AUSTRALIAN WATER & WASTEWATER ASSOCIATION
Volume 23, No 2 March/April 1996
Editorial Board
CONTENTS
F R Bishop, Chairman
ASSOCIATION NEWS 2
From the Federal President From the Executive Director
4
MY POINT OF VIEW 3
NCP - Will it Hurt?
D Sheffield
FEATURE - PIPES 6
P Ferguson, M Heathcote, G Moore, D Russell 9
Predicting Underground Pipeline Failure
G Constantine,] Darroch, R Miller 11
Australasian Corrosion Association
D Nicholas 12
'PIRAT' - Non-Subjective Sewer Inspection and Assessment
G Campbell, K Rogers,] Gibert 16
South Australia's Pipelines
EA (Bob) Swinton 18
Assessing Melbourne's CBD Sewer System
S C Carne, A M Norrish
WATER 21
Removal of Algal Toxins Using Membrane Technology
M Muntisov, P Trimboli
WASTEWATER Iron Chlorides for Filamentous Bulking: Laboratory Investigations
24
I Sosa-Sanchez 26
BUSINESS 30
A Pender 33
C Davis
ENVIRONMENT 34
JS Abbott OZWATER & OZWASTE 96 EXHIBITION CATALOGUE
Supplement
DEPARTMENTS International Affiliates From the Bottom of the Well New Products Books Meetings
Branch Correspondents ACT - Ian Bergman Tel (06) 248 3133 Fax (06) 276 1997 New South Wales - Mitchell Laginestra Tel (02) 412 9974 Fax (02) 412 9876 Northern Territory - Graeme Reed Tel (089) 82 7346 Fax (089) 82 7221 Queensland - Ted Cusack Tel (07) 3831 7316 Fax {07) 3832 1625 South Australia - Peter Martin Tel (08) 303 8723 Fax (08) 303 8750 Tasmania - Dao Norath Tel (002) 332 596 Fax (002) 347 559 Victoria - Mike Muntisov Tel (03) 600 1100 Fax (03) 600 1300 Westem Australia - Alan Maus Tel (09) 420 2465 Fax (09) 420 3178
is published six times per year January, March, May,July, September, November by
Australian Water & Wastewater Inc ARBN 054 253 066
Federal President Mark Pascoe Executive Director
PMartin
Key Issues for Irrigated Agriculture in Australia
E A (Bob) Swinton 4 Pleasant View Cres, Glen Waverly Vic 3150 Tel/Fax (03) 9560 4752
WATER (ISSN 0310- 0367)
L Walker
Antipodean Team to UK Water Industry
Editorial: Helen Cumming Advertising: Sandra Brennan PO Box 388 Artarmon NSW 2064 Level 2, 44 Hampden Road, Artarmon Tel (02) 413 1288 Fax (02) 413 1047
22
Bringing Water to the People
Transforming Government Business Enterprises
Advertising & Administration AWWA Federal Office
Features Editor
Condition Assessment of Water Mains Using Remote Field Technology
Reuse of Sewage Effluent
B N Anderson, G Cawston, M R Chapman P Draayers, W J Dulfer, G A Holder M Muntisov, P Nadebaum,J D Parker AJ Priestley J Rissman
4
25 38 38 39
Chris Davis Australian Water & Wastewater Association assumes no responsibility for opinions or statements of facts expressed by contributors or advertisers and editorials do not necessarily represent the official policy of the organisation. Display and classified advertisements are included as an informational services to readers and are reviewed by the Editor before publication to ensure their relevance to the water environment and to the objectives of the Association. All material in Water is copyright and should not be reproduced wholly or in part without the written permission of the Ei!itor.
Subscriptions Water is sent to all members of the AWWA as one of the privileges of membership. Non members can obtain Water on subscription at an annual subscription rate of $35 (surface mail).
PIPES
CONDITION ASSESSMENT OF WATER MAINS USING REMOTE FIELD TECHNOLOGY P Ferguson*, M Heathcote, G Moore, D Russell Summary The principles of Remote Field Technique {RFT) for Non-Destructive Evaluation {NDE) of water pipelines are briefly described. The performance of an RFT tool is also described, along with an evaluation from Australian field trials. A total of three sections of pipelines were examined in Sydney and Adelaide, and there is an excellent agreement between the RFT analyses and the exhumation results. Furthermore, the RFT analysis indicates that not all sections of a pipeline, earmarked for replacement, need replacing in the immediate future. Consequently, the technique provides an opportunity for the Water Industry to reduce costs for renewal projects and to ascertain the condition of critically located assets.
Keywords Nondestructive testing, water pipes, asset management, condition assessment.
Australia's Network In 1995 Australia's water pipeline network is estimated to be longer than 107,000 km and conservatively valued at A$ l 6 billion. Of this, approximately 72,000 km is metallic pipe - principally grey cast iron, ductile iron and steel. The remainder consists of non-metallic pipe, almost exclusively asbestos cement and unplasticised polyvinyl chloride. More than 16,800 km of sand cast iron pipe is still in operation in Australia, some of it more than 150 years old with the average age of this "type" of grey cast iron estimated at 85 years. Spun grey cast iron was introduced in the 1920s and its average age is estimated at 35-40 years. Initially, all sand cast iron pipelines were installed without internal or external corrosion protection, with cement lining being applied in-situ to most of these pipelines after the Second World War. Factory spun linings were introduced in the 1920s, and the majority of spun cast iron pipe is lined with the better performed factory-applied lining. However, external corrosion protection was not commonplace until the early 1970's. Although grey cast iron pipe enjoys a ~ood record of performance in Australia (two major water authorities define the "life" of grey cast iron pipes as 120 and 150 years for their asset value calculations) , its average age will increase and so 6
will the number of failures. Traditional techniques, such as soil testing, pipe sampling and statistical failure modelling, employed to ascertain the condition of existing mains provide some information but are unable to precisely locate positions of corrosion defects along a pipe/pipeline.
Remote Field Technique In simple terms, the remote field technique {RFT} uses the principles of Remote Field Eddy Current to measure the wall thickness of a pipe by sensing the attenuation and phase delay of an electromagnetic signal which has passed through the pipe wall. The signal is induced into the pipe by an internally placed solenoidal coil which is energised by a low frequency alternating (a.c.) current. This generates eddy currents and a magnetic field which radiates from the exciter. The electromagnetic field attenuates with distance and shifts in phase as it travels away from the exciter. At a distance of about three pipe diameters, the field in the pipe wall is stronger than the field within the pipe, and can be detected by sensors positioned in the pipe in this "remote field region". (See Figure 1) In effect, the electromagnetic energy has made a double transit through the pipe wall, and measurements of its attenuation and "time of flight" can be directly related to the pipe wall thickness. The signal arriving at the detector is typically very small (only a few microvolts) and very sensitive electronics are required for its measurement.
History of Development The technique existed as a nondestructive inspection tool for more than 40 years, and indeed a "remote field tool" was patented in 1951. Early development of the technique was performed by Shell Development for inspecting oil well casings and small diameter oil pipelines. However, early instruments lacked sensitivity to small pits and further development stalled until digital electronics and fast computers became readily available. Additional investigatory work was performed by Shell Development in 1978, based largely on theoretical considerations, and a large proportion of this research was verified by Colorado State University in 1986 using Finite Element Analysis (Schmidt 1989). In more recent applications, the
Remote Field Technique has been used in the Water Industry, and in 1992 an American Water Works Association Research Foundation report summarised available Non-Destructive Evaluation (NDE) methods with possible application for evaluation of the condition of water mains. A conclusion reached from the survey was "the remote-field eddy current inspection by Russell Technologies (RTI) was the most successful method evaluated in this study" (AmWWA, 1992). Following this report, RTI conducted field trials on 6" cast iron pipe, in Calgary, Edmonton, and in 1995, Sydney and Adelaide.
RFT NDE Tool Non-Destructive Evaluation (NDE) tools such as Hydroscope 201TM, use the principles of Remote Field Eddy Current to detect thickness variations in ferrous pipes. The RFT NDE tool (Figure 2) consists of a train of sealed modules containing excitation and detection coils, processing and data transmission electronics. Each individual pressure module is connected to the next by U-joints. The train of pressure modules are connected via a 1000 metre wireline to a host computer above ground. The tool is designed to traverse 90° bends and tees and is currently sized to fit 150mm and 200mm pipe. It is propelled through the pipe either by water pressure or by winching, at a speed up to 12 metres/ minute. The tool records data only when moving which is logged to the hard drive at the rate of 660 samples per metre. This translates to one sample per 1.5mm, which sets the axial resolution. At speeds greater than 12m/min, some data points may be lost. Each module of the tool is equipped with brushes which are designed for centralisation in the pipe, which may be cement mortar lined (insitu or centrifugally applied) or unlined {with small amount of tuberculation). The total tool clearance in clean unlined 150mm pipe is 50mm. Phase and amplitude readings are measured by the detector coil. The readings are then amplified, fiJtered and digitised for transmission to the above ground computer. The computer gathers, stores, processes, displays and prints data. Data can be displayed in chart form (Figure 3), where phase and amplitude • Tubemakers Pipelines Research Centre, 63 Haig Street, Southbank 3006 WATER MARCH/APRIL 1996
changes are shown as individual traces, or in polar form (Figure 4), where phase changes are displayed as changing vector angles, and amplitude as change in vector distance.
Performance of RFT NDE Tool Under ideal conditions the Hydroscope 201 TM has a resolution for "general" corrosion of 50/o of nominal wall thickness, and for "pitting" corrosion, 200/o of wall thickness over an area of 50mm in diameter. The presence of appurtenances such as property service connections, other large defects and fittings can in some situations "mask" the detection of small defects. Field trials were conducted in the summers of 1994 and 1995 in Canada, through a partnering arrangement between RTI and the City of Edmonton. ·several mains were tested with the first prototype tool, and subsequently excavated, cleaned and visually inspected. The results obtained by the RFf analysis provided good correlation with those obtained from the visual examination. (Staples, 1994) In order to ascertain the performance of the RFf technique, three 150mm cast iron pipelines were inspected in Australia in April 1995. Details of the 150mm pipelines are given in Table 1. From the detailed RFT analyses (Figure 5) the probability of short term failure for individual pipe length in each of the three lines was assessed, and assigned a value from 20 to 100 (100 representing a high probability of failure). The assessment was based on consideration of both minimum residual wall thickness and area of corrosion. Following the exhumation and subsequent grit blasting of 37 "pipe lengths" from the three sites (10 from South Strathfield, 21 from Merrylands, and 6 from Ottaway) each pipe length was assessed independently from the RFf results, but by using a similar assessment criteria. In the case of assessment of exhumed pipe however, only wall losses due to effects of external corrosion were considered as it was difficult to grit blast the bore of each pipe. The comparison of results obtained from the RFf analysis with that of the exhumations is depicted in Figure 6. There is very good agreement (less than 100/o variation) between the RFf analysis and exhumation results for 89.2% of the pipe lengths. Some difficulty existed with the RFf analysis of the Ottaway pipeline, but this is most likely due to the peculiar structure of the statically cast iron pipe. In simple terms, the structure consisted of a region containing a large amount of non-metallic material "sandwiched" between two outer layers (external surface and pipe bore) of cast iron. Accordingly, the RFf analysis has underestimated wall thickness. The results of the RFf analysis and observed condition from exhumation for the Ottaway pipeline is shown in Figure 7. WATER MARCH/APRIL 1996
Table 1 Australian RFT NDE Fie/,d Evaluation Locations Location
Length Length Analysed Exhumed m m
Age
Pipe Type
. yr
1. South Strathfield
Vertically Cast Iron
Sydney, N.S.W.
(native soil backfill, c.m.l. in·situ & lead joint)
2. Merrylands Sydney, N.S.W.
Spun Cast Iron
84
50
36
45
59
59
55
123
24
(native soil backfill, s)un c.m.l. .& lead joint
3. Ottaway Adelaide, SA
Vertically Cast Iron (native soil backfill, srn c.m.l. & lead joint
metal pipe wall
.. .........................
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··::.·.·.·::::::.·:::.·.·:.·:.·.·::::::-:.:·.:·.:·:·- ..
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detector coil
............ _........
exciter coil
Figure 1 Remote fie/,d technique for inspection of metal tube
Printer
Wnch
Data Acquisition and Analysis
Wreline
Pig
Exciter coil
Processing eledronics
Towing
Detector coil
adapter
Figure 2 An example of an RFT NDE tool - Rll's Hydroscope 201 TM
file
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e.
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Figure 3 Run-chart format of data from RFT NDE tool
7
Practical Outcomes
Wall Thickness Profile: Chester St MNNWEiiffW 100
100
90
90
80
80 70 60
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Odometer in Metres
Figure 5 An example of the detailed RFI' analysis 50r---------------------~
Conclusions
40
The RFf technique is an accurate and practical method to ascertain the condition of buried small diameter pipelines such as cement mortar lined grey cast iron. It offers the water industry an opportunity to reduce costs by replacing only sections of pipelines with that have a high probability of failure in the near future.
30 C
One practical outcome of an RFf analysis is to provide guidance on when and where to replace sections of a pipeline. Individual pipe lengths can be categorised into those which should be replaced immediately (within 1 year), those which should be replaced in 10 years, and those which will not need to be replaced for at least 20 years. This consideration involves the use of RFf data (depth and extent of corrosion) and operational factors (e.g.. maximum operating pressures, likelihood and magnitude of surge pressures, so11 conditions, traffic loading). From the RFf analysis of the Chester Street, Merrylands main (and subsequently verified by exhumation observations), only 30% of the existing section of pipeline earmarked for replacement using 'main break data', needed to be replaced immediately, and the remaining 70% could have remained in service for at least 10 years. This modified "replacement schedule" represents a cost saving of approximately 40% (based on discount rate of 10% and taking into account RFf analysis costs) compared with the traditional approach. An RFf analysis also ascertains the condition of mains which are classified as "critical" (those operating beneath major roadways, railways and shopping malls and centres). In these mains, no failure is tolerable, and everx effort is employed to minimise the probability of failure.
20
~ 10 QI ¡c 0 t-,-,r------~-.-----'--'----------'L-.L.L...L~ :1: Ottoway -10 -20
-30
References
~0L-J.......-L__.__JL......J.-..L......L........L......L....-L__._j~L.......L.-...L...-1.-._J_.......L............J.~L.......L..I
AWWA, (1992), American Water Works Association Research Foundation Report ¡ "Nondestructive Testing of Water Mains for Physical Integrity" Schmidt, TR, (1989), Materials Evaluation, 47, pl4 Staples, LB, (1994), Proc. Seminar on Trenchless Technologies, Montreal
3
5
7
9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 Pipe Length
Figure 6 Variation ofRFI' analysis to observed condition
High D RFT Iii Exhumation
Authors
Low 56
57
58
59
60
61
Pipe Position
Figure 7 Results of RFI' analysis and pipe exhumation for Ottoway pipeline (statically
cast grey iron pipe containing internal defects and lead joints) 8
Philip Ferguson, BSc, UNSW, is Pipeline Metallurgist for Tubemakers Pipelines Research Centre and manages their RFI' business. Greg Moore, BAppSc in Secondary Metallurt:1, is Principal Materials Scientist with the SA Water Corporation's Technology Division. ' Mark Heathcote, BSc, UNSW, is Materials Technologist in Materials and Standards Group of Sydney Water. Dave Russell is President of Russell Technologies Inc and teaches NDT at Northern Alberta Institute of Technology. WATER MARCH/APRIL 1996
PIPES
PREDICTING UNDERGROUND.PIPELINE FAILURE G Constantine*, J Darroch, R Miller Abstract A model for the prediction of future numbers of pipeline failures for underground water mains is described. The model uses historical failure data, which may be incomplete, and asset and environmental information. Applications of · the model for asset management are briefly described.
Keywords Asset management, corrosion, failure prediction, pipeline failure, statistical modelling
Summary This paper describes a method· for modelling pipeline failure patterns and the use of this method for predicting future failure numbers and other quantities of interest for asset managers. The model fitting requires historical data on failures together with asset information and any operating and environmental variables that may be available. These environmental variables may be quite simple, eg. a soil classification description or a town planning zone classification for each pipeline asset. An important feature of our model is that it can be used when data is incomplete. Most, if not all, computerised databases of pipeline failures do not contain complete information on all failures of older pipelines. If sufficient environmental information, such as soil type, is available, prediction of failure numbers can be carried out on an individual asset basis. Otherwise, only larger scale prediction is possible, eg. the total number of failures in a region. Possible areas of application of the model include: • the highlighting of those assets which are candidates for replacement, and the impact on maintenance requirements of replacing or not replacing • the impact on customer service requirements such as the number of unplanned service stoppages • long-term assessment of infrastructure performance, residual life of assets, etc.
Introduction An efficient method for the prediction of future numbers of failures of underground pipeline assets has many applicaWATE R MARCH/APRIL 1996
tions and benefits to asset managers who need to make decisions for short- and long-term planning. Most urban areas of Australia have a significant proportion of aging, deteriorating assets (some 25-30% of pipelines were installed before 1930) and the rate of installation of new and replacement assets has been far from constant over the years. Pipes have been constructed using different materials, which may have different economic lifetimes, and are buried in soils of widely different corrosivities. For the short-term, typical decisions required of asset managers are: • how much should be budgetted for maintenance (ie. repair of failures) for the next financial year • whether a particular asset be replaced or continue to be repaired. In addition, government regulatory authorities may demand minimum levels of service such as, say, no more than three unplanned interruptions of service per year to customers. For the longer term, issues such as intergenerational equity, the ability to foresee possible increasing failure rates are important as well as being able to assess the 'condition' of assets, or their proneness to failure. Failure patterns are notoriously variable and merely using the past few years failure history of an asset can be misleading. A common method for examining maintenance replacement strategies is carrying out 'what-if scenarios. What would be the result if the worst 11cm of assets is replaced now? The result can be quantified as the reduction in expected number of failures, and improvement in customer service requirements, and, of course, has to be assessed economically in terms of the large capital costs incurred in replacement. The method outlined below should enable asset managers to make their maintenance and replacement decisions with much better accuracy than is currently available.
Pipeline Failure Modelling Failures or breaks in pipelines can have several causes including: • mechanical, due to earth movement • installation, eg. improper bedding and jointing • corrosion.
