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Thames Water Utilities Limited – Hampton Water Treatment Works, Contact Tanks Inspection, Remediation and Cleaning

Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (as amended)

Reference: TMS-2023-00001

Version Number: 2

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): Thames Water Utilities Limited, with registered number 02366661 (hereinafter called ‘the Company’).

Assets Affected:

Asset Name

Reference

Hampton 3 NORTH WTW Contact Tank

T01S.010
T01S.011
T01S.012

Hampton WTW South Contact Tank

T01S.010
T01S.011
T01S.012

Hampton Water Treatment Works

T01S.010
T01S.011
T01S.012

Table 1: List of assets affected and associated reference numbers

Details of this Notice:

  1. The Drinking Water Inspectorate (‘the Inspectorate’) has received a set of regulation 28(1) report of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the Company on 11 October 2022 (and subsequent updates dated 20 February 2023), which state that there is or has been a significant risk of supplying water from Hampton Water Treatment Works (and associated assets as applicable) that could constitute a potential danger to human health or could be unwholesome.
  2. Consequently, this Notice is served on the Company by the Inspectorate on behalf of the Secretary of State, under regulation 28(4) for the assets listed above, for risks associated with:

Description of Risk

Hazard/ Hazardous Event/ Parameter

Potential risks from storage of water in tanks; including contamination from ingress or egress, and microbiological re-growth.

Coliform bacteria

Escherichia coli (E. coli)

Enterococci

Colony Counts

Chlorine (chlorine free and total)

Table 2: Table of the hazards, hazardous events, and/or parameters covered by this Notice, including the Hazard I D numbers and the description of risks.

  1. The Company are required to satisfy the following requirements.

The date given is that until or by which the requirements must be maintained or satisfied, as appropriate.

Requirements:

(a) To maintain the following measures for the period specified in each case:

  1. Operate the contact tanks at Hampton Water Treatment Works in accordance with current company policy, standards, and procedures, that align to recognised standards of good practice.
    Date: Ongoing for the duration of this Notice.
  2. Maintain risk-based enhanced (in addition to routine regulatory sampling) sampling for both the contact tanks at Hampton Water Treatment Works. This must include, as a minimum, colony counts, E. coli and coliforms.
    Date: Ongoing for the duration of this Notice.
  3. Maintain proactive external inspections, grounds maintenance, site security and asset maintenance of both the contact tanks at Hampton Water Treatment Works. This must include periodic inspections of hatches, seals, redundant assets, sample taps, overflows, washouts and air valves.
    Date: Ongoing for the duration of this Notice.
  4. Maintain appropriate contingency plans (including liaison with relevant stakeholders as appropriate) to protect human health.
    Date: Ongoing for the duration of this Notice.
  5. Maintain measures to ensure ingress is prevented from entering the contact tanks at Hampton Water Treatment Works.
    Date: Ongoing until the completion of measure (b)4 for the North contact tank and (b)8 for the South contact tank.

(b) To review, revise or make operational the following measures, by the dates specified in each case:

Hampton Treatment Works’ Contact Tank North

  1. Develop a plan for the enabling works required to allow the physical internal inspection, clean, flood test and completion of any required remedial work of the Hampton Treatment Works’ Contact Tank North.
    Date: Complete (14 June 2023).
  2. Complete the required enabling works identified under measure (b)1.
    Date: Complete (15 June 2023).
  3. Complete the physical internal inspection of Hampton Treatment Works’ Contact Tank North.
    Date: Complete (17 January 2024).
  4. Complete any required work identified by the internal inspection (measure (b)3). Complete the clean of Hampton Treatment Works’ Contact Tank North.
    Date: Complete (31 March 2024).

Hampton Treatment Works’ Contact Tank South

  1. Develop a plan for the enabling works required to allow the physical internal inspection, clean, flood test and completion of any required remedial work of the Hampton Treatment Works’ Contact Tank South.
    Date: Complete (14 June 2023).
  2. Complete the required enabling works identified under measure (b)5.
    Date: 30 June 2024.
  3. Complete the physical internal inspection of Hampton Treatment Works’ Contact Tank South.
    Date: 31 July 2024.
  4. Complete any required work identified by the internal inspection (measure (b)7). Complete the clean of Hampton Treatment Works’ Contact Tank South.
    Date: 30 November 2024.

