Flood Forum for residents

17th May 2017

Agenda6.30 Panel Event in Committee Room 5:

1. Welcome by Councillor Jonathan Bianco2. Terms of Reference and Agenda for the Evening3. Introducing the Panel4. Question Time5. Summing Up

7.00 Drop-in Session in Committee Room 6

In attendance, will be representatives from :

Affinity Water, Thames Water

Environment Agency

Flood Protection Company

London Fire Brigade

Council Officers working in: Emergency Response, Green Spaces, Highways and Flood and Water Management.

9.00 Session Ends

IntroductionChair: Councillor Jonathan Bianco,

Cabinet Member for Finance, Property and Business Services and Portfolio Holder for Flooding and Water Management.

Housekeeping - Fire Drills, Exits, Tea and Coffee provided at the back of this room

Sign in and Terms of Reference

● Officers have drawn together 10 questions from over 60 received, which broadly:○ Represent concerns from residents across the Borough, and represent a number of similar questions○ Do not lead to duplication nor require answers from an officer or organisation not represented on the Panel.○ Cllr Bianco will pose the question to the Panel on behalf of residents.○ There will be no follow up questions during the Q&A panel session, but attendees are asked to raise these in the

1 to 1 conversations taking place afterwards at the drop-in surgery.

● Government guidance for events held in Purdah○ There are some limits to the questions that can be answered in order that we could continue with this event. ○ The Council have written to candidates to be MP’s to ask them not to attend○ The Environment Agency cannot answer any questions about funding, work that requires extra funding or

Environment Agency resources in general.

Thursday 23 June 2016“Referendum Day”Heavy rainfall fell, from 5pm until 6pm resulting in immediate ponding on roads, and an overwhelming of gullies and sewers. Then, and through the evening, rivers burst their banks.

Impact was widespread across the (mainly) north of the borough, at this point 82 properties and commercial premises flooded internally in over 43 locations and strategic infrastructure affected, as well as hundreds of roads.

The Council thanks all those residents who have also contributed to allow a clearer understanding of the impact. The Council has also collated information across internal departments and made requests of external bodies.

The Flood Investigation is still in draft form and this event will go through what happened and help feed into the final version to be published in June.

This process has identified some action already taken and the priorities to invest future resources on.

Introducing the Panel● Environment Agency - Lee James - Flood and Coastal Risk Management Team

Leader● Affinity - Patrick Campbell - Network Asset Strategy Manager● Thames Water - Graeme Kasselman North London Infrastructure Planning

Manager and Anne Christie Area Performance Manager● London Borough of Hillingdon

○ Chris Mansfield- Deputy Director Planning, Transportation & Community Projects

○ Highways Service - Dalton Cenac - Highways Maintenance Manager○ Emergency Management - Mark Wolski - Emergency Manager○ Green Spaces - Stuart Hunt - Green Spaces Service Manager○ Planning Specialists - Vicky Boorman - Flood and Water Management Officer

Question 1 Roles and Responsibilities

“Following the flooding in Ruislip in June 2016, residents sought answers to questions mainly around which agency or organisation has specific responsibility for mitigation measures that ought to have been or should now be in place. To an extent they have been given conflicting or contrasting information and the impression has been given to both Residents and Cllrs that no one agency with capability is taking Responsibility. Please give a definitive answer to this with details of who is to be contacted”.

Cllr John Riley, asking on behalf of residents in his ward

Answers from:

1. Environment Agency - Flood and Coastal Risk Management Team Leader- Lee James2. London Borough of Hillingdon - Flood and Water Management Officer - Vicky Boorman3. Thames Water - Graeme Kasselman North London Infrastructure Planning Manager

1 Environment Agency response:The Environment Agency supervises and works with other organisations to manage the risk of flooding in England. We have a number of responsibilities relating to the management of flood risk on main rivers. We provide and operate flood warning systems, have powers to undertake maintenance and other works to manage flood risk on main rivers, issue permits for works on or near main rivers and advise planning authorities on the implications of development proposals on flood risk.

