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Flood Risk Assessment
Kevin Treanor & Ciara Leonard, August
2026
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COYLE ENVIRONMENTAL LTD.
Flood Risk Assessment Report
for Kevin Treanor and Ciara Leonard at
Feebaghbane, Scotstown, County Monaghan.
1st & 2nd Floor Kilmurry House, Main Street,
Castlerea, Co. Roscommon, F45 DK58
Tel: 094 962 1258 Website: www.coyleenv.ie RECEIVED: 08/09/2026
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About Coyle Environmental Ltd.
Coyle Environmental Ltd are a highly respected and progressive
Environmental Monitoring & Consulting practice.
For over two decades, Coyle Environmental Ltd has
been a trusted provider of professional
Environmental Monitoring and Consulting Services
throughout Ireland.
Our reputation is built on innovative work practices,
cost-effective solutions, and unwavering client
dedication.
Operating nationwide from our base in the West of
Ireland we pride ourselves on delivering consistently
high-quality services, ensuring that projects are
completed on time and within budget. Our
commitment to Continuous Professional
Development (CPD) and investment in the latest
technology keeps us at the forefront of the industry.
We deliver to our valued clients a consistently
excellent quality of service.
We offer a specialist range of services
comprising:
• Environmental Monitoring
• Environmental Consulting
• Environmental Project Management
Coyle Environmental Ltds ability to provide a cost-
efficient professional service coupled with a proven
track record on project completion and delivery
ensures that we remain an industry leader in our
areas of expertise.
Our progressive and innovative work practices,
together with our commitment to CPD (Continuous
Professional Development) ensure that our
workforce are consistently upgrading their
professional skills and that the company is
constantly investing in the most recent technology
and equipment.
RECEIVED: 08/09/2026
Tel: 094 962 1258 Web: www.coyleenv.ie iii
Natura Impact Statement
Kevin Treanor & Ciara Leonard,
August 2026
Document Production & Approval
Name Date Position
Prepared by: Martin Jancek 19/08/2026 Flood Risk Engineer
Approved by: Emma Yore 19/08/2026 Environmental
Consultant
Revision History
Rev Status Date
0 Draft 19/08/2026
1 Final 28/08/2026
Coyle Environmental Limited disclaims any responsibility to the Client and others in respect of any matters outside
the scope of the report. The report has been prepared with reasonable skill, care and diligence within the terms of
the Contract with the client. The report is confidential to the Client and Coyle Environmental Limited accepts no
responsibility of whatsoever nature to third parties to whom this report or any part thereof is made known. Any such
party relies upon the report at their own risk.
Document Control
Project Title: Flood Risk Assessment Report for Kevin Treanor and Ciara Leonard at
Feebaghbane, Scotstown, County Monaghan.
Project Reference No: 26-136
Project Description: Flood Risk Assessment Report for Proposed Residential Development at
Feebaghbane, Scotstown, County Monaghan.
Status: FINAL
Client Details: Kevin Treanor and Ciara Leonard
Issued By: Coyle Environmental Ltd., 1st & 2nd Floor Kilmurry House, Castlerea, Co.
