Don t mention the bore A transition from two water reticulation systems to one reticulation system Author Details John Roworth Director of Infrastructure Services Longreach Regional Council Abstract I will present a history of water supply for Longreach and track its journey from a bore water system to a bore water and river water supply to a blended system of the two. The transition has been a slow one due to many variables ranging from water quality & supply to political constraints and public outrage. The final solution was probably a good compromise which culminated in Longreach being able to satisfy its Fluoridation obligations, which prompted legislation to be amended to accommodate Longreach s proposal of blending bore water with the potable river water system. The presentation will cover asset management and explain why Longreach ended up with two systems in a reasonably poor state. I will explain the decision making process and the interaction between council staff & councillors and provide details of the public consultation process. The main issue that influenced the decision was obviously finances (the communities ability and will to pay for the luxury of two services), but also included drought proofing, water supply augmentations, efficient use of resources and the affect on the sewer system. I will also comment on the affects of amalgamations on the whole issue, maybe some good did come of amalgamations. I will then provide a description of Longreach s (as it would appear) unique fluoridation system and its effectiveness. The system is due to be commissioned by June this year. Keywords Fluoride, bore water, dual reticulation system, blending
Introduction Longreach had a dual reticulation system a potable river water supply and a non-potable bore water supply. Both systems were aging. After many years of Councils failing to adequately address the issue of having two reticulation systems, both systems were in need of urgent attention. The main reason that the issue was not addressed was political, definitely not technical. However, to a certain extent, due to mismanagement, it became a major financial issue that needed to be addressed. Finally a decision was made by Council to decommission the bore water reticulation system, blend the bore water with the river water and replace the aging river water mains. Longreach is a small quiet country town in remote Queensland. This paper will provide details of the journey that lead to Council s decision and the public relations and politics that played out on what should have been a straight technical matter. Longreach s Water History Bore water was clean and the original source of water. Bore water until 2003 was not rated. Therefore residents used bore water for laundries, showers and sinks. Bore water provided natural hot water to lots of residences. The river water was provided as raw water until 1960 s. The treated river water quality was poor until 2006 when a new water treatment plant was installed. As the river water quality increased the bore water usage decreased. In 2009 Longreach s water consumption was 95% river water & 5% bore water. The condition of the two reticulation systems The bore water system The average age of the pipes were over 45 years old, one bore was 84 years old and the other 111 years. Bore water mains breaks were 2.9/km costing $2,240/km. Losses were never determined. The river water system The river water system average age of pipes was over 50 years old with 10% over 75 years old. Anecdotally from the plumbers there were still sections with wooden pipes still in use. The Water Treatment Plant and raw water pumps were less than 5 years old. River water mains breaks were 1.4/km costing approx $1,900/km. There was 35% unaccounted for losses. This equates to 700Ml/year, which equalled our residential metered consumption, or 1240 l/connection/day or 22 l/s loss throughout the system. Two different leak finding companies only found leaks to the order of 0.2 l/s throughout the system but both concurred with our calculated losses. The leak detection companies put the discrepancy down to not being able to detect the leaks in reinforced concrete pipes. Technical History At least nine reports for various purposes, on water and sewer, from various consultants and state entities, were commissioned by various councils over 50 years. One report was commissioned in the 1960 s and the rest from the 1980 s to 2005. All recommended decommissioning the bore water system. As the bore water adversely affected the sewage with respect to salts, the sewer reports also recommended decommissioning the bore water system. Political Constraints Politically it was not palatable to decommission the bore water. Despite the numerous technical reports previous council s had not acted decisively and both systems limped along without any work, because (in my opinion), the previous Council s new that decommissioning the bore water was the right thing to do but didn t want to make the decision as it would be unpopular. Council did not allow new connections to bore water and once disconnected could not reconnect the bore water (based on planning reports).
