PDPF GP Ltd and Rega Ltd Junction 1 Retail Park New Retail ... Scanned... · Report 241074-001 Flood Risk Assessment for Junction 1 Retail Park, Rugby Page 2 of 18 CONTENTS Page 1

PDPF GP Ltd and Rega Ltd

Junction 1 Retail Park

New Retail Unit & Pod Units

Rugby, Warwickshire

Level 1 Flood Risk Assessment Report

Report no. 241074-01

October 2009

Safeguardingyour business

environment

Report 241074-001 Flood Risk Assessment for Junction 1 Retail Park, Rugby Page 2 of 18

CONTENTS

Page

1. INTRODUCTION 5 1.1 Purpose of Assessment 5 1.2 Level 1 Flood Risk Assessment 5 1.3 Limitations 5

2. SITE AND DEVELOPMENT DETAILS 6 2.1 Site Location and Description 6 2.2 Site Level Survey 6 2.3 Development Proposals 6

3. GEOLOGY AND HYDROGEOLOGY 8 3.1 Published Geology 8 3.2 Published Hydrogeology 8

4. IDENTIFICATION OF POTENTIAL SOURCES OF FLOODING 9 4.1 Outline of Catchment, Watercourse and Floodplain Characteristics 9 4.2 Strategic Flood Risk Assessment 9 4.3 Existing Flood Mitigation and Defence Measures 9 4.4 History of Flooding 9 4.5 Potential Sources of Flooding 10

5. POTENTIAL IMPACT OF PROPOSED DEVELOPMENT 11 5.1 Risk of Flooding and Effects on Proposed Development 11

5.1.1 Fluvial Flooding Risk 11 5.1.2 Existing and Post-Development Flood Flow and Flood Storage Situation 12 5.1.3 Flood Risk from Surface Water Runoff Generated On site 12 5.1.5 Flood Risk from Man-Made Drainage Systems 13 5.1.6 Flood Risk from Groundwater 13

5.2 Sustainable Drainage Systems 13 5.3 PPS25 Sequential Test and Exception Test 13

6. MITIGATION MEASURES AND RESIDUAL RISKS 15 6.1 Flood Alleviation Measures 15 6.2 Fluvial Freeboard Design 15 6.3 Flood Resistant Design 15 6.4 Safe Access and Exit 15 6.5 Flood Warning 15 6.6 Residual Risks 16

6.6.1 Residual Flood Risk 16 6.6.2 Social, Health and Safety Consequences 16 6.6.3 Economic Costs 16 6.6.4 Environmental Consequences 16

7. SUMMARY AND CONCLUSIONS 17


TABLES 2.1 Summary of Land Level Information 3.1 Conjectural geological succession beneath the site 4.1 Classification of Site from Environment Agency’s published Floodplain Map 4.2 Historical Flood Events on the River Avon 4.3 Flood Mechanisms Potentially Affecting Site 5.1 Flood Level Data for the River Avon 6.1 Advisory Minimum Finished Levels for Proposed New Development FIGURES Figure 1 Site Location Plan Figure 2 Existing Site Layout Plan Figure 3 Proposed Site Layout Plan: Dreams Store Figure 4 Proposed Site Layout Plan: Pod Units Figure 5 Environment Agency’s Internet Published Indicative Flood Zones Figure 6 Environment Agency’s Flood Zones and Model Node Points APPENDICES Appendix A Planning Policy Statement 25, Annex E Appendix B Information Received from the Environment Agency Appendix C Information Received from Warwickshire County Council Appendix D Information Received from Severn Trent Water – To Follow Appendix E Site Topographical Survey

RSK STATS Geoconsult Limited18 Frogmore RoadHemel Hempstead

HertfordshireHP3 9RT

UK

Telephone: +44 (0)1442 437500Fax: +44 (0)1442 437550

www.rsk.co.uk

RSK STATS Geoconsult LtdRegistered office

Spring Lodge • 172 Chester Road • Helsby • Cheshire • WA6 0AR • UKRegistered in England No. 2611785

www.rsk.co.uk

DOCUMENT CONTROL

Document Title: Level 1 Flood Risk Assessment Report Junction 1 Retail Park, Rugby

