MINUTES OF A MEETING OF THE FLOODING AND SUSTAINABLE PLANNING TASK AND FINISH GROUP HELD ON TUESDAY 12 OCTOBER 2010 FROM 7.00PM TO 9.30PM

Present:- Tim Holfon (Chairman), Phil Challis, Norman Gould and Emma Hobbs

Also presenfr-

Gary Cowan, Execufive Member for the Environmenf Maff Davey, Head of Technical Sewices Jim Dunning, Policy Manager, Land Use and Transport Team Phiala Mehring, Loddon Valley Residenfs Associafion Eddie Napper, Drainage Manager Bryan Roberts, Environmenf Agency Angus Ross, Execufive Member for Planning Madeleine Shopland, Senior Democratic Sewices Officer Clare Williams, Environmenf Agency

1. ELECTION OF A CHAIR RESOLVED: That Tim Holton be elected Chairman of the Task and Finish Group,

2..-, APOLOGIES There were no apologies for absence

3. DECLARATIONS OF INTEREST There were no declarations of interest made.

4. PUBLIC QUESTION TIME There were no public questions

5. MEMBER QUESTION TlME There were no Member questions.

6. TERMS OF REFERENCE The Task and Finish Group considered the Terms of Reference and agreed not to make any further amendments.

7, INFORMATION GATHERING - 2001 FLOODING REVIEW The Chairman reminded Members that the next Task and Finish Group meeting would take place on November 9.

The Task and Finish Group examined the Action Plan of the 2001 Flooding review to ascertain what actions had been taken in response to the review's recommendations.

Introduce enhanced maintenance regime. In order to do this it will be necessary to seek an increase in the Council's highways revenue budget of El00,OOO per annum - Matt Davey (MD) informed the Group that this budget increase had not been forthcoming. However, he felt the maintenance regime in place for gullies and flood assets to be adequate. o Eddie Napper (EN) commented that the frequency of the cleansing regime had been changed. However, he too believed the day to day prevention regime to be adequate. Phil Challis (PC) questioned whether the budget had increased or decreased over the years. MD stated that he did not have the exact figures but that there had been an element of growth as the network had increased. PC asked that further clarification be sought. PC asked whether any of the flooding that had occurred since the previous review had been the result of flooded ditches. EN responded that very few ditches were Council-owned and that those that were not were the responsibility of the landowner. He also commented that the maintenance budget was sufficient for maintenance works. f 100,000 had been received for capital works this year. It was noted that grills were checked when storms were expected and that gullies which had been identified as being a problem were cleared twice a year. To agree the priority system and complete any minor works (which are within the Council's area of responsibility) up to £20,000 per location to reduce the risk to properties. - EN stated that previously work had been undertaken to identify areas affected by flooding and the reasons for these floods. Every property which had reported flooding problems had been investigated by the Council's consultant and mediation measures undertaken. The collated results were not in the public domain. A map identifying problem areas had also been produced. Many problems had been the result of blocked gullies and works had been undertaken. PC asked whether the Flood and Water Management Act had clarified which areas organisations were responsible for. EN indicated that the Council was now the lead authority on flooding matters in the borough and that knowledge had greatly improved since the previous review. It was noted that manholes were starting to be recorded on a mapping system and that approximately 29,000 gullies had now been mapped. PC questioned whether there were many ditches in the borough whose ownership was disputed and what powers the Council had to make landowners clear blocked ditches on their land. EN responded that the there were many disputed ditches. The Council's powers to make landowners clear the ditches were weak. The Council could only act if the water flow was impeded and the process was often long and expensive. The landowner was only required to maintain the ditch and to ensure unimpeded water flow. If someone's house flooded as a result of a ditch on a private land flooding because it had not been cleared, the home owner could take the landowner to court. It would be a civil matter. Again, the process was potentially lengthy and costly. Phiala Mehring (PM) commented that the Council should endeavour to be more proactive. It was noted that the 2001 review report had referred to 605 individual locations of flooding. 225 of these locations had been Council responsibility. Members asked that Officers indicate where these locations were and if any improvements had been made since the 2001 review. EN commented that many problem areas identified were blocked gullies and that some areas were more prone to flooding than others. A lot of the same problems arose each year. For example leaf fall and weed growth caused clogging. Emma Hobbs (EH) expressed disappointment that there had not been more progress made since the previous review. She stated that whilst clearance had increased there were still big problem areas. Develop a list of possible major Flood Alleviation Schemes and subsequently determine which schemes should be taken forward to feasibility assessment. Investigate possible external funding opportunities. -The Council had been working on such a list since the flooding of 2000. No major alleviation schemes had been identified then. EN commented that most of the major schemes had been associated with the main rivers which were the responsibility of the Environment Agency. Some grants had been received from the Environment Agency and DEFRA.

Q Ensure that the Council has due regard to PPG25 and Local Plan Policies with respect to decisions about Development on Flood Plains. - MD commented that planning applications were assessed against the Council's Flood Plans. Jim Dunning (JD) indicated that the Council received a quarterly update from the Environment Agency on flood risks in the area and that the guidelines against planning applications which were assessed was strict, particularly applications for flood zone 3. The Council could potentially be called in by Central Government if they did not follow advice from the Environment Agency. The Council was required to report back on planning applications which had been agreed against Environment Agency advice. PC asked that the Group be informed of developments approved since 2000 which had since flooded. Norman Gould (NG) stated that there were a number of gullies and ditches which ran through new housing estates in his ward which could flood. It was important that such issues were taken on board by developers. He emphasised that it was important that the Council ensured that developers did what they said that they would and also ascertained how drainage systems would be maintained in the future.