Newer materials and improved installation methods . have reduced some of these problems in recent years. Ideally, failure databases should include the cause of each failure, though it is common that this data is either not recorded or is unknown. If such data is available, and is reliable, then each failure cause can be modelled separately. In the d~ta sets we have analysed to date, no causes were recorded but we were informed that corrosion was the principal cause in those areas. A typical failure pattern for a pipeline is an essentially trouble-free period during, say, the first 20-30 years of life, followed by a sequence of failures slowly increasing in intensity. Among the factors that may affect the failure rates are: • environmental conditions, such as soil type and overhead traffic • operating conditions, such as water pressure · • asset features, such as construction material and pipe size. Our model assumes that the number of failures, N(t), of an asset aged t years is distributed with mean: H(t) = at ' (For the technically minded, the statistical assumption is that N(t) is distributed as a Poisson random variable with mean H(t). The failure times then form a non-homogeneous, time dependent Poisson process). In principle, the parameters a and b may vary from asset to asset. We have found, however, that the shape parameter b appears constant and, in fact, is about the same for both AC and CICL pipes. The parameter a does vary according to the environmental variables and asset factors such as material. The condition of an asset aged t years we define as: C(t) = abt 1 · 1 the derivative of H(t). The higher the condition index, the more likely it is to fail. Figure 1 shows four fitted failure curves for AC (Sutton), AC (Mazza), CIS and CICL pipes in the Ringwood area of eastern Melbourne (averaged over all other factors) and standardised to 100 metres length. It is of interest that we found the value of b to be very close to 2 for Ringwood and other areas of Melbourne whose data 1
*CSIRO Division of Mathematics Statistics, Bag 2, Glen Osmond, 5064
and
9
we have analysed. This means that the curves in Figure 1 are quadratics, and the condition indices, C(t), are simply: C(t) =2at That is, the condition of these assets is proportional to their age, perhaps not unexpectedly, and the proportionality constant depends on factors such as material and soil type. If sufficient information is available, the parameters a can be estimated for each individual asset. We have found that soil type is the most important variable in explaining variation in failure numbers from asset to asset, with road traffic type (or town planning zone classification) significant but of less importance. Of course, a also depends on pipe material and size. The soil type influences corrosion in a complex manner, which is still not fully understood. Nevertheless, a simple classification of soil type into sand, clay, loam, etc, goes a long way towards
explaining asset-to-asset variability. Algebraically, the values are modelled by the log-linear form
not feasible), prediction is straightforward. For an asset aged t years, the predicted number of failures next year is simply
where l; is the length of the zlli asset, are variables describing the explanatory variates (ie. soil type, etc) and c1 are regression parameters to be estimated. We shall not go into statistical details here, but note that the xij can be thought of as dummy variables representing, eg. presence/ absence for a soil type, material, etc.
Such numbers can be totalled over all assets in a region, or in a smaller group such as a shut-off block. Prediction two, three or more years ahead is given by the obvious formulae. Various maintenance and replacement strategies can be examined by the use of the prediction formula. We suggest using the condition index (abt •·1) to identify those assets in poorest condition, and then computing the effects of replacing some total length of assets per year. That is, compute the expected number of failures in the remaining assets. As an example, Figure 2 shows the impact of replacing the worst 1km, 4km of assets in a region containing 120 km of pipes. The reductions shown in the numbers of failures indicate what level of replacement is required to maintain the region assets in the current level of service. Projecting these curves further into the future allows for a quantitative assessment of intergenerational equity . Economic lives of assets can be predicted in the usual way, the failure numbers can be predicted into the future and cost curves, usually in terms of net present value, can be computed. Other applications of the modelling are possible. We shall not go into all of them here, but welcome enquiries from interested pipeline asset managers.
xij
Prediction Once the parameters a and b have been estimated for each asset, (or each group of assets if individual estimation is
ACMZ ACSU CICL CIS
"'
,. /
/
.....
,/
/
/
.,..-···
--- --- ---
---
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10
20
30
40
60
50
age (years) FIGURE 1
Acknowledgements
Figur_e 1 The curves show the average failure numbers with age of assets constructed of the
materials asbestos cement (A C MaWJ, and A C Sutton), cast-iron concrete lined (CJCL), and cast-iron concrete lined in situ (CIS)
We acknowledge the support of Melbourne Water, particularly Randall Scott, and the UWRAA in funding our research.
Authors fi!
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0km 0.5km 1km 1.5km 2km 2 .5km 3km 3 .5km 4km
<I)
0.
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0
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1990
1992
1994 years
1996
1998
FI GURE 2
Figure 2 The curves show the predicted total number offailures in a region over a ten year period. Different curves correspond to a different replacement strategy
10
Graham Constantine has a PhD (Yale University) in Statistics, and has worked in the CS/RO since 1955. He is currently carrying out research and consulting in the area of industrial statistics with particular interest in reliability and maintenance scheduling. John Da"och, Professor of Statistics, Flinders University of SA, has wide ranging interests in statistics and has recently been collaborating with Graham Constantine in reliability theory. The pipeline reliability work has been partially funded by the UU'RAA. Ros Miller graduated BSc from the University ofAdelaide and is a member of the Q,uality Improvement Group of CS/RO Division of Mathematics and Statistics. In addition to the pipeline reliability project, she has worked in the area ofassessment ofsurface roughness and other industrial statistics projects. WATER MARCH/APRIL 1996
PIPES
¡AUSTRALASIAN CORROSION ASSOCIATION Report by D Nicholas The water industry is built around assets with extraordinarily long service lives. Successfully achieving these lives requires a multidisciplinary approach. Materials and corrosion science pay a key role in this approach. One of the primary activities of both ACA and A WWA members is to provide professionally realistic solutions to the problems of the . water industry. The recent ACA Perth Conference amply illustrates this fact. As an aside, the water industry has contributed at least two presidents to the ACA in the last nine years, with a further AWWA member scheduled for 1997. There is now a separate program at ACA conferences for the water industry, and a committee, of which I am the chairman, dedicated to water that operates within the international framework of the ACA (New Zealand ACA practitioners already liaise with their water industry colleagues). Asset management (and the maximising of asset life) is an area of endeavour which has attracted the talents of many ACA water industry members in recent years. There is no better evidence of this fact than the paper by Ferguson, Heathcote, Moore, and Russell on 'Condition Assessment of Water Mains Using Remote Field Technology' (see this edition of Water). It's not very often that a matter of this significance to the industry is presented. I can certainly attest to its impact on the audience when presented by one of the authors, Canadian Dave Russell of Russell Industries, the developer of the process. At last, a tool is available which will actually deliver accurate assessments of remaining asset life. The only questions in my mind are: Will it be used ?' Will the obvious benefits be recognised by the industry? The broader issues of asset management were detailed by Les Boulton and Peter Wilson of New Zealand's Industrial Research Limited. This work detailed a vigorous methodology to predict asset lives in New Zealand's water industry. I found it particularly intriguing that the software package developed for this water infrastructure model was actually developed in Melbourne (see Byrne & Leonard, Water, September) . Titled 'Assessment of the condition of corrodible underground structures in the water industry', Les Boultons' flawless presentation was succinct and informative. He described the methodologies needed to WATER MARCH/APRIL 1996
determine when buried pipes, fittings and other components can be left undisturbed, when they can benefit from rehabilitation or when total replacement is needed. The authors divided the investigation required into three phases, and produced a structured life assessment philosophy designed to give a utility a total picture of underground performance. Logically following this paper, Gordon Stewart's offering 'Material standardisation of the water industry' gave an overview of the work of Australian Water Agencies Quality Assurance Network (AWAQAN, inevitably). This group, with the blessing of most of the major utilities, is charged with creating uniform product specifications within the industry for 'strategic products'. The cost of not having standard product specifications in the past is truly enormous, and AWAQAN carries out an important role. The last paper reviewed here is purely technical, and on a subject close to my heart. 'The influence of surface films and potable water biofilms on copper corrosion'. Brett Wells, also from New Zealand's Industrial Research, gave a professional and concise presentation on an extremely complex subject. Corrosion of copper tubes (nothing, despite advertising, is 'forever') is a perpetual problem in most softwater areas of Australia and New Zealand, manifesting itself as either 'blue water', or in many cases pitting perforation of the tubes themselves. We have previously identified over twenty possible interrelated causes of this phenomena, and Brett described careful research which effectively eliminated one variable, silica, and pointed the finger at another, Microbiological Induced Corrosion (MIC) . The authors admit, however, that there is no simple chemical signature to either of these problems, and research continues, at a pace. The copper paper leads appropriately into another segment of the ACA Conference which is unique in my expe- ¡ rience. Several forums were arranged for a more informal discussion of specific problems, and over sixty people were present for a lively two hour discussion on four water industry topics. Brett Wells continued from his paper to enter into debate with Russell Taylor (CSIRO Division of Material Science, Melbourne) and David Nicholas (Hunter Water Corporation) on the influence of pH, bicarbonate and silica on the corrosion of
copper tubes. Brett had already eliminated silica as a contributor to corrosion, but as far as Hunter waters were concerned David was not so sure, thus lively debate eventuated. For something completely different, Sam Costin of Vinidex Tubemakers extolled the virtues of High Density Polyethylene (HDPE) as a pipe material for drinking water. He showed a video to demonstrate some novel methods of continuous pipe burial in outback Western Australia, and remarked pointedly on its superior corrosion resistance, thus severely upsetting some corrosionists whose livelihoods were instantly at risk. More seriously, it is important to realise that materials other than metals can provide solutions to problems, and healthy debate between proponents of different systems is actively encouraged in the ACA Water Forum. Graham Sussex (ETRS) then detailed case histories of several galvanised cooling towers in Australia. Despite waters falling into a so-called 'safe' analysis, and judicious use of inhibitors, these towers are now corroding at an alarming rate. Phil Ferguson (Tubemakers) and Greg Moore (SA Water Corporation), two of the authors of the eddy current paper presented earlier, talked about some local case histories and extended the debate to cover all the various options available of life assessment of underground water structures. The consensus, as you might expect, was that the remote field eddy current NDT method provides information several orders of magnitude better than the existing indirect methods. From an economic perspective, the inspection costs can be easily reclaimed if only a small percentage of pipes in a given line can be shown to be sound and not in need of replacement.. Corrosion conferences can be of real value to generalists in the water industry, and I heartily recommend them to all AWWA members. A unique feature of the Articles of the ACA water industry group, is an express desire to foster useful collaboration with the AWWA. This has already started to occur, and the first significant steps should already have been taken. Currently we are having ACA-AWWA discussions on joint local branch meetings so the full benefits of the synergy between the two can be realised. 11
PIPES
1
PIRAT' - NON-SUBJECTIVE SEWER INSPECTION AND ASSESSMENT G Campbell*, K Rogers,] Gibert
This paper is an edited version of papers presented at Pipes Wagga Wagga in August 1995, and at NO-DIG 95, in Dresden, Germany.
Abstract Assessment of sewer condition is an increasing priority world-wide. CCTVbased assessment is the norm, but it is error prone and subjective, and prone to operator inexperience. In response, Melbourne Water and CSIRO have undertaken development of a new qualitative technology, PIRAT. A prototype system for operational sewers has been developed and applied to 4 km of 600 mm sewers in Melbourne. It has demonstrated assessment performance superior to good CCTV operators. It has also provided new information to aid selection of the repair methods. The PIRAT technology measures the internal geometry of the sewer by laser or sonar scanners, which, together with a CCTV system, are mounted on a sewer tractor operated from a surface control van. The data is processed by artificial intelligence to rate condition automatically. Aberrant features can be interactively examined later by the asset manager on the computer screen. The paper describes the experimental system and discusses its performance. Development of a simplified prototype system for water authority use will be undertaken with commercial partners.
Introduction Water authorities world wide are giving increasing priority to assessing the condition of their sewer assets. This can forewarn asset managers of potential problems, including the impending collapse of a pipeline These situations result in considerable financial cost to the water authority and seriously erode its reputation. Litigation is an increasing risk. Detection of interior defects is usually the first warning of problems with a pipeline. Currently, inspection normally involves an operator making assessments via the images from a remotely controlled video camera (CCTV). Accurate assessments are not achieved in practice as important defects are hard to discern and the method makes high demands on the 12
skill and concentration of the operator. Detection of subtle defects and assessment of the degree of deterioration are particularly error prone, so the method is adequate only for detecting gross defects. Melbourne Water recognised these imitations and approached CSIRO for a better method. This led to the PIRAT project, wherein the experience of a practicing asset manager was combined with the scientific and technological skills of two divisions of CSIRO. The first stage proved the feasibility and potential of the technology under laboratory conditions. The second stage, which has recently been completed, has developed a system which has demonstrated its potential in operating sewers. The project has run for three years and cost $4.5m to date, and is considered to be a world leader.
The PIRAT System The PIRAT system comprises an in-pipe vehicle, or tractor, which carries the scanners and associated instruments through the sewer and a van which houses data analysis and control equipment, as well as a mobile power supply. The system can be collecting data within halfan-hour of arrival on site. Recovery and clean-up take a little longer. Data can be down-loaded into the corporate computer network. The instrument system, developed by a team at CSIRO Division of Manufacturing Technology (DMT), is used to collect the geometry data, and the interpretation system, developed by a team at CSIRO Division of Building
CCTV console
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Figure 1 The PIRAT System
Construction and Engineering (DBCE), analyses this data to detect, identify, rate and report defects. A laser scanner is used for near-empty pipes and a sonar scanner is provided for flooded pipes. The current system is designed for 600 mm diameter pipe, enabling standard size components to be used. (There are 70 km of 600 mm sewer of different materials in the Melbourne Water system, allowing extensive field trials) .
Instrument System In-pipe Vehicle. Existing CCTV vehicles lacked the required equipment space and their drive systems were unsuitable for continuous measurement, so a custom vehicle was developed for the project. The vehicle design allows maximum clear view for the scanners as well as providing a reasonably smooth ride and creditable ability to clear obstructions in the sewer. All the instrumentation is carried in the in-pipe vehicle, which, together with the CCTV monitor, is approximately 1 m long and weighs approximately 90 kg. The equipment size and design was determined by the standard manhole openings (600 mm diameter) and the need to facilitate deployment into the sewer at the bottom of the manhole. Ground clearance is 85 mm and 700 N of thrust can be supplied to the track system. A CCTV facility is provided for vehicle navigation, to support training of the interpretation system and to improve understanding of the data. The in-sewer equipment is designed to operate up to 250 m from the control van. Distance travelled along the pipe is measured by encoders sensing both track motion and cable motion at the winch. For safe operation in a sewer environment all in-sewer electronics are located in a sealed and positively pressurised compartment in the in-pipe vehicle . Electrical power supply is available only when the internal pressure exceeds the external pressure by a safe margin. Electrical power is also supplied via earth leakage protection devices Six major circuit boards for communications, signal conditioning and sensor â&#x20AC;˘ Melbourne Warer, Box 4342 GPO Melbourne Vic 3001
WATER MARCH/APRIL 1996
Figure 2 Maps of the laboratory test pipe from laser and sonar scanners
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WATER MARCH/APRIL 1996
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and control interfaces as well as scanner support electronics are housed in the eressurised compartment of this vehicle. (In the experimental prototype approximately 30 additional sensors are fitted to provide information for system improvement and re-design} . Figure 1 shows a typical set-up on site. The rear wet compartment of the van houses the cable winch, the in-pipe vehicle, etc .. The forward compartment houses the control, data collection and processing equipment. A Sun SPARCstation 2 provides a Window-based interface for operator controls ·and manages storage of the test data. A CCTV colour monitor with a joystick for vehicle control is provided for manual operation. This is used to drive the vehicle for deployment and to clear in-sewer obstructions. Once the vehicle is deployed into the sewer the complete system is controlled by the computer. Laser Scanner. The scanner is mounted on the in-pipe vehicle so that its axis is nominally at the pipe centre. It projects a radial beam of laser light onto the pipe wall. This beam is rotated to produce a disc of laser light and the reflected light is viewed by a video camera. The geometry of the laser beam, pipe, and camera system are such that deviation from centre of the laser image on the camera sensor indicates the normal distance from the scanner axis to the pipe wall, that is the pipe radius. A 20 mW infra red laser is used to maximise optical performance in minimum space. This laser presents a safety hazard and interlocks and defined operating procedures have been provided to protect staff. The current design allows radii from 230 to 430 mm to be imaged by the camera. The video camera sensor has an array of independent light-sensitive sites called pixels. These represent a radius resolution of approximately 1.5 mm. The speed of rotation of the beam is controlled to 3000 RPM to synchronise it with the scan of the camera sensor (50 Hz}. The scanner housing is pressurised and electrically powered from the in-pipe vehicle. The scanner was custom engineered for the project and includes a number of design innovations to reduce its length, which is important for deployment through a manhole, and to optimise its measurement performance within the optical constraints resulting from scanner pressurisation. Sonar Scanner. The sonar scanner has a rotating transducer which outputs bursts of 2.2 MHz 'pings'. 'The head listens for an echo from the pipe wall before rotating to the next position. Pipe radius is determined from the travel time of the ping and the sonic velocity in water. The 'ping' is transmitted as a beam which contacts the wall of a 600 mm pipe over a 13
small zone. The return sound received at the transducer is a composite of the echoes from all features in this zone. The return is complex from a rough pipe wall, and this complicates signal processing. The return strength is also affected by the angle at which the beam meets the pipe and under field conditions, the return signal strength varies by a factor in excess of five . This further complicates signal processing and an adaptive technique which responds to the characteristics of individual pings is used to extract radius values. The scanner was developed to PIRAT requirements by Simrad Mesotech of Canada. Communications Modules and Remote Link. A key requirement in the system is for the accurate transmission of - data at up to 400 Mbit/s between the in-pipe vehicle and the control room. This data is transmitted along the cable which also carries power for the in-sewer equipment. Optical fibre data transmission is used to achieve the required noise immunity. Communications modules were commercially available for most tasks, but were too bulky for the in-pipe vehicle, so a custom system was designed and manufactured. It provides simultaneous transmission channels for the CCTV video signal, digital video from the laser scanner, digital sonar data, sensor data and system commands. The robust, multi-function 250 m cable connects the in-sewer equipment to the control room. It transfers data, supplies up to 1 kW of power to the in-sewer equipment, and provides low speed links for fallback communications and safety interlocks. It can also be used as a tow rope with 4000 N capacity. During trials, this has been needed to recover a stranded in-pipe vehicle on several occasions. The cable is stored on a rotating drum and electrical and optical fibre rotary
PIRAT
joints are provided to connect the rotating drum with the control equipment. Cable tension is controlled by a novel winch drive which allows fine tension control to minimise drag on the in-pipe vehicle. The winch is controlled by the computer, which slaves cable tension to vehicle motion. This has proved valuable in protecting the cable.