Our powers in relation to main rivers allow us to do work to manage flood risk. However, this does not mean that we have to maintain or construct new works. We have to prioritise our work based on risk.

See next slide for responses from LBH and Thames Water

Question 1 Roles and Responsibilities

2 London Borough of Hillingdon Flood and Water Management Officer:The Flood and Water Management Act 2010 introduced new responsibilities to different bodies in order to help try and clarify who was responsible for different issues.

LBH in its role as Lead Local Flood Authority was given the lead for managing flooding from surface water, groundwater and from ordinary watercourses. It is also required to investigate those sources of flood risk.

However there are still lots of organisations involved who have different responsibilities in managing parts of the drainage system.It is often not clear initially during an event who is the responsible party, and you may have to report issues to a number of organisations as they are all responsible for different parts of the drainage system. Ie the Council the gullies, Thames Water the sewers and landowners the rivers. It was clear that water had come out of the culvert underneath Parkwood and Broadwood avenue.Based on information that Thames Water had provided to residents and the Council, Thames Water had acknowledged responsibility the culvert underneath Broadwood and Park Avenue. Therefore in addition to reporting it to the Council, residents were encouraged to report it to Thames Water.

It takes time to collate the information, and following receiving reports the Council in October interviewed a number of residents to establish what had happened and to whom and at what times.

3 Thames Water:Water and Sewerage Companies (WASC) are the statutory undertakers for public sewers.

We are therefore involved in all aspects of flow entering and exiting these systems.

We do not have a legal responsibility for sewer flooding as there are too many factors outside of our control that can cause flooding.

We request all of our customers to contact us when they experience sewer flooding. That gives us the opportunity to better understand why the flooding occurred and depending on those findings implement various different interventions that may reduce or removal the risk of flooding. It also allows us to keep a register of sewer flooding which drives our flood alleviation capital investment programme.

Our surface water influence is for rainfall that lands on buildings and associated hard standings that connects into the public surface water sewer.We hold no influence over highway flooding even if the highway gullies connect into the public sewer and the sewer is full which prevents them from draining the highway. Flow exiting the public sewer and entering the highway does concern us.Similarly we are not responsible for land drainage (i.e. rainfall that does not land on buildings).

Question 2 Emergency Response

“In view of residents' experience on 23rd June 2016 of difficulty in getting through to the Council and no practical advice being available, could the Council's Emergency Management and Response Team and other agencies please review their response arrangements to ensure more practical advice and assistance can be given when future major flooding events occur?”

Martin White (Friends of Pinn Meadows)

Answers from:

1. London Borough of Hillingdon - Emergency Response Manager - Mark Wolski2. Environment Agency - Flood and Coastal Risk Management Team Leader- Lee James

Useful Links https://www.gov.uk/sign-up-for-flood-warnings

Floodline on 0345 9881188.

1 London Borough of Hillingdon Emergency Response Manager: ● Specific flooding advice is always available on the Council web pages. This

provides detailed information on how to protect your home, how to plan for a flood and includes crucial advice on protecting you and your family, key steps to make your property safe and advice on driving do’s and dont’s. Go on to the website and search ‘flooding’

● If you are at risk of flooding, this advice must be considered in advance to be effective.

● We will be looking to identify main hotspots and to work on ways to get information across other than by using the internet.

● We acknowledge that when residents tried to contact the Council in the flood event that they not all were able to get through to speak to someone. We are conducting a review to determine how best to escalate internal Service capabilities ready to deal with an incident.

● The Council does not have the capability to perform key roles on the night which are the responsibility of the Emergency Services (such as pumping water from flooded properties) Highways will comment tonight on their capabilities regarding flooding.

● We will be engaging with the emergency services to improve planning and coordination when responding to calls during flood situations.

● Flood management will be providing further advice tonight in leaflets and by

● the attendance of a company providing flood prevention products● We are looking to enhance LBH coordination both in-hours and out of hours,

including the updating of Communications messages

2 Environment Agency response:The Environment Agency provides and operates a free flood warning system for main rivers where it is possible to provide this service. You can sign up for warnings on our website: https://www.gov.uk/sign-up-for-flood-warnings or by calling Floodline on 0345 9881188.

