Notice of Regulation: Southern Water – Otterbourne Water Supply Works

NOTICE UNDER REGULATION 28(4)THE WATER SUPPLY (WATER QUALITY) REGULATIONS 2016 (AS AMENDED)

Southern Water Services Ltd : Otterbourne Water Supply Works

Reference: SRN3698

Version: 5

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): Southern Water Services Limited, with registered number 02366670 (hereinafter called ‘the Company’). 

Assets affected

  • TH002 – Otterbourne Ground Water WSW
  • TH003 – Otterbourne Surface Water WSW
  • Y002 – Otterbourne Supply System

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 2016 (as amended) (‘the Regulations’) from the Company dated 6 September 2017, which states that there is or has been a significant risk of supplying water from Otterbourne WSW (and associated assets as applicable) that constitute a potential danger to human health.
  2. 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: 

Hazard/Hazardous Event/Parameter

Hazard ID

Description of Risks

Cryptosporidium

29774 / 29836

Breakthrough presenting risk to public health.

Turbidity

69629 / 69630

Compromised disinfection process 

E. coli

29778 / 29840

Ingress route and failure of treatment process

Total Coliforms 

29777 / 29839

Ingress route and failure of treatment process 

Enterococci 

29779 / 29841

Ingress route and failure of treatment process 

Clostridium Perfringens

29775 / 29837

Ingress route and failure of treatment process

Taste 

Odour 

29825 / 29887 

29826 / 29888

Failure of treatment poses risk to wholesomeness

  1. The Company are required to satisfy the following requirements. 

The date given (the ‘date’) is that until or by which the requirements must be maintained or satisfied, as appropriate. 

Requirements:

(a) to maintain the following measures for the duration of the Notice.

  1. Establish and maintain in place until improvement works are completed such enhanced operational measures as necessary to ensure that consumers are protected and water supplied from the site is adequately treated and wholesome.
    Date: Ongoing for duration of Notice
  2. Annual cleaning of clarifiers and sedimentation tanks.
    Date: Ongoing for duration of Notice
  3. Undertake jar tests to inform coagulant dose requirements at a frequency commensurate to regularity of treatment changes.
    Date: Ongoing for duration of Notice
  4. Review the rapid gravity filter (RGF) trends on a daily basis, investigate and resolve any unusual trends.
    Date: Ongoing for duration of Notice
  5. Review routinely and test alarms on the RGF system.
    Date: Ongoing for duration of Notice
  6. Implement a comprehensive set of MSTs for maintenance and cleaning of the microfiltration plant and the instrument sample lines.
    Date: Ongoing for duration of Notice
  7. Enhanced monitoring (as a minimum 3 times per week) for Cryptosporidium in the raw and treated water.
    Date: Ongoing for duration of Notice
  8. Enhanced monitoring for coliforms and E. coli in the treated water supplied by Otterbourne WSW.
    Date: Ongoing for duration of Notice
  9. Monitoring on a weekly frequency for animalcules in the raw and treated water.
    Date: Ongoing for duration of Notice
  10. Create and follow site specific operating plan for filter backwashes, including visual checks of backwashes every day.
    Date: Ongoing for duration of Notice
  11. Flush the supernatant return turbidity monitor daily.
    Date: Ongoing for duration of Notice
  12. Calibrate coagulant flow monitors at a frequency commensurate with treatment changes and as a minimum in line with manufacturer’s instructions.
    Date: Ongoing for duration of Notice
  13. Continually review and optimise the clarifier desludging process.
    Date: Ongoing for duration of Notice
  14. Monitor the ferric concentration on the clarifier and sedimentation tank outlet.
    Date: Ongoing for duration of Notice

