Open Decision Item

One Corby Policy Committee 11th September 2012

The Corby Culvert and related improvement works

SYNOPSIS That Members agree a way forward in terms of the necessary improvements that are required to the Corby Culvert.

1. Relevant Background Details A structure known as the ‘Corby Culvert’ is located on the Willow Brook just downstream of the clean water outfall from the Corby sewage treatment works in Weldon Road operated by Anglian Water. It is positioned where a railway line serving the Tata steelworks crosses the Brook.

This Culvert is nearing capacity which has implications for the Discharge Consent issued by the Environment Agency (EA) to Anglian Water. This Consent controls how much water can be released from the sewage treatment works into the Willow Brook.

It is likely that, unless the capacity of the Culvert is increased in the near future, the Environment Agency will begin to object to Planning Applications in Corby Borough on the grounds that there is not enough capacity for the sewage works to be able to discharge water into the Willow Brook after treating the foul drainage from them.

In view of this, without increased capacity in the Culvert, future housing and employment development in Corby could be brought to a halt.

2. Report The Corby Water Cycle Strategy of 2006 originally identified the capacity of the Culvert to be a constraint on development. Work by Halcrow at the time established a cost of £1.13 million to increase the capacity to accommodate Corby’s future growth to 2021 (£1.02 million for construction plus £110,000 in land costs). This assumed the Culvert would have to be replaced with a larger one.

Since the publication of this work, the aim has been that the cost of the Culvert works would be secured via Section 106 contributions made in relation to Planning Permissions.

However, as time has gone on, it has become apparent that this cost will not be affordable for many years. During this time, if growth in the Borough continues, there is a danger that the Culvert may reach capacity.

In view of this, further work has now been undertaken by Atkins on behalf of the Council that has identified that there is a cheaper solution to resolve this issue at a defined cost of £305,000. Their suggested solution involves increasing the capacity of the water course in the vicinity of the culvert and bank strengthening works. A copy of the Atkins report is available in the Members Room and a location plan and photograph of the Culvert are attached in Appendix 1 of this Report.

The conclusions in the Atkins Report have been accepted by the Environment Agency and Anglian Water.

046 1 Whilst the cost suggested by Atkins is much more achievable, and we do have some payments made to date from existing Legal Agreements of this nature, it is still not anticipated that the full amount of money needed will be received in the near future.

In view of this, Growing Places Funding is being sought from the Northamptonshire Enterprise Partnership (NEP) in order that the Culvert works can be carried out in advance of receiving sufficient Section 106 funds. This will enable the Culvert works to be carried out now in order to prevent this constraint bringing development in the Borough to a halt. This bid is currently ongoing and the Council is currently working on providing additional information in order that our request for funding can be considered further. At the time of writing this report, once payment is made for current water related consultancy work, Corby Borough Council will have £129,182 left from Section 106 Water Cycle Strategy Contributions received to date. Whilst this will leave none of this money for other drainage works, it is considered reasonable to put it all towards the Culvert works as this is recognised as the priority drainage scheme that is linked to new development in the Borough at the present time. This will mean that there is a shortfall of approximately £176,000 compared to the £305,000 recommended for the Culvert works by Atkins in their report of May 2012. In terms of anticipated Section 106 Water Cycle receipts in the near future from existing Section 106 Legal Agreements, if all the developments they relate to proceed as planned and the related money is received, a further £62,964.50 will be received. Again, it is considered justified to spend all of this on the Culvert as the Council’s priority drainage scheme. This will bring the total up to £192,146.50 and still leaves a shortfall of £112,853.50. The latest housing figures received on 1st June 2012 (which supersede those in the Atkins report dated May 2012) for sites with a potential to attract Section 106 Water Cycle contributions show a further 2106 dwellings are estimated to gain Permission in the Borough between 1st April 2012 and 31st March 2014. However, this figure includes a site in Bridge Court which (because it received Permission on 2nd April 2012) was also included in the list received on 28th May of anticipated Water Cycle receipts in the near future. This is shown as having 31 dwellings in the table of anticipated Permissions and these therefore need deducting from the 2106 to prevent double counting. This gives a revised figure of 2075 dwellings. If the total shortfall in funding is divided by this number of dwellings and a small amount of money is included to cover the NEP’s required administrative, appraisal and legal costs (£5000), this means that the Council has to seek a figure of approximately £60.00 per dwelling in future Section 106 contributions towards the Culvert works. This amount may vary depending what sites come forward, what the final costs of the Culvert works are and whether the total that Section 106 funding is secured from is 2075 dwellings. A table is attached in Appendix 2 to this report which summarises in rounded figures how the amount required for the works may be secured. Members should note that, in coming to these conclusions, it has been decided not to include commercial developments because most of the schemes of this nature that are coming forward at present are either small in scale or are warehouses which do not have the same impact on the foul drainage infrastructure as housing. The Council would, however, wish to reserve the right to secure Section 106 funding if a major commercial use came forward that did have a serious impact on the foul drainage system. This would, of course mean that the money needed for the improvements could be received earlier. It should also be noted that the payments which are still due from the Priors Hall and Little Stanion schemes have not been included in the calculations as it is understood these developments are currently seeking to secure a separate Sustainable Waste Water

2 Treatment Works which would discharge into the Willow Brook downstream of the Culvert. On this basis they will not impact on it. If this Treatment Works does not proceed or does not serve both these developments, some or all of these payments could be pursued and, again, would mean that more money would be received for the Culvert works at an earlier date. In the case of Priors Hall, this would be based on £223 per dwelling with slightly less per property being received for Little Stanion. Taking these points into account, and using the above figures, the Council has bid for a total of £181,000 to cover the shortfall of approximately £176,000 needed to carry out the works now plus £5000 to allow us to pay the NEP’s costs in administering the fund. Proceeding in this way is considered to be the best way to secure the necessary works in the vicinity of the Culvert at the earliest opportunity. This will prevent the current capacity being a constraint on development and therefore enable the continued growth of the Borough in line with the Council’s objectives. If our bid is successful, the NEP will require the money to be repaid in a maximum of 5 years. The aim is therefore that the amount secured will be repaid from money received from existing and future Section 106 Agreements. Related to this, the NEP requires the Council to enter into a Legal Agreement to secure the repayment of the funding. In considering this approach, Members need to be aware that there is a risk associated with this in that developments which are anticipated to secure the required Section 106 funding to repay the NEP may not come forward as planned. There is also the possibility that developers may try to argue that, once the works have been carried out, a financial contribution towards them is unnecessary. However, our response to this would be that they were advance funded to prevent the Culvert being a constraint on developments such as theirs and a contribution is still required to enable the repayment of this money. If, as a result of the above, there is a shortfall in the money needed to repay NEP, this would have to be found from elsewhere in the Council’s funds. 3. Options to be considered (if any) (i) Do nothing - This brings the risk that the capacity of the Culvert may prevent further development in the Borough in the near future. (ii) Support the suggested way forward in this Report to secure the improvement works in the vicinity of the Culvert – This will prevent the capacity of the Culvert being a constraint on future development in the Borough.

4. Issues to be taken into account:- Policy Priorities Regeneration and Growth of Corby to double the population by 2030 is a key Council priority. This report proposes a way which would assist in bringing housing sites forward to allow for population expansion. Financial and risk This report suggests a way to secure the necessary works in the vicinity of the Culvert to come forward at the earliest opportunity. This involves spending the balance of Section 106 Water Cycle Strategy money received to date on these works and securing funding for the remaining £181,000 (which we will have to pay back) via a bid to the Northamptonshire Enterprise Partnership. In terms of risk, if the Council does not secure the balance of money needed to pay for the Culvert works via Section 106 contributions, we will have to find another means of repaying the funding.

3 In addition, if we proceed in this way, we will be committing all of the Section 106 Water Cycle money we have received at the present time and are likely to receive in the near future to a particular project. This will leave none of this funding for other drainage related works. However, the improvements to the Corby Culvert are seen as the Council’s priority drainage project that is linked to the growth of the Borough at the present time. Legal The Northamptonshire Enterprise Partnership requires the Council to enter into a Legal Agreement to secure the repayment of any money we receive from them in relation to this matter. The Council’s Legal Services Team has confirmed that the expenditure of the Section 106 Corby Water Cycle Strategy contributions in this manner is in accordance with the purpose for which they were received. Performance Information Any mechanism for enabling Planning Applications to come forward may assist in meeting key performance targets such as: NI154 - Net Additional homes provided NI155 - Number of affordable homes delivered NI157 – Planning Application performance Best Value The conclusions in the Atkins Report dated May 2012 demonstrate value for money as they suggest a cheaper solution to the issue of the Corby Culvert compared to previous consultancy work. Human Rights No specific implications in this report Equalities No specific implications in this report Sustainability The National Planning Policy Framework advises Local Planning Authorities to approve sustainable development without delay. Proceeding with carrying out the Culvert improvement works now will help to ensure that sustainable development is not unnecessarily delayed. Community Safety The Culvert works will help reduce the possibility of flooding in the vicinity of the site.

5. Conclusion Work commissioned on behalf of the Council shows there is limited capacity in a culvert on the Willow Brook and suggests a solution to this issue. Part of the funding for these works can come from existing Section 106 receipts and it is proposed that the remainder is secured via funding from the Northamptonshire Enterprise Partnership. Assuming our bid for funding is successful, this money will have to be repaid in due course and the aim would be to secure this from Section 106 contributions. Proceeding in this way, is considered to be the best way to secure the necessary works in the vicinity of the Culvert at the earliest opportunity. This will prevent the current capacity being a constraint on development and therefore enable the continued growth of the Borough in line with the Council’s objectives. 6. Recommendation Members are asked to resolve to:

4 1. Accept the conclusions in the Atkins Report dated May 2012 which identifies the works needed in the vicinity of the Corby Culvert and the associated costs; 2. Support the use of the remaining Section 106 Water Cycle money received to date towards the Corby Culvert works and to support the Council’s bid for the balance of the money needed to secure these works via the Northamptonshire Enterprise Partnership’s Growing Places Fund; 3. If our bid for funding is successful, delegate to the Council’s Acting Chief Executive the powers for the signing of a Legal Agreement to secure the repayment of this funding in due course; 4. Support the collection of the balance needed to repay this funding via Section 106 contributions from Agreements in relation to existing Planning Permissions which secure Water Cycle Strategy contributions and proposed housing developments in the Borough; and 5. Agree to the Council commissioning the necessary improvement works in the vicinity of the Corby Culvert.

Background Papers 1. Corby Water Cycle Strategy - Phase 1, Outline Strategy, Technical Report – September 2005. 2. Corby Water Cycle Strategy - Phase 2, Detailed Strategy, Technical report – November 2006. 3. Corby Water Cycle Strategy Update - Corby Culvert - Options Assessment Report by Atkins for Corby Borough Council dated May 2012

External Consultations None List of Appendices Appendix 1 - Site Location Plan and photograph of the Corby Culvert. Appendix 2 - Summary of how it is anticipated the funding for the Culvert Works is to be achieved and repaid.

Officer to Contact Wayne Cattell, Major Projects Planner Direct Line: 01536 464099 Email: [email protected]

Appendix 1

5 Location Plan of the Culvert and Photograph.

6

The Corby Culvert viewed from the West

7 Appendix 2

Summary of how it is anticipated the funding for the Culvert Works can be achieved and repaid.

Source of funding Amount Remaining money already £129,000 received from existing Section 106 Agreements. Amount of ‘loan’ requested via £181,000 the growing places fund Total cost of works £310,000 including the Northamptonshire Enterprise Partnership’s fees Estimated funds to be £63,000 received in the near future from existing Section 106 Agreements Amount to be secured from £118,000 future Section 106 Agreements. Balance to be repaid £181,000

8

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment Corby Borough Council

May 2012

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

Notice

This document and its contents have been prepared and are intended solely for Corby Borough Council‟s information and use in relation to the Corby Water Cycle Strategy Update – Corby Culvert.

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

This document has 22 pages including the cover.

Document history

Job number: 5040250 Document ref: 71_DG_021 Corby WCS Update Options Assessment Revision Purpose description Originated Checked Reviewed Authorised Date Rev 1.0 DRAFT Internal Client LT - TR - March Review Only 2012 Rev 2.0 Issue for Client Review LT JL TR JL April 2012 Rev 2.1 Updated with review LT JL TR JL May 2012 comments Rev 3.0 Updated with review LT JL TR JL May 2012 comments

Client signoff

Client Corby Borough Council

Project Corby Water Cycle Strategy Update - Corby Culvert

Document title Options Assessment

Job no. 5040250

Copy no. 3.0

Document 71_DG_021 Corby WCS Update Options Assessment reference

Atkins Options Assessment | Version 3.0 | May 2012

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

Table of contents

Chapter Pages Glossary iv Executive summary v 1. Introduction 1 1.1. Background 1 1.2. Corby Culvert 1 1.3. Scope 2 2. Hydraulic Modelling 3 2.1. Overview 3 2.2. Model Approach 3 2.3. Model Results 3 3. Options Assessment 4 3.1. Overview of Options 4 3.2. Mitigation Options 4 3.3. Cost Appraisal 8 3.4. Recommended Option 8 3.5. Potential for Betterment 9 3.6. Implementation of Preferred Option 10 4. Conclusions and Recommendations 11 4.1. Conclusions 11 4.2. Recommendations 11

Appendices 13 Appendix A. Hydraulic Model Report 14 Appendix B. Meeting Minutes 15

Tables Table 1. Peak water level changes between current and Phase 2 scenarios 3 Table 2. Options Cost Breakdown 8 Table 3. Construction Cost Breakdown for Option 4 9

Figures Figure 1. Corby Culvert Location 1 Figure 2. Schematic of Channel Realignment Proposal 5 Figure 3. Alteration to cross section upstream of the Corby Culvert 7 Figure 4. Alteration to cross section downstream of the Corby Culvert 7

Atkins Options Assessment | Version 3.0 | May 2012

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

Glossary

Term Meaning/Definition AEP Annual Exceedance Probability CIL Community Infrastructure Levy FSR Flood Storage Reservoir SOP Standard of Protection STW Sewage Treatment Works mAOD Metres above Ordnance Datum WCS Water Cycle Strategy

Event Severity

The severities of the events discussed in this report are defined mainly as Annual Exceedance Probabilities (AEP). The AEP is the probability that there will be an event exceeding a particular severity in any one year.

Annual Exceedance Probability Probability (AEP) (chance in any given year) 50% 1 in 2 20% 1 in 5 10% 1 in 10 5% 1 in 20 4% 1 in 25 2% 1 in 50 1.33% 1 in 75 1% 1 in 100 0.5% 1 in 200 0.1% 1 in 1000

Atkins Options Assessment | Version 3.0 | May 2012 iv

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

Executive summary

The Corby Water Cycle Strategy (WCS) was completed in 2006 and outlined various mitigation measures that could be provided within the Corby Borough to manage flood risk in the future and as a result of further development. The WCS highlighted the constricting culvert downstream of the Sewage Treatment Works (STW) and the potential works that could be undertaken to prevent an increased risk as a result of future development and the associated STW increased discharge. The constricting culvert, the Corby Culvert, is located on the Southern Arm of Willow Brook. This options report outlines the potential options for mitigation and an indication of initial costs, both at the location of the Corby Culvert and the downstream channel.

The requirement for an additional culvert and hence significant engineering works was assessed through hydraulic modelling of the Southern Arm of Willow Brook. The modelling indicated that the future increase in flood level, as a result of increased discharge from the STW due to future development within Corby, is 100mm during the 10% Annual Exceedance Probability (AEP) event and 30mm during the 1% AEP event. Following consultation with the Environment Agency it was determined that the potential increase in flood risk may not warrant high financial investment and that other options should be considered.

Therefore the following five options have been considered for this assessment:

1. New additional culvert at the location of the Corby Culvert; 2. Moving the STW outfall downstream of the Corby Culvert; 3. Improving the channel conveyance adjacent to the downstream end of the Corby Culvert through channel alignment and vegetation clearance; 4. Provision of additional storage and vegetation clearance at the location of the STW outfall and adjacent to the downstream end of the Corby Culvert; and 5. Increase capacity within the Weldon Flood Storage Reservoir (FSR), through excavation.

The works outlined in Options 1 and 2 would reduce water backing up at the upstream end of the Corby Culvert and hence lower flood levels and prevent increased flood levels following increased discharge from the STW. The options require significant engineering works through the railway embankment and would increase discharge downstream. To prevent increased flood risk to properties, which are located downstream of the FSR, Option 5 would also have to be undertaken. The cost of Options 1 and 2 are both individually more than £2 million and would also require Option 5 to be carried out which may cost £300,000 or more.

