Flood Risk Assessment October 2011 Document …galloperwindfarm.com/assets/images/documents/Reports/Flood_Risk...Flood Risk Assessment . October 2011 . Document Reference ... 4.2.3

Galloper Wind Farm Project

Flood Risk Assessment

October 2011

Document Reference – 6.5

Galloper Wind Farm Limited

A COMPANY OF

HASKONING UK LTD. WATER

Rightwell House

Bretton

Peterborough PE3 8DW United Kingdom

+44 1733 334455 Telephone Fax

[email protected] E-mail www.royalhaskoning.com Internet

Document title Galloper Wind Farm Flood Risk Assessment

Document short title Status Final Report

Date 18 October 2011 Project name Galloper Wind Farm FRA

Project number 9V5811 Client Galloper Wind Farm Ltd

Reference 9V5811/R2/303427/PBor

Drafted by Ayyappa Gudimetla/Aminul Chowdhury

Checked by Andrew Robinson

Date/initials check AR…………………. 18.10.2011………………….

Approved by Andrew Robinson

Date/initials approval AR…………………. 18.10.2011………………….

CONTENTS Page

1 INTRODUCTION 1

2 DEVELOPMENT DESCRIPTION AND LOCATION 1 2.1 Development Description 1 2.2 Site Location 2

3 ASSESSMENT OF FLOOD RISK 2 3.1 Introduction 2 3.2 Environment Agency Flood Map 2 3.3 Strategic Flood Risk Assessment 3 3.4 Review of Terrain data 4

4 IMPACT ON LOCAL FLOODING REGIME 4 4.1 General 4 4.2 Surface Water Runoff 4 4.3 Access and Egress 5

5 CONCLUSIONS AND RECOMMENDATIONS 5 Appendix A: Figures Appendix B: Drainage Strategy (Peter Brett Associates)

9V5811/R2/303427/PBor Final Report - i - 18 October 2011

Error! Reference source not found. 9V5811/R2/303427/PBor Final Report - 1 - 18 October 2011

1 INTRODUCTION

1.1.1 This Flood Risk Assessment (FRA) addresses flood risk with respect to onshore aspects of the proposed Gallope Wind Farm (GWF).

1.1.2 This FRA is the outcome of a Level 1 Study in terms of the guidance given in the PPS25 Practice Guide Companion. This study will aim to

• Identify the potential sources of flooding to the site; • Consider the potential impacts of the development proposals

upon the local flood regime; and • Outline strategies to manage the flood risk to the site and local

area allowing for future climate change.

2 DEVELOPMENT DESCRIPTION AND LOCATION

2.1 Development Description

2.1.1 Galloper Wind Farm Limited (GWFL) are proposing to develop a new offshore wind farm. As part of this project there is a requirement for onshore infrastructure to allow electricity generated to be connected to the national grid. As such, a new onshore substation is required in the Sizewell area and is the element of the onshore development that is the subject of this Flood Risk Assessment (FRA). The other features of the development are not considered relevant to the FRA or are of a minor nature, such as underground cabling and cable access covers.

2.1.2 Construction is programmed to commence in 2013 at the earliest and last for approximately 38 months. GWF will be operational for a period of 25 years, with the ability to repower at the ends of its life, subject to any approvals. Whilst not the subject of the DCO application, in acknowledgement of the potential for repowering and the importance of considering long term climate change, this FRA conservatively assumes that repowering is undertaken. The assessment therefore assumed that the wind farm would be operational for a period up to approximately 2063.

2.1.3 National Policy Statements (NPS) provide the primary basis on which the Infrastructure Planning Commission (IPC) is required to make its decisions. Paragraph 5.7.4 of EN-1 states that: “Applications for energy projects of 1 hectare or greater in Flood Zone 1 in England or Zone A in Wales

and all proposals for energy projects located in Flood Zones 2

and 3 should be accompanied by a flood risk assessment (FRA).” Paragraph 5.7.6 also states that: “Further guidance can be found in the Practice Guide which accompanies Planning Policy Statement 25 (PPS25)”.


2.1.4 In terms of flood risk and vulnerability, the proposed onshore substation can be classified as ‘essential infrastructure’ as per Table D.2 of Planning Policy Statement 25 (PPS 25): Development and Flood Risk (December 2006). This type of development is appropriate if it falls into flood risk vulnerability classification of ‘Zone 1’ or ‘Zone 2’ but requires to pass exception test if it falls into ‘Zone 3a’ and ‘Zone 3b’ according to Table D.3 of PPS25 (December 2006).

2.2 Site Location

2.2.1 Figure 1 shows the proposed location for the onshore substation. The development site is approximately 3.1 hectares in size. The site is approximately 1km inland from the Suffolk coast, in a roughly westerly direction from Sizewell.

3 ASSESSMENT OF FLOOD RISK

3.1 Introduction

3.1.1 An assessment of flood risk was made by considering information from various sources such as the Environment Agency’s flood zone map and the Strategic Flood Risk Assessment (SFRA) for the Suffolk region. Using terrain data1 it has been possible to assess the likelihood of flooding at the development site. This section also considers the likely impact of the development on flood risk and the safety of people during a flood event.

3.2 Environment Agency Flood Map

3.2.1 The site is not at risk of flooding from rivers or the sea according to the Environment Agency’s Flood Zone map. A copy of the Environment Agency (EA) flood map is shown in Figure 2, which shows Zones 2 and 3. This identifies the site as falling in Zone 1 defined in Table D.1 of PPS25 as Low probability of flooding (land assessed as having a less than a 0.1% annual probability of river or sea flooding in any year). As per Table D.3 of PPS25 when the site proposed is in Zone 1 and is essential infrastructure, the development is appropriate and is not subjected to the Sequential or Exception Tests.

1 Interferometric Synthetic Aperture Radar (IFSAR) has been obtained to study the terrain of the site and its surroundings


3.3 Strategic Flood Risk Assessment

3.3.1 Suffolk Coastal and Waveney District Councils produced a Strategic Flood Risk Assessment (SFRA) in January 2009 in line with PPS25. Sizewell is one of the key settlements where growth is focussed.

3.3.2 Although there are several watercourses such as the River Alde and River Blyth in Suffolk and Waveney District regions, there are no major watercourses near the GWF development area. Therefore it is very unlikely that this site will flood from fluvial sources.

3.3.3 Flooding to low-lying land from the sea and tidal estuaries is caused by storm surges and high tides. This is the most likely source of flooding in Sizewell. The tidal defences near Sizewell vary in height. Using IFSAR data a long profile was obtained along the coast to assess the approximate height of defences. The elevations range from 8m AOD near the power station, 4.5m AOD near Sizewell to 12m AOD near Sizewell Hall in the south. This is illustrated in Figure 3.

3.3.4 The SFRA included extreme tide levels at Sizewell as well as predicted levels with climate change to 2107. The water levels for various annual probabilities are reproduced in Table 1.

Table 1: Maximum Sea Water Levels Extracted From SFRA Report (CC=Climate Change)

5% AEP 5% AEP CC 0.5% AEP 0.5% AEP CC 0.1% AEP 0.1% AEP CC 2.72 3.74 3.24 4.26 3.61 4.63

3.3.5 For the proposed GWF development, construction is planned to

commence in 2013 and even including a conservative assumption of repowering, would lie within the time period to 2107. Therefore the climate change allowance should be to 2045, which equates approximately to 3.92 m AOD for the 0.1% Annual probability.

3.3.6 According to the SFRA there are no records of significant groundwater flooding. The proposed finished floor level is on relatively high ground (8m AOD – 9m AOD), and previous geotechnical investigations suggest that groundwater is present at approximately 1.5m AOD. As such, it is unlikely that groundwater represents a significant issue with regard to potential flood risk.


