Killala Community Windfarm...2017/08/03 · 5279 - Killala - Appendix G - FRA_PRINT_Rev2 5 July 2017 1.3 STATEMENT OF AUTHORITY Jennings O’Donovan & Partners Ltd. (“JOD”) Consulting

Killala Community

Windfarm

Mullafarry, Killala,

County Mayo

Flood Risk Assessment

July 2017

Killala Community Windfarm Designated Activity Company Lisglennon, Killala, Co. Mayo, Ireland.

Jennings O’Donovan & Partners Limited, Consulting Engineers, Finisklin Business Park, Sligo. Tel.: 071 - 916 1416 Fax: 071 - 916 1080 e mail: [email protected]

Jennings O’Donovan & Partners Consulting Engineers Sligo

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________________________________________________________________________________ 5279 - Killala - Appendix G - FRA_PRINT_Rev2 i July 2017

JENNINGS O’DONOVAN & PARTNERS LIMITED. Project, Civil and Structural Consulting Engineers, FINISKLIN BUSINESS PARK,

SLIGO,

IRELAND.

Telephone (071) 91 61416

Fax (071) 91 61080

Email [email protected]

Web Site www.jodireland.com �

DOCUMENT APPROVAL

PROJECT Killala Community Wind Farm, Mullafarry, Killala, County Mayo

CLIENT / JOB NO

Killala Community Windfarm Designated Activity Company

5279

DOCUMENT TITLE Flood Risk Assessment

Prepared by Reviewed / Approved by

Document

Name

Michael Conroy Name

David Kiely

Date

June 2017

Signature

Signature

Date

July 2017

Signature

Signature

This report, and information or advice which it contains, is provided by JENNINGS O’DONOVAN & PARTNERS LIMITED solely for internal use and reliance by its Client in performance of JENNINGS O’DONOVAN & PARTNERS LIMITED’s duties and liabilities under its contract with the Client. Any advice, opinions, or recommendations within this report should be read and relied upon only in the context of the report as a whole. The advice and opinions in this report are based upon the information made available to JENNINGS O’DONOVAN & PARTNERS LIMITED at the date of this report and on current standards, codes, technology and construction practices as at the date of this report. Following final delivery of this report to the Client, JENNINGS O’DONOVAN & PARTNERS LIMITED will have no further obligations or duty to advise the Client on any matters, including development affecting the information or advice provided in this report. This report has been prepared by JENNINGS O’DONOVAN & PARTNERS LIMITED in their professional capacity as Consulting Engineers. The contents of the report do not, in any way, purport to include any manner of legal advice or opinion. This report is prepared in accordance with the terms and conditions of JENNINGS O’DONOVAN & PARTNERS LIMITED contract with the Client. Regard should be had to those terms and conditions when considering and/or placing any reliance on this report. Should the Client wish to release this report to a Third Party for that party's reliance, JENNINGS O’DONOVAN & PARTNERS LIMITED may, at its discretion, agree to such release provided that:

(a) JENNINGS O’DONOVAN & PARTNERS LIMITED written agreement is obtained prior to such release, and (b) By release of the report to the Third Party, that Third Party does not acquire any rights, contractual or otherwise, whatsoever against JENNINGS O’DONOVAN & PARTNERS

LIMITED and JENNINGS O’DONOVAN & PARTNERS LIMITED, accordingly, assume no duties, liabilities or obligations to that Third Party, and (c) JENNINGS O’DONOVAN & PARTNERS LIMITED accepts no responsibility for any loss or damage incurred by the Client or for any conflict of JENNINGS

O’DONOVAN & PARTNERS LIMITED’s interests arising out of the Client's release of this report to the Third Party.


