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HomeMy WebLinkAbout2560309 - F.I. Received Doc. - Application - Cover Letter CONSULTING ENGINEERS BUILDING SURVEYORS DESIGN CONSULTANTS Tel: 042-9746492 Fax: 042-9746511 Email: info@cspringle.com Website: www.cspringle.com Registered Office: Monaghan Road, Castleblayney, Co. Monaghan. Incorporated in Ireland: Reg No 640491 MNK Engineering Ltd trading as C S Pringle Page 1 of 23 Revised Flood Risk Assessment Newgrove Incorporating response to FI requested by MCC Researched by: Marcus Dancey BSc (Eng), Dip Eng, CEng MIEI, FConsEI Chartered Engineer C S Pringle Monaghan Road, Castleblayney A75 EP84 Co Monaghan Date: 7th November 2025 Requested by: Gallinagh Poultry Farms Ltd to support a planning application to Monaghan Co. Co. for the infilling of ground at Newgrove Location Address: Newgrove, Monaghan. Co. Monaghan. RECEIVED: 02/07/2026 Page 2 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Background As part of a submission for planning a Site-Specific Flood Risk Assessment was submitted. MCC then requested Further Information FI dated 29th September 2025 as below. As a result, the Flood risk assessment has been revised so that this revised report provides additional clarification to deal with the MCC FI request which requested inter alia as follows: “The office of Public Works (OPW) Preliminary Flood Risk Assessment (PFRA) maps indicate that a significant portion of the proposed site is vulnerable to pluvial flooding. Section 15.22.8 ‘Flood Zones and Appropriate Uses’ of the Monaghan County Development Plan 2015-2031, states that Monaghan County Council will restrict development in areas susceptible to flooding except where: a. The proposed development can be justified on strategic grounds. b. The proposed development has addressed the flooding concerns which exist. c. The flood risk can be managed to an acceptable degree and without increasing flood risk beyond the site itself. d. Appropriate and detailed mitigation measures can be implemented to remove/minimize flood effects. It is considered that the submitted site specific flood risk assessment does not give sufficient consideration to the potential effects of the loss of pluvial storage from the site and issues arising from displacement of this storage. The applicant is requested to submit revised flood risk assessment which sufficiently demonstrates compliance with criteria a) to d) listed above and which addresses the issues of pluvial flooding, the loss of pluvial storage on the site and the potential to create or exacerbate flooding elsewhere outside the sited due to displacement of pluvial storage. The revised flood risk assessment should also include the following: (i) Confirmation of the proposed classes of activity and type of materials to be used for the infilling of the lands. (ii) Information to clearly demonstrate that the characteristics of the imported subsoil/material, which will impact on water storage and flood risk, have been taken into account. (iii) Information to clearly demonstrate why a runoff risk index/WRAP value of 3 has been chosen. RECEIVED: 02/07/2026 Page 3 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers (iv) A revised topographical survey using Arc3d modelling or similar, to demonstrate approximate available space, in tonnages per cross section.” It also requests that the applicant is invited to review the content of a third-party submission that was received and to respond to the issues raised. Summary In brief this revised Flood Risk Assessment will show that it is not appropriate for MCC to place reliance upon the OPW Preliminary Flood Risk Assessment (PFRA) pluvial mapping extents to conclude that pluvial flood risk exists or that it exists to the extent shown on said mapping. The maps were originally prepared solely for the purpose of carrying out the first cycle PFRA and they have had limited if any application beyond that. The limitation of the mapping is due to the fact that no account was taken of sub surface artificial drainage networks. The OPW “advice to planning authorities has been that the PFRA indicative pluvial maps are not considered to be reliable for the purposes of zoning or decision making.” (See extract from OPW email in Appendix 2.) The pluvial flood extents effectively take a hollow or depression in the ground (referred to hereafter as a “basin”) indicated by LiDAR mapping and assumed little or no drainage infrastructure from said basin so that the maximum extent of the flooding shown is that of a lake forming to the level where it overspills the lowest point of the rim of the basin. If a 300mm pipe had been installed, then no pluvial flooding would take place as the flow of water into the basin would be matched at all times by the volume of water exiting. As it is the 225mm concrete pipe that has been installed slightly throttles the maximum flow from the basin but is large enough to limit the maximum extent of flooding so that it barely encroaches on the subject property. A sliver of land on the subject property is shown to be within the extents for a 100-year plus climate change (CC) but the toe of the proposed infill embankment does not encroach on these the flood extent. As a result, no displacement of water will result from the proposed filling. If no flooding exists within