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Severn Trent Water Limited – Stratford WSZ Residual disinfectant and microbiology

Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (as amended)

Reference: SVT-2024-00007

Version Number: 1

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): Severn Trent Water Limited, with registered number 02366686 (hereinafter called ‘the Company’).

Assets Affected:

ZWA15 – Stratford Water Supply Zone

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 25 September 2023, which states that there is or has been a significant risk of supplying water from Stratford water supply zone 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 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

Failure to maintain the residual disinfectant concentration throughout the Stratford zone to facilitate compliance with microbiological standards.

Coliform bacteria

ZWA15-1126-D-H035-C001-23P;

E. coli

ZWA15-1126-D-H035-C002-23Q;

Enterococci

ZWA15-1126-D-H035-C003-2Q2;

Clostridium perfringens

ZWA15-1126-D-H035-C004A-2YX;

Colony Counts After 3 Days At 22øc (Colony Counts)

ZWA15-1126-D-H035-C007-2C0;

Colony Counts After 48 Hours At 37øc (Colony Counts)

ZWA15-1126-D-H035-C013-2M2;

Viruses

ZWA15-1126-D-H035-H036-H036

Table 1: Table of the hazards, hazardous events, and/or parameters covered by this Notice, including the Hazard I D numbers and the description of risks.
  1. 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. Enhanced bacteriological monitoring of coliform bacteria and E. coli in the Stratford WSZ as defined in the audit strategy.
    Date: Ongoing for the duration of this Notice
  2. Optimise the existing network configuration to maintain a satisfactory chlorine residual in the network as defined in the audit strategy.
    Date: Ongoing for the duration of this Notice
  3. Activate booster chlorination in the event that chlorine residual levels fall below trigger values as defined 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. Complete the commissioning and make fully operational the temporary chlorine dosing rig located at Chesford Valve House.
    Date: 30 June 2024
  2. Review the hydraulic operation of Stratford WSZ to ascertain if splitting the zone is required.
    Date: 31 December 2024
  3. Install and commission a permanent chlorine dosing rig at Chesford Valve House allow for booster chlorination into the Stratford WSZ.
    Date: 31 December 2025

(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: 30 June 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 Stratford WSZ, 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. Provide a report on the completion of the commissioning and the operation of the temporary dosing rig at Chesford Valve House.
    Date: 31 July 2024
  3. Provide a report on the hydraulic operation review of the Stratford WQZ and if any zone boundaries are required to be changed.
    Date: 31 January 2025
  4. Provide a report on the installation, commissioning and operation of the permanent chlorine dosing rig at Chesford Valve House.
    Date: 31 January 2026
  5. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: 31 July 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: 31 January 2027

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.
  2. 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.
  3. 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
24 April 2024
Reference: SVT-2024-00007 v1

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