3.4 Review of Terrain data

Introduction 3.4.1 Interferometric Synthetic Aperture Radar (IFSAR) has been obtained to

study the terrain of the site and its surroundings. IFSAR is also known as RADAR. It has a resolution of 5m and an accuracy of +/- 1m vertically. Figure 3 shows the terrain represented by IFSAR. In addition a topographic survey of the site has been undertaken to confirm actual ground levels.

The development site 3.4.2 Figure 4 and 5 shows the varying ground levels at the development site.

The existing ground levels vary between approximately 9m AOD and 12m AOD. The finished floor level of the development is expected to vary between 8m AOD and 9mAOD.

3.4.3 The lowest point of the development is the access to the GWF site at Sizewell Gap and is approximately 7.9m AOD.

3.4.4 It can therefore be concluded that the development and access sits above the areas likely to flood even if the coastal defences are over topped and breached during a 0.1% AEP with climate change in 2107 (4.63m AOD).

4 IMPACT ON LOCAL FLOODING REGIME

4.1 General

4.1.1 Currently the site is greenfield and undeveloped. The substation comprises two compounds ( the Galloper Wind Farm compound and the transmission compound), sealing end compounds, underground cabling, a 5m wide access roads and a new landform which is designed to minimise the visual and acoustic impact of the proposed development on the surrounding area ( see Drawing GWF_348_R22 in Appendix 1:Figures). The site is currently not served by any formal surface water or foul drainage system.

4.2 Surface Water Runoff

4.2.1 The GWF substation comprises two permanent above ground installations: the GWF compound will be located on predominantly arable land (although also lying partly on acid grassland); and the transmission compound which will be located in an area that is currently woodland.


4.2.2 The Greenfield runoff generated by this land currently drains naturally towards the north. However, due to the proposed development, additional surface runoff will be generated from new impermeable surfaces which, as per PPS25, need to be managed efficiently to ensure that the site maintains the existing Greenfield runoff rate.

4.2.3 A Greenfield runoff calculation has been undertaken for the development. The estimated runoff volume for both compounds described above is estimated to be 554.3m3 in the 1 in 100 year with climate change scenario. Details are provided within Appendix B.

4.2.4 Appendix B comprises the Surface Water Drainage Strategy for the proposed site (Peter Brett Associates LLP) and details of the estimated runoff volume. The strategy mimics the existing drainage regime and discharges all surface water runoff generated by the development to ground via infiltrating SUDS. The strategy includes the use of dry swales along the access road, filter drains along the inside toe of the earthwork bund and soakaways within the substation.

4.3 Access and Egress

4.3.1 Given that the proposal comprises new development, consideration for human safety should be paramount.

4.3.2 Although the site is well above the peak 0.1% AEP water levels with climate change and is in Flood Zone 1, there are low lying areas which may flood during an extreme event, such as the areas further east towards Sizewell.

4.3.3 Access and egress routes are above likely flood levels and therefore access to the site can be provided via Sizewell Gap.

4.3.4 The Environment Agency currently operates flood warning schemes via their website or through the flood line on the Suffolk coast. Registering for their services can give alerts to possible flooding.

5 CONCLUSIONS AND RECOMMENDATIONS

5.1.1 This report has examined flood risk at a site proposed for the GWF onshore substation and other equipment. The Environment Agency’s Flood Map shows that the site falls within Flood Zone 1 defined in Table D.1 of PPS25 as the zone of low probability of flooding. Essential infrastructure development such as the proposed substation is acceptable in this flood risk vulnerability classification (Flood Zone 1) where Sequential or Exception Tests are not required.


5.1.2 Terrain data clearly indicates that the site lies on high ground. The lowest ground level at the substation site is 8m AOD. The assessment has demonstrated that in the current and future climate change scenarios, the site is well above the 0.1% AEP extreme tide level. This means the site would not be affected by breaches in the coastal flood defence.

5.1.3 The proposed development will produce surface water runoff that can be managed through SUDS. A surface water drainage strategy has been developed for the site which will form the basis of detailed design submissions to the EA and relevant drainage authorities post consent. This will eliminate the risk of increased flooding from surface water runoff and ensure the site maintains the present day Greenfield runoff rate. Discussions with Suffolk Coastal District Council and Suffolk County Council should be undertaken regarding the long term adoption and maintenance of any new surface water features.

5.1.4 Access and egress routes are above likely flood levels and therefore safe and dry access to the site is possible via Sizewell Gap.

A COMPANY OF

Appendix A: Figures

Figure:

Date: Scale:

Title:

Client:

Project:

1

Site Location Plan

Galloper Wind Farm - Flood Risk Assessment

Galloper Wind Farm Ltd

September 2011

Key:

Source:© Crown copyright, All rights reserved. 2010 Licence number 0100031673© The Automobile Association

I:\9V5

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1:7,000 @ A4

Colchester

IpswichFelixstoweHarwich

SaxmundhamAldeburgh

Wrentham

Site Location

0 300150 Metres

Figure:

Date: Scale:

Title:

Client:

Project:

2

EA Flood Zones



September 2011

Key:

Source:© Crown copyright, All rights reserved. 2010 Licence number 0100031673

I:\9V5

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Site LocationEA Flood Zone 3EA Flood Zone 2

0 300150 Metres

12

6.94

6.56

5.725.08

4.584.63

5.056.64

7.92

8.82

9.71

9.71

9.38

9.418.56

8.12

8.22

8.73

8.61

9.94

10.12

10.53

10.29

10.34Figure:

Date: Scale:

Title:

Client:

Project:

3Defence Levels Along Frontage

Galloper Wind Farm- Flood Risk Assessment


September 2011 1:9,000 @ A4

Key:

I:\9 V58 11 \Tech nica l_ Data \GIS \Proje cts

SAR(mAOD)

-0.1 - 00.01 - 11.01 - 22.012.01 - 33.01 - 44.01 - 55.01 - 66.01 - 7

7.01 - 88.01 - 99.01 - 1010.01 - 1111.01 - 1212.01 - 1313.01 - 1414.01 - 1515.01 - 1616.01 - 1717.01 - 1818.01 - 19


Defence Points and Levels mODSite Location

8

9

10

8.5

9.5

8.25

8.75

9.25 9.75

77.75

11

7.5

10.5

10.25

10.75

7.25

11.5

11.25

11.75

9.5

11

9.75

9.75

10.25

9.59.25

10.75

11.25

Figure:

Date: Scale:

Title:

Client:

Project:

4

SAR Contours



September 2011

Key:


I:\9V5

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1:1,500 @ A4

SAR Contours (mAOD)66.256.56.7577.257.57.7588.258.58.7599.25

9.59.751010.2510.510.751111.2511.511.751212.2512.512.75

Site Location

Figure:

Date: Scale:

Title:

Client:

Project:

5

Topography



September 2011

Key:


I:\9V5

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Site Location

0 300150 Metres

SARmAOD

-0.1 - 00.01 - 11.01 - 22.012.01 - 33.01 - 44.01 - 55.01 - 66.01 - 77.01 - 8

8.01 - 99.01 - 1010.01 - 1111.01 - 1212.01 - 1313.01 - 1414.01 - 1515.01 - 1616.01 - 1717.01 - 1818.01 - 19

Rev: 32Date: 13/10/11 Created: LW Checked: CMDatum: OSGB36 Projection:British National Grid

UK Offshore DevelopmentFigure 1

Galloper Wind Farm Onshore General Arrangement Drawing Number: GWF_348_R32Scale: Page: A3

TransitionBays

Mean

Low

WaterMe

an H

igh W

ater

Cliff/S

lope B

ottom

Vege

tation

/Land

form

Limit

0 100 200 30050 Metres

±

Greater Gabbard Offshore Wind Farm existing infrastructureGreater Gabbard substationCar Park and Access Road

