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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Appendix E The following flowchart depicts the requirements for special case Contamination sewage or chemical as a result of a watermain break. Examples of watermain breaks that are typical of Category 2 are included below for illustrative purposes only: The operating authority will attempt to maintain flow from the break, where possible, until an Air gap is established.
The local Ministry office shall be notified as soon as reasonably possible during business hours. The information shall be retained as per the record keeping requirements of Section 27 of O. Flushing watermain cleaning, the requirements of section 3.
If final disinfectant residual is less than 0. 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.
Return to normal service is contingent upon the corrective actions and sampling plan being completed to the satisfaction of the local Ministry office in consultation with the local Medical Officer of Health.
Watermain disinfection procedure |
The sampling plan shall include as a minimum taking two sets of Microbiological samples at least 24 hours apart. 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. This procedure also establishes minimum standards for record keeping, and notification to the Ministry and the local Medical Awea of Health.
Where copper pipe is used for smaller diameter watermains, Table 1 does not apply.
Watermain disinfection procedure
Notification to the local Ministry office is not required for Category 2 watermain breaks unless: Tags Environment and energyDrinking water. For Category 2 — Special Cases, include site specific plan.
Flow may aewa discontinued after an Air gap has been created. For all other types of cleaning e. Flow may be reduced by throttling valves while maintaining sufficient flow from the break to minimize the stabdard for Contamination. In addition to the procedures in 3. Category 2 watermain breaks are not required to be reported to the Spills Action Centre unless an operating authority believes that contaminated water was directed to users.
The operating authority shall implement the plan as prescribed and the watermain cannot be put back in service until the cleaning, disinfection and sampling is completed as per the plan unless a Water Advisory is declared. 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 standarrd as Category 2.
For relining of existing watermains, the conditions of section 1. The flow shall be directed to ensure that the sample represents water that has passed through the location of the repair. Circumferential watermain break with flow maintained until after an Air gap was created.
AWWA C / AWWA C / AWWA C – Disinfection Of Water Package
After business hours, the operating authority shall send an e-mail to the e-mail address specified by local Ministry office no later than 10 AM the next business day; or in the Special Cases described in sections 3.
This section does not require that all of the information be recorded on a single form:. When using the slug standwrd 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.
The following flowchart is an example of the typical steps required for Category 1 watermain breaks Note: Excavation dewatering shall be continued for the duration of the repairs such that the Air gap between the location of the break in the watermain and the water in the excavation is maintained.
The reporting and corrective actions of Schedule 16 and the applicable Schedule 17 or 18 of O. Where the operating authority opts to undertake Microbiological sampling, samples shall be considered distribution samples within the meaning of O. In addition to the requirements described in section 3. Additional steps shall be undertaken as appropriate to remove Contaminants from the watermain, such as:. The affected watermain s may not be put back in service before the corrective actions and sampling plan are completed unless a Water Advisory is declared.
Flushing shall continue until the disinfectant concentration at the point of Flushing reaches at least 0. Examples of watermain breaks that are typical of Category 2 are included below for illustrative purposes only:. 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.
This procedure uses a risk management approach to categorize watermain breaks based on the potential for Contamination. 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.
The following flowchart is an example of the typical steps required for Category 2 watermain breaks. After the completion of Flushing and restoration of secondary disinfection, at least one Microbiological sample shall be collected and submitted as soon as reasonably possible, taking into consideration laboratory x651 hours and transportation timeframes. Operating authorities shall develop and document operating procedures for emergency watermain repairs within their systems.
Staged sampling shall be performed as follows: