (of some contaminants) in this area and Cefas acknowledge this. However, analysis (of metals) is carried out on the fine fraction of the sediments only and this represents a small proportion of the sediment fabric. Therefore, metal concentrations should be considered an overestimate. Elevated concentrations of polycyclic aromatic hydrocarbons (PAH) were recorded in Polhawn Cove and although close to guideline values, these are not exceeded. The source of this contamination needs to be identified but, based on hydrodynamic models, the natural transport of sediments from Plymouth Sound into Polhawn Cove should be considered as a potential source. Furthermore, the natural inputs of contaminants (particularly metals) must be acknowledged.
4. Widespread concerns over the amount of litter on the seabed and on the beaches of Whitsand Bay: There is no doubt that litter accumulates on the beaches in this area. Whilst this has not been specifically studied by Cefas, evidence has been often presented by those who visit Whitsand Bay. Various litter items have been collected or noted which relate directly to the Naval Dockyard and these may have entered Whitsand Bay as a result of dredge disposal operations. However, large quantities of other types of
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litter have been recorded. There are no detectable ecological impacts of the litter and, although possible, there are no specific records of harm to marine life. However, the aesthetic impacts of litter are unacceptable even though there is no simple way of removing it from beaches other than by hand. It is recommended that the dredging companies continue to be rigorous about screening for litter prior to disposal.
5. Widespread concern over the impacts of dredged material disposal on marine life: Reduced species diversity and abundance of organisms have been reported from within the disposal site and within the immediate vicinity but no impacts have been reported farther afield. Therefore, any impacts are low level and isolated. However, the variable nature of the sea bed makes difficult the detection of impacts directly associated with dredged material disposal. Despite this, the characteristic species of a degraded seabed, which would include pollution and disturbance tolerant species, are not present. The observation of the sulphur-reducing bacteria Beggiatoa, indicative of organic enrichment on the seabed, cannot be attributed to the disposal and may be a feature of natural subsea peat deposits. The rocky areas support predatory echinoderms, cup corals, the pink sea fan (Eunicella verrucosa) and various mobile crustaceans and fish but there is insufficient evidence to indicate whether fish and crabs have declined in the area as a result of the disposal activity. Similarly, there is insufficient evidence to link any decline in the populations of commercial fish to the disposal activity. It is of note that there have been large scale changes in fish stocks due to overfishing and that southerly species are now being recorded in Cornish waters as a result of climate change.
6. Concerns regarding the adequacy of the monitoring: The extensive monitoring has been at a high cost but justified using priorities based on the need for environmental protection and public concern. Approximately 20% of the Cefas total budget available for monitoring the impacts of dredge disposal has been assigned to the Rame Head site. Overall, the science has been adequate and proportionate to the issues being addressed. In addition to routine monitoring, further, detailed studies have been carried out by Cefas and other institutions. These have focussed on sediment transport modelling, turbidity monitoring, contaminants monitoring and studies on the impacts of pollutants. These studies have used accepted procedures and protocols. None of these studies has identified any adverse impacts outside the disposal area directly attributable to the disposal activities at Rame Head. Cefas staff have engaged with the stakeholders when requested and fulfilled their duties as government advisors although they have not always fully communicated their results, or explained the licensing process or the constraints of detecting effects. This has exacerbated local concern. Cefas have attempted to summarise their findings and have their work examined in peer-review scientific publications although this needs improvement. Certain stakeholders should be congratulated for raising concerns about the disposal activity but they appear to be selective in their use of the available science and do not always appreciate the interpretation and the value of the evidence. Those concerned need to question the provenance of the available information while realising the limitations of the science. However, communication between the various institutions was inadequate and the reports produced by Cefas are brief and may not have enabled the public to fully understand the research outcomes. Furthermore, the use of a standard approach can be criticised for not being sufficiently site-specific in formulating and addressing testable hypotheses for the area.
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7. Socio-economic concerns: Several issues relating to the potential for loss of income if current dredging and disposal practices were allowed to continue were highlighted. Similarly, significant changes or removal of the dredging license may also have negative economic consequences in a region reliant on the maintenance of its waterways to support regeneration and development work. Drawing attention to the issue, through campaigning for changes in dredging and disposal practise is also thought to negatively impact upon local businesses. The disposal activity is largely restricted to the winter months and the licence conditions adopt best-practice to minimise the environmental impacts. There may be the case for a minor adjustment to the disposal site by moving it slightly further offshore over a rocky reef into slightly deeper water. Some stakeholders consider that it is unfortunate that the local media are more willing to report perceived problems rather than carry out objective reporting.
8. Public health: No Serious public health issues were identified although the source of the PAH contamination in Polhawn Cove may need to be identified even if it appears to be unrelated to the disposal operation. Silt accumulation on HMS Scylla was just one of several health and safety concerns associated with diving on the wreck. It is alleged to have caused the death of 2 divers who became disorientated as a result of poor visibility caused by the resuspension of fine sediments. However, there is no direct evidence to suggest that this silt has accumulated as a result of the disposal operation. Furthermore, numerous other hazards have been documented which pose an equal or more significant risk than poor visibility.
Conclusions and recommendations.
The impacts of dredge disposal are evident at the Rame Head site but are low level and not widespread. Based on the general nature of marine impacts due to human activities, the changes observed at Rame Head due to dredged material disposal are regarded as acceptable. However, it is recommended that screening for litter prior to disposal continues as rigorously as possible and that quayside practices are monitored to reduce waste. The source of the PAH contamination should be investigated and studies to determine the fate of sediments and contaminants transported out of Plymouth Sound would be beneficial.
Whilst there may be impacts associated with current disposal practices, it is thought that much of the contamination (litter and chemical) may be the result of historical disposal activity. With the exception of small scale changes in the benthic ecology within and adjacent to the disposal site, there is no evidence to directly attribute any other impacts to the disposal activity. Therefore, the licence conditions are considered valid and there is little economic or environmental justification for moving the disposal site further offshore or for considering on shore disposal options. A slight adjustment to the boundary of the licence area, enabling disposal in a rocky area with greater potential for offshore dispersal may be beneficial.
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The conclusions of the review can be summarised as follows:
The disposal site shows limited evidence of the impact of disposal, via contamination and ecological change and is rightly regarded as a dispersing site.
The present licensing regime is designed to ensure that contaminated dredged materials are not disposed of to sea and that the dredged material does not have a toxic component.
The scientific studies carried out in the area by Cefas and others have produced a large amount of information, data and understanding and the surveys (their components and funding) have been proportionate to the environmental issues being addressed; they have followed the accepted international guidelines for monitoring dredged-material disposal grounds.
There have been failings in the way the findings and background to the dredging and disposal operations have been communicated to stakeholders.
The concerns regarding litter at the disposal site and in adjacent areas are warranted and based on good evidence of the type of litter encountered although much of this appears historical and from before controls were in place.
The beach litter is from all sources irrespective of the disposal of dredging and is thus part of a wider problem.
It is considered more environmentally sustainable to keep licensing the existing site than choose another site.
Despite perceptions of environmental problems, moving the site further offshore would have adverse environmental and economic repercussions and there are no beneficial onshore uses of the dredged material.
Recommendations for Further Work
The rigorous scientific assessments of the hydrography and sedimentology of the Rame Head-Whitsand Bay area have concentrated on the disposal ground and the inshore area but there needs to be a wide scale assessment of silt dispersed over the wider offshore area.
Research into sediment dynamics and the fate of suspended sediments coming from the estuarine areas would give valuable information for future studies of disposal grounds here and elsewhere.
Remote grab and core sampling and seabed acoustic techniques have been used to good effect but more targeted and precise sampling, including diver surveys accompanied by surveys to obtain more video footage, would be of benefit.
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Cefas have placed little emphasis on understanding the ecological quality of the rocky areas, and hence they have been unable to counter comments from the stakeholders with concerns regarding the quality of the reef areas. The local diving fraternity could be used to obtain more rigorous scientific information.
The dredging company should ensure that its controls on litter entering the dredging barge hopper should be as effective as possible. However, it is acknowledged that screening does occur and that smaller grids cannot be used without an economic and logistical cost.
There should also be checks on quay-based practices to minimise waste entering the system, following IMO guidelines.
The litter appears to have an aesthetic impact rather than an ecological one such that a code of practice asking the large number of divers to retrieve dangerous pieces of litter would be of benefit and may allow them to feel they are contributing to the solution.
The HMS Scylla as a dive site and artificial reef can be regarded as a success and does not show signs of being affected by turbid conditions. However, its interior will scavenge silts and divers must be made aware of the hazards of this, together with the hazards associated with deterioration of the vessel.
The disposal monitoring has benefitted from the high number of marine scientists in the Plymouth area and it has provided education opportunities but the university supervisors have a duty to present a balanced view to their students and ensure that external lecturers are also giving a balanced view. The projects must have an open and objective rigour.
The Tamar Estuaries Consultative Forum is to be congratulated in taking the initiative to devise a dredging protocol but they are encouraged to include repercussions for the wider Rame Head area, disposal site and Whitsand Bay.
A detailed research project would be valuable to provide further support for the environmental and economic costs and benefits of the different disposal options.
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2. INTRODUCTION
2.1. Background
Dredging and the disposal of dredged material are regarded as essential activities with respect to the maintenance of navigable waterways, ports/harbours and construction work and are permitted under the OSPAR Convention (www.ospar.org), relating to north-western Europe, and under the global London Convention of 1972 (www.londonconvention.org) (Okada et al., 2009). Following dredging, there are several options for the disposal of the material which must be investigated before disposal at sea can be considered (e.g., beneficial use or landfill) and disposal at sea is subject to strict regulation. There are more than 150 designated disposal sites around the UK (although they are not necessarily all used in any one year), most of which are located in coastal areas (Bolam et al., 2006). Most of the material placed in disposal sites is fine sediment, being composed of soft silts and fine sands, although coarser material, including boulders, may be disposed (Bolam et al., 2009). Disposal sites may be regarded as either dispersing or accreting with the decision on which to use often being taken according to the type of material being placed. The underlying philosophy in the UK has been to use dispersing sites for material deemed to be wholly or predominantly natural sediment, relocated from maintenance dredging, or organic, degradable material which will disperse and be assimilated under the appropriate conditions. With the exception of munitions and highly organic and polluted sewage material (such as that previously disposed of at the Garroch Head ground in the outer Clyde), most material is placed in dispersive grounds.
Regardless of the need for the disposal at sea and the regulations and monitoring surrounding it, environmental effects (which may be positive or negative) are inevitable. Such effects are often (but not always) regarded as positive where the material goes for beneficial use but are largely regarded as negative where disposal at sea takes place (Bolam et al., 2006). Potential negative impacts include smothering of the seabed and resultant impacts on the benthic ecology, changes in water turbidity and impacts on primary production, contamination, changes in bathymetry and the local hydrodynamic regime, the potential for transport and deposition of sediments elsewhere (e.g. on public beaches), litter and other aesthetic impacts (OSPAR Commission, 2009). Such impacts not only affect the local ecology, directly and indirectly, but also have socio-economic effects (Okada et al., 2009). In contrast, positive effects of dredge disposal may include enhanced benthic productivity, resulting in enhanced prey availability for fish, and new habitat availability for colonisation by commercial and other species (Bolam et al., 2006).
2.1.1. RAME HEAD
Dredged material has been disposed of at Rame Head (to the west of Plymouth Sound, Figure 1) for over a century with the main source of material being dredgings from the ports, harbours and navigation channels within the Tamar and Plym estuaries and Plymouth Sound (Cefas, 2005). Until 1972, the site was also used for the disposal of munitions until the disposal of these was moved further offshore (Dr C Vivian, Cefas, pers. comm.) . The Rame Head site is situated at the eastern side of Whitsand Bay, approximately 2 km to the west of Rame Head in SE Cornwall. Compared to many UK disposal sites, this site is not only very close to the coast but also to an area significantly dependent on tourism to support the local economy.
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Figure 1. Location of the Rame Head disposal site within Whitsand Bay.
The disposal activity is clearly visible from land which, together with the fact that Whitsand Bay is a popular tourist beach and a dive site due to the HMS Scylla and James Egan Layne shipwrecks, has led to significant public concern. Several local residents and stakeholders have longstanding concerns and whilst they acknowledge the need for dredging and disposal, they have been campaigning for a change in disposal practice for several years. As such, the issue has received considerable attention from the media and local Government. The list of concerns can be summarised as:
increased turbidity and siltation at the HMS Scylla wreck dive site resulting in poor visibility and associated problems with safety and quality of the diving experience;
siltation of the beach and rocky reefs at the eastern side of Whitsand Bay (Polhawn Cove);
sediment contamination and accumulation of contaminants, particularly at the eastern end of Whitsand Bay;
litter on the beach and on the seabed;
presence of the sulphur-reducing bacteria Beggiatoa;
impacts on marine life, and a reduction in commercial and recreational fishing;
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potential loss of revenue and thus an impact on the local economy. This is due to degradation of the coast, dive sites and areas used for recreational angling, in an area where the income of the local community is largely dependent on tourism and recreation;
inadequate monitoring;
the timing of disposal activity;
public health.
In addition, the interests of local industry and the impacts of changes in disposal practice must be considered. Plymouth is an area of high unemployment and current activities and development proposals, which may require dredging, are beneficial, if not crucial to the local economy. Effective management of dredging and disposal activities therefore requires consideration of both socio-economic and environmental issues and an acceptable balance between the two must be reached. Due to the importance of these issues and the concerns of local stakeholders, the Marine Management Organisation (MMO) has requested an independent review of the existing literature and data which has been generated through previous monitoring campaigns at Rame Head, together with a review of information provided by local stakeholders.
2.2. Aims and objectives.
The present study aimed to be an independent review of the existing literature and data, which have been generated through previous monitoring campaigns at Rame Head, and through observations and records collated by local stakeholders. The review was carried out on behalf of the Marine Management Organisation (MMO). The design and components of the monitoring plan and the validity of the existing evidence were evaluated to determine whether the original conditions under which licences for disposal were granted remain valid and that the environmental effects remain tolerable. The study has the following objectives:
to summarise the legislation and monitoring surrounding the disposal of dredged material and to indicate dredging and disposal practices within the Plymouth Sound area;
to review existing monitoring evidence to assess the validity of existing monitoring data;
to assess sedimentological changes at the Rame Head site over time, compared to pre-disposal conditions, specifically to assess the potential for suspension, settlement and re-distribution of material;
to liaise with local stakeholders to record their views on the disposal activities at the site. This involved three meetings: (1 & 2) to establish views and concerns and (3) to present the findings of the review;
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to identify evidence gaps and, as necessary, recommend further data collection (e.g. parameters not considered under current monitoring activities), modifications to the monitoring or modifications to the licensing conditions if the environmental impacts are considered unacceptable;
to highlight unexpected consequences and future socio-economic and environmental risks likely to be linked to the disposal site with an indication of scale and impact.
2.3. Approach
Information was provided by the MMO, Cefas Lowestoft, consultant reports, published work and material in press (peer-reviewed), unpublished student theses and dissertations (these are not peer-reviewed but are carried out under the guidance of an academic supervisor), ad hoc information, personal submissions and minutes of meetings. Similarly, there are many photographs and a significant amount of video footage of underwater and surface features taken by divers, including the disposal operation/washing of tanks on the dredger. While it is difficult to do justice to that body of information, it is regarded here as ‗soft intelligence‘ which when obtained and used with rigour, becomes a source of hard data and good information.
There is a considerable body of information and it has been presented in many places and on many occasions although much of it appears to be repetitive. There have been concerns regarding the quality of information and the independent/unbiased nature of it, hence the need to triangulate the evidence by checking several sources. There is a strong reliance by some stakeholders on photographic (still and video) evidence but this information has not been catalogued nor can precise dates or locations be given. Furthermore, whilst student dissertations are a valuable source of information, it is often apparent that they have not always been carried out as rigorously or in such an unbiased, objective, scientific manner as is wished. These dissertations have been provided by stakeholders as key pieces of evidence and therefore they have been treated as such. It should be remembered that students are in an early stage of their scientific careers and their work is therefore not expected to be as scientifically sound as that carried out by experienced, practising scientists. Whilst these documents have been carefully read and considered, there were cases where inappropriate conclusions were drawn and hence these documents have not been given equal weight to those written by professionals.
The reviewers visited Plymouth twice in order to meet with local stakeholders and to provide them with an opportunity to present their views and evidence. The first visit on 19/10/2010 involved a visit to the former Coastguard Station, discussions with CoastWatch and a public surgery which was attended by Major Douglas Riley. A further public surgery was held on 16/11/2010 which was attended firstly by Dave Peake and Julie Elworthy, as local interested bodies, and secondly by Richard Cope and Robert Kidd from Westminster Dredging Company. A full list of consultees and local stakeholders is given in Appendix 1.
Discussions were held with the MMO in Newcastle on 27/09/2010 and with Cefas on 15/12/2010 with contributions from Dr Piers Larcombe, Dr Chris Vivian, Dr Stefan Bolam, Claire Mason, Dr Andrew Birchenough and Karema Warr. Further discussions were held with Plymouth Marine Laboratory (Dr Annie Linley, Dr Reg Uncles), the Marine Biological
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Association, Plymouth (Dr Keith Hiscock), MMO (Dr Dickon Howell from MMO Head Office Newcastle and Phil Whitby for MMO Plymouth) and Dr Peter Barham (ex-ABP, now independent).
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3. SELECTION OF DISPOSAL SITES, REGULATION AND MONITORING OF DISPOSAL AT SEA.
3.1. Site selection
In the absence of any statutory control (pre 1974), it is assumed that the disposal site would have been chosen originally with local knowledge, with the agreement of the local Harbour Master and the dredging operators. Disposal sites would have been deemed acceptable in terms of being sufficiently far from the area being dredged such that the dredged material was not immediately returned and re-deposited at the dredged site but not so far that the dredging became uneconomical or unable to keep pace with accretion at the dredging site. Licensing was not originally required nor was there any quality control on the material being sent for disposal. Therefore, both accreting sediment, which may or may not have been contaminated, and litter would have been sent to the disposal site. As the Rame Head site has been in existence for a century, there are no records of how the site was chosen nor of any scientific study of the pre-disposal characteristics (physical, chemical and biological) of the site being carried out. Therefore, there are no baseline data for the disposal site. In the case of Rame Head, it is not known whether a site to the west of the Sound entrance was chosen rather than one to the east because of fears about material returning into the Tamar nor whether local fishing grounds were avoided. Hence, it is assumed that the site was chosen mainly and initially on pragmatic rather than on environmental grounds. However, in common with other UK disposal sites, survey work by Cefas (and its predecessors) since the 1970s have confirmed that the area is a dispersing site and it has been licensed as such (Dr C Vivian, Cefas pers. comm.).
3.2. Regulation and Licensing
Prior to the mid 1960s there were no statutory controls on the disposal of solid materials at sea or on pipeline discharges from the coast or estuaries. There were only limited controls on other discharges from inland and freshwater areas. From the mid 1960s until 1974 there were no statutory controls on disposal at sea but there was an increasing focus on toxic and hazardous waste discharge, usually from industry. There were informal controls within the UK which addressed liquids and solids from industry and limited studies were carried out in relation to impact assessment. There was also some collaboration with industry to minimise adverse effects. Waste munitions from Ministry of Defence establishments could be disposed of to inshore areas (as was the case at Rame Head) but this practice ended in 1972 when the waste was taken offshore for disposal in deeper waters. Prior to the implementation of the 1974 Dumping at Sea Act (DASA), there were no controls on dredged materials, especially maintenance dredging, as these were deemed to be low risk. In addition, naval dockyard operations were exempt from civil environmental legislation until the operations were privatised although informal and voluntary controls were in place (Wells, 2001).
The DASA, 1974, enabled the UK to adopt the global London Dumping Convention 1972 (now the London Convention). DASA was enacted in 1975 and required new and existing sites to be licensed and stipulated that the location of disposal and the volume of material placed there must be recorded. Since then, the disposal of dredged material at sea in the UK has required licensing under the Food and Environmental Protection Act (FEPA), 1985 (Bolam et al., 2006). The FEPA licences stipulate the nature of the material and the amount
Page 12 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact study: review of evidence Client: Marine Management Organisation for disposal, the source activity, the type of disposal, the coordinates of the disposal ground and the type of monitoring required both of the material to be disposed of and the receiving area. The monitoring is carried out or arranged and paid for by the disposal company under the ‗polluter pays principle‘. In 2011, FEPA is expected to be superseded by the Marine and Coastal Access Act, 2009 (Defra, 2010).
3.3. FEPA Licence conditions for the Rame Head disposal site
The dredged material disposal at Rame Head is currently licensed under the Food and Environment Protection Act 1985: part II (as amended) Deposits in the Sea. The main licence is the Licence 33664/10/0, issued by the Marine and Fisheries Agency as the Licensing Authority (and now the Marine Management Organisation (MMO)) to Royal Boskalis Westminster Dredging Co Ltd (as the Licence Holder). Prior to issuing the licences, the MMO consults with statutory and non-statutory consultees as necessary and with the Regulatory Assessment Team within Cefas (Centre for Environment, Fisheries and Aquaculture Sciences, an Executive Agency of the Department for Environment, Food and Rural Affairs, based at Lowestoft).
The licence permits the depositing in the sea of substances or articles as defined in its Schedule. The current licence operates from 05/03/2010 to 08/01/2011 and replaces licence 33664/09/0. It relates to Area Code PL031, Rame Head South (referred to throughout this review at the Rame Head disposal site, Figure 1, 2), for the disposal of 117,333 tonnes of dredged material from maintenance dredging plus tank and hopper washings. Under the licence, the dredging company must record the date and time of departure from the port or site at which the substances or articles are loaded (the dredging site), the time and date of arrival at the disposal site, the position of the vessel no less than every 20 minutes during loading and disposal, the time taken to complete the dredge and disposal cycle, any variations to the programme, the rate of disposal and the weather, sea-state, wind and tidal state throughout deposit operations. Under force majeure, the disposal operation can be altered if the safety of the vessel or crew is at risk.
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Figure 2. Location of the Rame Head disposal site, showing the current and previous licence areas including the sewage sludge disposal ground to the south of Plymouth Sound. Source: Cefas.
The licence has a set of supplementary conditions undertaken by the dredging company and relevant to this review; these are given below, with added explanation:
The Licence Holder must take all reasonable precautions to prevent the disposal of man-made debris (i.e. litter) at sea. This involves screening the dredged material and the resulting litter must be disposed of to land.
Disposal should occur only during ebb tides or at slack water to minimise movement of dredged material landward, thus reflecting current patterns in the disposal area.
There should be a three year dredge plan from which a rolling sampling plan can be agreed with Cefas and dredging areas can be included or excluded for disposal according to the results of ongoing sample analysis. This relates to the obligations by the MMO to ensure that any material which is contaminated above thresholds agreed internationally should not be disposed of at sea.
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Because of the potential for contaminated materials, no material from certain areas in the port shall be disposed of at sea although land-based disposal may be discussed with the Environment Agency. This relates to the fact that some areas of the dockyard and approaches may be more contaminated than others. The depth to be dredged is specified; this relates to the fact that contaminated sediments may be at depth given the previous discharge of polluting materials into the Tamar and the ability of sediments to sequester and store contaminants.
The Licence Holder must liaise with the Environment Agency with regards to new findings from the Dredging Protocol (being produced by the Tamar Estuary Consultative Forum (TECF)), aimed to reduce the impact of dredging on the conservation interests of the estuary, which should be trialled during the forthcoming three-year period.
The Licence Holder must ensure that further pollution prevention methods are implemented to prevent the escape of contaminants into the Plymouth Sound and Estuaries European Marine Site (a Natura 2000 site encompassing the Special Areas of Conservation designated under the EC Habitats & Species Directive). Any resulting pollution of the estuary will be considered an offence under the Water Resources Act 1991, a clause inserted because of concerns with the level of PCB (Polychlorinated Biphenyls) in the sediments at this dredging site.
The Environment Agency does not support wider maintenance dredging operations during the summer period in order to protect migratory fish. However, the Wharf sides and basins can be dredged during the summer as disturbed silts would be restricted to only one side of the estuary leaving the other side of the channel clear for fish to migrate. Any dredging within the estuary channel beyond 50m from the Wharves should occur during the winter months, December to March (inclusive) when migrations are low. This is to protect the fish ecology of the area and reflect the fact that estuaries are migration routes for fishes moving between the sea and freshwaters in either direction for breeding and feeding.
The Environment Agency advise that due to the scale of dredging within the Sound, dredging should only take place during the winter months to avoid adverse impacts on commercial fishery interests. This reflects the fact that a dredged material disposal operation has the potential to either disturb the fisheries or release contaminants thus affecting the quality of the fish and shellfish taken for consumption.
Various supplementary conditions have been appended to licences issued since 2000 (the earliest licence presented to the reviewers) although these are generally specific to the individual licence. These generally refer to the areas where disposal is allowed to take place, areas where dredging with the intention of disposal at sea cannot take place, various health, safety and operational issues and organisations which should be notified of the activity. Whilst the list of supplementary conditions appears to have increased progressively over time, the obligation to take all reasonable precautions to prevent the disposal of man- made debris (i.e. litter) at sea has applied to all licences.
