former cold store site cwmbran - torfaen county borough ... interim report.pdf · the former cold...

Former Cold Store Site Cwmbran Flood Consequence Assessment Interim Report

19 April 2011

5082967.6390.130/DG01- FCA Interim Report 1-2.docx

Former Cold Store Site Cwmbran

Flood Consequences Assessment Interim Report

19 April 2011 Notice This document and its contents have been prepared and are intended solely for BDW Trading Limited’s information and use in relation to a Flood Consequences Assessment of Former Cold Store Site, Cwmbran, South Wales.

Atkins Limited assumes no responsibility to any other party in respect of or arising out of or in connection with this document and/or its contents.

Document History

JOB NUMBER: 5082967.6390.130 DOCUMENT REF: DG01- FCA Interim Report 1-2

1-2 Issue 2 incorporating client comments

DMH KIO HR HR 21-04-11

1 Client Issue DMH KIO HR HR 19-04-11

D1 Internal check & review DMH KIO 15-04-11

Revision Purpose Description Originated Checked Reviewed Authorised Date


Contents Sec tion Page Former Cold Store Site Cwmbran 1

1. Introduction 1

1.1 Purpose of the Interim Report 1 1.2 Regulatory Background 1 1.3 The need for the assessment 2

2. Site Details 2

2.1 Site Description 2 2.2 Proposed Development 2 2.3 Site Location 3

3. The Extent of the Assessment 5

3.1 Activities Undertaken 5

4. Potential Sources of Flood Risk 6

4.1 Flood History 6 4.2 Overtopping from the Afon Lwyd 6 4.3 Overland Flow from Cwmbran Brook 7 4.4 Surface water (Pluvial) Flooding 9 4.5 Sewer Flooding 9

5. Environment Agency Opinion 10

5.1 Environment Agency Liaison 10 5.2 Implications of the EA’s Opinion 10

6. Summary of the Assessment 12

7. Proposed Activities to produce a Flood Consequences Assessment 13

7.1 Production of the Flood Consequences Assessment 13

List of Figures

Figure 2-1Site Location Showing TAN15 Development Advice Map 3 Figure 2-2 Site Extent marked on Flood Map extract from Environment Agency Website 4

5082967.6390.130/DG01- FCA Interim Report 1-2.docx 1

1. Introduction

1.1 Purpose of the Interim Report This assessment has been undertaken in the context of Planning Policy Wales, Technical Advice Note 15 (TAN15) Development and Flood Risk issued by Welsh Assembly Government. The TAN document sets out the general advice to Local Planning Authority when assessing new planning applications in flood risk areas.

The scoping assessment:

• identifies the sources and level of known flood risk and the associated degrees of uncertainty based on the existing available information

• identifies further works considered necessary to define the risks and consequences of flooding to produce an FCA of the site.

If it is identified that a Flood Consequences Assessment is required to comply with TAN15, then it must demonstrate that the risks and consequences of flooding can be managed to acceptable levels. If this cannot be demonstrated, then this is a reason for the planning authority to refuse planning application.

The overarching objective of the scoping phase is to determine any analysis or assessment which may be required to produce a Flood Consequences Assessment in support of a planning application for development of the site. The extent of the assessment and the overall approach should be agreed with the Environment Agency.

1.2 Regulatory Background Technical Advice Note 15 (TAN15) Development and Flood Risk issued by Welsh Assembly Government sets out the general advice to a local planning authority when assessing new planning applications in flood risk areas.

TAN15 requires assessment of the consequences of flooding resulting from a development. The assessment needs to consider the risk to the proposed development itself plus the impact of the development on flood risk elsewhere.

The trigger to the FCA process is a known or perceived flood risk. Reference to the development advice map (DAM) which accompanies TAN15 will indicates levels of flood risk, described in three flood zones:

• Zone A – Areas considered to be at little or no risk of fluvial or tidal flooding.

• Zone B – Areas known to have flooded in the past evidenced by sedimentary deposits.