Modelling was used to determine the impacts of Option 3; however the model did not identify that this option would impact on flood levels upstream of the Corby Culvert. The model does not fully represent the misalignment and therefore a further hydraulic modelling exercise would need to be carried out to determine whether Option 3 would sufficiently mitigate flows and if so the additional requirement for excavation in the FSR, i.e. Option 5.

This assessment has identified Option 4 to be the recommended mitigation measure based on cost. This option is to increase floodplain storage upstream of the Corby Culvert without increasing flood levels. As a result flood levels are not increased downstream and works to the FSR is not required. As well as increasing storage through excavation, the channel and an additional 30m width will be cleared to provide a clean channel with short grass either side. During the 1% AEP event, there will be no increase in flood levels as a result of increased discharge following Phase 2 development and would actually provide betterment by up to 8mm at the location of the STW outfall. Elsewhere the model shows either no change in flood levels or betterment. During the 10% AEP event there would be an increase in peak flood levels by 50mm at the location of the STW, although this is half than the baseline scenario. However as part of the works for this option it may be determined that further excavation is feasible which could result in a lower or no increase in flood level during the 10% AEP event. The cost of this Option alone is likely to be approximately £205,000.

To maintain the benefits of Option 4, maintenance would be required at a likely sum of £5,000 annually. Alternatively the mitigation could be oversized to include redundancy and only minimal maintenance, such as that currently being undertaken would be required. The costs associated with either option would be approximately £100,000. It will only be during the detailed design stage that it will become apparent what the optimum combination will be for storage volume and maintenance regime.

Atkins Options Assessment | Version 3.0 | May 2012 v

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

It is recommended from this assessment that Option 4 should be taken forward as the preferred option for mitigation of the increased discharge from the STW as a result of future development within Corby. It is proposed that a likely cost for this option will be £160,000 if a 50mm increase in peak flows at the STW is acceptable during the 10% AEP event. Alternatively further excavation may be possible to reduce this increase.

It is recommended that the overall costs for the preferred option are taken forward as £305,000.

Atkins Options Assessment | Version 3.0 | May 2012 vi

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

1. Introduction

1.1. Background In 2006, the Corby Water Cycle Strategy (WCS) (Corby Borough Council, 2006) was completed for the Corby Borough, which outlined a range of mitigation measures that would prevent increased flood risk in the future as a result of further development within Corby. Corby Borough Council commissioned Atkins to determine the requirements for one of the mitigation options (works to the Corby Culvert) and to provide a cost and options appraisal for this measure. The WCS recommended a minimum contribution of £363 per dwelling to fund the mitigation measures set out in the strategy (see Table 11.6 of the WCS). The estimated costs from this assessment will be used to determine appropriate developer contributions to fund the preferred mitigation option.

1.2. Corby Culvert The WCS identified that the railway culvert (referred to as the Corby Culvert), downstream of the Corby Sewage Treatment Works (STW), acts as a constriction and causes inundation of surrounding areas during flood events. The Corby Culvert is located on the Southern Arm of Willow Brook at Grid Reference 490764, 288842 and as shown in Figure 1 below.

© Crown Copyright. All rights reserved. Corby Borough Council, 100018791, 2012. Figure 1. Corby Culvert Location

As a result of future development within Corby, the STW will be required to treat additional volumes leading to an increase in discharge to the Willow Brook. To prevent increased flood risk as a result of the increased discharge, the WCS recommended that an additional culvert be constructed at this location. This option would require a high financial input, with an estimated cost of £1,169k in 2006. The WCS also outlined that works to the Corby Culvert would be dependent on increasing capacity within the Weldon Flood Storage Reservoir (FSR) and channel maintenance to ensure the works would not result in an increased risk at downstream locations.

Corby Borough Council has commissioned Atkins to complete an assessment of this previous proposal which involves modelling flood flows and providing an indication of costs for required works/improvements.

Atkins Options Assessment | Version 3.0 | May 2012 1

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

1.3. Scope The scope of this assessment is as follows:

 To refine the drainage works identified in the 2006 WCS. This involved carrying out hydraulic modelling (alteration to an existing model) to determine changes in fluvial flood risk as a result of increased discharge from the STW as a result of future development within Corby for Phase 1 (up to 2021) and 2 (up to 2031);  Use the hydraulic modelling result to determine requirements of potential mitigation measures;  To provide initial cost estimates of potential mitigation measures with the aim to identify the most feasible; and  To identify future funding mechanisms and advise on a „per residential unit‟ unit that could be brought forward.

Atkins Options Assessment | Version 3.0 | May 2012 2

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

2. Hydraulic Modelling

2.1. Overview The Environment Agency provided the Willow Brook hydraulic model for this assessment. Following a number of required updates, the model was run for a range of events from the 10% AEP to the 1% AEP event with an allowance for climate change for current and future development up to 2031. This section provides an outline of the modelling assessment; the full model report as agreed with the Environment Agency is included within Appendix A.

2.2. Model Approach The hydraulic model provided by the Environment Agency was updated with the improvement works to the FSR (completed in 2009) and with an inflow to represent the STW discharge to produce a current day model scenario. The current day and future (Phase 1 and 2 development) discharge rates were provided by Anglian Water and were converted to hydrographs for inclusion with the model.

The model was run for the three scenarios for a range of return periods to allow a comparison of peak flood levels, duration of inundation and the associated changes in flood risk as a result of increased discharge from the STW.

2.3. Model Results Peak water level increases were observed in the model as a result of both Phase 1 and Phase 2 development, however the difference between the two phases was minimal. Therefore this result section focuses on changes in flood risk following Phase 2 development, i.e. up to 2031. Table 1 below shows the changes in peak water levels between the current and Phase 2 development scenarios. The locations shown in Table 1 are mapped within the modelling report in Appendix A.

Table 1. Peak water level changes between current and Phase 2 scenarios Location Chainage 10% AEP 4% AEP 2% AEP 1.3%AEP 1% AEP (location in model) Upstream of WBS3374 60mm 64mm 30mm 21mm 24mm STW inflow STW inflow WBS3054 98mm 51mm 45mm (at 47mm 31mm adjacent node WBS3018) Within the FSR WBS1858 12mm 5mm 4mm 3mm 7mm Downstream of WBS1647 71mm (at 18mm 17mm (at 15mm (at 14mm the FSR adjacent node adjacent node adjacent node WBS1630) WBS1630) WBS1795) Upstream of WI21647 35mm 15mm 14mm 16mm 13mm Deenethorpe constrictions

The results show that peak flood levels do increase in the vicinity of the STW outfall and upstream of the Corby culvert and hence improvements works would be required. However the increases are not extreme and as agreed with the Environment Agency during the meeting 16th February 2012 (see Appendix B) other options (in addition to significant financial investment, i.e. the construction of a new culvert through the railway embankment) would be worth exploring which could provide mitigation at a significantly lower financial cost.

Atkins Options Assessment | Version 3.0 | May 2012 3

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

3. Options Assessment

3.1. Overview of Options Following the completion of the modelling assessment and during consultation with Corby Borough Council and the Environment Agency it was identified that extensive works, such as the construction of a new culvert may not be required to mitigate the impact of the proposed development. Therefore additional potential options have been considered, including downstream improvements. The mitigation options which have been considered for this assessment are as follows:

1. An additional culvert at the location of the existing Corby Culvert (as recommended in the Corby WCS);

2. Moving the outfall of the STW downstream of the Corby Culvert;

3. Channel realignment and vegetation removal at the downstream end of the Corby Culvert;

4. Provision of additional storage and vegetation clearance at the location of the STW outfall and adjacent to the downstream end of the Corby Culvert; and

5. Increasing the capacity of the Weldon FSR through excavation (rather than increased embankment height).

3.2. Mitigation Options

3.2.1. Additional Culvert (Option 1) The Corby WCS suggested the provision of an additional culvert at the location of the Corby Culvert to allow for increased capacity through the embankment. It was proposed that a new 1500mm culvert would be installed to reduce the flow constriction at this location. The aim of such works is to prevent an increase in peak flood levels upstream of the Corby Culvert at the location of the STW as a result of increased discharge following Phase 2 development. This option has the potential to provide betterment as flood levels may reduce from current levels.

This option would increase the capacity of the culvert and result in additional flow in downstream areas. To prevent an increase in flood risk in downstream areas through the reduction in Standard of Protection (SOP) offered by the FSR, works to the FSR (i.e. Option 5) would also be required. At this stage the required excavation at the FSR is unknown and would have to be determined through hydraulic modelling. Although at this stage, it is unlikely that Option 1 will be implemented due to cost (approx £1.9 million plus FSR works, see Section 3.3) and hence it was not deemed necessary to complete such modelling.

3.2.2. STW Outfall Relocation (Option 2) The addition of the culvert was identified to be of high cost due to the significant engineering works required. As a result it was suggested that the outfall of the STW could be relocated downstream of the Corby Culvert hence preventing an increase in flood levels upstream of the Corby Culvert as a result of increased discharge. This option also has the potential to provide betterment as flood levels may actually reduce from current levels.

Consultation was not held with Anglian Water in relation to the potential movement of the outfall and hence the exact requirements are unknown. The costing of this option was based on the anticipated engineering works required. To move the outfall downstream of the Corby Culvert, the outfall pipe would need to be located through the railway embankment. It was not deemed suitable that this outfall pipe would pass through the existing culvert as it would cause additional constriction problems at this location. As a result this option (like Option 1) would require significant engineering works through the railway embankment and incur high costs.

This option would result in additional flow in downstream areas because less volume will be held upstream of the constricting Corby culvert. To prevent an increase in flood risk in downstream areas through the reduction in SOP offered by the FSR, works to the FSR (i.e. Option 5) would also be required. At this stage

Atkins Options Assessment | Version 3.0 | May 2012 4

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment the required excavation at the FSR is unknown and would have to be determined through hydraulic modelling. Although it is unlikely that Option 2 will be implemented due to high cost (approx £2 million plus FSR works see Section 3.3) and hence it was not deemed necessary to complete such modelling.

3.2.3. Channel Realignment Downstream of the Corby Culvert (Option 3) Adjacent to the downstream end of the Corby Culvert, the channel is misaligned from the culvert which may contribute to backing up of water upstream of the Corby Culvert. It is proposed that excavation is carried out at this location to straighten the channel and to increase the storage capacity as shown on Figure 2. For the purpose of this assessment it is proposed that the channel realignment will be achieved through excavation rather than the use of sheet piles.

To further improve the conveyance of the channel it is proposed that vegetation clearance is carried out within the areas that would be inundated during the 1% AEP event. To ensure that the channel continues to perform as required a maintenance regime including ongoing vegetation removal will be necessary for long term benefit.

This option is likely to improve flood levels downstream of the Corby Culvert and hence may increase conveyance through the culvert, which in turn could reduce flood levels upstream of the Corby Culvert. Initial modelling has been undertaken to determine the impact of vegetation removal and increased storage availability, however this does not indicate improved flood levels upstream of the Corby Culvert.

The channel misalignment is not fully represented in the 1d model. This is because the Willow Brook model was developed to provide a strategic overview of flood risk for the Willow Brook catchment. The modelling undertaken to date has been a comparative modelling exercise to determine the impact of modelled levels and flows in Willow Brook as a result of the increased discharge from Corby STW and potential mitigation options. The alignment of the channel in the model is therefore fit for this purpose. However if the strategic model is used for detailed design, then the alignment of the channel within the model should be reviewed. In any case, if this option does improve conveyance, it is possible that flood risk may increase in downstream areas which would require further mitigation through increasing capacity at the FSR i.e. Option 5, to prevent a reduction in the FSR SOP.

A high level overview of costs have been provided, but if this option is taken forward then further modelling and assessment would be recommended to ensure both that the works would mitigate flood risk from increased STW outfall and would not cause an increased risk elsewhere. The overview of costs has been determined on the assumption that altering the channel along a 100m reach, 50m wide and excavating 4m deep would effectively realign the channel.

© Crown Copyright. All rights reserved. Corby Borough Council, 100018791, 2012 Figure 2. Schematic of Channel Realignment Proposal

Atkins Options Assessment | Version 3.0 | May 2012 5

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

3.2.4. Increased Storage at the STW outfall and Downstream of the Corby Culvert (Option 4) The modelling assessment included as Appendix A, indicated that the most significant impact of increased discharge from the STW is located at the STW outfall, upstream of the Corby Culvert. As a result this option is proposed to increase flood storage at this location and immediately downstream of the Corby Culvert. The alteration in cross section at these locations is shown in Figures 3 and 4.

Storage for this option will be provided along an approximate 200m reach upstream of the Corby Culvert at a similar level to the 10% AEP flood level, which is approximately between 89-90 meters Above Ordnance Datum (mAOD). In addition vegetation clearance and channel maintenance is required within the areas inundated during the 10% AEP event. The vegetation clearance is required to improve channel roughness to an equivalent Manning‟s n of 0.035, which represents a clean channel and short grass. A Manning‟s n value is used within hydraulic modelling to determine surface roughness which will impact on conveyance and flow rates. Values for Manning‟s n are taken from Chow (1959) and range from 0.010 to 0.200; a low value represents a smooth surface and hence higher conveyance.

This option also requires increased storage and maintenance up to approximately 20m downstream of the Corby Culvert. As above, this will be achieved through excavation and improving channel roughness to represent a clean channel and short grass. As part of the works a working Method Statement would be required for submission to the Environment Agency to ensure that the constructional phase adequately manages runoff and associated pollution in line with the appropriate Pollution Prevention Guidelines (PPGs produced by the Environment Agency).

At an early stage of this Options Assessment, Option 4 was identified as the likely preferred option based on cost and likely effective mitigation and hence the impact was assessed through modelling. It has been determined that the proposed works would provide betterment in relation to reducing peak flood levels at the location of the STW outfall by between 0 and 8mm during the 1% AEP event up to the Phase 2 development scenario. Elsewhere the model either showed betterment through the reduction of peak levels by up to 10mm or no change from the baseline scenario during the 1% AEP event.

Modelling was also carried out to determine the impact of the option during the 10% AEP event. It was determined that without implementation of Option 4, flood levels as a result of Phase 2 development would increase by approximately 100mm at the location of the STW outfall, however following implementation of Option 4, this would be reduced to approximately 50mm. It is possible that sufficient storage could be provided through further excavation following a review of topographic information and the identification of additional areas which could be excavated.

During both the 1% and 10% AEP events, Option 4 would result in a minimal (<4mm) increase in peak water levels at the location of the FSR and further downstream following Phase 2 development. As a result, if Option 4 was carried out, there would be no requirement for works to the FSR because the FSR SOP would not be reduced.

As part of this Option it would be required that further assessment is carried out to determine the exact location of excavation. This would require detailed topographic survey and additional modelling. It may be possible to determine from the further assessment that additional excavation would result in no increase in peak flood levels during the 10% AEP event as a result of Phase 2 development.

The cost overview for this option assumes an excavation volume of 3,700m3, which is based on the cross section information within the hydraulic model and likely areas which could be excavated. As a result the volume of excavation may alter following a review of detailed topographic information.

To ensure that this option provides long term mitigation, ongoing maintenance would be required to ensure that the channel is maintained as a clean channel and with short grass. At present access to this reach of Willow Brook is restricted to foot access via the STW.

Atkins Options Assessment | Version 3.0 | May 2012 6

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

Figure 3. Alteration to cross section upstream of the Corby Culvert

Figure 4. Alteration to cross section downstream of the Corby Culvert

3.2.5. Increased Capacity of the FSR (Option 5) Three of the proposed options outlined above are suggested to improve conveyance along Willow Brook to prevent backing up at the Corby Culvert. The impact of this could be to increase flood levels downstream and hence further mitigation would be required. As a result it is proposed that if the preferred option increases peak levels downstream then the capacity of the FSR would be increased to prevent increased flows downstream of the FSR (i.e. to prevent a reduction in the FSR SOP) which may impact on properties.

To increase the storage capacity of the FSR it is proposed that excavation is carried out such that flood levels are reduced within the FSR. This option also involves the removal of vegetation, specifically larger shrubs and trees. The costs have been provided which assume the excavation depth will be 2m over a 130m reach with a width of 50m. The requirement of excavation would need to be determined through the use of hydraulic modelling to provide a better indication of cost if either Option 1, 2 or 3 is proposed as the option may require greater excavation volume.

Atkins Options Assessment | Version 3.0 | May 2012 7

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

To improve the SOP for Willow Brook, the WCS suggests increasing the SOP of the FSR. If work were to be carried out on the FSR to mitigate the increase in STW discharge, there would be the opportunity for significant efficiency savings by also carrying out further work at the same time to increase the overall storage potential and hence the SOP.