Q Draft Policy to set out Council's responses to instances of flooding and in particular over the distribution and timing of the issue of sandbags etc. Develop a Flood Plan -The sandbag distribution protocol was on the Council's website. There were mixed views on the appropriateness of sandbags for protection against flood waters. The Council had a stockpile of sandbags at its highways maintenance depot and there were distribution facilities in place. e MD stated that the Highways Maintenance Management Plan also covered the Council's response to flood incidents; where the incident had occurred, action taken and any advice given by the Environment Agency etc. The document was a working document and would be updated in the near future.

Q The 2007 floods had been largely fluvial, caused by a large slow moving cloud burst. The Council had been warned of the 2007 floods by the Environment Agency and had placed a warning on the borough alert system. The Parish Councils had been contacted and pallets of sandbags had been delivered to Charvil Parish Council, Wargrave Parish Council and Swallowfield Parish Council. The Parish Council buildings had acted as collection points for the local areas. EN stated that sandbags were of limited use and a finite resource. It was noted that Slough Borough Council did not issue sandbags and that West Council charged for their distribution and collection. o JD indicated that a Flood Risk Assessment had been carried out 2006-07 which had looked at issues including passage of water. A refresh would be undertaken in the next few months. EN, Emergency Planning and Planning would be involved. o PC stressed that it was important that a clear and open plan was communicated to residents. Members were reminded that the sandbag procedure was on the Council's website as were links to the Environment Agency's website. Information was available in a variety of formats. EH said that when she received a flood alert she emailed those in her ward whom she knew to be potentially at risk. Bryan Roberts (BR) informed the Group of the Environment Agency Flood Warning Sewice. o The Environment Agency was responsible for managing water courses but not for maintaining them. High risk areas were identified and work carried out on these areas. Enhance cross-departmental working within the Council - Previously when flooding had occurred the Highways and Emergency Planning teams had liaised. Direct would now also be involved by providing communication on what the Council could and could not provide and recording service requests. Whilst there had not been a major flooding incident since the establishment of Wokingham Direct they had successfully helped to further communication with the public during the bad weather of early 2010. Require Developers to provide adequate Flood Alleviation schemes in any relevant proposals. These can include the use of Sustainable Urban Drainage Systems (SUDS) (Balancing lagoons, swales, permeable pavements, reed beds etc) where appropriate. - Members were reminded that planning applications must fulfil the requirements of planning guidance. There was cross departmental working within the Council between Highways, Development Control and Engineering. The Council worked with developers to ascertain whether what was proposed by developers was appropriate. EN stated that under the Flood and Water Management Act there would be a requirement to establish a Sustainable Urban Drainage System (SUDS) Approval Body. These would have responsibility for the approval of proposed drainage systems in new developments and redevelopments. Begin discussions with Environment Agency to introduce local improvements in WDC's services which link to and supplement the Floodline system i.e. the central contact point for residentslpublic. - BR emphasised that a lot had been done in this area. Ensure that an adequate stockpile of sandbags is built up. These should be distributed to Town and Parish Councils (where feasible) and issued in accordance with the agreed Policy. -A protocol had been agreed. lncreaselimprove contingency planning in the event of flooding. - It was suggested that Peter Stuart, Principal Community Resilience Office would be best placed to provide an update. Identify by survey the location of all highway drains in the District - MD stated that gullies in the borough were being recorded on the Council's geographical information system. Highways drains were also being recorded. This was a lengthy process. Approximately 208km of mains sewers, 206km of main branch, 30,000 gullies (approximately 95% of the total) and 500 manholes (approximately 30% of the total) had been mapped. It was noted that the previous review had suggested that a Highways drainage survey team be created or a consultant be employed to carry out a survey. The estimated cost of this had been £40,000 per annum for 4 years. The Group were notified that this budget had not been forthcoming. Not all drainage assets were Council owned and many of the Council's drainage assets drained into assets owned by Thames Water. Non Council owned assets were also in the process of being mapped as far as possible. Members questioned what powers the Council had if a Thames Water owned drain adjourning a Council- owned drain became blocked. The Group were informed that the Council had carried out the necessary work when it had been the sewer contractor for Thames Water. This work was now carried out in house and the Council phoned to request work as per other customers. Work with ParishlTown Councils, where they are willinglable to do so, to maintain possession of sandbags at pre-acknowledged hotspots; contribute to a Flooding Emergency Plan; enhance information network. Provide feedback to residents and Town and Parish Councils representatives on findings, etc of the review through Parish Liaison Meetings and Engage TownlParish Councils (where willing and able) to assist in 'chasing up' notices served on private landowners to clear ditches and waterways with due regard to legal constraints. - EN had visited a number of parishes and asked that they mark flooding hot spots for their area on to a map. The Council was endeavouring to use Parish Councils' local knowledge. Parishes could help identify private landowners. 0 EH stressed that it was often difficult to find out who owned portions of land and that a land registry search did not always provide the answer. r PC questioned whether consideration had been given to communicating with residents via Facebook or Twitter. - There was one outstanding notice which had been served on a private landowner to clear ditches and waterways on their property. Wokingham to contribute to twice-yearly Thames Water workshops lliaison meetings between relevant agencies - BR stated that the Environment Agency was more focused on working with local authorities. It was important that neighbouring authorities worked together to tackle flooding. e Engage with Environment Agency to ensure that the flood warning status and all relevant information is provided direct to the Council -A system to ensure that information was provided had been established. 0 Enhance education for Members, and the public, raise profile of terminology, e.g. Flood Alleviation Schemes, Flood compensation scheme using internet, leaflets etc. Produce weboaaes. ., on WDC's internetl intranet. Produce Fact Sheet on Flooding - Little progress had been made with regards to this action. MD indicated that there were limited resources within the appropriate teams. The Group felt that it would be helpful if the Drainage Engineer had an assistant. EN commented that the drainage technician post had recently been vacated. A request to fill the post has been made and we are awaiting approval for this. e Produce leaflets1 literature to raise profile regarding relevant contact points in times of flooding, which organisation is including a glossary to help explain the 'terminology' associated with flooding. Include raising awareness of the role of townlparish councils, e.g. in event of them holding of road signslsandbags. Raise profileleducation of importance of holding water, where this is more beneficial than letting water flow to main river etc. Distribute leaflet to properties potentially affected by flooding and distribute via doctors surgeries and libraries. - MD stated that communication was now the responsibility of the Heads of Service. PC suggested that the Council involve voluntary groups more in the communication process. Provide double page spread in appropriate WDC News both on what action the Council has~taken- EH stressed that it was important that information was put in newsoaoers such as the Twvford Advertiser. which covered the northern oarishes to maki sire that information &as accessible tb all parts of the borough. Write to Central Government, urging increased funding to be made available for the Environment Agency to enhance protection in Wokingham. Urge Thames Water IOFWAT to direct additional resources to the prevention of flooding in Wokingham and Challenge Government on the number of houses being allocated under RPG9. Critically examine Wokingham aspects of the Berkshire Structure Plan - Gary Cowan (GC) commented that some of the southern local authorities, lead by Kent County Council, had written to Central Government asking for funding for the flooding bill. It was thought that RPG9 had been superseded by the Core Strategy.

