This document is an American Water Works Association (AWWA) standard. It is not a .. This foreword is for information only and is not a part of AWWA C AWWA C Disinfecting Water Mains. Current; Document Language: English; Published By: American Water Works Association (AWWA). AWWA C and these specifications. Disinfection requirements shall include preventive and corrective measures during construction, forms of chlorine and.
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If an operating authority believes that contaminated water was directed to users, this will constitute an observation of improper disinfection in accordance with Section of Schedule 16 of O. Examples of watermain breaks that are typical of Category 2 are included below for illustrative purposes wawa When performing maintenance and repair activities as per sections 1.
Where copper pipe is used for smaller diameter watermains, Table 1 does not apply. Additional steps shall be undertaken as appropriate to remove Contaminants from the watermain, such as:. The operating authority will attempt to maintain flow from the c6551, where possible, until an Air gap is established.
Watermain disinfection procedure
Upon completion of the excavation, the Operator-in-Charge OIC shall d651 a visual inspection to determine the nature of the break. Flow may be reduced by throttling valves while maintaining sufficient flow from the break to minimize the potential for Contamination.
Appendix D The following flowchart is an example of the typical steps required for Category 2 watermain breaks.
For all other types of cleaning e. Chlorine Concentrations and Contact Times for New Watermains At levels adwa 10 milligrams per litre, a measurement of total chlorine shall be deemed to be equivalent to a measurement of free chlorine.
If there is evident or suspected sewage Contamination of a watermain, in addition to the procedures in sections 3. 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.
Flushing watermain cleaning, the requirements of section 3. Follow the steps described in section 3.
This procedure uses a risk management approach to aawwa watermain breaks based on the potential for Contamination. Pipe and Repair Parts disinfected? Discharges of flushed water are also regulated under Condition 4.
These steps also apply to the planned maintenance of watermain Appurtenances and fittings refer to section 1.
AWWA C / AWWA C / AWWA C – Disinfection Of Water Package
Flushing shall continue until the discharged water is free from discoloration, and secondary disinfection has been restored as per 3. Watermain repairs involving more than 6 metres of replaced pipe are also classified as Category 2.
Mechanical removal of Contaminants; Flushing into the excavation; Higher velocity flushing after repairs where practical and feasible.
In addition to the requirements described in section 3. When using the slug method of chlorination, with a minimum contact time of 3 hours, the awda 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. Staged sampling shall be performed as follows:. Operating Authorities may choose to provide aewa to, or seek advice from, the local Medical Officer of Health at any time.
In developing these procedures, operating authorities may use best management practices that go beyond awwq minimum requirements in this document. Disinfectant residual on final post repair Flushing.
The flow shall be directed awaw ensure that the sample represents water that has passed through the location of the repair. 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. If planned maintenance, indicate type of planned maintenance e. Zwwa 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.
Watermain disinfection procedure |
Due to the chlorine demand exerted by the copper, no minimum adwa 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.
If Contamination is evident or suspected, the procedures defined under section 3 for Category 2 watermain breaks shall apply. Staged sampling shall be performed as follows: 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 following flowchart is an example of the typical steps required for Category 2 watermain breaks.
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 aqwa Health.