Roscommon RECEIVED: 08/09/2026
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2026
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1. INTRODUCTION 1
2. METHODOLOGY 1
2.1. Introduction 1
2.2. Definition of Flood Risk 1
2.3. Likelihood of Flooding 2
2.4. Climate Scenarios 2
2.5. Definition of Flood Zones 3
2.6. Objectives and Principles of the Planning Guidelines 5
2.7. The Sequential Approach and Justification Test 5
3. STUDY AREA 7
4. STAGE 1 – FLOOD RISK IDENTIFICATION 11
4.1. General 11
4.2. Information Sources Consulted 11
5. STAGE 2 – INITIAL FLOOD RISK ASSESSMENT 19
5.1. General 19
5.2. Sources of Flooding 19
5.3. Conclusion of Stage 2 FRA 21
6. STAGE 3 – DETAILED FLOOD RISK ASSESSMENT 21
6.1. Conclusion of Stage 3 FRA 21
7. CONCLUSIONS 22
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FIGURES
Figure 1. Source-Pathway-Receptor Model ..................................................................................................... 1
Figure 2. OPW The Planning System and Flood Risk Management, Classification of vulnerability of different
types of development ....................................................................................................................................... 4
Figure 3.Sequential Approaches (Source: The Planning System and Flood Risk Management) ................... 6
Figure 4. Site Location (Google Maps) ............................................................................................................ 7
Figure 5. Site Layout and Extent of Proposed Works .................................................................................... 10
Figure 6. OPW Community-Scale Flood Extent – All Probabilities Present Day Scenario. .......................... 12
Figure 7. OPW Community-Scale Flood Extent – Mid-Range Future Scenario – All Probabilities ............... 13
Figure 8. OPW Community-Scale Flood Extent – High-End Future Scenario – All Probabilities .................. 13
Figure 9. OPW Community-Scale Pluvial Flood Extent – All Probabilities .................................................... 14
Figure 10. National Indicative Fluvial Mapping – Present Day Scenario, Low and Medium Probability. ...... 15
Figure 11. National Indicative Fluvial Mapping – Mid-Range Future Scenario, Low and Medium Probability.15
Figure 12. National Indicative Fluvial Mapping – High-End Future Scenario, Low and Medium Probability. 16
Figure 13. Arterial Drainage Scheme (ADS) .................................................................................................. 17
Figure 14. Past Flood Events ......................................................................................................................... 18
Figure 15. Groundwater Flood Events ........................................................................................................... 18
Figure 16. Flood level as per NIFM-HEFS - 88.10 mOD. .............................................................................. 20
TABLES
Table 1. Correlation between return period and AEP ...................................................................................... 2
Table 2. Matrix of vulnerability versus flood zone to illustrate appropriate development and that required to
meet the Justification Test (Source: The Planning System and Flood Risk Management) ............................. 6
Table 3. Information Sources Consulted ........................................................................................................ 11
RECEIVED: 08/09/2026
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1. INTRODUCTION
Coyle Environmental Ltd. has been engaged to carry out a Flood Risk Assessment for a proposed
Residential Development by Kevin Treanor and Ciara Leonard at Feebaghbane, Scotstown, County
Monaghan.
This report has been prepared to assess the existing flood risk to the site.
2. METHODOLOGY
2.1. Introduction
This report has been prepared in accordance with ‘The Planning System and Flood Risk Management
Guidelines for Planning Authorities’ herein referred to as ‘The Guidelines’ as published by the Office of
Public Works (OPW) and Department of Environment, Heritage and Local Government (DoHLG) in
2009.
2.2. Definition of Flood Risk
Flood risk is a combination of the likelihood of a flood event occurring and the potential consequences
arising from that flood event and is then normally expressed in terms of the following relationship:
Flood risk = Likelihood of flooding x Consequences of flooding.
To fully assess flood, risk an understanding of where the water comes from (i.e. the source), how and
where it flows (i.e. the pathways) and the people and assets affected by it (i.e. the receptors) is required.
Figure 1 below shows a source-pathway-receptor model.
Figure 1. Source-Pathway-Receptor Model
The principal sources of flooding are rainfall or higher than normal sea levels. The principal pathways
are rivers, drains, sewers, overland flow and river and coastal floodplains. The receptors can include
people, their property and the environment. All three elements as well as the vulnerability and exposure
of receptors must be examined to determine the potential consequences.
The guidelines set out a staged approach to the assessment of flood risk with each stage carried out
only as needed. The stages are listed below:
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Stage I Flood Risk Identification – to identify whether there may be any flooding or surface water
management issues.
Stage II Initial Flood Risk Assessment – to confirm sources of flooding that may affect an area or
proposed development, to appraise the adequacy of existing information and to scope the extent of the
risk of flooding which may involve preparing indicative flood zone maps.
Stage III Detailed Flood Risk Assessment – to assess flood risk issues in sufficient detail and to provide
a quantitative appraisal of potential flood risk to a proposed or existing development or land to be zoned,
of its potential impact on flood risk elsewhere and of the effectiveness of any proposed mitigation
measures.
