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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The information shall be retained as per maihs record keeping requirements of Section 27 of O. 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 final disinfectant residual is less than 0.
AWWA C Disinfecting Water Mains | – BNI Books
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 Category 2. The following steps must be performed for all emergency watermain repairs Wawa 1 and Category 2.
Examples of watermain breaks that are dsinfecting of Category 2 djsinfecting included below for illustrative purposes only:. Skip to main content. 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. Pipe and Repair Parts disinfected? Disinfectant residual on final post repair Flushing.
Flushing watermain cleaning, the requirements of section 3. The operating authority shall determine disijfecting flow can be maintained to the break site until the watermain is excavated.
Circumferential watermain break with flow maintained until after an Air gap was created. Added, modified, replaced, extended; or Taken out of service for inspection, repair majns other djsinfecting 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.
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: Discharges of flushed water are also regulated under Condition 4.
The following flowchart is an example of the typical steps required for Category 1 watermain breaks Note: 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.
AWWA C651-05: Disinfecting Water Mains
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. Service pipes of mm diameter and greater shall be considered as watermains for the purposes of this procedure.
Mechanical removal of Contaminants; Flushing into the excavation; Higher velocity flushing after repairs where practical and feasible. 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. Flushed water may be discharged from a hydrant, plumbing or Appurtenances. 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.
If there is evident or suspected sewage Contamination of a watermain, in addition to the procedures in sections 3. If, at any time, Contamination is evident or suspected, the break shall be reclassified as Category 2. For Category 2 — Special Cases, include site specific plan. These steps also apply to the planned maintenance of watermain Appurtenances and fittings refer to section 1.
This procedure also establishes minimum standards for record keeping, and notification to the Ministry and the local Medical Officer of Health.
Follow the steps described in section 3. Flushing shall continue until the disinfectant concentration at the point of Flushing reaches at least 0. Flushing shall continue until the discharged water is free from discoloration, and secondary disinfection has been restored as per 3. All samples shall be considered distribution samples, taken and tested in accordance with O. The sampling plan shall include as a minimum taking two sets of Microbiological samples at least 24 hours apart.
Watermain breaks with no evident or suspected Contamination are classified as Category 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.
Operating authorities shall use Certified Operators for functions that must be performed by a Certified Operator.
Watermain disinfection procedure
The local Ministry office shall be notified as soon as reasonably possible during business hours. If chlorine disinfection was used, indicate initial concentration, contact time, final concentration and final concentration as percentage of initial concentration. 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.
The discharged water is deemed to be a Class II spill for the purposes of O. Additional steps shall be undertaken as appropriate to remove Contaminants from the watermain, such as:. For planned swabbing and hydraulic e. The sampling will typically occur at the point of Flushing, and may take place from sampling ports, hydrants, blow-offs, or premise plumbing.
Staged sampling shall be performed as follows: The requirements in this section also apply to temporary watermains. Appendix D The following flowchart is an example of the typical steps required for Category 2 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. Operating Authorities may choose to provide notification to, or seek advice from, the local Medical Officer of Health at any time.
Watermain disinfection procedure |
For all other types of cleaning e. In developing these procedures, operating authorities may use best management practices that go beyond the mins requirements in this document. Where copper pipe is used for smaller diameter watermains, Table 1 does not apply. After business hours, the operating authority shall contact the Spills Action Centre as soon as reasonably possible.
The following flowchart depicts the requirements for special case Contamination sewage or chemical as a result of a watermain break. In addition to the requirements described in section 3.
The operating authority will attempt to maintain flow from the break, where possible, until an Air gap is established. The procedures are required to be followed in order to satisfy conditions imposed by the Director in a drinking water works permit.