• Zone C – Based on the Environment Agency extreme flood outline which indicates a 0.1% (1 in 1000) or greater annual chance of flooding.

The DAM is revised only periodically, the last update being in 2009. The EA flood outlines are updated on a quarterly basis. The EA flood map can be considered to represent the more up to date source of information and should be referred to for an initial appraisal of a site.

In general, only the main rivers are represented on the Environment Agency Flood Map. These are usually larger streams and rivers. Environment Agency powers to carry out flood defence


works apply to main rivers only. On the smaller ordinary watercourses powers lie with the local authority.

The local authority planning or others may have local knowledge which indicates a potential flood risk to a proposed development site. This is particularly true where an ordinary watercourse is the source of the flood risk.

1.3 The need for the assessment The Former Cold Store Site, Cwmbran lies within 50m of the Environment Agency extreme flood outline. An ordinary watercourse, the Cwmbran Brook, follows a course within 260m north of the site.

Works were necessary to mitigate the risk of flooding as part of a development of an adjacent site to the south.

A study of the flood risks to the adjacent site, formerly known as Burton’s Biscuits Sports Field Site, was undertaken in 2004 and 2005 by Atkins Limited.

2. Site Details 2.1 Site Description

The land of interest is a disused Cold Store site at Court Road, to the south east of Cwmbran in South Wales. Cwmbran itself lies on the western slopes of the valley of the Afon Lwyd. The site location is centred on OS Grid Reference (ST 30150 94020).

The Cold Store site lies within the Court Road Industrial Estate. Previously, up to the mid part of the last century, the area north of the site was used for railway sidings and a brick works.

The site is separated from the Afon Lwyd by a railway embankment which follows an approximately northeast-southwest route immediately east of the site.

To the west of the site, situated on higher ground, are the residential properties fronting on to Llantarnam Road. A new residential development is currently nearing completion on the land bordering the south east of the Cold Store site. A public path leading to a footbridge over the railway separates this development from the site.

The Cwmbran Brook flows in an open channel some 260m north of the site, turning east to pass through twin arch culverts under the railway, before joining the course of the Afon Lwyd.

2.2 Proposed Development It is proposed to develop the site for residential use. Some 70 properties are to be built on the site.

Two proposed site layouts have been provided. We have completed this scoping assessment based on the later version provided to Atkins on 5 April 2011. This layout contains an additional triangular parcel of land of approximate area of 2,200 m2 located to the south east side of the path to the railway footbridge. No development is indicated to be proposed in this area and should not affect the extent of the FCA to be scoped.

We understand that it is proposed to raise the ground levels over the majority of the site by some 600mm.


2.3 Site Location The site location in relation to the main local watercourses is presented in Figure 2-1, together with the DAM. The majority of the site lies within zone B of the DAM. A small area within the eastern tip of the site boundary is indicated to be in Zone C2 of the DAM.

Figure 2-1Site Location Showing TAN15 Development Advice Map

Reference to the Environment Agency flood map (Figure 2-2), reveals a slight increase in the proportion of the site lying within the 0.1% (1 in 1000) chance flood outline compared to the DAM. The overall proportion of the development site within the flood boundary is still relatively small.

It should be noted that the flood map in this area does not appear to include any assessment of the Cwmbran Brook to the north (marked on Figure 2-1). The extent of the 0.1% chance outline over the course of the brook appears to derive from the estimated flood levels in the Afon Lwyd.


Figure 2-2 Site Extent marked on Flood Map extract from Environment Agency Website

Detail of extent of 0.1% (1 in 100) chance flood outline on the site

The copy of the Environment Agency 0.1% (1 in 1000) flood outline presented above has been provided for information only. The maps represent indicative boundaries and should be confirmed with appropriate assessments. However, they illustrate the limited extent of the 0.1% (1 in 1000) chance flood boundary on the development site.