2.3. Likelihood of Flooding
The Guidelines define the likelihood of flooding as the percentage probability of a flood of a given
magnitude or severity occurring or being exceeded in any given year. It is generally expressed as a
return period or annual exceedance probability (AEP). A 1% AEP flood indicates a flood event that will
be equaled or exceeded on average once every hundred years and has a return period of 1 in 100
years. Annual Exceedance Probability is the inverse of return period as shown in Table 1 below.
Table 1. Correlation between return period and AEP
Return Period (years) Annual Exceedance Probability (%)
1 100
10 10
50 2
100 1
200 0.5
1000 0.1
• 10% (High Probability) Annual Exceedance Probability
This can also be expressed as the 10 Year Return Period and as a 10:1 odds of occurrence in
any given year.
• 1% (Medium Probability - Fluvial/River Flood Maps) Annual Exceedance Probability
This can also be expressed as the 100 Year Return Period and as 100:1 odds of occurrence in
any given year.
• 0.5% (Medium Probability - Coastal Flood Maps) Annual Exceedance Probability
This can also be expressed as the 200 Year Return Period and as 200:1 odds of occurrence in
any given year.
• 0.1% (Low Probability) Annual Exceedance Probability,
Which can also be expressed as the 1000 Year Return Period and as 1000:1 odds of occurrence
in any given year.
2.4. Climate Scenarios
The following outlines common climate scenarios used for fluvial and coastal flood maps.
• The Present Day Scenario - This is also referred to as the Current Scenario. Present Day
Scenario data was generated using methodologies based on historic flood data, without taking
account of potential changes due to climate change. RECEIVED: 08/09/2026
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• The Mid-Range Future Scenario (MRFS) - This scenario is generated taking in the potential
effects of climate change using an increase in rainfall of 20% and sea level rise of 500mm (20
inches).
• The High-End Future Scenario (HEFS) - This scenario is generated taking in the potential
effects of climate change using an increase in rainfall of 30% and sea level rise of 1,000 mm (40
inches).
2.5. Definition of Flood Zones
Flood zones are geographical areas within which the likelihood of flooding is in a particular range and
are split into three categories in The Guidelines:
2.5.1. Flood Zone A
Flood Zone A where the probability of flooding from rivers and the sea is highest (greater than 1% or 1
in 100 for river flooding or 0.5% or 1 in 200 for coastal flooding);
Most types of development would be considered inappropriate in this zone. Development in this zone
should be avoided and/or only considered in exceptional circumstances, such as in city and town
centres, or in the case of essential infrastructure that cannot be located elsewhere, and where the
Justification Test has been applied. Only water-compatible development, such as docks and marinas,
dockside activities that require a waterside location, amenity open space, outdoor sports and recreation,
would be considered appropriate in this zone.
2.5.2. Flood Zone B
Flood Zone B where the probability of flooding from rivers and the sea is moderate (between 0.1% or
1 in 1000 and 1% or 1 in 100 for river flooding and between 0.1% or 1 in 1000 or 0.5% or 1 in 200 for
coastal flooding);
Highly vulnerable development, such as hospitals, residential care homes, Garda, fire and ambulance
stations, dwelling houses and primary strategic transport and utilities infrastructure, would generally be
considered inappropriate in this zone, unless the requirements of the Justification Test can be met.
Less vulnerable development, such as retail, commercial and industrial uses, sites used for short-let for
caravans and camping and secondary strategic transport and utilities infrastructure, and water-
compatible development might be considered appropriate in this zone. In general, however, less
vulnerable development should only be considered in this zone if adequate lands or sites are not
available in Zone C and subject to a flood risk assessment to the appropriate level of detail to
demonstrate that flood risk to and from the development can or will adequately be managed.
2.5.3. Flood Zone C
Flood Zone C where the probability of flooding from rivers and the sea is low (less than 0.1% or 1 in
1000 for both river and coastal flooding. Flood Zone C covers all plan areas which are not in zones
A or B.
Development in this zone is appropriate from a flood risk perspective (subject to assessment of flood
hazard from sources other than rivers and the coast) but would need to meet the normal range of other
proper planning and sustainable development considerations.