Laboratory and Field Tests Pilot inspections were run in a 600 mm diameter laboratory pipe set-up , comprising approximately 7 m of various concrete and vitrified clay (VC} sections, with a typical manhole, some 3 m high, built at one end. The pipe run was equipped with dummy branches and a number of simulated defects and excrescences were deliberately built in. In the field trials approximately 4 km of various types of operational sewer were inspected with the laser scanner. These were chosen on the basis of CCTV contractor reports to be safe, but with a large number of defects which would provide training data for the interpretation system. Unfortunately, the condition of the sewers did not agree well with the CCTV reports. Often the reported defects did not appear or were at different locations than reported. This reduced the defect data obtained, and has limited interpretation system development. However the result reinforces the limitations of CCTV inspections, which are reliant on subjective judgment which has to be maintained throughout the whole of the real-time operation. Approximately 500 m of operational concrete sewer was inspected with the sonar scanner. The segment was selected because its flow level could be controlled to ease system deployment and allow inspections with each scanner. With the laser scanner, inspections
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Figure 6 Structure of interpretation software 14
inspection report
were run at 100 mm/ sec, or 6 m/min, as this gives radius readings approximately every 5 mm, both axially and circumferentially. With the sonar scanner, inspections were run at 50 mm/sec, or 3 m/min. Due to the slower scanner speed, this gives radius readings every 25 mm axially. Lower speed would reduce this spacing, but was not operationally acceptable. Figure 2 shows laser and sonar maps of a section of the laboratory pipe, comprising a VC section and a concrete section. In the maps, the pipe surface has been unwrapped for planar display. On the computer screen, colour coding is employed to delineate pipe radius, as measured from the scanner axis, but for this publication this has been translated as various shades of grey, light grey indicating low radius. Black represents areas for which there is no radius result. With the laser scanner, missing radius results are due to the mount obscuring the pipe wall, to locally weak reflections, and to contamination of the optics. For the sonar scanner, the missing values are due to weak returns. The overall similarity between the laser and sonar maps is readily seen, with the major features of the dummy branches and the pipe joints and cracks evident on both. However the laser map shows much finer detail. This is related to scanner performance. To assess the size of the pipe features detectable with the sonar scanner, a matrix of small concrete cylinders was fixed to the pipe. They had diameters of 20-30 mm and lengths from 5 to 30 mm. All were detected, though they are unclear in this printed map. The laser map in Figure 3 is from a VC pipe in generally good condition. The uniformity of the map indicates good data when the vehicle ride is smooth. The large black stripe at 90 deg is water in the bottom of the pipe. The vertical lines near the left of the map indicate pipe joints. The dark section at the top of the pipe indicates greater radius in this area. As this effect is consistent across a number of pipe sections, it appears that the scanner is a little below the pipe centre. The dark patch at the top of the pipe and near the right of the map is a crack, through which roots dangle and have collected deposits. In the black areas, the dangling roots obscure the laser spot from the scanner camera. A few lighter spots in this mass indicate that they penetrate approximately 100 mm. These cracks appear quite different from the simulated cracks in the laboratory pipe. The map contains 400,000 radius values and fine detail, lost in the printed figure, can be accessed by mouse on the computer screen. Figure 4 is a laser map of a brick sewer in poor condition. The black zones above 900 are missing bricks. The disturbed pattern of the bricks is clear, and the light region below the cross hair in the top right of the figure shows bricks displaced towards the pipe centre. The WATER MARCH/APRIL 1996
smaller picture is the cross section at the cross hair. It clearly shows displacement of the bricks, and allows quantitative measurements. This has been valuable for asset managers assessing repair options for this sewer. The two narrow black stripes are due to contamination on the scanner optics, which usually clears during a run.
Interpretation System The interpretation system uses Artificial Intelligence (AI) techniques to automatically identify, classify and rate pipe defects. The software is designed to process the radius data (up to 100,000 readings per meter) to produce condition assessment reports. The software also implements a Management Information System (MIS) which allows further analy. sis of the results and access to the program controls via a graphical user interface (GUI) , Figure 5. The task performed by the interpretation system is complex because the pipe defects overlap and have complex surface geometry, and some radius readings are missing. Therefore, a new approach for automatic recognition of surface defects using actively sensed data needed to be developed. The automatic defect recognition is performed in five overlayed stages involving image preprocessing and segmentation, neural network classification, knowledge based interpretation and report generation. The software is structured as a hierarchy of modules, Figure 6. The image preprocessing involves correction, gridding, and removal of missing values from the raw data. Correction reduces the effect of in-pipe vehicle motion (pitch, yaw, etc.) by transforming raw data to a pre-defined global geometry model. Gridding interpolates radius values onto a uniform circumferential and axial grid. The preprocessing is dependent on the scanner type, and pipe size. It compensates for these effects, so that downstream modules are generic. Image segmentation clusters surface data into potential defect regions with characteristic geometric features . Classification of the regions is performed by a feed-forward neural network classifier which has been trained off-line by the back-propagation method using selected training data sets. A rule-based system interprets, rates and reports the classified regions as pipe defects in the format defined in the Australian Conduct Evaluation Manual (based on the British Sewer Rehabilitation Standard). The condition assessment report is generated automatically, and is integrated into the MIS which is the graphical interface by which the asset manager may study the data further. The interpretation system does the first-pass condition assessment currently performed by asset managers. Software quality assurance and object oriented WATER MARCH/APR IL 1996
approaches have been used in the design and implementation of the software in order to fully capture the most critical requirements for automatic asset management of sewers.
Performance of the Interpretation System The interpretation system was developed using simulated laser data in order to generate many pipe feature and defect examples. These were primarily needed for training of neural networks to classify the pipe defects. The simulated data was also used to test performance of other modules under ideal conditions. The classification accuracy of the interpretation system was greater than 970/o on simulated pipe intersections, holes and voids, corrosion, deformation, fat deposits, joint displacement, cracks, and tree roots. The interpretation system was tested using measured data from the laboratory pipe and from 4 km of operating sewer. For concrete and VC sewers, generally accurate classification was achieved. Some misclassification of complex defects occurred. This is attributed to simulated data being used to develop the system and to measured radii having higher variance than the simulated data. Large amounts of data from sewers is needed for neural network training to realise the potential performance of the interpretation system. Sewer defects which were correctly classified and rated were: gas attack, surface erosion, encrustation, tree roots, and grease. Pipe features such as pipe connections and pipe joints were also detected. The classification performance is rather poor for brick pipes. This is attributed to lower quality simulated data for brick pipes and their greater deviation from the global pipe geometry model. Generally unsensed areas specially close to water level and those affected by seepage were misclassified. In spite of these difficulties, the assessment of expert asset managers is that on concrete and VC pipes the system currently exceeds the performance of good CCTV operators. Further testing is needed on the laser field data in order to benchmark the performance of the software against CCTV-based assessments. Sonar data has coarser axial resolution and this significantly degrades the performance of the interpretation system. Furthermore, only minimal modifications to the preprocessor were undertaken to process sonar data. Consequently, only gross defects and features were detected in the lab pipe (eg. large fat deposits, branches). Finer defects could be assessed with slower inspection speeds and further development of the interpretation system.
Conclusion Current sewer condition information available to asset managers is subjective and unreliable. This has handicapped
financial justification of rehabilitation works, except for gross defects. In the current economic climate, water authorities are seeking maximum efficiency, and firm data is needed to justify their maintenance programs. Once the vehicle is launched into the sewer, PIRAT works almost independently of the operators. It can provide the quality of data asset managers need for confident assessment of sewer condition. The MIS report enables the manager to focus on significant areas. Pipe geometry can be accurately measured and with additional data from other technologies (eg. radar) , structural analysis of critical sections of pipeline can be confidently carried out. Not only is the inspection data more reliable and objective, but accurate comparison of condition over time is now possible. This will assist asset managers to more reliably predict system deterioration. It will be possible to predict when the condition becomes critical. This will result in more efficient allocation of scarce resources. Examination of the geometry data through the MIS is also valuable for the asset manager when assessing repair options. While it is often obvious that a sewer requires repair, the appropriate repair method is not always obvious. For instance, the feasibility of slip-lining a damaged section is . dependent on the dimensions of the section. If these are not known, slip-lining may not succeed and considerable funds could be wasted. The current experimental system has demonstrated the potential of the PIRAT approach to sewer inspection. The current system has demonstrated its superiority in 600 mm concrete and VC sewers and has provided valuable guidance for repair of a brick sewer. Further development is needed for different size pipes, to improve motion correction, and for brick sewers. The information already gathered has been valuable to Melbourne Water.
Authors Gary Campbell is a Civil Engineer who has been involved in asset management in Melbourne Water since 1984. As a senior engineer with extensive experience in sewer inspection techniques, he was seconded to the position of Project Manager of the PIRAT project. Dr Kevin Rogers is a Mechanical Engineer with 20 years' experience in CSJRO in the development of automation and instrumentation systems. He led the development of the iT?5trument system at the CSJRO Division ofManufacturing Technology. DrJacek Gibert is a Computer Scientist, who first worked for a software engineering company. He has spent the past 5 years in the CSIRO Division ofBuilding Construction and Engineering working on computer vision and artificial intelligence on numerous projects, including the PIRAT reporting system. 15
PIPES
SOUTH AUSTRALIA'S PIPELINES EA (Bob) Swinton This article was written by the Editor, from copious notes supplied by a band of retired E&WSD engineers, led by Bob Clisby. The ironic but useful comments in italics are mainly from jack Nitschke. Engineering details have been well-reported by Beaney et al, 7971, and Martin, 7979.
Sixty Six Years of Engineering Development Distinctive features of the South Australian landscape are the above-ground pipelines snaking up hill and down valley across this generally arid state. When they were originally proposed ovei 50 years ago, there were some protests about their visual intrusion, but the view of the majority was that they were acceptable, and in fact, it was not long before South Australians took some, perhaps perverse, pride in their presence. (A similar affection exists in Western Australia towards their Goldfields pipeline.) A brief history of their design and construction is well worth publishing at this stage, when, after 66 years of engineering development, the Engineering & Water Supply Department has just been restructured into the South Australian Water Corporation, plus other relevant government departments, and a commercial component. (Snippets of history regarding other feats of the engineers of yesteryear in construction of dams, tunnels and River Murray works are just as fascinating, and may well feature in a future issue of
Water) .
Why Above-ground'? Previous water supplies to the coastal fringe of South Australia were obtained by damming the somewhat limited rivers which flowed down from the Mount Lofty and Southern Flinders Ranges. However in drought years these failed even the best-designed storages. The answer had to be the Murray River. South Australia therefore commenced in 1887 the complex and long-drawn out negotiations with the upstream states, New South Wales and Victoria. In 1902, together with the newly born Commonwealth Government, this resulted in the first Interstate Commission agreement to report on 'the conservation and distribution of the waters of the Murray and its tributaries for the purposes of irrigation, navigation and water supply'. (There was 16
considerable incentive to do something by that time. After two or three years of drought, the river was stagnant, and in South Australia it was so saline and hard that the steam locomotives on the railway broke down.) South Australia had to fight New South Wales and Victoria for years to ensure a reasonable supply of water at the State boundary, a fight which persists even to the present day against the irrigation demands of the other states, now that water quality, as well as quantity, has entered the equation. Once politics had slowly assured a source of raw water, the next stage was the engineering, and the financing, necessary to lift the water over the Ranges, down to its customers on the coastal plain. The first long pipeline in South Australia, however, was the Tod River Trunk Main, on the Eyre Peninsula, which was commenced in 1922. Initially this served Port Lincoln, but then was extended north and north west to Ceduna, comprising a total of 244 miles of 33 inch down to 15 inch steel mains, laid underground. It was the longest gravity steel main in the world. However, within 10 years corrosion problems were being experienced both internally and externally. Following a study of the Goldfields Water Main in Western Australia, the main was lifted in lengths of 90 feet, reconditioned, cement lined and relaid above ground. This was done between 1936-1941 and lasted until the 1960s, when a new main was laid. The impetus for a second main pipeline, however, was not domestic demand for the city, or even rural irrigation, but Premier Playford's campaign to industrialise the state. This was enhanced by the war clouds gathering on the horizon. In 1938 he persuaded BHP not only to mine the iron ore of Iron Knob, at the north west of Spencer Gulf, and to ship it to their blast furnaces in Newcastle, but also to back load coal/coke from Newcastle to their port on Spencer Gulf, and create a new industrial town, Whyalla, where blast furnaces and a rolling mill would process a proportion of the ore into South Australian steel. Iron ore, coal, land and sea transport were assured, the missing link was fresh water, since Whyalla was surrounded by desert, groundwater was very limited, and the Tod pipeline already under stress. So the Morgan-Whyalla Pipeline was conceived, if not actually born, and
the E&WSD was on the way to becoming a world leader in cement lined steel pipeline construction, which continued for over 35 years until :the 70s.
The Morgan-Whyalla Pipeline The decision was made, at the outbreak of World War II, to build a 223 mile pipeline: 'to improve supply to the northern district.. as far as Port Augusta.... and to furnish a supply to BHP to operate steel and other plants'. (This developed even further into ship building for the war effort.) The rated capacity was to be 5800 gal/min (440 Us) , of which 5500 MIJa was destined for Whyalla, and 4000 MIJa to areas en route. There was little debate that the main would be laid above ground. The Tod River Main had been laid in the ground and had given trouble with external corrosion, with inside corrosion negligible except where ground stresses had cracked the cement lining. (Some advantage in cost could also be claimed at the time, due to the 'primitive' quality of excavation machinery, but this would not apply nowadays). The biggest difficulty was that the preferred route crossed through property boundaries and it was necessary to build underground sections to enable access to adjacent farm lands. However, through a program of consultation with landholders, local government and State Highways, very little dispute arose. The route and its adjacent maintenance track had to be carefully planned in the field, not only to reduce stress on the pipes and supports, but also to limit optical illusions and present a pleasing appearance. Local high spots could be cut away, but long or deep cuttings were avoided to reduce erosion problems. The rising main, 56 miles long, was 30 inch diameter, and four pumping stations of equal duty performed the 1560 foot lift. The gravity mains varied from 26 to 21 inch diameter. The pipes were to be continuously welded, with anchor and thrust blocks to resist the stresses. The 30 foot long pipes were delivered from factories in Adelaide and Port Pirie, with spun cement linings of half-inch thickness, and externally coated by a stove-dried inorganic zinc silicate. This coating stood the test of the years in the above-ground mains, but it could not cope with soil contact, and all underground sections had to be replaced with WATER MARCH/APRIL 1996
pipes coated with fibre-glass reinforced coal tar enamel. The pipe ends were left uncoated and they were butt-welded after delivery in sets of three on a rotating rig. At the joints the internal cement lining was trowelled on, usually by a (small) man lying on a trolley, and the external weld coated by a cold-curing zinc silicate. The final 'linking' was performed in strings of about two miles between anchor blocks, using welded collars to close the gaps at approximately 750 foot spacing. Sometimes in the middle of the night, as soon as the pipes reached about 20°C, within the range of water temperatures to be expected. Before wel.ding the pipes were temporarily supported on wooden blocks. At each collar joint, a wel.der stood by with his oxy torch . while temperatures were read until they all came down to the required range, when the order woul.d be shouted from a speeding Land Rover... "Start wel.ding". jack remembers an experienced wel.der slugging the pipe with a sledge hammer, whereupon it jumped horizontally on its blocks several inches as the temperature stress was relieved. Since this was not usually done, one wonders what were the actual stresses in the rest of the pipe strings. Towards the end of construction, in 1943, a new style of pipe became available, with slip-in joints, and a short length was constructed with single pipes laid directly to profile, and arc welded. The flexibility of the joint, though limited, eliminated the need to field-cut pipe-ends at even the least change of alignment, and the day of the oxy-welder disappeared. Eventually, ball and socket ends were manufactured to allow far greater flexibility. The pipe came into full operation in 1944, but demand steadily increased, and ten years later the rising main pumps were replaced, and four booster pumps installed in the gravity section. Finally, a l 00 mile long extension was run across the desert to service the W oomera rocket test station. However, by 1961, it was decided that a second main was required. Morgan-Whyalla No. 2 was constructed, following the same route, except that a short cut was taken by laying a submarine pipeline seven miles across the Gulf. This was 30 inch diameter concrete-lined mild steel protected by both coal tar enamel and cathodic protection, together with a coating of concrete to provide mechanical protection and bouyancy control. However, one failure was the use of a 30 mile length of 36 inch prestressed concrete which had to be replaced after only eight years due to severe corrosion.
in the gravity section, and feeds into the Adelaide reticulation system. It was designed for 37000 gal/min (2800 Vs) but was later upgraded to 56000 gal/min (4200 Vs) . It was the first to use packed expansion joints, supported on rollers to relieve stresses. In 1967-8 it supplied 75% of the city's demand. A second main was commenced in 1968, running 30 miles from Murray Bridge to discharge into headwaters of the Onkaparinga river, and thence into the system. It was 66 inch diameter, with an initial capacity of 78000 gal/min {6000 Vs) and has since been uprated. In 1970, a 36 inch main was laid from Swan Reach to Stockwell, to supply the country to the north of the city, and 300 miles of above-ground branches and interconnections now link the whole system. The South-East of the state, which had relied on groundwater, was boosted by an 80 mile main from Tailem Bend to Keith.
Hydraulic Design The C-values used in the HazenWilliams formula were based on field friction tests on various types of pipe, and ranged from 115 for 8 inch pipes to 140 for 48 inch cement-lined pipes. These applied only when the water was chlorinated. In the 7970s it was noticed that the capacity ofthe Morgan-Whyalla pipeline had fallen. A special check on the friction coefficient showed this was the cause. Manholes were cut into the main, and significant growths were found (sponges and bryozoa). Slug doses of 70 ppm chlorine cured this, but resulted in corrosion of the cement lining, so it was up to the chemists to work out suitable pretreatment. Surge control was a major factor in the routing of the mains, the location of the pumping stations and storages. Hydro-pneumatic surge vessels and pressure relief valves were also used. A surge problem did occur in the Mannum pipeline just before No.2 Pump Station. A change of grade at a high point resulted in a break in the water column at maximum flow if the pump was shut down when the Electricity Trust had to shed load. It sounded like two express trains colliding when the water column recombined. A surge tower solved that problem. At one point a malfunctioning hydraulic valve caused the concrete top of a surge tower to be blown off On the Onkararinga pipeline, until corrected, surges occurred in some of the suction lines, resulting in ten extremely loud bangs and violently shaking pipes every time the pumps were shut down.