3. The Extent of the Assessment

3.1 Activities Undertaken 1) Site visit to familiarise with site and surrounding area.

2) Review of the project data and information prepared for the Flood Risk Assessment of adjacent Burton’s Biscuits Sports Field Site, completed by Atkins on behalf of Barratt Homes, 2005.

3) Desktop exercise to assess any changes or updates to the analysis which might be required to update the previous assessment to meet current guidance and industry best practice.

4) Contact Torfaen Council for any flood history for the area

5) Check on potential for Surface Water Flood Risk with reference to Environment Agency Surface Water Flood Maps.

6) Review of contours in the area to identify potential overland flow routes towards the site from the surrounding area.

7) Identify the main sources of flood risk to the site.

8) Indentify any other new analysis required to assess the flood risk to the site.

9) Scoping of assessment to quantify flood risk to satisfy requirements of TAN15.

10) Correspondence and discussion with a number of departments within the Environment Agency Wales, including:

- Development & Flood Risk;

- Planning Liaison;

- Hydrology

- Data & Mapping.

11) Agree the extent of any proposed assessment with the Environment Agency.

12) Provide a costing proposal to produce a Flood Consequences Assessment of the Cold Store Site.


4. Potential Sources of Flood Risk Based on a review of the project data and analyses for the earlier FRA of the adjacent site, the Cold Store site is potentially at risk from a number of sources:

• Direct overtopping from the Afon Lwyd

• Overland flows developing from Cwmbran Brook in the event of overtopping of the right bank

• Surface water flooding

• Sewer flooding

A scoping level summary of the risks is provided below. No updates of the previous analyses are implied. However, significant liaison has taken place with the Environment Agency to determine the level of existing information which might inform the FCA. Where it is considered that the level of uncertainty is unacceptable for assessment of the Cold Store site, this is indicated.

4.1 Flood History We have contacted Torfaen Council and were informed by telephone that there are no records of flooding in the area of the former Cold Store. The flood history from the previous flood risk assessment (FRA) of the adjacent site has been reviewed for any relevance to the current site.

In a letter from EA Planning Liaison dated 31st March, it is suggested that the historic flood outline which covers part of the Cold Store Site resulted from the Afon Lwyd.

However, the Environment Agency historic flood outline supplied for the previous FRA coincides with the route of the Eastern Valleys Trunk Sewer.

The former Burton’s Biscuits Site did flood on a number of locations from the Eastern Valleys Trunk Sewer (EVTS). The conclusion was made as part of the Atkins FRA (May 2004) that the source of flooding to the Burton’s Biscuits Site in 1979 was most likely the EVTS rather than the Cwmbran Brook or Afon Lwyd. The evidence suggests this is likely to be the source of flooding to the north eastern area of the Cold Store site.

We understand from the previous assessment that Dwr Cymru Welsh Water (DCWW) planned improvement works to the trunk sewer, which were due for completion in 2005. As part of the FCA for the site we will need to confirm with DCWW that these works were completed as planned and have mitigated the risk of flooding.

As part of the FCA we would confirm in writing that Torfaen CBC has no additional information on pertinent local flood history.

4.2 Overtopping from the Afon Lwyd The site is indicated to be flood free for the 1% (1 in 100) annual chance flood event. However, as already noted above (section 2.3), a small part of the site, estimated to be approximately 1,000m2 lies within the EA extreme (0.1% or 1 in 1000 annual chance) flood outline from the Afon Lwyd. Note the 1,000m2 area does not include the triangular parcel of land to the east of the footpath, south east of the Cold Store site. Although within the red line boundary, this area is not indicated to be developed for buildings.


From the development outline provided, four residential buildings are within the EA 0.1% (1 in 1000) chance flood boundary.

The 0.1% chance outline from the Afon Lwyd will need to be defined on the site.

