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South East Water Limited – Sheet Treatment Works, Disinfection Risk

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

Reference: SEW-2018-00005

Version Number: 3

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): South East Water Limited, with registered number 02679874 (hereinafter called ‘the Company’).

Assets Affected:

Table 1: List of assets affected and associated reference numbers

Asset Name

Reference

Sheet Treatment Works

T224

Tilmore No 1. Reservoir

R259

Tilmore No 2. Reservoir

R260

Tilmore Water Supply Zone

Z269

Sheet Water Supply System

Y224

Table 1: List of assets affected and associated reference numbers

Details of this Notice:

  1. The Drinking Water Inspectorate (‘the Inspectorate’) has received regulation 28(1) reports of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the Company dated 01 September 2022 (originally 01 September 2018), which state that there is or has been a significant risk of supplying water from Sheet 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

Hazard I D

Failure to meet the requirements of regulation 26 and associated microbiological risk.

 

Total coliforms

T224-TREATMENT-C001

Failure to meet the requirements of regulation 26 and associated microbiological risk.

Escherichia coli (E.coli)

T224-TREATMENT-C002

Failure to meet the requirements of regulation 26 and associated microbiological risk.

Clostridium perfringens

T224-TREATMENT-C004A

Failure to meet the requirements of regulation 26 and associated microbiological risk.

Enterococci

T224-TREATMENT-C003

Failure to meet the requirements of regulation 26 and associated microbiological risk.

Colony counts

T224-TREATMENT-C007

Failure to meet the requirements of regulation 26 and associated microbiological risk.

Residual disinfectant – chlorine free

T224-TREATMENT-C009

Failure to meet the requirements of regulation 26 and associated microbiological risk.

Residual disinfectant – chlorine total

T224-TREATMENT-C010

Failure to meet the requirements of regulation 26 and associated microbiological risk.

Turbidity

T224-TREATMENT-A002

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. Operation of all processes within defined operating ranges with appropriate triggers, responses and contingency procedures.
    Date: Ongoing for the duration of this Notice
  2. Up-to-date and subject to continuous review, site specific disinfection policy, which identifies clearly and unequivocally how disinfection is achieved at the works.
    Date: Ongoing for the duration of this Notice
  3. Continuous monitoring of chlorine dose at the point of dosing, with appropriate alarms and failsafe shutdowns.
    Date: Ongoing for the duration of this Notice
  4. Continuous turbidity and chlorine monitoring at the outlet of Tilmore Reservoir (No. 1 and 2), with appropriate action triggers in place to ensure unwholesome water is not able to enter supply.
    Date: Ongoing until the completion of measure (b)4
  5. Maintain contingency plans (including liaison with relevant stakeholders as appropriate) to protect human health.
    Date: Ongoing for the duration of this Notice
  6. Enhanced operational monitoring for microbiological faecal indicators and chlorine free and total, of water prior to entering Tilmore Reservoir (No. 1 and 2) and at the reservoir outlet.
    Date: Ongoing for the duration of this Notice
  7. Ensure water from Sheet Treatment Works is the only supply of water that can enter Tilmore Reservoir (No. 1 and 2).
    Date: Ongoing until the completion of measure (b)4

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

  1. Relocate the final water monitoring point to the appropriate temporary position at the end of the treatment and disinfection process at Sheet Treatment Works.
    Date: by 28 February 2023 until completion of measure (b)4
  2. Complete initial feasibility scoping to confirm the preferred solution, for progression to design, to enable suitable verification of disinfection and compliance with regulation 26.
    Date: Complete
  3. Complete the detailed design of the preferred solution identified in measure (b)2 above.
    Date: 30 June 2023
  4. Complete the construction, installation and commissioning of the chosen solution, designed under measure (b)3 (including the installation of the permanent final water monitoring point at the end of the treatment and disinfection process at Sheet Treatment Works). Commissioning must include the following to account for the changes made:
  • An appropriate maintenance regime for any installed processes;
  • Full integration of the new processes into the site control and monitoring systems;
  • Updating of the Site-Specific Disinfection Policy and any associated site-specific procedures;
  • Updating of the Site Operating Manual and removal of all out-of-date material from circulation; and
  • Provisions of adequate training for all relevant personnel on the operation, repair and maintenance of the installed process and the revised procedures, policies and manual.
    Date: 31 July 2024
  1. Complete the physical internal inspection of Tilmore No. 2 Service Reservoir.
    Date: 31 March 2023
  2. Complete any identified required remedial work, identified by the internal inspection (measure (b)5), and clean of Tilmore No. 2 Service Reservoir.
    Date: before returning the tank to supply

(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: 31 May 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 Sheet 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. Outline the feasibility scoping outcome and the preferred option being progressed to design, as required under measure (b)2.
    Date: Complete (30 December 2022)
  3. Report outlining the detailed design of the preferred solution to mitigate the identified risk, as required under measure (b)3.
    Date: 31 July 2023
  4. Confirmation of construction, installation and commissioning of the chosen solution as required under measure (b)4.
    Date: 31 August 2024
  5. Report the findings of the internal inspection (measure (b)5), any remedial work completed and the completion of the clean (measure (b)6) of Tilmore No. 2 Service Reservoir.
    Date: within two months of Tilmore No. 2 Service Reservoir’s return to supply
  6. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: 30 June 2023
  7. Submit any revisions of the audit strategy produced under measure (c)2.
    Date: within one month of a revision
  8. 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
  9. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 31 August 2025

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
17 March 2023
Reference: SEW-2018-00005 V3

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