The River Pinn Project information page

Closes 1 Oct 2019

Opened 10 Oct 2018

Overview

Updated January 2019

The River Pinn catchment is in the west of the Greater London area. It flows through the London Boroughs of Harrow and Hillingdon before joining the Frays River in Uxbridge. The Pinn is joined by several smaller rivers along its length, including the Cannon Brook in Ruislip. It is also fed by numerous drainage outfalls which carry rainwater to the river. Generally the water flows in open earth channels, regularly passing through various bridges and culverts.

Communities in the River Pinn catchment have experienced flooding several times, most recently in June 2016. We have been working with Hillingdon and Harrow Councils as well as Thames Water to better understand the causes of this flooding and identify actions that could reduce the risk in the future.

How you can help us:

  • champion the project locally
  • help us identify additional sources of funding
  • tell us how you have been impacted by the River Pinn flooding
  • tell us about your local knowledge of the environment and flooding.

Project Objectives

  • Better understanding of the risk of flooding in the River Pinn and Cannon Brook catchments;
  • Collaborate with others to develop flood reduction proposals which maximise benefits for people and the environment;
  • Work with local communities to ensure they understand our proposals and what actions they can take to be more prepared for flooding;
  • Work with our partners to secure additional funding from other sources to help us deliver viable projects.

Please understand that our proposals will not eliminate the risk of flooding altogether, only reduce it.

Working with communities

During March 2018 over 180 people attended three public drop-in sessions in Ruislip, Pinner and Uxbridge. This was an opportunity for the public and other local stakeholders to look at our proposals for the River Pinn projects and discuss them with our colleagues and specialists. It also provided an opportunity for the public to tell us how flooding has impacted them in the past.

   

Our  public consultation was available online for 6 weeks. We received over 120 responses from the public on our project plans. We would like to express our thanks to all those that participated and sent in responses. Please click here to view our consultation response report.

What the community told us at the drop-in sessions:

"I fully support any scheme which will help reduce flooding to the River Pinn…"

"The June 2016 flooding caused great damage to our house and several other houses in the road.  This resulted in a big insurance claim, massive disruption….and huge personal distress.  Anything….that can be done to alleviate the risk of something similar happening in the future must be done as soon as possible…"

"Although our house has not been flooded we are concerned that climate change is resulting in more frequent flash storms similar to the June 2016 incident thus putting our home at risk."

We will continue to gather the views and knowledge of local people as this project progresses. We will also continue to work with local flood action groups to develop emergency flood plans and share knowledge.

Working with Flood action groups

In November our Flood resilience team met Flood action groups to create community flood action plans. These plans will help residents work together as a community to prepare for and respond quickly to any flooding that may occur. The plans will combine local knowledge and experience of flooding processes with our technical expertise to help protect life and property.

The first stage is currently underway and we are working together to capture local flooding triggers and identify actions taken by residents. By working in partnership with the residents we will be able to use the information gathered to form a plan specific to the needs of the area.

The community action plans identify what actions residents can take before, during and after a flood and helps to identify what resources are readily available to help the community respond and recover. It also makes it easier for the community to communicate with each other and responding Authorities, seek help in an emergency and know who can help to recover quicker.

As part of this work, we have installed a gauge board on the Cannon Brook, at Howletts Lane Bridge to allow residents to observe and take accurate water level readings in the brook. In the absence of a current flood warning service on the Cannon Brook, this gauge board will help create a record of high water levels and will assist residents in taking early action before flooding occurs downstream. The gauge board will also help us make sure the river level readings we are taking from the electronic temporary river logger are accurate. The position of the gauge board ensures it is easy to read safely from Howletts Lane Bridge and will not obstruct any flow in the channel.

We will work with the local community to understand the relationship between the river levels at the gauge board and what is happening downstream by Wallington Close so it can be used as a method of warning residents before flooding occurs.

To finalise the plans, we would like to hold an exercise with residents to test the plans and identify any improvements.

Background

Communities in the River Pinn catchment have experienced flooding several times, most recently in June 2016. According to our records, flooding has affected different parts of the catchment in 1947, 1968, 1977, 1984, 1986, 1987, 1988, 1992, 1993, 2000, 2002, 2009, 2012, 2013 and 2014. We have recently been working with Hillingdon and Harrow Councils as well as Thames Water to better understand the causes of this flooding and identify actions that could reduce the risk in the future.

   

Photos above show flooding in 2014 and 2016 in the London Borough of Hillingdon.

Our recent work has focussed on drawing together what we know about the catchment to identify the potential options for managing the risk of flooding. This includes looking at previous studies and gathering knowledge about the flooding issues, both from our records and from residents. We have looked at the catchment in detail to better understand the risks and opportunities across the study area.

The “River Pinn Initial Assessment Report” which summarises the work we completed before our consultation is available as a pdf at the bottom of this page. Please note that the costs included in this report are an indication only, and will be revised to make sure they are realistic before we develop the project options in more detail.

The River Pinn Project – Option development

In our last update in October 2018, we explained that in order to develop our projects further and decide on our preferred options to implement on the ground we need to gather some more information. This is to help us better understand how flooding happens and design the individual options in greater detail. Our progress in these areas of work is outlined below:

  • gather topographic survey information (so we can better understand the lay of the land and exactly where water will flow in times of flood)

This is now complete and we received the final survey information from our contractors in December 2018.

  • use this survey data, alongside other information gathered through the consultation to update our flood computer model (so we can assess our options and understand where will be reduced from flooding)

Now that we have up-to-date survey data we have set up a contract with our consultants to update our flood computer model. We expect this work to start in February 2019 and it will run for up to 6 months. The update of the model covers the whole catchment so will be available for all of the projects.

