Hogsmill Sewage Treatment Works

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In 2008, the Council encouraged residents to report incidences of unreasonable odour coming from the Hogsmill Sewage Treatment works, in order that Thames Water could be made aware of the extent of the odour problems at the Works. Online reporting facilities and a dedicated telephone hotline were set up for this purpose.

As a result, complaint levels rose enabling officers to put greater pressure upon Thames Water to seek improvements to the design and management of the works. Some immediate steps were taken, although it was recognised that major works would also be required.

Thames Water were committed to make the necessary improvements and undertook to seek funding. It was acknowledged that given the level of investment needed it would be sometime before works would be commenced, but the Council was confident that the matter was progressing as quickly as possible.

This web page will be updated with the latest developments, please check back regularly.

We are now able to provide the following update regarding the progress of Thames Water’s odour mitigation works.

The covering of the Inlet Works is now 50% complete and together with its odour control plant is expected to be commissioned early 2012.

The covering of the secondary digesters with bio dome covers is expected to be complete by Christmas.  Its associated odour control measures will be commissioned early in 2012.

Improvements to the cleaning mechanisms to the Storm Tanks are expected to be fully operational by spring 2012.

Other works, such as the meeting room for visiting School children, landscaping works and tree planting are all expected to be completed by Christmas 2011.

Thames Water have also advised that over the next week or so they are undertaking rag clearance and tunnel cleaning in preparation for the covering of the Inlet Works and while they will take all reasonable measure to mitigate odour there may be a small increase during this period.

Thames Water advise that the blockage causing the recent odour incidents has been cleared. Dissipation of residual odour may result in some odour being occasionally detectable (depending upon wind strength and direction), however an improvement should be noticeable over the next few days

Officers responding to a recent increase in complaints have been advised by Thames Water that they have identified a blockage in ductwork taking screened material from the sewage.  They are currently working to unblock it and anticipate it to be cleared by the beginning of next week.

The Council has received a number of complaints about odour form the works this week and has been in communication with Thames Water to identify whether there were any specific reasons why this might be.

Thames Water advise that, as result of the recent dry weather, sewage flowing into the works inlet is more concentrated, and consequently more odorous. A general lack of surface/rain water to dilute and maintain a steady flow of sewage through the tunnel leading form the former Worcester Park works has increased bacterial activity in the sewage. The recent warm weather, higher atmospheric pressure and low wind speeds have hampered dispersal and caused transient odour to become more perceptible in the local area.  

Thames Water are investigating what steps can be taken to resolve remaining odour concerns, and we will continue to work with them to ensure that all available measures are being taken to minimise disturbance.

Small pockets of odour have been identified in the area of the old aeration lanes, and whilst it is not thought that these have been the source of cross boundary odour complaints, Thames Water are also undertaking works today to eliminate this potential.

Thames Water continue to progress with plans to provide long term odour control measures, and we understand they will be writing directly to residents about their proposals. In the meantime, please continue to check this webpage for the latest information.  

Tanker movements to the Works from the collapsed New Malden sewer have now ceased, although there may be some occasional movements from time to time until the repairs are complete.

The cleaning and maintenance operations that gave rise to the majority of the odour problems in March are now coming to an end.  This has been supported by a fall in complaint numbers over the last week.

Thames Water has acknowledged that residents were subjected to a period of unpleasant odour from the Works, apologise for this disturbance and are grateful for your patience.  The unusual increase in volume of complaints during March has provided Council Officers with a good platform to seek improvements in operational activity and processes and enabled the identification of specific odorous maintenance processes which need to be addressed by Thames Water.

We remain in close communication with Thames Water and will continue to use all available measures to ensure that they have systems and procedures in place to minimise the release of excessive odour.  Details of Thames Water’s future odour management proposals will be published on this page shortly.

Unfortunately tanker movements from the collapsed sewer in New Malden have needed to continue but Thames Water have now advised that this should cease by the weekend.

Problems were also encountered during some of their routine cleaning operations at the Works.  It is now planned for these to be completed by the end of the week. Other maintenance and landscaping works will continue but these are not believed to be a source of significant odour.

The Council continues to receive unusually high volumes of complaints and all parties, including Thames Water acknowledge the degree of odour that has been emitted from the Works in recent weeks.  We are in regular contact with them and are seeking more detailed information about their long term odour control works that are due to commence on site shortly.  It is anticipated that with the completion of these works odour episodes such as these will be greatly reduced.  More updates will follow.

Following a meeting with Thames Water this week and inspection of the Hogsmill Works we can provide the following update.

Works to replace the collapsed sewer in New Malden are progressing, although they were found to be more complicated than first thought.  It is hoped that by the weekend manual transfer of sewage back to the Hogsmill Works by tanker will cease and odours will be reduced.

A major source of odour has also been attributed to routine maintenance and cleaning works.  These are coming to an end this week and while some will continue, with some further ongoing landscaping works, it is anticipated that residents should experience a notable improvement in air quality.

Please continue to report episodes of odour as detailed below.

We have received a large number of complaints over the last 2-3 weeks of excessive odour from the Works.  Thames Water have advised that due to a major sewer collapse in New Malden they are needing to re-direct the sewage, which unfortunately has lead to increased odour release.  The works are quite involved and unfortunately will take some time to complete.

In addition they are undertaking some landscaping works, which form part of a planning agreement with the Council.  Similar works were undertaken in September 2009, which also lead to an increase in complaints.  They are also carrying out maintenance to some of their tanks, which may be contributing to the odour.

We will be meeting Thames Water next week and hope to be able to provide a further update.

Officers are due to meet with Thames Water in the near future. Thames Water have accelerated planned maintenance works at the site, which may have been responsible for recent malodour in the area. Further odour may be experienced in the short term whilst these works are completed. Further updates to follow.

Officers have met with representatives from Thames Water, who advised that OFWAT, the water regulator, has approved a substantial sum of expenditure on a range of odour prevention and abatement works at the Hogsmill Sewage Treatments Works. These works will essentially involve the enclosure within buildings of the potentially malodorous elements of the treatment process, together with odour abatement equipment to 'clean' air mechanically extracted from these buildings.

Thames Water hope to commence works in the next 2-3 months, with a view to completion in late 2011.

Officers will be meeting again with Thames Water in the Autumn to hear more about the project plan, and will continue to meet regularly to review progress.

We will continue to update this webpage as the work progresses.

Officers have met again with representatives from Thames Water Utilities.  Whilst work on the odour prevention and abatement works has yet to begin on site, Thames Water Utilities have appointed a project team and are in the process of finalising the design of the works and appointing sub-contractors.

A further meeting is arranged for the spring, when it is hoped more progress will have been made and detailed plans will be available for officers to examine.

You can register an odour incident with the Council by using the Report an Odour Online link at the bottom of this page, by emailing hogstwodour@rbk.kingston.gov.uk or leave a message 24 hours a day on the Odour Hotline  - 020 8547 4669.  When leaving a message it is important to provide your full contact details, including name and address as without this information we are unable to plot your location and establish the extent of the odour problem.

You may also make your complaint in writing to:

Environmental Health and Trading Standards
Royal Borough of Kingston upon Thames
Guildhall 2
Kingston upon Thames
KT1 1EU

Fax: 020 8547 5515

If you would like to discuss odour incidents with an officer, please telephone the Environmental Health Service on 020 8547 5002, during office hours.

You may also wish to report incidents of odour with Thames Water on 0845 9200800 or email: customer.feedback@thameswater.co.uk quoting “Hogsmill Sewage Treatment Works”.