Galloper Wind Farm Proposed InfrastructureSubstationGWF Export Cable CorridorTemporary Construction Area (Drilling & Transition Bays)Estimated Extent of DrillingEstimated Extent of Optional DrillingOther Electricity Cables & Utility CorridorsMaximum Extent of Transition BaysLandfall Cable Working AreaSealing End Compound BoundaryDNO Area (including Transformer)Anchor AreaSealing End Compound, Gantry, Connection & Pylon WorksAccess RoadTemporary Access RoadArea within which Temporary Beach Access(es) must lieTemporary Construction Area (Sealing End Compound)Temporary Construction Area (Substation)Grassed Areas (Including any Earthworks)Existing Woodland AreasProposed Woodland/Woodland Edge Planting (Including any Earthworks)Potential Additional Landscape Area/ EarthworksLand Returned to Pasture (After Earthworks)Land Returned to Arable (After Earthworks)Improvement for Long Term Reptile Habitat (if necessary)Access Route for Landscape Mitigation Works

Layout Information: Where the cables are laid by surface excavation, the permanent easement will be 23m with a total construction working width of 38m as shown on the plan. The permanent GWF cable corridor will have the ability to be located anywhere withinthe 38m corridor shown. Where the cables are installed through Horizontal Directional Drilling (HDD), the permanent easement for the HDD ducts and cables will be 33m, with the ability to locate the permanent easement anywhere within the 38m corridor shown.The "Other Cable Corridors" vary in width within the corridors shown on this plan. Access routes along the beach will be established within the area shown. An access route to the cable working area will be located on the beach foreshore and will be delineatedwith temporary matting to a maximum width of 4m. An additional access route to the landfall cable working areas is located along the shingle beach. A DNO transformer will be located within the area shown and will be an approximate size of 3m x 3m x 3m.Ordnance Survey © Crown Copyright 2011. All rights reserved. License number 100020449. This map is for discussion purposes only. Orientation, dimension and location of Galloper Wind Farm infrastructure is indicative only and does not represent finallocations. All locations are subject to detailed design. The concepts and information contained in this document are the copyright of SSE Renewables (UK) Ltd and RWE Npower Renewables Limited. Use or copying of the document in whole or in part without thewritten permission of SSE Renewables (UK) Ltd and RWE Npower Renewables Limited constitutes an infringement of copyright. SSE Renewables (UK) and RWE Npower Renewables Limited does not warrant that this document is definitive nor free of error anddoes not accept liability for any loss caused or arising from reliance upon information provided herein. Not to be used for navigation purposes.

Exact location of beach access routes within this area are subject to subsequent

approval with SCDC

Potential Additional Landscape Area/ Earthworks (Subject to Commercial Agreement)

Temporary Construction Area (Sealing End Compound, Gantry & Pylon Works)

1:5,000

Relocated GGOWF Communications Pole and Cable

Appendix B: Drainage Strategy (Peter Brett Associates)

J:\25456 Galloper Wind Farm\003 - Earthworks and Drainage\WP\TN001 - Proposed Drainage Strategy Rev C.doc Page 1 of 3

Job Name: Galloper Wind Farm

Job No.: 25456/003

Note No.: TN001C

Date: 11th October 2011

Subject: Drainage Strategy

Prepared By: C. Brown

Introduction This technical note details the surface water and foul drainage strategies for the Galloper Wind Farm Substation site. The proposed development consists of four compounds (the Galloper Wind Farm Substation, a transmission compound and two Sealing End compounds), underground cabling, a 6m wide access road and an earthwork landform which is designed to minimise the visual and acoustic impact of the proposed development on the surrounding area. The greenfield site, which is located approximately 0.60km to the west of the village of Sizewell, Suffolk, next to a similar substation development (the Greater Gabbard Offshore Wind Farm substation), is currently not served by any formal surface water or foul drainage networks. Surface Water Strategy The surface water drainage strategy for the development will mimic the existing drainage regime and discharge all the surface water runoff generated by the development to ground via infiltrating Sustainable Drainage Systems (SuDS). Infiltration tests carried out for the neighbouring Great Gabbard Offshore Wind Farm substation site in accordance with BRE Digest 365 by Geotechnical Engineering Ltd have confirmed that ground conditions across the site are suitable for such techniques with the poorest calculated infiltration rate (1x10-5m/s) proposed for use within the design. The finished ground levels for the site will lie no lower than 8.0m AOD while previous geotechnical reports suggest that groundwater is present at approximately 1.5m AOD. Therefore, maintenance of a 1m unsaturated zone between the bottom of any infiltration devices and the water table can be readily achieved. Refer to Geotechnical Engineering Ltd. correspondence dated 14th May 2008 a copy of which is contained in Appendix A. Based on the information provided by Geotechnical Engineering Ltd. a surface water drainage strategy has been developed that includes the use of dry swales along the access road, filter drains along the inside toe of the earthwork landform and soakaways within the substation compounds. Dry swales consist of a vegetated conveyance channel, designed to include a filter bed of prepared soil that overlays an infiltration trench. The trench provides additional treatment and storage capacity ensuring that the swale does not become boggy during periods of wet weather. Dry swales have been proposed for use alongside the extension to the access road

Peter Brett Associates LLP

Caversham Bridge House

Waterman Place, Reading

Berkshire RG1 8DN

T: +44 (0)118 950 0761

F: +44 (0)118 959 7498

E: [email protected]

Website: www.peterbrett.com


to the substation compounds as they are effective at removing hydrocarbons from runoff and providing storage during larger rainfall events. Filter drains consist of an infiltration trench which incorporates a perforated pipe within its base. The pipe provides additional storage and conveyance if required. They have been proposed for the internal toe of the landform that will surround the compound as they are effective at accepting overland sheet flow and treating runoff by vegetative filtering and promoting the settlement of particulate pollutants. The main compound areas will be drained via piped networks and trapped gullies which collect the surface water runoff generated by the development’s hard standing areas and discharge it to ground via cellular soakaways. In accordance with best practice all surface water runoff generated from hard standing areas within the main compounds other than roofs will pass through a class 1 bypass separator before being discharged to ground to remove any hydrocarbon pollutants present in the runoff. While the internal layout of the substation compounds are still to be finalised, similar developments, such as the existing neighbouring Greater Gabbard Offshore Wind Farm substation, have a level of impermeability of approximately 35-45%. These impermeable areas include the concrete maintenance road which provides access to the bunded transformer plinths and the control building. The remainder of the site (approximately 55-65%) will be made up of a gravel layer approximately 0.1m deep. In accordance with the requirements of Part 2 and Section 4.8 of the National Policy Statement for Energy (EN-1) a 20% allowance for climate change has been calculated based on the predicted life expectancy of the development and the latest UK Climate Projections as defined by Planning Policy Statement 25: Development and Flood Risk (PPS25). Indicative sizing of the proposed infiltration devices for the 1 in 100yr + 20% climate change allowance rainfall event has been undertaken in MicroDrainage using the calculated infiltration rate of 1x10-5m/s. In order to demonstrate that the proposed infiltration techniques can be incorporated into the proposed development layout the indicative size and location of the infiltration devices are shown on the concept drawing 25456/003/050 contained in Appendix B, with the accompanying calculations contained in Appendix C. The two Sealing End compounds, which contain no sources of pollution and will have a predominantly gravel finish, will discharge any surface water run-off generated into the gravel prior to infiltration into the ground. The final surface water drainage scheme will be subject to detailed design of the compound layouts post-consent, however there will be a legal requirement for approval of the drainage scheme by the local planning authority in conjunction with the Environment Agency. The routing of overland flow in an extreme rainfall event has also been considered in developing this surface water drainage strategy. Based on the existing drainage catchment and fall of the land surrounding the compound any overland flow generated in an extreme rainfall event will flow from south to north across the site. The proposed levels and layout of the compounds will preserve this overland flood route to the north in extreme rainfall events. However, any runoff exceeding the capacity of the drainage system would initially be stored within the voids of the gravel base, which covers the majority of the site, prior to infiltration into the ground. If the gravel layer were to become saturated, surface water would be discharged off-site to the north, through the transmission compound and into an existing woodland belt. This capture of any runoff from the substation compounds will prevent any


potential contaminants from the leaving the site and minimises the risk of them entering the Sizewell Marshes SSSI which is located approximately 100m to the north of the site. Foul Water Strategy The foul drainage system will collect all foul water generated by the development in a piped network and convey the flow towards a cesspit which will be emptied as and when required. The cesspit will be fitted with a high level alarm to alert maintenance staff when the pit requires emptying. The cesspit will attenuate all the foul water generated by the development ensuring that effluent cannot enter the ground or groundwater. Annual emptying and cleaning of the cesspit as well as regular visual inspections will be required along with servicing of the high level alarm to ensure that the cesspit continues to operate as designed. The oil filled transformers will be sited on bunded plinths, with either underground oil containment integral with the foundations or a remote oil containment tank and linking pipe work, in case of leakage or full oil discharge in emergencies. These will be drained by a pumped system which under normal operating conditions will either discharge rainfall run-off to the foul water cesspit or via a class 1 full retention separator into the surface water system, subject to detailed design and the views of the Environment Agency. Should a full discharge of the transformer oil be undertaken then sensors on the pumping apparatus will detect the presence of oil and prevent the pump from operating. The oil would then be drained down by pumping into a mobile tanker and taken off-site for disposal.

