Page 1

I

ISS N 0310-0367

Official Journal of the

AUSTRALIAN WATER AND

WM-ii #1\'M •=i ;~$i•XeJ m•t•J~,

,1 Vol. 12, No. 1, March 1985-$2.50 Registered by Australia Post -

publication no . VBP 1394

I


FEDERAL PRESIDENT A. Lloyd, G.H. & D. , GPO Box 668, Brisbane 4001 .

FEDERAL SECRETARY F. J. Carter, Box A232 P.O. Sydney Sth., 2001 .

FEDERAL TREASURER J. D. Mol loy, Cl¡ M.M.B.W. 625 Lt. Col lins St ., Melbourne, 3000.

BRANCH SECRETAR IES Canberra, A .C.T. Dr. L. A. Nagy, 8 Belconn en Way, Page, A.C.T. 2614. (062 54 1222)

Vol. 12, No. -1, March 1985

water lei Official Journ al AUSTRALIAN WATER AND WASTEWATER ASSOCIATION

CONTENTS Viewpoint-Viv Forbes, President Tax Payers United ........................................... .

5

Association News, Views and Comments ........................ .

6

International Association on Water Pollution Research and Control-News ......... . ................... .

10

Book Review ....... .. .. .. .... .... . ............ .. ........... . .

10

Water Treatment in Queensland Power Stations -R. Roberts ....................... . ... . . .. ............... .

11

Book Review and Publications .... . ......................... . .. .

15

Water Quality Impact of a Fire in a Chemical and Pesticide Warehouse -R. A. Craswell, R. Sadler and G. R. Shaw

18

'Water'-lndex 1983 and 1984 . . ... ... ................ . . . ....... .

23

Calendar ....... . .............................. .. ....... . .. . .

24

Water Quality Enhancement in the Burnett River -M. C. Miller ................................ . ......... . .

28

The Mandalay Water Supply Project .,. -R. M. Lehmann ..... .. . . ..... . ........ . ... .... .. . ...... .

34

Plant-Equipment-People ............. .... .................. .

38

Conferences-Courses- Technical Interests . .. .. ............... .

40

New South Wales C. Davis, G.H. & D. P/L, P.O. Box 219, Neutral Bay Junct . 2089 (02 908 2399)

Victoria .

J. Park, S.R.W.S.C. Water Training Centre, P.O. Box 409, Werribee, 3030. (741 5844)

Queensland D. Mackay, P.O. Box 412, West End 4101 . (07 44 3766)

South Australia A. Glatz, State Water Laboratories, E. & W.S. Private Mail Bag, Salisbury, 5108. (259 0319)

Western Australia P. Jack, Govt. Chem . Labs 30 Plain St. 6000

Tasmania G. Nolan , G.P.O. Bo x 78A Hobart, 7001 . (002 28 0234)

Northern Territory G. Clark, P.O. Box 37283 Winnellie, N.T. 5789.

EDITORIAL & SUBSCR IPTION CORRESPONDENCE G. A. Goffin, 7 Mossman Dr., Eaglemont 3084 03 459 4346

COVER PICTURE The Tarong Power Station, being constructed by the Queensland Electricity Generating Board on a 1500 hectare site near Yarraman in South -East Queensland, will have four boilerlturbogenerator units each rated at 350 MW. These will be the Board 's largest generating units . The station will burn coal from the adjacent Meandu mine of Pacific Coa l Pty Ltd and will be supplied with water from the newly constructed Boondooma Dam near Proston via a 96 kilometer long pipeline. This aerial view, taken In late 1984, shows No. 1 unit in operation with the remaining units under construction . No. 2 unit is being comm issioned as we go to press. The pretreatment plant and filtered water storage tanks can be seen in the lower left hand corner, whilst the demineralisation plant building, acid and caustic bulk storage tanks, pump station and demineralised water storage tanks are between the cooling towers. Cover picture -

courtesy Queensland Electricity Commission .

The statements made or opinion s expressed in ' Water ' do not neces saril y reflect the views of the Australian Water and Wastewater Association, its Council or committees .

WATER March, 1985

I


Water Treatment in Queensland Power Stations P. Roberts Peter Roberts

INTRODUCTION Power stations are large water users and the availability of suitable supplies, and the costs both of procurement of water and its disposal within any environmental restrictions applying, are major considerations in the assessment of alternative sites for new stations. Most water usage is as cooling water in the unit condensers which condense to water the spent steam from the turbines which can then be recycled to the boilers. Other areas of water usage are in auxiliary cooling water systems, in the boiler water circuits, in the ash and dust handling systems, for general cleaning purposes, and as domestic water. The design and operation of water systems in power stations is a complex subject and becoming more so as supplies become restricted and/ or environmental constraints on water discharges increase.

QUEENSLAND POWER {;ENERATION SYSTEM For those not fully familiar with the Queensland power generation system, details of the coal fired power stations being operated or under construction by the Queensland Electricity Generating Board (Q .E.G.B .) are set out in Table I. Q.E.G.B. also operates hydro-electric generating stations at Barron Gorge and Kareeya in North Queensland, and a pumped storage hydro-electric station at Wivenhoe Dam near Esk. Hydro stations require little or no water treatment. Bulimba and Tennyson stations date from the I 950s and in the last few years have received major overhauls and modifications and they will continue in operation into the 1990s . At each station the refurbishment has included a new demineralisation plant. Calli de 'A', Collinsville and Swan bank were constructed in the I 960s to early 1970s by the former Central Regional Electricity Board , Northern Electric Authority of Queensland and Southern Electric Authority of Queensland respectively . The six units at Gladstone, the largest station, were progressively commissioned from 1975 to 1982, whilst the first unit at Tarong went into normal service in May 1984 and No. 2 unit is currently being commissioned. The remaining units at Tarong will be commissioned over the next 18 months, units at Callide 'B' will enter service in 1988 and 1989

The Queensland Electricity Generating Board (Q .E.G.B.) is now the Queensland Electricity Commission by legislation of January 1st 1985. Peter Roberts is Chemical Plant Engineer in the Generation Design Department of the Authority.

respectively, whilst the first unit at Stanwell is scheduled for service in 1991.

COOLING WATER TREATMENT Cooling water systems for power stations can be broadly divided into two types 'once through' and 'recirculating' .

(a) Once Through Systems In Queensland; Gladstone (seaboard), Tennyson and Bulimba (both on the Brisbane River) have 'once through' cooling systems. At Gladstone sea water enters the station via a specially constructed intake off Auckland Inlet, is pumped through the condensers and discharged to the mouth of the Calliope River on the opposite side of the station . At Tennyson and Bulimba , water is drawn from the river upstream of the station and discharged downstream (Tennyson) or to Doboy Creek (Bulimba). At Gladstone, as is typical of seaboard stations throughout the world, cooling water treatment is by chlorination and ferrous sulphate dosing.

brass condenser tubes to act as a corrosion barrier. Gladstone Power Station is a major user of chlorine, current consumption being approximately 300 tonnes/ annum. At present, the station purchases chlorine, however, within a few months the existing chlorination plant will be replaced by an electrolytic plant in which chlorine (or, more correctly, hypochlorite anion OCJ ·) is generated in situ by passing direct current through sea water flowing through an electrolytic cell. Electrolytic plants are common in seaboard stations throughout the world and such plants are in operation at Stokes Hill Power Station, Darwin , and at Torrens Island Power Station, Adelaide. At present chlorination at Gladstone is cyclic, each of the six cooling water circuits being individually dosed in sequence once or twice each day. When the electrolytic plant is installed there will be an option of using continuous low level dosing (0.5 ppm Cl) as practised at Torrens Island . Chlorine demand

TABLE 1. COAL FIRED POWER ST ATIO NS Station

Area Location

Number of Turbogenerator Units

Size of Unit

MW

Total Rated Output

Boiler Pressure mPa

MW In Operation March 1985

Bulimba

Brisbane

Tennyson

Brisbane

Callide 'A'

Biloela

Swanbank

Ipswich

Collinsville

Collinsville

Gladstone Tarong

South Burnett

Gladstone

6 4 2 4 6 4 4 1

31

186

4.2

248

4.2 6.2

,,_ 120

4.3

31} 62 30 70

125}

:}

920 180

8.6 13.1 4.2 6.2

6

275

1650

16.9

1•

350 350

350 350

17.7 17.7

• Being Com missioned, into normal service May /985.