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________________________________________________________________________________ 5279 - Killala - Appendix G - FRA_PRINT_Rev2 ii July 2017

KILLALA COMMUNITY WINDFARM

FLOOD RISK ASSESSMENT

CONTENTS

1.0 INTRODUCTION ............................................................................................................. 3

1.1 GENERAL .......................................................................................................................... 3

1.2 SCOPE............................................................................................................................... 4

1.3 STATEMENT OF AUTHORITY ............................................................................................. 5

2.0 PLANNING GUIDELINES .............................................................................................. 6

3.0 PROPOSED DEVELOPMENT SITE .............................................................................. 8

3.1 PROPOSED DEVELOPMENT SITE .......................................................................................... 8

3.2 HAUL ROUTE OPTIONS ....................................................................................................... 8

4.0 FLOOD RISK REVIEW ................................................................................................. 10

4.1 APPROACH ...................................................................................................................... 10

4.2 FLUVIAL FLOOD RISK ...................................................................................................... 10

4.3 PLUVIAL FLOOD RISK ...................................................................................................... 13

4.4 GROUNDWATER FLOOD RISK............................................................................................ 14

4.5 AVAILABLE PREDICTIVE FLOOD RISK MAPPING ................................................................. 15

4.6 IMPACT OF DEVELOPMENT ON CURRENT FLOOD REGIME .................................................. 16

4.7 SUMMARY OF FLOOD RISK ............................................................................................... 16

5.0 HISTORY OF FLOODING ............................................................................................ 17

6.0 CONCLUSION ................................................................................................................ 18


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5279 - Killala - Appendix G - FRA_PRINT_Rev2 3 July 2017

1.0 INTRODUCTION

1.1 GENERAL

This Flood Risk Assessment Report has been prepared by Jennings O’Donovan &

Partners Limited for Killala Community Wind Farm Designated Activity Company to

assess flood risk associated with the EIA Development (as defined in Section 1 and 2 of

the REIS / EIAR).

The EIS Development consists of:

“A wind energy development comprising of five electricity generating wind

turbines, each with a rotor diameter not exceeding 103.2m, a hub height not

exceeding 73.5m and a blade tip height not exceeding 126m. The development

will include a meteorological mast not exceeding 82m in height, internal

underground electrical cabling, a 38kv substation building, an external

underground grid connection cable and ducting to the 110kv Tawnaghmore

Upper substation, associated grid substation works, associated site access roads

and ancillary site works including upgrades to the existing site access, a

temporary construction compound and haulage route works. The maximum

output capacity of the wind farm will be up to 18MW and has an intended

operational life of 25 years” (“the EIA Development”).

The Mayo County Development Plan 2014-2020 (“the CDP”) states that:

“It is an objective of the Council to restrict inappropriate development in areas at

risk of flooding (inland or coastal) as identified on flood risk maps, erosion and

other natural hazards or would cause or exacerbate such a risk at other locations.

As part of this, the Planning Authority shall require a Flood Risk Assessment

and/or a Landslide Risk Assessment for any new development” (Flooding and

Soil Erosion Policy FS—01).

As set out in the ‘Renewable Energy Strategy for County Mayo 2011 – 2020’:

“Renewable energy developments must comply with the provisions of the

DEHLG/OPW publication ‘The Planning System and Flood Risk Management:

Guidelines for Planning Authorities 2009’. Sites will be required to avoid areas of

flood risk and that where there is a strategic case for allowing development in

such areas, that these proposals be subject to the’ justification and sequential

tests’ in the Flood Risk Management Guidelines and assessed to ensure that

flood risk can be reduced and mitigated as appropriate”.

“flood risk assessments shall accompany planning applications for renewable

energy developments and these assessments shall be incorporated into the

process of making decisions on planning applications and planning appeals”.


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In accordance with this strategy, a site-specific flood risk assessment has been carried

out for the EIA Development in consideration of the guidance document ‘The Planning

System and Flood Risk Management – Guidelines for Planning Authorities’1.

The assessment methodology involved researching and collating flood related information

from the following data sources:

• Base maps – Ordnance Survey of Ireland;

• Flood Hazard Maps and flooding information for Ireland, (www.floodmaps.ie);

• Office of Public Works (OPW);

• Geological Survey of Ireland (GSI) maps on superficial deposits;

• EPA hydrology maps;

• Western CFRAMS (Catchment Flood Risk Assessment & Management Study);

and

• Mayo County Development Plan 2014 – 2020.

1.2 SCOPE

This Flood Risk Assessment is based on the following:

• Department of Environment, Heritage and Local Government guidelines for

Planning Authorities covering Flood Risk Management (The Planning System and

Flood Risk Management: Guidelines for Planning Authorities 2009’)

• Risk of flooding to the Proposed Development Site and Haul Route Options

(where works are required) from flood flow from neighbouring watercourses.

• Risk of flooding resulting from rainfall.