3.3. Cost Appraisal The costs provided within this section are based on a high level review to determine which options would be financially feasible. The costs are based on SPON'S Civil Engineering and Highway Works Price Book 2007 and have been benchmarked against a recent similar project. An overview of the costs is provided in Table 2.

Table 2. Options Cost Breakdown

Options Cost for Option Other Works Required Total cost for Option 1 (Additional Culvert) £1,900,000. Option 5 £2,200,000 2 (STW Outfall £2,000,000. Option 5 £2,300,000 Relocation) 3 (Channel Realignment) £470,000 Unknown at this stage £470,000 (minimum) 4 (Increased Storage at £160,000 N/A £160,000 STW) 5 (Increased Storage at £300,000 N/A £300,000 FSR)

The cost overview for the options above is based on the following assumptions:

 The costs include the required works, design costs, site investigations, contract management and supervision;  An optimism bias of 60% (contingency);  All excavated material could be deposited within 1 mile from site and will not be contaminated; and  That land purchase/compensation does not exceed £20,000.

Yearly maintenance costs are not included within the proposed costs provided in Table 2, however need to be considered as part of the options appraisal. Options 1 and 2 have been considered inappropriate due to high costs and hence maintenance costs for these options have not been determined. It is proposed that maintenance for Options 3, 4 & 5 would be up to £5,000 per annum each for the life time of the development, assumed to be 60 years.

3.4. Recommended Option At this stage it is proposed that Option 4, increasing storage at the location of the STW outfall and just downstream of the Corby Culvert is taken forward as the preferred option based on cost.

This Option assumes that an increase in peak flood levels of approximately 50mm would be acceptable at the location of the STW during 10% AEP event and slight betterment will be provided at the 1% AEP event. Without Option 4, the peak flood levels at this location as a result of Phase 2 development would be 100mm. As part of the works to determine the exact locations of excavation, it may be possible to determine that additional excavation could be carried out to prevent an increase in flood levels at this location. Without detailed topographic data for the areas it is not possible to determine how much excavation would be required, but if the excavation is 50% greater than the estimates assumed here, the additional cost would be £45,000 and hence the total for this option would be £205,000.

A breakdown of the costs for this option is provided in Table 3.

Atkins Options Assessment | Version 3.0 | May 2012 8

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

Table 3. Construction Cost Breakdown for Option 4 Works Cost All works associated with excavation and tree removal £100,000 Vegetation clearance to provide a clean channel and short grass £20,000 approx 30m width Works to determine exact locations of excavation. £20,000 Land Purchase/compensation £20,000 Total £160,000 Potential additional excavation costs £45,000 Total with additional excavation £205,000

Currently, maintenance of this reach of Willow Brook is restricted due to limited access to the river. To ensure that the mitigation proposed remains effective for the lifetime of the development the channel and floodplain will need to be well maintained. An upper estimate of the cost for maintenance for this reach is estimated to be in the order of £5,000 per year. Over an assumed lifetime of 60 years, this equates to a total maintenance cost of £127,000 (as a discounted present value). The WCS estimated maintenance costs at £7,000 per km – the reach where the mitigation is being proposed is approximately 0.5km. Using these values the discounted present value maintenance cost would be approximately £89,000.

The responsibility for funding and carrying out the maintenance of the channel is currently not confirmed. The WCS recommended “that a maintenance company was set up which pools the contributions from various sources”. Given the uncertainty involved in how maintenance will be carried out, a variation to the preferred option is proposed which will over size the mitigation to incorporate a degree of redundancy that accounts for a reduction in performance over the years, if only the minimum level of maintenance is carried out (i.e. continuing with the current practice). A further allowance of approximately £50,000 should be included to increase the additional flood storage volume by a further 30% to include this redundancy. Even the minimum level of maintenance will incur a cost, therefore adding a further allowance of £40,000 over the assumed lifetime of the development.

Whether the reach and mitigation measures are fully maintained to the required standard, or if the mitigation is oversized to include some redundancy, the costs associated with either are in the order of £100,000. Only during the detailed design stage will it become apparent what the optimum combination will be for storage volume and maintenance regime. For this reason it is recommended that the overall costs for the preferred option are taken forward as £305,000.

3.5. Potential for Betterment The proposed modified floodplain and channel profiles should be designed where practicable to include environmental benefit. Upstream of the Corby Culvert, works to increase floodplain capacity can be designed to include measures to reconnect the river with its floodplain, for example, re-profiling to create a two stage channel and silt traps could be incorporated to provide improved drainage and targeted ecological benefit. Downstream of the culvert, the works will realign the river to a more naturally sinuous channel. This newly aligned channel will increase flow diversity and manage flood risk by improving conveyance at times of high flow.

Consideration of these aspects at the design stage will provide a contribution towards meeting the objectives of the Water Framework Directive to prevent deterioration of water quality, ecology and natural channel morphology through the impacts of new development in growth areas. Further work is being planned under the Water Framework Directive programme to improve the Willow Brook North tributary. The combined measures will help the Willow Brook and downstream River Nene meet the new target standards.

Maintenance regimes may have a significant influence on the ecological status of this stretch of river, meaning that landowners and beneficiaries should be encouraged to input to detailed design, landscaping and its sustainable maintenance

Atkins Options Assessment | Version 3.0 | May 2012 9

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

3.6. Implementation of Preferred Option Only a limited amount of development can take place before mitigation is required to compensate for the increase in the outfall discharge associated with the developments as they become online. The majority of the increase in peak water levels (unmitigated) occurs by 2020 based on the modelling assessment carried out for this report; therefore it can be considered that the mitigation works would need to be implemented as early as possible to ensure that there is no unacceptable impact on flood levels.

Contributions to fund the works for the preferred option will be required from developments in accordance with the three tests for s106 contributions or through CIL contributions if adopted by Corby Borough Council. Based on the current housing trajectory for Corby, there are 1551 dwellings that are expected to receive planning approval by 2014. If the works are to be funded wholly through S106 contributions prior to the CIL being adopted the costs will need to be apportioned accordingly resulting in a per dwelling contribution of approximately £200.

Atkins Options Assessment | Version 3.0 | May 2012 10

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

4. Conclusions and Recommendations

4.1. Conclusions It can be concluded from this assessment that:

1. The Corby Culvert acts as a constriction of flow during flood events and as a result flood levels will increase upstream of the culvert by 100mm in the 10% AEP event and by 30mm in the 1% AEP event following Phase 2 development and the associated increase in STW discharge. Flood levels will also increase downstream of the Corby Culvert to Deenethorpe;

2. Five options have been assessed and costed to mitigate the increased risk following additional discharge from the STW due to future development up to 2031. Two of which would cost more than £2million. The other options individually cost less than £0.5million;

3. The preferred option which requires the least financial investment is Option 4 which involves increasing flood storage at the location of the STW outfall and just downstream of the Corby Culvert. This option also involves annual channel maintenance and vegetation clearance;

4. The preferred option, would prevent an increase in flood level (and would provide slight betterment at some locations) as a result of Phase 2 development during the 1% AEP event. Analysis shows that increasing the flood storage at this location will mitigate the increase levels and that during the 10% AEP event the preferred option would see a reduction of approximately 50mm at the location of the STW outfall. Therefore with further mitigation it may be possible to fully mitigate the increase at the 10% AEP event; and

5. Works required as part of Option 4 to identify exact areas of excavation may determine that additional excavation is possible to prevent an increase in flood risk during the 10% AEP event following Phase 2 development.

4.2. Recommendations As a result of this assessment it has been determined that Option 4 is the preferred option for works to mitigate the increases in flood levels following increased discharge from the STW due to Phase 2 development (development up to 2031). This is under the assumption that a 50mm increase at the location of the STW is acceptable during the 10% AEP event.

It is recommended that as part of Option 4, when exact locations for excavation are identified, that the potential for additional excavation to prevent increases in flood levels at the STW outfall during the 10% AEP event is determined. If this proves to be possible it is recommended that further excavation is carried out.

It is also recommended that consultation is held with Anglian Water to determine improved access arrangements required for the necessary ongoing maintenance requirements for Option 4.

The assessment indicates that the potential cost for Option 4 is £305,000. This includes a contribution to annual maintenance which will be required.

If this potential contribution is provided by the developer then there would not be further funding requirements and hence additional funding sources would not be required.

To ensure that the works provides adequate flood risk mitigation over the life time of the development the scheme would either have to involve over engineering solutions or long term maintenance. If over engineering is determined not to be possible during the design phase, it is recommended that early consultation is held with the Environment Agency, Anglian Water and Corby Borough Council to agree responsibilities.

There is potential that as part of the mitigation works to ensure flood risk does not increase that environmental betterment could be provided. It is therefore recommended that opportunities for betterment within the scope of the proposed works are explored as part of the design phase.

Atkins Options Assessment | Version 3.0 | May 2012 11

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

Only a limited amount of development could go ahead before flood risk will rise to an unacceptable level, therefore it is recommended that mitigation measures are carried out as soon as possible.

Atkins Options Assessment | Version 3.0 | May 2012 12

Appendices

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

Appendix A. Hydraulic Model Report

Atkins Options Assessment | Version 3.0 | May 2012 14

Corby Water Cycle Study Update Willow Brook Modelling Report Corby Borough Council

May 2012

Corby Water Cycle Study Update Willow Brook Modelling Report

Notice

This document and its contents have been prepared and are intended solely for Corby Borough Council’s information and use in relation to the Corby Water Cycle Study Update

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

This document has 21 pages including the cover.

Document history

Job number: 5040250 Document ref: Willow Brook Modelling Report Revision Purpose description Originated Checked Reviewed Authorised Date Rev 1.0 Client/EA review LT LF TR TR Dec 2011 Rev 2.0 Update following LT JL TR TR Feb 2012 Client/EA Review Rev 3.0 Final for Issue LT JL TR TR March 2012 Rev 4.0 Issue for Options Report LT JL TR TR May 2012

Client signoff

Client Corby Borough Council

Project Corby Water Cycle Study Update

Document title Willow Brook Modelling Report

Job no. 5040250

Copy no. 1

Document Willow Brook Modelling Report reference

Corby Water Cycle Study Update Willow Brook Modelling Report

Table of contents

Chapter Pages Executive summary iv 1. Introduction 1 2. Methodology 2 2.1. Flood Storage Reservoir 2 2.2. Inclusion of Sewage Treatment Works Outfall 2 2.3. Proposed Development in Corby 3 3. Model Results 4 3.1. Overview 4 3.2. Flood Storage Reservoir Update 4 3.3. Inclusion of Sewage Treatment Works Outfall 5 3.4. Proposed Development within Corby 6 3.5. Additional Model Runs 11 4. Conclusions and Recommendations 12 4.1. Conclusions 12 4.2. Recommendations 12 Appendix A. Consultation 13 Appendix B. Environment Agency Licence Agreement 14

Tables Table 1. Peak water level changes between the original model and FSR updates 5 Table 2. Peak water level changes as a result of the current day STW outflow 6 Table 3. Peak water level changes between current and Phase 1 scenarios 7 Table 4. Peak water level changes between current and Phase 2 scenarios 7 Table 5. Peak Water Level Changes for Phase 2 Development 11

Figures Figure 1. Location Map 1 Figure 2. Increase in discharge from the STW during the 1% AEP event 3 Figure 3. Key locations of water level changes 4 Figure 4. Locations of water level increases of more than 20mm for Phase 2 development during the 10% AEP event 8 Figure 5. Location of water level increase of more than 20mm for the more extreme events 9 Figure 6. Increased flow over the FSR embankment during the 10% AEP event 10 Figure 7. Increased flow over the FSR embankment during the 1% AEP event 11

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 ii

Corby Water Cycle Study Update Willow Brook Modelling Report

Glossary

Term Meaning/Definition

AEP Annual Exceedance Probability

FSR Flood Storage Reservoir

STW Sewage Treatment Works

mAOD Metres above Ordnance Datum

Event Severity

The severities of the events discussed in this report are defined mainly as Annual Exceedance Probabilities (AEP). The AEP is the probability that there will be an event exceeding a particular severity in any one year.

Annual Exceedance Probability Probability (AEP) (chance in any given year)

50% 1 in 2

20% 1 in 5

10% 1 in 10

5% 1 in 20

2% 1 in 50

1.33% 1 in 75

1% 1 in 100

0.5% 1 in 200

0.1% 1 in 1000

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 iii

Corby Water Cycle Study Update Willow Brook Modelling Report

Executive summary

Atkins was commissioned to update the existing Corby Water Cycle Study (WCS) in specific relation to proposed development up to 2031 and the impacts on Willow Brook. As part of this update it was necessary to complete a modelling study for the implications on flood risk as a result of proposed future development within Corby and the associated increases in discharge from the Corby Sewage Treatment Works (STW). This is of specific importance in the area upstream of the Corby Culvert which is a known constriction of flow and requires maintenance. A detailed hydraulic model was made available for this assessment by the Environment Agency and hydrographs for current and future outfall scenarios from the STW were made available by Anglian Water. The overall reason for the modelling assessment was for comparative purposes between the current and future discharge from the STW, not to update flood mapping or to redefine flood risk along the Willow Brook.

The original hydraulic model for the Willow Brook needed altering which involved updating the model node representing the Weldon Flood Storage Reservoir (FSR) embankment based on recent improvement works and the incorporation of a lateral inflow point to the model to represent discharge from the STW. The impacts of these updates were reported to highlight any changes from the existing flood extents.

The update of the FSR embankment involved raising the spillway and lowering the additional overtoppable embankment. To determine the impact of the change in embankment heights, the updated model was run for the 4%, 1% and 0.1% AEP events. Peak water levels for the 4% AEP and 1% AEP show increased levels within the FSR of 76mm and 29mm respectively. Elsewhere the peak water level changes during these events are minimal. These changes are unlikely to cause significant changes to the flood extents although this would need to be confirmed with the Environment Agency following a model review by the Environment Agency. During the 0.1% AEP event, water levels are reduced within the FSR by up to 220mm and this may potentially refine the flood extent at this location. Downstream of the FSR, during this event the maximum increase in peak water level is 28mm and it is assumed that this will have a minimal impact on flood extents. The 50% AEP event was also modelled for comparative purposes. This model change had no impact on the 50% AEP flood levels within the model.

The addition of the STW outfall into Willow Brook within the model has the potential to double count flows within the Willow Brook catchment because the original model represented the catchment runoff but did not include a specific inflow point at the STW. Although this is a conservative approach it is deemed suitable by the Environment Agency as it would not underestimate flood risk within the catchment. Utilising current outfall rates, the result of this addition is an increase in peak water levels at the location of the outfall and upstream of the Corby Culvert by up to 237mm during the 1% AEP event which would cause localised increase in the flood extent by approximately 4m. Elsewhere the peak water level increases are smaller and likely to cause changes in the flood extent by less than 1m. This updated model run formed the current (baseline) scenario.

The focus of this modelling was to assess the impact of the increased STW outfall flows on peak water levels and the flood extents as a result of proposed development within Corby over two phases. Phase 1 and 2 represent future development and associated increased outfall rates from the Corby STW up to years 2021 and 2031 respectively. Anglian Water provided their estimated outfall rates for various annual exceedance events for both phases of development and these were used directly within the model. The hydrographs for these events indicated minimal increase in peak flow rates, although the overall volume increased.

The increased outfall rates cause the greatest increase in peak levels adjacent to the outfall and upstream of the Corby Culvert. As a result of the Phase 1 development (up to 2021) the maximum increase in peak water levels within the model is 91mm during the 10% AEP. During more extreme events such as the 1% AEP event the maximum increase in peak water level within the model up to Phase 1 is 31mm and 8mm during the 1% AEP event with an allowance for climate change.

The peak water levels do not rise much more following additional development between 2021 and 2031. During the 10% AEP event peak water levels increase by 98mm compared to the baseline, an increase of 7mm from Phase 1. The Phase 2 results for the 1% AEP event show no increase in peak flood levels between 2021 and 2031 at the location of the STW. The model showed instabilities during the 1% AEP event with an allowance for climate change for Phase 2, however following a review of the Phase 1 results, it is anticipated that proposed development up to 2031 will have an impact of less than +31mm throughout the Willow Brook during the 1% AEP event taking climate change into account. This conclusion has been drawn

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 iv

Corby Water Cycle Study Update Willow Brook Modelling Report because the water level increases were greater during the 1% AEP event without an allowance for climate change (max +31mm) in comparison to with an allowance for climate change (max +13mm) for Phase 1 and it is assumed that this trend is to continue for Phase 2 development.