Under Construction

Tarong Callide ' B' Stanwell

South Burnett Biloela

2 2

350 350

700 700

17.7 17.7

Rockhampton

4

350

1400

17.7

Chlorination is used to prevent marine growth, both plant and animal, in the cooling water circuit. If not controlled, such growths lower the efficiency of the condenser, either by physically blocking the condenser tubes (25 mm diameter) or by forming deposits which increase the resistance to heat transfer and in consequence the power output from the turbogenerator unit is reduced. Marine growth can also set up severe localised corrosion. Ferrous sulphate is added in order to form a thin film of iron oxides on the inside of the

varies seasonally, being higher in spring (the spawning season) and summer and lowest in June/July. It is, of course, necessary to electrically interlock the chlorination and ferrous sulphate dosing plants so that they are not simultaneously dosing the same C.W. circuit. The Board has acquired considerable experience in the performance of various materials of construction in chlorination plants, particularly at Gladstone. As a result, materials specifications for such plants have been considerably upgraded and are WATER March, 1985

11


somewhat different from manufacturers' standards. For the various duties in the plant we now specify: Chlorine under Pressure: Piping - Alloy 20 passivated with nitric acid after installation. Valves - All stainless steel with Ptfe seals and seats Gaseous Chlorine under Vacuum: Piping and Valves rigid Pvdf Chlorine Solution: Piping and Valves ABS Small bore tubing in the chlorinators: Ptfe It is considered that these materials are necessary to ensure long life with high plant availability and low maintenance re quirements.

(b) Recirculating Systems The remaining stations; Swanbank, Callide 'A' and Collinsville, and the new stations at Tarong, Callide 'B' and Stanwell, all have recirculating cooling systems in which the hot water issuing from the condensers is cooled in cooling towers and then reused. Makeup to ,replace losses by evaporation and blowdown is added into the pond at the bottom of the towers. Fig. 1 shows a typical cooling water circuit. The makeup water to the above stations is from a river or dam . Chlorination is still necessary but chlorine usage per MW is much lower than for a seaboard station. Dosing of each C.W. circuit once per day for 20-30 minutes is normally adequate to keep the system clean. As portion of the water is evaporated on passage through the cooling tower the concentration of solids in the recooled water increases and it is necessary to ensure that, the concentration does ·not reach the limit of solubility of sparingly soluble salts such as calcium carbonate, calcium sulphate or magnesium silicate, otherwise the resultant precipitate will tend to form a hard scale on the condenser tubes which would impede heat transfer. Unless there are significant environmental constraints on water discharges from the site, cooling water treatment in power stations with recirculating C.W. systems is little different from that in other industries with similar systems. Calcium carbonate scale is

prevented by dosing with sulphuric acid to maintain a Langelier Index at about + 0. 5 whilst the system is blown down to ensure that calcium sulphate or magnesium silicate precipitation does · not occur . In all Queensland stations, magnesium silicate is the factor which determines the required blowdown, the product of magnesium hardness and silica concentration (both in ppm) being limited to 35 000. The mathematica1 relationships between the concentration factor (n), makeup flow (M), blowdown (B) and evaporation (E) are: n=M = E+B B

B

For dissolved species which are not changed by the cooling tower chemical treatment processes, at equilibrium : Concentration in Cooling Water = n x Concentration in Makeup. In Queensland stations, n is in the range of 4-8, usually 5-6. Cooling water circuits have reasonable tolerance for suspended solids provided they are neither abrasive nor liable to form deposits in the condenser tubes . At Swanbank for example, the C. W. typically contains of the order of 50-100 mg/ L suspended solids . In Queensland we have not as yet had to fit sidestream filters to any of our station C.W. systems. Finally, it should be mentioned that in both 'once through' and 'recirculating' systems, the Board also uses various proprietary water treatment compounds such as biocides, usually on an 'as required' basis .

ZERO DISCHARGE The term 'zero discharge' as applied to power stations, industrial plants etc., has now become part of the language of the water treatment industry and in common usage, means that no liquid process effluents leave the site. To achieve 'zero discharge' from a power station usually entails the provision of a chemical or physico-chemical plant as part of the cooling water system . Such plants normally treat a sidestream drawn from the cooling tower basin and returned to the C.W. circuit after treatment but it is also possible that the makeup may be treated. The aim of the

COHCfH'TAAT ION FACTOR I")

.•"

VAPOIU.TION (f \

. ,-c. a

lOW PRESSIMIE Sl£AJ1 FROH TURBIN[

COOllH(i TOWER

Sll.PtUIK A([)

COOlltG WATER PIMP

-r..r,---_-->---......- - - - - 1

c__ _ _ _ _ _

(ti.ORN£

"''"" '"'

AUUAN TO BOUR BLOWOOWN

'"

VIA COHD(NSATE POlwetGPlANT

AJI> HfDttlATIHG PUNT

Figure 1. Typical cooling water circuit. 12

WATER March , 1985

CONDENSATE

[XIRACTIOtl PVNP

treatment is to remove solids from the system in highly concentrated streams or as sludges, so that the amount of water with them is reduced to a manageable quantity. In extreme cases, further processing is required to remove the solids in a semi-dry form. A variety of treatment processes may be employed including lime softening, silica removal by precipitation with magnesium at high pH, ion exchange, reverse osmosis, vapor-compression distillation, multi-effect distillation etc. The longest experience with zero discharge stations is in the U.S.A. and in South Africa, however in Australia we are about to gain similar experience at E.C.N.S.W's Bayswater Power Station where a .4 x 660 MW station in the Hunter Valley is to commence operation shortly. Bayswater has a very sopHisticated cooling water chemical treatment system, both sidestream on the towers and on the makeup. Callide 'B' Power Station has been designed as a 'zero discharge' station. However, rather than instal a chemical treatment plant, Q.E.G.B. has been able to take advantage of favourable site topography and a high net evaporation rate to design an alternative scheme involving the construction of approximately 120 ha of evaporation ponds in terraces. Together with the ash dam, they are expected to provide sufficient surface to enable natural evaporation of all station effluents.

DOMESTIC WATER Bulimba, Tennyson, Swanbank and Gladstone Stations are connected to a treated municipal water supply, however, Callide 'A', Collinsville and Tarong Stations are r.emote from such supplies and hence manufacture their own domestic water from river or dam supply. Conventional clarification/filtration plants are usc;d, the clarifiers being upflow hopper bottomed tanks at Callide and Collinsville and solids recirculation type at Tarong, the Tarong plant is also large enough to use a dry chemical feed system for alum. ,. In a few months' time a water treatment plant at Callide dam will be commissioned, the plant will be owned and operated by the Banana Shire Council. This plant will both augment the water supply to Biloela and supPY treated water to Callide 'B' Power Station in approximately a 2: 1 ratio. Tarong provided a 'first' in Australia in that a treatment plant had to be installed early in the construction programme to provide good quality domestic water for the site workforce during the construction period. Until the completion of the pipeline from Boondooma Dam shortly before No. 1 unit was commissioned the only available water supplies on the site were high TDS local bore and surface waters. The Tarong Construction Water Treatment Plant includes aeration, clarification, filtration and reverse osmosis. It operated from 1980 until early 1984 and is currently being stored at Tarong. Next year it will be transferred to the Stanwell site near Rockhampton where it will perform similar duty in the years 1986-1990. Most of the throughput of the station treatment plants, or from the municipal supplies is used, not for domestic purposes, but as feed to the demineralisation plant and subsequent-


ly as makeup water to the boiler water system.

DEMINERALISATION FEEDW ATER MAKEUP TREATMENT

BOILER

Ion Exchange Processes Cooling water treatment, at least in its basic form, and domestic water treatment are familiar to most in the water treatment industry but this may not apply to the ion exchange processes - demineralisation and condensate polishing - which are used in power stations for the production of ultrapure water. 'Ultra-pure water' is commonly defined as having a conductivity of less than 10 uS/ m. This can be compared with the theoretical conductivity of absolutely pure water (5.6 uS/ M at 25°C) . For another comparison, Brisbane mains water has a conductivity of 25 000-100 000 uS/ m. Very high quality water is necessary for the reliable operation of all steam generating systems excepting some industrial applications operating at very low pressure. In general the higher the pressure, the purer the water must be. Q.E.G .B's more modern demineralisation plants (Gladstone, Tarong and the recently retrofitted plants at Bulimba and Tennyson) routinely produce ultrapure demineralised water as defined above, and the quality of water from the older plants is close to this level. Ion exchange resins are synthetic polymers which contain active groups . Cation resins have hydrogen atoms which exchange with cations such as sodium in the water according to the reaction: R-H · + Na• "' R-Na· + H• Anion resins have active hydroxyl groups which exchange anions such as chloride: R-OH + c1 - "' R-Cl + OHNote that these ion-exchange reactions are reversible and the chemical relationships involved are therefore equilibrium relationships. Some, but not all, anion resins are able to exchange the anions of weak acids such as carbonic acid and silicic acid. The development ;ri the years after the Second World War of these so-called strongly basic anion resins with their ability to remove silica from -.va,er has been a major factor in enabling turbogenerator unit sizes, boiler pressures and steam cycle efficiencies to be increased to today's levels .

Demineralisation In its simplest form, demineralisation involves passing water through a bed of cation exchange resin to remove the cations, then through a bed of anion exchange resin to remove the anions and silica. The hydrogen and hydroxyl ions released from the resin in the exchange reactions combine to form more water. When the capacity of the resins is used up, they are regenerated by applying excess acid and alkali to the cation and anion resins respectively, the above reactions are reversed and the ions exchanged by the resin during the previous service run are released and removed from the system in the regeneration effluent. Within this basic process, there are many possible combinations of detailed process

design, plant hardware design and specific resins. Factors influencing the selection are the plant throughput, raw water quality, treated water purity required and the relative weighting given to · minimising capital and operating chemical costs as there is usually a trade-off between the two. Demineralisation plants in Queensland power stations typically consist of two trains, each train containing, in series, a carbon filter, cation exchanger, degasser, anion exchanger and mixed bed . The carbon filter acts as a polishing mechanical filter but its primary duty is as a chlorine scavenger to protect the ion exchange resins from oxidative attack by any chlorine in the water. The carbon is not regenerated and lasts about IO years before requiring replacement. On passage through the cation exchanger, the salts in the water are converted to the equivalent acids, thus carbonic acid is formed from the alkalinity in the water. As this acid is unstable, breaking down into carbon dioxide and water, the load on the anion exchanger and hence the operating cost of the plant, and, for high alkalinity waters, also the capital cost can be reduced by passing the decationised water through a degassing tower against an upflow of air. In Australian power stations, inclusion of a degassing tower in the train is economically justified if the town or filtered water contains more than about 30 mg/ L alkalinity and all Q.E.G.B. plants include degassing. The degassed water is collected in a tank under the degasser and repumped to the anion exchanger. In plants with modern engineering and proper resin selection, the treated water issuing from the anion exchanger will contain less than, and often much less than, 0.5 mg/ L dissolved solids, mainly traces of sodium and silica. These are removed in a polishing mixed bed which contains both cation and anion resin. During service the resins are intimately mixed, and a mixed bed can be considered to be equivalent to a very large number of cation and anion exchangers in series. Thus, theoretically, a mixed bed is capable of producing the highest purity water. For regeneration, the resins are firstly separated by backwashing with water at a controlled rate, during which the less dense anion resin forms an upper layer . The vessel design incorporates an internal collection at the interface of the resins and, after separation, caustic soda is passed through the upper anion layer and acid through the lower cation layer to regenerate the resins, following which they are rinsed and remixed with air.

Regeneration All Australian power stations use sulphuric acid as the regenerant acid . Hydrochloric acid is superior both from process and hardware cost considerations but is far too expensive for use in any but the smallest, 'package' type demineralisation plants. Regenerant handling systems are of two basic types, the 'batch measurement and dilution' type, and the 'mixing tee' type . In the former , each charge of regenerant is drawn from bulk storage tanks into a batch measurement tank by vacuum, and then diluted, usually to IOOJo concentration, in a

batch dilution tank. It is then pumped from the dilution tank to the i<>il exchange vessel, being further diluted to its application strength en route. In larger plants it is more economic to pump the regenerant directly from the bulk storage tanks and dilute it directly to its application strength in a mixing tee. However, the heat of dilution of sulphuric acid and its effect on materials of construction, and the necessity to ensure that concentrated chemicals can never contact the resins, gives greater engineering and control problems compared with the batch measurement and dilution system. In Q.E .G.B. we have a mixing tee system at Tarong and the Callide 'B' plant will also incorporate such system, but our other plants use batch measurement and dilution. The application strength of sulphuric acid to the resin ranges from 0. 70Jo to 50Jo, depending primarily upon the ratio of calcium to total cations in the water, but sometimes is also affected by engineering factors . Acid concentration must be kept sufficiently low to avoid blocking the internal distribution and collection systems with calcium sulphate. Caustic soda concentrations are .normally in the range 3-5 OJo, but can be lower in some circumstances. The caustic soda is sometimes heated to 40°-50°C. EFFECT OF POLYELECTROLYTES

Operators of demineralisation plants in general do not like the use of polyelectrolytes in the pretreatment plant because all anion resins, to a greater or lesser degree, absorb organic materials into their structure under the acid to neutral conditions applying during the service stage. When these organics are eluted during regeneration there is no problem, and in fact such absollption is desirable for the production of highest purity water. It is when the organics are not eluted during regeneration that so-called organic fouling is said to occur. Orga9ic fouling is of particular concern to the power industry because the anion resins with the greatest ability to economically remove silica are among the most susceptible to fouling. Fortunately, in Australia organic fouling is generally much less a problem than it is in Europe or North America . However, polyelectrolytes used as flocculants or flocculant aids in water treatment plants are high molecular weight organic materials and hence have, again to a greater or lesser degree, the intrinsic capability of fouling some ion exchange resins. Of course, when the water treatment plant is being correctly operated, all of the polyelectrolyte added should be removed in the clarifier sludge or filter backwash. It is when the system malfunctions or is maloperated and overdoses of polyelectrolyte occur that the potential danger to ion exchange resins exists . The clarifiers of our Queensland water treatment plants are conservatively rated so that polyelectrolyte addition is not normally necessary. Where we purchase treated water, we appreciate being informed of any polyelectrolytes in use as significant changes have potential for affecting the station demineralisation plant. However, we would WATER March, 1985

13


trust that in a large well operated and supervised plant, upsets in polyelectrolyte dosing would be short term and well buffered by the municipal reticulation system.

