Towcester Vale Flood Risk Assessment

November 2007 Revision 1

Issue No 1 44406876 / BDRP0007

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Towcester Vale Flood Risk Assessment

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Towcester Vale Flood Risk Assessment

CONTENTS

Section Page No

EXECUTIVE SUMMARY...... 1

1. INTRODUCTION...... 3 1.1. Background ...... 3 1.2. Study Aims and Objectives ...... 3 1.3. Data Collected and Consultation with the EA ...... 4 1.3.1. Data Collected...... 4 1.3.2. Consultation with the EA ...... 5 1.4. Site Setting ...... 5 1.4.1. Location and Type of Proposed Development...... 5 1.4.2. Topography ...... 5 1.4.3. Hydrology ...... 6 1.4.4. Geology ...... 6 1.4.5. Hydrogeology ...... 8 1.4.6. Flood Vulnerability Classification ...... 9

2. EXISTING/PRE-DEVELOPMENT FLOOD RISK ...... 10 2.1. Historical Flooding...... 10 2.2. Risk of Flooding from Rivers ...... 10 2.2.1. Calculation of Flood Flows ...... 11 2.2.2. Hydraulic Modelling...... 12 2.3. Risk of Flooding from Land ...... 17 2.3.1. Greenfield Runoff Rates...... 17 2.3.2. Greenfield Volumes...... 18 2.4. Risk of Flooding from Groundwater ...... 18 2.5. Probability of Site Flooding ...... 19 2.6. Climate Change Adjustment for Peak River Flows ...... 19

3. DEVELOPMENT PROPOSAL...... 20 3.1. Development Layout Details ...... 20 3.2. Proposed Development within the Floodplain...... 20 3.2.1. Channel Diversion...... 20 3.2.2. Silverstone Brook Road Crossings ...... 21 3.2.3. Wood Burcote Brook Road Crossings ...... 22 3.2.4. Flood Storage Compensation ...... 23

4. POST-DEVELOPMENT FLOOD RISK...... 24 4.1. Surface Water Drainage Strategy ...... 24 4.1.1. General Policy Guidelines...... 24 4.1.2. Selection of SUDS...... 25 4.1.3. Maintenance of SUDS...... 27 4.2. Risk of Flooding from Rivers ...... 27 4.3. Risk of Flooding from Land ...... 27 4.4. Risk of Flooding from Groundwater ...... 27

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CONTENTS

Section Page No 4.5. Residual Flood Risk ...... 27

5. SUMMARY AND CONCLUSIONS ...... 27

Appendix A - Compliance with PPS25 Guidelines

Appendix B - Geotechnical Investigation Hand Auger Logs

Appendix C - Calculation Details for Existing/Pre-Development Flood Flows

Appendix D - Environment Agency Data Used for Silverstone Brook Model Calibration

Appendix E - Calculation Details for Assessment of Flooding for Existing/Pre- Development Conditions

Appendix F - WinDes Program Output Results for Greenfield Runoff Rates and Volumes

Appendix G - Calculation Details for Assessment of Flooding for Development Conditions

Figures

Drawings

Drawing 44406876/01 – Location Map

Drawing 44406876/02 – Towcester Vale Site, Development Proposal with Surface Water Drainage Strategy

Drawing 44406876/03 – Historical Flooding Map

Drawing 44406876/04 – Geological Map

Drawing 44406876/05 – Towcester Vale Geological Investigation, Hand Auger Borehole Locations

Drawing 44406876/06 – Groundwater Vulnerability Map

Drawing 44406876/07 – Groundwater Source Protection Zones Map

Drawing 44406876/08 – Flood Map

Drawing 44406876/09 – Existing Site Hydrology

Drawing 44406876/10 – Flood Risk Assessment, Existing Conditions with Climate Change Flow Adjustment for Silverstone Brook

Drawing 44406876/11 – Flood Risk Assessment, Existing Conditions with Climate

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CONTENTS

Section Page No Change Flow Adjustment for Wood Burcote Brook, Sheet 1 of 2

Drawing 44406876/12 – Flood Risk Assessment, Existing Conditions with Climate Change Flow Adjustment for Wood Burcote Brook, Sheet 2 of 2

Drawing 44406876/13 – Flood Risk Assessment, Silverstone Brook Post Development Conditions

Photographs

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EXECUTIVE SUMMARY

URS Corporation Limited (URS) was commissioned by Persimmon Homes Ltd to carry out a flood risk assessment (FRA) pertaining to the development of 202.3ha of farmland located south of the town of Towcester in Northamptonshire. Based on Planning Policy Statement 25: Development and Flood Risk (PPS25), a formal flood risk assessment is required to ensure that flood risks to, or caused by, a development are successfully managed. A study comprising of data collection, a site visit, assessment of the flood risks, and flood mitigation measures was therefore undertaken.

The 202.3ha site lies to the south of Towcester and is made up of open farmland. It is bordered by the A43 to the west, by housing developments to the north, by A5 (London Road) to the east, and by farmland to the south. The site is crescent shaped with curved edges bordering the housing to the north and farmland to the south, about 3km long, and 0.5km wide. The site will be developed to comprise 3,000 residential units in addition to up to 21 hectares of employment land with retail, education and community facilities and over 50 hectares of open space. The scheme will also include the provision of a bypass joining the A5 and the A43 to the south of the site.

Two brooks cross the site, Silverstone Brook flowing northerly on the east side, and Wood Burcote Brook flowing northerly through the middle of the site.

The site is divided in two major parts by a south-north ridge about 950m east of the A43, which separates the catchments of the two brooks flowing through the area. The land on the west side of the ridge falls northwesterly towards Silverstone Brook and makes up watershed Area 1. The land on the east side of the ridge falls northeasterly towards Wood Burcote Brook and makes up watershed Area 2. Also, a ridge parallel to the A5 divides the eastern part of the site in the third catchment, watershed Area 3.

The Environment Agency (EA) flood zone map for Towcester (See Drawing 44406876/08) indicates that approximately 10ha of the site (excluding the flood compensation area) is located in Zone 3a (High Probability) along Silverstone Brook. The remainder of the site lies within Zone 1 (Low Probability), except some small areas along Silverstone Brook on the northern part of the site, which are located in Zone 2 (Medium Probability). “More Vulnerable”, “Less Vulnerable” and “Water Compatible” land uses are all appropriate within Flood Zones 1 and 2. To more accurately define the flood zones at the site, URS has created Hydraulic Engineering Centre-River Analysis System (HEC- RAS) models for the relevant stretches of the two brooks crossing the site.

The assessment indicates that:

• Development of this site using on site attenuation would not increase either the existing surface water runoff rate or volume from the site, and therefore would not increase flood risk elsewhere.

• A number of opportunities are available for the use of Sustainable Urban Drainage Systems (SUDS) within the development proposal. The proposed development site was assessed for preliminary design purposes as 80% impermeable in the high-density housing areas, 70% impermeable in the medium density housing areas, 60% impermeable in the low-density housing areas, 85% impermeable in the mixed use and employment areas, 65% impermeable

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in the education areas and 60% impermeable in the highway areas. Rainfall intensities used in WinDes calculations were increased by 20% for commercial and industrial land use areas, and 30% for residential land use areas to allow for climate change. It has been shown that surface water runoff can be restricted to existing greenfield runoff rates when redeveloping this site (See Drawing 44406876/09 for location of Areas 1, 2 and 3, and Drawings 44406876/02 for the layout of the SUDS scheme.

• Development of the site calls for construction of a bypass road on the south connecting the site to the A43 and the A5, and Spine Road and two Access Roads within the site. This scheme involves raising of land in the flood area along Silverstone Brook requiring flood compensation. The compensatory area will be provided south of the bypass as shown in Drawing 4406876/13. This will ensure that water levels for flood events up to and including the 1% annual probability (1 in 100 years) event are not significantly different from the existing conditions. Because of the small extent of Zone 3a along Wood Burcote Brook, compensatory provision will not be required in this area of development. Climate change adjustments were accounted for in these evaluations (See Section 3).

• The bypass scheme will involve construction of a roundabout over the existing Silverstone Brook. This plan will require diversion of 250m of the existing channel to the southeast. The EA did not object to this proposal during a meeting held on 21 st September 2007. It is proposed that the new diversion be a 280m long two-stage channel (a combination of a main channel and overflow channel) designed to cope with multiple storm events including the 1% annual probability (1 in 100 years) flow. South of the bypass the two-stage channel will be located in the area used for flood compensation. The compensation area will provide significant detention storage volume during major storm events, ensuring that the water levels for post development and existing conditions are not significantly different. In addition, the main channel overbanks will be used for farming and gently sloped towards the main channel.

The recently published Development and Flood Risk: A Practice Guide Companion to PPS25 – ‘Living Draft’ (February 2007) requires that a FRA Pro-forma be completed and submitted with the planning application for developments for which a FRA is required. Answers to the questions raised in this pro-forma can be found in Appendix A of this report.

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1. INTRODUCTION

1.1. Background

Persimmon Homes Ltd. commissioned URS Corporation Ltd. (URS) in January 2007 to carry out a Flood Risk Assessment (FRA) to support the planning application for a site located south of the town of Towcester in Northamptonshire, England. The site, which is presently used as farmland, will be developed to comprise 3,000 residential units in addition to up to 21 hectares of employment land with retail, education and community facilities and over 50 hectares of open space. The scheme will also include the provision of a bypass joining the A5 and the A43 to the south of the site. URS is not aware of an existing Strategic Flood Risk Assessment (SFRA) from the Local Planning Authority covering this site.

The assessment was prepared in consultation with the EA, and based on the requirements presented in the Planning Policy Statement 25: Development and Flood Risk (PPS25).

The purpose of this evaluation is to identify and assess the risk of all forms of flooding to and from the development, and demonstrate how these flood risks will be managed, taking climate change into account.

1.2. Study Aims and Objectives

Regarding new developments, PPS25 aims to ensure that flood risk is taken into account at all stages in the planning process, to avoid inappropriate development in areas at risk of flooding. This policy recommends preparation of sustainable planning strategies to reduce the flood risk to and from new developments through location, layout and design, incorporating sustainable drainage systems (SUDS).

This study objective is to complete a Site-specific FRA that meets the requirements of PPS25. This FRA will examine the risk of flooding from rivers, land, groundwater, and any residual flood-related residual risks to and from the development site. In order to accomplish this goal, the following tasks have been carried out:

• Liaison with the EA regarding the required analysis, procedures, and for data collection to support the site hydrologic study.

• Review of available data and assessment of the fluvial and groundwater related flood risks.

• Review of the existing site drainage and assessment of the existing runoff rates at the site.

• Development of hydraulic models to assess the effect of rainfall events, including an event with 1% (1 in 100) annual probability, on water levels along the relevant stretches of the brooks.

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• Delineation of flood zones, as defined in PPS25.

• Assessment of the possible effects of climate change.

1.3. Data Collected and Consultation with the EA

1.3.1. Data Collected

The table below indicates the data that has been collected and used for this assessment.

TABLE 1 Data Collected Purpose Data and Source Comments

Identification of 1:50,000 Landranger Series Map, Identifies the position of the hydrological and hydro- Northampton and Milton Keynes, Sheet 152 site and general topography geological features - Ordnance Survey (1991) with 10m contour lines

Site Topography – Milton Keynes Survey Provides existing site Limited (2006), and URS (2007) topography with 0.5m contour lines

Groundwater Vulnerability Map of the Helps in determining the Northern Cotswolds, Sheet 30 – EA (1996) surface water drainage strategy Groundwater Vulnerability Map of Bedfordshire, Sheet 31 - National Rivers Authority (1995)

Groundwater Source Protection Zones map Identifies the risk of - EA (http://www.environment- contamination from any agency.gov.uk/) activities that might cause pollution in the area of the site

Geological Map, Towcester, Sheet 202, Identifies the underlying Solid and Drift Edition (1969) – Geological geology at the site Survey of Great Britain (England and Wales)

FEH CD-ROM 1999 Version 1.0 – NERC Provides rainfall and (1999) catchment data

Identification of existing Flood Map – EA (http://www.environment- Identifies the flood risk at the flood risk agency.gov.uk/) site

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1.3.2. Consultation with the EA

Assessment of the flood risk at the site has been done in consultation with the EA. Thus, URS agreed with the EA on the methodology that would be applied to calculate the greenfield discharge rates and runoff storage and control in a meeting held on 2 nd November 2006. Water levels data from a hydraulic model of the Silverstone Brook Main River was provided by the EA in December 2006 and used in the calibration of the model that URS constructed for this study.

The EA reviewed a preliminary HEC-RAS model of the Silverstone Brook existing conditions within the area of interest in July 2007, and had some suggestions for model improvement. These suggestions were also discussed during a meeting between the EA and URS held on 21 st September 2007. After this meeting the EA provided more data that was used by URS to improve the Silverstone Brook existing conditions model as suggested by the EA. During the 21 st September 2007 meeting, URS also discussed with the EA the proposed Silverstone Brook channel diversion scheme in the area of the new bypass roundabout, in conjunction with the area planned for flood compensation.

1.4. Site Setting

1.4.1. Location and Type of Proposed Development

The site lies to the south of Towcester in Northamptonshire, centred at National Grid Reference (NGR) SP 696 468 (See Drawing 44406876/01). The site comprises some 202.3ha of open farmland, and is bordered by the A43 to the west, by housing development to the north, by the A5 to the east, and by farmland to the south. The site is crescent shaped with curved edges bordering the housing to the north and farmland to the south, about 3km long, and 0.5km wide. The scheme will include 3,000 residential units in addition to up to 21 hectares of employment land with retail, education and community facilities, and over 50 hectares of open space. The scheme will also include the provision of a bypass joining the A5 and the A43 to the south of the site (See Drawing 44406876/02).

1.4.2. Topography

The site is currently undeveloped open farmland with ground levels varying from about 90m AOD to 130m AOD. The lower elevations are along the two brooks that cross-over the site, Silverstone Brook flowing northerly on the east side, and Wood Burcote Brook flowing northerly through the middle of the site. A number of farm ditches are connected to the two brooks throughout the site.

The site is divided in two major parts by a south-north ridge about 950m east of the A43 Highway, which separates the catchments of the two brooks flowing through the area. The land on the west side of the ridge falls northwesterly towards Silverstone Brook at a grade of 4.6%, and the land on the east side of the ridge falls northeasterly at a grade of 3.3% towards Wood Burcote Brook. A ridge parallel to the A5 divides the eastern part of the site. On the east side of this ridge the land falls northeasterly at a slope of 7%, and on the west side, the land falls westerly at a slope of 3% (See Drawing 44406876/09).

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1.4.3. Hydrology

Silverstone Brook and Wood Burcote Brook are two tributaries of River Tove (which flows easterly on the north side of Towcester). Silverstone Brook flows northerly through the site over a distance of approximately 1km, about 200m from the west site border. Wood Burcote Brook flows northerly through the site over a distance of approximately 0.7km, approximately 800m from the east site border.

Surface water runoff from 65.8ha on the east side of the site flows overland into Silverstone Brook. Surface water from 105.2ha in the middle of the site discharges overland into Wood Burcote Brook, and 31.3ha on the east side of the site, discharges overland northeasterly towards the A5 (Drawing 44406876/09).

1.4.4. Geology

The underlying geology of the site is covered by the Geological Survey of Great Britain (England and Wales), Sheet 202, Towcester. The geological map indicates that the superficial and solid geology of the area comprises the following:

Pleistocene and Recent: Glacial Deposits

Jurasic: Blisworth Limestone Upper Estuarine Series Northampton Sand Upper Lias Clay

A narrow corridor of alluvium is present along Silverstone Brook, and Limestone along Wood Burcote Brook over-banks and the west side of the site. A site investigation was carried out by URS during March 2007, and included nine hand auger boreholes across the area of the proposed development. The borings encountered a variety of soil strata, as indicated in Table 2.

TABLE 2 Geological Investigation Data Hole From To Description HA1 0.0m 0.2m Topsoil 0.2m 0.85m Soft to firm brown gravelly CLAY (Upper Lias) 0.85m 1.20m Light brown clayey sandy GRAVEL (Upper Lias) HA2 0.0m 0.2m Topsoil 0.2m 1.2m Firm grey mottled orange-brown CLAY (Northampton Sand/Upper Lias) 1.2m 2.0m Firm grey highly fissured CLAY (Upper Lias)

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TABLE 2 Geological Investigation Data Hole From To Description HA3 0.0m 0.25m Topsoil 0.25m 0.5m Weak light brown fine-grained LIMESTONE, highly weathered (Blisworth Limestone) HA4 0.0m 0.3m Topsoil 0.3m 0.7m Firm to stiff brown CLAY with occasional gravel and limestone fragments (Upper Estuarine Series) 0.7m 1.50m Soft to firm orange-brown CLAY (Upper Estuarine Series) HA5 0.0m 0.25m Topsoil 0.25m 1.10m Soft to firm brown sandy CLAY with occasional gravel (Upper Estuarine Series) 1.1m 2.0m Brown gravelly clayey fine to medium SAND (Upper Estuarine Series) HA6 0.0m 0.2m Topsoil 0.2m 2.0m Soft to firm brown sandy CLAY with occasional gravel (Upper Estuarine Series) HA8 0.0m 0.2m Topsoil 0.2m 0.85m Firm light brown CLAY with occasional limestone gravel (Glacial Till) 0.85m 1.0m Weak light brown fine-grained LIMESTONE, highly weathered (Upper Estuarine Limestone) HA9 0.0m 0.3m Topsoil 0.3m 0.6m Firm light grey mottled light brown CLAY (Glacial Till) 0.6m 2.0m Firm to stiff grey fissured CLAY with partings and pockets of orange-brown sand (Glacial Till) HA10 0.0m 0.2m Topsoil 0.2m 0.6m Made Ground 0.6m 2.0m Stiff orange-brown CLAY with occasional gravel (Glacial Till)

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Groundwater was encountered in five of the borings (HA1, HA2, HA4, HA5, HA6) between 0.85m below ground level (bgl), and 1.6m bgl. HA3 and HA8 encountered limestone, but did not encounter groundwater. It is likely that the limestone will act as an aquifer and water will probably be encountered within this stratum below the level reached by the hand auger investigation. The remaining two hand auger holes where groundwater was not encountered are predominantly cohesive. The depths where groundwater was encountered are given in the table below.

TABLE 3 Hand Auger Boreholes Groundwater Depth Depth of Hole groundwater HA1 0.85m HA2 1.6m HA4 1.0m HA5 1.3m HA6 1.6m

In addition surface water was noted at a number of the locations across the area indicating poor infiltration rates of the underlying strata. This was located predominantly in the areas around HA1 to HA4 and also in the area around HA8 and HA10.

1.4.5. Hydrogeology

Reference to the EA Groundwater Vulnerability for the Northern Cotswolds, Sheet 30 map (1996), and the National Rivers Authority Groundwater Vulnerability of Bedfordshire, Sheet 31 map (1995), indicate that the site is positioned on an area covering three geological classes: Non-Aquifer, Minor Aquifer, and Major Aquifer (Drawing 44406876/06). This suggests that the below strata at the site is made of formations that vary in their capacity of transmitting contaminated recharge entering their surface

The Non-Aquifer area is more predominant on the east side of the site. Non-Aquifers are negligibly permeable, and are regarded as containing insignificant quantities of groundwater. They comprise of formations of clay, earth, and mudstones. Although groundwater flow through these formations is imperceptible, it does take place and needs to be considered in assessing the risk associated with persistent pollutants.

Minor-Aquifers are present at the site as narrow corridors on the west and the northeast side. They are variably permeable and consist of fractured or potentially fractured rocks or other formations of variable permeability. These aquifers do not usually produce enough water for abstraction, but they are important for the local supplies and in supplying base flow to rivers. The soils forming Minor-Aquifers at the site generally have high leaching potential, that is, they have little ability to attenuate diffuse source

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pollutants in which leaching discharges have the potential to move rapidly to underlying strata or to shallow groundwater.

Major-Aquifers occupy the southern part of the site and comprise of formations of limestone and sandstone. They are highly permeable formations that may be highly productive and able to support large abstractions of water. At the site, these aquifers are overlaid by low permeability drift deposits, such as till and stoneless clay and silt. The soils forming the Major-Aquifers at the site have intermediate leaching potential and can possibly transmit a wide range of pollutants.

The EA Groundwater Source Protection Zones map of the area indicates that the site does not lie within any groundwater source protection zone (Drawing 44406876/07).

1.4.6. Flood Vulnerability Classification

The EA provides a web-based Flood Map of England on their internet site. The flood zones shown on the Internet maps indicate the current estimates of the risk of flooding from rivers and the sea, without considering other sources, and without accounting for potential climate change impact. Also, the EA maps show the extent of the natural floodplain if there were no flood defences or certain other manmade structures and channel improvements.

The recently published PPS25 defines four flood zones in which a site may be located:

Zone 1 – Low Probability, comprises of land assessed as having a less than 1 in 1000 annual probability of river or sea flooding (<0.1%).

Zone 2 – Medium Probability, comprises land assessed as having between a 1 in 100 and 1 in 1000 annual probability of river flooding (1%-0.1%) or between a 1 in 200 and 1 in 1000 annual probability of sea flooding (0.5%-0.1%).

Zone 3a – High Probability, comprises land assessed as having a 1 in 100 or greater annual probability of river flooding (>1%) or a 1 in 200 or greater annual probability of flooding from the sea (>0.5%).

Zone 3b – The Functional Floodplain, comprises land where water has to flow or be stored in times of flood. In general this zone is identified as land, which would flood with an annual probability of 1 in 20 (5%) or greater.

The current EA indicative flood map for Towcester (See Drawing 44406876/08) shows that approximately 10ha of the site (excluding the flood compensation area) is located in Zone 3a (High Probability) along Silverstone Brook. The rest of the site lies within Zone 1 (Low Probability), except some small areas along Silverstone Brook on the northern part of the site, which are located in Zone 2 (Medium Probability).

To more accurately define the flood zones at the site, HEC-RAS models were created for the relevant stretches of the two brooks crossing the site, using recent topography.

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2. EXISTING/PRE-DEVELOPMENT FLOOD RISK

Using the guidance provided in PPS25, URS has identified and assessed the potential sources of flooding for the Towcester site: Flooding from Rivers, Flooding from Land, and Flooding from Groundwater.

2.1. Historical Flooding

The development site contains two brooks which represent the main risk of flooding at the site, Silverstone Brook and Wood Burcote Brook. There were two known noticeable floods in the area, the first in 1969 and the second in 1998. Based on the Woods Warren Consulting Engineers, October 2002 Report Burcote Road Towcester, Flood Risk Assessment , during the the flood of 1969 the water levels of Wood Burcote Brook, which in 1969 was an open watercourse down to Burcote Road, reached a high of 90.91m AOD in the area where the brook enters Towcester. The EA has no records for the 1998 floods in that area of Wood Burcote Brook.

According to the same report, the floods of Easter 1998 resulted in some localised flooding of Silverstone Brook. These flood areas are indicated on a drawing extracted from the report indicating some localised flooding along Silverstone Brook in areas upstream of Springfields Road and Watling Street (See Drawing 44406876/03).

2.2. Risk of Flooding from Rivers

The assessment method for the fluvial flood risk at the site has been carried out in two stages:

Stage 1: Calculation of Flood Flows

In order to assess the flood discharges required in the hydraulic analyses for 5% annual probability (1 in 20 years), 1% annual probability (1 in 100 years), and 0.5% annual probability (1 in 200 years) flood events, URS used the Institute of Hydrology Flood Estimation Handbook (FEH) software, and the Centre for Ecology and Hydrology Revitalized Flood Studies Report (FSR)/FEH Rainfall Runoff Method v1.3. The 5% annual probability (1 in 20 years), and 1% annual probability (1 in 100 years) events were selected to determine the Flood Zones 3a and 3b at the site. The 0.5% annual probability (1 in 200 years) event was selected for sensitivity analysis to determine how an increase in flow would affect the Flood Zone 3a limits.

During the preliminary review of the URS Silverstone Brook hydraulic model for the existing conditions, the EA was in favour of the methodology used in determining the modelling flows. The same method was applied in calculating the flows for Wood Burcote Brook.

Stage 2: Assessment of Flooding.

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by Milton Keynes Ltd. in 2006 for most of the site, and URS in 2007 for an area of approximately 4.6ha downstream of the A43 and Silverstone Brook junction.

The models were adjusted based on consultations with the EA.

The following sections summarise the main findings of these calculations

2.2.1. Calculation of Flood Flows

Wood Burcote Brook flows northerly through Towcester, and joins the River Tove just north of the town. The Silverstone Brook catchment, upstream of the outlet of interest (NGR SP 68572 47960), is 21.42km 2. The Wood Burcote Brook catchment, upstream of the outlet of interest (NGR SP 69625 47788) is 2.47 square kilometres (km 2).

No gauged information is available for either Silverstone Brook or Wood Burcote Brook. The FEH rainfall-runoff methodology was adopted, alongside the Centre for Ecology and Hydrology Revitalized FSR/FEH Rainfall Runoff Method v1.3 to determine flood discharges for a range of annual probability floods in the Silverstone Brook and Wood Burcote Brook catchments (Table 4). Calculation details are provided in Appendix C.

TABLE 4 Flood Flow Derivation for Silverstone Brook and Wood Burcote Brook Annual Probability of Flood Flow (m 3/s) River Flooding Silverstone Brook Wood Burcote Brook 5% 9.5 1.5 (1 in 20 years) 1% 13.3 2.2 (1 in 100 years) 0.5% 15.6 2.6 (1 in 200 years) Notes: Silverstone Brook catchment outlet taken at NGR SP 68572 47960 Wood Burcote Brook catchment outlet taken at NGR SP 69625 47788

Based on PPS25 recommendations, a 20% increase was applied to the peak flows to account for potential effects of climate change. These flows were then used in the HEC- RAS analyses to determine the extent of flooding for each annual probability analysed (Table 5).

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TABLE 5 Flood Flows Derivation for Silverstone Brook and Wood Burcote Brook Taking into Account Possible Effects of Climate Change Annual Probability of Flood Flows (m 3/s) River Flooding Silverstone Brook Wood Burcote Brook 5% 11.4 1.8 (1 in 20 years) 1% 16.0 2.6 (1 in 100 years) 0.5% 18.7 3.1 (1 in 200 years)

2.2.2. Hydraulic Modelling

Steady flow models were constructed for Silverstone Brook and Wood Burcote Brook using the HEC-RAS software Version 3.1.3 developed by the U.S. Army Corps of Engineers. The HEC-RAS program was designed to perform one-dimensional hydraulic calculations for a network of natural or constructed channels. The system is comprised of a graphical user interface (GUI), separate hydraulic analysis components, data storage and management capabilities, graphics and reporting facilities.

Cross-sections perpendicular to the brooks were created and inserted into the corresponding models to determine water levels at different locations. Both brooks are heavily vegetated on banks edges, with scattered brush and trees and heavy weeds. Detailed results are included in Appendix E.

2.2.2.1. Silverstone Brook Model

Silverstone Brook is designated as a Main River for 1.6km upstream of its outfall, and therefore this portion falls under the responsibility of the EA for flood control. The EA has a model of Silverstone Brook that covers 1.7km from the confluence with the River Tove, to about 100m upstream of Towcester. The EA model was calibrated using 1998 flood data and concluded that “the Manning’s factors determined using the April 1998 flood were relatively high” (See Appendix D).

EA input into the model

An initial model was set-up by URS and calibrated using predicted water levels provided by the EA for the 1% annual probability (1 in 100 years) flood event for three locations upstream of the Springfields Road bridge (See Appendix D for water levels and Drawing 44406876/10 for locations). This model was set-up for a length of approximately 1.1km along the brook, between the A43 and a point 160m downstream of the footbridge located on site.

After a preliminary review of the URS Silverstone Brook hydraulic model and during a meeting with the EA on 21 st September 2007, the EA suggested that the model be extended at the downstream end to include the bridge over the Springfields Road in

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Towcester. This suggestion was made because it was considered that there were some uncertainties about the EA model covering the Silverstone Brook upstream of the Springfields Road bridge. Since URS did not have detailed survey of the area downstream of the lined channel inlet, the EA provided cross-sections for model extension (See Appendix D, Drawing Siverstone Brook Cross Sections CH 0.870km to CH 1.300km ). URS included two of these cross-sections in the extended model, one at CH 1.200, and one at CH 1.300, and incorporated the portion of the lined channel between station 10 and station 50 (See Drawing 44406876/10 for locations). The EA also asked URS to check the culvert located between stations 1005 and 1100 that URS initially modelled with the upper part uncovered with dirt. During a site visit URS confirmed that the upper part of the culvert is exposed (See Photograph 7 attached).

URS checked the flow values along Silverstone Brook for a catchment outlet at NGR SP 69576 48579 and obtained comparable values to what initially was calculated (See Table 4). Therefore, the flows shown in Table 4 were the ones used in the extended model also. During the review of the initial model, the EA agreed to the flow values used for that model. The Silverstone Brook model details presented below will refer to the extended model.

To determine the flood zones for the 5% annual probability (1 in 20 years), 1% annual probability (1 in 100 years), and 0.5% annual probability (1 in 200 years) events along Silverstone Brook, a hydraulic model was created for a length of approximately 1.4km along the brook, between the A43 and a point 117m downstream of the Springfields Road bridge located in Towcester. Cross-sections perpendicular to the brook were created and inserted into the model to determine water levels at different locations.

The model includes five existing hydraulic structures: the bridge at Springfields Road crossing, the footbridge, two small farmer’s crossings (a concrete slab bridge, and a circular culvert bridge) and the concrete box culvert beneath the A43 Highway (See attached photos).

Due to the lack of topographic survey information on the channel right overbank between the HEC-RAS stations 230 and 40, levees were used as shown on Drawing 44406876/10. The area of interest for the proposed development at these locations is on the right overbank of the channel and it was considered that use of levees on the left overbank would be a conservative approach. Moreover, the available EA data used in model calibration is in this zone.

2.2.2.2. Silverstone Brook Model Calibration

The hydraulic model was calibrated against the EA modelled water levels for the 1% (1 in 100) annual probability flood event. The 1% annual probability (1 in 100 years) flow used by the EA for the Silverstone Brook model was 15.6m3/s. This flow was run in the URS HEC-RAS model to determine water levels that could be compared to those provided by the EA. Calibration of the URS model, based on EA water surface values, led to the selection of a Manning’s roughness coefficient of 0.12 for the natural channel, 0.08 for the over-banks, and 0.035 for the lined channel located towards the model downstream end. Photographs of channel conditions are shown in the attachments. A comparison

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between the URS and the EA water surface levels in the same river area shown in Table 6 and the figure below indicates that there is good agreement between the URS and the EA water levels. During the review of the initial model, the EA agreed to the Manning’s roughness coefficient values of 0.12 and 0.08.

TABLE 6 Comparison Between EA Model and URS Model Water Levels EA Model URS Model Distance Distance Upstream of Water Level Upstream of Water Level Node Station HEC-RAS (mAOD) HEC-RAS (mAOD) Station 10 (m) Station 10 (m)

10 0.0 87.64

20 117.4 87.98

30 129.9 88.01 EA0522181005 136.6 88.03 (468639E, 248077N) 40 267.1 88.33

50 278.0 88.61

100 282.8 88.94

150 319.9 89.07 EA052218104 356.1 89.11 (468504E, 247901N) 200 368.7 89.28

EA052218105 413.5 89.39 210 413.5 89.38 (468450E, 247879N)

220 429.2 89.45

230 483.1 89.57 EA0522181006 487.7 89.65 (468411E, 247821N) 300 534.2 89.73

Note: EA node locations are shown in Drawing 44406876/10

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Comparison Between the Silverstone Brook URS Model and EA Model Water Levels

90.0 89.8 89.6 89.4 89.2 89.0 88.8 88.6 88.4 EA Data 88.2 88.0 URS model

Water Level (mAOD) Water 87.8 87.6 87.4 87.2 87.0

0.0 100.0 200.0 300.0 400.0 500.0 600.0 Distance (m)

2.2.2.3. Silverstone Brook Model Results

A summary of the model results for existing conditions, within the boundaries of the proposed site development, is presented in Table 7. Detailed model results are shown in Appendix E.

TABLE 7 Silverstone Brook HEC-RAS Existing Conditions Model Accounting for Climate Change Summary of Results

Annual Water Surface Elevation (mAOD) Flooded Surface Probability of Area (ha) River Flooding Max Min

5% 92.17 88.14 8.88 (1 in 20 years) 1% 92.25 88.34 9.98 (1 in 100 years) 0.5% 92.28 88.45 10.34 (1 in 200 years)

The results from Table 7 indicate that the increase in the flooded area between the 5% annual probability (1 in 20 years) event and the 1% annual probability (1 in 100 years) event is 12%, and the increase in the flooded area between the 1% annual probability (1 in 100 years) event and the 0.5% annual probability (1 in 200 years) event is 4%.

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2.2.2.4. Wood Burcote Brook Model

In order to determine the flood zones for the 5% annual probability (1 in 20 years), 1% annual probability (1 in 100 years), and 0.5% annual probability (1 in 200 years) events, along Wood Burcote Brook, URS created a hydraulic model for a length of approximately 1.6km along the relevant stretch of the brook. URS did not have detailed survey information of the area north of the site boundary. In order to extend the model further downstream, URS used a 2003 drawing from Woods Warren which covers this area (See Drawing 44406876/12). Although the area presented in this drawing is now residential (not shown in the 2003 drawing), it was considered that information contained in the drawing such as channel details, culvert information, and the general elevation contours could be used for modelling purposes. Moreover, to better estimate the present conditions this drawing was integrated with the available 2006 detail survey information, (See Drawing 44406876/12) and the site was recently visited.

The model includes eight existing hydraulic structures: six culverts (including a length of 70m of the 1200 φ pipe through which Wood Burcote Brook is culverted as it enters Towcester) and two bridges. The 1200 φ pipe located at the model downstream end is equipped with a grille at the inlet to protect it from debris blockage inside (See Photograph 12). Debris from the brook is also retained by another grille located 29m upstream of the pipe inlet (See Photograph 13). Because of the high probability of these grilles to experience debris blockage during flooding, the culvert was modelled as being blocked entirely, and the cross-section at STA 40 (where the upstream grill is located) as being obstructed to the top of the channel. Modelling results indicate that during a flooding event, the water would flood the left channel over-bank and flow downstream through the existing residential area towards Burcote Road (See Photograph 11 of the residential area).

