2. Flood Risk Assessment

closeddate_range12 Dec, 2014, 12:00am - 6 Feb, 2015, 12:00am
 

2.1             Stage 1 Flood Risk Identification

The purpose of this stage is to identify whether there are any flooding or surface water management issues relating to the proposed amendment plan area that may warrant further investigation.  Sources which were consulted are outlined below.  This assessment is for an amendment to a Local Area Plan and therefore is at the Strategic Flood Risk Assessment scale. 

2.1.1       Regional Flood Risk Appraisal

A Regional FRA was carried out and published as Appendix 3 to the Strategic Environmental Assessment of the South East Regional Planning Guidelines, 2010.  This document provided guidance on the issues to be addressed in any Strategic Flood Risk Assessment.   The Regional FRA referred to flooding that occurred in August 2008 and stated that “Graiguenamanagh and Callan, two of the worst-hit parts of the county, along with Thomastown will benefit from a Flood Risk Management Study which will be undertaken by Kilkenny County Council” (See Section 2.4 below).    

2.1.2       Strategic Flood Risk Appraisal

A Strategic Flood Risk Assessment for the County was published in 2014 as part of the County Development Plan 2014-2020.  This examined the level of information available on flooding in the county.  This did not specifically address the Callan LAP area. 

 

A Flood Risk Assessment of Amendment 1 to the Callan Local Area Plan (Core Strategy) was carried out in March 2012.   

2.1.3       CFRAM Programme  

CFRAM is Catchment Flood Risk Assessment and Management.  The national CFRAM programme commenced in Ireland in 2011. The OPW is the lead agency for flood risk management in Ireland and is the national competent authority for the EU Floods Directive. The CFRAM Programme comprises three phases:

  • The Preliminary Flood Risk Assessment (PFRA): 2011
  • The CFRAM Studies and parallel activities: 2011-2015
  • Implementation and Review: 2016 onwards

The ‘Floods’ Directive[1] requires Member States to undertake a national preliminary flood risk assessment by 2011 to identify areas where significant flood risk exists or might be considered likely to occur.  In March 2012, the OPW published the National Preliminary Flood Risk Assessment, Overview Report.   The objective of the PFRA is to identify Areas for Further Assessment (AFA’s) and this further assessment will take place though Catchment Flood Risk Assessment and Management Studies (CFRAMS).  Callan was identified as a ‘Possible Area for Further Assessment’.  Draft CFRAM flood mapping for the Callan area was produced in March 2014 and this is discussed below.      

 

 

2.1.4          Available sources

The data listed below is available and provides information on the historical occurrence of flooding as it relates to the proposed amendment. 

 

Primary Sources for flood risk information:

 

  1. CFRAM floodmaps / models

A draft flood map for Callan was published on behalf of the OPW in March 2014. This shows that part of the subject site has a 0.1% AEP event risk.  An extract is reproduced below:

 

 Figure 1: CFRAMS Draft Mapping for Callan, 2014.

 

Figure 1: CFRAMS Draft Mapping for Callan, 2014.

 

 

  1. Detailed flood study

Kilkenny County Council commissioned Hyder Consulting to carry out a Flood Relief Report for Callan, Thomastown and Graiguenamanagh in 2010.  The Callan Report included detail on historical flood events and mapped the 100 year flood extent around the River Nore (see extract from the map below).  This report recommended two measures for mitigation of flood risk in Callan:

·                     Flood Cell 1 (the left bank) - Flood defence wall around the car park at KCAT

  • Flood Cell 2 (the right bank) Flood proofing and awareness

 

These measures were incorporated into the flood alleviation scheme which was completed in Callan in 2011.  This scheme is to address flooding in the central core of the town around Bridge Street/KCAT car park/Clotheen Lane area. Its focus is the protection of residences and businesses.  It has done this by a combination of earthen bunds, structural walls, flood gates and flap valves on existing outflows.

 

Figure 2: Hyder Consulting Flood Zones for Callan, 2010

 

Figure 2: Hyder Consulting Flood Zones for Callan, 2010

 

 

Secondary Sources

 

  1. Office of Public Works OPW Flood Events Mapping

As part of the National Flood Risk Management Policy, the OPW developed thewww.floodmaps.ie web based data set, which contains information concerning historical flood data, displays related mapped information and provides tools to search for and display information about selected flood events.  Two flood events are noted proximate to the site, as shown below, (i) Approx. 170m south of the subject site a flood event occurred in October 2004, and (ii) approx. 130m to the south east of the subject lands a flood event occurred in October 2004 also.  No flood events are shown on the subject site.     

 

Figure 3: Historic Flood Events, www.flooding.ie

Figure 3: Historic Flood Events, www.flooding.ie

 

 

  1. OPW Benefitting Lands mapping

These maps were prepared to identify areas that would benefit from land drainage schemes, and typically indicate low-lying land near rivers and streams that might be expected to be prone to flooding.  The extract below shows the south-western part of the proposed amendments area to be benefitting lands (indicated in red hatching).   