8. INFORMATION GATHERING - ENVIRONMENT AGENCY THAMES VALLEY FLOOD PLAN 2009 This item was deferred to the Task and Finish Group's next meeting.

9. INFORMATION GATHERING - NATIONAL & LOCAL POLICY This item was deferred to the Task and Finish Group's next meeting.

10. INFORMATION GATHERING - VIEWS OF LODDON VALLEY RESIDENTS' ASSOCIATION PM provided a presentation on the views of the Loddon Valley Residents' Association. The slides of this presentation are attached as an Appendix to these minutes.

0 Loddon Valley Residents Association had been established 20 months previously in response to the increasing occurrence of flooding and the apparent lack of response. Whilst Earley and Lower Earley were mainly at risk from pluvial flooding some homes were located in flood zone 1 (lowest) and were therefore at some risk of fluvial flooding. Suggestions on how to manage this included ensure that the rivers flow is unimpeded, not developing the flood plains and removing flood storage, maintaining flood assets and flood alleviation scheme. It was appreciated that flood alleviation schemes could be expensive. The Environment Agency had indicated that the area did not meet the cost:benefit ratio for a flood alleviation scheme. In the past pluvial flooding had caused sewage problems. It was suggested that these problems could be managed to some extent by maintaining flood assets and upgrading assets when necessary. The pluvial assets in this area were owned by Wokingham Borough Council, Earley Town Council, Thames Water and Riparian ownership. In some instances ownership was in dispute. c Woodley and were subject to both fluvial and pluvial flooding, primarily fluvial. Flooding of the area along The Emm tended to be fluvial compounded by pluvial flooding. It was noted that the Environment Agency had indicated that there were a number of developments in the Emmbrook area which had increased the volume of run off which entered the watercourse. The Environment Agency provided developers with detailed guidance on managing run off rates. PM briefly discussed possible flood management options.

e The Chair asked that Members forward any questions that they had for the Environment Agency to him prior to the next meeting so that they could be sent to the representatives. He also requested that Democratic Services provide the Group with copies of the Jacobs report. Members agreed that it would be helpful to the review to speak to a representative from Thames Water and asked that they be approached with a view to providing evidence at the next Panel meeting.

$4. OPEN QUESTIONS This item was deferred to the Task and Finish Group's next meeting.