INSTRUMENTATION The major on-line instruments used in monitoring and control of demineralisation plants are conductivity monitors and sodium and silica analysers. Parallel with the developments in ion exchange technology which have led to the reliable and economical production of ultrapure water, have been developments in instrumentation for accurately measuring very low levels of impurities. Station chemical staff spend considerable time and effort to ensure that instruments are properly maintained and calibrated, and if necessary, in modifying or adapting instruments to the very demanding duty associated with low level measurements. In this we work as closely as possible with the instrument suppliers and have occasionally been gratified to find · that improvements suggested by us have been incorporated into later models of the instrument.

CONDENSATE AND BOILER WATER TREATMENT The final major aspect of water treatment in the power generation industry is the treatment of water once it enters the main boiler / turbine, water / steam circuit. A simplified typical flow sheet of such circuit is shown on Fig. 2

transfer , in severe cases physical failure of tubes will occur. • To prevent deposits in the turbine which could eventually lead. to corrosion failures or cause unacceptable vibration levels in the machine. The form of boiler water treatment adopted is mainly dependent upon the boiler pressure. In our older, lower pressure stations, treatment is much the same as in large industrial boilers operating at similar pressures, and typically consists of: • Addition of an oxygen scavenger such as hydrazine or sodium sulphite to remove by chemical reaction oxygen which has not been removed by mechanical deaeration. • Injection of trisodium phosphate into the boiler . This ensures both that conditions are alkaline rather than acid and that any hardness which enters the system (the usual point of entry is via leaks at the condenser) precipitates as a soft, gelatinous phosphate rather than as a hard, scale forming carbonate or silicate . In the event of a large leak the unit has of course to be taken off line and the leak repaired but operational requirements may dictate that we have to try and keep the unit running, at least for a period, with small condenser leaks. The concentration of sodium phosphate maintained in the boiler drum depends on local factors, being typically 5-7 mg/ L at Swanbank and 20-40 mg/ L at Tennyson. • Blowing down the boiler periodically. We try to minimise this as boiler water is valuable, of the order of $2 per kilolitre.

COOllNti

WA HR

ll

SUf' fR HE ATfR

WA TER WA lLS

Figure 2. Boiler/ turbine steam/ water circuit -

The objects of the treatment are: • To 'prevent corrosion. It should be borne in mind that the high temperatures which prevail throughout most of the boiler/ turbine/ condensing and feedheating plant circuit mean that conditions which perhaps could be tolerated at ambient temperatures can lead to very high rates of corrosion at these elevated temperatures. • To prevent the occurrence of deposits on the inside surfaces (water side) of the boiler tubes. At best such deposits will lower the efficiency of the boiler by impeding heat 14

WATER March, 1985

simplified flow sheet.

At boiler pressures much above 12 MPa, and certainly at the pressures of 16-18 MPa used in modern stations, treatment as described above is no longer appropriate, primarily because at these pressures .many solids species are appreciably volatile and soluble in dry steam. For example, at 18 MPa the partition coefficient for sodium chloride, defined as, equilibrium: Concentration in boiler water Concentration in steam is only about 500 and that of silica is even less.

The presence of significant quantmes of solids in the steam passing ~ the turbine cannot be tolerated as they will deposit in the turbine as the pressure is reduced. Whilst proper attention to the design of the boiler drum can minimise the mechanical carryover of water, and hence of solids, into the steam, the boiler designer cannot do anything about fundamental chemical equilibria . Thus, for high pressure systems we attempt to run as close as practicable to 'zero solids' in the boiler . The operating limits current at Gladstone and Tarong are Sodium - not to exceed 350 ug/ L Silica - not to exceed 100 ug/ L Chloride - not to exceed 100 ug/ L Even though low, these limits may be thought to be some way abo_ve zero, but when it is realised that a steady concentration of an impurity in the feedwater will result in the concentration in the boiler drum being 10-12 times that feed concentration within an hour, the need for the water entering the boiler to be as free from solids as possible is apparent. In high pressure systems control of boiler water chemistry is achieved in two main ways. (i) All Volatile Treatment (A VT) of the system. (ii) Provision of a condensate polishing plant immediately following the condenser. In AVT, normally the only chemicals added into the circuit are ammonia and hydrazine, both added immediately following the condensate polishing plant. Hydrazine is again used as a oxygen scavenger whilst the ammonia controls the system pH. At Gladstone and Tarong we operate at pH 9.3 which is equivalent to an ammonia concentration of about 700 ug/ L.

.

CONDENSATE POLISHING PLANT

The condensate ·polishing plant is another ion exchange plant with the main purpose of removing traces · of ionic impurities which enter the system, e~. from condenser leaks. A secondary purpose is to act as a filter to remove minor amaunts of crud , mainly iron and to a lesser extent copper oxides, which are dislodged from around the system. Fig . 3 shows a typical condensate polishing plant flowsheet. Condensate polishing plants differ from make-up demineralisation plants in the following ways: • The plant is functionally in two parts, the polisher groups used for service and the regeneration section . The polisher groups are located in the turbine house basement near the condenser whilst the regeneration vessels are located adjacent to the demineralisation plant in a separate building. Resin is hydraulically transferred, as required , between the polisher groups and regeneration vessels, and this distance may be several hundred metres. There are two main reasons for this approach. Firstly, the service vessels are the wrong configuration, both hydraulically and chemically to give efficient regeneration and secondly, to avoid any risk of a malfunction leading to the injection of acid or caustic into the feed heating train and boiler . • Flow velocities through the service vessels are an order of magnitude higher and the ionic load on the resin two or three orders of


In the operating plants at Gladstone and Tarong the regeneratio~ system includes three main vessels . The exhausted resin is transferred into the first where it is backwashed to separate the cation and anion resins . After separation, one resin is hydraulically transferred into the second vessel. The resins are then separately air scoured to loosen crud, vigorously backwashed, regenerated, rinsed and then transferred to a further vessel for remixing. The regenerated resin is then held until another service vessel is emptied .

REG£NfRAHT5 fRON COHCl(HS[R

R(SIH lRAP~Sf(R LIH[

ION EXCHANGE IN AUSTRALIA TOL.P. Hf.AlUIS

10 R(CiOOAHTS S'l'STEH PQUSHU ril!OUP

R(G(HfRA TIOHPU.Hl

lAAMSRA WAT[JI

Figure 3. Condensate polishing plant -

PIH'

simplified typical flow sheet.

magnitude lower than in the make-up demineralisation plant. • The polishers also act as crud filters as described above. Special resins of higher physical strength are used in condensate polishing plants, to resist the pressure forces in the bed caused by the high flow velocities and mechanical attrition during resin transfers . The service vessels contain a mixed bed of

cation and anion resin, and in Q.E.G.B . plants the control system is arranged so that a thin layer of cation resin is placed on top of the mixed bed . We endeavour to trap most of the particulate matter in this upper layer as it is easier to remove it from cation resin than from anion resin. In each polisher group there are either 2 x 100% or 3 x 50% vessels, so that a standby is always available.

BOOK REVIEW

its approach. Notwithstanding this, the text does include some useful ' rule of thumb' design bases which can be useful when taking a simplified design approach to smaller systems, or when a check is desired of a system for which the design parameters are already specified - often statutory authorities will specify minimum design parameters as a condition of acceptance of the discharge. Consideration is also given to the design for control of precipitate crystalline properties, and reagent selection to overcome possible anion interferences with precipitation: Both of these topics are important as they can significantly affect sludge disposal costs and metals residual in the treated effluent. The book includes sections on costing metals treatment systems; however, these are based on US data and are likely to be of limited use to Australian engineers. The last chapters in the book deal with solids separation and sludge handling, and the information is largely a presentation of standard theory, with little data specific to metals sludge treatment being presented . Access to information in the book is hampered by the lack of an index, this is offset by the comprehensive table of contents. The book's main thrust is on wastewater neutralization and precipitation as the title indicates and in these areas the book should form a valuable resource and is recommended to all those with an interest in the field. P. NADEBAUM

REMOVAL OF METALS FROM WASTEWATER Neutralization and Precipitation Edited by G. C. Cushnie, Jr. Noyes Publications, Park Ridge, New Jersey, USA, 1984. US$32.