 

Figure 4: Benefitting Lands, www.flooding.ie

 

 

  1. Mineral Alluvial Soil Mapping

The soils and subsoils maps were created by the Spatial Analysis Unit, Teagasc. The project was completed in May 2006 and was a collaboration between Teagasc, Geological Survey of Ireland, Forest Service and the EPA.  The presence of alluvial soils can indicate areas that have flooded in the past (the source of the alluvium).  The map below shows the location of alluvial soils immediately south of the Amendment area and to the north (none on the subject site). 

Figure 5: Alluvial Soils, 2006

Figure 5: Alluvial Soils, 2006

 

 

  1. Ordnance Survey “Lands liable to floods” mapping (6” OS maps)

These maps have been studied to see if there is an area marked as being “Liable to Floods” in or in the vicinity of the zoned areas.  It is noted that the OS maps simply show the text “Liable to Floods” without delineating the extent of these areas.  An extract from the 6’’ map is attached overleaf.  No text is shown in relation to the proposed amendment site. 

 

It should be noted that some of this data is historically derived, not prescriptive in relation to flood return periods and not yet predictive or inclusive for climate change analysis.  Many of these maps were based on survey work carried out from 1833-1844 with many updated in the 1930s and 1940s. Therefore they do not show or take account of recent changes in surface drainage, such as development in floodplains, road realignments or drainage works for forestry or agriculture. So there is significant potential that flood risk in some areas may have increased or been reduced since they were prepared. 

 

Figure 6: Ordnance Survey 6 inch map, 1829-1842

 

Figure 6: Ordnance Survey 6 inch map, 1829-1842

2.1.5          Conclusion of Stage 1

 

The available sources of information is summarised in table 1 below and a composite map of the flood risks in relation to the proposed amendment area is shown in Map 2. 

 

Having regard to all of the information sources as outlined above, it is considered that the area could be subject to a potential flood risk issue and therefore the assessment should proceed to Stage 2. 

 

Map 2 SFRA

    

2.2              Stage 2 Initial Flood Risk Assessment

The purpose of this stage is to ensure that all relevant flood risk issues are assessed in relation to the decisions to be made, and potential conflicts between flood risk and development are addressed to the appropriate level of detail.  The extent of the risk of flooding should be assessed which may involve preparing indicative flood zone maps.  Having identified flood zones, the sequential approach is used to direct, where possible, new development to areas at low risk of flooding. 

 

2.2.1       Flood zone mapping

Flood zones are geographical areas within which the likelihood of flooding is in a particular range.  There are three types of flood zones defined:

 

  • 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)
  • Flood Zone B – where the probability of flooding from rivers and the sea is moderate (greater than 0.1% or 1 in 1000 for river 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 river flooding).  Flood Zone C covers all areas of the plan which are not in zones A or B.   

 

The Draft CFRAMS mapping produced for the King’s River is the most recent and reliable data in terms of flooding for the subject site.  For this reason, it is used on its own in determining flood zones on the subject site in deference to other sources.     

 

Accordingly, it is considered that the south-western part of the subject site is located in Flood Zone B (approx. 2.4 acres) and the remainder of the site is located in Flood Zone C (approx. 5.6 acres).   This is illustrated in Map 3 overleaf.    

 

 

Map 3 SFRA

 

 

 

 

2.2.2       Application of the Sequential Approach

Having identified the flood risk zones within the plan area the next step is to apply the sequential approach to land use planning.  The Guidelines have categorised land uses into three vulnerability classes and have also specified which vulnerability class would be appropriate in each flood zone, or where the Justification Test would be required. 

 

The table of vulnerability classes (Table 3.1 of the Guidelines) is as follows:

Table 1 Classification of vulnerability of different types of development

Vulnerability Class

Land uses and types of development which include*:

Highly

vulnerable development

(including

essential infrastructure)

Garda, ambulance and fire stations and command centres required to be operational during flooding; Hospitals; Emergency access and egress points; Schools;

Dwelling houses, student halls of residence and hostels;

Residential institutions such as residential care homes, children’s homes and social services homes;

Caravans and mobile home parks;

Dwelling houses designed, constructed or adapted for the elderly or, other people with impaired mobility; and

Essential infrastructure, such as primary transport and utilities distribution, including electricity generating power stations and sub-stations, water and sewage treatment, and potential significant sources of pollution (SEVESO sites, IPPC sites, etc.) in the event of flooding.

Less vulnerable development

Buildings used for: retail, leisure, warehousing, commercial, industrial and non-residential institutions; Land and buildings used for holiday or short-let caravans and camping, subject to specific warning and evacuation plans;

Land and buildings used for agriculture and forestry;

Waste treatment (except landfill and hazardous waste);

Mineral working and processing; and

Local transport infrastructure.

Water-compatible development

Flood control infrastructure; Docks, marinas and wharves; Navigation facilities;

Ship building, repairing and dismantling, dockside fish processing and refrigeration and compatible activities requiring a waterside location;

Water-based recreation and tourism (excluding sleeping accommodation);

Lifeguard and coastguard stations;

Amenity open space, outdoor sports and recreation and essential facilities such as changing rooms; and

Essential ancillary sleeping or residential accommodation for staff required by uses in this category (subject to a specific warning and evacuation plan).