The Client: PDPF GP Ltd and Rega Ltd c/o TIS Property Services Ltd The Lodge Heriots The Common Stanmore Middlesex HA7 3HG

RSK STATS Geoconsult Limited (RSK) has prepared this report in accordance with the instructions of Indigo Planning Limited acting on behalf of PDPF GP Ltd & Rega Ltd c/o TIS Property Ltd (“The Client”) and under the terms of appointment for RSK. This report is confidential and non-assignable by the Client and RSK shall not be responsible for any use of the report or its contents for any purpose other than that for which it was prepared and provided. Should the Client require to pass copies of the report to other parties for information, the whole of the report should be so copied, but no professional liability or warranty shall be extended to other parties by RSK in this connection without the explicit written agreement thereto by RSK.

Report Number 241074-001

Status FINAL

Date of issue 30th October 2009

Prepared by Emma Evans

Graduate Hydrologist

Reviewed by Matthew Cheeseman

Senior Hydrologist

Approved by Adrian Marsh

Director

Page no 4 of 18


1. INTRODUCTION

1.1 Purpose of Assessment

On the instructions of Indigo Planning Limited acting on behalf of PDPF GP Ltd & Rega Ltd c/o TIS Property Ltd, RSK STATS Geoconsult Limited has carried out a Level 1 Flood Risk Assessment for proposed additional building developments at Junction 1 Retail Park, Rugby. With respect to flood risk, the site lies within Flood Zone 3, therefore a Flood Risk Assessment will be required for any planning application at the site in accordance with Planning Policy Statement 25 (PPS25).

1.2 Level 1 Flood Risk Assessment

The assessment was commissioned principally in order to determine the risk of the site being flooded, the impacts of the proposed development on flood risk elsewhere in the catchment and the impacts in the event that the site is flooded.

The Flood Risk Assessment has been undertaken in accordance with Annex E of PPS25 “Development and Flood Risk” published by the DCLG (December 2006), as reproduced in Appendix A, and takes account of current Environment Agency guidelines for general developments within the flood plain.

The project has mainly utilised information provided by the Environment Agency (EA), Warwickshire County Council, Severn Trent Water, a site topographical survey and information gathered during the site reconnaissance visit.

1.3 Limitations

Floods are natural occurrences and the risks they pose are wide ranging. This study is primarily concerned with the risk to people and property from fluvial flooding associated with the River Avon and the River Swift, There is no statutory or regulatory requirement setting a minimum level of acceptable risk in relation to public use development. Table D.1 in PPS25 provides some guidance on flood zones related to the annual probability of river flooding, with “low probability” being defined at an annual probability of <0.1%, “medium probability” at 1% to 0.1% probability and “risk probability” at >1%.

The risk of flood events occurring may most simply be expressed as an annual probability, e.g. a 1% annual probability flood. This event has been translated into having a “return period” of 100 years, or the 1-in-100 year event, after rounding. It is important to recognise that a 1% annual probability flood has a 26% chance of being equalled or exceeded at least once in 30 years (the duration of a typical mortgage) and a 49% probability of being equalled or exceeded at least once in 70 years. The 1% annual probability flood also has a 15% chance of occurring twice in 70 years.

Traditionally, design considerations for ordinary commercial development focus on the Design Flood Event and typically the 1% annual probability of fluvial flooding (or 100 year flood event) or the 1 in 200 year tidal event. This 1 in 100 year fluvial flood level has been adopted as the design flood condition in this study but strictly in the knowledge that this equates to a significant residual risk of flooding occurring, as discussed above.


2. SITE AND DEVELOPMENT DETAILS

2.1 Site Location and Description

The site is located at National Grid reference 450542E 276651N, and the whole retail park development covers approximately 6.5hectares. The site is situated within the northern area of Rugby in a mainly industrial/commercial area. The retail park contains a number of large retail units located along its southern side and a Cinema on its eastern side. The remainder of the site comprises car parking, access roads and three fast food restaurants located close to the northern border of the site. A small area of undeveloped land is located in the north of the site to the east of the fast food restaurants.

The site is bounded to the north and west by the River Avon. The River Swift’s confluence with the River Avon is located just beyond the northern-most point of the site.

An extract of the 1:50,000 Ordnance Survey map showing the location of the site is included in Figure 1 and an existing site layout plan in Figure 2.

2.2 Site Level Survey

A topographic survey of the site has been undertaken and the ground levels on site are summarised in Table 2.1 and the Survey is reproduced in Appendix E.

Table 2.1 Summary of Existing Land Level Information Item Level (mAOD) Source Comment

Maximum and minimum ground levels on site

Min = 85.88

Max = 87.00

Measured site survey

Minimum level taken from western exit to roundabout

Maximum level taken from northern exit off roundabout

Ground Levels in the vicinity of the proposed Retail Unit

Min = 86.19

Max = 86.55


Ground Levels in the vicinity of the proposed Pod Units

Min = 86.27

Max = 86.52


Ground Levels in the centre of Site

86.20 Measured site survey

Water Level in River Avon at River Swift Confluence


Level taken from Left Bank

Bed Level in River Avon at River Swift Confluence


Level taken from Left Bank

Water Level in River Avon upstream of Site Access Bridge


Level taken from Right Bank

Bed Level in River Avon upstream of Site Access Bridge


Level taken from Right Bank

2.3 Development Proposals

The development proposals for the site will involve the following:

• The development of a 359sqm-retail unit located in the south western section of the overall retail park site adjoining the existing Dreams Store. A plan showing the location of this unit is contained in Figure 3.


• The development of 3 pod retail units with a total footprint of 325sqm, located on the northern side of the main central existing car park. A plan showing the location of this unit is contained in Figure 4.


3. GEOLOGY AND HYDROGEOLOGY

3.1 Published Geology

The published 1:50,000-scale geological map of the area (Sheet No 184, “Warwick”) indicates that the site is directly underlain by superficial deposits of Alluvium, which is further underlain by River Terrace Deposits. These superficial deposits are underlain by Mudstones and Limestones of the Lower Lias Formation.

On the basis of the published geological maps of the area the full succession of natural strata in the vicinity of the site is likely to comprise: Table 3.1 - Conjectural geological succession beneath the site

Geological Unit Brief Description Anticipated Thickness

Superficial Soils/Drift

Alluvium Gravel, sand and silt a few metres

River Terrace Deposits Sand and gravel, locally with lenses of silt, clay or peat

a few metres

Solid Geology Deposits

Undivided Limestone (Lower Lias)

Grey mudstones with concretionary and tabular argillaceous limestone, ironstone or sandstone.

>75m

The existing topography and history of development of the site suggests that in addition to these natural strata some made ground may be present on the site.

3.2 Published Hydrogeology

The hydrogeology of the site is likely to be characterised by the presence of a shallow aquifer that underlies the site, associated with the Alluvium and River Terrace Deposits. These deposits are classified by the EA as a Minor Aquifer (as indicated on the EA’s Groundwater Vulnerability Map of the area, Sheet No. 30 ‘Northern Cotswolds).

Shallow groundwater in the site area is anticipated to flow in a west/northwest direction, i.e. towards and in the direction of flow of the River Avon.


4. IDENTIFICATION OF POTENTIAL SOURCES OF FLOODING

4.1 Outline of Catchment, Watercourse and Floodplain Characteristics

The nearest surface watercourses to the site are described as follows:

• River Avon borders the north and west of the site, and flows in a west/south westerly direction. The Avon flows in an oversized channel adjacent to the site which is approximately 22 – 35m wide at bank-full level.

• The River Swift is located directly to the north of the site and flows in a north to south direction towards its confluence with the River Avon. The channel of the River Swift is between 5 and 9m wide and the river flows over a small weir before flowing into the Avon.

The Environment Agency’s internet published floodplain map is reproduced in Figure 5. This flood map indicates that with respect to flood risk the whole site is classified approximately as follows:

Table 4.1 Classification of Site from Environment Agency’s published Floodplain Map Flood Zone Flood Risk Area of Site Classified

1 ‘Low Probability’ (Probability of fluvial flooding of <0.1%)

0% of site

2 ‘Medium Probability’ (Probability of fluvial flooding of 1% to 0.1%)

0% of site

3 ‘High Probability’ (Probability of fluvial flooding of >1%).

