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41521914 Coleshill STW Dewatering Scheme: Flood Risk Assessment

COLESHILL STW DEWATERING SCHEME

FLOOD RISK ASSESSMENT

Document 41521914_FRA: Coleshill Dewatering: Flood Risk Assessment

Issue Date Status Prepared by Checked by Reviewed by Authorised for Issue

1 28/09/16 Planning Issue Krishna Dey Kelvin Limbrick Adrian Higgins Gareth

Wheatley


Contents

Page No

EXECUTIVE SUMMARY 1

1. INTRODUCTION 2

1.1. Purpose 2

1.2. Proposed Development Site 2

1.3. Report Objectives 2

1.4. Available Information 2

2. DESCRIPTION OF THE EXISTING SITE 3

2.1. Coleshill STW/SDP 3

3. DESCRIPTION OF THE PROPOSED DEVELOPMENT 4

3.1. Proposed development at Coleshill STW 4

4. POTENTIAL SOURCES OF FLOOD RISK 5

4.1. Sources of Flooding 5

5. FLOOD ZONES 6

5.1. Planning Practice Guidance Flood Zones 6

6. FLOOD RISKS TO THE SITE 7

6.1. Sources of Flooding 7

6.2. Flooding from Rivers and the Sea 7

6.3. Flooding from Land 9

6.4. Flooding from Groundwater 9

6.5. Flooding from Sewers 9

6.6. Flooding from Reservoirs, Canals and Other Artificial Sources 9

7. PLANNING PRACTICE GUIDANCE 10

7.1. Proposed Land Use Classification 10

7.2. PPG Requirements 10

7.3. Sequential Test 10

8. FLOOD RISK CONSIDERATIONS 11

8.1 Key Considerations 11

8.2 Remain Operational in Times of Flood 11

8.3 No Net Loss of Floodplain Storage 11

8.4 No Impediment to Flood Water Flows 12

8.5 Surface Water Runoff 12

8.6 Risks to People 13

8.7 Access to flood defence and management facilities 13

9. CONCLUSIONS 14


Page 1

EXECUTIVE SUMMARY

This document presents the findings of a Flood Risk Assessment (FRA) undertaken for a proposed development at Coleshill Sewage Treatment Works (STW). Coleshill STW is located on Marconi Way, Coleshill, Birmingham, Warwickshire (SP 19318 91270). The STW serves a population of 238,536 people.

The Coleshill STW and Sludge Destruction Plant (SDP) are located adjacent to the ‘Delta Junction’ on the proposed HS2 route. The access road will need to be realigned and large areas of the STW and SDP will need to be demolished and relocated to allow for the construction of this stretch of HS2. This FRA has been prepared to accompany the planning application for these relocated elements.

The areas of the proposed development site are shown to be located within Flood Zones 2 and 3 (Medium and High Probability, respectively) of the River Tame, which is classified as a Main River by the Environment Agency. As such, current planning regulations require that the planning application for the proposed development is accompanied by an appropriate Flood Risk Assessment (FRA).

This FRA has been prepared in accordance with the National Planning Policy Framework (NPPF) and supporting Planning Practice Guidance (PPG) and is intended to accompany a planning application for the proposed realignment of access road and relocation of parts of the STW and SDP.

The proposed development would be classified as ‘Less Vulnerable’ under the PPG and, therefore, suitable for location within Flood Zones 2 and 3. During the preparation of this FRA, the Environment Agency’s flood model of the Lower River Tame was applied to derive flood outlines and levels for different flooding scenarios.

This FRA confirms that the proposed development will meet the requirements of the NPPF/PPG. Specifically, this FRA has demonstrated that:

• The proposed land use is appropriate for location within Flood Zones 2 and 3 and the development proposals will not involve an increase in the number of staff working within a flood risk area;

• The proposed development will remain operational in times of flooding over the duration of its intended lifetime;

• The development proposals will result in no significant change in built footprint on site and will therefore not cause an adverse impact on floodplain storage or conveyance; and

• The new build will not result in an increase in the volume and rate of surface runoff leaving the site.

In summary, this FRA has demonstrated that the proposed development is appropriate for its location, will remain operational in times of flooding, and will not result in an increase in off-site flood risk.


Page 2

1. INTRODUCTION

1.1. Purpose

This document presents the findings of a Flood Risk Assessment (FRA) undertaken to accompany a planning application for the realignment of the site access road and elements of the Coleshill STW and SDP, required as a result of the construction of HS2.