On our website, there is also information about how to prepare for flooding, where to go for help during a flood and what to do after a flood:

https://www.gov.uk/prepare-for-floodinghttps://www.gov.uk/help-during-floodhttps://www.gov.uk/after-flood

Reports of flooding or blockages in rivers should be made to our 24/7 incident reporting line on 0800 80 70 60. We have officers on standby 24/7 to assess and attend reports of blockages in main rivers. We also carry out practice clearance of specific river control structures and hotspots prior to forecasted heavy rainfall events.

We have a network of remote telemetered river level monitoring sites that send instantaneous river level readings to our duty officers. We know the level a river has to get to for it to start causing flooding and we use these levels to trigger the issuing of Flood Alerts and Warnings. Since the flooding in June 2016, we have reviewed our flood warning trigger levels and in some cases, have lowered them so warnings are issued sooner, but not too soon so as to cause a false alarm. We have also increased our maintenance frequency along the River Pinn to 3 times per year. Parts of the catchment are also visited on a monthly basis where field teams walk the channel and remove any debris larger than a football, which could pose a flood risk. We are happy to support residents groups who want to understand their local flood risk and what to do before, during and after a flood event. Many communities choose to create a community or personal flood plan and we are happy to support with these.

Question 3 Emergency response“1) Why did we not get emergency AID during flooding on 23rd June 2016 2) We contacted all authorities during this difficult time and each of them were passing the buck to each other, and offering no help 3) Highways need to clean road gullies frequently. Surface water caused major flooding, then river water.4) In our area, the River Pinn needs a good clean up but no authority is paying any attention to this, passing the buck to each other, without any good out come”

Mr N Kotecha (Westcote Rise, Ruislip)

Answers from:

1. London Borough of Hillingdon - Highways Service - Dalton Cenac2. London Borough of Hillingdon - Flood and Water Management Officer - Vicky Boorman3. Thames Water - Graeme Kasselman North London Infrastructure Planning Manager4. Environment Agency - Flood and Coastal Risk Management Team Leader- Lee James

Useful link https://www.gov.uk/government/publications/riverside-ownership-rights-and-responsibilities

1 London Borough of Hillingdon Highways Service Maintenance Manager response:

Introduction to Highways Maintenance roles & responsibilitiesResponsible for

● 32,100 road gullies - A Roads 3200 / B, C & Residential 28900● Pipework up to sewer only● Various ordinary watercourses● 27No trash screens

Cyclical gully cleansing works outsourced to new service provider from 3rd April.New approved cyclical programme for every road in the borough (can see individual roads at Drop-In session)Frequency of cleanses?

A-Roads - twice a yearB,C & Unclassified/Residential roads - once per year

Ad-hoc cleanses on request etcImprovements to gully service from 2017/18

400 Critical gullies in locations that require more frequent cleansing (including Westcote Rise) to be cleansed four times per annum.Asset condition data recorded by new service provider

CCTV Surveys to be undertaken where appropriateRolling programme of defective gullies, gratings, broken pipes, tree root damage prepared and prioritised for repair based on asset condition/CCTV results.

2 London Borough of Hillingdon Flood and Water Management Officer:

We have described some of the roles and responsibilities and why this leads to some confusion in other answers.

The information on what has been reported is found in the Flood Investigation. This does not include all the details that may have been collated in the course of an investigation in recognition of residents concerns about blight on their properties. However all of this information helps inform what the priorities for the council and next steps.

A simple report is to be used in future which will be available online for residents to report incidents after the event. All information collected by the Council has been shared during the collation of the investigation report with Thames Water, and partners were provided with a draft of the report to comment on before draft publication for residents.

The Council are also working closely with Thames Water to try and find ways of sharing information more easily in future, and changes have been made to their sewer flooding questionnaire so that residents can allow information to be sent to Local authorities.

This has been raised by the Council with national government and it is recognised as a national issue, so Government Cabinet Office are working on ways that all emergency responders can collect and provide information in a consistent and accessible way.

