Yorkshire Water Services Limited – Chellow Heights WTW Repeat Coliform Detections
Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (as amended)
Reference: YKS-2024-00001
Version Number: 1
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: T4691410
- Chellow Heights WTW: T4691430
- Water Supply System: YSAI00130555
- Water Supply System: YSAI00130844
- Water Supply System: YSAI00130846
- Water Supply System: YSAI00130868
- Water Supply System: YSAI00130872
Details of this Notice:
- The Drinking Water Inspectorate (‘the Inspectorate’) has received a regulation 28(1) report of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the Company dated 15 January 2024, 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 ID |
|---|---|---|
|
Failure of treatment process to prevent coliforms entering supply. |
C001 – Total Coliforms Confirmed |
46623 |
|
Failure of treatment process to prevent E. coli entering supply. |
C002 – E. coli (Faecal Coliforms Confirmed) |
41994 |
- 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:
- Continue with investigations currently being conducted by the company.
Date: Ongoing for the duration of this Notice. - Enhanced sample monitoring of raw waters, inclusive of routine confirmation for positive samples.
Date: Ongoing for the duration of this Notice. - Enhanced sample surveillance monitoring of process and final water.
Date: Ongoing for the duration of this Notice. - Enhanced on-line monitoring of direct microbiological and related parameters, providing a greater understanding of the treatment challenge.
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:
- Complete the research commissioned through Cranfield University into the resistance of Serratia fonticola to chemical disinfection.
Date: 31 March 2024 - Continuation of the upgrades to the Rapid Gravity Filters until completion.
Date: 31 July 2025 - Carry out a full investigation of the Water Treatment Works interstage processes. The investigation is to include:
- Internal inspection of all interstage processes and process streams.
- Sampling of all interstage processes and process streams, inclusive of but not limited to the wastewater system to ensure statistical significance and to account for seasonal variation.
Date: 31 March 2025
- Carry out an investigation of the disinfection process at Chellow Heights water treatment works following the Cranfield University research project. To include empirical data and definition of the disinfection process. Determine hydraulic retention times and plug flow efficiency following any interventions.
Date: 31 March 2025 - Completion of the implementation of improved operational tasks for cleaning of the rapid gravity filters and wastewater system, to ensure effective treatment and reduced bacteriological loading (and associated parameters) within the supernatant return.
Date: 31 June 2024 - Carry out risk assessments of single points of failure found within the process.
Date: 31 March 2025 - As far as is reasonably practicable, establish the root cause of the coliform detections.
Date: 31 March 2025 - Carry out an internal inspection of the East CWT contact tank. The investigation is to include internal inspection, inundation flood testing and sampling prior to return to service.
Date: 31 December 2024 - Specify the long-term plan for Chellow heights Water Treatment Works.
Date: 31 July 2025
(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: 31 May 2024 - 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. - Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
Date: 30 June 2024 - Provide a report detailing the research commissioned through Cranfield University into the resistance of Serratia fonticola to chemical disinfection, as required in step (b)1.
Date: 30 April 2024 - Provide a completion report for upgrades to the Rapid Gravity Filters, as required in step (b)2.
Date: 31 August 2025 - Provide a report detailing the full investigation undertaken of the Water Treatment Works interstage processes, as required in step (b)3.
Date: 30 April 2025 - Provide a report detailing the full investigation of the disinfection process at Chellow Heights water treatment works following the Cranfield University research project, as required in step (b)4.
Date: 30 April 2025 - Provide a report detailing the completion of the implementation of improved operational tasks for cleaning of the Rapid Gravity Filters and wastewater system, as required in step (b)5.
Date: 31 July 2024 - Provide a report detailing the risk assessments of single points of failure found within the process, as required by step (b)6.
Date: 30 April 2025 - Provide a report establishing, as far as is reasonably practicable, the root cause of the coliform detections as required in step (b)7.
Date: 30 April 2025 - Provide a report detailing the internal inspection of the East CWT contact tank, as required in step (b)8.
Date: 31 January 2025 - Provide a report specifying the long-term plan for Chellow heights Water Treatment Works as required in step (b)9.
Date: 31 August 2025 - 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: 31 August 2026
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).
Original Signed
Nicholas Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
12 March 2024
Reference: YKS-2024-00001