These are the Minutes of a meeting of the Flooding & Sustainable Planning Task and Finish Group

If you need help in understanding this document or if you would like a copy of if in large prinf please confacf one of our Team Support Officers. The Emm Brook and Lower Loddon

Flood Alleviation Pre-Feasibility Study

Final Report - Exec Summay

April 2010 Client: Environment Agency Project: The Emm Brook and Lower Loddon Job No: B1341000 Study Document Title: Pre-Feasibility Study

Originator Checked by Reviewed by Approved. . by DRAFT NAME NMIE 1IIIME NONE Jonathan Barnes Phil Gamey Jonathan Barnes Nigel Widgem' Elmar Torenga George Prowse Jonathan Steve Dunthorne Shakir Choudhuw Stephanie O'Gorman Barnes loanna Golemi Strive Mills Sally Kelday

DRTE SIGNATURE SICNATURE SIGNATURE UCNATURE 15th Feb 2010

L Document Status Draft Final

DRAFT lliUIE NAME N&ME NAME REVISION 1 Phil Garvey Jonathan Barnes Steve Dunthorne Jonathan Barnes

DATE SlliNATURE SIONATURE LIONI\TURE SICN&TURE 5th March 2010

Document Status

FINAL NAI.(E NAME NAME NllhVE Phil Garvey Jonathan Barnes Steve Dunthorne Jonathan Barnes

SIGNATURE SIGNATURE

11 Document Status

J~cobsEngineering U.K. Limited

E UL.:-T~.! ?as O?C~FICFSIJ oy a u i jcn, s.cs 2 ar, cr sli s:e cf .ico3r Er:~neennjlA K L mloa .'.2co~i, n a proiesr :na caps? 5 as cons. llnis n accomen:e #ul in5 terms 313 cono'ons of. acoos'coniraci ,,;.in me c3nnl rs Jr i.0 pdrty 6n2 C em). Regard rnoL o 2e hnd io m:ie !ems am ccn3:"nr .,re7 onr.oe?m s?a'or clsc-a an? rel'snlc c? ns a:cl-?e.?r lio m'i of thi a~c.mcn1 my, be co3a3 or reproduced by any means without prior writtehpermissibn fmm ~a&bs. if you have received this dac"ment in emoior ppleas ddestmy all &pies in your possession or contml and notliy Jacobs.

Any advice, opinions, oi recommendations within this document (a) should be read and relied upon only in the context of the document as a whole: (b) do not, in any way, purport to include any manner of legal advice or opinion: (c) are based upon the information made available to Jacobs at the date of this document and on current UK standards, codes, technology and constmciion practices as at !he date of this document it should be noted and it is expressly stated that no independent wiification of any of the documents or information supplied to Jacobs has been made. No liability is accepted by Jacobs far any use of this document, other than for the purposes for which it was ori~inaliyprepared and provided. Falioiving finai delivery of this document to the Client. Jacobs wili have no further obligations or duty to advise the Ciient on any matters. including development affecting the information or advice provided in !his document.

This document has been prepared for the exclusive use of the Ciient and unless otherwise agreed in writing by Jacobs, na other palty may use, make use of or rslv on the contents of this document. Should !he Ciient wish to release this document to a third party, Jacobs may, at its

or for any conflict of Jacobs' inieieits arising out of the~li;"fs reikse of this doCumant to the third party JACOBS

E.1 Introduction

In June 2009 Jacobs was commissioned by the Environment Agency to carry out the Emm Brook and Lower Loddon Flood Alleviation Pre-Feasibility Study.

Residential property flooding has occurred on the Lower Loddon during the October 2000, January 2003 and July 2007 flood events and flooding of the Loddon Bridge roundabout, Showcase Cinema complex and Winnersh Triangle Trading Estate has led to disruption to transport and industry in the area.

Flooding has also been experienced at a number of locations along the Emm Brook in 2000, 2003 and 2007. Locations affected included Sylvester Close, Emmbrook School, some properties within the residential area downstream of Barkham Road and on Finchampstead Road adjacent to the Tesco site.

The main objectives of the Loddon and Emm Brook Study were as follows: . Revise the design event hydrology (1 in 5,20, 100 and 100+20% year annual exceedance probabilities (AEPs)) for the Emm Brook and Lower Loddon catchments using the Flood Estimation Handbook (FEH) 2008 Guidelines; Update the existing IDEmm Brook hydraulic model to a 2D model; Calibrate the 20 Emm Brook hydraulic model and validate the existing 20 Lower Loddon hydraulic model using the July 2007 flood event data; e Produce new existing situation design event flood extent maps using the 2D hydraulic models and the FEH 2008 design event hydrology; e Review and reassess previously-identified flood alleviation options for both the Loddon and Emm Brook;

0 Examine new flood alleviation options including flood storage and consider the interrelationship with other sources of flooding; e Assess the effectiveness of the options using the 2D hydraulic models; Give consideration to potential environmental impacts and opportunities in our option development and selection; Provide option costs, outline drawings, and economic analysis to determine the oreferred odion: Identify potential imdrovements in flood warning systems and take-up, channel and floodplain maintenance and make recommendations; and 0 Prepare a re-~easibilit~ Final Report detailing the above objectives and findings.

E.2 Study Area Description

The rises near Basingstoke, Hampshire and flows in a north-easterly direction for approximately 45 km to join the near Wargrave in Berkshire. During its course it is joined by a number of major and minor tributaries, the most significant being the River Blackwater (which, with its tributary the River Whitewater). In total the River Loddon and its tributaries drain a catchment of approximately 1,036 km2. The Lower Loddon is part of the River Loddon catchment downstream of the confluence with the Rivers Blackwater and Whitewater, and this is shown in Figure 1.1. The Lower Loddon sub-catchment has an area of

Emm Brook and Lower Loddon Flood Alleviaiion Pre-Feasibility Study Final Repori 11-1 approximately 162km2 and a length of approximately 18km from Sheepbridge Court Farm to the A4 road bridge near Twyford.

The Emm Brook is a tributary of the Lower Loddon and rises in the rural Pinewood I Heathlands area of Wokingham District as a series of field drains and becomes the Emm Brook at Redlake Ford. From here it flows in a predominantly north-westerly direction towards Wokingham as shown in Figure 1.1. Near the confluence with the Loddon, the Emrn Brook passes under the M4 motorway and the A329 (M) motorway and through Dinton Pastures Country Park before joining the River Loddon downstream of Sandford Mill. Overall the Emm Brook and its tributaries drain a catchment area of approximately 27 km2. The length of the Emm Brook from Chapel Cross Farm to the Loddon is approximately 8 km.

E.3 Hydrology

The hydrology was revised with the Lower Loddon and Emm Brook design peak flows taken from FEH (CEH 1999 as revised by CEH 2008) and based on the estimation of an index flood and growth factors that give peak design flows when multiplied with the index flood. The design events modelled were the for the 1 in 5, 1 in 20, 1 in 100 and 1 in 100 +20%.

The results from the hydrological analysis are considered suitable for application in the Lower Loddon and Emrn Brook hydraulic models. The resulting flow hydrographs incorporate the latest statistical procedures and have been stretched to preserve the percentage runoff estimated using FEH and correspond to historic floods.

E.4 Hydraulic Modelling Calibration and Design Event Analysis

The 2D Tuflow Lower Loddon Hydraulic Model (Jacobs, 2006) was used to model the July 2007 flood event. The results of the comparison were that the flow and water levels simulated for the July 2007 event are within 2 200 mm target accuracy when compared to the observed data. This gives confidence that the hydraulic model is mimicking this high AEP historical event with reasonable accuracy for this Pre-Feasibility Study. Broadly the July 2007 flood event was the equivalent of less than 1 in 5 design event on the Blackwater at Swallowfield and a 1 in 20 on the Loddon at Sheepbridge.

The Estry IDmodel of the Emm Brook (Jacobs, 2006) was revised to a 2D Tuflow model between the upstream boundary at Chapel Green and downstream to Toutley Bridge. The Emm Brook Tuflow simulated 2007 event flood extent shows a very close comparison with the observed flood extents along the length of the Emrn Brook between Chapel Green and Toutley Bridge, again giving confidence that the Emrn Brook 2D Hydraulic model schematisation is accurate. Broadly the July 2007 flood event was the equivalent of a 1 in 100 year + 20% design event along the Emm Brook.

Flood outline maps have been produced for the 1 in 5, 1 in 20, 1 in 100 and 1 in 100 +20% design events for both the Lower Loddon and Emm Brook.

The new design event flood extents for the Lower Loddon show that in general the new Jacobs flood outlines are less than the Jacobs 2006 flood outlines, but are larger than the WSP flood outlines.

Emm Brook and Lower Loddon Flood Alleviation Pre-Feasibility Study Final Report 11-2 In conclusion the use of the FEH 2008 statistical methods to generate revised flood extents ensures that the new Jacobs flood outlines provide the best estimate for the design event flood outlines.

E.5 Hydraulic Modelling Flood Alleviation Options

The variety of flood alleviation options were identified from previous reports and new flood alleviation options were additionally investigated along the Lower Loddon and Emm Brook. A filtering process was then applied by examining these from a technically viable perspective. The hydraulic modelling simulations were carried out for some of the flood alleviation options.

The findings of the design event hydraulic modelling of the flood alleviation options was that there are four main options that are potentially practical and technically viable as follows:

Emm Brook (20 year standard of protection) o Scheme 1 On-line Flood Storage Area upstream of the A321 Finchampstead Road including: Flood walls I bunds along properties on Barkham Road and Curl Way and e Flood walls I bunds along properties along Meadow Way and Meadow Road

Lower Loddon Scheme 2 Lower Earley Flood Defence Bunds and Pumping Station; Scheme 3 Winnersh Flood Bunds and Pumping Station with A329 Road Raising and Scheme 4 Cha~ilFlood Defence Bunds and Pumping Station

Generic outline design concepts were produced to complement the shortlisted engineering options. The information and assumptions contained in the design aspects were also linked to the flood alleviation options costing.

E.6 Cost Estimates

Cost estimates have been prepared for the four schemes. Generally the engineering option for each scheme requires a bund and (apart from the Emm Brook Flood Storage Area) a pumping station to alleviate flood problems in the area. The costs are high level estimates and based on proposed design solutions and scope of works. In addition an alternative of using individual flood resistance measures for the properties identified as being at risk of flooding has been costed. This method has been costed for both the 1 in 100 +20% Standard of Protection used in the Lower Loddon engineering options and for a 1 in 20 year Standard of Protection.