the footprint of the proposed infill material, then no flooding needs to be managed and if no displacement of flood storage takes place, then no transfer of risk takes place and appropriate and detailed mitigation measures to remove/minimize flood effect are not required. However, for purposes of ensuring that any runoff from the inert material being stored it is proposed to place a toe drain along the base of the embankment and said drain will have the impact of increasing the flood storage available which will slightly lower the level to which water will rise to. RECEIVED: 02/07/2026 Page 4 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Dealing with the items requested above in order as follows: (i) Confirmation of the proposed classes of activity and type of materials to be used for the infilling of the lands. The proposed classes of activity is 5 & 6 if done under a certificate of registration or waste facility permit. This may also be done under Article 27 EPA notification using by-product. The type of material used for infilling the lands is inert material or By-product or as otherwise described in the attached breakdown of materials to be used. (ii) Information to clearly demonstrate that the characteristics of the imported subsoil/material, which will impact on water storage and flood risk, have been taken into account. As the imported subsoil material is shown not to encroach on the 100-year +CC of the flood extents water storage is not displaced and no transfer of flood risk takes place. (iii) Information to clearly demonstrate why a runoff risk index/WRAP value of 3 has been chosen. A WRAP value of 3 has been chosen because the site in question is located in an area with a WRAP value of 3. (iv) A revised topographical survey using Arc3d modelling or similar, to demonstrate approximate available space, in tonnages per cross section.” Materials are proposed to be imported into the site. The volume of materials is approximately 6365m³ depending on the suitability of material excavated on site. Assuming the imported inert material has a density of around 1.4 tonnes/m³, there will be approximately 7,500-10,000 tonnes of inert material to be imported to site. A section near the end of this report addresses directly the content of the third-party submission. RECEIVED: 02/07/2026 Page 5 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Flood Risk Assessment. Our client, the applicant, wishes to allow a portion of his land to be infilled with inert material. An outdated OPW Preliminary Flood Risk Assessment (PFRA) has been used to indicate that the area where infilling is proposed is at risk of pluvial flooding. The extents given of the flooding effectively show the basin to be filled to capacity or maximum flooding. See following map where the flooding is shown extending into the subject site proposed to be filled. Screenshot shows the location of the area to be filled superimposed on the OPW PFRA of pluvial flooding. The PFRA shows that the site in question is not impacted by fluvial flooding which is shown in blue. This PFRA pluvial mapping and indicated pluvial flood extents were obtained by use of Lidar to determine the topography of the ground and shows up as a depression or a basin. The Assessment assums no underground infrastructure to convey the water from the basin. The OPW “advice to planing authorities has been that the PFRA indicative pluvial maps are not considered to be reliable for the purposes of zoning or decision- making.” RECEIVED: 02/07/2026 Page 6 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers The following screenshot shows how runoff from the catchment area surrounding the subject site behaves. Rainwater runoff flows across fields within the catchment area of the basin which in turn is serviced by a 31m section of concrete 225 pipe from C to D on the neighbouring property and by a 27m length of twin-wall pipe 250mm in diameter shown from D to E on the Applicant’s lands. (Conservatively the characteristics of the pipe has been assumed as a 225mm for the entire length from C to E. If one were to take the actual pipe sizes, then more water could be conveyed through the system than has been assumed resulting in a lower storage volume required and lower flood extents.) The flow characteristics of the concrete 225mm diameter pipe flowing freely are such that the pipe is not sufficient to take the full flow from the catchment for low probability events and so for these events the pipe effectively acts as a throttle to the flow causing water to back up to form an area of temporary flooding. Such flooding occurs only for short periods of time following very heavy rainfall and quickly dissipates. Such flooding will occur regardless of whether or not the proposed development takes place. Catchment area used by IH124 as determined accurately using LiDAR data. The area is 8.6Ha which makes IH124 the most suitable no-records formula for calculating the runoff. North is up. RECEIVED: 02/07/2026 Page 7 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Screenshot shows the location of the subject site outlined in blue in relation to the adjacent site to the east. The low point of the subject site is shown at A and runoff from the field naturally drains across the neighbouring property via an open sheugh from A to B. From there it