It is important to note that when determining flood zones the presence of flood protection structures
should be ignored. This is because areas protected by flood defences still carry a residual risk from
overtopping or breach of defences and the fact that there is no guarantee that the defences will be
maintained in perpetuity. RECEIVED: 08/09/2026
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Figure 2. OPW The Planning System and Flood Risk Management, Classification of vulnerability of different types of
development RECEIVED: 08/09/2026
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2.6. Objectives and Principles of the Planning Guidelines
The principal actions when considering flood risk are set out in the planning guidelines and are
summarized below:
• “Flood hazard and potential risk should be determined at the earliest stage of the planning
process...”
• “Development should preferentially be located in areas with little or no flood hazard thereby
avoiding or minimising the risk. ”
• “Development should only be permitted in areas at risk of flooding when there are no alternative,
reasonable sites available. ”
• “Where development is necessary in areas at risk of flooding an appropriate land use should be
selected”
• A precautionary approach should be applied, where necessary, to reflect uncertainties in
flooding datasets and risk assessment techniques. ”
• “Land required for current and future flood management... should be pro-actively identified”
• “Flood risk to, and arising from, new development should be managed through location, layout
and design incorporating Sustainable Drainage Systems (SuDS) and compensation for any loss
of floodplain”
• Strategic environmental assessment (SEA) of regional planning guidelines, development plans
and local area plans should include flood risk as one of the key environmental criteria”
2.7. The Sequential Approach and Justification Test
The Guidelines outline the sequential approach that is to be applied to all levels of the planning process.
This approach should also be used in the design and layout of a development, and the broad philosophy
is shown in Figure 3 below. In general, development in areas with a high risk of flooding should be
avoided as per the sequential approach. However, this is not always possible as many town and city
centers are within flood zones and are targeted for development. RECEIVED: 08/09/2026
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Figure 3.Sequential Approaches (Source: The Planning System and Flood Risk Management)
The Justification Test has been designed to rigorously assess the appropriateness, or otherwise, of
developments that are being considered in areas of moderate or high flood risk. The test comprises the
following two processes.
The first is the Plan-making Justification Test and is used at the plan preparation and adoption stage
where it is intended to zone or otherwise designate land which is at moderate or high risk of flooding.
The second is the Development Management Justification Test and is used at the planning application
stage where it is intended to develop land at moderate or high risk of flooding for uses or development
vulnerable to flooding that would generally be inappropriate for that land.
Table 2 below illustrates the types of development that would be required to meet the Justification Test.
Table 2. Matrix of vulnerability versus flood zone to illustrate appropriate development and that required to meet the
Justification Test (Source: The Planning System and Flood Risk Management)
Flood Zone A Flood Zone B Flood Zone C
Highly vulnerable
development (including
essential infrastructure)
Justification Test
Justification Test
Appropriate
Less vulnerable
development
Justification Test Appropriate Appropriate
Water-compatible
development Appropriate Appropriate Appropriate
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3. STUDY AREA
The proposed development consists of proposed dwelling, proposed garage and proposed associated
services such as proposed percolation area and septic tank at Feebaghbane, Scotstown, County
Monaghan.
Site Location is shown in Figures 4 & 5, proposed Site Layout is shown in Figure 5. Full Site Layout
drawings are shown in Appendix A, site location coordinates: 54.306531, -7.061860.
Figure 4. Site Location (Google Maps) RECEIVED: 08/09/2026
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Figure 5. Site Layout and Extent of Proposed Works RECEIVED: 08/09/2026
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4. STAGE 1 – FLOOD RISK IDENTIFICATION
4.1. General
This Stage I Flood Risk Identification includes a review of the existing information and the identification
of any flooding or surface water management issues in the vicinity of the proposed site.