A Manning’s roughness coefficient of 0.12 and 0.08 was used for the channel and the overbanks respectively, between the upstream end of the model and STA 40 as in the case of Silverstone Brook (See Drawing 44406876/11 for station locations).

A Manning’s roughness coefficient of 0.08 and 0.03 was used for the channel and the overbanks respectively, between STA 40 and the 1200φ pipe inlet at the downstream end of the model. Detailed model results are presented in Appendix E.

Due to the lack of topographic survey information on the channel right overbank between the HEC-RAS stations 300 and 40, levees were used as shown on Drawing 44406876/11. The area of interest for the proposed development at these locations is on the right overbank of the channel and it was considered that use of levees on the left overbank would be a conservative approach.

2.2.2.5. Wood Burcote Brook Model Results

A summary of the model results for existing conditions, and within the boundaries of the proposed site development, is presented in Table 8. Detailed model results are presented in Appendix E and Drawings 44406876/11 and 44406876/12.

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TABLE 8 Wood Burcote Brook HEC-RAS Existing Conditions Model Accounting for Climate Change Summary of Results

Annual Water Surface Elevation (mAOD) Flooded Surface Probability of Area (ha) River Flooding Max Min

5% 112.69 92.36 0.58 (1 in 20 years) 1% 112.78 92.42 0.74 (1 in 100 years) 0.5% 112.82 92.46 0.83 (1 in 200 years)

Table 8 shows that the increase in the flooded area between the 5% annual probability (1in 20 years) event and the 1% annual probability (1 in 100 years) event is 27%, and the increase in the flooded area between the 1% annual probability (1 in 100 years) event and the 0.5% annual probability (1 in 200 years) event is 12%.

2.3. Risk of Flooding from Land

Factors influencing the amount of runoff from the site include the area of extent and the nature of the surface. The site is a farmland area which extends to 202.3ha located within three natural drainage areas: one draining to Silverstone Brook (Area 1), one draining to Wood Burcote Brook (Area 2), and one draining east towards the A5 (Area 3) (See Drawing 44406876/09). Based on topography at the site, the overland flow would currently be expected to naturally discharge to Silverstone Brook, Wood Burcote Brook and towards the A5, as shown in Drawing 44406876/09. Therefore it is considered that the risk of flooding, under existing conditions, within Zone 1 (Low Probability) and Zone 2 (Medium Probability) at the site is low as the runoff would discharge towards the Zone 3a floodplains along Silverstone Brook and Wood Burcote Brook.

The EA was consulted during a meeting on 2 nd November 2006 with regard to the calculation methodology for greenfield discharge rates and it was agreed that the IOH 124 method be used.

2.3.1. Greenfield Runoff Rates

The greenfield runoff rates for annual average, 1-, 30-, and 100-year return periods were calculated for the site using the WinDes program, with the Interim Code of Practice (ICP) Sustainable Drainage Systems (SUDS) approach. These return periods were selected based on the ICP for Sustainable Drainage Systems recommendation for calculation of peak rates and runoff from greenfield sites.

The results are presented in Table 9 and program outputs in Appendix F.

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TABLE 9 Return Period Greenfield Runoff Rates (l/s) Based on ICP SUDS Method

Return Period Area 1 Area 2 Area 3 QBAR 270.6 425.8 137.5 1 235.4 370.5 119.6 30 650.1 1,023.1 330.4 100 963.3 1,516.0 489.5 Notes: 1. QBAR – Arithmetic mean annual maximum flood 2. Area 1=63.2ha, Area 2=105.2ha, Area 3=31.3ha

2.3.2. Greenfield Volumes

The EA was consulted during a meeting on 2 nd November 2006 with regard to the calculation methodology for greenfield discharge rates and it was agreed that the IOH 124 method be used.

For this report, the volumes of runoff from the undeveloped site during a storm event of 360minutes duration and 100-year return period were calculated using the WinDes program. The storm event return period and duration was selected based on the ICP recommendation. The results are presented in Table 10 and program outputs in Appendix F.

TABLE 10 Return Period Greenfield Runoff Volumes (m 3)

Return Period Area 1 Area 2 Area 3 100 17,799.6 29,671.9 8,789.0 Notes: 1. Area 1=63.2ha, Area 2=105.2ha, Area 3=31.3ha

2.4. Risk of Flooding from Groundwater

URS is not aware of records of groundwater flooding at the site. As indicated in Section 1.4.4, during a site investigation carried out in March 2007, URS recorded groundwater levels between 0.85m bgl and 1.6m bgl. It can be estimated that the groundwater levels will vary based on the water elevations in the two brooks at the site and subject to groundwater migration from other sources such as minor aquifers or springs. Based on topographic conditions, the risk of groundwater flooding of the areas planned for residential development at the site is not considered significant. However, a detailed geotechnical investigation would be required to fully assess the risk of groundwater flooding at the site.

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2.5. Probability of Site Flooding

The main potential source of flooding at the site is fluvial flooding. The cause of this type of flooding will be exceedance of the flow capacity of Silverstone Brook and Wood Burcote Brook, typically associated with heavy rainfall events. The site is not considered to be at significant risk from groundwater flooding, as the initial site investigation results indicate groundwater to be struck at 0.85m bgl and 1.6m bgl.

2.6. Climate Change Adjustment for Peak River Flows

The effects of climate change on the flooding at the site were analysed as directed by the PPS25 guidelines. Thus a 20% increase was applied to the peak flows to account for potential effects of climate change. According to PPS25 it is estimated that this increase would cover a time period up to year 2115. The increased flows, as shown in Section 2.2.1, were then used in the HEC-RAS analyses to comparatively determine the increase in water levels relative to the existing condition levels for each of the annual probabilities considered. Table 11 and Figures 1, 2 and 3 attached show the results for Silverstone Brook. These results indicate that the effect of climate change on flood levels at this location would not be significant for the site. Drawing 44406876/10 shows the extent of flooding for the 5% annual probability (1 in 20 years), 1% annual probability (1 in 100 years), and 0.5% annual probability (1 in 200 years) storm events at the site.

TABLE 11 Silverstone Brook HEC-RAS Model Summary of Results the Portions of the Brook Inside the Proposed Development Boundaries Excluding the Flood Compensation Area (STA 40 to STA 1800) Difference in Water Levels Between Climate Flooded Surface Areas (ha) Annual Change Conditions and Existing Conditions Probability of Maximum Minimum Average Climate Existing River Flooding Water Level Water Level Water Level Change Difference Conditions Difference Difference Difference Conditions 5% 0.25 0.02 0.05 8.88 8.47 0.41 (1 in 20 years) 1% 0.11 0.04 0.05 9.98 9.52 0.46 (1 in 100 years) 0.5% 0.12 0.04 0.05 10.34 9.92 0.42 (1 in 200 years)

The results from Table 11 indicate that for the existing conditions (with no climate change adjustment) during the 1% annual probability (1 in 100 years) event the site is flooded over an area of 9.52ha along Silverstone Brook, approximately 5% less than the 10ha shown on the EA indicative flood map.

Table 12 and Figures 4, 5 and 6 attached show the results for Wood Burcote Brook. These results indicate that the effect of climate change on flood levels at this location would not be significant for the site. Drawing 44406876/11 shows the extent of flooding

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for the 5% annual probability (1 in 20 years), 1% annual probability (1 in 100 years), and 0.5% annual probability (1 in 200 years) storm events at the site.

TABLE 12 Wood Burcote Brook HEC-RAS Model Summary of Results for the Portions of the Brook Inside the Proposed Development Boundaries (STA 50 to STA 700 and STA 1700 to STA 2400) Difference in Water Levels Between Climate Flooded Surface Areas (ha) Annual Change Conditions and Existing Conditions (m) Probability of Maximum Minimum Average Water Climate Existing River Flooding Water Level Water Level Level Change Difference Conditions Difference Difference Difference Conditions 5% 0.12 0.02 0.06 0.58 0.49 0.09 (1 in 20 years) 1% 0.11 0.03 0.06 0.74 0.66 0.08 (1 in 100 years) 0.5% 0.12 0.02 0.07 0.83 0.74 0.09 (1 in 200 years)

3. DEVELOPMENT PROPOSAL

3.1. Development Layout Details

The proposed development comprises a mixed-use scheme covering the site area. The scheme will include 3,000 residential units in addition to up to 21 hectares of employment land with retail, education and community facilities, and over 50 hectares of open space. The scheme will also include the provision of a bypass joining the A5 and the A43 to the south of the site.

The scheme layout is shown in the Masterplan Drawing 44406876/02.

3.2. Proposed Development within the Floodplain

The Bypass Road for the A43 access and the Spine Road for the MU1 Parcel access involves crossing Silverstone Brook and Wood Burcote Brook. These roads are partly located within the 1% (1 in 100) annual probability floodplain and therefore, URS has assessed the hydraulic impact on the floodplain extent in these areas.

3.2.1. Channel Diversion

The proposed bypass road involves construction of a roundabout over the existing Silverstone Brook. URS investigated a few options on how to accommodate this bypass scheme over the brook and it was concluded that a diversion of the existing stream would be the best solution. Therefore it is proposed that a portion of 250m of the brook be diverted to the southeast. The EA did not raise any objection to this proposal during a meeting held on 21 September 2007. The new diversion will be a 280m long two-stage channel (a combination of a main channel and overflow channel). To cope with multiple storm events, the channel cross-section will be composed of a lower section designed to

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carry the frequent flows as well as the peak annual flow, and an overflow section sized to convey major events such as the 1% annual probability (1 in 100 years) flow. The bypass will cross the channel over a bridge with a 10m span. South of the bypass the two-stage channel will be located in the area used for flood compensation. The compensation area will provide significant detention storage volume during major storm events, ensuring that the water levels for post development and existing conditions are similar. In addition, the main channel overbanks will be used for farming and gently sloped towards the main channel.

North of the bypass the channel will flow through an area that will be bordered to the east by the proposed development and to the west by the on/off roundabout ramp (See Drawing 44406876/13).

It is proposed that the low flow channel have a bottom width of 1m, depth of 1.3m, and side slopes of 1V:2H. The overbank areas, which are part of the overflow channel, will be wide and slightly sloped towards the main channel. The side slopes on the left side will remained unchanged since this area borders the A43, whereas the side slopes on the left side will be 1V:4H. The main channel does not require a freeboard, but the overbank areas will require a minimum of 0.3m of freeboard (Cross Section Details for existing and post development ground levels are shown in Appendix G).

3.2.2. Silverstone Brook Road Crossings

The development proposal includes the Bypass for the A43 highway access and the Spine Road for MU1 parcel access. This scheme involves crossing Silverstone Brook at two locations. The proposal is for a bridge for the bypass, which will have to accommodate a footpath running approximately parallel to the brook on the right overbank. Future Spine Road crossing hydraulic structure will be selected at a later date when more detail planning will cover this aspect. For post development hydraulic analyses, it was conservatively assumed that the brook would flow underneath the Spine Road through a structure with a 6m span (See Drawing 44406876/13). Also, in the modelling it was assumed that the two small farmer’s crossings, the concrete slab bridge, and the circular culvert bridge would be removed during the development.

Hydraulic analyses were performed using HEC-RAS modelling to determine the optimum dimensions of the hydraulic structures (rise and span) required for the two road crossings, ensuring that water levels for the 1% annual probability (1 in 100 years) event, upstream and downstream of the structures, would not be significantly different than those of existing conditions for the same return period.

The flows used in analyses were adjusted to take into account possible effects of climate change. Structure characteristics are presented in Table 13 and locations are shown in Drawing 44406876/13. Modelling results are shown in Appendix G.

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TABLE 13 Hydraulic Structure Dimensions for the Silverstone Brook Crossings Upstream Upstream Total Span Hydraulic Channel Cross-Section Footpath Berm Cross-Section 1 (m) Structure Width (m) Channel Width (m) Width (m) Rise 2 (m) Depth (m) Bypass 6.0 1.3 3.5 0.5 10.0 6.7 Bridge Spine Road 6.0 1.6 N/A 3 N/A 6.0 2.5 Structure Notes: 1. The berm width is under the bridge, on the left side of the channel looking downstream 2. The rise is measured from the footpath elevation to the bridge soffit. The rise values indicated in the table may change, as the road elevations will be set in the final design. Selection of these values was based on available data as to date, and general design guidelines. However, the rise will be sufficient to allow safe passage of the 1% annual probability (1 in 100 years) flow. 3. At this location the footpath will cross over the road.

Water level profiles generated for the 5% annual probability (1 in 20 years) and 1% annual probability (1 in 100 years) events for existing and post-development conditions show very small changes along Silverstone Brook between the downstream end of the HEC-RAS model and station 1500. Comparisons of these levels along this section of the brook are shown in Figures 7 and 8. Because of the planned channel diversion upstream of station 1500, the existing channel alignment will be different than the future one (See Section 3.2.1 for more details). Water level comparisons for locations upstream of station 1500 are shown in Appendix G. The variations in ground levels shown in the figures are at of the planned Spine Road Crossing.

3.2.3. Wood Burcote Brook Road Crossings

The new The Bypass Road and the Spine Road will also cross Wood Burcote Brook. In addition, the brook will be crossed at a location downstream that would connect the new development to the existing Burcote Road (See Drawing 44406876/02). The Bypass Road crossing will have to accommodate a footpath on the left Wood Burcote Brook overbank. For this model none of the existing hydraulic structures were assumed to be removed during the development.

Hydraulic analyses were performed to determine the size of the bridge (rise and span) required for the Bypass Road crossing that could accommodate the footpath and ensure that water levels for the 1% annual probability (1 in 100 years) event, upstream and downstream of the bridge, would not be significantly different than those of existing conditions for the same return period.

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The Spine Road and the Burcote Access Road crossings could be done over concrete box culverts.

The dimensions for the hydraulic structures were selected based on HEC-RAS sensitivity analyses and the results are presented in Table 14. Bridge and culvert locations are shown in Drawing 44406876/02 and modelling results are shown in Appendix G.

TABLE 14 Hydraulic Structure Dimensions at the Upstream Cross-Sections for the Wood Burcote Brook Crossings Upstream Upstream

Cross- 1 Total Span Cross- Hydraulic Channel Footpath Berm Width Section Structure Width (m) Width (m) (m) (m) Section Channel Rise 2 (m) Depth (m) Bypass 3.0 0.9 3.5 0.5 7.0 5.0 Bridge Spine Road N/A N/A N/A N/A 4.0 1.5 Box Culvert Access Road N/A N/A N/A N/A 4.0 1.5 Box Culvert Notes: 1. The berm width is under the bridge, on the right side of the channel looking downstream. 2. The rise is measured from the footpath elevation to the bridge soffit. The rise values indicated in the table may change, as the road elevations will be set in the final design. Selection of these values was based on available data as to date, and general design guidelines. However, the rise will be sufficient to allow safe passage of the 1% annual probability (1 in 100 years) flow.

Water level profiles generated for the 5% annual probability (1 in 20 years) and 1% annual probability (1 in 100 years) events for existing and development conditions, show very small changes along the entire modelled stretch of Wood Burcote Brook. Comparisons of these levels along the entire brook are presented in Figures 9 and 10.

3.2.4. Flood Storage Compensation

Development and Flood Risk: A Practice Guide Companion to PPS25 ‘Living Draft’ (Feb 2007 ) stipulates that: Unless the development is located in an area which is subject to tidal flooding and which serves no conveyance function, land raising must be accompanied by compensatory provision of flood storage either on- or off-site. (5.28). The site has two areas along Silverstone Brook and three areas along Wood Burcote brook that could be considered ‘’land raising’’ within the 1% annual probability (1 in 100 years) event flood plains. The new development scheme will involve construction of the

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Bypass Road connecting the development to the A5 and to the A43, the Spine Road connecting the development to the Bypass Road, and an Access Road connecting the new community to the Burcote Road (See Drawing 4446876/02). These new roads will involve land raising and thus require flood compensation.

3.2.4.1. Silverstone Brook Scheme

Silverstone Brook Scheme involves river crossing at two locations (See Drawing 4446876/13). It is proposed that the flood compensation area be located adjacent to Silverstone Brook, south of the bypass road scheme. The area required for flood compensation must ensure that the water levels for the post development conditions must not be significantly different from the existing conditions. Modelling results showing water levels for before and after development conditions are presented in Appendix G.

3.2.4.2. Wood Burcote Brook Scheme

As shown in Drawing 4446876/11 the extent of the flood area along Wood Burcote Brook is very small compared to the flood area along Silverstone Brook. Also, hydraulic analyses indicate that for the 1% annual probability (1 in 100 years) flood event, the water levels for existing and development conditions are not significantly different (See Section 3.2). It is therefore considered that storage compensation would not be needed for this scheme.

4. POST-DEVELOPMENT FLOOD RISK

4.1. Surface Water Drainage Strategy

4.1.1. General Policy Guidelines

The Proposed Development site will be subject to urbanisation resulting in an increase of impermeable surfaces across the site. Due to the increase in impermeable surface area, the developed site surface water runoff will be greater and faster than for the existing greenfield site. This can result in increased frequencies of bankfull flows causing scour and erosion that would affect the morphology and ecology of the streams. It can also increase flood risk downstream. PPS25 and the EA guidelines require that the proposed development surface water runoff rates into a watercourse mimic the existing site greenfield runoff rates for a range of annual probabilities of up to 1% (1in 100 years). The EA also requires that the total discharged runoff volume from the developed site match (or reduce where possible) the greenfield equivalent volume. The reasons for this are: 1) The water volumes available for infiltration into the ground should be unchanged in order to maintain the level of aquifer recharge and sustain watercourse baseflows; 2) Reduce pollutant loads from the small frequent runoff events to the receiving system; and 3) Maintain or reduce the flood levels in case of extreme events in the receiving watercourses.

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This section outlines the proposed mitigation measures to control the surface water discharge flows and volumes from the site using SUDS to mimic, as far as practicable, the natural drainage patterns.

4.1.2. Selection of SUDS

Implementation of SUDS for new developments is generally viewed as potentially more beneficial than the conventional drainage systems for a number of reasons such as: 1) better control of water discharge rates and volumes; 2) water quality improvement via filtration and sedimentation of pollutants; 3) recharge of aquifers; 4) amenity improvement and facilitation of wildlife habitat. A range of SUDS components available for use on new developments are listed below.

• Preventive measures – Rainwater harvesting systems, alternative roofs (e.g. green roofs);

• Pervious surfaces – Surfaces that facilitate rainwater inflow into the underlying construction (e.g. solid paving blocks with gaps between the individual units);

• Green roofs – Vegetated roofs that reduce the rate and volume of runoff;

• Filter strips – Vegetated areas on gentle slopes designed to drain water evenly off impermeable areas and to filter out silt;

• Swales – Shallow vegetated channels that convey and retain water, and may also permit infiltration;

• Basins, ponds and wetland – Areas that can be used for surface water runoff storage;

• Soakaways – Drainage structures that store surface water allowing gradual infiltration into the surrounding soil;

• Geocellular/modular systems – Modular plastic geocellular systems with a high void ratio that can be used to create a below ground infiltration (soakaway) or storage structure.

At this stage a detailed geotechnical investigation containing soil and groundwater contamination testing and permeability testing for the whole site has not been undertaken. Therefore, the use of soakaways for various locations within the site would require further testing. At a meeting with URS on 2nd November 2006, the EA indicated that soakaways at the site would be acceptable as long as they were not more than 2m deep and sufficiently far above the unsaturated zone. A hand auger borehole investigation performed by URS in March 2007 indicates that SUDS using infiltration as an outfall would be restricted within this development because of high water tables and cohesive strata below the surface at the site.

URS opted, in consultation with the master planners, for balancing ponds, basins, swales and underground storage to be used for this development. The purpose of the balancing

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basins/ponds is to control the surface flows before their transfer downstream by using a storage volume and a constrained outlet, such as a Complex Control using a combination of flow restrictors at different elevations to simulate 1-, 30-, and 100-year return period greenfield flows. Storage structure locations at the site were selected based on CIRIA’s recommendation that wherever possible the storm water should be managed within small sub-catchments rather than being conveyed to and managed in large systems at the bottom of the drainage areas.

Basins/ponds 1 were designed in accordance with guidelines presented in the Interim Code of Practice for Sustainable Drainage Systems (ICP) , and The SUDS Manual (CIRIA C697).

The following percentile impermeable areas shown below were assumed from each land usage. Changes to the assumed percentile impermeable areas indicated below or to the size of any land use shown in the development master plan will affect basin/ pond storage requirements:

Land Use Percentile Impermeable

• High Density Housing (50dph): 80%

• Medium Density Housing (38dph) 70%

• Low Density Housing (30dph) 60%

• Mixed Use 85%

• Employment 85%

• Education 65%

• Highways 60%

Rainfall intensities used in SUDS calculations were increased in accordance with recommended national precautionary sensitivity ranges for peak rainfall intensities within Table B.2 of PPS25 over the expected life span of the respective land uses.

The use of underground storage systems such as permeable paving, cellular storage or tanks within commercial or educational land uses may be used subject to final layout designs and associated costs.

The location and extent of basins/ponds is shown on Drawing 44406876/02.

1 Basin: A bowl type storage structure that attenuates surface water runoff during extreme storm events but will predominantly remains dry throughout the year.

Pond: A bowl type structure that attenuates surface water runoff during extreme storm events and will have a permanent water level.

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4.1.3. Maintenance of SUDS

It is essential that the SUDS components be maintained on a regular basis to ensure that they function properly and avoid localised flooding of the site. Adoption and maintenance of the flood mitigation works and SUDS, and any private drainage must be arranged by negotiation and agreement between the developer and a suitable maintenance authority, e.g. South Northamptonshire District Council.

4.2. Risk of Flooding from Rivers

The various parcel uses within the proposed development site were allocated considering the flood zones as presented in Annex D of PPS25, and the SUDS locations. All developments, except for segments of the A43 Bypass and Spine Road access routes, have been sited within Flood Zone 1-Low Probability and Zone 2-Medium Probability.

4.3. Risk of Flooding from Land

Existing risk of flooding from land, as discussed in Section 2.3 is not considered significant. Development of the site, using the proposed surface water drainage strategy will not increase the existing flood risk at the site or elsewhere as long as the drainage system functions properly. Therefore it is very important that the SUDS are inspected and maintained on a regular basis. Storage structures are generally located below residential development areas and site topography below these structures would allow stormwater runoff, in the event of a storage structure failure, to flow towards the respective outfall locations and away from the residential dwellings.

4.4. Risk of Flooding from Groundwater

Existing risk of groundwater flooding as discussed in Section 2.4 is not considered significant. Based on the nature of the development, it is estimated that the proposal should not increase the risk of groundwater flooding at the site or elsewhere.

4.5. Residual Flood Risk

A small residual flood risk would remain after implementation of the proposed surface water drainage strategy if good maintenance practices are not followed and in the event of a storm in excess of the 1% (1 in 100) annual probability storm event.

5. SUMMARY AND CONCLUSIONS

The EA flood zone map for Towcester indicates that approximately 10ha of the site (excluding the site compensation area) is located in Zone 3a (High Probability) along Silverstone Brook. The remainder of the site lies within Zone 1 (Low Probability), except some small areas along Silverstone Brook on the northern part of the site, which are located in Zone 2 (Medium Probability). “More Vulnerable”, “Less Vulnerable” and “Water Compatible” land uses are all appropriate within Flood Zones 1 and 2.

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To more accurately define the flood zones at the site, URS has created HEC-RAS models for the relevant stretches of the two brooks crossing the site. River modelling results show that within the site boundaries for the 5% annual probability (1 in 20 years) flood event with climate change adjustment, an area of 8.88 ha would be flooded along Silverstone Brook, and an area of 0.58ha would be flooded along Wood Burcote Brook. For the 1% annual probability (1 in 100 years) flood event with climate change adjustment, an area of 9.98ha would be flooded along Silverstone Brook, and an area of 0.74ha would be flooded along Wood Burcote Brook.

For the existing conditions (with no climate change adjustment) during the 1% annual probability (1 in 100 years) event the site is flooded over an area of 9.52ha, along Silverstone Brook, approximately 5% less than the 10ha shown on the EA indicative flood map.

Development of this site using on site attenuation would not increase either the existing surface water runoff or volume from the site, and therefore would not increase flood risk elsewhere.

A number of opportunities are available for the use of SUDS within the development proposal. The proposed development site was assessed for preliminary design purposes as 80% impermeable in the high-density housing areas, 70% impermeable in the medium density housing areas, 60% impermeable in the low-density housing areas, 85% impermeable in the mixed use and employment areas, 65% impermeable in the education areas and 60% impermeable in the highway areas. Rainfall intensities used in WinDes calculations were increased by 20% for commercial and industrial land use areas, and 30% for residential land use areas to allow for climate change.

Development of the site calls for construction of a bypass road on the south connecting the site to the A43 and the A5, and Spine Road and two Access Roads within the site. This scheme involves raising of land in the flood area along Silverstone Brook requiring flood compensation. The compensatory area will be provided south of the bypass road and will ensure that water levels for flood events up to and including the 1% annual probability (1 in 100 years) event are not significantly different from the existing conditions. Because of the small extent of Zone 3a along Wood Burcote Brook, compensatory provision will not be required in this area of development. These evaluations were done accounting for possible effects of climate change.

The bypass scheme will involve construction of a roundabout over the existing Silverstone Brook. This plan will require diversion of 250m of the existing channel to the southeast. The EA did not raised objections to this proposal during a meeting held on 21 st September 2007. It is proposed that the new diversion be a 280m long two-stage channel designed to cope with multiple storm events including the 1% annual probability (1 in 100 years) flow. South of the bypass the two-stage channel will be located in the area used for flood compensation. The compensation area will provide significant detention storage volume during major storm events, ensuring that the water levels for post development and existing conditions are similar. In addition, the main channel overbanks will be used for farming and gently sloped towards the main channel.

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Appendix A - Compliance with PPS25 Guidelines

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Relevant Policy in PPS25

PPS 25 provides policy for planners in the preparation of local development documents; a supporting Practice Guide provides guidance on the implementation of the policies set out in PPS 25. The policy and guidance relevant to the Towcester Site is as follows:

A 1 . Development description and location

A 1a. What type of development is proposed and where will it be located?

The site will be developed to comprise 3,000 residential units in addition to up to 21 hectares of employment land with retail, education and community facilities and over 50 hectares of open space.

The site lies to the south of Towcester in Northamptonshire, centred at National Grid Reference (NGR) SP 696 468. The site comprises some 202.3ha of open farmland, and is bordered by the A43 to the west, by housing development to the north, by the A5 to the east, and by farmland to the south. The site is crescent shaped with curved edges bordering the housing to the north and farmland to the south, about 3km long, and 0.5km wide.

A 1b. What is its vulnerability classification?

The majority of the development would be classified as "More Vulnerable" since there will be buildings used for dwelling houses, drinking establishments, nightclubs and hotels. In addition, non-residential buildings used for health services, nurseries and educational establishments are planned.

A smaller portion of the development would be classified as "Less Vulnerable" since there will be buildings used for shops, financial, professional and other services, restaurants and cafes, hot food takeaways, offices, general industry, storage and distribution and assembly and leisure facilities.

A minor portion of the development would be classified as "Water Compatible Development" since the area will be used for flood control infrastructure, water transmission infrastructure and pumping stations, sewage transmission infrastructure and pumping stations, amenity open space, nature conservation and biodiversity and outdoor sports and recreation.

A 1c. Is the proposed development consistent with the Local Development Documents?

The South Northamptonshire Local Plan (Oct 1997) is the current Local Development Document for the scheme area. This document does not directly address the Towcester Vale residential, educational, commercial and open space development; but it does contain policies within Chapter 2: Housing and in Chapter 4: Environment that address housing and flooding considerations such as:

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Policy H7 states: Where there is a demonstrable lack of affordable housing for sale or rent to meet local needs, the Council will negotiate with developers to secure an element of affordable housing within large residential development schemes. The council will need to be satisfied that such affordable housing: (i) is economically viable in terms of its ability to meet the local needs identified; (ii) will be available to meet local needs over the long term through secure arrangements being made to restrict the occupancy of the development.

Policy H10 states: Proposals for residential development will, where appropriate, be expected to provide a variety of densities and dwelling types.

Policy EV26 states: Planning permission will normally be granted for new development providing:- (i) it is not located in an area at risk from flooding; or (ii) it is not likely to materially impede the flow of flood water; or (iii) it will not increase the risk of flooding elsewhere; or (iv) it will not result in problems due to additional surface water run-off. Where occasionally development is permitted in areas at risk from flooding or likely to result in flooding elsewhere appropriate flood prevention measures will be required.

West Northamptonshire Development Corporation (WNDC) was set up by the Office of the Deputy Prime Minister (ODPM, now the Department for Communities and Local Government - DCLG) in December 2004 to deliver sustainable regeneration and growth in the West Northamptonshire towns of Northampton, Daventry and Towcester.

The WNDC Corporate Plan: April 2006 - March 2008 defines the Towcester Urban Development Area (UDA) which encompasses Towcester town centre, built-up area and potential urban extensions - including the area which is proposed for the Towcester Vale development.

Paragraph 1.3 of the WNDC Corporate Plan states: As current and planned development patterns indicate, there are major opportunities for boosting the economic strength of Northampton and neighbouring centres in Daventry and Towcester. There is scope to create an enhanced urban environment and improve public infrastructure through regeneration and high quality design focusing on a series of town centre and urban fringe sites. Successful regeneration of these centres would enhance the development of sustainable and viable local communities able to accommodate proposed levels of growth. It would also recognise the key sub-regional links between Northampton, South Northamptonshire and Daventry Districts.

Paragraph 3.3.1.6 states: The rejuvenation of Towcester’s town centre is an identified priority for South Northamptonshire District Council. Moat Lane, running parallel to Towcester’s historic Watling Street, with a riverside location and a heritage site in Bury Mount, provides an excellent opportunity to improve the town’s overall retail, leisure and employment offer. During this Corporate Plan period, WNDC will continue to work with the District Council to develop and invest GAF2 in a project that maximises the potential in this site. Additionally, WNDC will work with the Council to:

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• Identify development opportunities within the built-up area, such as at the ex-Plessey site identified in South Northamptonshire Council’s urban capacity study • Identify priorities for the potential development of land within the Urban Development Area south of Towcester, and for a potential bypass to the A5 which currently runs through the High Street, and the impact these would have on the town centre

A 1d. Please provide evidence that the Sequential Test or Exception Test has been applied in the selection of this site for this development type.

Development classified as “More Vulnerable” and “Less Vulnerable” is located on 94.4% of the development site, which is also in Flood Zone 1. These land uses are appropriate in these zones per PPS25 Table D.1: Flood Zones , therefore the Sequential Test and the Exception Test are not required for the developments located in these zones.

A 2. Definition of the flood hazard

A 2a. What sources of flooding could affect the site?

Flooding from rivers, the land and groundwater are the potential sources of flooding at the Towcester Vale development.

A 2b. For each identified source, describe how flooding would occur, with reference to any historic records wherever these are available.

Risk of Flooding from Rivers

The Towcester Vale development is at risk of river flooding by Silverstone Brook and Wood Burcote Brook. The assessment method for the fluvial flood risk at the site has been carried out in two stages:

Stage 1: Calculation of Flood Flows

Stage 2: Assessment of Flooding.

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Two site-specific hydraulic models, one of Silverstone Brook, and one of Wood Burcote Brook, were constructed using HEC-RAS, Version 3.1.1. to assess the risk of flooding. Site specific topographic and structure information was obtained from surveys carried out by Milton Keynes Ltd. in 2006 for most of the site, and URS in 2007 for an area of approximately 4.6ha downstream of the A43 and Silverstone Brook junction.

Hydraulic Modelling

Steady flow models were constructed for Silverstone Brook and Wood Burcote Brook using the HEC-RAS software Version 3.1.3 developed by the U.S. Army Corps of Engineers.

The HEC-RAS program was designed to perform one-dimensional hydraulic calculations for a network of natural or constructed channels. The system is comprised of a graphical user interface (GUI), separate hydraulic analysis components, data storage and management capabilities, graphics and reporting facilities.

Risk of Flooding from Land

Factors influencing the amount of runoff from the site include the area of extent and the nature of the surface. The site is a farmland area which extends to 202.3ha located within three natural drainage areas: one draining to Silverstone Brook (Area 1), one draining to Wood Burcote Brook (Area 2), and one draining east towards the A5 (Area 3) (Drawing 44406876/09). Based on topography at the site, the overland flow would currently be expected to naturally discharge to Silverstone Brook, Wood Burcote Brook and towards the A5, as shown in Drawing 44406876/09. Therefore it is considered that the risk of flooding, under existing conditions, within Zone 1 (Low Probability) and Zone 2 (Medium Probability) at the site is low as the runoff would discharge towards the Zone 3a floodplains along Silverstone Brook and Wood Burcote Brook.

Risk of Flooding from Groundwater

URS is not aware of records of groundwater flooding at the site. As indicated in Section 1.4.4 of the FRA during a site investigation carried out in March 2007, URS recorded groundwater levels between 0.85m bgl and 1.6m bgl. It can be estimated that the groundwater levels will vary based on the water elevations in the two brooks at the site and subject to groundwater migration from other sources such as minor aquifers or springs. Based on topographic conditions, the risk of groundwater flooding of the areas planned for residential development at the site is not considered significant. However, a detailed geotechnical investigation would be required to fully assess the risk of groundwater flooding at the site.

A 2c. What are the existing surface water drainage arrangements for the site?

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Surface water runoff from the existing farmland site surface drains to Silverstone Brook, Wood Burcote Brook and towards the A5.

A 3. Probability

A 3a. Which flood zone is the site within?

The current EA indicative flood map for Towcester shows that approximately 10ha of the site is located in Zone 3a (High Probability) along Silverstone Brook. The rest of the site lies within Zone 1 (Low Probability), except some small areas along Silverstone Brook on the northern part of the site, which are located in Zone 2 (Medium Probability). To more accurately define the flood zones at the site, URS has created HEC-RAS models for the relevant stretches of the two brooks crossing the site, using recent topography.

A 3b. If there is a Strategic Flood Risk Assessment covering this site, what does it show?

Investigations by URS determined that South Northamptonshire Council has not completed a Strategic Flood Risk Assessment for the area at the time of this report.

A 3c. What is the probability of the site flooding taking account of the contents of the SFRA and of any further site-specific assessment?

Based on the site specific assessment and river modelling, the probability that the developments nearest Silverstone Brook or Wood Burcote Brook would flood is very Low to Negligible.

A 3d. What are the existing rates and volumes of run-off generated by the site?

Greenfield Runoff Rates

The greenfield runoff rates for annual average, 1-, 30-, and 100-year return periods were calculated for the site using the WinDes program, with the Interim Code of Practice (ICP) Sustainable drainage Systems (SUDS) approach. These return periods were selected based on the (ICP) for Sustainable Drainage Systems recommendation for calculation of peak rates and runoff from greenfield sites. The results are presented in the table below and program outputs in Appendix F.

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Return Period Greenfield Runoff Rates (l/s) Based on ICP SUDS Method

Return Area 1 Area 2 Area 3 Period QBAR 270.6 425.8 137.5 1 235.4 370.5 119.6 30 650.1 1,023.1 330.4 100 963.3 1,516.0 489.5 Notes: 3. QBAR – Arithmetic mean annual maximum flood 4. Area 1=63.2ha, Area 2=105.2ha, Area 3=31.3ha

Greenfield Volumes

The volumes of runoff from the undeveloped site during a storm event of 360minutes duration and 100-year return period were calculated using the WinDes program. The storm event return period and duration was selected based on the ICP recommendation. The results are presented in the table below and program outputs in Appendix F.

Return Period Greenfield Runoff Volumes (m 3)

Return Area 1 Area 2 Area 3 Period 100 17,799.6 29,671.9 8,789.0 Notes: 2. Area 1=63.2ha, Area 2=105.2ha, Area 3=31.3ha

A 4. Climate Change

A 4a. How is flood risk at the site likely to be affected by climate change?

River flood levels for Silverstone Brook and Wood Burcote Brook would rise due to increased rainfall intensities as a result of climate change. The HEC-RAS model of these rivers was created and peak river flows were increased by 20%, as specified in PPS25, Annex B, Table B2: Recommended national precautionary sensitivity ranges for peak rainfall intensities, peak river flows, offshore wind speeds and wave heights , to allow for climate change.

The effects of climate change have also been accounted for in the WinDes drainage software, which was used to model the maximum storage requirements for the site. Rainfall intensities used in WinDes calculations were increased by 20% for commercial and industrial land use areas, and 30% for residential land use areas to allow for climate change. This is in accordance with recommended national precautionary sensitivity

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ranges for peak rainfall intensities within Table B.2 of PPS25 over the expected life span of the respective land uses.

A 5. Detailed development proposals

A5 a. Please provide details of the development layout, referring to relevant drawings.

The site will be developed to comprise 3,000 residential units in addition to up to 21 hectares of employment land with retail, education and community facilities and over 50 hectares of open space. The scheme will also include the provision of a bypass joining the A5 and the A43 to the south of the site, and a Spine Road and two Access Roads within the site (See Drawing 44406876/02)

A 5b. Where appropriate, demonstrate how land-uses most sensitive to flood damage have been placed in areas within the site that are at least risk of flooding.

The Towcester Vale development buildings are located so that the sources of flooding will not affect the site, as explained in under Item A2 (above), Item A6 (below) and in Section 2.

A 6. Flood risk management measures

A 6a.How will the site be protected from flooding, including the potential impacts of climate change, over the development’s lifetime?

The site does not require flood protection for the developments, as all developments are located above the 1% annual probability (1 in 100 years) flood levels (with climate change adjustment) of Silverstone Brook and Wood Burcote Brook. Therefore, the Towcester Vale development would be at minimal risk from increased flood levels as a result of climate change.

A 7. Off site impacts

A 7a. How will you ensure that your proposed development and the measures to protect your site from flooding will not increase flood risk elsewhere?

The proposed development will include the incorporation of SUDS, which will be designed to reduce the peak runoff rates to the greenfield values, and improve the quality of the surface water runoff at the site.

PPS25 requires that a development mimic the surface water flows arising from the site prior to the proposed development . The PPS25 requirement is typically applied to the 1 in 1 year, 1 in 30 years and the 1 in 100 years probability storm events restricting the surface water discharge of the developed site to its equivalent storm greenfield runoff rate.

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A 7b. How will you prevent run-off from the completed development causing an impact elsewhere?

See Section 4.1 for the surface water drainage strategy of the proposed development implementing SUDS.

A 8. Residual risks

A 8a. What flood-related risks will remain after you have implemented the measures to protect the site from flooding?

A 8b. How, and by whom, will these risks be managed over the lifetime of the development?

In case of emergencies, South Northamptonshire District Council can maintain the surface water drainage system using their permissive powers under the Land Drainage Act.

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Appendix B - Geotechnical Investigation Hand Auger Logs

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HAND AUGER LOG

Project Hole Location HOLE No Towcester EIA/ Flood Risk Assessment, . Job No Date Ground Level (mAOD) Co-ordinates (mOD) HA1 44406876 Mar 7, 07 E 468270 N 247670 Contractor Sheet URS Corporation Ltd. 1 of 1

SAMPLES & TESTS STRATA Type In situ Reduced Depth DESCRIPTION

Depth Tests Water Level Legend (Thick-

No. Geology Instru- ment/ Backfill (Vane) mAOD ness) kN/m2 TOPSOIL- Brown to dark brown sandy clay with fine to medium gravel and occasional rootlets. 0.20 Firm become soft brown orange slightly sandy gravelly CLAY. Sand is fine to medium and gravel consists of fine to coarse angular quartz. (0.50) Gravel absent from 0.5m depth.

0.70 Very soft light brown to brown gravelly CLAY. Gravel consists of 0.85 fine to medium sub - angular quartz. Light brown slightly clayey sandy fine to medium GRAVEL,damp.

1.20

End of Hand Auger at 1.20m

GENERAL REMARKS Groundwater encountered at 0.85m bgl.

All dimensions in metres Client Method Logged Scale 1:20 Persimmon Homes Midlands Ltd Hand Augeringby SP/JS 3/26/07, HANDAUGER, 44406876 EIA.GPJ HAND AUGER LOG

Project Hole Location HOLE No Towcester EIA/ Flood Risk Assessment, . Job No Date Ground Level (mAOD) Co-ordinates (mOD) HA2 44406876 Mar 7, 07 E 468670 N 247720 Contractor Sheet URS Corporation Ltd. 1 of 1

SAMPLES & TESTS STRATA Type In situ Reduced Depth DESCRIPTION

Depth Tests Water Level Legend (Thick-

No. Geology Instru- ment/ Backfill (Vane) mAOD ness) kN/m2 TOPSOIL- Brown to dark brown sandy clay with fine to medium gravel and occasional rootlets. 0.20 Firm brown mottled grey and orange - brown CLAY.

(0.65)

0.85 Firm grey mottled orange - brown CLAY.

1.20 Firm grey highly fissured CLAY .

1.60 Firm grey CLAY.

2.00

End of Hand Auger at 2.00m

GENERAL REMARKS Groundwater encountered at 1.6m bgl.

All dimensions in metres Client Method Logged Scale 1:20 Persimmon Homes Midlands Ltd Hand Augering by SP/JS 3/26/07, HANDAUGER, 44406876 EIA.GPJ HAND AUGER LOG

Project Hole Location HOLE No Towcester EIA/ Flood Risk Assessment, . Job No Date Ground Level (mAOD) Co-ordinates (mOD) HA3 44406876 Mar 7, 07 E 468990 N 247450 Contractor Sheet URS Corporation Ltd. 1 of 1

SAMPLES & TESTS STRATA Type In situ Reduced Depth DESCRIPTION

Depth Tests Water Level Legend (Thick-

No. Geology Instru- ment/ Backfill (Vane) mAOD ness) kN/m2 TOPSOIL - Firm grey to black sandy gravelly clay.

0.25 Weak thinly bedded light brown fine - grained LIMESTONE, highly weathered.

0.50

End of Hand Auger at 0.50m

GENERAL REMARKS Hole stopped at 0.5m, Hard soil strata(Lime stone) found at the depth of completion. No Groundwater encountered.

All dimensions in metres Client Method Logged Scale 1:20 Persimmon Homes Midlands Ltd Hand Augeringby SP/JS 3/26/07, HANDAUGER, 44406876 EIA.GPJ HAND AUGER LOG

Project Hole Location HOLE No Towcester EIA/ Flood Risk Assessment, . Job No Date Ground Level (mAOD) Co-ordinates (mOD) HA4 44406876 Mar 7, 07 E 469360 N 247140 Contractor Sheet URS Corporation Ltd. 1 of 1

SAMPLES & TESTS STRATA Type In situ Reduced Depth DESCRIPTION

Depth Tests Water Level Legend (Thick-

No. Geology Instru- ment/ Backfill (Vane) mAOD ness) kN/m2 TOPSOIL- Brown to dark brown sligtly sandy clay with fine sub-angular gravel.

0.30 Firm to stiff brown CLAY with occasional fine to medium sub-angular gravel and fine to medium gravel size fragments of limestone.

0.70 Firm becoming soft orange-brown CLAY.

(0.80)

1.50

End of Hand Auger at 1.50m

GENERAL REMARKS Groundwater encountered at 1.0m bgl.

All dimensions in metres Client Method Logged Scale 1:20 Persimmon Homes Midlands Ltd Hand Augeringby SP/JS 3/26/07, HANDAUGER, 44406876 EIA.GPJ HAND AUGER LOG

Project Hole Location HOLE No Towcester EIA/ Flood Risk Assessment, . Job No Date Ground Level (mAOD) Co-ordinates (mOD) HA5 44406876 Mar 8, 07 E 469850 N 246880 Contractor Sheet URS Corporation Ltd. 1 of 1

SAMPLES & TESTS STRATA Type In situ Reduced Depth DESCRIPTION

Depth Tests Water Level Legend (Thick-

No. Geology Instru- ment/ Backfill (Vane) mAOD ness) kN/m2 TOPSOIL:Brown to dark brown sandy clay with occasional fine sub - angular gravel,roots and rootlets. Sand is fine to medium.

0.25 Firm brown sandy CLAY with occasional roots. Sand is medium.

0.60 Firm brown mottled grey sandy CLAY with occasional medium sub - angular gravel. Sand is medium.

0.90 Firm brown CLAY with partings of orange medium sand . 1.00 Soft light brown mottled grey sandy gravelly CLAY. Sand is fine to 1.10 medium and gravel is of fine to medium sub- angular quartz. Brown gravelly clayey fine to medium SAND. Gravel is fine to medium sub- angular to sub rounded quartz.

(0.90)

2.00

End of Hand Auger at 2.00m

GENERAL REMARKS Groundwater encountered at 1.3m bgl.

All dimensions in metres Client Method Logged Scale 1:20 Persimmon Homes Midlands Ltd Hand Augering by SP/JS 3/26/07, HANDAUGER, 44406876 EIA.GPJ HAND AUGER LOG

Project Hole Location HOLE No Towcester EIA/ Flood Risk Assessment, . Job No Date Ground Level (mAOD) Co-ordinates (mOD) HA6 44406876 Mar 8, 07 E 470040 N 246720 Contractor Sheet URS Corporation Ltd. 1 of 1

SAMPLES & TESTS STRATA Type In situ Reduced Depth DESCRIPTION

Depth Tests Water Level Legend (Thick-

No. Geology Instru- ment/ Backfill (Vane) mAOD ness) kN/m2 TOPSOIL:Brown to dark brown clay with occasional fine sub - angular gravel and rootlets. 0.20 Firm brown grey sandy CLAY with occasional fine to medium sub- angular gravel. Sand is medium.

(0.60)

0.80 Firm brown CLAY with partings of orange medium sand.

(0.50)

1.30 Soft to firm brown gravelly sandy CLAY. Gravel is fine to medium subangular quartz and sand is fine to medium.

(0.70)

2.00

End of Hand Auger at 2.00m

GENERAL REMARKS Groundwater encountered at 1.6m bgl.

All dimensions in metres Client Method Logged Scale 1:20 Persimmon Homes Midlands Ltd Hand Augering by SP/JS 3/26/07, HANDAUGER, 44406876 EIA.GPJ HAND AUGER LOG

Project Hole Location HOLE No Towcester EIA/ Flood Risk Assessment, . Job No Date Ground Level (mAOD) Co-ordinates (mOD) HA8 44406876 Mar 8, 07 E 470440 N 247530 Contractor Sheet URS Corporation Ltd. 1 of 1

SAMPLES & TESTS STRATA Type In situ Reduced Depth DESCRIPTION

Depth Tests Water Level Legend (Thick-

No. Geology Instru- ment/ Backfill (Vane) mAOD ness) kN/m2 TOPSOIL- Firm brown to dark brown clay with old roots.

0.20 Firm light brown CLAY with weathered limestone fragments..

0.40 Firm light brown mottled orange- grey CLAY with occasinal bands of weathered limestone and fine orange sand.

(0.45)

0.85 Weak light brown fine - grained LIMESTONE, highly weathered. 1.00

End of Hand Auger at 1.00m

GENERAL REMARKS Hole stopped at 1.0m, Hard soil strata(Lime stone) found at the depth of completion. No Groundwater encountered.

All dimensions in metres Client Method Logged Scale 1:20 Persimmon Homes Midlands Ltd Hand Augering by SP/JS 3/26/07, HANDAUGER, 44406876 EIA.GPJ HAND AUGER LOG

Project Hole Location HOLE No Towcester EIA/ Flood Risk Assessment, . Job No Date Ground Level (mAOD) Co-ordinates (mOD) HA9 44406876 Mar 8, 07 E 470870 N 247080 Contractor Sheet URS Corporation Ltd. 1 of 1

SAMPLES & TESTS STRATA Type In situ Reduced Depth DESCRIPTION

Depth Tests Water Level Legend (Thick-

No. Geology Instru- ment/ Backfill (Vane) mAOD ness) kN/m2 TOPSOIL- Firm brown to dark brown clay.

0.30 Firm light grey mottled light brown CLAY.

0.60 0.65 Orange brown medium SAND. Firm becoming stiff grey CLAY with occasional pockets of orange medium sand.

(0.85)

1.50 Stiff grey to dark grey highly fissured CLAY with pockets of orange medium sand.

(0.50)

2.00

End of Hand Auger at 2.00m

GENERAL REMARKS No Groundwater encountered.

All dimensions in metres Client Method Logged Scale 1:20 Persimmon Homes Midlands Ltd Hand Augering by SP/JS 3/26/07, HANDAUGER, 44406876 EIA.GPJ HAND AUGER LOG

Project Hole Location HOLE No Towcester EIA/ Flood Risk Assessment, . Job No Date Ground Level (mAOD) Co-ordinates (mOD) HA10 44406876 Mar 8, 07 E 470110 N 247430 Contractor Sheet URS Corporation Ltd. 1 of 1

SAMPLES & TESTS STRATA Type In situ Reduced Depth DESCRIPTION

Depth Tests Water Level Legend (Thick-

No. Geology Instru- ment/ Backfill (Vane) mAOD ness) kN/m2 TOPSOIL: Brown to dark brown sandy clay with occasional fine angular gravel. 0.20 MADE GROUND: Firm to stiff brown to dark brown slightly sandy clay with occasional gravel ,brick fragments , chalk and pocket of peat.

0.60 Stiff orange-brown CLAY with occasional fine to medium sub - angular gravel.

(1.40)

2.00

End of Hand Auger at 2.00m

GENERAL REMARKS No Groundwater encountered.

All dimensions in metres Client Method Logged Scale 1:20 Persimmon Homes Midlands Ltd Hand Augeringby SP/JS 3/26/07, HANDAUGER, 44406876 EIA.GPJ Towcester Vale Flood Risk Assessment

Appendix C - Calculation Details for Existing/Pre-Development Flood Flows

Persimmon Homes Midlands Ltd\44406876 Towcester EIA\BDRP0007/FB/FB Revision 1 November 2007 BDRP0007

Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

User name Florian Baltoi Catchment name Silverstone Brook Date/time modelled 04-Oct-2007 20:31 Company name URS Corporation Ltd. Catchment easting 468550 Version 1.3 Project name Towcester FRA Catchment northing 247950 Catchment area 21.42 Summary of model setup Design rainfall parameters Loss model parameters Routing model parameters Baseflow model parameters

Return period (yr) 1.01 Cmax (mm) 331 Tp (hr) 5.18 BL (hr) 41.8

Duration (hr) 8.5 Cini (mm) 128 Up 0.65 BR 0.9 3 Timestep (hr) 0.5 ααα factor 1 Uk 0.8 BF 0 (m /s) 0.9 Season Winter

Summary of results FEH DDF rainfall (mm) 16.5 Peak rainfall (mm) 1.6 Design rainfall (mm) 10.8 Peak flow (m 3/s) 3.5

Results Graph Series Design Rainfall Net rainfall Direct runoff Baseflow Total flow 3 3 3 ReFH Model Output: Silverstone Brook Unit mm mm m /s m /s m /s 0.0 0.1 0.1 0.0 0.9 0.9 1.8 4 0.5 0.2 0.1 0.0 0.9 0.9 1.0 0.3 0.1 0.0 0.9 0.9 1.6 3.5 1.5 0.4 0.1 0.0 0.8 0.9 1.4 2.0 0.5 0.2 0.0 0.8 0.9 3 2.5 0.7 0.3 0.1 0.8 0.9 1.2 3.0 1.0 0.4 0.1 0.8 1.0 2.5 /s) 3.5 1.3 0.5 0.2 0.8 1.0 1 3 4.0 1.6 0.7 0.3 0.8 1.1 2 4.5 1.3 0.5 0.5 0.8 1.3 0.8 5.0 1.0 0.4 0.7 0.8 1.5 1.5 0.6 Flow (m 5.5 0.7 0.3 0.9 0.8 1.7 Rainfall (mm) 1 6.0 0.5 0.2 1.1 0.8 1.9 0.4 6.5 0.4 0.2 1.4 0.8 2.2 7.0 0.3 0.1 1.7 0.8 2.5 0.2 0.5 7.5 0.2 0.1 1.9 0.8 2.7 8.0 0.1 0.1 2.1 0.8 3.0 0 0 8.5 0.0 0.0 2.4 0.8 3.2 0 5 10 15 20 25 9.0 0.0 0.0 2.5 0.9 3.4 9.5 0.0 0.0 2.6 0.9 3.5 Time (hr) Rainfall Net rainfall Total flow Direct runoff Baseflow 10.0 0.0 0.0 2.6 0.9 3.5 10.5 0.0 0.0 2.6 0.9 3.5 11.0 0.0 0.0 2.5 0.9 3.4 11.5 0.0 0.0 2.4 0.9 3.3 12.0 0.0 0.0 2.3 1.0 3.2 12.5 0.0 0.0 2.1 1.0 3.1 13.0 0.0 0.0 2.0 1.0 2.9 13.5 0.0 0.0 1.8 1.0 2.8 14.0 0.0 0.0 1.7 1.0 2.6 14.5 0.0 0.0 1.5 1.0 2.5 15.0 0.0 0.0 1.4 1.0 2.4 15.5 0.0 0.0 1.3 1.0 2.3 16.0 0.0 0.0 1.2 1.0 2.2 16.5 0.0 0.0 1.1 1.0 2.1 17.0 0.0 0.0 1.0 1.0 2.0 17.5 0.0 0.0 0.9 1.0 1.9 18.0 0.0 0.0 0.8 1.0 1.8 18.5 0.0 0.0 0.7 1.0 1.7 19.0 0.0 0.0 0.6 1.0 1.6 19.5 0.0 0.0 0.6 1.0 1.5 20.0 0.0 0.0 0.5 1.0 1.5 20.5 0.0 0.0 0.4 1.0 1.4 21.0 0.0 0.0 0.3 1.0 1.3 21.5 0.0 0.0 0.3 1.0 1.2 22.0 0.0 0.0 0.2 0.9 1.1 22.5 0.0 0.0 0.1 0.9 1.1 23.0 0.0 0.0 0.1 0.9 1.0 23.5 0.0 0.0 0.1 0.9 1.0 24.0 0.0 0.0 0.0 0.9 0.9 24.5 0.0 0.0 0.0 0.9 0.9 25.0 0.0 0.0 0.0 0.9 0.9 25.5 0.0 0.0 0.0 0.9 0.9 26.0 0.0 0.0 0.0 0.9 0.9 26.5 0.0 0.0 0.0 0.9 0.9 27.0 0.0 0.0 0.0 0.8 0.8 Total (mm) 10.8 4.3 4.3 4.2 8.5

Audit comments

Catchment Error checking data in catchment descriptor file 'J:\Bedford-Jobs\Persimmon Homes Midlands Ltd\44406876 Towchester EIA\Technical\Flood risk assessment\Silverstone Brook Existing\New Flow Node\Silverstone Brook.csv' No catchment descriptor file stored - catchment descriptors manually entered Catchment decriptor file exported from CD ROM version 1 BFIHOST value of 0.397 used PROPWET value of 0.3 used SAAR value of 661 used DPLBAR value of 4.67 used DPSBAR value of 35.9 used URBEXT value of 0.011 used C value of -0.024 used D1 value of 0.314 used D2 value of 0.304 used D3 value of 0.237 used E value of 0.298 used F value of 2.506 used

Rainfall

Page 1 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

Recommended season is Winter, as URBEXT < 0.125 ReFH design standard Seasonal Correction Factor of 0.69 applied ReFH design standard Areal Reduction Factor of 0.95 applied

Loss Model

CMax derived from catchment descriptors

ReFH design standard C ini used ReFH design standard α factor used

Routing Model

Tp derived from catchment descriptors

ReFH design standard used for U p

ReFH design standard used for U k

Baseflow Model BL derived from catchment descriptors BR derived from catchment descriptors

ReFH design standard BF 0 used

Page 2 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

User name Florian Baltoi Catchment name Silverstone Brook Date/time modelled 09-Aug-2007 09:58 Company name URS Corporation Ltd. Catchment easting 468550 Version 1.3 Project name Towcester FRA Catchment northing 247950 Catchment area 21.42 Summary of model setup Design rainfall parameters Loss model parameters Routing model parameters Baseflow model parameters

Return period (yr) 20 Cmax (mm) 331 Tp (hr) 5.18 BL (hr) 41.8

Duration (hr) 8.5 Cini (mm) 128 Up 0.65 BR 0.9 3 Timestep (hr) 0.5 ααα factor 0.94 Uk 0.8 BF 0 (m /s) 0.9 Season Winter

Summary of results FEH DDF rainfall (mm) 49.9 Peak rainfall (mm) 5 Design rainfall (mm) 32.7 Peak flow (m 3/s) 9.5

Results Graph Series Design Rainfall Net rainfall Direct runoff Baseflow Total flow 3 3 3 ReFH Model Output: Silverstone Brook Unit mm mm m /s m /s m /s 0.0 0.4 0.2 0.0 0.9 0.9 6 10 0.5 0.6 0.2 0.0 0.9 0.9 1.0 0.8 0.3 0.0 0.9 0.9 9 5 1.5 1.1 0.4 0.1 0.8 0.9 8 2.0 1.6 0.6 0.1 0.8 1.0 2.5 2.2 0.8 0.2 0.8 1.1 7 4 3.0 3.0 1.2 0.4 0.8 1.2

6 /s) 3.5 4.1 1.6 0.6 0.8 1.4 3 4.0 5.0 2.0 0.9 0.8 1.7 3 5 4.5 4.1 1.7 1.4 0.8 2.2 5.0 3.0 1.3 2.0 0.8 2.8 4 2 Flow (m 5.5 2.2 1.0 2.7 0.8 3.5 Rainfall (mm) 3 6.0 1.6 0.7 3.4 0.9 4.3 2 6.5 1.1 0.5 4.2 0.9 5.1 1 7.0 0.8 0.4 5.0 0.9 6.0 1 7.5 0.6 0.3 5.8 1.0 6.8 8.0 0.4 0.2 6.5 1.0 7.6 0 0 8.5 0.0 0.0 7.2 1.1 8.3 0 5 10 15 20 25 9.0 0.0 0.0 7.7 1.2 8.9 9.5 0.0 0.0 8.0 1.2 9.3 Time (hr) Rainfall Net rainfall Total flow Direct runoff Baseflow 10.0 0.0 0.0 8.1 1.3 9.5 10.5 0.0 0.0 8.1 1.4 9.4 11.0 0.0 0.0 7.8 1.4 9.3 11.5 0.0 0.0 7.5 1.5 9.0 12.0 0.0 0.0 7.1 1.6 8.7 12.5 0.0 0.0 6.6 1.6 8.3 13.0 0.0 0.0 6.2 1.7 7.8 13.5 0.0 0.0 5.7 1.7 7.4 14.0 0.0 0.0 5.2 1.8 6.9 14.5 0.0 0.0 4.7 1.8 6.5 15.0 0.0 0.0 4.3 1.8 6.1 15.5 0.0 0.0 4.0 1.8 5.8 16.0 0.0 0.0 3.6 1.9 5.5 16.5 0.0 0.0 3.3 1.9 5.2 17.0 0.0 0.0 3.0 1.9 4.9 17.5 0.0 0.0 2.8 1.9 4.7 18.0 0.0 0.0 2.5 1.9 4.4 18.5 0.0 0.0 2.3 1.9 4.2 19.0 0.0 0.0 2.0 1.9 3.9 19.5 0.0 0.0 1.8 1.9 3.7 20.0 0.0 0.0 1.5 1.9 3.4 20.5 0.0 0.0 1.3 1.9 3.2 21.0 0.0 0.0 1.0 1.9 2.9 21.5 0.0 0.0 0.8 1.9 2.7 22.0 0.0 0.0 0.6 1.8 2.5 22.5 0.0 0.0 0.5 1.8 2.3 23.0 0.0 0.0 0.3 1.8 2.1 23.5 0.0 0.0 0.2 1.8 2.0 24.0 0.0 0.0 0.1 1.8 1.9 24.5 0.0 0.0 0.1 1.8 1.8 25.0 0.0 0.0 0.0 1.7 1.8 25.5 0.0 0.0 0.0 1.7 1.7 26.0 0.0 0.0 0.0 1.7 1.7 26.5 0.0 0.0 0.0 1.7 1.7 27.0 0.0 0.0 0.0 1.7 1.7 Total (mm) 32.7 13.4 13.4 6.7 20.1

Audit comments

Rainfall

Page 1 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

Recommended season is Winter, as URBEXT < 0.125 ReFH design standard Seasonal Correction Factor of 0.69 applied ReFH design standard Areal Reduction Factor of 0.95 applied

Loss Model

CMax derived from catchment descriptors

ReFH design standard C ini used ReFH design standard α factor used

Routing Model

Tp derived from catchment descriptors

ReFH design standard used for U p

ReFH design standard used for U k

Baseflow Model BL derived from catchment descriptors BR derived from catchment descriptors

ReFH design standard BF 0 used

Page 2 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

User name Florian Baltoi Catchment name Wood Burcote Brook Date/time modelled 09-Aug-2007 10:06 Company name URS Catchment easting 469600 Version 1.3 Project name Towcester Vale Catchment northing 247750 Catchment area 2.47 Summary of model setup Design rainfall parameters Loss model parameters Routing model parameters Baseflow model parameters

Return period (yr) 20 Cmax (mm) 356 Tp (hr) 2.74 BL (hr) 34.3

Duration (hr) 4.75 Cini (mm) 128 Up 0.65 BR 0.97 3 Timestep (hr) 0.25 ααα factor 0.94 Uk 0.8 BF 0 (m /s) 0.1 Season Winter

Summary of results FEH DDF rainfall (mm) 43.3 Peak rainfall (mm) 3.8 Design rainfall (mm) 27.7 Peak flow (m 3/s) 1.5

Results Graph Series Design Rainfall Net rainfall Direct runoff Baseflow Total flow 3 3 3 ReFH Model Output: Wood Burcote Brook Unit mm mm m /s m /s m /s 0.00 0.3 0.1 0.0 0.1 0.1 4 1.6 0.25 0.4 0.1 0.0 0.1 0.1 0.50 0.6 0.2 0.0 0.1 0.1 3.5 1.4 0.75 0.8 0.3 0.0 0.1 0.1 1.00 1.0 0.4 0.0 0.1 0.1 3 1.2 1.25 1.4 0.5 0.0 0.1 0.1 1.50 1.8 0.6 0.0 0.1 0.1 2.5 1 /s)

1.75 2.4 0.9 0.1 0.1 0.2 3 2.00 3.2 1.2 0.1 0.1 0.2 2 0.8 2.25 3.8 1.4 0.2 0.1 0.3 2.50 3.2 1.2 0.2 0.1 0.3 1.5 0.6 Flow (m

2.75 2.4 1.0 0.3 0.1 0.4 Rainfall (mm) 3.00 1.8 0.7 0.4 0.1 0.5 1 0.4 3.25 1.4 0.6 0.6 0.1 0.7 3.50 1.0 0.4 0.7 0.1 0.8 0.5 0.2 3.75 0.8 0.3 0.8 0.1 0.9 4.00 0.6 0.2 0.9 0.1 1.1 0 0 4.25 0.4 0.2 1.1 0.1 1.2 0 2 4 6 8 10 12 14 4.50 0.3 0.1 1.2 0.1 1.3 4.75 0.0 0.0 1.2 0.1 1.4 Time (hr) Rainfall Net rainfall Total flow Direct runoff Baseflow 5.00 0.0 0.0 1.3 0.1 1.5 5.25 0.0 0.0 1.4 0.2 1.5 5.50 0.0 0.0 1.4 0.2 1.5 5.75 0.0 0.0 1.3 0.2 1.5 6.00 0.0 0.0 1.3 0.2 1.5 6.25 0.0 0.0 1.2 0.2 1.4 6.50 0.0 0.0 1.2 0.2 1.4 6.75 0.0 0.0 1.1 0.2 1.3 7.00 0.0 0.0 1.0 0.2 1.2 7.25 0.0 0.0 1.0 0.2 1.2 7.50 0.0 0.0 0.9 0.2 1.1 7.75 0.0 0.0 0.8 0.2 1.0 8.00 0.0 0.0 0.7 0.2 1.0 8.25 0.0 0.0 0.7 0.2 0.9 8.50 0.0 0.0 0.6 0.2 0.9 8.75 0.0 0.0 0.6 0.2 0.8 9.00 0.0 0.0 0.5 0.2 0.8 9.25 0.0 0.0 0.5 0.2 0.7 9.50 0.0 0.0 0.4 0.2 0.7 9.75 0.0 0.0 0.4 0.2 0.6 10.00 0.0 0.0 0.4 0.2 0.6 10.25 0.0 0.0 0.3 0.2 0.6 10.50 0.0 0.0 0.3 0.2 0.5 10.75 0.0 0.0 0.2 0.2 0.5 11.00 0.0 0.0 0.2 0.2 0.5 11.25 0.0 0.0 0.2 0.2 0.4 11.50 0.0 0.0 0.1 0.2 0.4 11.75 0.0 0.0 0.1 0.2 0.4 12.00 0.0 0.0 0.1 0.2 0.3 12.25 0.0 0.0 0.1 0.2 0.3 12.50 0.0 0.0 0.0 0.2 0.3 12.75 0.0 0.0 0.0 0.2 0.3 13.00 0.0 0.0 0.0 0.2 0.3 13.25 0.0 0.0 0.0 0.2 0.2 13.50 0.0 0.0 0.0 0.2 0.2 13.75 0.0 0.0 0.0 0.2 0.2 14.00 0.0 0.0 0.0 0.2 0.2 14.25 0.0 0.0 0.0 0.2 0.2 14.50 0.0 0.0 0.0 0.2 0.2 Total (mm) 27.7 10.4 10.4 3.9 14.3

Audit comments

Catchment Error checking data in catchment descriptor file 'J:\Bedford-Jobs\Persimmon Homes Midlands Ltd\44406876 Towchester EIA\Technical\Flood risk assessment\Wood Burcote Brook Existing\Wood Burcote CD.csv' No catchment descriptor file stored - catchment descriptors manually entered Catchment decriptor file exported from CD ROM version 1 BFIHOST value of 0.428 used PROPWET value of 0.3 used SAAR value of 644 used DPLBAR value of 1.57 used DPSBAR value of 33.5 used URBEXT value of 0.012 used C value of -0.024 used D1 value of 0.308 used D2 value of 0.296 used D3 value of 0.243 used

Page 1 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

E value of 0.299 used F value of 2.511 used

Rainfall Recommended season is Winter, as URBEXT < 0.125 ReFH design standard Seasonal Correction Factor of 0.66 applied ReFH design standard Areal Reduction Factor of 0.97 applied

Loss Model

CMax derived from catchment descriptors

ReFH design standard C ini used ReFH design standard α factor used

Routing Model

Tp derived from catchment descriptors

ReFH design standard used for U p

ReFH design standard used for U k

Baseflow Model BL derived from catchment descriptors BR derived from catchment descriptors

ReFH design standard BF 0 used

Page 2 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

User name Florian Baltoi Catchment name Silverstone Brook Date/time modelled 09-Aug-2007 10:02 Company name URS Corporation Ltd. Catchment easting 468550 Version 1.3 Project name Towcester FRA Catchment northing 247950 Catchment area 21.42 Summary of model setup Design rainfall parameters Loss model parameters Routing model parameters Baseflow model parameters

Return period (yr) 100 Cmax (mm) 331 Tp (hr) 5.18 BL (hr) 41.8

Duration (hr) 8.5 Cini (mm) 128 Up 0.65 BR 0.9 3 Timestep (hr) 0.5 ααα factor 0.83 Uk 0.8 BF 0 (m /s) 0.9 Season Winter

Summary of results FEH DDF rainfall (mm) 74.6 Peak rainfall (mm) 7.4 Design rainfall (mm) 48.9 Peak flow (m 3/s) 13.3

Results Graph Series Design Rainfall Net rainfall Direct runoff Baseflow Total flow 3 3 3 ReFH Model Output: Silverstone Brook Unit mm mm m /s m /s m /s 0.0 0.6 0.2 0.0 0.9 0.9 8 14 0.5 0.9 0.3 0.0 0.9 0.9 1.0 1.2 0.4 0.0 0.9 0.9 7 12 1.5 1.7 0.6 0.1 0.8 0.9 2.0 2.4 0.8 0.2 0.8 1.0 6 2.5 3.3 1.1 0.3 0.8 1.1 10 3.0 4.5 1.6 0.5 0.8 1.3 5 /s)