flows in an open sheugh located along a hedge from B to C where it enters a pipe which drains to an outfall at E via D and from there it flows in an open sheugh to enter the Ulster Blackwater River at F. The contributing catchment area to the location is 8.597Ha hereinafter assumed to be 8.6 hectares. North is up. In our analysis the system is modelled as an attenuation design problem where the conservative assumption is made that the average flow from the catchment for a given storm duration arrives instantly at the subject area at the beginning of the rainfall event and stops immediately upon the rain ceasing. With any attenuation calculation the total amount of water flowing into the subject area in a particular time duration is calculated knowing the area of the catchment contributing, the percentage impermeability of the catchment, the depth of rainfall that falls within that time for a design return period and the total amount of water leaving the site is calculated knowing the characteristics of the pipe infrastructure draining the area and the head involved to provide the energy for the flow. IH 124 no-records equation is used to estimate the maximum volume of water that flows from this catchment through the basin for a 100-year storm with a 1.2 climate change multiplier used in the calculations. RECEIVED: 02/07/2026 Page 8 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Table gives the calculation of the maximum flow expected from the catchment. The Qbar figure is 44.4lts/s and this is multiplied by 1.2 to account for climate change which gives 53.2lts/s and this is multiplied by the Irish growth factor of 1.96 to give a 100-year plus CC maximum flow of 104.1lts/s. The calculation used a catchment area of 8.6 hectares, an AAR of 999mm and a Soil factor G of 0.4 for a WRAP location of 3. IH 124 is a 3-variable no records equation which requires the area of the catchment, the annual average rainfall (AAR), and a value for the winter rainfall acceptance potential (WRAP) of the soil to arrive at a Qbar figure which is the average annual maximum flow. The area has been measured as 8.59Ha rounded to 8.6Ha and the extent of the catchment has been obtained accurately from contours and is shown on a previous page. The AAR is 999mm for taken from MET Eireann figures for the location. The WRAP value is 3 from WRAP maps, so the soil value G is taken as 0.4. RECEIVED: 02/07/2026 Page 9 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Screenshot shows the rainfall for this location as 999mm as per Met Eireann figures for the location E265000, N335000 Irish grid coordinates. Screenshot shows the location of the site within the WRAP value of 3 which corresponds to a G value of 0.4 within the IH124 equation. This answers 1. (iii) of the additional information. RECEIVED: 02/07/2026 Page 10 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers To determine the impermeability factor of the catchment the time of concentration (ToC) needs to be calculated. The ToC is the time it takes water falling on the extremity of the catchment at the beginning of a rainfall event to arrive at a point of consideration (the pipe entry point). The ToC gives us the earliest time that the entire catchment comes into play. A longer time than the ToC will not mobilise any greater catchment area but will have a lesser rainfall intensity and so will produce a lesser flow. A shorter time than the time of concentration will have a more intense rainfall but with a smaller area than the catchment area contributing which again will produce a lesser flow. Thus, the maximum runoff from the catchment happens when the duration of the rainfall event equals the ToC. Knowing the ToC, we obtain from Met Eireann DDF tables the depth of rainfall that falls in the duration for a 100-year event and multiply it by 1.2 to allow for climate change. Knowing the depth of rainfall and the area contributing and the maximum flow expected at the point of consideration (104.1lts/s from IH124) the impermeable factor of the catchment is calculated. The ToC is calculated using the FAA equation and checked against the Kerby Kirpich method. The upper-bound ToC from the FAA equation is 26mins while the lower bound ToC for the same equation is 15mins. One could reasonably take the average of the two ToCs which would give a 20.5mins ToC and this would accord nicely with the Kerby method which calculates the time of concentration to be 22mins. However, it is conservatively assumed that the time of concentration is 30mins. (The longer the ToC the greater the attenuation storage required.) An even more conservative estimate of 60mins was taken in the PFRA report that previously accompanied this planning submission giving a larger required storage volume. Using this conservative time of 30 minutes for the duration of the event we obtain the depth of water that falls on the catchment for this duration which from MET Eirean DDF tables is 27.1mm. This figure is multiplied by 1.2 to give a design rainfall depth of 32.5mm. (27.1*1.2CC=32.5mm). Using this depth and knowing the maximum runoff flow from the catchment (104.1lts/s from Equation IH124) and knowing the size of the catchment (86000m²) the effective impermeability of the catchment can be calculated. In this case it is 6.71% which produces a flow of 