4.2.1 Existing Information to determine extent and consequences of this risk The hydrology and hydraulic modelling of the Afon Lwyd used to estimate flood levels for Atkins previous flood assessment of the Burtons Biscuits site (2004) are now considered out of date. This results from :

• Changes in the ways extreme flows are estimated

• Availability of additional years of gauge data for the Afon Lwyd (at Ponthir gauging station)

• Refinements to the structure of the Environment Agency’s 1D hydraulic model

Hydrology

We have determined that the Environment Agency has an up to date flood frequency relationship for a location on the Lwyd upstream of the confluence of the Cwmbran Brook. However, these flow estimates would not be appropriate to assess levels adjacent to the Cold Store as they do not include the contribution of the Cwmbran Brook.

The Environment Agency hold no existing flow estimates for the required study reach of the Lwyd. Peak flow estimates will therefore need to be derived for use in a hydraulic model.

Hydraulic models

The 1% (1 in 100) chance flood map is based on Environment Agency’s 1D steady state hydraulic model. This model includes the hydraulic influence of structures such as bridges on estimated flood levels. Atkins’ previous study for the Burton Biscuits site used an earlier version of this 1D model to estimate flood levels, including those adjacent to the site.

The Environment Agency extreme flood outline (0.1% chance event) is based on a different model, a broad scale 2D JFLOW model. Hydraulic structures and the influences on flood levels are not well represented. However, the model does provide outputs suitable for mapping on a broad scale the extent of low probability events.

The flood levels from the 2D model of the Afon Lwyd are not of sufficient accuracy for use in site specific assessments, especially in relatively flat sites such as the Cold Store where the boundary is not clearly defined by step changes in the topography.

The Environment Agency’s current 1D model of the Afon Lwyd is likely to be suitable to derive flood levels for the 0.1% chance event, based on updated flow estimates which will need to be derived as described above.

4.3 Overland Flow from Cwmbran Brook The Cwmbran Brook follows a course under the railway via twin culverts located some 270m north of the Cold Store site.

In the event of flows exceeding the channel capacity upstream of these culverts water will spill over the right bank. The ground levels along Court Road would suggest a potential flow path from the brook towards the Cold Store Site.

Previous assessments by Atkins in 2004 suggest that the site was unlikely to flood during a 1% (1 in 100) event on the Cwmbran Brook. This assessment included an allowance for climate change. A 0.1% (1 in 1000) chance event was not assessed.


Consideration of the risk of blockage of the culverts indicated a risk of overtopping of the right bank of the Cwmbran Brook and some flooding to Court Road.

For a blockage of one culvert only, it was previously estimated that the duration of overtopping during a 1% event would be short, approximately 20mins. The majority of flood water would be retained in the car parking area adjacent to and south of the brook.

However, as described in the following section, there is some uncertainty as to how representative the catchment area used for the previous assessment is of the actual area.

It is noted that we have been unable to uncover any incidents of flooding in the area which are attributable to the Cwmbran Brook. This in itself suggests that the risk of flooding from this source is low.

Nonetheless, we consider that there is a potential risk of flooding from the Cwmbran Brook which will need to be investigated.

4.3.1 Existing Information to determine extent and consequences of this risk Hydrology

Through recent discussion with the Environment Agency hydrology team we have been made aware of an error in the catchment area defined in the industry standard Flood Estimation Handbook (FEH) CD ROM.

Potentially the catchment area to the rail culverts is over 2km2 compared to the 0.6km2 previously assessed. This may result in an increase in the peak flow assessed to reach the open channel section of the brook compared to that agreed with the Environment Agency for the previous assessment in 2004.

However, the Cwmbran Brook is culverted has a number of long culverts. The capacity of these culverts will serve to some extent (to be investigated) to throttle the peak flows which can develop in the open channel section of interest.

It is also considered possible that water could spill at locations upstream and remote from the study site during high flow events. The potential for any spills to develop as overland flow paths and return to the Brook will need to be assessed.

Once flow estimates in the downstream reach to the rail culverts have been estimated, we can re-assess the potential for these to exceed the channel capacity in the hydraulic model (see following section).

