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.
|Published (Last):||18 December 2018|
|PDF File Size:||18.27 Mb|
|ePub File Size:||20.73 Mb|
|Price:||Free* [*Free Regsitration Required]|
This 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. The procedures are required to be followed in order to satisfy conditions imposed by the Director in a drinking water works permit.
With respect to new watermains, relined aqwa and temporary watermains, the provisions of this document, including sections 1. Service pipes of mm diameter and greater shall be considered as watermains for the purposes of this procedure.
Operating authorities shall use Certified Operators for functions that must be performed by a Certified Operator.
Watermain disinfection procedure |
The requirements in this section also apply to temporary watermains. Where copper pipe is used for smaller xwwa watermains, Table 1 does not apply. Due to the chlorine demand exerted by the copper, no minimum wwwa 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.
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. The operating authority shall record the duration awa disinfection, as well as the initial dose and remaining residual at the end of the contact time.
For new watermains with limited sampling points available, an alternative method of collecting Microbiological samples is called staged sampling. Staged sampling shall be performed as follows:. For relining of existing watermains, the awaw of section 1. Notwithstanding the conditions of section 1. For planned swabbing and hydraulic e. Flushing watermain cleaning, the requirements of section 3.
For all other types of cleaning e. 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. If Contamination is evident or suspected, the procedures defined under section 3 for Category 2 watermain breaks shall apply.
Drinking water system operating authorities shall ensure that emergency repairs to watermains and Appurtenances are undertaken in accordance with this awea by any person authorized to perform the repairs. Operating authorities shall develop and document operating procedures for emergency watermain repairs within their systems. In developing these procedures, operating authorities may use best management practices that go beyond the minimum requirements in this document.
This procedure uses a risk management approach to categorize watermain breaks based on the potential aawwa Contamination. This procedure also establishes minimum standards for record keeping, and notification to the Ministry and the local Medical Officer of Health. Upon completion of the excavation, the Operator-in-Charge OIC shall conduct a visual inspection to determine the nature of the break. 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.
Refer to Appendices A and B for a flowchart and pictures to better understand the criteria to determine the categories of watermain breaks. Watermain breaks with no evident or suspected Contamination are classified as Category 1. Follow the steps described in section 3. 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.
If, at any time, Contamination is evident or suspected, the break shall be reclassified as Category 2. Watermain breaks with evident or suspected Contamination are classified as Category 2. Watermain repairs involving c6651 than 6 metres of replaced pipe are also classified as Category 2.
AWWA C / AWWA C / AWWA C – Disinfection Of Water Package
Category 1 watermain breaks are not defined as an observation of improper disinfection in accordance with Section of Schedule 16 of O. Operating Authorities may choose to provide notification to, or seek advice from, the local Medical Officer of Health at any time. 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.
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. Operating authorities may choose to provide notification to, or seek advice from, the local Medical Officer of Health at any time.
Notification to the local Ministry office is not required for Category 2 watermain breaks unless:. The following awaw must be performed for all emergency watermain repairs Category 1 and Category 2. Examples of typical steps for Category 1, 2 and awsa special cases are attached as Appendices C, D and E respectively. The operating authority shall determine if flow can be maintained to the break site until the watermain is excavated. The operating authority will attempt to maintain flow from awwq break, where possible, until an Air gap is established.
Flow may be reduced by throttling valves while maintaining sufficient flow from the break to minimize the potential for Contamination. Flow may be discontinued after an Air gap has been created. 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.
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. 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. Flushed water may be discharged from a hydrant, plumbing or Appurtenances.
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. Flushing shall continue until the discharged water is free from discoloration, and secondary disinfection has been restored as per 3.
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.
The discharged water is deemed to be a Class II spill for the purposes of O. Discharges of flushed awws are also regulated under Condition 4.
Flushing shall continue until the disinfectant concentration at the point of Flushing reaches at least 0. 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 awwaa Flushing location, or by using documented benchmarks for the area, as long as free chlorine concentrations are aqwa least 0.
Watermain disinfection procedure
Upon restoration of secondary disinfection, the system can be returned to normal service, defined as having all valves returned to normal operating position. There is no requirement to undertake Microbiological sampling for Category 1 watermain break repairs. Where the operating authority opts to undertake Microbiological sampling, samples shall be considered distribution samples within the meaning of O. In addition to the requirements described in section 3.
Additional steps shall be undertaken as appropriate to remove Contaminants from the watermain, such as:. In addition to the procedures in 3. 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.
The flow shall be directed to ensure awea the sample represents water that has passed through the location of the repair. The sampling will typically occur at the point of Flushing, and may take place from sampling ports, hydrants, blow-offs, or premise plumbing. All samples shall be considered distribution samples, taken and tested in accordance with O. The reporting and corrective actions of Schedule 16 and the applicable Schedule 17 or 18 of O. The watermain may be returned to normal service defined as having all valves returned to normal operating position cc651 to receipt of sample results.
If there is evident or suspected sewage Contamination of a watermain, in addition to the procedures in sections 3. The sampling plan shall include as a minimum taking two sets of Awwa samples at least 24 hours apart. 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.
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 requirements for new watermains as per Section 1. If there is evident or suspected chemical Contamination of a watermain, in addition to the procedures in sections 3. The operating authority shall finalize the plan in agreement cc651 the local Ministry office in consultation with the local Medical Officer of Health.
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. When performing maintenance and repair activities as per sections 1. The information shall be retained as per the record keeping requirements of Section 27 of O.
This section does not require that all of the information be recorded on a single form:. Examples of watermain breaks that are typical of Category 1 are included below for illustrative purposes only:. Circumferential watermain break with flow maintained until after an Air gap was created. Corrosion hole leak in a watermain with flow maintained until after an Air gap was created. Examples of watermain breaks that are typical of Category 2 are included below for illustrative purposes only:.
The following flowchart is an example of the typical steps required for Category 1 watermain breaks Note: These steps also apply to the planned maintenance of watermain Appurtenances and fittings refer to section 1. The following flowchart is an example of the typical steps required for Category 2 watermain breaks. The sequence of actions may be varied as appropriate for the specific situation.
The following flowchart depicts the requirements for special case Contamination sewage or chemical as a result of a watermain break. Skip to main content. 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.
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. 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.
Staged sampling shall be performed as follows: Notification to the local Ministry office is not required for Category 2 watermain breaks unless: The local Ministry office shall be notified as soon as reasonably possible during business hours.
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.
After business hours, the operating authority shall contact the Spills Action Centre as soon as reasonably possible. Mechanical removal of Contaminants; Flushing into the excavation; Higher velocity flushing after repairs where practical and feasible. This section does not require that all of the information be recorded on a single form: