Undertakings: United Utilities Water – Cumwhinton to Carlisle trunk/distribution mains

SCHEDULE OF WORKS

UNDERTAKING GIVEN BY UNITED UTILITIES WATER PLC IN RESPECT OF IRON AND MANGANESE IN WATER QUALITY ZONES SUPPLIED BY CUMWHINTON TO CARLISLE TRUNK MAIN

REFERENCE NO: UUT2793

  1. WATER SUPPLY SYSTEM
    • All zones in the connected supply system supplied by Cumwhinton To Carlisle Trunk Main Which are for the time being listed in the Annex to this Schedule of Works, and which are subject to revision as necessary.
  2. NATURE OF CONTRAVENTION AND ITS CAUSE
    • The Iron and Manganese parameter(s) exceeds or is at risk of exceeding the prescribed concentrations in the zones listed in the Annex to this Schedule because of accumulation of deposits in the Cumwhinton To Carlisle Trunk Main.
  3. MAXIMUM DEVIATION OF QUALITY
    • The prescribed concentration for the Iron parameter is 200 µgFe/l and the Manganese parameter is 50 µgMn/l and remains so regardless of this undertaking. However, there is a risk that the prescribed concentration will be exceeded while remedial steps set out in this Schedule are being taken. If the prescribed concentration of Iron and Manganese is exceeded in the water supply zones listed in the Annex to this Schedule of Works, steps must be taken to minimise the impact of discoloured water on customers.

  1. Steps to be taken

(a)

Ensure that the Iron and Manganese parameters have been assessed as hazards as part of the Regulation 27 Risk Assessment for the connected supply system associated with Cumwhinton to Carlisle Trunk Main according to a Drinking Water Safety Plan approach.
Date: 1 October 2008

(b)

Submit a specific Action Plan identifying short, medium and/or long term mitigating steps to address the risk of the Iron and Manganese parameters associated with the water supply zones listed in the Annex to this Schedule of Works. To include as a minimum the requirements within (c), (d) and (e) below.
Date: 31 July 2010 and after changes made as a result of review, for the duration of the undertaking

(c) Short term measures:

Take and analyse a minimum of 12 samples for Iron and Manganese throughout the year from the area supplied from the Cumwhinton to Carlisle Trunk Main to supplement current regulatory monitoring. If the concentration of Iron or Manganese in any sample exceeds the maximum concentration that the Company has agreed with Public Health England in the water supply zones listed in the Annex to this Schedule of Works, take reasonable measures in consultation with the Health Protection Agency to minimise the impact of discoloured water on customers. Report regulatory exceedences of the Standards to DWI as part of current monthly exception reporting procedures.
Date: For the duration of the Undertaking

(d) Medium Term measures:

Phase 1 – Submit a summary of the investigations carried out to confirm the appropriateness of the remedial measures proposed for the cleaning/lining of the Cumwhinton to Carlisle Trunk Main. This should comprise a method statement which includes:
Date: 30 June 2015

  • (i) The methodology used to determine/confirm the source of the problem and where it impacts, the criteria for selection of each section of trunk main identified for improvement, the improvement options considered and solution proposed.
  • (ii) The criteria by which success will be measured (e.g. by inspection, sampling, reduction in discoloured water events), the length of cleaning and refurbishment completed and how this will be monitored during the programme of work.

The method of post-assessment to determine that the work has been successful.

Phase 2 – Submit a summary of the investigations carried out to confirm the appropriateness of the remedial measures proposed for the strategic distribution mains cleaning programme in the water supply zones listed in the Annex to this Schedule of Works. This should comprise a method statement which includes:
Date: 31 January 2018

  • (i) The methodology used to determine/confirm the source of the problem and where it impacts, the criteria for selection of each section of main identified for improvement, the improvement options considered and solution proposed.
  • (ii) The criteria by which success will be measured (e.g. by inspection, sampling, reduction in discoloured water events/levels of complaints), the length of cleaning completed and how this will be monitored during the programme of work.
  • (iii) The method of post-assessment to determine that the work has been successful.