• Risk of flooding from groundwater generated on the Proposed Development Site

and Haul Route Options (where works are required).

In addition to the above, the study also examined any possible impact the proposed

works may have on the existing drainage regime locally adjacent to the Proposed

Development Site and Haul Route Options (where works are required). The impacts

addressed under this heading comprise:

• The impact of surface water runoff on the flow regimes in neighbouring

watercourses.

• Loss of floodplain.

• Review of historical flood records.

1 Department of Environment, Heritage and Local Government, (2009). The Planning System and Flood Risk Management

– Guidelines for Planning Authorities.


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1.3 STATEMENT OF AUTHORITY

Jennings O’Donovan & Partners Ltd. (“JOD”) Consulting Engineers, were commissioned

on behalf of Killala Community Windfarm DAC to carry out a Flood Risk Assessment of

the proposed EIA Development.

JOD has extensive experience in the development of wind farms from planning through

to construction. JOD have been active in the wind energy market in Ireland since 1998 as

engineering consultants for numerous completed wind farm projects varying from single

wind turbine installations to large scale development which extends to over 2,000MW of

power in Ireland.

This Flood Risk Assessment has been prepared by Mr. Michael Conroy of JOD, who has

undertaken numerous Flood Risk Assessments for projects throughout Ireland. Michael

has 7 years’ experience in the civil engineering and flooding sectors. He has obtained a

Bachelor’s Degree in Civil Engineering and is a Chartered Engineer. Michael previously

worked in the Flood Risk Assessment and Management section of the OPW, and was

involved in the Catchment Flood Risk Assessment and Management Studies (CFRAMS).


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2.0 PLANNING GUIDELINES

In November 2009, the Department of Environment, Heritage and Local Government

issued a guidance document to planning authorities in relation to flood risk management,

titled ‘The Planning System and Flood Risk Management’. These guidelines set out the

policy on development and flood risk in Ireland and provide a framework for the integration

of flood risk assessment into the planning process. The objective is to ensure that flood

risk is considered at all stages of the planning process in order to:

• Avoid inappropriate development in areas at risk of flooding,

• Avoid new developments increasing flood risk elsewhere,

• Ensure effective management of residual risks for development permitted in

flood plains.

The guidelines set out a staged approach for the consideration of flood risk in relation to

developments as follows:

Stage 1: Flood risk identification – to identify whether there may be any flooding

or surface water management issues related to either the area of

regional planning guidelines, development plans and Local Area Plans

(LAP’s) or a proposed development site that may warrant further

investigation at the appropriate lower level plan or planning application

levels;

Stage 2: Initial flood risk assessment – to confirm sources of flooding that may

affect a plan area or proposed development site, 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.

Where hydraulic models exist, the potential impact of a development on

flooding elsewhere and of the scope of possible mitigation measures

can be assessed. In addition, the requirements of the detailed

assessment should be scoped; and

Stage 3: 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.

The guidelines classify developments into three vulnerability classes based on the

effects of flooding:


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• Highly vulnerable development,

• Less vulnerable development,

• Water compatible development.

Electricity generation is classed as highly vulnerable infrastructure. The guidelines also

classify land areas into three flood zones based on the probability of flooding. Flood zones

are defined as follows in the guidelines:

• Zone A is at highest risk. In any one year, Zone A has a 1 in 100 year (1%)

chance of flooding from rivers and a 1 in 200 year (0.5%) chance of flooding

from the sea.

• Zone B is at moderate risk. The outer limit of Zone B is defined by the 1 in

1,000 year (or 0.1%) flood from rivers and the sea.

• Zone C is at low risk. In any one year, Zone C has less than 1 in 1,000 year

(<0.1%) chance of flooding from rivers, estuaries or the sea.

It is stated in the guidelines that during the identification of flood zones, no account should

be taken of any flood relief walls or embankments. In cases where there are insufficient

sites available to locate a development in the appropriate low flood risk zone, the

guidelines allow for consideration of sites within flood risk zones.

This report considers the flood risk of the proposed EIA Development in relation to Stages

1 and 2 of the staged approach outlined above.


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3.0 PROPOSED DEVELOPMENT SITE

3.1 PROPOSED DEVELOPMENT SITE

The Proposed Development Site is located in the townlands of Magherabrack, Mullafarry,

Meelick, Tawnaghmore Lower and Tawnaghmore Upper in County Mayo. The Proposed

Development Site is approximately 1.3km south of Killala (See Figure 1 below). It is

approximately 9.4km north-west of Ballina. The Proposed Development Site is located to

the west of the former Asahi synthetic fibres production facility, whilst the access road

(also included in the Proposed Development Site) runs to the north and east of this facility.

The Proposed Development Site is accessed via the R314 Regional Road which runs

from Killala to Ballina.

Figure 1: Proposed Development Site Location (boundary outlined in red)

The current use of the Proposed Development Site is agricultural grassland. The

Proposed Development Site is relatively elevated in relation to the surrounding area at

approximately 61m AOD. The Proposed Development Site slopes downwards in a

northern direction at approximately 1/18.

3.2 HAUL ROUTE OPTIONS

Jennings O’Donovan carried out a haul route assessment for the delivery of turbine

components between Killybegs Harbour and the Proposed Development Site. Two haul

route options were identified:

• Haul Route via Bunniconlan


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• Haul Route via Swinford

The two haul routes are illustrated in Figure 2 below, along with seven areas where

material construction works would be required prior to deliveries. A larger version of Figure

2 is included in Appendix 1 of this report.

Figure 2: Haul Route Options


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4.0 FLOOD RISK REVIEW

4.1 APPROACH

The risk of flooding to the Proposed Development Site and Haul Route Options shall be

assessed in relation to the following criteria:

• Fluvial Risk: Inundation from flow from neighbouring watercourses

• Pluvial Risk: Flooding due to direct rainfall

• Groundwater Risk: Flooding due to a high-water table

• History of Flooding

• Available Predictive Flood Risk Mapping

• Impact of presence of the proposed development on the existing flood risk regime

at the proposed site

4.2 FLUVIAL FLOOD RISK

A review of the local hydrology was carried out and a number of watercourses in close

proximity to the Proposed Development Site were identified. The River Moyne flows along

the eastern extent of the Proposed Development Site, adjacent to the R314. This river

flows in a northern direction past the Proposed Development Site, before changing its

direction of flow to a north-western direction and entering Killala Bay via Abbeylands

Townland. The proposed access point to the Proposed Development Site will cross this

river. The Mullafarry Stream and Tawnaghmore-Lower Stream are located to the north of

the Proposed Development Site. The Mullafarry Stream is a tributary of the River Moyne,

and flows generally in an eastern direction until it joins the River Moyne. The

Tawnaghmore-Lower Stream is a tributary of the Townplots-West River, which flows

generally in a northern direction and enters Killala Bay at Kilroe Townland. The

Tawnaghmore-Lower Stream flows adjacent to the Proposed Development Site in a

western direction before joining the Townplots-West River.

Figure 3: Nearby Watercourses (Red dot indicates site location)


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The Moyne Stream and the Medown Stream are located to the south of the Proposed

Development Site. The Moyne Stream flows generally in a north-eastern direction before

joining the Moyne River. The Medown Stream flows in a southern direction for a short

distance, before changing its direction of flow to a western direction and joining the

Magherabrack River. The Magherabrack River is located to the west of the Proposed

Development Site and flows in a northern direction, before changing to flow in a north-

western direction and joining the Cloonaghmore River which enters Killala Bay via

Rathfran Bay. The Rathowen-East Stream is also located to the west of the Proposed

Development Site, and flows in a south-western direction before joining the Magherabrack

River.

It is noted that no river or stream flows through the centre of the Proposed Development

Site indicating that the Proposed Development Site is located on a watershed boundary

between catchments. EPA mapping2 confirms that the Proposed Development Site is split

between two river sub-basins, as defined by the water framework directive (see Figure 4

below). The access road at the western extent of the site is located in the Moyne sub-

basin, while the remaining site area is located in the Cloonaghmore sub-basin.

Figure 4: EPA Sub-Catchment Mapping (Red dot indicates site location)

Preliminary Flood Risk Assessment (“PFRA”) mapping was produced by the OPW for the

Republic of Ireland. The PFRA mapping was completed prior to the carrying out of the

Catchment Flood Risk Assessment and Management Studies (“CFRAM”) studies and the

2 Gis.epa.ie, EPA Map Viewer. [Online] Available at: http://gis.epa.ie/Envision [Accessed 3rd July 2017].


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production of the more accurate CFRAM flood maps. It should be noted that the predicted

extent of flooding illustrated on the PFRA maps was developed using a low resolution

digital terrain model (“DTM”). Therefore, the PFRA maps are intended to be indicative

only. Figure 5 below shows an extract from the PFRA mapping for the Proposed

Development Site.

