A field trial of a proprietary, high-rate physico-chemical sewage clarification process developed by CDS Technologies was conducted jointly with a Victorian water authority. The objective of the trial was to evaluate the suitability of the new process for reducing the load on the sewer during peak periods in a holiday resort area under the authority’s jurisdiction by storing clarified sewage off-line for later return to the sewer.

Trials over a 2-month period were conducted, and water quality data on both influent and effluent collected for the process. These show that the process is capable of producing clear effluent suitable for UV disinfection within 3 minutes of start-up.

The off-line storage concept was demonstrated to be feasible for smoothing the loads on sewerage and provides an alternative strategy for the management of excess flows arising from a variety of causes.

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In 1998 Norske Skog, then known as Australian Newsprint Mills, started an extensive program to reduce odour that was being generated from its effluent treatment plant. Section 4 (iii) of the Pollution reduction Program issued to (then) Australian Newsprint Mills Ltd on June 15th 1998 required the company to:

“Prepare and submit a report to the EPA on preferred options for introduction of in-line continuous monitoring that identify the onset of conditions for anaerobic decay within individual plant units. The report must identify operational contingency plans when the onset of conditions for anaerobic decay are detected by the monitors.”

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The paper describes the aeration system at the Black Rock Sewage Treatment Plant and discusses the methods adopted to effectively manage, maintain and replace the 42,000 fine bubble diffusers used to aerate the plant.

The objective of the work on the aeration system and diffusers at the plant is to maximise the life of the diffusers, minimise the energy used in the plant while providing optimum process performance.

The centrifugal compressors and diffused air distribution system are the heart and veins through which the lifeblood of the plant flows. The flow of air provides the oxygen which keeps aerobic micro-organisms alive and well in the Intermittently Decanted Extended Aeration (IDEA) plant.

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The Southwest region of Goulburn Valley Water, consisting of the towns of Broadford, Wallan, Kilmore and Wandong/Heathcote Junction, has been experiencing the worst drought on record. Between May 2002 and the current time, the usually reliable water catchment of Sunday Creek reservoir has received the lowest rainfall on record. This has resulted in the most severe water restrictions in the regions history.

The Southwest region is one of the fastest growing areas of Victoria outside of Metropolitan Melbourne. This paper discusses the impact of the water restrictions on a rapidly growing area and the operational management of limited water resources, the challenges of delivering quality product, policing severe restrictions and the actual implementation of our Drought Management Plan.

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The Warrnambool Cheese and Butter Factory wastewater treatment plant incorporates an induced air floatation system to remove suspended solids from the Anaerobic treated effluent. Failures in the floatation cell could lead to high levels of suspended solids being discharged, causing a negative impact on the operation of the South West Water Authority wastewater treatment plant at Thunder Point.

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Obtaining best practice in the Water Industry is always a difficult task, given the water shortages throughout Victoria from the ongoing below average rainfall; it is critical that Water Companies do every thing in their power to minimise non revenue water. Water Companies have developed marketing campaigns to enable their customers to reduce the amount of water usage and wastage by promoting water wise products such as low flow shower heads, garden mulch, tap timers etc. However, generally very little is being done to identify areas with unusually high night flows and the development of programs to locate leaks and reduce these flows. During the early hours of the morning customer usage should be minimal, however, if there are high night flows it may indicate a high level of leakage.

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Quakers Hill Sewage Treatment Plant (STP) is Sydney Water’s second largest inland STP, discharging an average of 32 megalitres per day of tertiary treated effluent into Breakfast Creek. The EPA regulates the effluent quality in order to protect the aquatic environment of the Hawkesbury/Nepean River System. Work has recently been completed to improve the reliability of four Travelling Bridge Filters, resulting in improvements in treatment performance and saving millions of dollars in deferred capital.

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The S::CAN Spectro::lyserTM (S::CAN) is an inline UV-Vis instrument for measuring multiple substance concentrations in situ. The unit was trialled at the Lower Molonglo Water Quality Control Centre (LMWQCC) in the influent stream. Chemical oxygen demand (COD) and suspended solids (SS) were routinely monitored and it was found that the S::CAN data calibrated well with data from real time samples collected and analysed at the ECOWISE laboratory. There is also potential for calibrating BOD data to the spectra for online BOD measurement.

The S::CAN unit therefore offers operators real time data on COD and SS which can be used to optimise and control process units via looping instructions. The S::CAN instrument can communicate with SCADA to generate an alarm, or instigate process control changes.

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Grampians Region Water Authority is experiencing great pressure through the current period of extended low rainfall.

The drought has impacted the town storage-filling regime for 29 of the Authority’s 74 towns located across an area of 60,000 square kilometers. Volumes normally reserved for twelve months or less are being managed to ensure sustained supply for up to fifteen months.