Hydraulic Models

The only existing hydraulic mode of the Cwmbran Brook is the 1D steady state HEC RAS model developed by Atkins for the previous flood studies (2004 & 2005). Visual inspection as part of our recent site visit suggests no evidence that the channel geometry has changed significantly since the development of this model. It is considered to provide a good representation of the open channel section of the brook to the rail culverts and its confluence with the Afon Lwyd.

We would note that the Environment Agency Development & Flood Risk initially indicated that the risk from this source is not considered significant. However, the changes in catchment boundaries described in the preceding section, leads to uncertainty in the previously estimated flood levels. This needs further investigation in the existing hydraulic model.

We would not expect that any model development or extensive re-running of the model to be required.


4.4 Surface water (Pluvial) Flooding The site is low lying relative to surrounding areas to its north west and south west. The ground contours in the area and the EA Surface Water Map suggest that surcharging of the highway and surface water during over design storm events could result in overland flow being directed along roads towards the site.

We understand that the finished flood levels of the buildings will be raised by approximately 600mm. Careful consideration of the site layout and vertical alignments of the distributor roads will be required to ensure that overland flows do no impact on existing or new development.

The potential for surface water flooding to the site will be commented upon in the FCA. Based on available information, we consider that it is likely that such a risk can be managed within the design of the development layout.

No new analysis or calculations are proposed.

4.4.1 Management of surface runoff from the development. It is assumed that the drainage design will be undertaken separately and is specifically excluded from our proposal for an FCA for this site.

It is assumed that any surface water from the development site will, ultimately be discharged to the Afon Lwyd. The potential for the drainage system to surcharge during periods of elevated water levels in the Afon Lwyd will need to be considered as part of the drainage design.

It is assumed that surface runoff from the development site itself will be managed using appropriate sustainable drainage systems (SuDS) to restrict runoff as required by section 8.5 of TAN15. If this is not possible due to existing hydrological regime then attenuation systems will be required to reduce the surface water discharge to at least Greenfield runoff.

Consideration will need to be given to any existing flow paths onto or away from the site.

4.5 Sewer Flooding It is assumed that the capacity of the existing sewerage network to accommodate the proposed development will be agreed with the undertaker.

Specifically, it will need to be confirmed that the improvement works to the Eastern Valleys Trunk Sewer undertaken by Welsh Water has mitigated the risk from this source.


5. Environment Agency Opinion 5.1 Environment Agency Liaison

We have contacted the Environment Agency to gain its opinion of the requirements and the extent of any FCA required for the site. An onsite meeting was originally arranged with the Environment Agency Development & Flood Risk Officer, but this was cancelled by the EA and we were advised by e-mail (copy attached) that no FCA for the site would be required.

As a precaution, to ensure no flood risk issues would arise at a later date in the planning process, we drew the EA officer’s attention to the potential risk from Cwmbran Brook. This was one of the sources of flood risk considered as part of the earlier FRA of the adjacent Burton’s Biscuits Sports Field Site. Nonetheless, it was re-confirmed to us by telephone there would be no need for an FCA.

We advised our client by telephone of this position on 15th March and subsequently requested formal written confirmation by letter to Environment Agency Planning Liaison, dated 16th March 2011.

The written response from EA Planning Liaison (dated 31st March, copy attached) stated that a small part of the development site lies within 0.1% chance outline and that records show that the proposed site has flooded from the Afon Lwyd. The EA letter advises that development should be avoided in the area at risk of flooding. If development is required within the flood outline and the EA recommend an FCA should be prepared to demonstrate that the risks can be managed.

Since this time we have had a number of discussions and correspondence with a number of departments to determine the available flood information on which to base an assessment and to define the extent of the assessment.

5.2 Implications of the EA’s Opinion 5.2.1 Risk from the Afon Lwyd As described in section 4.2, the flood map boundary from the Afon Lwyd is not of sufficient accuracy to define the limits of flooding over the site.