As a result of the concerns expressed by the Environment Agency in relation to the potential impact of double counting, additional modelling was carried out. This involved only using the additional discharge as a result of future development (up to 2031) as the point inflow at the STW. During the 10% AEP event, the result was a 17mm difference in peak water levels at the location of the Corby Culvert. This is increased downstream of the FSR, although there would no risk to properties. During the 1% AEP event, the impact was 24mm at the location of the STW outfall, although elsewhere the maximum change was 7mm.

It can be concluded from this modelling assessment that the potential change in flood risk will be minimal as a result of increased discharge from the STW, following development up to 2031 in Corby. Further discussions with Corby Borough Council and the Environment Agency will determine whether mitigation is required.

However as shown by modelling the 1% AEP event, the incorporation of the current STW discharge into the model does change peak flood levels fairly significantly in the vicinity of the outfall location of the STW and immediately upstream of the Corby Culvert. Consultation is required with the Environment Agency and Corby Borough Council to determine whether this change is considered significant, or whether additional analysis will be required to improve the estimates of the rural and urban runoff. Elsewhere the model indicates minimal increases in peak water levels therefore this is an issue only localised to the short reach near the STW outfall.

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 v

Corby Water Cycle Study Update Willow Brook Modelling Report

1. Introduction

Atkins has been commissioned to update the existing Corby Water Cycle Study (WCS) in specific relation to proposed development up to 2031 and the impacts on Willow Brook. As part of this update it was necessary to complete this modelling exercise to determine the potential flood risk implications of increased discharge from the Corby Sewage Treatment Works (STW) as a result future development within Corby. The findings of the study would inform requirements for improvement works that may be required along Willow Brook as a result of this future development. The proposed development within Corby will result in increased effluent discharge from the Corby STW which has the potential to increase peak flood levels and hence flood risk along Willow Brook. Prior to the completion of the modelling assessment it was anticipated that the culvert located just downstream of the STW (the Corby Culvert) had the potential to constrict flows in the Willow Brook and hence cause flooding in the upstream areas which would be increased following the inclusion of the STW outfall within the model.

This assessment will provide an update to the current Corby Water Cycle Study (WCS) and determine potential requirements for mitigation to offset any increase in flood risk along Willow Brook as a result of additional discharge at the STW. The hydraulic model of the Willow Brook completed as part of the WCS, has been provided by the Environment Agency, although a number of updates were required as outlined within Section 2. This included the recent change to the embankment crest levels of the Weldon Flood Storage Reservoir (FSR) and the outfall from the Corby STW.

Figure 1 below shows the location of the areas of interest within the model.

© Crown Copyright. All rights reserved. Corby Borough Council, 100018791, 2012. Figure 1. Location Map

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 1

Corby Water Cycle Study Update Willow Brook Modelling Report

2. Methodology

The Environment Agency provided their current model of the Willow Brook Catchment for this assessment which was created within ISIS. Detail of the model structure and other related information can be found within the Nene Model report (Environment Agency, 2009). The hydraulic model required two updates, as a result of the improvement works to Weldon Flood Storage Reservoir (FSR) and for the inclusion of discharge from the STW. These two updates were required to provide a baseline of the existing scenario against which future development scenarios were compared. These two updates had the potential to impact on current flood extents and therefore have been outlined in detail within the following two sections.

The original model was run for a number of storm durations, specifically, 7, 11, 19 and 25 hours. The focus of this assessment is at the location of the STW outfall and the Corby culvert. On inspection of the model results provided by the Environment Agency it was determined that the 7 hour storm duration produced the greatest peak water levels at this location. These levels were significantly greater than the 19 and 25 hour storm durations and 20mm greater than the 11 hour duration. The peak water level for the 7 hour storm duration also occurs at a more similar time as the peak outfall from the STW, in comparison to any of the other storm durations. The 11 hour storm duration does provide slightly higher peak levels at the location of the FSR, but this is only 14mm during the 1% AEP event. As a result it was determined that the 7 hour rainfall duration was the most appropriate for this modelling assessment (it would produce the most conservative results at the location of the STW and Corby Culvert) and hence has been used for all model runs. It is likely that running the 11 hour storm duration would have a smaller impact on peak levels at the location of the FSR and downstream, and would still not impact on flood risk to properties.

2.1. Flood Storage Reservoir In autumn 2009 the Weldon FSR spillway was altered by the Environment Agency to increase the capacity of the FSR. Prior to the improvement works, under normal conditions the FSR remains dry and significant storage only commences during flood events above the 20% AEP. During the 5% AEP event the entire flood waters would have been impounded within the FSR and spill would occur during more extreme flood events.

In total the FSR embankment is approximately 81m in length, with a spillway located on top of the culverted Willow Brook and an additional overtoppable embankment. The 30.65m spillway (owing for side slopes, 27.65m at the crest) was previously at a level of 85.88mAOD, this was raised to 86.15mAOD as a result of the improvement works. The 50.35m additional overtoppable embankment was lowered from 86.96 to 86.30mAOD.

The FSR embankment is represented at model node WBS1858SPu and hence this node was altered based on the level changes outlined above. No other changes were made to the model for this part of the assessment.

The existing Environment Agency mapping utilised the original FSR embankment dimensions (i.e. pre 2009 improvements) within the model and therefore any changes to the model and as such peak flood levels has the potential to alter flood extents. As a result the peak flood levels for the 1% AEP and 0.1% AEP events have been compared pre and post model update with the FSR improvements to determine any potential impact on flood extents. For comparative purposes the 4% AEP event and the 50% AEP have also been assessed.

2.2. Inclusion of Sewage Treatment Works Outfall The original model provided by the Environment Agency did not explicitly include the outfall from the STW and hence the model required the addition of a point inflow node to represent the STW outfall. Outfall hydrographs were provided by Anglian Water and added to the model at model node WBS3054 and as shown in Figure 1.

The original model was calibrated including runoff from the whole catchment and as a result there were some concerns that double counting of surface water flow would occur if the current outfall from the STW was included as a point inflow to the Willow Brook without reducing the catchment inflows already represented in the model. As a result the baseline scenario of the updated model (i.e. current outfall from the site) is likely to overestimate flood extents. However in agreement with the Environment Agency (November

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 2

Corby Water Cycle Study Update Willow Brook Modelling Report

2011) this potential double counting was accepted for the purposes of this comparative exercise and it is recognised that the modelling results may be conservative.

To determine the potential impact of adding the STW outfall into the model without altering other model inflows, the updated model with the FSR amendments and with the current STW outfall were compared for the 1% AEP event. The Anglian Water data during the 0.1% AEP event was not available and hence impact of including the STW outfall on the 0.1% AEP flood extent cannot be determined.

Anglian Water provided discharge hydrographs for a number of storm durations, although the use of a 16 hour storm duration resulted in the greatest discharge rates and volumes and hence has been used for this assessment as a conservative approach. The peak discharge rates for each of the design storms were within the range of 1.4 to 1.6m3/s and this remains approximately constant for Phase 1 and 2 of development as shown in Figure 2 (increases of approximately 0.1m3/s as a result of future development). The most significant impact of future development is the increase the overall volume discharging from the STW.

The time to peak for the flow rates from the STW is just under nine hours and the flood flow hydrograph within the original model indicates a peak flow just after nine hours. Due to the fairly similar peak times the STW discharge hydrographs were added directly to the model.

Figure 2. Increase in discharge from the STW during the 1% AEP event

2.3. Proposed Development in Corby The focus of this modelling was to determine the impact of the proposed development within Corby and hence the increased outfall from the STW on flood levels along Willow Brook. Anglian Water provided outfall hydrographs for a range of return periods for the current scenario and Phases 1 and 2 of development, representing the increased discharge due to development up to 2021 and 2031 respectively.

The model was run for the baseline (current), Phase 1 and Phase 2 scenarios for a range of design events, namely the 10% AEP, 4% AEP, 2% AEP, 1.3% AEP, 1% AEP and 1% AEP with an allowance for climate change events. The climate change allowance for the 1% AEP event was an increase of 20% on natural flow within the watercourse. The results for the other events do not include an increase in natural flow as a result of climate change, because modelled flows with an allowance for climate change were not available. However, increases in the natural flow within the watercourse as a result of climate change will result in discharge from the STW being proportionally smaller than presented within this assessment. As a result this assessment is considered to be conservative.

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 3

Corby Water Cycle Study Update Willow Brook Modelling Report

3. Model Results

3.1. Overview The alterations to the model caused peak water level changes along the Willow Brook. The peak water level changes have been outlined in the following sections based on the two required updates and the future development scenarios. The key locations where peak water level changes were observed are shown on Figure 3.

© Crown Copyright. All rights reserved. Corby Borough Council, 100018791, 2012. Figure 3. Key locations of water level changes

3.2. Flood Storage Reservoir Update The update to node WBS1858SPu to account for the revised FSR embankment crest levels caused no change in peak water levels during the 50% AEP event because no over spilling occurs during this event. During the 4% AEP event a maximum peak water level increase in the FSR of 76mm was observed because the increased spillway height resulted in the retention of additional water upstream of the FSR embankment. In addition the model indicated that there was an increase in water level of 15mm immediately downstream of the FSR where the interaction of the different flow routes (via the spill, culverts and sluice) causes the localised increase. Further downstream there is a reduction in water level of 6mm in the area surrounding Deenethorpe.

The impact of increasing the spillway height had a similar effect during the 1% AEP event as water levels within the FSR were elevated slightly, by a maximum of 29mm. There are also peak water level increases in downstream areas with a maximum change of 15mm. As a result the flood extent for the 1% AEP event will increase as a result of the updates to the FSR. The increase in levels is relatively small, but to confirm if these increases would significantly impact flood extents, a review of the cross section data in the model was carried out and it showed that the increase in the 1% AEP flood extent is insignificant (<1m). However this will have to be confirmed following consultation with the Environment Agency at a later stage.

The results for the 0.1% AEP event indicate a reduced peak water level within the FSR by up to 220mm. However along most of the downstream reach until the confluence near East Crescent, peak water levels are increased by as much as 20mm and around Deenethorpe, water levels are increase by a maximum of

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 4

Corby Water Cycle Study Update Willow Brook Modelling Report

28mm. As a result of the FSR embankment improvements the 0.1% flood extent could be refined slightly upstream of the FSR embankment, although the width by which it would be reduced is not known at this stage. The slight increases in downstream reaches are fairly small, and following a review of the cross section data, unlikely to impact significant on the current flood extent.

In conclusion the result of altering the levels of the FSR embankment had the most significant changes within the FSR, with minor changes along the reach downstream of the FSR and in the area surrounding Deenethorpe. A summary of the maximum water level changes for these three areas is provided in Table 1.

The update to the model required as result of the FSR improvements has been included within the baseline model as outlined in Section 3.3.

Table 1. Peak water level changes between the original model and FSR updates

Location 50% AEP 4% AEP 1% AEP 0.1% AEP Upstream of FSR 0mm +76mm +29mm -220mm Chainage - WBS1867 WBS1999 WBS1867 Immediately 0mm +15mm +15mm +20mm downstream of FSR Chainage - WBS1545 WBS1565 WBS1079 Deenethorpe 0mm -6mm 0mm +28mm Chainage - WI21607 - WI21607

3.3. Inclusion of Sewage Treatment Works Outfall The result of including an additional discharge point within the model to represent the outfall from the sewage treatment works resulted in increased peak water levels at several locations within the model. Therefore the proposed baseline scenario will potentially produce different flood extents in comparison to those provided by the Environment Agency. The impact of adding the discharge from the STW into the model has been reviewed for the 1% AEP event.

At the location of the outfall, peak water levels in Willow Brook were increased by a maximum of 237mm in comparison to the updated baseline model. This is due to the capacity restrictions of the Corby Culvert. During the 1% AEP event, prior to inclusion of the STW outfall, the Corby Culvert does not have sufficient capacity and caused backing up along Willow Brook and flooding in adjacent areas. Therefore as a result of including discharge from the STW there is additional water within the system causing higher water levels upstream of the culvert potentially increasing flood extents in this area. This change will cause a localised increase in the 1% AEP extent by an approximate 4m in width (2m either side of Willow Brook).

Within the reach 300m upstream of the Corby Culvert, the increase in peak water levels range from 208 to 237mm. Along this reach it is likely that the 1% AEP flood extent will widen, however the current cross section data is insufficient to determine the resultant increase in width. Further upstream peak water level increases are 90mm and less, and the channel cross sections imply that the increase in water levels will cause a minimal impact on the 1% AEP flood extent.

Immediately downstream of the Corby Culvert the water levels are increased by a maximum of 67mm, however this is likely to cause a minimal increase in the 1% AEP flood extent (<1m). Further downstream, between the FSR and Deenethorpe, the peak water level increase is between 16mm and 28mm, although this is insufficient to cause a significant increase in flood extent.

The model indicates that there are no other significant changes to peak flood levels during the 1% AEP event as a result of the inclusion of discharge from the STW. A summary of the peak water level changes for various locations is shown in Table 2.

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 5

Corby Water Cycle Study Update Willow Brook Modelling Report

Table 2. Peak water level changes as a result of the current day STW outflow

Location of Change and Chainage Peak Water Level Approximate Change Grid Reference Change in 1% AEP extent Location of the STW outfall WBS3314 +237mm 4m 490471, 288819 Upstream of the Corby WBS3018 +237mm 4m Culvert inlet 490764, 288843 Downstream of the Corby WBS2791 +67mm <1m Culvert 490973, 288866 Within the FSR WBS1858 +16mm <1m 491794, 289279 Upstream of constrictions in WI21607 +28mm <1m Deenethorpe 495544, 292133

3.4. Proposed Development within Corby Peak water level increases were observed in the model as a result of both Phase 1 and Phase 2 development; however the difference between the two phases was minimal. The model ran successfully for all events for Phase 1, although for Phase 2 the 1% AEP event with an allowance for climate change was unstable and therefore did not reach the peak. The model as provided for this assessment had been calibrated and therefore making further alterations was not desirable. Given the small differences in peak water level between Phase 1 and 2 for all other events, this omission was deemed acceptable.

The modelled increases in peak levels as a result of increased discharge from the STW during Phase 1 development are shown in Table 3. From this table it can be seen that as a result of the Phase 1 development, at the location of the STW outfall, levels are raised by 91mm for the 10% AEP event. During the 4% AEP this increase is 63mm and at higher annual exceedance events, specifically the 1% and 1% AEP with an allowance for climate change, the water level increase is smaller. As expected the peak levels are increased by a greater amount during the more frequent flood events, because the increased outfall from the STW (as a result of future development) would be a greater percentage of the natural flow within the channel.

Further downstream, along the reach between the FSR embankment and the confluence near East Crescent, as shown on Figure 3, peak water levels are raised through all modelled events. For Phase 1, during the 10% AEP event the peak water level increase along this reach is between 10mm and 65mm. During more extreme events such as the 1% AEP event, the increase along this reach is smaller, between 7mm and 13mm, with even smaller increases when climate change is taken into account.

The model shows that the other location which experiences changes in flood levels as a result of the point inflow from the STW is around Deenethorpe. At this location water levels are increased by 28mm during the 10% AEP event as a result of Phase 1 development. The more extreme events show smaller peak water level increases, within the range of 11 to 13mm.

It can be seen from the results that increasing discharge from the STW as a result of Phase 1 development within Corby causes the maximum change in peak water level for the 10% AEP event. During more extreme events, the greatest increase in peak water levels as shown by the model is 63mm.

The additional discharge for Phase 2 development causes further increases in peak water levels, although the change is minimal. The increases in peak water levels from the baseline scenario are shown in Table 4. At the location of the STW outfall during the 10% AEP event the increase in peak water level as a result of Phase 2 development is 98mm, which is only 7mm greater than the increased peak water level for Phase 1. During more extreme events, the increase in peak water levels for Phase 2 development is within the range of 0-3mm from Phase 1.

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 6

Corby Water Cycle Study Update Willow Brook Modelling Report

Elsewhere within the model this trend continues and there are no locations during any events where the peak water level increases more than 11mm from Phase 1 to Phase 2 development.

It can therefore be seen that the model implies that the increase discharge from the STW between Phases 1 and 2 (i.e. 2021 and 2031) will have a minimal impact on flood risk during the annual exceedance events modelled.

Following a review of the model results, the increased outfall from the STW does not cause out of bank flooding along any reach which does not flood during the current day scenario. There are no other locations at which water levels are significantly impacted as a result of additional outfall from the STW. The results indicate that the greatest change in peak flood levels as a result of Phase 1 and 2 developments is at the location of the STW, as a result of insufficient capacity of the Corby Culvert located downstream of the STW. A summary of the key locations and associated peak flood level changes for Phase 1 and 2 are shown in Tables 3 and 4, below. At various locations, slightly higher peak water levels occur at adjacent nodes and these have been shown in Tables 3 and 4 where applicable.