4.2. Information Sources Consulted
The following information sources were consulted as part of the Stage I Flood Risk Identification:
Table 3. Information Sources Consulted
Source Comments
OPW Flood Info maps
consulted
Fluvial, Pluvial, Coastal and Groundwater flooding
examined;
http://www.floodinfo.ie/map/floodplans/
https://www.floodinfo.ie/map/floodmaps/
Catchment Flood Risk
Assessment and Management
Study (CFRAM)
https://www.floodinfo.ie/map/floodmaps/
OPW flood records www.floodmaps.ie,
Geological Survey of Ireland
(GSI) Maps
GSI Teagasc subsoils map consulted to identify if
alluvium is present at development site that may indicate
the presence of a watercourse and floodplain
4.2.1. Previous Flood Risk Assessments and Predictive Flood Maps
Preliminary Flood Risk Assessment
The PFRA is a national screening exercise, based on available and readily-derivable information, to
identify areas where there may be a significant risk associated with flooding (referred to as Areas for
Further Assessment or AFA’s). As part of the PFRA study, maps of the country were produced showing
the indicative fluvial, coastal, pluvial and groundwater flood extents.
The OPW Preliminary Flood Risk Assessment Maps, (PFRA) are now retired and replaced by National
Indicative Fluvial Mapping (NIFM) at floodinfo.ie web page.
Pluvial flood mapping at retired PFRA mapping is indicative and is not decisive for site Flood Zone
categorization. Fluvial and Coastal flooding are decisive for site Flood Risk categorization as per Table
2.
4.2.2. OPW Community-Scale Flood Extent
This Flood Hazard data is produced to meet the requirements of Article 6 of the European Communities
(Assessment and Management of Flood Risks) Regulations 2010 to 2015 (the “Regulations”)
(implementing Directive 2007/60/EC). This dataset shows the modelled extent of land that might be
flooded by river flooding (fluvial flooding) during a theoretical or ‘design’ flood event with an estimated
probability of occurrence, rather than information for actual floods that have occurred in the past. The
flood extents have been developed taking account of effective flood defences. Areas that are not shown
as being flooded may still be at risk of flooding from unmodelled coastal or river reaches, as well as
from other flood sources. RECEIVED: 08/09/2026
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Fluvial and coastal flood hazard data is developed using hydrodynamic modelling. This is based on
calculated design river flows and extreme sea levels, surveyed channel cross-sections, river / coastal
structures, Digital Terrain Models, and other relevant datasets such as land use, data on past floods for
model calibration etc. The data has been developed taking account of effective flood defences. Areas
that are not shown as being flooded may still be at risk of flooding from unmodelled coastal or river
reaches, as well as from other flood sources.
The flood depths are calculated by subtracting the ground levels from the predicted water level. The
flood depths are mapped as constant depths over grid squares, whereas in reality depths may vary
within a given square. The flood depth data originates from a significant number of individual projects
as described below and the process may vary for particular areas or maps. Individual Technical
Hydrology and Hydraulics Reports set out full technical details on the derivation of the flood maps for
each location.
The primary flood depth data source is the original project raster data, suitable for analysis purposes.
For national-scale display, the individual depth datasets are reprocessed into a banded vector product
to harmonise resolutions and grid origins and to remove dataset overlaps. The resulting depth vector
data product is suitable for display purposes only at a national scale.
Flood extents are derived from raster flood depth maps and vectorised to produce the final vector
outputs. The national flood extents dataset is compiled from the original source data and is based on
the alignment of the original raster datasets, rather than on the banded national vector depth product.
Evidence of estimated flooding within or in the vicinity of the site is shown below at Figure 6, information
is not available for site location.
The Present Day Scenario - This is also referred to as the Current Scenario. Present Day Scenario data
was generated using methodologies based on historic flood data, without taking account of potential
changes due to climate change.
Figure 6. OPW Community-Scale Flood Extent – All Probabilities Present Day Scenario.
The Mid-Range Future Scenario (MRFS) - This scenario is generated taking in the potential effects of
climate change using an increase in rainfall of 20% and sea level rise of 500mm (20 inches). RECEIVED: 08/09/2026
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Evidence of estimated flooding within or in the vicinity of the site is shown below at Figure 7, information
is not available for site location.
Figure 7. OPW Community-Scale Flood Extent – Mid-Range Future Scenario – All Probabilities
The High-End Future Scenario (HEFS) - This scenario is generated taking in the potential effects of
climate change using an increase in rainfall of 30% and sea level rise of 1,000 mm (40 inches).
Evidence of estimated flooding within or in the vicinity of the site is shown below at Figure 8, information
is not available for site location.