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In addition to the above licensing regime, the dredging and disposal operation and the developments with which they are associated may be subject to other means of assessment, such as Environmental Impact Assessment or Habitat Regulations‘ Appropriate Assessment under the relevant environmental protection acts and EC Directives. Activities outside a European Marine Site (SAC/SPA) but which have potential to influence the conservation objectives of the site may also need to be subject to an Appropriate Assessment under the Conservation of Habitats and Species Regulations, 2010. This will need to be considered in the forthcoming TECF protocol for dredging in estuaries.
The quality of the dredged material has to be tested against recognised and accepted OSPAR standards with the procedure for this being outlined in Cefas (2010). Contamination is assessed against Action Levels and material containing concentrations of contaminants exceeding Action Level 2 is considered unfit for disposal at sea. Material containing contaminant concentrations below Action Level 1 can go to sea and where concentrations are between Action Levels 1 and 2, further assessment is required (Cefas, 2010). The adverse effects of dredged material disposal are further minimised by dredging being prohibited in the period for 4hr before HW and up to HW to prevent material from drifting inshore. There are checks on short-dumping (i.e. disposal before reaching the licensed disposal site) with dredging and disposal information recorded via EMS (Electronic Monitoring System) on dredgers as well as the information from bridge plotters. The licence condition is to spread the material over the area during disposal. Disposal is limited to the area to the south of 52º17‘ within the licensed area, i.e. in deeper water now in 30m contour (on softer sediment).
3.4. Monitoring and Management
The DASA, 1974, required new and existing sites to be licensed and stipulated that the location of disposal and the volume of material placed there must be recorded. However, the licence conditions did not include any requirement for monitoring or assessment of existing sites and impact assessment was only required for new sites. Existing disposal sites were maintained unless there were severe concerns requiring them to be relocated, i.e. there was a policy of not moving sites once they had been used. Initially, the monitoring for disposal sites was mostly performed by the Ministry of Agriculture, Fisheries and Food (MAFF, now Cefas) Laboratory at Burnham on Crouch (producing a set of documents collectively known as the ‗MAFF Yellow reports‘) which addressed the sediment chemical, physical and biological quality of the receiving areas. However, the main assessments were performed on sites of concern, especially those for hazardous and industrial waste (e.g. pulverised fuel ash from coal fired power stations) and urban sewage sludge. Hence the Plymouth sewage sludge disposal site, located further offshore than the Rame Head site, was subject to extensive monitoring (e.g., MAFF, 1989; Cefas, 1993).
The prevailing policy has been to remove large litter items and contaminants at source and send only the clean silt for disposal at sea (contaminated dredged material is either left in situ or disposed of by other means). The incidence of litter, often from diffuse sources, has been more difficult to address and the earliest licence for Rame Head found with a condition requiring the screening out of man-made debris was one issued in 1985 (Dr C Vivian,
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Cefas, pers. comm.). There may have been earlier ones but the Cefas database is only complete from 1985 onwards.
3.4.1. MANAGEMENT OF DISPOSAL AT SEA – UNDERLYING PRINCIPLES
Disposal at sea is subject to a strict regulatory framework which focuses on environmental protection. However, in line with prevailing government policy, the MMO has a corporate objective regarding sustainable development and must therefore take into account the socio-economic aspects of the activity. Accordingly, disposal at sea can be interpreted and managed under the so-called 7-tenets (Table 1) that for the sustainable and acceptable use of the marine area, managers must ensure that the natural science aspects and the societal context are both accounted for but within the prevailing economic, legal and political frameworks.
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Table 1. 7-tenets of successful and sustainable environmental management (from Elliott, 2010, expanded from Elliott & Cutts, 2004; Mee et al., 2008)
Environmentally/ecologically sustainable That the measures will ensure that the ecosystem features and functioning and the fundamental and final ecosystem services are safeguarded, i.e. the dredging and disposal operations will not adversely affect the ecology of either area
Technologically feasible That the methods, techniques and equipment for ecosystem protection are available, i.e. that the method and apparatus of dredging and disposal are suitable
Economically viable That a cost-benefit assessment of the environmental management indicates viability and sustainability, i.e. that the costs of ensuring the viability of the operation and the protection of the environment are acceptable
Socially desirable/tolerable That the environmental management measures are as required or at least are understood and tolerated by society as being required; i.e. that societal benefits involved in the dredging and disposal are delivered, both for the commerce and the aesthetic aspects
Legally permissible That the operations follow relevant regional, national or international agreements and/or statutes which will enable and/or force the management measures to be performed, i.e. that the dredging and disposal are licensed and that the activity does not contravene UK or EU law or international agreements such as obligations under OSPAR or the London Convention.
Administratively achievable That the statutory bodies such as governmental departments, environmental protection and conservation bodies are in place and functioning to enable successful and sustainable management, i.e. that the MMO, Defra, the Environment Agency, Natural England, the Inshore Fisheries and Conservation Agency and all other relevant authorities are competent and capable of managing the dredging and disposal
Politically expedient That the management approaches and philosophies are consistent with the prevailing political climate and have the support of political leaders, i.e. that the sustainable dredging and disposal has political support
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Whilst disposal at sea is strictly regulated in order to protect both the environment and the interests of those using the environment, current management should be compatible with The Ecosystem Approach which aims to protect the ecological functioning of the environment whilst delivering societal needs in a sustainable manner (Elliott, 2010). This approach accepts that society wishes to use the environment and gain benefits and that such uses of the environment can have adverse effects. The Ecosystem Approach sensu stricto (as defined by the UN Convention on Biological Diversity) therefore requires that marine scientists and managers have to take a multidisciplinary approach covering natural and social sciences.
Furthermore, it is essential that robust and defendable science is used to assess the health of the marine environment and to underpin marine management. Therefore, the Aims (the overall idea behind the science) must be clearly defined, the Objectives (how the Aims will be achieved) must be clearly listed and the Hypotheses must be defined as testable and scientifically rigorous questions. Following this, the significance of any changes has to be determined, together with an assessment of whether or not those changes are acceptable. The significance of change can be determined in 3 ways. Firstly, and most objectively, the statistical significance of change can be determined provided that sufficient, robust data have been collected. Secondly, and perhaps more importantly, is the ecological or environmental significance, and thirdly, the significance of change to society must be determined. Despite this, the inherent variability within the data and the complexity of marine systems may make the detection and demonstration of change difficult. However, if society perceives change or considers an environmental change or impact to be unacceptable, then the problem must be objectively and robustly investigated. Consequently, the Ecosystem Approach relies on good and proportionate (fit-for-purpose) science to provide an ecosystem health assessment (or monitoring) programme which should include: (i) an analysis of the main processes and structural characteristics of ecosystem; (ii) an identification of known or potential stressors; (iii) the development of hypotheses about how those stressors may affect each ecosystem, and (iv) the identification of measures of environmental quality and ecosystem health to test hypotheses.
In the present context, the DPSIR framework provides a valuable philosophy for tackling and communicating methods of marine management (McLusky & Elliott, 2004; Atkins et al., 2011). This cyclical framework considers the Driving forces (human activities and economic sectors responsible for the pressures); Pressures (particular activities which are stressors on the environment); State changes (in the characteristics and conditions of the natural environment); Impacts (changes in the human system and the way in which we use the marine area), and Responses (the creation of different policy options and economic instruments to overcome the state changes and impacts). To this we may also add Recovery (i.e. reducing the state changes and impacts via the responses) this giving a DPSIRR framework.
In the context of disposal of dredged material at sea, the Drivers relate to the requirement to maintain navigation areas and clear berths for commerce and defence activities, such as a fully functioning dockyard able to take suitable vessels. This leads to Pressures to dispose of the material moved, the activities of moving and disposing of that material, the pressures created at the dredged site, the disposal site and further afield. If the activity is not carried out sustainably then this will lead to State Changes at the disposal site or even further afield, such as changes to the substratum and ecological communities. Eventually this leads to
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Impacts on the human system such as aesthetic impacts, changes to fishing, tourism and recreation or even the ability to carry out the dredging and disposal. Consequently Responses are required to minimise the State Changes and Impact such as licensing controls, monitoring of effects and action if adverse changes are observed, environmental assessments before and during activities and economic instruments such as incentives or sanctions. Therefore, to ensure sustainability the Responses operate on the Drivers and Pressures to prevent State Changes and Impacts.
It is therefore widely accepted that the marine system provides a set of Ecosystem Services which, if they operate satisfactorily, will deliver Societal Benefits (Atkins et al, 2011). The Ecosystem Services can be separated into Fundamental Services, such as the ability of the marine area to deliver its hydrographic conditions (tides, waves, currents, etc), sediment dynamics (supply, accretion, dispersion) and good water and sediment quality, and Final Services. The latter refers to the marine system supporting the biological elements such as primary producers, invertebrate prey populations and higher predators such as fish, birds and sea-mammals. As long as those Ecosystem Services are delivered, then the marine system will provide Societal Benefits such as fish and shellfish for food, areas for recreation, nature conservation and navigation. In the context of dredged material disposal, the activity has to be performed without compromising the system‘s ability to deliver those Ecosystem Services and Societal Benefits.
3.4.2. CEFAS MONITORING AND RESEARCH
Monitoring by Cefas is carried out to inform the regulatory authorities and to facilitate licensing decisions (Cefas, 2010; MEMG 2003). Given the way that sites were chosen historically, very few sites have baseline data for biota or contamination and so it is usually not possible to plot deterioration at the site with time. That is, it has not been possible to design a sampling programme which follows the standard BACI approach (Before, After, Control, Impact) (Gray & Elliott, 2009). Therefore, the aim for the monitoring of the site has been to determine changes by comparisons with nearby or control areas. This type of monitoring therefore has to allow for natural changes at both the disposal and control sites with the changes due to the effects of disposal being superimposed over these natural changes. Accordingly, Cefas has carried out multidisciplinary studies at the site and the surrounding area since 2001. These studies include both monitoring and research and have focussed on the physical conditions of the sea bed (bathymetry, particle size analysis), chemical contamination, the biological communities, hydrography, sediment transport modelling and visual studies of sea bed using video and stills images to identify accumulations of silt and litter. Smaller scale studies had been carried out by Cefas prior to this, as part of wider monitoring. All work carried out by Cefas has followed standard and nationally accepted protocols where they exist (e.g. the National Marine Biological Analytical Quality Control scheme (http://www.nmbaqcs.org and the procedures detailed in CSEMP, 2010).
As an indication of the survey effort expended by Cefas, to date (2001-2009), 222 samples have been taken for benthic community analysis, together with 187 samples for contaminant analysis and 182 samples for sediment particle size analysis. A total of 21 stations have been sampled in relation to the benthic communities with a maximum of 15 and a minimum of 6 stations being sampled in any one year. With the exception of 2001 (when the maximum number of stations was sampled), 3 (occasionally 4) replicates were taken at
Page 20 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO each station. Samples for contaminant analysis have been taken from 70 stations (2001- 2009) with sampling being carried out at more than 20 stations (to a maximum of 32) in most years. Exceptions include 2002, 2004 and 2006 when 11, 6 and 14 stations were sampled, respectively. Sediment sampling (for particle size) has been carried out in a similar manner.
In each year, the survey design has accounted for spatial variability in relation to both the disposal site and the sediment type. That is, stations have been positioned to include the disposal site itself, the immediate vicinity and the area farther afield. Additionally, stations have been positioned in relation to sediment type (particularly within the disposal site) to ensure spatial coverage of all environments. Whilst not all stations have been sampled in any one year, it is considered here and by Cefas that there has been sufficient spatial coverage to enable the detection of broadscale impacts. Temporal analysis (as a comparison of samples from individual stations between years) would be difficult although it is of note that analysis of temporal trends in sediment quality and the benthic communities present was not the aim of this monitoring campaign. It should also be noted that monitoring has been carried out with the aim of detecting broadscale impacts (negative changes to the area as a result of disposal), and not to determine whether or not the disposal site was in an optimum location.
This sampling intensity was based on the available effort but following general OSPAR guidelines which indicate the number of samples per area of a disposal ground (Dr S Bolam, Cefas, pers. com.) and according to monitoring best-practice at dredged material disposal sites (MEMG, 2003; OSPAR, 2004). Although of course more samples could have been collected, as with all survey work, the sampling design is a fine balance between what is necessary or adequate to fulfil the aims and the available budget. In this case, funds have rightly been assigned to additional, supporting studies (e.g. sediment transport modelling and hydrographic studies) rather than simply increasing the number of samples which would only lead to the same outcome but, perhaps, with a slightly higher degree of confidence.
The research and monitoring effort escalated in 2002 following a meeting between a local stakeholder and Cefas, held in Burnham-on-Crouch, and the increased level of interest in the issues surrounding the disposal activity by other local stakeholders. In particular, at this time, the RAFT and Millbay Dock proposals were of significant concern to local stakeholders. Accordingly, the estimated costs of monitoring and other scientific investigations at the Rame Head site were requested by the MMO. In total, it is estimated that Cefas has spent £850,000 - £900,000 on monitoring at Rame Head alone between 2001 and 2009, including the attendance of meetings and discussions with stakeholders. It is of note that Cefas has spent ca. £420k pa for all of its disposal ground monitoring over the past decade. This equates to a total for the decade of £4.2 million and the monitoring at Rame Head site accounts for approximately 20% of this expenditure (Dr C. Vivian, Cefas. Pers. comm.). This also includes special Defra investigations such as project ME1116 (Rame Head: Furthering our understanding of the Ecological Consequences of Dredged Material Disposal Activities). However, a significant amount of research has also been carried out by Plymouth Marine Laboratory, The National Marine Aquarium, Plymouth and the University of Plymouth and Cefas staff have formed links with these institutions in order to fully investigate the problem. The cost of these studies is not known. Furthermore, it is notable that all Cefas staff have been accommodating in attending local meetings and
Page 21 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO speaking to stakeholders. A list of research and monitoring studies at Rame Head is given in Appendix 2.
It is of note that Cefas have a reputation for producing unbiased science. In the present situation, it is apparent that they were not asked to determine whether the disposal site was optimal or to determine the fate of the material placed in the site. Their aim was primarily to address questions regarding the effect of disposal on the health of the site and whether the impacts extended beyond the boundary of the site and beyond what is acceptable. The above questions regarding the suitability of the site would only be asked if unacceptable impacts were detected. The science carried out is linked to Government policy that a new site would only be created if there was a demonstrable problem or if there was a new operation and no available site. The principles applied by Cefas to the monitoring of dredged material disposal sites are given in Figure 3.
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Figure 3. Schematic diagram summarising survey principles applied to Cefas monitoring of dredged material disposal sites. Reproduced from Cefas (2010)
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4. DREDGING PRACTICES IN THE PLYMOUTH AREA AND DISPOSAL PRACTICES AT RAME HEAD: THE LOCAL CONTEXT.
4.1 Dredging practices
Both maintenance and capital dredging are carried out in the area. Maintenance dredging is the removal of unconsolidated material, following sedimentation, to maintain channel/harbour depth. It is often regarded as the relocation of sediments which have settled in artificially deepened areas. In this area, it is predominantly carried out within the Naval Dockyard (accounting for 95% of all maintenance and 82% of all capital dredged material disposed of at Rame Head, Black & Veatch, 2010) to maintain access channels, berths and enclosed basins but also includes several commercial wharves within Cattewater and a number of marinas (Black & Veatch, 2010). Dredging is largely undertaken by hopper dredgers which transport the material for disposal at sea (Black & Veatch, 2010). However, unregulated plough dredging is also thought to be widespread and the use of Water Injection Dredging (WID) has also been investigated (Black & Veatch, 2010). Both of these techniques resuspend the sediment which would then potentially be dispersed and transported out of the estuary and Plymouth Sound by the currents. It is emphasised that plough dredging is currently unregulated (and, unlike disposal at sea, is not covered by FEPA licensing) and that material considered to be too contaminated for disposal at sea is often dredged in this manner or left in situ (A. Birchenough, Cefas, pers. comm.).
In comparison to maintenance dredging, capital dredging is the removal of material either not previously disturbed or not disturbed for many years, and is used to create a new harbour or deepen existing channels/harbours to accommodate larger ships. It often involves the removal of hard compacted or consolidated material. The RAFT (Remote Ammunitioning Facility Tamar) development, proposed in the late 1990s, was an example of this and although the capital dredging took place in 2001, the facility was not built. The disposal of dredged material following the RAFT project remains a highly contentious issue amongst the local stakeholders and is widely believed to have caused significant chemical and litter contamination and siltation in Polhawn Cove. RAFT was to be situated downstream of the Saltash Bridge and opposite the entrance to the Lynher River in the lower Tamar Estuary.
Major dredging events usually occur every one to two years with campaigns twice a year lasting one to three weeks, predominantly during the winter months (Plough dredging may take place in the intervening period (Black & Veatch, 2010)). Maintenance dredging is carried out using Trailer Suction Hopper Dredgers which can be fitted with teeth or may use water jets to loosen consolidated material. Silt and water are collected in a hopper and taken for disposal at sea (at Rame Head) once the hopper reaches capacity. Disposal is by ‗bottom dumping‘ where the material is released from doors in the bottom of the hopper and allowed to fall to the seabed over a period of approximately 5 minutes (Black & Veatch, 2010). Local observers, from the Rame Head Coastwatch station, indicate that the speed of disposal is rapid. The dredged material is principally composed of sandy mud and silt with over 75% being classed as silt (material by definition less than 63μm particle size) with the remainder being water.
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Plough dredging usually accompanies suction dredging, to remove material from areas which would be inaccessible by the suction dredger (close to harbour walls, high spots and ridges between suction dredger draghead tracks). Material is moved by the plough from one area to another, either so that it will be targeted by the suction dredger or, during intermittent periods, to areas at depths below the maintained bed level (Black & Veatch, 2010). Since plough dredging does not involve bringing the sediment to the surface, Black & Veatch (2010) suggest that it does not cause resuspension. However, there is potential for resuspension of fine sediments, particularly newly settled, unconsolidated sediments, and there is therefore the potential for transport and redistribution of these sediments.
4.2. Tamar and Plymouth Sound Estuaries Complex and the TECF Dredging Protocol
Plymouth Sound receives freshwaters from the rivers Tamar, Tavy and Lynher in the west, and from the Plym to the east and as such cannot be separated hydrodynamically from the upstream and the seaward areas. The Sound and its estuaries are treated as a single estuarine complex which is managed for its wildlife, landscapes, cultural heritage and other societal uses. The latter includes the commercial, industrial, recreational, tourism and defence interests (TECF, 2010). Hence, the area needs to be considered in discussing the dredging and disposal areas.
The Tamar Estuaries Consultative Forum (TECF) is a multi-stakeholder estuarine management partnership aimed at protecting the natural features of the area whilst allowing sustainable development. It aims for an integrated management plan which supports the statutory environmental protection and conservation agencies in the implementation of their policies. The Plymouth Sound and Estuaries European Marine Site, a Natura 2000 site, is designated under the European Directives for Habitats and Species and Wild Birds. Hence any plans or projects likely to have an adverse impact on the conservation objectives of the site require an Appropriate Assessment. Those plans or projects can be inside, adjacent to or even away from the designated area as long as their influence on the designated site is determined.
Although not considered further in this review, because of its timing, the TECF has recently (2010) initiated a project to develop a dredging protocol, as a set of guidelines for the area. This will review and assess the implications of dredging in the European Marine Site (EMS) and the Tamar estuaries management area. It aims also to consider the implications of the dredging while recognising the importance of the dredging activity for the commercial development of the water frontage (port and harbour) and the area as a whole. Any ecological implications of the dredging activities will then be addressed by discussions with the harbour and port authorities and other statutory bodies. It is expected that the study will result in a set of guidelines, probably as a voluntary code of conduct, which will ensure ecologically and economically sustainable dredging. In particular, the study will assist in licence applications and especially in carrying out Appropriate Assessments in line with the Conservation (Natural Habitats, &c.) Regulations 1994.
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4.3. Whitsand Bay and the Rame head Disposal site
The Rame Head disposal site (SE Cornwall, Figures 1 & 2) has been used for ca. a century, initially as a munitions dump but more recently (in the last 20 years or so) for the disposal of dredged material from the Tamar and Plym estuaries. Sediment accumulates in the lower parts of estuaries from both fluvial (riverine, including plant material) and seaborne sources with a small amount from immediate land runoff. The accumulation of sediment depends on marine transport, influenced by waves and tides, and downstream transport through high river flows. These sources will differ with time of year. For example, during the summer, low river-flow months, sediment may be pumped up the estuary by the dominating tidal influence. During high flow conditions in the autumn and winter, it will be washed down towards the outer, port areas. It may be assumed that the hydrographic conditions (river- flow, tidal action, etc) and sediment movement and accretion/erosion will be in equilibrium unless human activities disturb that equilibrium. By definition, dredging alters the bathymetry of the dredged site, creating a hole which then fills with depositing material which in turn requires removal.
The South Devon and Dorset Advisory Group (2009, in Black & Veatch, 2010) summarise this coast as a high energy, open area receiving south westerly waves from the Atlantic. As such, deposition of sediments is unlikely in all but the most sheltered areas. The subtidal sediments are composed of sands and sandy gravels/gravelly sands with areas of muddy sand and gravelly muddy sand (Cefas, 2005). The sediments are indicative of a high energy area. The disposal ground itself is situated within an area of mixed sediment, at a depth of 18-38 m (Okada et al., 2009). The sediments in the south western corner are composed of varying proportions of gravel, sand and silt and contain the highest proportion of silt in the area. The sediments elsewhere in the disposal site and the surrounding area are predominantly sand and gravel with the silt content decreasing northwards into Whitsand Bay (Cefas, 2005).
Rame Head and Whitsand Bay is a designated SSSI (Site of Special Scientific Interest) for supralittoral and terrestrial plant species and ecological features. Species of interest include Rumex rupestris (shore dock), Lotus angustissimus (slender birds-foot trefoil), Poa infirma (early meadow-grass), Erodium moschatum (musk storks bill) and Limonium britannicum (rock sea-lavender) (Black & Veatch, 2010). Black & Veatch (2010) indicated that most of the SSSI was in unfavourable but recovering condition and outline several activities which may compromise the condition of the site. Most of these are not considered relevant to dredging or dredge disposal although the dumping, spreading or discharge of materials was highlighted as a potential threat. It should be noted that this relates to all kinds of waste disposal and it is unlikely that material placed in an offshore disposal site would impact upon terrestrial and supralittoral habitats.
4.3.1. DISPOSAL ACTIVITIES
Between 2000 and 2009, a total of 1,860,238 wet tonnes were placed at the Rame Head site (1,143,161 tonnes associated with maintenance dredging and 717,077 tonnes associated with capital dredging) (Figure 4a). The annual average was 175,180 tonnes with a minimum of 6423 tonnes in 2000 (discounting 2006 when no disposal took place) and a maximum of 1,095,071 tonnes in 2001 (Dredging returns data provided by MMO, 2010). The most significant recent events were the RAFT (Remote Ammunitioning Facility Tamar)
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Naval Base development in 2000/2001 (total of 623,268 tonnes), which was proposed as part of the Dockyard development, and the Millbay Dock development in 2004 (93,800 tonnes) (Black & Veatch, 2010). With the exception of the 2001 disposal operation, total disposal at Rame Head is decreasing over time (Figure 4b). Dredging and disposal generally, but not exclusively, takes place during the winter months (Figure 4b). Additionally, cases where dredged material has been considered unfit for disposal at sea, due to high levels of contamination (exceeding Action level 2), are presented in Table 2.
a
b
Figure 4. Disposal quantities between 1994 and 2010 (a) and monthly disposal July 2000 to December 2009 (b). Source: MMO
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Table 2. Material considered unfit for disposal at sea. Source: K. Warr, Cefas, pers. comm.
Year Area Cause for concern 2010 Part of Victoria Wharf (30m by 30m) PAHs above that expected for area 2010 NY17 East (Part of No. 3 Wharf Inner) Copper, mercury, lead, zinc and PAH 2010 Millbay (1 to 2m) PAHs above that expected for area 2008 Yonderberry Jetty and No. 2 Wharf PCBs and PAHs 2007 No.3 Wharf Inner (NY17) Copper, mercury, lead, zinc and PAH 2004 No.3 Wharf Inner (NY17) Mercury 2004 Wharf 12 and 13 PCB and PAH. 4 month delay until testing complete 2003 Basin No. 3 PAH and metals 2003 Victoria Wharf East PAH 2001 Ernsettle Jetty and No.2 Wharf Mercury 1999 2 areas suggested although no details
Black & Veatch (2010), summarising previous sedimentological studies, state that 75- 3 150,000 m of fluvial sediment builds up in the Tamar Estuary and Plymouth Sound annually, compared to an average of 72,500 and a maximum of 147,904 tonnes dredged per annum. As these figures have not been verified and, for this material, the conversion between volume and weight is unknown then it is not possible to determine the resultant changes to the local bathymetry within such a dispersing disposal site. Similarly, it is not possible to calculate an accurate sediment budget for the estuary and dredged areas.
