P10.1.1 Transmission pump failure due to mechanical failure or overload. In addition to the possibility of contaminants sucked into the water by back flow, water hammer can also cause pipe failure. Preventive maintenance programme in place: regular inspections lubrication seal replacement leaks repaired corroded components replaced annual ammeter tests daily visual inspection, etc. Planned maintenance programme for replacement of components as per manufacturer’s recommendations. All pumps itemised and maintenance schedule followed. Duplicate pumps for critical applications. Use duplicate pumps alternately (provides a check that both are functioning and will not need to be overhauled at the same time). Align and secure all pump-linked pipework, valves and fittings according to standard practice. System pressure. Reservoir levels. Pump maintenance log. E. coli. FAC. No water. Reservoir levels are difficult to maintain. Frequent pump breakdowns. Frequency of unacceptable pressure drops in the system. Maintenance log not kept. with DWSNZ:2000. Revise, or put in place maintenance schedule. Review service/ duty periods of duplicate pumps (time in operation: time on standby). Carry out residual disinfection in the distribution zone if not presently done. Event: CHANGES IN PRESSURE, OR PRESSURE SURGES (WATER HAMMER) SUCK CONTAMINANTS INTO THE WATER cont’d P10.1.1 cont’d Install devices to lessen water hammer should it occur, eg: surge tanks air chambers slow-closing check valves surge suppressors.
P10.2.1 Process pumps do not add the correct dose of chemical. Schedule preventive maintenance, particularly replacement of elastomeric parts: diaphragms; tubing etc., as per manufacturers recommendations. Calibrate dosing pumps for expected duty. Ensure are fit for the purpose, eg., corrosion resistant. Provide duplicate pumps for critical functions. Daily check amount of chemical used. Use day tanks to reduce risk of overdosing. Visually check pumps daily. Check stroke and speed settings for manual pumps. Turbidity. E. coli. FAC. Chemical usage. Chemical type dosed. Coagulation process (if appropriate). with DWSNZ:2000. Signs of ineffective coagulation. Difficulty maintaining a chlorine residual in the treated water. No maintenance programme in Put maintenance schedule in place. Review dosing programme. Replace pump(s) with one appropriate for the chemical being dosed and its concentration. Obtain standby pump (critical functions). P10.2.2 Process pumps supplying water to monitoring fail. Strainers on pump lines to remove debris. Clean strainers regularly. Ensure pumps are fit for the purpose. Check required flow rates are within the range recommended by the manufacturer. Schedule preventive pump maintenance. Flow rates to Condition of strainers. Turbidity. E. coli. FAC. No, or irregular, flow to Fluctuating readings from with Maintenance log not kept. Strainers clogged. Put strainers in place. Replace pump with a unit having specifications that match requirements. Prepare and follow maintenance schedule. Event: CHANGES IN PRESSURE FROM THE BORE SUCK CONTAMINANTS INTO THE WATER Possible hazards: Germs and chemical contaminants. Level of risk: Moderate-high1
P10.3.1 Failure of the bore pump(s). Monitor bore performance either directly or using an observation bore. Schedule a preventive maintenance programme for bore pumps, and a planned maintenance programme for the overhaul of pumps. Monitor flow from the bore. Monitor system pressure. Bore flow. System pressure. E. coli. Bore pumps stop. Reduced, or no, flow from bore(s). Reduced pressure in distribution zone fed directly from the bore. with DWSNZ:2000. No maintenance log kept. Investigate bore pump performance. Put maintenance programme(s) in place. Disinfect the distribution zone if not presently disinfected. 1 If the water is disinfected after being drawn from the bore, or the water is pumped into a reservoir before reticulation, the consequences of the event will not be as severe as when the bore water is pumped directly into the distribution system. Contingency Plans If an event happens despite preventive and corrective actions you have taken, you may need to consult with the Medical Officer of Health to assess how serious a problem is. Event – Contamination gets in the water because of pump failure Indicators: Reservoir levels difficult to maintain. Pump failure. Flow significantly reduced. Pressure decrease or fluctuations. Elevated levels of turbidity or chemical determinands. In 100 ml samples of water, E. coli is continually detectable, or is present at elevated levels (more than 10 per 100 ml). Increased chlorine demand. Widespread illness in the community linked to the water supply.