The options scheme names that were assessed were as follows: Scheme 1: Emm Brook - Flood storage area; Scheme la: Emrn Brook- lndividual flood resistance (20 years); Scheme 2: Lower Earley - Bund; Scheme 2a: Lower Earley - lndividual flood resistance (100 years+20%); Scheme 3: Winnersh - Bund and A329 road raising; Scheme 3a: Winnersh - lndividual flood resistance (1 00 years+20%); Scheme 3b: Winnersh - lndividual flood resistance (20 years);

Emm Brook and Lower Loddon Flood Alleviaoon Pre-Feasibility Study Final Repod 11-3 11 Scheme 4: Chawil- Bund; Scheme 4a: Chawil- lndividual flood resistance (100 years+20%); Scheme 4b: Chawil - lndividual flood resistance (20 years). The summary of the overall cost estimates for each of the Options is shown below

Table E.l Costings Summary

Flood ~~~i~t~~~~Engineering New Option No. Option Description properties Option Costing Name at risk Costing (Ek) (fk) -- 1 in 100 year + 20% Standard of Protection On-l~neFlood storage Area upstream of the nla nla nla Scheme A321 Finchampstead Road Scheme 2 Lower Earley Flood Defence Bunds and 72 1,438 1,955 Pumping Station Scheme Winnersh Flood Bunds and Pumping Station with 117 3,030 13,640 A329 koad Raising Charvil Flood Defence Scheme 4 Bunds and Pumping. - 311 4,327 2,980 Station 1 in 20 year Standard of Protection On-line Flood storage Area upstream of the I I A321 Fincham~stead Road including o Flood walls along Scheme 1 properties on Barkham Road, TanhouseLane o Flood walls along properties along Meadow Way lndividual Flood Scheme 2 Resistance Measures at Lower Earley lndividual Flood Scheme 3 Resistance Measures at 28 407 - Winnersh lndividual Flood Scheme 4 Resistance Measures at 33 445 Cha~il Notes: Assumptions for these costs are provided in Section 6.2, and detailed in Appen

E.7 Economic Analysis

Emm Brook and Lower Loddon Flood Alleviation Pie-Feasibility Study Finai Repoii The summary of the recommendations from the economic analysis is provided below in terms of using flood resistance measures or the flood alleviation option for each of the flood locations.

For the flood resistant measures the economic analysis assumes there is 60% effectiveness along the Emm Brook. This is mainly because there is little time to get flood warnings in place due to the relative small size of the catchment and the short flood response time.

On the Loddon it is assumed there is an 80% effectiveness of flood resistant measures. This is due to the presence of upstream flow and water level gauging enabling greater warning time to be given.

Table E.2 Summary of Benefit Cost Ratios

Scheme 1 Emm Brook - Finchampstead Road Flood Storage Area

Both the engineering option and the individual flood resistance measures option give indicative benefit cost ratios exceeding 1. However, the individual flood resistance measures option has a significantly lower cost than the engineering option, for a 1 in 20 year Standard of Protection. It is also not possible to identify a technically viable engineering solution that can provide a better Standard of Protection than 1 in 20 years. It may be possible to provide a better Standard of Protection than 1 in 20 years using individual flood resistance measures.

Therefore individual flood resistance measures (Scheme la) are recommended for all properties indicated by the hydraulic model as being at risk of flooding in the Emm Brook catchment between Chapel Green and Emmbrook School.

Standard of Protection provided: 1 in 20 years

Number of Properties Protected: 48 residential and 6 business with existing Standard of Protection less than 1 in 20 years

Scheme 2 Lower Earley - Thistleton Way Bunds and Surface Water Storage Area I Pumping Station

As all the properties in Lower Earley indicated as being at risk of flooding in the Lower Loddon hydraulic model are not at risk of a 1 in 20 year flood event it is not possible to identify a technically and economically viable solution to the flood risk. The benefit cost ratio is marginally lower for the engineering solution (0.51) as

Emm Brook and Lower Loddon Flood Alleviafion Pre-Feasibility Siudy Final XepOit 11-5 opposed to the flood resistance option (0.58), but neither option is economically viable, even if climate change effects were taken into account.

If the hydraulic model is used to investigate the 1 in 50 year AEP flood and this shows a significant number of properties at risk of a flood event of this magnitude, this may lead to a revision of the calculated economic damages. Whilst modelling the 1 in 50 year design event would be unlikely to justify an engineering solution, this may result in the individual flood resistance measures option being considered cost effective.

Scheme 3 Winnersh Bunds, Surface Water Storage Area IPumping Station and Road Raising

The individual flood resistance measures options for both standards of protection give indicative benefit cost ratios of 4.77 and 6.14 for the two standards of protection considered, both well in excess of that for the engineering option (1.70) . The high level of damages associated with the business premises make up a significant proportion of the benefits and justify protection to a 1 in 100 year + 20% SOP (Scheme 3a).

Therefore the recommended option for properties at Winnersh is to provide individual flood resistance protection to each of the properties identified in the hydraulic model as being at risk of flooding up to a 1 in 100 year + 20% design flood event.

Standard of Protection provided: 1 in 100 years + 20%

Number of Properties Protected: 27 (including 6 business premises) with existing Standard of Protection less than 1 in 20 years, 80 (including 6 business premises) with existing Standard of Protection less than 1 in 100 years, and 117 (including 6 business premises) with existing Standard of Protection less than 1 in 100 Years + 20%

Scheme 4a Charvil Bunds, Surface Water Storage Areas I Pumping Stations and Road Raising

If it is desired to provide a 1 in 100 year + 20% standard of protection for the properties at risk of flooding in Cha~ilthe bunds and pumping station option is preferred (Scheme 4). However, the benefit cost ratio is marginally higher (and the Outcome Measures score marginally lower) if a 1 in 20 year standard of protection is considered acceptable, using the individual flood resistance measures option (Scheme 4b).