3.5 6.1 2.3 0.8 0.8 1.6 8 3 4.0 7.4 2.9 1.3 0.8 2.1 4 4.5 6.1 2.5 1.9 0.8 2.7 6 5.0 4.5 1.9 2.7 0.8 3.6 3 Flow (m 5.5 3.3 1.5 3.7 0.9 4.6 Rainfall (mm) 4 6.0 2.4 1.1 4.8 0.9 5.7 2 6.5 1.7 0.8 5.9 1.0 6.9 7.0 1.2 0.6 7.1 1.0 8.1 1 2 7.5 0.9 0.4 8.2 1.1 9.3 8.0 0.6 0.3 9.3 1.2 10.5 0 0 8.5 0.0 0.0 10.3 1.3 11.5 0 5 10 15 20 25 9.0 0.0 0.0 11.0 1.3 12.4 9.5 0.0 0.0 11.5 1.5 13.0 Time (hr) Rainfall Net rainfall Total flow Direct runoff Baseflow 10.0 0.0 0.0 11.7 1.6 13.3 10.5 0.0 0.0 11.6 1.7 13.3 11.0 0.0 0.0 11.3 1.8 13.1 11.5 0.0 0.0 10.9 1.9 12.7 12.0 0.0 0.0 10.3 2.0 12.2 12.5 0.0 0.0 9.6 2.0 11.7 13.0 0.0 0.0 8.9 2.1 11.1 13.5 0.0 0.0 8.2 2.2 10.4 14.0 0.0 0.0 7.5 2.2 9.8 14.5 0.0 0.0 6.9 2.3 9.2 15.0 0.0 0.0 6.3 2.3 8.6 15.5 0.0 0.0 5.8 2.4 8.1 16.0 0.0 0.0 5.3 2.4 7.7 16.5 0.0 0.0 4.8 2.4 7.3 17.0 0.0 0.0 4.4 2.4 6.9 17.5 0.0 0.0 4.0 2.5 6.5 18.0 0.0 0.0 3.7 2.5 6.1 18.5 0.0 0.0 3.3 2.5 5.8 19.0 0.0 0.0 2.9 2.5 5.4 19.5 0.0 0.0 2.6 2.5 5.1 20.0 0.0 0.0 2.2 2.5 4.7 20.5 0.0 0.0 1.9 2.5 4.3 21.0 0.0 0.0 1.5 2.5 4.0 21.5 0.0 0.0 1.2 2.4 3.7 22.0 0.0 0.0 0.9 2.4 3.4 22.5 0.0 0.0 0.7 2.4 3.1 23.0 0.0 0.0 0.5 2.4 2.9 23.5 0.0 0.0 0.3 2.4 2.7 24.0 0.0 0.0 0.2 2.3 2.5 24.5 0.0 0.0 0.1 2.3 2.4 25.0 0.0 0.0 0.1 2.3 2.4 25.5 0.0 0.0 0.0 2.3 2.3 26.0 0.0 0.0 0.0 2.2 2.2 26.5 0.0 0.0 0.0 2.2 2.2 27.0 0.0 0.0 0.0 2.2 2.2 Total (mm) 48.9 19.3 19.3 8.3 27.6

Audit comments

Rainfall

Page 1 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

Recommended season is Winter, as URBEXT < 0.125 ReFH design standard Seasonal Correction Factor of 0.69 applied ReFH design standard Areal Reduction Factor of 0.95 applied

Loss Model

CMax derived from catchment descriptors

ReFH design standard C ini used ReFH design standard α factor used

Routing Model

Tp derived from catchment descriptors

ReFH design standard used for U p

ReFH design standard used for U k

Baseflow Model BL derived from catchment descriptors BR derived from catchment descriptors

ReFH design standard BF 0 used

Page 2 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

User name Florian Baltoi Catchment name Wood Burcote Brook Date/time modelled 09-Aug-2007 10:07 Company name URS Catchment easting 469600 Version 1.3 Project name Towcester Vale Catchment northing 247750 Catchment area 2.47 Summary of model setup Design rainfall parameters Loss model parameters Routing model parameters Baseflow model parameters

Return period (yr) 100 Cmax (mm) 356 Tp (hr) 2.74 BL (hr) 34.3

Duration (hr) 4.75 Cini (mm) 128 Up 0.65 BR 0.97 3 Timestep (hr) 0.25 ααα factor 0.83 Uk 0.8 BF 0 (m /s) 0.1 Season Winter

Summary of results FEH DDF rainfall (mm) 66.3 Peak rainfall (mm) 5.8 Design rainfall (mm) 42.4 Peak flow (m 3/s) 2.2

Results Graph Series Design Rainfall Net rainfall Direct runoff Baseflow Total flow 3 3 3 ReFH Model Output: Wood Burcote Brook Unit mm mm m /s m /s m /s 0.00 0.5 0.1 0.0 0.1 0.1 7 2.5 0.25 0.6 0.2 0.0 0.1 0.1 0.50 0.9 0.3 0.0 0.1 0.1 6 0.75 1.2 0.4 0.0 0.1 0.1 2 1.00 1.6 0.5 0.0 0.1 0.1 1.25 2.1 0.7 0.0 0.1 0.1 5 1.50 2.8 0.9 0.1 0.1 0.2

1.5 /s) 1.75 3.7 1.2 0.1 0.1 0.2 4 3 2.00 4.9 1.7 0.2 0.1 0.3 2.25 5.8 2.1 0.2 0.1 0.3 3 2.50 4.9 1.8 0.3 0.1 0.4 1 Flow (m 2.75 3.7 1.4 0.5 0.1 0.6 Rainfall (mm) 2 3.00 2.8 1.1 0.6 0.1 0.7 3.25 2.1 0.8 0.8 0.1 0.9 0.5 3.50 1.6 0.6 1.0 0.1 1.1 1 3.75 1.2 0.5 1.2 0.1 1.3 4.00 0.9 0.4 1.3 0.1 1.5 0 0 4.25 0.6 0.3 1.5 0.1 1.7 0 2 4 6 8 10 12 14 4.50 0.5 0.2 1.7 0.1 1.8 4.75 0.0 0.0 1.8 0.2 2.0 Time (hr) Rainfall Net rainfall Total flow Direct runoff Baseflow 5.00 0.0 0.0 1.9 0.2 2.1 5.25 0.0 0.0 2.0 0.2 2.2 5.50 0.0 0.0 2.0 0.2 2.2 5.75 0.0 0.0 2.0 0.2 2.2 6.00 0.0 0.0 1.9 0.2 2.1 6.25 0.0 0.0 1.8 0.2 2.1 6.50 0.0 0.0 1.7 0.2 2.0 6.75 0.0 0.0 1.6 0.3 1.9 7.00 0.0 0.0 1.5 0.3 1.8 7.25 0.0 0.0 1.4 0.3 1.7 7.50 0.0 0.0 1.3 0.3 1.6 7.75 0.0 0.0 1.2 0.3 1.5 8.00 0.0 0.0 1.1 0.3 1.4 8.25 0.0 0.0 1.0 0.3 1.3 8.50 0.0 0.0 0.9 0.3 1.2 8.75 0.0 0.0 0.9 0.3 1.2 9.00 0.0 0.0 0.8 0.3 1.1 9.25 0.0 0.0 0.7 0.3 1.0 9.50 0.0 0.0 0.7 0.3 1.0 9.75 0.0 0.0 0.6 0.3 0.9 10.00 0.0 0.0 0.5 0.3 0.9 10.25 0.0 0.0 0.5 0.3 0.8 10.50 0.0 0.0 0.4 0.3 0.7 10.75 0.0 0.0 0.4 0.3 0.7 11.00 0.0 0.0 0.3 0.3 0.6 11.25 0.0 0.0 0.3 0.3 0.6 11.50 0.0 0.0 0.2 0.3 0.5 11.75 0.0 0.0 0.2 0.3 0.5 12.00 0.0 0.0 0.1 0.3 0.4 12.25 0.0 0.0 0.1 0.3 0.4 12.50 0.0 0.0 0.1 0.3 0.4 12.75 0.0 0.0 0.0 0.3 0.4 13.00 0.0 0.0 0.0 0.3 0.3 13.25 0.0 0.0 0.0 0.3 0.3 13.50 0.0 0.0 0.0 0.3 0.3 13.75 0.0 0.0 0.0 0.3 0.3 14.00 0.0 0.0 0.0 0.3 0.3 14.25 0.0 0.0 0.0 0.3 0.3 14.50 0.0 0.0 0.0 0.3 0.3 Total (mm) 42.4 15.2 15.2 4.9 20.1

Audit comments

Page 1 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

E value of 0.299 used F value of 2.511 used

Rainfall Recommended season is Winter, as URBEXT < 0.125 ReFH design standard Seasonal Correction Factor of 0.66 applied ReFH design standard Areal Reduction Factor of 0.97 applied

Loss Model

CMax derived from catchment descriptors

ReFH design standard C ini used ReFH design standard α factor used

Routing Model

Tp derived from catchment descriptors

ReFH design standard used for U p

ReFH design standard used for U k

Baseflow Model BL derived from catchment descriptors BR derived from catchment descriptors

ReFH design standard BF 0 used

Page 2 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

User name Florian Baltoi Catchment name Silverstone Brook Date/time modelled 09-Aug-2007 10:03 Company name URS Corporation Ltd. Catchment easting 468550 Version 1.3 Project name Towcester FRA Catchment northing 247950 Catchment area 21.42 Summary of model setup Design rainfall parameters Loss model parameters Routing model parameters Baseflow model parameters

Return period (yr) 200 Cmax (mm) 331 Tp (hr) 5.18 BL (hr) 41.8

Duration (hr) 8.5 Cini (mm) 128 Up 0.65 BR 0.9 3 Timestep (hr) 0.5 ααα factor 0.79 Uk 0.8 BF 0 (m /s) 0.9 Season Winter

Summary of results FEH DDF rainfall (mm) 88.6 Peak rainfall (mm) 8.8 Design rainfall (mm) 58 Peak flow (m 3/s) 15.6

Results Graph Series Design Rainfall Net rainfall Direct runoff Baseflow Total flow 3 3 3 ReFH Model Output: Silverstone Brook Unit mm mm m /s m /s m /s 0.0 0.7 0.2 0.0 0.9 0.9 10 18 0.5 1.0 0.3 0.0 0.9 0.9 1.0 1.5 0.5 0.0 0.9 0.9 9 16 1.5 2.0 0.6 0.1 0.8 0.9 8 2.0 2.8 0.9 0.2 0.8 1.0 14 2.5 3.9 1.3 0.3 0.8 1.2 7 12 3.0 5.4 1.9 0.6 0.8 1.4

6 /s) 3.5 7.3 2.7 0.9 0.8 1.7 10 3 4.0 8.8 3.5 1.4 0.8 2.3 5 4.5 7.3 3.0 2.2 0.8 3.0 8 5.0 5.4 2.3 3.1 0.9 4.0 4 6 Flow (m 5.5 3.9 1.8 4.3 0.9 5.2 Rainfall (mm) 3 6.0 2.8 1.3 5.6 0.9 6.5 4 6.5 2.0 0.9 6.9 1.0 7.9 2 7.0 1.5 0.7 8.3 1.1 9.3 1 2 7.5 1.0 0.5 9.6 1.1 10.8 8.0 0.7 0.4 10.9 1.2 12.1 0 0 8.5 0.0 0.0 12.0 1.3 13.4 0 5 10 15 20 25 9.0 0.0 0.0 13.0 1.5 14.4 9.5 0.0 0.0 13.6 1.6 15.2 Time (hr) Rainfall Net rainfall Total flow Direct runoff Baseflow 10.0 0.0 0.0 13.8 1.7 15.6 10.5 0.0 0.0 13.7 1.8 15.6 11.0 0.0 0.0 13.4 2.0 15.4 11.5 0.0 0.0 12.9 2.1 14.9 12.0 0.0 0.0 12.2 2.2 14.4 12.5 0.0 0.0 11.4 2.3 13.7 13.0 0.0 0.0 10.6 2.4 13.0 13.5 0.0 0.0 9.8 2.5 12.2 14.0 0.0 0.0 9.0 2.5 11.5 14.5 0.0 0.0 8.2 2.6 10.8 15.0 0.0 0.0 7.5 2.6 10.1 15.5 0.0 0.0 6.9 2.7 9.5 16.0 0.0 0.0 6.3 2.7 9.0 16.5 0.0 0.0 5.8 2.8 8.5 17.0 0.0 0.0 5.3 2.8 8.0 17.5 0.0 0.0 4.8 2.8 7.6 18.0 0.0 0.0 4.3 2.8 7.2 18.5 0.0 0.0 3.9 2.8 6.7 19.0 0.0 0.0 3.5 2.8 6.3 19.5 0.0 0.0 3.1 2.8 5.9 20.0 0.0 0.0 2.6 2.8 5.5 20.5 0.0 0.0 2.2 2.8 5.1 21.0 0.0 0.0 1.8 2.8 4.7 21.5 0.0 0.0 1.5 2.8 4.3 22.0 0.0 0.0 1.1 2.8 3.9 22.5 0.0 0.0 0.8 2.8 3.6 23.0 0.0 0.0 0.6 2.7 3.3 23.5 0.0 0.0 0.4 2.7 3.1 24.0 0.0 0.0 0.2 2.7 2.9 24.5 0.0 0.0 0.2 2.6 2.8 25.0 0.0 0.0 0.1 2.6 2.7 25.5 0.0 0.0 0.0 2.6 2.6 26.0 0.0 0.0 0.0 2.6 2.6 26.5 0.0 0.0 0.0 2.5 2.5 27.0 0.0 0.0 0.0 2.5 2.5 Total (mm) 58.0 22.8 22.8 9.2 32.0

Audit comments

Rainfall

Page 1 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

Recommended season is Winter, as URBEXT < 0.125 ReFH design standard Seasonal Correction Factor of 0.69 applied ReFH design standard Areal Reduction Factor of 0.95 applied

Loss Model

CMax derived from catchment descriptors

ReFH design standard C ini used ReFH design standard α factor used

Routing Model

Tp derived from catchment descriptors

ReFH design standard used for U p

ReFH design standard used for U k

Baseflow Model BL derived from catchment descriptors BR derived from catchment descriptors

ReFH design standard BF 0 used

Page 2 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

User name Florian Baltoi Catchment name Wood Burcote Brook Date/time modelled 09-Aug-2007 10:08 Company name URS Catchment easting 469600 Version 1.3 Project name Towcester Vale Catchment northing 247750 Catchment area 2.47 Summary of model setup Design rainfall parameters Loss model parameters Routing model parameters Baseflow model parameters

Return period (yr) 200 Cmax (mm) 356 Tp (hr) 2.74 BL (hr) 34.3

Duration (hr) 4.75 Cini (mm) 128 Up 0.65 BR 0.97 3 Timestep (hr) 0.25 ααα factor 0.79 Uk 0.8 BF 0 (m /s) 0.1 Season Winter

Summary of results FEH DDF rainfall (mm) 79.5 Peak rainfall (mm) 6.9 Design rainfall (mm) 50.9 Peak flow (m 3/s) 2.6

Results Graph Series Design Rainfall Net rainfall Direct runoff Baseflow Total flow 3 3 3 ReFH Model Output: Wood Burcote Brook Unit mm mm m /s m /s m /s 0.00 0.6 0.2 0.0 0.1 0.1 8 3 0.25 0.8 0.2 0.0 0.1 0.1 0.50 1.0 0.3 0.0 0.1 0.1 7 0.75 1.4 0.4 0.0 0.1 0.1 2.5 1.00 1.9 0.6 0.0 0.1 0.1 6 1.25 2.5 0.8 0.0 0.1 0.1 2 1.50 3.4 1.1 0.1 0.1 0.2 5 /s)

1.75 4.5 1.4 0.1 0.1 0.2 3 2.00 5.9 2.0 0.2 0.1 0.3 4 1.5 2.25 6.9 2.5 0.3 0.1 0.4 2.50 5.9 2.2 0.4 0.1 0.5 3 1 Flow (m 2.75 4.5 1.7 0.6 0.1 0.7 Rainfall (mm) 3.00 3.4 1.3 0.7 0.1 0.8 2 3.25 2.5 1.0 0.9 0.1 1.0 0.5 3.50 1.9 0.8 1.1 0.1 1.3 1 3.75 1.4 0.6 1.4 0.1 1.5 4.00 1.0 0.4 1.6 0.1 1.7 0 0 4.25 0.8 0.3 1.8 0.1 1.9 0 2 4 6 8 10 12 14 4.50 0.6 0.2 2.0 0.2 2.1 4.75 0.0 0.0 2.1 0.2 2.3 Time (hr) Rainfall Net rainfall Total flow Direct runoff Baseflow 5.00 0.0 0.0 2.3 0.2 2.5 5.25 0.0 0.0 2.3 0.2 2.6 5.50 0.0 0.0 2.4 0.2 2.6 5.75 0.0 0.0 2.3 0.2 2.6 6.00 0.0 0.0 2.3 0.2 2.5 6.25 0.0 0.0 2.2 0.3 2.5 6.50 0.0 0.0 2.1 0.3 2.4 6.75 0.0 0.0 2.0 0.3 2.3 7.00 0.0 0.0 1.8 0.3 2.1 7.25 0.0 0.0 1.7 0.3 2.0 7.50 0.0 0.0 1.6 0.3 1.9 7.75 0.0 0.0 1.4 0.3 1.8 8.00 0.0 0.0 1.3 0.3 1.7 8.25 0.0 0.0 1.2 0.3 1.6 8.50 0.0 0.0 1.1 0.3 1.5 8.75 0.0 0.0 1.0 0.3 1.4 9.00 0.0 0.0 1.0 0.4 1.3 9.25 0.0 0.0 0.9 0.4 1.2 9.50 0.0 0.0 0.8 0.4 1.2 9.75 0.0 0.0 0.7 0.4 1.1 10.00 0.0 0.0 0.6 0.4 1.0 10.25 0.0 0.0 0.6 0.4 0.9 10.50 0.0 0.0 0.5 0.4 0.9 10.75 0.0 0.0 0.4 0.4 0.8 11.00 0.0 0.0 0.4 0.4 0.7 11.25 0.0 0.0 0.3 0.4 0.7 11.50 0.0 0.0 0.3 0.4 0.6 11.75 0.0 0.0 0.2 0.4 0.6 12.00 0.0 0.0 0.2 0.4 0.5 12.25 0.0 0.0 0.1 0.4 0.5 12.50 0.0 0.0 0.1 0.4 0.4 12.75 0.0 0.0 0.1 0.4 0.4 13.00 0.0 0.0 0.0 0.4 0.4 13.25 0.0 0.0 0.0 0.4 0.4 13.50 0.0 0.0 0.0 0.4 0.4 13.75 0.0 0.0 0.0 0.4 0.4 14.00 0.0 0.0 0.0 0.3 0.4 14.25 0.0 0.0 0.0 0.3 0.3 14.50 0.0 0.0 0.0 0.3 0.3 Total (mm) 50.9 18.1 18.1 5.5 23.6

Audit comments

Page 1 of 2 Revitalised FSR/FEH rainfall runoff method Spreadsheet application report

E value of 0.299 used F value of 2.511 used

Rainfall Recommended season is Winter, as URBEXT < 0.125 ReFH design standard Seasonal Correction Factor of 0.66 applied ReFH design standard Areal Reduction Factor of 0.97 applied

Loss Model

CMax derived from catchment descriptors

ReFH design standard C ini used ReFH design standard α factor used

Routing Model

Tp derived from catchment descriptors

ReFH design standard used for U p

ReFH design standard used for U k

Baseflow Model BL derived from catchment descriptors BR derived from catchment descriptors

ReFH design standard BF 0 used

Page 2 of 2 Towcester Vale Flood Risk Assessment

Appendix D - Environment Agency Data Used for Silverstone Brook Model Calibration

Persimmon Homes Midlands Ltd\44406876 Towcester EIA\BDRP0007/FB/FB Revision 1 November 2007 BDRP0007

ModelledNodePointMeasurement

NFCDD_ID NodePointName ModelledFloodGroupCode ReturnPeriod LevelValue FlowValue Supporting deleted Downloaded changed for_upload 1 EA0522171022 EA05231 100 85.68 59 FALSE FALSE TRUE FALSE TRUE 2 EA0522171046 EA05231 100 85.58 59 FALSE FALSE TRUE FALSE TRUE 3 EA052218103 EA05232 100 86.04 15.6 FALSE FALSE TRUE FALSE TRUE 4 EA052218102 EA05232 100 85.95 15.6 FALSE FALSE TRUE FALSE TRUE 5 EA052218101 EA05232 100 85.85 15.6 FALSE FALSE TRUE FALSE TRUE 6 EA052218100 EA05232 100 85.8 15.6 FALSE FALSE TRUE FALSE TRUE 7 EA0522181009 EA05232 100 85.79 15.6 FALSE FALSE TRUE FALSE TRUE 8 EA0522181007 EA05232 100 85.68 15.6 FALSE FALSE TRUE FALSE TRUE 9 EA0522181006 EA05232 100 89.65 15.6 FALSE FALSE TRUE FALSE TRUE 10 EA052218105 EA05232 100 89.39 15.6 FALSE FALSE TRUE FALSE TRUE 11 EA052218104 EA05232 100 89.11 15.6 FALSE FALSE TRUE FALSE TRUE 12 EA0522181005 EA05232 100 88.03 15.6 FALSE FALSE TRUE FALSE TRUE 13 EA0522181004 EA05232 100 87.96 15.6 FALSE FALSE TRUE FALSE TRUE 14 EA0522181003 EA05232 100 87.24 15.6 FALSE FALSE TRUE FALSE TRUE 15 EA0522181008 EA05232 100 87 15.6 FALSE FALSE TRUE FALSE TRUE 16 EA0522181013 EA05232 100 86.42 15.6 FALSE FALSE TRUE FALSE TRUE

Page 1 """Chris"Chris Collin """ To <<k>>> 26/09/2007 10:26 bcc Subject Fwd: Re: Towcester Vale - Silverstone Brook Bypass Scheme

Florian,

Please find attached a map to show the location of the chainage points.

For clarity: CH 1.600 @ SP 68470 47885 (468470E 247886 N) CH 1.400 @ SP 68560 48020 (468560E 248020 N) CH 1.300 @ SP 68640 48085 (468640E 248085 N) - Springfields Bridge/Towcester By-Pass Bridge CH 1.200 @ SP 68735 48165 (468735 248165)

I think the bridge titled Buckingham Road Bridge is the Bridge over the River on Buckingham Way.

Hope this helps,

Chris.

Christopher Collin Development Control Engineer chris .collin @environment -agency .gov .uk Direct Dial: 01480 483805 Direct Fax: 01480 435193

The Environment Agency Bromholme Lane, Brampton, Huntingdon, Cambs. PE28 4 NE

Information in this message may be confidential and may be legally privileged. If you have received this message by mistake, please notify the sender immediately, delete it and do not copy it to anyone else.

We have checked this email and its attachments for viruses. But you should still check any attachment before opening it. We may have to make this message and any reply to it public if asked to under the Freedom of Information Act, Data Protection Act or for litigation. Email messages and attachments sent to or from any Environment Agency address may also be accessed by someone other than the sender or recipient, for business purposes.

If we have sent you information and you wish to use it please read our terms and conditions which you can get by calling us on 08708 506 506. Find out more about the Environment Agency at www.environment-agency.gov.uk ----- Message from "Chris Collin" on Tue, 25 Sep 2007 08:56:41 +0100 ----- To: "Rhiannon Swindale" , "Wasim cc: Quasem" Subj Re: Towcester Vale - Silverstone Brook Bypass Scheme ect: Florian,

Further to our meeting of the 21st, please find attached cross-section drawing and revised data licence agreement.

Regards, Chris.

Christopher Collin Development Control Engineer

chris .collin @environment -agency .gov .uk Direct Dial: 01480 483805 Direct Fax: 01480 435193

The Environment Agency Bromholme Lane, Brampton, Huntingdon, Cambs. PE28 4 NE

>>> 24/09/2007 10:59:04 >>>

Dear All,

Attached are the meeting minutes of the meeting that URS had with the Environment Agency on 21st September 2007 in Brampton. If you have comments please let me know. Regards,

Florian

(See attached file: BDMR 0003 Meeting with the EA on 21 Sept 2007.doc )

Florian Baltoi, P.E. Senior Hydrologist URS Corporation Ltd. URS House Horne Lane Bedford MK40 1TS United Kingdom Office: +44 (0) 1234 349 641 Direct: +44 (0) 1234 373 679 Fax: +44 (0) 1234 216 268 e-mail: Florian [email protected]

This e-mail and any attachments are confidential. If you receive this message in error or are not the intended recipient, you should not retain , distribute, disclose or use any of this information and you should destroy the e-mail and any attachments or copies.

URS Corporation Limited Place of registration: Scotland Registered number: 118271 Registered office: 243 West George Street, Glasgow G2 4QE

Click here to report this email as spam.

Legend

Chainage Points

0.4

0.6

0.8

1.2

1.4

1.6

Data Licence Agreement

This Licence Agreement is between:- The Environment Agency URS Corporation Ltd Head Office Rio House URS House Waterside Drive Horne Lane And Aztec West Bedford, Almondsbury MK40 1TS BRISTOL BS32 4UD

We, the Environment Agency (“The Agency”), and you, the recipient of the Data (" The User ") agree that: 1. This Agreement includes these paragraphs the Schedule below and General Conditions. 2. Subject to paragraph 9 if you make any usage of the Data you are deemed to accept the terms of this Agreement and to agree to use the Data accordingly. 3. If it is not possible to interpret consistently the special conditions below and the General Conditions attached the special conditions will prevail. 4. “Data” can include information, records and documents of any kind. 5. Either we own the intellectual property rights to the Data (“Agency Data”) or a third party might own such rights (“Third Party Data”)

6. We will provide you with the Data specified under the heading The Data below. 7. You must not do anything whatsoever with the Third Party Data, including copying, in excess of your statutory rights unless we have indicated in writing otherwise. You agree to indemnify us in respect of any breach of this requirement. 8. You must pay us the charges set out in the Schedule and (where applicable) value added tax. 9. This does not affect your statutory rights

SCHEDULE THE DATA Full details of information supplied including updates and any applicability to Supply Format future requests of the same kind Post construction modelled flood levels taken from the Letter & Email Towcester Flood Alleviation Scheme, Project Appraisal Report, December 2000. Northampton Road – SP 69290 49010 Broadwater Weir – SP 69670 48980 Cappenham Weir – SP 71140 48680 (1 in 5, 1 in 10, 1 in 25, 1 in 50, 1 in 75, 1 in 100) Drawing BR/21/00/102 – Silverstone Brook Cross Sections FEES PAYABLE

£50.00 CONTACT DETAILS

Agency User Chris Collin – Development Control Officer Florian Baltoi – Senior Hydrologist 01480 483805 01234 373679

PERIOD OF LICENCE:

Issue date: End Date: 20 February 2008

SPECIAL CONDITIONS

GENERAL CONDITIONS OF AGREEMENT

from defects, computer viruses, software locks or other similar 1 OWNERSHIP & LICENCE code or that the operation of the Data will be uninterrupted or 1.1 Subject to this Agreement, we grant you a non-exclusive and error-free. You should carry out all necessary virus checks non-transferable licence to use Agency Data beginning on the prior to loading the Data on to your computer system. date upon which we supply you with it. 5.3 We do not guarantee that the Data will always be accurate, 1.2 You will not remove, suppress or modify, in any way, any trade correct, complete, up to date or valid. We give you no mark, copyright or other proprietary marking on or in Agency warranty about the condition or satisfactory quality of any part Data or which are visible during their operation or use (whether of the Data. electronically or otherwise) or which are on their carrier 5.4 You accept that we are providing the Data to you because we medium, if any. 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(e) put Agency Data on the Internet or any similar system or 7.3 No waiver of any breach of the Agreement will be treated as a (f) do any other thing to Agency Data so that they cease to waiver of any other breach of the Agreement or other term of be readily identifiable as Agency Data the Agreement and no waiver will be effective unless made in writing. without our written approval beforehand. 7.4 The Agreement contains the whole agreement between you 4 SECURITY AND AUDITING and us relating to the provision of the Data and supersedes all previous communications, representations and arrangements, 4.1 You will maintain adequate security measures to safeguard the written or oral. Data from unauthorised access, or use. 7.5 No change to the Agreement will be effective unless it is in 4.2 You will allow us to check your use of the Data at all writing and signed by those authorised for the purpose by you reasonable times.. and us. 5 LIABILITY 7.6 The Agreement will be governed by and interpreted in accordance with English law and we and you agree to submit 5.1 We do not promise that the Data will provide any particular to the jurisdiction of the English courts in connection with the facilities or functions. You must ensure that the Data meet your Agreement. needs. You are entirely responsible for the consequences of any use of the Data and subject to condition 5.6, we give you 7.7 The parties hereby agree that nothing in this Agreement shall no warranty about the fitness for purpose or performance of be construed as creating a right which is enforceable by any any part of the Data. person who is not a party to it. (Version 6) 5.2 If an electronic format has been used, we do not promise that the media on which the Data are provided will always be free Towcester Vale Flood Risk Assessment

Appendix E - Calculation Details for Assessment of Flooding for Existing/Pre-Development Conditions

Persimmon Homes Midlands Ltd\44406876 Towcester EIA\BDRP0007/FB/FB Revision 1 November 2007 BDRP0007

HEC-RAS Plan: SB River: Silverstone Broo Reach: 1 Profile: EA 100 yr flow Reach River Sta Profile Q Total Min Ch El W.S. Elev Top Width Sta W.S. Lft Sta W.S. Rgt Cum Ch Len SA Total Vel Chnl Vel Left Vel Right Vel Total Froude # Chl (m3/s) (m) (m) (m) (m) (m) (m) (1000 m2) (m/s) (m/s) (m/s) (m/s) 1 2600 EA 100 yr flow 15.60 91.32 93.15 28.56 21.84 50.40 1411.50 127.84 0.71 0.29 0.67 0.20 1 2550 Culvert 1 2500 EA 100 yr flow 15.60 91.21 92.94 78.52 0.26 78.79 1369.00 123.81 0.49 0.30 0.38 0.12 1 2400 EA 100 yr flow 15.60 91.00 92.87 72.62 0.15 72.77 1365.00 121.02 0.58 0.39 0.45 0.15 1 2300 EA 100 yr flow 15.60 90.83 92.83 84.29 3.12 87.41 1347.50 120.25 0.49 0.36 0.39 0.14 1 2200 EA 100 yr flow 15.60 90.82 92.74 83.49 7.61 91.10 1336.00 116.88 0.48 0.11 0.35 0.38 0.13 1 2100 EA 100 yr flow 15.60 90.70 92.66 88.84 12.53 101.37 1312.50 114.81 0.65 0.47 0.35 0.45 0.17 1 2000 EA 100 yr flow 15.60 90.62 92.55 104.66 8.12 112.79 1280.00 112.51 0.55 0.38 0.33 0.40 0.16 1 1900 EA 100 yr flow 15.60 90.50 92.38 98.80 5.08 107.20 1231.50 106.65 0.47 0.38 0.18 0.38 0.14 1 1800 EA 100 yr flow 15.60 90.40 92.24 126.06 4.32 130.38 1181.50 101.26 0.54 0.34 0.29 0.36 0.14 1 1700 EA 100 yr flow 15.60 90.30 91.99 128.99 1.35 130.35 1128.50 93.64 0.62 0.40 0.24 0.42 0.18 1 1600 EA 100 yr flow 15.60 90.20 91.84 111.97 20.00 131.97 1094.50 90.36 0.63 0.44 0.34 0.45 0.19 1 1500 EA 100 yr flow 15.60 89.70 91.57 135.90 21.49 157.39 1021.50 85.07 0.67 0.31 0.34 0.41 0.18 1 1400 EA 100 yr flow 15.60 89.42 91.41 139.92 16.13 156.05 976.00 79.05 0.51 0.27 0.33 0.33 0.12 1 1300 EA 100 yr flow 15.60 89.28 91.29 136.29 15.91 152.21 943.50 72.73 0.55 0.29 0.31 0.35 0.15 1 1200 EA 100 yr flow 15.60 89.30 91.22 138.55 18.26 156.82 928.50 70.04 0.56 0.31 0.27 0.37 0.16 1 1100 EA 100 yr flow 15.60 89.08 91.10 140.33 16.66 156.99 900.50 65.73 0.59 0.31 0.25 0.37 0.16 1 1015 Culvert 1 1005 EA 100 yr flow 15.60 89.00 91.10 141.47 15.96 157.43 887.00 64.25 0.58 0.27 0.26 0.35 0.14 1 1002 EA 100 yr flow 15.60 89.00 91.06 144.94 21.40 166.34 868.50 62.96 0.56 0.28 0.28 0.34 0.14 1 1000 EA 100 yr flow 15.60 89.19 91.00 143.77 15.36 159.13 856.00 61.39 0.74 0.37 0.37 0.44 0.21 1 940 EA 100 yr flow 15.60 89.00 90.83 127.70 13.30 141.01 813.50 55.34 0.45 0.28 0.30 0.33 0.13 1 930 EA 100 yr flow 15.60 88.80 90.78 124.84 13.53 138.36 795.00 53.11 0.50 0.30 0.30 0.35 0.14 1 915 Bridge 1 905 EA 100 yr flow 15.60 88.70 90.71 124.02 13.87 137.89 783.00 51.62 0.62 0.34 0.34 0.42 0.18 1 900 EA 100 yr flow 15.60 88.65 90.66 117.71 19.05 136.76 775.00 50.51 0.65 0.38 0.38 0.45 0.20 1 800 EA 100 yr flow 15.60 88.60 90.39 106.90 2.89 109.79 717.00 43.71 0.51 0.37 0.33 0.38 0.15 1 700 EA 100 yr flow 15.60 88.45 90.27 116.52 8.89 125.41 684.00 40.04 0.54 0.33 0.34 0.39 0.16 1 600 EA 100 yr flow 15.60 88.32 90.21 116.40 11.77 128.17 669.00 38.65 0.59 0.29 0.42 0.42 0.18 1 500 EA 100 yr flow 15.60 88.22 89.95 101.91 26.35 128.26 595.00 31.11 0.47 0.34 0.33 0.36 0.14 1 400 EA 100 yr flow 15.60 87.89 89.78 118.11 16.03 134.14 542.00 25.80 0.59 0.31 0.32 0.40 0.17 1 300 EA 100 yr flow 15.60 87.90 89.73 121.15 18.12 139.27 527.00 24.03 0.61 0.29 0.29 0.39 0.16 1 230 EA 100 yr flow 15.60 87.92 89.55 71.29 0.00 71.29 480.00 19.56 0.62 0.44 0.49 0.17 1 220 EA 100 yr flow 15.60 87.90 89.42 72.37 0.00 72.37 427.00 17.39 0.48 0.38 0.41 0.14 1 215 Bridge 1 210 EA 100 yr flow 15.60 87.64 89.37 80.48 0.00 80.48 412.50 16.27 0.45 0.23 0.38 0.39 0.13 1 200 EA 100 yr flow 15.60 87.20 89.28 78.43 0.00 78.43 368.50 14.01 0.53 0.44 0.35 0.43 0.15 1 150 EA 100 yr flow 15.60 86.84 89.07 61.66 0.00 61.66 318.50 9.60 0.58 0.49 0.41 0.47 0.14 1 100 EA 100 yr flow 15.60 86.90 88.94 55.07 0.00 55.07 281.50 7.32 0.60 0.49 0.41 0.48 0.15 1 50 EA 100 yr flow 15.60 87.10 88.61 42.84 0.00 42.84 277.00 4.56 2.20 0.35 0.39 1.10 0.66 1 40 EA 100 yr flow 15.60 87.00 88.33 11.65 2.31 13.96 266.50 4.21 1.67 0.04 1.67 0.52 1 30 EA 100 yr flow 15.60 86.52 88.01 20.45 31.55 59.99 130.50 2.01 1.37 0.21 0.26 1.09 0.40 1 25 Bridge 1 20 EA 100 yr flow 15.60 86.47 87.98 20.18 31.59 59.95 117.00 1.77 1.41 0.21 0.26 1.14 0.41 1 10 EA 100 yr flow 15.60 86.09 87.64 9.83 12.94 22.77 1.56 1.56 0.49