2 Thames Water response:

We have staff that respond to flooding incidents at the time they occur. 23 June 2016 was an exceptional day and our resources were stretched beyond their capacity. Flooding in the east of London was much more severe than in the west of London.

Thames Water responded to calls made on the day of the event . We distributed our available resources based on the best information at the time to support as many customers as we could. In such high intensity rainfall events that our sewer systems are not designed to accommodate there is very little that we can do.

3 Environment Agency response:

The Environment Agency have permissive powers to undertake maintenance and capital works to manage flood risk on main rivers. On the River Pinn we remove blockages and cut overhanging branches 3 times per year.

Our powers in relation to main rivers allow us to do work to manage flood risk. However, this does not mean that we have to maintain or construct new works. We have to prioritise our work based on risk.

Everyone who owns land adjoining, above or with a watercourse running through it, has certain rights and responsibilities. In legal terms you are a ‘riparian owner’. Rights and responsibilities of riparian landowners have been established in common law for many years. Our ‘living on the edge’ guidance sets out the rights and responsibilities of riverside landowners: https://www.gov.uk/government/publications/riverside-ownership-rights-and-responsibilities

You may need permission for some activities from a third party, such as your local council or the Environment Agency.

Question 4 Planning

“Why are developers/builders allowed to build (continually) on land that is at flood risk or has a history of flooding, with areas of the ground at a lower level and/or sloping downwards - without being held responsible for strict appropriate stringent and 'fit for purpose' measures to protect new properties on such land. The NHBC, Thames Water and Council do not protect owners currently”.

Suzanne Stein

Answers from:

1. London Borough of Hillingdon - Flood and Water Management Officer - Vicky Boorman2. Environment Agency - Flood and Coastal Risk Management Team Leader- Lee James

1 London Borough of Hillingdon Flood and Water Management Officer:

The Local Planning Authority provide comments on planning applications on both fluvial and surface water flood risk. This is to ensure that risk is adequately identified and managed and that no unsuitable development is permitted.

Fluvial Flood RiskLand across the Borough is categorised into Flood Zones (1, 2 & 3).

● The majority of land in Hillingdon is in Flood Zone 1 (less than 0.1% chance of flooding in any one year)

● Development in Flood Zone 2 (between 0.1-1% chance of flooding in any one year) is required to submit a site specific FRA to determine the risk to and from the development and how that risk will be managed. Development resulting in new dwelling(s) is unlikely as this will have to pass the Sequential Test. The Sequential Test aims to steer new development to areas less likely to flood

● Flood Zone 3a (greater than 1% chance of flooding in any one year) - an FRA is required. New development is unlikely as the Sequential test needs to be passed

● Flood Zone 3b (functional floodplain - where water has to flow or be stored in times of flood) - No development is permitted other than ‘water compatible’ or ‘essential infrastructure’

However that government allows the redevelopment of an existing building at risk of flooding, and limited expansion as long as it take into account the flood risk and put in appropriate measures to protect it and prevent it increasing flood risk to government standards.

Sustainable Drainage● Sustainable Drainage is a material planning consideration for all major

developments (10+ properties). SuDS need to be included as part of these developments in order to manage surface water on site and reduce runoff. The Council also have stricter requirements than many other local authorities, Asking developers even where it is an existing developed site to mimic the drainage of a site as if it is a green field. Developers are required to follow the SuDS hierarchy of options in the London Plan with the most sustainable option being more preferable.

● In addition to this at this council, Minor developments at risk of surface water flooding according to the EA Flood Maps or located in Critical Drainage Areas as identified Surface Water Management Plan (SWMP) are required to include sustainable drainage methods to manage surface water on site thus reducing the pressure on main sewers.

● In addition front gardens that are now converted into front drives must comply with legislation which means they must be permeable or direct water to a permeable area - not just connecting to a pipe which ultimately runs into the road. The Council have enforced the remediation of these where they have been reported. More information can be found on a handout please share with your neighbours to encourage them.

2 Environment Agency response:

● The Environment Agency are a statutory consultee on some planning applications.

