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Suir CFRAM Study Draft Final Report UoM16

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DOCUMENT CONTROL SHEET

Client Office of Public Works

Project Title Suir CFRAM Study

Document Title Final Project Report UoM16

Document No. 1891_REP_170906_Final Project Report Draft

This Document Comprises

DCS TOC Text List of Tables List of Figures No. of Appendices

1 1 57 1 1 1

Rev. Status Author(s) Reviewed By

Approved By Office of Origin Issue Date

D01 Draft

Annmarie Jordan, Juan Carlos Johnson, Annemarie Fitzgerald, Steve Jones.

Gerry Gallagher J Martin Trim, Co. Meath 08/12/2017

Suir CFRAM Study

UoM16 Final Project Report


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F01 Final

Annmarie Jordan, Juan Carlos Johnson, Annemarie Fitzgerald, Steve Jones.

Gerry Gallagher J Martin

Trim, Co Meath 14/02/2018


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Copyright

Copyright – Office of Public Works. All rights reserved. No part of this report may be copied or reproduced by any means without prior permission from the Office of Public Works.

Suir CFRAM Study Report Final Project Report UoM16

1891_TECH_170111_Final Project Report 1

Table of Contents

1 INTRODUCTION ............................................................................................................ 5

1.1 Overview to Unit of Measurement 16 ...................................................................... 5

1.2 OBJECTIVE OF THIS REPORT.............................................................................. 7

1.3 ACCOMPANYING AND SUPPORTING REPORTS ................................................ 7

2 OVERVIEW OF PROJECT DELIVERABLES ................................................................. 8

2.1 Brief History of UoM16 ............................................................................................ 8

2.1.1 Sustainable Urban Drainage System (SuDs) .................................................... 8

2.1.2 Planning & Development .................................................................................. 8

2.2 SUMMARY of UoM16 HYDROLOGY REPORT ...................................................... 9

2.2.1 Key Outputs ..................................................................................................... 9

2.2.2 Key Findings ...................................................................................................10

2.3 SUMMARY of UoM16 HYDRAULICS REPORT .....................................................11

2.3.1 Key Outputs ....................................................................................................12

2.3.2 Key Finding .....................................................................................................13

2.4 SUMMARY of UoM16 PRELIMINARY OPTIONS REPORT ...................................14

2.4.1 Key Outputs ....................................................................................................15

2.4.2 Key Findings ...................................................................................................15

2.5 SUMMARY OF UoM16 DRAFT FLOOD RISK MANAGEMENT PLAN ...................16

2.5.1 Key Findings ...................................................................................................17

2.6 Summary of the Strategic Environmental Assessment (SEA) and Natura Impact Statement (NIS) ................................................................................................................18

2.6.1 Strategic Environmental Assessment ..............................................................18

2.6.2 Habitats Directive Assessment (Natura Impact Statement) .............................18

2.7 Directory of Deliverables (with Final Plan) ..............................................................20

2.8 Supplementary Deliverables ...................................................................................20

3 APPLICATION OF DATA ..............................................................................................23

3.1 1960’s Survey Data ................................................................................................23

3.1.1 Conversion Process ........................................................................................23

3.1.2 Cross Section Naming .....................................................................................23

3.2 2007 & 2010 Survey Data ......................................................................................23

3.2.1 Survey Photographs ........................................................................................23

3.3 LIDAR Data and Ortho-Photographs Data ..............................................................24

3.4 Economic Data .......................................................................................................24

3.4.1 Damages .........................................................................................................24

3.4.2 Cost Methodology ...........................................................................................24



3.5 Environmental Data ................................................................................................28

4 ANALYSIS AND LIMITATIONS .....................................................................................29

4.1 Hydrology Approach and Uncertainties ..................................................................29

4.1.1 Recommendations ..........................................................................................29

4.2 Hydraulic Modelling Approach and Uncertainties ...................................................30

4.2.1 Survey Data ....................................................................................................30

4.2.2 Model uncertainty with 1D models ...................................................................31

4.2.3 Medium Priority Watercourse (MPW) modelling ..............................................33

4.2.4 Missing structures in Models ...........................................................................34

4.2.5 Blockage scenarios .........................................................................................34

4.2.6 Insufficient Hydraulic Data ...............................................................................34

4.2.7 Clonmel Hydraulic Model ................................................................................35

4.3 Preliminary Options & Plan Report Recommendations ...........................................37

4.3.1 Relevant information for AFAs with low flood risk ............................................37

4.3.2 Other Areas outside the CFRAM AFA’s ..........................................................37

4.3.3 Additional AFAs Identified during SE CFRAM Flood Risk Review ...................37

4.3.4 MCA Process ..................................................................................................37

4.3.5 Natural Flood Management Measures ............................................................38

4.3.6 Unit Cost Database .........................................................................................38

4.4 Strategic Environmental Report Recommendations ...............................................38

5 HEALTH AND SAFETY .................................................................................................40

5.1 Project Supervisor Design Process ........................................................................40

5.2 Health and Safety – Channel Surveys ....................................................................40

5.3 Health and Safety – Defence Asset Survey ............................................................40

5.4 Health and Safety – Site Visits ...............................................................................40

5.5 Health and Safety Considerations in Option Selection ............................................40

5.6 Health and Safety Consideration of AFA Preferred Option .....................................42

5.6.1 Ardfinnan .........................................................................................................42

5.6.2 Borrisoleigh .....................................................................................................42

5.6.3 Cahir ...............................................................................................................43

5.6.4 Fethard ...........................................................................................................43

5.6.5 Golden ............................................................................................................43

5.6.6 Holycross ........................................................................................................43

5.6.7 Knocklofty .......................................................................................................44

5.6.8 Newcastle .......................................................................................................44

5.6.9 Piltown ............................................................................................................44

5.6.10 Thurles ............................................................................................................44



6 CONSULTATION ..........................................................................................................45

6.1 Summary of Public, Stakeholders and Statutory Consultation Engagement ...........45

6.1.1 Consultation on the Mapping ...........................................................................45

6.1.2 Consultation on the Options ............................................................................45

6.1.3 PCDs on the draft Plan ....................................................................................46

6.1.4 Statutory Consultation on the draft Plan ..........................................................46

6.1.5 Stakeholder Feedback ....................................................................................47

7 OUTCOMES AND NEXT STEPS ..................................................................................48

7.1 Summary of measures by UoM/AFA ......................................................................48

7.2 Next Cycle of the CFRAM ......................................................................................48

7.2.1 Flood Risk Management in Other Areas ..........................................................48

7.2.2 Natural Flood Risk Management Measures .....................................................48

7.2.3 Technical Methodology ...................................................................................49

7.2.4 Communication ...............................................................................................50

8 CONCLUSIONS ............................................................................................................51

9 REFERENCES & BIBLIOGRAPHY ...............................................................................52

List of Figures Figure 1.1 UoM16 Location Map ........................................................................................... 6

Figure 2.1 Map showing the modelled watercourses and AFAs within UoM16 .....................12

Figure 3.1 Cost Estimation Within the Wider Appraisal Process ...........................................25

Figure 3.2 Whole Life Cost Estimation ..................................................................................26

Figure 3.3 CFRAM Approach to Cost Estimation ..................................................................27

Figure 4.1 Flood depth just upstream of Golden, red circle highlights small flood depth indicating very shallow areas in the river. .............................................................................31

Figure 4.2 Flood extent of Cahir tributary river. Red circle indicates possible overestimation of flood extent .......................................................................................................................32

Figure 4.3 Observed versus modelled stages based on estimated return periods at Thurles gauging station (based on records from 1954-2015) ............................................................33

Figure 4.4 Flood extent at the junction of Anner River and Clashawley River, red circle indicated error in flood extent (missing cross-sectional data) ................................................34

List of Tables Table 4-1 Quality of hydraulic data .......................................................................................35

Table 5-1 Calculation of Health and Safety in the MCA process (Guidance Note No.28)......41



Abbreviations

AEP Annual Exceedance Probability AFA Area for Further Assessment BCR Benefit Cost Ratio CFRAM Catchment Flood Risk Assessment and Management DEHLG Department of Environment, Community and Local Government (previously

known as the Department of Environment, Heritage and Local Government) FCERM Flood or Coastal Erosion Risk Management FHRC Flood Hazard and Research Centre FRA Flood Risk Assessment FRM Flood Risk Management FRMP Flood Risk Management Plan FSU Flood Studies Update HA Hydrometric Area HEFS High-end future scenario HEP Hydrometric Estimation Point HPW High Priority Watercourse IPP Individual Property Protection IRR Individual Risk Receptor MCA Multi Criteria Analysis MCM Multi Coloured Manual MPW Medium Priority Watercourse MRFS Mid-range future scenario NHA Natural Heritage Area PCD Public Consultation Day OPW Office of Public Works PFRA Preliminary Flood Risk Assessment RBD River Basin District RMP Record of Monuments and Places SAC Special Area of Conservation SMR Sites and Monuments Record SI Statutory Instrument SoP Standard of Protection SPA Special Protection Area SSA Spatial Scale of Assessment SUDS Sustainable Urban Drainage System UoM Unit of Management


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1 INTRODUCTION

1.1 Overview to Unit of Measurement 16

The South Eastern Study area covers approximately 12,857 km2 and includes seven Units of Management ('UoM') each comprised of a single Hydrometric Area ('HA'). They are UoM11 (Owenavorragh), UoM12 (Slaney and Wexford Harbour), UoM13 (Ballyteigue‐Bannow), UoM14 (Barrow), UoM15 (Nore), UoM17 (Colligan‐Mahon) and UoM16 (Suir). UoM16 (Suir) is covered by the Suir pilot Catchment Flood Risk Assessment and Management (CFRAM) Study and covers an area of approximately 3,565 km2, the remaining six UoMs are covered under the South Eastern CFRAMS.

The principal river within UoM16 is the River Suir. The River Suir rises in the Devil’s Bit Mountains, near Moneygall (north of Templemore), and flows in a southerly direction until meeting the Knockmealdown mountain range where the river changes its course northwards. At Knocklofty, the River turns east passing north of the Comeragh Mountains and continues on through Waterford City until it enters the sea at Waterford Harbour having joined with the River Barrow and the River Nore. The river is tidal to Old Bridge in Carrick-on Suir. At 175km, the Suir is the second longest river in Ireland. It is considered a wide river with bank-to-bank widths ranging from 25-35m in its middle sections. The Suir has a number of significant tributaries such as the Drish, Upper Clodiagh (Thurles), Multeen, Aherlow / Ara, Tar / Duag, Nier, Anner / Clashawley, Lingaun, Clodiagh (Portlaw) and Blackwater / Pollanassa.

There are no Arterial Drainage Schemes within UoM16. There are Urban Flood Relief Schemes in the Waterford City, Carrick-on-Suir and Clonmel with a scheme due to commence shortly in Templemore. There are four Drainage Districts located within UoM16, none are on watercourses where fluvial and coastal flood risk is being investigated. Figure 1.1 shows the South East CFRAM study map with large towns and UoM 16 highlighted.


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Figure 1.1 UoM16 Location Map

Note:- Figure 1.1 Shows North and South Tipperary County Councils that are now one local authority – might be better to counties and label accordingly.