  • determine which are our preferred options, work out how much they will cost and get financial approval to design those options in detail.

For each of the study areas across the catchment we have determined which options or combination of options are most technically, financially and environmentally viable based on the information we have available at the moment. Further detail on these across the different areas of the catchment can be found later on this page. The work to design them in detail will start once the model update work is complete.

We will be focussing our detailed design work on the East Ruislip area first. This is because the technical and financial viability of these options is currently clearer. We have been able to develop an estimated timeline for our work on the East Ruislip project which can be found further down this page. We will provide timelines for the other project locations in future updates once the information is available.

The responses to our consultation told us people want to see more detail about how the options will affect them. The work we are starting now will continue to develop our understanding of how the options need to be designed to be most effective. We will continue to provide further information as it becomes available.

The next detailed information we will be able to share with communities will be once we have completed our model update in summer 2019. We will need to utilise local knowledge to make sure that our model represents flooding as it is experienced on the ground.

The River Pinn – individual project updates

As explained in our October 2018 update we have made a decision that the project will be progressed as 4 individual projects for the next steps. This is to enable us to focus on the specific areas, and progress each of them as soon as we are able to. The infographic below shows the 4 different areas we are looking at and the potential options we are investigating. There is more detail on each of the areas in the following sections.

We have included a summary of the most viable options for each of the areas, but please note that there is still scope to change the detail of these as we progress through the next stages of these projects.

Pinner and Hatch End

Our current preferred options for this area are a combination of:

  • embankments, walls and/or flood storage at Albury Drive
  • operational changes and control structure modifications to George V Reservoir (an existing flood storage area above George V Avenue)
  • natural flood management (NFM) in Pinner Wood

Following the model updates we will be able to look at the benefits of these options in more detail and refine our understanding of how much they will cost.

We will then need to find additional funding from other sources to enable us to progress this project any further.

East Ruislip

Our current preferred options for this area are a combination of:

  • natural flood management (NFM) and/or raised defence (embankment and/or wall) in Park Wood
  • flood storage area on Kings College Playing Fields
  • flood wall and/or embankments at Kings College Playing Fields

 
Following the model updates we will be able to look at the benefit of the options in more detail and refine our understanding of how much they will cost. We will then have a better idea of how much funding from other sources we will need to secure in order to design the options in more detail.
 

Our assessment of the options in East Ruislip is likely to progress more quickly than the other areas. This is because the technical and financial viability of these options is currently clearer. We have been able to develop an estimated timeline for this work. We have included major project milestones, as well as an indication of when we will hold specific engagement sessions with communities.

Please note that these timescales are an estimate based on the current information. They are subject to change as the project progresses, and should not be taken as definitive.

West Ruislip

In the West Ruislip area, the options which we identified are not currently being taken forward as the costs are too high for the benefits that they would provide.

Following the model updates, the next step for the West Ruislip area is for us to use all of the information we have gathered from communities, partners, and through the work we have done looking at options, to work out the best way to take the project forward. Even though we have not yet identified a solution which is financially, technically and economically viable, we have learnt a lot about the catchment and feel we are in a better place than we were when our project started. We would like you to continue to work with us to influence how this develops.

There has been a lot of concern and enquiries from residents relating to the silt build up in the Cannon Brook. We have reviewed all of the information we have been provided and discussed the issue with local experts. As a result we will be putting together a separate case study to outline our understanding of the silt processes in the catchment and any actions we think need to be taken to investigate it further. This document will be available on this page, and we will email our stakeholder list when it is published.

Lower Pinn

Our current preferred options for this area are a combination of:

  • embankments and/or walls - Dawes Road to Hillingdon Road, Uxbridge
  • embankments and/or walls – Church Road, Uxbridge
  • flood storage - south of Church Road, Uxbridge
  • embankments and/or walls - Zodiac Business Park, Yiewsley

 
Following the model updates we will be able to look at the benefits of these options in more detail and refine our understanding of how much they will cost.
 
We will then need to find additional funding from other sources to enable us to progress this project any further.

What happens next?

We will continue to work with our partners and communities to secure funding for these projects. They are currently partly funded by central government, but there is still a need to find more funding, for example from organisations and businesses that will benefit. We can only progress to the point where we are ready to undertake work on the ground, if full funding has been secured.

Alongside the information page we are developing a series of key messages which provide more detail on specific questions you might have about our projects. These will be available during February in pdf format from this information page and we will email our stakeholder list when they are available.

If you would like to be kept updated or share your experiences of flooding please fill out the forms in the sections below. If you are already on our list you do not need to fill out a form.

Our next webpage update will be in spring 2019, and for this update we hope to be able to split our project page into 4 so there is a page for each project. We hope this will make it easier for you to find the latest information for the area you are interested in.

Thank you for visiting our project information page. For any comments or feedback on our information page, please email PSO-HNL@environment-agency.gov.uk

Visit our website here to find out more about what you can do to reduce the impact of flooding on you and your property.

Find out about your rights and responsibilities of owning a watercourse here.

View our schedule of maintenance work on the River Pinn here.

If you have been flooded from a public sewer, please complete Thames Water's sewer flooding questionnaire on their website here and return it to them at the address on the form. 

 

Audiences

  • Recreational and commercial river users
  • Members of the public with an interest in the river, the species and conservation
  • Businesses
  • Charities
  • Statutory organisations
  • Members of the public
  • Elected representatives, including MPs
  • Local councils
  • Environment Agency customers
  • Local authorities
  • District and parish councils
  • Environmental bodies
  • Land owners
  • RFCCs
  • Water companies
  • Members of the public
  • Community groups
  • Flood action groups
  • Members of the public
  • Community groups
  • Members of the public

Interests

  • Flood management
  • Water resources
  • Habitats and wildlife