Dwr Cymru Cyfyngedig – AMP8 Capel Curig THMs

Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2018

Reference: DWR-2023-00009

Version Number: 2

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
Ffynnon Llugwy	C607817
Capel Curig WTW Final	T607832
Capel Curig	Z2009B32

Table 1: List of assets affected and associated reference numbers

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 2018 (‘the Regulations’) from the Company dated 31 July 2023, which states that there is or has been a significant risk of supplying water from Capel Curig 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 Welsh Ministers, under regulation 28(4) for the assets listed above, for risks associated with:

Description of Risk	Hazard/ Hazardous Event/ Parameter	Hazard I D
Potential for elevated levels of TOC [in treated water leaving the WTW] due to its presence in the raw water.	Total Organic Carbon	D134053
Risk of high levels of TOC in raw water having an impact on downstream treatment process which are incapable of satisfactory removal.	Trihalomethanes	D176570
Elevated levels of organics or THM precursors in the raw water contributing to THM levels greater than 50ug/l (50% PCV) at the final water sampling point and the potential risk of Disinfection by Products in distribution.	Risk of elevated levels of THM and other disinfection byproducts.	D108936
Risk of elevated disinfection by-products concentrations in network and at customers tap due to elevated precursors in raw water and ineffective treatment and removal at treatment works.	Potential for elevated THM levels	D90947

Table 2: Table of the hazards, hazardous events, and/or parameters covered by this notice, including the Hazard I D numbers and the description of risks.

3. 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. Continue to optimise the existing treatment process to minimise the level of THMs entering supply, including disinfection and water age.
   Date: Ongoing for the duration of this Notice
2. Enhanced monitoring of final water for THMs (dichlorobromomethane, dibromochloromethane, trichloromethane, tribromomethane and total trihalomethanes) at a minimum of weekly frequency.
   Date: Ongoing for the duration of this Notice
3. Provision of temporary, alternative supply should the THM levels exceed PCV at the customer tap in accordance with the existing total loss contingency plan for the Capel Curing WTW, as outlined in the audit strategy.
   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. Review and confirm the appropriateness of the proposed solution to install pipework, pumping stations and associated distribution networks to supply the downstream network from Llyn Conwy water treatment works and decommission Capel Curig water treatment works.
   Date: 31 March 2025
2. Confirm completion of design and expected start date for construction of the agreed solution.
   Date: 31 March 2027
3. Complete construction and commissioning of the agreed solution.
   Date: 31 March 2030

(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 Capel Curig 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. Confirmation of the appropriateness of the proposed solution.
   Date: 30 April 2025
3. Confirm completion and provide details of the design and expected start date for construction of the proposed solution.
   Date: 30 April 2027
4. Confirm completion of construction and commissioning of the proposed solution.
   Date: 30 April 2030
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 2031

Further Details of this Notice:

4. Any product or substance used as a result of the requirements in this Notice must comply with regulation 31.
5. Under regulation 28(6) the Inspectorate, on behalf of the Welsh Ministers, may by notice served on the Company, revoke or vary this Notice.
6. 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
05 April 2024
Reference: DWR-2023-00009 v2