Figure 5: PFRA Map Extract for the Proposed Development Site

It is noted that the Proposed Development Site is elevated between all the watercourses

identified above. While the PFRA mapping indicates a peak flood level of approximately

30m AOD for the 0.1% AEP on the River Moyne adjacent to the site entrance, the ground

level rises relatively quickly from a height of 30.5m AOD at the site entrance to over 61m

AOD further up the site. Given the elevation of the Proposed Development Site with

respect to the closest watercourses and the position of the Proposed Development Site

on a local watershed, the risk of fluvial flooding is considered to be minimal. It is

considered that the site can be placed in Flood Zone C as defined in Section 2 above.

The PFRA mapping was also used to assess the fluvial flood risk at locations along the

two potential haul routes where material construction works would be required. There are

three locations where road widening will be required in areas that are at risk from fluvial

flooding (see Appendix 1 - Points A, D & F). At Point A, road widening will be required

along the western edge of the R294, which is within the 1% AEP flood extent of the River

Eighnagh. It is noted that the existing road verge has approximately the same elevation

as the existing road surface. Therefore, no loss of floodplain is envisaged at this location.


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At Point D, road widening will be required along the northern edge of the R294, which is

within the 1% AEP flood extent of the River Srafaungal. It is noted that the existing road

verge has a higher elevation than the existing road surface. Therefore, no loss of

floodplain is envisaged at this location. At Point F, a turning area will be required along

the north-western verge of the N26, adjacent to the River Moy. The 1% AEP flood extent

encompasses the south-eastern verge of the road, but does not extend to the north-

western verge, where the turning area will be constructed. Therefore, no loss of floodplain

is envisaged at this location. In summary, it is deemed that the proposed road widening

works will not add to the level of fluvial flood risk in the catchment.

4.3 PLUVIAL FLOOD RISK

As mentioned in Section 3 above, the Proposed Development Site is relatively elevated

in relation to the surrounding area at approximately 61m AOD. The Proposed

Development Site slopes in a northern direction at approximately 1/18. The proposed EIA

Development will increase the impermeable area of the Proposed Development Site and

therefore, surface water runoff from the Proposed Development Site will be increased.

This can present an increased risk of pluvial flooding on site and downstream if not

managed correctly.

As outlined in Chapter 7 of the EIAR, the average annual rainfall for this region is

1244.8mm, with a runoff rate of approximately 477mm/yr. The proposed drainage

techniques provide for source control of surface water generated on the impermeable

areas of the Proposed Development Site through the use of drainage ditches and

settlement ponds with buffered outfalls. The site surface water drainage system will be

designed to best practice to provide protection from pluvial flooding.

The OPW’s pluvial flood mapping3 was examined to determine if there was an existing

risk from pluvial flooding at the Proposed Development Site (see Figure 6 below). The

pluvial flood mapping shows that there is an existing risk from pluvial flooding at a number

of locations along the northern and western extents of the Proposed Development Site.

However, it is not proposed to locate any of the wind turbines or associated infrastructure

at these locations. It is proposed to install new surface water drainage ditches adjacent to

all of the proposed turbine hardstands to mitigate the risk of pluvial flooding.

3 www.myplan.ie, Myplan. [Online] Available at: http://www.myplan.ie/webapp/ [Accessed 3rd July, 2017].


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Figure 6: Pluvial Flood Mapping for the Proposed Development Site

The use of SuDS techniques will ensure that the natural drainage patterns are replicated

and no negative impacts result from this development in terms of water quality or quantity.

The pluvial flood mapping was also used to determine if there was an existing risk from

pluvial flooding at locations along the two potential haul routes where material construction

works would be required. The pluvial flood mapping confirmed that none of the locations

where works are required are at risk from pluvial flooding.

4.4 GROUNDWATER FLOOD RISK

The Geological Survey of Ireland (“GSI”)4 mapping indicates that the Proposed

Development Site is underlain by the Ballina Limestone Formation that comprises

limestone and shale. The bedrock is indicated to contain a locally important aquifer. The

GSI mapping indicates that the Proposed Development Site is underlain by till derived

from limestone, with some rock outcrops. The groundwater vulnerability was determined

to be extreme, indicating that the soil thickness is minimal. See Figure 7 below.

4 www.gsi.ie, GSI Spatial Resources. [Online] Available at: http://www.gsi.ie/Mapping.htm [Accessed 3rd July, 2017]


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Figure 7: Groundwater Vulnerability Mapping for the Subject Site

A site investigation survey was carried out by Whiteford Geoservices Ltd in September

2015. The results of the survey showed that the Proposed Development Site is underlain

by fine grained sedimentary rock of the Ballina Limestone Formation. Approximately

0.11m – 2.5m of glacial soils overlies limestone. It was noted that groundwater was

generally not encountered on the site, and only low volumes of water would be anticipated

at construction stage.

As discussed in Section 4.3, it is proposed to install surface water drainage ditches

adjacent to the proposed hardstand areas. This drainage approach will help to lower the

level of the water table on site and mitigate against the risk of flooding due to groundwater.

The OPW’s groundwater flood mapping5 was examined to determine if there was an

existing risk from groundwater flooding at locations along the two potential haul routes

where material construction works would be required. The groundwater flood mapping

confirmed that none of the locations where works are required are at risk from

groundwater flooding.

4.5 AVAILABLE PREDICTIVE FLOOD RISK MAPPING

As part of Ireland’s obligations under the EU ‘Floods’ Directive, the Office of Public Work

(“OPW”) have generated new mapping to provide predictive estimates of the extent of

floodplains as part of the Catchment Flood Risk Assessment and Management Studies

(“CFRAMS”). This programme was undertaken on a River Basin District level. The

Proposed Development Site is located within the Western CFRAMS area.

5 www.myplan.ie, Myplan. [Online] Available at: http://www.myplan.ie/webapp/ [Accessed 3rd July, 2017].


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As set out in section 4.2, the Proposed Development Site was reviewed against the PFRA

mapping which confirmed that the Proposed Development Site is located within Flood

Zone C. As part of the PFRA mapping stage, the OPW identified a list of Areas of Further

Assessment (“AFA’s”). These areas were identified through the use of Geographical

Information Systems (GIS), which allowed receptors to be overlain on indicative flood

maps. Flood risk assessments were then carried out in each of the AFA’s as part of the

CFRAMS. It is noted that Killala was not identified as an AFA during the PFRA mapping

stage and therefore, a flood risk assessment was not carried out during the CFRAM’s

process. This indicates that flooding was not identified by the OPW as a significant issue

in the Killala area.

4.6 IMPACT OF DEVELOPMENT ON CURRENT FLOOD REGIME

All surface water runoff from the Proposed Development Site will be collected in a

dedicated drainage network. Sustainable Drainage Systems (“SuDS”) will be

implemented to provide elements of source control of surface water, attenuation of runoff

and water quality improvements. The site surface water drainage system will be designed

to best practice to provide protection from surface runoff due to direct rainfall. The

Proposed Development Site is not located in a floodplain, ensuring that the EIA

Development will not result in any loss of floodplain.

As discussed in Section 4.2, there are three locations where road widening will be required

in areas that are at risk from fluvial flooding (see Appendix 1 - Points A, D & F). However,

in each case the proposed works will not result in a loss of floodplain. Therefore, it is

deemed that the proposed road widening works will not add to the level of flood risk in the

catchment.

4.7 SUMMARY OF FLOOD RISK

Table 1 below provides a summary of the flood risk at the Proposed Development Site

and at locations along the Haul Route Options where construction works will be required.


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Source Pathway Receptor Comment

Tidal Not applicable Land &

Infrastructure

The Proposed Development Site is over 1.5km from the coast and therefore, there is no risk of coastal flooding. There is no risk of coastal flooding at any of the locations that require construction works along the Haul Route Options.

Fluvial Overbank

Land & Infrastructure

The risk of fluvial flooding at the Proposed Development Site is minimal. There are three locations along the Haul Route Options where construction works will be required in areas at risk from fluvial flooding. However, there will be no loss of floodplain.

Pluvial Ponding of

Rainwater on site


There is an existing risk of pluvial flooding at the Proposed Development Site. However, it is proposed to install new surface water drainage ditches adjacent to all of the proposed turbine hardstands to mitigate the risk. There is no risk of pluvial flooding along the Haul Route Options.

Groundwater Rising

Groundwater Levels


Based on the GSI mapping, OPW mapping and site investigation, there is no apparent risk from groundwater flooding at the Proposed Development Site or along the Haul Route Options.

Table 1: Flood Risk Summary Table

5.0 HISTORY OF FLOODING

The OPW Flood Hazard Maps website6 was consulted in relation to available historical or

anecdotal information on flooding incidents in the vicinity of the Proposed Development

Site. This website includes all available flood records held by the OPW, local authorities

and other relevant state organisations such as the EPA.

Minutes of a meeting held on 13th April 2006 between Mayo County Council and the

Electricity Supply Board International (“ESBI”) refer to flooding in the Greenpark area of

Killala, stating that the road floods “once or twice a year due to high tides”. The Greenpark

Area is located on the northern side of Killala, and is not in close proximity to the subject

6 www.floodmaps.ie, National Flood Hazard Mapping. [Online] Available at: http://www.floodmaps.ie/View/Default.aspx

[Accessed on 3rd July 2017]


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site. There is no information provided on flooding at the Proposed Development Site or

the existing Killala Business Park.

Minutes of a meeting held on 15th December 2005 between Sligo County Council and the

Electricity Supply Board International (“ESBI”) refer to road flooding on the R294 in the

vicinity of Lough Talt. This is an area where construction works would be required on the

Bunniconlan Haul Route Option.

6.0 CONCLUSION

There is minimal risk of fluvial flooding at the Proposed Development Site. It is reasonable

to conclude that the site lies within Flood Zone C as defined by the guidance document

‘The Planning System and Flood Risk Management’. There is an existing risk of pluvial

flooding at the Proposed Development Site. However, with the EIA Development

infrastructure being located away from the more sensitive areas and construction of an

adequate drainage system, this risk has been mitigated. The proposed works include a

drainage system to collect and convey runoff to the existing drainage system responsibly.

This research has concluded that there is no record of flooding previously occurring on

this Proposed Development Site. The Proposed Development Site is not located in a

floodplain; therefore, the proposed works will not result in a loss of floodplain. The

proposed works are unlikely to increase the current flood risk in this catchment.

There is a risk of fluvial flooding at three locations where road widening will be required

along the Haul Route Options (see Appendix 1 - Points A, D & F). However, in each case

there will be no loss of floodplain. Therefore, it is deemed that the proposed road widening

works will not add to the level of fluvial flood risk in the catchment.

The conclusion of this FRA is that the Proposed Development Site and Haul Route

Options are not at a significant risk of flooding (fluvial, pluvial or groundwater) and the

proposed works will not result in any significant change in risk or flooding regime.

Additionally, the Development is deemed to be appropriate (as set out in Table 3.2 of the

guidelines for Flood Risk Management (DoEHLG/OPW, 2009). As such, no further stages

of flood risk assessment are therefore required.


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APPENDIX 1

Met Eireann Return Period Rainfall Depths for sliding Durations Irish Grid: Easting: 119640, Northing: 328125,