Standard of Protection provided: 1 in 20 years

Number of Properties Protected: 31 with existing Standard of Protection less than 1 in 20 years

Standard of Protection provided: 1 in 100 years +20%

Number of Properties Protected: 31 1 with existing Standard of Protection less 1 in 100 years +20%

imm Brook and Lower Loddon Flood Alleviation Pre-Feasibility Study Final Repori 11-6 E.8 Recommendations

It is recommended that further consideration is given to the implementation of a programme of flood resistance measures for a Standard of Protection of 1 in 20 years, or possibly better, for the following locations:

Along the Emm Brook for some 48 residential properties and 6 businesses

It is recommended that further consideration is given to the implementation of a programme of flood resistance measures for a Standard of Protection of 1 in 100 years + 20% for the following locations:

In Winnersh for some 111 residential properties and 6 businesses

It is recommended that further consideration is given to the feasibility of a bund and pumping station solution for a Standard of Protection of 1 in 100 years + 20% for the following locations:

In Charvil for some 31 1 residential properties.

An alternative option for Cha~ilis to provide individual flood resistance measures for a Standard of Protection of 1 in 20 years, protecting 31 residential properties.

Since the Chawil flood alleviation engineering options has a higher benefit cost ratio (BCR) compared to the individual flood resistant measures BCR for the 1 in 100 year +20% it is recommended this option is progressed to Project Appraisal Report stage.

The results show that no properties are flooding for the 1 in 20 year event at Lower Earley. Therefore, with little economic benefit, a similar programme was not found to be justified for this location.

It is recommended that a study be carried out at national level to determine approximate flood resistance measure costs for individual properties and that this is included in the Flood Risk Management Estimating Guide, Unit Cost Database (Environment Agency 2007) update.

The following actions are recommended in relation to hydrology: a. The Emm Brook hydrology would benefit from having a flow gauging station. A suitable location for such a gauging station would be under the railway bridge downstream of Landen Court. In addition, spot flow gaugings during the peak of severe floods at a strategic position near the Wokingham level gauge could be employed to calibrate the current hydrological and hydraulic models. b. The Swallowfield gauging station on the River Blackwater and the Sheepbridge gauging station on the River Loddon suffer from complicated flood patternsthat affect their reliability. Jacobs endorses Eden Vale's recommendation that a detailed hydraulic model covering both gauging stations can be employed to re-rate both gauging stations for high flows, potentially by extending the existing 20 model to include Swallowfield.

Emm Srook and Lower Loddon Flood Alleviation Pre-Feasibiiity Study Final Eeport 11-7 Ernm Brook and Lower Loddon Study

Prepared by John Share, EA Project Manager 30Ih arch 2010

Jacobs have now completed their Pre-feasibility report on the Emm Brook and Lower Loddon and we have summarised the main outputs and results of the study below.

1.0 Introduction

In June 2009 Jacobs were commissioned by the Environment Agency to carry out the Emm Brook and Lower Loddon Flood Alleviation Pre-Feasibility Study. The main objectives of the Loddon and Emm Brook Study were as follows:

Undertake new 2D hydraulic modelling for both the Ernm Brook and the Lower Loddon; e Produce new design flood outlines for the 1 in 5, 20, 100 and 100+20% year flood events; Calibrate both models against the July 2007 flood event data; e Review previously identified flood alleviation options for both the Loddon and Emm Brook; Examine new flood alleviation options to help flood risk; 0 Assess the effectiveness of the options proposed using the new 2D hydraulic models; Provide option costs, outline drawings, and economic analysis to determine the preferred options; e Identify potential improvements in flood warning systems and take-up, channel and floodplain maintenance and e Prepare a Pre-Feasibility Final Report detailing the above findings.

2.0 Hydraulic modelling

Broadly the July 2007 flood event was the equivalent to a :-

1 in 20 on the lower reaches of the River Loddon and 1 in 100 year + 20% design event along the Ernm Brook.

New flood outline maps have been produced for the 1 in 5, 1 in 20, 1 in 100 and 1 in 100 +20% design events for both the Lower Loddon and Ernm Brook.

3.0 Options appraisal

As part of this study a detailed options appraisal was undertaken to identify which options would be discounted and which options were to be investigated further. This summary is attached together with a plan detailing the locations.

4.0 Options considered in detail

The following options were considered in detail as part of this study. Figures for all of these options are attached.

Site El: Finchampstead Road. Wokinqham

This option proposed a flood storage area next to the Tesco's superstore and would feature a compacted earth bund with an outlet control structure to restrict the flow downstream.

The hydraulic model resuits indicate that this online storage can attenuate up to nearly a 1 in 20 year design event flood, reducing out-of-bank flood levels downstream. Beiween Barkham Road and Meadow Road we would also propose additional training bunds I flood walls up to 0.8m high to protect nearby properties to the same level of protection.

We have not been able to identify a cost-effective solution for this catchment for largerflood events simply because there is not enough storage available in the field near to Tesco's.

54 properties are defended for the 1 in 20 year flood event.