The STW is located on Marconi Way, Coleshill, Birmingham, Warwickshire (SP 19318 91270). This FRA has been produced in accordance with the National Planning Policy Framework (NPPF) and supporting Planning Practice Guidance (PPG). The NPPF and PPG require that flood risk is taken into account at all stages of the planning process to ensure that new development is appropriate for its location, will remain safe, and will not increase flood risk elsewhere.

1.2. Proposed Development Site

The proposed development site is bounded by Edison Road to the North, Lichfield Road to the west and the River Tame to the south and east respectively. The River Tame is classified as a Main River by the Environment Agency. The description of existing site is detailed in section 2. The proposed development site layout is shown in Appendix A.

1.3. Report Objectives

The objectives of this report are to a) quantify the flood risk to the site; b) demonstrate that the proposed development will remain operational during flood conditions over its intended lifetime taking climate change into consideration; and c) demonstrate that the proposed development will not increase flood risk elsewhere.

This FRA concentrates on the flood risk issues over the operational lifetime of the proposed development.

1.4. Available Information

This assessment is based on the following available information:

• The existing site layout and areas of proposed development (Appendix A);

• Site Topographical survey (Appendix B);

• Environment Agency Flood Map – Rivers and Sea (Appendix C);

• Detailed fluvial flood risk mapping – 1 in 100 year plus 25% climate change event (Appendix D);

• Environment Agency Flood Map – Surface Water (Appendix E);

• Environment Agency Flood Map – Reservoirs (Appendix F); and

• Detailed fluvial flood risk mapping – 1 in 20 year event (Appendix G)


Page 3

2. DESCRIPTION OF THE EXISTING SITE

2.1. Coleshill STW/SDP

Coleshill Sewage Treatment Works (STW) is bordered to the north by the River Tame, the west by Severn Trent Water-owned non-operational land, the south by the Birmingham to Nuneaton railway line and to the east by Coleshill Parkway railway station. The STW currently serves a Population Equivalent (PE) of 238,536 which is predicted to reduce to 224,248 in 2017 due to the Barston project. The PE served is then expected to rise to 246,955 as a result of growth within the catchment by 2028.

Coleshill Sludge Destruction Plant (SDP) is bordered to the north by the Minworth STW effluent conduit, the west by the Birmingham to Tamworth railway line and the south and east by the River Tame. The SDP was originally constructed in 1972 adjacent to operational sludge drying beds and lagoons to process and incinerate digested sludge pumped from Minworth STW and indigenous sludge from Coleshill STW.

The grid reference (eastings, northings) for the site is:

419318, 291270

The postal address for the site is:

Coleshill Sewage Treatment Works Marconi Way, Coleshill, Warwickshire, B46 1DG. The existing site layout is shown in Appendix A and a plan showing ground levels from the topographical survey in Appendix B.

The responsibility for protecting the site infrastructure and ensuring its ongoing operation lies with Severn Trent Water Limited (STWL).

Large areas of the site of the proposed relocation of elements of the STW and SDP are currently undeveloped with grass coverage.


Page 4

3. DESCRIPTION OF THE PROPOSED DEVELOPMENT

3.1. Proposed development at Coleshill STW

Coleshill STW and Sludge Destruction Plant (SDP) are located adjacent to the ‘Delta Junction’ on the proposed HS2 route. The ‘Delta Junction’ will allow trains travelling from London to continue west to Birmingham and north to Manchester and Leeds (and vice versa).

The site access road will need to be realigned and large areas of the STW and SDP will need to be demolished and relocated to allow for the construction of this stretch of HS2. This FRA has been prepared to accompany the planning application for these relocated elements.

The sludge thickening/storage tanks, sludge blending tanks and associated pump stations, and sludge screening elements will all need to be relocated due to the construction of HS2. The HS2 programme requires these assets to be relocated by October 2018. Integrated into these replaced assets will be a Severn Trent Sludge Dewatering facility.

The area of the proposed development for which planning permission is required is ca. 1228 m². This area will form part of a wider boundary of 16,780m2 which will comprise additional elements of permitted development. HS2 will be affecting circa 32,300m2 of Severn Trent operational land area.

Table 3.1 below provides the details of the elements of the proposed development for which planning permission is sought.