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

  1. Carry out a robust investigation to identify the source of Cryptosporidium and pathway into supplies from Otterbourne Ground and Surface Works.
    Date: Complete
  2. Identify all options for additional risk mitigation to secure the long term protection of public health to consumers receiving water from the Otterbourne Ground and Surface Works’ supply system. Assess the risk of shortcircuiting of flow through the RGFs. Take action to alter the flow if any filters are found to have a significant Cryptosporidium risk due to shortcircuiting of flow.
    Date: Complete
  3. Update the regulation 28 risk assessment for the site and supply system upon the conclusion of the above investigation.
    Date: Complete
  4. Replace sodium hypochlorite storage tanks.
    Date: Complete
  5. Model flows within the contact tanks, taking into account the balance pipe between the ground water and surface water contact tanks, to review whether Regulation 26 is breached under any flow scenario. If the review identifies that disinfection could be compromised at any time, undertake remedial measures.
    Date: Complete
  6. Review and implement measures required to ensure that routine maintenance of the disinfection system at Otterbourne GWTW can be carried out without risk of breaching Regulation 26 of the Water Supply (Water Quality) Regulations 2016.
    Date: Complete
  7. Improve asset condition, resilience and control of the RGF including:
    Date: Complete
    • Replace outlet valve and backwash valve mechanism.
    • Replace main dose chlorine filtered water channel covers.
    • Seal RGF outlet valve covers to prevent vermin ingress, check outlet valve covers, record and action findings as part of routine operations.
    • Clean RGF outlet channels.
    • Replace media and refurbish underdrain system.
  8. Review and update equipment and procedures relating to all dosing pumps at Otterbourne ground and surface works (except carbon dosing, referenced in xi below) to mitigate the risks of under or over dosing chemical including installation of an automatic coagulation control system.
    Date: Complete
  9. Install orthophosphoric delivery bund.
    Date: Complete
  10. Install auto shutdown on low lift pumping station (abstraction).
    Date: Complete
  11. Replace ferric dosing system.
    Date: Complete
Chemical storage and dosing:
  1. Provide polyelectrolyte duty standby dosing pumps in accordance with SWS standards.
    Date: By 30 June 2022
    1. Review the carbon treatment system in context of the long-term water resources plan.
      Date: 31 December 2022
    2. Construct and commission new carbon treatment system.
      Date: By 31 December 2026
  2. Ensure the main dose hypo dosing is compliant with SWS standards
    Date: By 30 June 2022
  3. Install new hypo dosing system, controls and monitoring.
    Date: By 30 June 2022
UV and contact tank:
  1. Complete repurposing of the existing contact tank in line with new disinfection strategy
    Date: By 30 June 2022
  2. Design and build a new combined surface and groundwater capacity contact tank and associated dosing systems for the full, combined works flow.
    Date: By 30 June 2022
  3. Construct and commission ultraviolet treatment for the full, combined works flow.
    Date: By 30 June 2022
  4. Install and commission new intermediate and high lift pumps, including sample points.
    Date: By 30 June 2022
  5. Install and commission new final run to waste facility to ensure non-compliant water cannot enter distribution
    Date: By 31 December 2022
Maintenance and improvements to existing works:
  1. Refurbish the low lift pumping station (abstraction).
    Date: By 30 June 2022
  2. Carry out repairs to the RGF hall roof, install ventilation, replace non-compliant handrail and install new backwash pumps in accordance with SWS standards.
    Date: By 31 December 2022
  3. Replace the wash water pump.
    Date: By 31 August 2023
  4. Improve access to clarifier sedimentation tanks for more regular cleaning.
    Date: By 31 March 2025
  5. Improve access to the groundwater works balancing tank for increased regular cleaning.
    Date: By 31 March 2025
  6. Assess the condition of the MCC4 and associated equipment, refurbish and replace where required.
    Date: By 31 March 2025
Abstraction and borehole works:
  1. Complete borehole and well improvements including;
    Date: By 30 June 2022
    • Flood mitigation for all BHs including raising BH headworks C
    • Refurbish headworks
    • Install individual Turbidity monitoring and control
    • Decommission borehole D
    • Ensure the wells are secured to prevent ingress
  2. Ensure appropriate power supply resilience for each borehole.
    Date: By 31 March 2025
    1. Assess the abstraction transformer bunds
      Date: By 31 December 2022
    2. Ensure transformer compliance
      Date: By 31 March 2023
  3. Assess the structural integrity of the borehole access bridge and carryout necessary remediation
    Date: By 31 March 2025
  4. Provide Bore Hole run to waste facilities
    Date: By 31 March 2025
Site control:
  1. Replace site monitoring and control systems
    Date: By 30 June 2022
  2. Upgrade SCADA & WQSD.
    Date: By 30 June 2022
  3. Install new RGF PLC.
    Date: By 30 June 2022
  4. Replace post RGF turbidity monitors.
    Date: By 31 December 2022
  5. Provide individual borehole pump controls.
    Date: By 31 March 2025
  6. Repair or replace the river ammonia monitor.
    Date: By 31 March 2025
  7. Add visibility of the alarm status of the band screens to SCADA
    Date: By 31 March 2025
  8. Improve visibility key microfiltration plant operating parameters on SCADA
    Date: By 31 March 2025
  9. Repair or replace MCC5
    Date: By 31 March 2025
Site power:
  1. Make safe high voltage cables above the borehole access track
    Date: Complete
  2. Assess the condition of site generators and associated equipment. Refurbish or replace as required
    Date: By 31 March 2023
  3. Install and commission new High voltage equipment
    Date: By 30 June 2022
  4. Undertake a power survey and undertake required remedial actions
    Date: By 31 March 2023
Power and Resilience
  1. Carry out risk assessment investigation for the recommendations from the Power Survey (V1 dated 5/11/21) report, providing likelihood and severity of risks. Provide programme of works and timeframe for completion and short-term mitigation measures. 
    Date: 30 June 2022
  2. Confirm completion of programme of works in (b)45. 
    Date: 31 December 2026 
Dead legs and Cross connections
  1. Investigate, cut and cap redundant pipework, including Otterbourne Hill South
    Date: By 30 June 2023
Long term strategy:
  1. Confirm the long term water resources plan and pre-disinfection treatment requirements.
    Date: By 31 December 2022
  2. Review the wash water recovery system in context of the long term water resources plan.
    Date: By 31 December 2022
  3. Construction and commission of the long term pre-disinfection treatment.
    Date: By 31 December 2026