This book has been prepared as a manual of design and operating procedures for the removal of metals from industrial wastewaters by neutralization and precipitation. The book reviews wastewater management practices, process chemistry, engineering design, cost estimation, and sludge conditioning, treatment and disposal. As a guide to the considerations and practice of advanced wastewater neutralization and metals precipitation, the book provides a good text for both the student and the practising engineer. A comprehensive, detailed and theoretical approach is presented, and includes, for example, the development of reaction rate equations, the estimation of the number of reaction tanks and their configuration. This approach is particularly useful for application where large discharges and significant costs are involved, or the treated effluent quality criteria are stringent. In practice, however, most of the industrial metals treatment systems will not require a detailed theoretical treatment and the book may be found by some to be too theoretical in

The Australian power industry, over the last 20 years, has been quick to adopt developments in ion excllange where they have been cost-effective . In some ways, our local conditions are not usual by world standards and our general design philosophies and plant designs have evolved accordingly. Ion exchange plants in Australian power stations and large industrial plants in general, and in Q.E.G.B's power stations in particular, can stand technical comparison with plants anywhere else in the world.

ACKNOWLEDGMENTS The assistance of Mr. B. Harris - Sciences Officer, Gladstone Power Station, and other Generation Operations staff in the provision of data from operating stations is acknowledged with thanks . This paper is given by kind permission of Mr. V. Baker, Chief Engineer Generation Design, Q.E.G.B.

PUBLICATIONS ADVANCES IN SEW AGE AND INDUSTRIAL EFFLUENT TREATMENT TECHNOLOGY .Four papers on research and development and the use of new techniques given at the Scottish Branch Symposium of IWPC on March 14, 1984: • Current Research in WW Treatment • New Developments in Sludge Digestion • Research and Development- Consultants View • Vacuum Sewerage. 74 page, paperback, £2.50. PRELIMINARY PROCESSES Revised manual with new sections on disintegration, flow measurement and odour control. 64 pp, 18 figures, 10 plates, £5.00. ENQUIRIES: HOW ARD EV ANS, IWPC, MAIDSTONE, UK. IWES WATER PRACTICE MANUALS Book 2: Water and Land The establishment and management of open-air recreation on water and land by public authorities and private interests. Book 3: Water Supply and Sanitation in Developing Countries Technical and administrative aspects of water supply and sanitation projects.

'

ENQUIRIES: INST. OF WATER ENGINEERS AND SCIENTISTS - U.K. WATER March, 1985

15


Water Quality Impact of a Fire in a Chemical and Pesticide Warehouse R. A. Craswell, R. Sadler and G. R. Shaw SUMMARY Pesticide levels were monitored in water and sediment from affected streams following a fire in a Brisbane agricultural chemical and pesticide warehouse. The results are compared with baseline levels in the same water bodies and with behaviour reported in the literature. The estimated mass of pesticides in sediments sam pled is considerably lower than the quantities known to have existed within the warehouse.

1. INTRODUCTION In the early hours of the morning of 12th August, 1983, the warehouse of Noble Chemicals Pty. Ltd. was destroyed by fire. The Firm is a major supplier of agricultual chemicals and their warehouse ·was situated in suburban Brisbane, less than 100 metres from Rocky Water Holes Creek. This creek is a non-tidal stream which joins Moolabin Creek at about 2.0 km upstream of its confluence with Oxley Creek, a tributary of the Brisbane River. Moolabin Creek is tidal to just downstream of the junction of Rocky Water Holes Creek. Figure I illustrates the streams involved in the incident. Rocky Water Holes Creek was flowing with an uncharacteristically high base flow of 2 to 4 megalitres per day. At 4.30 a .m., about three hours after having been called out, the fire brigade controlled the blaze . In that period, approximately I megalitre of water was sprayed on the fire . Most of this would have entered Rocky Water Holes Creek via stormwater drains. An up to date inventory of the chemicals held at the time of the fire was not available, the most recent inventory having been taken some six weeks previously . Even allowing for minor variations which could have been expected to occur since the stocktake, there were very large quantities of pesticide present which would cause a potential hazard upon being washed into a watercourse. Amongst these, a number were insoluble (e.g. arsenic compounds) and would probably find their way into sediments within the first few kilometres of the stream. There were also considerable amounts of organochlorine and other bioaccumulatable substances stored on the premises . The fire released a large quantity of pesticides into the environment. Results of subsequent monitoring over the next four weeks to determine the fate of these compounds downstream of the site of the fire are reported herein.

2. MATERIALS AND METHODS Nomenclature of pesticides is in accordance with the trivial names prescribed by A.S. 1719-1981. The organic pesticides analysed in this survey fall into four major categories: organochlorines, organophosphates, carbamates and herbicides. The individual pesticides were classed into these categories because of molecular structural similarities or because a single analytical method is applicable to all pesticides in a single category. As a consequence of this last fact, an analysis for one of these pesticide categories would detect all pesticides falling into that analytical category if they were present in the sample. Sampling of water and sediment were carried out following the accident at the locations shown in Figure 1. Water samples were collected and stored in accordance with A.S. 2031-1978 . Sediment samples were collected using a Van Veen grab. After mixing in a stainless steel bucket, sub-samples were transferred to 500 mL glass containers, prepared as described for aqueous pesticide samples . Tables 1 and 2 list the samples which were routinely analysed for

Robert Croswell is Executive Engineer and Dr. Ross Sadler is Environmental Chemist with the Water Quality Council of Queensland. Glen Shaw is Senior Chemist with the Government Chemical Laboratories, Queensland. 18

WATER March, 1985

R. A. Craswell

R. Sadler

G. R. Shaw

organic pesticides following the fire. Sites 3, 5, 6 and 7 were the most commonly sampled sites because of ease of access and because they represented significant points in the stream system . Site 3 is a freshwater, non-tidal site where pesticide was subjectively noted on the day of the fire. Site 5 is an upstream tidal site in Moolabin Creek. Site 6 is a tidal site in Oxley Creek which would indicate dispersion up into this otherwise unaffected creek and site 7 would indicate passage of pesticide residues into the Brisbane River. On 16th August, four days after the fire, an intensive sampling of sediments was conducted in Rocky Water Holes Creek . Samples were collected from Rocky Water Holes and Moolabin-Creeks at nominally 100 m spacing for one half of one kilometre, 200 m spacing for a fur ther 600 m and 500 m spacing for a further one kilometre. These sites are shown in Figure 1. On 25th August, samples of both surface water and sediments were taken at one kilometre spacing in the Brisbane Riv~r for 9 kilometres upstream of AMTD 39.0 km, and for 9 km downstream of AMTD 38.0 km (AMTD is an adopted centre line distance measured upstream from zero located at the mouth of the Brisbane River where it joins Moreton Bay) . For extraction of chlorophenoxy acid Iferbicide residues, samples (500 mL) were acidified to pH 2 and extracted with diethyl ether (I x 150 mL and 3 x 100 mL aliquots). Following concentration, the extracts were methylated and the methyl esters of the chlorophenoxy acid esters extracted into petroleum ether . The extract was concentrated by low temperature evaporation and the pesticides separated by gas chromatography using electron capture detection. For determination of similar residues in sediments, procedures followed were similar to those described above. Acetone/ petroleum ether and acetone/ ethyl ether mixtures were used in place of diethyl ether for the initial extraction, which was carried out in a flask shaker, ·using 100 g (wet weight) samples of sediment. Gas chromatographic separation conditions were as follows: Organochlorine pesticides were separated isothermally on a 2% OV-1/3% QF-1 mixed phase column at 2J09C, or (when resolution of complex mixtures was required) on an OV-101 packed column. Separation of chlorophenoxy acid herbicides was performed isothermally at 215°C using a 2% OV-1 3% QF-1 packed column. Nitrogen was used as the carrier gas for packed column chromatography and helium for capillary column chromatography. Flow rates were 35 mL/ min. and 0.7 mL/ min. respectively. No general limits of detection for the analysis of the various pesticides could be set. This is a result of the widely differing concentrations of individual pesticides present in the various samples. The problem is also compounded by the fact that the concentrations of the different pesticides in a single sample may differ by many orders of magnitude. Hence, the high concentration of a certain pesticide in a sample may interfere with the determination of another pesticide present at a lower concentration.