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1.2 OBJECTIVE OF THIS REPORT The principal objective of this final report, in accordance with Section 12.2 of the CFRAM Studies Stage 1 Project Brief, is to provide a summary of the relevant reports prepared for UoM16 as part of the Suir CFRAM study, and detail the development of the UoM16 Flood Risk Management Plan (FRMP, hereafter referred to as the Plan) which was consulted on in 2016 and finalised in 2017.

This report also aims to identify any issues that may influence the proposed methodologies or programme going forward into the second cycle of the Floods Directive implementation.

1.3 ACCOMPANYING AND SUPPORTING REPORTS This report accompanies the UoM16 Flood Risk Management Plan, which is composed of the following volumes:

� VOLUME I - Draft Flood Risk Management Plan

� VOLUME II -SEA Environmental Report and Natura Impact Statement

This final report is also supported by a suite of project deliverables, including key technical reports on, Hydrology, Hydraulics, Preliminary Options and Strategic Environmental Assessment (SEA), which are summarised in Sections 2 of this report.

The development of the Flood Risk Management Plan is summarised in Section 2.5 of this report.

The full list of project reports to date, which also include a series of relevant consultation and environmental reports and specific assessments of flood risk, survey data, rainfall and blockage within the Suir CFRAM study area, are listed in Section 2.8.


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2 OVERVIEW OF PROJECT DELIVERABLES

2.1 Brief History of UoM16 The Suir CFRAM study was initiated in April 2007 with the first Steering Group meeting held in the Park Hotel, Clonmel on Thursday 26th April 2007. The requirement for an Inception Report was introduced two years later in the National CFRAM specification. Hence the requirement for a Suir CFRAM Inception Report was not required as part of this study specification.

2.1.1 Sustainable Urban Drainage System (SuDs)

Similar to the requirement for an Inception Report, a report on SuDs was not a requirement of the Suir CFRAM specification.

2.1.2 Planning & Development

Similar to the requirement for an Inception Report, a report on Planning and Development was not a requirement of the Suir CFRAM specification. However a GIS deliverable was developed as part of the study.


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2.2 SUMMARY of UoM16 HYDROLOGY REPORT In 2010, generation of the hydrology report commenced. The Suir CFRAM was one of four pilot studies on the national approach to flood risk management undertaken by OPW.

The hydrology report provides a description of the catchment together with the approach used in the data collection process. Relevant datasets were identified for use, including flood history, topographical data, hydrometric data, tidal data, mapping data and historic data.

For the purpose of meteorological and hydrometric data analysis, the Suir CFRAM study was used to alpha-test the emerging Flood Studies Update (FSU) methodologies applied to catchment-wide flood modelling. Estimation of extreme design flows for the Suir main channel and its significant tributaries were generated based on these analyses and compared with the values generated by the traditional method of the Flood Studies Report (FSR).

Following this, it summarises the outputs from the analysis, which were taken forward as inputs for the hydraulic modelling. Discussion is provided on the outputs in terms of degrees of confidence, which can be attached to the outputs and the opportunities for providing greater certainty for future studies, including opportunities for improving the observed data used to inform the study.

The hydrology report was finalised in 2016 after completion of the hydraulic modelling and the rating reviews. These activities were interactive and required input from the mapping consultation programme before in order that they could be concluded.

The Suir catchment can be characterised hydrologically as follows:

� The catchment has a wide range of climatic and physiographic characteristics but overall is considered to be a catchment of average level rainfall. The drier lowland areas around the centre and East of the catchment have SAAR values of 895.27mm to 941.36mm, while the higher land around the Devil’s Bit, the Galtee and the Silvermine mountains have SAAR values up to 1471.29mm.

� Hydrometric data is of good quality and availability within UoM16. The Suir Catchment has 28 active river flow gauges, 18 of which are maintained by the OPW. 7 of these flow gauges are on the main Suir, distributed from the upper reaches to near the tidal limit. 9 of the gauges have digitised records that are a little over 50 years in length. In addition to the above gauges, there are 11 tidal /semi-tidal gauges. A review of all the gauges in the catchment was undertaken as part of the Suir CFRAMs and reported on in a separate report that accompanies the Hydrology Report. In many cases, 1D hydraulic models (HEC-RAS) were developed in order to complete this review and in one case (i.e. Cahir Park), a 2D MIKE hydraulic model was developed.

2.2.1 Key Outputs

� The use of emerging FSU methodologies on a catchment scale project,

� Identification of suitable calibration data and verification based on known flood events,

� The generation of rainfall-runoff boundary units for hydraulic model calibration,

� Design inflows and hydrographs for a range of durations for the 50%, 20%, 10%, 5%, 2%, 1%, 0.5% and 0.1% AEP events for present day conditions for each Hydrometric Estimation Points (HEP) catchment,

� Design inflows and hydrographs for a range of durations for the 50%, 20%, 10%, 5%, 2%, 1%, 0.5% and 0.1% AEP events for the two future scenarios (Mid-Range Future Scenario and High End Future Scenario) for each HEP catchment.


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2.2.2 Key Findings

The primary output of the hydrological analysis was design flow estimation which was based on observed data and estimation/modelling techniques. Hydrological analysis required further validation through the calibration of the hydraulic models, which is reflective of best practice in hydrology/hydraulic modelling for flood risk assessment. Statistical analysis techniques with rainfall run-off modelling, showed that the design flow estimation has as high a degree of certainty as is possible prior to calibration/validation and that this yielded efficiency and increased accuracy in the hydraulic modelling phase of the CFRAM study process.

Full details of the hydrologic analysis can be found in the Suir CFRAM study HA16 Hydrology Report and accompanying Gauge Review Report.


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2.3 SUMMARY of UoM16 HYDRAULICS REPORT 9 hydraulic models have been developed for the entire Suir Catchment area and the AFAs located within the catchment, see Figure 2.1. These models simulated how each watercourse will react to various sizes of floods and its interaction with the surrounding floodplain. Details of the hydraulic analysis can be found in the Suir CFRAM study HA16 Hydraulics Report.

Hydraulic analysis was undertaken in order to identify the location and frequency of flooding within the extents of UoM16 modelled watercourses and AFAs. The analysis utilised computational modelling software informed by detailed topographical survey information (channel sections, in-channel and flood defence structures, bathymetric and floodplain), combined with hydrological inputs (riverine inflows and sea levels) and water-level control parameters (such as channel-roughness), to determine flood hazard. A series of flood extent, zone, depth, velocity and risk-to-life maps known collectively as flood hazard maps were generated based on the model results.

Six Models (M1-M6) have been developed using 1D ISIS and 2D TUFLOW software, developed by CH2M and BMT WBM respectively. These six models are not tidally influenced. 2D software has been used to simulate the multi-directional flows across the urban floodplains of Thurles and Tipperary Town.

The 1D and 2D components of the models are hydro dynamically linked such that water can flow between the river and floodplain during the event to simulate the observed flood mechanisms. A 1D approach has been taken in the remaining AFAs.

The remaining three models (Models M7-M9) are in the downstream region of the Suir catchment and they are tidally influenced. These three models have been developed in MIKE FLOOD (DHI). The influence of coastal water levels has been modelled by applying an appropriate water level boundary profile to the downstream extent of model 9. Coastal data has been taken from the Irish Coastal Protection Strategy Study (ICPSS). The effects of sea levels are propagated upstream by the modelling software allowing the interaction of river flows and coastal water levels to be modelled accurately.


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Figure 2.1 Map showing the modelled watercourses and AFAs within UoM16

The principal model parameters that are reviewed and amended during the model calibration process are:

� Bed and floodplain roughness coefficients,

� Structure roughness and head loss coefficients,

� Timing and magnitude of hydrographs.

The accuracy of the models representing existing conditions in terms of flood level, depth, extent and flow velocity allows potential flood options to be meaningfully assessed, enabling the appropriate actions/decisions to be taken.

There is historical evidence (Local newspaper articles, helicopter footage of the 2008 flood observed stage data) of a high level of flood risk within certain areas of the Suir CFRAM study area with significant coastal and fluvial flooding events having occurred in the past. A detailed account of historical flooding can be found in the Hydraulics report that has been used to calibrate and validate the hydraulic models (flood extents). Furthermore, the models were verified using Local Authority and public feedback.

2.3.1 Key Outputs

The calibrated/validated models were used to simulate current and future flood hazard conditions and potential options to facilitate the appraisal of possible flood risk management actions and measures. The models were run for eight flood probabilities under the current design scenario.


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Future potential changes which may affect the outputs of the CFRAM study were also assessed:

� The climate change allowances are applied to all models. Urbanisation and afforestation allowances are applied on a case by case basis as required, the factors themselves having been derived during the hydrology analysis by looking at historic urbanisation growth indicators and estimating appropriate growth factors for Mid Range Future Scenario (MRFS) and High End Future Scenario (HEFS).

The integration of hydraulic analysis with previously undertaken hydrological analysis is also outlined, with AFA / High Priority Watercourse (HPW) specifics provided. Full details of the methodology, datasets used and outcomes of the hydraulic analysis for the Suir CFRAM study area can be found in the final hydrology report.

2.3.2 Key Finding

A series of flood extent, depth, velocity, zone and risk-to-life maps were generated based on the model results. The outputs from the hydraulic analysis were used to inform the subsequent stages of the CFRAM study: to simulate potential options, facilitating the appraisal of possible flood risk management actions and measures. Model outputs also helped to determine and map the degree of flood risk. The specific findings in relation to the hydraulic modelling of each of the AFAs within UoM16 are summarised as follows:

� More focus should be on Medium Priority Watercourse (MPW) modelling. For this an accurate topographic data set is required and it is recommended to complete a survey of the entire river catchment.

� For four of the AFAs new measurement gauges are recommended.

� 2D-modelling should be further investigated to improve accuracy especially in the flood plains and urban areas.

� Blockage scenarios were based on experienced / observed floods. It was difficult to define the 100-year event and damage. Therefore, focus should be on clearance of the rivers to prevent flooding due to blockage in the channel and at structures.

More lessons learned and findings have been reported in Section 4.


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2.4 SUMMARY of UoM16 PRELIMINARY OPTIONS REPORT The purpose of the Preliminary Options Report (POR) was to provide detailed information in relation to activities associated with Flood Risk Assessment and the development of the Flood Risk Management Options for the Suir catchment.

In 2011, the OPW completed a Preliminary Flood Risk Assessment (PFRA) in accordance with the Articles 4 and 5 of the EU Floods Directive. The PFRA identified Areas for Further Assessment (AFAs) which were then taken forward in the CFRAM programme. The AFAs in the Suir Catchment were identified in consultation with the study stakeholders prior to the commencement of the PRFA. All AFAs identified by the PFRA were already in the Suir CFRAM study. In fact, the list of Suir AFAs included an additional four AFAs. The Suir CFRAM study has identified 25 areas for further assessments (AFAs).

The identified viable structural and non-structural options and measures for the effective and sustainable management of flood risk in the study area were outlined from a number of different perspectives and included considerable input from numerous organisations and additional studies such as a Strategic Environmental Assessment (SEA) and an Appropriate Assessment (AA) where necessary.