● Part of our role is to provide advice on technical flood risk issues and interpretation of flood risk-related policy to local council planners, developers, flood risk consultants and other relevant parties.

● https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications

Question 5 Flood Maps

“Maps indicating the vulnerability of properties to serious flooding have changed significantly since last June. What are the specific causes of such changes, how have they been or will they be reversed, when and by whom?”

Adrian Ingham (Park Avenue, Ruislip)

Answers from:

1. Environment Agency - Flood and Coastal Risk Management Team Leader- Lee James2. London Borough of Hillingdon - Flood and Water Management Officer - Vicky Boorman

Next two slides show examples of maps

Question 5 Flood Maps

Environment Agency Flood Maps https://flood-warning-information.service.gov.uk/long-term-flood-risk

1 Environment Agency

The Environment Agency provides flood risk maps on our website that detail the risk from main rivers, surface water and reservoirs. The information on which the maps are based are mainly from observed actual flooding incidents and predicted flood extents calculated from computer models. Maps tend to only be updated when new information is available. The last large-scale update of the Pinn catchment was published in January 2016.

A further update will be published later this year to correct an error in a very localised area which will reduce the mapped extent of flood risk. As a result, 7 properties will no longer be classed as at risk of flooding from the river. The flood map for surface water has not changed for several years and there are currently no plans to update this. Further mapping or changes to the surface water flood risk is the responsibility of Lead Local Flood Authorities.

https://flood-warning-information.service.gov.uk/long-term-flood-risk

Question 5 Flood Maps

London Borough of Hillingdon Maps http://www.hillingdon.gov.uk/article/28579/Rivers-ditches-and-canals

2 London Borough of Hillingdon Flood and Water Management Officer

LBH has published a Borough wide ‘Flood and water information map’. This provides an overview of the flood risk in the Borough and displays;

● Location of rivers and ordinary watercourses ● Thames Water outfalls● Flood risk from rivers - Flood Zones 2, 3a & 3b● Areas at risk from surface water flooding● Critical drainage areas● The map can be found by navigating the Council website

http://www.hillingdon.gov.uk > Residents > Environmental issues > Rivers, ditches, canals, > Flood and water information map

http://www.hillingdon.gov.uk/article/28579/Rivers-ditches-and-canals

The surface water maps produced by the Environment Agency have been confirmed by the Flood Investigation to be a good reflection of those areas likely to be at risk from heavy rainfall.As the Council develops projects, part of the project would be to assess the impact and produce modelling work of a standard that can be used to alter any flood risk mapping. This significantly increase the costs of any project.The London Borough of Hillingdon has not made any amendments or changes to the

surface water map shown on the EA website.However as large projects are taken forward to reduce flood risk and modelling can be undertaken, the Council will submit amendments to flood modelling

Question 6 Maintenance

“I should like to ask a representative from the Environment Agency why they published their 2016 Maintenance Schedule for watercourses, including Cannon Brook, but now appear to be telling residents that this is their responsibility”.

Mrs Susan Midgley (Howletts Lane, Ruislip)

Answers from:

1. Environment Agency - Flood and Coastal Risk Management Team Leader- Lee James

Useful link https://www.gov.uk/government/publications/riverside-ownership-rights-and-responsibilities.

1 Environment Agency response:

The Environment Agency have permissive powers to undertake maintenance and capital works to manage flood risk on main rivers. Along the Cannon Brook our field teams now walk the channel on a monthly basis and remove any debris larger than a football which is likely to pose a flood risk. We also respond to reports from residents of blockages during flooding incidents and will remove large objects from the channel that may cause an immediate flood risk.

Everyone who owns land adjoining, above or with a watercourse running through it, has certain rights and responsibilities. In legal terms you are a ‘riparian owner’. Rights and responsibilities of riparian landowners have been established in common law for many years. Our ‘living on the edge’ guidance sets out the rights and responsibilities of riverside landowners: https://www.gov.uk/government/publications/riverside-ownership-rights-and-responsibilities.

Essentially riparian owners are responsible for maintaining their section of the watercourse.You may need permission for some activities from a third party, such as your local council or the Environment Agency.

