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AWWA C Disinfecting Water Mains. Current; Document Language: English; Published By: American Water Works Association (AWWA). This standard presents essential procedures for the disinfection of new and repaired potable water mains. All new water mains shall be disinfected before they. FIELD CHLORINATION. • AWWA/ANSI C – Disinfecting Water Mains. • First standard approved Sept. 30, • Latest revision June 1.

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With respect to new watermains, relined watermains and temporary watermains, the provisions of this document, including sections 1. Operating authorities may choose to provide notification to, or seek advice from, the local Medical Officer of Health at any time.

Additional steps shall be undertaken as appropriate to remove Contaminants from the watermain, such as:. Chain of custody Date and time of standaed to normal c561 Water Advisory declared: Refer to Appendices A and B for a flowchart and pictures to better understand the criteria to determine the categories of watermain standzrd.

If the water level in the excavation rises such that the Air gap is not maintained after flow from the break has been discontinued, then the watermain break shall be classified as Category 2. If, at any time, Contamination is evident or suspected, the break shall be reclassified as Category 2.

Drinking water system operating authorities shall ensure that emergency repairs to watermains and Appurtenances are undertaken in accordance with this procedure by any person authorized to perform the repairs. Appendix D The following flowchart is an example of the typical steps required for Category 2 watermain breaks.

Disinfectant residual on final post repair Flushing. Appendix E The following flowchart depicts the requirements for special case Contamination sewage or chemical as a result of a watermain break. Pipe and Repair Parts disinfected? If chlorine disinfection was used, indicate initial concentration, contact time, final concentration and final concentration as percentage of initial concentration.

If final disinfectant residual is less than 0.

Watermain disinfection procedure

Notification to the local Ministry office is not required for Category 2 watermain breaks unless: Examples of watermain breaks that are typical of Category 2 are included below for illustrative purposes only: The disinfection requirements for new watermains as per Section 1. Appendix C Category 1 flowchart The following flowchart is an example of the typical steps required for Category 1 watermain breaks Note: Tags Environment and energyDrinking water.


Watermain breaks with no evident or suspected Contamination are classified as Category 1. Chlorine Concentrations and Contact Times for New Watermains At levels over 10 milligrams per litre, a measurement of total chlorine shall be deemed to be equivalent to a measurement of free chlorine. The operating authority shall determine if flow can be maintained to the break site until the watermain is excavated.

Operating authorities shall develop and document operating procedures for emergency watermain repairs within their systems. Category 1 watermain breaks are not defined as an observation of improper disinfection in accordance with Section of Schedule 16 of O. This procedure also establishes minimum standards for record keeping, and notification to the Ministry and the local Medical Officer of Health.

Added, modified, replaced, extended; or Taken out of service for inspection, repair or other activities that may lead to Contamination, shall be disinfected before being put into service in accordance with the provisions of the AWWA C — Standard for Disinfecting Stxndard Mains or an equivalent procedure.

Upon completion of the excavation, the Operator-in-Charge OIC shall conduct a visual inspection to determine the nature of the break.

Flushing shall stnadard until the disinfectant concentration at the point of Flushing reaches at least 0. Spiral watermain break with evident Contamination. This procedure uses a risk management approach to categorize watermain breaks based on the potential for Contamination. Examples of watermain breaks that are typical of Category 2 are included below for illustrative purposes only:. For all other types of cleaning e. There is no requirement to undertake Microbiological sampling for Category 1 watermain break repairs.

This definition does not include recharging the watermain or a requirement to achieve scouring velocity within the watermain. The sampling plan shall include as a minimum taking two sets of Microbiological samples at least 24 hours apart.

Where there is no discharge point to allow for Flushing, the operating authority shall tap the watermain on the downstream side of the break and discharge from that point. Watermain repairs involving more than 6 metres of replaced pipe are also standafd as Category 2.


Example 3 When using the slug method of chlorination, with a minimum contact time of 3 hours, the chlorine concentration shall be measured in the slug at the beginning of the disinfection standaed, as the slug moves through the watermain, and at the point of discharge. Due to the chlorine demand exerted by the copper, no minimum chlorine concentration is required following the 24 hour contact time, and the effectiveness of the disinfection process shall be demonstrated by the Microbiological sampling referred to in section 1.

Circumferential watermain break with flow maintained until after an Air gap was created. Staged sampling shall be performed as stanndard. Where copper pipe is used for smaller diameter watermains, Table 1 does not apply.

For planned swabbing and hydraulic e. Examples of watermain breaks that are typical of Category 1 are included below for illustrative purposes only:. The wawa authority shall finalize the plan in agreement with the local Ministry office in consultation with the local Medical Officer of Health.

In addition to the requirements described in section 3.

Watermain disinfection procedure |

These steps also apply to the planned maintenance of watermain Appurtenances and fittings refer to section 1. The reporting and corrective actions of Schedule 16 and the applicable Schedule 17 or 18 of O. Flow may be discontinued after an Air gap has been created. This document outlines procedures for disinfecting water mains as part of an addition, modification, replacement, extension, planned maintenance, or emergency repair in a municipal residential drinking water system.

The operating authority will attempt to maintain flow from the break, where possible, until an Air gap is established. Mechanical removal of Contaminants; Flushing into the excavation; Higher velocity flushing after repairs where practical and feasible. The requirements in this section also apply to temporary watermains.

Share facebook twitter Print. If planned maintenance, indicate type of planned maintenance e. Service pipes of mm diameter and greater shall be considered as watermains for the purposes of this procedure.