Dwr Cymru Cyfyngedig – Maerdy Treatment Works
Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2018
Reference: DWR 2023 00001
Version Number: 1
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:
|
Asset Name |
Reference |
|---|---|
|
Maerdy WTW Final (L/L @ Ferndale) Maerdy WTW Final (H/L @ Maerdy) |
T67358 T67357 |
Details of this Notice:
- The Drinking Water Inspectorate (‘the Inspectorate’) has received a series of regulation 28(1) reports of the Water Supply (Water Quality) Regulations 2018 (‘the Regulations’) from the Company dated, 4 November 2022, 14 December 2022 and 15 January 2023 which states that there is or has been a significant risk of supplying water from Maerdy Treatment Works (and associated assets as applicable) that could constitute a potential danger to human health or could be unwholesome.
- 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:
|
Hazard/ Hazardous Event/ Parameter |
Hazard I D | |
|---|---|---|
|
Turbidity >1 NTU at the end point of disinfection |
Turbidity |
D102326 |
|
Manganese >50 µg/l in the final water and the Maerdy / Porth Supply Zone |
Manganese |
D138244 |
|
The risk of sub-optimal clarifier and filter performance |
Cryptosporidium and turbidity |
D102325 |
|
The risk of short-circuiting Ct in the contact tanks |
Coliforms including E. coli |
D138245 |
|
The risk of chlorate formation |
Chlorate |
D188104 |
- 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:
- Continuous online monitoring of turbidity in the final water and “point of disinfection” monitoring points with appropriate alarms and failsafe shutdowns where applicable.
Date: Ongoing for the duration of this notice.
- Operation of all processes within defined operating ranges with appropriate triggers, responses and contingency procedures.
Date: Ongoing for the duration of this notice.
- Continuous monitoring for Cryptosporidium in the final water.
Date: Ongoing for the duration of this notice.
- Continuous monitoring of raw and treated water with control systems, alarmed operating limits and automatic shutdown as appropriate.
Date: Ongoing for the duration of this notice.
- Ensure that turbidity monitoring equipment is maintained in-line with manufacturers’ instructions.
Date: Ongoing for the duration of this notice.
- Up-to-date and subject to ongoing 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.
- Maintain contingency plans (including liaison with relevant stakeholders as appropriate) to protect human health.
Date: Ongoing for the duration of this notice.
- Continue regular and reactive monitoring for chlorate at the works final. Review the frequency of sampling whilst the risk of elevated chlorate is assessed as high.
Date: Ongoing for the duration of this notice.
- Respond as required if chlorate results are found to be above the World Health Organisation guideline value of 700 µg/l or company trigger value.
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:
- Conduct a critical review of compliance with regulation 26(1)(b) and 26(6)(b) at Maerdy Water Treatment Works to ensure water leaving the treatment works has received sufficient preliminary treatment to prepare it for disinfection. This review must assess the risk from turbidity and manganese carryover into the downstream network and the resulting implications.
Date: 31 December 2023
- Conduct a critical review of compliance with regulation 26(4) at Maerdy Water Treatment Works to ensure water leaving the treatment works has been subject to adequate disinfection. This review must include results from a tracer test or Computational Fluid Dynamics (CFD) to assess the risk of short-circuiting in the contact tanks.
Date: 31 December 2023
- Investigate and implement any required measures to ensure continuous online turbidity monitoring at the start of disinfection, at any point where the company considers there is a risk water quality may deteriorate and as soon as possible after the point where disinfection has been completed. Appropriate mitigation measures should be in place in case of monitor failure.
Date: 31 October 2023
- Investigate and implement measures to ensure turbidity is less than 1 NTU prior and during the disinfection stage (from the point of initial disinfection monitoring point to the point where disinfection is calculated as completed) at Maerdy water treatment works. This is including but not limited to cleaning and maintaining the contact main between the works and the contact tanks at Maerdy H/L and Ferndale L/L.
Date: 31 March 2024
- Design a solution to address any risks identified through the completion of the review required under measure (b)(1). Confirm completion date for this work, (b)(6).
Date: 31 March 2024
- Implement or install and commission (as appropriate) the chosen solution designed under measure (b)(5).
Date: 31 March 2025
- Design a solution to address any risks identified through the completion of the review required under measure (b)(2). Confirm completion date for this work, (b)(8).
Date: 30 September 2024
- Implement or install and commission (as appropriate) the chosen solution designed under measure (b)(7).
Date: 31 March 2026
- Review and update the site-specific disinfection policy as appropriate, following the completion of the review required under measure (b)(1) and (b)(2).
Date: 31 January 2024
- Conduct a critical review and identify short and long term actions to mitigate against the risk of chlorate formation at Maerdy water treatment works to ensure compliance with regulation 31(2)(b).
Date: 31 December 2023
- Implement or install and commission (as appropriate) the actions identified under (b)(10).
Date: 31 December 2024
(c) To audit whether the measures have been effective by the following means:
- Define an audit strategy to monitor the effectiveness of the measures specified in sections (a) and (b).
Date: 30 November 2023
- 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 Maerdy Treatment Works, 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:
- Provide a progress report annually.
Date: by 31 January each year.
- Report the findings of the review completed under (b)(1) and resulting measures implemented.
Date: 31 January 2024
- Report the findings of the review completed under (b)(2) and resulting measures implemented.
Date: 31 January 2024
- Report the findings of the investigation completed under (b)(3) and resulting measures implemented.
Date: 30 November 2023
- Report the findings of the investigation completed under (b)(4) and resulting measures implemented.
Date: 30 April 2024
- Submit a report outlining the chosen solution (measure (b)(5) and confirm the date for completion of measure (b)(6) (if different from below).
Date: 30 April 2024
- Confirm completion of measure (b)(6).
Date: 30 April 2025
- Submit a report outlining the chosen solution (measure (b)(7) and confirm the date for completion of measure (b)(8).
Date: 31 October 2024
- Confirm completion of measure (b)(8).
Date: 30 April 2026
- Confirmation of completion of measure (b)(9)
Date: 28 February 2024
- Outline the findings of the review required under (b)(10) and confirm required actions to mitigate the risk of chlorate formation. Confirm completion date for this work, (b)(11).
Date: 31 January 2024
- Confirmation of completion of measure (b)(11).
Date: 31 January 2025
- Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)(1).
Date: 31 December 2023
- Submit any revisions of the audit strategy produced under measure (c)(2).
Date: Within 1 month of a revision
- 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
- Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
Date: 30 April 2027
Further Details of this Notice:
- Any product or substance used as a result of the requirements in this notice must comply with regulation 31.
- Under regulation 28(6) the Inspectorate, on behalf of the Welsh Ministers, may by notice served on the Company, revoke or vary this notice.
- 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 Welsh Ministers
2 October 2023
Reference: DWR 2023 00001