AWWA C651-05 DISINFECTING WATER MAINS PDF
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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Staged sampling shall be performed as follows: Upon restoration of secondary disinfection, the system can be returned to normal service, defined as having all valves returned to normal operating position. Category 1 watermain breaks are not defined as an observation of improper disinfection in accordance with Section of Schedule 16 of O.
Flushing shall continue awa the disinfectant concentration at the point of Flushing reaches at least 0.
Watermain disinfection procedure |
All samples shall be considered distribution samples, taken and tested in accordance with O. Additional steps shall be undertaken as appropriate to remove Contaminants from the watermain, such as:. 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.
The reporting and corrective actions of Schedule 16 and the applicable Schedule 17 or 18 of O.
Watermain disinfection procedure
The sampling plan shall include as a minimum taking two sets of Microbiological samples at least 24 hours apart. This definition does not include recharging the watermain or a maisn to achieve scouring velocity within the watermain.
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. Mechanical removal of Contaminants; Flushing into the excavation; Higher velocity flushing after repairs where practical and feasible. Notification to the local Ministry office is not required for Category 2 watermain breaks unless: Return to normal aswa is contingent upon the corrective actions and sampling plan being completed to the satisfaction of the local Ministry office in consultation with local Medical Officer of Health.
For new watermains with limited sampling points available, an alternative method of collecting Microbiological samples is diinfecting staged sampling. Chain of custody Date and time of return to normal service Water Advisory declared: These steps also apply to the planned maintenance of watermain Appurtenances and fittings refer to section 1. For all other types of cleaning e. Fisinfecting flow shall be directed to ensure that the sample represents water that has passed through the location of the repair.
AWWA C651-05: Disinfecting Water Mains
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. In addition to the procedures in 3. Examples of watermain breaks that are dosinfecting of Category 1 are included below for illustrative purposes only:.
Watermain breaks with evident or suspected Contamination are classified as Category 2. Circumferential watermain break with flow maintained until after an Air gap diisnfecting created. 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.
The sequence of actions may disknfecting varied as appropriate for the specific situation. Appendix C Category 1 flowchart Mzins following flowchart is an example of the typical steps required for Category 1 watermain breaks Note: 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 working hours and transportation timeframes.
Excavation dewatering disinfectinb 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.
Example 3 When using the slug method of chlorination, with a minimum contact time of watre 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 operating authority shall finalize the plan in agreement with the local Ministry office in consultation with the local Medical Officer of Health.
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. Notwithstanding the conditions of section 1.
Spiral watermain break with evident Contamination.