104.2lts/s. (32.5/1000*86000*6.71%*1000/(30*60) =104.2lts/s) Formulae are developed which allow for ready calculation of rainfall depths for a range of durations as shown on the following screenshot. RECEIVED: 02/07/2026 Page 11 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Screenshot shows the formulae used to determine the depth of rainfall for varying durations for differing return periods. For example, the formula for the depth of rainfall for a 100- year storm of duration varying from 15 minutes to 3 hours is Depth mm= 10.092*(Duration (mins))^0.2899 RECEIVED: 02/07/2026 Page 12 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Depth Duration Frequency (DDF) table for the location of the catchment. This is used to calculate the depth of rainfall that occurs for any particular length of storm and of a given return period. RECEIVED: 02/07/2026 Page 13 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers The FAA equation shows the time of concentration as being somewhere between 26min s and 15mins with 15mins being probably closer to the true value due to the steepness of the catchment. The type of ground assumed is meadow. A reasonably conservative view would be to take a ToC as being the average of the two figures at 20.5mins. However, a more conservative figure of 30mins is being chosen as the ToC. RECEIVED: 02/07/2026 Page 14 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers The Kerby method gives an overland flow of 22mins assuming the surface is “Average Grass.” The 22mins accords well with the average of the FAA results of 20.5mins. However, 30 minutes is being taken. This is because in a throttled system the higher the value taken for the design duration the more storage is required. RECEIVED: 02/07/2026 Page 15 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers In the attenuation calculation while the basin is filling at an average inflow of 104.2lts/s giving a total volume of 187.6m² in the 30mins ToC duration (30*60*104.2/1000=187.3m³) it is being countered by the flow in the pipe exiting the basin conveying the runoff water to the river. To obtain the flow through the pipe exiting the basin the diameter of the pipe needs to be known along with the surface friction (roughness) of the pipe, the entry and exit conditions and the head of water at maximum flow and a factor to multiply the maximum flow by to obtain an average flow through the pipe in the design time duration as the attenuation basin is filling up. Obtaining the maximum head is an iterative problem as it depends on the maximum level to which the water storage comes which in turn is dependent upon the size of flow exiting the basement through the pipe. In this report the following figures are given after the iterative process has been carried out. The pipe in question is considered to be a 225mm diameter concrete pipe with a Manning n coefficient of 0.013. It has been calculated that the flow through the pipe is 57.8lts/s under a head of water of 1.132m which allows for the friction losses in the pipe and the entry shock loss. The exit shock loss is considered to be allowed for within the sheugh receiving it. The difference in level between the entrance and exit pipe soffits is 0.6 (55.7-55.1) so the surcharge is 0.532m. The level of water in the basin is then 56.232mOD (55.7+0.532). The maximum flow leaving the basin at maximum head of 1.132m is 57.8lts/s. However, the average flow of water leaving the basin as it fills up is less as the average head in the design duration that it takes to fill the basin is less than the maximum head. So, we multiply this maximum flow by a factor to get the average flow. Conservatively this factor is taken at 0.7. This is conservative in that the pipe is surcharged by 0.2m before any significant storage takes place as the sheugh itself in which the exit pipe is located offers very little storage so most of the time the head will be above this level. At 0.2 surcharge the flow is 48.6lts/s which is 0.84 times the maximum flow. So, we know that the average flow factor is at least 0.84 but, as stated above, 0.7 is the figure that was taken. The volume of water leaving the basin for the ToC duration of 30 minutes is 72.8m³, (30*60*57.9*0.7/1000), which makes the maximum storage volume within the basin at the end of the period as 114.5m³. From an analysis of the basin characteristics (See Appendix 1 below) we can obtain this amount of storage at a level of 56.232mOD which is the level assumed to give the head for the pipe flow from the basin. A contour was then interpolated between 56.2 and 56.3mOD to achieve the required area within the contour shown as a yellow line in the screenshot below. RECEIVED: 02/07/2026 Page 16 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Screenshot shows the maximum flow in pipe for the expected head and the level of water in the basin necessary to provide that head. The pipe is 225mm concrete pipe with a Manning coefficient n of 0.013. The head available over the length of the pipe is 0.6m. The expected maximum flow is 57.8lts/s with a head loss of 1.132 which means that the pipe is surcharged by 0.532m. The soffit of the pipe is pipe at its entrance is 55.7mOD making the necessary water level 56.232mOD. The Area of flooding at this level is 921m² and the volume stored at this level is 114.5m³ which is the