100% of site

4.2 Strategic Flood Risk Assessment

A Strategic Flood Risk Assessment (SFRA) was undertaken for Warwickshire County Council by Halcrow Group and published in February 2008. The Final version of the document is available on Warwickshire County Council website, which is as follows

http://www.warwickshire.gov.uk/Web/corporate/pages.nsf/Links/EAEDF813709ABB2E802573DB0039E0CE/$file/Warwickshire+Level+1+SFRA+Report.PDF

The SFRA states that the River Avon has flooded on several occasions in Rugby, however, there is no specific reference to the site having been flooded in the past.

4.3 Existing Flood Mitigation and Defence Measures

There are no formal flood defences that protect the site according to the floodmap provided by the EA. However, following correspondence and liaison with the EA it has been suggested that the left bank of the Avon, which borders the north and west of the site, is capable of containing the 1 in 100-year event. This prediction will be further analysed in Section 5.

4.4 History of Flooding

Neither the EA nor Warwickshire County Council has any historical records of the site having been affected by flooding in the past.

A historical flood level has been provided by the EA, which is as follows:


Table 4.2: Historical Flood Events on the River Avon Node Date Recorded Level Value X Y

662 10/04/1998 84.06 450270 276670

According to the topographical survey of the site this historical level is lower than ground levels on the existing site level and therefore would not have encroached onto the site.

4.5 Potential Sources of Flooding

Based on a review of the site characteristics, the proposed development and the flooding related information summarised above, the potential sources of flooding that could affect the subject site and proposed development are summarised in Table 4.3.

Table 4.3 Flood Mechanisms Potentially Affecting Site

Affecting Flood Source Mechanism

Typical impact On site

Fluvial (The River Avon & River Swift)

Extreme flood water levels leading to out of bank river flow caused by overtopping and surcharging culverts.

Up to regional scale impacts, including transport

Buildings (entering through doors, ducts and other openings), external paved and landscaped areas.

Surface runoff from storm water

Excessive runoff from site/surroundings. Overland flow resulting from overloading of local drains.

Up to neighbourhood scale impacts, including transport

Probably entering site from adjacent streets pavements. Could inundate services and landscaped areas.

Rising groundwater in shallow aquifer

Groundwater level in the shallow aquifer rising during recharge from high river levels and/or infiltration and/or from the deep aquifer.

Typically site-specific only

Should this exceed level of services it could infiltrate and flood causing reduced drainage and infiltration of surface water

Drainage services

Blockages and/or insufficient capacity of drainage & foul sewers, typically linked to storm water events.

Up to neighbourhood scale impacts, including transport

Backing up causing increased surface run-off, standing water and possibly entering buildings, especially any basements

Water supply services

Leaks Typically site-specific only

Leaks typically have limited impact, but may exacerbate flooding from other sources.


5. POTENTIAL IMPACT OF PROPOSED DEVELOPMENT

5.1 Risk of Flooding and Effects on Proposed Development

The principal potential flood mechanisms, identified in Section 4.6, are fluvial flooding from the River Avon and River Swift, flooding from local surface water runoff, groundwater flooding, overflowing drains and leaking water supply services. The risk from these sources of potential flooding, together with the likely impacts, are considered below on the basis of the findings set out in the preceding Chapters.

5.1.1 Fluvial Flooding Risk

The EA’s flood maps show that the site lies within the fluvial floodplain associated with the River Avon and/or the River Swift.

The Environment Agency has provided modelled fluvial flood levels for the River Avon ranging from the 1 in 5 year to the 1 in 100 year flood level. These are contained in Appendix B and summarised in Table 5.1 below. The information and levels generated by the detailed modelling are generally considered to be the best available to the EA. This data will therefore be used to review the site in terms of flood risk from the River Avon. The locations of the River Avon model nodes are shown in Figure 6.

Table 5.1 Flood Level Data for the River Avon

Return Period (years) and Flood Level (mAOD)

Node 1 in 5 1 in 10 1 in 25 1 in 50 1 in 100 X Y

M_LS_07_2502_120 84.02 84.35 84.72 84.98 85.25 450739 276720

M_LS_07_2502_122 83.96 84.30 84.67 84.94 85.22 450571 276790

M_LS_07_2502_123 83.87 84.22 84.59 84.85 85.13 450500 276780

M_LS_07_2502_124 83.69 84.02 84.39 84.65 84.92 450408 276725

M_LS_07_2502_125 83.53 83.85 84.20 84.45 84.70 450313 276655

M_LS_07_2502_127 83.51 83.84 84.19 84.44 84.70 450285 276619

The EA usually recommend the 1 in 100-year fluvial flood level be used to assess the site. Reference to the level information contained in Table 5.1 indicates that the 1 in 100 year flood level at the upstream site boundary is 85.25mAOD falling to 84.70mAOD at the downstream site boundary.

