Hanifa Dobson and Others v Thames Water Utilities Ltd The Water Services Regulation Authority ("Ofwat") (Intervening)

JurisdictionEngland & Wales
CourtQueen's Bench Division (Technology and Construction Court)
JudgeTHE HON. MR. JUSTICE RAMSEY,Mr Justice Ramsey
Judgment Date08 December 2011
Neutral Citation[2011] EWHC 3253 (TCC)
Date08 December 2011
Docket NumberCase No: HT 06-04

[2011] EWHC 3253 (TCC)




Royal Courts of Justice

Strand, London, WC2A 2LL


The Hon. Mr. Justice Ramsey

Case No: HT 06-04

Hanifa Dobson and Others
Thames Water Utilities Limited


The Water Services Regulation Authority (“Ofwat”)

Mr Stephen Hockman QC and Mr John Bates (instructed by Hugh James) for the Claimants

Mr David Hart QC and Mr Michael Daiches (instructed by Osborne Clarke) for the Defendants

Mr Ben Lask (instructed by Ofwat) for the Intervening Party




1. In these proceedings some 1350 claimants (“the Claimants”) who live in the vicinity of the Mogden Sewage Treatment Works (“Mogden STW”) in Isleworth, Middlesex seek damages against Thames Water Utilities Limited (“Thames Water”) for nuisance caused by odour and mosquitoes.


2. A Group Litigation Order dated 21 December 2005 applies to these proceedings. The Claimants are divided into two categories: those who have occupied properties as owners or lessees (Schedule A Claimants) and those who have occupied without any legal interest in the properties (Schedule B Claimants).


3. The Claimants served a Group Statement of Case on 9 March 2006 in which they pleaded that odours and mosquitoes from Mogden STW have caused a nuisance; that they have been caused by the negligence of Thames Water and that Thames Water have breached rights under Article 8.1 of the European Convention on Human Rights 1950 (“the Convention”) and Article 1 of the First Protocol to the Convention. As a result the Claimants seek damages for nuisance and negligence as well as damages under the Human Rights Act 1998 (“the HRA”) for breach of their Human Rights.


4. In the Defence to the Group Statement of Case, Thames Water raised various threshold defences to the claims. In particular, they contended that complaints about odour or mosquitoes from Mogden STW were complaints of a failure of its duties under the Water Industry Act 1991 (the “WIA”) and the Urban Waste Water Treatment Regulations and that there was no common law remedy or remedy under the Human Rights Act to enforce those duties, whether in nuisance, negligence or under the HRA because such causes of action were precluded by the decision of the House of Lords in Marcic v Thames Water Utilities Ltd [2004] AC 42. In addition Thames Water raised various other defences in relation to damages and limitation.


5. As a result, I ordered that there should be the trial of certain preliminary issues concerning the “Marcic Defence”, damages and limitation. I gave judgment in respect of those issues in Dobson v Thames Water Utilities Ltd [2007] EWHC 2021 (TCC); [2007] BLR 465 on 24 August 2007. The Court of Appeal gave permission to appeal on certain issues and in a judgment handed down on 29 January 2009, [2009] EWCA Civ 28; [2009] BLR 287, allowed the appeal in part.


6. Subsequently, this matter proceeded to a trial of test cases relating to 30 Claimants in respect of 10 lead properties to establish liability and quantum of the claims made by those claimants. In this judgment I consider those claims.


7. I consider, first, the background to the claim, including the history of Mogden STW, the process carried out there, the regulatory system which applies at Mogden STW, the work which has been carried out to that STW and other matters of chronology. I then consider the various parts of the plant, the allegations about the performance of the plant and then allegations of odour negligence. After that I consider the allegations of mosquito nuisance, I then set out my conclusions on liability for those two complaints. Finally I turn to the question of quantum.


8. Mr Stephen Hockman QC and Mr John Bates appeared for the Claimants; Mr David Hart QC and Mr Michael Daiches appeared for Thames Water. Mr Ben Lask appeared on behalf of Ofwat in relation to the evidence of one witness, Mr George Day, called to give evidence about various regulatory matters.




The History of Mogden STW


9. Mogden STW was originally built between 1931 and 1935 to cope with a population of 1.2 million people. It has since been expanded on a number of occasions in 1962, 1989 to 1991 and 2000 and now deals with sewage flows from an area bounded by Hendon in the North, Uxbridge in the West, Sunbury in the South and Chiswick in the East, a population of some 1.8 million people.


10. The works were originally operated by the relevant local authority. In 1974 they were transferred to Thames Water Authority and subsequently on 1 September 1989, when the water industry was privatised, they were transferred to Thames Water.


11. At privatisation of the water industry on 1 September 1989 the works at Mogden STW required much needed investment to comply with new regulations then coming into force regarding river quality.


The process at Mogden STW


12. It is convenient to identify the plant at Mogden STW and how that forms part of the sewage treatment process. The sewage arrives at Mogden STW through three main sewers: the Bath Road high level sewer, the Chiswick low level sewer and the Western low level sewer. The flow to the works is divided into two main streams: the East stream and the West stream, both treating the sewage by similar processes.