required volume to be stored. The maximum flow into the basin in the duration is 187.3m³ and the maximum volume out of the system in the duration is 72.9m³ making a storage capacity requirement of 114.5m³. RECEIVED: 02/07/2026 Page 17 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers The screenshot above shows the extent of the 56.232mOD contour at maximum flooding. Logarithmic interpolation of the areas associated with the contours gives an area of 921m² for the 56.232mOD contour. The toe of the proposed fill does not come as close to the boundary as this and so no flood displacement takes place. However, a toe drain is proposed along the toe of the embankment into which any runoff from the fill area is collected. The outflow from this drain will not have any suspended particles from the fill material as they will have settled out over time. Third party comments Dealing with the third-party submission point by point: 1. Mr. Stephen Moffett acting for the appellant (Appellant) states that the land adjacent to the subject property is the property of ValePark Farms. My understanding is that ValePark Farms do not own said property and have never owned it. If this is different then ValePark is requested to provide MCC with proof of their ownership of said property. 2. The Appellant misunderstands the nature of the pluvial flood risk as indicated in the OPW PFRA. This is elaborated upon elsewhere. RECEIVED: 02/07/2026 Page 18 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers 3. The Appellant is taking a description of the natural drainage of the catchment that flows to the basin and thence to the river via a piped section of the drain from C to D to E as being something the Applicant is going to use in a way that wasn’t previously being used. Again, none of the drain is within the ownership of ValePark Farms and the part of the drain from D to E to F is in fact in the ownership of the Applicant. The Appellant misunderstands the description that was given and the concept that an inadequately sized pipe in heavy rainfall can act as a temporary throttle. He misunderstands the hydrology and natural drainage within a rural environment whereby drainage channels convey water from field to field regardless of ownership depending on the topography. If we were to follow the logic used by the Appellant (even if he did own the land adjacent) he would have no right to drain water through my client’s lands from D to E to F. 4. No screen is proposed in this application either on the entrance to the pipe on the neighbouring land nor on the exit to the pipe located on the Applicant’s lands. 5. See points 2 and 3 above. 6. Firstly, the lands the Appellant is taking on to “defend” is not his to defend as stated in Point 1 above. An extra 8mm in the level of water on the lands as per the previous submission which lasted 3.1 minutes for a 100-year storm plus CC (equating to a roughly 1:300-year storm) before returning to the state that pertained previous to the development was considered so trivial a risk as to be truly insignificant especially when given the generous nature of the assumptions made to arrive at this conclusion. The nature of what it means to be “insignificant” seems to be lost on the Appellant. In this revised report it has been shown that with assumptions that are still conservative there is no encroachment of the fill material on the calculated flood events. So, there is no loss of flood storage and therefore no loss whatsoever to the neighbouring lands. 7. The point being made is not understood. 8. Dealt with in Point 3 above. With regard to the FMP 2 Flood Risk Management, the development can be justified on strategic grounds without increasing flood risk beyond itself. It is stated that silt and debris from filled lands will cause ongoing issues and extra maintenance. The proposed infill material is to be inert material so debris will not be an issue. Measures to combat silt will have been built into the system. RECEIVED: 02/07/2026 Page 19 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers With regard to FLP 2 Flood Risk Policy it has been demonstrated that no mitigation measures are required as there is no displacement of flood water storage and in fact flood water storage has been effectively increased. To summarize this section dealing with the Third-Party objection, a third-party submission was lodged by an agent acting for parties claiming to be owners of the adjoining lands. It is understood that the lands immediately adjacent to the proposed development are not, in fact, owned by the parties identified in the submission. Should ownership be asserted, documentary confirmation should be provided to the planning authority. The appellant’s interpretation of the OPW Preliminary Flood Risk Assessment (PFRA) mapping appears to rest on a misunderstanding of the purpose and limitations of that dataset. As clarified by the OPW, the PFRA pluvial mapping was not designed for, nor is it suitable for, development management or decision-making purposes. It does not take account of local subsurface drainage or hydraulic infrastructure and therefore cannot accurately depict flood extents at the site. Further, the submission misinterprets the description of local drainage, implying that the proposed development would make new use of, or alter, an existing