HomeMy WebLinkAbout2660120 - F.I. Received Doc. - Flood risk assessment26/387 TE
25th June 2026
Monaghan County Council
Planning Department
Dublin Street
Monaghan
Re: Planning and Development Act 2000 (as amended).
Planning and Development Regulations 2001 (as amended).
26/60120 - permission consequent on the grant of outline permission Ref: 24/60201, at Acres (DED
Ballybay Rural) & Annaneese, Ballybay, Co. Monaghan. The development will consist of
construction of a two-storey dwelling house & detached domestic garage, with proprietary
wastewater treatment system along with other associated ancillary site works & new site access.
Said application contains a Site-Specific Flood Risk Assessment Report at Acres (DED Ballybay
Rural) & Annaneese Ballybay Co. Monaghan.
Dear Sir/Madam,
I refer to your letter dated 8th May 2026, we now comment as follows
Item 3 - Section 15.22.8 of the Monaghan County Development Plan 2025-2031 states that all
development proposals in flood risk areas should be supported with a site-specific Flood Risk Assessment
(FRA), in accordance with the DECLG, The Planning System and Flood Risk Management Guidelines for
Planning Authorities (2009) and Departmental Circular PL2/2014.
The Office of Public Works (OPW) Preliminary Flood Risk Assessment (PFRA) maps indicate that part of the
application site is vulnerable to pluvial flooding events. Although the associated Outline Planning
Application was accompanied by a Site-Specific Flood Risk Assessment, it is noted that this report has
not been re-submitted. Having reviewed the information, the Planning Authority has concerns with the
orientation and position of the proposed dwelling, which appears to conflict with the proposed area of
compensatory storage, as per the Outline Permission and the associated Site-Specific Flood Risk
Assessment.
In this regard, and taking account of the Further Information and amendments requested under Point 1
and Point 2 above, the Applicant shall submit a new Site-Specific Flood Risk Assessment for the proposed
development, completed by a competent professional with hydrological experience, confirming that the
development:
• Will not be at risk of flooding
• Will not exacerbate flooding in the immediate vicinity or wider area. RECEIVED: 21/07/2026
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• Will not obstruct or impede important flow paths
• Will not result in residual risks to the area and/or development that cannot be managed to an
acceptable level.
The flood risk assessment shall also clearly demonstrate proposed management of any residual risks.
Response –
Introduction
This Technical Memorandum has been prepared in response to Item 3 of the Further Information request
issued by Monaghan County Council dated 08 May 2026.
The Planning Authority noted that the associated Outline Planning Application was accompanied by a
Site-Specific Flood Risk Assessment (Hydrec Environmental Consulting, Report No. 15322-01, dated 18
December 2023), however expressed concern that the revised orientation and position of the proposed
dwelling may conflict with the compensatory flood storage area identified within that assessment.
The purpose of this memorandum is to review the revised site layout and confirm whether the findings
and conclusions of the existing Site-Specific Flood Risk Assessment remain applicable.
Existing Flood Risk Assessment
The existing Site-Specific Flood Risk Assessment was prepared in accordance with The Planning System
and Flood Risk Management Guidelines for Planning Authorities (2009) and included a detailed Stage 3
Flood Risk Assessment using a site-specific two-dimensional hydraulic model.
The assessment concluded that:
• the site is not at risk from fluvial or coastal flooding;
• the only flood mechanism affecting the site is pluvial flooding;
• the modelled 1% Annual Exceedance Probability (AEP) event including a 20% climate change
allowance results in a maximum flood level of 93.6 m AOD;
• the proposed finished floor level of 94.6 m AOD provides 1.0 m freeboard above the modelled
flood level;
• compensatory flood storage has been incorporated on a level-for-level basis to offset the loss of
flood storage resulting from the proposed development; and
• subject to the proposed mitigation measures, the development will not increase flood risk
elsewhere and will not be at risk of flooding.
Review of Revised Site Layout
The revised site layout has been reviewed against the findings and recommendations contained within
the original Flood Risk Assessment. RECEIVED: 21/07/2026
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The proposed dwelling has been repositioned within the application site in response to the planning
authority's landscape and siting requirements. The proposed finished floor level remains unchanged at
94.6 m AOD.
The revised dwelling position does not alter the flood mechanism previously identified for the site, namely
localised pluvial flooding within the lower-lying southern portion of the site.
The compensatory flood storage area identified within the original Flood Risk Assessment has also been
reviewed. The revised dwelling location does not alter or encroach upon the proposed compensatory
storage area, which remains available to provide the level-for-level flood storage compensation
identified within the original assessment.
Accordingly, the mitigation strategy previously developed as part of the Flood Risk Assessment remains
applicable.
Development will not be at risk of flooding
The original hydraulic modelling established a maximum design pluvial flood level of 93.6 m AOD for the
1% AEP event including climate change allowance.
The proposed dwelling and detached garage continue to have a finished floor level of 94.6 m AOD,
providing approximately 1.0 m freeboard above the modelled flood level.
The revised layout therefore does not increase flood risk to the proposed development.
Development will not exacerbate flooding in the immediate vicinity or wider area
The original Flood Risk Assessment incorporated level-for-level compensatory flood storage in
accordance with The Planning System and Flood Risk Management Guidelines for Planning Authorities
(2009).
The revised layout has been reviewed and the compensatory storage area remains unaffected by the
revised dwelling location. Consequently, the mitigation measures previously proposed remain available
to offset the loss of flood storage associated with the development.
Accordingly, the revised proposal will not increase flood risk or exacerbate flooding within the immediate
vicinity or wider catchment.
Development will not obstruct or impede important flow paths
The revised dwelling location does not obstruct or impede the overland pluvial flow paths identified within
the original hydraulic assessment.
The source and pathway of pluvial floodwaters remain unchanged from those previously assessed.
RECEIVED: 21/07/2026
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Development will not result in unacceptable residual flood risk
Residual flood risks remain unchanged from those identified within the original Flood Risk Assessment.
These risks continue to be managed through:
• maintaining a finished floor level of 94.6 m AOD;
• provision of level-for-level compensatory flood storage;
• maintaining the proposed site access outside the modelled flood area; and
• locating the wastewater treatment system outside the predicted flood extent.
Conclusion
The revised site layout has been reviewed in the context of the Site-Specific Flood Risk Assessment
prepared by Hydrec Environmental Consulting (Report No. 15322-01).
While the dwelling has been repositioned within the application site, the revised layout does not
materially alter the findings or conclusions of the original Flood Risk Assessment.
The proposed finished floor level remains 1.0 m above the modelled 1% AEP plus climate change flood
level, the compensatory flood storage area remains unaffected by the revised layout, and the original
mitigation measures remain applicable.
It is therefore concluded that the revised proposal:
• will not be at risk of flooding;
• will not exacerbate flooding in the immediate vicinity or wider area;
• will not obstruct or impede important flow paths; and
• will not result in residual flood risks that cannot be managed to an acceptable level.
Accordingly, it is considered that the findings and conclusions of the Site-Specific Flood Risk Assessment
(Hydrec Environmental Consulting, Report No. 15322-01) remain valid and applicable to the revised
development proposal.
Should you require any further information, please do not hesitate to contact me.
Yours sincerely,
Nevin Traynor
BSc Env, HDIP IT, Cert SHWW, IAH RECEIVED: 21/07/2026