Appendix 3 – Marine Archaeology Assessment Report. IRIS Cable System 57 March 2021 Job No. 1334 Marine Archaeological Assessment Of the Preferred Route of the Proposed IRIS Cable System Client: McMahon Design and Management Author: Checked By: Job No. G21004 Fore Shorelicence No. 07016 Licence No. 20D0029, 20R0106 and 20E0287 Date: 03/03/2021 Geomara, The Portershed, Eyre Square, Galway H91 HY51 Tel: + 353 87 6485228, Email:[email protected], Web: www.geo-mara.com Marine Archaeological Assessment – Preferred Route IRIS Contents Non technical Summary..................................................................................................................... 6 1 Introduction .............................................................................................................................. 8 2 Project Details ........................................................................................................................... 8 2.1 Planning Background .......................................................................................................... 8 2.2 Location ........................................................................................................................... 10 2.3 Landfall at Ballyloughane ................................................................................................. 11 2.4 Route Position List............................................................................................................ 12 2.5 Legislative Framework ...................................................................................................... 14 3 Assessment Methodology ........................................................................................................ 14 3.1 Desk Based Assessment ................................................................................................... 15 3.2 Screening of Geotechnical Locations ................................................................................ 16 3.3 Geophysical Survey Review and Monitoring ..................................................................... 16 3.4 Geotechnical Review ........................................................................................................ 16 3.5 Impact Assessment .......................................................................................................... 16 3.6 Mitigation measures ........................................................................................................ 16 4 Existing Environment ............................................................................................................... 17 4.1 Introduction ..................................................................................................................... 17 4.2 Planning Context in relation to Archaeology and Cultural Heritage ................................... 17 4.2.1 Archaeological Heritage ............................................................................................ 18 4.2.2 Architectural Heritage .............................................................................................. 18 4.2.3 Record of Protected Structures ................................................................................. 19 4.2.4 Architectural Conservation Areas ............................................................................. 20 4.2.5 Vernacular Heritage.................................................................................................. 20 4.2.6 The Coast ................................................................................................................. 21 4.2.7 Views of Special Amenity Value and Interest ............................................................ 21 4.3 Geological Baseline .......................................................................................................... 22 4.4 Bathymetry and Seabed Typology .................................................................................... 22 4.5 Galway City ...................................................................................................................... 23 4.6 Galway City Council Storm Damage Mitigation Report ..................................................... 26 5 Cultural Heritage Along the Proposed Route ............................................................................ 27 5.1 Onshore Cultural Heritage Assets Listed by the DHLG and the National Museum of Ireland 27 Geomara, The Portershed, Eyre Square, Galway H91 HY51 Tel: + 353 87 6485228, Email:[email protected], Web: www.geo-mara.com Marine Archaeological Assessment – Preferred Route IRIS 5.2 Storm Damage Mitigation report Sites and Finds .............................................................. 28 5.3 Recorded shipwreck sites ................................................................................................. 29 5.4 Unrecorded Sites.............................................................................................................. 32 5.5 Areas of Archaeological Potential ..................................................................................... 32 5.6 Archaeological excavations ........................................................................................... 32 5.7 Topographical Files ....................................................................................................... 32 6 Bathymetry and Geophysical Surveys....................................................................................... 33 6.1 Survey from -1.5m WD to 15m WD .................................................................................. 33 6.2 Survey from 15m WD to 12nm Limit................................................................................. 35 6.3 Survey Dates .................................................................................................................... 36 6.4 Survey Blocks ................................................................................................................... 36 6.5 Vessels and Equipment .................................................................................................... 36 6.6 Geotechnical Investigations.............................................................................................. 38 7 Survey and Geotechnical Results.............................................................................................. 39 7.1 Nearshore survey 15m WD to -1.5m WD .......................................................................... 40 7.2 Shallow Water Survey – 15m WD to 12nm Limit ............................................................... 45 7.3 Archaeological Screening in Advance of Geotechnical Works ........................................... 46 7.4 Intertidal Survey ............................................................................................................... 47 8 Proposed Cable Development Details ...................................................................................... 49 8.1 The Landfall at Ballyloughane ........................................................................................... 49 8.2 Cable Installation on the Beach ........................................................................................ 50 8.2.1 Horizontal Directional Drill........................................................................................ 50 8.2.2 Beach manhole ......................................................................................................... 51 8.3 Inshore Cable Installation ................................................................................................. 51 8.4 Offshore Cable Installation ............................................................................................... 52 8.4.1 Prelay Grapnel Run ................................................................................................... 52 8.4.2 Cable Installation on the Continental shelf................................................................ 52 8.4.3 ROV Operations ........................................................................................................ 53 9 Impact Assessment .................................................................................................................. 53 9.1 Impacts on Maritime Cultural Heritage ............................................................................. 54 9.2 Direct Impacts .................................................................................................................. 54 9.3 Indirect Impacts ............................................................................................................... 55 9.4 Secondary Impacts ........................................................................................................... 55 Geomara, The Portershed, Eyre Square, Galway H91 HY51 Tel: + 353 87 6485228, Email:[email protected], Web: www.geo-mara.com Marine Archaeological Assessment – Preferred Route IRIS 9.5 Cumulative Impacts .......................................................................................................... 55 10 Mitigation ............................................................................................................................ 55 Appendix 1 Shipwreck Inventory ................................................................................................. 57 Appendix 2 Topographic Files.....................................................................................................