Metropolitan Pipelines
Structural Design
These were built by E& WSD throughout the period 1950-1980. The Mannum-Adelaide pipeline has 33 miles above ground. It is 58 inch and 55 inch diameter in the rising main, and 46 inch
Above ground continuously welded rigid mains have been built up to 48 inch diameter, and expansion joint mains from 46 inch to 84 inch diameter. The influence of topography is such that no clear
WATER MARCH/APRIL 1996
differentiation in economics could be made. Up to 1980, all pipes were built of AS Al49 mild steel, with no advantage seen for higher yield steels. The minimum plate thickness was 1/140 of shell diameter. Stress analysis took into account hoop, bending, temperature, Poisson effect, weight and saddle and roller friction stresses. Supports, anchors and thrust blocks were designed by a combination of theory and practice, and charts were prepared to assist field engineers to cope with changes of alignment. The minimum thickness ofpipe was determined so that it would not collapse under vacuum occasioned either by a burst or human error in operation. (In Ballarat Victoria, in the early days, a section ofpipe, several miles long, collapsed into a flat ribbon of useless steel.) Automatic air-valves were not favoured although used by other authorities.
Pump Station Troubles Morgan No. 7 Pump Station consists of a screen and pump set in a chamber below river level, part excavated from the limestone cliff Originally two separate chambers were proposed, but the Chief at the time did not approve and sketched on the plan a single circle. Detailed design proceeded, but the Chief was not amused when he saw the final drawings, which formed an ellipse. His rough drawing was thereupon pro,duced, and he had to swallow hard. People still ask why an ellipse was built. The pumps in the Mannum station were designed with a type of expansion joint to relieve the pump casings of stresses. However, the contractor failed to realise that this imposed the hydraulic reaction onto the pump itself When turned on, the pump recoiled, dowels sheared, bolts bent and water squirted everywhere. This was ten days before Christmas after a prolonged water rationing period in the city, so it was 24 hours a day, seven days a week to fix it. At Mannum No. 7 the primary pumps are submerged and driven through long vertical shafts with intermediate bearings. The alignments have had to be readjusted constantly over a period of several years, the total differential movement being several inches. This was due to long-term shrinkage of the concrete structure.
Construction Morale was always high, people were proud to work for The Waterworks. There was a competition between gangs as to pipe lengths laid, or concrete poured. This developed a spirit of camaraderie, adventure and cheerful fun at all levels of the organisation. There was an important job to be done and they did it.
References . Beaney H L, Dawkins N W, Turner D M C (1971). Inst Eng Aust. Ann Conf. Papers. Martin D E (1979). Construction Branch Newsletter, 25th anniversary edition 17
PIPES
ASSESSING MELBOURNE'S CBD SEWER SYSTEM S C Carne*, A M Norrish Abstract A fully calibrated sewer network model is an important and useful asset for sewerage system authorities. This paper outlines the methodology used in a project that involved the construction, calibration and subsequent use of a sewer model of the Melbourne Main Sewer catchment, which serves the Melbourne Central Business District (CBD) area and some surrounding suburbs. The model is now owned and operated by City West Water Ltd, the retail business supplying water and sewerage services to the Melbourne city area and western suburbs.
Key Words Hydraulic model, sewerage system, capacity analysis.
Introduction Aims and Objectives. Recent concern over the structural integrity and hydraulic performance of sewers in the Melbourne Main Sewer Catchment lead to the appointment of Gutteridge Haskins & Davey Pty Ltd by the Maribyrnong Region of Melbourne Water (now City West Water) to carry out the hydraulic investigation of this catchment. The project was managed by the Sewer Assets Team of Melbourne Water. The investigation had the following three major objectives: • flow and rainfall monitoring throughout the study area to obtain raw data on system performance • .development of a computer hydraulic model to assess system performance under dry and wet weather flow conditions • development of feasible and practical improvement strategies aimed at eliminating deficiencies and optimising system performance.
Catchment Description The Melbourne Main Sewer caters for approximately 86 000 equivalent population. The catchment covers some 925 ha and as shown on Figure 1 includes parts of Carlton, East Melbourne, Port Melbourne, South Melbourne and the entire central business district (CBD) of Melbourne. The catchment includes sewers made of brick, concrete, vitrified clay, uPVC and cast-iron pipes in 18
sizes ranging from 50 mm to 1 500 mm diameter. Some of the older sewers still in service in the catchment were constructed in the 1890s. The catchment also includes two pump stations and an emergency relief structure (ERS) which, in times of extreme wet weather, permits overflows out of the system. An aspect of the catchment which made this project quite distinct from previous modelling projects carried out by GHD was the extent of the difference in population and hence dry weather flow patterns between weekdays and weekends. The Melbourne CBD and sporting and concert events at the MCG and National Tennis Centre were the reasons for these differences. Of further particular interest in this catchment was the historical engineering significance of some of the sewerage system infrastructure in the catchment. In addition to the extent of brick arch sewers, the catchment contains a 100 year old cast-iron siphon crossing of the Yarra River.
Methodology The sewer catchment hydraulic investigation followed a procedure adopted by Melbourne Water which comprised the following main work phases: • collection and analysis of flow and rainfall monitoring data • validation of system data to be used as input for the model development process • calibration of the model under wet and dry weather flow conditions • use of the model to assess system performance under defined storm events and the evaluation of various augmentation options. Flow and Rainfall Monitoring. The monitoring plan for the study was based on a preliminary plan prepared by Melbourne Water. Modifications to the plan, as a result of the desktop and site assessments, were made by GHD and were due to: • clarification of the sewer connectivity • preference for, where possible, directly measuring sub-catchment discharges • inspection of the proposed sites to assess access and traffic. The hydraulic conditions at a gauge site govern the quality of the collected data.' Therefore, a number of options
were considered by GHD for each gauging site and the best site selected within the constraints of the monitoring plan. A total of 27 depth-velocity flow gauges were installed by a subcontractor to GHD at selected sites within the catchment (as shown in Figure 1) for a period of approximately six weeks. The monitoring conditions at the final sites varied widely due to: • accumulations of silt and gravel • some sewer drops • manhole form • bends at manholes. Rainfall data for the study was collected from a telemetered site. Four temporary rain gauges were installed to assess rainfall variability over the catchment. During the period for which rainfall and flow data were concurrently available, five storm events occurred. These events were useful . for ranking the Infiltration/Inflow characteristics of the catchments. However, longer term gaugings are required to assess the overall performance of the system. Gaugings taken over a longer term enable differences in antecedent moisture condition, groundwater table evaluation and rainfall characteristics to be taken into account. A system to manage flow and rainfall data quality was established for the project which addressed specific areas which impact on quality of data and safety of monitoring sub-contractors. These areas included: • occupational health and safety • instrument installation, maintenance • operation and calibration • data management and processing • verification procedures. Model Development. Validation of all sewer system data for model building was undertaken by Melbourne Water. The base model data-files were provided to GHD for completion of the model development. The development of the model included definition of the following: • ancillary structures • sub-catchment areas defined in the range of 2 to 10 hectares ' • dry weather flow data based on flow monitor output and catchment land use definition • pipe roughness • GHD, 380 Lonsdale Street, Melbourne, 3000
WATER MARCH/APRIL 1996
• equivalent unmodelled storage in the system • manhole headloss parameters. Storage of sewage flows under surcharge conditions may be due to either storage in the main line or storage in smaller sewers which were not actually modelled. It is desirable to account for this storage as its absence, depending on system characteristics, could lead to an overestimation of the extent of surcharging within the system under wet weather conditions. On and off line storage values were determined using software developed in-house and adjusted where necessary and then input to the model data file. Hydraulic roughness for pipes was determined based on the following : • recent CCTV inspection tapes of the Melbourne Main and other main branch sewers • photographic inspection records • Melbourne Water Guidelines. Silt levels at gauge sites varied throughout the monitoring period and therefore were not included in the model. Minor headlosses in manholes under surcharged flow were accounted for in the model by a headloss co-efficient index assigned to each pipe as necessary. It was subsequently found however that calibration simulations were not sensitive to the defined headloss index. The sewer system in each sub-catchment was investigated to identify cross-connections between sewers in adjacent sub-catchments. Three types of cross-connections were identified, reviewed and modelled: • connection of sewers at the tips of the network • connection between sewers within the network • flow splitting.
t
WATER MARCH/APRIL 1996
Model Calibration Dry Weather Conditions. The
model was calibrated to the typical observed dry weather flow {DWF} characteristics for each gauge and sub-catchment. It is noted that due to the constraints imposed by the sewer network and the budget for the number of flow gauges, characteristics for sub-catchments in the lower reaches of the catchment were determined from subtracted flow hydrographs. Characteristics determined in this way have a wide confidence range when the sub-catchment flow is less than the contribution from upstream sub-catchments. In these circumstances several sub-catchments were aggregated to determine typical dry weather flow characteristics. The steps of the dry weather flow analysis were: • determine average dry weather flow {ADWF} at each flow gauge • determine ADWF expressed as Uequivalent person/ day for residential and commercial sources of wastewater • characterise the diurnal pattern of wastewater flow • quantify baseflow including ground water infiltration. The results were used to calibrate the model for dry weather flow. Dry weather flow data were selected from days without rainfall. Hydrographs representative of dry weather flow were averaged to produce a typical composite dry weather flow hydrograph. The analysis indicated different typical DWF hydrographs for weekdays and weekends. This was also found to vary during school and public holidays as expected. For the purposes of dry weather flow modelling, the DWF at each monitor site
was distributed over a number of pipes within the catchment to represent the source of flows . Several sub-catchments were aggregated for DWF modelling after a conformity check which checked the sensitivity of flows determined by subtraction. The calibration of the dry weather model was assessed for flow and depth with regard to the following: • shape of hydrograph • time and magnitude of the peak • daily volume. A satisfactory dry weather flow calibration was achieved. Wet Weather Conditions. The model was calibrated for wet weather flow (WWF) and verified against recorded rainfall events for use as a tool to evaluate the performance of the existing system for specific storm events and to develop an upgrading plan to adequately cater for the 5 year ARI design standard. The method adopted for calibration of the model for wet weather flow for each storm event is summarised below: • re-calibration of the model against observed flow at each flow gauge prior to and after the storm to represent variations in antecedent soil moisture conditions • select rainfall-run-off model parameters for each sub-catchment, apply to the model, review calibration and repeat to achieve a suitable fit for flows • review calibration for depth and repeat preceding step until a suitable calibration of flow and depth has been achieved at each flow gauge. Calibration took into consideration the following hydrograph characteristics: • peak flow • hydrograph shape including recession limb of rainfall in the sewers • flow volume • peak depth. The parameters used to calibrate the wet weather model were catchment area; percentage fast; response area; slow response coefficient; routing constant; and depression storage constant. In the light of the above the calibration parameters that were adopted for some sections of both models were a compromise between flow and depth criteria with no spillage predicted. An example of output from the calibration process showing a comparison of observed and predicted hydrographs at one of the flow gauge sites is shown in Figure 2. Rainfall-dependent infiltration/ inflow (RDl/1) is the rainfall that enters the sewer system as either inflow or infiltration. It is obtained by subtracting the typical dry weather flow, based on a composite weekly pattern, from the wet weather flow. Analysis of the volumes of RDl/1 for monitored storm events enables: • quantification of the annual amount of infiltration/inflow {I/I) and • identification of the predominant type of 1/1. 19
A key performance indicator derived from the RDl/1 analysis is the return ratio "R". This represents the proportion ofthe rainfall that ends up in the collection system as RDl/1. This assessment was not a requirement of the brief but was included for completeness. These values have not been standardised for dry and wet soil conditions which is desirable to provide a suitable means of identifying likely 1/1 sources and selection of appropriate source detection techniques. Longer term gauging over a wider range of storm and catchment conditions could yield greater volume ratios. The sub-catchments were given a preliminary ranking to indicate the severity of infiltration/inflow (1/1). Preliminary rankings were determined for two parameters: • indicative fast response area • predicted RDl/1 volume. Peak flows (fast response area) tend to influence the capacity of the collection system within the sub-catchments. Assessment of System Performance. In addition to the model containing current dry weather flows, a second model was built to incorporate future dry weather flows. This incorporated inputs from proposed major redevelopments in the catchment and projected population growth. For each dry weather flow model, the capacity utilisation of all sewers in the model was determined. Plans of the network were produced with modelled pipes colour-coded to display the level of utilisation of each pipe. Hydraulic analyses under wet weather conditions were undertaken to assess the performance of the existing system for specific scenarios. These scenarios were : • monitored storm event • storm which just causes spillage • design storms of 1, 2 and 5 year average recurrence interval (ARI). The result of this analysis is the determination of: • current hydraulic capacity • the surcharge capacity of the existing system • hydraulic performance for each scenario. It is noted that a 5 year ARI storm may not produce the peak 5 year flow at the outlet of the catchment. The frequency of occurrence of the peak flow is also dependent on the soil wetness and the magnitude of the dry weather flow at the time of the storm. Upgrading works within the catchment will also improve the hydraulic conveyance and increase peak flows . The surcharge capacity of the system was determined by multiple model simulations to identify the storm event which just causes spillage. Events of various durations were generated to determine hydraulic response of the catchment and hence the critical 20
ed by GHD has enabled City West Water Ltd to: . • interpret performance of the system, including the level of utilisation within the system • identify sewers causing system restrictions or bottlenecks • assess the hydraulic impact of future development within the catchment • predict the frequency and intensity of storms that would result in the first spillage of sewage from the system • model the performance of possible upgrading works to the. system so that the most practical, cost-effective solution to any system deficiencies could be identified. These outcomes are typical of the output of hydraulic analysis of sewerage systems using computer models. It is an approach currently being used by City West Water Ltd and many other water authorities in Australia.
duration of the storm. The characteristics of each storm event were based on the 1987 edition of Australian Rainfall and Run-off The simulations were carried out based on ultimate dry weather flow. Upgrading Options. Upgrading options were developed to eliminate spillage for the 5 year event and provide a surcharge capacity between 10 and 20% greater than the standard. An optimum comprehensive rehabilitation strategy for the wastewater collection system requires consideration of structural condition, operations and maintenance, as well as hydraulic performance. In accordance with the brief this investigation considered the hydraulic performance only. The options considered provided an indication of the extent of works required to achieve the specified level of service. Detailed investigation of the options did not form part of this study. Upgrading of the sewer network to improve the hydraulic condition to the desired grade can be achieved through: • diversion of flows to an adjoining system • capacity upgrading • infiltration/inflow reduction strategies. Six options were developed using the above strategies to achieve the desired hydraulic condition for the Melbourne system. Feasibility cost estimates were prepared fo r each of the six options. It is understood that City West Water Ltd are now separately evaluating the structural condition of the collection system and developing rehabilitation strategies and contingency plans as appropriate.
Acknowledgements The authors acknowledge the support and assistance received from City West Water Ltd and Melbourne Water in the preparation of this paper. The input and assistance during the project from these companies and also colleagues within GHD is particularly acknowledged.
Authors Steve Carne is a Senior Civil Engineer with Gutteridge Haskins & Davey (GHD) Pty Ltd in Melbourne. He has 7 years experience in wastewater and water supply infrastructure projects. Tony Norrish is a Principal Civil Engineer with GHD. He has 15 years water and wastewater experience and is now the Manager, Wastewater Systems, far GHD in Western Australia. Both Steve and Tony have expertise in hydraulic evaluation, infiltration/inflow studies and rehabilitation of wastewater collection systems.
Conclusions The rigorous procedure for modelling of sewerage systems used by Melbourne Water was adopted by GHD to analyse performance of the Melbourne Main Sewer Catchment under dry and wet weather flow conditions. The hydraulic investigation conduct-
"'
!I
~
80
Rainfall Hyetograph
C
~
150
I• 0. 080
H1 5
01 I...
(Obse rved)
H15
Pl
{Predicted)
.§. 0. 060 ~
e>
~
0. 040
0"'
12. 0fl
. 24. 00
36. 00
18. 01
Til'le (Hours )
Figure 2 Wet weather calibration plot
WATER MARCH/APRIL 1996
WATER
REMOVAL OF ALGAL TOXINS USING MEMBRANE TECHNOLOGY M Muntisov *, P Trimboli* Abstract
rate of 67%, with a concentrate rate of 76%. Facilities for alum and ferric chloride dosing were also provided. The equipment was set up on the River Murray at Murray Bridge in South Australia. The pilot plant feed pump drew water from the river for testing. To test for algal toxin and taste and odou compound removal, microfiltered raw water was spiked with the toxins Microcystin-LR, Nodularin and the algal taste and odour compounds Geosmin and 2-Methylisoborneol (MIB}.
The results from pilot testing of membrane technology for the removal of algal toxins from River Murray water are presented. The results show that nanofiltration is capable of removing two common algal toxins.
Introduction The development of treatment methods for the removal of algal toxins from drinking water has been a priority in the Australian water industry ever since the well-publicised toxic algal bloom occurred in the Darling River in 1991. Most research has focussed on the use of activated carbons or ozone for treatment. The known molecular structure of the algal toxins Microcystin-LR and Nodularin indicate that nanofiltration membrane technology is theoretically capable of removing these toxins from water. A pilot test program was undertaken to determine the effectiveness of nanofiltration membrane technology in removing algal toxins.
Pilot Testing The pilot test equipment consisted of a MEMCOR* microfiltration trial unit, together with a spiral-wound nanofiltration membrane unit. The microfiltration system was operated at a nominal flux rate of 120 Um2.hr and a transmembrane pressure of 60 kPa. The nanofiltration unit was operated at an overall recovery
Results A summary of the treatment results achieved is presented in Table 1. The results indicate the following: • the raw water has high turbidity, colour and iron levels and has a very high organic content as measured by TOC and THM formation potential (THMFP} • rnicrofiltration without coagulant addition is effective in removing turbidity, iron and manganese but is poor in removing colour, TOC and THMFP • microfiltration with coagulant provides improved colour, TOC and THMFP removal • nanofiltration following microfiltration (without coagulation} achieves excellent colour removal and, more significantly, a very dramatic reduction in TOC and THMFP levels compared to coagulation. The nanofiltration treatment performance in this trial indicates its potential for effective no-chemical treatment. It also has the potential to produce a bio-
Table 1 Treatment of River Murray water Parameter Raw Microfiltered
Turbidity (NTU} Aluminium (mg/ L) Iron (mg/ L} Manganese (mg/ L} Colour (HU) pH (TOC} (mg/ L) (THMFP} (mg/ L)
Nanofiltered (no Coagulant)
No Coagulant
With alum (28 mg/L)
3.3 0.04
0.09 0.08 0.09 0.01
65
53
0.06 0.03 0.02 0.01 7
0.06 0.03 0.01 0.0 1 3
6.8 9.6 718
7 8.2 588
6.5
7.1 0.5
61
5.0
4.2 164
36
Table 2 Removal of algal toxins, tastes and odours Parameter Mycrocystin-LR (mg/ L) Nodularin (mg/ L) Geosmin (ng/ L)
MIB (ng/L) • detection limit 0.5 rng/ L
WATER MARCH/APRIL 1996
Spiked Microfiltered
Nanofiltered
8.4 8.0 52 38
below detection• below detection• 22 21
logically stable water which could minimise or even eliminate the need for residual disinfection (Muntisov, 1995).