In order to inform options for the site, the 0.1% (1 in 1000) chance outline will need to be determined in greater detail based on suitable hydraulic model flood levels and mapped across the site based on surveyed site levels. Once this flood outline is established, the following options would be available to comply with the indicative guidance contained in TAN15 and the area of developable land would be defined.

The options would be to:

• Keep any buildings outside the 0.1% (1 in 1000) outline.

• Locate buildings within the 0.1% (1 in 1000) chance flood outline – but demonstrate that flood depths would be less than 600mm. Demonstrating that flood flow velocities are within TAN15 limits may be more difficult and could require further hydraulic calculations and potentially modelling on the site itself. Although it is considered unlikely to be necessary based on current information.

• Locate buildings in current 0.1% (1 in 1000) chance outline – but raise the slab level to ensure that they remain flood free. This would require compensatory flood storage to be provided. It would also need to be demonstrated that mitigation could be achieved to cancel


the potential increased risk to third parties from diverting overland flow paths as a result of raising the site.

5.2.2 Risk from the Cwmbran Brook The Environment Agency’s Development & Flood Risk are not aware of any significant risk from the Cwmbran Brook and has not specifically requested consideration of the risk from this source. However, given the uncertainty over the flow estimates used for previous assessments, described in section 4.3, we would recommend further work to clarify the flood risk from this source, to avoid any potential delay due to a change in opinion on receipt of an FCA for the site.


6. Summary of the Assessment • The site is entirely outside the Environment Agency’s 1% (1 in 100) chance flood outline.

• A small area of the northeast of the site, however, lies within the boundary of the Environment Agency’s extreme flood outline (0.1% annual chance event). This area is considered potentially at risk from direct inundation from the Afon Lwyd.

• There is a potential flood risk from the Cwmbran Brook north of the site. The potential for overland flows to develop along Court Road and onto the site cannot be ruled out.

• We consider that there is sufficient uncertainty as to the level of risk for the Cwmbran Brook to warrant further investigation.

• The site is relatively low lying compared to areas to the west and north. The surface water flood map and local topography for the area suggest that during high intensity storms overland flow paths would develop due to surface water flooding. These would flow towards the lower lying parts of the site during overdesign events causing surcharging of the local surface water and highway drainage system. This risk will require careful consideration in the design of the site layout and vertical alignments of the distributor roads to ensure flow paths do not impact on any proposed or existing developments.

• There is limited flood history for the area. The Environment Agency has indicated that a map of the historic flood outline on the site is attributable to the Afon Lwyd. However, Atkins’ previous study for the Burton’s Biscuits’ site suggests that this flooding derived from hydraulic overload of the foul sewerage system. We understand that this risk has been mitigated by Welsh Water’s work to the Eastern Valleys Trunk Sewer.


7. Proposed Activities to produce a Flood Consequences Assessment

7.1 Production of the Flood Consequences Assessment

Following the Phase 1 FCA Scoping study, there remains a number of uncertainties as to the extent of the flood risk to the site from the Cwmbran Brook and Afon Lwyd.

We would propose that the following activities are required to assess the level of flood risk to allow Flood Consequences Assessment to be prepared for the site.

The amount of reporting necessary will be dependent on the results of the respective assessments of the Cwmbran Brook and Afon Lwyd.

A summary of the activities required is provided below. Itemised costing of the activities is provided separately.

We propose the following:

Define the Risk from the Afon Lwyd

Establish revised flood levels for the reach of Afon Lwyd adjacent to the site, extending from Llanfrechfa Way Bridge downstream to Newport Road Bridge. The activity will include:

• Derive a flood frequency relationship at a single point (Newport Road Bridge) to current to current guidance and industry best practice as input to a hydraulic model.

• As part of the hydrological assessment, procure and analyse Gauge data at Ponthir Gauging Station.