HEC-RAS Plan: SB River: Silverstone Broo Reach: 1 Reach River Sta Profile Q Total Min Ch El W.S. Elev Top Width Sta W.S. Lft Sta W.S. Rgt Cum Ch Len SA Total Vel Chnl Vel Left Vel Right Vel Total Froude # Chl (m3/s) (m) (m) (m) (m) (m) (m) (1000 m2) (m/s) (m/s) (m/s) (m/s) 1 2600 20 yr with clima 11.40 91.32 92.96 21.53 28.33 49.86 1411.50 116.13 0.63 0.08 0.63 0.19 1 2600 100 yr with clim 16.00 91.32 93.17 28.93 21.53 50.46 1411.50 128.80 0.71 0.30 0.67 0.20 1 2600 200 yr with clim 18.70 91.32 93.29 31.39 19.41 50.79 1411.50 134.48 0.73 0.38 0.68 0.20

1 2550 Culvert

1 2500 20 yr with clima 11.40 91.21 92.83 69.92 0.32 70.24 1369.00 112.64 0.45 0.26 0.34 0.12 1 2500 100 yr with clim 16.00 91.21 92.95 79.25 0.26 79.51 1369.00 124.73 0.49 0.31 0.38 0.12 1 2500 200 yr with clim 18.70 91.21 93.01 83.45 0.23 83.69 1369.00 130.17 0.51 0.33 0.40 0.13

1 2400 20 yr with clima 11.40 91.00 92.77 66.22 0.17 66.39 1365.00 110.15 0.55 0.34 0.41 0.14 1 2400 100 yr with clim 16.00 91.00 92.88 73.15 0.15 73.30 1365.00 121.91 0.59 0.40 0.45 0.15 1 2400 200 yr with clim 18.70 91.00 92.93 76.57 0.14 76.70 1365.00 127.20 0.61 0.43 0.48 0.15

1 2300 20 yr with clima 11.40 90.83 92.73 77.31 3.36 80.67 1347.50 109.44 0.47 0.31 0.36 0.14 1 2300 100 yr with clim 16.00 90.83 92.84 84.87 3.10 87.98 1347.50 121.14 0.49 0.36 0.39 0.14 1 2300 200 yr with clim 18.70 90.83 92.90 88.56 2.98 91.54 1347.50 126.39 0.50 0.39 0.41 0.14

1 2200 20 yr with clima 11.40 90.82 92.65 76.35 9.12 85.47 1336.00 106.35 0.44 0.05 0.30 0.34 0.12 1 2200 100 yr with clim 16.00 90.82 92.75 84.07 7.48 91.56 1336.00 117.74 0.49 0.11 0.36 0.39 0.13 1 2200 200 yr with clim 18.70 90.82 92.80 87.80 6.69 94.50 1336.00 122.85 0.51 0.14 0.38 0.41 0.14

1 2100 20 yr with clima 11.40 90.70 92.57 82.77 14.56 97.34 1312.50 104.44 0.62 0.44 0.29 0.42 0.17 1 2100 100 yr with clim 16.00 90.70 92.67 89.32 12.37 101.69 1312.50 115.66 0.65 0.47 0.36 0.45 0.17 1 2100 200 yr with clim 18.70 90.70 92.71 92.38 11.34 103.72 1312.50 120.68 0.67 0.49 0.39 0.48 0.17

1 2000 20 yr with clima 11.40 90.62 92.46 92.85 8.36 104.93 1280.00 102.36 0.53 0.39 0.29 0.38 0.16 1 2000 100 yr with clim 16.00 90.62 92.56 105.02 8.10 113.12 1280.00 113.35 0.55 0.38 0.34 0.40 0.16 1 2000 200 yr with clim 18.70 90.62 92.60 107.22 7.99 115.21 1280.00 118.31 0.56 0.41 0.36 0.41 0.16

1 1900 20 yr with clima 11.40 90.50 92.30 86.19 5.26 98.64 1231.50 97.23 0.42 0.33 0.13 0.34 0.13 1 1900 100 yr with clim 16.00 90.50 92.39 99.87 5.06 107.92 1231.50 107.45 0.47 0.39 0.18 0.39 0.14 1 1900 200 yr with clim 18.70 90.50 92.43 105.44 4.97 112.37 1231.50 112.17 0.50 0.42 0.20 0.41 0.14

1 1800 20 yr with clima 11.40 90.40 92.17 117.86 8.70 126.56 1181.50 92.42 0.53 0.30 0.24 0.34 0.14 1 1800 100 yr with clim 16.00 90.40 92.25 126.55 4.15 130.70 1181.50 102.01 0.54 0.34 0.29 0.37 0.14 1 1800 200 yr with clim 18.70 90.40 92.29 129.51 3.12 132.62 1181.50 106.48 0.56 0.37 0.31 0.38 0.15

1 1700 20 yr with clima 11.40 90.30 91.92 108.69 9.18 117.88 1128.50 85.56 0.58 0.36 0.19 0.39 0.17 1 1700 100 yr with clim 16.00 90.30 91.99 130.75 0.68 131.42 1128.50 94.33 0.62 0.40 0.24 0.42 0.18 1 1700 200 yr with clim 18.70 90.30 92.03 134.53 -1.06 133.47 1128.50 98.62 0.64 0.43 0.27 0.43 0.18

1 1600 20 yr with clima 11.40 90.20 91.78 101.10 27.37 128.47 1094.50 82.74 0.57 0.38 0.29 0.40 0.18 1 1600 100 yr with clim 16.00 90.20 91.85 112.92 19.36 132.28 1094.50 91.01 0.63 0.44 0.35 0.45 0.19 1 1600 200 yr with clim 18.70 90.20 91.88 119.06 15.20 134.26 1094.50 95.16 0.66 0.47 0.38 0.48 0.19

1 1500 20 yr with clima 11.40 89.70 91.50 128.15 26.59 154.74 1021.50 77.90 0.68 0.25 0.31 0.40 0.19 1 1500 100 yr with clim 16.00 89.70 91.58 136.44 21.17 157.61 1021.50 85.69 0.67 0.31 0.34 0.41 0.18 1 1500 200 yr with clim 18.70 89.70 91.62 139.87 19.13 158.99 1021.50 89.60 0.66 0.34 0.36 0.42 0.18

1 1400 20 yr with clima 11.40 89.42 91.34 121.92 30.60 152.51 976.00 72.43 0.48 0.24 0.29 0.30 0.12 1 1400 100 yr with clim 16.00 89.42 91.42 141.45 14.91 156.35 976.00 79.62 0.51 0.27 0.33 0.33 0.12 1 1400 200 yr with clim 18.70 89.42 91.46 151.14 7.12 158.26 976.00 83.25 0.52 0.29 0.35 0.34 0.13

1 1300 20 yr with clima 11.40 89.28 91.22 128.06 21.22 149.28 943.50 66.75 0.52 0.25 0.27 0.33 0.15 1 1300 100 yr with clim 16.00 89.28 91.30 136.99 15.47 152.45 943.50 73.24 0.55 0.30 0.31 0.36 0.15 1 1300 200 yr with clim 18.70 89.28 91.33 141.44 12.60 154.04 943.50 76.52 0.56 0.32 0.33 0.37 0.15

1 1200 20 yr with clima 11.40 89.30 91.16 131.70 22.74 154.44 928.50 64.22 0.54 0.26 0.22 0.35 0.16 1 1200 100 yr with clim 16.00 89.30 91.23 139.13 17.89 157.02 928.50 70.55 0.56 0.31 0.27 0.38 0.16 1 1200 200 yr with clim 18.70 89.30 91.27 142.81 15.48 158.29 928.50 73.75 0.57 0.34 0.30 0.39 0.17

1 1100 20 yr with clima 11.40 89.08 91.04 135.64 19.44 155.08 900.50 60.08 0.58 0.25 0.20 0.35 0.16 1 1100 100 yr with clim 16.00 89.08 91.11 140.72 16.43 157.15 900.50 66.23 0.60 0.31 0.26 0.38 0.16 1 1100 200 yr with clim 18.70 89.08 91.14 143.22 14.95 158.17 900.50 69.34 0.61 0.34 0.29 0.39 0.16

1 1015 Culvert

1 1005 20 yr with clima 11.40 89.00 91.04 136.60 18.59 155.20 887.00 58.65 0.55 0.21 0.21 0.32 0.14 1 1005 100 yr with clim 16.00 89.00 91.11 141.87 15.75 157.61 887.00 64.74 0.58 0.27 0.26 0.35 0.14 1 1005 200 yr with clim 18.70 89.00 91.14 144.44 14.36 158.79 887.00 67.82 0.60 0.30 0.28 0.37 0.14

1 1002 20 yr with clima 11.40 89.00 91.00 138.55 25.51 164.06 868.50 57.43 0.54 0.24 0.24 0.32 0.14 1 1002 100 yr with clim 16.00 89.00 91.07 145.35 21.14 166.49 868.50 63.44 0.56 0.29 0.29 0.35 0.14 1 1002 200 yr with clim 18.70 89.00 91.10 148.07 19.43 167.50 868.50 66.49 0.58 0.31 0.31 0.36 0.15

1 1000 20 yr with clima 11.40 89.19 90.93 119.82 31.80 151.62 856.00 56.03 0.75 0.34 0.34 0.45 0.22 1 1000 100 yr with clim 16.00 89.19 91.01 144.13 15.18 159.31 856.00 61.87 0.73 0.38 0.38 0.45 0.21 1 1000 200 yr with clim 18.70 89.19 91.05 146.43 14.01 160.44 856.00 64.89 0.71 0.40 0.39 0.45 0.20

1 940 20 yr with clima 11.40 89.00 90.76 120.33 18.82 139.15 813.50 50.68 0.42 0.24 0.26 0.29 0.12 1 940 100 yr with clim 16.00 89.00 90.84 128.34 12.83 141.17 813.50 55.80 0.46 0.29 0.31 0.33 0.13 1 940 200 yr with clim 18.70 89.00 90.88 132.49 9.73 142.22 813.50 58.68 0.47 0.31 0.33 0.35 0.13

1 930 20 yr with clima 11.40 88.80 90.72 118.58 17.53 136.10 795.00 48.56 0.46 0.25 0.26 0.31 0.14 1 930 100 yr with clim 16.00 88.80 90.79 125.38 13.18 138.56 795.00 53.56 0.50 0.31 0.31 0.36 0.15 1 930 200 yr with clim 18.70 88.80 90.82 128.96 10.89 139.85 795.00 56.37 0.52 0.33 0.33 0.38 0.15

1 915 Bridge

1 905 20 yr with clima 11.40 88.70 90.64 118.25 17.21 135.45 783.00 47.14 0.61 0.29 0.29 0.39 0.18 1 905 100 yr with clim 16.00 88.70 90.72 124.52 13.58 138.10 783.00 52.06 0.62 0.35 0.34 0.42 0.18 1 905 200 yr with clim 18.70 88.70 90.76 127.76 11.71 139.46 783.00 54.83 0.63 0.37 0.37 0.43 0.18

1 900 20 yr with clima 11.40 88.65 90.59 111.02 23.12 134.14 775.00 46.09 0.65 0.33 0.33 0.43 0.21 1 900 100 yr with clim 16.00 88.65 90.67 118.29 18.69 136.98 775.00 50.95 0.65 0.38 0.38 0.45 0.20 1 900 200 yr with clim 18.70 88.65 90.71 122.03 16.42 138.45 775.00 53.68 0.65 0.41 0.41 0.46 0.20

1 800 20 yr with clima 11.40 88.60 90.31 99.39 4.84 104.23 717.00 39.71 0.48 0.31 0.29 0.35 0.15 1 800 100 yr with clim 16.00 88.60 90.40 107.55 2.72 110.27 717.00 44.10 0.51 0.37 0.33 0.39 0.15 1 800 200 yr with clim 18.70 88.60 90.44 111.75 1.63 113.37 717.00 46.60 0.53 0.40 0.35 0.41 0.15

1 700 20 yr with clima 11.40 88.45 90.19 110.64 11.72 122.36 684.00 36.25 0.52 0.28 0.29 0.36 0.16 1 700 100 yr with clim 16.00 88.45 90.27 117.03 8.64 125.68 684.00 40.42 0.54 0.33 0.34 0.39 0.16 1 700 200 yr with clim 18.70 88.45 90.31 120.34 7.05 127.39 684.00 42.81 0.55 0.36 0.36 0.41 0.16

1 600 20 yr with clima 11.40 88.32 90.12 110.68 15.04 125.72 669.00 34.92 0.60 0.23 0.38 0.41 0.19 1 600 100 yr with clim 16.00 88.32 90.21 116.89 11.49 128.38 669.00 39.02 0.59 0.29 0.42 0.42 0.18 1 600 200 yr with clim 18.70 88.32 90.26 120.01 9.71 129.72 669.00 41.37 0.59 0.32 0.44 0.44 0.17

1 500 20 yr with clima 11.40 88.22 89.87 91.19 34.01 125.20 595.00 27.93 0.44 0.30 0.29 0.33 0.13 HEC-RAS Plan: SB River: Silverstone Broo Reach: 1 (Continued) Reach River Sta Profile Q Total Min Ch El W.S. Elev Top Width Sta W.S. Lft Sta W.S. Rgt Cum Ch Len SA Total Vel Chnl Vel Left Vel Right Vel Total Froude # Chl (m3/s) (m) (m) (m) (m) (m) (m) (1000 m2) (m/s) (m/s) (m/s) (m/s) 1 500 100 yr with clim 16.00 88.22 89.96 102.81 25.71 128.52 595.00 31.43 0.48 0.35 0.34 0.37 0.14 1 500 200 yr with clim 18.70 88.22 90.01 108.42 21.76 130.18 595.00 33.48 0.50 0.37 0.36 0.38 0.14

1 400 20 yr with clima 11.40 87.89 89.70 106.32 22.35 128.67 542.00 23.18 0.58 0.26 0.28 0.39 0.17 1 400 100 yr with clim 16.00 87.89 89.79 119.13 15.48 134.61 542.00 26.08 0.59 0.32 0.32 0.40 0.17 1 400 200 yr with clim 18.70 87.89 89.84 125.78 11.92 137.69 542.00 27.83 0.59 0.34 0.34 0.41 0.17

1 300 20 yr with clima 11.40 87.90 89.63 110.62 24.11 134.73 527.00 21.57 0.60 0.24 0.24 0.39 0.17 1 300 100 yr with clim 16.00 87.90 89.73 122.05 17.61 139.66 527.00 24.30 0.61 0.29 0.30 0.39 0.16 1 300 200 yr with clim 18.70 87.90 89.78 128.00 14.23 142.22 527.00 25.96 0.60 0.31 0.32 0.40 0.16

1 230 20 yr with clima 11.40 87.92 89.45 65.00 0.00 65.00 480.00 17.49 0.60 0.39 0.45 0.17 1 230 100 yr with clim 16.00 87.92 89.56 71.61 0.00 71.61 480.00 19.79 0.63 0.45 0.49 0.17 1 230 200 yr with clim 18.70 87.92 89.61 73.69 0.00 73.69 480.00 21.24 0.63 0.48 0.51 0.17

1 220 20 yr with clima 11.40 87.90 89.32 68.47 0.00 68.47 427.00 15.47 0.44 0.33 0.37 0.13 1 220 100 yr with clim 16.00 87.90 89.43 72.73 0.00 72.73 427.00 17.62 0.48 0.39 0.41 0.14 1 220 200 yr with clim 18.70 87.90 89.49 74.96 0.00 74.96 427.00 19.01 0.49 0.42 0.43 0.14

1 215 Bridge

1 210 20 yr with clima 11.40 87.64 89.27 76.62 0.60 77.21 412.50 14.40 0.44 0.17 0.34 0.35 0.13 1 210 100 yr with clim 16.00 87.64 89.38 80.78 0.00 80.78 412.50 16.49 0.46 0.24 0.38 0.39 0.13 1 210 200 yr with clim 18.70 87.64 89.44 82.64 0.00 82.64 412.50 17.85 0.47 0.27 0.40 0.41 0.13

1 200 20 yr with clima 11.40 87.20 89.16 73.12 0.00 73.12 368.50 12.26 0.52 0.39 0.30 0.41 0.16 1 200 100 yr with clim 16.00 87.20 89.29 78.93 0.00 78.93 368.50 14.22 0.53 0.44 0.35 0.43 0.15 1 200 200 yr with clim 18.70 87.20 89.35 81.87 0.00 81.87 368.50 15.53 0.53 0.47 0.37 0.44 0.15

1 150 20 yr with clima 11.40 86.84 88.94 56.84 0.00 56.84 318.50 8.19 0.58 0.44 0.36 0.44 0.15 1 150 100 yr with clim 16.00 86.84 89.08 61.93 0.00 61.93 318.50 9.78 0.58 0.50 0.41 0.47 0.14 1 150 200 yr with clim 18.70 86.84 89.15 63.60 0.00 63.60 318.50 10.93 0.59 0.52 0.44 0.49 0.14

1 100 20 yr with clima 11.40 86.90 88.80 51.03 0.00 51.03 281.50 6.09 0.58 0.43 0.36 0.45 0.15 1 100 100 yr with clim 16.00 86.90 88.95 55.44 0.00 55.44 281.50 7.49 0.60 0.50 0.41 0.49 0.15 1 100 200 yr with clim 18.70 86.90 89.02 57.37 0.00 57.37 281.50 8.57 0.61 0.53 0.44 0.50 0.15

1 50 20 yr with clima 11.40 87.10 88.43 30.19 0.00 34.53 277.00 3.87 2.29 0.19 0.28 1.58 0.75 1 50 100 yr with clim 16.00 87.10 88.62 43.02 0.00 43.02 277.00 4.70 2.23 0.36 0.40 1.10 0.67 1 50 200 yr with clim 18.70 87.10 88.67 44.46 0.00 44.46 277.00 5.63 2.34 0.43 0.45 1.10 0.69

1 40 20 yr with clima 11.40 87.00 88.14 8.30 2.65 10.95 266.50 3.63 1.49 1.49 0.49 1 40 100 yr with clim 16.00 87.00 88.34 13.40 2.28 15.68 266.50 4.35 1.69 0.06 1.67 0.52 1 40 200 yr with clim 18.70 87.00 88.45 24.55 2.09 26.64 266.50 5.20 1.78 0.13 1.62 0.53

1 30 20 yr with clima 11.40 86.52 87.79 18.79 31.78 59.76 130.50 1.76 1.28 0.09 0.19 1.14 0.41 1 30 100 yr with clim 16.00 86.52 88.03 20.59 31.53 60.01 130.50 2.03 1.38 0.22 0.27 1.08 0.40 1 30 200 yr with clim 18.70 86.52 88.15 21.45 31.41 60.13 130.50 2.13 1.44 0.26 0.30 1.09 0.40

1 25 Bridge

1 20 20 yr with clima 11.40 86.47 87.75 17.50 32.28 59.72 117.00 1.52 1.33 0.05 0.17 1.22 0.43 1 20 100 yr with clim 16.00 86.47 88.00 20.32 31.57 59.97 117.00 1.78 1.42 0.21 0.27 1.14 0.41 1 20 200 yr with clim 18.70 86.47 88.11 21.18 31.45 60.09 117.00 1.88 1.48 0.26 0.30 1.14 0.41

1 10 20 yr with clima 11.40 86.09 87.40 8.36 13.90 22.25 1.46 1.46 0.48 1 10 100 yr with clim 16.00 86.09 87.66 9.96 12.86 22.82 1.57 1.57 0.49 1 10 200 yr with clim 18.70 86.09 87.78 10.76 12.31 23.07 1.64 0.09 1.64 0.50

Silverstone Brook Plan: Silverstone Brook 12/10/2007 2600 Legend

2500 WS 20 yr with clima 2100 2000 WS 100 yr with clim 1900 WS 200 yr with clim 1800 Ground 1700 Bank Sta 1600 Levee 1500

1400 1300 1100 1002

940 905

800 700

500

400

230 220 200

150 100

Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Broo 1 94 Legend

WS 200 yr with clim WS 100 yr with clim WS 20 yr with clima Ground Left Levee 92

90 Elevation (m)

88 1500 1600 1700 1800 1900 2000 2100 2200 2400 2550 86 20 40 150 200 210 230 300 500 600 800 900 940 1000 1005 1200 1400 0 200 400 600 800 1000 1200 1400 1600 Main Channel Distance (m)

Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 2600 RS = 2550 Culv RS = 2550 Culv .08 .12 . .08 .12 . .12 .08 94.5 0 94.5 0 93.5 8 Legend 8 Legend Legend 94.0 WS 200 yr with clim 94.0 WS 200 yr with clim WS 200 yr with clim 93.0 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 93.5 93.5 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 92.5 93.0 Ground 93.0 Ground Ground

92.5 Bank Sta 92.5 Bank Sta Bank Sta 92.0 Elevation(m) Elevation(m) Elevation(m) 92.0 92.0 91.5 91.5 91.5

91.0 91.0 91.0 0 10 20 30 40 50 60 0 10 20 30 40 50 60 0 20 40 60 80 100 120 Station (m) Station (m) Station (m) Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 2500 RS = 2400 RS = 2300 .12 .08 . .08 . . .08 93.5 93.5 1 93.5 0 1 Legend 2 Legend 8 2 Legend

WS 200 yr with clim WS 200 yr with clim 93.0 WS 200 yr with clim 93.0 93.0 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima 92.5 WS 20 yr with clima 92.5 92.5 Ground Ground Ground 92.0 Bank Sta Bank Sta Bank Sta 92.0 92.0 Elevation(m) Elevation(m) Elevation(m) 91.5

91.5 91.5 91.0

91.0 91.0 90.5 0 20 40 60 80 100 120 0 20 40 60 80 100 120 0 20 40 60 80 100 120 140 Station (m) Station (m) Station (m) Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 2200 RS = 2100 RS = 2000 .08 . .08 .08 . .08 .08 . .08 93.5 1 94.0 1 94.0 1 2 Legend 2 Legend 2 Legend

93.0 WS 200 yr with clim 93.5 WS 200 yr with clim 93.5 WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 93.0 93.0 92.5 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima Ground 92.5 Ground 92.5 Ground 92.0 Bank Sta 92.0 Bank Sta 92.0 Bank Sta Elevation(m) Elevation(m) 91.5 Elevation(m) 91.5 91.5

91.0 91.0 91.0

90.5 90.5 90.5 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 160 180 0 50 100 150 200 Station (m) Station (m) Station (m)

Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 1900 RS = 1800 RS = 1700 .08 . .08 .08 . .08 .08 . .08 93.5 1 92.5 1 92.5 1 2 Legend 2 Legend 2 Legend

93.0 WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 92.0 92.0 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 92.5 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 91.5 91.5 Ground Ground Ground 92.0 Bank Sta Bank Sta Bank Sta 91.0 91.0 Elevation(m) 91.5 Elevation(m) Elevation(m)

90.5 90.5 91.0

90.5 90.0 90.0 0 20 40 60 80 100 120 140 160 180 0 20 40 60 80 100 120 140 160 -20 0 20 40 60 80 100 120 140 160 Station (m) Station (m) Station (m) Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 1600 RS = 1500 RS = 1400 .08 . .08 .08 . .08 .08 . .08 92.0 1 92.0 1 91.5 1 2 Legend 2 Legend 2 Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 91.5 91.0 91.5 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 91.0 90.5 Ground Ground Ground 91.0 Bank Sta Bank Sta Bank Sta 90.5 90.0 Elevation(m) Elevation(m) Elevation(m)

90.5 90.0 89.5

90.0 89.5 89.0 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160 180 0 20 40 60 80 100 120 140 160 Station (m) Station (m) Station (m) Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 1300 RS = 1200 RS = 1100 .08 . .08 .08 . .08 .08 . .08 91.5 1 91.5 1 91.5 1 2 Legend 2 Legend 2 Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 91.0 91.0 91.0 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 90.5 90.5 90.5 Ground Ground Ground Bank Sta Bank Sta Bank Sta 90.0 90.0 90.0 Elevation(m) Elevation(m) Elevation(m)

89.5 89.5 89.5

89.0 89.0 89.0 0 20 40 60 80 100 120 140 160 180 0 20 40 60 80 100 120 140 160 180 0 20 40 60 80 100 120 140 160 180 Station (m) Station (m) Station (m)

Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 1015 Culv RS = 1015 Culv RS = 1005 .08 . .08 .08 . .08 .08 . .08 92.0 1 91.5 1 91.5 1 2 Legend 2 Legend 2 Legend

91.5 WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 91.0 91.0 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 91.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 90.5 90.5 Ground Ground Ground 90.5 Bank Sta Bank Sta Bank Sta 90.0 90.0 Elevation(m) 90.0 Elevation(m) Elevation(m)

89.5 89.5 89.5

89.0 89.0 89.0 0 20 40 60 80 100 120 140 160 180 0 20 40 60 80 100 120 140 160 180 0 20 40 60 80 100 120 140 160 180 Station (m) Station (m) Station (m) Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 1002 RS = 1000 RS = 940 .08 . .08 .08 . .08 .08 . .08 91.5 1 91.5 1 91.0 1 2 Legend 2 Legend 2 Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 91.0 91.0 WS 100 yr with clim WS 100 yr with clim 90.5 WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 90.5 90.5 Ground Ground Ground 90.0 Bank Sta Bank Sta Bank Sta 90.0 90.0 Elevation(m) Elevation(m) Elevation(m)

89.5 89.5 89.5

89.0 89.0 89.0 0 50 100 150 200 0 20 40 60 80 100 120 140 160 180 0 20 40 60 80 100 120 140 160 Station (m) Station (m) Station (m) Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 930 RS = 915 BR RS = 915 BR .08 . .08 .08 . .08 .08 . .08 91.0 1 91.0 1 91.0 1 2 Legend 2 Legend 2 Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 90.5 90.5 90.5 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 90.0 90.0 90.0 Ground Ground Ground Bank Sta Bank Sta Bank Sta 89.5 89.5 89.5 Elevation(m) Elevation(m) Elevation(m)

89.0 89.0 89.0

88.5 88.5 88.5 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160 Station (m) Station (m) Station (m)

Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 905 RS = 900 RS = 800 .08 . .08 .08 . .08 .08 . .08 91.0 1 91.0 1 90.5 1 2 Legend 2 Legend 2 Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 90.5 90.5 WS 100 yr with clim WS 100 yr with clim 90.0 WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 90.0 90.0 Ground Ground Ground 89.5 Bank Sta Bank Sta Bank Sta 89.5 89.5 Elevation(m) Elevation(m) Elevation(m)

89.0 89.0 89.0

88.5 88.5 88.5 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 Station (m) Station (m) Station (m) Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 700 RS = 600 RS = 500 .08 . .08 .08 . .08 .08 . .08 90.5 1 90.5 1 90.5 1 2 Legend 2 Legend 2 Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 90.0 90.0 90.0 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 89.5 89.5 89.5 Ground Ground Ground Bank Sta Bank Sta Bank Sta 89.0 89.0 89.0 Elevation(m) Elevation(m) Elevation(m)

88.5 88.5 88.5

88.0 88.0 88.0 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 160 Station (m) Station (m) Station (m) Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 400 RS = 300 RS = 230 .08 . .08 .08 . .08 .12 .08 90.0 1 90.0 1 90.0 2 Legend 2 Legend Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 89.5 89.5 89.5 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 89.0 89.0 89.0 Ground Ground Ground Bank Sta Bank Sta Levee 88.5 88.5 88.5 Elevation(m) Elevation(m) Elevation(m) Bank Sta

88.0 88.0 88.0

87.5 87.5 87.5 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 Station (m) Station (m) Station (m)

Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 220 RS = 215 BR RS = 215 BR .12 .08 .12 .08 .08 . .08 90.0 90.0 90.0 1 Legend Legend 2 Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 89.5 89.5 89.5 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 89.0 89.0 89.0 Ground Ground Ground Levee Levee Levee 88.5 88.5 88.5

Elevation(m) Bank Sta Elevation(m) Bank Sta Elevation(m) Bank Sta

88.0 88.0 88.0

87.5 87.5 87.5 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100 Station (m) Station (m) Station (m) Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 210 RS = 200 RS = 150 .08 . .08 .08 .12 .08 .08 .12 .08 90.0 1 89.5 89.5 2 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim 89.0 WS 200 yr with clim 89.5 89.0 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima 88.5 WS 20 yr with clima 89.0 88.5 Ground Ground Ground 88.0 Levee Levee Levee 88.5 88.0 Elevation(m) Elevation(m) Bank Sta Elevation(m) Bank Sta 87.5 Bank Sta

88.0 87.5 87.0

87.5 87.0 86.5 0 20 40 60 80 100 0 20 40 60 80 100 0 10 20 30 40 50 60 70 80 Station (m) Station (m) Station (m) Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 100 RS = 50 RS = 40 .08 .12 .08 .08 . .08 . .035 .08 89.5 89.5 0 89.5 0 Legend 3 Legend 8 Legend 5 89.0 WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 89.0 89.0 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 88.5 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 88.5 88.5 Ground Ground Ground 88.0 Levee Levee Bank Sta 88.0 88.0 Elevation(m) Elevation(m) 87.5 Bank Sta Elevation(m) Bank Sta

87.5 87.5 87.0

86.5 87.0 87.0 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 Station (m) Station (m) Station (m)

Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 30 RS = 25 BR RS = 25 BR .08 .035 .08 .08 .035 .08 .08 .035 .08 90.0 90.0 90.0 Legend Legend Legend

89.5 WS 200 yr with clim 89.5 WS 200 yr with clim 89.5 WS 200 yr with clim

WS 100 yr with clim WS 100 yr with clim 89.0 WS 100 yr with clim 89.0 89.0 WS 20 yr with clima WS 20 yr with clima 88.5 WS 20 yr with clima 88.5 Ground 88.5 Ground Ground 88.0 88.0 Bank Sta 88.0 Bank Sta Bank Sta 87.5 Elevation(m) Elevation(m) Elevation(m) 87.5 87.5 87.0

87.0 87.0 86.5

86.5 86.5 86.0 0 20 40 60 80 0 20 40 60 80 0 20 40 60 80 Station (m) Station (m) Station (m) Silverstone Brook Plan: Silverstone Brook 12/10/2007 Silverstone Brook Plan: Silverstone Brook 12/10/2007 RS = 20 Chainage 1.3km Cross-Section Provided by the EA RS = 10 .08 .035 .08 .08 .035 .08 90.0 88.5 Legend Legend

89.5 WS 200 yr with clim WS 200 yr with clim 88.0 89.0 WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima 88.5 87.5 Ground Ground 88.0 Bank Sta Bank Sta 87.5 87.0 Elevation(m) Elevation(m)

87.0 86.5 86.5

86.0 86.0 0 20 40 60 80 5 10 15 20 25 30 Station (m) Station (m)

HEC-RAS Plan: WBB River: Wood Burcote Bro Reach: 1 Reach River Sta Profile Q Total Min Ch El W.S. Elev Top Width Sta W.S. Lft Sta W.S. Rgt Cum Ch Len SA Total Vel Chnl Vel Left Vel Right Vel Total Froude # Chl (m3/s) (m) (m) (m) (m) (m) (m) (1000 m2) (m/s) (m/s) (m/s) (m/s) 1 2600 20 yr with clima 1.80 113.50 114.29 13.00 9.71 22.71 1597.90 13.75 0.71 0.47 0.22 0.62 0.31 1 2600 100 yr with clim 2.60 113.50 114.39 19.64 8.47 28.11 1597.90 17.94 0.72 0.51 0.32 0.59 0.29 1 2600 200 yr with clim 3.10 113.50 114.42 22.18 7.99 30.17 1597.90 19.95 0.75 0.55 0.36 0.60 0.30

1 2500 20 yr with clima 1.80 112.60 113.51 14.29 4.43 29.41 1558.90 13.25 0.73 0.09 0.71 0.33 1 2500 100 yr with clim 2.60 112.60 113.56 21.56 4.32 30.89 1558.90 17.20 0.90 0.27 0.77 0.40 1 2500 200 yr with clim 3.10 112.60 113.59 26.42 4.25 31.88 1558.90 19.09 0.94 0.34 0.75 0.41

1 2400 20 yr with clima 1.80 111.80 112.69 17.05 16.02 33.07 1505.40 12.53 0.58 0.35 0.48 0.25 1 2400 100 yr with clim 2.60 111.80 112.78 25.97 11.60 37.57 1505.40 16.11 0.56 0.15 0.38 0.45 0.23 1 2400 200 yr with clim 3.10 111.80 112.82 29.53 9.73 39.25 1505.40 17.81 0.58 0.18 0.40 0.46 0.23