J:\25456 Galloper Wind Farm\003 - Earthworks and Drainage\WP\TN001 - Proposed Drainage Strategy Rev C.doc


Appendix A

- Geotechnical Engineering Ltd. correspondence dated 14th May 2008



Appendix B

- Galloper Wind Farm Onshore Substation Works Illustrative Surface Water Concept Layout, 25456/002/050 Rev B


Substation Platform Level 9.00m A.O.D.Excavation Base Level 8.50m A.O.D.

Northern Earthwork Bund Level 15.00m A.O.D.South & Western Earthwork Bund Level 16.50m A.O.D.

30 x 5 x 1.2m

20 x 6 x 1.2m

38 x 6 x 1.2m

NOTES:

1. Do not scale this drawing.

2. All dimensions are in metres unless stated otherwise.

3. To be read in conjunction with PBA Technical Note TN001 'Proposed Drainage Strategy.'

4. All earthworks associated with the access road are offset 2m from the edge of the carriageway to allow spacefor infiltration swales adjacent to the road and at a gradient of 1 in 3.

KEY:

Proposed boundary fence

Checked by

Drawing Issue Status

Date of 1st Issue

Drawing Number

Drawn by

Revision

DrawnMark Revision ChkdDate

File Location: j:\25456 galloper wind farm\003 - earthworks and drainage\cad\dwgs\25456_003_050.dwg

UTILITIES NOTE: The position of any existing public or private sewers, utility services, plant or apparatus shown on this

drawing is believed to be correct, but no warranty to this is expressed or implied. Other such plant or apparatus may also

be present but not shown. The Contractor is therefore advised to undertake his own investigation where the presence of

any existing sewers, services, plant or apparatus may affect his operations.

SCALING NOTE: Do not scale from this drawing. If in doubt, ask.

user name: michael pigden

Offices throughout the UK,continental Europe, Africa and Asia

© Peter Brett Associates LLPwww.peterbrett.com

READINGTel: 0118 950 0761 Fax: 0118 959 7498

GALLOPER WIND FARM

ONSHORE SUBSTATION WORKS

PRELIMINARY SURFACE WATER

CONCEPT LAYOUT

Client

F O R I N F O R M A T I O N

25456/003/050

15.08.2011

1:1000

RGM

CMB

A1 Scale

Cellular Storage

Filter Drain

Dry Swale

Overland Flow Routing


Appendix C

-MicroDrainage Galloper Substation Cellular Soakaway Serving One Third of Drained Area - MicroDrainage Galloper Substation Cellular Soakaway Serving Two Thirds of Drained Area - MicroDrainage Calculations National Grid Substation Cellular Soakaway - MicroDrainage Calculations Sample Dry Swale - MicroDrainage Calculations Sample Filter Drain


Peter Brett Associates LLP Page 1

Caversham Bridge House Galloper Wind Farm

Waterman Place Cellular Soakway

Reading RG1 8DN One third of area

Date 15.08.2011 Designed by CMB

File 3no cellular soakaway.srcx Checked by

Micro Drainage Source Control W.12.6

Summary of Results for 100 year Return Period (+20%)

©1982-2011 Micro Drainage Ltd

Half Drain Time : 1360 minutes.

Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

15 min Summer 0.428 0.428 0.7 48.7 O K

30 min Summer 0.559 0.559 0.7 63.7 O K

60 min Summer 0.694 0.694 0.8 79.1 O K

120 min Summer 0.827 0.827 0.8 94.2 O K

180 min Summer 0.898 0.898 0.8 102.4 O K

240 min Summer 0.944 0.944 0.8 107.6 O K

360 min Summer 0.994 0.994 0.9 113.3 O K

480 min Summer 1.018 1.018 0.9 116.1 O K

600 min Summer 1.031 1.031 0.9 117.5 O K

720 min Summer 1.035 1.035 0.9 118.0 O K

960 min Summer 1.026 1.026 0.9 117.0 O K

1440 min Summer 0.990 0.990 0.9 112.8 O K

2160 min Summer 0.934 0.934 0.8 106.5 O K

2880 min Summer 0.884 0.884 0.8 100.7 O K

4320 min Summer 0.793 0.793 0.8 90.4 O K

5760 min Summer 0.711 0.711 0.8 81.0 O K

7200 min Summer 0.635 0.635 0.8 72.4 O K

8640 min Summer 0.566 0.566 0.7 64.5 O K

10080 min Summer 0.502 0.502 0.7 57.2 O K

15 min Winter 0.479 0.479 0.7 54.7 O K

30 min Winter 0.627 0.627 0.8 71.5 O K

60 min Winter 0.779 0.779 0.8 88.9 O K

120 min Winter 0.931 0.931 0.8 106.1 O K

180 min Winter 1.014 1.014 0.9 115.6 O K

240 min Winter 1.067 1.067 0.9 121.6 O K

360 min Winter 1.128 1.128 0.9 128.5 O K

480 min Winter 1.160 1.160 0.9 132.3 O K

600 min Winter 1.180 1.180 0.9 134.5 O K

720 min Winter 1.190 1.190 0.9 135.6 O K

960 min Winter 1.191 1.191 0.9 135.7 O K

1440 min Winter 1.154 1.154 0.9 131.6 O K

2160 min Winter 1.085 1.085 0.9 123.7 O K

2880 min Winter 1.017 1.017 0.9 116.0 O K

4320 min Winter 0.887 0.887 0.8 101.1 O K

5760 min Winter 0.766 0.766 0.8 87.3 O K

Storm

Event

Rain

(mm/hr)

Time-Peak

(mins)

15 min Summer 106.134 19

30 min Summer 69.795 34

60 min Summer 43.808 64

120 min Summer 26.633 124

180 min Summer 19.670 182

240 min Summer 15.784 242

360 min Summer 11.487 362

480 min Summer 9.146 482

600 min Summer 7.669 602

720 min Summer 6.638 720

960 min Summer 5.281 960

1440 min Summer 3.821 1184

2160 min Summer 2.760 1560

2880 min Summer 2.189 1964

4320 min Summer 1.577 2808

5760 min Summer 1.249 3624

7200 min Summer 1.041 4400

8640 min Summer 0.897 5184

10080 min Summer 0.791 5952

15 min Winter 106.134 19

30 min Winter 69.795 33

60 min Winter 43.808 64

120 min Winter 26.633 122

180 min Winter 19.670 180

240 min Winter 15.784 240

360 min Winter 11.487 356

480 min Winter 9.146 472

600 min Winter 7.669 588

720 min Winter 6.638 700

960 min Winter 5.281 924

1440 min Winter 3.821 1340

2160 min Winter 2.760 1664

2880 min Winter 2.189 2132

4320 min Winter 1.577 3028

5760 min Winter 1.249 3912










Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

7200 min Winter 0.655 0.655 0.8 74.7 O K

8640 min Winter 0.555 0.555 0.7 63.2 O K

10080 min Winter 0.464 0.464 0.7 52.9 O K

Storm

Event

Rain

(mm/hr)