Question 7 Highways Gullies“Four houses in Evelyn Avenue Ruislip flooded because the single gulley outside No 141 could not cope with the rainwater which accumulated within 30 minutes of the start of the severe rainfall. This one gulley is at the lowest part of the whole of Evelyn Avenue. The next gulley is 40.25 metres down the road, and 14.5 cm higher, and it took virtually no rainwater.

Water 12.5 cm deep outside No 141 will cross the pavement and flood the houses. Cars driving down the road through the water caused flooding well before this depth of water was reached. Now the road has been resurfaced, the lowest height of the camber in the road, is 14.2cm higher than this gully. Some of the camber is 17cm higher. As a result the gulley on the opposite side of the road does not take any of the water that flows down to the lowest point outside No 141 and which accumulates there.

Please would you explain why the Council has decided not to install 2 more gulleys in this low section of road, which would alleviate this specific problem and help prevent flooding again?FYI Over 7” of water flooded our houses. It was over 8 months before the damage was repaired and my wife and I could return to our house of bare plaster and concrete floors.

Adrian Neilson (Evelyn Avenue, Ruislip)

Answers from:

1. London Borough of Hillingdon - Highways Maintenance Service - Dalton Cenac

1 London Borough of Hillingdon Highways Service Manager Dalton Cenac See next two slides for information

Question 7

1 London Borough of Hillingdon Highways Service Manager Dalton Cenac

Roads designed to disperse water to gullies (and sewer) as quickly as possible based on basic parameters of the following:

2 yr return period / 1 gully per 200m2 of carriageway / adequate camber and longitudinal gradient between gullies.

Based on these parameters there are sufficient gullies at appropriate spacings (Slide 1 of 2)"Lowest point o/s No 141" "new gully required etc"

Accepted that resurfacing has removed water check/upstand to crossover o/s 139/141 which may cause water to accumulate (not necessarily a low point)

Works order raised to provide upstand/water checkLevel survey to be undertaken to check longitudinal/crossfalls and low points.

This will determine whether reprofiling of surface is required or gully to eliminate low spot/ponding issues.

Question 7

1 London Borough of Hillingdon Highways Service Manager Dalton Cenac

23 June extreme event - Quarter June average 47mm in 1 hr etcFlooding is result of complex interaction of various sources – Rivers/Sewers/GulliesEvelyn Avenue/Brook Drive – drainage system overwhelmed whereby TW sewer surcharged and could not discharge into River Pinn; gullies backed up and water on road could not flow away etcNo T/W sewer in this section of Evelyn Avenue (Slide2 of 2)CCTV surveys to determine layout, connections, condition, size of highway pipework.To include Brook Drive and T/W sewer (with permission of T/W)Options to reduce the incidence of flooding to be developed following results of CCTV surveys and dialogue with both TW & EA who are also investigating solutions. In interim gullies in Evelyn Avenue & Brook Drive to be cleansed 4-times per annum (critical gullies)

Question 8 Flood Alleviation SchemesWhat measures have been/will be put in place to ensure Brook Drive does not flood in the future:

Hillingdon council/Green Spaces - what preventative measures will be put in place to stop the River Pinn from breaching.

Thames Water-what measures are in place to monitor the sewer in brook drive to locate and remove blockages before flooding occurs (the sewer blockage in place at the time of the flood was discovered only after persistent calls from residents after the flooding had occurred ). What will be done to widen the sewer at the point of the belly (dip in the sewer) along Brook Drive which increases the risk of blockages and slows the rate of water drainage in heavy rain. Are the sewers wide enough to take away surface water? How often will the sewer be checked?

Environment Agency - what plans are in place to defend our properties from the River Pinn breaching its banks in the future. Please provide details of investigations into the drainage system for the local area in which all the sewers drain through Brook Drive, therefore putting us at risk of future flooding. What can be done to re route the drainage system so that Brook Drive is not overloaded.How have all of the services above (LBH/Thames Water/EA) worked collaboratively to plan for a shared approach to preventing flooding from taking place.

