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South West Water Limited – AMP7 St Cleer Water Treatment Works

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

Reference: SWT-2018-00003

Version Number: 4

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:

  • St Cleer WTW, T5330F
  • St Cleer Supply System, Y5330

Details of this Notice:

  1. The Drinking Water Inspectorate (‘the Inspectorate’) has received a regulation 28(1) report of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the Company dated 21 December 2017, which states that there is or has been a significant risk of supplying water from St Cleer Water Treatment Works (and associated assets as applicable) that 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

Potential risk of discolouration associated with manganese oxidation in the network.

Manganese

294090; 198.

Consumer acceptability relating to discolouration.

Discolouration

22

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. Enhanced operational monitoring for the iron, manganese and turbidity parameters for the water leaving St Cleer works, and within the water supply zones covered by this notice.
    Date: Ongoing for the duration of this Notice
  2. Optimisation of current treatment processes within the operational limits that have an impact on discolouration parameters.
    Date: Ongoing for the duration of this Notice
  3. Continue water quality monitoring in the water supply zones supplied by St. Cleer works.
    Date: Ongoing for the duration of this Notice
  4. Respond to any PCV failure or consumer contact, relating to discolouration parameters, in line with company procedures.
    Date: Ongoing for the duration of this Notice
  5. Record, monitor and analyse consumer contacts received within the zones supplied by St Cleer works in appropriate detail and as required for the DWI annual return. React to consumer contacts as appropriate and ensure that this information is built into future plans for improvement works and remediation within the zones.
    Date: Ongoing for the duration of this Notice
  6. Define and carry out reactive flushing in zones where necessary as dictated by an increase in consumer contacts within a zone supplied by St Cleer works, or by a breach of the iron, manganese or turbidity parameter.
    Date: Ongoing for the duration of this Notice
  7. Liaison with local and public health authorities following on from any PCV failure, in line with company procedures.
    Date: Ongoing for the duration of this Notice
  8. Inform on-going raw water risk assessment by enhanced monitoring.
    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. Plan and develop the outline design of the long-term solution to reduce final water manganese concentrations.
    Date: Complete
  2. Award the full contract for the construction of the chosen solution.
    Date: Complete
  3. Develop the detailed design of the chosen solution.
    Date: Complete
  4. Complete the construction, installation and commissioning of the long-term solution.
    Date: 30 September 2025

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

  1. Update and confirm the strategy for auditing the effectiveness of the above measures to include as a minimum:
    • Enhanced monitoring of raw and final water for manganese concentration at the supplying works, relevant downstream service reservoirs and from consumer taps within zones ZC9, and ZP1. Complete a monthly review of this data.
    • Develop and initiate an action plan for use when results from monitoring of works or zones covered by this notice are not within the expected ranges.
    • Target a reduction in zonal manganese to less than 5 µg/l.
    • Secure compliance with the manganese standards and a reduction in discoloured water consumer contacts.
    • Monthly monitoring of any consumer complaints.
    • An appropriate operational monitoring regime for manganese at St Cleer works.
      Date: Complete
  1. 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 St Cleer 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. Complete and submit a review of the long-term measures proposed, to confirm the long-term solution. The review shall include a report on any foreseeable risk to disinfection, and how the company intends to mitigate them. Include commentary on whether there is a risk of shielding pathogens due to Manganese particle formation in the chlorine contact tank after the current pre-filter chlorine dosing is stopped. The review shall also include an updated schematic diagram on what the works will look like post implementation of this scheme.
    Date: Complete
  3. Confirm completion of the outline design of the final solution proposed.
    Date: Complete
  4. Confirm and evidence the award of the full contract for the construction of the chosen solution.
    Date: Complete
  5. Provide the detailed design of chosen solution.
    Date: Complete
  6. Confirm completion of construction, installation and commissioning of the chosen long-term solution.
    Date: 31 October 2025
  7. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: Complete
  8. Submit any revisions of the audit strategy produced under measure (c)2.
    Date: Within 1 month of a revision
  9. 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
  10. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 31 October 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

Nick Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
10 December 2024
Reference: SWT-2018-00003 v4

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