Site Specific Flood Risk Assessment - Project: Newmarket / Ardee Street BTR Development Job No. 19.308 - Newmarket SHD
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Site Specific Flood Risk Assessment
Project:
Newmarket / Ardee Street BTR
Development
Job No.
19.308
Document No.: 19.308-IR-02 1
DOCUMENT CONTROL
Project: Newmarket / Ardee Street BTR Development
Project No: 19.308
Document Title: Site Specific Flood Risk Assessment
Document No: 19.308 – IR – 02
DOCUMENT STATUS
Issue Date Description Orig. PE Issue Check
1 30.05.21 Draft KB MH MH
2 04.06.21 PAC Issue KB MH MH
3 29.06.21 PAC Issue KB MH MH
4 01.12.21 SHD Submission KB MH MH
© Copyright Barrett Mahony Consulting Engineers. All rights reserved.
The report has been prepared for the exclusive use of our client and unless otherwise agreed in writing by Barrett Mahony Consulting Engineers no other party may
use, make use of or rely on the contents of this report. The report has been compiled using the resources agreed with the client and in accordance with the scope of
work agreed with the client. No liability is accepted by Barrett Mahony Consulting Engineers for any use of this report, other than the purpose for which it was prepared.
Barrett Mahony Consulting Engineers accepts no responsibility for any documents or information supplied to Barrett Mahony Consulting Engineers by others and no
legal liability arising from the use by others of opinions or data contained in this report. It is expressly stated that no independent verification of any documents or
information supplied by others has been made. Barrett Mahony Consulting Engineers has used reasonable skill, care and diligence in compiling this report and no
warranty is provided as to the report’s accuracy. No part of this report may be copied or reproduced, by any means, without the written permission of Barrett Mahony
Consulting Engineers.
Prepared by: Prepared for:
BMCE Nrek1 Limited
52-54 Lower Sandwith Street 12 Northbrook Road
Dublin 2 Ranelagh
D02WR26 Dublin 6
Director - Planning D06E8W5
Document No.: 19.308-IR-02 2
CONTENTS
1. INTRODUCTION .................................................................................... 3
1.1 General Description ............................................................................................. 3
1.2 Scope Of This Report ........................................................................................... 3
2. Stage 1: Flood Risk Identification .......................................................... 5
2.1 Historical Flooding ............................................................................................... 5
2.2 Coastal Flooding .................................................................................................. 6
2.3 Fluvial Flooding .................................................................................................... 7
2.4 Ground Water ...................................................................................................... 8
2.5 Pluvial Flooding .................................................................................................... 9
2.6 Climate Change .................................................................................................. 10
3. Stage 2: Initial Flood Risk Assessment ................................................ 11
3.1 Sequential Approach ......................................................................................... 11
4. Residual Flood Risk Management ....................................................... 14
5. Conclusion.......................................................................................... 14
APPENDICES
APPENDIX 1 - Site Plan Layout
APPENDIX 2 - OPW Flood Maps
Document No.: 19.308-IR-02 3
1. INTRODUCTION
1.1 GENERAL DESCRIPTION
Planning permission is being sought for a proposed mixed use, primarily residential
development at Newmarket Square, Ardee Street and Mill Street, Newmarket, Dublin 8 on
behalf of Nrek1 Limited.
This report outlines the findings of the Site Specific Flood Risk Assessment (SSFRA) carried out
for the proposed development.
The proposed development site is approximately 0.32 hectares in area and consists of the
demolition of all existing buildings/structures on the site and the construction of a 6-9 storey
mixed use building with frontage onto Newmarket Square to the north, Ardee Street to the west
and Mill Street to the south.
Refer figure 1.1 and Site Plan Layout drawing in Appendix 1 for a satellite and a plan view of the
site.
Building
Location
Figure 1.1: Site Location
The proposed building contains the following:
• 134 no. Build-To-Rent (BTR) apartment dwellings, comprising 1 no. studio unit, 96 no. 1
bed units, 7 no. 2 bed (3 person) units and 30 no. 2 bed (4 person) units. The proposed
apartments are primarily provided from first to eight floor level (132 no. units) with 2 no.
units provided at ground floor level with frontage onto Ardee Street.
• 314 sqm of private amenity space for the BTR units is provided in the form of balconies
on all elevations (55 no. balconies);
• 1,131 sqm of external communal amenity space for future residents is provided in the
form of a large first floor level communal courtyard (330 sqm) and 5 no. communal
garden terraces at roof level (total of 801 sqm), incorporating associated landscaping,
external lighting and seating areas.