Figure 8. OPW Community-Scale Flood Extent – High-End Future Scenario – All Probabilities
Evidence of estimated CFRAM Pluvial Flooding within or in the vicinity of the site is shown below at
Figure 9. Information is not available for site location. RECEIVED: 08/09/2026
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Figure 9. OPW Community-Scale Pluvial Flood Extent – All Probabilities
4.2.3. National Indicative Fluvial Mapping (NIFM) River Flood Extent
This data shows the modelled extent of land that might be flooded by rivers (fluvial flooding) during a
theoretical or ‘design’ flood event with an estimated probability of occurrence, rather than information
for actual floods that have occurred in the past.
The Present-Day Scenario is also referred to as the Current Scenario. Present Day Scenario data was
generated using methodologies based on historic flood data, without taking account of potential
changes due to climate change. The potential effects of climate change have been separately modelled
and reported on.
Data has been produced for catchments greater than 5km2 in areas for which flood maps were not
produced under the National CFRAM Programme and should be read in this context. River reaches
that have been modelled are indicated by the NIFM Modelled River Centrelines dataset.
Flooding from other reaches of river may occur, but has not been mapped, and so areas that are not
shown as being within a flood extent may therefore be at risk of flooding from unmodelled rivers (as
well as from other sources).
The Present Day Scenario - This is also referred to as the Current Scenario. Present Day Scenario data
was generated using methodologies based on historic flood data, without taking account of potential
changes due to climate change.
Evidence of estimated flooding within or in the vicinity of the site is shown below at Figure 10.
RECEIVED: 08/09/2026
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Figure 10. National Indicative Fluvial Mapping – Present Day Scenario, Low and Medium Probability.
The Mid-Range Future Scenario (MRFS) - This scenario is generated taking in the potential effects of
climate change using an increase in rainfall of 20% and sea level rise of 500mm (20 inches).
Evidence of estimated flooding within or in the vicinity of the site is shown below at Figure 11.
Figure 11. National Indicative Fluvial Mapping – Mid-Range Future Scenario, Low and Medium Probability. RECEIVED: 08/09/2026
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The High-End Future Scenario (HEFS) - This scenario is generated taking in the potential effects of
climate change using an increase in rainfall of 30% and sea level rise of 1,000 mm (40 inches).
Evidence of estimated flooding within or in the vicinity of the site is shown below at Figure 12.
Figure 12. National Indicative Fluvial Mapping – High-End Future Scenario, Low and Medium Probability.
4.2.4. Arterial Drainage Scheme Channels
Arterial Drainage Schemes were carried out under the Arterial Drainage Act, 1945 to improve land for
agriculture and to mitigate flooding. Rivers, lakes weirs and bridges were modified to enhance
conveyance, embankments were built to control the movement of flood water and various other work
was carried out under Part II of the Arterial Drainage Act, 1945. The purpose of the schemes was to
improve land for agriculture, to ensure that the 3 – year flood was retained in bank this was achieved
by lowering water levels during the growing season to reduce waterlogging on the land beside
watercourses known as callows.
Flood protection in the benefiting lands was increased as a result of the Arterial Drainage Schemes.
Evidence of ADS Channels within vicinity of the site is shown below at Figure 13. Site is within ADS
Channel C1/1/5/21 and ADS Benefited Lands location. RECEIVED: 08/09/2026
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Figure 13. Arterial Drainage Scheme (ADS)
4.2.5. Past Flood Events
A Past Flood Event is defined as the occurrence of recorded flooding at a given location on a given
date or on a recurring basis. The event is derived from available flood information documentation
including flood event reports, news articles, archive information and photos.
Past flood events are represented on the map in three different ways. Where the boundary of a flood
has been mapped, the flood is shown as a shaded area with a blue border defining the extent of the
flood. Most floods cannot be shown in this way because the extent of the flood was not mapped at the
time. Therefore, floods without extent information are represented with a point symbol at the
approximate location of the flood. A flood point symbol is placed at any location mentioned in a report
giving details of a flood event. Where more than one flood has occurred in the same location, and to
denote a location with recurring flooding, a multiple flood point symbol is used.