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5. REVIEW OF EVIDENCE
5.1. Hydrodynamics and sediment dynamics in the Rame Head – Whitsand Bay area.
The primary concerns amongst local stakeholders regarding the hydrodynamics and sedimentology were increased siltation at the HMS Scylla dive site, the resultant reduction in water clarity and the accumulation of fine sediments in Polhawn Cove. Hence a good understanding of the hydrodynamic patterns is necessary to interrogate these concerns.
5.1.1. CURRENT PATTERNS AND WAVE CLIMATE
The coastal area around Rame Head is predominantly rock with Whitsand Bay being the only nearshore area composed of sand (Cefas 2005). The area has a moderate energy regime and Whitsand Bay can be described as dynamic in terms of its sedimentary regime and wave climate. The area is exposed to waves from the south west with a long fetch and the sediment composition reflects this, with the subtidal sediments being composed of sands and gravels with patches of mud in very sheltered areas (Cefas, 2005). The beach frequently changes, fluctuating between calm periods where sand is present and rough periods when the beach is composed of pebble, cobble and boulders (Dr Annie Linley, Plymouth Marine Laboratory, pers. comm.). During comparatively calm conditions in the summer, Whitsand Bay can be described as an accreting beach with the onshore movement of sand and finer particles (which may include silt). However, due to wave action and tidal currents, silt is unlikely to remain in the intertidal area and is more likely to be rapidly winnowed away during the ebb tide. Indeed, photographs of Whitsand Bay (e.g., http://www.whitsandbay.org/) do not indicate the presence of silt on the beach. During winter storms (and indeed stormy periods in the summer), erosion of the beach will take place, removing sand and finer material. Gravels may also be displaced.
Current meters have been used (e.g. Acoustic Doppler Current Profiler meters or Nortek single-point current meters) to determine current speeds and directions around the disposal site and HMS Scylla. Five months of consecutive current meter data (July – December, 2005) indicated that current flow was predominantly parallel to the coast, running north-west to south-east (and vice versa), with the strongest flow on the ebb tide (Snelling, 2006). These data are consistent with the Admiralty chart tidal diamond and with data collected by Siddorn et al. (2003); Cefas (2005) and Okada et al. (2009). A second, weaker and less frequent current pattern was also observed, originating from the south west and north east (Snelling, 2006). Current speeds and direction are affected to a much lesser extent by seasonally strong winds up to gale force (Snelling, 2006). For the tidally dominated waters around the UK, current speeds of <0.50 m s-1 are generally classified as low (Howart, via P. Hadziabdic, 2006, British Oceanographic Data Centre – pers. comm., in Snelling, 2006).
There are two main surface current patterns in the coastal area around Plymouth Sound, as described by Siddorn et al. (2003): (1) increased velocities around the Eddystone rocks and (2) two currents flowing west and east of the breakwater in Plymouth Sound, which converge and flow into Whitsand Bay (Figure 5). Current velocities over the tidal cycle are as follows:
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High water -3h. Flood begins and current speeds reach up to 1.2 m s-1 in the Sound (north of the breakwater). Flows of up to 0.7 m s-1 occur around Eddystone Rocks with the water in the surrounding area being slack. At this time, water flows north- east into Plymouth Sound and directly north into Whitsand Bay with eddies in the eastern side of the Bay (Polhawn Cove area) evident.
High water. The direction of flow is to the east, parallel to the coast and north-east within Whitsand Bay, flowing directly into the eastern side of the bay. Current velocities are generally around 0.5 m s-1, reaching 0.8 m s-1 around the Eddystone Rocks.
Mid water Ebb (high water +3h). Offshore currents slacken and the direction of flow is south westerly, out of Plymouth Sound. Due to the headland eddies created by Rame Head, weak currents move north-west into Whitsand Bay, travelling west along the bay before moving south. Southerly flows of up to 1.3 m s-1 occur in the eastern channel of Plymouth Sound and up to 1.1 m s-1 in the western channel. In the lee of the breakwater (large region to the south), the flow is <0.1 m s-1.
Low water. The main flows from either side of the breakwater turn westerly to converge with the waters around the Rame Head peninsula where the current velocities are highest. Water flows into Whitsand Bay at up to 1 m s-1 and strong currents travel north-west and then west out of Whitsand Bay. However, counter currents also may create eddies at the eastern end of the Bay. The offshore currents run from east to west at speeds of 0.4-0.8 m s-1 with the maximum speeds being evident around the Eddystone Rocks.
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Figure 5. Surface current speed and direction for (A) HW -3h, (B) HW, (C) HW + 3h and (D) LW. Tide times relate to Devonport. Source: Siddorn et al. (2003).
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The same general patterns were observed for neap tides but with lower current velocities (maximum of 0.6 m s-1). Meteorological influence on the current patterns was considered to be low. At low water, the freshwater (lower salinity) plume coming from Plymouth Sound extends around Rame Head into Whitsand Bay where much of it remains (this may limit the diversity of the organisms colonising the rocky reefs in this area although the low salinity nature is dependent upon run-off). At high water, the extent of the plume is limited due to the incoming tide. In summary, Siddorn et al (2003) indicate higher current speeds on the ebb, which would favour the export of sediment from Whitsand Bay. This is consistent with tidal data, collected using Acoustic Doppler Current Profilers (ADCP) given in Cefas (2005) (Figure 6). Cefas (2005) concluded that the area was wave dominated.
Figure 6. Spring tide depth-averaged flow: at HW +1.1 hours (blue arrows) and HW +4 hours (green arrows). Data collected on the spring tide of 23rd February 2005. Source: Cefas, 2005.
Eddies caused by the presence of Rame Head cause the recirculation of water and suspended sediments in the eastern side of Whitsand Bay (Polhawn Cove) and the weak, north and north-eastward currents during the flood indicate potential for sediment to move into Whitsand Bay from areas further offshore (Dr P Larcombe, Cefas, pers. com.). Additionally, tracer studies carried out by Siddorn et al. (2003) show that soon after high water, the southward flows significantly dispersed the tracer plume upon exit from Plymouth Sound. The plume released in the Tamar ultimately became trapped in Whitsand Bay, as did freshwater from the Tamar. Tracer released at Cawsand Bay and Bovisand Bay also became trapped to some degree in Whitsand Bay. All 3 releases eventually became
Page 32 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO trapped in Whitsand Bay to some extent (particularly the eastern side), regardless of the location of their release. This suggests that suspended sediments may follow the same route potentially leading to the retention of fine material in Polhawn Cove (and other sheltered areas in the east of the bay). Based on this finding, Siddorn et al. (2003) recommended monitoring of contaminants in Plymouth Sound, particularly those associated with fine sediments, due to potential for accumulation in Whitsand Bay.
5.1.2. SEDIMENT TRANSPORT AND BEHAVIOUR OF MATERIAL AT THE DISPOSAL SITE
The disposal site is situated in a dynamic area and has therefore been accepted as a dispersing site. As such, any material placed there will be transported away from the site, predominantly in a north-west to south-east direction, in the direction of the prevailing currents. The seabed scanning image produced by Cefas is perhaps the most valuable impression of the seabed characteristics within the disposal site (Figure 7). The image indicates different depths (with colours ranging from blue to green) with prominent rock outcrops (coloured black) in the west where sediment cover is either very thin or absent. Acoustic data were used to determine areas with distinct sediment types and the seabed scanning surveys were followed by grab sampling and granulometric analysis in these areas for the purpose of ground-truthing. The ground relief indicates smooth sediment areas and rock outcrops protruding through the sediment. The granulometric data are summarised in text on the Figure 7. Patchy sediment in the adjacent area becomes thicker with increasing distance towards the shallower waters in the east. The south-western part of the site shows a large-scale geological feature, as a well-defined break in the bed, which then leads to a deeper area covered by soft sediment (to a depth of >35 m). This area of mud does not appear to have been recently mobilised by wave action although low level undulations are present on the surface indicative of the influence of the waves and currents on the surficial sediments (Cefas, 2005). The sediments in much of the southern part of the site appear to be composed of varying proportions of sand, gravel and cobbles with patches of finer sediment. These fine sediments largely comprise fine sands in the east and muddy sand in the west. Furthermore, grab sampling by Cefas (2005) indicated that the presence of soft, black mud in the western part of the site may be related to disposal. However, samples taken from areas outside the disposal site have not been found to contain this type of sediment. The image clearly illustrates that the disposal ground is at the transition between the shallower (<20m) inshore area and the deeper and more muddy offshore area >35m. These data do not indicate the formation of large scale bedforms although features (approximately 50 x 50 m) observed in the eastern part of the site may be related to capital dredging disposal.
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Figure 7. Rame Head disposal site - Seabed acoustic image giving past and present licensed dredged material disposal areas; colours relate to depth, the stations marked are those sampled by Cefas (NB the ridges parallel to the long axis of the image are artefacts caused by the technique) (figure produced by Cefas, 2005).
Capital dredgings are generally consolidated, will travel to the seabed and then may be subjected to erosion. In contrast, the maintenance dredgings are usually less consolidated and whilst the larger particle sizes will reach the bed, lighter fractions will form a suspended solids load which will travel in the direction of the prevailing current, depending on current speed. Very light material may form a surface slick although none has been observed according to monitoring reports and local stakeholder evidence. Given that a small amount of wind energy is transferred to moving the surface waters, suspended sediments at the surface can be moved in the direction of the winds. The unconsolidated bed sediments may be subject to bed-load transport, depending on particle size and bottom current speed.
Material already in suspension will be more readily transported, and by weaker currents, than settled material. Therefore, whilst the currents in Whitsand Bay may be described as weak and may not be sufficiently strong to cause the resuspension of consolidated material, they could cause the transport of fine sediment already in suspension. The faster currents recorded (~0.4 ms-1) are sufficient to move particles classed as sands or smaller (greater than 1 Φ or less than 0.5-1 mm) either as the suspended or bed-load transport. It is again emphasised that the site was chosen and accepted as a dispersive site and therefore, most of the material placed there would have moved into the near and far-field areas around the site over time. Given the length of time over which disposal has occurred and the volumes of material which have been placed in the site, large mounds of material would be evident if this were not the case. Acoustic data from Cefas (2005) provide no evidence for this.
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The published, peer-reviewed paper by Okada et al. (2009), involving Cefas staff, describes an analysis of the <63 μm sediment fraction. This innovative study used the characterisation and comparison of the entropy of different particle size distributions where maximum entropy assumes that the volume or mass in each size spectra occurs with equal frequency (random) and minimum entropy assumes that all particles belong to the same size class. This aimed to estimate the spatial distribution of dredged material from the disposal site. Grab sampling was used with subsequent granulometric analysis and trace metal concentrations were used as an additional, complimentary indicator. Sampling stations were grouped according to their sediment characteristics resulting in an overall classification as:
G1. Silty, with very fine sands present in the western part of the disposal site; 2 km to the SE of the disposal site; 2 km SW of the disposal site; 1-3 km to the NW and to the east of the Rame Head Peninsula.
G2. Silty sandy gravels were present within the disposal site; 6 km to the SE; 4 km to the SW and 6 km to the NW.
G3. Unimodal well-sorted sands were found within the eastern part of the disposal site and in nearshore areas in depths of <20 m. Sediments of this type also occurred to the SW and NW of the disposal site.
Hence, the spatial distribution of the sediment types indicates coarser sediments in the inshore areas within Whitsand Bay and that the distribution of the silty sands and gravels follows the pattern of the NW-SW current direction (Figure 8).
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Figure 8. General sediment types (derived from grab sampling) in the Rame Head area (G1, silty very fine sands; G2, silty sands and gravels; G3, unimodal and well sorted sand). (From Okada et al., 2009.)
It was concluded that the disposal activities may have influenced the metal and particle size characteristics to a distance of 6 km from the site, a distribution dependent upon current -1 speed. At 0.3 ms and greater, particles were transported to the SE whilst at lower current speeds, particles could be transported and widely distributed around Whitsand Bay. At 0.1 ms-1, particles were distributed around all sampling stations in Whitsand Bay with transport likely to the west being <2%. However, Larcombe et al. (unpublished, in Okada et al., 2009) argue that the dispersed dredged sediments are only distinct from the ambient sediments to the NW and SE of the disposal site (tidal dispersal) and to the S and SW due to movement down the slope of the sea bed. These findings were documented in Cefas (2005) where modelling studies indicate that the movement and accumulation of sediment from the disposal site occurs in a NW-SE direction with an along-shelf orientation (Figure 9). Whilst this study has been criticised for not accounting for wave action, it is of note that Cefas (2005) found depth-averaged flow to be stronger in an offshore than an onshore direction. This is also indicated by Siddorn et el. (2003). Cefas (2005b) also stated that:
‘To move to a mathematical assessment of wave-associated sediment transport would require good estimates of the bed shear stress generated by tides and waves during a variety of storms. This was not possible due to resource constraints, but is not necessary for the work to be fit for purpose. It is clearly acknowledged in the report that some material will be moved shoreward. The regional and local distribution of bed sediment provides the evidence of the capacity for sediment sorting and accumulation in the area’.
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Figure 9. Sediment transport patterns after 24 h of modelled dispersion from the disposal site (black triangles indicate path of sediment transport). Source: Cefas, 2005.
Furthermore, grab sampling carried out to validate the modelling studies (Cefas, 2005) did not indicate large amounts of fine material within Whitsand Bay. This was also noted by Murray (2002). Finally, the Shoreline Management Plan for the area, which considers sediment transport and erosion according to sediment cells, also suggests that there is little or no significant sediment transport along the coast between Rame Head and Lizard Point (Royal Haskoning 2009). There is likely to be localised onshore-offshore transport of fine sand and silt within the distinct bays, but sediment tends to be retained within each of these sub-cells, due to the physical control exerted by the hard-substratum headlands that extend out into deep water.
The sediment patterns of the coastal and offshore areas are linked to those in the estuaries and Plymouth Sound given the interlinked dynamics of the areas. As with most estuaries, there are erosion-deposition cycles in the Tamar estuary with different sediment fractions moving in different directions on different tides and with different river flow conditions. Pulses of sediment will come down the Tamar when freshwater flows dominate over tidal flows. Sediment supply to the subtidal could occur by drawdown of sediment from intertidal areas after dredging if the sediment and bathymetry equilibrium is disturbed. Tidal influences under low river flow conditions often deposit marine sands and silts into the outer parts of estuaries although here geomorphologists consider that little marine sediment gets into Plymouth Sound, a possible effect of the breakwater (Dr. P. Larcombe, Cefas. Pers. comm.). The mechanism for the movement of fine sediment into the dredging areas is not yet understood. It is considered that suspended sediments can be transported out of the Tamar around the Rame Headland into Polhawn Cove but this material will be kept in suspension. Bale et al. (2007) suggest that much sediment is kept within the Tamar and only a small fraction is moved artificially by dredging compared to what is moved naturally.
The findings of Murray (2002), that coarse material remained at the disposal site and fine material was transported inshore and that therefore the disposal site must be the source of the fine material, do not consider material naturally transported out of Plymouth Sound which in itself would be similar to the material present in the disposal site. Current patterns indicate that a proportion of sediment transported out of Plymouth Sound would inevitably end up in Whitsand Bay (Siddorn et al., 2003; Dr R Uncles, Plymouth Marine Laboratory, pers. comm.; Dr P Larcombe, Cefas, pers. com.) and the potential for natural sediment transport and deposition in sheltered areas cannot be ignored. Silt from the disposal site may be transported into Polhawn Cove but the quantities are likely to be small given the prevailing hydrodynamic conditions. Furthermore, it is not possible to differentiate between silt originating from the disposal site and that entering Polhawn Cove as a result of natural sediment export from Plymouth Sound. Reliable tracer studies would be required to confirm the source of the material in Polhawn Cove but the tracer used would have to be sufficiently distinct from the natural sediment to allow its detection whilst being sufficiently similar to accurately mimic the behaviour of the sediment. That is, appropriate particle sizes must be used. The material must also be environmentally benign and must not cause any adverse aesthetic impacts. Such a tracer study may not be feasible in this area.
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Finally, whilst photographic, video and other anecdotal evidence clearly shows the presence of silt in Polhawn Cove, evidence for a significant increase over time has not been presented and it is thought that much of the fine sediment washed into the area is quickly washed out. Furthermore, it is unlikely that a change in the disposal activity (e.g. movement of the site further offshore) would prevent silt from washing into Polhawn Cove entirely.
5.1.3. SEDIMENT CHARACTERISTICS WITHIN AND AROUND THE DISPOSAL SITE.
Both Cefas (2005) and others such as Murray (2002, an undergraduate thesis) showed that the sediments within the disposal site were primarily composed of coarse material, with little fine material being present, except for the lower SW corner. Murray (2002) stated that the natural sediment of Whitsand Bay was coarse sand and shingle whereas that of the Tamar estuary was fine sand, silt and clay. Murray (2002) hypothesised that any silt found in Whitsand Bay would have been introduced to the system and that if the particle size distribution matched that of the sediments in the disposal site then this would provide evidence of sediment movement from the disposal site into the bay. This hypothesis is flawed because it does not account for natural sediment transport out of Plymouth Sound which would share the characteristics of the material in the disposal site. Inshore of the disposal ground, in Whitsand Bay, the sediments ranged from fine sands (10 of the 15 sites) to very coarse sands and gravels. Murray (2002) (using limited sampling) showed maximum values for very fine sand (4 Φ), very coarse silt (4.5 Φ) and coarse silt (5 Φ) as 4.94, 1.55 and 0.72%, respectively (these figures were compared to figures of 11.56, 10.62 and 25.2% at the control sites within the Tamar estuary).
The minimum grain size at one of the control sites within Whitsand Bay was 4 Φ and the minimum grain size of sediments from the disposal site was 2 Φ (Murray, 2002). Samples further into Polhawn Cove contained particles smaller than 4 Φ (i.e. higher Φ values, indicating smaller particle sizes) and this led Murray (2002) to conclude that sediments with this proportion of fine material did not naturally occur and that the source could be the disposal site. Murray (2002) did not consider the natural transport of material out of Plymouth Sound – the original source of the material present in the disposal site. It was later demonstrated that, due to the current patterns, a proportion of the sediment transported out of Plymouth Sound would inevitably end up in Whitsand Bay (Siddorn et al., 2003). Furthermore, the relatively sheltered nature of the Bay in this area and the model to which Murray (2002) refers, showing tidal eddies around Rame Head, are not acknowledged in his thesis. This assessment is considered naïve since silt is attracted to any accreting site and can be scavenged from anywhere in the system, even offshore muddy areas.
The potential for silt to be transported inshore from the disposal site is not disputed. However, Murray (2002) strongly suggests that this is the case even though he had little or no direct evidence and he attributes any silt content to disposal activities without consideration of other sources. Transport inshore is assumed in the thesis without any consideration for transport offshore. In contrast, Siddorn et al. (2003) and Cefas (2005) both later demonstrated a stronger offshore transport potential.
The proportion of sediment with a grain size of >4 Φ (i.e. silt and clay with a grain size of <63μm) accounted for less than 5% by weight in samples taken by Cefas (2005) and Murray (2002) in Whitsand Bay. Maximum silt content was recorded in samples taken from stations immediately to the north of the disposal site and the subtidal areas of the bay (Murray,
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2002). Values of <1% were recorded from the intertidal areas and the very nearshore areas. Cefas (2005) recorded maximum silt concentrations within the disposal site itself, at stations parallel to the shore (in and NW to SE direction) and at stations to the south of the disposal site. These levels of silt/fine sediments are unlikely to cause an adverse ecological impact. However, it is emphasised that given that the inshore and intertidal sediments will vary seasonally, especially given the large-scale topographic changes to the beach from summer (an accreting beach) and the winter (an eroding beach) then the proportions of different particle sizes in sediments taken as a synoptic sample have to be regarded with caution. The surveys carried out do not interrogate sediment fluxes but merely assess the types of sediments in place during the surveys.
Selkirk (2005 a, b) questioned the validity of techniques used by Cefas to separate the fine (<63 µm) and coarse sediment fractions prior to particle size analysis. Concern was raised that consolidated fine sediments may not be completely broken up and may be retained in the sieve, thus leading to an underestimation of the fine fraction. However, Cefas are aware that this is a potential problem and take steps to ensure that all fine material passes through the sieve. That is, sieves are not overloaded and the sediment is washed until the water runs clean (C. Mason, Cefas. Pers. comm.). It is of note that particle size analysis is not only carried out in relation to monitoring at dredge disposal sites but is routinely carried out to explain the distribution of benthic organisms. Hence there is the need for employing techniques which accurately separate the different size fractions.
5.1.4. TURBIDITY AND SILTATION
Emu Environmental Ltd (2001, in Murray, 2002) monitored water quality (turbidity) before, during and after the RAFT disposal operation, using Acoustic Doppler Current Profilers (ADCP) and Optical Backscatter Sensors (OBS). Monitoring was carried out over a 13 h period, along a transect running shoreward of the disposal site. No impacts on turbidity were detected outside of the disposal site and this was attributed to low current velocities which would allow the material to settle in-situ. Emu Environmental (2010) did not account for stormy conditions, as stated in the conclusions. Murray (2002) implies that this indicates a bias towards the interest of the Ministry of Defence in order to enable dredging and disposal to continue. However, the author clearly states that ―the methodology will attempt reject the null hypotheses (that there is no impact of disposal on turbidity), leaving the hypotheses (turbidity is increased as a result of disposal) open for acceptance‖. It is considered here that this is a biased approach to hypothesis testing, i.e. experimental/survey design must not make any assumptions about the outcome and the sampling and methodology must be unbiased and not be carried out in such a way that favours one outcome over another. Without being too critical of undergraduate theses, as certain stakeholders have given them much credence, it is emphasised here that they have to be guided in an impartial manner otherwise the student will conclude what any proposers of the study expect him/her to conclude.
A spokesperson for a local business (who wishes to remain anonymous to protect the interests of the business) has described Whitsand Bay as ‗stunning with blue seas and good water clarity‘. Following storms, an increase in turbidity was noticed but this was attributed to resuspension of sediments caused by rough seas.
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5.1.5. INCREASED TURBIDITY AND SILTATION AT THE HMS SCYLLA WRECK DIVE SITE
Local stakeholders have voiced concerns regarding siltation and increased turbidity and thus poor visibility impacting on diver safety and the quality of the diving experience at HMS Scylla. Anecdotal evidence has been provided in support of this. It has been suggested that visibility has been reduced from 8-10 m to 2-3 m following disposal and reduced to 4 m from 15 m, 20 years ago. Whilst much of this information is anecdotal, poor visibility can impair the ability of a diver to escape from inside the wreck which is a significant safety concern. Furthermore, the death of two divers on the HMS Scylla wreck was attributed (by local residents) to poor visibility in the area. Even if it occurs, there appear to be mixed views over the cause of the increase in turbidity in this area. Several have associated it with the disposal activities but it has also been suggested that the presence of HMS Scylla itself could have led to increased turbidity. Fine sediment in suspension during storms will easily be deposited inside a sheltered and complex structure such as HMS Scylla. It is likely that this sediment would build up over time due to the lack of potential for resuspension. Furthermore, increased deposition could take place following seasonal phytoplankton blooms although no evidence has been provided to suggest this and it is not known whether this has been studied. It is of note that Cefas (2005) also monitored turbidity and found no evidence for increased turbidity resulting from the disposal activities.
Wave action can cause the resuspension of bed sediments down to water depths of 10 – 20 m (Wright et al., 2005, in Snelling, 2006). Since HMS Scylla lies at depth of approximately 26m, there is potential for sediment resuspension around the vessel, particularly during stormy conditions. This may cause a temporary increase in turbidity. Scour has been noted on both sides of the ship (Snelling, 2006, 2010; Fost, 2010) with a build up of unidentified material (possibly netting) on the starboard side. Side-scan images indicate the occurrence of back-eddies and sand ripples, indicating sediment movement.
Snelling (2006) examined the sediment properties along a transect to the north of the disposal site (site 1) running directly to HMS Scylla (site 5) (Figure 10). The sediment became finer between sites 1 and 5 with the sediments at sites 1 and 2 being composed of 18-79% gravel (higher values at site 2) with 2-4% silt. Sites 3 and 4 were in areas of mainly fine sand with up to 11% silt and the sediment at site 5 (next to HMS Scylla) was composed of 14-19% silt with remainder predominantly being fine sand. These data were consistent with BGS data which show the disposal site to be located in an area of sandy gravel with the Whitsand Bay area and sites 3-5 being sandy. Small amounts of anthropogenic debris were noted including glass fragments and paint flecks. Snelling (2006) suggested that there was an increase in silt towards HMS Scylla with the Rame Head disposal site as a potential source.