(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: Complete
  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 Otterbourne WSW, 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: 

Provide a progress report annually by 31 January and against the following milestones: 

  1. Confirmation of completion of all measures due for completion by 31 December 2017. 
    Date: Complete 
  1. Confirmation of completion of filter refurbishment. 
    Date: Complete 
  1. Confirmation of completion of all measures due for completion in June 2022. 
    Date: 31 July 2022 
  1. Confirmation of completion of all actions due for completion in December 2022. 
    Date: 31 January 2023 
  1. Confirm the long-term pre-disinfection treatment plans for Otterbourne. 
    Date: 31 January 2023 
  1. Confirmation of completion of all actions relating to site power and transformer compliance. 
    Date: 30 April 2023 
  1. Confirmation of completion of all actions relating to dead leg and cross connections. 
    Date: 31 July 2023 
  1. Confirm replacement of wash water pump 
    Date: 30 September 2023 
  1. Provide an interim report on progress with the long-term plan for Otterbourne. 
    Date: 30 June 2024 
  1. Confirmation of completion of all remaining actions due for completion in March 2025. 
    Date: 30 April 2025 
  1. Confirm the completion of the pre-disinfection treatment. 
    Date: 31 January 2027 
  1. Confirm the construction and commissioning of the new carbon treatment system. 
    Date: 31 January 2027 
  1. Submit risk assessment investigation for the recommendations from the power survey report, providing likelihood and severity of risks. Provide programme of works and timeframe for completion and short-term mitigation measures. 
    Date: 31 July 2022 
  1. Evidence completion of programme of works relating to power and resilience in (b)(xlv) 
    Date: 31 January 2027 
  1. Submit the strategy for auditing the effectiveness of the measures, as specified in (c)1. 
    Date: Complete 
  1. Submit any revisions of the audit strategy produced under measure (c)2. 
    Date: Within 1 month of a revision 
  1. Submit a report in the event that any completed measures of this Notice needs to be altered in any way for any reason. 
    Date: Ongoing for the duration of this notice. 
  1. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off. 
    Date: 31 January 2028

Further Details of this Notice: 

  1. Any product or substance used as a result of the requirements in this Notice must comply with regulation 31. 
  1. 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.  
  1. 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). 
  1. Contravention of a regulation 28(4)(d) requirement is an offence under regulation 33(1). If guilty of such an offence, the Company is liable on summary conviction, or on conviction on indictment, to a fine. Under regulation 33(2) it is a defence for the Company to show that it took all reasonable steps and exercised all due diligence to avoid the commission of the offence. 
  1. Where a measure requires the company to install this is deemed to include installation, commissioning, asset integration, training for all relevant personnel and being in beneficial use. 

Signed 

Nicholas Adjei 
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs 
28 March 2022 
Reference: SRN3698 V5 

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