Reference to the site topographical survey and levels, summarised in Table 5.1, show that the site ranges from 85.88mAOD to 87.00mAOD. It is clear from this information that the site would remain unaffected by flooding during the 1 in 100 year flood event, indicating that the EA’s internet published flood maps are inaccurate.

With specific reference to the proposed new unit adjacent to Dreams, and the new Pod units located in the car park, the following conclusions can be drawn:


• Proposed New Retail Unit adjacent to Dreams

The modelled node point nearest to the proposed new retail unit next to Dreams is M_LS_07_2502_124. Reference to the level information contained in Table 5.1 indicates that the 1 in 100 year flood level nearest the proposed retail unit is 84.92mAOD.

Reference to the site topographic survey shows the minimum ground level of the proposed retail unit is 86.19mAOD.

It is therefore clear from this information that this area of the overall retail park site is not at risk from fluvial flooding during the 1 in 100 year event as the modelled flood level is 1.27m below the minimum ground level in the footprint area of the proposed new Unit.

• Proposed New Pod Units

The modelled node point nearest to the proposed new pod units is M_LS_07_2502_122. Reference to the level information contained in Table 5.1 indicates that the 1 in 100 year flood level nearest the proposed retail unit is 85.22mAOD.

Reference to the site topographic survey shows the minimum ground level of the proposed retail unit is 86.27mAOD.

It is therefore clear from this information that this area of the overall retail park site is not at risk from fluvial flooding during the 1 in 100 year event as the modelled flood level is 1.05m below the minimum ground level in the footprint area of the proposed new Pod Units.

Although there is no allowance for climate change on the modelled flood levels supplied by the EA, it is considered that the freeboard levels of 1.27m and 1.05m above the 1 in 100-year flood level will ensure that there will be sufficient freeboard in the event of the 1 in 100-year climate change flood event to ensure that the new units remain dry.

5.1.2 Existing and Post-Development Flood Flow and Flood Storage Situation

It has been established from the site topographic survey and the modelled flood levels provided by the EA that the whole site lies outside the 1 in 100 year floodplain. Thus establishing that the proposed new units will not have any adverse effect on either flood flows or floodplain storage during the 1 in 100-year flood event.

5.1.3 Flood Risk from Surface Water Runoff Generated On site

Flooding from overland flow occurs when water flows over the ground surface that has not entered a natural or artificial drainage channel and commonly occurs following intense rainfall that exceeds the infiltration capacity the ground and any surface water drainage systems.

The existing surface runoff from the site appears to discharge via a number of flapped outfalls into the River Avon. The proposal is for the two developments to be built on areas covered with existing hardstanding. Hence there will be no additional surface runoff generated from the site, putting no additional surface water flow into the surrounding surface water drainage system and receiving watercourse. The flood risk associated with increased surface runoff being generated from the site should remain as low.


5.1.4 Flooding from Off-Site Surface Runoff

The site is bordered to the north and west by soft landscaping adjacent to the channel of the River Avon. The industrial area to the east is set at a lower level than the site and the area to the south is currently being redeveloped. The risk from off-site runoff flowing onto the site is classified as low.

5.1.5 Flood Risk from Man-Made Drainage Systems

Flooding from artificial drainage systems may occur at the site from blocking or overloading of pipes or sewers or failure of pumping systems. Sewers and surface water drains are often very old and generally designed to a lower standard, such as 1 in 10 year standard. As a result, the flood risk associated with sewer flooding is generally higher in long-established urban areas than from other sources although the consequences are usually limited in extent.

On the basis that any new foul water sewerage and surface water systems for the proposed redevelopment will be designed to meet the specifications of Severn Trent Water this should ensure that the systems have sufficient capacity to prevent overloading under the normal range of operating conditions. This should ensure that the flood risk from new artificial drainage systems should therefore be low.