Council s Strategy Amalgamations came and left Longreach Regional Council with a solid corporate structure and no time for councillors to be worried about potholes etc. That is the council was able to think strategically. Council commissioned another report regarding the water system in Longreach with the aim of once and for all determining the viability of the bore water system. Council ownership of the report was achieved by drafting up a table of contents and then asking council to advise what areas they wanted to cover. Council staff then made sure the areas were covered by the consultant. The Survey for the Bore Water Viability Report A survey was undertaken as part of the report. The results are summarised below. 293 surveys were returned (approximately 20% of what was issued), 250 had the ability to connect to the bore water system and 243 were connected. Approximately 50% received cold bore water all the time, 18% hot bore water all the time and the remainder a mixture of varying degrees. 84% had hot water systems. 90% of residents had rain water tanks which they used for drinking water. Various comments were recorded which reflected community concern that river water alone will not sustain Longreach s growing water demand, especially during drought. The bore water is predominantly used for domestic purposes. When asked the question, if the annual bore water rates increased by 5, 10 or 15% per year would they remain connected to the bore water, the following data was collected. A 5% increase would mean that 32% would disconnect and 54% would stay. A 10% increase would mean 44% would disconnect and 36% would stay. A 15% increase would see that 50% would disconnect and 27% would stay. It was quite evident the community wanted the service but did not want to pay. The Findings of the Bore Water Viability Report The report indicated that the bore water system was economically viable providing the bore water disconnections were less than 1% per year and that there was a rate increase of 6.67% per year. Based on the survey results regarding rate increases and the trend of disconnections over time it was clear that the bore water system was not economically viable. Water consumption was found to be reasonably consistent over 30 years with river water spiking and falling to meet demand induced by seasonal affects. The bore water was on a steady decline well before any indication that Council may investigate the viability of it. The report indicated that there would be a very long delay to any required augmentation of the river water supply. If the status quo was maintained, Longreach was forecasting an augmentation of the river water supply within 5 to 7 years. By reducing the unaccounted for losses from approximately 35% to 10% the augmentation was forecasted to be required in approximately 40 years. By blending the bore water this was increased by another 10 years. As the Longreach Water supply only has approximately 15 months capacity it relies heavily on yearly rain during the wet season to replenish the resource. The blending of the bore water would increase the capacity by 6 weeks, thus allowing extra time for rain to fall and hence assist with drought proofing the township. The bore water is naturally high in Fluoride, which is the only reason it is un-potable. The report indicated that if the bore water was mixed with the potable river water supply it would meet the obligation of dosing water for Fluoride.
Councils Decision The report was adopted by council. Council decided to decommission the bore water reticulation system and blend the bore water with the potable river water system. Council committed to $10M over 7 years towards the river water mains replacement. Public relations The bore water issue was a major catalyst for the formation of the Longreach Regional Residents Incorporated (LRRI). The campaign that was pro bore and anti-council was relentless. There was public consultation hosted by Council to present the Bore Water Viability report. This was met with a protest a month later. Council s newsletter was met with LRRI newsletters, media reports and letters to the editor. 22 letters to the editor were published over a span of 45 papers from September 2008 to July 2009, all negative none positive. Blending for Fluoride The Water Fluoridation Regulation 2008 Schedule 2 lists the prescribed fluoride concentrations for all local government areas in Queensland. Section 6 of the Regulation specifies that a public potable water supplier for a public potable water supply that adds fluoride to the water supply must maintain the prescribed fluoride concentration, for the water supply, mentioned in subsection (2). The prescribed fluoride concentration for the water supplied located in Longreach is 0.7 mg/l +/-0.1 mg/l for each day averaged over a quarter. A review of historical water test results for the new bore and previous bores at Longreach, and locally for the Thomson River, found a