1 2300 20 yr with clima 1.80 110.70 111.59 15.21 9.88 25.09 1411.40 10.91 0.57 0.29 0.27 0.48 0.24 1 2300 100 yr with clim 2.60 110.70 111.63 16.95 8.89 25.83 1411.40 13.98 0.71 0.40 0.36 0.59 0.29 1 2300 200 yr with clim 3.10 110.70 111.67 18.57 7.96 26.53 1411.40 15.42 0.74 0.44 0.40 0.61 0.29

1 2200 20 yr with clima 1.80 110.00 111.05 15.83 8.55 24.39 1362.90 10.12 0.59 0.18 0.53 0.25 1 2200 100 yr with clim 2.60 110.00 111.22 21.26 5.33 26.59 1362.90 13.01 0.48 0.30 0.14 0.40 0.18 1 2200 200 yr with clim 3.10 110.00 111.27 23.03 4.41 27.44 1362.90 14.37 0.49 0.33 0.17 0.41 0.18

1 2120 20 yr with clima 1.80 109.80 110.88 9.21 19.59 28.80 1349.90 9.97 0.66 0.17 0.62 0.27 1 2120 100 yr with clim 2.60 109.80 111.17 23.87 8.31 32.18 1349.90 12.73 0.41 0.26 0.14 0.33 0.14 1 2120 200 yr with clim 3.10 109.80 111.22 26.08 7.06 33.14 1349.90 14.07 0.42 0.29 0.16 0.34 0.14

1 2115 Bridge

1 2110 20 yr with clima 1.80 109.60 110.47 4.25 19.76 24.01 1336.40 9.91 0.87 0.87 0.40 1 2110 100 yr with clim 2.60 109.60 110.63 6.54 17.84 24.39 1336.40 12.57 0.92 0.14 0.91 0.39 1 2110 200 yr with clim 3.10 109.60 110.71 10.48 14.08 24.56 1336.40 13.87 0.94 0.30 0.88 0.38

1 2100 20 yr with clima 1.80 108.20 109.27 4.06 11.35 15.41 1275.40 9.66 0.66 0.66 0.26 1 2100 100 yr with clim 2.60 108.20 109.45 4.58 11.16 15.74 1275.40 12.23 0.74 0.74 0.27 1 2100 200 yr with clim 3.10 108.20 109.55 4.85 11.05 15.91 1275.40 13.40 0.78 0.78 0.28

1 2000 20 yr with clima 1.80 107.80 108.71 4.34 9.61 13.94 1240.90 9.52 0.74 0.74 0.32 1 2000 100 yr with clim 2.60 107.80 108.87 4.93 9.36 14.29 1240.90 12.06 0.82 0.82 0.33 1 2000 200 yr with clim 3.10 107.80 108.95 5.25 9.22 14.47 1240.90 13.23 0.86 0.86 0.33

1 1900 20 yr with clima 1.80 106.30 107.44 4.36 6.32 10.68 1161.90 9.17 0.65 0.65 0.26 1 1900 100 yr with clim 2.60 106.30 107.66 5.08 6.01 11.08 1161.90 11.67 0.69 0.69 0.25 1 1900 200 yr with clim 3.10 106.30 107.77 5.45 5.84 11.29 1161.90 12.80 0.71 0.71 0.25

1 1800 20 yr with clima 1.80 105.60 106.84 3.47 7.41 10.87 1112.90 8.98 0.65 0.65 0.23 1 1800 100 yr with clim 2.60 105.60 106.98 3.75 7.28 11.03 1112.90 11.45 0.79 0.79 0.27 1 1800 200 yr with clim 3.10 105.60 107.06 3.91 7.21 11.12 1112.90 12.57 0.87 0.87 0.29

1 1720 20 yr with clima 1.80 105.10 106.67 12.80 7.18 19.98 1065.90 8.60 0.31 0.14 0.29 0.10 1 1720 100 yr with clim 2.60 105.10 106.75 16.03 5.55 21.59 1065.90 10.99 0.40 0.20 0.05 0.35 0.12 1 1720 200 yr with clim 3.10 105.10 106.77 17.53 4.95 22.49 1065.90 12.07 0.45 0.24 0.08 0.40 0.14

1 1715 Culvert

1 1710 20 yr with clima 1.80 104.40 105.34 5.30 15.77 21.07 1048.40 8.45 0.53 0.53 0.21 1 1710 100 yr with clim 2.60 104.40 105.54 6.00 15.40 21.40 1048.40 10.80 0.57 0.57 0.21 1 1710 200 yr with clim 3.10 104.40 105.65 6.39 15.20 21.58 1048.40 11.87 0.59 0.59 0.21

1 1700 20 yr with clima 1.80 104.10 104.99 3.49 2.69 6.18 1021.90 8.34 0.81 0.81 0.33 1 1700 100 yr with clim 2.60 104.10 105.21 4.00 2.49 6.48 1021.90 10.67 0.85 0.85 0.31 1 1700 200 yr with clim 3.10 104.10 105.33 4.26 2.38 6.64 1021.90 11.73 0.87 0.87 0.31

1 1600 20 yr with clima 1.80 102.50 103.61 4.08 5.03 9.11 934.90 8.01 0.64 0.64 0.24 1 1600 100 yr with clim 2.60 102.50 103.75 4.47 4.79 9.25 934.90 10.30 0.76 0.76 0.28 1 1600 200 yr with clim 3.10 102.50 103.83 4.68 4.65 9.33 934.90 11.34 0.82 0.82 0.29

1 1500 20 yr with clima 1.80 101.60 102.46 4.10 2.31 6.41 867.40 7.73 0.82 0.82 0.36 1 1500 100 yr with clim 2.60 101.60 102.68 7.59 2.00 9.58 867.40 9.89 0.79 0.33 0.76 0.30 1 1500 200 yr with clim 3.10 101.60 102.77 9.23 1.87 11.11 867.40 10.86 0.80 0.41 0.74 0.29

1 1420 20 yr with clima 1.80 101.10 102.06 3.81 12.13 15.94 849.90 7.66 0.78 0.78 0.32 1 1420 100 yr with clim 2.60 101.10 102.46 7.17 11.55 18.73 849.90 9.77 0.58 0.58 0.23 1 1420 200 yr with clim 3.10 101.10 102.60 9.79 11.31 21.10 849.90 10.72 0.56 0.14 0.15 0.56 0.21

1 1415 Bridge

1 1410 20 yr with clima 1.80 100.80 101.75 4.47 13.52 17.99 836.40 7.61 0.69 0.69 0.29 1 1410 100 yr with clim 2.60 100.80 101.96 5.23 13.08 18.31 836.40 9.74 0.72 0.72 0.28 1 1410 200 yr with clim 3.10 100.80 102.06 6.15 12.31 18.46 836.40 10.65 0.75 0.14 0.75 0.27

1 1400 20 yr with clima 1.80 99.90 101.14 5.95 9.83 15.78 770.90 7.27 0.50 0.08 0.49 0.18 1 1400 100 yr with clim 2.60 99.90 101.22 8.07 7.81 15.88 770.90 9.30 0.64 0.18 0.62 0.23 1 1400 200 yr with clim 3.10 99.90 101.26 9.47 6.48 15.95 770.90 10.13 0.71 0.25 0.67 0.25

1 1380 20 yr with clima 1.80 99.60 101.13 12.35 12.67 25.02 762.40 7.17 0.27 0.07 0.07 0.26 0.09 1 1380 100 yr with clim 2.60 99.60 101.19 15.07 10.47 25.54 762.40 9.17 0.36 0.12 0.12 0.34 0.12 1 1380 200 yr with clim 3.10 99.60 101.24 16.92 8.97 25.89 762.40 9.97 0.40 0.15 0.15 0.37 0.13

1 1350 Culvert

1 1300 20 yr with clima 1.80 99.20 99.92 4.54 27.69 32.23 711.90 6.74 0.93 0.93 0.45 1 1300 100 yr with clim 2.60 99.20 100.09 6.20 27.27 33.46 711.90 8.63 0.91 0.91 0.43 1 1300 200 yr with clim 3.10 99.20 100.18 6.83 27.06 33.88 711.90 9.37 0.91 0.91 0.41

1 1200 20 yr with clima 1.80 98.40 99.34 8.75 12.37 21.12 659.90 6.40 0.39 0.39 0.17 1 1200 100 yr with clim 2.60 98.40 99.45 9.52 11.97 21.49 659.90 8.22 0.46 0.46 0.19 1 1200 200 yr with clim 3.10 98.40 99.50 9.87 11.79 21.66 659.90 8.94 0.51 0.51 0.21

1 1100 20 yr with clima 1.80 98.00 98.92 13.40 4.59 18.00 614.40 5.91 0.71 0.24 0.63 0.30 1 1100 100 yr with clim 2.60 98.00 99.02 26.17 4.43 30.60 614.40 7.46 0.71 0.31 0.54 0.28 1 1100 200 yr with clim 3.10 98.00 99.05 26.39 4.38 30.77 614.40 8.16 0.71 0.37 0.54 0.27

1 1010 20 yr with clima 1.80 97.10 98.17 19.03 24.83 43.86 550.40 5.01 0.61 0.30 0.36 0.44 0.20 1 1010 100 yr with clim 2.60 97.10 98.21 22.21 22.13 44.33 550.40 6.10 0.73 0.38 0.46 0.53 0.24 1 1010 200 yr with clim 3.10 97.10 98.24 24.27 20.37 44.64 550.40 6.74 0.77 0.42 0.50 0.55 0.25

1 1005 Culvert

1 1000 20 yr with clima 1.80 97.00 97.86 24.65 20.19 44.84 528.40 4.28 0.56 0.32 0.23 0.41 0.22 1 1000 100 yr with clim 2.60 97.00 97.89 27.51 17.70 45.21 528.40 5.27 0.69 0.41 0.31 0.50 0.26 1 1000 200 yr with clim 3.10 97.00 97.92 30.56 15.05 45.60 528.40 5.83 0.69 0.43 0.33 0.50 0.26

1 900 20 yr with clima 1.80 96.40 96.83 7.78 52.18 59.96 476.90 3.57 0.87 0.87 0.54 HEC-RAS Plan: WBB River: Wood Burcote Bro Reach: 1 (Continued) Reach River Sta Profile Q Total Min Ch El W.S. Elev Top Width Sta W.S. Lft Sta W.S. Rgt Cum Ch Len SA Total Vel Chnl Vel Left Vel Right Vel Total Froude # Chl (m3/s) (m) (m) (m) (m) (m) (m) (1000 m2) (m/s) (m/s) (m/s) (m/s) 1 900 100 yr with clim 2.60 96.40 97.03 10.61 51.29 61.90 476.90 4.43 0.65 0.65 0.34 1 900 200 yr with clim 3.10 96.40 97.08 11.19 51.10 62.30 476.90 4.90 0.69 0.69 0.35

1 820 20 yr with clima 1.80 95.20 96.80 12.13 43.62 55.76 439.90 3.20 0.16 0.16 0.05 1 820 100 yr with clim 2.60 95.20 96.99 31.25 25.53 56.78 439.90 3.86 0.19 0.04 0.04 0.18 0.06 1 820 200 yr with clim 3.10 95.20 97.02 33.62 23.33 56.95 439.90 4.31 0.21 0.05 0.05 0.20 0.06

1 815 Culvert

1 810 20 yr with clima 1.80 95.20 96.36 3.44 33.79 37.23 423.90 3.08 0.70 0.70 0.26 1 810 100 yr with clim 2.60 95.20 96.57 3.87 33.49 37.35 423.90 3.58 0.78 0.78 0.27 1 810 200 yr with clim 3.10 95.20 96.68 4.10 33.33 37.42 423.90 4.01 0.82 0.82 0.27

1 800 20 yr with clima 1.80 94.40 95.22 4.33 19.50 23.83 364.90 2.85 0.82 0.82 0.37 1 800 100 yr with clim 2.60 94.40 95.37 4.91 19.24 24.15 364.90 3.32 0.91 0.91 0.38 1 800 200 yr with clim 3.10 94.40 95.44 5.19 19.12 24.30 364.90 3.74 0.97 0.97 0.39

1 700 20 yr with clima 1.80 93.50 94.64 7.62 32.32 39.95 316.40 2.56 0.52 0.18 0.50 0.20 1 700 100 yr with clim 2.60 93.50 94.80 11.17 32.09 43.26 316.40 2.94 0.56 0.29 0.51 0.20 1 700 200 yr with clim 3.10 93.50 94.87 12.87 31.98 44.85 316.40 3.30 0.58 0.33 0.52 0.20

1 600 20 yr with clima 1.80 93.20 93.95 3.89 21.56 25.44 260.40 2.25 0.81 0.81 0.34 1 600 100 yr with clim 2.60 93.20 94.04 4.10 21.45 25.55 260.40 2.52 1.02 1.02 0.41 1 600 200 yr with clim 3.10 93.20 94.08 4.20 21.40 25.60 260.40 2.84 1.13 1.13 0.45

1 500 20 yr with clima 1.80 92.50 93.61 14.38 31.09 45.47 225.40 1.98 0.47 0.34 0.41 0.18 1 500 100 yr with clim 2.60 92.50 93.74 18.25 27.40 45.65 225.40 2.20 0.45 0.36 0.40 0.16 1 500 200 yr with clim 3.10 92.50 93.80 20.19 25.54 45.74 225.40 2.49 0.44 0.37 0.40 0.15

1 400 20 yr with clima 1.80 92.30 93.39 5.20 6.75 11.95 204.40 1.65 0.60 0.26 0.59 0.22 1 400 100 yr with clim 2.60 92.30 93.52 6.36 6.55 12.91 204.40 1.78 0.72 0.40 0.69 0.25 1 400 200 yr with clim 3.10 92.30 93.59 11.95 1.47 13.42 204.40 1.92 0.77 0.10 0.46 0.71 0.26

1 300 20 yr with clima 1.80 91.90 93.28 8.61 0.25 8.86 183.90 1.51 0.44 0.13 0.13 0.42 0.15 1 300 100 yr with clim 2.60 91.90 93.37 10.42 0.00 10.42 183.90 1.61 0.54 0.25 0.22 0.50 0.17 1 300 200 yr with clim 3.10 91.90 93.43 11.39 0.00 11.39 183.90 1.69 0.59 0.32 0.26 0.53 0.18

1 275 Culvert

1 250 20 yr with clima 1.80 91.60 92.57 5.62 1.38 7.01 164.90 1.39 0.49 0.49 0.19 1 250 100 yr with clim 2.60 91.60 92.72 6.18 1.14 7.31 164.90 1.48 0.57 0.57 0.21 1 250 200 yr with clim 3.10 91.60 92.80 6.47 1.01 7.48 164.90 1.54 0.61 0.61 0.22

1 200 20 yr with clima 1.80 91.20 92.49 5.37 2.56 7.92 150.90 1.31 0.44 0.44 0.16 1 200 100 yr with clim 2.60 91.20 92.62 5.98 2.22 8.20 150.90 1.39 0.54 0.04 0.54 0.19 1 200 200 yr with clim 3.10 91.20 92.69 6.93 2.03 8.96 150.90 1.45 0.59 0.13 0.59 0.20

1 100 20 yr with clima 1.80 91.10 92.36 8.50 0.00 8.50 119.90 1.09 0.43 0.21 0.11 0.41 0.14 1 100 100 yr with clim 2.60 91.10 92.43 9.70 0.00 9.70 119.90 1.14 0.56 0.33 0.19 0.52 0.18 1 100 200 yr with clim 3.10 91.10 92.47 10.39 0.00 10.39 119.90 1.17 0.62 0.40 0.23 0.57 0.20

1 50 20 yr with clima 1.80 91.00 92.36 13.76 0.00 13.76 109.70 0.98 0.19 0.18 0.07 0.18 0.06 1 50 100 yr with clim 2.60 91.00 92.42 14.33 0.00 14.33 109.70 1.02 0.25 0.24 0.10 0.24 0.07 1 50 200 yr with clim 3.10 91.00 92.46 14.65 0.00 14.65 109.70 1.04 0.28 0.28 0.12 0.27 0.08

1 40 20 yr with clima 1.80 92.13 92.27 12.67 0.00 12.67 98.80 0.84 1.05 1.36 0.99 1.11 0.90 1 40 100 yr with clim 2.60 92.13 92.31 12.91 0.00 12.91 98.80 0.87 1.16 1.53 1.09 1.24 0.88 1 40 200 yr with clim 3.10 92.13 92.33 13.04 0.00 13.04 98.80 0.89 1.23 1.64 1.16 1.32 0.89

1 30 20 yr with clima 1.80 90.40 91.88 8.04 4.81 12.85 78.60 0.63 0.24 0.24 0.08 1 30 100 yr with clim 2.60 90.40 91.94 8.27 4.71 12.98 78.60 0.66 0.33 0.33 0.11 1 30 200 yr with clim 3.10 90.40 91.97 8.41 4.65 13.05 78.60 0.67 0.38 0.38 0.12

1 20 20 yr with clima 1.80 90.06 91.87 13.32 0.00 13.32 71.00 0.53 0.49 0.25 0.22 0.37 0.12 1 20 100 yr with clim 2.60 90.06 91.93 13.85 0.00 13.85 71.00 0.55 0.61 0.36 0.30 0.47 0.14 1 20 200 yr with clim 3.10 90.06 91.96 14.15 0.00 14.15 71.00 0.56 0.67 0.42 0.35 0.52 0.16

1 15 Culvert

1 10 20 yr with clima 1.80 88.75 89.45 1.20 27.20 28.40 2.15 2.15 0.82 1 10 100 yr with clim 2.60 88.75 89.68 1.20 27.20 28.40 2.33 2.33 0.77 1 10 200 yr with clim 3.10 88.75 89.82 1.20 27.20 28.40 2.42 2.42 0.75

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Legend 2500 2400 WS 20 yr with clima WS 100 yr with clim 2300 WS 200 yr with clim 2200 Ground

2100 Bank Sta 2000 Levee

1900 1800 1720 1700

1600

1500

1400 1300 1200 1100 1010

900 820

800 700

600

400 250 100 30

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Bro 1 115 Legend

WS 200 yr with clim WS 100 yr with clim WS 20 yr with clima 110 Ground Left Levee

105

100 Elevation (m)

90 1700 1710 1800 1900 2000 2100 2110 2200 2300 2400 2500 2600 85 15 40 200 275 400 600 700 800 810 900 1000 1100 1200 1300 1350 1410 1500 1600 0 200 400 600 800 1000 1200 1400 1600 Main Channel Distance (m)

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 2600 RS = 2500 RS = 2400 .08 .12 .08 .08 .12 .08 .08 .12 .08 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 114.8 113.8 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 112.8 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 114.6 Ground 113.6 Ground Ground

Bank Sta Bank Sta 112.6 Bank Sta 114.4 113.4

114.2 113.2 112.4 Elevation(m) Elevation(m) Elevation(m) 114.0 113.0 112.2

113.8 112.8

112.0 113.6 112.6

113.4 112.4 111.8 0 10 20 30 40 50 0 10 20 30 40 50 0 10 20 30 40 50 Station (m) Station (m) Station (m) Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 2300 RS = 2200 RS = 2120 .08 .12 .08 .08 .12 .08 .08 .12 .08 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 111.4 111.4 111.8 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 111.2 Ground 111.2 Ground Ground 111.6 Bank Sta Bank Sta 111.0 Bank Sta 111.0 111.4 110.8 110.8 110.6 111.2 Elevation(m) Elevation(m) Elevation(m) 110.6 110.4 111.0 110.4 110.2

110.8 110.2 110.0

110.6 110.0 109.8 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 10 20 30 40 Station (m) Station (m) Station (m)

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 2115 BR RS = 2115 BR RS = 2110 .08 .12 .08 .08 .12 .08 .08 .12 .08 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 111.4 110.8 110.8 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 111.2 Ground 110.6 Ground 110.6 Ground

111.0 Bank Sta Bank Sta Bank Sta 110.4 110.4

110.8 110.2 110.2 110.6 Elevation(m) Elevation(m) Elevation(m) 110.0 110.0 110.4

109.8 109.8 110.2

110.0 109.6 109.6

109.8 109.4 109.4 0 10 20 30 40 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Station (m) Station (m) Station (m) Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 2100 RS = 2000 RS = 1900 .08 .12 .08 .08 .12 .08 .08 .12 .08 110.0 108.5 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 109.4 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima 108.0 WS 20 yr with clima 109.2 109.5 Ground Ground Ground

Bank Sta 109.0 Bank Sta Bank Sta

107.5 108.8 109.0 108.6 Elevation(m) Elevation(m) Elevation(m) 107.0

108.4

108.5 108.2 106.5

108.0

108.0 107.8 106.0 0 5 10 15 20 25 0 5 10 15 20 25 0 5 10 15 20 Station (m) Station (m) Station (m)

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 1800 RS = 1720 RS = 1715 Culv .08 .12 .08 .08 .12 .08 .08 .12 .08 107.5 107.0 107.0 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 107.0 Ground 106.5 Ground 106.5 Ground Bank Sta Bank Sta Bank Sta

106.5 106.0 106.0 Elevation(m) Elevation(m) Elevation(m)

106.0 105.5 105.5

105.5 105.0 105.0 0 2 4 6 8 10 12 14 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Station (m) Station (m) Station (m) Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 1715 Culv RS = 1710 RS = 1700 .08 .12 .08 .08 .12 .08 . .12 .08 107.0 107.0 106.5 0 Legend Legend 8 Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 106.5 106.5 WS 20 yr with clima WS 20 yr with clima 106.0 WS 20 yr with clima Ground Ground Ground

106.0 Bank Sta 106.0 Bank Sta Bank Sta

105.5

105.5 105.5 Elevation(m) Elevation(m) Elevation(m) 105.0

105.0 105.0

104.5 104.5 104.5

104.0 104.0 104.0 0 10 20 30 40 0 10 20 30 40 0 5 10 15 20 25 30 35 Station (m) Station (m) Station (m)

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 1600 RS = 1500 RS = 1420 .08 .12 .08 . .12 .08 .08 .12 .08 104.5 103.5 0 103.5 Legend 8 Legend Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima 103.0 WS 20 yr with clima 104.0 Ground 103.0 Ground Ground Bank Sta Bank Sta Bank Sta

102.5

103.5 102.5 Elevation(m) Elevation(m) Elevation(m) 102.0

103.0 102.0 101.5

102.5 101.5 101.0 0 5 10 15 20 0 5 10 15 20 25 0 5 10 15 20 25 30 35 40 Station (m) Station (m) Station (m) Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 1415 BR RS = 1415 BR RS = 1410 .08 .12 .08 .08 .12 .08 .08 .12 .08 103.5 103.0 103.0 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 103.0 WS 20 yr with clima 102.5 WS 20 yr with clima 102.5 WS 20 yr with clima Ground Ground Ground Bank Sta Bank Sta Bank Sta

102.5 102.0 102.0 Elevation(m) Elevation(m) 102.0 Elevation(m) 101.5 101.5

101.5 101.0 101.0

101.0 100.5 100.5 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Station (m) Station (m) Station (m)

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 1400 RS = 1380 RS = 1350 Culv .08 .12 .08 .08 .12 .08 .08 .12 .08 101.5 101.5 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 101.4 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 101.2 Ground 101.0 Ground 101.0 Ground

101.0 Bank Sta Bank Sta Bank Sta

100.8 100.5 100.5 100.6 Elevation(m) Elevation(m) Elevation(m)

100.4

100.0 100.0 100.2

100.0

99.8 99.5 99.5 0 5 10 15 20 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Station (m) Station (m) Station (m) Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 1350 Culv RS = 1300 RS = 1200 .08 .12 .08 .08 .12 .08 .08 .12 .08 101.5 101.5 100.5 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 101.0 WS 20 yr with clima 101.0 WS 20 yr with clima 100.0 WS 20 yr with clima Ground Ground Ground Bank Sta Bank Sta Bank Sta

100.5 100.5 99.5 Elevation(m) Elevation(m) 100.0 Elevation(m) 100.0 99.0

99.5 99.5 98.5

99.0 99.0 98.0 0 10 20 30 40 50 0 10 20 30 40 50 0 5 10 15 20 25 30 35 Station (m) Station (m) Station (m)

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 1100 RS = 1010 RS = 1005 Culv .08 .12 .08 .08 . .08 .08 . .08 99.0 1 99.0 1 Legend 2 Legend 2 Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 99.4 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 99.2 Ground 98.5 Ground 98.5 Ground Bank Sta Bank Sta Bank Sta 99.0

98.8 98.0 98.0 Elevation(m) Elevation(m) Elevation(m) 98.6

98.4 97.5 97.5

98.2

98.0 97.0 97.0 0 5 10 15 20 25 30 35 0 10 20 30 40 50 60 0 10 20 30 40 50 60 Station (m) Station (m) Station (m) Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 1005 Culv RS = 1000 RS = 900 .08 . .08 .08 . .08 .08 .12 .08 1 1 101 2 Legend 2 Legend Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim 98.4 98.4 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima 100 WS 20 yr with clima 98.2 Ground 98.2 Ground Ground Bank Sta Bank Sta Bank Sta 98.0 98.0 99

97.8 97.8 Elevation(m) Elevation(m) Elevation(m) 98 97.6 97.6

97.4 97.4 97

97.2 97.2

97.0 97.0 96 0 10 20 30 40 50 60 0 10 20 30 40 50 60 0 20 40 60 80 100 Station (m) Station (m) Station (m)

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 820 RS = 815 Culv RS = 815 Culv .08 .12 .08 .08 .12 .08 .08 .12 .08 98.0 98.0 97.5 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 97.5 97.5 WS 20 yr with clima WS 20 yr with clima 97.0 WS 20 yr with clima Ground Ground Ground

97.0 Bank Sta 97.0 Bank Sta Bank Sta

96.5

96.5 96.5 Elevation(m) Elevation(m) Elevation(m) 96.0

96.0 96.0

95.5 95.5 95.5

95.0 95.0 95.0 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 0 10 20 30 40 50 Station (m) Station (m) Station (m) Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 810 RS = 800 RS = 700 .08 .12 .08 .08 .12 .08 .08 .12 .08 97.5 96.5 96.0 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 97.0 WS 20 yr with clima 96.0 WS 20 yr with clima 95.5 WS 20 yr with clima Ground Ground Ground Bank Sta Bank Sta Bank Sta

96.5 95.5 95.0 Elevation(m) Elevation(m) 96.0 Elevation(m) 95.0 94.5

95.5 94.5 94.0

95.0 94.0 93.5 0 10 20 30 40 50 0 5 10 15 20 25 30 35 0 10 20 30 40 50 60 Station (m) Station (m) Station (m)

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 600 RS = 500 RS = 400 .08 .12 .08 .08 . .08 .08 .12 .08 96.0 95.5 1 95.0 Legend 2 Legend Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 95.5 95.0 94.5 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima Ground Ground Ground

95.0 Bank Sta 94.5 Bank Sta 94.0 Bank Sta

94.5 94.0 93.5 Elevation(m) Elevation(m) Elevation(m)

94.0 93.5 93.0

93.5 93.0 92.5

93.0 92.5 92.0 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 0 5 10 15 20 25 30 35 Station (m) Station (m) Station (m) Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 300 RS = 275 Culv RS = 275 Culv . .12 .08 . .12 .08 .12 .08 94.5 0 94.5 0 94.5 8 Legend 8 Legend Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 94.0 94.0 94.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima Ground Ground Ground

93.5 Levee 93.5 Levee 93.5 Levee Bank Sta Bank Sta Bank Sta

93.0 93.0 93.0 Elevation(m) Elevation(m) Elevation(m)

92.5 92.5 92.5

92.0 92.0 92.0

91.5 91.5 91.5 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 Station (m) Station (m) Station (m)

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 250 RS = 200 RS = 100 .12 .08 .08 .12 .08 .08 .12 .08 94.5 94.5 93.0 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim 94.0 WS 100 yr with clim WS 100 yr with clim 94.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima Ground Ground 92.5 Ground 93.5 93.5 Levee Bank Sta Levee Bank Sta Bank Sta 93.0

93.0 92.0

92.5 Elevation(m) Elevation(m) Elevation(m)

92.5 92.0 91.5

92.0 91.5

91.5 91.0 91.0 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 0 5 10 15 20 Station (m) Station (m) Station (m) Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 50 RS = 40 RS = 30 .08 .12 .08 .08 .12 .08 .03 .08 .03 93.0 93.0 92.5 Legend Legend Legend

WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima 92.0 WS 20 yr with clima 92.5 Ground 92.5 Ground Ground Levee Levee Bank Sta Bank Sta Bank Sta 91.5

92.0 92.0 Elevation(m) Elevation(m) Elevation(m) 91.0

91.5 91.5 90.5

91.0 91.0 90.0 0 5 10 15 20 0 2 4 6 8 10 12 14 16 18 0 2 4 6 8 10 12 14 16 18 Station (m) Station (m) Station (m)

Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 20 RS = 15 Culv RS = 15 Culv .03 . .03 .03 . .03 .03 . .03 92.5 0 92.5 0 92.0 0 3 Legend 3 Legend 3 Legend WS 200 yr with clim WS 200 yr with clim WS 200 yr with clim WS 100 yr with clim WS 100 yr with clim 91.5 WS 100 yr with clim 92.0 WS 20 yr with clima 92.0 WS 20 yr with clima WS 20 yr with clima Ground Ground Ground 91.0 Bank Sta Bank Sta Bank Sta

91.5 91.5 90.5

90.0 Elevation(m) Elevation(m) Elevation(m) 91.0 91.0

89.5

90.5 90.5 89.0

90.0 90.0 88.5 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 10 20 30 40 50 60 Station (m) Station (m) Station (m) Wood Burcote Brook Plan: Wood Burcote Brook 12/10/2007 RS = 10 .03 . .03 92.0 0 3 Legend WS 200 yr with clim 91.5 WS 100 yr with clim WS 20 yr with clima Ground 91.0 Bank Sta

90.5

90.0 Elevation(m)

89.5

89.0

88.5 0 10 20 30 40 50 60 Station (m) Towcester Vale Flood Risk Assessment

Appendix F - WinDes Program Output Results for Greenfield Runoff Rates and Volumes

Persimmon Homes Midlands Ltd\44406876 Towcester EIA\BDRP0007/FB/FB Revision 1 November 2007 BDRP0007

URS Corporation Ltd Page 1 URS House Horne Lane Bedford MK40 1TS Date 11 October 2007 17:21 Designed By Florian_Baltoi File Checked By Micro Drainage Source Control W.10.4

ICP SUDS Mean Annual Flood

Input

Return Period (years) 100 SAAR (mm) 700.000 Urban 0.000 Area (Ha) 63.200 Soil 0.450 Region Number 5

Results l/s

QBAR Rural 270.6 QBAR Urban 270.6

Q 100 years 963.3

Q 1 year 235.4 Q 30 years 650.1 Q 100 years 963.3

(c)1982-2006 Micro Drainage URS Corporation Ltd Page 1 URS House Horne Lane Bedford MK40 1TS Date 18 October 2007 17:39 Designed By Florian_Baltoi File Area 1.SRC Checked By Micro Drainage Source Control W.10.4

Summary of Results for 100 year Return Period

Critical storm not identified, please run longer storm durations.

Storm Maximum Maximum Maximum Maximum Maximum Duration Control Outflow Water Level Depth Volume Status (mins) (l/s) (l/s) (m OD) (m) (m³)

360 Summer 0.0 0.0 0.2817 0.2817 17799.6 O K 360 Winter 0.0 0.0 0.2817 0.2817 17799.6 O K

Storm Rain Time-Peak Duration (mm/hr) (mins) (mins)

360 Summer 10.04 838 360 Winter 10.04 838

(c)1982-2006 Micro Drainage URS Corporation Ltd Page 2 URS House Horne Lane Bedford MK40 1TS Date 18 October 2007 17:39 Designed By Florian_Baltoi File Area 1.SRC Checked By Micro Drainage Source Control W.10.4

Rainfall Details

Region ENG+WAL Cv (Summer) 0.750 Summer Storms Yes Return Period (years) 100 Cv (Winter) 0.840 Winter Storms Yes M5-60 (mm) 20.100 Shortest Storm (mins) 360 Climate Change % +0 Ratio-R 0.444 Longest Storm (mins) 360

Time / Area Diagram

Total Area (ha) = 0.000

Time (mins) Area from: to: (ha)

0 4 0.000

ICP SUDS Mean Annual Flood

Input

Return Period (years) 100 SAAR (mm) 700.000 Urban 0.000 Area (Ha) 105.200 Soil 0.450 Region Number 5

Results l/s

QBAR Rural 425.8 QBAR Urban 425.8

Q 100 years 1516.0

Q 1 year 370.5 Q 30 years 1023.1 Q 100 years 1516.0

(c)1982-2006 Micro Drainage URS Corporation Ltd Page 1 URS House Horne Lane Bedford MK40 1TS Date 18 October 2007 17:45 Designed By Florian_Baltoi File Area 2.SRC Checked By Micro Drainage Source Control W.10.4

Summary of Results for 100 year Return Period

Critical storm not identified, please run longer storm durations.

Storm Maximum Maximum Maximum Maximum Maximum Duration Control Outflow Water Level Depth Volume Status (mins) (l/s) (l/s) (m OD) (m) (m³)

360 Summer 0.0 0.0 0.2822 0.2822 29671.9 O K 360 Winter 0.0 0.0 0.2822 0.2822 29671.9 O K

Storm Rain Time-Peak Duration (mm/hr) (mins) (mins)

360 Summer 10.04 882 360 Winter 10.04 882

(c)1982-2006 Micro Drainage URS Corporation Ltd Page 2 URS House Horne Lane Bedford MK40 1TS Date 18 October 2007 17:45 Designed By Florian_Baltoi File Area 2.SRC Checked By Micro Drainage Source Control W.10.4

Rainfall Details

Time / Area Diagram

Total Area (ha) = 0.000

Time (mins) Area from: to: (ha)

0 4 0.000

ICP SUDS Mean Annual Flood

Input

Return Period (years) 100 SAAR (mm) 700.000 Urban 0.000 Area (Ha) 31.300 Soil 0.450 Region Number 5

Results l/s

QBAR Rural 137.5 QBAR Urban 137.5

Q 100 years 489.5

Q 1 year 119.6 Q 30 years 330.4 Q 100 years 489.5

(c)1982-2006 Micro Drainage URS Corporation Ltd Page 1 URS House Horne Lane Bedford MK40 1TS Date 18 October 2007 17:48 Designed By Florian_Baltoi File Area 3.SRC Checked By Micro Drainage Source Control W.10.4

Summary of Results for 100 year Return Period

Critical storm not identified, please run longer storm durations.