However, Work by Siddorn et al. (2003) suggests that this may, in part, be the result of a release of sediments into Plymouth Sound, the source of which could be dredging activity in the River Tamar. Due to low currents, Whitsand Bay would eventually receive a proportion of any accidental releases (including disturbed sediment) within Plymouth Sound (Siddorn et al., 2003). Additionally, fine sediment will be deposited in (be scavenged by) any suitable low-energy area whereas in higher energy areas, it will be resuspended or prevented from sinking. As indicated above, the nearshore and shallow sublittoral area in Whitsand Bay is dominated by sand and gravelly sand with large areas of muddy sand slightly offshore and directly south of HMS Scylla and the Rame Head disposal site. Hence, stormy conditions
Page 40 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO with onshore winds could easily cause the movement of fine material (from this area of fine sediment and from the disposal site) north towards HMS Scylla. Cameron (2009) also highlighted this area of muddy sand as a potential source of sediment to HMS Scylla. Furthermore, multibeam echo sounder images indicated scour around some parts of the ship which must also be considered as a source of fine material, particularly considering the silt content of up to 19% in this area. By 2007, it was evident that this scouring was occurring around the whole vessel, to a maximum depth of 0.5 m (Snelling, 2010). This scour was also reported by Fost-HM (2010).
Figure 10. Sampling locations (PSA and Current meter), prior to sinking of HMS Scylla and location of James Egan Layne. Source: Snelling, 2006
5.1.6. SILTATION OF THE BEACH AND ROCKY REEFS AT THE EASTERN SIDE OF WHITSAND BAY (POLHAWN COVE).
Concern has been raised by several local stakeholders over increased levels of silt in Whitsand Bay and particularly on the rocky reefs in Polhawn Cove and there is an underlying presumption by many parties that any fine material accumulating anywhere in Whitsand Bay must be related to the disposal activity. However, not all respondees take the view that this is either occurring or is a problem. Furthermore, there is no direct evidence for this. Sediment analyses detailed above (e.g. Cefas, 2005) show very low levels (<1%) of fine material in the sediments in Whitsand Bay although sampling this close to the shore has
Page 41 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO not formed part of any routine monitoring programme. Silt does occur in rocky areas close to the shore but the material has not been confirmed as mud (silt and clay) or as fine organic debris. However, video footage of this material shows that once disturbed, the material settles rapidly (seconds). Given that silts (material between 63 and 4μm) take up to minutes to settle over short distances (e.g. 20 cm) and clays (<4μm) can stay in suspension for over an hour (Bale & Kenny, 2005), it is considered that the material disturbed by divers is either flocculated fine material or coarse particles (coarse silts and fine-medium sands).
As an indication of the health of the reefs, photographs on the Whitsand Bay Website (Stop the dumping in Whitsand Bay. http://www.whitsandbay.org/) are used to compare reefs in Polhawn Cove with those of Heybrook Bay, also a western facing reef but on the eastern side of Plymouth Sound (Figure 11). Stakeholders have suggested that the Heybrook Bay area is a control area against which the dredged-material receiving waters of the western side can be compared.
Heybrook Bay, a small rocky Cove within the Wembury Voluntary Marine Conservation Area, has been described as:
‘Underwater there are rocky gullies lined with fairly coarse sand running down to a depth of about 10m, 100m from the shore at high water. There is a diverse selection of algae and other marine life. When I first dived here I was reminded of Kimeridge in Dorset which is very diverse in algae.
A small fresh water stream runs into the bay, but the area is not silted. The bay is not subject to strong tidal movement but a large amount of weed and debris wash into it. At times the shoreline is knee deep in rotting weed. Sometimes there is lot of broken weed (definitely not silt) in suspension in the water which can knock the visibility. This weed carpets the floor of the sandy gullies close to the shore, but provides an excellent habitat for wrasse. We see more ballan and corkwing wrasse foraging together in this weed than we see anywhere else. All common wrasse species, except cuckoo wrasse are here. Also a site for black faced blennies, conger eels, lobsters, crabs and shoals of school bass.
In contrast we first dived Rame Head in 1996 and found it extremely disappointing. It was littered with manmade debris, very silty with little marine life attached to the rocks. I assumed that it was because the runoff with the falling tide goes west depositing the silt at Rame. Because of the poor quality at Rame we generally dive east of Plymouth Sound unless we dive the wrecks west of the Tamar’ (comment from Karen Williams, submitted by Dr Keith Hiscock, MBA, Plymouth).
Furthermore, Dr K. Hiscock (MBA, Plymouth. Pers. comm.) considers that the reefs to the west of Plymouth Sound are much less diverse than those to the east as a result of the residual current direction which is broadly to the west. Thus, west of Plymouth seabed communities are subject to the variable salinity and often high turbidity and, maybe, contaminants coming out of the estuaries much more than to the east.
Page 42 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO
Polhawn Cove Polhawn Cove
Heybrook Bay Heybrook Bay Figure 11. Reef quality at Heybrook Bay and Polhawn Cove. Source: http://www.whitsandbay.org/
5.2. Contaminants in Sediments
In addition to concerns over the levels of silt in the Bay, some stakeholders are concerned over contamination, either the levels they believe to be present or the potential for it to occur. Particular concern has been raised over the eastern end of Whitsand Bay (the Polhawn Cove area) although there are differing opinions on the occurrence and source of the contamination. It has been widely attributed to the disposal site although HMS Scylla has also been proposed as a potential source of certain substances. Similarly, natural inputs must be considered together with inputs from the local estuaries, arising from urbanisation and industrial activity, flowing into the coastal waters. Siddorn et al. (2003) demonstrated that Whitsand Bay could receive contaminants (e.g. resulting from a discharge or pollution event) originating from Plymouth Sound and is therefore considered vulnerable to waste discharge and pollution events within Plymouth Sound, regardless of their origin. This implies that natural processes could deposit contaminated sediments and silt in Whitsand Bay.
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Prior to disposal at sea, all dredged material is assessed for contamination against Cefas Action Levels which are agreed and published by OSPAR (2008). These are derived from chemical and ecotoxicological data sets to establish a range of concentrations in material suitable for disposal at sea. They should not be viewed as pass/fail criteria but rather as assisting in decision-making (Cefas, 2005) although material containing concentrations of contaminants exceeding Action Level 2 is not considered suitable for sea-disposal. It should be further noted that protocols for the assessment of dredged material differ to those for the assessment of environmental quality, largely because the two types of assessment have different aims and are based on different sediment fractions and extraction methods (Cefas, 2007a). Therefore, comparison of environmental samples (i.e. those taken from the seabed compared to the material from the dredger) against Cefas Action Levels is not appropriate. At present, satisfactory sediment quality standards do not exist in the UK, although they are under development. The fate of contaminants in the marine environment is complex, particularly in sediments, and factors such as salinity, pH, oxygen availability, sediment redox conditions and the physical properties of the sediment (particularly the amount of organic matter and fine material) all affect the chemical state of contaminants, their affinity to bind to sediments and, ultimately, their bioavailability (Gray & Elliott, 2009). Hence, it is not appropriate to apply a single standard to all areas of the marine environment.
In the absence of suitable standards in the UK, those derived by CCME (2002) and the USEPA (US Environmental Protection Agency) have been widely adopted. Such standards include Interim Sediment Quality Guidelines (ISQG) and Probable Effects Levels (PEL) developed by CCME (2002) and the Effects Range Low (ERL) and Effects Range Median (ERM) developed by the United States Environmental Protection Agency (USEPA, detailed in OSPAR, 2009a). As standards do not exist for all substances (e.g. the USEPA guidelines only include 3 metals – Hg, Pb and Cd), comparisons between contaminants in samples from Rame Head and Whitsand Bay have been made with both sets of standards. Additionally, data have been compared to Background Concentrations (BC) and Background Assessment Concentrations (BAC). BC values are relevant to naturally occurring substances and are derived from samples taken from areas considered to be pristine or remote from human influence. BAC values apply to synthetic compounds which do not naturally occur in the marine environment and for which the BC should be zero (OSPAR, 2009a).
Cefas (2005) presents data for a wide variety of contaminants including metals and organometals and a number of classes of organic compounds such as Polycyclic Aromatic Hydrocarbons (PAH), organochlorine pesticides, Brominated Flame Retardants (BFR) and Polychlorinated Biphenyls (PCB). Cefas (2007a) also reported levels of artificial radioactivity. Methods of analysis used by Cefas are consistent with those given in CSEMP (2010, although the precise protocols in this version may have been updated and may therefore differ slightly to those used by Cefas, (2005)). The analysis of metals (also used by the Environment Agency and other regulatory bodies) involves the fine fraction of the sediment (<63 µm fraction) with which contaminants are predominantly associated. Samples for the analysis of organics are not passed through fine sieves (to prevent loss of analyte) although they are passed through a 2 mm mesh to remove stones. Fine grained sediments present a larger surface area for adsorption by contaminants than do equal volumes of coarser material. This together with the ionic nature of silts/clays and organic matter means that contaminants have a strong affinity for fine grained sediments and organic matter (Gray & Elliott, 2009). Therefore, the data should be interpreted with this in
Page 44 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO mind and apparently high values are not necessarily indicative of contamination. In particular, the low levels of silt and organic matter present in Whitsand Bay and the analysis of a small fraction of that sediment may over-estimate (or give a perception of over- estimation of) the contaminants present. It is also of note that a significant proportion of the contamination present will not be bioavailable (see Section 5.2.1.).
5.2.1. METALS
High levels of metals, exceeding various guidelines (e.g. Canadian ISQG, PEL, ERL, BC and BAC values) have been reported from Whitsand Bay by numerous studies carried out independently by several institutions. These include those involved with statutory monitoring (e.g. Cefas 2005; 2007a), an undergraduate dissertation from the University of Plymouth (Thorpe, 2009) and comments from local stakeholders. Specifically, Mr Bruce Selkirk (Selkirk, 2005 a, b) raised concerns that average metal concentrations in sediments close to Polhawn Cove were higher than those in sediment samples from the disposal ground itself. It was suggested that this was due to transport of contaminated material out of the disposal site and accumulation in Polhawn Cove.
Cefas (2005) found concentrations of As, Zn, Cu and Cd to be elevated within the disposal site compared to the surrounding area. However, As concentrations exceeded the ISQG throughout the study area and exceeded the PEL at 1 site to the north of the disposal ground, near Polhawn Cove. Similarly, Cu concentrations were greater than the ISQG at all sites and greater than the PEL at 1 site within the disposal ground. Zn concentrations also exceeded the ISQG at 11 of the 15 sites but were below the PEL throughout the survey area (with the exception of 1 site within the disposal ground). Cd concentrations close to the shore in Polhawn Cove were similar to those found in the disposal site. However, Cd concentrations were lower than the ERL at all 15 sites (including those within the disposal ground), were greater than the BAC at 5 sites and greater than or equal to the BC at 5 sites. Furthermore, Cd concentrations were below the PEL at all sites and only exceeded the ISQG at one site within Polhawn Cove.
Similarly, comparatively high concentrations of Hg were found in Polhawn Cove and at a location to the east of the disposal site. Hg concentrations exceeded the ERL (and therefore the BC and BAC) and ISQG values throughout the survey area and also exceeded the PEL at one site within the disposal ground and 3 sites within Polhawn Cove. No spatial trends in Ni, Pb or Cr were found but it is of note that Pb concentrations exceeded the ERL at all stations and both Pb and Cr values were greater than the ISQG throughout the survey area (standards do not exist for Ni). Pb values were greater than the PEL at 6 sites (2 within the disposal site, 3 to the north towards Polhawn Cove and 1 to the south east) whilst Cr values exceeded the PEL at 2 stations within Polhawn Cove. Cefas (2005) considers metal contamination in the Rame Head area is comparable to that around other disposal sites but is elevated compared to other areas in SW England.
Whilst concentrations of some metals exceed the various guideline values in much of Whitsand Bay (but not necessarily within the disposal site), it is emphasised that the analysis is carried out on the silt and clay component of the sediment sample only and that this represents a small proportion of the total sample. Hence, metal concentrations should be considered to be overestimated in the context of any comparison with guideline values. Furthermore, in coarse sediments, collecting sufficient sample for analysis can be difficult
Page 45 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO and may lead to anomalous values (e.g. the particularly high concentration of As reported at a single station in 2004 (Cefas, 2005; Dr C Vivian, Cefas pers com.).
Thorpe (2009) analysed intertidal (middle and lower shore) and cliff sediments at 6 sites in Whitsand Bay. Arsenic was found to exceed the ISQG of 7.24 mg kg-1 for all beach samples and also several of the cliff samples (with the exception of Sharrow and Happy Valley). However, the maximum concentration of <30 mg kg-1 was lower than the PEL of 41.6 mg kg-1 throughout the area. Cu and Pb exceeded the ISQG at a minority of stations but never the PEL and Zn and Hg concentrations were below the ISQG at all stations. Cd was below the limit of detection at most sites except Tregantle and Tregonhawke where -1 -1 concentrations of 0.74 and 0.21 mg kg were recorded (ISQG = 0.7 mg kg ; PEL = 4.2 mg kg-1). These values exceed the BC (0.2 mg kg-1) and, at Tregantle, the BAC (0.31 mg kg-1, but were below the ERL (1.2 mg kg-1). Comparison with Cefas (2005) indicated that the intertidal sediment concentrations of metals were considerably lower than subtidal sediments. This may be partly due to differences in the sample preparation and digestion methods, an important consideration when interpreting contaminant data. Thorpe (2009) analysed the entire sediment sample, using Aqua-Regia (3:1 concentrated HCl:HNO3) to extract the metals from the sediment (partial digest). In contrast (and according to CSEMP (2010)), Cefas routinely carry out the analysis on the <63 μm fraction of the sediment sample, using Hydrofluoric acid (HF) which has a greater recovery rate than strong acids (total digest). HF digestion is internationally recognised as the standard technique for total metal determination. It also results in dissolution of the main matrix components of the sediment enabling normalisation of metals against non-mobile elements such as aluminium (Cook et al., 1997). This method allows objective spatial and temporal comparison but caution in needed for data interpretation with regard to the potential for biological effects.
Whilst concentrations of some contaminants have been found to exceed various standards, it is unlikely that they are present in a bioavailable form since contaminants readily become sequestered within the sediments. In particular, excessively strong acids (not present within the digestive system of animals) are used to measure the total metal concentration within the sediment and, in the case of Cefas (2005), the analyses were carried out on the silt/clay fraction of the sediment which, in most cases, was a very small proportion of the total sediment (generally <10%). In terms of the total sediment (including all size classes), the overall concentrations will be significantly lower, despite the assumption that some metal content will be associated with the larger size classes. The concentrations of metals present are therefore unlikely to pose a threat.
Metal levels in sediments were also provided by Mr Dave Peake (provided to him by Greenpeace in 2005). The metal concentrations were lower than the ISQG values in all cases, although the relevance of these comparisons and any comparison with Cefas data is questionable because details of sample collection, preparation and digestion were not given. Furthermore, concentrations of Hg, Pb and Cd were well below the BC, BAC and ERL values adopted by OSPAR (2009a). Both Hg and As were consistently reported at concentrations of <10 mg kg-1 and hence the precise concentrations are not known. These values could potentially exceed the ISQG values although the limits of detection of the analytical procedure were not given. The limits of detection for the methods used by Cefas are 1 mg kg-1 and 10 µg kg-1 for As and Hg, respectively. Whilst the concentrations of Hg and As are assumed to be below the limit of detection, no reliable interpretation of the data
Page 46 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO relating to these two substances can be given. Interpretation of these data was given by Greenpeace.
It is of note that Cornwall has a history of metal mining and that the rocks are naturally rich in metals. Metals will enter the marine environment as a result of dissolution of the rock, acid mine drainage, run-off and smelting processes. Given the history of the area, elevated metal concentrations in the sediments are inevitable, as is their concentration in relatively sheltered areas such as Polhawn Cove.
As stated above, modelling indicates the potential for the transport of material from Plymouth Sound into Whitsand Bay, particularly the eastern side (i.e. Polhawn Cove). Siddorn et al. (2003) specifically point out that a proportion of any contaminants released into Plymouth Sound would eventually end up in Whitsand Bay. Metal concentrations in Jennycliff Bay (eastern area of Plymouth Sound), monitored by the Environment Agency between 2000 and 2010, regularly exceed ISQG values for several metals (see Appendix 3). For example, Cu concentrations exceed the ISQG by an average of 298% and a maximum of 527% with maximum values being up to 91% of the PEL. Hg (which has been found at elevated levels around the Rame Head disposal site) exceeded the ISQG by a mean of 246% and a maximum of 520% with maximum values being up to 96% of the PEL. Pb and As also significantly exceeded the ISQG, with maximum values being over 95% of the PEL, whilst Zn and Cd concentrations were below the ISQG and PEL. It is of note that the Environment Agency methods of analysis are consistent with CSEMP (2010), examining only the fine fraction (<63 µm). Mean, maximum and minimum concentrations of Hg and Pb were found to significantly exceed the BC, BAC and ERL values. The maximum value for Hg was 450% of the ERL (the assessment criteria follow the order of BC It is also of note that dredged material is analysed prior to disposal and the disposal at sea of any sediments with high concentrations (generally exceeding Cefas Action Level 2) of contaminants is not authorised. Therefore, whilst the potential for the disposal site to act as a source of contaminants in Polhawn Cove is not discounted, other sources must be considered. In particular, when disposal at sea is not authorised, contaminated sediments may remain in-situ (A. Birchenough, Cefas, pers. comm.) and become subject to plough dredging (which is not covered by FEPA licensing). Although Black & Veatch (2010) suggest this type of dredging does not cause the resuspension of sediment, the potential for the transport of contaminated, disturbed sediments needs to be considered as a potential source of contamination in Polhawn Cove. The former sewage sludge disposal ground (Figure 2) to the south of Plymouth Sound should also be considered as a potential, albeit historic, source of contamination. Similarly, the Rame Head disposal site has also historically been used for the disposal of munitions which could have caused the release of metals to the sediments. 5.2.2. ORGANOMETALS The toxic antifouling paint TributylTin (TBT) was present in the baseline survey biota prior to the placement of HMS Scylla. Although the vessel was not cleaned of TBT, this shows that there were other sources of contamination. Although the use of TBT is now prohibited, it is a persistent contaminant and inputs dating back to its first use in the 1970s will still be Page 47 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO present in the environment. Most UK coasts adjacent to ports, harbours and marinas have detectable levels of TBT and/or the biological effects of the toxin such as imposex of marine gastropods such as dogwhelks (Nucella lapillus). Hence, in the Plymouth and Whitsand Bay area there will be many possible sources of TBT including the dockyard, ship maintenance, hull cleaning operations and marina activities. Paint flakes will end up in the sediment and will not only be transferred from the dredging site into the disposal area but will also be transported into Whitsand Bay via natural sediment export from Plymouth Sound. Cefas (2005) reported elevated concentrations of TBT within the disposal ground but concentrations were generally below the limit of detection (0.001 mg kg-1). There were 2 exceptions to this with detectable levels being found at one site within the disposal area and at one site to the north. Given that TBT concentrations in surface sediments should be decreasing (due to the ban on the use of TBT), inputs from maintenance dredging should also decrease over time. 5.2.3. POLYCYCLIC AROMATIC HYDROCARBONS (PAH) Cefas (2005) reported concentrations of 400-2600 µg kg-1 (total PAH) from the disposal site with concentrations in the surrounding area generally being lower. Therefore, total PAH concentrations within the disposal site are below the ERL (OSPAR, 2009a). However, elevated concentrations of up to 5500 µg kg-1 (exceeding the ERL) were recorded from station G28 (Figure 12) and, more importantly, elevated concentrations (although below the ERL for total PAH) were recorded from the sandy sediments at sites RH4 and RH5 (Figure 12), within Polhawn Cove. These sites are very close to the shore. Furthermore, the PAH profile of the samples taken from site RH4 is similar to that of sediment samples taken from dredging areas within the Tamar where total PAH concentrations range from 2591 to 6194 µg kg-1. Whilst this may require further investigation, there is no direct evidence that the contamination in Polhawn Cove is the direct result of the disposal operations alone. Given the current patterns in this area (Siddorn et al., 2003), natural water circulation and sediment transport processes must be taken into account. It is noted for completeness that based on analyses provided by Greenpeace in 2005 to Mr Dave Peake, several organic compounds were detected but methods of analysis and the concentrations found were not given. 5.2.4. SYNTHETIC ORGANICS Brominated Flame Retardants (BFR) were found to be either below the limits of detection or at very low concentrations. The sum of the 10 congeners was 0.7 µg kg-1 (dry weight) which is equivalent to the lowest levels detected in European marine sediments (Cefas 2005). The maximum concentration of Polychlorinated Biphenyls (PCB) was 19 µg kg-1 (sum of 25 congeners) and was recorded from within the disposal site. Except for one site to the south of the disposal area (G28, Figure 12), PCBs were undetectable within Whitsand Bay. Several organochlorine pesticides were detected within and around the disposal site although these were generally found at concentrations below the ISQG and PEL values (OSPAR 2009a does not indicate standards for organochlorine pesticides). Concentrations of Hexachlorocyclohexane (HCH or lindane) were detected throughout the area but with the highest concentration being found at station G28 to the south of the disposal site (Figure Page 48 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO 12). The dominant isomer was γ-HCH and exceeded both the ISQG and PEL at this site. Comparatively high concentrations of DDT (predominantly pp-DDT) were also recorded from this area (again exceeding the ISQG and PEL). However, it is emphasised that contamination by organochlorine pesticides and other synthetic organics is generally low and that station G28 may represent an isolated hotspot for elevated levels of contamination. This was explained by the presence of a gyre to the south east of the disposal site, leading to the accumulation of litter and contaminants (Cefas, 2005). Figure 12. Grab sampling locations (Cefas, 2005) 5.2.5. RADIONUCLIDES Radiological analysis for the 66,000 tonnes of capital dredged material from the Tamar estuary was carried out in relation to the RAFT project (Cefas, 2007a). 137Cs was the only detectable artificial (anthropogenically produced) radionuclide and was only present in surface sediments. The activities of 60Co and 241Am were below detection. The average activities of 234Th, 214Pb and 228Ac (the gamma emitting daughter products of 238U, 226Ra and 232Th, respectively) were similar to the average ‗background‘ values estimated for UK mud. Therefore, radiological contamination is not considered to be a problem in Tamar estuary or in the vicinity of the Rame Head disposal site. Page 49 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO 5.2.6. FINAL COMMENTS The distribution of contaminants in the marine environment is complex and is related to the sediment properties, hydrodynamic conditions, presence of other contaminants and the specific chemical properties of individual contaminants (Gray & Elliott 2009). It is of note that sediments can be mobile and that the chemical properties of contaminants vary according to the physico-chemical conditions of the environment. In order to fully understand the distribution of metals around the Rame Head disposal site, multivariate analysis linking contaminant concentrations to the sediment properties (particularly the proportion of silt and clay) would be necessary. Furthermore, the source of contamination needs to be established. Whilst there is no direct evidence to suggest that the disposal activities are responsible for the elevated concentration of some contaminants within Whitsand Bay, there is also no direct evidence to suggest the contrary. In particular, the effect of plough dredging on sediment resuspension and contaminant mobilisation needs to be established and the potential for natural sediment transport from Plymouth Sound must be considered. Despite this, the levels of most contaminants (with the exception of PAH) do not give cause for concern and the cost of establishing the above facts needs to be balanced up against the benefit. However, dredging companies, together with Cefas, should continue to be rigorous in their assessment of the chemical quality of dredged material and the biological effects of those contaminants in order to ensure that unacceptable levels of contaminants do not enter the marine environment via disposal operations. 5.3. Litter on the beach and at the dive sites Local stakeholders have concerns regarding litter accumulation at Polhawn Cove and an increase in the amount of plastic debris on the beaches. In particular, a local business stated that large amounts of litter were washed into the bay on every tide and in order to protect their business, employees spent approximately 2-3 hours, twice a week, clearing rubbish from the beach. Other local users of the beach have also stated that they carry bin liners when they visit Whitsand Bay in order to remove litter from the area. The litter was described as being from various sources but the amount associated with barbecues and picnics was commented on in particular (Dr Annie Linley, Plymouth Marine Laboratory, pers. comm.). There is also extensive and valuable photographic evidence, provided by Mr Dave Peake, regarding litter at dive sites. Mr Peake has retrieved various litter items from the beach, including industrial and presumably dockyard materials (webbing, aluminium sheeting and gasmasks). However, little quantitative evidence was presented in support of these photographs, e.g. number of pieces per unit area or quantitative presence in different habitats (amount in reefs vs. amount in bare sands) nor was any attempt made to document the age of the debris. Rigorous studies on the amount of litter in Whitsand Bay are limited. Cefas reported an average of 1.7 coarse litter items/100 m within the disposal site (based on underwater video evidence) but they did not conduct any litter surveys in the intertidal area. No litter items have been recovered from any of the sediment samples collected by Cefas. Cefas did not comment on the source of the litter but disposal activities cannot be excluded as a source of some of the litter found in Whitsand Bay. The Marine Conservation Society (2004, in Cefas, 2005) reported large amounts of litter on Potwrinkle beach (Whitsand Bay) with 30% being derived from fishing activity, and 50% being from unknown sources. Burkill (2006) carried Page 50 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO out litter surveys within Whitsand Bay (Polhawn Cove, Portwrinkle and Tregantle) in various weather conditions ranging from calm weather (October) to bad weather and rough seas (January). Slightly higher levels of litter were found in Polhawn Cove compared to other areas with higher levels being found following bad weather (over 200 litter items) although no indication of variability is given. Most of the litter was plastics, marine industry refuse and items (termed non-source or foreign) which could not be associated with beach use or any other source. These items included foot wear, industrial building materials, dust masks, cylume sticks, torches and electrical cables. Unfortunately, large amounts of litter on beaches and at sea are common, especially in areas adjacent to a port/harbour/tourist areas and shipping and ferry routes. However, the Marine Conservation Society (2004, in Cefas, 2005) indicated that the amount of litter in Whitsand Bay is about twice the national average. Whilst some of this litter may come from the local area, it is notable that ocean circulation patterns transport litter from all over the world, causing deposition of litter far from its source. Whilst there may be regulations and campaigns in the UK and Europe to control litter at sea, these controls do not exist everywhere, particularly in developing countries such as those along the West African and South American coasts. However, as documented above, it does appear that much of the litter found in Whitsand Bay is from local sources. Marine litter is a widespread problem of both national and global significance with serious implications for marine life and those using marine and coastal areas. To knowingly deposit litter in the sea (and many people do) is unacceptable and usually unnecessary. The licence conditions for the Rame Head disposal site stipulate that the licence holder must take all reasonable precautions to prevent the disposal of man-made debris (i.e. litter) at sea and according to Cefas (2005), Enforcement Officers reported compliance with this during the 2001 RAFT disposal operation. Information concerning compliance during other disposal campaigns was not given and it would be unreasonable to assume other practices, particularly since non-compliance with licence conditions could result in withdrawal of the licence. This is not in the interest of the dredging companies. Maintenance dredgings, by their nature, are less consolidated than capital dredgings and are therefore easier to screen for than capital dredgings which contain historic, buried litter. It is therefore likely that litter could have been present in the disposal material following the RAFT disposal operation in 2001 (when particular concern about litter was raised by local stakeholders) and other capital dredging operations. It is emphasised that dredged materials are thoroughly screened prior to any future disposal operations although it is noted that the removal of all litter is not possible. 