Table 3.1 Development Proposals

Structure Length (m)

Width (m)

Area (m2)

Number Total Development

Area (m2)

Dewatering MCC Kiosk 15.0 5.0 75.0 1 75.00

Dewatering (Centrifuges) 11.0 14.0 154.0 1 154.00

Polymer Dosing Kiosk 5.0 3.0 15.0 1 15.00

Potable Water Booster Station 5.0 3.0 15.0 1 15.00

Washwater (FE) Booster 10.5 3.5 36.75 1 36.75

Sludge Storage Area MCC 17.5 5.0 87.5 1 87.50

Sludge Screens 5.5 3.0 16.5 2 33.00

SITA Office Building 22.0 8.5 187.0 1 187.00

SITA Storage Building 9.0 2.5 22.5 2 45.00

SITA Concrete Block Building 15.0 10.0 150.0 1 150.00

Site Drainage Return PS Kiosk 5.0 3.0 15.0 1 15.00

Industrial Water Pump Station Kiosk**

5.0 4.0 20.0 1 20.00

Interim Sludge Screen* 5.5 3.0 16.5 1 16.50

Interim MCC Kiosk* 15.0 5.0 75.0 1 75.00

Sludge Thickening Building 19.0 18.0 342.0 1 342.00

1227.75


Page 5

*Interim structures may be required due to STW operational and HS2 construction requirements. These will be removed as part of the demolition works required by HS2 – No net increase.

**Replacing an existing Kiosk that will be removed – No net increase

Net total area for planning structures on project completion is 1116.25m2.

4. POTENTIAL SOURCES OF FLOOD RISK

4.1. Sources of Flooding

Flooding can occur from a number of sources as shown in Table 4.1.

Table 4.1 Possible Sources of Flooding Identified in the PPG

Source Description

Flooding from rivers River flows which exceed the flow capacity of the river channel (or culverts) can cause flooding from rivers.

Flooding from the sea High tides and/or storm surges can cause flooding from the sea.

Flooding from land Intense rainfall that cannot soak into the ground or enter drainage systems can quickly run off the land and result in local flooding.

Flooding from groundwater Groundwater flooding occurs when water levels in the ground rise above surface elevations.

Flooding from sewers Sewer flooding can occur when piped systems are overwhelmed by heavy rainfall, when sewers become blocked or when sewers are of inadequate capacity.

Flooding from reservoirs, canals and other artificial sources

Non-natural or artificial sources of flooding can include reservoirs, canals and lakes where water is retained above natural ground level.


Page 6

5. FLOOD ZONES

5.1. Planning Practice Guidance Flood Zones

The PPG defines three flood zones as shown in Table 5.1.

Table 5.1 PPG Flood Zones

Flood Zone Return Period (Annual Exceedance Probability)

1 Low probability - less than 1 in 1,000 year (<0.1%) for river or sea flooding.

2 Medium probability - between 1 in 1,000 year (0.1%) and 1 in 100 year (1%) for river flooding or between 1 in 1,000 year (0.1%) and 1 in 200 year (0.5%) for sea flooding.

3a High probability - 1 in 100 year (1%) or greater for river flooding or 1 in 200 year (0.5%) or greater for sea flooding.

3b The Functional Floodplain - land where water has to flow or be stored in times of flood. There is not a strict definition of the annual probability of flooding in this zone, but the 1 in 20 year (5%) or greater return period should provide a starting point for consideration.

According to the Environment Agency’s Flood Map for Rivers and the Sea (Appendix C), the Coleshill STW lies within Flood Zone 2 (Medium Probability). The proposed development will be located within Flood Zone 2 (Medium Probability) and Flood Zone 3 (High Probability). All planning applications for development located in Flood Zones 2 and 3 need to be accompanied by an appropriate FRA.


Page 7

6. FLOOD RISKS TO THE SITE

6.1. Sources of Flooding

The Environment Agency’s Flood Maps shown in Appendices C, E and F provide a high level overview of the likely flood risk to a specific area or region, although the flood extents shown do not account for the presence of existing flood defences or the likely impacts of climate change. Each of these sources of flood risk is considered in more detail below.

6.2. Flooding from Rivers and the Sea

The Flood Map in Appendix C indicates that the most likely source of flooding to the proposed development site is fluvial from the River Tame.

To provide detailed flood levels/depths across the proposed development site the Environment Agency’s ISIS – TUFLOW (1D/2D) model of the Lower River Tame has been used as part of this FRA. In order to assess the likely impacts of climate change to the most recent standards, the model was re-run for the 1 in 20 year, 1 in 100 year, 1 in 100 year + 20% and 25%1 increases in river flows, and 1 in 1000 year return period events.

Under the 1 in 100 year + 25% climate change event the model indicates that the proposed development area would experience flooding (Appendix D). Consequently, the site of the proposed development is considered to be located within PPG Flood Zone 3a (High Probability).