range of fluoride concentrations for bore water between 4.8 to 6.0 mg/l, and for Thomson River water ranging from 0.1 to 0.24 mg/l. The proposed 10% (10:90, new bore water: river water) shandy was determined based on these natural fluoride concentrations. The maximum and minimum combinations of those values would give the town water supply fluoride concentrations ranging from 0.57 to 0.82 mg/l. The concentration would be 0.67 mg/l based on the new bore water and river water test results. The Water Treatment Plant (WTP) was designed to deliver water at between 63 and 126L/s. The bore water would need to range between 6 to 15 l/s to satisfy all possible ranges of flows into the WTP. The new bore is artesian and flows free to the surface at approximately 4 L/s. A 120 hour draw down indicated that the draw down would range from 25 m to 110 m below ground level, dependant on the flow. There were a number of advantages of using bore water as a fluoride source as compared to conventional fluoride dosing such as:- the installation and operation of bore infrastructure is less problematic than that of chemical dosing equipment; the technical resources required are not as skilled as those needed to maintain and operate a fluoride dosing system; existing staff are already familiar with bore hole pumping equipment; the need for additional chemical supply and handling is eliminated; the bore provides an additional water source to supplement the river water supply; The demand on river water will be significantly reduced and consequently extend the storage time of the river water at the weirs; Lowest WHS risk option; Low environmental risk; and Lowest operating cost option. Change of legislation The Water Fluoridation Act and Regulations 2008 did not contemplate using a natural source to dose for Fluoride. It contemplated the situation where a water source had appropriate levels of fluoride naturally and also conventional dosing arrangements. Therefore Council lobbied to change the act to accommodate its proposal. The Act was amended to suit Longreach s situation and allowed council to access State Government funding for Fluoride Dosing Infrastructure.
Technical Details of the Associated Fluoride Dosing Infrastructure The bore is 850m deep with 150 m of 168 mm slotted casing in the aquifer and 219mm to the surface. One of the major technical difficulties was overcoming the suspected 10% gas content in the bore water coupled with its temperature of 75 degrees celcius. This restricted the choice of pump to a shaft driven Mono Helical Rotor Positive Displacement pump. The motor is controlled by a Variable Frequency drive. The pump is automatically controlled based on operator set points. The mixing occurs near the Sodium Hypochlorite dosing point and is mixed in the transfer tank before being received into the Ground Level Reservoir. The dosing is monitored by manual grab samples. Conclusion Despite poor public opinion, legislative and technical obstacles Longreach Regional Council implemented a decision that was economically, socially and environmentally sound. The blending of bore water with the potable river water has better utilised the bore water resource, supplemented the river water resource, assisted with drought proofing Longreach s water supply, delayed expensive water augmentation projects and provided natural fluoride dosing to its potable water. Acknowledgements Worley Parsons, Water Supply Assessment Bore Water Viability Study, December 2008 Worley Parsons, Water Supply Assessment Additional Work for - Bore Water Viability Study, April 2009 Worley Parsons, Fluoridation Concept Design Report, November 2010 Author Biography Name: John W. Roworth Born: 1971 Nationality: Australian Qualifications: Bachelor of Engineering (Civil) University of New South Wales, 1993. Affiliations: Member of the Institution of Engineers, Australia. Member No: 972820. Chartered Professional Engineer - Institution of Engineers, Australia Registered with the National Professional Engineers (Australia) No. 972820. Registered Professional Engineer of Queensland. No. 11929. Member of Institute of Public Works Engineers Australia, Queensland Summary of Experience Eight years in construction (Australia, PNG, Singapore and UK). All facets of project management from direct supervision of labour, subcontractor management, client liaison, quality, safety, environment, traffic management, estimating, procurement and programming. The nature of the work varied considerably across heavy industrial civil works, civil works, marine works and building works. Five years as a consultant (Australia). Focus on local government specialising in tender and contract administration, water works, building works, roadworks and civil works. Five years as a local government engineer (Australia). Roadworks, water works, building works and civil works. Contact Details: Longreach Regional Council PO Box 472 Longreach, QLD 4730
Email: engineer@longreach.qld.gov.au