5.4. Sediment microbial health - Beggiatoa The presence of mats of the sulphur-reducing bacteria Beggiatoa on the seabed has been suggested, based on diver photographs (thought to date from 2002), although not confirmed by sampling and analysis by Cefas or others. Beggiatoa mats have been recorded by divers in summer but this may not have coincided with times of sampling by Cefas (usually in May) and the location and coverage by the mats needs to be recorded more scientifically. The divers have concerns that these mats are a result of dredged material disposal. To develop, the mats need a ready source of organic matter together with its degradation products (hydrogen sulphide (H2S), methane (CH4)). Page 51 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Whilst there is no direct evidence to suggest the absence of Beggiatoa, this is not the usual environment for it to occur in. It is difficult to understand how the dredged material could cause it given that the sediments in the area are coarse with ambient, rather than elevated, levels of organic matter. Such high levels of organic matter in a dispersive site would be unusual and have not been recorded in any of the samples taken by Cefas (2005) or noted by Snelling (2006) or any of the undergraduate students who studied the sediments in the area. Similarly, while there are isolated sewage discharges from the coast these are considered insufficient to cause the conditions for the mats to develop. If Beggiatoa is present, then there must be other causal mechanisms. For example, there are records of ‗knee-deep‘ rotting algae on the coast in the region of Rame Head (Dr Stefan Bolam, Cefas, pers. comm.). However, in order for Beggiatoa mats to develop, the algae would need to be assimilated into the sediments to produce methane and hydrogen sulphide. Beggiatoa beds have been found under fish farms, even in high energy and coarse substratum areas (Hall-Spencer et al., 2006) and on rotting saltmarsh detritus (Petersen et al., 1980). Given their ability to occur naturally on marine sediments, Beggiatoa on anoxic sublittoral mud is recognised as a biotope or habitat under the European EUNIS habitats classification (EUNIS 2004) thus reinforcing the fact that stable anoxic areas which are not anthropogenically produced can occur. It has been suggested (Dr P. Larcombe, CEFAS, pers. comm.) that peat underlying the sediments in the eastern area of Whitsand Bay may be a potential source of sufficient organic matter to cause anoxia (the absence of oxygen which leads to the evolution of gases such as methane and hydrogen sulphide) and promote the formation of Beggiatoa. To date, the presence of peat in or under the seabed sediments has not been properly substantiated and requires further investigation. However, there is the potential for it to exist in submerged areas, particularly where the overlying marine sediments may be frequently eroded, exposing the underlying peat (Professor R Gehrels, University of Plymouth, pers comm.). Therefore, sub-surface peat deposits in subtidal coastal areas could provide suitable conditions for Beggiatoa to develop. Rützler (2004) found white patches of Beggiatoa on a subtidal on peat wall near a muddy bottom. Peat layers have been found in seabed sediments along the Devon Coast (e.g. http://www.scopac.org.uk/scopac sediment db/lyme/lyme.htm). If the presence of Beggiatoa mats in the Rame Head/Whitsand Bay area can be substantiated, the presence of peat should be investigated as a possible cause. At present there is little evidence to require further studies on the disposal ground in relation to organic enrichment and the formation of Beggiatoa mats. 5.5. Ecological understanding 5.5.1. IMPACTS ON THE MARINE BENTHIC COMMUNITIES Most of the local stakeholders who have voiced their concerns over the dredge disposal activity at Rame Head have raised the issue of impacts on marine life. As part of routine monitoring within and around dredge disposal sites, grab sampling and underwater video/stills photography are used by Cefas to sample the infaunal (sediment dwelling) and epifaunal (living on the sediment surface) organisms. Page 52 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO As has been recorded at other disposal sites, Cefas (2005) found a reduced species richness and abundance within and close to the disposal site. Standard multivariate techniques were used to identify distinct community types and, to some extent, indicated separation between the benthic communities within the disposal site from those farther afield. There was also some separation between the communities within Whitsand Bay, those in the north west and those in the south east. However, there is a high variability within the data set. Furthermore, one particular group of similar samples (representing samples collected in 2001, possibly after the RAFT disposal operation) contains samples from all areas (except Polhawn Cove). Samples taken from the Polhawn Cove area represent the most distinct group and, as stated by Cefas, this is most likely to be related to differences in the sediment characteristics and depth. This analysis does not strongly indicate that the disposal operations have caused an unacceptable impact in the surrounding area and it is of note that the highest values for species richness and abundance were recorded from station 28 (Figure 12), the site of the highest levels of contamination. Furthermore, the benthic communities have remained reasonably stable over time in the areas outside of the disposal site, where corresponding stable patterns in the sediment properties were also recorded. Variability in community structure inside the site can be explained by frequent physical disturbance of the sea bed and variability in particle size distribution in relation to the disposal activity. Finally, evidence from other surveys in the Rame Head area suggests similar numbers of taxa and species compositions as those recorded by Cefas. This includes data from as early as 1939. The benthic community analysis presented in Cefas (2005) is brief and demonstrates key findings only. More detailed interrogation of the data would be required to enable the reader to fully understand spatial and temporal patterns in species distribution and community structure. In particular, the relationships between the physical properties of the sediment, depth, contamination and benthic community structure should be examined in more detail. An unpublished but submitted manuscript by Bolam et al. (Dr S. Bolam, Cefas, pers. comm.) aims to take this analysis further. 5.5.2. SEDIMENT BIOASSAYS As a further indication of impacts on individual marine organisms, Cefas used sediment- organism bioassays. As with the benthic community studies, emphasis is placed on the sediments as most contaminants are either discharged with sediments or bind to them after discharge. Selkirk (2005 a,b) raised concerns that the bioassay data (using the polychaete Arenicola marina and the amphipod Corophium volutator) presented by Cefas (2005) indicate increased mortality of C. volutator in sediments from the Polhawn Cove area, despite the lack of statistical significance. Indeed, reduced survival is apparent in sediments from stations G18 (within the disposal site) and G13 (to the north east of the disposal site). Additionally, reduced survival was recorded from station G2, a considerable distance to the north west of the disposal site. The Corophium volutator and Arenicola marina sediment bioassays are outlined briefly in OSPAR (1997) and in more detail in references therein, and are internationally accepted methods of sediment quality assessment based on a substantial amount of scientific work. Whilst chemical monitoring determines concentrations of contaminants, it does not give any information about their bioavailability or their in-combination (antagonism and synergy) effects. Whole sediment bioassays directly indicate adverse biological responses but they Page 53 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO are not without their limitations and this must be acknowledged when interpreting the results of such assays (Gray & Elliott 2009). This was not discussed in detail by Cefas (2005) but was later clarified by their response to Selkirk in September 2005 (Cefas 2005a). In particular, it is important to consider the impact of the physical characteristics of the sediment on survival in combination with that of any contaminants which may or may not be present. C. volutator and A. marina are intertidal, predominantly estuarine organisms which inhabit soft, fine grained sediments. Both are deposit feeding organisms which rely on organic detritus and microbiological films associated with fine sediments (McLusky 1967; McLusky, 1968; Longbottom, 1970; Zebe & Schiedek, 1996). Furthermore, C. volutator is reasonably tolerant of low oxygen concentrations within the sediment (Meadows, 1964). Whilst both species are generally found in estuaries, both are tolerant of full seawater discounting salinity as a factor influencing survival. C. volutator survives within a salinity range of 2-50 (McLusky 1967; McLusky, 1968) and A. marina is found at salinities above 8 (Green, 1968) but most abundantly in the outer areas of estuaries. As noted above, the highest mortality was recorded from stations G2, G13 and G18 where the sediments were generally classed as sandy gravels/gravelly sands and gravelly muds. Lower mortality was recorded from stations G3, closest to Polhawn Cove where the sediments were more uniform and G19, in the south eastern corner of the disposal site. However, as details of the physical characteristics of the control sediment were not reported then direct comparison is difficult. Furthermore, details of the level of contamination for sites G2 and G3 were not given and so interpretation of mortality in relation to contamination is difficult. Survival of Arenicola was not affected and faecal cast production was generally uninhibited although it is of note that the highest rate of production was at stations G2 and G18, where silt content was highest. There appears to be no clear spatial pattern in mortality with respect to proximity to the disposal site or contaminant concentration. Overall, there is no strong evidence for any effect of contaminants on the survival or behaviour of C. volutator or A. marina. However, a reduction in survival of C. volutator was recorded at a number of stations and it would be speculative to conclude a lack of impact. Hence, these results should be considered inconclusive. The bioassays used conform to internationally accepted protocols and good correlations have been demonstrated between levels of contamination and response by organisms. They were used correctly by Cefas and include the agreed control mortality criteria. Despite this, it may be questioned that bioassays and their test organisms designed for muddy sediments are unsuitable for coarse sediments. 5.5.3. CELLULAR BIOASSAYS AND CONTAMINANT CONCENTRATIONS IN MUSSEL TISSUE (MYTILUS SPP.) In order to consider a further indication of biological harm, the Crown Estate commissioned Plymouth Marine Laboratory to investigate the impact of disposal activities on the health of mussels (as a sentinel organism) in Whitsand Bay. A series of histopathological analyses were carried out to determine damage at a cellular level. Sampling was carried out over 2 eight-year time periods spanning 1978-1985 (preceding 2 capital dredging and disposal programmes) and 1998-2006 (including dredging and disposal operations), the latter coinciding with the RAFT project in 2001. Further analysis was carried out before, during and after the disposal of sediments from Cattewater Harbour in 2007. Page 54 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Lowe (2009) used a total of 17 cellular markers, covering digestive tract responses (5), reproductive responses (7), disseminated neoplasia (blood cell abnormalities) (2) granulocytomas (inflammatory cell responses) (1), immune system responses (1) and the prevelance of parasites (1) in the mussel Mytilus galloprovincialis and suspected hybrids of M. galloprovincialis and Mytilus edulis. In general, these histopathological analyses did not provide any evidence to suggest that the disposal of dredged material at Rame Head was having any adverse effects on the health of the mussels in Whitsand Bay. However, it should be noted that a temporary change in the cellular structure of the digestive system was recorded in 2001 when the RAFT disposal operation took place. It is also of note that between 1974 and 1977, studies on mussels at the confluence of the Tamar and Lynher rivers (Beggars Island), where the dredging for the RAFT project took place, showed 2% of the population to exhibit blood cell abnormalities (visually similar to human leukaemia). This indicates that contaminated sediments can potentially cause cellular abnormalities but that the prevalence was low in this area. Further analyses on M. edulis were carried out by Lockwood-Saunders (2003) to determine metal concentrations in mussel tissue. Comparisons were made between Polhawn Cove, the Mayflower Marina in Plymouth and Tamar Bridge (close to the site of dredging). Due to similarities between tissue concentrations at Polhawn Cove and at the dredge site (Tamar Bridge), it was concluded that the disposal site must be the source of contamination. However, interpretation of the results appears to have been based on graphical descriptions of the data (with no indication of variability) without any statistical testing. The present review then performed a 1–way Analysis of Variance test using the raw data in the appendices to the dissertation and the output can be summarised as: As and Zn concentrations were equal at all three sites. Zn concentrations at the Mayflower Marina appear to be considerably lower but cannot be classified as such because of the high variability in the data at all three sites. Cd, Mn and Pb concentrations were highest at Tamar Bridge and equal at Polhawn Cove and Mayflower Marina. Cu concentrations were lowest at Polhawn Cove and equal at Tamar Bridge and Mayflower Pier. These data do not suggest elevated metal concentrations in mussel tissue at Polhawn Cove and do not provide evidence for contamination caused by the disposal activities. As with other low-level projects carried out in this area, there is no consideration of natural inputs, historic inputs or natural sediment transport processes. Tissue concentrations (in mg kg-1) were compared to the World Health Organisation Drinking Water Quality Guidelines (http://www.who.int/water_sanitation_health/dwq/GDWAN4rev1and2.pdf) (given as mg l-1). This is considered not relevant since environmental waters and biota do not need to meet drinking water quality standards and standards relating to public health are not relevant to assessing environmental quality. Furthermore, the units are not interchangeable in this context. Again this study showed the limitations of undergraduate student projects and less than rigorous hypothesis testing. Page 55 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO 5.5.4. HEALTH OF MARINE ORGANISMS There is little concrete evidence for abnormal or poor health of individual marine organisms although photographs have been provided by divers. For example, pictures of anemones and cup corals with their tentacles withdrawn may reflect a reaction to the diver or water currents. Similarly, a picture of a ‗sick lobster‘, which was covered in fouling organisms such as barnacles and tube worms (Pomatoceros sp.), merely reflects the fact that this was an old animal which had not moulted for perhaps 2 years (the intermoult period becomes longer with age) (Dr Roger Uglow, University of Hull, pers. com.). The animal had a damaged claw, again a sign that it had not moulted and thus been able to repair the claw. 5.5.5. COLONISATION ON HMS SCYLLA Snelling (2006) indicated that HMS Scylla was sunk in March 2004 and the surrounding area was monitored for TBT (Tributyl tin) contamination from the hull paint. The differences in community development between the hull and the superstructure were assessed together with an analysis of whether the fouling colonisation on HMS Scylla was similar to that of the nearby wreck ‗the James Eagan Layne‘ which had not been cleaned. Photographic records 2 of colonisation within a 1 m quadrat were made at 3 and 6 months and at 1, 2, 5 and 10 years after sinking, in 4 areas of the vessel. In addition, because of the concerns that the TBT would act as an endocrine disrupting substance which could be taken up by organisms, concentrations of TBT were measured in biota. Whilst elevated TBT concentrations (>2 μg -1 -1 kg / 20 μg kg for molluscs) were found in most biota samples up to 12 months after sinking, colonisation of HMS Scylla in terms of the timescale and the types of species present was consistent with that of other artificial reefs (Snelling, 2006; Hiscock, 2010). However, the community differed from that of adjacent natural reefs, especially in terms of the paucity of rare, threatened or scarce species such as the branching and cushion sponges. This may be the result of the difference between artificial and natural substrata. Studies on the colonisation patterns of HMS Scylla have been carried out with scientific rigour by skilled taxonomists using accepted methods and published in the peer-reviewed international literature (Hiscock et al, 2010). Colonisation of new marine surfaces usually passes through a recognised sequence given that bare surfaces have to be ‗weathered‘ whereby a microbial bacterial, fungal and algal covering then provides attractive surfaces for larvae to settle. In addition, the timing and speed of colonisation by fouling organisms will reflect the time at which the surfaces become available in relation to the main annual recruitment period. Just as the sediment infaunal (sediment dwelling) community reflects sediment and water quality, the colonisation of any surface by epifaunal biota provides an indication of water quality. In particular, many sessile organisms feed by filtering particles from the water column (suspension feeding) and so high levels of suspended solids would adversely affect the species diversity, abundance and health of the organisms present. The presence of sensitive filter-feeding animals and delicate red algae on HMS Scylla is not indicative of high levels of suspended solids. Algae and the suspension-feeding tube worm Pomatoceros triqueter colonised the vessel widely within the first 3 months, followed by a seasonal decline in algae at 6 months but an increase in faunal species diversity. The echinoderms Asterias rubens, Psammechinus miliaris and Astropecten opercularis, the suspension feeding ascidian Ciona intestinalis and the anemone Metridium senile were all present on the vessel within the first 6 months. A Page 56 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO year after being scuttled in 2005, different parts of the vessel showed different degrees of colonisation. For example, the density of P. triqueter decreased on the starboard bow whilst reasonable numbers remained on the port quarter. The echinoderms P. miliaris and A. rubens were noted in large numbers thus indicating that the sessile fauna were now supporting predators. The delicate hydroid Tubularia species occurred on much of the superstructure; again the ascidian C. intestinalis and plumose anemone M. senile were present on the starboard quarter. The density of algal species also increased on the superstructure after the winter decline. There was a marked increase in colonisation after 2 years and, after 5 years, the vessel supported 263 taxa although the colonisation was poor on internal and TBT-painted surfaces. Despite this, colonisation was starting on TBT-painted areas where the paint was damaged or adjacent to colonised areas. Hiscock et al (2010) considers that the community became mature after passing through a 5-stage sequence over the first 5 years after being scuttled: colonisation by opportunists such as filamentous green algae, hydroids, serpulid polychaetes and barnacles; recruitment and growth; seasonal die back and predation resulting in large areas of bare reef; completion of recruitment of species which were to become dominant in later years although abundance and body size was low; prolonged period (2006-2008) of growth and increase in abundance of species which were to become dominant. Winter die back no longer a part of succession but part of natural variability. The community was composed primarily of long lived species and the reef was considered to be mature. It is of note that one of the last major colonisers was the pink sea fan Eunicella verrucosa, a species of high conservation importance. The development of a mature community on HMS Scylla, composed of delicate filamentous algae, delicate suspension feeding organisms and carnivorous predators, is not indicative of excessive levels of silt in the water column. Many of the species found have delicate feeding and gill structures which would be damaged by high levels of silt. In turn, constant cleaning of silt from the gills requires energy expenditure and would cause the organisms to deteriorate in terms of their capacity for growth and reproduction. In low energy areas such as the inside of a shipwreck, there is potential for debris (e.g. faeces, dead and decaying animals) to settle and this should be considered as a potential source of some of the silt found inside HMS Scylla. 5.5.6. FISH Concern for the health of the marine life in the area has been raised by many local stakeholders with some of them specifically referring to fish. There are reports of unfamiliar fish although these were later identified as Redband or ribbon fish which are common in Whitsand Bay. Similarly, another angler reported catches of herring which were later identified as Allis shad, a species which is protected under the Habitats Directive. In Page 57 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO contrast, two anglers reported fishing for 2 hours without a bite and were concerned that this may be due to the effects of the disposal activity. The Angling Trust has also expressed significant concern over the impacts of the disposal activity on local fish stocks. In contrast, dialogue on the World Sea Fishing Forum (World Sea Fishing Ltd, 1998-2010) suggests that the area is used by sea anglers who appear to recommend the area around Queener Point for good sized wrasse and pollack with wrasse being particularly common. Other species mentioned include mackerel, weaver fish, dogfish (huss), whiting, rockling, bass, pouting, sea trout, john dory, codling, thornback ray, silver eel, codling, conger eel, mullet and occasionally bass. Small numbers of tope have also been caught. Cefas fisheries survey reports for the Western Channel were available for 2007 to 2009 (Cefas 2007b; Cefas, 2008; Cefas, 2009). In UK waters, the area covered by these surveys included Portland to the Isles of Scilly. The survey area includes the area immediately offshore from Whitsand Bay and Rame Head (although no sampling appears to have been carried out within Whitsand Bay) where approximately 3 inshore stations and 5 stations from the surrounding area (either to the west or further offshore) were sampled in 2007 with fewer stations in the immediate vicinity of Rame Head being sampled in 2008 and 2009. It should be noted that the aim of these surveys was to carry out stock assessment for the area as a whole and to determine factors such as species distribution, abundance and size distribution in relation to their environment. Fish length, weight and maturity measurements were taken in support of the EU Data Regulation and supplementary physico-chemical data, including salinity and temperature, were collected. These surveys employ a random, stratified design (meaning that the area is divided into strata such as habitat type, population and geographic area and samples are taken from each stratum) and are not specifically designed to detect the impacts of specific activities. It should also be noted that the information provided included survey reports (labelled as ‗provisional‘) and not detailed research reports. These reports are intended for internal use within Cefas only. The surveys indicate that that main commercial species caught in the Rame Head area included sole, plaice, monkfish and lemon sole. Poor cod is assumed to have been recorded in this area since this species was present in almost all samples (Cefas, 2008). Data are presented as maps in all reports, with circles of different sizes indicating abundance (on a log scale). These maps are only provided for a limited number of species (presumably the most widespread and abundant species) and a complete species list for each station is not given. Species composition is plotted in pie charts on maps (Cefas, 2008) although these are complex and are not readily interpretable due to overlap between charts. However, these charts present data for 40 species with approximately 10-15 species (estimated from the figure) being present at most stations in English Coastal Waters. Whilst a proportion of the charts representing the Rame Head area is obscured, at least 10 species were recorded (Cefas, 2008). The adjacent chart indicates a large catch composed of approximately 2 (certainly less than 5) species. Ad-hoc records indicate that large numbers of cod have also been seen around HMS Scylla. The size frequency data appear to have been pooled in order to determine the size frequency distribution for the survey area as a whole. They therefore cannot be interpreted in the context of this study. Walmsley & Pawson (2007) reported on the fishing activity around the coast of Devon and Cornwall although it is emphasised that details of the number of vessels operating and the quantity of fish landed cannot be interpreted in the context of the impact of dredge disposal at Rame Head. This is because details of the location of fishing vessels at sea are not Page 58 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO given. Over 50 fishing vessels regularly land into Plymouth (including boats registered elsewhere) and fishing activity can be divided into offshore and inshore. Inshore fishing activity is considered to be most relevant to this review. The inshore fleet comprises approximately 10 boats of 9-14 m which use otter or beam trawls (but may also use dredges, nets and lines) to target white fish such as plaice, whiting, lemon sole, turbot and monkfish for most of the year. More recently, species such as red mullet and cuttlefish have become important. Pilchards are occasionally targeted in winter. These boats operate to a distance of 20 miles offshore and the majority of them land their catches into the daily fish market. Around 12 scallop dredgers, some of which may change to beam/otter trawling during the spring, operate within 14 miles of the coast. Scallop dredging has increased since the 1980s as a result of restrictions on the quantity of white fish which can be landed and the Eddystone area is considered to be very productive in this respect. Finally, 10-15 boats use pots to target crabs and lobsters and other static gear (nets and longlines) to target fish in the Eddystone area. Three of these boats may also use hand-lining to fish for mackerel and, in the estuarine areas, bass. Whilst there is an active inshore fishery and broad evidence that the Rame Head area supports a diversity abundance of fish similar to that of other inshore areas around the south Cornwall coast, there is insufficient evidence to indicate that the disposal activity either does or does not impact upon fish populations. The absence of an impact cannot be assumed based on the available data and further, targeted, studies would be required to confirm this. It is of note that disposal activity can potentially have positive effects on fish (Bolam et al., 2006) but this has not been studied at Rame Head. It is of note that Stebbing et al. (2002) reported significant correlations between temperature data for the North Atlantic region and the immigration of southern fish species to Cornish waters. It is possible (but again unconfirmed) that changes in angler catch records may be influenced by warming in this region. 