Under the 1 in 20 year event the model indicates that the proposed development area would not experience flooding (Appendix G). As such, the site of the proposed development will not be located within PPG Flood Zone 3b (Functional Floodplain).

Table 6.1 below shows the maximum flood depths at each individual assets for different return period events which suggest that the areas of proposed development are at risk of flooding for 5 assets for 100 year +25% climate change event and 9 assets for 1000 year event.

Table 6.1 Modelled Flood Depths

Development Element Approximate maximum flood depths (m)

100 Year 100 Year + 20%

100 Year + 25%

1000 Year

Sludge Screen 0.00 0.22 0.32 0.70

MCC Sludge Tanks 0.00 0.22 0.28 0.49

FE Booster 0.00 0.00 0.00 0.24

Air Mixing to Tanks (Blower/compressor)

0.00 0.11 0.45 0.31

Dewatering MCC Kiosk 0.00 0.00 0.00 0.11

1 STWL standard design practice is 1 in 100 year; the site is less vulnerable and located in the northwest region of the

River Basin District for which a climate change allowance of 25% was chosen.


Page 8

Development Element Approximate maximum flood depths (m)

100 Year 100 Year + 20%

100 Year + 25%

1000 Year

Dewatering (Centrifuges) 0.00 0.00 0.00 0.09

Polymer Dosing Kiosk 0.00 0.00 0.00 0.00

Site Drainage Return PS Kiosk 0.00 0.00 0.00 0.92

Potable Water Booster Pumping Station

0.00 0.00 0.00 0.24

SITA Office Building 0.00 0.00 0.04 0.00

SITA Concrete Block Building 0.00 0.00 0.00 0.67

SITA Storage Building 0.00 0.00 0.04 0.00

Industrial Pump Station Kiosk2 0.00 0.00 0.00 0.00

Interim Sludge Screen2 0.00 0.00 0.08 0.58

Interim MCC Kiosk2 0.00 0.00 0.30 1.01

Table 6.2 below provides the approximate maximum flood level at each individual assets of the proposed development areas for the four flooding events discussed.

Table 6.2 Modelled Flood Levels

Development Element Approximate maximum flood Levels (m AOD)

100 Year 100 Year + 20%

100 Year + 25%

1000 Year

Sludge Screen N/A 73.09 73.21 73.58

MCC Sludge Tanks N/A 73.87 73.94 74.11

FE Booster N/A N/A N/A 73.25

Air Mixing to Tanks (Blower/compressor)

N/A 72.82 73.16 73.03

Dewatering MCC Kiosk N/A N/A N/A 73.80

Dewatering (Centrifuges) N/A N/A N/A 72.93

Polymer Dosing Kiosk N/A N/A N/A N/A

2 Located outside the proposed development area


Page 9

Development Element Approximate maximum flood Levels (m AOD)

100 Year 100 Year + 20%

100 Year + 25%

1000 Year

Site Drainage Return PS Kiosk N/A N/A N/A 74.37

Potable Water Booster Pumping Station

N/A N/A N/A 73.20

SITA Office Building N/A N/A 73.02 N/A

SITA Concrete Block Building N/A N/A N/A 73.76

SITA Storage Building N/A N/A 73.03 N/A

Industrial Pump Station Kiosk N/A N/A N/A N/A

Interim Sludge Screen N/A N/A 73.70 74.37

Interim MCC Kiosk N/A N/A 73.70 74.41

6.3. Flooding from Land

The Environment Agency Flood Map for Surface Water (Appendix E) confirms that the site is not at significant risk from this source. Accordingly, this source of flood risk is not considered further.

6.4. Flooding from Groundwater

There is no historical record of flooding of the site by groundwater. This is not expected to change as a result of the proposed development. Accordingly, this source of flood risk is not considered further.

6.5. Flooding from Sewers

There is no historical record of flooding of the site by overwhelmed sewers. This is not expected to change as a result of the proposed development. Accordingly, this source of flood risk is not considered further.

6.6. Flooding from Reservoirs, Canals and Other Artificial Sources

There is no historical record of flooding at the proposed site by reservoirs, canals or other artificial sources.

The Environment Agency flood map for Reservoirs (Appendix F) indicates no flood risk to the proposed development site from this source. Accordingly, this source of flood is not considered further.


Page 10

7. PLANNING PRACTICE GUIDANCE

7.1. Proposed Land Use Classification

The proposed development is classified as ‘Less Vulnerable’ land use, which is defined under the PPG as “…sewage treatment works, if adequate measures to control pollution and manage sewage during flooding events are in place’. According to the PPG, this would mean that the proposed development is considered appropriate for location within Flood Zones 2 and 3.

