The existing forestry settlement at Uriarra in rural ACT was destroyed in the 2003 Canberra bushfires. The ACT Government committed to rebuilding and a new village containing 100 homes is nearing completion. Sewerage services to Uriarra Village consist of a pressurised sewer network and a membrane bioreactor treatment plant, which are owned and operated by ACTEW Water. Sewage characterisation, inflow equalisation, balancing, pressurised sewers.

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One of Shoalhaven Water’s water quality management barriers is the maintenance of a consistent free chlorine residual throughout the entire water distribution network to provide a final barrier against pathogens. In 2011, Shoalhaven Water embarked on the development of a Disinfection Residuals Strategy (DRS) to identify the most technically appropriate and cost effective approach for providing a disinfection residual throughout the entire distribution network.

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MidCoast Water has used magnesium hydroxide to effectively control hydrogen sulphide odours in small sewage pump stations. The use of magnesium hydroxide has reduced our operating costs by removing the need to use potable water and ineffective chemicals, whilst reducing odour issues, internal sewer corrosion and improved confined space space entry as high levels of hydrogen sulphide are no longer present. MidCoast Water developed a trial of magnesium hydroxide as a control method for hydrogen sulphide.

A number of trial installations were established at sewage pump stations with known odour issues. A relatively small dose of 40 mg/L of magnesium hydroxide was able to reduce hydrogen sulphide levels from over 100 parts per million (ppm) to less than 5 ppm by using a small and inexpensive dosing system. The use of magnesium hydroxide has significantly reduced our operating costs by removing the need for potable water use to reduce septicity and the need for other chemical or biological agents to mask or control odours.

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An augmentation of the Bowral sewerage treatment plant was carried out in 2006. This was a substantial upgrade that provided council with a facility that was capable of consistently delivering a very high quality effluent to the receiving waters, being the Wingecarribee River. The team at Bowral identified some problems in the secondary treatment area at the plant and have since carried out some further upgrades in this area to address these issues. Optimisation of the plant was carried out to minimise the impact of these problems in the secondary treatment area. Another significant capital works project has been identified for next year to further improve this area of the plant.

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Designed to provide water supply operators with additional tools for monitoring and controlling water and ultimately providing consumers with adequate water pressure in all areas of a water reticulation system.

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Biological activated carbon (BAC) filters are often used in conjunction with ozonation to reduce biodegradable dissolved organic carbon (BDOC) release into the distribution system. BDOC is associated with higher chlorine demand, biofilm growth and taste and odour issues within the distribution system and therefore a target of 0.2 mg BDOC/L is desired after the BAC filters.

Orange WTP experiences high variations in water temperature from summer to winter. It was discovered through regular BDOC monitoring, that optimisation of the BAC filters’ operating conditions, in particular backwashing frequency, significantly influences BAC filter performance. It also raised the question as to whether the BDOC test should be conducted at 21oC as per the standard method or whether it should be conducted closer to the temperature of the water in the distribution system. Describe the differences in BDOC concentration in relation to the backwashing frequency of the BAC filters, water temperature, initial dissolved organic carbon (DOC) levels, ozone residuals and temperature of the BDOC test itself in the water collected from Orange WTP.

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During 2010, three rain events within the Queanbeyan River Catchment caused the Googong Reservoir to rapidly fill after a period of prolonged drought. The water quality during that time experienced spikes that had not previously been seen in the reservoir. True colour peaked at ten times the average, and to date has still not returned to normal.

Turbidity, on the other hand spiked almost as high, but returned to relatively normal within the next few months. Total and dissolved manganese followed similar trends to turbidity, whilst, total and dissolved iron is still significantly elevated. These never before seen spikes caused several breaches of action limits and critical limits set under the Hazard Analysis and Critical Control Point (HACCP) system.

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Nature strip congestion has become a serious problem within Wagga Wagga for Riverina Water County Council over the last decade. This congestion on the nature strip is primarily due to the numerous telecommunication carriers with an optic fibre network in the city, of which there are currently six. The result of this congestion is significantly increased construction times and costs being incurred by Riverina Water. A recent job to replace 550m of 450mm DICL pipe resulted in 6 months work and $80,000 expenditure to identify a suitable alignment on the nature strip. In the end, we were unable to construct on the nature strip & the pipeline was built under sporting fields.

These costs and a number of other incidences resulted in us posing the question “why we have no rights on the nature strip, when The Telecommunications Act 1997 gives telco’s the right to do whatever they want?” Water utilities have to work with the largest & least flexible material of all utilities on the nature strip, yet we are the ones with no rights when it comes to installing and maintaining our asset. With the NBN rollout having just started in Wagga, this situation is only going to get worse, going by our first experience with NBN Co.