5.1.6 Flood Risk from Groundwater

The risk from groundwater flooding stems from the presence of a shallow aquifer located in the superficial Alluvium and River Terrace Deposits beneath the site. This aquifer is potentially in hydraulic continuity with the nearby surface watercourses. In periods of sustained elevated river flow conditions, water levels in the shallow aquifer will probably also rise.

A predicted result of climate change is wetter winters that may lead to increased groundwater levels and as such potentially increasing the risk of groundwater flooding. In recognition of this, proper consideration should be given to any deep service installations or basements that may will intercept the groundwater table and these should be designed to resist hydrostatic water pressures and capillary rise water

The risk of rising water levels in the shallow aquifer breaking surface is assessed as low.

5.2 Sustainable Drainage Systems

Given the minor scale of the proposed changes to the overall retail park site, and given that there will be no increase in surface runoff from the site, it is not considered necessary to incorporate any Sustainable Drainage Systems (SUDs) into the scheme.

5.3 PPS25 Sequential Test and Exception Test

Within the context of PPS25 the proposed development would most likely be classed as “Less Vulnerable” on the Flood Risk Vulnerability Classification given in PPS25 Annex D Table D.2.

Less Vulnerable developments are considered appropriate uses of land in Flood Zones 1, 2 and 3a according to PPS25 Annex D Table D.1, subject to various conditions being met. These conditions relate to ensuring that the impact of any flooding on the development and any impact that the development has off site are both taken into account and managed to minimise the overall impacts to an acceptable level.

As the areas earmarked for development have been proven to lie well above the 1 in 100 year flood level, it is concluded that the proposed development satisfies the requirements of the


PPS25 Sequential Test and there is no need to have recourse to the Exception Test. The proposed type of development is therefore an appropriate use of land with respect to flood risk.


6. MITIGATION MEASURES AND RESIDUAL RISKS

6.1 Flood Alleviation Measures

As a result of the flood risk assessment studies at the site it has been concluded that there is no need for any specific flood alleviation and mitigation measures, as discussed below.

6.2 Fluvial Freeboard Design

The Environment Agency typically advises three minimum freeboard levels with respect to the flood design levels for proposed residential elements in new developments relating to the 1 in 100-year + 20% climate change flood level, as set out in Table 6.1.

Table 6.1 Advisory Minimum Finished Levels for Proposed New Development Residential Element of Development EA’s Flood-Related Criterion

Ground Floors Flood Level + 600mm freeboard

Dry External Access/Egress Flood Level + 600mm freeboard

Car Parking 200mm maximum depth of flooding

There are no specific guidelines relating to retail developments, but the two areas of the site earmarked for the new retail units have been found to be a minimum of 1.05m above the 1 in 100 year flood level, which is considered more then sufficient freeboard.

6.3 Flood Resistant Design

Following on from the conclusions drawn above it is not considered necessary to include the use of flood resistant design features to the proposed developments.

6.4 Safe Access and Exit

Although the site is located within the EA’s internet published fluvial Flood Zone 3 associated with the River Avon, it has been established that the site is actually located at a higher level than that modelled for the 1 in 100 year flood event and therefore safe access would be available from both proposed new units.

6.5 Flood Warning

Although the main retail park site has been found to lie well above the 1 in 100 year flood level, the close proximity of the Rivers Avon and Swift and the occasional incidents of flooding that have affected nearby parts of the town indicate that access to and from the retail park could be disrupted by flooding off site in the future. To minimise the impact of such disruption consideration should be given to the most appropriate ways of linking into the regional flood warning system and to the adoption of appropriate emergence procedures. Such a Flood Management System will principally be aimed at minimising the risk to human health and safety should an extreme flood event occur and should include:

• The extent of the floodplain in the area and make users aware of the EA’s regional Flood Warning system in order to provide adequate warning in advance of floodwaters reaching the site.

• Show the nearest watercourse and direction of flow.

• Contain contact details of the relevant emergency services in case of an emergency.


6.6 Residual Risks

6.6.1 Residual Flood Risk

Given the conclusions above, the residual flood risks, i.e. the risks that exist after mitigating measures have been implemented, are considered to be low.

6.6.2 Social, Health and Safety Consequences

The social impacts (e.g. psychological effects and stress from loss of personal possessions, loss of property value, temporary housing loss and disruption of transport and emergency services) are likely to be minimal as the proposed retail units are set above the 1 in 100 year flood level.