The Environment Agency’s ISIS-TUFLOW model results for the 1 in 20 year flood event (Appendix G) show that the area of proposed development lies outside the Functional Floodplain (i.e. Flood Zone 3b).

7.2. PPG Requirements

Given the scale and nature of the proposed development, the key considerations of this FRA are to ensure that the new equipment will:

• Remain operational in times of flooding;

• Result in no net loss of floodplain storage;

• Not impede flood water flows; and

• Not increase the volume and rate of surface water runoff leaving the site.

In addition, the PPG states that ‘minor developments’ are unlikely to raise significant flood risk issues unless:

• They would have an adverse effect on a watercourse, floodplain or its flood defences;

• They would impede access to flood defence and management facilities; or

• The cumulative impact of such developments would have a significant effect on local flood storage capacity or flood flows.

7.3. Sequential Test

The Sequential Test aims to steer new development to areas that have the lowest probability of flooding. Given that the proposed development would be located within the existing site boundary, the PPG suggests a pragmatic approach to the Sequential Test in such circumstances: “in considering planning applications for extensions to existing business premises it might be impractical to suggest that there are more suitable alternative locations for that development elsewhere.” As such, the

requirement to pass the Sequential Test is not considered further.


Page 11

8. FLOOD RISK CONSIDERATIONS

8.1 Key Considerations

As described in Section 7.2, to meet (or exceed) the PPG requirements, ‘Less Vulnerable’ land use such as that proposed at the Coleshill STW will be considered suitable for location within PPG Flood Zones 2 and 3 provided it:

• Remains operational in times of flood over the duration of its intended lifetime taking climate change into account;

• Results in no net loss of floodplain storage;

• Does not impede flood water flows; and

• Does not increase the volume and rate of surface water runoff leaving the site.

In addition, the PPG states that ‘minor developments’ are unlikely to raise significant flood risk issues unless:

• They would have an adverse effect on a watercourse, floodplain or its flood defences;

• They would impede access to flood defence and management facilities; or

• The cumulative impact of such developments would have a significant effect on local flood storage capacity or flood flows.

Each of these requirements is discussed in relation to the proposed development in Sections 8.2 to 8.7 below.

8.2 Remain Operational in Times of Flood

The fluvial modelling results suggest that 5 of the 15 individual assets of the proposed development lie within the 1 in 100 year plus 25% allowance for climate change flood outline. Therefore these at-risk assets will be constructed on concrete plinths that will be raised above the peak flood level at each location.

8.3 No Net Loss of Floodplain Storage

The existing SDP structures, that are being replaced, will be demolished which will release additional flood storage capacity of ca. 564 m3 (see Table 8.1 below).

To achieve access to the assets above the flood levels, the area of the proposed development will be raised. This results in a storage volume loss of 2,330m3.

Therefore, the proposed development will incur a net loss of floodplain storage capacity of ca. 1770 m3 which will be compensated through removing some of the existing sludge in the beds adjacent to the River Tame as shown on the issued drawing A6S-12892-PA-26007.


Page 12

Table 8.1 Structures to be demolished

Structures to be Demolished

Length (m)

Width (m)

Structure Area (m2)

Number Total Area (m2)

Existing Ground Level (mAD)

1 in 100 + 25% CC

Depth (m)

Volume in Flood

Area (m3)

Screenhouse (Building)

13.0 10.0 130.00 0 0 73.5 0.25 0.0

Sludge Holding Tanks

155.00 4 620 73.5 0.25 155.0

Primary Sludge Pump Station (Building)

13.2 10.0 132.00 1 132 73.5 0.25 33.0

Sludge Blending Tanks

327.00 4 1308 73.5 0.25 327.0

Blending Tank Mixing Kiosk

5.0 4.5 22.50 1 22.5 73.5 0.25 5.6

Secondary Sludge Pump Station (Building)

8.2 7.5 61.50 1 61.5 73.5 0.25 15.3

Filtrate Pumphouse (Building)

15.0 7.4 111.00 1 111.0 73.5 0.25 27.7

563.6

8.4 No Impediment to Flood Water Flows

The raised area will be graded to allow flood water flow movement. The existing SDP structures will be demolished which will release additional flood conveyance capacity (see Table 8.1 above).

8.5 Surface Water Runoff

There are no existing surface water discharges from the sludge bed area to the watercourse. No new discharges are proposed as part of this development.