*Uses not listed here should be considered on their own merits

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 3.2 of the Guidelines sets out how the vulnerability classes interact with the flood zones and when the Justification Test is required.

 

 

Development

Flood Zone A

 

Flood Zone B

Flood Zone C

Highly vulnerable

Justification Test

Justification Test

Appropriate

Less vulnerable

Justification Test

Appropriate

Appropriate

Water-compatible

Appropriate

Appropriate

Appropriate

 

 

The Amendment to the LAP is to zone the land ‘Agriculture’ and include a site specific development objective for the land. 

 

Agricultural use is listed as a ‘less vulnerable’ class of use in Table 3.1 of the Guidelines.  Therefore, the Agricultural zoning is appropriate for Flood Zones B and C, and a justification test is not required in this instance. 

 

A residential based complex/development for the Camphill Community is considered to be a ‘highly vulnerable’ class of use as defined in Table 3.1 of the Guidelines.  In accordance with Table 3.2 of the Guidelines, this type of use is appropriate in Flood Zone C and a justification test is required for this use in Flood Zone B.   

 

While a site-specific Flood Risk Assessment and a site specific justification test is required to be submitted at planning application stage, it is considered prudent to carry out a justification test for this type of development as part of the strategic flood risk assessment  in accordance with Section 3.8 of the Guidelines.       

 

2.2.3       Justification Test

This justification test refers to a residential use for the Camphill Community as it pertains to the Flood Zone B part of the amendment site.  

 

The criteria for the Justification Test are outlined in Section 1.3.1 of the Guidelines and the test is set out below.   

 

 

1.       The urban settlement is targeted for growth under the National Spatial Strategy, regional planning guidelines, statutory plans or under the Planning Guidelines or Planning Directives provisions of the Planning and Development Act 2000, as amended. 

 

Callan is identified as a District Town in the Regional Planning Guidelines 2010-2022.  District towns are “targeted for growth as centres that can perform an important role in driving the development of a particular spatial component of the overall region”.  Callan is also a District Town in the County Development Plan spatial hierarchy. 

 

  1. The zoning or designation of the lands for the particular use or development type is required to achieve the proper and sustainable planning of the urban settlement and in particular:
    1. Is essential to facilitate regeneration and/or expansion of the centre of the urban settlement
    2. Comprises significant previously developed and/or under-utilised lands;
    3. Is within or adjoining the core of an established or designated urban settlement;
    4. Will be essential in achieving compact or sustainable urban growth;
    5. There are no suitable alternative lands for the particular use or development type, in areas at lower risk of flooding within or adjoining the core of the urban settlement.

 

The site is immediately adjacent to the town boundary of the Callan LAP.  The Camphill Community currently owns the subject site and it is economically feasible and viable for these lands to be developed for these purposes.  The pedestrian connection from the site back to the core of the town will consolidate the Camphill community and help it grow sustainably within the town.  However, the development of the Zone B part of the site is not essential in achieving compact urban growth and there are alternative zoned lands available in Callan that could be developed for this purpose.  Therefore, it is considered that the development objective as it relates to Zone B does not satisfy this part of the justification test.     

 

  1. A flood risk assessment to an appropriate level of detail has been carried out as part of the Strategic Environmental Assessment as part of the development plan preparation process, which demonstrates that flood risk to the development can be adequately managed and the use or development of the lands will not cause unacceptable adverse impacts elsewhere.

 

A Flood Risk Assessment was carried out for Amendment No. 1 of the Callan LAP in 2010 for the Core Strategy.  Flood management policies were included in that Amendment to mitigate unacceptable impacts from flooding.   

 

The County Development Plan 2014-2020, for which a full SEA and SFRA were carried out, also contains policies in relation to flooding and mitigation of flooding which is relevant to Callan.  A full suite of Development Management Standards in relation to surface water drainage is set out in Section 9.2.11 of the County Development Plan which is applicable to new developments in Callan also. 

 

The SEA and SFRA carried out for Amendment No. 1 of the LAP and the County Development Plan 2014-2020 have informed policy in relation to flooding.  These policies demonstrate that flood risk can be adequately managed and unacceptable adverse impacts elsewhere can be prevented. 

 

Justification Test Conclusion:

The development objective as it relates to Zone B does not satisfy part 2 of the justification test as prescribed in Section 4.23 of the Guidelines and accordingly a residential use in flood zone B should be excluded from the Amendment.      

 

2.2.4       Stage 2 Conclusion

 

Having regard to the following:

  1. The ‘Agriculture’ zoning objective proposed,
  2. The mapped flood zones, 
  3. The wording of the proposed development objective which requires a site specific flood risk assessment and justification test to be carried out for any development on the site,
  4. The justification test regarding the site specific objective and the Flood Zone B part of the Amendment area

 

It is considered that, subject to residential use being excluded from the flood zone B part of the site, the flood risk to the development of this land can be adequately managed without causing unacceptable adverse impacts elsewhere and it is not necessary at this stage to proceed to Stage 3, Detailed Flood Risk Assessment.