Department of the Environment, Community and Local Government Arklow Harbour: Foreshore licence application Supporting report for the Foreshore licence application for the dredging of Arklow Harbour Issue | 8 February 2013 This report takes into account the particular instructions and requirements of our client. It is not intended for and should not be relied upon by any third party and no responsibility is undertaken to any third party. Job number 224515.00 Ove Arup & Partners Ireland Arup 50 Ringsend Road Dublin 4 Ireland www.arup.com Department of the Environment, Community and Local Government Arklow Harbour: Foreshore licence application Supporting report for the Foreshore licence application for the dredging of Arklow Harbour Contents Page 1 Introduction 1 2 Background information 1 2.1 History of the project 1 2.2 Surveys 2 3 Proposed scheme & assessment methodology 2 3.1 Proposed scheme 2 3.2 Application Methodology 5 4 Surveys 8 4.1 Sediment granulometry & chemistry 8 4.2 Sediment transport 24 4.3 Radiological assessment 24 4.4 Archaeological 24 5 Proposed methodology for dredging 56 5.1 Introduction 56 5.2 Dredging operation 57 5.3 Impact assessment 58 5.4 Mitigation measures 63 5.5 Monitoring 66 5.6 Residual impacts 67 5.7 Previous dredge spoil disposal 68 6 Consultees 68 6.1 Sea Fisheries Protection unit 68 6.2 Department of Agriculture 69 6.3 Marine Institute 69 6.4 Additional consultees 69 7 Conclusions 69 | Issue | 8 February 2013 | Arup J:\224000\224515-00\4. INTERNAL PROJECT DATA\4-03 DESIGN\4-03-03 INFRASTRUCTURE\01 FORESHORE LICENCE\UPDATED REPORT 08.02.13\APPLICATION TO BE SENT\ACCOMPANYING REPORT\ACCOMPANYING REPORT FORESHORE LICENCE APPLICATION_REVSL_08.02.13FINALISSUE.DOCX Department of the Environment, Community and Local Government Arklow Harbour: Foreshore licence application Supporting report for the Foreshore licence application for the dredging of Arklow Harbour 1 Introduction The EPA (Environmental Protection Agency) have granted a DaS Permit (Dumping at Sea Permit) for the disposal of the contaminated material obtained from the dredging of Arklow Harbour. This material will be disposed by dumping at sea in a purposely dredged pit to contain the contaminated sediments. The pit will be covered with a 3.1m thick capping layer and an erodible layer of 1.4 m Arup has been commissioned to prepare this foreshore licence application required for the dredging works in the harbour to be submitted to the Department of Environment, Community and Local Government (DECLG). This report, accompanying the foreshore licence application will examine how the dredging works will be completed and also any potential impacts from dredging in Arklow Harbour may have. 2 Background information 2.1 History of the project The Avoca River continues to deposit river borne suspended sediment loading in the Avoca Estuary downstream of Arklow Bridge which constitutes the area utilised as the Port. This is due to the local hydrodynamic regime which allows the river to slow east of the Bridge. The lowering of river velocity allows the suspended sediment load to deposit at the mouth of the estuary which is the location of the port berths and facilities, the marina and the dock. It is necessary for the maintenance dredging to take place to ensure the viability of Arklow as one of Ireland’s east coast ports (recognised in the Regional Planning Guidelines for the Greater Dublin and Mid-East Areas), to ensure that local yachting can maintain access to the marina and in situ pontoons and berths which forms a key aspect of the tourism industry and a social amenity for Arklow. Dredging is also essential in order to ensure that the Irish Coast Guard Lifeboat Station can launch their lifeboat at low water which they are currently having difficulty with due to the continued deposition of sediments in the dock area. 2007: A previous application for dredging in Arklow Harbour by the Arklow Harbour Commissioners was submitted in 2007. This application was turned down by the Coastal Management Division due to insufficient data. 2009: Arup were commissioned by Arklow Harbour Commissioners in the year 2009 to prepare and manage an updated application for a Dredge Spoil Disposal Licence for Arklow Port. It was identified by the Coastal Management Division during the first application process (2007) that contamination in the Avoca Estuary at Arklow Port was significant enough to warrant further investigation. Legislative requirements for the disposal of dredge spoil included the undertaking of a full contamination assessment of the sediment and identifying ecological and archaeological constraints. The dredge site and the site where potentially contaminated spoil will be deposited for disposal were both the subject of a | Issue | 8 