Time-Peak

(mins)

7200 min Winter 1.041 4752

8640 min Winter 0.897 5536

10080 min Winter 0.791 6344








Rainfall Details


Rainfall Model FSR Ratio R 0.400 Cv (Winter) 0.840

Return Period (years) 100 Summer Storms Yes Shortest Storm (mins) 15

Region England and Wales Winter Storms Yes Longest Storm (mins) 10080

M5-60 (mm) 18.100 Cv (Summer) 0.750 Climate Change % +20

Time / Area Diagram

Total Area (ha) 0.248

Time

(mins)

Area

(ha)

0-4 0.248








Model Details


Storage is Online Cover Level (m) 2.000

Cellular Storage Structure

Invert Level (m) 0.000 Safety Factor 2.0

Infiltration Coefficient Base (m/hr) 0.03600 Porosity 0.95

Infiltration Coefficient Side (m/hr) 0.03600

Depth (m) Area (m²) Inf. Area (m²) Depth (m) Area (m²) Inf. Area (m²) Depth (m) Area (m²) Inf. Area (m²)

0.000 120.0 120.0 1.200 120.0 182.4 1.201 0.0 182.4



Waterman Place Cellular Soakaway

Reading RG1 8DN Two thirds of area


File 2 thirds cellular soakaway.srcx Checked by





Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

15 min Summer 0.417 0.417 1.3 90.4 O K

30 min Summer 0.546 0.546 1.4 118.2 O K

60 min Summer 0.677 0.677 1.4 146.7 O K

120 min Summer 0.807 0.807 1.5 174.8 O K

180 min Summer 0.877 0.877 1.5 190.0 O K

240 min Summer 0.921 0.921 1.5 199.6 O K

360 min Summer 0.970 0.970 1.6 210.2 O K

480 min Summer 0.995 0.995 1.6 215.4 O K

600 min Summer 1.007 1.007 1.6 218.2 O K

720 min Summer 1.011 1.011 1.6 219.0 O K

960 min Summer 1.003 1.003 1.6 217.3 O K

1440 min Summer 0.967 0.967 1.6 209.4 O K

2160 min Summer 0.912 0.912 1.5 197.5 O K

2880 min Summer 0.862 0.862 1.5 186.7 O K

4320 min Summer 0.773 0.773 1.5 167.4 O K

5760 min Summer 0.692 0.692 1.4 149.8 O K

7200 min Summer 0.617 0.617 1.4 133.6 O K

8640 min Summer 0.548 0.548 1.4 118.7 O K

10080 min Summer 0.485 0.485 1.4 105.0 O K

15 min Winter 0.468 0.468 1.3 101.4 O K

30 min Winter 0.612 0.612 1.4 132.6 O K

60 min Winter 0.761 0.761 1.5 164.8 O K

120 min Winter 0.909 0.909 1.5 196.8 O K

180 min Winter 0.990 0.990 1.6 214.4 O K

240 min Winter 1.042 1.042 1.6 225.6 O K

360 min Winter 1.101 1.101 1.6 238.6 O K

480 min Winter 1.134 1.134 1.6 245.6 O K

600 min Winter 1.153 1.153 1.6 249.7 O K

720 min Winter 1.163 1.163 1.7 251.9 O K

960 min Winter 1.164 1.164 1.7 252.2 O K

1440 min Winter 1.129 1.129 1.6 244.6 O K

2160 min Winter 1.061 1.061 1.6 229.7 O K

2880 min Winter 0.994 0.994 1.6 215.3 O K

4320 min Winter 0.866 0.866 1.5 187.5 O K

5760 min Winter 0.746 0.746 1.5 161.5 O K

Storm

Event

Rain

(mm/hr)

Time-Peak

(mins)

15 min Summer 106.134 19

30 min Summer 69.795 34

60 min Summer 43.808 64

120 min Summer 26.633 124

180 min Summer 19.670 182

240 min Summer 15.784 242

360 min Summer 11.487 362

480 min Summer 9.146 482

600 min Summer 7.669 602

720 min Summer 6.638 720

960 min Summer 5.281 960

1440 min Summer 3.821 1196

2160 min Summer 2.760 1560

2880 min Summer 2.189 1964

4320 min Summer 1.577 2808

5760 min Summer 1.249 3624

7200 min Summer 1.041 4400

8640 min Summer 0.897 5192

10080 min Summer 0.791 5952

15 min Winter 106.134 19

30 min Winter 69.795 33

60 min Winter 43.808 64

120 min Winter 26.633 122

180 min Winter 19.670 180

240 min Winter 15.784 240

360 min Winter 11.487 356

480 min Winter 9.146 472

600 min Winter 7.669 588

720 min Winter 6.638 700

960 min Winter 5.281 924

1440 min Winter 3.821 1342

2160 min Winter 2.760 1668

2880 min Winter 2.189 2132

4320 min Winter 1.577 3028

5760 min Winter 1.249 3920










Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

7200 min Winter 0.636 0.636 1.4 137.7 O K

8640 min Winter 0.536 0.536 1.4 116.0 O K

10080 min Winter 0.445 0.445 1.3 96.4 O K

Storm

Event

Rain

(mm/hr)

Time-Peak

(mins)

7200 min Winter 1.041 4752

8640 min Winter 0.897 5536

10080 min Winter 0.791 6344








Rainfall Details






Time / Area Diagram


Time

(mins)

Area

(ha)

0-4 0.460








Model Details








0.000 228.0 228.0 1.200 228.0 333.6 1.201 0.0 333.6



Waterman Place Dry Swale

Reading RG1 8DN


File Dry Swale.srcx Checked by





Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

15 min Summer 0.433 0.433 0.0 0.6 Flood Risk















5760 min Summer 0.293 0.293 0.0 0.4 O K

7200 min Summer 0.261 0.261 0.0 0.3 O K

8640 min Summer 0.237 0.237 0.0 0.3 O K

10080 min Summer 0.218 0.218 0.0 0.3 O K

15 min Winter 0.479 0.479 0.0 0.6 Flood Risk














4320 min Winter 0.295 0.295 0.0 0.4 O K

5760 min Winter 0.249 0.249 0.0 0.3 O K

Storm

Event

Rain

(mm/hr)

Time-Peak

(mins)

15 min Summer 106.134 18

30 min Summer 69.795 33

60 min Summer 43.808 62

120 min Summer 26.633 108

180 min Summer 19.670 138

240 min Summer 15.784 170

360 min Summer 11.487 240

480 min Summer 9.146 308

600 min Summer 7.669 374

720 min Summer 6.638 442

960 min Summer 5.281 576

1440 min Summer 3.821 824

2160 min Summer 2.760 1208

2880 min Summer 2.189 1560

4320 min Summer 1.577 2292

5760 min Summer 1.249 3048

7200 min Summer 1.041 3752

8640 min Summer 0.897 4496

10080 min Summer 0.791 5240

15 min Winter 106.134 18

30 min Winter 69.795 32

60 min Winter 43.808 60

120 min Winter 26.633 116

180 min Winter 19.670 144

240 min Winter 15.784 182

360 min Winter 11.487 258

480 min Winter 9.146 332

600 min Winter 7.669 404

720 min Winter 6.638 472

960 min Winter 5.281 606

1440 min Winter 3.821 866

2160 min Winter 2.760 1252

2880 min Winter 2.189 1616

4320 min Winter 1.577 2336

5760 min Winter 1.249 3064




Reading RG1 8DN






Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

7200 min Winter 0.219 0.219 0.0 0.3 O K

8640 min Winter 0.197 0.197 0.0 0.2 O K

10080 min Winter 0.180 0.180 0.0 0.2 O K

Storm

Event

Rain

(mm/hr)

Time-Peak

(mins)

7200 min Winter 1.041 3816

8640 min Winter 0.897 4504

10080 min Winter 0.791 5248




Reading RG1 8DN




Rainfall Details






Time / Area Diagram


Time

(mins)

Area

(ha)

0-4 0.003




Reading RG1 8DN




Model Details



Dry Swale Structure

Infiltration Coefficient Base (m/hr) 0.00000 Trench Width (m) 0.5

Infiltration Coefficient Side (m/hr) 0.03600 Trench Length (m) 10.0

Safety Factor 2.0 Side Slope (1:X) 3.0

Porosity 0.30 Slope (1:X) 100.0

Invert Level (m) 0.000 Cap Volume Depth (m) 0.000

Trench Height (m) 0.500 Cap Infiltration Depth (m) 0.000



Waterman Place Filter Drain

Reading RG1 8DN


File Filter Drain.mdx Checked by

Micro Drainage Network W.12.6

Existing Network Details for Storm


* - Indicates pipe has been modified outside of System 1

PN Length

(m)

Fall

(m)

Slope

(1:X)

I.Area

(ha)

T.E.