6.6.3 Economic Costs

The economic costs associated with any flooding of the site could be significant if floodwaters were ever to reach the site. Depending upon the severity of flooding, these costs could relate to a variety of losses, including:

• damage to the buildings, building services and associated clean-up, repair and replacement costs;

• damage to property and belongings inside buildings and vehicles parked in flooded areas; and

• loss of capital/rental value of the property.

6.6.4 Environmental Consequences

Given the location and the continued proposed future use of the site as a commercial retail park development, the environmental impacts on natural habitats and resources caused by a flooding event are considered to be minimal.


7. SUMMARY AND CONCLUSIONS

A Level 1 Flood Risk Assessment has been undertaken with respect of the proposed development of a new retail unit and 3 pod units within the existing Junction Retail Park, Rugby.

The Environment Agency’s (EA) Internet published flood map shows that the site lies within the Flood Zone 3 associated with the River Avon. However, the site specific status of the retail park has been checked with reference to the latest river modelling output supplied by the EA and a detailed topographic survey of the site.

Reference to the river modelling level information indicates that the 1 in 100 year flood level at the upstream site boundary is 85.25mAOD falling to 84.70mAOD at the downstream site boundary. Reference to the site topographical survey and levels, summarised in Table 5.1, show that the site ranges from 85.88mAOD to 87.00mAOD.

It is clear from this information that the entire site would remain unaffected by flooding during the 1 in 100 year flood event, indicating that the EA’s flood maps are inaccurate. In relation to the proposed two new areas of development within the retail park:

Proposed New Retail Unit adjacent to Dreams

The modelled node point nearest to the proposed new retail unit next to Dreams is M_LS_07_2502_124. Reference to the level information contained in Table 5.1 indicates that the 1 in 100 year flood level nearest the proposed retail unit is 84.92mAOD. Reference to the site topographic survey shows the minimum ground level of the proposed retail unit is 86.19mAOD. It is therefore clear from this information that this area of the site is not at risk from fluvial flooding during the 1 in 100 year event as the modelled flood level is 1.27m below the minimum ground level in the footprint area of the proposed new Unit.

Proposed New Pod Units

The modelled node point nearest to the proposed new pod units is M_LS_07_2502_122. Reference to the level information contained in Table 5.1 indicates that the 1 in 100 year flood level nearest the proposed retail unit is 85.22mAOD. Reference to the site topographic survey shows the minimum ground level of the proposed retail unit is 86.27mAOD. It is therefore clear from this information that this area of the site is not at risk from fluvial flooding during the 1 in 100 year event as the modelled flood level is 1.05m below the minimum ground level in the footprint area of the proposed new Pod Units.

Although there is no allowance for climate change on the modelled flood levels supplied by the EA, it is considered that the freeboard levels of 1.27m and 1.05m above the 1 in 100-year flood level will ensure that there will be sufficient freeboard in the event of the 1 in 100-year climate change flood event to ensure that the units remain dry.

It has been established from the site topographic survey and the modelled flood levels provided by the EA that the whole site lies outside the 1 in 100 year floodplain. Thus establishing that the proposed new units will not have any adverse effect on either flood flows or floodplain storage during the 1 in 100-year flood event. The flood risk associated with increased surface runoff being generated from the site is assessed as low.

The risk from off-site runoff flowing onto the site is classified as low. The flood risk from new artificial drainage systems is assessed as low.


Given the minor scale of the proposed changes to the site, and given that there will be no increase in surface runoff from the site, it is not considered necessary to incorporate any Sustainable Drainage Systems (SUDs) into the scheme. The areas earmarked for development have been proven to lie well above the 1 in 100 year flood level, it is therefore concluded that the proposed development satisfies the requirements of the PPS25 Sequential Test and there is no need to have recourse to the Exception Test. The proposed type of development is therefore an appropriate use of land with respect to flood risk.

Although the main retail park site has been found to lie well above the 1 in 100 year flood level, the close proximity of the Rivers Avon and Swift and the occasional incidents of flooding that have affected nearby parts of the town indicate that access to and from the retail park could be disrupted by flooding off site in the future. To minimise the impact of such disruption consideration should be given to the most appropriate ways of linking into the regional flood warning system and to the adoption of appropriate emergence procedures.

