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We’re investing £5.5 million on a major upgrade of Portswood Wastewater Treatment Works in Portswood, Southampton.

The improvements we’re making will help reduce odours in and around the site and will improve the efficiency of our treatment works.

  1. Why are you doing this work? 
    • This work will help reduce smells for people living and working near the treatment works, while ensuring it can continue to meet the wastewater needs of our customers.
  2. What work are you doing?  
    • We’ll be installing a new odour control system and fitting covers onto the parts of the treatment process, which will help to reduce smells.

      We’ll also be upgrading the inlet works – where wastewater enters the site – and making improvements to the tanks which store and treat water.
  3. Will this work stop smells coming from the site?  
    • We understand that smells can be a concern for customers living and working close to the treatment works and the improvements we’re making will help reduce these smells in future.

      The new covers and odour control system will both help to reduce odours, and we’ll also be making changes to how we transport sludge from the site.

      While it’s impossible to completely eliminate odours associated with treatment works, we’re confident that once complete, our work will result in a noticeable improvement.
  4. Who’s carrying out the work and how long will it take? 
    • These improvements are being carried out by our contractors Galliford Try. Work began in September 2017 and should be complete by August 2019.
  5. What will be your working hours? 
    • Our normal working hours will be 7.30am to 6pm Monday to Friday. If we need to work on a Saturday, this will be between 8am to 1pm will not include excessively noisy activities.
  6. Will there be any disruption during the work? 
    • There will be minimal disruption for businesses and residents living nearby as all work will take place within the site, which is well-screened.
  7. How many trucks will there be coming and going from the site and how will this be managed? 
    • There will be less than 100 trucks arriving at the site over the course of the two-year project. Some of these will be need to deliver large items of equipment or portable office units.

      A traffic management plan will be in place for all large deliveries. Kent Road may be subject to temporary parking restrictions during identified large deliveries. We will contact residents along the route prior to any restrictions being in place.

      All suppliers and subcontractors will be given written instructions detailing this route and acceptable times for making deliveries.
  8. Will you be removing any trees? 
    • No trees or vegetation will be removed from the perimeter of the site as part of these works.
  9. How many people will be working on the site? 
    • Around 30 people will be working on this scheme.


Find out what progress we’ve made and what work is coming up:

7 September 2018
The Odour Control Unit is now fully installed. Final commissioning of the unit continues to take place to help make sure that it’s working at full capacity and this will be completed as soon as possible. 
Although the unit is not yet fully optimised, we’ve completed many other aspects of our major upgrade work which has helped reduce odour levels.
Thank you for your patience.

17 August 2018

The Odour Control Unit is still on track to be operational by the end of the month.

3 August

Commissioning the Odour Control Unit is progressing well. The system needs carbon for filtering air, which arrived this week.

This major piece of equipment is still on track to be operational by the end of August, to reduce odour by removing, filtering and re-releasing air from the covered tanks.

We’re continuing to work hard to reduce odour at the site, and our temporary measures remain in place. The site also includes permanent deodoriser sprays which run constantly.

  1. June and July 2018 updates 
    • 27 July

      Work is progressing with our £5.5 million upgrade. The Odour Control Unit has been installed and pipework is being completed. We'll then start the process of making the system operational - we aim to have it running by the end of August.

      We’re also currently installing the Motor Control Centre, with the panel for the equipment arriving on site last week.

      All tank covers have now been installed. We’re continuing to work hard to reduce smells coming from the site in the future.

      6 July

      Works continue to progress well and this week saw our final storm tank platform delivered to site.

      We’ve almost finished installing the covers on the detritor area of the site and we’re hopeful these particular works will be complete by the end of the month.
      Our permanent deodoriser sprays on site, which run constantly, are just one of the odour mitigation measures in place.  Thank you for your continued patience during this period of particularly hot weather, while we work hard to make improvements that will reduce smells coming from site in the future.

      29 June
      With works continuing, we remain on track to complete the installation of our permanent filtration system by the end of July. Commissioning of the unit will then take place and we’re hopeful the new system will be operational by the end of August. In the meantime, our temporary carbon filter will continue to process the odorous air coming from both consolidation tanks.

      Please be aware that we have a crane being delivered to site on Tuesday 3 July. The final storm tank platform will also be delivered on the same day, which will arrive on a large lorry.
      We’re continuing to work hard to minimise the smells coming from site and a number of odour mitigation measures remain in place.