Table 3. Peak water level changes between current and Phase 1 scenarios

Location Chainage 10% AEP 4% AEP 2% AEP 1.3%AEP 1% AEP 1% AEP +CC Upstream of WBS3374 55mm 63mm 31mm 21mm 24mm 4m STW inflow STW inflow WBS3054 91mm 52mm 48mm 47mm 31mm 8mm (at adjacent node WBS3018) Within the FSR WBS1858 10mm 5mm 4mm 3mm 7mm 5mm Downstream of WBS1630 60mm 16mm 14mm 13mm (at 13mm (at 9mm the FSR adjacent adjacent node node WBS1628) WBS1628) Upstream of WI21647 28mm 12mm 12mm 13mm 11mm 13mm Deenethorpe constrictions

Table 4. Peak water level changes between current and Phase 2 scenarios

Location Chainage 10% AEP 4% AEP 2% AEP 1.3%AEP 1% AEP Upstream of WBS3374 60mm 64mm 30mm 21mm 24mm STW inflow STW inflow WBS3054 98mm 51mm 45mm (at 47mm 31mm adjacent node WBS3018) Within the FSR WBS1858 12mm 5mm 4mm 3mm 7mm Downstream of WBS1630 71mm (at 18mm 17mm (at 15mm (at 14mm the FSR adjacent node adjacent node adjacent node WBS1630) WBS1630) WBS1795) Upstream of WI21647 35mm 15mm 14mm 16mm 13mm Deenethorpe constrictions

Figures 4 and 5 show the location of peak water level increases of more than 20mm for Phase 1 and 2. There are three separate reaches which experience such increases in peak water levels for the 10% AEP event as shown on Figure 4. During more extreme events, the only reach which would experience increased water levels of more than 20mm is in the vicinity of the STW outfall as shown on Figure 5. Mitigation measures are normally required as a result in flood risk changes during the 1% AEP event and as a result

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 7

Corby Water Cycle Study Update Willow Brook Modelling Report this assessment indicates that the only reach which would potentially require mitigation is an approximate 300m reach in the vicinity of the STW outfall as shown on Figure 5.

Therefore it is recommended that potential mitigation measures are identified for the reach as shown, below on Figure 5. The feasibility of the potential measures should be determined following consultation with Corby Borough Council and the Environment Agency.

© Crown Copyright. All rights reserved. Corby Borough Council, 100018791, 2012. Figure 4. Locations of water level increases of more than 20mm for Phase 2 development during the 10% AEP event

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 8

Corby Water Cycle Study Update Willow Brook Modelling Report

© Crown Copyright. All rights reserved. Corby Borough Council, 100018791, 2012. Figure 5. Location of water level increase of more than 20mm for the more extreme events

The duration of inundation has also been determined for this assessment. At the location of the STW outfall (where there is the greatest increase in peak level), during the 10% AEP event the peak water level overtops the bank for approximately 20 minutes longer as a result of Phase 2 development which increases over topping time to almost 2.5 hours. However for the 1% AEP event, this increase in overtopping duration is less than 10 minutes (total overtopping duration is approximately eight hours), which is considered insignificant.

Downstream of the FSR at node WBS1630, the duration of bank overtopping increases by approximately 15 minutes as a result of Phase 2 development during the 10% AEP event (total overtopping duration approximately two hours), and approximately 10 minutes in the 1% AEP event (total overtopping duration is just over seven hours).

At WI21647, located in Deenethorpe, the increase in flood duration as a result of Phase 2 development is approximately 20 minutes during the 10% AEP event (total overtopping duration eight hours), and approximately 10 minutes during the 1% AEP event (total overtopping duration 12 hours).

Even though downstream of the FSR the peak water level would increase by between 71mm (10% AEP) and 14mm (1% AEP) as a result of Phase 2 development, the results indicated that no inundation of properties under the Phase 2 scenario for the 1% AEP event would occur and hence flood risk will not be significantly increased in this area as result of increased discharge. Further downstream at WBS790, using the available information it is not possible to determine whether properties will be inundated during the 1% AEP event at this stage. The difference in peak water level during this event at this location is approximately 11mm and this increase in levels would need to be addressed through appropriate mitigation measures.

In addition to increased peak water levels, the increases in flow rates have also been determined. Figures 6 and 7 show the increase in flow rate over the FSR embankment as a result of increased discharge from the STW. It can be seen that during the 10% AEP event the increase in flow is approximately 1m3/s over approximately 1 hour, after which the increase in flow rate is approximately 0.5m3/s for 30 minutes. For the remaining three hours during which the embankment is over topped, the increase in flow rate is less than 0.5m3/s. During the 1% AEP event the increase in flow rate over the embankment is less, as shown on Figure 7, with a maximum increase typically less than 0.5m3/s (<5%) during four of the nine hours during

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 9

Corby Water Cycle Study Update Willow Brook Modelling Report which the FSR embankment is overtopped. This increase in flow rate is not considered significant, although this would require confirmation from the Environment Agency.

Figure 6. Increased flow over the FSR embankment during the 10% AEP event

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 10

Corby Water Cycle Study Update Willow Brook Modelling Report

Figure 7. Increased flow over the FSR embankment during the 1% AEP event

3.5. Additional Model Runs Following correspondence with the Environment Agency (see Appendix A), the potential double counting as outlined in Section 2.2 was seen as a concern. As a result it was deemed appropriate that an additional model run was carried out, for which only the additional outfall from the STW as a result of Phase 2 development was included as inflow at the location of the STW. This scenario was run for the 10% and 1% AEP events. The results, and a comparison with the results outline in Section 3.4, are provided below, in Table 5.

Table 5. Peak Water Level Changes for Phase 2 Development

Additional discharge as a result Full STW outfall as shown in Location Chainage of Phase 2 development Section 3.4 10% AEP 1% AEP 10% AEP 1% AEP Upstream of WBS3374 55mm 17mm 60mm 24mm STW inflow STW inflow WBS3054 115mm 55mm 98mm 31mm Within the FSR WBS1858 23mm 4mm 12mm 7mm Downstream of WBS1630 134mm 15mm 71mm 14mm the FSR Upstream of WI21647 24mm 16mm 35mm 13mm Deenethorpe constrictions

The results in Table 5 indicate that regardless of whether the full outfall hydrograph from the STW or just the additional outfall as a result of Phase 2 development is utilised within the model, the peak water level increase just upstream of the Corby culvert would be between 98 and 115mm and hence within a 17mm range during the 10% AEP event. The greatest range of peak flow during the 10% AEP event is 63mm and is located downstream of the FSR, however these peak flood levels will not impact on properties and thus

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 11

Corby Water Cycle Study Update Willow Brook Modelling Report there would not be a change in flood risk to existing development. Within the FSR and elsewhere this range is much less, approximately 10mm.

During the 1% AEP, whether the full outfall hydrograph from the STW or just the additional outfall as a result of Phase 2 development is utilised within the model, the peak water level increase is fairly consistent between +/- 1 to 7mm at most locations. The greatest range in peak water level is at the location of the STW which is 24mm.

As expected the differences in peak water levels are greater during the more frequent events. This is because the outfall from the STW forms a greater percentage of the flows within the watercourse during the lower order events. The results from this additional assessment show the range of differences when using either the full outfall hydrograph from the STW or just the additional discharge as a result of future development. Therefore it was not deemed necessary to re-run the model for all annual probabilities. 4. Conclusions and Recommendations

4.1. Conclusions There are a number of conclusions which can be made from this assessment, these are as follows:

1. The impact on the flood extents as a result of updating the model with the revised FSR embankment heights is likely to be minimal, particularly for the 0.1% AEP flood extent; 2. The inclusion of the STW outfall into the model results in a widening of the 1% AEP flood extent by approximately 4m upstream of the Corby Culvert and in the vicinity of the STW. Elsewhere the result is flood extent widening of less than 1m; 3. Increased STW outfall for Phases 1 and 2 does not cause any out of bank flooding along reaches which do not flood during the current day scenario; 4. The greatest change in peak water level as a result of additional outfall from the STW during Phases 1 and 2 of development within Corby is 91mm and 98mm respectively. These changes in levels occur during the 10% AEP event at the location of the STW outfall and are potentially exacerbated by the Corby Culvert restriction just downstream of the STW; 5. Elsewhere along Willow Brook the result of increased outfall from the STW has a minimal impact on flood levels for the 1% AEP and 1% AEP with an allowance for climate change events, with peak water level increases of no more than 31mm within open channels; and 6. Using the approaches outlined in this assessment to represent outfall from the STW, Phase 2 development would cause a maximum increase in peak flood levels at the location of the STW of between 98-115mm (during the 10% AEP) and 31-55mm (during the 1% AEP) event.

4.2. Recommendations There are a number of recommendations that can be made from this assessment, these are as follows:

1. Consultation with the Environment Agency is carried out to confirm that the update of the FSR embankment crest levels and the incorporation of the STW outfall would cause a minimal change to their current flood extents; and 2. The assessment has concluded that the impact of increased discharge from the STW as a result of development up to 2031 in Corby will result in increased flood risk along Willow Brook specifically in the vicinity of the STW outfall. As a result it is recommended that potential mitigation measures are required (despite potentially no impact on properties) and that options are identified, the feasibility of which should be determined through consultation with Corby Borough Council and the Environment Agency.

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 12

Corby Water Cycle Study Update Willow Brook Modelling Report

Appendix A. Consultation

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 13

Meeting notes

Project: Corby WCS Update Subject: Willow Brook Modelling and Mitigation Date and time: 16 Feb 2012 Meeting no: 2 Meeting place: Atkins, Peterborough Minutes by: Liz Tilbrook Present: Ian Tattersall Representing: Corby Borough Council Wayne Cattell Corby Borough Council Andra Bowyer NNJPU Rhiannon Swindale Environment Agency Clare Fravigar Environment Agency Chris Swain Environment Agency Paul Hunt Environment Agency Tom Rouse Atkins Liz Tilbrook Atkins

ITEM DESCRIPTION & ACTION RESPONSIBLE

0 Apologies Josie Bateman 1 Model results run through TR – Outlined the model results, which indicate that the greatest increase in flood risk as at the STW outfall where levels are increased between 100mm and 30mm (depending on AEP) with increase duration of flooding 15- 20mins. Elsewhere peak level increase is less. 2 Model agreement LT update report as CF – The EA agrees that the model does indeed provide a good comparison discussed. between pre and post development and that the results do not show significant changes. Although the EA still have some concern about double counting and that the model is unlikely to represent actual flood risk. IT – CBC operate with a safety factor so the conservative approach is considered acceptable. TR – Highlighted that the focus of the modelling exercise is to determine the impact of the STW outfall increase (as a result of future development within Corby). The modelling shows no inundation of properties during the 1% AEP event, even with the conservative approach and hence even though there are some increases in peak water levels, the risk to properties is not increased. PH/RS – The EA are in agreement with the model updates, although would require wording amendments to the report to reflect discussions during this meeting. In addition the report needs to make it clear that the model should only be used to compare flood risk, not to redefine flood risk along Willow Brook. 3 STW outfall levels

Next meeting: - Distribution: All present, Josie Bateman, Chris Rance Date issued: 21-02-2012 File ref: 5040250_40_DG_020

NOTE TO RECIPIENTS: These meeting notes record Atkins understanding of the meeting and intended actions arising therefrom. Your agreement that the notes form a true record of the discussion will be assumed unless adverse comments are received in writing within five days of receipt.

Meeting minutes 16-02-12.docx

ITEM DESCRIPTION & ACTION RESPONSIBLE IT – Questioned the practicality of STW discharge during flood events. Would STW still be able to discharge at the specified rate during flood events and therefore do the results actually represent the correct situation. TR – Outlined that the modelling assumes that the discharge is not restricted. At the current time it is not known whether the discharge would be restricted during flood events. However if water is restricted, the impacts on flood risk within the Willow Brook will be less than modelled results, with lower peaks, but more prolonged events. 4 Double Counting TR – As outlined earlier, the EA have some concern in relation to double counting within the model. It is suggested that to assess the impact of double counting, the model could be run with just the additional discharge resulting from development. Hence take out the current day outfall from the STW. CF – Agreed that this would be a good idea and would like to see the results of such modelling within the modelling report. TR – The results of these additional model runs and in comparison with current results could be used to define the range over which flood risk will change as a result of development. It is not known whether in reality the impact would be closer to the upper or lower bound, but the range may be small anyway. AB – Suggested that if the precautionary value is used, this may reflect flood risk impacts of development beyond 2031. 5 Mitigation IT – Outlined that the purpose of the assessment is to determine mitigation requirements and that the modelling shows low impacts so what mitigation would be required? Can it be agreed that the results do not warrant significant engineering works such as the construction of an additional culvert. RS – The EA is in agreement that significant engineering works are unlikely to be required and that instead the mitigation works could involve improving conveyance through vegetation remove or channel alignment. The culvert is not well aligned with the watercourse and therefore the works could involve changes at the downstream end of the culvert. Even though minor works are likely to be more feasible than a significant engineering scheme, all potential works should be outlined in a feasibility assessment/options report. IT – Highlighted that one potential option could involve moving the STW outfall location to downstream of the Corby Culvert and that this option should also be considered. 6 Previous WCS results EA to determine. RS – Outlined that the results indicate different mitigation works in comparison to the original WCS. The reasons for these differences need to be determined. 7 Timescales Atkins to provide The modelling report will be updated based on the outcomes of this meeting RS with updated and issued to the EA for review early w/c 20th Feb. modelling report. The draft options report to be issued w/c 5th March. Atkins to package The model files and results will be packaged and issued to CF. the model. The EA will review the updates to the modelling report and provide a response by 2nd March.

Meeting minutes 16-02-12.docx Corby Water Cycle Study Update Willow Brook Modelling Report

Appendix B. Environment Agency Licence Agreement

Atkins Corby Water Cycle Study Update | Version 4.0 | May 2012 14

2011

Special Licence – FRA/FCA - Non-Commercial

Ref: CCN-2011-28380

PARTIES ENVIRONMENT AGENCY whose principal office is at Horizon House, Deanery Road, Bristol, BS1 5AH (the “Agency”) (1) and ORGANSISATION NAME whose principal office is at Deene House, New Post Office Square, Corby, NN17 1GD (the “Licensee”) (2) BACKGROUND This licence applies if you are seeking permission for Non-Commercial re-use of Agency information and will not allow others to make commercial use either, and you have asked for Information for use in the preparation of: 1. a flood risk / consequence assessment carried out by an individual or Non-Commercial Body, or 2. a public authority strategic flood risk assessment or other public authority strategic study requiring flood risk information namely sustainability appraisals, regional spatial strategies and local development frameworks (“other strategic study”). LICENCE We, the Environment Agency (“We”), and you, the recipient of the Information ("You") agree that: 1. This agreement (the “agreement”) which is dated on the date of signing below includes these paragraphs, the Schedules below and the Standard Terms and Conditions for an Environment Agency Information/Intellectual Property Licence in Appendix 1. 2. We will provide you (if you do not already have a copy) with the Information specified in Schedule 3. 3. If Schedule 3 indicates that any of the Information is Copy Derived from Ordnance Survey Data, Special and you are not a local authority You agree to comply with the terms of the standard Pan-Government Agreement 2 (PGA-2) End User Licence, a copy of which is either attached in Appendix 2 or available on request. For the purposes of that agreement the End User means You and the Licensor means the Environment Agency. 4. If it is not possible to interpret consistently the Special Conditions in Schedule 6 below and the Standard Terms and Conditions in Appendix 1 the Special Conditions will prevail. 5. “Information” can include information, data, records, documents and other Content of any kind. 6. YOU MUST NOT USE THE INFORMATION UNLESS YOU AGREE TO ALL THE TERMS. Any such use is deemed to be an acceptance of the terms thereby immediately creating a binding contract between us

SCHEDULE 1 – Licence Fees Not applicable

SCHEDULE 2 – Approved External Use

1. For the avoidance of doubt you may use the Information in any way connected to the preparation of a flood risk/consequence assessment or (if you are a public authority) strategic flood risk assessment or other strategic study provided that in either case it is in relation to a specific piece of land or geographic area. 2. Your permission in paragraph 1 includes taking extracts of our data to Description of 1 include within the assessment or study and using the data to input into a approved external use model to produce outputs needed for the flood risk/consequence assessment or strategic flood risk assessment or other strategic study. 3. Where you are a local authority you may share the assessment or study or related outputs with other local authorities provided this use is in accordance with paragraph 1. 4. You may supply the assessment or study or related outputs to any third 2011

party if they do not include any As-Is or Copy Derived Environment Agency Information or Ordnance Survey Information or Joint Ordnance Survey Information provided that you prohibit any Commercial Use. 5. You may supply the assessment or study or related outputs to any third party as Fixed Format copies if they include any As-Is or Copy Derived Environment Agency Information or Ordnance Survey Information or Joint Ordnance Survey Information provided that you give no licence to make Commercial Use of them. Information used for 2 Any of the Information listed in Schedule 3. this purpose 3 Use type As-Is Will this use involve 4 partners? If so identify Yes - Contractors the type of partners 5 Third Party Royalties None Special conditions 6 applicable to this n/a Approved Use Information warnings 7 applicable to this n/a] Approved Use

