Preventive measures Checking preventive measures Corrective action Causes What to Signs that action is needed Event: CONTAMINATION GETS INTO THE TRUNK MAINS cont’d P2.1.3 Management of pressure Visual Regularity of Modify leak fluctuations and peak inspection. observed detection Leaks. pressures to minimise leaks. programme stress on the system and and Unexplained eliminate negative plan. water loss. pressure conditions. Annual leak detection and repair programme. P2.1.4 Quarterly inspection of Inspection. Number of Determine vulnerable zones with reported and viability of Incidental appropriate follow-up detected improving damage (eg, during or after incidents failures. level of floods, slips, (natural disasters, vehicle protection. accidents, etc). incidents). Provide adequate physical protection for trunk mains. P2.1.5 See D2.3 (D2.3.1.2–D2.3.1.9). Poor repairs of breaks, incidental damage, and penetration of trunk mains. Event: SEDIMENT CONTAINING CONTAMINANTS STIRRED UP Possible hazards: Germs; iron; manganese; possibly heavy metals; aluminium (from coagulant); organic particulate matter. Level of risk: Low P2.2.1 Intake designed to See Guide D2.3 (D2.3.2). minimise introduction of Sediment or sediment into the biofilm treatment plant. allowed to develop. For distribution trunk mains see Guide D2.3 (D2.3.2). P2.2.2 See D2.3 (D2.3.2). Velocity too high. Preventive measures Checking preventive measures Corrective action Causes What to check Signs that action is needed Event: CONTAMINATION GETS INTO OPEN CHANNEL CONDUITS AND BREAK-PRESSURE TANKS Possible hazards: Germs; chemical determinands. Level of risk: High2
Causes Preventive measures Checking preventive measures Corrective action What to Signs that action is needed Event: CONTAMINATION GETS INTO THE TRUNK MAINS cont’d P2.1.3 Leaks. Management of pressure fluctuations and peak pressures to minimise stress on the system and eliminate negative pressure conditions. Annual leak detection and repair programme. Visual inspection. Regularity of observed leaks. Unexplained water loss. Modify leak detection programme and plan. P2.1.4 Incidental damage (eg, floods, slips, incidents). Quarterly inspection of vulnerable zones with appropriate follow-up during or after incidents (natural disasters, vehicle accidents, etc). Provide adequate physical protection for trunk mains. Inspection. Number of reported and detected failures. Determine viability of improving level of protection. P2.1.5 Poor repairs of breaks, incidental damage, and penetration of trunk mains. See D2.3 (D2.3.1.2–D2.3.1.9). Event: SEDIMENT CONTAINING CONTAMINANTS STIRRED UP Possible hazards: Germs; iron; manganese; possibly heavy metals; aluminium (from coagulant); organic particulate matter. Level of risk: Low P2.2.1 Sediment or biofilm allowed to develop. Intake designed to minimise introduction of sediment into the treatment plant. For distribution trunk mains see Guide D2.3 (D2.3.2). See Guide D2.3 (D2.3.2). P2.2.2 Velocity too high. See D2.3 (D2.3.2). Causes Preventive measures Checking preventive measures Corrective action What to check Signs that action is needed Event: CONTAMINATION GETS INTO OPEN CHANNEL CONDUITS AND BREAK-PRESSURE TANKS Possible hazards: Germs; chemical determinands. Level of risk: High2
treatment-water-transmission-feb14-v2.docx