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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Upon completion of the excavation, the Operator-in-Charge OIC shall conduct a visual inspection to determine the nature of the break. In addition to the procedures in 3. All samples shall be considered distribution samples, taken and tested in accordance with O.
The information shall be retained as per the record keeping requirements of Section 27 of O. 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 local Medical Officer of Health.
Watermain disinfection procedure
The following steps must be performed for all emergency watermain repairs Category 1 and Category 2. The sampling will typically occur at the point of Flushing, and may take place from sampling ports, hydrants, blow-offs, or premise plumbing.
The watermain may be returned to normal service defined as having all valves returned to normal operating position prior to receipt of sample results. Notification to the local Ministry office is not required for Category 2 watermain breaks unless: 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.
If, at any time, Contamination is evident or suspected, the break shall be reclassified as Category 2. 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.
Examples of watermain breaks that are typical of Category 1 are included below for illustrative purposes only:. Mechanical removal of Contaminants; Flushing into the excavation; Higher velocity flushing after repairs where practical and feasible. The following flowchart depicts the requirements for special case Contamination sewage or chemical as a result of a watermain break. 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.
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. Service pipes of mm diameter and greater shall be considered as watermains for the purposes of this procedure.
Watermain repairs involving more than 6 metres of replaced pipe are also classified as Category 2. If there c6551 evident or suspected chemical Contamination of a watermain, in addition to the procedures in sections 3. The local Ministry office shall be notified as soon as reasonably possible during business hours.
Flow may be discontinued after an Air gap has been created. When using the slug method of chlorination, with a minimum contact standqrd 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.
Operating authorities may choose to provide notification to, or seek advice from, the local Medical Officer of Health at any time. 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. 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.
Added, modified, replaced, extended; or Taken out of service for inspection, repair or other activities that may lead to Contamination, shall be disinfected before being put into service in accordance with the provisions of the AWWA C — Standard for Disinfecting Water Mains or an equivalent procedure.
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.
Chain of custody Date and time of return to normal service Water Advisory declared: Refer to Appendices A and B for a flowchart and pictures to better understand the criteria to determine the categories of watermain breaks. Due to the chlorine stnadard 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 tsandard section 1.
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Longitudinal watermain break with evident Contamination. This procedure uses a risk management approach awaa categorize watermain breaks based on the potential for Contamination. Operating Authorities may choose to provide notification to, or seek advice from, the local Medical Officer of Health at any time.
There is no requirement to undertake Microbiological sampling for Category 1 watermain break repairs.
AWWA C / AWWA C / AWWA C – Disinfection Of Water Package
This section does standar require that all of the information be recorded on a single form:. The operating authority shall implement the plan as prescribed and the watermain cannot be put back in service until the cleaning, disinfection standarr sampling is completed as per the plan unless a Water Advisory is declared.
For planned swabbing and hydraulic e. The disinfection requirements for new watermains as per Section 1. 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.
Appendix B Tools to help determine the category of watermain break – standsrd Examples of watermain breaks that are typical of Category 1 are included below for illustrative purposes only: