Refer to the following information:
- IT-1 General Provisions for minimum requirements and applying for inspections/tests.
- IT-1 Appendix A Inspection and Testing Summary and TCC/WBoPDC Hygiene Code of Practice for Water Supply Systems for the
- number of inspections required
- timing of inspections
- representatives at inspections
- TS-7.2 Disinfection Mixture (available in IDC Toolbox) for test sheet.
- TCC/WBoPDC Hygiene Code of Practice for Water Supply Systems Appendix A: Producer Statement Water System: Disinfection
- CS-9.6 Cleaning and Disinfection of Watermains for further information on keeping water main under pressure after cleaning and disinfection
IT-7.4.1 Disinfection Procedure
- Pipes shall be filled with a (minimum) 15 mg/L free available chlorine (FAC) solution to disinfect. See table TS-7.2 Disinfection Mixture (available in IDC Toolbox) for guideline amounts of sodium hypochlorite to achieve this.
- The disinfection mixture can be prepared in the following ways:
- Mix a suitable amount of potable water with the required amount of sodium hypochlorite in a tanker. The water shall be tested for chlorine concentration before use and contain sufficient free available chlorine (FAC) to produce a uniform concentration of at least 15 mg/l in the pipe.
- If pre-mixed chlorinated water is not used, the chlorine solution must be injected at a continuous rate to ensure a concentration of at least 15 mg/l in the pipe and is in contact with every part of the pipe system. This can be achieved by pumping in the chlorine solution or by using a chlorine injector while the pipe is being filled with water.
- The chlorinated water shall be introduced at the lowest point of the section of pipe to be disinfected to ensure that no air is trapped. The method of filling shall be such that the chlorine concentration is consistent when tested and recorded along the length of the pipe.
Please note Sodium Hypochlorite is a hazardous substance. Please ensure that the appropriate Health and Safety measures are followed by referencing the Materials Safety Data Sheet for the product. Chlorine solutions deteriorate when left standing, particularly if containers are dirty, exposed to sunlight or left in a warm place. Concentrated Sodium Hypochlorite should be used within specified use-by dates, checked for strength before use and should preferably be appropriately diluted and stored in clearly labelled dark plastic containers.
d. Once filled, the pipeline shall be isolated to prevent any water loss and left to stand for 24 hours. After 24 hours, the FAC is to be tested by Council to confirm that the chlorine residual is greater than 5 mg/L.
IT-7.4.2 Draining and Safe Disposal of Super-Chlorinated Water
- Once the disinfection process has been successfully completed, commence draining the pipe, ensuring that the chlorinated water is disposed of in a safe manner. This can be done by one of the following processes:
- discharging to the nearest sewer (consent to be obtained from the Council‘s Waste Services Department),
- dechlorination while draining method (see TS-7.3 Disinfection Mixture de-chlorination calculator available in IDC Toolbox, for sodium thiosulphate/other de-chlorination chemicals), or by
- tankering off site for safe disposal.
- The pipe shall be emptied of the super-chlorinated water and the ingress of any contaminants prevented. This can be achieved by purging the super-chlorinated water with potable water from the Council’s Water Supply. The pipe to be flushed out until the pipe has been purged of all super-chlorinated water (confirmed by FAC measurements at the point
Definitions in this section