The starting point in this process was to identify the Spatial Scales of Assessment (SSA) applicable to the Suir catchment. These can include:

� Unit of Management SSA

� Sub-catchment SSA

� AFA SSA

� Flood Cell SSA and

� IRR SSA

Identifying the SSAs in the Suir catchment informed the Flood Risk Management (FRM) measure screening process by assuring that only measures appropriate to the spatial scale are considered. Following this, a review of the flood hazard maps was undertaken to ascertain where flood risk management would be necessary and to what extent. This review consisted of a more detailed flood hazard and risk assessment for all twenty-five AFAs identified.

For some, the results of the more detailed analysis proved that the level of flood risk from rivers and/or the sea was considerably lower in the AFAs than previously envisioned.. In other instances, schemes have been completed or initiated since the initial list of AFAs were identified. In such cases, the development of FRM measures were not pursued. The result was ten of the twenty-five AFAs being progressed to development of FRM Options stage.

Once the risk was satisfactorily identified, a screening process was applied to a list of pre-determined, SSA appropriate FRM measures in order to rule out those that were not applicable and carry forward the measures that could potentially provide a solution, or part of a solution to the next stage.

The applicability and viability of each of the FRM measures was considered in terms of the following criteria:

� Applicability to the area (i.e. technical merit),

� Economic (potential benefits, impacts, likely costs etc.),

� Environmental (potential impacts and benefits),

� Social (impacts on people, society and the likely acceptability of the method), and

� Cultural (potential benefits and impacts upon heritage sites and resources).

The measures that were not screened out were then used as ‘building blocks’ to create FRM options unique to each AFA.


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To ensure consistency across all the national studies, and to aid in the developing of a prioritisation matrix for all options in the later stages of the project, Multi-Criteria Analysis (MCA) was applied to each option under the same criteria mentioned above with sub-objectives contained within each. This generated a score for each option that could then be used to identify preferred options and also rank options at a national level.

Upon completion of the preliminary optioneering in draft format for each of the ten AFAs, a formal consultation process on the options was required under Statutory Instrument No. 122 of 2010 in accordance with the EU Floods Directive specifications. This provided the Local Authorities, key stakeholders and members of the public an opportunity to consider what was being put forward and document their concerns and opinions on the proposed measures, such as the one they considered would be most appropriate.

The feedback received from the public consultation was collated and considered, resulting in several proposed FRM Measures being modified. Public consultation was not undertaken for the non-progressed AFAs. The emerged preferred options formed the basis of the Preliminary Option Report (POR) and Flood Risk Management Plan (Plan) for the Suir CFRAM study.

In 2016, OPW completed the Preliminary Options Report (POR); it was accompanied by AFA specific appendices containing supporting technical details on all potential options (whole life costing, multi criteria analysis and option drawings) and also supporting information such as method screening, calculations and GIS layers supporting the risk and options analysis.

2.4.1 Key Outputs

� Ten AFAs within UoM16 were included for optioneering at POR stage; for the rest of the AFAs, where FRM options were not developed under the Suir CFRAM Programme, recommendations such as maintain the existing regime, application for The Minor Flood Mitigation Works and Coastal Protection Scheme were suggested and further developed in the Flood Risk Management Plan (Plan).

2.4.2 Key Findings

� OPW awarded a specialist contract to JBA to develop an analysis tool to support the whole-life costing of the CFRAM study options.

� This tool was consistently applied to all national studies for the purpose of commensurate scores so that the resulting options would be comparable for use to develop a nationally prioritised programme of implementation.

� Local Authority and the OPW regional team feedback raised concerns regarding the outcome of costs for some options developed under this whole-life costing tool with particular regard to smaller schemes. A wider perception that coastal works costing may be generally too conservative, whilst culverting works may be less was also observed. The cost for diversion channels was also considered to be conservative.

� During the risk assessment analysis, OPW noted that there were significant gaps and inconsistencies between the An Post GeoDirectory geodatabase and the OSi building layers. There was therefore significant modification and updates required. In addition to this, datasets on basements were difficult to obtain with many of them being belatedly identified by means of Local Authority feedback and public consultation days. This resulted in unavoidable reworking of damages and options in some cases.


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2.5 SUMMARY OF UoM16 FLOOD RISK MANAGEMENT PLAN

The development of flood risk management plans, which are the statutory output of the CFRAM studies, was led by the OPW. The OPW produced a template and undertook a series of consultations within the OPW, with other relevant government departments and national groups.

The first draft of the template was produced for comment in July 2015. It was intended to indicate the overall format of the draft Plan, and in particular, the structure of some template tables and forms that the OPW required to be used in order to facilitate reporting to the European Union, Common Implementation Strategy Working Group.

Revision C of the draft Plan was produced by the OPW in May 2016, this version, incorporated later additions and policy updates. This version formed the basis of the draft plans that were consulted on during the second half of 2016.

UoM specific material (text, maps and datasets) were populated by OPW drawing largely on the supporting technical studies on hydrology, hydraulics and the preliminary options assessments. The OPW reviewed the draft plans at project level with regard to consistency at national level. The progress group members also reviewed the draft Plans providing information about relevant plans and programmes and previous projects.

Within the draft plans, Areas for Further Assessment (AFAs) considered to be at low risk were identified and the measures for such areas were not presented within the plan. The relevant measures remain available within the preliminary options report and may be more readily implemented via the minor works programme. Within UoM16, the following low risk AFAs were identified:

� Ballymacarbry, � Kilsheelan,

� Ballyporeen, � Mullinavat,

� Bansha, � Portlaw,

� Clogheen, � Tipperary Town1

� Fiddown,

Note 1: Tipperary Town was included here even though damages were calculated at €3M. Damages are calculated on

entire floor area. However, only small proportion of the property is considered to be at risk.

A number of existing Flood Risk Management measures have been completed or initiated since the initial list of AFAs were identified. These AFAs have not been progressed further through the Plan. The following schemes have been completed or are due for completion:

� Waterford City Flood Alleviation Scheme (Completed in 2015),

� Clonmel Flood Defence Scheme (Completed in 2012),

� Carrick-on-Suir Flood Defence Scheme (Completed in 2001),

� Templemore Flood Relief Scheme (In progress),

� Mullinahone was part of a completed minor works scheme.

The plans are supported by the final core hazard and risk mapping and the Plan’s statutory environmental assessments under the Strategic Environmental Assessment (SEA) Directive


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and the Habitats Directive (Volume II). The environmental assessment process, which resulted in an SEA Environmental Report and Natura Impact Statement, influenced:

� the development and assessment of measures,

� the selection of preferred measures,

� the identification of mitigation measures and

� an environmental monitoring programme during the Plan’s implementation.

2.5.1 Key Findings

The plan’s main deliverable is a list of potentially viable measures to manage the flood risk. .

The plan incorporates a suite of certain prevention and preparedness measures related to flood risk management that form part of wider Government policy. These measures, set out below, should be applied across the whole of UoM16, including all AFAs:

� Sustainable Planning and Development Management

� Sustainable Urban Drainage Systems

� Voluntary Home Relocation

� Local Adaptation Planning

� Land Use Management and Natural Flood Risk Management Measures

� Maintenance of Drainage Districts

� Flood Forecasting and Warning

� Review of Emergency Response Plans for Severe Weather

� Promotion of Individual and Community Resilience

� Individual Property Protection

� Flood-Related Data Collection

� Minor Works Scheme.

No measures were identified at Thurles & Holycross sub-catchment and Cahir & Ardfinnan sub-catchment scales. However, ten AFA specific measures were identified under the Suir CFRAM study.

It should be noted that there were some policy changes for measures between the preliminary option reporting and Plan finalisation, such as mechanisms to support relocation and individual property protection.

The public consultation undertaken on the preliminary options necessitated some revisions of the options.

� Plan.

A common theme throughout the CFRAM study consultation process was the need for a programme of when the measures would be implemented. The draft plans did not have such an overall programme, as this is dependent on the outcome of the national consultation process. However, it is intended as part of the final Plan Plan that a national priority list for the implementation of the proposed options will be developed. Plan


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2.6 Summary of the Strategic Environmental Assessment (SEA) and Natura Impact Statement (NIS)

2.6.1 Strategic Environmental Assessment

The SEA Environmental Report has been prepared to provide a formal and transparent assessment of the likely significant impacts on the environment arising from the Plan for UoM16 under the Suir CFRAM study, including consideration of reasonable alternatives. As the Plan has the potential to impact upon European sites, there is a requirement under the EU Habitats Directive to carry out an AA and to produce a NIS.

The main significant environmental contributions were presented during the Preliminary Screening of FRM Methods, the Multi-Criteria Analysis of FRM Options (Alternatives) and in the Environmental Assessment of Preferred Options via this SEA Environmental Report and NIS. In these key stages of the Plan development environmental specialists helped to steer the planning team towards more sustainable FRM methods, provided guidance on environmental issues in the areas of interest, assisted in the development of FRM alternatives, provided positional improvements of methods and advised on the incorporation of methods into options to enhance sustainability. The development of FRM options was an iterative process between the environmental and FRM planning specialists, with the MCA of FRM options stage being heavily influenced by the environmental specialists.

The highest scoring option for each area of flood risk (e.g. catchment or AFA), along with consideration of feedback from public and stakeholder consultation and engineering judgement, has been used to identify the preferred option in the draft Plan.

The non-structural options (twelve measures as set out in the Plan) are considered to have no physical outcome or are an existing process and so they have not been assessed for impacts on the wider environment within this SEA environmental Report. The impacts on the environment due to the maintenance of drainage districts measure is the responsibility of the Local Authority.

The SEA Environmental Report details the environmental assessment of engineering options detailed in the draft flood risk management plan (Plan). There was found to be the potential for some negative environmental impacts from construction of these engineering options on the wider environment; however, in the medium to long term, following the completion of works and the re-establishment of areas, the impacts are generally significantly positive with only minor residual negative impacts. These medium to long term, positive impacts are anticipated due to the increased management of flood risk and protection of people, property, soils, heritage features, infrastructure and amenity. The SEA Report recommends environmental mitigation measures to avoid or minimise these potential negative impacts of implementing the engineering options. It is recommended that these measures are adopted in full at the detailed design stage of assessment of these options.

The SEA Report details environmental monitoring to be undertaken during development of the second cycle of the Plan, to identify at an early stage any unforeseen adverse effects due to implementation of the plan. This environmental monitoring has been adopted into the draft Plan.

2.6.2 Habitats Directive Assessment (Natura Impact Statement)

The NIS details the findings of the Suir CFRAMS Stage Two Appropriate Assessment conducted to further examine the potential direct and indirect impacts of the FRM Options advanced in the draft Plan. The Plan considers the AFAs of Ardfinnan, Borrisoleigh, Cahir, Knocklofty, Fethard, Golden, Holycross, Newcastle, Piltown and Thurles in respect of the following European sites:

� Hook Head SAC (000764);

� Lower River Suir SAC (0002137); and


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� River Barrow and River Nore SAC (002162).

These European Sites were identified by way of a screening exercise that determined the risk of significant effects in relation to the above sites. The screening exercise was conducted using the source - pathway - receptor method, examining surface water, groundwater, land and air pathways.

The Appropriate Assessment investigated the potential direct and indirect impacts of the proposed works on the integrity and interest features of the above European Sites for each of the AFAs where FRM Options have been proposed in the draft Plan.