(mins)

k

(mm)

HYD

SECT

DIA

(mm)

* 1.000 62.500 0.000 0.0 0.000 4.00 0.600 o 225

* 1.001 62.500 0.000 0.0 0.000 0.00 0.600 o 225

* 1.002 1.000 0.000 0.0 0.000 0.00 0.600 o 100

PN US/MH

Name

US/CL

(m)

US/IL

(m)

US

C.Depth

(m)

DS/CL

(m)

DS/IL

(m)

DS

C.Depth

(m)

Ctrl US/MH

(mm)

* 1.000 1 0.600 0.100 0.275 0.600 0.100 0.275 600

* 1.001 2 0.600 0.100 0.275 0.600 0.100 0.275 600

* 1.002 3 0.600 0.500 0.000 0.600 0.500 0.000 600

Free Flowing Outfall Details for Storm

Outfall

Pipe Number

Outfall

Name

C. Level

(m)

I. Level

(m)

Min

I. Level

(m)

D,L

(mm)

W

(mm)

1.002 0.600 0.500 0.000 600 0

Simulation Criteria for Storm

Volumetric Runoff Coeff 0.750 Manhole Headloss Coeff (Global) 0.500 Inlet Coeffiecient 0.800

Areal Reduction Factor 1.000 Foul Sewage per hectare (l/s) 0.000 Flow per Person per Day (l/per/day) 0.000

Hot Start (mins) 0 Additional Flow - % of Total Flow 0.000 Run Time (mins) 60

Hot Start Level (mm) 0 MADD Factor * 10m³/ha Storage 2.000 Output Interval (mins) 1

Number of Input Hydrographs 2 Number of Offline Controls 0 Number of Time/Area Diagrams 0

Number of Online Controls 0 Number of Storage Structures 2 Number of Real Time Controls 0

Synthetic Rainfall Details

Rainfall Model FSR M5-60 (mm) 18.100 Cv (Summer) 0.750

Return Period (years) 2 Ratio R 0.400 Cv (Winter) 0.840

Region England and Wales Profile Type Summer Storm Duration (mins) 30




Reading RG1 8DN




Storage Structures for Storm


Infiltration Trench Manhole: 2, DS/PN: 1.001



Safety Factor 2.0 Slope (1:X) 100000.0

Porosity 0.30 Cap Volume Depth (m) 0.000

Invert Level (m) 0.000 Cap Infiltration Depth (m) 0.000

Infiltration Trench Manhole: 3, DS/PN: 1.002



Safety Factor 2.0 Slope (1:X) 100000.0

Porosity 0.30 Cap Volume Depth (m) 0.000

Invert Level (m) 0.000 Cap Infiltration Depth (m) 0.000




Reading RG1 8DN




1 year Return Period Summary of Critical Results by Maximum Level (Rank 1) for Storm


Margin for Flood Risk Warning (mm) 300.0 DTS Status ON Inertia Status OFF

Analysis Timestep Fine DVD Status OFF

Profile(s) Summer and Winter

Duration(s) (mins) 15, 30, 60, 120, 240, 360, 480, 960, 1440

Return Period(s) (years) 1, 30, 100

Climate Change (%) 0, 0, 20

PN Storm

Return

Period

Climate

Change

First X

Surcharge

First Y

Flood

First Z

Overflow

O/F

Act.

Lvl

Exc.

1.000 120 Summer 1 0% 100/360 Summer

1.001 1440 Summer 1 0% 100/360 Summer

1.002 60 Winter 1 0%

PN

US/MH

Name

Water

Level

(m)

Surch'ed

Depth (m)

Flooded

Volume

(m³)

Flow /

Cap.

O'flow

(l/s)

Pipe

Flow

(l/s) Status

1.000 1 0.109 -0.216 0.000 0.00 0.0 0.0 OK

1.001 2 0.060 -0.265 0.000 0.00 0.0 0.0 OK

1.002 3 0.000 -0.600 0.000 0.00 0.0 0.0 OK

Input Hydrograph Manhole 1, DS/PN 1.000 (Storm)

120 minute 1 year Summer I+0%

Input Hydrograph Type: FSR Dynamic

Input Variables

Region England and Wales H(85%) (m) 6.026 Urban 0.000

M5-60 (mm) 18.100 H(10%) (m) 0.709 SPR 10.000

Ratio R 0.400 Area (Ha) 0.227 LAG (hrs) 0.000

Areal Reduction Factor 1.000 SAAR (mm) 600 Base Flow (l/s) (Calculated)

