DUBLIN PORT COMPANY Maintenance Dredging Programme 2022 – 2029 Application for Foreshore Licence Water Quality Risk Assessment IBE1618 D01 8 February 2021 rpsgroup.com WATER QUALITY RISK ASSESSMENT Document status Version Purpose of document Authored by Reviewed by Approved by Review date D01 Water Quality Risk Assessment 08/02/2021 Approval for issue 8 February 2021 Prepared by: Prepared for: RPS Dublin Port Company Associate - Water Environment and Flood Risk Port Engineer Management Elmwood House Port Centre 74 Boucher Road, Belfast Alexandra Road, Dublin 1 Co. Antrim BT12 6RZ Co. Dublin T +44 2890 667 914 T +353 1 8876000 E E Dublin Port Maintenance Dredging Programme 2022-2029 | Water Quality Risk Assessment | 8 February 2021 Page 1 rpsgroup.com WATER QUALITY RISK ASSESSMENT Contents 1 INTRODUCTION ......................................................................................................................................5 1.1 Dredging Operations ......................................................................................................................5 1.2 Consent Requirements ..................................................................................................................6 2 WATER QUALITY RISK ASSESSMENT ................................................................................................6 2.1 Assessment Methodology ..............................................................................................................6 2.2 Receiving Water Environment........................................................................................................8 2.2.1 Study Area Water Bodies .................................................................................................9 2.2.2 Water Framework Directive ............................................................................................10 2.2.3 Protected Areas ..............................................................................................................14 2.2.4 Marine Strategy Framework Directive Environmental Status .........................................18 2.2.5 EPA Water Quality in 2017: An indicators Report .........................................................19 2.2.6 ABR Project - Capital Dredging Water Quality Monitoring .............................................21 2.2.7 Maintenance Dredging 2020/2021 - Water Quality Monitoring ......................................51 2.2.8 Earth Observation Data ..................................................................................................67 2.2.9 Water Quality Summary ..................................................................................................72 2.3 Likelihood of Impacts ...................................................................................................................74 2.3.1 Potential Impacts ............................................................................................................74 2.4 Description of Likely Significant Impacts ......................................................................................75 2.4.1 Maintenance Dredging & Disposal Operations ...............................................................75 3 MITIGATION MEASURES .....................................................................................................................75 3.1 Suspended Sediment and Sedimentation ....................................................................................75 3.1.1 Dredging and Disposal ...................................................................................................75 4 RESIDUAL IMPACTS ............................................................................................................................76 5 POTENTIAL CUMULATIVE IMPACTS .................................................................................................77 5.1 Dublin Port Company ABR Project ..............................................................................................77 5.2 Dublin Port Company MP2 Project ..............................................................................................77 5.3 Dublin Port Company – Dublin Harbour Capital Dredging Project ..............................................79 6 CONCLUSIONS .....................................................................................................................................79 Tables Table 2-1 Criteria for Rating Receptor Sensitivity (NRA, 2008) .........................................................................7 Table 2-2 Criteria for Rating the Magnitude of Impact (NRA, 2008) ..................................................................7 Table 2-3 Criteria for Rating the Significance of Environmental Impacts (NRA 2008) .......................................8 Table 2-4 Defining Impact Significance (NRA, 2008) .........................................................................................8 Table 2-5 WFD Status (2009-2018) .................................................................................................................12 Table 2-6 WFD Status Breakdown (2013-2018) ..............................................................................................13 Table 2-7: Annual Assessment Criteria for Bathing Waters .............................................................................16 Table 2-8 2019-2020 Windstorm Events Impacting Ireland (Met Eireann) .....................................................24 Table 2-9 Summary statistics for dissolved oxygen (DO), Salinity, Temperature and Turbidity at ABR Project River Sonde Monitoring Stations between September 2019 and September 2020 ........25 Table 2-10 Details of 2019/2020 Dredging Activities .......................................................................................31 Table 2-11 Summary statistics for dissolved oxygen (DO), salinity (Sal), temperature (Temp) and turbidity (Turb) at monitoring stations ..........................................................................................37 Table 2-12 Mean Turbidity for Dredge and No-Dredge Intervals. Figures in brackets are the numbers of data observations in each case. ..................................................................................................38 Table 2-13 Mean Turbidity (NTU) at each depth for Buoys 1 to 4. Numbers in brackets are the number of data observations .....................................................................................................................44 Table 2-14 Mean turbidity at Buoys 1 to 4 during winter and summer seasons and during dredging and no dredging intervals. Figures in brackets are the number of data observations ........................45 Dublin Port Maintenance Dredging Programme 2022-2029 | Water Quality Risk Assessment | 8 February 2021 Page 2 rpsgroup.com WATER QUALITY RISK ASSESSMENT Table 2-15 Summary statistics for Turbidity (NTU) measured at 4 sites within the inner Liffey channel (December 2017 - October 2020) ................................................................................................52 Table 2-16 Summary statistics for Dissolved Oxygen (mg/l) measured at 4 sites within the Inner Liffey channel (December 2017 - October 2020) ..................................................................................53 Table 2-17 Summary statistics for Turbidity (NTU) measured at 4 sites within Dublin Bay (September 2017 - October 2020) ...................................................................................................................61 Table 2-18 Summary statistics for Turbidity (NTU) measured at 4 sites within Dublin Bay (September 2020) ............................................................................................................................................63 Figures Figure 2-1 Site Location in the Context of the Wider Surface Water Environment ..........................................10 Figure 2-2 Elements of the Water Framework Directive Status .......................................................................11 Figure 2-3 Water Framework Directive water body status ...............................................................................14 Figure 2-4: Nutrient Sensitive Areas .................................................................................................................15 Figure 2-5: Bathing Water Quality in the Dublin Area 2019 (EPA, 2020) .........................................................17 Figure 2-6: Natura 2000 Designated Sites .......................................................................................................18 Figure 2-7 Water quality monitoring stations in the Dublin Port area ..............................................................21 Figure 2-8 Relationship established between Turbidity and Total Suspended Solids (inner Liffey channel) ........................................................................................................................................22 Figure 2-9 Fouling of East Link sonde after 3 weeks deployment in August 2019 .........................................23 Figure 2-10 East Link Bridge Monitoring Station - Water Quality Data (12 Hour Median) ...............................26 Figure 2-11 Poolbeg Monitoring Station - Water Quality Data (12 Hour Median) ............................................27 Figure 2-12 North Bank Monitoring Station - Water Quality Data (12 Hour Median) .......................................28 Figure