February 2013 | Arup Page 1 J:\224000\224515-00\4. INTERNAL PROJECT DATA\4-03 DESIGN\4-03-03 INFRASTRUCTURE\01 FORESHORE LICENCE\UPDATED REPORT 08.02.13\APPLICATION TO BE SENT\ACCOMPANYING REPORT\ACCOMPANYING REPORT FORESHORE LICENCE APPLICATION_REVSL_08.02.13FINALISSUE.DOCX Department of the Environment, Community and Local Government Arklow Harbour: Foreshore licence application Supporting report for the Foreshore licence application for the dredging of Arklow Harbour detailed investigation. Based on the investigations carried out a Dumping at sea licence was awarded by the EPA: DaS Licence (EPA Licence No. S0002-01) 2010: Arup were commissioned by Wicklow County Council to prepare and manage an application for maintenance dredging at Arklow Harbour. This document outlines the range of environmental investigations that were undertaken, the proposed mitigation and monitoring for the duration of the proposed scheme as well as an Impact Hypothesis. 2.2 Surveys In situ investigative work was completed by Arup’s specialist sub-consultants; Moore Group Ltd. Moore Group is a fully accredited professional geotechnical company with whom Arup has a successful working relationship which also includes previous investigative work at Arklow. As part of Arup’s environmental role in the Arklow Flood Relief Scheme, a full contamination assessment of the Avoca River in the vicinity of Arklow and the upper catchment was required. Arup utilised Moore Group Ltd. for the in situ sampling tasks. Moore Group conducted the following investigations for Arklow Port Dredge Disposal Licence Application at the end of 2008 and early 2009; • Sediment Dive Sampling, dredge and dump area; • Archaeological Study, dredge and dump area • Ecological Survey for the dump area; • Bathymetric and Hydrodynamic Survey for the dump area (Oceanography Chapter). A new bathymetric survey of the harbour was carried out on June 10th 2011 In order to undertake the foreshore licence required for the dredging works in the harbour, this report outlines the reports and surveys carried out related to the dredge area of Arklow Harbour. 3 Proposed scheme & assessment methodology 3.1 Proposed scheme The purpose of the dredging scheme is to maintain the depth of the Avoca Estuary (essentially a tidal channelised river) and adjacent dock at low water for the continued use of Arklow Port. Consequently this dredging scheme has been classified by Arklow Harbour Commissioners as Maintenance Dredging. The average depth of material to be dredged is approx. 1.3 m in the turning basin, 0.3 m in the river and 1,4 m in the dock. The area within Arklow Harbour and Dock to be dredged along with the current depths is indicated in Appendix A_003a (Appendices Application form). Maintenance dredging previously | Issue | 8 February 2013 | Arup Page 2 J:\224000\224515-00\4. INTERNAL PROJECT DATA\4-03 DESIGN\4-03-03 INFRASTRUCTURE\01 FORESHORE LICENCE\UPDATED REPORT 08.02.13\APPLICATION TO BE SENT\ACCOMPANYING REPORT\ACCOMPANYING REPORT FORESHORE LICENCE APPLICATION_REVSL_08.02.13FINALISSUE.DOCX Department of the Environment, Community and Local Government Arklow Harbour: Foreshore licence application Supporting report for the Foreshore licence application for the dredging of Arklow Harbour undertaken within Arklow Harbour (most recently in 1996) utilised disposal of dredge spoil at sea at a previously used spoil disposal site. At Arklow this was considered to be the most suitable option for disposal of dredge spoil material at that time. Following guidance from the EPA Inspector report, almost all of the dredged material has been reclassified material as contaminated. Figure 1 Previous classification of the material. The contaminated spoil material disposal site was recommended by the Coastal Management Division to be a “dig, dump and cover” site where the sea bed is excavated, contaminated spoil deposited and the removed sea bed material placed back over the contaminated material as a cap. 3.1.1 Dredge Site The area of Arklow Harbour to be dredged in the proposed scheme is illustrated in Appendix A_003a (Appendices Application form). The following coordinates apply to the area for proposed dredging; | Issue | 8 February 2013 | Arup Page 3 J:\224000\224515-00\4. INTERNAL PROJECT DATA\4-03 DESIGN\4-03-03 INFRASTRUCTURE\01 FORESHORE LICENCE\UPDATED REPORT 08.02.13\APPLICATION TO BE SENT\ACCOMPANYING REPORT\ACCOMPANYING REPORT FORESHORE LICENCE APPLICATION_REVSL_08.02.13FINALISSUE.DOCX Department of the Environment, Community and Local Government Arklow Harbour: Foreshore licence application Supporting report for the Foreshore licence application for the dredging of Arklow Harbour Irish Grid Co-ordinates ETRF89 GPS Co-ordinates Latitude Longitude Point no. Easting Northing degrees minutes seconds