Report 241074-001 Flood Risk Assessment for Junction 1 Retail Park, Rugby

FIGURES

(this section contains 7 pages, including this one)

Reproduced from Ordnance Survey mapping with the permission of the Controller of Her Majesty’s Stationery Office. Crown Copyright reserved (Licence No: 100002620)

Client: PDPF GP Ltd and Rega Ltd Figure: 1

Site: Junction One Retail Park Job No: 241074-001

SITE LOCATION

PLAN Scale: NTS Source: Promap

The Site

Reproduced from Ordnance Survey mapping with the permission of the Controller of Her Majesty’s Stationery Office. Crown Copyright reserved (Licence No: 100002620)

Client: PDPF GP Ltd and Rega Ltd Figure: 2


SITE LAYOUT

PLAN Scale: NTS Source: Client

Client: PDPF GP Ltd and Rega Ltd Figure No: 3


PROPOSED SITE LAYOUT PLAN SHOWING NEW RETAIL UNIT

Scale: NTS Source: RGP


Site: Junction One Retail Park, Job No: 241074-001

PROPOSED SITE LAYOUT PLAN SHOWING NEW POD RETAIL UNITS

Scale: NTS Source: RGP



THE ENVIRONMENT AGENCY’S PUBLISHED FLOOD MAP

Scale: NTS Source: Environment Agency

The Site



THE ENVIRONMENT AGENCY’S FLOOD MAP SHOWING MODEL NODE

LOCATIONS Scale: NTS Source: Environment Agency


APPENDIX A

PPS25 Development and Flood Risk

Annex E The Assessment of Flood Risk, General Principles

(DCLG, December 2006)

(this appendix contains 2 pages, including this one)


GUIDANCE ON REQUIREMENTS FOR UNDERTAKING A FLOOD RISK ASSESSMENT (ANNEX E OF PPS25 (DCLG, 2006))

Annex E: The Assessment of Flood Risk

General Principles E1. Properly prepared assessments of flood risk will inform the decision-making process at all stages of development planning. There should be iteration between the different levels of flood risk assessment.

E2. Any organisation or person proposing a development must consider whether that development will not add to and should where practicable reduce flood risk. The future users of the development must not be placed in danger from flood hazards and should remain safe throughout the lifetime of the plan or proposed development and land use.

E3. At all stages of the planning process, the minimum requirements for flood risk assessments are that they should:

• be proportionate to the risk and appropriate to the scale, nature and location of the development;

• consider the risk of flooding arising from the development in addition to the risk of flooding to the development;

• take the impacts of climate change into account (see PPS25 Annex B);

• be undertaken by competent people, as early as possible in the particular planning process, to avoid misplaced effort and raising landowners expectations where land is unsuitable for development;

• consider both the potential adverse and beneficial effects of flood risk management infrastructure including raised defences, flow channels, flood storage areas and other artificial features together with the consequences of their failure;

• consider the vulnerability of those that could occupy and use the development, taking account of the Sequential and Exception Tests and the vulnerability classification (see PPS25 Annex D), including arrangements for safe access;

• consider and quantify the different types of flooding (whether from natural and human sources and including joint and cumulative effects) and identify flood risk reduction measures so that assessments are fit for the purpose of the decisions being made;

• consider the effects of a range of flooding events including extreme events on people, property, the natural and historic environment and river and coastal processes;

• include the assessment of the remaining (known as ‘residual’) risk (see PPS25 Annex G) after risk reduction measures have been taken into account and demonstrate that this is acceptable for the particular development or land use;

• consider how the ability of water to soak into the ground may change with development, along with how the proposed layout of the development may affect drainage systems; and

• be supported by appropriate data and information including historical information on previous events.


APPENDIX B

Information Supplied by The Environment Agency



APPENDIX C

Information Supplied by Warwickshire County Council



Warwickshire County Council Strategic Flood Risk Assessment Web Address:

http://www.warwickshire.gov.uk/Web/corporate/pages.nsf/Links/EAEDF813709ABB2E802573DB0039E0CE


APPENDIX D

Information Supplied by Seven Trent Water

Information to follow


APPENDIX E

Site Topographical Survey


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