Evidence of past flood events within or in the vicinity of the site is shown below at Figure 14. RECEIVED: 08/09/2026
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Figure 14. Past Flood Events
4.2.6. Geological Survey Ireland Groundwater Flooding
Groundwater is the water that soaks into the ground from rain and can be stored beneath the ground.
Groundwater floods occur when the water stored beneath the ground rises above the land surface.
Geological Survey Ireland have developed Groundwater Flood Maps for the Republic of Ireland. The
maps were developed as part of the 2016-2019 GW Flood project in collaboration with Trinity College
Dublin and the Institute of Technology Carlow.
Evidence of Groundwater flood events within or in the vicinity of the site is shown below at Figure 15.
Figure 15. Groundwater Flood Events RECEIVED: 08/09/2026
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5. STAGE 2 – INITIAL FLOOD RISK ASSESSMENT
5.1. General
A Stage 2 FRA (initial flood risk assessment) was undertaken to:
• Confirm the sources of flooding that may affect the subject site;
• Appraise the adequacy of existing information as identified by the Stage 1 FRA
5.2. Sources of Flooding
Groundwater Flooding
Ground water flooding is a result of upwelling in occurrences where the water table or confined aquifer
rises above the ground surface. This tends to occur after long periods of sustained rainfall and/or very
high tides. High volumes of rainfall and subsequent infiltration to ground will result in a rising of the water
table. Groundwater flooding tends to occur in low - lying areas, where with additional groundwater
flowing towards these areas, the water table can rise to the surface causing groundwater flooding.
The sources consulted such as the OPW Community-Scale Flood Extent mapping are not available for
this location, available GSI records show no indication that the proposed site location is subject to
Groundwater derived flooding.
The proposed site is not considered to require a detailed flood risk assessment with respect to
groundwater flooding.
Pluvial Flood Risk
Pluvial flooding results from heavy rainfall that exceeds ground infiltration capacity or more commonly
in Ireland where the ground is already saturated from previous rainfall events. This causes ponding and
flooding at localized depressions. Pluvial flooding is commonly a result of changes to the natural flow
regime such as the implementation of hard surfacing and improper drainage design.
The sources consulted such as the OPW Flood Maps and OPW Rainfall Flood Plans mapping show no
indication that the proposed site is subject to pluvial derived flooding.
Any potential pluvial flood risk would be accommodated by proposed site drainage will not result in a
loss / reduction of pluvial flood water storage on site.
Fluvial Flood Risk
A fluvial, or river flood, occurs when the water level in a river, lake or stream rises and overflows onto
the surrounding banks, shores and neighboring land. The water level rise could be due to excessive
rain or snowmelt.
The sources consulted such as the CFRAM, OPW Flood Maps, OPW Flood Plans and OPW
Community-Scale Flood Extent mapping show indication that part of the site is subject to fluvial derived
flooding.
As per National Indicative Fluvial Mapping (NIFM) River Flood Extents - High-End Future Scenario, site
survey and proposed dwelling location, it has been determined that Low probability flood level (1:1000
years with 30% climate change factor applied) is 88.10 mOD. Proposed dwelling FFL is set at 88.60
mOD, proposed garage FFL is set at 88.40 mOD, minimum of 300mm freeboard is provided, refer to
Figure 16. RECEIVED: 08/09/2026
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Kevin Treanor & Ciara Leonard, August
2026
Figure 16. Flood level as per NIFM-HEFS - 88.10 mOD.
Coastal Flood Risk
Coastal flooding is the inundation of land areas along the coast by seawater. Common causes of
coastal flooding are intense windstorm events occurring at the same time as high tide (storm surge),
and tsunamis.
Storm surge is created when high winds from a windstorm force water onshore — this is the leading
cause of coastal flooding and often the greatest threat associated with a windstorm. The effects
increase depending on the tide - windstorms that occur during high tide result in devastating storm
surge floods. In this type of flood, water overwhelms low-lying land and often causes devastating loss
of life and property.
The sources consulted such as the CFRAM, OPW Flood Maps, OPW Flood Plans and OPW
Community-Scale Flood Extent mapping show no indication that site is subject to coastal derived
flooding.
