D2.3.1.12 Inspection of the Inspection Cross on system for cross records. connections Cross connections. found during of staff connections2 inspections. undertaking Ensure that only connections. appropriately Reports of qualified persons gross visual are permitted to contamination carry out of tapwater by connection work consumers. undertaken for the Unexplained water supplier. fluctuations in chemical and water quality. Event: RE-SUSPENSION OF CONTAMINANTS IN SEDIMENTS IN THE DISTRIBUTION SYSTEM Possible hazards: Germs; chemical determinands, turbidity. Level of risk: Moderate3 D2.3.2.1 See D2.3.3 Causes Scour, pig, and Preventive flush Sediment or Measures. distribution biofilm allowed system. to develop. Restore acceptable quality. D2.3.2.2 Controlled FAC. Customer Restore opening/closing complaints. acceptable Water velocity Microbiological valves and starting quality. too high. quality. Failure to meet pumps. requirements Amend Turbidity. Size pipe diameters of flushing to accommodate DWSNZ:2000. protocol. demand for water without high water velocities sediment. (In some situations it may not be possible to accommodate fire flows.) 2 Examples of situations where cross connections might be a concern include premises: with an auxiliary water supply; having a swimming pool; where connection is provided to for supplying ships; and where a substance or material (included processed water or water from the public supply which might be contaminated) is handled, stored or contained. 3 The condition of the mains, the type of water source used and the performance of the treatment plant are key factors. Re-suspension of deposited manganese or silicates in volcanic areas, exposure of rusted surfaces or detachment or nodules, and possible subsequent release of bacteria are potential problems arising from flow fluctuations or reversals. Preventive measures Checking preventive measures Corrective Causes action What to check Signs that action is needed Event: DEVELOPMENT OF SEDIMENT OR BIOFILM Possible hazards: Germs; chemical determinands, turbidity. Level of risk: Moderate
D2.3.1.12 Cross connections2 Inspection of the system for cross connections. Ensure that only appropriately qualified persons are permitted to carry out connection work undertaken for the water supplier. Inspection records. Cross connections found during inspections. Reports of gross visual contamination of tapwater by consumers. Unexplained fluctuations in chemical and water quality. on of staff undertaking connections. Event: RE-SUSPENSION OF CONTAMINANTS IN SEDIMENTS IN THE DISTRIBUTION SYSTEM Possible hazards: Germs; chemical determinands, turbidity. Level of risk: Moderate3 D2.3.2.1 Sediment or biofilm allowed to develop. See D2.3.3 Causes and Preventive Measures. Scour, pig, flush distribution system. Restore acceptable quality. D2.3.2.2 Water velocity too high. Controlled opening/closing valves and starting pumps. Size pipe diameters to accommodate demand for water without high water velocities sediment. (In some situations it may not be possible to accommodate fire flows.) FAC. Microbiological quality. Turbidity. Customer complaints. Failure to meet requirements of DWSNZ:2000. Restore acceptable quality. Amend flushing protocol. 2 Examples of situations where cross connections might be a concern include premises: with an auxiliary water supply; having a swimming pool; where connection is provided to for supplying ships; and where a substance or material (included processed water or water from the public supply which might be contaminated) is handled, stored or contained. 3 The condition of the mains, the type of water source used and the performance of the treatment plant are key factors. Re-suspension of deposited manganese or silicates in volcanic areas, exposure of rusted surfaces or detachment or nodules, and possible subsequent release of bacteria are potential problems arising from flow fluctuations or reversals. Causes Preventive measures Checking preventive measures Corrective action What to check Signs that action is needed Event: DEVELOPMENT OF SEDIMENT OR BIOFILM Possible hazards: Germs; chemical determinands, turbidity. Level of risk: Moderate
distribution-operation-feb14-v2.docx