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Notice of Regulation: Twyford Water Supply Works

Completion Date: 31/01/2023
Ref: SRN-2018-00012

THE WATER SUPPLY (WATER QUALITY) REGULATIONS 2016 (AS AMENDED)

NOTICE UNDER REGULATION 28(4)

SOUTHERN WATER: TWYFORD WATER SUPPLY WORKS

Site reference and name:
TH005 Twyford Water Supply Works

Supply System reference and name:
Y002 Hampshire South

DWI Reference number: LI/SRN/2018/00012

THE SECRETARY OF STATE:

  1. has on 28 December 2017 received a report from Southern Water (the “Company”) dated 28 December 2017 (the “Report”) which states that there is or has been a significant risk of supplying water from Twyford Water Supply Works that could constitute a potential danger to human health.
  2. GIVES NOTICE to the Company under regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (as amended) that it must satisfy the following requirements:

For risks associated with:

  • Nitrate

Requirements

(a) to maintain the following measures for the period specified

  1. Continue current blending regime and operational alarm responses.
    Date: For the duration of the Notice.
  2. Carry out enhanced sampling and monitoring (once installed) for nitrate.
    Date: For the duration of the Notice.
  3. Monitoring and reporting the impact of any changes made.
    Date: For the duration of the Notice.

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

  1. Install and commission online monitoring at Twyford, Twyford Moors and Otterbourne Water Supply Works.
    Date: By 31 December 2019.
  2. Install and commission treated water blending of Twyford with Otterbourne Water Supply Works and Twyford Moors Water Supply Works within Twyford Water Service Reservoir by modifying the valving on the existing distribution system near Tollgate Cottage
    Date: By 31 December 2021.
  3. Investigate changes to the operation model for Twyford WSW to reduce output during high nitrate periods.
    Date: By 31 December 2021.
  4. Monitor nitrate concentrations at Twyford Water Service Reservoir to ensure water with nitrate concentrations exceeding 50 mg/l does not enter supply.
    Date: For the duration of the Notice.

(c) to audit whether the measures have been effective by the following means:

  1. Implement an enhanced monitoring strategy for nitrate to include the monitoring of all high risk raw water sources and associated final waters on a weekly basis to supplement the current regulatory treated water monitoring.
    Date: For the duration of the Notice.
  2. Report all exceedances of the nitrate parameter to the Local Authority and Health Protection team and agree further additional steps to protect public health as appropriate.
    Date: For the duration of the Notice.
  3. Report all regulatory exceedances of the standards for the nitrate parameter to DWI as part of current monthly exception reporting process.
    Date: For the duration of the Notice.

(d) 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 risk of supplying water that would constitute a potential danger to human health:

  1. Provide a progress report annually by 31 January and against the following milestones:
    Date: For the duration of the Notice.
    • Submit a report confirming installation and commissioning of online monitoring at Twyford, Twyford Moors and Otterbourne Water Supply Works.
      Date: By 31 January 2020.
    • The company shall provide an overview of its operational strategy for maintaining nitrate below the standard prescribed by the Water Supply (Water Quality) regulations 2016 (as amended).
      Date: By 30 April 2020
    • Submit a report confirming the installation and commissioning of treated water blending with Otterbourne Water Supply Works and Twyford Moors Water Supply Works.
      Date: By 31 January 2022.
    • Submit a report detailing the operational changes to Twyford to mitigate Nitrate beyond 2025 predicted levels.
      Date: By 31 January 2022.
  2. Review the risk assessment for Twyford Water Supply Works as required by Regulation 27(3) and subsequently submit a revised regulation 28 report accompanied by a signed board level declaration.
    Date: From time to time and by 21 January 2023.
  3. Submit a satisfactory completion report.
    Date: By 31 January 2023.

Failure by the Company to comply with this Notice may result in enforcement proceedings under section 18 of the Act.

Signed by authority of the Secretary of State
Milo Purcell
Deputy Chief Inspector
10 February 2021
DWI ref: LI/SRN/2018/00012
Version 2