      22 June
      This week saw the new air filtration system delivered to site and progress continues to be made. We remain on track for the system to be installed by the end of the month, with the expectation that it will be fully operational by the end of August. The new system will help remove unpleasant smells by taking away the air from the covered tanks and cleaning it.

      As you’ve seen from our previous updates, both consolidation tank lids were recently fitted and we’ve now also installed a temporary carbon filter which has been connected to both tanks.
      Our temporary odour mitigation measures remain in place and we thank you for your patience while we work hard to make improvements that will reduce smells coming from site in the future.

      15 June
      Progress has continued throughout the week, with upgrade works taking place on a number of different treatment processes.  A crane will arrive on site on Tuesday 19 June, to assist with installing necessary equipment.
      With both consolidation tank lids recently installed, we’re confident this has helped reduce smells on site. 
      Looking ahead, we’re on track for our permanent filtration system to be installed this month and we remain hopeful it will be fully operational by the end of August 2018.  The new system takes away the air from the covered tanks and will remove the unpleasant smells.
      The temporary centrifuge will continue to be used on certain days and we’re aware it can contribute to unpleasant odours coming from site.  We’ll continue to minimise the smells as much as we can, with odour reducing sprays just one of the additional measures in place.

      8 June

      We’ve continued to make good progress this week and the second consolidation tank cover was installed on Wednesday 6 June.  Both covers are now in place, which should help contain odours and reduce smells on site.

      The temporary centrifuge remains in use on certain days and we’re aware it can contribute to unpleasant odours coming from site.  We’ll continue to do all we can to minimise the smells and the odour reducing sprays will remain in use for the time being. 

      We’re hopeful that our permanent filtration system that takes away the air from the covered tanks and removes the unpleasant smells will be installed this month and will be fully operational by the end of August 2018.

      Thank you to those who joined us this week at our public drop-in.  Our project team enjoyed providing you with the latest site updates and answering your questions.

      1 June

      The project continues to progress well with the first of the permanent covers for the consolidation tanks being lifted into place today.  Preparations for the placing of the second cover are underway and we plan to have this in place by mid-June. 

      We’re aware the site can produce unpleasant smells, we’re doing all we can to keep these to a minimum while we complete the work. The temporary odour management will remind in place until we complete the improvements. We should be finished by the end of August 2018.

      Want to know more about what we’re doing, come and meet the team:

      We’d love you to meet our project team for an update and to ask questions about the improvements, so join us on Tuesday 5 June, any time between 1.30pm-3.30pm, for a public drop-in. We’ll be at Wessex DriveAbility, Leornain House, Kent Road, Portswood, Southampton, SO17 2LJ.

  2. Previous updates 
    • 25 May 2018

      We've continued to put additional odour mitigation measures in place throughout this week.

      The permanent consolidation tank lids have arrived on site and the first lid will be put in place during the first week of June. The second lid will be in place mid-June. These lids will help reduce the odours on site. 

      Additional odour mitigation sprays have also been put around the site. 

      We're working hard to make improvements that will reduce smells coming from the site in the future and we thank you for your patience.

      18 May 2018

      Due to the warm weather we’re putting in place some additional odour control on the site. This will include installing temporary covers on the open consolidation tanks and installing additional odour management equipment.

      The consolidation tanks will have permanent covers installed as part of the current improvements underway on site.  

      Please be assured we're working hard to make improvements that will reduce smells coming from the site in the future.

      April 2018

      We have now completed around 20% of the odour control work. The next stage will be to install odour covers on the consolidation tanks, which will take place over the spring and summer 2018. The odour control system will be delivered in the coming weeks and work continues to replace the main control centre, with the installation of a kiosk and replacement of cables. Work to install jet cleaners on the storm tanks is also in progress.

      February 2018

      New odour control covers have been installed over the inlet works – where wastewater enters to site for treatment. Final detailed design has also been finalised.

      December 2017

      With work well underway, we’ve joined forces with contractors Galliford Try to fund a £5,000 community grant. The money has been shared between a range of local groups and organisations including Victory Gospel Church’s Recovered 4 Life project, the Friends of Portswood Rec and Southampton Mencap. 

      September 2017

      We’re finalising plans for two innovative new domes which will replace covers on two of the sludge consolidation tanks. The lightweight design of the domes reduces the health and safety risk for construction worker yet provides an efficient barrier for odours.

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