5.6. Socio-economic aspects and impact on the local economy There are perceived or actual concerns that the disposal of dredged material at sea has the potential to negatively impact upon the local economy, particularly in areas dependent on tourism. Conversely, dredging and dredge disposal operations are equally important to the local economy in terms of maintaining navigable waterways and continuing urban regeneration and development work. Some stakeholders are concerned about poor visibility at the HMS Scylla dive site, degradation of the coast in terms of the amount of silt and litter present and negative impacts on local fish populations. Concern has been raised over the potential for loss of income from tourism if current disposal practices continue, in particular a reduction in divers visiting HMS Scylla and the associated loss of income to the local dive shops and dive clubs. However, as indicated below, these dive sites attract very high numbers of divers and it is not possible to say if this is reduced because of adverse publicity relating to the dredged material disposal. To a lesser extent, stakeholders are concerned that the number of visitors to the beach will fall if Whitsand Bay is perceived to be polluted and that this will have repercussions for local businesses (shops, restaurants, hotels etc). Page 59 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Whitsand Bay is a popular recreational angling area and also supports commercial fishing in the form of netting, potting and mackerel fishing. Any reduction in these species would have economic consequences. The value of recreational and commercial fishing activities has not been quantified in this review but these activities are undoubtedly important to the local economy. In many UK coastal areas, recreational fishing has a greater economic value than commercial fishing when the amount of money spent on travel and accommodation is included. Accordingly, the Angling Trust stated that the South West of England was one of the most popular areas in the UK for recreational sea angling and that the activity was of major economic and cultural value to the local community. As such, the Trust aims to maximise its potential through protecting the marine fish stocks and the environment on which they depend. Whilst taking the view that the disposal activity is having a ‗detrimental impact‘ on local fish stocks, members of the Trust are concerned that the present review may recommend cessation of disposal at Rame Head and relocation of the disposal site. In their view, this would produce similar adverse effects in a new area and potentially reduce the income from angling and tourism. They have therefore requested the MMO to consider alternative uses for the dredged material. Throughout this review, it has been emphasised that perceived adverse effects are regarded with the same weight as actual adverse effects. Accordingly, at least one local business owner, who wished to remain anonymous in order to protect their business, has concerns over the potential loss of revenue if local campaigners continue to draw attention to the issue. The concerns indicated above are countered by other local stakeholders reaffirming the importance of dredging to the operation of Plymouth Dockyard, the port and the marinas. Stakeholders include 2 statutory Harbour Authorities: River Yealm Harbour Authority and Dockyard Port of Devon (which includes the statutory Harbour Authorities of Cattewater Harbour Commissioners, Sutton Harbour Company and ABP Millbay Dock). There are also 7 marinas in the Dockyard Port area including Plymouth Yacht Haven and Plymouth Yacht Haven Quay (within Cattewater), Queen Anne‘s Battery and Sutton Harbour Marina (off Plymouth Sound), Mayflower International Marina and Royal William Yard (lower Tamar) and Millbay Marina (within Millbay Dock, off Plymouth Sound). Hence many jobs are dependent on port operations, including commercial shipping, Navy operations and leisure. Changes to dredging and disposal practices or removal of the licence could compromise the interests of local industry. One stakeholder has even indicated that compensation would be sought if the licence for disposal were to be retrospectively removed especially as a reduction in development opportunities would result in reduced business and employment opportunities. Despite being located in one of the most spectacular settings in the country, Rugg (2004) described Plymouth as an area of high unemployment and deprivation with areas of dereliction. The city is built around Plymouth Sound and its estuaries, which are a natural barrier to efficient movement around the city, and their use for transport has declined since the peak in the late 1800s and early 1900s (Rugg, 2004). The waterfront is one of the main attractions and promoting it, together with a good quality water-transport system, is key to attracting investors to the area in order to re-develop the city. The demand for this regeneration of the waterfront area comes from local residents and from proposals to attract tourists to the area. Surveys indicate that improved water transport between areas in and around the city, separated by Plymouth Sound, would be beneficial and viable, according to Page 60 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO public demand. Rugg (2004) concluded that there would be sufficient future demand for enhanced services in the upper Tamar Valley and the promotion of water transport in Plymouth Sound and estuaries is a highly important issue. It is thought that water transport could play a significant role in boosting economic development, tourism and could, itself, be a visitor attraction. Implementation of such a scheme relies on the resolution of issues of access to the waterfront and connectivity with existing city and regional transport systems. This is likely to lead to a requirement for dredging (Black & Veatch, 2010). Accordingly, the use of the dock, marina and waterfront areas is dependent on clear navigation channels and thus on dredging and dredged material disposal, again reinforcing the value to the local economy (Rugg, 2004). 5.7. Public health issues, aesthetic impacts and public perceptions The most high profile event linked to disposal activities at Rame Head was the deaths of 2 divers on August 2nd 2007 after they became disorientated on HMS Scylla. It was raised at the Inquest that poor visibility caused by the volume of silt placed at the Rame Head site was the cause. Reports of the incident suggested that the police would investigate the amount of silt on the vessel but there is no record of this following the Coroner‘s report (http://www.divemagazine.co.uk/index.php/news/latest-news/3744-silt-possible-factor-in- scylla-diving-deaths.html; http://www.thisiscornwall.co.uk/news/Silt-hazard-warning-divers- deaths-Scylla/article-1087794-detail/article.html BridgeZone Ltd (2010) was commissioned by the National Marine Aquarium in Plymouth to monitor the condition of HMS Scylla in relation to diver safety. This included a visual inspection of warning signs and an assessment of the integrity of barriers put in place to prevent divers from entering the innermost parts of the ship considered to be unsafe. Structural damage was assessed and documented as were other potential hazards such as snags, overhangs and silt pockets. Varying levels of silt deposition were found around the vessel, ranging from <1 cm (light siltation) to >40 cm (heavy siltation). Silt had accumulated in most areas deep in the vessel, particularly the lower decks and very sheltered areas, and was considered to pose a significant risk to divers. However, the photographs presented by BridgeZone Ltd (2010) show the least colonization by marine organisms in these sheltered areas where heavy siltation has occurred (Figure 13a; b). Therefore, these areas are not expected to be of particular interest to divers. Furthermore, significant risks in the form of snags, loose ropes, wires, netting, structural damage (e.g. collapsed of cladding, air conditioning ducting, deck head linings) and other objects obstructing entrance/exit holes were also noted. The warning signs were either unreadable due to colonisation, or missing. BridgeZone Ltd (2010) emphasised that HMS Scylla was in a state of constant and progressive decay which would create a hazardous environment (Figure 13c; d). It was recommended that divers be properly advised of the potential hazards and that buoys were used to direct divers to safe entry and exit points. It can therefore be said that the risks associated with diving on HMS Scylla are varied and significant. Heavily silted areas can and should be avoided by divers and silt is just one of a number of hazards, many of which pose a far more significant risk (e.g. blocked entrance/exit holes). Page 61 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO (a) Light siltation (Deck 2) (b) Heavy siltation (deck 4) (c) Structural damage (d) Structural damage Figure 13. Condition of HMS Scylla. Source: BridgeZone Ltd (2010). As an indication of environmental quality, to date, there have been 13 positive and 3 negative diver comments on the Dive Site Directory regarding HMS Scylla. The National Marine Aquarium suggest that between scuttling in 2004 and June 2009 an estimated 40,000 divers have visited the wreck, with an average of 20 per day over the whole year (http://www.divesitedirectory.co.uk/dive_site_uk_england_southwest_wreck_hms_scylla.htm l) Other major concerns relate to sediment contamination and litter. The concentrations of chemical contaminants in the dredged material for sea disposal are within the standards approved for disposal using internationally and legally agreed limits. However, the licence conditions indicate that certain dock areas or certain depths of sediment may not be dredged because of the possibility of high concentrations of contaminants, especially polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAH). The dredging and dredged material disposal has been licensed based on advice from the Environment Agency, Natural England and Cefas, to avoid affecting local finfish or shellfish areas in order to prevent contaminants entering the human food chain. There is no evidence of the dredged material being contaminated with microbial pathogens. Despite this, any materials discharged into the estuary from sewage outfalls, storm water or combined sewage outfalls, run-off from urban and agricultural areas are likely to contain Page 62 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO pathogens. These aspects have been included in the Environment Agency classification of Whitsand Bay under the Water Framework Directive and the Bathing Beach Directive. As part of an undergraduate research project, Burkill (2006) carried out a limited number of interviews (of local people from various age groups and occupations) to gain an understanding of public perception of the disposal activities. However, the restricted information was centred on two key sources (Mr David Peake and Councillor Sheryll Murray) as Burkill (2006) claimed that they had provided all the necessary information. Councillor Murray highlighted to Burkill (2006) the need for dredging but also the need for an alternative means of dealing with the dredged material. The discussion also recommends that fishermen from Looe and Plymouth bring to shore all litter present in their trawls and do not dispose of waste at sea although the amount of litter from other boats operating in the Atlantic and English Channel is not known. The interview between Burkill (2006) and Mr Peake also highlighted the requirement for dredging and stated that the problem arose more because of the industrial debris rather than the surface silt and sand. The full transcripts of these interviews were included in the appendices of the dissertation but were not presented to the reviewers. The comments should therefore be treated with caution. Furthermore, the comments relating to silt accumulation contradict those made by Mr Peake during a meeting (November 2010) held between the MMO, Professor Mike Elliott and local stakeholders. During this meeting, evidence was presented to indicate the level of silt in Polhawn Cove. Both the interview with Burkill (2006) and the meeting in November 2010 highlighted the problems of industrial waste being lodged into rocks and dead marine life, particularly after the RAFT disposal, and criticised the authorities for the lack of research. Concerns over the impact on the local tourist industry were raised and it was suggested that more thorough checks on the waste (presumably the litter content) may alleviate the problem. Finally, it was suggested that finding an alternative disposal site would be acceptable provided that the area was appropriate and carefully chosen. In contrast, other users of Whitsand Bay have described the area as aesthetically pleasing although they do comment on the amount of beach litter. The National Coastwatch Institution provides a valuable service in the area and gives reliable observations regarding activity at sea (including disposal activity). Their staff at Rame Head have no concerns regarding slick production and they indicate that material from the barge is dumped very quickly and that there is no surface plume. Video footage posted on Facebook and the ‗Stop dumping in Whitsand Bay‘ website (http://www.whitsandbay.org/) shows a dredger at the disposal site discharging material by pumping it over the side. The boat was suspected to be washing its dredged material tanks rather than carrying out any disposal. Local stakeholders have a perception of silts in Whitsand Bay sediments but the scientific data and sampling do not show this. It should be noted that all but the very highest intensity of sampling would not detect any isolated pockets of silt and that such isolated and possibly ephemeral pockets of silt are unlikely to be of ecological significance in terms of their potential impact. Whitsand Bay was noted, according to available photographs studied in this review, to have clean, uniform sand in the summer and then be scoured in the winter, exposing rocks and stones on the surface. Local observers have indicated that Whitsand Bay beach frequently changes in this manner (Dr Annie Linley, PML, pers. comm.). Public advertising websites for the Whitsand Bay and Polhawn Cove area, for example the Polhawn Fort venue, use high amenity images of the beach which show the clarity of the Page 63 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO waters under calm conditions although even under such conditions there is still some sediment resuspension due to the swash and backwash of the waves. 5.8. Timing of disposal The dredging location, the depth and the seasonal timing of dredging and disposal are stipulated in the FEPA licence including the condition that disposal is only permitted during an ebb tide or during the preceding slack water. This ensures that the material either sinks to the bed with little opportunity for initial dispersion or it is quickly dispersed by the prevailing tidal currents, in an along or offshore direction. In general, dredging and disposal occur during the winter months although, in some years, small amounts of disposal have taken place during the summer (Figure 4). This is regarded as a precautionary approach, based on the possibility of fine materials being transported landward under a combination of wind and tidal conditions. Dredging in the estuary is carried out at a place and time to ensure that water quality barriers, due to suspended sediment, do not impair the upstream migration of fishes, presumably salmonids, Allis and Twaite shad, eels and lamprey. Although not recorded here, levels of suspended sediment and any decrease in dissolved oxygen due to resuspension of organic matter can act as a water quality barrier for migratory fishes (Elliott & Hemingway, 2002). 5.9. Alternatives to disposal at Rame Head 5.9.1. SITE RELOCATION Stakeholders with concerns regarding the current disposal operation have suggested that the disposal site could be moved further offshore, for example below the 50 m contour (Selkirk, 2005a; b). However, moving the disposal site has both environmental and socio- economic repercussions. Any new site is likely to develop adverse effects more rapidly than the old site would recover, if recovery could be detected. The increased cost of steaming (including increased staff time) if site was moved further offshore must be considered. For example, in the current situation relocating the disposal site to below the 50 m contour would involve an extra 7 km of steaming time by the dredger. During the autumn and winter months when disposal is permitted, adverse weather is also likely to cause difficulties and delays. At present, a dredging and disposal cycle (dredging, loading, steaming to the disposal site and back) can be completed within a working day. Increased distance to the disposal site would increase the cost associated with dredging and disposal operations in terms of additional staff or overtime, duration of the operation, fuel costs and the potential requirement for larger vessels. Furthermore, the costs of finding a suitable new site are high, with the cost of the Environmental Impact Assessment (EIA) being estimated as 1-3% of that of a capital operation. This cost would have to be borne by the licensee and cost- benefit considerations may be taken into account together with the environmental reasons for site relocation. It has been suggested that rather than a complete relocation of the disposal site, a minor adjustment of the site boundaries, by a slight-extension to the ESE, would enable disposal in a rocky area with greater potential for dispersal (Dr C Vivian, Cefas, pers. com.). This may reduce the potential for inshore movement of the dredged material although Page 64 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO hydrographic modelling and dispersion studies would be required to confirm this. The cost of this would be significantly lower than that associated with a full EIA. It is of note that there has been a similar slight modification to the disposal area in the past. A full economic appraisal of the present and any new, proposed site could be carried out but is beyond the scope of the current review. The appraisal would have to consider and quantify: the costs and benefits to the dredging companies and the industries supported by the marinas, harbour and port; the increased costs and carbon footprint of moving the material further offshore; the costs and benefits of other alternatives to disposal; the economic value of any benefits to the diving, tourism and recreational and commercial fishing as the result of relocation. This analysis could be carried out by centring the discussion on the ecosystem services and societal benefits of the operation and the area, hence considering the socio-economics of the societal benefits of diving, tourism and dredging and the ecosystem services provided by a fully-functioning ecosystem (see Atkins et al., 2011 regarding ecosystem services and aggregate extraction). 5.9.2. ALTERNATIVES TO DISPOSAL AT SEA. As indicated at the start of this review, the prevailing UK philosophy is based on a Weight of Evidence approach, which includes all aspects of the nature of the material being deposited, the nature of the receiving area both in the near and far-field, the environmental and economic consequences and benefits. This incorporates internationally agreed standards and requires extensive scientific capabilities. As with any environmental problem or cause of a potential problem, there are several or even many options and so all need to be subject to a Best Practicable Environmental Option/Best Available Technique policy and Environmental Impact Assessment, using practices developed over many years and enshrined in UK and European legislation and international agreements. Hence, the aim is therefore to consider the ecological and economic costs and benefits and thus maintain ecosystem services and deliver societal benefits (Atkins, et al., 2011). As indicated earlier, sea disposal of dredged material will be agreed after an evaluation of the disposal options. This is based on the OSPAR guidelines for the management of dredged material and the Dredged Material Assessment Framework (DMAF) of the London Convention and then implemented in the laws of the UK and devolved administrations through the FEPA 1985. Indeed, the applicant has to review the costs and benefits (in economic and environmental terms) of the alternatives during the licence application (e.g. Defra, 1999). Hence, within the management of sea disposal, alternatives have to be considered within the environmental, logistic and economic constraints. Available alternative methods relating to dredged material have been developed because material is either so contaminated that it cannot be disposed of at sea or is considered Page 65 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO suitable for and is also required for other uses. Unacceptably contaminated material can be capped in-situ or the various fractions can be removed, separated and dewatered for compaction and other disposal methods (e.g. to land or landfill). Other alternatives involve thermal immobilisation (e.g. to produce building materials), washing or chemical and biological stabilisation (Bortone & Palumbo, 2007). Each of these has environmental and economic consequences, not least because of the space and energy they require. As an example, the Flemish Government and the Port of Antwerp have launched AMORAS (Antwerp Mechanical De-watering, Recycling and Application of Silt) which aims to provide a viable means of dealing with contaminated silt following maintenance dredging of navigation channels (http://www.maritimejournal.com/features/tugs,-towing,-pollution-and- salvage/pollution-control/innovative-harbour-clean-up-underway-at-antwerp). Following dredging, the silt is stored and allowed to consolidate and de-water to reduce its volume. The fully de-watered silt is compressed into blocks which, once dry, can be stored on land for eventual use in construction. This strategy has been suggested by a local stakeholder (Mr Dave Peake) as a viable alternative to disposal at Sea at Rame Head, indicating that it could be jointly funded by the Ministry of Defence, Cattewater Harbour Commissioners, the Duchy of Cornwall and the Crown Estate. Therefore, whilst it may potentially be viable, it is considered here to be unrealistic to expect the above organisations to pay for such a facility without good reason. Furthermore, a full EIA and planning application would be necessary before any construction work could be permitted. The benefits of providing such a facility for a relatively small volume of dredged material need to be weighed up against the construction and operational costs. However, it should be emphasised that this innovative project is designed to deal with contaminated material, not simply with silt, and as such reflects the Slufter system used by the Port of Rotterdam (Vellinga & Eisma, 2005). This system aims to take contaminated material out of the system to a secure site. It was designed to receive the most polluted sediments, which could not be licensed for disposal to sea, until the pollution controls throughout the catchment were sufficient that the dredged material was no longer a threat. The decision, which would also have to be taken for the Tamar dredging, was based on the costs, environmental effects, applicability and availability space. The removal of wetland (estuarine habitat) to accommodate the system will also have further repercussions. The beneficial use of dredged material has been gaining acceptance both in the UK and worldwide for uses such as beach nourishment and sea defence. The purposes are generally to counter erosion or sea level rise and to maintain or develop habitats (e.g. Yozzo et al, 2004). The potential for beneficial use is dependent on the nature of the material being dredged, particularly the grain size required for successful nourishment (i.e. mud on mudflats and sand for coastal beaches). Bolam et al. (2006) consider the comparative environmental effects of intertidal and subtidal placement of dredged material, especially on the fauna of the receiving area. Dredged material from the Tamar could be deposited on land or sent to landfill but the costs are levied according to tonnage and type of material and are payable through the Landfill Tax. There are also environmental considerations relating to the movement of the material by road from port areas, perhaps to areas outside the city where space is available. Most importantly, and paradoxically, if material is too contaminated to be disposed of at sea then it is unlikely to be permitted for landfill because of the possibility of groundwater Page 66 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO contamination. Alternatively, the costs per tonne may be prohibitively high, reflecting the level of contamination. The prevailing policy is that accommodating large amounts of uncontaminated sediment would be a waste of the resource of landfill space. In the Tamar, the adopted philosophy has been to remove sediments from the system in order to maintain navigation channels, ports and harbours. However, in other estuaries (e.g. the Humber) dredged material is retained within the system to prevent a net loss of sediment which could increase erosion of intertidal areas, compromising the conservation status of the estuary. The ‗draw-down‘ of mudflats following subtidal dredging could reduce the area available for use by foraging and roosting birds. This will have to be taken into consideration by the forthcoming TECF dredging protocol discussions. Plough, agitation or Water Injection Dredging (WID), which is not regulated by FEPA licensing, involves the physical disturbance and redistribution (via the local current patterns) of the material within the system. In time, a proportion of the material may return to the dredged area or be transported elsewhere, within or outside the system. Deposition of dredged sediments within the dredging area particularly occurs in areas where the balance between the hydrography, bathymetry and sedimentation has been disturbed. Similarly, a beneficial use may involve placing dredged material in areas previously dredged but where the depth is no longer required. In the Tamar, the RAFT dredged area could have been used for receiving other dredgings but it is likely that now this area has accreted and reached a sediment equilibrium. A final option, of course, is to leave the material in situ but as this would have economic and operational repercussions for the dock and harbour activities and for regeneration and development plans, it is not considered further. Additionally, Siddorn et al. (2003) indicated the potential for the transport of contaminants to the eastern side of Whitsand Bay. It is assumed that in deciding that sea disposal is the best option, the implications of options such as keeping the dredged material within the Tamar/Plymouth Sound system, WID or plough dredging and/or leaving the material in-situ have been considered. 