Claire Pitt (Brook Drive, Ruislip)

Answers from:

1. London Borough of Hillingdon - Green Spaces 2. Thames Water - Anne Christie 3. Environment Agency - Flood and Coastal Risk Management Team Leader- Lee James

1 London Borough of Hillingdon Green Spaces:

There are existing measures that were put in place where the banks were raised to hold water in the river for longer. These were put in by the Environment Agency. These delay the speed at which the river spills out of bank.However In June, the surface water drainage system which flows into the river was submerged and therefore water could not drain away. This meant water built up in the sewers and then the gullies and on the roads.

The Council have been working with the Environment Agency for the last few years on the River Pinn Project, and will continue to provide feedback on behalf of residents.

Further information on the works that the Highways department and the investigations scheduled have been provided in response to question 7.

2 Thames Water response:

We have cleaned sections of the sewer in Evelyn Avenue relating to silt build up in our asset along with planned maintenance of cleaning between our asset and the outfall on Brook Drive on a yearly basis.Regarding the point of belly in the Foul Water Line, which is actually on the S24 for no.19 (not the Main Sewer in Brook Drive), we have works at planning stage to

replace 10.5mtrs. Evidence suggests that this was caused by subsidence, which the house owner confirms they have had historical issues for which their house is underpinned.

3 Environment Agency response:

We are currently developing a flood alleviation scheme to address flood risk across the whole of the River Pinn catchment. This will include investigating options to reduce the risk in the Ruislip area.

We have now completed the first stage of the project, which used a computer model to more accurately map the extent of current potential flooding from the river under different rainfall scenarios. We will use this information to look in more detail at potential options for reducing flood risk from the watercourse. We will also consider the impacts from surface water. This type of flooding occurs when roadside drains or natural drainage into the ground become unable to cope with the amount of water. This is a particular problem during periods of heavy rain and thunderstorms.

Hillingdon Council are the Lead Local Flood Authority in your local area and are responsible for investigating and managing surface water flooding. We will work with Hillingdon as we develop our flood alleviation scheme project and we are committed to ensure flood risk from all sources, not just the river, is taken into account.

Moving from a proposal to reduce flood risk to actually doing work on the ground can take a long time as we need to be sure the proposed measures are the most effective. The risk of flooding from the River Pinn therefore remains the same at the current time.

Question 9 Flood Alleviation Schemes

“What steps are the Council (and landowner of Park Wood) taking to reduce / eliminate the flood risk from Park Wood to Broadwood & Park Avenues”.

Lucas Whittaker ( Broadwood Avenue, Ruislip)

Please note the Council has received a petition from residents of Park Wood and Broadwood Avenue covering a range of issues, which the Council will respond to through the Forum, and subsequent engagement.

Lead petitioner Mr Heneker

Answers from:

1. Environment Agency - Flood and Coastal Risk Management Team Leader- Lee James2. London Borough of Hillingdon - Green Spaces Management of Park Woods - Stuart Hunt3. Affinity - Network Asset Strategy Manager - Patrick Campbell

1 Environment Agency reponse:

We are currently developing a flood alleviation scheme to address flood risk across the whole of the River Pinn catchment. This will include investigating options to reduce the risk in the Ruislip area.

As part of our project we are committed to working with Hillingdon Council to make sure we take into account any work they are undertaking in the short term in Park Wood. We will provide advice and guidance to Hillingdon Council to support them with their bid for funding to undertake natural flood management work in the woods.

2 London Borough of Hillingdon Green Spaces:

The Council has done some work in Park Wood already with the aim of holding more water back during storm events.

● A meeting was arranged to take on board some suggestion by residents● As a result a pond has been cleared out, the ditch entering the pond has also

been cleared both of which will allow for more water to be stored here● A ditch on the eastern end of Broadwood avenue has been cleared of debris

and obstructions● A debris screen that was found to have become dislodge was put back in

place upstream of the culvert entrance near the back of the properties on Broadwood Ave. This will catch and stop larger debris from flowing towards

● the culvert entrance. This screen will not be cleared as the buildup of debris will help in slowing the flow of water during times of heavy flow

● A screen at the entrance of the culvert underneath broadwood and parkwood avenue was replaced.

