This document is an American Water Works Association (AWWA) standard. It is not a specification. AWWA standards describe minimum requirements and do not . This standard describes essential procedures for the disinfection of new and repaired potable water mains. New water mains shall be disinfected before they ar. AWWA/ANSI C – Disinfecting Water Mains *It is recommended that you follow the current AWWA C specification with the following.
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Notification to the aater Ministry office is not required for Category 2 watermain breaks unless: Upon completion of the excavation, the Operator-in-Charge OIC disinfexting conduct a visual inspection to determine the nature of the break.
In developing these procedures, operating authorities may use best management practices that go beyond the minimum requirements in this document. Appendix B Tools to help determine the category of watermain break – pictures Examples of watermain breaks that are typical of Category 1 are included below for illustrative purposes only: The OIC will assess the evidence of Contamination or potential Contamination of the watermain before and during the repair procedure, and shall classify the break into one of two categories as per 3.
The local Ministry office shall be notified as soon as reasonably possible during business hours. The requirements in this section also apply to temporary watermains. The operating authority shall finalize the plan in agreement with the local Ministry office in consultation with the local Medical Officer of Health.
The procedures are required to be followed in order to satisfy conditions imposed by the Director diisinfecting a drinking water works permit. In addition to the procedures in 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 process, as the slug moves through the watermain, and at the point of discharge.
For new watermains with limited sampling points available, an alternative method of collecting Microbiological samples is called staged sampling.
Watermain disinfection procedure
Watermain breaks with evident or suspected Contamination are awwx as Category 2. Upon restoration of secondary disinfection, the system can be returned to normal service, defined as having all valves returned to normal operating position. If these disinfectant concentrations cannot be achieved, Flushing shall continue until the disinfectant concentration at the point of Flushing is representative of the system residual in the break area, determined by sampling upstream of the break area and downstream at the Flushing location, or by using documented benchmarks for the area, as long as free chlorine concentrations are at least 0.
Category 1 watermain breaks are not defined as an observation of improper disinfectign in accordance with Section of Schedule 16 of O. Service pipes of mm diameter and greater shall be considered as watermains for the purposes of this procedure.
The operating authority shall record the duration of disinfection, as well as the initial dose and remaining residual at the end of the contact time.
Where the operating authority opts to undertake Microbiological sampling, samples shall be considered distribution samples within the meaning of O.
Follow the steps described in section 3. Contamination is typically not suspected for circumferential breaks or small leaks where flow is maintained from the break until an Air gap is established and where the Air gap is maintained during the repair procedure.
Flushing shall continue until the discharged water is free from discoloration, and secondary disinfection has been restored as per 3. This procedure also establishes minimum standards for record keeping, and notification to the Ministry and the local Medical Officer of Health.
For Category 2 — Special Cases, include site specific plan. Operating authorities may choose to provide notification to, or seek advice from, the local Medical Officer of Health at any time.
AWWA C651-05: Disinfecting Water Mains
The information shall be retained as per the record keeping requirements of Section diisinfecting of O. When performing maintenance and repair activities as per sections 1. The following flowchart is an example of the typical steps required for Category 1 watermain breaks Note: The discharged water is deemed to be a Class II spill disinfectihg the purposes of O. Flushed water may be discharged from a hydrant, plumbing or Appurtenances.
If an operating authority believes msins contaminated water was directed to users, this will constitute an observation of improper disinfection in accordance with Section of Schedule 16 of O. Longitudinal watermain break with evident Contamination.
All samples shall be considered distribution samples, taken and tested in accordance with O. Disinfexting section does not require that all of the information be recorded on a single form: Dechlorination of discharged water is required for any water that is directed into surface water or if the discharge into the natural environment causes or is likely to cause an adverse effect, as per Condition 10 of Schedule B of the Municipal Drinking Water Licence.
AWWA C Disinfecting Water Mains | – BNI Books
For all other types of cleaning e. The operating awwaa will xisinfecting to maintain flow from the break, where possible, until an Air gap is established. Spiral watermain break with evident Contamination. Circumferential watermain break with flow maintained until after an Air gap was created. 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.
If Contamination is evident or suspected, the procedures defined under section 3 for Category 2 watermain breaks shall apply. For planned swabbing and hydraulic e.
If final disinfectant residual is less than 0. Flushing shall be conducted following repairs by creating a temporary dead end downstream of the break through valve operation, and Flushing through the location of the repair to a discharge point. Notification to the local Ministry office c651-055 not required for Category 2 watermain breaks unless:.
This document outlines procedures for disinfecting water mains as part of an addition, disinfceting, replacement, extension, planned maintenance, or emergency repair in a municipal residential drinking water system.
Watermain disinfection procedure |
For relining of existing watermains, the conditions of section 1. Watermain repairs involving more than 6 metres of replaced pipe are also classified as Category 2. Watermain breaks with no evident or msins Contamination are classified as Category 1.