5.10. Adequacy of the Science & Monitoring As indicated in Section 3, the onus is on the disposer to demonstrate that they are not causing an adverse impact rather than on the regulator to show that there is an impact. Local stakeholders claim that there is a lack of research surrounding the impacts of the disposal activities at Rame Head but as shown here, Cefas have carried out a large amount of monitoring and research at Rame Head, compared to other UK disposal sites. In addition, Plymouth Marine Laboratory, the National Marine Aquarium, Plymouth and the University of Plymouth (via numerous undergraduate students) have all carried out significant research. Despite this, it is considered here that the research between the groups has not been coordinated and has therefore not been as cost-effective as it could have been. There have also been claims that knowledge of the contaminants present and their levels in the sediments is lacking. Mr Dave Peake feels that the authorities are failing the precautionary principle but evidence shows that the licensing arrangements, the implementation of OSPAR guidelines, the compliance with the FEPA licence and EC Directives are all designed to comply with this principle. Prior to disposal, chemical analysis Page 67 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO of dredged material is carried out to determine its suitability for disposal at sea. Cefas (2005) presents a summary of the monitoring data (with an extensive raw data set being held by Cefas) and highlights the spatial distribution and concentration of key contaminants. This work is supplemented by that of Lowe (2009) which indicated that there were no detectable biological effects (at a cellular level) of contamination in Whitsand Bay. It is of note that these studies have been carried out using approved methodologies and survey designs to detect spatial and temporal trends. However, the Cefas (2005) report is necessarily brief and was intended to provide an overview. Each major section of the report could be written as a standalone, and substantial, report although it is often not useful to present this level of detail in a report which is made publicly available and to non-scientists. It is emphasised that there is a further significant amount of ongoing work within Cefas to understand sediment contamination and to optimise methods for monitoring and assessment (C. Mason, Cefas. Pers. comm.). In relation to the ecological impacts, detailed analysis is currently being undertaken to determine spatial and temporal patterns in benthic community structure. This includes measures of secondary production and the use of regression techniques to investigate the relationships between the biological and the physical variables (e.g., depth, sediment properties) (Dr. S. Bolam, Cefas. Pers. comm.). This work, as with a large number of Cefas studies, has been submitted for publication in an international, peer-reviewed journal, an independent indication that robust science has been performed. The research and monitoring carried out at the Rame Head site and within Whitsand Bay is considered to be extensive in effort and budget and apparently exceeds that carried out at other disposal sites. However, at times, it has been poorly communicated, even though Cefas staff have participated in a number of stakeholder meetings. Furthermore, although Cefas have followed procedures and OSPAR guidelines as recommended, they have not necessarily added-value to create an integrative assessment. It should also be pointed out that different writing styles are required when presenting the results of such studies to practising scientists and the general public. Because of this, together with the sensitivity of the issue, there are ingrained and long-held perceptions in the area by local residents and stakeholders irrespective of what the analysis says. They have poor faith in the science carried out and, sometimes, even in the scientists doing the work. This has created a barrier to the acceptance of any objective science. There is a large degree of perception and comment passed on by word of mouth and not all of this is supported by personal and substantiated observations. For example, some reliable observations counter others. Whilst Cefas have undertaken a large amount of work, it is suggested that they have not spent sufficient time analysing the significance of change/types of change (or at least, this information has not been made publicly available). Similarly, the data between surveys and years have not been analysed together or rigorously and there has been little incorporation of the wider research. This review has been hampered by the absence of long-term data and an emphasis by the available science on synoptic surveys rather than looking at processes, i.e. the surveys indicate the characteristics present during the sampling campaign without looking at processes. While these comments relate to the 2005 report, it is acknowledged that Cefas carry out a significant amount of other research in relation to dredge disposal. As some reports by Cefas are presented as a ‗preliminary analysis‘, e.g. the 2005 report, they are advised to ensure that they record the final analysis. There are also some mistakes and simple errors in the Cefas reports, such as in terminology, species Page 68 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO names and interpretation, and whilst none of these errors is sufficient to warrant questioning the quality of the overall science, they will cause the audience to question the rigour of the science being carried out. In this review it has become apparent that details of the licensing procedure, the background philosophy for licensing and environmental and economic appraisal, and the nature and adequacy of the science either have not been presented to the stakeholders sufficiently (either in time or in form); alternatively the stakeholders are still unwilling to listen to the arguments. Some local stakeholders appear to be unwilling to believe in the scientific evidence presented and have expressed the need for further research. Whilst more research could potentially be carried out, it has to be proportionate to the nature of the problem and it is not the role of this review to pass judgement on the way that funds for monitoring and research have been used since that is a political decision. Furthermore, it is beyond the scope of this review to determine the ratio of funding for the environmental work to that of the capital cost of either the dredging operation or the economy of the activities protected by dredging, i.e. the dock and port development. Despite this, there is the potential for gathering other, quantitative data such as the use of webcams on HMS Scylla to gather turbidity data and link this to the sea state, weather and disposal regime information and to include the diving fraternity in rigorous monitoring. Page 69 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO 6. DISCUSSION, RECOMMENDATIONS AND CONCLUSIONS The long history of dredging and disposal of the Tamar dredged material has been carried out within the prevailing philosophy that disposal at sea is environmentally and economically the best option in cases where the material is considered to pose little threat to the marine environment. It is emphasised that the disposal of dredged material at sea is a permissible activity and the activity is suitable for the relocation of natural and uncontaminated sediments. However, the dredging companies are obliged to ensure that the material is free from all contamination, not just chemical contaminants but also litter where possible. As mentioned earlier, the significance of any adverse impacts of disposal can be considered in statistical, ecological and socio-economic terms. Similarly, if there is a perception of adverse impacts, society will be regard this as the same as the demonstration of adverse impacts. It is notable that stakeholders opposed to the disposal have created the adverse publicity and in particular certain stakeholders have been extremely active in raising the profile of the perceived problem. Demonstration of the significance of an impact has to be in terms of statistical, environmental and socio-economic significance. Statistical significance Taking the above types of significance in turn, there have been limited attempts to determine the statistical significance of differences in environmental quality within and outside the disposal area. Multivariate statistical techniques, used commonly and as standard in environmental assessments, have shown that there are numerical differences in community type but, because of the nature of open and highly variable marine systems, it is difficult to separate these changes from background and inherent variability. The levels of contamination are considered elevated in a few areas and concentrations of certain contaminants exceed some of the guideline values (including background concentrations) for sediment quality. However, due to the analytical methods used, concentrations of some contaminants should be considered an overestimate. In the case of the rocky reef ecology, there are apparent differences between the east and west of the entrance to Plymouth Sound but these differences have not been tested with scientific or statistical rigour. Environmental significance The area has been subjected to a large amount of scientific survey and analysis, much of which has been done by Cefas. However, the area has benefited greatly from the large amount of locally available marine scientific expertise, at the Plymouth Marine Laboratory, the Marine Biological Association, The National Marine Aquarium and the University of Plymouth. Cefas have acted extensively in their defined and accepted role of providing the best available science and advice to the licensing authorities. That science has taken the well-defined route of understanding the behaviour of the system, the behaviour of the activity, the behaviour of physical and chemical materials put into the system, the nature of the biological features at risk, the behaviour of materials taken up by the biota and the repercussions of those changes. Of course more research could have been carried out but this has to be proportionate, within accepted and allowed budgets and based on priorities. It has been estimated that to date the Cefas involvement in Rame Head has cost £850-900k since the early 2000s and that this work has been carried out both as part of a national remit but also as dedicated studies of the Rame Head area. Page 70 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Whilst the site continues to receive screened material, mostly from maintenance dredgings, there is a long history of the site receiving unscreened capital dredging. Until 2 decades ago, munitions and dockyard debris (cables, webbing, gasmasks, sheet plate, etc) has contaminated the seabed even though much of this material will remain buried at the disposal site. In contrast to many other pollutants, litter has a very long half-life and so it is preferable that the material remains buried at the site. As such, even if the disposal site was moved, there would still be a legacy from the historic disposal. The essence of determining whether dredging and dredged material disposal has an environmental effect is to assess its influence on the ecosystem services, i.e. the ability of the marine system to maintain its accepted ecological structure and functioning and societal benefits (i.e. the provision of features required by society). Hence it has to be demonstrated that dredging and dredged material disposal have not adversely affected the hydrography, sediment state and producer, prey and predator ecology nor affect the system‘s ability to support navigation, tourism, fisheries, recreation, etc. The protection of these features therefore aims to ensure the sustainable use of the marine system, the raison d‘être of Defra and the MMO, and to achieve the Ecosystem Approach to marine environmental management. As indicated in the introduction, the sustainability of human activities can be interpreted against the DPSIR approach and the 7-tenets – that the operation fulfils the environmental, economic, technological, social, administrative, legislative and political constraints (Table 3). It was beyond the scope of this review to perform a Best Practicable Environmental Option appraisal for the Tamar dredging activities although a brief assessment of the other options (beneficial use, dewatering and treatment, to landfill) indicates that sea-disposal is the best option provided that the material meets the required standards and that other options are not viable. This limited assessment has not included a rigorous cost-benefit analysis of the current disposal practice, the movement to a site further offshore or the use of onshore disposal/beneficial use. However, the available evidence suggests that there are no environmental benefits and indeed there will be environmental costs in moving the disposal site. Evidence elsewhere suggests that in moving such a site the new site would deteriorate more quickly than the old site would recover this giving a net loss in environmental quality. Socio-economic significance Whilst a full analysis of the socio-economic issues surrounding the disposal activity has not been carried out, these issues have been highlighted throughout the review. Concerns include the potential for loss of income for businesses associated with the tourism, recreation and fishing industries if disposal activities continue in the present manner. In contrast, there is potential for loss of income to the dredging companies and local developers if significant changes to current practice were enforced. Similarly there are economic consequences of moving the site, in the surveys needed to locate a new site, the Environmental Impact Assessment which would be required at the site and the ongoing operational and environmental costs. These include the cost of increased carbon emissions which would result from increased travel to a site further offshore (Table 3). Page 71 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Table 3. Assessment of present and alternative dredged material disposal practices against the 7-tenets. 7-tenets Present operation Disposal site re-location On-land alternatives to sea disposal Environmentally sustainable Yes, as no unacceptable environmental There are environmental There are environmental effects have been detected although a consequences both at any new and old consequences of any alternatives but carbon budget for the operation has not site; the respective speed of these could be mitigated and/or been calculated deterioration and recovery are unknown compensated (e.g. a loss of estuarine but likely to differ between any new site wetland for any treatment plant would and the existing site; a carbon budget require compensation). This is not a would require to be included sustainable long term option. Economically viable This has not been compared rigorously Increased costs of the site selection, an The Cost benefit Analysis of any new but it is assumed that it is within the EIA, any Appropriate Assessment, and operation, including its carbon budget business case of those funding the ongoing operational changes and would be required; costs may be operation; the economic costs of public environmental monitoring would have offset if there are economically perceptions of poor environmental to be met. beneficial uses of the material (e.g. quality have not been determined; the for countering sea level rise); high costs of the environmental environmental monitoring costs monitoring performed have to be would also have to be included included here Technologically feasible Yes, under the current vessels and The vessel may have to be larger to There is a large and increasing operation accommodate a longer steaming time, experience of alternative disposal weather conditions offshore and a options, of the engineering aspects greater volume to allow for longer and of handling large amounts of dredge cycles materials – these need testing on a site-specific basis. They are unlikely to be sustainable in the long term at Rame Head. Page 72 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Table 3. Continued. 7-tenets Present operation Disposal site re-location On-land alternatives to sea disposal Socially desirable/ tolerable There has been no rigorous assessment This would placate some users (e.g. This may be socially acceptable if all of this although some local users and divers) and residents although others other tenets were fulfilled but would residents have long-held objections to (e.g. fishermen and anglers) have occupy land and facilities and thus the site; there may be an element of indicated objections may encounter local opposition local geography (e.g. ‗Devon‘s waste in Cornish waters‘) Administratively achievable Yes, the site has been licensed and Yes, if the new site complies with all Yes, again the statutory bodies are in agreement is from the statutory bodies regulatory requirements place to consider and agree with conditions applied alternatives Legally permissible Yes, the current site complies with Any new site could be licensed as long Any new method of dealing with the national and EC law and international as it complies with national and EC law dredged material must comply with obligations and agreements and international obligations and national and EC law. agreements Politically expedient The accepted policy is for sea disposal This may meet opposition if perceived If presented as having benefits for of uncontaminated dredging; there is as a return to the ‗out of sight, out of the ecology and the economy of the some political opposition but it is mind‘ philosophy whole area unknown how representative this is. Page 73 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO The ability of the marine system to assimilate the dredged material without compromising the ecological and socio-economic aspects is paramount to a sustainable dredging operation. This review has assessed whether the various stakeholders have fulfilled the roles expected of them. The licensing authorities (the MMO using the Environment Agency, Harbour Authorities and Natural England as statutory consultees) appear to have taken the available science and economical aspects into account to provide a sustainable solution. The Government‘s scientific advisors, Cefas, have carried out a large amount of new scientific research in providing advice. The dredging companies have done what is expected of them and have fulfilled their licensing conditions. However, local stakeholders have expressed concern over the environmental and economic impacts of the current dredging and disposal practice. These concerns can be summarised under 8 categories: (i) Increased turbidity and siltation at the HMS Scylla wreck dive site result in poor visibility and associated problems with safety and quality of the diving experience: Silt has accumulated in sheltered areas of the vessel, as would be expected in any area or structure in which there is little water movement. Prior to scuttling, modifications were made to the vessel to make the diving more interesting and this may have led to the creation of sheltered areas in which silt could settle. The comments of the dive community and the number of divers visiting the wrecks in the area, including HMS Scylla, do not on the whole indicate that divers are deterred from diving in the area. Whilst some respondents emphasise that the water in Whitsand Bay was turbid on a seasonal basis, it was suggested that a larger number indicated that it was clear or had no opinion. (ii) Siltation of the beach and rocky reefs at the eastern side of Whitsand Bay (Polhawn Cove): The available data indicate that silt will accumulate in any sheltered area but that it is easily resuspended under regularly and normally occurring tidal and wave conditions. The hydrographic conditions of the Rame Head/Whitsand Bay area suggest that fine material will be transported eastwards along the bay on flooding tides and that there is potential for material to be transported around the Rame Headland during outflow from the Tamar on an ebbing tide. The resuspension of bed sediment by tidal action, wave, swell and residual currents is possible and any material in the surface layers can be affected by the weaker wind-driven currents which, with predominant SW winds, could take material landward. However, in addition to the fine material placed in the disposal site, the muddy substratum offshore and sediment exported from Plymouth sound can add to the suspended sediment load and are therefore also a potential source of the silt in Polhawn Cove. The respondents often referred to the accumulation of silt in Polhawn Cove, from the disposal site. While it is acknowledged that fine particles will be deposited in sheltered areas, it is not possible to say whether the material would have accumulated even without disposal taking place, i.e. an experimental control is not possible. It is also not possible to say whether the particles came from the disposal ground, the fine sedimentary areas offshore of Whitsand Bay or from the Tamar estuary/Plymouth Sound. Page 74 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO (iii) Litter on the beach and on the seabed: There are no doubts that litter is washed up on the local beaches and becomes trapped in rocky reefs area, especially given the hydrodynamic transport patterns. The litter is also likely to be buried in areas of soft sediment, especially given that for many decades there were no controls on dockyard litter being included with the dredgings. The litter observed is from several sources and includes both household and industrial materials and, because of the hydrographic patterns described above, the light material will be deposited along the strandline. Furthermore, marine litter is a global problem and due to ocean circulation patterns, litter can be deposited on beaches a great distance from the source. The webbing, gas-masks and aluminium sheeting which most likely emanated from the dockyard will have a long half-life and can presumably be regarded as dockyard materials deposited several decades ago. It is likely that much of this, and any munitions, placed in the old licence area (which is mostly contiguous with the present area) will remain buried in the sediment unless disturbed by natural or human activities. Given that no bottom trawling occurs over the disposal site then the material should remain buried. In addition, it is appropriate to consider whether litter is merely contamination (the presence of the material) or whether it constitutes pollution, i.e. the ability of the contaminants to cause biological damage or the loss of amenity value (‗aesthetic pollution‘). The material observed on photographs and videos is unlikely to have ecological effects, and in many cases will eventually be assimilated into the sediments or trapped and thus taken out of circulation. There are no specific records of organisms, especially seabirds, sharks, sea turtles and marine mammals being harmed by litter in the area but there is potential for it to happen. However, in having an aesthetic effect, and possibly even being harmful to other users (e.g. a danger to divers, damage to fishing gear), then it is an unacceptable problem. Despite this, there is no simple way of removing the material other than physically retrieving it by hand. It is of note that local users of the beach clear litter from the beach in order to increase the amenity value. (iv) Sediment contamination and accumulation of contaminants, particularly at the eastern end of Whitsand Bay: Trace metals and organic compounds such as PAHs (polycyclic aromatic hydrocarbons) have been recorded in fine sediments in the area and organometallic compounds have been detected in the biota. However, in the case of metals, analysis is only carried out on the silt/clay fraction (<63 µm) of the sediment and this represents a small proportion of the sediment composition as a whole. Therefore, metal concentrations should be treated as an overestimate and contamination can be considered low. Although PAH concentrations are elevated in Polhawn Cove, they do not exceed guideline values. However, they are close to the Effects Range Low (ERL) which may warrant further investigation. As there are few, if any, pollutants which could only have come from the dredged material then it is not possible to fingerprint contaminants in the bay as a whole or trace them only to the dredged material. If fine suspended particles and organic detritus naturally get washed out of the Tamar on an ebb tide and around the Rame Headland, then this would also transport pollutants from the estuary. Page 75 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO As with many shipping and boating areas worldwide, the antifouling paint TBT has contaminated the sediment and biota in Whitsand Bay. There are several sources of this contamination: paint flecks in the dredged material, natural transport of contaminated sediments from the Tamar and other port/marina areas, and from HMS Scylla which was not completely cleaned of paint before being scuttled. Finally it is of note that the south-west region has many historical metal mining areas and runoff from spoil heaps from these enters several of the local estuaries, again leading to an overall higher level of contamination than elsewhere. Hence, any attempt to separate the contamination from the dredged material from the background levels, either natural or anthropogenic, is not possible unless a specific tracer could be found. (v) Potential loss of revenue, due to actual or perceived degradation of the HMS Scylla dive site: As indicated above, there is conflicting evidence and views regarding the impact of the disposal activity on water clarity and the accumulation of silt at the HMS Scylla dive site. It is estimated that the local dive sites are well used but it is not possible to determine if this use is lower than would be the case without either adverse publicity or perceptions of impacts. Based on comments made, the local area has to counter the perception, held in many estuarine areas, that silty equates to dirty which equates to polluted which equals unhealthy when in fact it is a natural state in tidal areas dominated by soft sediments. (vi) Impacts on marine life, reduction in commercial and recreational fishing: Using a detailed study and multivariate analysis, the disposal site and immediate surrounding area shows evidence of a modified benthic faunal community which is influenced by the disposal of dredged material. However, as the disposal site is relatively heterogeneous in terms of habitats (with sand pockets, rocky outcrops, sloping shelf area and vertical surfaces and relatively smooth, deeper areas), the inherent variability of the physical conditions of site makes it difficult to detect a change due only to the disposal. Despite this, the site does not show the characteristic fauna of a degraded seabed which would include pollution and disturbance tolerant species. It is of note that inshore reefs in the eastern part of Whitsand Bay (west of Plymouth Sound) appear to be less diverse than those at the eastern side of Plymouth Sound entrance. This is based on informal observations rather than rigorous survey and is difficult to support based on the limited evidence. However, a comparative reduction in species diversity on the reefs to the west of Plymouth Sound may be due to the influence of out flowing waters from the Tamar estuaries complex. With regard to the commercial and recreational fishing, there are only ad hoc records of a decline in fish stocks over time and insufficient evidence to support this claim. Given that the disposal has occurred since the early part of the last century, it is not possible to attribute changes to the disposal activities because reliable historic or baseline data do not exist. In addition, there have been large scale changes in fish stocks due to over-fishing and changes in species distributions, including the presence of rarer, more southerly species occurring in the waters of the SW due to climate change. Page 76 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO (vii) Public health issues: The public health issues have centred on perceptions of pollutants in the water column, the sediments or the biota and while not expressed, it is assumed that the fears relate to entry to the food chain. Therefore, the Environment Agency recommended that disposal takes place late in the year after the fishing and shell fishing season. This has not been extensively investigated as there are no designated shellfish beds in the area. Therefore, analysis for quality under the EU Shellfish Health and Hygiene Directives has not been carried out. The ecological quality of the area has been classified as good rather than high under the EC Water Framework Directive. The dredged material is tested and licensed for disposal on the basis that the concentrations of pollutants such as PCBs, trace metals and PAHs comply with the sediment quality criteria agreed by OSPAR. With regard to the presence of potential microbial pathogens, the western end of Whitsand Bay beach passes the higher level guideline quality standards of a designated bathing beach under the EU Bathing Waters Directive. The unfortunate and tragic deaths of two divers whilst on HMS Scylla was alleged to have been caused by them becoming disorientated by high levels of resuspended silts in the enclosed parts of the vessel. While there is no doubt that fine particles have accumulated in sheltered parts of the vessel and that these were resuspended by the divers, there is no evidence to indicate that the accumulated levels of silt were due to the disposal operation. (viii) The monitoring is inadequate: There has been an extensive amount of monitoring carried out at a high cost but this has been justified against priorities based on the need for environmental protection and public concern. The monitoring has followed accepted procedures and protocols developed over many years and at many disposal sites, not only in the UK but worldwide. It has focussed on the hydrographic-sedimentary system as the latter is the part of the marine system most expected to show the effects of sediment deposition. However, the use of a standard approach can be criticised for not being sufficiently site-specific in formulating and addressing testable hypotheses for the area. In particular, there should have been greater emphasis on the significance of changes found and there is the need for a better integration of the science used (e.g. there is the need to put together the sequence of change across the features: hydrographic-geomorphological-sediments-contaminants-community biota- bioassay- dredging procedures). As indicated above, the understanding of the central sequence of hydrography leading to sediment distribution and dispersion patterns, in turn leading to biotic changes, is fundamental to understanding the concerns surrounding the disposal activity at Rame Head. Various hydrographic studies have been carried out by different scientists working in different organisations, such as PML and Cefas, and their findings have been broadly similar. However, other scientists (e.g. Professor Robin Pingree of the MBA) criticised the earlier work carried out by Cefas which did not account for wind-induced currents, sea state and swell. It is considered that Cefas staff now have a detailed appreciation of the hydrographic conditions of the area although they could have communicated this in greater detail. It is also of note that regardless of the quality of the modelling studies, significant amounts of fine material have not been recorded in the sediments in Whitsand Bay (intertidal or subtidal). Page 77 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO It is considered that the Cefas staff have engaged with the stakeholders when requested and fulfilled their duties as government advisors. However, they have not always fully communicated their results or fully explained the licensing process or the constraints of detecting effects. It is acknowledged that Cefas staff have made attempts to synthesise their findings and have the findings tested in peer-review scientific publications. It is of note that a peer-reviewed summary of the features of the area has recently been accepted for publication in an international journal (Dr S. Bolam, Cefas. Pers. comm.) but that a synthesis of the physical aspects has not appeared (note that such a synthesis was cited in the paper by Okada et al 2009 as Larcombe et al in prep. but unfortunately this was not produced). Overall, it is considered that the research and monitoring carried out has been adequate, proportionate to the issues being addressed and in line with similar environmental concerns elsewhere. However, it is concluded that the severity of the concerns raised by stakeholders has been exacerbated because there has been poor communication by the authorities and others on why disposal is necessary, the licensing procedure, the type of material licensed for disposal, and on the relative amounts of material for disposal with respect to natural sediment transport processes. In addition, it is always unfortunate that the local media are more willing to report perceived problems rather than report facts in an objective manner. For example, while the operation is mostly relocating dredged material settling in inconvenient places in relation to our use of the estuaries and marine environment, it is pejorative to use the term ‗dredged spoil dumping‘. The stakeholders with concerns about the disposal activity should be congratulated for skilfully and assiduously raising awareness of the topic and keeping it in the public arena. Local involvement in environmental issues is always to be welcomed. However, it is concluded that they have been selective in their use of the available science and have not always appreciated the interpretation and the value of the evidence. They have often relied on student projects for evidence but it is apparent that while some of these may contain useful information, they are often either unreliable, are limited by time and funding constraints (for carrying out new work) or have to rely on existing data and summaries. The dissertations, especially those from undergraduates, should always be regarded as education for the students rather than published and peer-reviewed articles. For example, those with concerns about the disposal operation, and indeed various student projects carried out in conjunction with them, appear to make the assumption that the inshore substratum of Whitsand Bay is primarily medium and coarser sands and that of the Tamar is fine sand, silts and clay. Therefore, any fine particles found anywhere, either in depositing pockets in and around HMS Scylla, in the reefs and inshore in Polhawn Cove must be from the dredging disposal operation. In this review, these dissertations have been read with interest and compared with information from the professional scientists both at scientific institutions in Plymouth and at Cefas. Consequently a large amount of time has been taken to consider the validity and provenance of the ad-hoc information and to compare this against detailed quantitative information from professional scientists. Page 78 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO 6.1. Future Practices and Recommendations Dredging practices and licensing: The dredging company should ensure that its controls on litter entering the dredging barge hopper are as effective as possible although it is acknowledged that screening does