(at the point of entry of the stormwater drain) also smelled ht.avily of pesticides and showed an oily fi[m on the surface . This was attributed to the clean-up operations at the site of the fire and adjacent properties onto which pesticide had been hosed during the fire fighting.

3.2 Organochlorine Pesticides

~

.

-~---••

Surface waters and sediments were sampled as shown in Tables I and 2. Concentrations of organochlorine pesticides for water are given in Table 3 and for sediments in Table 4. In most cases limits of detection have not been reported as they varied according to the concentrations of other pesticides. Residues of chlordane and lindane (which appeared sporadically in sediqients) have not been reported. The analysis of the samples of water and sediment from the survey of the Brisbane River on 25th August yielded only a small number of positive results. No residues exceeded the detection limit for organochlorines in water (0 .01 /.Lg/ L) and only eight sediment samples contained pesticide residues above the detection limit for organochlorines in sediments (0.05 /.Lg/ kg) . The maximum results were 27 /.Lg/ kg for dieldrin, 40 /.Lg/ kg for DDT, 4 /.Lg/ kg for DDD and 8 /.Lg/ kg for DDE. All the maximum results were reported from the site nearest the confluence and 0.3 km upstream. No other results exceeded 3.9 /.Lg/ kg.

Si te of Water Sample only

Site of Sed i ment Sample only

3.3 Organophosphorus Pesticides

Si te of Water and Sed iment Sample SCALE

1 : 25 000 12 km

Figure 1. Map of steam system affected by fire showing sampling sites.

3. RESULTS

Concentrations of organophosphorus pesticides in water and sediments are given in Tables 5 and 6 respectively . The incompatibility of many organophosphorus pesticides with lime, due to alkaline hydrolyses could result in low levels of organophosphate residues ' within the creek system, since quantities of lime were stored with pesticides in the warehouse.

3.1 Subjective Assessments Field observations were made during sampling visits on the day of the fire and the next two days. These observations were as follows: • 10 a.m . to 11.30 a.m . Friday 12th August. Fire crews were damping down the remains of the fire and water was flowing freely into the drain leading to Rocky Water Holes Creek in two streams. One was of a milky appearance and the other was red in colour . Both were heavily contaminated and smelled strongly of pesticides. The creek was inspected just below the point of discharge from the stormwater drain where it had a strong pesticide odour and a considerable amount of foam was evident. Very likely, the foam represented the wetting agents used in formulations. Pesticide odour was clearly evident at a site 300-400 metres downstream of the fire and also at a site a further 300 metres downstream. On inspection of the creek in the Brisbane Golf Course Area a further 700 metres downstream there was no evidence of any pesticide odour, nor had the greenkeeper detected any during that day . • Morning . Saturday 13th August. Pesticide odour was noticeable at sampling sites 3 and 5 but not at sites 6 and 7 in Oxley Creek . • Morning. Sunday 14th August. The first two Sites 3, and 5, again had a very strong smell of pesticides, but a trace was evident at Site 6 in Oxley Creek a distance of 3.5 kilometres downstream of the fire indicating the rapid dispersion of the pesticide. No odour of pesticides could be detected at Site 7. The area at the warehouse was visited and a continuing pesticide odour was noted there. Rocky Water Holes Creek

3.4 Carbamate Pesticides No carbamate pesticides were detected in any surface water sample (detection limit 10 /.Lg/ L). Residues of carbamate pesticides in sediment samples were all below the detection limit (50 /.Lg/ kg) . The carbamates present in the warehouse would presumably have been rapidly coverted to a.naphtnol when flushed into the creek system, especially if alkaline conditions existed from the presence of lime.

3.5 Chlorophenoxy Acid Herbicides Results of analyses for chlorophenoxy acid herbicides in water and sediments are included in Tables 7 and 8 respectively. These tables show results at sites where residues in signficant concentrations were detected, with the exception of the Brisbane River survey of 25th August, for which only three of the eleven sediment samples contained herbicide residues above the detection limit (0.5 /.LS/ kg). The maximum concentration reported was 0.8 /.Lg/ kg. The detection limit for the Brisbane River water samples was 0.01 /.Lg/ litre .

3.6 Arsenic and Mercury In addition to the analysis reported above, data was also obtained on the levels of arsenic and mercury pesticides in the stream system, as the warehouse was known to contain pesticides of these types . The maximum reported concentration of arsenic was 4 ,,gl L in water and 12 mg/ kg in sediments. For mercury, analysis of water samples showed no residues above the detection limit (0.5 ,,gl L) and the maximum concentration reported in sediments was 181 J.Lg/ kg. WATER March, /985

19


TABLE 1. WATER SAMPLES FOR PESTICIDE ANALYSIS FOLLOWING FIRE (For details of sampling sites see Figure 1)

TABLE 2. SEDIMENT SAMPLES TAKEN FOR PESTICIDE ANALYSIS FOLLOWING FIRE (For details of sampling sites see Figuw 1)

DATE 12 / 8 13/8 14/8 1S/8 18/8 22/8 6/9

2 3 4

5 LU

IV)

6 7 8

9 10

DATE

1s/a rn/s 22/s 6/9

momoooo mDDDDDD ~m~mrn~ffi mDDDDDD o~~mrn~EE ommmrnrnrn o~~~rnrnrn ooomrnrnrn ooomrnrnrn ooomrnrnrn

3

5 6

.,_ LJ..J

7

Vl

8 9 10

m@@EB m@@EB mEBEEEB mEBEEEB ~EEEEEB ~EEEEEB ~EEEEEB

KEY TO TABLE

KEY TO TABLE

Shading represents analysis for organoc hlorin e carbtimate

Shad ing represents analysis for

or ganophos pha le herb icide

organochlorine carbamate

3.7 Environmental Effects On Saturday, 13th August, an inspection of Rocky Water Holes Creek noted three dead fres hwater eels (Anguilla reinhardtil). During the extensive and repeated sampling programme no evidence of any other dead fish or fauna was found and no reports of dead fis h were received from the public. There was no obvious evidence of damage to littoral vegetation .

TABLE 3. ORGANOCHLORINE PESTICIDES IN WATER ,..gl litre Site

2 3 4

5 6 7

Sample Date A ug. '83

Total DDT

Dieldrin

12.8.83 12.8 .83 12.8.83 12.8.83

2 800 620 3 000

250 250 1 200 3

13. 8.83 13. 8.83 13.8 .83 13.8 .83

24

20

â&#x20AC;˘ Not detected

20

WATER March, 1985

Aldrin

8

â&#x20AC;˘ 300

Heptachlor

950 320 850 6

Endosulfan

1 400 410 1 300 13

6 3

1.5

otgan ophosphate herbicide

4. DISCUSSION 4.1 Other Reports of Environmental Behaviour of Pesticides Pesticides may be removed from a water body by (I) fluvial movement, (2) sorption by macrophytes or sediments, (3) metabolism . To eliminate the complications caused by the first means of loss, most workers have concentrated on static water bodies such as lakes, salt marshes, etc. and hence their results are not directly comparable to the present situation . In addition, most of the investigators have studied the fate of a fairly low level application of pesticides, such as those used for treatment of insects or plants in lakes. Generally the organophosphorus pesticides tend to be shorter lived and less subj ect to bioaccumulation than the organochlorines . Amongst organochlorine insecticides, DDT and cyclodienes are the most readily adsorbed onto sediments (Brown, 1978) . When a variety of organochlorine pesticides was shaken with a turbid, aqueous suspension, the ratio of free to bound insecticide varied from I: I 000 for DDT to I :4 for endosulfan (Richardson and Epstein , 1971). The results in Table 3 show that both pesticides disappeared rapidly fro m the aqueous phase, most within the first 24 hours, there being little evidence for a preferential loss of DDT. Accumulation of DDT in the sediment was noted at a number of sites, particularly site 3 at the Rocklea underpass and site 9 at the confluence of Oxley Creek and the Brisbane River. Results obtained by other workers suggest that rather

.