General

  1. Review the Hampton Treatment Works’ specific emergency contingency plans to ensure they are fit for purpose so that the Company can respond in a timely and appropriate manner, to any potential water quality incident, to protect human health. Implement any necessary measures to address the findings of the review.
    Date: Complete (30 June 2023).
  2. Following the completion of measures (b)4 and (b)8, review the suitability of the treatment and disinfection process arrangements at Hampton Water Treatment Works to prevent unwholesome water from entering supply.
    Date: 31 December 2024.
  3. Implement measures to address the findings of the review completed under measure (b)10.
    Date: 30 June 2025.
  4. Upon the discovery of active ingress into either of the Hampton Treatment Works’ contact tanks;
  • Implement immediate short term mitigation measures to ensure human health is protected; and
  • Design and implement a solution to stop the ingress.
    Date: Ongoing for the duration of the Notice.

(c) To audit whether the measures have been effective by the following means:

  1. Define an audit strategy to monitor the effectiveness of the measures specified in sections (a) and (b).
    Date: Complete (30 June 2023).
  2. Implement, and keep under continuous review, the audit strategy defined in measure (c)1.
    Date: Following completion of measure (c)1 onwards.

(d) Not to supply water for regulation 4(1) purposes from Hampton Water Treatment Works, or not to so supply unless the specified conditions below are satisfied:

  1. Not applicable

(e) To provide the following information in the time and manner specified below to enable monitoring of progress towards the mitigation of the risks:

  1. Provide a progress report annually.
    Date: by 31 January each year.
  2. Provide the plan, including timeframes, of the enabling works required to remove Hampton Treatment Works Contact Tank North and South from supply for a physical internal inspection, clean, flood test and completion of any required remedial work (measure (b)1 and (b)5).
    Date: Complete (06 April 2023).
  3. Submit a report outlining the following for Hampton Treatment Works Contact Tank North:
  • Findings from the internal inspection;
  • Evidence of any remedial works completed; and
  • Return to supply water quality sign off and sample results.
    Date: Complete (30 April 2024).
  1. Submit a report outlining the following for Hampton Treatment Works Contact Tank South:
  • Findings from the internal inspection;
  • Evidence of any remedial works completed; and
  • Return to supply water quality sign off and sample results.
    Date: 31 December 2024.
  1. Outline the findings of the review required under measure (b)9 and any measures implemented.
    Date: Complete (31 July 2023).
  2. Outline the findings of the review required under measure (b)10.
    Date: 31 January 2025.
  3. Confirm completion of measure (b)11.
    Date: 31 July 2025.
  4. Where ingress has been found and the company are unable to take the tank out of supply immediately or keep the tank out of supply until the ingress has been stopped, this must be notified as an event to the Inspectorate under paragraph 9(1) of the Water Industry (Suppliers’ Information) Direction 2023. The company’s written notification under paragraph 9(2)(b) of the Direction must outline:
  • the immediate mitigation measure implemented to protect human health; and
  • the company’s action plan to mitigate the risks associated with ingress in the medium to long term.
    Date: in line with the requirements of the Water Industry (Suppliers’ Information) Direction 2023 (and any subsequent amendments thereof)
  1. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: Complete (31 July 2023).
  2. Submit any revisions of the audit strategy produced under measure (c)2.
    Date: Within 1 month of a revision
  3. Submit a report in the event that any completed measures of this Notice need to be altered in any way, for any reason.
    Date: Ongoing for the duration of this Notice.
  4. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 31 July 2026.

Further Details of this Notice:

  1. Any product or substance used as a result of the requirements in this Notice must comply with regulation 31.
  2. Under regulation 28(6) the Inspectorate, on behalf of the Secretary of State, may by notice served on the Company, revoke or vary this Notice.
  3. Failure by the Company to comply with this Notice may result in enforcement proceedings under section 18 of the Water Industry Act 1991 (as amended).

Signed

Nicholas Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
Date: 18 July 2024
Reference: TMS-2023-00001 v2

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