Algal Toxin Removal Microfiltered River Murray water was spiked with two algal toxins and two algal taste and odour compounds prior to treatment by nanofiltration. The results are shown in Table 2. The key conclusions which can be drawn from these results include: • nanofiltration is capable of removing the algal toxins Microcystin-LR and Nodularin to below detection levels. The detection level for Microcystin-LR is below the range of values being considered as a guideline value Gones et al, 1993} • nanofiltration provided around 50% removal of the common algal taste and odour compounds geosmin and MIB. The removal rate could be improved by more optimal operating ' settings on the nanofiltration system. Even so, it is unlikely that nanofiltration will be satisfactory in the removal of geosmin and MIB given that the taste and odour thresholds of these compounds is in the 5 to 10 ng/L range. Therefore, supplementary treatment in addition to nanofiltration would be required for effective algal taste and odour control. The use of powdered activated carbon is an option.
Conclusion The main conclusion from the microfiltration/nanofiltration pilot testing program is that two common algal toxins can be removed from River Murray water by nanofiltration membrane technology.
Acknowledgements The authors wish to acknowledge the work of Brett Alexander of Memtec Ltd in carrying out the site trial work and the Australian Water Quality Centre in Adelaide which conducted the analyses.
References Jones G, Burch M, Falconer I, Craig, K (1993). Cyanobacterial Toxicity, pp 17-32. Technical Advisory Group Report. Murray Darling Basin Commission. Algal Management Strategy. MDBCi Canberra. Muntisov M (1995). Future Technology for Drinking Water Treatment, AWW A Queensland Regional Conference, Gold Coast, October 1995. • Gutteridge Haskins & Davey, 380 Lonsdale Street, Melbourne, 3000 * Memtec Ltd, Bag 1, Windsor 2756
21
WATER Contaminated Aquatic Sediments This IAWQ Specialist Group symposium, 'Effects of Scale and Management of Sediment and Water Quality', was held in Colorado, USA in July 1995. It was an extension of an earlier symposium on 'Variability in Stream Erosion and Sediment Transport', held in Canberra in December 1994. It focused on the scale effects on process variability and the manner by which physical and chemical characteristics of sediment and water vary with scale. The symposium aimed to: • identify scalar effects on fluxes of water · and contaminant loads • evaluate scalar effects ofhydrologic and geomorphic processes relative to environmental concerns • consider the application of models and other technologies to resolve questions of scale . • recognise, especially through statistical analyses, data requirements for developing relations between scale and contaminant fluxes • propose management and monitoring schemes by which knowledge of scale problems can be applied and extended. Overall, 36 oral and poster papers were presented during the course of this four-day symposium; two of the presentations were by Australian participants. The text of these oral and poster presentations is available in IAHS Publication No. 226, Effects of scale on interpretation and management of sediment and water quality. The papers presented, although related to large ranges of climate, topography, hydrologic conditions and land use practices, all conform to a recognition that the evaluation of hydrological data must be conducted relative to the areas and periods within which those data were collected. - AroArakel
and stability in lake strata' (Andy Cohen) • 'General review of the applications of stable isotopes in paleolimnology' (Michael Talbot) 'Lacustrine sequence stratigraphy' (Finn Surlyk) • 'Sedimentary processes in rift lakes' CTean:Jacques Tiercelin) • 'Paleoclimate from ice cores - regional and/ or global significance' (Claus Hammer) • 'Saline alkaline lakes of the Kenya Rift: modem and ancient' (Robin Renaut) • 'Sedimentology and hydro-geochemistry of modem lakes - an Australian perspective' (Aro Arakel). The week-long technical program included some 125 oral and poster presentations dealing with different aspects of limnogeology; a significant number of presentations related to new approaches and methodologies for applied research. The proceedings volume of the Congress is scheduled for publication as a special volume of Paleogeography, Paleoclimatology, Paleoecology in 1996. -Aro Aralcel
Bringing Water to the People In Tigray, northern Ethiopia, projects funded by Water Aid aim to bring water supplies to communities without access to sufficient safe water. Water Aid is an initiative of organisations such as Sydney Water, Hunter Water, ACTEW and Brisbane City Council, in conjunction with Community Aid Abroad (CAA).
Limnogeological Congress This congress was sponsored by International Geological Correlation Program (IGCP), Project 324, entitled 'Global Paleoenvironmental Archieves in Lacustrine Systems'. It also represented the last major official activity of the IGCP 324 for fostering closer links particularly with South American, Asian, African and Eastern European scientists involved with research on ancient lacustrine deposits. It was attended by over 220 people from some 25 countries; two of the participants were from Australia. Eight people with diverse research backgrounds presented keynote speeches covering the following topics: • 'Frontiers in limnology: paleogeography from ancient lacustrine basins?' (Kerry Kelts) 'Interpreting biotic turnover
22
For girls like this, clean water in the village means less sickness, more to eat and time to go to school Tigray has suffered from successive years of drought. This, combined with the long-term effects of a brutal civil war, has brought famine to the area and caused an unprecedented water crisis. In Tigray, women are traditionally responsible for water collection and can spend as long as eight hours a day in search of water. During the dry season, families are forced to split up. The aged, woi;nen and children stay at home while the younger men and livestock migrate in
search of water and grazing. CAA began supporting a rural domestic water supply program in 1984. CAA and its partner organisation, the Relief Society of Tigray (REST), have advanced a system of hand-dug wells using simple, low technology construction methods. The program aims to provide water in remote areas where most people live. Since December 1992, 87 new wells have been built and 19 old wells rehabilitated. Wells are constructed by REST, whose local knowledge ensures the viability of hand dug wells. The local community is involved at all stages of the project. The community forms a Water and Sanitation Committee of five members, three of whom, ideally, are women. This has a direct bearing on its sustainability due to the importance of water to the women of Tigray. The committee helps to plan the well. It also organises construction, maintains the hand pump (tools and spare parts are given to the committee) promotes health education, the sanitary aspects of water use and recruits water system workers. Well construction is supervised by trained local technicians, two of whom are women. People from the local community supply mucli of the labour and construction rock. Excavation is carried out using hand tools. If hard rock is encountered, explosives are used to break it up. A hand pump is installed on a cast concrete cover over the well. The benefits for the communities involved are enormous. The time saved from water collection allows women to participate in community development and family activities, while not having to carry water over long distances is dramatically improving their health. In July 1995 an award of appreciation was made to CAA by the Tigray Development Association and the Prime Minister of Ethiopia, Meles Zenawi, on behalf of the people of the country. These efforts to 'bring water to the people' were reported widely in the Ethiopian media and Australian assistance was applauded. In 1996 the project aims to construct 100 new wells and rehabilitate ten. Each well costs an average of $4000 and supplies at least 200 villagers permanently with water at less than $20 a head! A brochure requesting your support for Water Aid is included with this issue. In addition, the Relief Society of Tigray and the CAA field offices in Ethiopia and the Sudan require computer equipment. If you are able to donate a new computer, printer, software, modem or photocopier, or would like more information about Water Aid, please call Lisa Walker at Community Aid Abroad on telephone (02) 264 1399. - Lisa Walker WATER MARCH/APRIL 1996
WATER IAWQ SPECIALIST GROUP, PARTICULATE SEPARATION These reports come from members of this group. Further reports on progress in particulate separation are welcomed by David Dixon, Secretary of the IA WQ Specialist Group, CSIRO Division of Chemicals and Polymers, Private Bag 10, Rosebank MDC, Clayton, Victoria 3169
Separation of MicroOrgan~sms from Water This IA WQ workshop, held in Amsterdam, was attended by over 100 delegates from at least 19 countries. The microorganisms of interest were the protozoans, cyanobacteria and coliforms and viruses in general. The material presented fitted three main categories. Firstly, there was the discussion of hands-on experience of separation technologies. This was lead by a joint effort be tween Montgomery Watson and Lyonnaise des Eaux-Dumez, reeorting results oflow pressure membrane (MF and UF) separation of the protozoans; Cryptosporidium parvuum, Giardia muris, the bacteria; E. coli and P. aeruginosa and the MS2 bacteriophage. Their bench-scale work indicates that both MF and UF provide an absolute barrier to protozoa and selected bacteria. However, the limit of UF membranes appears to be 100,000 Daltons for complete rejection of the bacteriophage. Other papers followed this theme with coagulation of Cryptosporidium, kaolin filtration of algae, DAF removal of cyanobacteria and a novel wire-like contact-media for direct algal removal. A group of four papers investigated the morphological properties of microorganisms and their potential effect on removal efficiency. John Gregory and Hedley Pugh from University College London presented work on the adhesion of Cryptosporidium to surfaces. They have designed a micropipette technique to directly measure the strength (as low as 10·11 N) of attachment of Cryptosporidium to model surfaces. A collaborative Dutch effort from the International Institute for Infrastructural, Hydraulic and Environmental Engineering and Delft University of Technology reported the improved removal of algae by direct filtration using permanganate pretreatment. They explained their results in terms of a combination of inactivation of motile organisms and the in-situ production of a natural, algal derived coagulant aid. A collaborative South African effort between Rand Water and Potchefstroom University, reported the advantages and disadvantages of preoxidation with chlorine and chlorine dioxide for algal removal by coagulation and filtration . WATER MARCH/APRIL 1996
Their work confirmed the results of the previous paper: morphological changes in the alga in response to the oxidants were critical in determining removal efficiency. There were two papers on applying instrumentation to investigating microorganisms in drinking water. Firstly, there was a group from France reporting on the use of particle counting for disinfection control. In my opinion, the most interesting paper was delivered by George Dubelaar, of Dubelaar Research Instrument Engineering. He reported the results of modifying the traditional flow cytometry technique to investigate particle agglomerates rather than discrete particles. The material presented would certainly be the topic of debate within flow cytometry circles but surely represents what many would see as a natural extension of the current technology. If this was not enough to get the scientist on the edge of the seat he then tabled a project called 'Cytobuoy' which was aimed at producing a remotely controlled buoy which incorporated a flow cytometer to monitor selected microorganisms.
- Kelvin O'Halloran
Coagulation Trials with Ferric Chloride in Brisbane
occurred. Trials are continuing using polyelectrolytes as a filter aid and coagulant aid. - Mark Pascoe
Effect of Ozone in Pre-treatment At the North Pine Dam treatment plant, a 400 kL/day pilot plant has been established to investigate the use of ozone in pre-treatment. Objectives for the project include: • whether ozone improves floe formation: this could lead to converting the plant to direct filtration mode • will ozone reduce algal related taste problems? • will it inactivate cyanobacterial toxins? The plant was closed down for the first time this year because of a toxic bloom of Cylindrospermopsis raciborski. Other issues include the effect of ozone on dissolved organic compounds and on the disinfection demand. The use of ozone in Australian water treatment plants is not common, but the need to reduce off-flavours and improve disinfection efficacy together with the increased number of toxic blue-green algae blooms has resulted in much interest in this research project. - Hans van Leeuwen
Surface Chemistry and
Rheology Research In conjunction with ICI Watercare, Brisbane City Council has been trialing The Advanced Mineral Products ferric chloride as an alternative coagulant Research Centre is working on the underto aluminium sulphate, at its major water standing of the properties of particulate treatment plants. fluids. The fluids of interest consist of The source water for two of the water mineral or other particles, typically in treatment plants is the Brisbr..ne River, water. A theme of the research is to which has a moderately high alkalinity understand the inter-relationship between and usually a low turbidity (< 5 NTU) the surface chemistry of the particles and which is sometimes difficult to treat. the rheology of concentrated suspensions However, stormwater run-off can of the same particles. The results of the increase the turbidity dramatically. work have implications for such chemical Therefore, it was necessary to evaluate processes as coagulation and flocculation the effectiveness and costs of ferric chloand such processes as pumping, thickenride under various plant operating condiing, clarification and filtration. tions and with different raw water characThe group is interested, at a fundateristics. mental level, in the inter-particle forces Ferric chloride was found to be an between oxide particles in the presence of effective coagulant for treating Brisbane dispersants, flocculants and coagulants. River water at low turbidities and also at The projects typically use an atomic force turbidities of several hundred NTU. The microscope to determine the inter-particle treated water met council's standards as force and the mechanism of action of the follows : Turbidity < 0.5 NTU; True molecule on the surface. The rheology of Colour< 5 Pt/Co units; Iron < 50 ppb; · concentrated dispersions of the same surManganese < 50 ppb; Aluminium faces in the presence of the additives is < 200 ppb. used as an indicator of the effect such At a third site, the raw water is direct- additives have on suspension properties. ly drawn from a dam on the North Pine Fundamental and applied work is also River. At this plant a higher dose rate was under way to develop an µnderstanding required to meet the treated water stanof filtration and thickening. The main aim dards. It was necessary to coagulate at a of the work is to establish laboratory pH of 8.0 using caustic soda in conjuncbased, non-empirical tests that allow pretion with the ferric chloride to ensure that diction of filtration or thickening performance at full scale. Initial work in this manganese levels remained low. At very high filtration rates (17 m/h), break- area has proved to be both generic and successful. - Peter Scales through of colloidal iron hydroxide 23
WASTEWATER
IRON CHLORIDES FOR FILAMENTOUS BULKING: LABORATORY INVESTIGATIONS I Sosa-Sanchez Abstract Laboratory trials kve been conducted on a glucose-promoted, activated sludge bulking unit to study the effects of ferric and ferrous chloride solutions on filamentous bulking. Findings so far indicate a .positive effect on settleability.
Introduction Filamentous sludge bulking is a common operational problem found in activated sludge processes. Solid separation problems in wastewater treatment plants are several and so are the proposed solutions. Iron salt addition, particularly in the form of ferric and ferrous chloride, is considered in this study, following observations made while using iron salts for phosphorus removal.
Experimental Methods Laboratory trials were conducted using a laboratory scale, continuously fed activated sludge unit comprising a 71 aeration zone and a 31 settling zone. The unit was seeded with activated sludge obtained from a mildly bulking sewage treatment aeration basin. A final concentration of around 2000 mg/1 MLSS was obtained. The temperature was maintained at 25 +/-1 °C by using an aquarium heater. Oxygen was manually adjusted daily using a flowrneter to maintain a DO concentration between 2.5 to 3.0 mg/I throughout the experimental period. Mean Cell Residence time {MCRT) was 10 d. Three MCRT were used per test. The unit was run for 162 days. To stimulate bulking conditions, the effect of glucose was tested at three different feed concentrations {0.5 g/L, 0.75 g/L and 1.0 g/L). No significant changes in SVI were observed during the addition of glucose at 0.5 g/L and 0.75 g/L. However, good bulking conditions were achieved by the addition of glucose 1.0 g/L to the artificial feed. The Sludge Volume Index {SVI} test was used for this investigation, being the simplest test used to measure filamentous bulking. Good settling sludges characteristically have SVl's below 150 with best settling observed below 100. Sludges with SVI's greater than 150 are usually considered to be bulking. Filamentous microorganism growth 24
was subjectively determined under the microscope only, and no attempt was made to identify species during this trial. Jar Tests. Jar tests were conducted to observe the effects of different concentrations of iron salts on 0.51 samples of MLSS, as collected without pH adjustments {pH 6.5-7.0). It was observed that ferric chloride 20 mg/L as Fe• 3 and ferrous chloride at 15 mg/ L as Fe• 2 {per Litre of MLSS sample} had similar effects on settleability {sludge blanket height} of test samples. Chemicals. !Cl's 'Nutrifloc 42' {Ferric Chloride 42%} and 'Nutrifloc 12' {Ferrous Chloride 12%} commercial grades were used to prepare stock chemical solutions used for these experiments. To stimulate bulking conditions {after day 50}, 1.0 g/L glucose was added to a synthetic feed comprising {per Litre} : 260 mg Nutrient Broth {Difeo), 30 mg Urea, 7 mg NaCl, 4 mg CaCl2-2H 2O, and 2 mg MgSO 4-7H2O .
Results and Discussion The effect of ICI's 'Nutrifloc 42' and 'Nutrifloc 12' preparations on the filamentous bulking is shown in Figure 1. The results obtained indicate that when bulking conditions were present, the addition of ferric chloride to the synthetic feed at a concentration of 20 mg/ L, from day 68, marked the beginning of a decrease in SVI levels from 357 to 140 during the following 3 MCRT. When ferric chloride addition to the unit was stopped at day 98, bulking con-
ditions increased, as the SVI measurements indicate. The .addition of ferrous chloride to the feed at a concentration of 15 mg/ I as Fe• 2 at day 124 was found to be not as effective as the ferric chloride addition, but still good enough to lower the SVI level from 328 to 184. The results obtained indicate that the higher dose of ferric chloride was, under the test conditions, more efficient at inducing improved settleability than ferrous chloride. However, in these preliminary trials improvement of the filamentous bulking to levels below 150 was maintained only for short periods of time.
Conclusion !Cl's experience in field observations has often shown dramatic improvement in Nocardia foam problems when iron salts have been used in activated sludge plants for phosphorpus removal. This investigation has found that ferric and ferrous chloride solutions can have a positive effect on Sludge Volume Index when added to a bulking activated sludge at laboratory scale, thus showing some promise for use in normal activated sludge plants. Further research at pilot and full scale plants would be necessary to establish the capability of these products on such a complex problem.
Author Ismael Sosa-Sanchez is a Development Technologist with ICI Watercare, PO Box 4371, Melbourne 3007.
"' ~ - -- -- - -- - - -- - - - - - - - - - -- ----, 300
"'
20
30
'°
50
60
70
l!IO
. ,.