(e) Complete planning, design and procurement arrangements for:

Phase 1 – the cleaning/lining of the Cumwhinton to Carlisle Trunk Main, comprising 30.6 km 18” and 21” diameter main, to meet the success criteria detailed in 4d (ii).
Date: 31 December 2015

Phase 2 – the provision of a strategic mains cleaning programme of those mains constructed of preferred material (i.e. 590 km excluding unlined Iron mains), to remove the historic deposits in the water supply zones listed in the Annex to this Schedule of Works, using the appropriate cleaning technique and enabling works to secure compliance with the Standard for Iron and Manganese.
Date: 31 October 2018

(f) Complete construction, installation and commissioning of:

Phase 1 – the cleaning/lining of the Cumwhinton to Carlisle Trunk Main, comprising 30.6 km 18” and 21” diameter main, to meet the success criteria detailed in 4d (ii).
Date: 30 September 2021

Phase 2 – the strategic distribution mains cleaning programme of those mains constructed of preferred material (i.e. 590 km excluding unlined Iron mains), to remove the historic deposits in the water supply zones listed in the Annex to this Schedule of Works, using the appropriate cleaning technique and enabling works to secure compliance with the Standard for Iron and Manganese.
Date: By 31 December 2021

(g) Long term measures:

In accordance with the Drinking Water Safety Plan approach, continue to appraise the risk of the Iron and Manganese parameters as hazards as part of the regulation 27 Risk Assessment for the connected supply system associated with the Cumwhinton to Carlisle Trunk Main.
Ensure that documents pursuant to Regulation 28, and including the Action Plan referred to in Step 4 (b), are reviewed and updates provided as necessary.
Date: Within 3 months and by 31 March 2022

(i) Reporting:

At regular intervals provide DWI with reports on progress made with carrying out the steps set out in the Action Plan.
Date: At 6 monthly intervals for the duration of the undertaking. Reporting periods are January to June and July to December.

Reports to include at least the following details:

  1. All Iron and Manganese data from the monitoring of treated water in the water supply zones listed in the Annex to this Schedule;
  2. Details of the remedial steps that comprise the programme of work including commencement and completion dates for investigations, design, tendering, construction and commissioning;
  3. Current state of progress with the steps referred to in (i)2. above;
  4. A statement of implications of any slippage of the programme and details of activities planned to bring programme back on target;
  5. Whether the Company has any other reason to believe it may not be able to meet any of the key dates set out in this Schedule of Work.

(j)

  1. Carry out post-commissioning assessment to demonstrate the effectiveness of Phase 1 – the cleaning/lining of the Cumwhinton to Carlisle Trunk Main, as detailed in the method statement referred to in Step 4 (d).
    Date: 30 September 2022
  2. Continue to monitor at the frequency referred to in Step 4 (c) for Iron and Manganese parameters for a period of 12 months following commissioning of Phase 2 to demonstrate the effectiveness of the remedial measures taken.
    Date: 30 April 2021

(k)

  1. Provide an interim report to DWI on the efficacy of the remedial measures taken in Phase 1 on the Cumwhinton to Carlisle Trunk Main as part of the Action Plan. Include as evidence for closure of Phase 1 of this scheme appropriate documentation to demonstrate that this Trunk Main has been cleaned/lined in accordance with the method statement referred to in Step 4 (d).
    Date: 31 October 2022
  2. Provide a final report to DWI on the efficacy of the remedial measures taken as part of the Action Plan. Include as evidence of closure for this scheme appropriate documentation to confirm that the actions set out in this Schedule of Works have been taken.
    Date: 31 January 2023

is satisfied that United Utilities Water Plc has given and is complying with an undertaking to take all such steps as appear to the Secretary of State for the time being to be appropriate to secure or facilitate compliance with the requirement of regulation 4(2)(c) of the Water Supply (Water Quality) Regulations 2018 (as amended).

Authorised by the Secretary of State to sign in that behalf

Milo Purcell
Deputy Chief Inspector
Drinking Water Inspectorate
DWI Ref No: UUT 2793
19 April 2010

ANNEX TO SCHEDULE

United Utilities Water Plc

Undertaking in respect of Iron and Manganese parameters

Supply Zones associated with the Cumwhinton to Carlisle Distribution System where there is a risk of exceedences of the Iron and Manganese standard occurring

Population of the supply zone

WSZ 002 Carlisle North

48151

WSZ 003 Carlisle South

44766

Risk Assessment Reference (name of Regulation 28 Report or Supply System)

DWI Reference

WSZ 002 Carlisle North

UUT-Risk-Z002-10-19

WSZ 003 Carlisle South

UUT-Risk-Z003-10-19

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