• 115.7 sqm of internal communal amenity space for future residents is provided at ground
floor level, including a co-working area (60.6 sqm) and a games room (55.1 sqm). The co-
working area addresses the corner of Ardee Street and Mill Street, while the games room
addresses Mill Street;
Document No.: 19.308-IR-02 4
• The main resident access to the BTR units is provided via a foyer (50 sqm) at ground floor
level fronting onto Ardee Street, incorporating a reception desk and
management/maintenance office area. Ancillary services for BTR residents at ground
floor level include a refuse storage area (58.3 sqm) and a bicycle storage area (184.4 sqm)
accommodating 238 no. resident/visitor bicycle spaces and 2 no. spaces for cargo bikes.
Additional external access to the bike and bin storage areas is provided via doors onto
Mill Street.
• 606.1 sqm of ground floor level commercial/retail space is proposed, with direct frontage
onto Newmarket Square and at the corner of Newmarket Square and Ardee Street. The
commercial/retail unit includes a dedicated refuse storage area (27.9 sqm) and a bike
storage area (7.7 sqm) accommodating 8 no. spaces. Additional external access to the
bike and bin storage areas is provided via doors onto Newmarket Square.
• The ground floor level also incorporates ancillary infrastructure/services for the building
including an Energy Centre (80.0 sqm, Water Storage Plant (58.0 sqm) and 2 no. ESB
substation/switch rooms. The ESB substation/switch rooms are accessed directly from
Newmarket Square.
Proposals are also provided for road, footpath, vehicular parking and public realm upgrade works
in the immediate vicinity of the site. These proposals facilitate the provision of enhanced
pedestrian facilities along Newmarket Square, Ardee Street and Mill Street, and at the 2 no. road
junctions immediately to the north-west (Newmarket Square/Ardee Street/Chamber Street
junction) and south-west (Mill Street/Ardee Street/Oscar Square/Clarance Mangan Road
junction) of the site respectively. 5 no. additional car parking spaces (including 1 no. dedicated
car share space) and 1 no. loading bay, together with the relocation of an existing bus stop are
also provided by the proposed development along Ardee Street.
The proposed development also includes all associated site and development works and ancillary
infrastructure including water services, foul and surface drainage and connections, attenuation
proposals, electrical connections, public lighting and signage.
1.2 SCOPE OF THIS REPORT
This report outlines the findings of the SSFRA (site specific flood risk assessment) carried out for
the proposed residential development, and takes cognisance of the following relevant
guidelines and policies:
• Department of the Environment Heritage and Local Government (DEHLG) and the Office of
Public Works (OPW) Guidelines for Planning November 2009 on ‘The Planning System and
Flood Risk Management Guidelines for Planning Authorities’.
• The Planning and Development Act 2000.
The stages involved in the assessment of flood risk are listed in the guidelines as follows:
• Stage 1: Flood Risk Identification
• Stage 2: Initial Flood Risk Assessment
• Stage 3: Detailed Flood Risk Assessment
The OPW and DEHLG’s publication also outline a Sequential Approach for determining whether
a particular development is appropriate for a specified location in terms of flood risk. The
categorisation of the subject site in terms of the OPW and DEHLG’s sequential approach is
further outlined in Section 3.
Document No.: 19.308-IR-02 5
2. STAGE 1: FLOOD RISK IDENTIFICATION
Stage 1 identifies whether there are any flooding or surface water management issues at the
subject site location and whether a flood risk assessment is required. This involves review of
desk study information available as outlined in the following headings.
Table 2.1 The possible sources of flood water
Source Pathway Receptor Likelihood Consequence Risk
Tidal Note Overtop Property Very High Low
Breach remote
Fluvial Note Overtop Property Remote High Medium
Breach
Groundwater Rising Property Very Medium Low
groundwater remote
levels
Pluvial Overflow / Property Possible Medium Medium
Surface water Blockage
2.1 HISTORICAL FLOODING
A review of the OPW Historical Flood Maps online was carried out and indicates no flooding
events in the immediate vicinity of the site.
On 20th January 1941 flooding associated with the Liffey catchment occurred approximately
540m northwest of the subject site on Marrowbone Lane.
Flooding occurred on 10th June 1963 on Clanbrassil Street, approximately 400m southeast of
the subject site, which was associated with the Liffey catchment.
Flooding occurred on Wexford Street on 26th July 2013 associated with the null catchment,
which is approximately 850m east of the subject site.
The Local Authority notes that a number of defence assets were put in place after these events.
Recurrent flooding has been recorded at Camac Bow Bridge, however the Local Authority has
put a number of defence assets in place. This location is 1.3km northwest of the subject site.
Based on available and recorded information as outlined above, the subject site is considered
not to have been subject to flooding in recent history.
Document No.: 19.308-IR-02 6
Site Location
Figure 2.1 Recorded Past Flood Events (Source: OPW – www.floodinfo.ie)
2.2 COASTAL FLOODING
Coastal flooding occurs when sea levels along the coast of in estuaries exceed neighbouring land
levels or overcome coastal defences where these exist. A review of the OPW Tidal Flood Extents
Mapping was carried out and indicates no coastal flooding at the subject site for the following
flood event probabilities:
• 10% Tidal AEP (Annual Exceedance Probabilities) or 1 in 10 year return period.
• 0.5% Tidal AEP or 1 in 200 year return period.
• 0.1% Tidal AEP or 1 in 1000 year return period.
Therefore, the risk of tidal flooding is considered low as the subject site lies outside the 0.1%
AEP.
Document No.: 19.308-IR-02 7
Site Location
Figure 2.2 Tidal Flood Extends (Source: OPW Eastern CFRAM Study)
2.3 FLUVIAL FLOODING
Fluvial flooding occurs when rivers and streams break their banks and water flows out onto the
adjacent low-lying areas. A review of the OPW Fluvial Flood Extents Mapping was carried out
and indicates low and medium probability fluvial flooding at the southern boundary of the
subject site for the following flood event probabilities:
• 10% Fluvial AEP (Annual Exceedance Probabilities) or 1 in 10 year return period.
• 1% Fluvial AEP or 1 in 200 year return period.
• 0.1% Fluvial AEP or 1 in 1000 year return period.
The site is not located near any major open watercourses, however a branch of the culverted
River Poddle flows beneath Mill Street. A review of the OPW Flood Maps database does not
indicate any history of flood events at or near the subject site. It is worth noting that an open
part of the River Poddle is located to the south-east of the site, within the Sweeneys Corner
Student Accommodation development that is currently under construction.
Flood risk modelling conducted on behalf of the OPW under the Eastern CFRAM (Catchment
Flood Risk Assessment and Management) Study indicates that the subject site is within an area
with a fluvial flood event AEP of less than 1%. The risk of fluvial flooding within the site is
therefore considered low. The OPW Fluvial Flood Extents Maps near the subject site is included
in Appendix 2 for further information.
Document No.: 19.308-IR-02 8
Proposed
Building
Location
Figure 2.3 Fluvial Flood Extents (Source: OPW Eastern CFRAM Study)
2.4 GROUND WATER
Groundwater flooding occurs when the level of water stored in the ground rises as a result of
prolonged rainfall, to meet the ground surface and flows out over. A desktop study was carried
out to review previous site investigations in the surrounding area of the site out to identify
ground water levels. Ground investigations on an adjacent site (‘The Eight Building’) to the east
recorded groundwater at 7.70m BGL. The locations of this site investigations in relation to the
proposed site are shown in Figure 2.4 below. The risk of flooding due to ground water ingress
to the proposed development is considered low.
Adjacent Site
‘The Eight Building’
Proposed
Building
Figure 2.4 Site Investigation Info Available From Adjacent Site
Document No.: 19.308-IR-02 9
A review of the groundwater vulnerability data from the Geological Survey Ireland (GSI) website
was also carried out and the model indicates low risk of groundwater contamination. The map
identifies how susceptible areas are to groundwater contamination.
Site
Location
Figure 2.5 Groundwater Vulnerability (Source: GSI Data Viewer Map)
2.5 PLUVIAL FLOODING
Pluvial flooding occurs when the amount of rainfall exceeds the capacity of urban surface water
drainage systems or the ground to absorb it. A review of the available literature including the
DCC FloodResilienCity (FRC) project was carried out and indicates some pluvial flooding
surrounding the site. Note, these maps are ‘predictive’ flood maps showing areas predicted to
be inundated 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, which is
presented on ‘historical’ flood maps.
The FRC project considers the subject site to be low risk of pluvial flooding as it is not located in
low laying areas. The FRC project identifies the main surface of flooding to be surface water run-
off conveyed by road networks into low lying areas.
A new surface water system is proposed to collect rainwater from all impervious areas of the
proposed building along with intensive and extensive green roof areas to reduce the
developments impact on existing surface water drainage systems. All stormwater will be
discharged to a Pluvial Cube Attenuation Tank and Soil Infiltration system. The risk of pluvial
flooding is considered low, due to existing and proposed measures in place.Document No.: 19.308-IR-02 10
Site Location
Figure 2.6 Pluvial Flood Extents (Source: OPW Eastern CFRAM Study)
2.6 CLIMATE CHANGE
All new developments are required to take climate change into consideration when assessing
the flood risk of a site. When designing for extreme rainfall events an allowance of 20%
additional flow should be taken. The system is designed for storms up to and including the 1 in
100 year storm and 20% extra for climate change. Hence the development can be considered
to be climate change resilient.Document No.: 19.308-IR-02 11
3. STAGE 2: INITIAL FLOOD RISK ASSESSMENT
The purpose of an initial flood risk assessment is to examine flood risk issues highlighted as part
of Stage 1 Flood Risk Identification.
Based on available recorded information as outlined in Stage 1, the site is considered to not
been subject to flooding in recent history.
The risk of tidal flooding is considered low as the subject site lies outside the 0.1% AEP.
The risk of fluvial flooding is considered low based on the Eastern CFRAM Study.
The risk of flooding due to ground water ingress to the proposed building is considered low.
The risk of pluvial flooding is considered low, due to the site location and proposed measures
for the building.
3.1 SEQUENTIAL APPROACH
The sequential approach used in this assessment follows the guidelines from The Planning
System and Flood Risk Management Guidelines for Planning Authorities, 2009, see Figure 3.1
for a graphical representation.
As outlined in the OPW and DEHLG publication, new developments are divided into three
categories which are as follows:
• Highly Vulnerable Development (i.e. power stations, residential)
• Less Vulnerable Development (i.e. retail, leisure)
• Water-compatible Development (i.e. car parking, recreational space)
The proposed residential development comes under the heading of Highly Vulnerable
Development.Document No.: 19.308-IR-02 12
Figure 3.1 Sequential Approach (Source: Guidelines for Planning Authorities, 2009)
Table 3.1 Matrix of vulnerability versus flood zone (Source: Guidelines for Planning Authorities, 2009)
Flood Zone A Flood Zone B Flood Zone C
Highly vulnerable
Justification Test Justification Test Appropriate
development
Less vulnerable
Justification Test Appropriate Appropriate
development
Water compatible
Appropriate Appropriate Appropriate
development
Geographical areas are similarly divided into three categories, based on their risk of river and
tidal flooding. The three categories are as follows:
• 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).
• 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 and 0.5% or 1 in 200 for coastal flooding).
• 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 i.e. all areas which are not within zone
A or B).
Based on the flood risk identification in Stage 1, the proposed building falls in Flood Zone C,
Therefore, a ‘Justification Test’ and / or Stage 3 Detailed Flood Risk Assessment is not required.
The sequential approach shown recommends mitigation measures for residual risks. In addition,Document No.: 19.308-IR-02 13
extract from DCC Development Plan 2016-2022 in Figure 3.2 shows the proposed development
in Flood Zone C in agreement with this SSFRA.
Building
Location
Figure 3.2 Strategic Flood Risk Assessment (Source: Dublin City Development Plan 2016-2022)Document No.: 19.308-IR-02 14
4. RESIDUAL FLOOD RISK MANAGEMENT
As highlighted in Section 2, during extreme rainfall events and where the proposed drainage
system is blocked, there is a chance that localised ponding will occur. Ensuring that internal
finished floor levels are set above the highest external surface levels in the vicinity will allow for
any runoff or ponding to be retained on access road and bicycle parking surfaces. This measure
given the unlikely event, is considered appropriate for the nature of the development.
5. CONCLUSION
This report outlines the findings of the SSFRA carried out for the mixed use, primarily
residential development at Newmarket Square, Ardee Street and Mill Street, Dublin 8.
This SSFRA was carried out in accordance with the DEHLG guidelines for Planning 2009 and
The Planning and Development Act 2000.
Based on available and recorded information, the site has not been subject to flooding in recent
history.
The risk of tidal flooding is considered very low as the subject site lies outside the 0.1% AEP.
The risk of fluvial flooding in the area is considered low as the proposed site lies outside the 1%
AEP.
The risk of flooding due to ground water ingress to the proposed development is considered
low.
The risk of pluvial flooding is considered low, due to the site location and proposed measures
for the development.
Based on the flood risk identification in Stage 1, the proposed development falls in Flood Zone
C. Therefore, the proposed development is deemed ‘Appropriate’ in accordance with the
guidelines of the OPW’s publication.Appendix 1 Site Plan Layout
Notes:
DO NOT SCALE FROM THIS DRAWING. USE FIGURED DIMENSIONS IN ALL
CASES. VERIFY DIMENSIONS ON SITE AND REPORT ANY
DISCREPANCIES TO THE ARCHITECTS IMMEDIATELY. THIS DRAWING TO
BE READ IN CONJUNCTION WITH THE ARCHITECTS SPECIFICATION. ©
THIS DRAWING IS COPYRIGHT AND MAY ONLY BE REPRODUCED WITH
THE ARCHITECTS PERMISSION.
Drawing Notes:
BUS
BUS N
IN G
LO AD
IN G
LO AD
BUS
BUS
Refer to road
layout in Engineering
BUS
drawings PLANNING LEGEND
26959
NEWMARKET SQUARE
BUS
17572
Site Boundary Line
14424
LOADING LOADING LOADING
Applicant Ownership
STOP
Boundary
STOP
4373
3549
00
124
ROOF
PLANT FFL +34.296 m
FFL +37.296 m
FFL +43.339 m P01 10.11.21 LH ISSUED FOR PLANNING
23 UP
100 UP
UP UP
Rev Date DRN Description
BUS
Refer to
Landscaping
543
AR
BUS FFL +19.000 m drawings
70
FFL +40.339 m
19569
DE
39079
LO
AD
IN G
E
Reddy Architecture + Urbanism
LO
Dartry Mills,
AD
S TR
IN G
Dartry Road
3143 Dublin 6, D06 Y0E3.
T: +353 (0)1 4987000
EE
W: www.reddyarchitecture.com
E: info@reddyarchitecture.com
T
FFLUP
+36.957 m
UP Client Details:
NREK1 Limited
7
953
17157
Project Details:
Ardee Street
8154
STOP
10833
18 Newmarket, Dublin 8
STOP
MILL STR
7
EET
59
23
Drawing Title:
Proposed Site Layout Plan
Job No Date Scale@A3
P19-149D 11/23/21 1:500
STOP Status Drawn By:
Planning LH
Purpose Checked By:
Planning EOB
Drawing Number Revision
Roof
1 : 500 P19-149D_RAU- 3.1_004 P01Appendix 2 OPW Flood Maps
Subject Site at Ardee St / Newmarket D8
314200 314400 314600 314800 315000 315200 315400 315600 315800
Node Label Water Level (OD) Flow (m³/s) Water Level (OD) Flow (m³/s) Water Level (OD) Flow (m³/s)
10% AEP 10% AEP 1% AEP 1% AEP 0.1% AEP 0.1% AEP
234400
234400
SO15331313 8.4 2.26 8.43 2.62 8.46 3.21
SO15333813 5.52 4.19 5.94 4.67 6.63 5.72
SO15345201 2.53 4.4 2.59 4.98 2.69 6.27
Poddle
SO15345201
234200
234200
(
! IMPORTANT USER NOTE:
THE VIEWER OF THIS MAP SHOULD REFER
TO THE DISCLAIMER, GUIDANCE NOTES
AND CONDITIONS OF USE THAT
ACCOMPANY THIS MAP.
Legend
10% Fluvial AEP Event
1% Fluvial AEP Event
0.1% Fluvial AEP Event
Modelled River Centreline
234000
234000
AFA Extents
(
! Node Point
Node ID Node Label
SO15333813
(
!
233800
233800
FINAL
REV: NOTE: DATE :
233600
233600
Subject Site at
Ardee St /
Newmarket D8
233400
233400
(
! The Office of Public Works
Jonathan Swift Street
Elmwood House T +44(0) 28 90 667914
74 Boucher Road F +44(0) 28 90 668286
Trim Belfast W www.rpsgroup.com
Co Meath BT12 6RZ E ireland@rpsgroup.com
SO15331313 Map:
Poddle River Fluvial Flood Extents
Map Type: EXTENT
Source: FLUVIAL
Map Area: HPW
Scenario: CURRENT
233200
233200
Drawn By : F.M.C. Date : 11 August 2016
Checked By : A.S. Date : 11 August 2016
Approved By : S.P. Date : 11 August 2016
Drawing No. :
(
! E09POD_EXFCD_F0_06
314200 314400 314600 314800 315000 315200 315400 315600 315800
0 50 100 200 300 400 500
Map Series : Page 6 of 6
Metres [
SO14337104 © Ordnance Survey Ireland. All rights reserved. Licence number EN 0021016/OfficeofPublicWorks.
Drawing Scale : 1:5,000 @A3Document No.: 19.308-IR-02 1
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