occur and that smaller grids cannot be used without hampering the process. There should also be checks on quay-based practices to minimise waste entering the system, following IMO (International Marine Organisation) guidelines. It is of note that the recently-agreed EC Marine Strategy Framework Directive will include for the first time, litter as an element affecting marine environmental status. This may lead to a more concerted attempt to assess the impact and control this diffuse contaminant. The Tamar Estuaries Consultative Forum (TECF) is to be congratulated in taking the initiative for helping to devise a dredging protocol. However, while the focus is on helping the statutory bodies and dredgers to protect the European Marine Site, it would be encouraged to include repercussions for the wider Rame Head area, disposal site and Whitsand Bay. It is encouraging that the TECF has a constituent body which will allow it to take such a wide view. Based on the brief analysis in this review, there are few economic or environmental grounds for considering moving the disposal area to a new site further offshore or for considering different onshore disposal options. Despite this, it would be valuable to carry out a detailed research project involving environmental and economic scenario-testing for different options, if only to provide further evidence on the environmental and economic costs and benefits of the different disposal options. Available Science: The rigorous scientific assessments of the hydrography and sedimentology of the Rame Head-Whitsand Bay area have concentrated on the area from the disposal ground and inshore. Given the nature of the dredging and disposal activity the scientific studies have rightly concentrated on the sedimentary regime and the influence of the hydrographic regime. The sampling areas have recently been placed according to the likely dispersion of the material. However, for a more complete understanding of the dynamics of the area, there needs to be a wide scale assessment of silt dispersed over the wider offshore area. Following earlier work by Okada et al (2009), there is the potential for the innovative use of particle size modal distributions to further interrogate the sediment patterns and link these to the source material. This may give a clearer assessment of the links in the sequence of geomorphological – sedimentological – coastal/estuary features and confirm long term dispersal patterns of the fine sediment fractions. The past surveys have relied on obtaining samples by remote grab and core sampling and by seabed acoustic techniques. More targeted and precise sampling could be carried out but this would need to include diver surveys accompanied by surveys to obtain more video footage. Similarly, Cefas have placed little emphasis on understanding the ecological quality of the hard substratum, especially rocky areas, and hence they have been unable to counter comments from the stakeholders with concerns regarding the quality of the reef areas. An opportunity has been missed to engage with the local diving fraternity to obtain more rigorous scientific information. Several studies have indicated that further comparative analyses of the sediments in the wider Rame Head and Whitsand Bay area is required. In particular, comparison between Page 79 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO the material from the Tamar with that in Whitsand Bay, the disposal site and the area to the south of the disposal site would be useful. Whilst this would be of interest, it may still only confirm that fine sediments are present offshore, are present in the Tamar, can be transported out of the Tamar and have been placed in the area for a century as a result of the disposal activities. Research in this area would give valuable information for future studies of disposal grounds here and elsewhere. Community Involvement: The diver community is rightly concerned regarding evidence of large pieces of litter on the seabed but as indicated previously this type of diffuse pollution is difficult to address. As much of it has apparently been on the seabed for years, if not decades, it becomes an aesthetic problem rather than having any impact on the marine life. Indeed once the material is inert and not giving off any dissolved contaminants then the biota will use it merely as another subsea surface for colonisation. Despite this, given the estimated number of divers to the areas then a code of practice which recommends that they retrieve dangerous pieces of litter may allow them to feel they are contributing to the solution. The Plymouth area has arguably one of the highest concentrations of marine scientists in the UK, who continue to study the marine features of the area and have a long history of doing so. By its nature, however, this research is not coordinated and so will not always give a thorough assessment of the area. The University is to be congratulated in encouraging wider stakeholders to lecture to their students and to become involved in research projects and dissertations. However, the University supervisors have a duty to present a balanced view to their students and ensure that external lecturers are also giving a balanced view. It has been apparent that the students have not kept an open, objective mind in carrying out their research. In short, the students carried out studies expecting and therefore finding adverse impacts. 6.2. Conclusions In summary, the disposal site shows limited evidence of disposal activities via contamination and biota change, and is rightly regarded as a dispersing site. Accordingly the material is dispersed widely (predominantly alongshore and offshore with some onshore transport). Whilst there is a poor indication of why the site was chosen initially, it is assumed to have been a pragmatic decision with reference to the dockyard (in terms of the costs of dredging and disposal), together with local knowledge of current patterns. This would have involved consideration of the cost and time associated with dredge disposal and also the potential for material to be transported back into Plymouth Sound. However, it is now considered more environmentally sustainable to keep licensing the existing site than choose another site. The present licensing regime is designed to ensure that contaminated dredged materials are not disposed of to sea and that the dredged material does not have a toxic component. It is also of note that the increasing controls on pollutants at source are minimising the pollutant loads entering the watercourses and thus contaminating the sediments to be dredged. The evidence does not indicate that environmental problems are being caused by the present disposal operation and that any problems which can be detected are likely to be related to historical disposals. Page 80 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO The scientific studies carried out in the area by Cefas and other organisations have given a large amount of information, data and understanding. While of course, further research can always be performed, it is considered that the surveys (their components and funding) have been proportionate to the environmental issues being addressed and they have followed the accepted international guidelines for monitoring dredged-material disposal grounds. However, there have been failings in the way the findings and background to the dredging and disposal operations have been communicated to stakeholders. HMS Scylla as a dive site and artificial reef can be considered a success in terms of the numbers of divers attracted and their overall response to the dive site. The evidence suggests that it has been colonised by marine organisms as expected and the colonising organisms do not indicate that the vessel is situated in turbid waters. It is expected that the interior parts of the vessel would scavenge fine particles and that pockets of silt would accumulate. Indeed this might have been encouraged by creating dive-through areas prior to scuttling. It is hoped that experience gained through the creation of this dive site will be of value to similar ventures in the future. In addition, there is, as expected, evidence of deterioration of the vessel which needs to be monitored as this also poses a health and safety problem. Divers constantly need to be made aware of the dangers of diving on man- made structures and the diver community has a responsibility in this direction. The concerns regarding litter at the site and in adjacent areas are warranted and there is good evidence of the type of litter encountered. However, the larger pieces appear to have emanated from the dockyard and estuarine activities many years ago, at times of lesser control than today. Given the half-life of this type of litter, it will remain for many years and can only be removed by hand or become buried by sedimentation. The litter along the beaches in the area emanates from many sources, irrespective of the disposal of dredged material, and is thus part of a wider problem. There are concerns that even if no effects are shown, the perception of effect is just as important as the presence of actual effects. Such perceptions are difficult to counter although in this case, it is widely believed that the solution would be to move the disposal site. However, this is not considered to be cost-effective nor would it bring environmental benefits. Indeed if a carbon budget was added into the considerations, then the extra steaming time to a site further offshore would be even more damaging. Despite this, a decision could be made on economic rather than environmental grounds but there would need to be a site selection investigation and an EIA at the chosen sites. An Appropriate Assessment may also have to be carried out if there is the possibility of this activity influencing the local Natura 2000 site. It is again emphasised that in any such assessments, the onus would be on the licensee to show no effect rather than on the statutory bodies to demonstrate an effect. Based on a brief appraisal here, there is little economic or environmental justification for moving the disposal site further offshore, into deeper water, or for considering other onshore disposal options. If the material being dredged did have an economic value and use then this should be considered but this is unlikely because of its nature. This would also have environmental consequences. Page 81 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO 7. REFERENCES Atkins, J.P., Burdon, D., Elliott, M. & Gregory, A.J. 2011. Management of the marine environment: integrating ecosystem services and societal benefits with the DPSIR framework in a systems approach. Mar. Pollut. Bull. doi:10.1016/j.marpolbul.2010.12.012 Bale, A.J. & Kenny, A.J. 2005. Sediment analysis and seabed characterisation. In Eleftheriou, A. & McIntyre, A (Eds). Methods for the study of marine benthos (3rd edition). pp 43-86. Bale, A.J., Uncles, R.J., Villena-Lincoln, A. & Widdows, J. 2007. An assessment of the potential impact of dredging activity on the Tamar Estuary over the last century: Bathymetric and hydrodynamic changes. Hydrobiologia. 588: 83-95 Black & Veatch Ltd. 2010. Baseline document for maintenance dredging in Plymouth Sound and Estuaries European Marine Site. Report to Debut Services (SW) Ltd and Defence Estates, 147pp. Bolam, S. G., Rees, H.L., Somerfield, P., Smith, R., Clarke, K.R., Warwick, R.M., Atkins, M. & Garnacho, E. 2006. Ecological consequences of dredged material disposal in the marine environment: A holistic assessment of activities around the England and Wales coastline. Mar. Pollut. Bull. 52:415-426. Bolam, S.G., Mason, C., Bolam, T., Whomersley, P., Birchenough, S.N.R, Curtis, M., Vanstaen, K., Rumney, H., Barber, J., Law, R., Aldridge, J, Nye, V. & Griffith, A. 2009. Dredged material disposal site monitoring across England and Wales: summary of 2008-09 sampling under SLAB5. Cefas contract report SLAB5, 120pp. Bortone, G. & Palumbo, L. (Eds). 2007. Sustainable Management of Sediment Resources: Sediment & Dredged Material Treatment. Elsevier, Amsterdam. BridgeZone Ltd. 2010. Survey Report. The condition of the Scylla Reef lying in Whitsand Bay. Report to the National Marine Aquarium, Plymouth, 21pp. Burkill, S.D. 2006. A study of offshore disposal of dredged materials and associated impacts: Whitsand Bay. Unpublished BSc. thesis, University of Plymouth. 76pp. Cameron, R. 2009. A review of the Scylla Monitoring Programme: Is sediment from the Rame Head Disposal Site being deposited around the Scylla. Unpublished BSc. thesis, University of Plymouth, 46pp. Canadian Council of Ministers for the Environment (CCME). 2000. Canadian Sediment Quality Guidelines for the Protection of Aquatic Life: Summary Tables. Extract from Excerpt from Publication No. 1299; ISBN 1-896997-34-1. http://www.ccme.ca/assets/pdf/sedqg_summary_table.pdf. Accessed 20.11.2010. Cefas. 1993. Fifth Report of the Group Co-ordinating Sea Disposal Monitoring. Marine Pollution Monitoring Management Group. Aquatic Environment Monitoring Report No. 39. Page 82 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Cefas. 2005. Environmental impacts resulting from disposal of dredged material at the Rame Head disposal site, S.W. England: An analysis of existing data and implications for environmental management. Cefas, June 2005, 120 pp. (http://www.cefas.co.uk/media/29994/20050602_rame_head_report.pdf) Cefas. 2005a. Cefas response to Bruce Selkirk‘s note ―Whitsand bay and the Cefas report - some areas of serious concern‖ (prepared by Bruce Selkirk, July 2005). (http://www.cefas.co.uk/publications/miscellaneous-publications/environmental-impacts- at-rame-head/cefas-response-to-bruce-selkirks.aspx Cefas. 2005b. Cefas response to ―Scientific appraisal of conditions found at Rame Head and Whitsand Bay‖ by Professor Robin Pingree, 8 August 2005. Cefas. 2007a. Rame Head: Furthering our understanding of the Ecological Consequences of Dredged Material Disposal Activities. Report ME1116 to Defra, 19pp. Cefas. 2007b. 2007 Research Vessel survey report; Cefas Endeavour 5/07 Cefas. 2008. Cruise Report CEND608 for the Quarter one Southwest Beamtrawl survey. Cefas. 2009. 2009 Research Vessel survey report; Cefas Endeavour 05/09 Cefas. 2010. Disposal of dredged material at the Rame Head Disposal Site: A review of Cefas‘ Role in its Monitoring and a Summary of the Monitoring Evidence. Report to the Marine Management Organisation, 28pp. Cook, J.M., Gardner, M.J., Griffiths, A.H., Jessep, M.A., Ravenscroft, J.E. & Yates, R. 1997. The comparability of sample digestion techniques for the determination of metals in sediments. Mar. Pollut. Bull. 34(8): 637-644. CSEMP 2010. Clean Seas Evidence Monitoring Programme Green Book. Appendices 7-9. http://www.cefas.co.uk/publications/scientific-series/green-book.aspx Defra 1999 Economic Evaluation of MAFF‘s policy relating to the disposal or dredged waste at sea. Prepared by BMT and ABPmer Ltd for: Ministry of Agriculture, Fisheries and Food, Report Number: 505S012, Issue 1.00: May 1999; accessed via http://www.defra.gov.uk/evidence/economics/foodfarm/evaluation/wastedis/ Defra, 2010. Government guidance to the Marine Management Organisation (MMO) on its role in relation to applications, and proposed applications, to the Infrastructure Planning Commission (IPC) for development consent under the Planning Act 2008. http://www.defra.gov.uk/environment/marine/documents/legislation/mmo-ipc.pdf. Accessed on 18.1.11. Elliott, M., 2010. Marine science and management means tackling exogenic unmanaged pressures and endogenic managed pressures – a numbered guide. Marine Pollution Bulletin. doi:10.1016/j.marpolbul.2010.11.033. Page 83 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Elliott, M. & Cutts, N.D. 2004. Marine Habitats: loss and gain, mitigation and compensation. Marine Pollution Bulletin, 49, 671-674. Elliott, M & Hemingway, K.L. 2002. Fishes in estuaries, Blackwells, Oxford, pp636. EUNIS. 2004. A5.7211 Beggiatoa spp. on anoxic sublittoral mud – annex of all EUNIS habitats - http://eunis.eea.europa.eu/upload/EUNIS_2004_list.pdf Fost-HM. 2010. HMS Scylla MBES Survey, February 2010. 7pp. Gray, J.S. & Elliott, M. 2009. Ecology of Marine Sediments. From Science to Management. 2nd Edition. Oxford University Press, Oxford, 225pp. Green, J. 1968. The biology of estuarine animals. Sidgwick & Jackson. London, 401pp. Hall-Spencer, J., White, N., Gillespie, E., Gillham, K., A Foggo, A. 2006. Impact of fish farms on maerl beds in strongly tidal areas Mar. Ecol. Prog. Ser. 326: 1–9. Hiscock, K. Sharrock, S., Highfield, J. & Snelling, D. 2010. Colonization of an artificial reef in south-west England—ex-HMS ‗Scylla‘. J. Mar. Biol. Assoc., UK. 90(1): 69-94. Langston W.J. Chesman.B.S. Burt G.R. Hawkins S.J. Readman J. Worsfold P. (2003) Site Characterisation of the South West European Marine Sites; Plymouth Sound and Estuaries cSAC, SPA. Marine Biological Association occasional publication, No. 9, 216pp. Lockwood-Saunders, E. 2003. The impact of dredging in the river Tamar on Mytilus edulis in the surrounding area. Unpublished BSc thesis, University of Plymouth. Longbottom, M.R., 1970. The distribution of Arenicola marina (L.) with particular reference to the effects of particle size and organic matter of the sediments. J. Exp. Mar. Biol. Ecol. 5: 138-157. Lowe, 2009. The Rame Head Study: The impact of offshore sediment dumping activity on the health of the mussel population in Whitsand Bay, Cornwall. Plymouth Marine Laboratory Report to the Crown Estate, 42pp. ISBN: 978-1-906410-07-0 MAFF. 1989. First Report of the Marine Pollution Monitoring Management Group's Co- ordinating Group on Monitoring of Sewage-Sludge Disposal Sites. Aquat. Environ. Monit. Rep., MAFF Direct. Fish. Res., Lowestoft, (20), 64 pp. McLusky, D.S. 1967. Some effects of salinity on the survival, moulting and growth of Corophium volutator (Amphipoda). J. Mar. Biol. Assoc. U.K. 47: 607-617. McLusky, D.S. 1968. Some effects of salinity on the distribution and abundance of Corophium volutator in the Ythan estuary. J. Mar. Biol. Assoc. U.K. 48: 443-454. McLusky, D. & Elliott, M. 2004. The Estuarine Ecosystem: ecology, threats and management. Third Edition. Oxford University Press, Oxford. 214pp. Page 84 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Meadows, P.S. 1964(a). Experiments on substrate selection by Corophium species: films and bacteria on sand particles. J. Exp. Biol. 41: 499-511 Mee, L.D., Jefferson, R.L., Laffoley, D..A., Elliott, M., 2008. How good is good? Human values and Europe‘s proposed Marine Strategy Directive. Mar. Pollut. Bull. 56, 187–204. MEMG, 2003. Group Co-ordinating Sea Disposal Monitoring. Final Report of the Dredging and Dredged Material Disposal Monitoring Task Team. Sci. Ser., Aquat. Environ. Monit. Rep., CEFAS, Lowestoft, (55): 52pp. Murray, I. 2002. Impact of dredged spoil on grain size distributions in Whitsand Bay, Cornwall. Unpublished BSc thesis, University of Plymouth, 157pp. Okada, T., Larcombe, P. & Mason, C. 2009. Estimating the spatial distribution of dredged material disposed of at sea using particle-size distributions and metal concentrations. Mar. Pollut. Bull. 58: 1164-1177. OSPAR Convention for the Protection of the Marine Environment of the North-East Atlantic. 1997. JAMP Guidelines for General Biological Effects Monitoring (OSPAR Agreement 1997- 7). www.ospar.org/documents/dbase/decrecs/agreements/97-07e.doc. Accessed 28.11.10. OSPAR, 2004. Revised OSPAR Guidelines for the Management of Dredged Material, (Reference number: 2004-08) http://www.dredging.org/documents/ceda/downloads/environ- ospar-revised-dredged-material-guidelines.pdf Accessed 23.02.11 OSPAR Commission. 2008. OSPAR Commission, 2008: Overview of Contracting Parties‘ National Action Levels for Dredged Material. Biodiversity series, 23pp. http://www.ospar.org/documents/dbase/publications/p00363_action%20level%20belgium.pd f. Accessed on 21.1.11. OSPAR Commission. 2009. Background Document on CEMP assessment criteria for the QSR 2010. OSPAR Monitoring and Assessment Series. http://qsr2010.ospar.org/media/assessments/p00390_supplements/p00461_Background_D oc_CEMP_Assessmt_Criteria_Haz_Subs.pdf. Accessed 21.1.11 OSPAR Commission. 2009a. JAMP Assessment of the Environmental Impact of Dumping of Wastes at sea. 32pp. Petersen, BJ, Howarth, R.W., Lipschultz, F. & Ashendorf, D. 1980 Saltmarsh detritus: an alternative interpretation of stable carbon isotope ratios and the fate of Spartina alterniflora. Oikos 34 173-177. Royal Haskoning. 2009. Cornwall and Isles of Scilly SMP2 Strategic Environmental Assessment: Scoping Report prepared by Royal Haskoning Ltd for Cornwall Council for CISCAG (Cornwall and Isles of Scilly Coastal Advisory Group), July 2009, Final Report 9T8801. Rugg, N. 2004. Tamar Estuaries Consultative Forum. Plymouth Sound and Estuaries Water Transportation Study. Scott Wilson and Atlantic Consultants, 65pp. Page 85 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Rützler, K., Goodbody, I., Diaz, M.C., Feller, I.C. & MacIntyre, I.G. 2004. The Aquatic Environment of Twin Cays, Belize. Atoll Research Bulletin, No. 512, Nat. Mus. Of Nat. Hist., Smithsonian Inst., Washington DC, US, Sept 2004. Selkirk, B. (2005a) The CEFAS report - some areas of serious concern, July 2005 8pp. Selkirk, B. (2005b) The CEFAS report - some areas of serious concern, Revised report. August 2005 4pp. Siddorn, J.R., Allen, J.I. & Uncles, R.J. 2003. Heat, salt and tracer transport in the Plymouth sound coastal region: a 3D modelling study. Snelling, D. 2006. The Scylla Monitoring Programme 2004–2006. National Marine Aquarium report to Defra, 99pp Snelling, D. 2010. The Scylla Monitoring Programme 2007–2009. National Marine Aquarium report to Defra, 36pp Stebbing A.R.D., Turk S.M.T., Wheeler A., & Clarke K.R. 2002. Immigration of southern fish species to south-west England linked to warming of the North Atlantic (1960–2001). Journal of the Marine Biological Association of the UK, 82, pp 177-180. Sullivan, N. 2000. The Use of Agitation Dredging, Water Injection Dredging and Sidecasting: Results of a Survey of Ports in England and Wales. Terra et Aqua – Number 78 – March 2000. TECF (2010). Tamar Estuaries Consultative Forum accessed via http://www.plymouth.gov.uk/homepage/environmentandplanning/natureconservation/naturep rojects/tecf.htm . Accessed on 12.12.10 Thorpe, A. 2009. Study into metal contamination in Whitsand Bay, SE Cornwall as a result of the disposal of dredged spoil. Unpublished BSc dissertation, School of earth, Ocean and Environmental Sciences, University of Plymouth. 85pp Vellinga, T. & Eisma, M. 2005. Management of contaminated dredged material in the Port Of Rotterdam. In: J Vermaat, W Salomons, L Bouwer & K Turner (Eds.), Managing European Coasts: past, present & future. Springer, Berlin, p315-322. Walmsley S.A. and Pawson, M.G (2007). The coastal fisheries of England and Wales, Part V: a review of their status 2005–6. Sci. Ser. Tech Rep., Cefas Lowestoft, 140: 83pp. Wells, R. 2001. An identification of the scale of potential impacts, as a result of military activities, on conservation in the coastal zone of the UK. Unpublished MSc Dissertation, University of Hull. World Sea Fishing Limited. 1998-2010. World Sea Fishing Forum. http://www.worldseafishing.com/forums/showthread.php?t=246841 and http://www.worldseafishing.com/marks/england/southwest/rame_head_cornwall.html Accessed 20.1.11. Page 86 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Yozzo, D.J., Wilber, P. & Will, R.J. (2004) Beneficial use of dredged material for habitat creation, enhancement, and restoration in New York–New Jersey Harbour. J. Env. Management, 73(1) 39-52. Zebe, E. & Schiedek, D. 1996. The lugworm Arenicola marina: a model of physiological adaptation to life in intertidal sediments. Helgoländer Meeresunters. 50: 37-68. Page 87 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO APPENDICES Appendix 1. Acknowledgements The cooperation and assistance of a large number of people, representing both the scientific community and the local community, is gratefully acknowledged. Specifically, Mr Dave Peake, Mr T Blagdon, Dr Bruce Selkirk and Professor Robin Pinigree are thanked for taking the time to collate and present a large volume of evidence. Cefas, the Environment Agency, Natural England, the Marine Biological Association (UK), Plymouth Marine Laboratory and the University of Plymouth are also thanked for their assistance. A full list of consultees is provided below. Name Affiliation Christine Angle Local resident Dr Peter Barham Peter Barham Environment Ltd Dr Andrew Birchenough Cefas Mr T Blagdon Local resident Pete Bluett Environment Agency Dr Stefan Bolam Cefas Ben Bunting Environment Agency Richard Cope Westminster Dredging Kaja Curry Tamar Estuaries Consultative Forum Sarah Dashfield Plymouth Marine Laboratory Natalie Dunwell Local resident Julie Elworthy Local resident Ms Galleymore Bird Local resident Stuart Gee Environment Agency Stephen Hall National Oceanography Centre, Southampton Dr Keith Hiscock Marine Biological Association, UK Dr Pete Jonas Environment Agency Robert Kidd Westminster Dredging David Knight K.S.A.R.S. Ltd Louisa Knights Natural England Dr Piers Larcombe Cefas Dr Annie Linley Plymouth Marine Laboratory Dr David Lowe Plymouth Marine Laboratory Claire Mason Cefas David Mitchell Angling Trust Janet Moss Local resident Andy Murray Local resident Professor Mark Osborn University of Hull Dave Peake Local resident Page 88 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Name Affiliation Dr Bruce Selkirk Local resident John Steven Hunter Stone Professor Robin Pinigree Marine Biological Association, UK Helen Richards Cornwall County Council Dr Jon Rees Cefas Major Douglas Riley Local resident Frankie Robinson Local resident Dr Lynda Rodwell and colleagues University of Plymouth Mike Smith Local resident Deborah Snelling National Marine Aquarium, Plymouth Richard Talbot Southern Diving Unit 1 in HMNB Devonport Anthony Thorpe Local resident Marigold Thorpe Local resident Dr Reg Uncles PML Dr Chris Vivian Cefas Karema Warr Cefas Dr Steve Widdicombe Plymouth Marine Laboratory Karen Williams Local resident Page 89 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Appendix 2. Research and monitoring studies at Rame Head and Whitsand Bay. Bolam, S.G., Mason, C., Bolam, T., Whomersley, P., Birchenough, S.N.R, Curtis, M., Vanstaen, K., Rumney, H., Barber, J., Law, R., Aldridge, J, Nye, V. & Griffith, A. 2009. Dredged material disposal site monitoring across England and Wales: summary of 2008-09 sampling under SLAB5. Cefas contract report SLAB5, 120pp. BridgeZone Ltd. 2010. Survey Report. The condition of the Scylla Reef lying in Whitsand Bay. Report to the National Marine Aquarium, Plymouth, 21pp. Burkill, S.D. 2006. A study of offshore disposal of dredged materials and associated impacts: Whitsand Bay. Unpublished BSc. thesis, University of Plymouth. 76pp. Cameron, R. 2009. A review of the Scylla Monitoring Programme: Is sediment from the Rame Head Disposal Site being deposited around the Scylla. Unpublished BSc. thesis, University of Plymouth, 46pp. Cefas. 2005. Environmental impacts resulting from disposal of dredged material at the Rame Head disposal site, S.W. England: An analysis of existing data and implications for environmental management. Cefas, June 2005, 120 pp. (http://www.cefas.co.uk/media/29994/20050602_rame_head_report.pdf) Cefas. 2007a. Rame Head: Furthering our understanding of the Ecological Consequences of Dredged Material Disposal Activities. Report ME1116 to Defra, 19pp. Cefas. 2010. Disposal of dredged material at the Rame Head Disposal Site: A review of Cefas‘ Role in its Monitoring and a Summary of the Monitoring Evidence. Report to the Marine Management Organisation, 28pp. Fost-HM. 2010. HMS Scylla MBES Survey, February 2010. 7pp. Hiscock, K. Sharrock, S., Highfield, J. & Snelling, D. 2010. Colonization of an artificial reef in south-west England—ex-HMS ‗Scylla‘. J. Mar. Biol. Assoc., UK. 90(1): 69-94. Lockwood-Saunders, E. 2003. The impact of dredging in the river Tamar on Mytilus edulis in the surrounding area. Unpublished BSc thesis, University of Plymouth. Lowe, 2009. The Rame Head Study: The impact of offshore sediment dumping activity on the health of the mussel population in Whitsand Bay, Cornwall. Plymouth Marine Laboratory Report to the Crown Estate, 42pp. ISBN: 978-1-906410-07-0 Murray, I. 2002. Impact of dredged spoil on grain size distributions in Whitsand Bay, Cornwall. Unpublished BSc thesis, University of Plymouth, 157pp. Okada, T., Larcombe, P. & Mason, C. 2009. Estimating the spatial distribution of dredged material disposed of at sea using particle-size distributions and metal concentrations. Mar. Pollut. Bull. 58: 1164-1177. Page 90 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Royal Haskoning. 2009. Cornwall and Isles of Scilly SMP2 Strategic Environmental Assessment: Scoping Report prepared by Royal Haskoning Ltd for Cornwall Council for CISCAG (Cornwall and Isles of Scilly Coastal Advisory Group), July 2009, Final Report 9T8801. Rugg, N. 2004. Tamar Estuaries Consultative Forum. Plymouth Sound and Estuaries Water Transportation Study. Scott Wilson and Atlantic Consultants, 65pp. Siddorn, J.R., Allen, J.I. & Uncles, R.J. 2003. Heat, salt and tracer transport in the Plymouth sound coastal region: a 3D modelling study. Snelling, D. 2006. The Scylla Monitoring Programme 2004–2006. National Marine Aquarium report to Defra, 99pp Snelling, D. 2010. The Scylla Monitoring Programme 2007–2009. National Marine Aquarium report to Defra, 36pp TECF (2010). Tamar Estuaries Consultative Forum accessed via http://www.plymouth.gov.uk/homepage/environmentandplanning/natureconservation/naturep rojects/tecf.htm . Accessed on 12.12.10 Thorpe, A. 2009. Study into metal contamination in Whitsand Bay, SE Cornwall as a result of the disposal of dredged spoil. Unpublished BSc dissertation, School of earth, Ocean and Environmental Sciences, University of Plymouth. 85pp World Sea Fishing Limited. 1998-2010. World Sea Fishing Forum. Page 91 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Appendix 3. Metal concentrations A3.1 ARSENIC Plots are given for each year. JB denotes sites within Jennycliffe Bay (Plymouth Sound). All other sites are within Whitsand Bay Page 92 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Page 93 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO A3.2 CADMIUM Page 94 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Page 95 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO A3.3 CHROMIUM Page 96 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Page 97 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO A3.4 COPPER Page 98 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Page 99 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO A3.5. MERCURY Page 100 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Page 101 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO A3.6. LEAD Page 102 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Page 103 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO A3.6. ZINC Page 104 Institute of Estuarine and Coastal Studies Rame Head Environmental Impact Study: review of evidence. MMO Page 105 Institute of Estuarine and Coastal Studies