90
,oo
110
120
130
l otO
150
160
170
FeCG adOed - ct.y 68 to98 F.ct2 ackltd - dlly 124 I0153
Figure 1 Fe Salts Vs Bullcing (SVI changes with time)
WATER MARCH/APRIL 1996
WASTEWATER Rouse Hill Effluent Reuse Ian Law, National Manager CMPS&F, gave an excellent presentation on the Rouse Hill (NSW) Dual Water Scheme to WA branch members last November. The scheme was built according to advanced ideology and 'world first' standards (e.g. effluent never to exceed values of 2 virus/ SO mL or 1 parasite/50mL). Such standards have never been applied anywhere else in the world, and these types of concentrations could not be measured when the project started. In addition, the reuse of effluent inside homes for toilet flushing had never been practised on a reasonable scale elsewhere. Thus the dual reticulation scheme, built at great cost, was a world first in many ways. The regulations and operating conditions were still being developed while the wastewater treatmeht plant (complete with nutrient removal and tertiary treatment) was being built. When the regulations were completed, it became necessary to add further treatment stages (including the need to chlorinate to 5 mg/ L free chlorine after 1 hour detention). When added to the 34 km of trunk and effluent reticulation laid and dual meters for each house, it all became extremely expensive. The planners did not get the timing right and the treatment plant was commissioned at 100/o load with predictions of 900/o loading by the end of 1997. However, it is still only operating at 100/o of design load. As insufficient effluent is being generated, the effluent system is currently being topped up (almost 100%) with potable scheme water. Some home owners have realised this and have placed hoses through windows into their homes, paying only 20c/kL for the 'effluent' versus the normal rate for potable water of about 60c/kL. Ian also expressed concern about the significant health and liability risk issues associated with recycling effluent. The Rouse Hill experiment has provided a costly lesson. It would have been cheaper to treat all effluent to drinking water quality and distribute via a normal potable water reticulation system. Planners should think long and hard in future before contemplating another dual supply scheme.
Recent Developments in Nutrient Removal Over 50 NSW members attended a seminar last November on recent developments in nutrient removal in USA and Australia. Tom Wilson, Rust Environment & Infrastructure, USA, talked about the latWATER MARCH/APRIL 1996
FROM THE BOTTOM OF THE WELL
est technologies being used in the USA for nitrogen reduction. He spoke of three levels: (1) simple nitrification (2) partial denitrification (5-15 mg/ L TN in the effluent) (3) full nitrification/ denitrification (<5 mg/ L TN in the effluent). In the USA there are relatively few plants which achieve level 3, but these are mainly required for the larger STW (>40 MUd). Typically, the TKN achieved is approximately 0.5 to 2 mg/ L, with a carbon source being used to achieve full denitrification. Examples include Tampa (360 MUd, and includes tertiary sand filtration), Blue Plains (1360 MUd) and Munich (410 MUd). Dr Wilson discussed the availability of options for step feeding in activated sludge systems and the advantages, including decrease in reactor volume. He then spoke about advanced biological nutrient removal (ABNR}, which involves level 3 nitrogen removal process, incorporating step feed arrangement. There is no recycle of MLSS and consequently there is significantly less tankage required (for a 75 MUd reactor, some 530/o of the size} compar~d to other BNR systems. There is also a reported 200/o reduction in energy and chemical costs. Methanol is used typically rather than sewage carbon sources to enhance denitrification. The step feed arrangement can improve the performance significantly. Other work being undertaken involves the combined process of MLE with a fixed film (rope) based system. Ian Law, CMPS&F Environmental, spoke about recent developments in biological P removal. Issues related to biological nutrient removal include shorter design SRT's, release of phosphorus under anaerobic conditions and prefermentation for generation of short chain volatile fatty acids for reliable performance. Today shorter design SRT's are favoured, which provide many advantages including reactor volume decrease. It is also noted that wasting of mixed liquor is generally preferred above WAS because of the improved control and to cater for diurnal flows. Ian spoke of the need for consideration for diurnal flows. Ammonia breakthrough may occur if the plant does not have in-built safety factors in the design to deal with peaks. P and N will also vary with the flow. Biowin is a new program which incorporates flow fluctuations. CMPS&F has used this to simulate flows and effluent N and P for Bolivar (South Australia) and other STW with accurate results.
The bottom ofFreddo's well is littered with books that Freddo's family thinks he ought to read. They were given to him at the Annual Present Giving Frenzy (APGF) of recent memory. The well is relatively quiet now as visiting offspring and accompanying grand tadpoles have departed. Freddo does not think this departure was hastened by his having a Michael Leunig cartoon stuck to the fridge door: the one about children who will not leave home. Fredda believes that the wise ones who are looking after us encourage the APGF to train our young ones to be avid consumers. To put quantity ahead of quality. To live in the present. To believe that: 'He with the most toys wins' . There also seems to be a deeper objective to this conditioning. We are teaching our young ones that not even their parents can be trusted. We tell them about Santa Claus and then let them discover from some older child that their parents have deceived them. But deep down we go on hankering after Santa Claus. Someone who will satisfy our most extravagant wants at no cost to us. As a nation we have handled our water resources as if they came out of Santa's sack. In our endeavour to mould the country to our vision of what it ought to be rather than what it is, we are placing unbearable stress on our river systems. We have allocated too much water to human needs and not enough to environmental needs. To repair that situation will require great skill and sensitivity. It will also require enormous political courage. Australia is so fragile, so vulnerable and so unlike the lands from which our forefathers came. Our climate, driven by the gigantic forces of the Southern Oscillation, is more erratic than Europe's and does not follow a comfortable, predictable, seasonal pattern. We march to the erratic beat of a different, harsher drum of drought and flooding rain. The big dry and the big wet. In spite of this, we farm on an annual basis as if the seasons were predictable. And all the time the thin layer of mother soil gets thinner and the salt rises. It will be difficult to estimate how much water, at any given time, will be enough to satisfy the environmental needs of our rivers. It will be difficult to satisfy all points of view. We have choices to make. While we may be aiming for sustainability, what or who will we sustain and what or who will we not? We cannot return the country to what it was like before European settlement, but neither can we go on treating it the way we are . The question of the management of our water resources is not just about quality, it is about what lives and what dies.
Freddo 25
WASTEWATER
RE-USE OF SEWAGE EFFLUENT Report by Peter Martin through an environment improvement The 'Re-use of Sewage Effiuent' semi- sures will also be needed to assist the viaprogram, and action in an emergency bility of effiuent irrigation schemes. nar was held in Adelaide on 26 Ted Maynard from the SA Health outlined in a contingency plan. September 1995, organised by AWWA, Mr Palmer emphasised that the EPA the SA EPA and the Department of Commission described effiuent as a 'compreferred to work with industry towards Environment and Natural Resources, plex soup of biological and chemical better practices and solutions than spend with the support of the Local Govern- agents', and said that the variable nature its limited resources catching offenders. ment Association of SA, the Australian of this and other factors involved means To this end it maintained a network of we face 'considerable uncertainty' in Water Panel of the Institution of Enginclient coordinators. Nevertheless its poweers, the SA Water Resources Council, dealing with the associated risk to public ers in dealing with polluters were clear. ;md the Hydrological Society of SA. health. It was important to realise that risk License fees will be used as a lever to Proceedings are available from the SA = hazard X exposure. improve performance, as well as a signifBranch of AWWA. Level of exposure to hazard needed Over 90 people attended the seminar. special attention, since it was possible that icant source of revenue. The annual budget for the EPA is currently $8 The SA Minister responsible million, and the long-term aim for water resources, the Hon. of the SA Government is for David Wotton, outlined his the authority to be self fundgovernment's commitment to water reuse, saying that 'the ing. Louise Rose from the SA reuse of resources is a logical Water Resources Council, and path'. He announced that the SA Government would soon Richard Clark from the SA Department of Environment be releasing a new water plan and Natural Resources, for the State, including some explained the place of effiuent major policy initiatives, and reuse in the' State's water planthat for the first time these would include the consideraning. In recent consultations the council found several tion of wastewater and areas repeatedly emphasised: Michael Hickinbotham, the Hon. David Wotton and Rob Tnomas at stormwater as a resource. • the need for management The Minister also pointed the seminar to the good progress being decisions to reflect land and made with the Virginia pipeline concept we may already be approaching critical water plans, including the need to use the (which now has State Cabinet approval in exposure levels for certain chemicals: catchment as the operating land unit principle), the Government's determina- cadmium and lead were examples. • the need to know the total water budget tion to eliminate wastewater discharge to before allocating water However, detailed information on the • the key role of local management structhe River Murray, new initiatives by SA chemical composition of wastewater and tures country towns in wastewater reuse, relevant safety criteria were hard to • management to encourage efficient and opportunities in India, and the impor- obtain. Dr Maynard was also concerned effective water use. tance of AWWA input into the impend- that while measures using faecal coliform To this end the council has estabing review of the SA Water Act. as indicators of bacteria were important, In opening the seminar Rob Thomas, they told us little about viruses, protozoa lished an Effluent Reuse Policy Executive Director of the SA EPA, paral- or helminths. Committee, which presented its first draft leled the Minister's thinking on wasteDr Maynard was supportive of wastereport to the council in July. Early discussions by the committee have included: water being a resource rather than a nui- water reuse, but advocated reduction wherever possible in the disposal of haz- • the advantages of moving towards sance. He suggested that new initiatives in ardous waste through the wastewater planned reuse user pays, demand management and • a new generation of integrated reuse environmental care have contributed to stream. For the purposes of discussion he this reassessment. Whilst encouraging included several draft tables on standards schemes wastewater reuse (with measures such as a for wastewater reuse in his paper, includ- • the impact of local reuse on assett replacement schemes 50% discount on fees for licences), the ing a classification of reclaimed water, • constraints to reuse. EPA was also required to consider the water quality standards for recreation and Draft recommendations are expected domestic use, and for municipal irrigalong-term sustainability of land disposal to include that research be supported and schemes. He suggested that the salinity of tion. extended into integrated resource manLicence requirements of the SA EPA Bolivar effiuent reused at Virginia, for agement. example, might be a cause for concern in for the use or disposal of wastewater were Peter Dillon from 'the CSIRO the future . presented by the Authority's Senior Division of Water Resources, and Advisor Wastewater, Neil Palmer. Not Nevertheless, excellent proposals for Adelaide Manager of the Centre for only do potentially polluting activities imaginative reuse are emerging, such as Groundwater Studies, presented a paper new ideas for the use of wastewater from require a monitoring program, but land on current research work on developing the Glenelg plant. Although technical disposal of wastewater is also subject to guidelines for the quality of water to be solutions to reuse problems are being an agreed irrigation management plan. injected into aquifers for storage. The steadily developed, novel economic meaBetter performance may be required
26
W ATER MARCH/APRIL 1996
main aims of the work are to find ways of: • preventing clogging of recharge wells • protecting the quality of groundwater • ensuring that recovered water meets target standards. In addition the work seeks to improve on current guidelines for wastewater irrigation being used elsewhere in Australia, since they have not been effective in protecting groundwater quality. Dr Dillon gave examples of recent and current projects involving the irrigation of pig effluent for potatoes and forestry, and raised the issue of the long-term effect on the aquifer of high salt levels in wastewater. On the subject of biological pollution he felt more needed to be known about attenuation rates of pathogens in specific aquifers. Treatment Senior Wastewater · Engineer with the SA Water Corporation, Rick Desmier, described how an irrigation scheme using wastewater is different from a conventional irrigation system. Types of reuse irrigation schemes include irrigation on demand, partial reuse, year-round dispersal and total reuse. Water quality parameters that cause most concern are salinity, sodium adsorption ratio, boron, nitrogen and suspended solids. The mismatch between the relatively uniform output of a wastewater plant and the highly variable demand of an irrigated crop means that some form of storage is required. Some adjustment to crop type {e.g. a proportion of drought-tolerant plants) may be necessary to ensure that extreme demands are not beyond the system's capacity to deliver. Nutrient balance, site selection, storage lagoon design, monitoring and contractual arrangements are also key elements requiring careful attention. Roger Stokes, Principal of Roger Stokes and Associates, reviewed the history and substantial recent progress of the proposal to pipe wastewater from Bolivar to the 'Virginia Vegetable Triangle' on the northern Adelaide Plains. The attraction of the scheme is that it has the potential to end the ocean discharge from Bolivar, which has caused extensive environmental damage over the last 30 years and threatens fisheries, and at the same time solve a water shortage problem for horticulturalists at nearby Virginia where groundwater is now seriously overdrawn. Roger Stokes and Associates, together with Gutteridge Haskins and Davey Pty Ltd, were commissioned early in 1995 by the Virginia Pipeline Committee to prepare a reuse scheme and business plan by which (a) 800/o and (b) 1000/o of Bolivar effluent could be redirected from the Gulf St Vincent to Virginia. The plan included an agreement that the water delivered would be only for Class B uses (i.e. unrestricted use for vegetable growing including crops eaten raw) . The plan covers treatment plant location, treatment plant
WATER MARCH/APRIL 1996
type, the distribution system (176 km of pipe from 150mm to 1200 mm, with 750 offtakes), and a range of demand and supply considerations. Economic analyses showed that in order to achieve 1000/o effluent use in an average year, substantial winter irrigation or storage would be required. Storage at Bolivar, and aquifer storage and recovery, were easily the most attractive of several options. The latter would involve 50 bores around the perimeter of the area, using aquifers that are already slightly saline. Capital costs of building the 800/o reuse option were estimated at $47.7 million. An overview of water reuse schemes in SA was presented by Lester Sickerdick, A/Supervising Engineer Wastewater Treatment at the SA Water Corporation. Whilst SA Water owns and operates all p ants in fully sewered areas {four in Adelaide and 19 in country towns), 100 septic tank effluent drainage schemes (STEDS) are operated by local councils. Reuse was an early feature of Adelaide's first sewage treatment scheme at Islington, constructed in 1881, and again at Glenelg at the tum of the century. Current plants in the Adelaide area incorporating reuse schemes include Glenelg (resumed since 1958), Christies Beach {since 1972), and Bolivar (currently about 70/o is used by irrigators). In the country, schemes exist at Pt Augusta West (since 1979), Mannum (since 1991), Murray Bridge (primarily an evaporation scheme), and Hahndorf. Construction is underway also at Gumeracha and Myponga, and possibilities exist at Victor Harbour. Of the 100 STED schemes operating in rural SA, 20 involve some 'beneficial' reuse. Mr Sickerdick also presented figures on current reclaimed water charges (0.55 -2.16 c/k.L), and an estimate for reclaimed water under dual reticulation at Victor Harbour at 87c/k.L to $1.75/k.L. Rebecca Giles, Senior Environment Engineer with Acer W argon Chapman (SA) Pty Ltd, continued the theme of using STED effluent with an account of a scheme her company recently installed at Tanunda in the Barossa Valley. Although local vignerons were taking most of the wastewater already through an unofficial arrangement, flows during autumn could still be discharged to the North Para River. The expiry of this discharge licence in late 1993 led to the Tanunda District Council engaging Acer to redesign and formalise the disposal system. Water quality criteria used for the development of the scheme were based on practice in NSW, guidelines from the NHMRC, the old AWRC, ANZECC, and discussions with the SA Health Commission. Features of the scheme include: • extensive community involvement,
including the formation of the Association of Tanunda STED lrrigators, and a STED Board of Management • transferable water rights on a week-by-week basis • water rights to carry an obligation to dispose of available effluent on land. The success of this scheme will attract much attention in the Baross Valley, where conventional water resources appear to be approaching limits at a time of expanding demand for its irrigated products. Michael Hickinbotham, a Director of the Hickinbotham Group, outlined some of the environmental problems of the Murray-Darling Basin, and gave an account of a study tour of countries with scarce water resources. Two notable examples were the planned reuse of wastewater for potable purposes in Windhoek, Namibia, and a dual distribution system by the Irvine Ranch Water District in California. Closer to home, the Hickinbotham Group recently installed a new bio-reactor system {know as the Hickinbotham Aquacycle) in Renmark. This was in response to a problem involving STED discharges to the River Murray at times of high river flow, typically every three years. In seeking to eliminate this nutrient pollution, the town examined and ruled out expensive conventional disposal options. Its choice of a relatively small and low energy bio-reactor will enable extensive reuse of wastewater for irrigation within the town. Ted Allender from Land Energy Pty Ltd described the Koorlong Wastewater Scheme near Mildura in Victoria, currently the largest municipal effluent irrigation project in SE Australia. After six years of investigations and planning, Lower Murray Water commissioned the 106 ha native hardwood irrigation scheme in December 1993. Initially taking 9MIJday of effluent from Mildura, the scheme aims to be using 24.8MIJday by 2040. Located 25 km south of Mildura, the site receives piped untreated effluent. After primary sedimentation, a digester and sludge lagoons, the effluent is polished ready for the drip irrigation system. This is arranged in 53 separate valved sections, each independently and remotely monitored, and managed through a computerised control system. Shallow and deep groundwater systems are also being monitored. Considerable attention has been given to the selection of tree types for the site, with the result that four species now dominate ,the planting: Casuarina glauca, and the three eucalypts camal.dulensis, occidentalis and grandis. The CSIRO Division of Forestry is involved at Koorlong in research on E. grandis, and the Division of Entomology has been engaged to help manage the potential problem of insect attack. 27
WASTEWATER
Nutrient Removal Seminar Interest in this subject is exemplified by recent seminars in both New South Wales and Victoria. EPA Regulatory Environment. Last December David Coleman, Operations Manager of the Eastern Treatment Plant, spoke at a meeting of the Victorian Branch's Wastewater Treatment Special Interest Group. David discussed the EPA regulatory environment in the Yarra Valley region. It requires sewage treatment plants serving an equivalent population of greater than 1500 to reduce effluent total phosphorus concentration to less than 2 mg/ L, and possibly to less than 1 mg/L by the year 2004. At Brushy Creek, a local treatment plant located in the north eastern suburbs of Melbourne, chemical removal was chosen because a guaranteed phosphorus removal was required. The process could be operated intermittently and implemented quickly with limited additions and modifications. The three types of metal ions that are typically used are iron salts, such as ferric chloride, ferric sulphate (Ferriclear), ferrous chloride (pickle liquor), aluminium salts, such as aluminium sulphate (alum), and calcium salts, such as calcium hydroxide (lime). Laboratory testing of ferric chloride, pickle liquor, alum and Ferriclear was used to predict the metal ion dose rate and the caustic soda dose rate. Typically the metal ion dose rate was greater than stoichiometric, but very close in the case of pickle liquor (when aerated). For a final phosphorus level of 2 mg/L, the final phosphorus concentration is very sensitive to metal salt dose in all cases. Pilot plant testing confirmed actual metal dose rates and caustic dose rates. Dosing metal salt and caustic soda into the same dosing point at either the raw sewage or mixed liquor made no significant difference to the required dose rate. Separating the metal salt dose point and the caustic soda dose point yielded a lower required dose rate. The optimum dosing point combination was metal salt dosed into the raw sewage, and caustic soda dosed into the mixed liquor. The optimum chemical was pickle liquor dosed at a rate of 25 mg iron per litre of raw sewage. This yielded an effluent phosphorus concentration of less than 1 mg/L. The addition of caustic soda at a ratio of 1:6 (caustic to metal salt) is required with ferric chloride. Alum will require addition at a ratio of 1:4. Pickle liquor 28
when aerated only requires addition of caustic at a ratio of 1:40. Effluent quality in terms of BOD, suspended solids and ammonia is not significantly affected by chemical dosing. However, clarity is adversely affected by dosing metal salt into the mixed liquor. Sludge production will increase by 100/o by mass and 10/o by volume with the use of ferric chloride. With pickle liquor the increase is 27% by mass and 2% by volume. Ferric chloride and pickle liquor both increase the settling rate of the sludge. The increase with pickle liquor, however, is only marginal. Pilot plant experience was used to design a full scale facility using pickle liquor. Pebble bed clarifiers reduced the required dose rate from 30 mg/L to 16.5 mg/ L. ACTEW Experience at the Lower Molonglo. The evening's second speaker was John Dymke, Manager of Water Quality and Supply Branch, ACTEW Corporation Ltd. He is also the Technical Manager of FERRAQ, the corporation's business enterprise. John's presentation focussed on ACTEW experience at the Lower Molonglo Water Quality Control Centre in the ACT and phosphorus reduction activity being undertaken by FERRAQin NSW and other areas. The benefits of a chemical phosphorus reduction plant are: • low capital costs and easily installed • low chemicals cost available from the steel industry • high level of predictable P performance • easy to operate and control • good short and long-term solution. It can be used to achieve low levels of dissolved and total phosphorus in wastewater effluents (<0.5 mg/ L), where total land disposal is not a viable or economic solution. The main concerns of a chemical phosphorus reduction plant are: • increase in effluent salinity as a result of metal salts addition • increase in effluent-heavy metals concentration • impact of chemical P reduction on sewage sludges • annual operating costs for chemical supply. John looked broadly at approaches being taken in NSW under the NSW Local Government Phosphorus Action Plan and the ACT scene. The ACT PCA currently has limit licences for treatment plant discharges of <0.3 mg/L Total P. The LMWQCC load limit is 24 kg/ day Total P for a flow of approximately 94 MVday. Pressures are
also applied on water mining projects to reduce nutrient loading on rivers. In NSW, the trend is moving towards a total P level 0.3 to 0.5 mg/ L. The NSW State objective is for off-stream reuse of effluent where economically feasible . However, chemical P removal is encouraged in a number of plants where full or partial irrigation/ reuse is not possible. The NSW Local Government Phosphorus Action Plan is a state-wide program based on the TCM approach through TCM committees and local government. The State provides up to 500/o funding for approved projects eg. AlburyCorowa program, Murrumbidgee Water Action Plan and the UMCCC Project on septic tanks discharge. The CSIRO Experience. Our final speaker was Bill Raper, Senior Principal Research Scientist with CSIRO Watertec. Work at CSIRO has demonstrated that biological nutrient removal processes can achieve very low levels of nitrogen and phosphorus in water discharged from sewage plants without the need for chemical addition or effluent filtration. The first generation of BNR plants in Australia have been built and commissioned for some time now, and are proving that the process can indeed by operated on the stronger Australian sewage. The performance in terms of effluent P levels is somewhat poorer than that obtained in the USA: about 2-3 mg/ L vs 1-2 mg/ L, but Australian influent Pis significantly higher. The second generation of plants being commissioned at present employ either prefermentation of influent sewage or add polishing amounts of metal salts. They are designed to achieve below 1 mg/ L P in the effluent. The conditions used in the prefermentation process, known as the APT process, are novel and have been patented by CSIRO. A full scale APT process plant is constructed at the West W odonga Treatment Plant where the present conventional full scale biological nutrient removal plant has been unable to achieve low effluent P levels. Discharge regulations are now being tightened to 1 mg/L and sometimes less. It will be interesting to see if the results obtained using prefermentation in fullscale plants in North J\merica and Canada, and by CSIRO in their pilot plant at Lower Plenty, can be obtained reliably in full-scale plants here. Early commissioning results from full-scale plants utilising prefermentation in Queensland and Victoria show promising results. WATER MARCH/APRIL 1996
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Effluent Plantation Wins Landcare Award The Wagga W agga Effluent Plantation Project has been awarded the 1995 BHP State Landcare Research Award for NSW. The award was presented by the Hon Kim Yeadon, Minister for Land and Water Conservation, at a ceremony aboard HMA V Bounty on Sydney Harbour last October. Randall Falkner of the Division of Forestry and Colin Earnshaw, Facilities Engineer with W agga W agga City Council, represented the project team at the ceremony. The W agga W agga Effluent Plantation Project is a CSIRO priority project. It involves a team of up to 17 staff from the Divisions of Forestry and Soils representing disciplines of soil science, hydrology, plant physiology, silviculture and modelling. Commenced in 1991, it is a six-year study of the potential productivity and limitations to the sustainability of this form of land management. It aims to produce national guidelines based on experimental data and models that will assist local government, rural industries, environmental regulators and planners in the environmentally sound design and management of effluent-irrigated plantations. Toward this end, a manual entitled
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WATER MARCH/ APRIL 1996
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BUSINESS
TRANSFORMING GOVERNMENT BUSINESS ENTERPRISES A Pender* This presentation was given to the Institute of Water Administration in Victoria, and is reported by the Editor.
