P3.2.5 Maintain water level in Inspect tank Unexplained Promptly tank to minimise ingress. every 2–5 deterioration repair any of years of water (depending on quality. the age of the groundwater Audit tank and risks (for inspection caused by its records. location). tanks). Complaints of Integrity test petrol smell (if of tank. near underground fuel tanks). Integrity test identifies leak. P3.2.6 Put screens on outlet of Regular Taste and Replace or upstream source. screen odour clean Animal entry inspection. complaints. screens. at upstream source Counts of (animals quality. faecal trapped and indicators destroyed by higher than action of expected in inlet control valves on treatment. tanks). P3.2.7 See Guide S1.1. Introduction of by run-off or see page from land use activities. Event: DEVELOPMENT, OR RE-SUSPENSION, OF SEDIMENT WITHIN TANK OR RESERVOIR Possible hazards: Germs, manganese, disinfection by-products (trihalomethanes, haloacetic acids, chloral hydrate). Level of risk: Low P3.3.1 Avoidance of rapid Turbidity. Visible slime Review drain/fill. or sediment. cleaning Sediment/ Audit cleaning procedures slime Undertake regular procedures Customers and plant cleaning of reservoirs and operation. complain of operation. and (every 1–5 years slime or release. depending on the quality sediment. of the source water, flow through and degree of stagnation in the tank, etc). Shut off intake during periods of poor raw water quality. Event: DEVELOPMENT OF OXYGEN-DEFICIENT CONDITIONS WITHIN TANK OR RESERVOIR Possible hazards: Manganese. Level of risk: Low
P3.2.5 of groundwater (for tanks). Maintain water level in tank to minimise ingress. Inspect tank every 2–5 years (depending on the age of the tank and risks caused by its location). Integrity test of tank. Unexplained deterioration of water quality. Audit inspection records. Complaints of petrol smell (if near underground fuel tanks). Integrity test identifies leak. Promptly repair any P3.2.6 Animal entry at upstream source (animals trapped and destroyed by action of inlet control valves on tanks). Put screens on outlet of upstream source. Regular screen inspection. quality. Taste and odour complaints. Counts of faecal indicators higher than expected in Replace or clean screens. P3.2.7 Introduction of by run-off or see page from land use activities. See Guide S1.1. Event: DEVELOPMENT, OR RE-SUSPENSION, OF SEDIMENT WITHIN TANK OR RESERVOIR Possible hazards: Germs, manganese, disinfection by-products (trihalomethanes, haloacetic acids, chloral hydrate). Level of risk: Low P3.3.1 Sediment/ slime and release. Avoidance of rapid drain/fill. Undertake regular cleaning of reservoirs (every 1–5 years depending on the quality of the source water, flow through and degree of stagnation in the tank, etc). Shut off intake during periods of poor raw water quality. Turbidity. Audit cleaning procedures and operation. Visible slime or sediment. Customers complain of slime or sediment. Review cleaning procedures and plant operation. Event: DEVELOPMENT OF OXYGEN-DEFICIENT CONDITIONS WITHIN TANK OR RESERVOIR Possible hazards: Manganese. Level of risk: Low treatment.