There would be an increase in impermeable area of ca. 970 m2 associated with the development (Table 3.1) as the proposed area is currently undeveloped and grass covered. Without mitigation, this increased impermeable area would generate an increase in the volume and rate of surface water runoff generated on the site when compared to the existing site layout.

The proposed development would utilise the existing sludge bed liquor drainage system currently present beneath the sludge bed area. Rainfall percolating through the sludge beds was historically pumped to the head of works at Coleshill STW. It is proposed that this system remains in place to collect and treat surface water runoff from the relocated assets in a similar manner.

Surface run-off where contamination is possible and wash down areas will be collected in a dedicated system discharging to the existing SDP Site Drainage Return pump station that returns to the head of works at Coleshill STW.

In addition, dedicated process specific return pump stations are proposed to replicate the existing treatment route through Coleshill STW. The SITA return pump station will be constructed that takes both process and surface water runoff from the SITA Grit Processing Facility to the head of the STW for treatment.

The rationale behind this approach is that all surface water runoff from the relocated assets will need to be considered as foul and returned to the head of the STW for treatment. As such, the required attenuation and storage of the additional runoff will be provided within the treatment stream of the STW itself. This measure will ensure that the proposed development would not result in an increase in surface water flood risk.


Page 13

Greenfield Runoff Estimation

Using the IH124 method, QBAR was estimated for a 50 hectare site then factored down to the 970m2 (0.097ha) area of the proposed development. These calculations are included below:

• QBAR @ 50 ha = 20.2 l/s

• QBAR @ 0.097 ha = 0.039 l/s

As per current guidance, the minimum outfall rate for any new development is 5 l/s. As such, the attenuation storage volume has been estimated based on a permissible discharge rate of 5 l/s.

Attenuation Storage Estimation

The “Quick Storage Estimation” function in WinDes was used to estimate the attenuation storage requirement.

With the permissible discharge rate limited to 5 l/s, the attenuation storage requirement for the proposed development has been estimated for the 100 year + 25% climate change event, as follows:

• FSR rainfall method - 37 m3

• FEH rainfall method - 44 m3

STWL has confirmed that at least 44 m3 of spare capacity is already available within the Coleshill STW and that this spare volume will be preserved for the purposes of providing the required attenuation storage for the relocated development over its intended lifetime, taking climate change into account.

8.6 Risks to People

STWL has confirmed that the proposed development would not require additional staff to be present on site on a regular basis. In fact, the proposed development would mean that the assets would become more automated and would require less manual operational input, especially during times of flooding. As such, there would be no increased risk to people on site as a result of the proposed development.

8.7 Access to flood defence and management facilities

The proposed development will be located ca. 100m from the northern bank of the River Tame. Access to any Environment Agency-maintained flood defences would not be compromised as a result.


Page 14

9. CONCLUSIONS

This FRA has used the latest Environment Agency information and hydraulic modelling to quantify flood risk to the proposed development at the Coleshill STW site. The flood level data have been used to inform the design of the proposed development associated with this planning application to ensure that it will remain operational during times of flooding over the duration of its intended lifetime, whilst taking climate change into consideration.

The proposed development is at risk of fluvial flooding from the River Tame under the 1 in 100 year + 25% climate change event. The peak on site flood level associated with this event is 73.94 m AOD. The proposed relocated assets that would be at risk under this event will be raised on concrete plinths that would also permit the storage and conveyance of floodwater beneath each asset.

The proposed land use type is considered suitable for location within Flood Zones 2 and 3 (Medium and High Probability respectively) and the development proposals will not increase the number of people working in or visiting a flood risk area.

The conclusions of this FRA are, therefore, that the proposed development:

• Is appropriate for its location from a flood risk perspective;

• Will remain operational in times of flooding;

• Will not represent an increase in risk to people;

• Will not increase flood risk elsewhere; and

• Will not restrict access to flood defence and management facilities.


THIS PAGE IS INTENTIONALLY BLANK.


APPENDIX A

Existing Site Layout and Areas of Proposed Development




APPENDIX B

Site Topographical Survey




APPENDIX C

Environment Agency Flood Map –

Rivers and Sea




APPENDIX D

Detailed Fluvial Flood Risk Mapping – 1 in 100 year plus 25%




APPENDIX E

Environment Agency Flood Map - Surface Water




APPENDIX F

Environment Agency Flood Map -Reservoirs




APPENDIX G

Detailed Fluvial Flood Risk Mapping – 1 in 20 year



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