SCHEDULE 3 – The Information Special Data 1 Number 1 Information Name & 2 AfA Code (if Willow Brook ISIS Model applicable) 3 Description One-dimensional hydraulic ISIS model of the Willow Brook Catchment. 4 Format supplied ISIS (.dat, .gxy, .ied, .ief, .zzn, .zzl) 5 Version number V2 Source Update 6 Five year review Frequency Are there any known 7 No Third Party Rights? If yes, state who owns those n/a rights Are there any special 8 conditions relating to No this Information? Are there any information warnings 9 No relating to this Information? 10 Full details/attributes Is Ordnance Survey No Information, or Joint If Yes, how many terminal users of the Information will the Licensee have? Ordnance Survey … Information, identified “Ordnance Survey Information” is information in respect of which Ordnance Survey (or 11 in (6) above? that of someone that they have a relevant licence from) own the Intellectual Property. If yes, is the Licensee “Joint Ordnance Survey Information” is Information in respect of which Ordnance currently unlicensed Survey Intellectual Property (or that of someone that they have a relevant licence from) is to use it (e.g. directly incorporated into the Information. from OS)? 2011

1 Number 2 Information Name & 2 AfA Code (if Willow Brook With Defences Model Outlines applicable) GIS modelled outlines showing the extent of flooding for scenarios: 50%, 20%, 3 Description 10%, 4%, 2%, 1.3%, 1%, 1%+CC, 0.5%, 0.1%, 0.1%+CC. 4 Format supplied .shp 5 Version number 2 Source Update 6 Five year review Frequency Are there any known 7 No Third Party Rights? If yes, state who owns those n/a rights Are there any special 8 conditions relating to No this Information? Are there any information warnings 9 No relating to this Information? 10 Full details/attributes Is Ordnance Survey No Information, or Joint If Yes, how many terminal users of the Information will the Licensee have? Ordnance Survey … Information, identified “Ordnance Survey Information” is information in respect of which Ordnance Survey (or 11 in (6) above? that of someone that they have a relevant licence from) own the Intellectual Property. If yes, is the Licensee “Joint Ordnance Survey Information” is Information in respect of which Ordnance currently unlicensed Survey Intellectual Property (or that of someone that they have a relevant licence from) is to use it (e.g. directly incorporated into the Information. from OS)?

1 Number 3 Information Name & 2 AfA Code (if Topographical Survey applicable) Topographical Survey of Willow Brook including the North, Central and Southern 3 Description arms of the watercourse 4 Format supplied .dwg 5 Version number 2005 Source Update 6 n/a Frequency Are there any known 7 No Third Party Rights? If yes, state who owns those n/a rights Are there any special 8 conditions relating to No this Information? Are there any 9 information warnings No relating to this 2011

Information? 10 Full details/attributes Is Ordnance Survey No Information, or Joint If Yes, how many terminal users of the Information will the Licensee have? Ordnance Survey … Information, identified “Ordnance Survey Information” is information in respect of which Ordnance Survey (or 11 in (6) above? that of someone that they have a relevant licence from) own the Intellectual Property. If yes, is the Licensee “Joint Ordnance Survey Information” is Information in respect of which Ordnance currently unlicensed Survey Intellectual Property (or that of someone that they have a relevant licence from) is to use it (e.g. directly incorporated into the Information. from OS)?

1 Number 4 Information Name & 2 AfA Code (if River Nene E-Report applicable) Model report detailing the hydrological inputs and model build of the River Nene 3 Description Catchment including Willow Brook. 4 Format supplied PDF/word 5 Version number 2009 Source Update 6 n/a Frequency Are there any known 7 No Third Party Rights? If yes, state who owns those n/a rights Are there any special 8 conditions relating to No this Information? Are there any information warnings 9 No relating to this Information? 10 Full details/attributes Is Ordnance Survey No Information, or Joint If Yes, how many terminal users of the Information will the Licensee have? Ordnance Survey … Information, identified “Ordnance Survey Information” is information in respect of which Ordnance Survey (or 11 in (6) above? that of someone that they have a relevant licence from) own the Intellectual Property. If yes, is the Licensee “Joint Ordnance Survey Information” is Information in respect of which Ordnance currently unlicensed Survey Intellectual Property (or that of someone that they have a relevant licence from) is to use it (e.g. directly incorporated into the Information. from OS)?

1 Number 5 Information Name & 2 AfA Code (if National Flood and Coastal Defence Database applicable) 3 Description GIS files and access databases of the Willow Brook defences and structures. 4 Format supplied .shp, .tab and .mdb 5 Version number - Source Update 6 n/a Frequency 2011

Are there any known 7 No Third Party Rights? If yes, state who owns those n/a rights Are there any special 8 conditions relating to No this Information? Are there any information warnings 9 No relating to this Information? 10 Full details/attributes Is Ordnance Survey No Information, or Joint If Yes, how many terminal users of the Information will the Licensee have? Ordnance Survey … Information, identified “Ordnance Survey Information” is information in respect of which Ordnance Survey (or 11 in (6) above? that of someone that they have a relevant licence from) own the Intellectual Property. If yes, is the Licensee “Joint Ordnance Survey Information” is Information in respect of which Ordnance currently unlicensed Survey Intellectual Property (or that of someone that they have a relevant licence from) is to use it (e.g. directly incorporated into the Information. from OS)?

1 Number 6 Information Name & 2 AfA Code (if Weldon FSR Section 10 Inspection Report applicable) 3 Description A report detailing the latest inspection of the Weldon FSR. 4 Format supplied PDF 5 Version number March 2010 Source Update 6 n/a Frequency Are there any known 7 No Third Party Rights? If yes, state who owns those n/a rights Are there any special 8 conditions relating to No this Information? Are there any information warnings 9 No relating to this Information? 10 Full details/attributes Is Ordnance Survey No Information, or Joint If Yes, how many terminal users of the Information will the Licensee have? Ordnance Survey … Information, identified “Ordnance Survey Information” is information in respect of which Ordnance Survey (or 11 in (6) above? that of someone that they have a relevant licence from) own the Intellectual Property. If yes, is the Licensee “Joint Ordnance Survey Information” is Information in respect of which Ordnance currently unlicensed Survey Intellectual Property (or that of someone that they have a relevant licence from) is to use it (e.g. directly incorporated into the Information. from OS)?

2011

Non Special Data Discharge Consents for Corby Sewage Treatment Works in PDF (12287 AW5NF297.pdf & 13651CorbyVar06.pdf). Historic Flood Extent Map in PDF.

SCHEDULE 4 – Contact Details Operational contact (day to day) AGENCY LICENSEE Position: Flood Risk Mapping & Data Principal Engineer Management Technical Specialist Name: Clare Fravigar Ian Tattersall Tel: 01522 785801 01536 464177 Email: clare.fravigar@environment- [email protected] agency.gov.uk

SCHEDULE 5 – Commencement Date and Term

This agreement commences on 15/08/2011 for a period of 1 years ending on 14/08/2012 Next major review date: 2013 for implementation on or after 1 January 2014 The major licensing review aims to review all Agency licences and bring all licence users onto the same terms and conditions. When the review occurs the new terms will replace the terms and conditions of this agreement; this does not affect your right to terminate this agreement.

SCHEDULE 6 – Special Conditions No. Insert Details Special Conditions applicable for all Non-Commercial FRA/FCA Licensees The following uses are licensed for the purposes of Standard Condition 5.1: i. If Schedule 3 indicates that either Ordnance Survey Information or Joint Ordnance Survey Information is included and the Licensee is not a local authority or already licensed to use it the Licensee may use the Information for the purposes identified in Schedule 2 part 1 paragraphs 1 1 to 3 whether it is Internal Use or External Use. ii. If special condition 1(i) does not apply The Licensee may make any Non-Commercial Internal Use and Approved External Use identified in Schedule 2 provided that the Agency is acknowledged as the copyright owner where applicable. The Licensee shall take reasonable care when supplying Information or Derived Information 2 externally taking into account any relevant Information Warning. Special Conditions applicable as we require a licence to use outputs derived from our Information You will supply to the Environment Agency copies of any assessments/studies and related outputs created pursuant to the supply of the Information (including any model and all input, processing and 3 output data) and any records of historic flooding in the study area regardless of the flood source all of which are hereinafter referred to as “the Data”. If any Information (including model input/outputs) is altered or modified in any way by you, you will, 4 when supplying the Data, enclose documentation detailing the changes “the Changes”. You will offer us an opportunity to review and comment on the Data and the Changes and agree not to publish or supply the Data or any part thereof to any third party if we choose to review and 5 comment. If we do choose to review and comment we will do so within 10 Working Days of receipt of the Data. You hereby grant the Environment Agency an unrestricted and perpetual licence to use the Data or any part thereof for all Internal purposes and supply to others as derivatives (such as incorporation 6 into the Environment Agency's products) but supply of the Data “As-Is” to others will be made only as required by law. Special Condition applicable when we supply more information than is requested. 2011

For technical reasons the Information you have been supplied may be greater than strictly 7 necessary for the site or project you are working on and so contain more data than specified in Schedule 3. You must not use such additional Information.

SCHEDULE 7 – Information Warning No. Insert Details

1

2

3

Signed on behalf of the Agency

Name Clare Fravigar

Job Title Flood Risk Mapping & Data Management Technical Specialist

Signature

Witnessed by (Name) John Ray

Witness job title (or address if not Agency) Flood Risk Mapping & Data Management Team Leader

Witness Signature

Date 15/08/2011

2011

Appendix 1 - Standard terms and conditions for an Environment Agency Information / Intellectual Property Licence 1. Definitions and Interpretation contracted to provide services to the information 1.1. In this agreement the following words shall have the provider, when: following meanings unless the context otherwise ƒ use is limited to the purposes of that contract, and requires: ƒ all terms of the original licence are applied to the “Agency Primary Source” means the relevant primary Contractor, and Dataset or Content source created and (where ƒ the person letting the contract remains responsible applicable) maintained for the statutory functions of the for those terms, and Agency which is national (if such exists) or local (if not ƒ the Contractor does not pass the Information to any national). person other than the Licensee or a subcontractor “Approved External Uses” means the Licensee’s who complies with these conditions and specific and identified External Uses that are extant at ƒ the Contractor destroys all copies of the Information the Commencement Date (or are added by the parties or Derived Information supplied (and anything Copy from time to time pursuant to condition 20) that are set Derived from that) at the end of the contract. out in and fully meet the descriptions included in “Copy Derived” means that the derived Information is Schedule 2. not As-Is but either includes a copy of the Information as “Archival Use” means a) Internal Use by the Licensee a whole or a substantial part of it or the derived or its contractors to retain copies of the Information or b) Information can be reverse engineered to create a copy any External Use that had previously been Approved of the Information or a substantial part thereof. In External Use to the extent necessary to answer technical deciding whether or not information or an information support questions or to comply with any statutory or product is Copy Derived it is necessary to look at regulatory requirement in either case for a period not whether a systematic series of extractions or the exceeding six years. product, taken as a series of unit sales, meets the test of “As-Is” means a copy of the whole or part of a piece of being Copy Derived. Information that is unaltered and un-adapted other than “Dataset” means a collection of thematically linked data, layout (font, size, colour and other minor display facts, intelligence, or advice in any recorded form (but changes). This includes bundling with other Information not including documents) in the same format whether or or with a cover sheet provided that the original not the collection is all in one place or in a single information is discrete. It does not include merging of database or other single system. information or changing format other than between Fixed “Derived Information” unless the context requires Format types (for example, pdf to hardcopy or jpeg to otherwise means Copy Derived Information or Process tiff). Derived Information. “Commercial” means Internal Use for any “End User” means any person using information purpose within a Commercial Body, or supplied in pursuance of an Approved External Use for ƒ offering a product or service containing Information or its own Internal Use. Derived Information for direct monetary “End User Licence Agreement” and “EULA” mean the compensation such as the sale of a book or terms under which the Licensee supplies Information or newsletter with a cover charge even if it does not Derived Information to End Users (see condition 6) cover all costs, or “External As-is Use” means use that is not Internal Use ƒ offering a product or service based on Information for that involves the creation of As-Is Information. indirect commercial advantage by a Commercial “External Derived Use” means use that is not Internal Body, Use that involves the creation of Derived Information. that is not Public Sector Use or Statutory Supply (in all of “External Use” means External As-Is Use and/or the cases above). External Derived Use. “Commercial Body” means an organisation that is “Fees” means Licence Fees and any charges applicable primarily engaged in a profession, even if it has public to External Use. task functions (unless it is a body that is set up under a “Fixed Format” means Information that is formatted in constitution/ memorandum of association/trust deed such a way as to be static and unalterable (or not easily which prevents it from distributing any of its income alterable without the loading of special software). It will whether as money or in any other form to its Committee, typically include hard copy, portable document format board or members and limits payments to employees to (pdf), image format (such as jpeg, gif, tiff and bmp) and salaries and a bonus scheme that is not designed to video format (such as mpeg, avi and wmv). distribute all profits or surplus income but has provisions “Information” means the Datasets (including sets of for distribution of surplus income for some public good documents) or other Content identified in Schedule 3. (usually charitable) purpose ) or is engaged in trade or “Information Warning” means information required by commerce. Schedule 7 to be taken into account when using the “Confidential Information” means any information Information or Derived Information. relating to this agreement disclosed by one party to the “Intellectual Property Rights” means any patent, other under this agreement or coming to the Licensee’s copyright, database right, registered design, trademark or the Agency’s attention directly or indirectly as a result or other industrial or intellectual property together with of this agreement whether orally or in writing and any applications for any of the foregoing. whether or not such information is expressly stated to be “Internal Use” means use of Information or Derived confidential or marked as such provided that such Information that is not a supply of it externally other than information is confidential in nature. for Contractor Use, Professional Use, Regulatory Use, or “Consistency Principle” means the principle whereby display of fixed image information to third parties either End Users of Information receive Information that is the for demonstration purposes (including marketing and same from whichever person they obtain the Information. training) on the licensee’s or third party premises (but not “Consultant” means a person who provides in removable documents) or display on a website professional services to a client and as a necessary but operated for Non-Commercial purposes with no use minor part of that service includes Agency Information or rights granted other than to read. Derived Information as background supporting material “Licence Fees” means the Agency’s marginal costs of to the services. supply charges and licensing charges as identified in “Content” has the same meaning as in the Re-Use of Schedule 1 together with Third Party Royalties Public Sector Information Regulations 2005 but may also “No Detriment Principle” means that any intended use include computer programs. of Information must not represent a risk of: “Contractor Use” means passing of Information or ƒ being misleading to the End User; or Derived Information to a person (Contractor) who is 2011

