Notice of Regulation: Legacy and Rhos




Legacy (Z06) and Rhos Zones (Z15)

Improvement Programme Database Reference number: HDC-2019-00005


  1. Have received a report from Hafren Dyfrdwy (previously Dŵr Dyffryn Dyfrdwy) (the “company”) dated 5 December 2014 which states that there is or has been a significant risk of supplying water from Legacy works that could constitute a potential danger to human health.
  2. GIVE NOTICE to the company under regulation 28(4) of the Water Supply (Water Quality) Regulations 2018 that it must satisfy the following requirements:

For risks associated with:

  • Manganese


(a) to maintain the following measures for the period specified

  1. DOMS risk based targeted mains cleaning programme
    Date: Ongoing
  2. Use of Manganese Operating Protocol at Legacy treatment works to minimise manganese concentration as far as practical through controlling source water selection and treatment works output
    Date: Ongoing
  3. Weekly sampling in Legacy and Rhos zones for manganese
    Date: Ongoing

(b) to review, revise and/or make operational the following measures, by the date specified:

  1. Determine trunk main lengths for cleaning in Legacy and Rhos zones and submit project plan
    Date: Complete
  2. Carry out trunk main cleaning of identified lengths from (b)1
    Date: Complete
  3. Make operational and maintain the water safety plan for the Legacy supply system
    Date: Ongoing

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

  1. Define a strategy for auditing the effectiveness of the above measures by 31 August 2015; To include:
    • Improvement in discoloured water contact numbers in Legacy and Rhos zone.
      Date: Complete
  2. Implement the audit strategy outlined in (c)1 until revocation of this notice.
    Date: Ongoing

(d) not to supply water for regulation 4(1) purposes from Rhos and Legacy supply zones, or not to 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 risk of supplying water that would constitute a potential danger to human health:

  1. Provide a progress report annually by 31 January and against the following milestones:
    • Completion of audit strategy
      Date: Complete
    • The project plan
      Date: Complete
    • Confirmation of the completion of the trunk mains cleaning
      Date: Complete
  2. Review the risk assessment for Legacy Supply System as required by regulation 27(3) and submit a revised regulation 28(1) report.
    Date: Ongoing
  3. Submit a satisfactory completion report.
    Date: 31 January 2022

Failure by the company to comply with this Notice may result in enforcement proceedings under section 18 of the Act.

Signed by authority of the Welsh Ministers,
Laura Moss
Deputy Chief Inspector
Date: 21 May 2021
DWI Ref: HDC-2019-00005
Version 2

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