drain in a way that affects other lands. The drainage pattern described—flow from higher fields to lower fields via open channels and pipes—is natural and pre-existing, and the proposed development does not introduce new hydraulic connections or obstructions. The 225 mm concrete pipe presently in place simply acts as a throttle to runoff under rare, intense rainfall, temporarily retaining water in the upstream basin before releasing it gradually. This phenomenon occurs irrespective of the proposed development. No screens or modifications to the existing pipe are proposed. The fill will consist of inert material only, with no suspended solids or debris anticipated. A toe drain is proposed solely to ensure clean discharge of surface water; it will marginally increase flood storage volume and therefore slightly reduce any localised ponding. The hydrological analysis demonstrates that, even under conservative assumptions, the fill does not encroach upon the 100-year plus climate-change flood extent, and no displacement of floodwater occurs. The additional storage provided by the proposed toe drain represents a small net improvement to flood capacity in the basin. On this basis, the issues raised in the third-party submission are without technical merit. They appear to stem from a misunderstanding of ownership and of the hydrological principles involved and should therefore be given little weight in the assessment of this application. RECEIVED: 02/07/2026 Page 20 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Residual risks By analysing the situation with more reasonable, but still generous, assumptions the extent of the flooding has been limited from having a small portion within the footprint of the proposed fill to having no encroachment into the footprint of the fill whatsoever. Thus, no displacement of flood waters takes place and so no mitigating measures are required with their attendant residual risks. By constructing a trench along the boundary more flood storage capacity is created for the flood waters in the neighbouring property allowing the level of flooding to decrease very slightly for a design storm. Thus, there are no residual risks associated with this development. Conclusion The OPW’s indicative pluvial mapping, relied upon in part by the local authority, was prepared for a preliminary national screening exercise and is not suitable for site-specific decision-making. It excludes local artificial drainage and therefore overstates potential flood extents. Successive analyses have used conservative and transparent assumptions to test the proposed infill. Earlier iterations already showed any flood displacement to be negligible—an 8 mm rise in adjacent levels dissipating within three minutes for a 100-year plus climate-change event. The current revision refines those assumptions and demonstrates that no encroachment or displacement of flood storage occurs at all. The proposed toe drain will marginally increase available storage and improve runoff control. In professional terms, this constitutes a genuinely insignificant level of residual risk. Engineering judgment must recognise the distinction between a theoretical or mathematically detectable effect and one of practical consequence. Informed management of risk involves distinguishing negligible local variations from cumulative or systemic hazards; the present proposal falls clearly in the former category. The development therefore complies with the objectives of the Monaghan County Development Plan and with the requirements of the Flood Risk Management Guidelines. It will not increase flood risk either within or beyond the site, and no further mitigation measures are warranted. Signed……………………………………………………. Marcus Dancey BSc (Eng), Dip Eng, CEng MIEI, FConsEI Chartered Engineer. RECEIVED: 02/07/2026 Page 21 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Appendix 1 analysis of the basin characteristics The area of the contours are obtained from the level of 55.8mOD up to the level of 56.3mOD and these are tabulated. Areas of the contours in the neighbouring field. RECEIVED: 02/07/2026 Page 22 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers The above is the tabulation of the areas. The volume from one contour to the one above it is obtained using the formula for a truncated cone or pyramid substituting 0.1 for h (the contour interval) and A1 and A2 being the area of the smaller and larger contour. Volume =h/3*(A1+(A1*A2)^0.5+A2). By cumulating them the volume of water storage below any contour can be accurately obtained. A formula was then devloped to obtain the level of the storage for any volume inputted. The formula is as shown under the table. It accords very accurately with the actual value. This formula is used to obtain the level of water in the basin when the required flood storage capacity is calculated. This then informs the head above the pipe which informs the flow which in turn informs the volume of storage required and so on. Iterating produces an answer that is internally consistent. RECEIVED: 02/07/2026 Page 23 of 23 Consulting Engineers Building Surveyors Design Certifiers Assigned Certifiers Appendix 2 Screenshot of email from OPW when requested to provide a copy of the mapping that was being used by the MCC to highlight pluvial flood risk. RECEIVED: 02/07/2026