Notice of Regulation: Cwm Taff

NOTICE UNDER REGULATION 28(4) OF THE WATER SUPPLY (WATER QUALITY) REGULATIONS 2018

Dwr Cymru Cyfyngedig: Cwm Taff Water Treatment Works

Reference: DWR-2018-00001

Water undertaker as appointed under section 6 of The Water Industry Act 1991 (as amended): Dwr Cymru Cyfyngedig, with registered number 02366777 (hereinafter called ‘the Company’).

Assets affected:
T67151 Cantref, T67149 Llwynon and T67034 Pontsticill
WQZ: Y8120 Pontsticill Low Level

  1. The Drinking Water Inspectorate (‘the Inspectorate’) has received a regulation 28(1) report of the Water Supply (Water Quality) Regulations 2018 (‘the Regulations’) from the Company dated 30 May 2018, which states that there is or has been a significant risk of supplying water from Cantref, Llwynon and Pontsticilli water treatment works (and associated assets as applicable) that could constitute a potential danger to human health.
  2. Consequently, this Notice is served on the Company by the Inspectorate on behalf of the Welsh Ministers, under regulation 28(4) for the assets listed above, for risks associated with:
  • Raw water deterioration
  • Resilience of supply
  • Taste and Odour
  • Regulation 26(4) – design and continuously operate an adequate treatment process for the water source

  1. The Company are required to satisfy the following:

Requirements

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

  1. Develop and implement mitigation action plans for raw water deterioration and the presence of Geosmin and/or MIB above taste & odour thresholds in treated water leaving Cantref, Llywnon and Pontsticill WTW, to include;
    Date: Ongoing for the duration of this Notice
    • Early initiation of Powdered Activated Carbon (PAC) dosing on reaching pre-defined triggers of concentration of Geosmin and/or MIB.
    • Use of company designed Critical Parameter Board with defined triggers and escalation processes.
    • Regular and routine reviews of customer contacts.
    • Raw water source management including use of alternative reservoir draw offs and technologies to reduce algal blooms and reservoir stratification.
  2. Enhanced operational monitoring for taste and odour for the water leaving Cantref, Llwynon and Pontsticill works and within the water supply zones covered by this notice.
    Date: Ongoing for the duration of this Notice
  3. Optimisation of current treatment processes within the operational limits that have an impact on taste and odour parameters.
    Date: Ongoing for the duration of this Notice
  4. Continue water quality monitoring in the water supply zones supplied by Cantref, Llwynon and Pontsticill works.
    Date: Ongoing for the duration of this Notice
  5. Record, monitor and analyse consumer contacts received within the zones supplied by Cantref, Llwynon and Pontsticill works to examine trends and identify issues and as required for the DWI annual return. React to consumer contacts as appropriate.
    Date: Ongoing for the duration of this Notice
  6. 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
  7. Maintain Cantref, Llwynon and Pontsticill works to ensure risks detailed in section 2 above are mitigated until such time that the works are decommissioned.
    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:

Phase 1 – Development of Zonal Care Plan

  1. Implement the zonal Care Plan for Z1052N10 – Merthyr/Abercynon zone.
    Date: By 31 March 2020 and maintain through the duration of the Notice

Phase 2 – Pengarnddu SRV

  1. Inform an ongoing raw water risk assessment by enhanced monitoring for taste and odour causing compounds
    Date: Ongoing from date of issue of notice
  2. Develop a suitable audit strategy
    Date: By 31 March 2021

Phase 3 – Design and Build of final Water storage

  1. Confirm the design and delivery programme for a 150Ml storage tank and associated pumping station and network connections on the site of the new WTW. This tank is to provide treated water storage from the three existing sites at Cantref, Llwynon and Pontsticill until the new Cwm Taff WTW facilities are constructed and commissioned.
    Date: By 31 March 2025
  2. Construct and commission the 150Ml storage tank and associated pump station and network connections.
    Date: By 31 March 2030

Phase 4 – Design and Build of Cwm Taff WTW

  1. Confirm the design and delivery programme for a single WTW (Cwm Taff) to replace the existing three assets (Cantref, Llwynon and Pontsticill).
    Date: By 31 March 2025
  2. Construct and commission Cwm Taff WTW and associated network connectivity to facilitate the decommissioning of Cantref, Llwynon and Pontsticill WTWs.
    Date: By 31 March 2030
  3. Complete a Zonal Study of Z1052N10 Merthyr/Abercynon Zone following the construction of the new ‘Cwm Taff’ WTW to identify any further network remediation.
    Date: By 31 March 2031

(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 section (a) and (b).
    Date: Ongoing and for the duration of the Notice
    • Ensuring the current works are maintained and optimized for treatment of taste and odour causing compounds and continue optimisation until the new works is fully operational.
    • Develop and initiate a commissioning plan for the new works.
    • Utilise results from the pilot trial of the new works to inform outcomes of future decisions made.
    • Enhanced monitoring of taste and odour causing compounds at the supplying works, relevant downstream service reservoirs and from consumer taps within zones supplied from the works. 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 customer contacts reporting taste and odour on supply as a result of the presence of MIB and Geosmin at concentrations above taste and odour thresholds. This will be measured through the annual submission of customer contacts to DWI as well as notification of events as appropriate.
  2. Improved resilience of supply – demonstrated fewer WTWs outages that result in customer impact of loss of supply.
    Date: Demonstrated from 2030
  3. Implement, and keep under continuous review, the audit strategy defined in measure (c)1.Following completion of measure (c)1.
    Date: onwards

(d) not to supply water for regulation 4(1) purposes from Cantref, Llywnon or Ponsticilli, or not to so supply unless the specified conditions below are satisfied:

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 by 31 January and against the following milestones:Annually by 31 January
    • Implement a zonal Care Plan for Z1052N10 – Merthyr/Abercynon zone.
      Date: 30 April 2020 (Complete)
    • Confirm the design and delivery programme for a 150Ml storage tank and associated pumping station and network connections on the site of the new WTW.
      Date: 30 April 2025
    • Construct and commission the 150Ml storage tank and associated pump station and network connections.
      Date: 30 April 2030
    • Confirm the design and delivery programme for a single WTW (Cwm Taff) to replace the existing three assets (Cantref, Llwynon and Pontsticill).
      Date: 30 April 2025
    • Construct and commission Cwm Taff WTW and associated network connectivity to facilitate the decommissioning of Cantref, Llwynon and Pontsticill WTW’s
      Date: 30 April 2030
    • Review the risk assessment for Y8120 Pontsticill Low Level as required by regulation 27(4) and subsequently submit a revised regulation 28 report accompanied by a signed board level declaration.
      Date: Ongoing through the duration of the Notice
    • Complete a Zonal Study of Z1052N10 Merthyr/Abercynon Zone following the construction of the new ‘Cwm Taff’ WTW to identify any further network remediation.
      Date: 30 April 2031
  2. Submit any revisions of the audit strategy produced under measure (c)3.
    Date: Within 1 month of a revision
  3. Submit a report in the event that any completed measure of this Notice needs 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 May 2032

  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 Welsh Ministers, 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
Milo Purcell
Deputy Chief Inspector, on behalf of the Welsh Ministers
26 March 2021
Reference: DWR-2018-00001
Version 4

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