Storm Maximum Maximum Maximum Maximum Maximum Duration Control Outflow Water Level Depth Volume Status (mins) (l/s) (l/s) (m OD) (m) (m³)

360 Summer 0.0 0.0 0.2807 0.2807 8789.0 O K 360 Winter 0.0 0.0 0.2807 0.2807 8789.0 O K

Storm Rain Time-Peak Duration (mm/hr) (mins) (mins)

360 Summer 10.04 736 360 Winter 10.04 736

(c)1982-2006 Micro Drainage URS Corporation Ltd Page 2 URS House Horne Lane Bedford MK40 1TS Date 18 October 2007 17:48 Designed By Florian_Baltoi File Area 3.SRC Checked By Micro Drainage Source Control W.10.4

Rainfall Details

Time / Area Diagram

Total Area (ha) = 0.000

Time (mins) Area from: to: (ha)

0 4 0.000

Appendix G - Calculation Details for Assessment of Flooding for Development Conditions

Persimmon Homes Midlands Ltd\44406876 Towcester EIA\BDRP0007/FB/FB Revision 1 November 2007 BDRP0007

HEC-RAS Plan: SEL River: Silverstone Broo Reach: 1 Reach River Sta Profile Q Total Min Ch El W.S. Elev Top Width Sta W.S. Lft Sta W.S. Rgt Cum Ch Len SA Total Vel Chnl Vel Left Vel Right Vel Total Froude # Chl (m3/s) (m) (m) (m) (m) (m) (m) (1000 m2) (m/s) (m/s) (m/s) (m/s) 1 2600 20 yr with clima 11.40 91.32 92.95 20.54 29.29 49.83 1443.00 97.79 0.64 0.08 0.63 0.19 1 2600 100 yr with clim 16.00 91.32 93.16 28.68 21.74 50.42 1443.00 107.82 0.72 0.30 0.68 0.20 1 2600 1 yr with climat 4.20 91.32 92.52 13.63 35.01 48.64 1443.00 38.67 0.37 0.37 0.13

1 2550 Culvert

1 2500 20 yr with clima 11.40 91.21 92.82 68.93 0.32 69.26 1400.50 94.36 0.46 0.26 0.35 0.12 1 2500 100 yr with clim 16.00 91.21 92.94 77.97 0.27 78.23 1400.50 103.82 0.51 0.31 0.39 0.13 1 2500 1 yr with climat 4.20 91.21 92.49 26.18 0.48 26.66 1400.50 37.40 0.34 0.14 0.30 0.10

1 2400 20 yr with clima 11.40 91.00 92.75 65.13 0.18 65.31 1396.50 91.92 0.58 0.35 0.43 0.15 1 2400 100 yr with clim 16.00 91.00 92.86 71.65 0.15 71.80 1396.50 101.06 0.62 0.41 0.48 0.16 1 2400 1 yr with climat 4.20 91.00 92.47 42.67 0.25 42.91 1396.50 36.29 0.49 0.15 0.39 0.14

1 2300 20 yr with clima 11.40 90.83 92.71 75.72 3.42 79.13 1379.00 91.22 0.50 0.33 0.38 0.15 1 2300 100 yr with clim 16.00 90.83 92.81 82.76 3.18 85.94 1379.00 100.31 0.53 0.38 0.42 0.15 1 2300 1 yr with climat 4.20 90.83 92.40 43.69 4.14 47.83 1379.00 35.84 0.51 0.18 0.40 0.16

1 2200 20 yr with clima 11.40 90.82 92.61 73.26 9.78 83.03 1367.50 88.22 0.49 0.02 0.33 0.37 0.14 1 2200 100 yr with clim 16.00 90.82 92.70 79.78 8.39 88.18 1367.50 97.03 0.56 0.10 0.39 0.43 0.15 1 2200 1 yr with climat 4.20 90.82 92.34 47.05 10.43 57.47 1367.50 34.08 0.41 0.20 0.30 0.13

1 2100 20 yr with clima 11.40 90.70 92.48 73.60 16.71 90.30 1344.00 86.46 0.85 0.57 0.32 0.58 0.24 1 2100 100 yr with clim 16.00 90.70 92.54 80.18 15.43 95.61 1344.00 95.12 0.99 0.68 0.43 0.66 0.27 1 2100 1 yr with climat 4.20 90.70 92.25 24.34 22.16 46.50 1344.00 33.22 0.59 0.34 0.07 0.51 0.18

1 2000 20 yr with clima 11.40 90.62 92.16 103.85 9.09 131.50 1311.50 84.53 0.82 0.69 0.39 0.56 0.28 1 2000 100 yr with clim 16.00 90.62 92.25 108.58 8.88 131.83 1311.50 93.03 0.76 0.59 0.46 0.55 0.25 1 2000 1 yr with climat 4.20 90.62 91.94 9.95 9.66 46.74 1311.50 32.68 0.75 0.74 0.75 0.29

1 1950 20 yr with clima 11.40 90.43 92.03 132.68 6.52 155.33 1278.00 81.02 0.87 0.21 0.21 0.34 0.27 1 1950 100 yr with clim 16.00 90.43 92.15 142.74 6.25 155.79 1278.00 89.19 0.84 0.22 0.25 0.32 0.25 1 1950 1 yr with climat 4.20 90.43 91.75 27.65 7.18 90.38 1278.00 32.06 0.81 0.26 0.03 0.68 0.29

1 1900 20 yr with clima 11.40 90.33 91.97 135.25 54.03 189.28 1243.00 76.64 0.85 0.16 0.22 0.33 0.26 1 1900 100 yr with clim 16.00 90.33 92.10 159.86 29.99 189.85 1243.00 83.83 0.79 0.17 0.25 0.30 0.23 1 1900 1 yr with climat 4.20 90.33 91.64 12.72 114.45 127.17 1243.00 31.46 0.88 0.02 0.02 0.88 0.32

1 1870 20 yr with clima 11.40 90.25 91.89 84.15 33.35 117.49 1213.00 71.91 0.96 0.28 0.22 0.43 0.29 1 1870 100 yr with clim 16.00 90.25 92.04 85.22 32.85 118.07 1213.00 78.10 0.92 0.31 0.27 0.41 0.26 1 1870 1 yr with climat 4.20 90.25 91.54 6.16 63.02 69.18 1213.00 31.17 0.91 0.91 0.34

1 1850 20 yr with clima 11.40 90.20 91.83 74.17 24.67 98.83 1194.00 70.12 1.04 0.25 0.27 0.48 0.32 1 1850 100 yr with clim 16.00 90.20 91.99 75.44 24.03 99.47 1194.00 76.29 0.98 0.29 0.31 0.45 0.28 1 1850 1 yr with climat 4.20 90.20 91.47 6.07 52.06 58.14 1194.00 31.06 0.94 0.94 0.35

1 1800 20 yr with clima 11.40 90.13 91.77 64.07 26.49 90.56 1171.00 68.24 0.96 0.27 0.28 0.46 0.29 1 1800 100 yr with clim 16.00 90.13 91.95 65.53 25.74 91.27 1171.00 74.38 0.92 0.31 0.32 0.45 0.26 1 1800 1 yr with climat 4.20 90.13 91.38 5.99 50.11 56.09 1171.00 30.92 0.96 0.96 0.36

1 1750 20 yr with clima 11.40 90.06 91.68 55.64 15.08 70.72 1147.00 66.51 1.17 0.29 0.30 0.60 0.36 1 1750 100 yr with clim 16.00 90.06 91.88 56.82 14.71 71.53 1147.00 72.60 1.04 0.34 0.34 0.52 0.29 1 1750 1 yr with climat 4.20 90.06 91.27 5.82 40.69 46.51 1147.00 30.78 1.02 1.02 0.39

1 1700 20 yr with clima 11.40 90.00 91.62 10.00 24.00 34.00 1127.50 65.77 1.15 0.16 0.20 1.04 0.29 1 1700 100 yr with clim 16.00 90.00 91.76 10.00 24.00 34.00 1127.50 71.85 1.47 0.22 0.31 1.29 0.35 1 1700 1 yr with climat 4.20 90.00 91.27 6.00 24.50 30.50 1127.50 30.66 0.55 0.55 0.16

1 1540 Bridge

1 1530 20 yr with clima 11.40 89.89 91.57 10.00 25.00 35.00 1087.50 65.37 1.10 0.15 0.21 0.99 0.27 1 1530 100 yr with clim 16.00 89.89 91.68 10.00 25.00 35.00 1087.50 71.45 1.43 0.21 0.31 1.26 0.34 1 1530 1 yr with climat 4.20 89.89 91.26 10.00 25.00 35.00 1087.50 30.34 0.51 0.03 0.03 0.50 0.14

1 1520 20 yr with clima 11.40 89.83 91.56 47.16 32.07 79.24 1065.50 64.43 0.90 0.29 0.29 0.48 0.27 1 1520 100 yr with clim 16.00 89.83 91.68 48.07 31.60 79.67 1065.50 70.49 1.01 0.36 0.36 0.54 0.28 1 1520 1 yr with climat 4.20 89.83 91.23 44.80 33.31 78.11 1065.50 29.43 0.72 0.11 0.10 0.48 0.25

1 1510 20 yr with clima 11.40 89.77 91.52 51.92 21.39 73.31 1043.00 63.28 0.88 0.28 0.27 0.45 0.25 1 1510 100 yr with clim 16.00 89.77 91.64 52.59 21.08 73.67 1043.00 69.33 0.98 0.34 0.33 0.51 0.27 1 1510 1 yr with climat 4.20 89.77 91.19 50.12 22.21 72.33 1043.00 28.33 0.72 0.09 0.09 0.49 0.25

1 1500 20 yr with clima 11.40 89.70 91.44 51.70 22.49 74.19 1020.00 62.02 1.06 0.22 0.19 0.64 0.30 1 1500 100 yr with clim 16.00 89.70 91.55 56.96 22.21 79.16 1020.00 68.00 1.22 0.31 0.25 0.67 0.33 1 1500 1 yr with climat 4.20 89.70 91.16 10.32 49.07 59.39 1020.00 27.60 0.60 0.04 0.59 0.19

1 1400 20 yr with clima 11.40 89.42 91.36 71.16 21.71 92.88 974.50 59.17 0.47 0.36 0.29 0.36 0.12 1 1400 100 yr with clim 16.00 89.42 91.46 74.62 21.47 96.09 974.50 64.94 0.51 0.43 0.35 0.41 0.12 1 1400 1 yr with climat 4.20 89.42 91.11 58.54 22.36 80.90 974.50 26.00 0.41 0.21 0.16 0.28 0.11

1 1300 20 yr with clima 11.40 89.28 91.26 78.15 24.76 102.92 942.00 56.86 0.57 0.31 0.31 0.41 0.16 1 1300 100 yr with clim 16.00 89.28 91.35 82.09 24.51 106.60 942.00 62.54 0.62 0.39 0.38 0.45 0.17 1 1300 1 yr with climat 4.20 89.28 91.00 34.31 57.50 91.81 942.00 24.68 0.51 0.11 0.45 0.16

1 1200 20 yr with clima 11.40 89.30 91.18 90.18 36.25 126.43 927.00 55.16 0.58 0.32 0.26 0.41 0.17 1 1200 100 yr with clim 16.00 89.30 91.26 93.33 35.91 129.25 927.00 60.80 0.63 0.39 0.33 0.46 0.18 1 1200 1 yr with climat 4.20 89.30 90.94 27.38 59.84 87.22 927.00 24.13 0.46 0.06 0.44 0.15

1 1100 20 yr with clima 11.40 89.08 91.07 138.04 18.02 156.06 900.00 50.95 0.50 0.24 0.20 0.31 0.14 1 1100 100 yr with clim 16.00 89.08 91.14 143.29 14.91 158.20 900.00 56.46 0.52 0.29 0.24 0.34 0.14 1 1100 1 yr with climat 4.20 89.08 90.86 70.42 66.82 137.24 900.00 22.15 0.41 0.12 0.06 0.31 0.12

1 1005 20 yr with clima 11.40 89.00 91.04 136.60 18.59 155.20 886.50 49.50 0.55 0.21 0.21 0.32 0.14 1 1005 100 yr with clim 16.00 89.00 91.11 142.08 15.63 157.71 886.50 54.95 0.58 0.27 0.26 0.35 0.14 1 1005 1 yr with climat 4.20 89.00 90.84 65.62 74.65 140.27 886.50 21.44 0.38 0.08 0.08 0.29 0.10

1 1002 20 yr with clima 11.40 89.00 91.00 138.53 25.52 164.06 868.00 48.28 0.54 0.24 0.24 0.32 0.14 1 1002 100 yr with clim 16.00 89.00 91.07 145.68 20.93 166.61 868.00 53.66 0.55 0.28 0.28 0.34 0.14 1 1002 1 yr with climat 4.20 89.00 90.81 76.04 69.05 145.10 868.00 20.78 0.39 0.12 0.12 0.27 0.11

1 1000 20 yr with clima 11.40 89.19 90.93 119.83 31.79 151.62 855.50 46.88 0.75 0.34 0.34 0.45 0.22 1 1000 100 yr with clim 16.00 89.19 91.02 144.65 14.92 159.56 855.50 52.08 0.70 0.37 0.37 0.43 0.20 1 1000 1 yr with climat 4.20 89.19 90.76 59.72 73.18 132.89 855.50 20.04 0.61 0.19 0.19 0.43 0.20

1 940 20 yr with clima 11.40 89.00 90.76 119.58 19.38 138.96 813.00 41.55 0.43 0.25 0.26 0.30 0.13 1 940 100 yr with clim 16.00 89.00 90.89 133.54 8.94 142.48 813.00 45.88 0.39 0.26 0.28 0.29 0.11 1 940 1 yr with climat 4.20 89.00 90.43 31.49 75.30 106.79 813.00 18.02 0.64 0.07 0.07 0.61 0.22

1 930 20 yr with clima 11.40 88.80 90.71 117.70 18.09 135.79 794.50 39.45 0.48 0.25 0.25 0.32 0.14 1 930 100 yr with clim 16.00 88.80 90.86 131.95 8.98 140.93 794.50 43.54 0.41 0.26 0.26 0.30 0.11 1 930 1 yr with climat 4.20 88.80 90.28 8.55 85.25 93.80 794.50 17.65 0.60 0.60 0.21 HEC-RAS Plan: SEL River: Silverstone Broo Reach: 1 (Continued) Reach River Sta Profile Q Total Min Ch El W.S. Elev Top Width Sta W.S. Lft Sta W.S. Rgt Cum Ch Len SA Total Vel Chnl Vel Left Vel Right Vel Total Froude # Chl (m3/s) (m) (m) (m) (m) (m) (m) (1000 m2) (m/s) (m/s) (m/s) (m/s)

1 820 20 yr with clima 11.40 88.60 90.48 6.00 86.00 92.00 761.00 36.98 1.01 1.01 0.24 1 820 100 yr with clim 16.00 88.60 90.61 6.00 86.00 92.00 761.00 40.78 1.33 1.33 0.30 1 820 1 yr with climat 4.20 88.60 90.14 6.00 86.00 92.00 761.00 17.41 0.45 0.45 0.12

1 815 Culvert

1 810 20 yr with clima 11.40 88.50 90.44 6.00 38.00 44.00 729.00 36.79 0.98 0.98 0.22 1 810 100 yr with clim 16.00 88.50 90.55 6.00 38.00 44.00 729.00 40.59 1.30 1.30 0.29 1 810 1 yr with climat 4.20 88.50 90.13 6.00 38.00 44.00 729.00 17.22 0.43 0.43 0.11

1 700 20 yr with clima 11.40 88.45 90.19 110.64 11.72 122.36 684.00 34.13 0.52 0.28 0.29 0.36 0.16 1 700 100 yr with clim 16.00 88.45 90.27 117.03 8.64 125.68 684.00 37.79 0.54 0.33 0.34 0.39 0.16 1 700 1 yr with climat 4.20 88.45 89.98 75.03 27.52 102.55 684.00 15.37 0.51 0.10 0.10 0.41 0.18

1 600 20 yr with clima 11.40 88.32 90.12 110.68 15.04 125.72 669.00 32.81 0.60 0.23 0.38 0.41 0.19 1 600 100 yr with clim 16.00 88.32 90.21 116.89 11.49 128.38 669.00 36.39 0.59 0.29 0.42 0.42 0.18 1 600 1 yr with climat 4.20 88.32 89.89 37.65 67.39 105.04 669.00 14.62 0.55 0.21 0.45 0.19

1 500 20 yr with clima 11.40 88.22 89.87 91.19 34.01 125.20 595.00 25.82 0.44 0.30 0.29 0.33 0.13 1 500 100 yr with clim 16.00 88.22 89.96 102.81 25.71 128.52 595.00 28.80 0.48 0.35 0.34 0.37 0.14 1 500 1 yr with climat 4.20 88.22 89.60 57.31 58.21 115.52 595.00 11.21 0.39 0.23 0.20 0.28 0.13

1 400 20 yr with clima 11.40 87.89 89.70 106.31 22.36 128.67 542.00 21.07 0.58 0.26 0.28 0.39 0.17 1 400 100 yr with clim 16.00 87.89 89.79 119.10 15.50 134.60 542.00 23.44 0.59 0.32 0.32 0.40 0.17 1 400 1 yr with climat 4.20 87.89 89.40 10.08 82.98 93.06 542.00 9.58 0.50 0.50 0.17

1 300 20 yr with clima 11.40 87.90 89.63 110.61 24.12 134.73 527.00 19.45 0.60 0.24 0.24 0.39 0.17 1 300 100 yr with clim 16.00 87.90 89.73 122.02 17.63 139.64 527.00 21.66 0.61 0.29 0.30 0.39 0.16 1 300 1 yr with climat 4.20 87.90 89.35 8.84 79.05 87.90 527.00 9.44 0.44 0.44 0.13

1 230 20 yr with clima 11.40 87.92 89.45 64.96 0.00 64.96 480.00 15.38 0.60 0.39 0.46 0.17 1 230 100 yr with clim 16.00 87.92 89.55 71.55 0.00 71.55 480.00 17.16 0.63 0.45 0.50 0.18 1 230 1 yr with climat 4.20 87.92 89.21 43.17 0.00 43.17 480.00 8.70 0.47 0.22 0.35 0.15

1 220 20 yr with clima 11.40 87.90 89.32 68.41 0.00 68.41 427.00 13.36 0.45 0.33 0.37 0.13 1 220 100 yr with clim 16.00 87.90 89.42 72.57 0.00 72.57 427.00 14.99 0.48 0.39 0.41 0.14 1 220 1 yr with climat 4.20 87.90 89.08 59.04 0.22 59.25 427.00 7.11 0.36 0.19 0.26 0.12

1 215 Bridge

1 210 20 yr with clima 11.40 87.64 89.27 76.51 0.64 77.15 412.50 12.29 0.44 0.17 0.34 0.36 0.13 1 210 100 yr with clim 16.00 87.64 89.38 80.60 0.00 80.60 412.50 13.86 0.46 0.24 0.39 0.39 0.13 1 210 1 yr with climat 4.20 87.64 89.02 63.17 6.03 69.20 412.50 6.21 0.42 0.04 0.22 0.29 0.14

1 200 20 yr with clima 11.40 87.20 89.16 72.90 0.00 72.90 368.50 10.15 0.53 0.39 0.30 0.41 0.16 1 200 100 yr with clim 16.00 87.20 89.28 78.43 0.00 78.43 368.50 11.61 0.54 0.45 0.35 0.44 0.16 1 200 1 yr with climat 4.20 87.20 88.86 35.51 0.00 35.51 368.50 4.73 0.48 0.13 0.08 0.44 0.17

1 150 20 yr with clima 11.40 86.84 88.92 55.42 0.00 55.42 318.50 6.14 0.61 0.45 0.37 0.47 0.16 1 150 100 yr with clim 16.00 86.84 89.04 60.97 0.00 60.97 318.50 7.21 0.64 0.53 0.44 0.51 0.16 1 150 1 yr with climat 4.20 86.84 88.54 34.25 0.00 34.25 318.50 2.73 0.64 0.12 0.12 0.57 0.19

1 100 20 yr with clima 11.40 86.90 88.72 48.63 0.00 48.63 281.50 4.12 0.71 0.48 0.40 0.54 0.19 1 100 100 yr with clim 16.00 86.90 88.85 52.40 0.00 52.40 281.50 5.00 0.74 0.57 0.47 0.58 0.19 1 100 1 yr with climat 4.20 86.90 88.10 5.46 13.22 18.67 281.50 1.97 0.93 0.93 0.33

1 50 20 yr with clima 11.40 87.10 88.43 30.19 0.00 34.53 277.00 3.88 2.29 0.19 0.28 1.58 0.75 1 50 100 yr with clim 16.00 87.10 88.62 43.02 0.00 43.02 277.00 4.71 2.23 0.36 0.40 1.10 0.67 1 50 1 yr with climat 4.20 87.10 87.78 3.55 12.66 16.21 277.00 1.95 2.27 2.27 1.00

1 40 20 yr with clima 11.40 87.00 88.14 8.30 2.65 10.95 266.50 3.64 1.49 1.49 0.49 1 40 100 yr with clim 16.00 87.00 88.34 13.36 2.28 15.64 266.50 4.35 1.69 0.06 1.67 0.52 1 40 1 yr with climat 4.20 87.00 87.64 6.97 3.53 10.50 266.50 1.90 1.07 1.07 0.46

1 30 20 yr with clima 11.40 86.52 87.79 18.79 31.78 59.76 130.50 1.76 1.28 0.09 0.19 1.14 0.41 1 30 100 yr with clim 16.00 86.52 88.03 20.58 31.53 60.01 130.50 2.03 1.38 0.22 0.27 1.09 0.40 1 30 1 yr with climat 4.20 86.52 87.27 7.52 41.00 48.53 130.50 0.91 0.96 0.96 0.40

1 25 Bridge

1 20 20 yr with clima 11.40 86.47 87.75 17.50 32.28 59.72 117.00 1.52 1.33 0.05 0.17 1.22 0.43 1 20 100 yr with clim 16.00 86.47 88.00 20.32 31.57 59.97 117.00 1.78 1.42 0.21 0.27 1.14 0.41 1 20 1 yr with climat 4.20 86.47 87.23 7.36 41.08 48.44 117.00 0.81 1.01 1.01 0.43

1 10 20 yr with clima 11.40 86.09 87.40 8.36 13.90 22.25 1.46 1.46 0.48 1 10 100 yr with clim 16.00 86.09 87.66 9.96 12.86 22.82 1.57 1.57 0.49 1 10 1 yr with climat 4.20 86.09 86.86 6.54 14.91 21.45 1.09 1.09 0.46

Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Legend

2500 WS 20 yr with clima 2100 2000 WS 100 yr with clim 1900 Ground 1870 Bank Sta 1800 Levee 1750 1700 1530 1510

1400 1100 1002

940 820

810 700

500

400

230 220 200

150 100

Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Broo 1 100 Legend

WS 100 yr with clim WS 20 yr with clima

98 WS 1 yr with climat Ground Left Levee

Elevation (m) 92

88 1500 1510 1520 1540 1750 1800 1850 1900 1950 2000 2100 2200 2400 2550 86 20 40 150 200 210 230 300 500 600 810 815 930 1000 1005 1200 1400 0 200 400 600 800 1000 1200 1400 1600 Main Channel Distance (m)

Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 2600 RS = 2550 Culv RS = 2550 Culv .08 .12 . .08 .12 . .12 .08 94.5 0 94.5 0 93.5 8 Legend 8 Legend Legend 94.0 WS 100 yr with clim 94.0 WS 100 yr with clim WS 100 yr with clim 93.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 93.5 93.5 WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat 92.5 93.0 Ground 93.0 Ground Ground

92.5 Bank Sta 92.5 Bank Sta Bank Sta 92.0 Elevation(m) Elevation(m) Elevation(m) 92.0 92.0 91.5 91.5 91.5

91.0 91.0 91.0 0 10 20 30 40 50 60 0 10 20 30 40 50 60 0 20 40 60 80 100 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 2500 RS = 2400 RS = 2300 .12 .08 . .08 . . .08 93.5 93.5 1 93.5 0 1 Legend 2 Legend 8 2 Legend

WS 100 yr with clim WS 100 yr with clim 93.0 WS 100 yr with clim 93.0 93.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima WS 1 yr with climat WS 1 yr with climat 92.5 WS 1 yr with climat 92.5 92.5 Ground Ground Ground 92.0 Bank Sta Bank Sta Bank Sta 92.0 92.0 Elevation(m) Elevation(m) Elevation(m) 91.5

91.5 91.5 91.0

91.0 91.0 90.5 0 20 40 60 80 100 0 20 40 60 80 100 120 0 20 40 60 80 100 120 140 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 2200 RS = 2100 RS = 2000 .08 . .08 .08 . .08 .08 . .08 93.5 1 94.0 1 94.0 1 2 Legend 2 Legend 2 Legend

93.0 WS 100 yr with clim 93.5 WS 100 yr with clim 93.5 WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 93.0 93.0 92.5 WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat Ground 92.5 Ground 92.5 Ground 92.0 Bank Sta 92.0 Bank Sta 92.0 Bank Sta Elevation(m) Elevation(m) 91.5 Elevation(m) 91.5 91.5

91.0 91.0 91.0

90.5 90.5 90.5 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 160 180 0 50 100 150 200 Station (m) Station (m) Station (m)

Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 1950 Diversion Channel Upstream XS RS = 1900 RS = 1870 .08 . .08 .08 . .08 .08 . .08 94.0 0 100 0 100 0 5 Legend 5 Legend 5 Legend 93.5 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 98 98 93.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat 92.5 96 96 Ground Ground Ground 92.0 Bank Sta Bank Sta Bank Sta 91.5 94 94 Elevation(m) Elevation(m) Elevation(m)

91.0 92 92 90.5

90.0 90 90 0 50 100 150 200 0 50 100 150 200 250 0 20 40 60 80 100 120 140 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 1850 RS = 1800 RS = 1750 .08 . .08 .08 . .08 .08 . .08 100 0 100 0 100 0 5 Legend 5 Legend 5 Legend WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 98 98 98 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat 96 96 96 Ground Ground Ground Bank Sta Bank Sta Bank Sta 94 94 94 Elevation(m) Elevation(m) Elevation(m)

92 92 92

90 90 90 0 20 40 60 80 100 120 0 20 40 60 80 100 120 0 20 40 60 80 100 120 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 1700 RS = 1540 BR RS = 1540 BR .08 . .08 .08 . .08 .08 . .08 100 0 100 0 100 0 3 Legend 3 Legend 3 Legend 5 5 5 WS 100 yr with clim WS 100 yr with clim 98 WS 100 yr with clim 98 98 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima WS 1 yr with climat WS 1 yr with climat 96 WS 1 yr with climat 96 96 Ground Ground Ground 94 Bank Sta Bank Sta Bank Sta 94 94 Elevation(m) Elevation(m) Elevation(m) 92

92 92 90

90 90 88 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100 Station (m) Station (m) Station (m)

Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 1530 RS = 1520 RS = 1510 .08 . .08 .08 . .08 .08 .05 .08 100 0 100 0 100 3 Legend 5 Legend Legend 5 98 WS 100 yr with clim 98 WS 100 yr with clim 98 WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 96 WS 1 yr with climat 96 WS 1 yr with climat 96 WS 1 yr with climat Ground Ground Ground 94 94 94 Bank Sta Bank Sta Bank Sta

Elevation(m) 92 Elevation(m) 92 Elevation(m) 92

90 90 90

88 88 88 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 1500 RS = 1400 RS = 1300 .08 .05 .08 .08 . .08 .08 . .08 100 100 1 100 1 Legend 2 Legend 2 Legend

98 WS 100 yr with clim 98 WS 100 yr with clim 98 WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 96 WS 1 yr with climat 96 WS 1 yr with climat 96 WS 1 yr with climat Ground Ground Ground 94 94 94 Bank Sta Bank Sta Bank Sta Elevation(m) Elevation(m) 92 Elevation(m) 92 92

90 90 90

88 88 88 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100 120 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 1200 RS = 1100 RS = 1005 .08 .12 .08 .08 . .08 .08 . .08 100 91.5 1 91.5 1 Legend 2 Legend 2 Legend

98 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 91.0 91.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 96 WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat 90.5 90.5 Ground Ground Ground 94 Bank Sta Bank Sta Bank Sta 90.0 90.0 Elevation(m) Elevation(m) 92 Elevation(m)

89.5 89.5 90

88 89.0 89.0 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 160 180 0 20 40 60 80 100 120 140 160 180 Station (m) Station (m) Station (m)

Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 1002 RS = 1000 RS = 940 .08 . .08 .08 . .08 .08 . .08 91.5 1 91.5 1 91.0 1 2 Legend 2 Legend 2 Legend WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 91.0 91.0 WS 20 yr with clima WS 20 yr with clima 90.5 WS 20 yr with clima WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat 90.5 90.5 Ground Ground Ground 90.0 Bank Sta Bank Sta Bank Sta 90.0 90.0 Elevation(m) Elevation(m) Elevation(m)

89.5 89.5 89.5

89.0 89.0 89.0 0 50 100 150 200 0 20 40 60 80 100 120 140 160 180 0 20 40 60 80 100 120 140 160 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 930 RS = 820 modified cross-section to accomodate bridge RS = 815 Culv .08 . .08 .08 . .08 .08 . .08 91.0 1 92.0 1 92.0 1 2 Legend 2 Legend 2 Legend WS 100 yr with clim 91.5 WS 100 yr with clim 91.5 WS 100 yr with clim 90.5 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 91.0 91.0 WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat 90.0 Ground 90.5 Ground 90.5 Ground

Bank Sta 90.0 Bank Sta 90.0 Bank Sta 89.5 Elevation(m) Elevation(m) Elevation(m) 89.5 89.5 89.0 89.0 89.0

88.5 88.5 88.5 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 815 Culv RS = 810 modified cross-section to accomodate culvert RS = 700 .08 . .08 .08 . .08 .08 . .08 92.0 1 92.0 1 90.5 1 2 Legend 2 Legend 2 Legend 91.5 WS 100 yr with clim 91.5 WS 100 yr with clim WS 100 yr with clim 90.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 91.0 91.0 WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat 89.5 90.5 Ground 90.5 Ground Ground

90.0 Bank Sta 90.0 Bank Sta Bank Sta 89.0 Elevation(m) Elevation(m) Elevation(m) 89.5 89.5 88.5 89.0 89.0

88.5 88.5 88.0 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 Station (m) Station (m) Station (m)

Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 600 RS = 500 RS = 400 .08 . .08 .08 . .08 .08 . .08 90.5 1 90.5 1 90.0 1 2 Legend 2 Legend 2 Legend WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 90.0 90.0 89.5 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat 89.5 89.5 89.0 Ground Ground Ground Bank Sta Bank Sta Bank Sta 89.0 89.0 88.5 Elevation(m) Elevation(m) Elevation(m)

88.5 88.5 88.0

88.0 88.0 87.5 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 300 RS = 230 RS = 220 .08 . .08 .12 .08 .12 .08 90.0 1 90.0 90.0 2 Legend Legend Legend WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 89.5 89.5 89.5 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat 89.0 89.0 89.0 Ground Ground Ground Bank Sta Levee Levee 88.5 88.5 88.5 Elevation(m) Elevation(m) Elevation(m) Bank Sta Bank Sta

88.0 88.0 88.0

87.5 87.5 87.5 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 0 20 40 60 80 100 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 215 BR RS = 215 BR RS = 210 .12 .08 .08 . .08 .08 . .08 90.0 90.0 1 90.0 1 Legend 2 Legend 2 Legend WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 89.5 89.5 89.5 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat 89.0 89.0 89.0 Ground Ground Ground Levee Levee Levee 88.5 88.5 88.5 Elevation(m) Elevation(m) Bank Sta Elevation(m) Bank Sta Bank Sta

88.0 88.0 88.0

87.5 87.5 87.5 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100 Station (m) Station (m) Station (m)

WS 100 yr with clim 89.0 WS 100 yr with clim 89.0 WS 100 yr with clim 89.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima WS 1 yr with climat 88.5 WS 1 yr with climat 88.5 WS 1 yr with climat 88.5 Ground Ground Ground 88.0 88.0 Levee Levee Levee 88.0 Elevation(m) Bank Sta Elevation(m) 87.5 Bank Sta Elevation(m) 87.5 Bank Sta

87.5 87.0 87.0

87.0 86.5 86.5 0 20 40 60 80 100 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 50 RS = 40 RS = 30 .08 . .08 . .035 .08 .08 .035 .08 89.5 0 89.5 0 90.0 3 Legend 8 Legend Legend 5 WS 100 yr with clim WS 100 yr with clim 89.5 WS 100 yr with clim 89.0 89.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 89.0 WS 1 yr with climat WS 1 yr with climat WS 1 yr with climat 88.5 88.5 Ground Ground 88.5 Ground

Levee Bank Sta 88.0 Bank Sta 88.0 88.0 Elevation(m) Elevation(m) Bank Sta Elevation(m) 87.5 87.5 87.5 87.0

87.0 87.0 86.5 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 0 20 40 60 80 Station (m) Station (m) Station (m) Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 25 BR RS = 25 BR RS = 20 .08 .035 .08 .08 .035 .08 .08 .035 .08 90.0 90.0 90.0 Legend Legend Legend

89.5 WS 100 yr with clim 89.5 WS 100 yr with clim 89.5 WS 100 yr with clim

WS 20 yr with clima 89.0 WS 20 yr with clima 89.0 WS 20 yr with clima 89.0 WS 1 yr with climat 88.5 WS 1 yr with climat 88.5 WS 1 yr with climat 88.5 Ground Ground Ground 88.0 88.0 88.0 Bank Sta Bank Sta Bank Sta 87.5 87.5 Elevation(m) Elevation(m) Elevation(m) 87.5 87.0 87.0

87.0 86.5 86.5

86.5 86.0 86.0 0 20 40 60 80 0 20 40 60 80 0 20 40 60 80 Station (m) Station (m) Station (m)

Silverstone Brook Diversion Plan: SBD Selected 15/10/2007 RS = 10 .08 .035 .08 88.5 Legend