RECEIVED: 08/09/2026
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2026
5.3. Conclusion of Stage 2 FRA
The sources consulted such as the CFRAM, OPW Flood Maps, OPW Flood Plans and OPW
Community-Scale Flood Extent mapping show no indication that the site is subject to groundwater,
pluvial and coastal flooding.
As per National Indicative Fluvial Mapping (NIFM) River Flood Extents - High-End Future Scenario, site
survey and proposed dwelling location, it has been determined that Low probability flood level (1:1000
years with 30% climate change factor applied) is 88.10 mOD. Proposed dwelling FFL is set at 88.60
mOD, proposed garage FFL is set at 88.40 mOD, minimum of 300mm freeboard is provided.
Based on the above information and extent of proposed works, proposed dwelling with all associated
works would be allocated as Flood Zone C, proposed garage would be allocated as Flood Zone B.
6. STAGE 3 – DETAILED FLOOD RISK ASSESSMENT
6.1. Conclusion of Stage 3 FRA
Stages 1 and 2 of the flood risk assessment of proposed site have indicated that the site is not subject
to flooding in low, medium or high probability exceedance events up to 0.1% AEP (1 in 1000 chance
in any given year) with 30% climate change factor applied from groundwater, pluvial and coastal
flooding.
As per National Indicative Fluvial Mapping (NIFM) River Flood Extents - High-End Future Scenario, site
survey and proposed dwelling location, it has been determined that Low probability flood level (1:1000
years with 30% climate change factor applied) is 88.10 mOD. Proposed dwelling FFL is set at 88.60
mOD, proposed garage FFL is set at 88.40 mOD, minimum of 300mm freeboard is provided.
Any potential pluvial flood risk would be accommodated by proposed site drainage and will not result in
a loss / reduction of pluvial flood water storage on site.
Based on the above information and extent of proposed works, proposed dwelling with all associated
works would be allocated as Flood Zone C, proposed garage would be allocated as Flood Zone B as
per Table 2. The proposed dwelling with proposed associated works is defined as Highly Vulnerable
Development, proposed garage as Less Vulnerable Development as per OPW The Planning System
and Flood Risk Management, Figure 2. The site is Appropriate as per Table 2.
RECEIVED: 08/09/2026
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Kevin Treanor & Ciara Leonard, August
2026
7. CONCLUSIONS
Stages 1, 2 and 3 of the flood risk assessment of the proposed site have indicated that the site is not
subject to flooding in low, medium or high probability exceedance events up to 0.1% AEP (1 in 1000
chance in any given year) with 20% climate change factor applied from groundwater, pluvial, fluvial
and coastal flooding.
As per National Indicative Fluvial Mapping (NIFM) River Flood Extents - High-End Future Scenario, site
survey and proposed dwelling location, it has been determined that Low probability flood level (1:1000
years with 30% climate change factor applied) is 88.10 mOD. The proposed dwelling FFL is set at 88.60
mOD, proposed garage FFL is set at 88.40 mOD, minimum of 300mm freeboard is provided.
Any potential pluvial flood risk would be accommodated by the proposed site drainage and will not result
in a loss / reduction of pluvial flood water storage on site.
Based on the above information and extent of proposed works, the proposed dwelling with all
associated works would be allocated as Flood Zone C, proposed garage would be allocated as Flood
Zone B as per Table 2. The proposed dwelling with proposed associated works is defined as Highly
Vulnerable Development, the proposed garage as Less Vulnerable Development as per OPW The
Planning System and Flood Risk Management, Figure 2. The site is Appropriate as per Table 2.
The proposed site will not have an adverse impact or impede access to watercourses, floodplains or
flood protections and management facilities. RECEIVED: 08/09/2026
Appendix A RECEIVED: 08/09/2026
89878 8
SCTPTPTPMkrWMGG90.6989.28SV90.6290.
8390.8090.6390.6190.
5390.
3490.
4390.
4690.
1690.
2590.
0490.
2389.
6989.
6789.
9189.
8989.
7589.
7589.
4689.
2589.
4889.
3889.
2489.
3489.RECEIVED: 08/09/2026
RECEIVED: 08/09/2026