Notice of Regulation: Chellow Heights – AMP7 Disinfection By-products
Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (as amended)
Yorkshire Water Services Limited – Chellow Heights AMP7 Disinfection by Products
Reference: YKS-2018-00005
Version Number: 3
Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): Yorkshire Water Services Limited, with registered number 02366682 (hereinafter called ‘the company’).
Assets Affected:
- Chellow Heights WTW Inlet Nidd Combined (A4611400);
- Chellow Heights WTW Inlet Stubden (A4611410);
- Chellow Heights WTW Inlet Chelker (A4611395);
- Chellow Heights WTW (T4691410; T4691430; T4691440);
- Chellow Heights Water Supply System (YSAI00130844).
Details of this notice:
- The Drinking Water Inspectorate (‘the Inspectorate’) has received a set of regulation 28(1) reports of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the company dated between 20 September 2018 and 13 December 2021, which states that there is or has been a significant risk of supplying water from Chellow Heights water 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 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 |
|---|---|---|
|
Water Quality issues due to DBP levels. |
Disinfection by-products |
17489; 17490 |
|
Water Quality issues due to DBP levels. |
Trihalomethanes |
17489; 17490 |
|
Failure of treatment process to remove taste and odour causing compounds from raw water. |
Taste (Quant) |
25141 |
|
Failure of treatment process to remove taste and odour causing compounds from raw water. |
Odour |
25140 |
- The company is 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:
- Continue to regularly monitor raw water trends for the parameter colour and keep under review dissolved organic carbon trends from on-line monitoring (UV254).
Date: Ongoing for the duration of this notice - Optimise existing processes to minimise the risk of DBP formation.
Date: Ongoing for the duration of this notice - Regularly monitor treated, stored, and distributed water for disinfection by-products (trihalomethanes and halo acetic acids).
Date: Ongoing for the duration of this notice - Continue to review opportunities for catchment management activities with stakeholders and implement protective measures, where feasible, to improve raw water quality and reduce disinfection by-product precursors.
Date: Ongoing for the duration of this notice - Regularly monitor treated water, water within key service reservoirs, and distributed water for DBPs (THMs and HAAs).
Date: Ongoing for the duration of this notice - Regularly review the level of residual DOC remaining from raw water following the existing processes and ensure its removal is optimised (including the optimisation of coagulation pH and coagulant dose, and the minimisation of RGF turbidity). Regularly review WTW performance within Water Quality and Production Operational teams to maintain optimised conditions.
Date: Ongoing for the duration of this notice - Continuously review the raw water challenges and the effectiveness of the catchment mitigation measures at controlling the raw water risks against the appropriateness of the treatment at Chellow Heights works to mitigate the raw water risks.
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:
- Confirm the chosen solution and provide outline design for additional removal of DOC from the Nidd Aqueduct inlet, following engineering and process reviews and, where required, pilot trials.
Date: Complete - Provide a detailed design of the proposed solution.
Date: Complete - Review and update the analytical method and sampling procedure for the raw water sources supplying Chellow Heights WTW to ensure that sampling, reporting of results and any required actions are clearly defined. Consideration should be given for species level identification of cyanobacteria to recognise whether taste and odour producing cyanobacteria are present in raw water sources. Train all relevant staff on the updated procedure.
Date: 31 December 2022 - Develop a taste and odour mitigation plan (MIB and Geosmin) for Chelker IRE, Stubden IRE and the Nidd sources, to ensure appropriate triggers are in place to enhance monitoring and shorten analytical turnaround time for samples for improved response and escalation, with consideration for any additional treatment onsite that may be required. To include:
- Process optimisation steps to mitigate against the risk of taste and odour;
- Appropriate escalation in response to onsite taste and odour checks.
Date: 31 December 2022
- Install and commission additional monitors on the raw water network supplying Chellow Heights to provide real time data of UV254, turbidity, and flow at the identified strategic points within the Nidd Valley and at the Stubden inlet.
Date: 31 December 2023 - Retrain the pollution monitor/spectral analyser at Lobwood to identify deterioration in raw water quality and develop appropriate alarms and actions to manage water pumped from the River Wharfe to Chelker reservoir.
Date: 31 August 2023 - Develop a procedure for appropriate escalation between all of the raw water teams, catchment teams, water quality scientists, and site production teams in the Chellow Heights supply system. This should be in addition to regular communications between these teams. Appropriate escalation procedures should be defined for visual changes in raw water quality across the raw water sources supplying Chellow Heights WTW; sample results that are outside normal operating levels; and site production observations on raw water changes (e.g. smell bell detections).
Date: 31 December 2022 - Train all relevant staff on the plan and procedure developed in (b)4 and (b)7, respectively and on the response to alarms from the retrained spectral analyser at Lobwood (as specified in (b)6). In addition, ensure that all of the raw water teams, catchment teams, water quality scientists, and site production teams in the Chellow Heights supply system are trained on changes in raw water quality and the associated impacts on final water.
Date: 31 March 2023. - Install, commission, and verify through testing, the chosen solution.
Date: 31 March 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). To include
- Sampling and data analysis for DBPs (THMs and HAAs) with a focus on ex-works and distributed water
- Development of an auditable means by which the company will demonstrate minimisation of DBP risks at the upgraded works under all raw water conditions.
31 October 2022
- 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 Chellow Heights Water 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. - Completion of investigations, pilot trials and development of outline design.
Date: Complete - Completion of the detailed design of the proposed solution.
Date: Complete - Provide the updated analytical method and sampling procedure for the raw water sources supplying Chellow Heights WTW following the review completed in (b)3.
Date: 31 January 2023 - Provide the taste and odour mitigation plan for the raw water sources supplying Chellow Heights water treatment works, as specified in (b)4.
Date: 31 January 2023 - Confirm the installation and commissioning of the raw water monitors across the Chellow Heights raw water supply system, as specified in (b)5.
Date: 31 January 2024 - Provide a report confirming the re-training of the spectral analyser at Lobwood demonstrating appropriate alarms and actions are in place to respond to deteriorations in raw water quality.
Date: 30 September 2023 - Provide the procedure developed in (b)7.
Date: 31 January 2023 - Confirm completion of training for all relevant staff on the procedures developed in (b)4 and (b)7 and on the response/actions from the re-trained spectral analyser, as specified in (b)8. Provide evidence demonstrating relevant staff have been trained on these procedures.
Date: 31 October 2023 - Confirm the installation, commissioning and verification of the chosen solution.
Date: 30 April 2024 - Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
Date: 30 November 2022 - 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 2025
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 Secretary of State, 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 Secretary of State for Environment, Food and Rural Affairs
23 September 2022
Reference: YKS-2018-00005 (V3)