• Provide the resulting peak flow estimates to the Environment Agency for agreement. • Procure the Environment Agency’s 1D HEC RAS hydraulic model and an associated licence

to use (fee applies). • Run the model using the revised flood frequency relationship (once agreed with EA) to derive

flood levels on the Afon Lwyd. • Carry out sensitivity tests on the model results. • Map the extent of the 1% chance (including climate change) and 0.1% (1 in 1000) chance

flood levels across the proposed development site, based on the site survey levels. • Consider the significance of the rail embankment in providing informal flood defence to the

site. • Assess any areas which may without mitigation, fail to comply with the indicative acceptance

criteria described in TAN15. • Advise the client of the extent of flooding over the site.


Define the risk from the Cwmbran Brook

To assess the flood levels in the open channel reach of the brook to the twin rail culverts and the magnitude of potential overland flows which may develop towards the site.

• Assess upstream catchments of brook.

• Liaison with Torfaen Land Drainage for any existing records of culverted sections of the Cwmbran Brook.

• Engineer’s site visit to assess dimensions of the key culverts on Cwmbran Brook

• Undertake hand calculations to determine culvert capacities

• Assess potential spill points along the Cwmbran Brook

• Undertake hydrological assessment of the peak flows on the Brook catchment, recognising the inherent uncertainty in assessing flow from an ungauged catchment.

• Undertake semi quantitative assessment of the overland flow paths which might develop to locations away from the brook or the Cold Store Site.

• Assess the order of magnitude of the peak flows likely to develop in the open channel. These will be limited to flow capacity of the upstream culverts and any overland flow which can find its way back to the channel.

• Agree assessed flows with the Environment Agency

The approach to assessing flows from the upstream catchment avoids complicated modelling of the Cwmbran Brook. If it is not accepted by the EA, we will need to consider other ways of assessing the flood risk which may result in increased costs. Assuming agreement, however, the following activities are proposed.

• Test the agreed flows in the existing Atkins 1D steady state HEC RAS model of the Cwmbran Brook to assess flood levels for reference flood events for TAN15 criteria.

• Estimate by hand calculations the scale of overland flows likely to affect the site due to overtopping from the Cwmbran Brook.

• With reference to earlier assessments, consider and comment on the risk of blockage of the rail culverts.

• Assess any areas which may without mitigation, fail to comply with the indicative acceptance criteria described in TAN15.

• Advise the client of the extent of flooding over the site.

• Scope potential mitigation options if necessary

Other sources of flooding

These are to be assessed based on existing information as described in sections 4.4 and 4.5, above.

Reporting/Outputs

• Assess the site against the indicative acceptability criteria contained in TAN15. • Produce Flood Consequences Assessment in format suitable for submission in support of a

planning application. • Package hydraulic models and calculation records for submission to the Environment

Agency. • Produce a maximum of 4 No. Drawings in GIS or AutoCAD format


Appendix A

A.1 Correspondence from Environment Agency Wales

Environment Agency Development & Flood Risk, e-mail indicating of extent of FCA Required – dated 10 March

Environment Agency Planning Liaison Letter– dated 31 March

1

Harries, Dominic M

Subject: FW: FCA requirement for proposed development - Cwmbran

From: Walker, Rebecca [mailto:[email protected]]

Sent: 10 March 2011 14:49

To: Harries, Dominic M

Subject: RE: FCA requirement for proposed development - Cwmbran

Good Morning Dominic Having looked at your proposed development site, I can confirm that it is not in either the Dam zone C1/C2 and apart from the area located behind the building (indicated on the flood map) not within the extreme flood outlines of the 1 in 100 year or 1 in 1000 year. Therefore we would not seek further information in the form of a FCA. Should you still require a site meeting, I am sorry but I have double booked myself, so could we please re-arrange the day. If you have any queries, please feel free to contact me. Kind Regards Becky Becky Walker

Development and Flood Risk

Environment Agency Wales

Ext: 7 26 2170 Tel: +44 (0) 29 2024 5170 Fax: +44 (0) 29 2036 2920 Rivers House, St Mellons Business Park, Cardiff, CF3 0EY

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