to staff to win their commitment to the change.
Four Hard Issues to be Tackled
Introduction Throughout the nation Government Business Enterprises (GBEs}, ranging through electricity, gas, water, sewerage, roads, hospitals, prisons, and more, are being transformed into either fully privatised companies, or government-owned corporations operating under the same commercial principles as private enterprise. The process of this change can be, and often is, highly traumatic to the 'public servants' who have maintained these enterprises successfully, if not competitively, virtually throughout this century. This process of 'change' is not limited to GBEs, indeed it seems now to be a fact of life throughout the commercial sphere, with the impact of globalisation on what was once a business culture protected by the tariff wall. What can be learned from mutual experience to enhance the effectiveness of the process of change? The most important lesson is that top and middle management have to learn and apply the skills of implementing change, and learn to communicate the changed philosophy
• Change always takes time, and more time than expected • resistance is natural, to be expected and must be confronted • people fear the loss of control that follows change • mistakes are bound to be made, and must be acknowledged.
The Basics for Success • Commit more time, resources and costs • slow down, deal with the resistance, in order to go further • reduce ambiguity by responding to fears and giving some control • monitor continuously so you can backtrack when necessary.
The Stages of Commitment Winning the commitment of managers and employees is never a one-step process. Rather it is a long-term process which must be managed in order to avoid the various danger points that can result in an aborted conclusion. Figure 1 illustrates this process. The process is both
8
13ijjjjjjjjtjjffiiii!%¥
Internalisation
Insta ll ation
Commitment Threshold
liitititi@liittit Contact
Figure 1 The stages to commitment
30
Disposition Threshold
technical and psychological. It must be understood that the organisation's capacity to absorb any particular change is finite. If overloaded, it will go into dysfunction: Future Shock. This is accentuated if a number of projects are attempted simultaneously, but not properly integrated. Operating staff will soon discern the interface conflicts, and lose even more confidence in senior management.
Managers.. Or Leaders? There is a distinct difference between the deliverables of management and leadership. The former can be summed up as predictability, order and consistency. Leadership is crucial under conditions of change and is devoted to establishing a mission, which may require fundamental organisational changes. Kotter (1990} sums it up in the matrix in Figure 2. Leadership is not 'charisma', but the need for a humility to share ideals with all levels of staff, to establish 'believability' to win hearts and minds. Leadership is defining the vision, the mission, the values. It comprises creating a sense of urgency, developing strategies to achieve the critical success factors, building an effective team to support the necessary changes, by communication, and by empowering others to support the leader. To the extent that 'management' is focussed on delivering order and consistency, cultural change represents a real challenge to the tasks and skills that managers apply. The 'leadership' element is essential to any successful cultural change. It is at top management level that the leader must succeed in communicating positive perception before any change can be implemented at the work unit, and the individual level. This is even more vital in changing the culture of a GBE which has been based on competent engineering, where the managers have been selected as much for their engineering competence as their administrative talents. With change to commercialism they feel threatened, and if they are to be retained, the leader must rebuild their sense of value. This necessity *Coopers and Lybrand, Box 2650 Sydney 2001
WATER MARCH/APRIL 1996
Management
Leadership
• Planning and budgeting
• Establishing direction
• Organising and staffing
• Aligning people
• Controlling and problem solving
• Motivating and inspiring
• Dealing with/resolving internal complexity
• Responding to a rapidly changing external environment
~
~
Change Dramatic redirection ~ Fundamental change in strategy and culture
Predictability and order ~ Consistent short term results in line with expectations ~ Order and consistency
~
from Kotter 1990
Figure 2 Management/Leadership deliverables
goes right down the line. Burke and Litwin (1994} outline the variables that contribute to organisational and individual performance with the most powerful ones higher up the model. (Figure 3}. They also suggest the dysfunctions which can, and do, occur when organisations fail to recognise the many 'human' elements involved in effectively changing an organisation. Figure 4 represents a totally miserable set of circumstances, but all readers will recognise at least components of it from their own experience. The dominant blocks to this failure to achieve change deserve to be spelt out:
Mission and Stratef,'j: • no shared vision • separate Divisional and Functional strategies • weak link between external environment and internal action • inward focus on own operations • distrust of government agenda.
Management practices: External Environment Any outside condition that influences
the performance of the organisation
Leadenblp Exec utives providing overall direction and serving as behavioural role models Culture for employees -----1~.- - - - - - - - - - ~
I
Mission and Strategy
I
What top management declares to
~anas:ement Practlca
j
: Tht
way we do thlo11 round hen:". The collection or
be! What employees believe is the --,~.mrccr~-===-=-=-,==n=--c==-'r-ovcrl and covert ruin, valua and princlplu that central purpo5e of the organisation -wha managen do to use the human cnsurtt and 1uldt1 ors:aal~onal behaviour
Structure
Land
material resources to carry out the strategy
!
The arrangement of functions and people into specific areas and levels of respons ibility, decision making, authority etc to ensure effective performance ~-T-u_k_a-nd_S_kl_ll_R_eq_ul_re_m_e-nts-~
__J!
non members
Motivation
Individual Need• and Valuea
~ - - - - - - - - - - - ' r h e e av oura ten enc1es to move towards The required behaviour and skills goals, take needed action and persist until to accomplish assigned work and responsibilities
SySt emi
Work Unit Climate The standard policies and T e co ect ve current 1mpress1ons, ee mgs ......_mechanisms that facilitate work and expectations of members that affect their relationship with boss, eac h other and
satisfaction is attained OfpDBiU0Dil ibd uidlVki.Uil . Performance
I
The OUTCOME or RESULT as well as the Indicator of effort and achievement
The endurln& thou1hts and feelings employees apply to determine the worth and satisfaction of their work
(drawn from IM w«ko/W Warntr BurU and G Litwin)
Figure 3 Performance matrix
• competition for resources between functions • management processes not understood/ valued • all problems treated as unique • control-focussed - limited delegation • no involvement of employees in decision process • pressure to increase productivity.
Priority Problem/Opportunity Areas Flowing from the analysis above, the leader has to apply himself or herself in specific areas. The prime priority is to define mission and strategy, next to change the culture: "the way we do things around here". The next priorities are to attack management practices, systems, task and skill requirements, and motivation. Organisational structure can wait, it will evolve.
The Leader's Tasks External Envll'onment (.;llllll(lal lltclllltry 11ntc:•r~ •IMI 1overamc.1 npe,cutiMI
• Com111trd1liulioa
• C•rporatiuitio•
Leaaenbtp
MDSIOn and !Strategy S.parateDiriaioaal lllld FucriNal1tn1~ Weak lb1k btl'!fl'- ncenul "--'roa . . . 1 alMI laceraal aclion
.comperitio. ,RatnKtvri•1
MNtf'tiluht•mta Playilufe
1Ackoftnu1 - doa '1keep proi:nittt t-VUlbtlilf
Jowarcl (ocua n - • opcrariou
\;Whlre Tac:lri•kallJdrivffl arroe:uu RulaboulMI P.-.mlH11<1tllla1
Pro--'dtleduucaluc:elte.ce Aaliprinltmterp~ valun
Dia1nt11ofovtra-1-ac1a
Orpnlaation Structure Too-ro'l•kalioa l.yu• F'l&acriouil.UocalioaofrtHUre• M.uyi.lltrfac:efllactiou Coatiaaill1 rtd.c:lio• I.a rttOllrtft
-·
Management Practices
,vr r-,11,~.., ._, .. etti ...11 M111a1tmffll rroctMtl aol 1111dtnlood/valutd All problem, lftaled U HlqlM Cnrrol focuted - ll•lltd ddepdoll ~- l11volvc . . . 1 of ••i>kY-1• decblOII pro«M
SystelDI No co111pa•y-wld1 comm1111icalioa procnan Poorcolluntrol1y,111111 h•crioullr batecl perfo,-.ac:e -lllrffllffll alMI ,_..,cl wldto11lnleraalrtftt'flKt
Work Unit Climate ..-wor-. ... rce_,., Stroa1 Wffllifkatioa wltll wort Ila.ii •IMI '9yally te ii DiltnY1of_ .. ___,1t•cl ovttw-lH-41
Motivation
Tuk and Skill Reqnlrements l11ctlk•t tac:ukal ,Id.Ila W•k1...,a1 ....1~11killl p-QOWlecl11ot'MmteddlVff)'
Srro111fllac:lioulklyal1y O.lre 10 do lhc ril,bt llriia1 I.MIMalt•flodfw•rtll Fedd_. vallMIII by t•pliuit" n111o_,
lndlvldnal Needs and Valna Srroa1 Dted for tcdllnkal rec:opllio11 JobMC11rily Stroq '9yally lo llbtorical orsubalio•
1nu1v1uu111 ana urgantaanonal Performance · Loa1prGC.e1&1i_, H.ipce11 IAwcuio-urilfacdotl
figure 4 When performance failr
WATER MARCH/APRIL 1996
Nou•paradw J•1Ukadou
(dralWtfrom the w.orko/W Warner Burk.e and G Litwin)
Managing the behavioural risks of change is critical to achieving the transformation. Throughout this period, which can last for one to two years, a continued drive is essential; eg. every internal memo must contain a reference to the change, otherwise it can degenerate into a 'flavour of the month' under the pressure of current business. Above all, the plan must aim for some early wins to keep motivation on the boil. • Look into the past history of culture change in the organisation. If it is poor, this cynicism will carry into any new project. • Appoint 'Sponsors', ' Or Change Managers, key people at each level, who are committed to the change and have the power and authority to take positive action, to get the divisional managers to take specific actions. They can do this through 'Reference Groups', where control is passed to the manager to organise, 31
not 'what' but 'how' to change, recognising the technical expertise involved, followed by detailed discussions with the operational staff. • Run fairly frequent 'Visioning Workshops', analysing what managers have to do differently, for example, to change the order of the agenda for weekly meetings, eg. listing what you know, what you don't know, what you need to know. Review progress. • Check with the stakeholders: corporate, customers, employees, professional associations and unions. If there are negative perceptions, try out the "vision" on them. If it is not acceptable, modify it. • Focus for six months on the senior management team, sell them the benefits of the change. After three months, test them for positive perceptions, not just · placatory platitudes. • Recognise that all employees want to be doing 'something' and to be involved. Trust them. There are many examples to prove this.
Key Risks • The perception that the change process looks too hard, too complex, too time consuming • The denial of past historical successes, so that incumbent staff lose face and self-worth • Wavering of the commitment of the key sponsors over time • The skills of the sponsors being inadequate
• Overload, both of the organisation and individuals, as current reponsibilities clash with the demands of the change process • Cultural clash: the inertia is massive, so allow a longer time-frame • Ramming it through too fast: this may be forced upon you, but if you do not carry 'hearts and minds' you will be forced to use the whip for a very long time.
The Solution? • First recognise the size of the task. It will never be easy, in some GBEs the existing culture is more established than I in others • commit time and resources, in excess of 30%-400/o of senior management time • anticipate, and plan • be prepared to get discouraged • sustain and support one another.
An Example Steps toward commercialisation of a GBE. (1) Assess current situation (2) Develop vision, mission and values (3) Identify critical success factors (4) Define priorities/ programs for: - operational performance - culture change support (5) Establish sponsors for key programs that represent the major changes required: business planning, client rela-
tions, management processes, people issues, financial systems, skills development. (6) Establish employee involvement processes - program reference groups - monitoring of change process (employee survey) (7) Develop work plans for each program with defined roles for: - sponsor - reference group - technical expertise (8) Reinforce/communicate vision plans and programs (9) Report/celebrate results
References W Warner Burke and G H Litwin, {1992) "A Causal Model of Organisational Performance and Change", Journal of Management (18, 2) pp! 523-545 JP Kotter and] L Heskett, {1992) Corporate Culture and Performance, Free Press,
N.Y.
Author Anne Pender is a qualified industrial psychologist with over twenty years' experience in consulting. Since 1985 she has worked at Coopers & Lybrand Consultants where she is the partner working on transformation ofcommercial companies. eg NRMA, Civil & Civic, and government organisations such as Sydney Electricity and Sydney Water.
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BUSINESS
ANTIPODEAN TEAM TO UK WATER INDUSTRY Report by C Davis In November last year nine people from the Australian and New Zealand water industry travelled to the UK to learn about their capabilities in the field of industrial wastewater treatment. We were guests of the Department of Trade and Industry, British Water and ANZTAC {The Australia-New Zealand Trade Advisory Committee). Over two weeks, we traced a path 路 around England, finding out about the water industry at large, telemetry, clinical wastes disposal and stormwater management. This article will focus on some of the trip's highlights.