ƒ detriment to the Agency’s ability to achieve its “Source Update Frequency” means the frequency with objectives; or which an Agency Primary Source is updated. ƒ detriment to the environment, including the risk of “Standard Condition” means one or more of the reduced future enhancement; or Standard Terms and Conditions in Appendix 1 also ƒ being prejudicial to the effective management of referred individually as a numbered “condition”. information held by the Agency; or “Statutory Supply” means a supply of information by a “Non-Commercial” means use that is not Commercial. public sector body required to do so under the “Notice” means a notice given in accordance with Environmental Information Regulations 2004, the condition 21. Freedom of Information Act 2000, the Data Protection “Principles” means the Transparency Principle, the Act 1998 or any other statutory provision requiring Consistency Principle and the No Detriment Principle. information to be supplied, provided that recipients are “Process Derived” in relation to Information means the limited to Internal Use. mechanism by which a derivative requires the physical “Third Party Claim” means any claim for compensation input of the Information into a rules-based process or any other legal remedy (including remedies in respect whether or not that process is automated or done by of negligence) in connection with this agreement or the human intervention where the resulting information is not Information by any person other than the Licensee or the Copy Derived or created As-Is from the Information and Agency. any use that involves manipulation (other than making “Third Party Royalties” means the charges payable to As-Is copies) of the original information is Process third parties as identified in Schedule 1 (Internal Use) Derived if it is not Copy Derived. and Schedule 2 (External Use). “Professional Use” means, in respect of a particular “Transparency Principle” means the principle that End client and particular transaction or matter, i) internal use Users should not be misled in any way about matters by a Consultant for a client and ii) As-Is Fixed Format relating to the Information which affect its potential supply of Environment Agency information by a usefulness or as regards its source. Consultant to a client, where: “Working Day” means Monday to Friday inclusive from a) the information is obtained directly from the 9:00am to 5:30pm, excluding UK public holidays. Environment Agency (and any applicable Licence Fees “written” includes fax and email and any other paid) or by way of an Environment Agency value added electronic text. reseller approved product or Copy Derived derivative “Year” means each period of twelve months product, as and when needed for and on behalf of a commencing on the Commencement Date and each particular client anniversary thereof. b) the information supplied to a client relates to a site in 1.2. Unless the context otherwise requires: single ownership and can include any other information 1.2.1 a reference to any statute, statutory provision or necessary for an environmental assessment of that site; statutory instrument includes a reference to that and statute, statutory provision or statutory instrument c) the client is not granted any licence to copy, adapt or together with all rules and regulations made under sublicence the information other than to take one back it or them as from time to time amended, up copy or to supply As-Is Fixed Format copies consolidated or re-enacted; necessary for that client(or the Consultant can supply 1.2.2 words importing a gender shall include all such copies on behalf of the client) provided that no genders; charge is made for such supplies; and 1.2.3 reference to any person includes any legal entity, d) no charge is made by the Consultant to its client for including without limitation a natural person or the information other than a charge for professional incorporated entity; and services and disbursements; and 1.2.4 words importing a singular include the plural and e) where the information is Environment Agency vice versa. information, ownership is attributed to the Environment 2. Background Agency 2.1 The Agency wishes to appoint licensees of its “Public Sector Use” means use of Information or Information to facilitate environmental work done on its Derived Information: behalf or in connection with its responsibilities and to ƒ for Internal Use by a public sector body, a body that increase environmental awareness through increased is subject to the Environmental Information dissemination of its information and other Content. Regulations 2004, or a body having a public task; 2.2 The Licensee has offered or agreed to act as or is ƒ by a public sector body in products or services to already a Licensee and the Agency has agreed to the other parts of EU and UK Government or public Licensee being so engaged on the terms and conditions sector bodies, or set out in this agreement. ƒ by a public sector body in products or services to any 2.3 The Agency and the Licensee acknowledge that the body outside the UK where the supply is in Consistency Principle and the Transparency Principles pursuance of international treaties or conventions are in the interests of fairness and improved service to provided that in each case of Public Sector Use: End Users. ƒ all use (including that by any permitted recipient 3. Term body) is in pursuance of that body’s statutory This agreement shall commence with effect from the functions or public task, and Commencement Date and shall continue for a period ƒ any charge reflects only the additional marginal costs (the “Term”) specified in Schedule 5 when it will expire incurred in the provision of those products or automatically without notice, subject to earlier services. termination as set out in conditions 12. The term may be Note: The marginal costs of a UK trading fund (or any extended by mutual agreement between the parties in similar government body) can include all charges that accordance with condition 20. are required by legislation or binding government rules in 4. Supply of Information to the Licensee by the Agency relation to making supplies to other public sector bodies 4.1 The Agency shall supply to the Licensee the Information “Regulatory Use” means inclusion by or on behalf of a (where these are specified in Schedule 3) from the person of Fixed Format information either As-Is or as Agency Primary Source held by the Agency (to the Derived Information in any documentation where this is extent that the Licensee does not already hold such reasonably necessary in connection with any process of Information) and use all reasonable endeavours to do so a court, tribunal or regulatory body (but not including a on the Commencement Date or as soon as practicable trade association) affecting that person thereafter “Re-use” shall have the same meaning as in Regulation 4.2 Where the Information exists in electronic form the 4 of the Re-use of Public Sector Information Regulations Agency shall supply it in that form but shall at its 2005. discretion choose the electronic media. 2011

5. Licence NOTIFICATIONS BY THE LICENSEE 5.1 In consideration of the mutual obligations in this 6.1.10. The Licensee will notify the Agency if: agreement and the payment (if applicable) by the a. it becomes aware that it is in breach of the Licensee of the Fees the Agency hereby grants to the licence agreement, Licensee a non-transferable, non-exclusive revocable b. it suspects or discovers any possible licence subject to the terms of this agreement to supply infringement of the Agency’s Intellectual Information or Derived Information in a Statutory Supply, Property Rights in the Information by a third make the uses specified in the Special Conditions and to party, or take any copies of the Information reasonably needed in c. it suspects or discovers that use of the connection with licensed use including backup copies. Information might be an infringement of any 5.2 This licence is given to the Licensee personally and not third party’s Intellectual Property Rights or of to any affiliated company or organisation. any third party’s contractual rights derived 6. Obligations of the Parties therefrom or be any other breach of 6.1 The Licensee shall: confidentiality or statute, or INFORMATION d. it receives any third party claim or a significant 6.1.1. not use the Information or any Derived complaint or report in connection with this Information other than as licensed by this agreement or the Information and will, subject agreement or under a separate licence from the to any legally binding confidentiality, supply Agency and for the avoidance of doubt this copies of any relevant documentation to the condition does not prohibit products or derivatives Agency. that do not contain Information or comprise 6.2 The Agency shall: Derived Information; 6.2.1 supply to the Licensee such information and 6.1.2. not use any other Agency information unless assistance as the Licensee may reasonably under a separate licence from the Agency and request, to the Contact identified in Schedule 4, where the Information replaces earlier information for the purposes of this agreement in connection supplied not use that earlier information otherwise with the processes and procedures used to create than for Archival Use (no Archival Use Fee is the information unless such information is payable if replacement information is licensed); confidential to the Agency or supply would breach 6.1.3. not (otherwise than to a Contractor) supply the any intellectual property rights, contractual Information to anyone else if it is not an Approved restrictions or other third party confidentiality in External Use nor supply any other Agency disclosing them; information to any other person and in particular 6.2.2 treat equitably the Licensee and other comparable ensure that any web hosting or web mapping licensees services are consistent with this obligation and not 7. Payment given any greater licence to use the Information 7.1 Fees are as detailed in Schedules 1 and 2 and are, than is permitted by way of Contractor Use; subject to any Special Conditions, payable in advance of EXTERNAL SUPPLY OF INFORMATION OR DERIVED this agreement. INFORMATION 7.2 The Licensee shall keep true, accurate and sufficient 6.1.4. comply with any Terminal Use Restriction and any accounts and records to enable the amount of all restriction on use of the Information that derive payments required under this agreement to be from third party rights in respect of the Information determined. The Licensee shall keep such accounts that are identified in Schedule 3; and records during the life of this agreement and six ears 6.1.5. take all reasonable technical, contractual and after its termination or expiry. other security measures to protect the integrity 8. Liability and security of Information and to prevent any use 8.1 QUALITY AND FITNESS FOR PURPOSE of the Information contrary to this agreement and The Agency does not warrant that the Information will any breach of this sub-condition which has a always be accurate, complete or up to date or that the demonstrable effect shall be capable of being Information will provide any particular facilities or treated as a material breach of this agreement; functions or be suitable for any particular purpose. The PUBLICITY & MARKETING Licensee must ensure that the Information meets its 6.1.6. not hold itself out, in relation to the Agency, as an needs and is entirely responsible for the consequences authorised Licensee of anything supplied nor hold of any use of the Information. itself out as having any other relationship with the 8.2 ELECTRONIC FORMAT Agency unless expressly authorised by the If an electronic format has been used, the Agency Agency in writing; applies reasonable endeavours to ensure that but cannot 6.1.7. not refer to the Agency or use Information in any guarantee that the media on which the Information is marketing or publicity material without prior provided will always be free from defects, computer approval of the Agency in writing; viruses, worms, trojan horses, software locks or other END USER TERMS AND CONDITIONS similar code of a destructive or unwelcome nature. The 6.1.8. ensure that any supply to a third party in Licensee should carry out all necessary checks prior to pursuance of this agreement of As-is or Copy loading the Information on to its computer system. Derived Information is on the terms of an End 8.3 ECONOMIC AND INDIRECT LOSS User Licence Agreement (EULA) which: Other than in respect of the obligation in condition 6 to a. prohibits any External Use that is not comply with the Principles, the provisions in condition 8 separately licensed by the Agency; relating to information supply delays, the warranty in b. requires the As-Is or Copy Derived Information condition 10 and condition 11, neither party shall be to be destroyed at the end of the term of the liable to the other or any other person (whether in EULA; contract or in negligence or in other tort or otherwise) for: COMPLIANCE WITH THE PRINCIPLES a. any economic losses (including without limitation loss 6.1.9. do nothing which might contravene the Principles of revenues, profits, contracts, business or and any breach of this sub-condition which has a anticipated savings) other than Fees; or demonstrable effect shall be capable of being b. any loss of goodwill or reputation; or treated as a material breach of this agreement c. any special, indirect or consequential losses in any provided that provision of truthful responses to case whether or not such losses were within the enquiries put to the Licensee which are purely contemplation of the parties at the date of this factual in nature shall not be capable of Licence (including loss of business, profit, reputation constituting a breach of this agreement unless or goodwill) arising out of or in connection with this they are a breach of condition 11; agreement or its subject matter. 2011

8.4 MAXIMUM LIABILITY 10.3 REMEDYING OF DEFECTS The Agency’s and the Licensee’s maximum aggregate If any use of any part of the Information in accordance liability to the other (including legal costs) in connection with this agreement infringes any Intellectual Property with this agreement shall not (apart from payment of Rights the Agency shall use all reasonable endeavours Fees and the indemnities in condition 17) exceed the to obtain the right (without charge) for the Licensee to total sum of Fees due under this agreement or such continue to use and to distribute the infringing other sum as shall be indicated in Special Conditions. Information. If however the Agency is unable to do this, 8.5 NOTICE OF CLAIMS without prejudice to the above warranty in this condition Neither party shall be liable for any claim between the and any other remedy the Licensee may have, the parties (not being in relation to a Third Party Claim) Agency shall use all reasonable endeavours to modify arising under this agreement unless Notice of the claim (or replace) the infringing Information so as to be as is given to the other within six months of becoming close to the usefulness of the original Information as aware of the circumstances giving rise to such claim, or reasonably possible or (if this is not possible) remove the of such time as the relevant party ought reasonably to infringing Information from Schedule 3. have become aware of such circumstances. 10.4 NO SPECIFIC PERFORMANCE 8.6 DEFECTS IN OWNERSHIP Neither party shall be entitled to bring an action for The Agency shall not be liable under this agreement for specific performance of the other party’s obligations any defect in its Intellectual Property Rights to the under this agreement where the performance of such Information if: obligation would be in breach of the Intellectual Property 8.6.1 it has used reasonable endeavours to ensure that Rights of a third party. Information where the defect occurs (being one of 11. Confidentiality those separately identified and numbered 11.1 The Licensee and the Agency agree: sections in Schedule 3 or any addition thereto) is 11.1.1 to keep Confidential Information in strict in the generality the property of the Agency or confidence and secrecy; property of a third party who has licensed the 11.1.2 not to use any Confidential Information other than Agency to supply its information; and for the purposes of this agreement; 8.6.2 such defect in Intellectual Property Rights in that 11.1.3 to restrict the disclosure of any part of Confidential part of the Information after the application of the Information to such of their respective employees, provisions in condition 10 on remedying agents and contractors who need access to it to infringements would not require the withdrawal of enable them to perform their obligations under or that part in full or a significant part thereof, it being in connection with this agreement and to bring to accepted that less than five percent (5%) the attention of such persons the duty of (measured either as to value, geographically, or confidentiality under this condition before allowing by quantity) would not be significant. them access to Confidential Information unless 8.7 DEATH AND PERSONAL INJURY they are already bound by alternative equivalent Nothing in this condition 8 shall limit or exclude either obligations; and party’s liability for death or personal injury arising from its 11.1.4 not to disclose any Confidential Information to any negligence. other third parties without the prior written consent 8.8 REPRESENTATIONS of the other. Except as expressly provided in this agreement, all 11.2 This condition 11 shall survive the expiry of this representations, conditions and warranties whether agreement or its termination howsoever caused. express or implied (by statute or otherwise) are hereby 11.3 This condition 11 shall not apply to Confidential excluded to the fullest extent permitted by law provided Information: that this shall not exclude statutory or common law rights 11.3.1 which when it was disclosed was in the public in respect of negligence. domain otherwise than because of a breach of an 9. Audits obligation of confidentiality; or 9.1 Not more than once in any Year and for 6 years post 11.3.2 that a party could be required to disclose by law; termination the Licensee shall permit the Agency or its or agents to have access to its records of dealings in 11.3.3 that has been disclosed in accordance with the respect of the Information on not less than 5 Working Public Interest Disclosure Act 1998, the Freedom Days’ Notice in order to verify the amount of Fees due of Information Act 2000, the Environmental from the Licensee, compliance with the Principles and Information Regulations 2004 or the Re-use of whether any other provision of the agreement has been Public Sector Information Regulations 2005; or breached and to take and retain copies of such records 11.3.4 received by a party from a third party at liberty to for its own use. disclose it; or 9.2 If the results of the verification under condition 9.1 reveal 11.3.5 supplied to a third party whose Intellectual a significant breach of the agreement is identified, the Property Rights have been used in connection cost of the verification shall be paid by the Reseller, but with the Information and who has reasonably otherwise such cost shall be borne by the Agency. asked for such Confidential Information in order to 9.3 If the results of any verification under condition 9.1 verify payments due to them. identify additional Fees due to the Agency such Fees 11.4 Neither party shall be entitled to bring an action for shall be payable by the Reseller. specific performance of the other party’s obligations 9.4 The Agency shall be entitled to invoice the Reseller for under this agreement where the performance of such any costs due to it under condition 9.2 and any Fees due obligation would breach a legally binding confidentiality under Condition 9.3 and the Reseller shall pay such requirement of a third party. sums within 20 Working Days of the date of the Agency’s 12. Termination invoice together with VAT at the then prevailing rate. 12.1 The Agency shall be entitled to terminate this agreement 10. Intellectual Property Rights by Notice in accordance with the following provisions : 10.1 NO TRANSFER OF RIGHTS 12.1.1 With 60 Working Days Notice if the Licensee is in No Intellectual Property Rights are transferred or material breach of any of the terms of this licensed to the Licensee save those which are expressly agreement, the Notice identifies that breach and, provided in this agreement (see in particular condition 5). in the case of a breach capable of remedy, 10.2 WARRANTY indicates that termination will not follow if the The Agency warrants that subject to the provisions on Licensee remedies that breach in such manner as defects in ownership contained in condition 8 it has all may be described in the notice, within that period other powers and rights necessary to grant to the of 60 Working Days; or Licensee the licences set out in condition 5. 12.1.2 With 20 Working Days Notice if the Licensee has persistently (and not less than 5 times in any 12 2011