Interval | YearsDURATION 6months, 1year, | 2, 3, 4, 5, 10, 20, 30, 50, 75, 100, 150, 200, 250, 500, 5 mins 2.4, 3.5, | 4.1, 5.1, 5.8, 6.3, 8.1, 10.1, 11.5, 13.5, 15.3, 16.7, 18.9, 20.6, 22.1, N/A , 10 mins 3.3, 4.9, | 5.8, 7.1, 8.1, 8.8, 11.2, 14.1, 16.0, 18.8, 21.3, 23.3, 26.3, 28.8, 30.8, N/A , 15 mins 3.9, 5.8, | 6.8, 8.4, 9.5, 10.3, 13.2, 16.6, 18.9, 22.1, 25.1, 27.4, 31.0, 33.8, 36.2, N/A , 30 mins 5.1, 7.5, | 8.8, 10.8, 12.2, 13.2, 16.8, 20.9, 23.6, 27.5, 31.1, 33.8, 38.2, 41.5, 44.3, N/A , 1 hours 6.8, 9.8, | 11.4, 13.9, 15.6, 16.9, 21.3, 26.2, 29.6, 34.3, 38.5, 41.8, 47.0, 51.0, 54.3, N/A , 2 hours 9.0, 12.8, | 14.8, 17.9, 20.0, 21.6, 26.9, 33.0, 37.0, 42.7, 47.8, 51.7, 57.8, 62.6, 66.5, N/A , 3 hours 10.6, 14.9, | 17.2, 20.7, 23.1, 24.9, 30.9, 37.8, 42.3, 48.6, 54.2, 58.6, 65.3, 70.5, 74.9, N/A , 4 hours 11.9, 16.7, | 19.2, 23.0, 25.6, 27.6, 34.1, 41.5, 46.4, 53.2, 59.3, 64.0, 71.2, 76.8, 81.4, N/A , 6 hours 14.0, 19.5, | 22.4, 26.7, 29.6, 31.9, 39.2, 47.5, 52.9, 60.5, 67.2, 72.4, 80.4, 86.6, 91.7, N/A , 9 hours 16.5, 22.7, | 26.0, 31.0, 34.3, 36.8, 45.1, 54.3, 60.3, 68.8, 76.2, 82.0, 90.8, 97.6, 103.2, N/A ,12 hours 18.5, 25.4, | 29.0, 34.4, 38.0, 40.8, 49.7, 59.7, 66.3, 75.3, 83.4, 89.5, 99.0, 106.3, 112.3, N/A ,18 hours 21.8, 29.6, | 33.8, 39.9, 43.9, 47.0, 57.1, 68.3, 75.6, 85.7, 94.5, 101.4, 111.8, 119.8, 126.4, N/A ,24 hours 24.5, 33.1, | 37.6, 44.3, 48.7, 52.1, 63.0, 75.1, 83.0, 93.8, 103.4, 110.7, 121.8, 130.4, 137.5, 161.8, 2 days 31.7, 41.5, | 46.5, 53.8, 58.6, 62.2, 73.8, 86.3, 94.3, 105.3, 114.8, 122.0, 133.0, 141.3, 148.1, 171.4, 3 days 38.0, 48.8, | 54.3, 62.2, 67.3, 71.2, 83.4, 96.6, 104.9, 116.2, 125.9, 133.3, 144.4, 152.8, 159.6, 182.9, 4 days 43.8, 55.6, | 61.5, 69.9, 75.3, 79.5, 92.3, 106.0, 114.7, 126.3, 136.4, 143.9, 155.2, 163.8, 170.7, 194.1, 6 days 54.6, 68.1, | 74.7, 84.1, 90.1, 94.6, 108.6, 123.4, 132.6, 145.0, 155.6, 163.5, 175.3, 184.2, 191.3, 215.4, 8 days 64.8, 79.7, | 86.9, 97.2, 103.7, 108.6, 123.6, 139.3, 149.1, 162.2, 173.2, 181.5, 193.8, 203.0, 210.4, 235.2, 10 days 74.6, 90.8, | 98.6, 109.6, 116.5, 121.8, 137.7, 154.3, 164.6, 178.3, 189.8, 198.4, 211.1, 220.6, 228.3, 253.7, 12 days 84.1, 101.5, | 109.8, 121.5, 128.9, 134.4, 151.3, 168.6, 179.4, 193.6, 205.6, 214.5, 227.6, 237.4, 245.3, 271.4, 16 days 102.6, 122.2, | 131.5, 144.4, 152.6, 158.6, 177.0, 195.8, 207.3, 222.6, 235.4, 244.8, 258.7, 269.0, 277.3, 304.7, 20 days 120.7, 142.2, | 152.4, 166.4, 175.2, 181.8, 201.5, 221.6, 233.9, 250.0, 263.5, 273.4, 288.0, 298.8, 307.5, 335.9, 25 days 142.9, 166.7, | 177.8, 193.2, 202.7, 209.8, 231.1, 252.6, 265.7, 282.8, 297.1, 307.6, 322.9, 334.3, 343.3, 373.0,NOTES:N/A Data not availableThese values are derived from a Depth Duration Frequency (DDF) ModelFor details refer to:’Fitzgerald D. L. (2007), Estimates of Point Rainfall Frequencies, Technical Note No. 61, Met Eireann, Dublin’, Available for download at www.met.ie/climate/dataproducts/Estimation-of-Point-Rainfall-Frequencies_TN61.pdf

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