Mission Highlights First on the schedule was Acumem, North West Water's membrane technology company, which has developed a line of tubular microfiltration membranes. Although oily water separation is their forte, they had recently sold a water treatment plant to Noosa in Queensland. The next stop was at North West Water's new laboratory complex at Lingley Mare, constructed at a cost of 20 million pounds. The facility, being commissioned at the time, will be automated to an unprecedented degree. It will be the analytical centre for the whole company, processing millions of samples each year. North West Water's customer service centre, which handles some 8,000 documents each day, was next. All their mail is passed through a detector to check for bombs and devices which shoot razor blades! The next day we inspected several of the facilities operated by Yorkshire Water: the industry leader in incineration. At the time, Yorkshire Water was being berated in the media for failing to cope with the drought. Throughout the trip we were struck by the bad press received by the privatised water companies, despite their delivering a generally high standard of service. After a night on the shores of Rutland Water, we visited the Innovation Centre at Cambridge run by our host, Anglian Water. The diverse range of technologies there included Kaldnes {the fixed film, suspended media system from Norway) ; and a pioneer greywater recycling unit, designed for household use. A tour of N eotronics' factory in Bishops Stortford was an eye-opener. The company produces industrial gas monitors, in-situ water quality monitoring WATER MARCH/APRIL 1996
devices and related equipment. Many by UK enterprises. The range of topics included rapidly deployed water tanks, electronic components are assembled by telemetry and a rotary fine screen. Useful robots. The piece de resistance was the NOSE, a computer-driven set of poly- contacts were made and it proved a valumeric sensors, which can 'learn' to distin- able exercise. guish odours at very low concentrations. Hydro International, a company spe- Lasting Impressions cialising in stormwater and related areas, What came of all of that? The followwas also an interesting point of contact. ing impressions seemed to worm their Their core product is a vortex unit which way to the top of most minds. separates a proportion of the pollution The UK move to privatisation, boldly from the overflow from combined sewers embarked upon in 1989, has galvanised during storms {most in Europe are comthe water industry and given it new purbined). We saw several fascinating ideas, pose. However, the companies do not including porous pavements and plastic seem to have carried the public with honeycomb modules to lay under car them. As a result, they suffer from a poor parks and store stormwater for use or media image, despite a generally good slow release. record of performance. In a visit to the National Rivers Specific skills in areas such as telemeAuthority offices near Bristol, we heard 路 try and 路remote monitoring, as well as about its pending merger with other agenelectronics, are of a high order. There is cies to become the Environmental scope to employ these even more than is Agency on 1 April 1996. Many of the inialready the-case in Australia. tiatives, eg invertebrate monitoring for There are some interesting technoloevaluating river health, mirror those gies in niche areas for which good marbeing adopted in Australia. kets exist in Australia. Information about After an overnight in Reading, we vis- all the visits and meetings is held in the ited Thames Water, the largest of the pies. AWWA library, for anyone interested in We inspected some of Thames' research following up any topic. projects, including lamellar separators Australia has quite advanced skills and biological aerated filters, as well as and experience in wastewater treatment their main laboratory complex. and in some of the institutional arrangeThames Water also arranged our only ments, so there is also scope for two-way visit to an industrial site where purifica- exchanges of skills and information. tion was taking place: ITI's plating facili- From what we saw of regular sewage ty in Basingstoke. treatment, we felt our own designers At BOC Gases we learned about their could hold their own more than adeworldwide scope then viewed the pilot quately. work being done with CO 2, ozone and Overall, the mission was an excellent pure oxygen. The potential of ozone in venture which exceeded our expectaindustrial wastes was graphically demon- tions. There are now nine well-informed strated with a decolourising plant, while individuals dotted around Australia and the pH correcting capabilities of CO 2 was New Zealand, keen to share their knowlshown in another unit. We also visited edge with colleagues and to cement the Logica, experts in telemetry and related cordial links which we established with activities, who foreshadowed reductions organisations in England. in staff levels; increased reliance on teleThe Group working, decentralising and a focus on core competencies. The members of the mission were: Peter
Brown-Cooper (EPA Western Australia); Richard Stasiak (South Australian Water); On the penultimate day of the mis- Keith Green (City West Water, Victoria); sion, our group addressed around 100 David Dixon (CSIRO Division of Chemicals & Polymers}; David Blau; (WaterCare, UK industry representatives, painting a picture of wastewater treatment and Auckl.and, New Zeal.and); Lindsay Deb:,oppo industrial wastewater regulation in (Department of Environment and Heritage, Australia and New Zealand. In the afterQ,ueensl.and), Errol Samuel (NSW EPA); noon, there were one-to-one sessions with 路 Peter Borrows (Brisbane City Council} and Chris Davis (Australian Water and more detailed discussions. Friday 24 November, the last day of Wastewater Association), who was also the the mission, saw a series of presentations mission leader. 33
Addressing Industry
ENVIRONMENT
KEY ISSUES FOR IRRIGATED AGRICULTURE IN AUSTRALIA JS Abbott This is an edited version of a background paper prepared by J S Abbott far A WWA . Copies of the background paper are available from the A WWA Federal Office, telephone (02) 473 7288.
.Introduction Farmers and crop processors, water supply agencies, research and advisory agencies, manufacturers, equipment suppliers, contractors and consultants are all part of the irrigation industry. The main aim of the industry is to maximise production on the farm. This is where many of the environmental impacts are caused and where many of the solutions will have to be found. Irrigation accounts for around 77% of all water use in Australia, producing 25% of Australia's agricultural production off 5% of the area under crops and pastures. Production of most fruit, vegetables, dairy products, rice, cotton, wine and some sugar depends on irrigation. World wide, irrigation accounts for 70% of water use. Irrigated agriculture produced 70% of the last doubling in world food supply and will need to produce 80% of future increases if predicted world food demands are to be met. However, the high levels of productivity in Australia have exacted a price from the natural environment. In all states, irrigation has led to variations in the seasonal flow in rivers and contributed to rising water tables and salinity. It has also contributed to ecological losses and to increases in nutrients, salinity and pesticide levels in some rivers. This article outlines the key issues associated with irrigated agriculture in Australia and the actions being taken to overcome the problems.
Production In Australia, two million hectares of land are irrigated. The annual farm gate value of the produce is about $6 billion (see Table 1). This is twice the output of the wheat industry and almost as much as the $8 billion of coal, Australia's largest export. Approximately 70% of irrigated agricultural production is processed before being consumed or exported. Off-farm activities multiply the contribution of irrigated agriculture to the nation's economy
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by three to four times in terms of output, income and employment. A high proportion of irrigated production is exported (around 90% in the case of rice and cotton). The export value has fluctuated in recent years due to water shortages in NSW. The normal value of exports is estimated at around $3 billion. On average, the returns per hectare from irrigation in Australia are approximately four times those from dry land production. Despite its importance, the cost of water generally only ranges from 10/o to 13% of cash growing costs {Industry Commission 1992). This will increase as water industry reform is initiated.
Murray-Darling Basin The oldest irrigation schemes, dating from the late 19th century, are found in the Murray-Darling Basin. Seventy five per cent of Australia's irrigation takes place there. There are now significant environmental problems in the basin. Due to concern about the impact of increasing diversions on the riverine environment, in 1995 the Murray-Darling Basin Ministerial Council decided to contain diversions at current levels until more information is available. Environmental problems are also emerging in the Bundaberg, Burdekin and Mareeba schemes in Queensland and in the Ord and the Southwest Schemes of Western Australia. In 1985, the Murray-Darling Basin Ministerial Council was established. It now has representatives from the Queensland, NSW, Victorian, South Australian and Commonwealth Governments. The council's objective is to coordinate planning and management to achieve efficient and sustainable use of the land, water and environmental resources of the basin. As part of an holistic approach, the Murray-Darling Basin Commission (supported by the relevant state authorities) has developed a Natural Resource Management Strategy, as well as strategies for salinity and drainage, algal management, fish management, nature conservation and river care. The commission is also developing an irrigation management strategy which aims 'to achieve an economically and
environmentally ·sustainable and self sufficient irrigation industry by the year 2010'. The strategy will consider higher water charges, cost savings, farming productivity, environmental factors and farming industry restructuring. The Algal Management Strategy has focussed attention on flow rates and nutrients. It is now clear that many of the rivers are over-regulated and flow rates need to be increased. An increased focus on catchment management (particularly soil loss) will be needed to control diffuse nutrient sources. To address the problems of an aging infrastructure and the opportunities provided through transferable water entitlements, there is a need to consider these interacting issues: • water prices • commodity prices • property size • productivity • opportunities for diversification • environmental impact • social issues • changed management arrangements • changed government attitudes to subsidising industry.
Infrastructure Refurbishment The development of a sustainable irrigation industry in Australia will require water management and farming systems that are economically viable and environmentally sustainable. The irrigation industry will need to be restructured to: • increase the revenue available for operating, maintaining and refurbishing assets • improve the efficiency of water supply delivery and farming practices • improve flexibility in allocating water entitlements. Most of the major irrigation systems in Australia are operated by state government agencies but there are some large systems operated by privately managed irrigation trusts in NSW, Victoria and South Australia. In many areas the systems are over 50 years old and require major refurbishment over the next 20 years. Studies by the Industries Commission and others indicate that water charges may need to be increased by 50% to 400% to meet the full cost of operating and maintaining the schemes. To avoid causing undue hardship to WATER MARCH/APRIL 1996
farmers and industry, price increases could be phased in. This would allow time to reduce water use by improved efficiency and for changes in cropping patterns to occur. Costs could also be kept down by gains in operational efficiency, by adopting improved technology or by downsizing systems. In recent years, most states have been increasing water charges in real terms to move towards self funding. Studies indicate that further increases will put pressure on some segments of irrigated agriculture, leading to farm amalgamations and restructuring. It is forecast that as a result of price increases, some poorly performing assets would not be refurbished and some irrigation areas would contract. Other areas would use transferred water rights to expand and this could have environmental benefits. The Council of Australian Governments agreed in February 1994 that the states should progressively review charges for rural water supply so that a positive rate of return on the written down replacement cost of assets is achieved no later than 2001, wherever practicable. The council also recognised that the speed and extent of water industry reform and the adjustment process depend on the availability of financial resources.
Institutional Change In 1992, the Industries Commission recommended that the management of public irrigation distribution systems should be devolved to regional bodies with a view to privatisation. The transfer of ownership should occur before assets are refurbished so that those paying for the service can have a greater input into management decisions. It would also mean that irrigators will decide whether or not to refurbish assets according to commercial self-interest. Through privatisation and corporatisation, the NSW and Victorian Govern.ments have introduced self management of irrigation schemes. Similar plans exist for South Australia and Wes tern Australia. There is still debate about the most appropriate institutional format, the viability of older schemes and about who will be responsible for maintaining and replacing ageing assets. Many irrigation areas have to overcome environmental degradation which compounds financing problems. It has been proposed that environmental obligations are included in the operating license for each irrigator management board, to ensure the focus is not on reducing costs at the expense of the environment. It would also be more difficult to achieve integrated catchment management if irrigation authorities focus solely on their supply activities. WATER MARCH/APRIL 1996
Table 1 Farm gate value of irrigated production in Australia (millions of dollars) 1992-93 Product Crops Cotton, Rice, Cane
Fruit Vegetables
Milk Stock Products Totals
¡NSW
VIC
QLD
SA
WA
TAS
NT
ACT
AUST
359 560
260 0
220 535
88 0
66 0
28 0
4 0
0 0
1025 1095
282 134 172 105
464 264 626 20
347 336 86 11
266 140 64 3
88 134 32 4
44 106 59
0 0 0 0
0 0 0 0
1491 1113 1039 144
1612
1635
1535
560
324
238
4
0
5907
Farming Productivity The ability to pay increased water charges and fund the works needed to deal with environmental degradation can only come from increased farm production. Fortunately, there is a favourable market outlook for most irrigated crops other than citrus. In the past two years there has been a massive increase in the level of investment in the food processing industry, with $260m invested in the Shepparton Irrigation Region alone. The Horticultural Policy Council has forecast that horticultural exports could triple by the year 2010 and most of this would come from the irrigated regions. Research has also indicated that productivity gains can be achieved through adopting new technology, better management and transferring water to more profitable crops. The main constraint to achieving higher returns in the Southern Murray area is the small average farm size, a result of the closer settlement objective of the original development. Many family farms produce incomes below the poverty level and are too small to use or pay for new technology. Currently, only around 300/o of dairy and horticulture farms are large enough to be profitable with the likely increases in water charges. No beef, sheep, meat, wool or cereal farms are large enough to be profitable. In order to remain profitable, farm amalgamations have been occurring across Australia for many decades. In many areas this is facilitated by the Rural Adjustment Scheme.
Transferable Water Entitlements All states allocate water rights and entitlements are mostly attached to the land. In recent years, all states have permitted the temporary transfer of water entitlements between irrigators, especially in drought periods. Limited permanent transfers are permitted in some states. Studies carried out for the commission estimate that gains of $48m in annual output could be achieved from transferable water entitlements. Developing systems which allow the sale of water rights would allow water to move to more
profitable uses, away from environmentally degraded areas or low productivity crops. There is also agreement that water should be formally allocated to in-stream use and other environmental requirements. The Council of Australian Governments Agreement requires that by 1998, all states will have to specify water entitlements in terms of ownership, volume, reliability, transferability and (if appropriate) quality.
Many family farms produce incomes below the poverty level and are too small to use or pay for new technology Variation in Seasonal Flows Storage capacity in the MurrayDarling Basin allows almost total regulation of the flow in the rivers. Annual water extraction in the basin now exceeds 800/o of the mean annual flow. This degree of regulation has significantly modified the rivers' flow regime. It has changed habitats in stream and on the flood plain, affecting wildlife breeding patterns, migration patterns, the composition of species represented in the ecosystem and the character of remnant vegetation. Low flows are also a major determinant of the frequency and intensity of algal blooms in rivers. Studies have shown the importance of intermittent flooding to the flood plain wetlands. The Murray-Darling Basin Commission has funded studies into the basin's more important wetlands, eight of which have international significance. Since 1989 it has also funded projects to improve wetland management. Community involvement has been crucial for the success of these projects. Water is now being allocated for environmental purposes to improve the hydrological regime of the most important wetlands. The commission is prepar-
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ing a strategy for flood plain management which will have a five-year program of activities with community involvement.
Water Logging The irrigation areas in the Murray Geological Basin generally have poorly defined natural surface drainage systems. In many areas irrigation systems were co~structed without providing adequate dramage. These irrigation districts operated for 20 to 50 years before the water tables rose close enough to the surface to depress yields. In many cases the ground ~ater is saline which further depresses yield and leads to soil salination. In around 600,000 ha (40% of the irri-
Annual agricultural production losses from water logging and salinity are estimated to be around $70m gated area) the water table is now less than the safe level of 2 m below the surface. Unless further action is taken this will increase to around 1,300,000 ha by 2010. ~e ground water is rising due to: • accession from rainfall not used by crops (the largest component) • leaching from irrigated areas • seepage from channels. ~tate Gove~ents and the Murray Darling Commission have initiated community programs to construct drainage systems to remove surface run-off. As disch~~g the drainage water is limited by salinity concerns, it is mainly pumped to remote evaporation basins.
Salinity The rising saline water tables associated with irrigation have increased salinity levels in the rivers, caused land salination on the farm and increased costs for urban consumers. The annual agricultural production losses from water logging and salinity are estimated to be around $70m or approximately 1.5% of the gross farm gate output of the irrigated areas. By comparison, the annual loss in farm production in the Western Australian Wheat Belt due to dry land salinity, is estimated to be around $45m. The c?st to urban consumers (mostly in Adelaide) of the scaling and corrosion caused by the increased salinity is estimated at around $65m per annum. The Commonwealth and State Governments have funded a $47m pro~am to intercept saline water seeping mto the Murray in SA and divert it to evaporation basins. Further drainage works are being carried out by industry, the community and State Governments.
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Nutrients Increased drainage returns from irrigated areas can result in elevated nutrient levels in rivers and have contributed to the formation of algal blooms in recent years. A review of the nutrients entering the Murray-Darling system showed that irrigation drainage only contributed 8% of the average nutrients compared with 30% contributed by s~wage treatment plants and urban drainage. Studies are developing action plans for algal management within the basin.
Pesticides Pe~tic_ides ~e used extensively, particularly m mtensive forms of irrigated agriculture. These chemicals can be taken up by aquatic life and concentrated through the food chain, affecting animals such as birds at higher trophic levels. Residues can move off farm in drainage waters but are mainly transported in soil washed off farm by rainfall. For some years river water has been monitored for organochlorides (no longer used) an_d .organophosphate, with generally negligible amounts being detected. In ~e cotton industry, a major user of pesticides, most farmers now collect and recirculate the tailwater. This conserves water and prevents pesticides from escaping. Monitoring studies and research are continuing. Ind~stry guidelines are being d~veloped and licenses for other drainage discharges are being considered in NSW and Queensland.
Research Historically, irrigation research in Australia has been carried out by the CSl~l_O, state government agencies, univ~rsities and industry groups. Investigations have generally been in areas of broad interest or to address specific technical problems. The National Irrigation Research Fund (NIRF), established in 1987, has ~ded a r~ge of irrigation research pro, Jects. Fundmg for NIRF was provided by the Australian Water Research Advisory Council (AWRAC) and state government water and agricultural agencies. One study funded by the NIRF identified the priorities for national research as: • sustainable irrigated cropping systems • water use efficiency • drainage • pollution • salinity • technology transfer • education. . NIRF developed a strategy and irrigation research program which was adopted by the Land and Water Resources Research and Development Corporation (LWRRDC) in 1993. Regular updates of the three-year, $3.5~ program are given in the newsletter, Waterwheel.
Currently there are 21 proj ects addressing five key areas: • improving the management of conjunctive water use • finding cost effective solutions to infrastructure refurbishment • increasing water use efficiency both on and off farm • addressing drainage, salinity, nutrient and pesticide issues • enhancing technology adoption and education. A number of commodity industries independently fund programs. The Australian Irrigation Council (AIC) has had limited success with its attempt to develop the concept of industry financial support for generic irrigation research.
Conclusion Irrigation has had a profound impact on Australia's environment and water resources. It accounts for around 77% of all water use in Australia and the production o_f most fruit, vegetables, dairy products, n ee, cotton, wine and some sugar depends on irrigation. Irrigation plays an important role in the Australian economy. Two million hectares of land are irrigated and the annual farm gate value of the produce is around $6 billion. . . However, the high levels of productivity have exacted a price from the natural environment, creating problems which must be addressed. . 1:Iie aim must be to achieve an irrigation mdustry which is not only economically and environmentally sustainable, b~t also considers the social impact of higher water charges and of restructuring the farming industry.
TRAINING . P?st-secondary training in irrigation is not generally available in agricultural courses across Australia. !fowev~r, the Charles Sturt University is plannmg to offer specialised courses in irrigation and water management. The Irrigation Association of ~ustralia (IAA) has developed irrigation system design and installation courses. IAA has also developed the first_ ?raft of an Irrigation Industry Traimng Plan and is seeking the support of AWWA, LWRRDC and other organisations for submission to the Australian National Training Agency (ANTA). This plan proposes an irrigation advisory council to develop a national coordinated education and training system. The system would include rural and urban irrigation as well as all seginents of the industry, manufacturers, contractors and irrigators.
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