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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Mechanical removal of Contaminants; Flushing into the excavation; Higher velocity flushing after repairs where practical and feasible.
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 for illustrative purposes only: All samples shall be considered distribution samples, taken and tested in accordance with O. 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.
Refer to Appendices A and B for a flowchart and pictures to better understand the criteria to determine the categories of watermain breaks. The watermain may be returned to normal service defined as having all valves returned to normal operating position prior to receipt of sample results. 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.
This procedure uses a risk management approach to categorize watermain breaks based on the potential for Contamination.
Watermain disinfection procedure |
If Contamination is evident or suspected, the procedures defined under section 3 for Category 2 watermain breaks shall apply. In developing these procedures, operating authorities may use best management practices that go beyond the minimum requirements in this document.
In addition to the requirements described in section 3. 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 aww categories as per 3. This section does not require that all of the information be recorded on c615 single form: Appendix E The following flowchart depicts the requirements for special case Contamination sewage or chemical as a result of a watermain break.
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.
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 wwwa are at least 0. Awwz 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.
After the completion of Flushing and restoration of secondary disinfection, at least one Microbiological sample shall be collected and submitted as soon as awww possible, taking into consideration laboratory working hours and transportation timeframes. 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. The following steps must be performed for all emergency watermain repairs Category 1 and Category 2.
The operating authority shall determine if flow can be maintained to the break site until the watermain is excavated. After business hours, the operating authority shall contact the Awsa Action Centre as soon as reasonably possible. Longitudinal watermain break with evident Contamination. The procedures are required to be followed in order to satisfy conditions imposed by the Director in a drinking water works permit.
Pipe and Repair Parts disinfected? For Category 2 — Special Cases, include site specific plan. Flushing shall continue until the disinfectant concentration at the point of Flushing reaches at least 0.
The awa flowchart is an example of the typical steps required for Category 2 watermain breaks. For planned swabbing and hydraulic e. 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. Watermain breaks with no evident or suspected Contamination are classified as Category 1. In addition to the procedures in 3.
The requirements in this section also apply to temporary watermains. The sequence of actions may be varied as appropriate for the specific situation. Operating Authorities may choose to provide notification to, or seek advice from, the local Medical Officer of Health at any time. This definition does not include recharging the watermain or a requirement to achieve scouring velocity within the watermain.
The reporting and corrective actions of Schedule 16 and the applicable Schedule 17 or 18 of O. Flushed water may be discharged from a hydrant, plumbing or Appurtenances. Disinfectant residual on final post repair Flushing. Skip to main content.
If there is evident or suspected sewage Contamination of a watermain, in wawa to the procedures in sections 3.
Where the operating authority opts to undertake Microbiological sampling, samples shall be considered distribution samples within the meaning of O. If chlorine disinfection was used, indicate initial aawwa, contact time, final concentration and final concentration as percentage of initial concentration. The disinfection requirements for new watermains as per Section 1. The information shall be retained as per the record keeping requirements of Section 27 of O.
Watermain disinfection procedure
Operating authorities shall develop and document operating procedures for emergency watermain repairs within their systems. Notification to the local Ministry office is not required for Category 2 watermain breaks unless: Discharges awea flushed water are also regulated under Condition 4.
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. For all other types of cleaning e.
Where there is no discharge point to allow for Flushing, the operating authority shall tap the watermain on the downstream side of the break and discharge from that point. Corrosion hole leak in a watermain with flow maintained until after an Air gap was created.
Examples of typical steps for Category 1, 2 and for special cases are attached as Appendices C, D and E respectively. The operating authority will attempt to maintain flow from the break, where possible, until an Air gap is established. Dechlorination of discharged water is required for any water that is directed into surface water or if the discharge into the natural environment causes or is likely to cause an adverse effect, as per Condition 10 of Schedule B of the Municipal Drinking Water Licence.