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South West Water Limited – AMP8 Stowey WTW

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

Reference: BRL-2023-00006

Version Number: 1

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): South West Water Limited, with registered number 02366665 (hereinafter called ‘the Company’).

Assets Affected:

  1. T25 Stowey Water Treatment Works
  2. WSZ 422 Shepton Mallet, Pilton, Oakhill, Wookey Hole and Shipham
  3. WSZ 425 Blagdon, Clutton, Peasdown, Midsomer Norton and Radstock

Details of this Notice:

  1. The Drinking Water Inspectorate (‘the Inspectorate’) has received a set of regulation 28(1) reports of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the Company dated between 13 June 2017 and 17 May 2022, which state that there is or has been a significant risk of supplying water from Stowey 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

Hazard I D

Underperformance of pre-ozonation system leading to reduced organics removal through the works and promotion of biofilm downstream

Total Coliforms

T25Hazard1156

Organic loading from SSFs and potential for biofilm formation downstream

Total Coliforms

T25Hazard1158

UV biofilm growth

Total Coliforms

T25Hazard0914

Formation of Trihalomethanes in distribution network

Trihalomethanes (THMs)

Z422Hazard0029

Formation of Trihalomethanes in distribution network

Trihalomethanes (THMs)

Z425Hazard0031

Table 1: 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. Maintain the regular cleaning of the UV system with the Clean in Place (CIP) system at Stowey Water Treatment Works (WTW).
    Date: Ongoing for the duration of this Notice.
  2. Maintain regular physical cleaning of the UV reactors at Stowey WTW.
    Date: Ongoing for the duration of this Notice.
  3. Manage the chlorine dose at Stowey WTW to ensure chlorine residual is maintained.
    Date: Ongoing for the duration of this Notice.
  4. Continue to operate Stowey WTW treatment process to ensure compliance with regulation 26 and regulation 4 of the Regulations.
    Date: Ongoing for the duration of this Notice.
  5. Maintain monitoring in line with frequencies defined in the audit strategy.
    Date: Ongoing for the duration of this Notice.
  6. Maintain statutory sampling as defined in the Regulations.
    Date: Ongoing for the duration of this Notice.

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

  1. Complete the technology evaluation, including piloting to confirm the chosen solution.
    Date: 31 October 2025
  2. Complete the detailed design of the chosen solution and commence construction of the chosen solution.
    Date: 31 March 2027
  3. Complete the installation and commissioning of the chosen solution at Stowey WTW.
    Date: 31 March 2029

(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 2024
  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 Stowey 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. Confirm completion of the technology evaluation and chosen solution, as described in (b)1.
    Date: 30 November 2025
  3. Confirm completion of the detailed design and commencement of construction, as described in (b)2.
    Date: 30 April 2027
  4. Confirm completion of the installation and commissioning of the chosen solution.
    Date: 30 April 2029
  5. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: 30 June 2024
  6. Submit any revisions of the audit strategy produced under measure (c)2.
    Date: Within 1 month of a revision.
  7. 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.
  8. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 30 April 2030

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
13 March 2024
Reference: BRL-2023-00006

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