Main Stream Length (m) 29.520 CWI 87.000

Output Variables

TP(0) (mins) 39 TPt (mins) 41 TB (mins) 104 PR (%) 0.500

T (mins) 4 Q (l/s) 7.3 Base Flow (l/s) 0.0 S1085 (m/km) 240.154

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

4 0.0 32 0.0 60 0.0 88 0.0 116 0.0 144 0.0 172 0.0 200 0.0 228 0.0

8 0.0 36 0.0 64 0.0 92 0.0 120 0.0 148 0.0 176 0.0 204 0.0 232 0.0

12 0.0 40 0.0 68 0.0 96 0.0 124 0.0 152 0.0 180 0.0 208 0.0 236 0.0

16 0.0 44 0.0 72 0.0 100 0.0 128 0.0 156 0.0 184 0.0 212 0.0 240 0.0

20 0.0 48 0.0 76 0.0 104 0.0 132 0.0 160 0.0 188 0.0 216 0.0

24 0.0 52 0.0 80 0.0 108 0.0 136 0.0 164 0.0 192 0.0 220 0.0

28 0.0 56 0.0 84 0.0 112 0.0 140 0.0 168 0.0 196 0.0 224 0.0




Input Variables


M5-60 (mm) 18.100 H(10%) (m) 0.709 SPR 10.000




Output Variables






Reading RG1 8DN








Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

24 0.0 360 0.0 696 0.0 1032 0.0 1368 0.0 1704 0.0 2040 0.0 2376 0.0 2712 0.0

48 0.0 384 0.0 720 0.0 1056 0.0 1392 0.0 1728 0.0 2064 0.0 2400 0.0 2736 0.0

72 0.0 408 0.0 744 0.0 1080 0.0 1416 0.0 1752 0.0 2088 0.0 2424 0.0 2760 0.0

96 0.0 432 0.0 768 0.0 1104 0.0 1440 0.0 1776 0.0 2112 0.0 2448 0.0 2784 0.0

120 0.0 456 0.0 792 0.0 1128 0.0 1464 0.0 1800 0.0 2136 0.0 2472 0.0 2808 0.0

144 0.0 480 0.0 816 0.0 1152 0.0 1488 0.0 1824 0.0 2160 0.0 2496 0.0 2832 0.0

168 0.0 504 0.0 840 0.0 1176 0.0 1512 0.0 1848 0.0 2184 0.0 2520 0.0 2856 0.0

192 0.0 528 0.0 864 0.0 1200 0.0 1536 0.0 1872 0.0 2208 0.0 2544 0.0 2880 0.0

216 0.0 552 0.0 888 0.0 1224 0.0 1560 0.0 1896 0.0 2232 0.0 2568 0.0

240 0.0 576 0.0 912 0.0 1248 0.0 1584 0.0 1920 0.0 2256 0.0 2592 0.0

264 0.0 600 0.0 936 0.0 1272 0.0 1608 0.0 1944 0.0 2280 0.0 2616 0.0

288 0.0 624 0.0 960 0.0 1296 0.0 1632 0.0 1968 0.0 2304 0.0 2640 0.0

312 0.0 648 0.0 984 0.0 1320 0.0 1656 0.0 1992 0.0 2328 0.0 2664 0.0

336 0.0 672 0.0 1008 0.0 1344 0.0 1680 0.0 2016 0.0 2352 0.0 2688 0.0




Reading RG1 8DN









Duration(s) (mins) 15, 30, 60, 120, 240, 360, 480, 960, 1440



PN Storm

Return

Period

Climate

Change

First X

Surcharge

First Y

Flood

First Z

Overflow

O/F

Act.

Lvl

Exc.

1.000 1440 Summer 30 0% 100/360 Summer

1.001 1440 Summer 30 0% 100/360 Summer

1.002 1440 Summer 30 0%

PN

US/MH

Name

Water

Level

(m)

Surch'ed

Depth (m)

Flooded

Volume

(m³)

Flow /

Cap.

O'flow

(l/s)

Pipe

Flow

(l/s) Status

1.000 1 0.179 -0.146 0.000 0.02 0.0 0.2 OK

1.001 2 0.179 -0.146 0.000 0.02 0.0 0.3 OK

1.002 3 0.179 -0.421 0.000 0.00 0.0 0.0 OK




Input Variables


M5-60 (mm) 18.100 H(10%) (m) 0.709 SPR 10.000




Output Variables



Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

24 0.0 360 0.0 696 0.2 1032 0.1 1368 0.0 1704 0.0 2040 0.0 2376 0.0 2712 0.0

48 0.0 384 0.0 720 0.2 1056 0.1 1392 0.0 1728 0.0 2064 0.0 2400 0.0 2736 0.0

72 0.0 408 0.0 744 0.2 1080 0.1 1416 0.0 1752 0.0 2088 0.0 2424 0.0 2760 0.0

96 0.0 432 0.0 768 0.2 1104 0.0 1440 0.0 1776 0.0 2112 0.0 2448 0.0 2784 0.0

120 0.0 456 0.1 792 0.2 1128 0.0 1464 0.0 1800 0.0 2136 0.0 2472 0.0 2808 0.0

144 0.0 480 0.1 816 0.2 1152 0.0 1488 0.0 1824 0.0 2160 0.0 2496 0.0 2832 0.0

168 0.0 504 0.1 840 0.2 1176 0.0 1512 0.0 1848 0.0 2184 0.0 2520 0.0 2856 0.0

192 0.0 528 0.1 864 0.2 1200 0.0 1536 0.0 1872 0.0 2208 0.0 2544 0.0 2880 0.0

216 0.0 552 0.1 888 0.1 1224 0.0 1560 0.0 1896 0.0 2232 0.0 2568 0.0

240 0.0 576 0.1 912 0.1 1248 0.0 1584 0.0 1920 0.0 2256 0.0 2592 0.0

264 0.0 600 0.1 936 0.1 1272 0.0 1608 0.0 1944 0.0 2280 0.0 2616 0.0

288 0.0 624 0.1 960 0.1 1296 0.0 1632 0.0 1968 0.0 2304 0.0 2640 0.0

312 0.0 648 0.1 984 0.1 1320 0.0 1656 0.0 1992 0.0 2328 0.0 2664 0.0

336 0.0 672 0.2 1008 0.1 1344 0.0 1680 0.0 2016 0.0 2352 0.0 2688 0.0




Reading RG1 8DN








Input Variables


M5-60 (mm) 18.100 H(10%) (m) 0.709 SPR 10.000




Output Variables



Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

24 0.0 360 0.0 696 0.2 1032 0.1 1368 0.0 1704 0.0 2040 0.0 2376 0.0 2712 0.0

48 0.0 384 0.0 720 0.2 1056 0.1 1392 0.0 1728 0.0 2064 0.0 2400 0.0 2736 0.0

72 0.0 408 0.0 744 0.2 1080 0.1 1416 0.0 1752 0.0 2088 0.0 2424 0.0 2760 0.0

96 0.0 432 0.0 768 0.2 1104 0.0 1440 0.0 1776 0.0 2112 0.0 2448 0.0 2784 0.0

120 0.0 456 0.1 792 0.2 1128 0.0 1464 0.0 1800 0.0 2136 0.0 2472 0.0 2808 0.0

144 0.0 480 0.1 816 0.2 1152 0.0 1488 0.0 1824 0.0 2160 0.0 2496 0.0 2832 0.0

168 0.0 504 0.1 840 0.2 1176 0.0 1512 0.0 1848 0.0 2184 0.0 2520 0.0 2856 0.0

192 0.0 528 0.1 864 0.2 1200 0.0 1536 0.0 1872 0.0 2208 0.0 2544 0.0 2880 0.0

216 0.0 552 0.1 888 0.1 1224 0.0 1560 0.0 1896 0.0 2232 0.0 2568 0.0

240 0.0 576 0.1 912 0.1 1248 0.0 1584 0.0 1920 0.0 2256 0.0 2592 0.0

264 0.0 600 0.1 936 0.1 1272 0.0 1608 0.0 1944 0.0 2280 0.0 2616 0.0

288 0.0 624 0.1 960 0.1 1296 0.0 1632 0.0 1968 0.0 2304 0.0 2640 0.0

312 0.0 648 0.1 984 0.1 1320 0.0 1656 0.0 1992 0.0 2328 0.0 2664 0.0

336 0.0 672 0.2 1008 0.1 1344 0.0 1680 0.0 2016 0.0 2352 0.0 2688 0.0




Reading RG1 8DN









Duration(s) (mins) 15, 30, 60, 120, 240, 360, 480, 960, 1440



PN Storm

Return

Period

Climate

Change

First X

Surcharge

First Y

Flood

First Z

Overflow

O/F

Act.

Lvl

Exc.

1.000 1440 Summer 100 +20% 100/360 Summer

1.001 1440 Summer 100 +20% 100/360 Summer

1.002 1440 Summer 100 +20%

PN

US/MH

Name

Water

Level

(m)

Surch'ed

Depth (m)

Flooded

Volume

(m³)

Flow /

Cap.

O'flow

(l/s)

Pipe

Flow

(l/s) Status

1.000 1 0.449 0.124 0.000 0.04 0.0 0.7 FLOOD RISK

1.001 2 0.449 0.124 0.000 0.04 0.0 0.7 FLOOD RISK

1.002 3 0.449 -0.151 0.000 0.00 0.0 0.0 OK




Input Variables


M5-60 (mm) 18.100 H(10%) (m) 0.709 SPR 10.000




Output Variables



Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

24 0.0 360 0.1 696 0.5 1032 0.1 1368 0.1 1704 0.0 2040 0.0 2376 0.0 2712 0.0

48 0.0 384 0.1 720 0.6 1056 0.1 1392 0.1 1728 0.0 2064 0.0 2400 0.0 2736 0.0

72 0.1 408 0.1 744 0.6 1080 0.1 1416 0.1 1752 0.0 2088 0.0 2424 0.0 2760 0.0

96 0.1 432 0.1 768 0.7 1104 0.1 1440 0.1 1776 0.0 2112 0.0 2448 0.0 2784 0.0

120 0.1 456 0.1 792 0.6 1128 0.1 1464 0.1 1800 0.0 2136 0.0 2472 0.0 2808 0.0

144 0.1 480 0.1 816 0.6 1152 0.1 1488 0.0 1824 0.0 2160 0.0 2496 0.0 2832 0.0

168 0.1 504 0.1 840 0.5 1176 0.1 1512 0.0 1848 0.0 2184 0.0 2520 0.0 2856 0.0

192 0.1 528 0.2 864 0.4 1200 0.1 1536 0.0 1872 0.0 2208 0.0 2544 0.0 2880 0.0

216 0.1 552 0.2 888 0.4 1224 0.1 1560 0.0 1896 0.0 2232 0.0 2568 0.0

240 0.1 576 0.2 912 0.3 1248 0.1 1584 0.0 1920 0.0 2256 0.0 2592 0.0

264 0.1 600 0.3 936 0.3 1272 0.1 1608 0.0 1944 0.0 2280 0.0 2616 0.0

288 0.1 624 0.3 960 0.2 1296 0.1 1632 0.0 1968 0.0 2304 0.0 2640 0.0

312 0.1 648 0.4 984 0.2 1320 0.1 1656 0.0 1992 0.0 2328 0.0 2664 0.0

336 0.1 672 0.4 1008 0.2 1344 0.1 1680 0.0 2016 0.0 2352 0.0 2688 0.0




Reading RG1 8DN








Input Variables


M5-60 (mm) 18.100 H(10%) (m) 0.709 SPR 10.000




Output Variables



Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

Time

(mins)

Flow

(l/s)

24 0.0 360 0.1 696 0.5 1032 0.1 1368 0.1 1704 0.0 2040 0.0 2376 0.0 2712 0.0

48 0.0 384 0.1 720 0.6 1056 0.1 1392 0.1 1728 0.0 2064 0.0 2400 0.0 2736 0.0

72 0.1 408 0.1 744 0.6 1080 0.1 1416 0.1 1752 0.0 2088 0.0 2424 0.0 2760 0.0

96 0.1 432 0.1 768 0.7 1104 0.1 1440 0.1 1776 0.0 2112 0.0 2448 0.0 2784 0.0

120 0.1 456 0.1 792 0.6 1128 0.1 1464 0.1 1800 0.0 2136 0.0 2472 0.0 2808 0.0

144 0.1 480 0.1 816 0.6 1152 0.1 1488 0.0 1824 0.0 2160 0.0 2496 0.0 2832 0.0

168 0.1 504 0.1 840 0.5 1176 0.1 1512 0.0 1848 0.0 2184 0.0 2520 0.0 2856 0.0

192 0.1 528 0.2 864 0.4 1200 0.1 1536 0.0 1872 0.0 2208 0.0 2544 0.0 2880 0.0

216 0.1 552 0.2 888 0.4 1224 0.1 1560 0.0 1896 0.0 2232 0.0 2568 0.0

240 0.1 576 0.2 912 0.3 1248 0.1 1584 0.0 1920 0.0 2256 0.0 2592 0.0

264 0.1 600 0.3 936 0.3 1272 0.1 1608 0.0 1944 0.0 2280 0.0 2616 0.0

288 0.1 624 0.3 960 0.2 1296 0.1 1632 0.0 1968 0.0 2304 0.0 2640 0.0

312 0.1 648 0.4 984 0.2 1320 0.1 1656 0.0 1992 0.0 2328 0.0 2664 0.0

336 0.1 672 0.4 1008 0.2 1344 0.1 1680 0.0 2016 0.0 2352 0.0 2688 0.0



Waterman Place National Grid Substation

Reading RG1 8DN Cellular Soakaway


File 1no Cellular Soakaway.srcx Checked by





Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

15 min Summer 0.422 0.422 0.9 60.1 O K

30 min Summer 0.552 0.552 0.9 78.6 O K

60 min Summer 0.685 0.685 1.0 97.6 O K

120 min Summer 0.815 0.815 1.0 116.2 O K

180 min Summer 0.885 0.885 1.1 126.2 O K

240 min Summer 0.930 0.930 1.1 132.5 O K

360 min Summer 0.978 0.978 1.1 139.3 O K

480 min Summer 1.001 1.001 1.1 142.6 O K

600 min Summer 1.012 1.012 1.1 144.3 O K

720 min Summer 1.015 1.015 1.1 144.7 O K

960 min Summer 1.005 1.005 1.1 143.1 O K

1440 min Summer 0.969 0.969 1.1 138.0 O K

2160 min Summer 0.913 0.913 1.1 130.2 O K

2880 min Summer 0.863 0.863 1.1 123.0 O K

4320 min Summer 0.772 0.772 1.0 110.1 O K

5760 min Summer 0.691 0.691 1.0 98.4 O K

7200 min Summer 0.616 0.616 1.0 87.7 O K

8640 min Summer 0.547 0.547 0.9 77.9 O K

10080 min Summer 0.484 0.484 0.9 68.9 O K

15 min Winter 0.473 0.473 0.9 67.4 O K

30 min Winter 0.619 0.619 1.0 88.2 O K

60 min Winter 0.769 0.769 1.0 109.6 O K

120 min Winter 0.918 0.918 1.1 130.8 O K

180 min Winter 0.999 0.999 1.1 142.4 O K

240 min Winter 1.051 1.051 1.1 149.8 O K

360 min Winter 1.110 1.110 1.1 158.1 O K

480 min Winter 1.141 1.141 1.1 162.6 O K

600 min Winter 1.159 1.159 1.2 165.2 O K

720 min Winter 1.168 1.168 1.2 166.4 O K

960 min Winter 1.167 1.167 1.2 166.3 O K

1440 min Winter 1.128 1.128 1.1 160.7 O K

2160 min Winter 1.060 1.060 1.1 151.0 O K

2880 min Winter 0.992 0.992 1.1 141.3 O K

4320 min Winter 0.861 0.861 1.1 122.7 O K

5760 min Winter 0.741 0.741 1.0 105.5 O K

Storm

Event

Rain

(mm/hr)

Time-Peak

(mins)

15 min Summer 106.134 19

30 min Summer 69.795 34

60 min Summer 43.808 64

120 min Summer 26.633 124

180 min Summer 19.670 182

240 min Summer 15.784 242

360 min Summer 11.487 362

480 min Summer 9.146 482

600 min Summer 7.669 602

720 min Summer 6.638 720

960 min Summer 5.281 952

1440 min Summer 3.821 1168

2160 min Summer 2.760 1552

2880 min Summer 2.189 1960

4320 min Summer 1.577 2768

5760 min Summer 1.249 3584

7200 min Summer 1.041 4392

8640 min Summer 0.897 5184

10080 min Summer 0.791 5952

15 min Winter 106.134 19

30 min Winter 69.795 33

60 min Winter 43.808 64

120 min Winter 26.633 122

180 min Winter 19.670 180

240 min Winter 15.784 240

360 min Winter 11.487 356

480 min Winter 9.146 472

600 min Winter 7.669 586

720 min Winter 6.638 700

960 min Winter 5.281 922

1440 min Winter 3.821 1328

2160 min Winter 2.760 1648

2880 min Winter 2.189 2108

4320 min Winter 1.577 3024

5760 min Winter 1.249 3864










Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

7200 min Winter 0.631 0.631 1.0 89.9 O K

8640 min Winter 0.532 0.532 0.9 75.8 O K

10080 min Winter 0.443 0.443 0.9 63.1 O K

Storm

Event

Rain

(mm/hr)

Time-Peak

(mins)

7200 min Winter 1.041 4688

8640 min Winter 0.897 5528

10080 min Winter 0.791 6256








Rainfall Details






Time / Area Diagram


Time

(mins)

Area

(ha)

0-4 0.306








Model Details








0.000 150.0 150.0 1.200 150.0 234.0 1.201 0.0 234.0

Documents

Flood Risk Assessment October 2011 Document …galloperwindfarm.com/assets/images/documents/Reports/Flood_Risk...Flood Risk Assessment . October 2011 . Document Reference ... 4.2.3