month period) committed a non-material breach of or to agreeing upon such alternative arrangements as any of the terms of this agreement, the Notice may be fair and reasonable. identifies that breach and, in the case of such 14.4 The Agency shall not be liable to the Licensee for delay breach capable of remedy, indicates that 20 in performing its obligations under this agreement if such Working Days is available, to remedy that breach delay arises out of the overriding need to comply with its in such manner as may be described in the statutory obligations. notice, in addition and before the 20 Working 15. Assignment Days period before termination commences; or The Licensee may not transfer or in any other way make 12.1.3 With 20 Working Days Notice if the Licensee over to any third party the benefit of this agreement undergoes a change of ownership or control either in whole or in part without the express prior written (other than a change that is within the public consent of the Agency such consent not to be sector) to which the Agency has, within 20 unreasonably withheld or delayed. Working Days of becoming aware of such 16. Waiver change, reasonably and properly taking into Failure by either party to exercise or enforce any rights account the Principles, and objected; or available to it, or any forbearance, delay or grant of 12.1.4 immediately, if a resolution is passed or an order indulgence, will not (subject to condition 17 below) be is made for the winding up of the Licensee (save construed as a waiver of its rights under this agreement for the purpose of a bona fide re-construction or or otherwise. amalgamation) or the Licensee becomes subject 17. Indemnities to an administration order, or a receiver or 17.1 Each party shall indemnify the other against all costs administrative receiver is appointed over any of (including reasonable and proper legal costs), claims, the Licensee’s property or assets, or the Licensee damages, demands and expenses arising directly or is dissolved; or indirectly out of any Third Party Claim in accordance with 12.2 The Licensee shall be entitled to terminate this the following principles: agreement by 20 Working Days' Notice for any reason. 17.1.1 the Licensee shall (subject to the sub-conditions 12.3 The rights to terminate this agreement given by this below) be responsible for any claims which arise condition 12 shall be without prejudice to any other right in connection with the supply or use of the or remedy of either party in respect of the breach Information in so far as that claim arises from any concerned (if any) or any other breach. breach of the agreement by the Licensee or a 13. Consequences of Termination Licensee Agent; 13.1 Subject to the provisions of this condition, on expiry or 17.1.2 the Agency shall, subject to the provisions on termination of this agreement the Licensee’s entitlement defects in ownership in condition 8, be to use the Information shall, cease. responsible for any claims that use of the 13.2 All copies of the Information or any Copy Derived Information infringes any United Kingdom Information in the Licensee's possession (and for the Intellectual Property Rights or has been supplied avoidance of doubt this includes persons making in breach of a legally binding confidentiality Contractor Use) shall, subject to Archival Use authorised requirement; by this condition below, be destroyed. 17.1.3 nothing in these indemnities shall have the effect 13.3 Continued use by an End User of Information or Derived of requiring one party to indemnify the other to the Information supplied under this agreement prior to expiry extent that the other has been negligent or in or termination is licensed by the Agency for the wilful default; remainder of the period of any EULA that is compliant 17.2 The Agency or the Licensee (as the case may be) shall: with this agreement. This condition shall survive 17.2.1 forthwith on receipt of a written request from the termination or expiry of this agreement. Licensee or the Agency (as the case may be) give 13.4 the Licensee will be issued on request an Archival Use to the other the sole conduct of the defence and licence subject to further payment of annual Licence settlement of any such claim and at no time admit Fees, where Licence Fees are payable under this liability; and agreement, with a discount of 80% on Licence Fees 17.2.2 act in accordance with the reasonable instructions (other than Third Party Royalty Fees) without any of the other and give all such assistance as it may Licence Fee cap if such was applicable in the reasonably require to defend or settle such claim. agreement. 17.3 This condition 17 shall not apply when both parties are 13.5 Internal Use Licence Fees shall in the first Year be public sector bodies. payable in full for that Year regardless of when it is 18. Entire agreement terminated and in subsequent years be due for the full This agreement constitutes the entire agreement year (of 1 April to 31 March) in which this agreement is between the parties and supersedes all oral or written terminated but, subject to the provisions on Archival Use, agreements, representations, understandings or not thereafter. arrangements relating to its subject matter other than 13.6 On expiry of this agreement Internal use Licence Fees subsequent written alterations to this agreement shall be due pro rata up to the date of expiry. mutually agreed by the parties. The parties irrevocably 14. Force Majeure, National Security and Agency’s and unconditionally waive any right to rescind this Operating Requirements agreement by virtue of any misrepresentation and to 14.1 Neither party shall be liable to the other for any delay in claim damages for any misrepresentation save in each or failure of performance of its obligations under this case where such misrepresentation was made agreement (other than an obligation to pay money) fraudulently. arising from any cause beyond its reasonable control 19. Severance including, without limitation, any of the following: Act of If any part of the agreement is found by a court of God; governmental act (including acts of regulatory competent jurisdiction or other competent authority to be authorities); statutory obligation; industrial action; any unenforceable, then that part will be severed from the change in the law or the interpretation of the law by the remainder of the agreement which will continue to be courts; war; fire; flood; explosion or civil commotion valid and enforceable to the fullest extent permitted by (“Force Majeure”). law. 14.2 If a party is affected by Force Majeure it shall forthwith 20. Variation give Notice to the other party of the nature and extent of CHANGES BY THE LICENSEE such Force Majeure. 20.1 The Licensee may request by Notice that this agreement 14.3 If Force Majeure prevails for a continuous period in be amended, modified, varied or supplemented and excess of 20 Working Days the parties shall enter into such request shall be accompanied at that time or bona fide discussions with a view to alleviating its effects subsequently by such additional information in 2011

connection therewith that the Agency reasonably 21.3 Notices may be sent by first class mail (or other requires. comparable and reputable postal services) or by email. 20.2 The Agency may also by Notice propose reasonable 21.4 Correctly addressed notices sent by first class mail shall consequential variation of any other part of the be deemed to be delivered 2 Working Days after posting. agreement (including, without limitation, Schedules 1, 3, 21.5 Correctly addressed emails shall be deemed to be 6 and 7) and if such changes are proposed the date a delivered when sent provided that a confirmation copy is variation takes effect will be not earlier than the date sent by first class mail within 24 (twenty four) hours. such consequential variations are agreed. 21.6 Nothing in these standard conditions shall prevent the 20.3 Variations requested by the Licensee and consequential sender of any Notice from choosing a longer period than variations proposed by the Agency must be agreed by the minimum required. both parties in writing signed by or on behalf of the 21.7 Any consent, approval or agreement given pursuant to Agency and the Licensee and neither party shall this agreement shall be in writing and in the case of the unreasonably refuse such requests for a variation. Licensee shall be signed in accordance with the contacts CHANGES BY THE AGENCY records in Schedule 5, which may be varied in writing by 20.4 The Agency may by Notice: either party from time to time. 20.4.1 withdraw any of the Information from Schedule 3 22. Relationship of Parties by giving at least twelve calendar months Notice Nothing in this agreement shall: with reasons if it reasonably believes that any of 22.1 create a partnership or joint venture between the parties, the Principles would be substantially prejudiced; nor shall this agreement constitute one party the agent or of the other or give either party authority to act or hold 20.4.2 withdraw any of the Information (or attributes itself out as having authority to act on behalf of the other; thereof) from Schedule 3 by giving at least 20 or Working Days’ Notice with reasons if would be in 22.2 confer or purport to confer on any third party any benefit breach of any legislation or a direction by any or rights in respect of the terms of this agreement. relevant regulatory body by continuing to license 23. Dispute Resolution that part of the Information; or 23.1 All disputes under or in connection with this agreement 20.4.3 vary description (other than attributes) of, or add shall be referred first to the parties’ respective managers attributes to, Information in Schedule 3, or amend with responsibility for the day to day management of this Schedule 6 or Schedule 7 by giving at least 20 agreement. Working Days’ Notice with reasons if such change 23.2 Either party may thereafter initiate, at any time, the other is justified by any of the Principles or if there is a party’s standard internal complaints process (or if none requirement imposed on the Agency in respect of exists refer the dispute up to the next level of third party rights in, or used in the creation of, any management). part of the Information; or 23.3 After the relevant complaints procedure or referral is 20.4.4 amend Licence Fees not earlier than the review completed (within the relevant timescales set out therein date stated in Schedule 1; or or in the absence of a timescale, the time shall be 20.4.5 replace Appendix 1 Terms and Conditions of this deemed to be 20 Working Days), the dispute may be agreement on or following the next major review referred by either party to the parties’ respective Chief date identified in Schedule 5. Executive Officers. 20.5 In respect of changes made by the Agency under 23.4 If the parties’ respective Chief Executive Officers are condition 20.4 above in respect of Fees, Special unable to resolve the dispute within 10 Working Days Conditions, or the Terms and Conditions: from it being referred to them, the dispute shall be 20.5.1 the Agency will allow the Licensee 20 Working referred to the Centre for Dispute Resolution who shall Days after receipt of the Notice proposing appoint a mediator and the parties shall then submit to changes to make representations to such the mediator’s supervision of the resolution of the changes, dispute. 20.5.2 after receipt of such representations the Agency 23.5 Recourse to this dispute resolution procedure shall be shall give the Licensee 30 Working Days’ Notice binding on the parties as to submission to the mediation after the Agency has responded to the Licensee’s but not as to its outcome. Accordingly all negotiations representations prior to such variations taking connected with the dispute shall be conducted in strict effect. confidence and without prejudice to the rights of the 20.6 The Agency shall endeavour to apply the same parties in any future legal proceedings. Except for any variations as far as possible to other licensees of similar party’s right to seek interlocutory relief in the courts, no information for similar purposes. party may commence other legal proceedings under the 20.7 Variations to this agreement shall not apply to jurisdiction of the courts or any other form of arbitration Information or Derived Information already supplied by until 20 Working Days after the appointment of the the Licensee. mediator. 20.8 If the Agency updates its standard conditions for 23.6 If, with the assistance of the mediator, the parties reach comparable licensees or enters into any agreement with a settlement, such settlement shall be put in writing and, a comparable licensee on different terms and conditions once signed by a duly authorised representative of each to those in this agreement and the differences are not of the parties, shall remain binding on the parties. attributable to different circumstances, it will publish such 23.7 The parties shall bear their own legal costs of this new conditions or supply a copy thereof to the Licensee dispute resolution procedure, but the costs and and allow (but not oblige) the Licensee to terminate expenses of mediation shall be borne by the parties under condition 12 and to enter into new agreement on equally. such new terms and conditions if there is no other 23.8 Nothing in this condition shall restrict the Parties' rights change. to seek interim relief. 21. Notices and Consents 24. Rights Of Third Parties 21.1 Notices under this agreement shall be written, in English, No third parties shall have rights to enforce any part of in advance by the period specified in this agreement (or this agreement under the Contracts (Rights of Third after the event if so specified) and shall be sent to the Parties) Act 1999. address of the party as set out in this agreement (or 25. Governing Law such other address in the United Kingdom as either party This agreement shall be governed and construed in may notify to the other in accordance with this condition). accordance with English law and the parties submit to 21.2 Notices shall be marked for the attention of the contact the exclusive jurisdiction of the English courts in the identified in Schedule 4. event of a dispute.

2011

Appendix 2 - Schedule 2 of the Pan Government Agreement for Ordnance Survey information

Ordnance Survey Pan Government Agreement (Schedule 2) End User Licence

Under the terms of the Pan Government Agreement Standard Licence Agreement between the Environment Agency and the Ordnance Survey, a Schedule 2 End User Licence m ust be issued when Ordnance Survey data, and/or data containing Ordnance Survey intellectual property, is to be provided to a person or organisation (the End User) for the purposes of a specific project or activity required to deliver or support the delivery of Core Business by the Environment Agency (the End User Purpose).

This embedded pdf document is the End User Licence:

Adobe Acrobat Document

Please read and note the terms and conditions within.

The content of this Word document applies as though it were within the embedded licence.

1. Parties The Environment Agency (“Licensor”) Rio House Waterside Drive Aztec West Bristol BS32 4UD and the Licensor (as defined in the agreement above) (“End User”)

Together the “Parties”.

2. End User contact details As per Schedule 4 above

3. Supplied data Note that the information entered here relates to Schedule 2A of the embedded pdf document.

The following datasets covering the Project Area are provided to the End User, and are to be used by the End User for the End User Purpose described in this licence only.

Dataset Mark X here if data is to be provided under this licence Ordnance Survey PGA datasets 1:10,000 raster 1:25,000 colour raster 1:50,000 colour raster 1:250,000 colour raster MeridianTM 2 Miniscale® Strategi® MasterMap Topography MasterMap Integrated Transport Network MasterMap Integrated Transport Network Road Routing information MasterMap Address Layer 2 Boundary-LineTM 1:50,000 scale gazetteer

The Project Area is defined as in Schedule 3 above.

2011

4. End User Purpose details Note that the information entered here relates to Schedule 2B of the embedded pdf document.

Project/activity title: as in Schedule 2 of the agreement above. End User Purpose description: as in Schedule 2 of the agreement above. Start date: as Schedule 5 in the agreement above. End date: as Schedule 5 in the agreement above [Date the project/activity ends or 30/03/13 (whichever is soonest), when this licence will cease]. Number of End User Users: as in Schedule 3 above.

Tom Rouse Atkins Ltd Broadoak, Southgate Park Bakewell road Peterborough PE2 6YS

Email: [email protected] Telephone: 01733 366900 Direct telephone: 01733 366956 Fax: 01733 366999

© Atkins Ltd except where stated otherwise.

The Atkins logo, ‘Carbon Critical Design’ and the strapline ‘Plan Design Enable’ are trademarks of Atkins Ltd.

Corby Water Cycle Strategy Update - Corby Culvert Options Assessment

Appendix B. Meeting Minutes

Atkins Options Assessment | Version 3.0 | May 2012 15

Meeting notes

Project: Corby WCS Update Subject: Willow Brook Modelling and Mitigation Date and time: 16 Feb 2012 Meeting no: 2 Meeting place: Atkins, Peterborough Minutes by: Liz Tilbrook Present: Ian Tattersall Representing: Corby Borough Council Wayne Cattell Corby Borough Council Andra Bowyer NNJPU Rhiannon Swindale Environment Agency Clare Fravigar Environment Agency Chris Swain Environment Agency Paul Hunt Environment Agency Tom Rouse Atkins Liz Tilbrook Atkins

ITEM DESCRIPTION & ACTION RESPONSIBLE

0 Apologies Josie Bateman 1 Model results run through TR – Outlined the model results, which indicate that the greatest increase in flood risk as at the STW outfall where levels are increased between 100mm and 30mm (depending on AEP) with increase duration of flooding 15- 20mins. Elsewhere peak level increase is less. 2 Model agreement LT update report as CF – The EA agrees that the model does indeed provide a good comparison discussed. between pre and post development and that the results do not show significant changes. Although the EA still have some concern about double counting and that the model is unlikely to represent actual flood risk. IT – CBC operate with a safety factor so the conservative approach is considered acceptable. TR – Highlighted that the focus of the modelling exercise is to determine the impact of the STW outfall increase (as a result of future development within Corby). The modelling shows no inundation of properties during the 1% AEP event, even with the conservative approach and hence even though there are some increases in peak water levels, the risk to properties is not increased. PH/RS – The EA are in agreement with the model updates, although would require wording amendments to the report to reflect discussions during this meeting. In addition the report needs to make it clear that the model should only be used to compare flood risk, not to redefine flood risk along Willow Brook. 3 STW outfall levels

Next meeting: - Distribution: All present, Josie Bateman, Chris Rance Date issued: 21-02-2012 File ref: 5040250_40_DG_020

NOTE TO RECIPIENTS: These meeting notes record Atkins understanding of the meeting and intended actions arising therefrom. Your agreement that the notes form a true record of the discussion will be assumed unless adverse comments are received in writing within five days of receipt.

Meeting minutes 16-02-12.docx

ITEM DESCRIPTION & ACTION RESPONSIBLE IT – Questioned the practicality of STW discharge during flood events. Would STW still be able to discharge at the specified rate during flood events and therefore do the results actually represent the correct situation. TR – Outlined that the modelling assumes that the discharge is not restricted. At the current time it is not known whether the discharge would be restricted during flood events. However if water is restricted, the impacts on flood risk within the Willow Brook will be less than modelled results, with lower peaks, but more prolonged events. 4 Double Counting TR – As outlined earlier, the EA have some concern in relation to double counting within the model. It is suggested that to assess the impact of double counting, the model could be run with just the additional discharge resulting from development. Hence take out the current day outfall from the STW. CF – Agreed that this would be a good idea and would like to see the results of such modelling within the modelling report. TR – The results of these additional model runs and in comparison with current results could be used to define the range over which flood risk will change as a result of development. It is not known whether in reality the impact would be closer to the upper or lower bound, but the range may be small anyway. AB – Suggested that if the precautionary value is used, this may reflect flood risk impacts of development beyond 2031. 5 Mitigation IT – Outlined that the purpose of the assessment is to determine mitigation requirements and that the modelling shows low impacts so what mitigation would be required? Can it be agreed that the results do not warrant significant engineering works such as the construction of an additional culvert. RS – The EA is in agreement that significant engineering works are unlikely to be required and that instead the mitigation works could involve improving conveyance through vegetation remove or channel alignment. The culvert is not well aligned with the watercourse and therefore the works could involve changes at the downstream end of the culvert. Even though minor works are likely to be more feasible than a significant engineering scheme, all potential works should be outlined in a feasibility assessment/options report. IT – Highlighted that one potential option could involve moving the STW outfall location to downstream of the Corby Culvert and that this option should also be considered. 6 Previous WCS results EA to determine. RS – Outlined that the results indicate different mitigation works in comparison to the original WCS. The reasons for these differences need to be determined. 7 Timescales Atkins to provide The modelling report will be updated based on the outcomes of this meeting RS with updated and issued to the EA for review early w/c 20th Feb. modelling report. The draft options report to be issued w/c 5th March. Atkins to package The model files and results will be packaged and issued to CF. the model. The EA will review the updates to the modelling report and provide a response by 2nd March.

Meeting minutes 16-02-12.docx

Tom Rouse Atkins Broadoak Southgate Park Bakewell Road, Orton Southgate Peterborough PE2 6YS

[email protected]

© Atkins Ltd except where stated otherwise.

The Atkins logo, „Carbon Critical Design‟ and the strapline „Plan Design Enable‟ are trademarks of Atkins Ltd.