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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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 sampling plan shall include as a minimum taking two sets of Microbiological samples at least 24 hours apart. 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 Stabdard 2.
There is no requirement to undertake Microbiological sampling for Category 1 watermain break repairs. 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 process, as the slug moves through the watermain, and at the point of discharge.
Disinfectant residual on final post repair Flushing.
Share facebook twitter Print. 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 stadnard illustrative purposes only: Flushing shall continue until the disinfectant concentration at the point of Flushing reaches at least 0. 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.
The disinfection standardd for new watermains as per Section 1. After business hours, the operating authority shall contact the Spills Action Centre as soon as reasonably possible.
This section does not require that all of the information be recorded on a single form:. Pipe and Repair Parts disinfected? The sampling will typically occur at the point of Flushing, and may take place from sampling ports, hydrants, blow-offs, or premise plumbing. If there is evident or suspected chemical Contamination of a watermain, in addition to the procedures in sections 3. The following steps must standsrd performed for all emergency watermain repairs Category 1 and Category 2.
Flushing stzndard 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.
Appendix E The following flowchart depicts the requirements for special case Contamination sewage or chemical as a result of a watermain break.
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 shall record the duration of disinfection, as well as the initial dose and remaining residual at the end of the contact time. 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.
The information shall be retained as per the record keeping requirements of Section 27 of O. Tags Environment and energyDrinking water.
Staged sampling shall be performed as follows:. The Sstandard will assess aqwa 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.
Notification to the local Ministry office is not required for Category 2 watermain breaks unless:. If chlorine disinfection was used, indicate initial concentration, contact time, final concentration and final concentration as percentage of initial concentration.
Watermain breaks with no evident or suspected Contamination are classified as Category 1. Flushing watermain cleaning, the requirements of section 3. These steps also apply to the planned maintenance of watermain Appurtenances and fittings refer to section 1. Operating Authorities may choose to provide notification to, or seek advice from, the local Medical Officer of Health at any time. Appendix C Category 1 flowchart The following flowchart is an example of the typical steps required for Category 1 watermain breaks Note: The sequence of actions may be varied as appropriate for the specific situation.
Upon completion of the excavation, the Operator-in-Charge OIC shall conduct a visual inspection to determine the nature of the break. Upon restoration of secondary disinfection, the system can be returned to normal service, defined as having all valves returned to normal operating position.
The discharged water is deemed to be a Class II spill for the purposes of O. Refer to Appendices A and B for a flowchart and pictures to better understand the criteria to determine the categories of watermain breaks.
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.
Category 1 watermain breaks are not defined as an observation of improper disinfection in accordance with Section of Schedule 16 of O.
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. For Category 2 — Special Cases, include site specific plan.
The requirements in this section also apply to temporary watermains. Mechanical removal of Contaminants; Flushing into the excavation; Higher velocity flushing after repairs where practical and feasible.
Where the operating authority opts to undertake Microbiological sampling, samples shall be considered distribution samples within the meaning of O.