WS 100 yr with clim 88.0 WS 20 yr with clima WS 1 yr with climat 87.5 Ground Bank Sta 87.0 Elevation(m)

86.5

86.0 5 10 15 20 25 30 Station (m)

HEC-RAS Plan: WBBD River: Wood Burcote Bro Reach: 1 Reach River Sta Profile Q Total Min Ch El W.S. Elev Top Width Sta W.S. Lft Sta W.S. Rgt Cum Ch Len SA Total Vel Chnl Vel Left Vel Right Vel Total Froude # Chl (m3/s) (m) (m) (m) (m) (m) (m) (1000 m2) (m/s) (m/s) (m/s) (m/s) 1 2600 20 yr with clima 1.80 113.50 114.18 6.25 11.19 17.44 1598.30 12.01 1.03 0.57 0.98 0.51 1 2600 100 yr with clim 2.60 113.50 114.24 9.06 10.44 19.50 1598.30 15.20 1.24 0.77 0.22 1.15 0.58

1 2500 20 yr with clima 1.80 112.60 113.62 28.77 4.17 32.94 1559.30 11.39 0.46 0.21 0.36 0.19 1 2500 100 yr with clim 2.60 112.60 113.69 30.99 4.03 35.01 1559.30 14.49 0.47 0.28 0.37 0.19

1 2400 20 yr with clima 1.80 111.80 112.37 2.98 16.74 19.72 1505.80 10.66 1.82 1.82 1.01 1 2400 100 yr with clim 2.60 111.80 112.47 3.44 16.50 19.94 1505.80 13.71 1.96 1.96 1.01

1 2320 20 yr with clima 1.80 111.60 112.05 3.00 16.50 19.50 1499.30 10.65 1.35 1.35 0.64 1 2320 100 yr with clim 2.60 111.60 112.16 3.00 16.50 19.50 1499.30 13.68 1.55 1.55 0.66

1 2315 Bridge

1 2310 20 yr with clima 1.80 111.20 111.79 3.00 11.50 14.50 1456.80 10.52 1.01 1.01 0.42 1 2310 100 yr with clim 2.60 111.20 111.92 3.00 11.50 14.50 1456.80 13.56 1.21 1.21 0.46

1 2300 20 yr with clima 1.80 110.70 111.42 5.56 16.24 21.80 1411.30 10.32 0.99 0.11 0.11 0.99 0.50 1 2300 100 yr with clim 2.60 110.70 111.55 13.45 10.88 24.34 1411.30 13.18 0.95 0.43 0.40 0.83 0.42

1 2270 20 yr with clima 1.80 110.50 111.16 4.00 17.00 21.00 1401.30 10.28 0.68 0.68 0.27 1 2270 100 yr with clim 2.60 110.50 111.31 4.00 17.00 21.00 1401.30 13.10 0.80 0.80 0.29

1 2250 Culvert

1 2210 20 yr with clima 1.80 110.20 111.15 4.00 15.00 19.00 1374.80 10.17 0.47 0.47 0.15 1 2210 100 yr with clim 2.60 110.20 111.30 4.00 15.00 19.00 1374.80 13.00 0.59 0.59 0.18

1 2200 20 yr with clima 1.80 110.00 111.05 15.83 8.55 24.39 1362.80 10.03 0.59 0.18 0.53 0.25 1 2200 100 yr with clim 2.60 110.00 111.22 21.26 5.33 26.59 1362.80 12.82 0.48 0.30 0.14 0.40 0.18

1 2120 20 yr with clima 1.80 109.80 110.88 9.21 19.59 28.80 1349.80 9.88 0.66 0.17 0.62 0.27 1 2120 100 yr with clim 2.60 109.80 111.17 23.87 8.31 32.18 1349.80 12.54 0.41 0.26 0.14 0.33 0.14

1 2115 Bridge

1 2110 20 yr with clima 1.80 109.60 110.47 4.25 19.76 24.01 1336.30 9.82 0.87 0.87 0.40 1 2110 100 yr with clim 2.60 109.60 110.63 6.54 17.84 24.39 1336.30 12.37 0.92 0.14 0.91 0.39

1 2100 20 yr with clima 1.80 108.20 109.27 4.06 11.35 15.41 1275.30 9.57 0.66 0.66 0.26 1 2100 100 yr with clim 2.60 108.20 109.45 4.58 11.16 15.74 1275.30 12.03 0.74 0.74 0.27

1 2000 20 yr with clima 1.80 107.80 108.71 4.34 9.61 13.94 1240.80 9.42 0.74 0.74 0.32 1 2000 100 yr with clim 2.60 107.80 108.87 4.93 9.36 14.29 1240.80 11.87 0.82 0.82 0.33

1 1900 20 yr with clima 1.80 106.30 107.44 4.36 6.32 10.68 1161.80 9.08 0.65 0.65 0.26 1 1900 100 yr with clim 2.60 106.30 107.66 5.08 6.01 11.08 1161.80 11.47 0.69 0.69 0.25

1 1800 20 yr with clima 1.80 105.60 106.84 3.48 7.40 10.88 1112.80 8.89 0.65 0.65 0.23 1 1800 100 yr with clim 2.60 105.60 106.98 3.75 7.28 11.03 1112.80 11.26 0.79 0.79 0.27

1 1720 20 yr with clima 1.80 105.10 106.69 13.18 6.81 19.99 1065.80 8.50 0.30 0.14 0.28 0.10 1 1720 100 yr with clim 2.60 105.10 106.75 16.11 5.52 21.63 1065.80 10.79 0.40 0.20 0.05 0.35 0.12

1 1715 Culvert

1 1710 20 yr with clima 1.80 104.40 105.34 5.30 15.77 21.07 1048.30 8.35 0.53 0.53 0.21 1 1710 100 yr with clim 2.60 104.40 105.54 6.00 15.40 21.40 1048.30 10.61 0.57 0.57 0.21

1 1700 20 yr with clima 1.80 104.10 104.99 3.49 2.69 6.18 1021.80 8.23 0.81 0.81 0.33 1 1700 100 yr with clim 2.60 104.10 105.21 4.00 2.49 6.48 1021.80 10.48 0.85 0.85 0.31

1 1600 20 yr with clima 1.80 102.50 103.61 4.08 5.03 9.11 934.80 7.90 0.64 0.64 0.24 1 1600 100 yr with clim 2.60 102.50 103.75 4.47 4.79 9.25 934.80 10.11 0.76 0.76 0.28

1 1500 20 yr with clima 1.80 101.60 102.46 4.10 2.31 6.41 867.30 7.63 0.82 0.82 0.36 1 1500 100 yr with clim 2.60 101.60 102.68 7.59 2.00 9.59 867.30 9.70 0.79 0.33 0.76 0.30

1 1420 20 yr with clima 1.80 101.10 102.06 3.81 12.13 15.94 849.80 7.56 0.78 0.78 0.32 1 1420 100 yr with clim 2.60 101.10 102.46 7.18 11.55 18.73 849.80 9.58 0.58 0.58 0.23

1 1415 Bridge

1 1410 20 yr with clima 1.80 100.80 101.75 4.47 13.52 17.99 836.30 7.50 0.69 0.69 0.29 1 1410 100 yr with clim 2.60 100.80 101.96 5.24 13.08 18.32 836.30 9.54 0.72 0.72 0.28

1 1400 20 yr with clima 1.80 99.90 101.15 6.02 9.75 15.78 770.80 7.16 0.49 0.08 0.49 0.18 1 1400 100 yr with clim 2.60 99.90 101.21 7.92 7.95 15.87 770.80 9.11 0.65 0.18 0.63 0.23

1 1380 20 yr with clima 1.80 99.60 101.13 12.47 12.57 25.04 762.30 7.06 0.27 0.07 0.07 0.26 0.09 1 1380 100 yr with clim 2.60 99.60 101.19 14.83 10.66 25.49 762.30 8.98 0.36 0.12 0.12 0.34 0.12

1 1350 Culvert

1 1300 20 yr with clima 1.80 99.20 99.92 4.56 27.69 32.24 711.80 6.63 0.93 0.93 0.45 1 1300 100 yr with clim 2.60 99.20 100.09 6.19 27.27 33.46 711.80 8.45 0.91 0.91 0.43

1 1200 20 yr with clima 1.80 98.40 99.33 8.73 12.38 21.11 659.80 6.28 0.39 0.39 0.17 1 1200 100 yr with clim 2.60 98.40 99.45 9.53 11.97 21.50 659.80 8.04 0.46 0.46 0.19

1 1100 20 yr with clima 1.80 98.00 98.92 14.11 4.58 18.69 614.30 5.79 0.70 0.25 0.60 0.29 1 1100 100 yr with clim 2.60 98.00 99.02 26.15 4.44 30.58 614.30 7.27 0.72 0.31 0.55 0.28

1 1010 20 yr with clima 1.80 97.10 98.16 18.39 25.38 43.77 550.30 4.88 0.63 0.31 0.37 0.46 0.21 1 1010 100 yr with clim 2.60 97.10 98.22 22.58 21.81 44.39 550.30 5.91 0.71 0.38 0.45 0.51 0.23

1 1005 Culvert

1 1000 20 yr with clima 1.80 97.00 97.87 25.38 19.56 44.94 528.30 4.15 0.54 0.31 0.23 0.39 0.21 1 1000 100 yr with clim 2.60 97.00 97.89 27.66 17.57 45.23 528.30 5.07 0.68 0.41 0.31 0.49 0.26

1 900 20 yr with clima 1.80 96.40 96.79 7.25 52.35 59.59 476.80 3.44 1.01 1.01 0.65 1 900 100 yr with clim 2.60 96.40 97.03 10.54 51.31 61.85 476.80 4.22 0.66 0.66 0.34

1 820 20 yr with clima 1.80 95.20 96.76 11.90 43.67 55.57 439.80 3.08 0.17 0.17 0.06 1 820 100 yr with clim 2.60 95.20 96.99 30.10 26.65 56.75 439.80 3.67 0.19 0.03 0.03 0.18 0.06

1 815 Culvert

1 810 20 yr with clima 1.80 95.20 96.33 3.36 33.84 37.20 423.80 2.96 0.73 0.73 0.27 1 810 100 yr with clim 2.60 95.20 96.52 3.77 33.55 37.33 423.80 3.40 0.82 0.82 0.29 HEC-RAS Plan: WBBD River: Wood Burcote Bro Reach: 1 (Continued) Reach River Sta Profile Q Total Min Ch El W.S. Elev Top Width Sta W.S. Lft Sta W.S. Rgt Cum Ch Len SA Total Vel Chnl Vel Left Vel Right Vel Total Froude # Chl (m3/s) (m) (m) (m) (m) (m) (m) (1000 m2) (m/s) (m/s) (m/s) (m/s)

1 800 20 yr with clima 1.80 94.40 95.29 4.61 19.37 23.99 364.80 2.73 0.72 0.72 0.31 1 800 100 yr with clim 2.60 94.40 95.45 5.26 19.08 24.34 364.80 3.13 0.79 0.79 0.32

1 700 20 yr with clima 1.80 93.50 94.49 4.42 32.55 36.97 316.30 2.51 0.67 0.67 0.28 1 700 100 yr with clim 2.60 93.50 94.63 7.43 32.34 39.76 316.30 2.83 0.77 0.25 0.74 0.29

1 650 20 yr with clima 1.80 93.50 93.95 4.00 27.50 31.50 296.60 2.43 0.99 0.99 0.47 1 650 100 yr with clim 2.60 93.50 94.07 4.00 27.50 31.50 296.60 2.71 1.13 1.13 0.48

1 610 Culvert

1 605 20 yr with clima 1.80 93.20 93.91 4.00 7.50 11.50 260.80 2.28 0.63 0.63 0.24 1 605 100 yr with clim 2.60 93.20 94.02 4.00 7.50 11.50 260.80 2.57 0.80 0.80 0.28

1 500 20 yr with clima 1.80 92.50 93.61 14.38 31.09 45.47 225.40 1.98 0.47 0.34 0.41 0.18 1 500 100 yr with clim 2.60 92.50 93.74 18.25 27.40 45.65 225.40 2.20 0.45 0.36 0.40 0.16

1 400 20 yr with clima 1.80 92.30 93.39 5.20 6.75 11.95 204.40 1.65 0.60 0.26 0.59 0.22 1 400 100 yr with clim 2.60 92.30 93.52 6.36 6.55 12.91 204.40 1.78 0.72 0.40 0.69 0.25

1 300 20 yr with clima 1.80 91.90 93.28 8.61 0.25 8.86 183.90 1.51 0.44 0.13 0.13 0.42 0.15 1 300 100 yr with clim 2.60 91.90 93.37 10.42 0.00 10.42 183.90 1.61 0.54 0.25 0.22 0.50 0.17

1 275 Culvert

1 250 20 yr with clima 1.80 91.60 92.57 5.62 1.38 7.01 164.90 1.39 0.49 0.49 0.19 1 250 100 yr with clim 2.60 91.60 92.72 6.18 1.14 7.31 164.90 1.48 0.57 0.57 0.21

1 200 20 yr with clima 1.80 91.20 92.49 5.37 2.56 7.92 150.90 1.31 0.44 0.44 0.16 1 200 100 yr with clim 2.60 91.20 92.62 5.98 2.22 8.20 150.90 1.39 0.54 0.04 0.54 0.19

1 100 20 yr with clima 1.80 91.10 92.36 8.50 0.00 8.50 119.90 1.09 0.43 0.21 0.11 0.41 0.14 1 100 100 yr with clim 2.60 91.10 92.43 9.70 0.00 9.70 119.90 1.14 0.56 0.33 0.19 0.52 0.18

1 50 20 yr with clima 1.80 91.00 92.36 13.76 0.00 13.76 109.70 0.98 0.19 0.18 0.07 0.18 0.06 1 50 100 yr with clim 2.60 91.00 92.42 14.33 0.00 14.33 109.70 1.02 0.25 0.24 0.10 0.24 0.07

1 40 20 yr with clima 1.80 92.13 92.27 12.67 0.00 12.67 98.80 0.84 1.05 1.36 0.99 1.11 0.90 1 40 100 yr with clim 2.60 92.13 92.31 12.91 0.00 12.91 98.80 0.87 1.16 1.53 1.09 1.24 0.88

1 30 20 yr with clima 1.80 90.40 91.88 8.04 4.81 12.85 78.60 0.63 0.24 0.24 0.08 1 30 100 yr with clim 2.60 90.40 91.94 8.27 4.71 12.98 78.60 0.66 0.33 0.33 0.11

1 20 20 yr with clima 1.80 90.06 91.87 13.32 0.00 13.32 71.00 0.53 0.49 0.25 0.22 0.37 0.12 1 20 100 yr with clim 2.60 90.06 91.93 13.85 0.00 13.85 71.00 0.55 0.61 0.36 0.30 0.47 0.14

1 15 Culvert

1 10 20 yr with clima 1.80 88.75 89.45 1.20 27.20 28.40 2.15 2.15 0.82 1 10 100 yr with clim 2.60 88.75 89.68 1.20 27.20 28.40 2.33 2.33 0.77

Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 2600 Legend 2500 2400 WS 20 yr with clima 2310 WS 100 yr with clim 2300 Ground 2210 2110 Bank Sta

2100 Levee 2000

1900 1800 1720 1700

1600

1500

1400 1300 1200 1100 1010

900 820

800 700

605 400 250 100 30

Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Bro 1 120 Legend

WS 100 yr with clim WS 20 yr with clima

115 Ground Left Levee

110

105

Elevation (m) 100

90 1700 1710 1800 1900 2000 2100 2110 2200 2250 2310 2315 2500 2600 85 15 40 200 275 400 605 610 700 800 810 900 1000 1100 1200 1300 1350 1410 1500 1600 0 200 400 600 800 1000 1200 1400 1600 Main Channel Distance (m)

Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 RS = 2600 RS = 2500 RS = 2400 .08 .12 .08 .08 .12 .08 .08 .12 .08 Legend Legend Legend 114.8 113.8 WS 100 yr with clim WS 100 yr with clim 112.8 WS 100 yr with clim 114.6 WS 20 yr with clima 113.6 WS 20 yr with clima WS 20 yr with clima 112.6 114.4 Ground 113.4 Ground Ground Bank Sta Bank Sta Bank Sta 114.2 113.2 112.4

114.0 113.0 Elevation(m) Elevation(m) Elevation(m) 112.2 113.8 112.8 112.0 113.6 112.6

113.4 112.4 111.8 0 10 20 30 40 50 0 10 20 30 40 50 0 10 20 30 40 50 Station (m) Station (m) Station (m)

117 WS 20 yr with clima 117 WS 20 yr with clima 117 WS 20 yr with clima

116 Ground 116 Ground 116 Ground Bank Sta Bank Sta Bank Sta 115 115 115

114 114 114 Elevation(m) Elevation(m) Elevation(m)

113 113 113

112 112 112

111 111 111 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 Station (m) Station (m) Station (m)

Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 RS = 2310 RS = 2300 RS = 2270 .032 . .032 .08 .12 .08 .08 .12 .08 119 0 113.0 3 Legend Legend Legend 2 118 WS 100 yr with clim 111.8 WS 100 yr with clim WS 100 yr with clim 112.5 117 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 111.6 Ground Ground Ground 116 112.0 Bank Sta 111.4 Bank Sta Bank Sta 115 111.2 114 111.5 Elevation(m) Elevation(m) Elevation(m) 111.0 113 111.0 112 110.8

111 110.6 110.5 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 Station (m) Station (m) Station (m)

WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 112.5 112.0 112.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima Ground Ground Ground 112.0 111.5 111.5 Bank Sta Bank Sta Bank Sta

111.5 111.0 111.0 Elevation(m) Elevation(m) Elevation(m)

111.0 110.5 110.5

110.5 110.0 110.0 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Station (m) Station (m) Station (m)

Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 RS = 2200 RS = 2120 RS = 2115 BR .08 .12 .08 .08 .12 .08 .08 .12 .08 Legend Legend Legend 111.4 111.4 111.4 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 111.2 111.2 111.2 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 111.0 111.0 111.0 Ground Ground Ground Bank Sta 110.8 Bank Sta 110.8 Bank Sta 110.8 110.6 110.6 110.6 Elevation(m) Elevation(m) Elevation(m) 110.4 110.4 110.4 110.2 110.2

110.2 110.0 110.0

110.0 109.8 109.8 0 5 10 15 20 25 30 35 0 10 20 30 40 0 10 20 30 40 Station (m) Station (m) Station (m)

110.8 WS 100 yr with clim 110.8 WS 100 yr with clim WS 100 yr with clim

110.6 WS 20 yr with clima 110.6 WS 20 yr with clima 109.5 WS 20 yr with clima

110.4 Ground 110.4 Ground Ground Bank Sta Bank Sta Bank Sta 110.2 110.2 109.0

110.0 110.0 Elevation(m) Elevation(m) Elevation(m)

109.8 109.8 108.5

109.6 109.6

109.4 109.4 108.0 0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 5 10 15 20 25 Station (m) Station (m) Station (m)

Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 RS = 2000 RS = 1900 RS = 1800 .08 .12 .08 .08 .12 .08 .08 .12 .08 108.5 107.5 Legend Legend Legend 109.4 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 109.2 108.0 WS 20 yr with clima WS 20 yr with clima 107.0 WS 20 yr with clima 109.0 Ground Ground Ground 107.5 108.8 Bank Sta Bank Sta Bank Sta 106.5 108.6 107.0 Elevation(m) 108.4 Elevation(m) Elevation(m) 106.0 108.2 106.5 108.0

107.8 106.0 105.5 0 5 10 15 20 25 0 5 10 15 20 0 2 4 6 8 10 12 14 Station (m) Station (m) Station (m)

WS 100 yr with clim WS 100 yr with clim 106.5 WS 100 yr with clim 106.5 WS 20 yr with clima 106.5 WS 20 yr with clima WS 20 yr with clima Ground Ground 106.0 Ground Bank Sta Bank Sta Bank Sta 106.0 106.0 105.5 Elevation(m) Elevation(m) Elevation(m) 105.0 105.5 105.5 104.5

105.0 105.0 104.0 0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 10 20 30 40 Station (m) Station (m) Station (m)

106.5 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 106.0 WS 20 yr with clima WS 20 yr with clima 104.0 WS 20 yr with clima 106.0 Ground Ground Ground 105.5 Bank Sta Bank Sta Bank Sta 105.5 103.5 105.0 Elevation(m) Elevation(m) 105.0 Elevation(m) 103.0 104.5 104.5

104.0 104.0 102.5 0 10 20 30 40 0 5 10 15 20 25 30 35 0 5 10 15 20 Station (m) Station (m) Station (m)

Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 RS = 1500 RS = 1420 RS = 1415 BR . .12 .08 .08 .12 .08 .08 .12 .08 103.5 0 103.5 103.5 8 Legend Legend Legend WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 103.0 103.0 103.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima Ground Ground Ground 102.5 102.5 Bank Sta Bank Sta Bank Sta 102.5 102.0 102.0 Elevation(m) Elevation(m) Elevation(m)

102.0 101.5 101.5

101.5 101.0 101.0 0 5 10 15 20 25 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 Station (m) Station (m) Station (m)

Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 RS = 1415 BR RS = 1410 RS = 1400 .08 .12 .08 .08 .12 .08 .08 .12 .08 103.0 103.0 Legend Legend Legend 101.4 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 102.5 102.5 WS 20 yr with clima WS 20 yr with clima 101.2 WS 20 yr with clima Ground Ground 101.0 Ground 102.0 102.0 Bank Sta Bank Sta 100.8 Bank Sta 100.6 101.5 101.5 Elevation(m) Elevation(m) Elevation(m) 100.4

101.0 101.0 100.2 100.0

100.5 100.5 99.8 0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 5 10 15 20 Station (m) Station (m) Station (m)

WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 101.0 101.0 WS 20 yr with clima 101.0 WS 20 yr with clima WS 20 yr with clima Ground Ground Ground 100.5 Bank Sta Bank Sta Bank Sta 100.5 100.5 100.0 Elevation(m) Elevation(m) Elevation(m)

100.0 100.0 99.5

99.5 99.5 99.0 0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 10 20 30 40 50 Station (m) Station (m) Station (m)

WS 100 yr with clim WS 100 yr with clim 99.4 WS 100 yr with clim 101.0 100.0 WS 20 yr with clima WS 20 yr with clima 99.2 WS 20 yr with clima Ground Ground Ground 100.5 99.5 99.0 Bank Sta Bank Sta Bank Sta 98.8

100.0 99.0 98.6 Elevation(m) Elevation(m) Elevation(m)

98.4 99.5 98.5 98.2

99.0 98.0 98.0 0 10 20 30 40 50 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 Station (m) Station (m) Station (m)

98.5 WS 20 yr with clima 98.5 WS 20 yr with clima 98.2 WS 20 yr with clima

Ground Ground 98.0 Ground Bank Sta Bank Sta Bank Sta 98.0 98.0 97.8

97.6 Elevation(m) Elevation(m) Elevation(m)

97.5 97.5 97.4

97.2

97.0 97.0 97.0 0 10 20 30 40 50 60 0 10 20 30 40 50 60 0 10 20 30 40 50 60 Station (m) Station (m) Station (m)

Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 RS = 1000 RS = 900 RS = 820 .08 . .08 .08 .12 .08 .08 .12 .08 1 101 98.0 2 Legend Legend Legend 98.4 WS 100 yr with clim WS 100 yr with clim 97.5 WS 100 yr with clim 100 98.2 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima Ground Ground 97.0 Ground 98.0 99 Bank Sta Bank Sta Bank Sta 97.8 96.5

97.6 98 Elevation(m) Elevation(m) Elevation(m) 96.0 97.4 97 95.5 97.2

97.0 96 95.0 0 10 20 30 40 50 60 0 20 40 60 80 100 0 10 20 30 40 50 60 70 Station (m) Station (m) Station (m)

97.5 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 97.0 97.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 97.0 Ground Ground Ground 96.5 96.5 Bank Sta Bank Sta Bank Sta 96.5 96.0 96.0 Elevation(m) 96.0 Elevation(m) Elevation(m)

95.5 95.5 95.5

95.0 95.0 95.0 0 10 20 30 40 50 60 70 0 10 20 30 40 50 0 10 20 30 40 50 Station (m) Station (m) Station (m)

WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 96.0 95.5 95.5 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima Ground Ground Ground 95.5 95.0 95.0 Bank Sta Bank Sta Bank Sta

95.0 94.5 94.5 Elevation(m) Elevation(m) Elevation(m)

94.5 94.0 94.0

94.0 93.5 93.5 0 5 10 15 20 25 30 35 0 10 20 30 40 50 60 0 10 20 30 40 50 60 Station (m) Station (m) Station (m)

WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 95.5 95.0 95.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima Ground Ground Ground 95.0 94.5 94.5 Bank Sta Bank Sta Bank Sta

94.5 94.0 94.0 Elevation(m) Elevation(m) Elevation(m)

94.0 93.5 93.5

93.5 93.0 93.0 0 10 20 30 40 50 60 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Station (m) Station (m) Station (m)

95.0 WS 100 yr with clim 94.5 WS 100 yr with clim 94.0 WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 94.5 Ground 94.0 Ground 93.5 Ground Bank Sta Bank Sta Levee 94.0 93.5 93.0 Bank Sta

Elevation(m) 93.5 Elevation(m) 93.0 Elevation(m) 92.5

93.0 92.5 92.0

92.5 92.0 91.5 0 10 20 30 40 50 60 70 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 Station (m) Station (m) Station (m)

94.0 WS 100 yr with clim 94.0 WS 100 yr with clim 94.0 WS 100 yr with clim WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 93.5 Ground 93.5 Ground 93.5 Ground Levee Levee Levee 93.0 93.0 93.0 Bank Sta Bank Sta Bank Sta Elevation(m) Elevation(m) 92.5 Elevation(m) 92.5 92.5

92.0 92.0 92.0

91.5 91.5 91.5 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 Station (m) Station (m) Station (m)

94.0 WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim

WS 20 yr with clima 92.5 WS 20 yr with clima 92.5 WS 20 yr with clima 93.5 Ground Ground Ground 93.0 Bank Sta Levee Levee 92.0 92.0 92.5 Bank Sta Bank Sta Elevation(m) Elevation(m) Elevation(m) 92.0 91.5 91.5

91.5

91.0 91.0 91.0 0 5 10 15 20 25 30 0 5 10 15 20 0 5 10 15 20 Station (m) Station (m) Station (m)

Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 RS = 40 RS = 30 RS = 20 .08 .12 .08 .03 .08 .03 .03 . .03 93.0 92.5 92.5 0 Legend Legend 3 Legend WS 100 yr with clim WS 100 yr with clim WS 100 yr with clim 92.0 92.0 92.5 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima Ground Ground Ground 91.5 91.5 Levee Bank Sta Bank Sta 92.0 Bank Sta 91.0 91.0 Elevation(m) Elevation(m) Elevation(m)

91.5 90.5 90.5

91.0 90.0 90.0 0 2 4 6 8 10 12 14 16 18 0 2 4 6 8 10 12 14 16 18 0 5 10 15 20 25 30 35 Station (m) Station (m) Station (m)

Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 Wood Burcote Brook Development Plan: Wood Burcote Brook Development 15/10/2007 RS = 15 Culv RS = 15 Culv RS = 10 .03 . .03 .03 . .03 .03 . .03 92.5 0 92.0 0 92.0 0 3 Legend 3 Legend 3 Legend WS 100 yr with clim 91.5 WS 100 yr with clim 91.5 WS 100 yr with clim 92.0 WS 20 yr with clima WS 20 yr with clima WS 20 yr with clima 91.0 91.0 Ground Ground Ground 91.5 Bank Sta 90.5 Bank Sta 90.5 Bank Sta

90.0 90.0 91.0 Elevation(m) Elevation(m) Elevation(m) 89.5 89.5 90.5 89.0 89.0

90.0 88.5 88.5 0 5 10 15 20 25 30 35 0 10 20 30 40 50 60 0 10 20 30 40 50 60 Station (m) Station (m) Station (m) Cross-Section at STA 1400 (See Drawing 44406876/13 for Location) Comparison Between Water Levels for Existing and Post Development Conditions Climate Change Taken into Account for Both Conditions

101.0

100.5

100.0

99.5 Existing ground profile

99.0 Post development ground profile

98.5 Existing 5% annual probability (1 in 20 years) event water level

98.0 Existing 1% annual probability (1 in 100 years) event water level

97.5 Post Development 5% annual probability (1 in 20 years) event water level

97.0 Post Development 1% annual probability (1 in 100 years) event water level

96.5 Post development 100% annual probabilty (1 in 1 year) event water level

96.0

95.5

95.0

94.5

94.0

Elevation (mAOD) 93.5

93.0

92.5

92.0

91.5

91.0

90.5

90.0

89.5

89.0

88.5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 Distance (m) Cross-Section at STA 1510 (See Drawing 44406876/13 for Location) Comparison Between Water Levels for Existing and Post Development Conditions Climate Change Taken into Account for Both Conditions

101.0

100.5

100.0 Existing ground profile 99.5 Post development ground profile 99.0 Existing 5% annual probability (1 in 20 years) event water level 98.5

98.0 Existing 1% annual probability (1 in 100 years) event water level

97.5 Post Development 5% annual probability (1 in 20 years) event water level

97.0 Post Development 1% annual probability (1 in 100 years) event water level

96.5 Post development 100% annual probabilty (1 in 1 year) event water level

96.0

95.5

95.0

94.5

94.0 Elevation (mAOD)

93.5

93.0

92.5

92.0

91.5

91.0

90.5

90.0

89.5

89.0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 Distance (m) Cross-Section at STA 1800 (See Drawing 44406876/13 for Location) Comparison Between Water Levels for Existing and Post Development Conditions Climate Change Taken into Accont for Both Conditions

100.5

100.0

99.5 Existing ground profile

99.0 Post development ground profile

98.5 Existing 5% annual probability (1 in 20 years) event water level

98.0 Existing 1% annual probability (1 in 100 years) event water level

97.5 Post development 5% annual probability (1 in 20 years) event water level

97.0 Post development 1% annual probability (1 in 100 years) event water level

96.5 Post development 1% annual probability (1 in 1 year) event water level

96.0

95.5

95.0

94.5

Elevation (mAOD) 94.0

93.5

93.0

92.5

92.0

91.5

91.0

90.5

90.0

89.5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240 245 250 255 260 265 270 Distance (m) Cross-Section at STA 2000 (See Drawing 44406876/13 for Location) Comparison Between Water Levels for Existing and Post Development Conditions Climate Change Taken into Account for Both Conditions

94.5

94.0

93.5

93.0

92.5

92.0 Elevation (mAOD)

Existing ground profile 91.5 Post development ground profile

Existing 5% annual probability (1 in 20 years) event water level 91.0 Existing 1% annual probability (1 in 100 years) event water level

Post Development 5% annual probability (1 in 20 years) event water level 90.5 Post Development 1% annual probability (1 in 100 years) event water level Post development 100% annual probabilty (1 in 1 year) event water level

90.0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 Distance (m) Towcester Vale Flood Risk Assessment

Figures

Persimmon Homes Midlands Ltd\44406876 Towcester EIA\BDRP0007/FB/FB Revision 1 November 2007 BDRP0007

Figure 1 Silverstone Brook Water Levels for Existing and Climate Change Conditions for the Entire Length of the Model Annual Probability: 5% (1 in 20 years) 94

89 Elevation (m)

85 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 Distance (m)

Channel Bed Level Existing Water Level Climate Change Water Level Figure 2 Silverstone Brook Water Levels for Existing and Climate Change Conditions for the Entire Length of the Model Annual Probability: 1% (1 in 100 years)

89 Elevation (m) Elevation

85 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 Distance (m)

Channel Bed Level Existing Water Level Climate Change Water Level Figure 3 Silverstone Brook Water Levels for Existing and Climate Change Conditions for the Entire Length of the Model Annual Probability: 0.5% (1 in 200 years)

89 Elevation (m) Elevation

85 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 Distance (m)

Channel Bed Level Existing Water Level Climate Change Water Level Figure 4 Wood Burcote Brook Water Levels for Existing and Climate Change Conditions for the Entire Length of the Model Annual Probability: 5% (1 in 20 years) 115

110

105

100

95 Elevation (m) Elevation

80 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 Distance (m)

Channel Bed Level Existing Water Level Climate Change Water Level Figure 5 Wood Burcote Brook Water Levels for Existing and Climate Change Conditions for the Entire Length of the Model Annual Probability: 1% (1 in 100 years) 115

110

105

100

95 Elevation (m) Elevation

80 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

Channel Bed Level DistanceExisting (m)Water Level Climate Change Water Level Figure 6 Wood Burcote Brook Water Levels for Existing and Climate Change Conditions for the Entire Length of the Model Annual Probability: 0.5% (1 in 200 years) 115

110

105

100

95 Elevation (m) Elevation

80 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 Distance (m)

Channel Bed Level Existing Water Level Climate Change Water Level Figure 7 Silverstone Brook Water Levels for Existing and Post-development Conditions from Model Downstream End to STA 1500 Flows were Adjusted for Climate Change Annual Probability: 5% (1 in 20 years) 92.00

90.00

88.00 Elevation (m)

86.00

90.00

88.00 Elevation (m)

86.00

84.00 0 100 200 300 400 500 600 700 800 900 1000 1100 Distance (m) Existing Conditions Channel Bed Level Developed Conditions Channel Bed Existing Conditions Water Level Developed Conditions Water Level Figure 9 Wood Burcote Brook Water Levels for Existing and Post-development Conditions for the Entire Legth of the Model Flows were Adjusted for Climate Change Annual Probability: 5% (1 in 20 years) 116 114 112 110 108 106 104 102 100 98 96 Elevation Elevation (m) 94 92 90 88 86 84 82 80 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 Distance (m) Existing Conditions Channel Bed Level Developed Conditions Channel Bed Existing Conditions Water Level Developed Conditions Water Level Figure 10 Wood Burcote Brook Water Levels for Existing and Post-development Conditions for the Entire Length of the Model Flows were Adjusted for Climate Change Annual Probability: 1% (1 in 100 years)

116 114 112 110 108 106 104 102 100 98 96 Elevation Elevation (m) 94 92 90 88 86 84 82 80 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 Distance (m) Existing Conditions Channel Bed Level Developed Conditions Channel Bed Existing Conditions Water Level Developed Conditions Water Level