13. The sewage flow to the West side works is taken from the Bath Road sewer. The rate of flow coming into the West side is controlled by a hydraulic gate known as “Lucifer's gate”. The flow rate to treatment in the West side is measured after Lucifer's Gate. Sewage from the Chiswick and the Western low level sewers is measured in the main pumping station where it joins the remaining flow from the Bath Road sewer which has not passed to the West side works. This sewage then flows to the East side works. After screening and grit removal any flow in excess of the treatment capacity of the East side works passes over an overflow weir and goes to the storm tanks. The rate of flow is measured after this overflow weir and the amount to be treated is controlled from the control room using a valve known as “Penstock John”. Closing this penstock valve causes the flow level to back up which then leads to more sewage overflowing to the storm tanks. If the penstock is opened then the water level at the overflow weir is reduced and this in turn reduces the amount of overflow passing to the storm tanks.


14. When capacity for treatment is available, the storm tanks are then emptied by pumping the untreated sewage back into the East side of the works. If there is prolonged or high rainfall and the capacity of the storm tanks cannot deal with the overflow then the excess, partially settled sewage passes directly into the River Thames.


15. The sewage which passes through Lucifer's Gate in the West side inlet works or Penstock John on the East side inlet works then both go through a similar process of treatment on each side of Mogden STW, except that originally there were both Primary Settlement Tanks and Secondary Settlement Tanks on the East side which provided a two stage primary settlement process.


16. First the sewage goes through the primary settlement tanks (“PSTs”) where sludge known as primary sludge is settled out. After primary settlement, the sewage then receives biological treatment by the activated sludge process (“ASP”). That process introduces air and uses naturally occurring micro-organisms in the sewage to treat the organic matter in the settled sewage by oxidizing and synthesising it. The air used in the process is blown into aeration units in the form of domes to keep the dissolved oxygen level in the sewage/bacteria mixture aerobic. That sewage/bacteria mixture is referred to as “mixed liquor”. When the waste organic matter and ammonia in the sewage have been oxidised to a satisfactory level, the mixed liquor flows to the final settlement tanks (“FSTs”). Here the mixed liquor is allowed to settle and some of the sludge is then pumped back to the aeration units to seed the incoming settled sewage with micro-organisms so they can treat more incoming sewage by the ASP. This return cycle of sludge is called return activated sludge (“RAS”).


17. The treated sewage in the form of a final effluent then overflows the FST weirs and is discharged to the tidal River Thames. Once the waste water has been treated by the process, as set out above, there is a need to treat the surplus activated sludge (“SAS”) which is the sludge which is not recycled as RAS to the inlet of the ASP, as well as the primary sludge which has been settled out in the PST.


18. The primary sludge is pumped to a holding tank, known as the raw sludge holding tank (“RSHT”). This sludge is then thickened by a process which originally used paddles, known as Picket Fence Thickeners (“PFTs”) but now uses drum thickeners so that the sludge is concentrated to have a solid content of about 6%. This sludge is then transferred to another holding tank, the thickened sludge holding tank (“TSHT”).


19. The SAS from the FSTs was also originally pumped to form part of the same sludge stream as the primary sludge so that it was also thickened by using Picket Fence Thickeners. This process was modified, as I shall explain below, and the SAS is now pumped to a separate holding tank and is then thickened by the use of centrifuges until it also has a solids content of approximately 6%. It is then transferred to the TSHT, the same holding tank as the thickened primary sludge.


20. The combined flow of the thickened...

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4 cases
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    • Queen's Bench Division (Technology and Construction Court)
    • 20 June 2014
    ...have been affected, it may be appropriate and just to evaluate the related inconvenience etc. In Dobson v Thames Water Utilities Ltd [2011] EWHC 3253 (TCC), which was an odour nuisance case, Ramsey J addressed the method of assessment of damages to owners and occupiers of dwellings around a......
  • Loke Yuen Jean Tak Alice v Wong Kit Ying And Another
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    • High Court (Hong Kong)
    • 1 August 2019
    ...and 706 [78] DCCJ934/2006, HHJ Mimmie Chan (as she then was) (unreported, 12 July 2007) paras 87-88 [79] [2016] 1 WLR 2265, 2279 [80] [2011] EWHC 3253 TCC (see also see McGregor on Damages 20th ed para 39-021 at p 1234, Calabar Properties Ltd v Stitcher [1984] 1 WLR 287 and Formalex v Abdoo......
  • Hanifa Dobson & Others v Thames Water Utilities Ltd
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    • Queen's Bench Division (Technology and Construction Court)
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    ...A Claimants ("the Claimants") for interest on the general damages which I awarded for nuisance in the Second Judgment, [2011] EWHC 3253 (TCC). There is a disagreement between the parties about the basis on which interest should be awarded on an award of general damages for nuisanc......
  • Loke Yuen Jean Tak Alice v Wong Kit Ying And Another
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    • 1 August 2019
    ...and 706 [78] DCCJ934/2006, HHJ Mimmie Chan (as she then was) (unreported, 12 July 2007) paras 87-88 [79] [2016] 1 WLR 2265, 2279 [80] [2011] EWHC 3253 TCC (see also see McGregor on Damages 20th ed para 39-021 at p 1234, Calabar Properties Ltd v Stitcher [1984] 1 WLR 287 and Formalex v Abdoo......

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