The Appropriate Assessment investigated the potential direct and indirect impacts of the proposed works on the integrity and interest features of the above European sites, alone and in-combination with other plans and projects, taking into account the sites' structure, function and conservation objectives.

Where potentially significant adverse impacts have been identified, a range of mitigation and avoidance measures have been recommended to help eliminate them by design or reduce them to acceptable levels.

In conclusion, the proposed draft Suir Plan will not have a significant adverse impact on the screened in European Sites of Hook Head SAC, Lower River Suir SAC and River Barrow and River Nore SAC provided the mitigation measures of the NIS are adopted in the Plan and at project stage.

2.6.3 Final Environmental Report and SEA Statement

As part of the finalisation process of the Plan, the SEA Environmental Report was updated and an SEA Statement was produced. Both documents detailed the changes that occurred because of the public consultation process.


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2.7 Directory of Deliverables (with Final Plan) � Geographical Information Systems (GIS)

GIS data indicating the location or extent of each measure, attributed with the following data:

o Type of measure

o Name of measure

o Short description of the measure

o Location as:

a) Coordinates (x,y) of centroid of measure, where relevant (i.e. Location-specific physical interventions), or

b) Name of location (short description), where measure is not a physical intervention of is widespread

o Area(s) for which the measure has been included in the Plan to achieve the specified objectives (AFA(s) or UoM, as appropriate)

o Priority of the measure

o Cost of the measure

o Legislation under which the measure has been implemented (where relevant)

2.8 Supplementary Deliverables (T\CFRAM\Proposed Final Deliverables List)

� Reports

o Hydrology Report & Gauge review Report

o Hydraulics Report

o Final SEA Environmental Report and SEA Statement

o Final Natura Impact Statement (NIS)

o Preliminary Options Report

o Flood Risk Management Report

� Geographical Information Systems (GIS)

o Spatial Scales of Assessment (SSAs) Boundaries

o High Priority Watercourses (HPWs)

o Medium Priority Watercourses (MPWs)

� Safety File (Included as part of the Final Report)

� Datasets

o Flood Relief / Risk Management Measures

o Historic Flood Events

o Hydrometric Data

o Meteorological Data

o Land-Use Data


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o Soil and Geological Data

o Planning and Development Information

o Defence and Coastal Protection Asset Data

o Existing Survey / Geotechnical Data

o Environmental Data

o Flood Event Collection Register

o Economic Damages

o MCA

o Cost Calculations

o Other Receptor Data

� Survey

o Defence Asset Database

o Channel and Structures

o Flood Plain LiDAR (If Altered)

� Flood Maps (see details of folder structure at end of report)

o Core - Flood Extent

o Core - Flood Depth

o Core - Risk to Life Function

o Core - Specific Risk – No. of Inhabitants

o Core - Specific Risk – Types of Economic Activity

o Core - General Risk – Environmental

o Non-core – Flood Zone

o Non-core - General Risk – Social

o General Risk – Cultural Heritage

o General Risk – Economy

o Non-core – Defence Failure Mapping - Extent

o Non-core – Defence Failure Mapping - Depth

o Non-core – Defence Failure Mapping – Velocity

o MPW Mapping

o Non-core mapping (Futures, Breach, Uncertainty)

o All GIS Mapping

o

� Model Files

o Design Runs

o Sensitivity Analysis

o Breach Analysis

� Collation of Measures Database.

� Appendix VI / VII of the Stage II Specification


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� Defence Asset Database

� Final Model Files (including Gauging Station Reviews & Analysis)

� Dynamic/Coded Damages and Benefit Datasets

� All finalised Survey Data (Tidy topographical survey data)

� Outstanding flood event reports

� Outstanding Project Management Deliverables (e.g. Minutes etc.)

� Miscellaneous materials bought under OPW Project Budget


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3 APPLICATION OF DATA

A number of different types of survey data was gathered as part of the study. The following sections detail the various survey data sets collected.

3.1 1960’s Survey Data In the 1960’s the OPW undertook an extensive Channel and Structure Cross Section Survey (i.e. CSCS) of the Suir Catchment with the objective of pursuing an Arterial Drainage Scheme under the 1945 Act. While the scheme was not progressed, the survey was completed.

The suitability of the 1960’s survey data was determined by two check surveys and deemed suitable for use in the Suir CFRAMs. Full details of the checking process are provided in Appendix J of the Hydrology Report. The use of this data by the study was limited to Medium Priority Watercourses (i.e. MPWs) and to supplement where required the surveys acquired in 2007 and 2010.

3.1.1 Conversion Process

In addition, the Suir Project Team in collaboration with Maltby Survey Limited developed a methodology for converting the paper records of the 1960’s surveys that had been recorded in imperial units and to Poolbeg datum into SI units and the current Malin Datum. This conversion rendered the data suitable for hydraulic modelling.

Use of the 1960s survey data while it did reduce the need to undertake surveys on the MPWs channels it did require significant resource inputs from the project team in terms of checking and its conversation for use in the hydraulic models. For future, the use of such data should be carefully considered and any envisaged savings with survey procurement should consider the additional resource requirements with the use of such historical data.

3.1.2 Cross Section Naming

For the 1960’s data, the cross sections were typically spaced in units of 100 yards apart. For example, two successive cross sections would be labelled 10/00 and 11/00. If a structure occurred between these two cross sections, it would have been labelled as 10/20 that would indicate that the structure is 20 feet from the cross section 10/00. OPW convention in relation to chainages was that chainage “00” occurs at the end/outfall of the river and increased in an upstream direction. Negative chainages are used to identify tidal reaches. In the Suir project folders an index of the 1960’s survey data has been saved as an excel spreadsheet.

3.2 2007 & 2010 Survey Data In June 2007, Maltby Survey Limited were commissioned to undertake a Channel and Structure Cross Section (CSCS) Survey of all the Suir AFAs and eight hydrometric gauges selected for rating review. In 2010, following extensive hydraulic model construction a further survey was undertaken at locations where additional detail was deemed necessary. These surveys were undertaken using modern GIS surveying techniques and supplied in a format suitable for hydraulic modelling software. This survey was undertaken by Murphy Surveys.

3.2.1 Survey Photographs

The survey data supplied from the 2007 and 2010 surveys is saved in a number of formats and includes a word document of photos taken at each cross section. The photos are labelled with the same chainage as the surveyed cross section. Details of the how the sections are named in the hydraulic models are outlined in the following document - 1891_REP_OPW_120207_Suir ISIS Modelling Guide WIP. In order to identify the correct


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photo/survey cross section from a model, first use the key plan AutoCAD drawing (i.e. KP in title) to determine the chainage of the survey section.

3.3 LIDAR Data and Ortho-Photographs Data Light Detection & Ranging Data (LiDAR) was flown in 2008 and was supplied in 10m, 5m & 2m Digital Terrain Models (DTM) and 2m Digital Elevation Model (DEM). It was used to model the floodplains.

The LiDAR survey report produced in January 2009 has been saved at Lidar (\\OPW_FILER 05) () 1868-NFDTM-DELIVERABLES\2007 - 04 - SUIR\LiDAR\Current\report.

Blom Aerofilms Limited undertook the orthophotographic survey for the Suir CFRAMs in November 2007. These photos were produced to a 25cm resolution accuracy. More details are contained in the survey report which has been saved at Lidar (\\OPW_FILER 05 \1868-NFDTM-DELIVERABLES\2007 - 04 - SUIR\LiDAR\Current\report.

The CFRAM specification requires that a threshold survey is undertaken where estimated potential damages are greater or equal to €500,000 for a 0.1% AEP and for entry points to significant basements or underground car parks. No such surveys were required for the Suir CFRAMs.

The property floor levels were determined from LiDAR datasets. The minimum ground level nearest the building footprint was extracted from the LiDAR dataset to which 150mm was added for each step up determined from a visible examination of the building from Google Maps. This method provided a conservative floor level for the building. The accuracy of the aerial survey was checked with ground topographical survey from 46 locations. The Root Mean Square (RMS) accuracy of the LiDAR dataset is given as 0.20m. No correction on floor levels has been taken into account for this inaccuracy. No threshold surveys have been undertaken for the Suir CFRAM.

Any identified option brought to detailed design stage would be subject to a further damage assessment based on actual floor level surveys. For more detail, reference should be made to Guidance Note 2 Survey Requirements for High and Medium Priority Watercourses.

3.4 Economic Data

3.4.1 Damages

Damages were calculated based on the entire floor area of a building once the flood outline reached the edge of a building. In other CFRAM studies, damages were calculated when the flood outline reached the centroid of the building.

Damage assessment involved a manual visual inspection of GIS datasets on a property by property basis. In future studies, it is recommended that this process be automated to improve efficiency.

3.4.2 Cost Methodology

The Unit Cost Database (UCD) was developed for the purpose of consistent construction costs representation across the six national CFRAM studies undertaken by OPW.

In order to determine appropriate unit costs for common methods of flood risk management, for a range of conditions and scales, the UCD was calibrated against actual costs, taking into account the date, condition and scale of construction. This as well as the Whole Life Cost (WLC) estimation process which includes costs incurred over the period of time to which the flood risk management measure has been designed (i.e. operational and maintenance costs), formed part of the overall CFRAM appraisal process, as shown in Figure 3.1 and detailed in the Preliminary Options report and the Flood Risk Management Plan. Each of the steps below forms part of standard appraisal processes.


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Figure 3.1 Cost Estimation within the Wider Appraisal Process

In total, nineteen flood risk management measures were investigated and costed. The nineteen core measures plus the options of cost variables based on height and/or length combines to give over 220 combinations that have unit costs associated with them in the database.

The Suir CFRAM was the only pilot study to also use this database and for this reason, it is comparable to the rest of the country’s CFRAM results.

3.4.2.1 Methods and Factors Unit costs for a range of methods were determined to support the CFRAM process. The costs related to the construction and implementation of each method and included relevant annual operation and maintenance costs (if applicable). The range of factors cover a range of flood risk management activities covering both structural and non-structural approaches. A full list of the methods and factors costed is provided in the CFRAM Unit Cost Development Project Report (2014).

3.4.2.2 Whole Life Costing and Methodology Whole life costs enable investment options to be more effectively evaluated through the consideration of all costs rather than just the initial capital costs. This facilitates the choice between completing alternative options/strategies and ensures planning decisions and sustainable solutions are sufficiently robust and backed up by consistent and accurate costed programmes of activities.

Whole life estimation required costs of acquiring the solution (consultancy, design, construction etc.), operating the system, and maintaining the system over the whole life of the defence as shown in Figure 3.2.


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Figure 3.2 Whole Life Cost Estimation

The whole life cost estimation needed to identify all activities that constitute flood defence management practice e.g. inspection, vegetation management, repair, operations, incident management, general administration and regulatory activities.

The four key cost elements that would normally need consideration as part of the whole life cost include the following:

� Acquisition or enabling costs

� Capital costs

� Operational costs

� Other and end of life costs

The UCD developed for the CFRAM studies focused mainly on capital and operational costs. The basic approach to cost estimation is shown in Figure 3.3


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Figure 3.3 CFRAM Approach to Cost Estimation


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3.5 Environmental Data RPS (Cork) Consultants led the scoring of the environmental objectives using the Multi Criteria Analysis (MCA) and the preparation of the environmental reports.