Site L3 (Option L3a): Lower Earley

This option considered providing flood defence bunds to protect properties from fluvial flooding and a pumping station to address surface water flooding. The hydraulic model indicates that whilst none of these properties are at risk of flooding during a 1 in 20 year design event flood, 34 properties are at risk of flooding during a 1 in 100 year design event flood and 72 properties are at risk from a 1 in 100 year (+ 20%) design event flood.

Site L4 (Option L4d): Winnersh

The option considered providing flood defence bunds to protect properties from fluvial flooding and a pumping station at Winnersh to address surface water flooding, together with elevation of 220m of the A329 and Loddon Bridge roundabout.

A total of 117 properties and 5 businesses are modelled as being at risk of flooding during a 1 in 100 year (+ 20%) design event flood.

However approximately 116,000 m3 of compensation storage would have to be provided. This might be available near to the proposed Hatch Farm Dairy site but this would have to be confirmed through further investigation.

Site L5: Chawil

This option considered providing flood defence bunds to protect properties from fluvial flooding and a pumping station to address surface water flooding. Hydraulic modelling indicates 31 1 properties are at risk in a 1 in 100 year (+ 20%) flood.

Whilst there is potential for this option to reduce the risk of flooding, similar to the Winnersh option a suitable area for flood compensation would have to be identified through further work.

Plans detailing all of these options are attached.

5.0 Capital Costs

Costings were based on providing the following :-

a 1 in 100 year + 20% Standard of Protection in the Lower Loddon catchment and 1 in 20 year Standard of Protection in the Emm Brook catchment.

The findings of the costings are that individual flood resistance flood walls around each of the flood prone properties is less expensive than the engineering flood alleviation options in all cases except Chawil.

6.0 Economic Analysis

The flood design events for which analysis has been carried out are 1 in 5 years, 1 in 20 years, 1 in 100 years and 1 in 100 years + 20%, the latter accounting for potential climate change effects.

The exception to this is in the Emm Brook, where modelling has shown that the maximum practically achievable Standard of Protection (SOP)is for the 1 in 20 years design event. Summary Table : Options, costings and economic analysis

Flood Engineeri Resistance ng Option Option No. Benefit Description Properties costing Benefit Option cost ratio at risk Costing (E k) (f k)

Charvil Flood Defence Bunds and

On-line Flood storage Area upstream of the A321 Finchampstead Road including Scheme I o Flood walls along properties on Emm Brook Barkham Road, Tanhouse Lane o Flood walls along propeities along Meadow Way

Scheme 2 Individual Flood Resistance Measures at Lower Eariey Lower Earley

28 4. Scheme 3 Individual Flood Resistance Measures at 2 Winnersh Winnersh businesses

Scheme 4 Individual Flood Resistance Measures at 33 Charvil Charvil 1

7.0 Sylvester Close

Some engineering works were undertaken to improve the flood risk at Sylvester Close in 2003. A range of further engineering options for reducing the flood risk at Sylvester Close were proposed from previous reports. These have been reappraised, and Wokingham Borough Council have now applied for the properties to be provided with flood resistance grants.

Having run the hydraulic model with and without the proposed flood storage area in place, for a 1 in 20 year flood event the depth of flooding at Sylvester Close is only reduced from 500mm to 390mm,

The main reasons for this is that there are substantial areas of floodplain both just upstream of Toutley Bridge and also 800m further downstream, therefore the peak of the hydrograph is reduced substantially by the time it reaches Sylvester Close. 8.0 Conclusions and way forward

This project has delivered its brief :-

0 Accurately remodelled both the Emm Brook and lower reaches of the River Loddon 0 ldentified new flood extents forthe 1 in 5, 20, 100 and 100 +20% events. Reviewed all previous options and identified new options to help reduce flood risk Provided costings and undertaken benefit cost analysis for the proposed options. ldentified potential improvements in telemetry, flood warning systems, channel and floodplain maintenance as well as environmental improvements for the options proposed. * ldentified conflicts between these proposals and future development plans in the area but also identified opportunities to combine schemes.

It is important to explain that currently for a scheme to obtain FDGiA approval a benefit cost ratio (BCR) of greater than 5 is required. This means that whilst this study has identified options for reducing flood risk along the Emm Brook and lower reaches of the River Loddon, they will not be eligible for grant in aid funding

Nevertheless, for the options appraised in this study the following will be progressed :-

Site El: Finchampstead Road. Wokinqham

The BCR for the engineering option scored low, 1.55, however by combining these proposals with the relief road proposed as part of the South Wokingham Development, the BCR could be significantly increased. We will approach the RFDC on this basis. This would also be a better use of levy funding but would significantly delay the planned construction of these proposals by at least 5 years. This option would also have to be explored further with Wokingham BC.

Site L3 (Option L3a): Lower Earlev

This option will not be progressed as neither the engineering or the flood resistance option has a positive benefit cost ratio.

Site L4 (Option L4d): Winnersh

The cost of the engineering option f13.64M to protect the 117 properties and 6 commercial units in the Winnersh area is too high to receive Levy funding. However we will approach RFDC to gauge their willingness to fund the f3M for the flood resistance measures.

Site L5: Charvil

Whilst this option scored the highest BCR out of all the engineering options, a suitable location has not yet been identified for the flood compensation. Further consideration would have to be given to this issue before we have certainty that it is worth progressing.

For any further information please contact Doug Hill (01276 454513) who is the Asset System Management Team Leader for this area.