● In addition to the clearance work suggested, the council followed a some new principles introduced recently called “natural flood management” techniques have been installed along on the stream from the pond to the culvert entrance to slow the flow. Logs have been placed across the stream at various points and staked in place. This is known as ‘large woody debris’ and will act by naturally gathering smaller sticks and leaves creating a permeable surface allowing water to get through. These will reduce the flow of water in the watercourse during times of high flow, pushing water onto the banks in the process

● These were limited as the park is a SSSI and works have to be undertaken in agreement with natural england and changes to the ancient woodland monitored.

● The EA have visited Park Wood and agree with the principle of natural flood management and have made some suggestions where improvements could be made.

● The Council has met with Thames 21 and Brunel University and will work in conjunction to develop these methods further. An application for funding natural flood management work in Park Wood has been made to DEFRA

● The Council arranged for Affinity to come out on site in Park Woods to help them understand the area and issues, and asked Affinity to provide feedback on their plans to reduce the risk of Pipe burst.

Please also see handout for further information

3 Affinity response:

● This 18” cast iron main was laid in 1948 and is gravity fed from Oxhey reservoir in Northwood. It is used to feed an area west of Park Wood in Ruislip of more than 2600 properties by carrying over 1 million litres of water per day.

● Following the failures of the main we are now going to carry out a detailed condition and leakage assessment to determine the extent of corrosion and remaining life of the pipe. We plan to carry out this assessment during early autumn once all permissions are received on working in the wood (see the section on Condition Assessment). The outcome of the assessment will be the decision on whether to replace the pipe in our next investment cycle (2020-2025). Repeated bursts may however mean that could bring forward our plans.

● Park Wood is classified as a National Nature Reserve (NNR) as well as a Site

● of Special Scientific Interest (SSSI). We will take special care to mitigate any environmental impact that our works will have on the wood and will work with all interested parties to make sure this is achieved.

● Further information can be found in their handout provided.

Question 10 Flood

“I would like the Council to pay for our Flood Doors in the event of us being flooded again. The cost is £7,000, a small sum when calculated how much it has cost us and Insurance Companies. This should be for all Properties in a Flood Risk Area” David and Kim Baker, Ruislip

Answers from:

1. London Borough of Hillingdon - Chris Mansfield - Deputy Director Planning, Transportation & Community Projects

Useful Link: http://www.bluepages.org.uk/

1 London Borough of Hillingdon Deputy Director Planning, Transportation & Community Projects

● There are potentially over 35,000 people at risk from different sources of flooding, that may be affected in an extreme event. ( Flood Risk Management Strategy/ Surface Water Management Plan)

● The Council is one of many bodies with responsibilities for aspects of flooding.● Council cannot afford to provide funding for all those properties. Particularly

where the same product may not be suitable for all properties, so each property would have to be looked at in detail to understand what would be suitable.

● The Council have arranged for a company to showcase the types of flood products that are available to residents to use and buy and to provide advice at the Flood Forum.

● The government provided a scheme a few years ago, where residents who were affected were allowed to apply for a grant to put in these flood products.However they have not made that grant available for this event or for all

events.

Summary● THANK YOU for attending, and contributions.● Key information from the event, will be sent to all those interested.● Handouts which include the useful links.● The Flood Investigation is still in draft. Please provide comments by the

31st May online where possible. ● All points of clarification and information where suitable will be

incorporated within the final Flood Investigation report released in June.● Actions from the Flood Investigation ● NEXT DROP IN SESSION

○ Next door in Committee Room 6 ○ Layout and organisations attending information

THANK YOU TO ALL THOSE ORGANISATIONS on the PanelAND RESIDENTS for contributions at the forum and for all the information provided for the Flood Investigation

Key next steps include:1. Publication of the updated preliminary Flood Risk Assessment maps showing

incidents of flooding.2. Review of the key Critical drainage areas informed by this report3. Emergency Response review4. River Pinn Flood Alleviation Project led by the Environment Agency5. Park Woods Natural Flood Management led by the Council6. Further Highways Investigations Planned