The type of environmental data accessed using the MCA included the following:

� Support the objectives of the WFD,

� Support the objectives of the Habitat Directive,

� Avoid damage to, and where possible enhance, the flora and fauna of the catchment,

� Protect, and where possible enhance, fisheries resource within the catchment,

� Protect, and where possible enhance, landscape character and visual amenity within the river corridor, and,

� Avoid damage to or loss of features, institutions and collections of cultural heritage importance and their setting.

The baseline environmental datasets assessed in the SEA include the following:

� Biodiversity, Flora & Fauna,

� Population & Human Health,

� Geology, Soils and Land use,

� Water,

� Air,

� Climate,

� Material Assets,

� Cultural, Archaeological and Architectural Heritage,

� Landscape and Visual Amenity,

� Fisheries, Aquaculture and Angling, and

� Amenity, Community and Socio-Economics.

Further detail is contained in Guidance Note GN28 Option Appraisal and Multi-Criteria Analysis Framework.


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4 ANALYSIS AND LIMITATIONS

4.1 Hydrology Approach and Uncertainties It should be noted that while the Hydrology Analysis on the Suir CRFAM Study was substantially concluded in 2015, data gathered and used within the study is based on the relevant moment in time. The following datasets and their respective time frame are listed below:

� LiDAR topographical survey – flown Summer 2008,

� Calibration data – Met Éireann synoptic and non-synoptic rain gauges 2009,

� Historic flood events recorded up to 2009,

� Corine Land Cover Data – 2006,

� Population change and growth – Census 2006,

4.1.1 Recommendations

The following potential opportunities to improve the hydrological analysis further in the next cycle of the CFRAM were identified:

� It is recommended that for all future Suir CFRAM catchment studies, relevant datasets should follow on from those listed in Section 4.1.

� The Suir catchment has an extensive network of gauges that are generally operated by either the OPW or the EPA / Local Authorities. The exception is the tidal gauge at Great Island, which is operated by the Port of Waterford. There are three OPW gauges that need to be reviewed and these are listed below:

o Gauge Ref: 16001 Athlummon. This gauge gives a very flat growth curve and seems to be experiencing events greater than 0.1% AEP event regularly.

o Gauge Ref: 16137 Newbridge. This gauge was installed in mid-2005 as part of the flood warning system for Clonmel. However due to the turbulent nature of the flow through the bridge at the gauge site, it has not been possible to obtain reliable readings. Hence, data from the gauge was of limited use for the Study.

o Gauge Ref: 16138 Ballydonagh. Like the previous gauge, this one was also installed as part of the flood warning system for Clonmel. However, due to the inaccessible nature of the gauge location, particularly due to high flow events, there are no reliable readings and hence the gauge was of limited use.

o Installation of new gauge for the AFA of Mullinahone to gain a better understanding of the hydrology for hydraulic modelling.

� A number of rain gauges were installed in 2005 by the OPW as part of the Clonmel Flood Warning System. However, due to both brevity and the non-continuous records, these were of limited use for the study. If the reliability of the gauges and their records were improved, this dataset could be of benefit for future updates of the Suir CFRAM.

� While there is extensive meteorological and hydrometric data in the Suir catchment, there was difficulty in obtaining the digitised data. Digitising large amounts of paper charts was not possible within the timescales of the study. It is recommended that the full data record be digitised to enable future reviews of the Suir CFRAM study hydrology, including peak over threshold statistical analysis and unit hydrograph analysis. It is also recommended that a joint EPA and OPW review be undertaken to ascertain whether further collaboration is possible in accessing, storing and disseminating data from gauges.


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� In addition to determining the existing flood risk, there are a number of factors that can influence future flood risk in the Suir catchment. These include climate change, afforestation and urbanisation. In relation to climate change and net sea level rise, it is recommended that subsequent revisions of the Suir CFRAM consider data available from a Continuous Global Positioning System (CGPS) station at Castletownbere in assessing isostatic subsidence along the south coast of Ireland.

� As previously mentioned, in order to facilitate the assessment of potential future flood risk, future scenarios were proposed. The range of parameters incorporated in each of the future scenarios has been determined from a comprehensive review of current research and data. This area will continue to be actively researched and it is recommended that the outcomes of this research be used to inform future catchment studies.

4.2 Hydraulic Modelling Approach and Uncertainties

4.2.1 Survey Data

Figure 4.1 shows the flood depths for the 100-year event just upstream of Golden. The area within the red circle highlights areas of shallow depth. However, the river within this area is much deeper then represented. Here the flood depth minus the LiDAR is being represented. For the LiDAR data, no correction has been done for the deep river channel. Therefore, at some areas you would see the LiDAR over the actual river cross-section data. The current river cross-section data set is based on the 1960’s survey. For the next phase of the CFRAM, it is recommended to survey the entire River Suir. Following this, the next step is to clip the channel for the LiDAR data and to integrate the river cross-sections into the LiDAR to get a single topographic data set of the flood plains, urban areas and river channel. Extensive LiDAR data was collected but only used to define the topography within the 2D extent of the hydraulic models (Tipperary and Thurles AFA). Any works carried out on the rivers in the AFAs post 2006 e.g. minor works scheme would need to be incorporated into the next round of modelling.


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Figure 4.1 Flood depth just upstream of Golden, red circle highlights small flood depth indicating very shallow areas in the river.

4.2.2 Model uncertainty with 1D models

In general, 1D models have their limitations. They have a limited level of detail and accuracy. This should be taken into account when doing successive analyses like the damage and risk assessments.

The AFAs of Thurles, Tipperary Town, Carrick-on-Suir, Piltown, Portlaw and Fiddown have been modelled using linked 1D-2D models. It is recommended that future studies develop more 1D-2D models for the some of the other Suir AFAs, particularly, Cahir, Clonmel and Waterford City.

4.2.2.1 Floodplain Representation

4.2.2.2 For the AFAs of Thurles, Tipperary Town, Carrick-on-Suir, Piltown, Portlaw and Fiddown, 2D flood plains were added to the 1D models. Presently, the floodplains in the other AFAs are not modelled in this manner, which can result in less accurate results. It is recommend that future studies make more use of linked 1D-2D models for floodplain representation. Overestimating flood extents

1D models can overestimate the flood extents and subsequent flood depth in certain areas. This can be the case where steep slopes exist. The 1-D model and the resulting flood extents are not volume based. The flood extents are only related to the water level in the centre line of the river that is then extrapolated over its cross-section.


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In the case of the tributary of the Suir in Cahir, it would be more realistic to apply a 2D-modeling approach. During public consultations, the public were surprised with the extent of the flooding in the area to the left bank of the tributary. There is no evidence to believe it is overestimated, therefore it was not amended. When applying a 2D-model the amount of water that is flowing into the area at the left bank would be volume based. The result would be more accurate. The flood extent at the left bank of the tributary is show in below figure (area indicated in red circle).

Figure 4.2 Flood extent of Cahir tributary river. Red circle indicates possible overestimation of flood extent

4.2.2.3 Underestimating flood depths The first calibration and verification exercises focused on matching flow in the river and the resulting flood extents. Less emphasis was placed on actual flood depths in the urban areas resulting from an extreme flood. In some urban areas, the river stages were underestimated in the order of 20 – 60 cm. Subsequently, this resulted in too low and unrealistic flood depths for the properties. The underestimated flood depths had significant impact on the damages from flooding and therefore the risk. A number of revisions have been made between the preparation of the POR and the final Plan to many of the urban areas (AFAs): Thurles, Golden, Knocklofty and Fethard. The damages increased with the increase of flood depth.

The calibration/verification analysis was based on nearby measurement stations with observed stages. The stations have long-term measurements that are very suitable for extreme value analysis (in some cases back to the 1950’s). Figure 4.3 below shows an example on how the extrapolation of the stages has been conducted. For more details and for other models refer to the Hydraulics report (section hydraulic verification of individual model chapter).


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Figure 4.3 Observed versus modelled stages based on estimated return periods at Thurles gauging station (based on records from 1954-2015)

For the other AFAs, the models provided realistic flood levels for the different extreme events, i.e. for M1A, M2B, M4A, M5A-D. It is recommended to repeat the calibration/verification process in the next round of assessments with the new survey data.

4.2.3 Medium Priority Watercourse (MPW) modelling

The modelled rivers between the AFAs are based on limited river cross-sectional information. This resulted in less accurate modelling between the AFAs. The following limitations of the modelling should be addressed during the next round of the CFRAM:

� It is assumed that in some cases the cross-section of the river was schematized smaller than in reality. This means the channel can convey less flow, therefore more flow is in the flood plain and the extent is overestimated.

� The hydraulic calibration is based on the 2008 flood event with aerial photography. The approach here is similar in principle to the ungauged locations within an AFA. However, there is likely to be less usable information on known levels in known events, and hence the use of the term “calibration” in these areas would generally be misleading. Consideration of the question “is it believable?” for the size of the extent was most appropriate as a reality check.

� No 2D modelling has been completed for the floodplains. This can lead to less accurate results because of no realistic schematization of out of bank flow (hydraulic losses).

� There is an error in model M6C with one of the cross-section, that leads to a gap in the flood extent, see Figure 4.4 below.


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Figure 4.4 Flood extent at the junction of Anner River and Clashawley River, red circle indicated error in flood extent (missing cross-sectional data)

4.2.4 Missing structures in Models

A footbridge at Piltown downstream of the main street bridge is missing. During the December 2015 flood, the footbridge caused 10 cm afflux and therefore a 10cm higher water level upstream of the main bridge. The error is covered therefore by the applied blockage scenario, as this scenario was the baseline for Optioneering.

4.2.5 Blockage scenarios

The determination of the percentage of blockage was estimated. In many cases, this resulted in increased results for the damages. During the next round of assessments, this would need to be revisited.

4.2.6 Insufficient Hydraulic Data

For the majority of AFAs within the Suir catchment there is sufficient data available for conducting hydraulic modelling. However, the installation of additional gauges is highly recommended for the following AFAs: Borrisoleigh, Fethard and Newcastle, see Table 4-1.


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Table 4-1 Quality of hydraulic data

AFA Quality of Data

Borrisoleigh Limited gauge data is available on the Cromoge river, therefore only reasonable confidence exists in both the hydrology and hydraulics in the Borrisoleigh AFA. Future recording of this river is recommended.

Fethard A gauging station exists downstream of Fethard however, it stopped recording at the end of 2010. Rainfall gauging stations are located near Fethard. The available data is used to estimate the extreme values (flow and stage). Due to the limited data availability, there is only reasonable confidence in both the hydrology and hydraulics for Fethard AFA. It is recommended that the downstream gauge is reinstalled/ upgraded and continues recording flow and stage in this river.

Newcastle There are multiple gauging stations along the River Suir. Most of these gauges have long-term continuous records. The station located closest to the AFA provided observed flow and stage data to represent the hydrology and flood depths respectively. Due to the available long-term data, close estimates of the extreme values (flow and stage) could be assessed. Only limited data is available on the Glen River. The aerial photography from the 2008 event for the Main Suir provided evidence of the flood extents for the representative AEP. For this reason, there is good confidence in both the hydrology and hydraulics on the Suir. On the Glen River, a rather conservative approach was taken because of the low confidence in the hydrology and hydraulics. Future recording in the Glen River is recommended.

Mullinahone Installation of new gauge to gain a better understanding of hydrology in order to develop a robust and representative hydraulic model

4.2.7 Clonmel Hydraulic Model

The Suir CFRAM did not undertake any hydraulic modelling for the town of Clonmel as this was completed by the consultants Mott McDonald as part of the design for the flood relief scheme for the town.

The Suir CFRAM project team received a copy of the ISIS_1D hydraulic model along with three flood outlines in AutoCAD format. Three outlines received were for the 10% AEP Current Scenario, 1% AEP Current Scenario and 1% AEP & 20% Climate Change. A statistical analysis on the latter extent indicated that it was a very good approximation for the 0.1% AEP event. These AutoCAD layers were used to develop the flood extent maps and flood depth maps for this AFA.

The Suir CFRAM flood mapping for Clonmel has the following limitations: -

� The defended area mapping received from the consultants for the Clonmel Scheme was based on what was perceived at design stage with modifications to account for changes at construction stage. There was no defended model run completed for the scheme. It is recommended that at the next renewal stage a defended model run is undertaken.

� The flood outlines received were for the current scenario only, no MRFS or HEFS outlines were developed as part of the Clonmel Flood Relief Scheme.

� The hydraulic modelling for the flood relief scheme was completed using ISIS_1D software with inflows for the Suir tributaries of the Boulic, Frenchman, Whitening and Auk. There is a history of flooding on the Boulic (e.g. Clenconnor Cottages IG Ref: - 218627, 123444) and the fact that this watercourse has not been modelled is considered to be something that needs be addressed in any model revisions. This


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watercourse is heavily culverted and is considered by the Local Authority as part of the storm water drainage network. Hence, maintenance on this watercourse is by Irish Water. As part of the Suir CFRAMs an Integrated Catchment Model (ICM) was constructed, this model was not run, as there were concerns over the accuracy of some of the Boulic survey data supplied by Atkins. This data was captured as part of a storm water capacity study commissioned by Clonmel Borough Council. It is recommended that further studies would benefit if this model was completed and updated flood maps generated from the outputs.

� The LiDAR dataset used at design stage has been updated and for the next renewal cycle, it is recommended that the latest LiDAR be used.

� Manual correction was applied to the flood outline for the Semiton yard site (IG Ref: - 219400, 121600) following an infill survey completed by the Suir CFRAMs. The flood outline for two domestic dwellings (IG Ref: - 218170, 121220) was also manually corrected following the same infill/validation survey.

4.2.7.1 Waterford Hydraulic Model In 2014, a flood alleviation scheme was completed in Waterford City that consisted of the construction of flood defences on John’s River, Lisduggan Stream and the Suir River within the urban area of the city. The scheme also included the raising of the Tramore Road that had been subjected to past flooding. The scheme design was completed by the consultants RPS (Cork), with Waterford City and County Council (i.e. WCCC) as the client. Funding for the scheme was provided by the Office of Public Works and WCCC.

As part of the Suir CFRAMs, the development of the flood maps for this section of the Suir was sub-contracted to RPS (Belfast). For the city of Waterford, the flood extents that had been generated as part of the scheme were used for the flood extent and flood depth maps. For the scheme, only two flood extents were generated and these were (a) 1% AEP Fluvial with a 0.5%AEP tidal boundary and (b) 0.1% AEP Fluvial with a 0.1%AEP tidal boundary. In this regard, the maps for the city differ from the type of maps that were generated nationally as part of the CFRAM process.

Following public consultation of the Suir flood maps, only one objection was received and this related to a site within Waterford City. The basis of the objection is that since the flood maps were generated the site has been developed which included raising of the ground level. This objection is currently being examined.

It is recommended that in any model / mapping update for the city that the hydraulic model that was partially constructed by the Suir project team is completed using the survey data captured as part of the study. This model can be used to develop flood maps with the other AEPs that have been used nationally.


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4.3 Preliminary Options & Plan Recommendations

4.3.1 Relevant information for AFAs with low flood risk

As discussed in Section 2.5, for certain AFAs, currently a low level of flood risk from rivers exists. In such cases, the development of flood risk management measures aimed specifically at managing the risk in such AFAs has not been pursued. In UoM16, the level of risk has been determined as being low in nine AFAs.

The level of risk in the AFAs where the CFRAM process has determined that there is currently a low level of flood risk will be reviewed, along with all areas, as part of the review of the PFRA in the next round of the CFRAM.

4.3.2 Other Areas outside the CFRAM AFA’s

During the public consultation days, a number of areas outside the AFAs were highlighted as at risk of flooding. The following areas were highlighted:

� Fanningstown, Co.Kilkenny,

� Ballycamus, Co. Tipperary,

� Mooncoin, Co. Kilkenny,

� Laganstown and Thomastown Cross near Golden, Co. Tipperary,

� Grange near Knocklofty, Co. Tipperary

In general, flooding at these locations is from either pluvial or from groundwater. These sources of flooding were not addressed in this cycle of the CFRAM. It is a recommendation of the Suir CFRAM study that these sources of flooding are examined in the next round of the PFRA.

4.3.3 Additional AFAs Identified during SE CFRAM Flood Risk Review

The AFAs in the Suir were determined prior to the Preliminary Flood Risk Assessment Process (PFRA). The Flood Risk Review undertaken as part of the South Eastern CFRAMs included a number of possible Suir AFAs. This Flood Risk Review recommended the inclusion of both Galbally and Hollyford as AFAs. It is recommended that any review of the PFRA should review these two areas and determine if they should be included in any future updates to the Suir CFRAMs

4.3.4 MCA Process

A Multi-Criteria Assessment (MCA) is used as part of the process for assessing potential options for reducing or managing flood risk for each AFA. This MCA process assigns a score for each option that relates to how effective that option is in terms of achieving set goals under a set of objectives.

In order to take account of the relative importance of some objectives in comparison with other objectives, each sub-objective is given a Global Weighting. Following a public consultation process and analysis by UCD, these global weightings were set at a national level and are uniform across all of the CFRAM Studies.

In order to take cognisance of the local perspective on the relative importance of objectives, each sub objective is also given a local weighting. Local weightings vary from 0 for not locally important to 5 for very important locally.

A number of observations was raised in relation to the MCA process through the course of the Suir CFRAM study as detailed below:

� Local Weighting and Option Scoring subject to a maximum score of 5. In some cases, it was felt that this score could be higher to reflect an objectives importance


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� A strong bias towards environmental objectives particularly in relation to agriculture and health and safety,

� Social Importance to Industry not taken into account (e.g. Bridge Replacement at Piltown). There was no objective for scoring this measure in the MCA process.

4.3.5 Natural Flood Management Measures

All of the measures proposed for the Suir CFRAM study have focussed on structural measures.

Non-structural measures such as Land Use Management and Natural Flood Risk Management Measures, etc. are terms used to cover a suite of measures that are intended to reduce flood risk by working with natural systems and, where possible, provide environmental benefits. While in small catchments they can effectively manage flood risk to a certain degree in their own right, in larger catchments they can work in a complimentary way with other measures to achieve flood risk management targets.

Due to the time required to initiate, establish and prove the flood risk management targets of such measures, they are not deemed viable to mitigate the current flood risk.

During the public consultation days and stakeholder meetings, there was a strong appetite for natural flood management measures. In the next cycle of the CFRAM, these measures should be explored further. A number of catchment-scale natural flood management pilot studies could be progressed with the objective of informing future CFRAM studies.

4.3.6 Unit Cost Database

Ideally, costing would be undertaken through a robust review of previous OPW schemes. Unfortunately, data sources from past OPW schemes are statistically limited. They are not recorded in a way that specific asset or flood risk mitigation method costs can be extracted to enable past scheme costs to be used for the future. As a result, 'bottom-up' pricing was the preferred option for this study.

� The preferred approach of generating a series of ‘typical’ engineering elements for each measure and varying these costs by modifying key elements or by scaling and weighting elements does not always give an accurate representation of local material and operational costs.

� The risk involved when using outrun costs from existing projects collated within available unit cost reports is that these outrun costs do not necessarily reflect the costs associated with schemes constructed in Ireland. The applicability of costing databases derived using UK data in Ireland may significantly under-predict costs.

� The rates used represented a ‘sunny day’ scenario and in no way try to cover all possible risks or unseen eventualities. For this reason, all possible risks need to be taken into account as part of the assessment and allowances made for these as part of the method factor or optimism bias.

� Rates used did not allow for regional variations nor allow for site-specific conditions. on insufficient data available to

� Health and safety aspects assumed a competent contractor, but site-specific risks were considered.

4.4 Strategic Environmental Report Recommendations The Plan took into account available flood risk data up to 2011/2012 and to a lesser extent more recent historical flooding in 2014 and 2015. The Plan, SEA ER and SEA Statement includes the most recently available information on flooding and takes account of feedback received from the consultation process.


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A point to note from public consultation and submissions is that the River Nore and Barrow were designated as SPAs for Kingfisher because they were surveyed especially for breeding Kingfishers in 2010. The River Suir was not surveyed as part of the study. The River Suir has a healthy population of breeding Kingfishers and may be designated as a SPA by the time a scheme commences.

The NIS provides clear, precise and definitive reasoning as to how best practice protocols and Standard Operating Procedures will avoid adverse effects of ‘working in-channel’.


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5 HEALTH AND SAFETY

5.1 Project Supervisor Design Process Unlike the other national CFRAMs studies, this study was undertaken in-house with OPW having the duties of Project Supervisor Design Stage (i.e. PSDS). All Health and Safety Documentation associated with the study have been saved at T:\Engineers\FRAM\00 - Projects\1891 - Suir CFRAM\03-H&S.

A preliminary Health and Safety Plan (i.e. 1891_TECH_060614_Preliminary Health & Safety Plan.doc) and Information for the PSDS (i.e. 891_PP03-F2 REV1 PSDP Info.doc) are saved in this folder. Study Hazard and Risk assessments are also saved in this folder.

5.2 Health and Safety – Channel Surveys Health and safety documents for the Channel and Structure Cross Sectional Survey (CSCSS) for both Maltby Surveys and Murphy’s Surveys are saved at T:\Engineers\FRAM\00 - Projects\1891 - Suir CFRAM\03-H&S. Among the possible health and safety issues identified in the hazard and risk assessments was the possibility of disturbance of the bental toxic muds at the Tannery weir in Clonmel. This risk did not arise as no new surveys were undertaken along this reach of the Suir and the model that had been developed as part the Clonmel Flood Relief Scheme was used in the study.

One reportable incident did occur during the surveys where a surveyor lost part of his finger top when it was caught in the tribrach of a survey tripod that he was carrying at the time. Incident occurred on the 15th Oct 2007 and was duly reported to the Health and Safety Authority (copy of the report is saved at T:\Engineers\FRAM\00 - Projects\1891 - Suir CFRAM\03-H&S\Maltby Survey\Report to HSA.htm). Subsequently all future hazard and risk assessments where updated with the requirement that when carrying survey tripods that the legs were to be close and secured together with the attached straps. No other reportable incidents occurred during these surveys.

5.3 Health and Safety – Defence Asset Survey Health and safety documents for the Defence Asset Survey are saved at T:\Engineers\FRAM\00 - Projects\1891 - Suir CFRAM\03-H&S\Flood Defence Survey. Haskoning undertook this work. No reportable incidents occurred during this survey nor were any new or unforeseen risk reported.

5.4 Health and Safety – Site Visits During the course of the study, members of the study team were required to undertake site visits. Prior to any such visit, a hazard and risk assessment was completed. These assessments were completed in accordance with the FRAM Section’s procedures and are saved at T:\Engineers\FRAM\00 - Projects\1891 - Suir CFRAM\03-H&S\Site Visits

5.5 Health and Safety Considerations in Option Selection As part of the Multi Criteria Analysis (MCA) used to assist in the identification of the preferred flood risk management option, the Health and Safety risk associated with the construction and operation of the option was assessed as detailed in Table 5-1 below:


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Table 5-1 Calculation of Health and Safety in the MCA process (Guidance Note No.28)

Objective 4B of the MCA

Objective Minimise health and safety risk in construction, maintenance and operation of the flood risk management option

Indicator Degree of health and safety risk during construction, maintenance and operation

Scoring By professional judgement, taking into account the guidance and criteria set out below, with review of candidate preferred options by PSDP

Basic Requirement Moderate to high, but acceptable and manageable, level of health and safety risk during construction, maintenance or operation

Aspirational Target Negligible risk to health and safety during construction, maintenance or operation

Global Weighting 20

Local Weighting Constant and equal to 5, i.e., no amendment to local weighting

Guidance on Assignment of Local Weightings

The Local Weighting to be applied for this objective is constant, and should always be set equal to 5, as it always a consideration in option design and selection.

Guidance on Scoring

Scoring is to be by professional judgement, taking into account the guidance and criteria set out below.

The indicative score under this objective should be set at five, and then have a point deducted for each specific risk (as defined under the Safety, Health and Welfare at work (Construction) Regulations) likely to be encountered in a) construction and then again in b) operation and maintenance.

As an example, a measure requiring deep excavation and working near water during construction, and then working near water during operation / maintenance, would have a score of 2 (5 – 2 (construction stage) – 1 (operation / maintenance stage) = 3).

Professional judgement needs then to be applied to take into account any locally or context-specific issues, e.g., specific hazards, or a potentially higher risk for construction in an urban environment.

The PSDP (or person assigned the duties of PSDP where a company is nominated as PSDP) should review the scoring afforded to the preferred option(s) and other options that would be realistically in contention to be adopted as a preferred option based on other objectives, to ensure that the scoring is appropriate and reasonable.

Note: It should be assumed in assigning scores that good construction health and safety practices will be implemented.


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5.6 Health and Safety Consideration of AFA Preferred Option In UOM 16, the health and safety considerations specific to each of the ten AFAs are detailed in Sections 5.6.1 to 5.6.10.

All these risks can be avoided or mitigated through the implementation of robust design at detail design stage, good construction practice and site management and through the development of safe operational and maintenance procedures. It is also importance that any persons who are required to design, construction operate or maintain any flood defence item are competent to do so.

As many of the works are in public areas and alongside public roads, public safety and traffic management will also need to be considered.

5.6.1 Ardfinnan

The preferred flood risk management option for Ardfinnan consists of: -

� The construction of new flood retaining walls and embankments,

� Raising of section of a public road,

� Installation of penstocks.

During the public consultation days, a number of health and safety issues were identified at Ardfinnan:

� Bridge in Ardfinnan was reported to be structural unsound by a number of individuals,

� Weir breach,

� Slipway to river is reportedly unsafe and in need of rehabilitation.

The risk of drowning is envisaged as a possible health and safety risk as some of the work will require construction along the river edge. Engulfment in deep excavation and falling from a height are also possible risks. In addition, this option requires the installation of sheet piles.

5.6.2 Borrisoleigh

The preferred flood risk management option for Borrisoleigh (River Cromoge and tributary) consists of: -

� Improvement of channel conveyance, (lowering bed levels),

� Channel Widening,

� Channel dredging and widening on a flashy river channel,

� Replacement of an existing bridge and culvert,

� Road Raising,

� Construction of flood retaining walls (1.2m high) and embankments (1m high).

The risk of drowning is envisaged as a possible health and safety risk as some of the work will require construction along the edge of the river Cromoge, which is a flashy mountain river with fast and sudden flows. Engulfment in deep excavation and falling from a height are also risks that need to be considered.


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5.6.3 Cahir

The preferred flood risk management option in this large urban AFA consists of: -

� Construction of flood retaining walls along the Suir and flood embankments along a small tributary,

� Construction of a penstock sluice gate,

� Upgrading an existing weir.

The risk of drowning is envisaged as a possible health and safety risk as some of the work will require construction along the river edge. It is envisaged that construction works will require deep excavations so the risk of engulfment needs to be addressed by adherence to the health and safety guidance for excavations and confined spaces. Falling from a height is also a possible risk. These works are to be undertaken in a large urban area, so due care to the general public and proper traffic management need to be adhered to. At this location in the mid catchment, the Suir can have significant flows so this risk needs to be addressed.

5.6.4 Fethard

The preferred flood risk management option for the AFA of Fethard consists of: -

� Construction of flood walls and embankments,

� Upgrading of some existing defences.

The risk of drowning is envisaged as a possible health and safety risk as some of the work will require construction along the river edge and in the channel. This option requires in-channel works. It is envisaged that the construction works will require some excavation so the risk of engulfment would need to be addressed by adherence to the best health and safety guidance for excavations and confined spaces. Falling from a height is also a possible risk.

5.6.5 Golden

It is proposed to protect the at-risk properties in Golden with a series of floodwalls, embankments and one demountable barrier. Most of the proposed embankments will be located some distance from the river edge while the walls will be close to the edge of a public road.

The risk of drowning is envisaged as a possible health and safety risk as some of the work will require construction along the river edge. It is envisaged that the construction works will require some excavation so the risk of engulfment would need to be addressed by adherence to the health and safety guidance for excavations and confined spaces. Falling from a height is also a possible risk. Traffic management will also need to be considered.

5.6.6 Holycross

In this AFA, the at risk properties would be protected by upgrading of existing walls and construction of new embankments. The options also include the installation of one floodgate.

The risk of drowning is envisaged as a possible health and safety risk as some of the work will require construction along the river edge. It is envisaged that the construction works will require some excavation so the risk of engulfment would need to be addressed by adherence to the health and safety guidance for excavations and confined spaces. Falling from a height is also a possible risk. Traffic management will also need to be considered as a school and a tourist attraction (abbey) are close to the site. Negligible operational risk with potential substantial maintenance requirements due to floodgates.


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5.6.7 Knocklofty

In the Knocklofty AFA, the at risk properties would be protected by two new embankments with an average height of 1.4m and would be connected to the existing wall. The embankment would have an average height of 1.2 (varying from 0.5 to 2.0m)

The risk of drowning is envisaged as a possible health and safety risk as some of the work will require construction along the river edge. Most of the construction work will be located in agricultural land close to a large farm. Care would need to be taken due to the likely presence of farm machinery and animals. Anglers also use this site so consideration needs to be given to public safety. This option will require the transportation of large volumes of excavated material and hence movement of vehicles on both the site and the nearby public road should be given consideration. Low risk with regular monitoring and maintenance due to the floodgate.

5.6.8 Newcastle

The at risk properties in Newcastle would be protected through the improvement of channel conveyance by under-pinning walls and lowering of bed levels to a maximum depth of 0.75m. Lowering of bed levels on the side channel north of Newcastle would also be required to protect properties.

The risk of drowning is envisaged as a possible health and safety risk as some of the work will require construction along the river that is considered a flashy river. Work would involve bridge replacement and underpinning of walls so the risk of collapse, engulfment and falling objects need to be addressed by adherence to the best health and safety guidance. Negligible operational risk with regular monitoring /maintenance.

5.6.9 Piltown

In the Piltown AFA, it is proposed to address the flood risk through the construction of retaining walls and embankments, improved channel conveyance consisting of dredging, culvert and bridge replacement and road raising.

The risk of drowning is envisaged as a possible health and safety risk as some of the work will require construction along the river edge. It is envisaged that the construction works will require some excavation so the risk of engulfment would need to be addressed by adherence to the health and safety guidance for excavations and confined spaces. Falling from a height is also a possible risk. Traffic management will need to be considered. As this section of the Pil river is tidally influence this would also need to be considered. Negligible operational risk with regular monitoring /maintenance.

5.6.10 Thurles

In the Thurles AFA, it is proposed to protect the at risk properties by the construction of a series of embankments and floodwalls.

The risk of drowning is envisaged as a possible health and safety risk as some of the work will require construction along the river edge. It is envisaged that the construction works will require deep excavation so the risk of engulfment would need to be addressed by adherence to the health and safety guidance for excavations and confined spaces. Falling from a height is also a possible risk. These works are to be undertaken in a large urban area, so due care to the general public and proper traffic management need to be adhered to.


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6 CONSULTATION

6.1 Summary of Public, Stakeholders and Statutory Consultation Engagement

6.1.1 Consultation on the Mapping

Consultation on the draft flood maps were conducted through Public Consultation Days (PCDs), a local authority workshop and a national consultation process.

A workshop between the OPW and the local authorities within the Suir was held prior to the PCDs. The Mapping PCDs in UoM16 were held in ten AFAs between February and April 2015. The attendance at these PCDs was 114. National consultation on the mapping occurred from 20th November to 23rd December in 2015.

6.1.1.1 Feedback from the Consultation Feedback from the PCDs and local authorities were collated. This feedback was divided into three categories – technical, policy and optioneering. A breakdown of the statistics are as follows:

� 261 items of feedback were received. A single feedback item could have multiple sub items.

o The majority (160) of the comments were received during the PCDs,

o The Local Authority workshop prior to the PCDs generated 84 items of feedback,

o The majority of the feedback items were technical (206), followed by optioneering type items (48) and policy items (7),

o A small number of submissions were received on the Suir mapping. One objection was received on the maps in the Waterford AFA. This was based on ground levels on a site being raised after the survey was completed.

Overall, the flood extent maps are largely representative of previously experienced flood magnitudes. Due to the high volume of hydraulic model and flood extent map comments received, it is not possible to discuss all comments on an individual basis, although they can be referred to within an electronic master spreadsheet. Many of the technical comments resulted in a review of the maps or the model.

A summary of the feedback received during consultation on the flood mapping are available at T:\Engineers\FRAM\00 - Projects\1891 - Suir CFRAM\08-COMM\00-PCD\00-Mapping PCD\Collated_Feedback\1891_Tech_150609_DFMaps_Feedback_Collated_Populated.

6.1.2 Consultation on the Options

The Options PCDs in UoM16 were held in six AFAs in July 2016. The attendance at these PCDs was 76. A summary of the comments received during the public consultation on the options are available at T:\Engineers\FRAM\00 - Projects\1891 - Suir CFRAM\08-COMM\00-PCD\01-Options PCDs\RPS Stakeholder Consultation Report.

A number of observations were raised during the Options stage of the consultations. The following sections detail the key changes after consultation.

6.1.2.1 Golden AFA � One resident requested to move the proposed embankments, closer to the river, in

order to facilitate a lawn/garden in the aforementioned area.


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� Concerns were raised regarding the effectiveness of the proposed option. The locals suggested that the main problem was underground water. The proposed embankments in Option 1 did not include sheet piling.

OPW increased the length of the aforementioned embankment in order to facilitate a lawn/garden. In order to cover the risk of underground water flowing from the main Suir to the residential areas, OPW included 5m sheet pilling to all the original embankments. OPW updated the cost / BCR for this Option.

6.1.2.2 Cahir AFA One resident requested the proposed flood defence wall to be located further back along the existing wall (to the northeast) at Supervalu. OPW changed the length of the floodwall and updated the cost / BCR for the Options.

6.1.2.3 Fethard AFA � One resident stated that the weir in the channel is in fact an old sewer pipe.

� The ballroom has been flooded up to 10cm during December floods. This is not shown on OPW maps.

OPW updated & included this information regarding the sewerage pipe in the Preliminary Option Report. In terms of the Ballroom, while the aforementioned property has been included in the damages assessment spreadsheet it was not possible to model the flood mechanism that may have caused the property to flood.

6.1.3 PCDs on the draft Plan

PCDs on the Draft Plan were held in two locations in Tipperary (Cahir and Thurles) and one location in both Kilkenny (Kilkenny City) and Waterford (Dungarvan). The PCDs in Kilkenny and Waterford were combined with PCDs for the South Eastern CFRAMs. The attendance at both Cahir and Thurles was 44. A summary of the comments received during the public consultation on the options are available at T:\Engineers\FRAM\00 - Projects\1891 - Suir CFRAM\08-COMM\00-PCD\01-Options PCDs\RPS Stakeholder Consultation Report.

A number of observations were raised during the plan stage of the consultations. The following list a number of the key changes after public consultation.

6.1.3.1 Fethard AFA The Chairperson of Birdwatch Ireland advised that there has been a recent judgement from the European Commission (Commission V Ireland C418/04 July 2015) which has identified that Ireland has not fulfilled its obligation to designate SPAs in some instances. Advised that when the NPWS were designating SPAs they only surveyed the Nore and the Barrow for Annex I species and therefore they were designated as SPAs. However, the Suir was not surveyed at this time. Therefore, the presence of the Kingfisher was not identified along this river even though it is an Annex I species.

6.1.4 Statutory Consultation on the draft Plan

Statutory consultation on the Suir draft Plan commenced the 4th October 2016 and concluded on the 13th December 2016 for the public and the 13th January 2017 for local authority submissions. Thirty submissions were received on the Suir Plan. The following summarises the submissions received:

� 44 % of these were technical,

� 31% of these were environmental,

� 18% were policy related,

� 6% were non-OPW related.


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46% of the submissions were related to AFAs, with most of the submissions in relation to Fethard and Piltown AFAs.

Due to the number of comments and sub comments received, it is not possible to discuss all on an individual basis, although they can be referred to within an electronic master spreadsheet.

A summary of the feedback received during consultation on the flood mapping are available at T:\Engineers\FRAM\00 - Projects\1891 - Suir CFRAM\Plan Submissions.

6.1.5 Final Plan

The final Plan for the Suir was completed and issued to PER on 18th August 2017.

6.1.6 Stakeholder Feedback

A number of stakeholder meetings were held during the course of the South East CFRAM which included the Suir CFRAM.

Tipperary County Council (CoCo) suggested that the Nire catchment would be a good area to pilot land use management for future studies due to the presence of flow records and the flashy nature of the river.

They also noted that the modelling of the mid-range and high-end future scenarios would provide beneficial input into their Climate Change Adaptability Strategy Plans.


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7 OUTCOMES AND NEXT STEPS

7.1 Summary of measures by UoM/AFA No measures were identified at Sub-Catchment scale however, the following AFA specific measures were identified under the Suir CFRAM study:

� Ardfinnan Flood Relief Scheme – Flood Defences,

� Borrisoleigh Flood Relief Scheme – Flood Defences & Improvement of Channel Conveyance,

� Cahir Flood Relief Scheme – Flood Defences, Improvement of Channel Conveyance & Other Works,

� Fethard Flood Relief Scheme - Flood Defences Golden Flood Relief Scheme – Flood Defences

� Holycross Flood Relief Scheme – Flood Defences and Improvement of Channel Conveyance

� Knocklofty Flood Relief Scheme – Flood Defences

� Newcastle - Improvement of Channel Conveyance

� Piltown Flood Relief Scheme - Flood Defences & Improvement of Channel Conveyance (Bridge Replacement)

� Thurles Flood Relief Scheme - Flood Defences Next Cycle of the CFRAM

This section deals with the discussion of technical methodology and areas for potential revision in the second cycle.

7.1.1 Flood Risk Management in Other Areas

The Plan is focussed on the AFAs identified through the Preliminary Flood Risk Assessment (PFRA). While some measures set out herein represent the implementation of wider government policies that should be applied in all locations, the Plan does not specifically address the management of local flood problems outside of the AFAs.

While it is considered that the PFRA identified the areas of significant flood risk throughout Ireland, the PFRA will be reviewed by the end of 2018, and other areas can be considered for detailed assessment at that stage. It is suggested that both Hollyford and Galbally are included in this review to investigate if flood risk in these locations warrant their inclusion as AFAs in the next cycle of the Suir CFRAMs.

This cycle of the Plan does not addressed a number of areas in UoM16 that are affected by other sources of flooding such as pluvial and groundwater. These sources of flooding should be looked at in more detail in the next cycle.

7.1.2 Natural Flood Risk Management Measures

The CFRAM process is biased towards structural measures in the provision of the design standard of protection. Natural Flood Risk Management (NFRM) measures should be explored in more detail in future studies.

There is a lack of robust quantifiable data to accurately perform critical analysis such as the MCA process outlined in this study for such measures. There are however case studies where examples of these measures have been incorporated for the purpose of flood alleviation management. Some of these case studies include:

7.1.2.1 Case Study: Restoration of Durrow Floodplain Alluvial Woodland NWRM Implemented: Overland flow areas in peatland forests


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This site was one of nine included in the LIFE05 project to restore priority woodland habitats in Ireland. The Durrow site is located on the floodplain of the river Erkina, and had been affected by planting of non-native conifers and associated drainage. A network of shallow drainage ditches covered the entire site, and was found to be adversely affecting the native alluvial woodland by reducing retention time of floodwaters on the floodplain. To counter this, a total of 350 dams were installed on ditches across the site

7.1.2.2 Case Study: River Tolka Constructed Wetlands and Enhancements NWRM Implemented: Wetland restoration & management, Urban forest parks, Natural bank stabilisation and Basins & ponds

The River Tolka runs through Dublin, Ireland. A series of measures was applied to the urban sections of the river to slow flood flows, reduce pollution and support wildlife. These included the establishment of retention ponds to manage runoff storage; bank engineering to slow flows and prevent erosion; and planting trees along the river to slow runoff. Two phases of retention pond construction have been carried out, the latter as part of a wider ‘Greenway’ project to develop a green corridor with cycling route.

7.1.2.3 Case Study: Restoring the River Quaggy NWRM Implemented: Floodplain restoration and management

River restoration and flood management measures were implemented on the River Quaggy in London. The measures were necessary due to increasing urban development in the river valley and natural flood plain, with an associated increase in fluvial flooding. A suite of measures was implemented between 1990 and 2005, including de-culverting a reach of river and creating associated floodplain; building a detention basin; set-back flood defences; channel re-profiling. This scheme took a catchment-scale view in order to develop the best solution, and worked with a multi-disciplinary team as well as having extensive community involvement.

Based on these examples, it is recommended that a number of similar measures could be incorporated into catchments such as the Suir.

7.1.3 Technical Methodology

In some AFAs, there was insufficient information to provide high confidence in the analysis of flood risk and this can only be redressed by further collecting of data as and when events occur. However, the best use of available data was made so that in most cases recommendations could be made to progress flood risk management measures without recourse to further study.

7.1.4 Flood Defences

In relation to the status of defences, a significant issue arose in determining whether defences were effective or ineffective. In some cases, the information required to establish effectiveness was not available, and there is a liability issue with assuming effectiveness for a structure where no such information is available. The scope of the CFRAM study did not extend to the level of detail required to determine effectiveness, in terms of site investigation or structural assessment. The CFRAM only undertook visual condition and geometric surveys of formal effective flood defences. Hence, such structures were omitted from the models. While this is a conservative approach from the OPW perspective by avoiding the indication of areas as “protected” when, in fact, the structural performance cannot be confirmed, it may pose difficulties for property owners and other stakeholders within these areas which are indicated to have no protection. In order to address this further assessment of the defence performance and a policy review regarding the mapping of such areas would need to be carried out, possibly accompanied by provision of relevant information to the insurance industry via the Memorandum of Understanding.


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7.1.5 Communication

The longevity of the studies posed difficulties in terms of achieving and maintaining engagement with stakeholders and the wider public. The quality, rather than quantity, of consultation events remains the focus of future consultation phases, that the publicising the events is given a high priority going forward with engagement of national groups under an overall communications strategy, opportunities to tap into similar local engagement programmes are utilised (for example WFD engagement), and, that information be made available using flexible electronic visualisation applications as well as hard copy deliverables.

The South Eastern/Suir CFRAM study’s integrated Progress/Steering Group engaged well throughout the study, perhaps benefiting from personnel who were involved together in previous catchment scale flood risk management studies and also some Local Authorities who had staff dedicated to flood management duties. The resource demands that a study of this nature put on Local Authority partners is acknowledged.


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8 CONCLUSIONS

The Suir CFRAM was one of four pilot studies on the national approach to flood risk management undertaken by OPW. It was a significant and challenging project in terms of the detailed analysis it required, which was provided in-house.

The level of ambition to undertake catchment scale studies of this nature created a significant resource demand on the OPW, including the organisations represented on project progress, steering and stakeholder groups. This significant resource demand, caused a programme delay, of over one year, which meant that the final consultation deliverables (draft Plan and accompanying documentation) were prepared in 2016, rather than 2015 as originally programmed.

Throughout the process, there was a degree of conflict between maintaining a strategic and plan level of detail, to develop a catchment-scale plan, and the need to address the often very localised issues and nuances to particular flooding problems. In all relevant cases, it should be recognised that the subsequent analysis for progressing detailed design will involve some degree of remodelling to account for site investigations, service details, land owner requirements, and consequently this type of study provides “line and level” solutions with variations and refinements to be realistically expected in subsequent stages.

The CFRAM studies in this first cycle were ambitious and whilst they had been informed by pilot studies, there were areas where the methodology was untested at a CFRAM study scale that led to some delays and iteration throughout the process. The methodology and scope for the second cycle should be developed as soon as possible to enable pilot studies and trials to be undertaken and a realistic programme to be developed. This should enable more efficient working in the next cycle.


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9 REFERENCES & BIBLIOGRAPHY

1. EC Directive on the Assessment and Management of Flood Risks (2007/60/EC).

2. S.I. No. 122/2010 - European Communities (Assessment and Management of Flood Risks) Regulations 2010.

3. S.I. No. 495/2015 - European Communities (Assessment and Management of Flood Risks) (Amendment) Regulations 2015.

4. National Flood Risk Assessment and Management Programme, Catchment-based Flood Risk Assessment and Management (CFRAM) Studies, Stage I Tender Documents: Project Brief, Office of Public Works, 2010.


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APPENDICES