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Dungog WTP is a 90 ML/d direct filtration plant in the Lower Hunter region of NSW. This plant experiences significant variations in raw water quality on a seasonal basis as well as during elevated turbidity events caused by heavy rainfall. These variations in quality cause changes to coagulation conditions and filtration performance that can result in sub-optimal performance with regard to water quality, chemical dose rates and filter media condition. This makes optimisation of the process a difficult and challenging task for operational staff. How the improved monitoring was set up and how this information is now routinely used as an operational tool to optimise filter performance and minimise life-cycle costs.

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Even in developed countries like Australia, drinking water systems are vulnerable to contamination. Communities cannot rely simply on end-point water quality monitoring. There is strong international consensus that a preventive risk-management approach as set out in the Australian Drinking Water Guidelines (ADWG)1 is the most reliable way to protect public health.

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The Mount Stromlo Water Treatment Plant (SWTP) abstracts water from Bendora Dam via gravity, Cotter Dam via Cotter Pump Station and the Murrumbidgee River via Murrumbidgee and Cotter Pump Stations. Since the 2003 bushfires the catchment has been very prone to erosion during wet weather events. The dirt and sediment washing into the dams are high in Iron and Manganese. Dissolved Air Flotation and Filtration has been a very effective treatment process for the low quality raw water from the catchment during wet weather events. However the float from the filters and waste backwash water is a concentrated mix of turbidity, metals and anything else that has made its way from the catchment.

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The wastewater conveyance system from Alfred Street pump station (Slacks Creek) to the Loganholme Wastewater Treatment Plant (WWTP) is a critical component of the Logan North wastewater network. Previous planning had identified a $132 M engineering solution to upgrade the network, which was operating at capacity.

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Source Water Management minimising risk to the owners and operators. Uniform water temperatures throughout the column allowed deep vertical jet penetration inhibiting the growth of algae, the warmer temperatures deeper in the dam eliminated cold water pollution from releases downstream. Forcing the oxygen rich top water layer to the bottom of a water reservoir improved the oxygen concentration of the entire water body, the oxygen in the water at these lower levels oxidized the soluble iron and manganese, these and other elements came out of solution and dropped to the dam floor. Good management of our scarce water resource and by improving the quality of these water bodies, treatment costs can be drastically reduced. PAC costs can also be reduced. The removal of Fe and Mn will reduce the cost in the water treatment plant.

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Stromlo Water Treatment Plant is a 250 ML/day DAFF plant which operates with seasonal changes in coagulation chemistry. At water temperatures of less than 12°C the process is aluminium sulphate (Alum), polyaluminium chloride liquid (PACL) and polymer. For warmer water only Alum and polymer are used. Mud balls were discovered in the filters in late 2012. In response, a review of the coagulation at Stromlo WTP is being conducted to consider the chemical dosing history that caused the problem, the ongoing polymer dose location and options for primary coagulants. Alum and PACL are both primary coagulants and in all other known treatment plants either Alum or PACL are dosed, not both. At Stromlo WTP historically both are dosed, in series based on original jar testing and pilot plant operation when the plant was designed. Polymer is currently dosed to the second floc chamber of individual filters via a passive splitter box. This flow splitting arrangement is believed to be unable to provide even flow splitting, resulting in random overdosing and under dosing of polymer.

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Hunter Water Australia (HWA) is a subsidiary company of Hunter Water Corporation (HWC), a public utility providing water and wastewater services to around half a million customers in the lower Hunter region of NSW. HWA has been contracted since 1998 to operate HWC’s water and wastewater treatment plants. Supplying a safe, reliable and aesthetic product is a critically important function of a water supply utility. Hunter Water’s performance is regulated by the NSW Independent Pricing and Regulatory Tribunal (IPART) via an operating licence, and performance is audited annually. The operating licence is aligned with the Australian Drinking Water Guidelines and the ‘Framework’ embedded within the guidelines.

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Ensuring that skills and training of staff are concurrent with ever changing legislations, codes and striving for continued improvements for industry best practice will always provide a challenge in any industry. For North East Water the challenge was compounded by having valued long term employees with experience gained over many years in the water industry.

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A study undertaken to assess the corrosivity of Canberra’s water supply, which affects the asset life of water pipes and fittings in the distribution system. The aim of the study was to determine appropriate targets for treated water pH and alkalinity, to minimise the potential for corrosion. The Calcium Carbonate Precipitation Potential (CCPP) for Stromlo WTP treated water leaving the plant was calculated using StaSoft 4.0 software for the available water quality data between 2005 and 2011. The CCPP results revealed occasional cases of highly corrosive (aggressive) water, while most of the samples showed only mildly corrosive or passive conditions.

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Drinking water storage tank cleaning is carried out to maintain water quality and to monitor the condition of the structure. Many water supply providers now use the diver vacuuming method to clean their tanks, rather than isolate the tank for days and place personnel into confined spaces with the traditional drain and sweep methods. Discuss the equipment used, the hazards encountered, vacuuming methods employed, waste water disposal issues, and the inspection opportunities that are available.

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