Grampians Water has developed and successfully implemented trigger point modeling. This method of modeling allows excessive consumption to be detected ensuring timely initiation of action to minimise restrictable demand. Trigger point modeling ensures a higher degree of security while keeping the impact on customers to a minimum.

The data presented will identify the success of the practices discussed illustrating how Grampians Region Water Authority manages drought without doubt.

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Ensuring that the right chemical, of the right quality, is delivered into the right storage vessel, at the right site, at the right time is a challenge all Water Authorities face. This account details Gippsland Water’s chemical quality journey. The journey culminates with the letting of a chemical supply contract with defined quality standards for all chemicals and the requirement that each chemical has a laboratory test certificate prior to delivery. The associated issues of delivery procedures and the gradual change in organisational culture are also presented.

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This paper reviews the experience of South Gippsland Water (SGW) in the use of Geobags for the dewatering of water and wastewater sludges. This method of dewatering sludges has proved to a low cost and simple method of dewatering wastewater sludges for small plants. It has also proved to be effective in significantly increasing the solids contents of alum sludges to reduce the transport costs of sludge removal.

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Draining of Lake Mulwala in May/June 2002 and persistent low rainfall in Springhurst caused raw water quality for the Yarrawonga and Springhurst water supplies to be adversely affected. Lowering water levels in both dams lead to elevated concentrations of Manganese (Mn) entering the treatment plants and reticulation systems. Several methods of Mn removal reported in literature were tested and it was found that oxidation of the Mn using Sodium Hypochlorite with contact times available in the plants and the addition of Powdered Activated Carbon during the flocculation stage achieved optimal removal of the Mn.

Systems were put in place utilising these findings, which have proven to consistently reduce raw water Mn concentrations in excess 0.42mg/L at Yarrawonga and up to 1.2mg/L at Springhurst to levels well below the guideline value of 0.1mg/L. Particle counting was also found to be a sensitive and effective monitoring tool for indicating Mn breakthrough due to system failures at Springhurst.

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ActewAGL have four specialist choke trucks incorporating a Jet Rodder as their primary method of cleaning sewer mains in the Australian Capital Territory largely replacing hand and machine sewer rods. This followed a history of accidents with sewer rods, rodding machines and sewer eels

Two lost time accidents and numerous near misses using the jet rodders prompted ActewAGL to look for engineering solutions and training in their use.

However it became obvious that there were underlying issues with the jet rodders that led to a complete review of the whole process with the following conclusions:

• Training was ad hoc and full of misconceptions about the jet rodder use.
• No standard work method for cleaning sewer mains
• Cleaning was unsatisfactory with significant revisits
• Equipment was not treated with respect required
• Trucks and equipment in poor condition with safety systems bypassed.
• Problems maintaining competence

ActewAGL undertook a complete program, which included fixing equipment reviewing work methods and developing training to the new Water Industry Package Unit 255A.

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East Gippsland Water provides water services to twenty-seven towns and sewerage services to seventeen as well as many rural consumers in an area of approximately 20,000 square kilometres ranging from Bairnsdale (South West) to Mallacoota (East) and Dinner Plain (North). Whilst the majority of these towns are located on the coastal plains, the towns of Swifts Creek, Omeo and Dinner Plain sit in the heart of Victoria’s (God’s Own) High Country. This paper will provide some insight into the operating issues encountered due to extreme weather conditions, distance from major towns / supply centres and also how we maintained services during the recent “Australia Day” bush fires.

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Warragul Water Treatment Plant is located approximately 110 kilometers west of Melbourne. The raw water is supplied from Pederson Weir, with very high turbidity and colour entering the plant during dirty water events. Gippsland Water decided to build a new DAFF Plant, which replaced the old clarification plant. The design of the plant included provision for a Milton Roy SC 5200 Streaming Current Detector (SCD), this was the first SCD to be installed and trialed at any of Gippsland Water’s treatment plants.

The operation of this SCD required several changes to the set-up at the Warragul site. These changes included changing the planned Alum and pre-lime dosing points, installing a new sample point for the SCD unit, installing a smaller Alum dosing pump, and altering the pre-lime dosing system to provide better coagulation pH control.

These changes allowed the SCD to provide close control of the coagulation at the Warragul site, including managing dirty water events with turbidities up to 300 NTU’s and colour of up to 300 PtCo. During these events the SCD manages coagulation dosing to produce suitable output quality.

These changes have significantly reduced chemical consumption and operator input, particularly during these dirty water events. This time is utilized for routine maintenance and further performance testing around the water treatment plant to better manage water quality.

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