TABLE 4. ORGANOCHLORINE PESTICIDES IN SEDIMENTS /Lg/ kg wet weight Site

Sample Date

DDT

6 7 8 9 10

15 .8.83 15.8.83 15 .8.83 15 .8.83 15.8.83 15.8.83 15 .8.83

530t 490t 890t 140t 350t 310t I 050t

11 12 13 14 15 16 17 18 19 20 21

16.8.83 16.8.83 16.8.83 16.8.83 16.8.83 16.8.83 16.8 .83 16.8.83 16.8.83 16.8.83 16.8.83

I 400 800 2 400 3 100 3 500

3 6 7 9

18.8.83 18.8.83 18.8.83 18.8.83

540 130 20

3

22 .8.83 22 .8.83 22.8.83

720 60 I 000

5

5 9 3

5 6 7 8 9

DDD

Dieldrin

Heptachlor

180 90

100

500 80 I 200 4 500 I 000 30

DDE

280 200 490 420 290 120 30 270 240 100 10

250 130 320 300 100 100 30

280 100 420 20

6

310

190

270

450 120 140

160 40 20

420 250 60

120

600 100

10

clusions cannot be drawn regarding long term persistence of this· substance. Heptachlor appeared briefly in water,.samples and was observed in sediments over the first 300 m of Rocky Water Holes Creek . Organophosphate insecticides are generally of lower persistence than organochlorines. Most are hydrolysed in water under alkaline conditions, with the exception of chlorpyrifos. There is a considerable gradation in the relative stabilities of organophosphorus pesticides in water . In a study where stabilities of organophosphorus insecticides in river water were compared, percentages remaining at the end of two weeks varied from 10% for malathion to 100% for monocrotophos (Brown 1978). The results in Table 5 show initial high concentrations in water of dimethoate, chlorpyrifos, fenamiphos, diazinon, malathion, methamidophos and parathion-methyl at most sites, followed by a rapid decrease as was noted for organochlorines . There is some apparent persistence of several pesticides, particularly dimethoate and fenamiphos at site 3, the day after the fire. Significant concentrations of these compounds also occurred at.site 5 on this day . It is of interest to note that several pesticides (e.g. monocrotophos, dimeton-methyl) which were not recorded on the day of the fire, were detected on 13th August. Whilst this could be taken to represent a secondary release of adsorbed pesticides, it seems more likely that the observation is the result of cleanup operations at the factory.

70

TABLE 6. ORGANOPHOSPHORUS PESTICIDES IN SEDIMENTS /Lg/ kg wet weight

50

6.9 .83 6.9.83 6.9.83 6.9.83 6.9.83 6.9.83

820 285 1.0 0.5 2. 5 0.3

Site Sample Dimethoate Chlorpyrifos Diazinon Malathion Methamidophos Date

0.6

longer half-lives would be expected for DDT, on the basis of sorption and metabolic phenomena and hence the observed changes in both aqueous and bound DDT are probably the result of fluvial movement. When water bodies are treated with DDT, the DDT passes first to the macrophytes and is then released to the water, from which it finally passes to the sediments. For example, in a Florida salt marsh , treated at 0.22 kg/ ha with DDT, the macrophyte Ruppia maritima showed residues of 75 ppm after 3 to 4 weeks and these declined to 0.5 ppm one month later (Croker and Wilson, 1965). In a farm pond, treated with 0.02 ppm DDT, the Potamogeton contained residues of 30 ppm the day after treatment, which declined to about 4 ppm two weeks later, at which time the plants began to die. The DDT had disappeared from the water after 3 weeks but persisted in the mud for 8 weeks (Bridges et al, 1963). Aldrin (which appeared sporadically in sediments) is readily converted to dieldrin . The latter compound is relatively stable although organisms may convert it to photodieldrin (Brown 1978). It is of interest to note some persistence of dieldrin at site 3 (Table 4) and these results suggest a considerable accumulation in sediments over a period of time . As sampling was terminated on 6th September, further conTABLE 5. ORGANOPHOSPHORUS PESTICIDES IN WATER /Lg/ L 2

11 12 13 14 15 16 17 18 19 20 21

16.8 .83 16.8 .83 16.8.83 16.8.83 16.8.83 16.8.83 16.8.83 16.8.83 16.8.83 16.8.83 16.8. 83

5

t Total DDT

Site

7 9 10

15.8 .83 15.8.83 15.8.83 15 .8.83 15 .8.83

3

2 100 100 1. 2 0.6

1 100 310 1.0 0.4 3.2 0.2

3

4

5

6

• Not detected

820 3 700 300 I 800 I 400 I 200 360

20 70

420 I 800 210 790 I 700

4

200 180

90

50

70 220

160 180 120

500 150

1 8

130 210

110 40

50

120 80 380 150 200

310

180 220 200 20 20 60 80 60

140 110 200 100 220

50 20 100 60 10 10 't-

3 700

50

500 3 200 2 400 2 000 400 100 ' 420 920 120 40

240 180

• Not detec ted

Surveys at points 3, 5, 7, 9 and 10 on the 15th August revealed only evidence of dimethoate and diazinon in sediments and neither of these compounds is reportedly more resistant to degradation than are other organophosphates. Where degradation of organophosphorus insecticides in river water was studied, 55% of the original dimethoate remained undegraded at the end of a two week period (Brown, 1978) . On 16th August, a detailed study of organophosphate residues was carred out in Rocky Water Holes Creek (Sites 11-21, Table 6). The data clearly shows a wide variety of organophosphorus pesticides in sediment, near the site of the accident, followed by a variation in deposition downstream. This may reflect a variation in the pattern of release and adsorption of the pesticides, or it may also, in part, reflect TABLE 7. CHLORPHENOXY ACID HERBICIDES IN WATER /Lg/ litre

7

Site

Sample Date

4

12. 8.83t

3

13 .8.83 13 .8.83 13.8.83 13.8 ..83

Sample date Aug. '83

Dimethoate Chlorpyrifos Fenamiphos Diazinon Malathion Methamidophos Parathion-Methyl

20 100 20 20 30

80

5 6 7

2, 4-D

2,4,5-T

Diuron

3

2

2 800

50 3 2

2

• Not detect ed t Samples at Sites I, 2 and 3 on 12. 8.83 contained organochlorinc pesticides at too high a concentratio n to permit determinati on of herbicides.

WATER March , 1985

21


TABLE 8. CHLORPHENOXY ACID HERBICIDES IN SEDIMENTS µg / kg wet weight Site

Sample Date

3 5 6 7 8 9 20

15.8.83 15 .8.83 15 .8.83 15.8.83 15.8.83 15 .8.83 15.8.83

II 12 13 14 15 16 18 19 21

16.8.83 16.8.83 16.8 .83 16.8.83 16.8.83 16.8.83 16.8.83 16.8.83 16.8.83

3 9

18.8.83 18.8.83 18.8.83

10

22 .8.83 22.8 .83 22.8 .83

3 9

10

2,4-D

50

60

2,4,5-T 58 100 30 70 120 60

50 20

Diuron

40 30 40 10 20

50 30 40

400

20 I 200 80 140 2 000 70

10 30

20

50 50 399

40

260

40 700 25

20

Detection limit for analysis of 18.8.83 was 5 µg/kg. • Not detected

difficulties in obtaining statistically uniform samples. The differences between values obtained at site 3 on 15th August and the nearby site 17 the next day would tend to support the latter view. Adsorption of the pesticides largely occurred in the upper region of the stream, with the exception of dimethoate. As was observed above, fluvial movement is probably the major factor responsible for movement of pesticides from the waterways . Chlorpyrifos was the major organophosphorus pesticide observed after the accident. When applied to ponds at 1.1 kg/ ha, the initial concentration of chlorpyrifos decreased from an initial 220 ppb to 3 ppb in one week within the aqueous phase. During the first week, the chloropyrifos concentration in the sediment reached 520 ppb, but fell to 250 ppb by the end of the second week (Hurlbert et al. 1970). Most authors have concluded that chlorpyrifos is readily hydrolysed in polluted waters and is easily absorbed by particles of organic matter. If these were the only means of removal in the present instance, longer residence times than those apparent from Table 6 might have been expected. The herbicide concentration in most of the samples taken on 12th August could not be measured . On the first and second days after the fire, levels of all three herbicides in the water were fairly low, except at site 5 on 13th August. Elevated levels of herbicides were again detected in the water at all sites sampled on 15th August (Table 7). This could possibly reflect a secondary release of herbicides . 2,4-D has been shown to reach its maximum concentration in water 1-2 weeks after application, this being the result of uptake by vegetation, followed by subsequent release upon lysis of the tissue (Brown 1978) . As would be expected, herbicide found its way into the sediment. The appearance of herbicide in the sediment was fairly short lived, probably as a result of fluvial movement.

pesticides in sediment were estimated from the analytical results. The sediment layer containing pesticides was taken to ~ve a mean width of 3 m and a mean depth of 100 mm. This method gave estimated quantities of various pesticides contained in 615 m3 of sediment as: Dieldrin 0.28 kg Total DDT 2.4 kg Total Organophosphates 2.0 kg Total Chlo rophenoxy Acids 0.26 kg These quantities bear little relation to the masses in the inventory . As a comparison, results from a survey of dieldrin in sediments of the tidal reaches of the Brisbane River in I 978 indicated a mean level of dieldrin of approximately 2 µg / kg over the 80 km of the Brisbane River (Water Quality Council unpublished report). Taking a sediment depth of 0.5 m and a mean width of 200 m, a value of 32 kg of dieldrin can be calculated. This is also quite small in terms of total usage of dieldrin in the catchment over the years. The above results would suggest that dredging sediments is an unsatisfactory method of clean-up for a stream following a pesticide spill. Little pesticide is retained in the sediment and the dredging operation is likely to cause further environmental problems from disturbance of sediments.

4.3 Variations Between Results at a Site The variation in pesticide concentrations of water samples between sites on the day of the fire suggests that different pesticides were released with the firefighting water at different times during the blaze. The lower concentrations of pesticide in water samples taken from the Brisbane River indicates loss by sorption in the downstream waters and the dilution of the pesticides in the larger tidal water bodies downstream . The results for DDT in sediments at site 9 in the Brisbane River on 22nd August indicate that at least some concentrated pesticide solutions reached that stream . There was a considerable variation in apparent pesticide concentration between samples taken at the same site on different days . This indicates that the method of sampling (i .e. subsampling composited material) did not average local variations in concentration. No study was made of the variation in concentration with depth below the sediment-water interface and the collection of samples by a Van Veen grab in the deeper waters would have yielded a mixture of subsurface -and surface sediments in varying proportions. This would introduce further complexity into interpretation of the results . The comments included above, relating to other published work, also indicate reasons for variations . Flu vial transpoft in the non-tidal reaches will be undirectional downstream, whilst both upstream and downstream transfer would occur in the lower reaches . The Brisbane River has a mean spring tidal range of 2.2 m and a mean neap range of 1.1 m in the reaches near its confluence with Oxley Creek. The tidal excursion would be approximately 6 km for a neap tide of I. I m (Ozturk, personal communication).

4.4 Comparison with other Records Following a bulk carrier capsize near site 3 in I 972, part of the watercourse comprising Rocky Water Holes and Moolabin Creeks was heavily contaminated with DDT emulsifiable concentrate (Hurwood, 1973) . DDT concentrations as high as 7 000 ppm were reported for water samples in Rocky Water Holes Creek and I 850 ppm in sediments of Moolabin Creek. As part of the Water Quality Council's routine surveillance of ambient water quality in various waters of the State, samples for analysis of organochlorine pesticide residues have been taken during the period 1978-1982. The maximum concentration reported from sediment

4.2 Estimates of Masses of Pesticides TABLE 9. MAXIMUM CONCENTRATIONS OF ORGANOCHLORINE PESTICIDES IN SEDIMENTS 1978-1982 INCLUSIVE

There are three possible fates for pesticide stored in the warehouse: (I) Loss to the stream in water used to control the blaze; (2) Destruc-

tion in the fire; (3) Removal as debris after the fire . Damaged containers of pesticide were disposed of at the Brisbane City Council's waste disposal area. No estimate can be made of any of these. An inventory of the warehouse contents (taken about six weeks before the blaze and assumed approximately correct) listed a total of I 743 kg of organochlorine, I 102 kg of organophosphorus and 385 kg of chlorophenoxy acid pesticides. An attempt was made to estimate the mass of pesticide in the sediments of the two kilometres of Rocky Water Holes and Moolabin Creeks sampled. Using simplifying assumptions, the quantities of 22

WATER March, 1985

Water

Rocky Water Holes Creekt Mollabin Creekt Oxley Creek Site 7

No. of Maximum Concentration µg l kg Samples _ D_D_ T -D- i-el-d-ri_n_ A_ld-r-in_ C _ h_l_o_rd_a_n_e _L_ ,__n-da_n_e

20

I8 21

10.2 58 .0 0.7

55.7 223.0 35.0

11.1 12.0 0.8

• Not detected Sample location s do not correspond to any of these shown in Fig . I

t

35.0

2.2


samples during that period and the number of samples taken nominally at three-monthly intervals are shown in Table 9. It is noted that in the period 1974- 1978, larger concentrations of organochlorine pesticides in sediment were reported . The~e figures are not now , considered relevant for comparison with results from the fire. In the intervening years , the implementation of the Clean Waters Act caused major changes to the numbers and locations of discharges of wastes. Analysis of sediment samples for mercury from 17 Rocky Water Holes and Moolabin Creek sites, gave mercury levels of 0.01 -0.07 mg/ kg and 0.01-0.21 mg/ kg respectively. The routine analysis for residues of other pesticides is not carried out by the Water Quality Council in any waters of the State . Some results for the chlorophenoxy acid herbicides are available from a Water Quality Council special survey . Analysis of 17 water and 26 sediment samples near a forestr y area yielded one positive result for water (0.01 l'g/ L) . The detection limit for water was 0.01 l'g/ L and for sediments was 0.1 l'g/ kg (Pumicestone Passage Study 1982).

variety of pesticides at one time. No littoral vegetation was observed to have been affected and no fi sh kills , except the small one on the day after the fire were noted. Unless pesticides are removed and destroyed, their relocation from sediments to land disposal areas only makes sense if the latter areas do not permit further migration and the process of relocation, itself, does not further disperse the pesticides. Once pesticides are allowed to reach the environment and become dispersed, the process is to all intents and purposes, irreversible. As unacceptable as this proposition appears, it can be stated with confidence that under the prevailing circumstances, nothing could have been done at the time, nor in the immediate subsequent period to prevent the irreversible dispersi°on of the pesticides into the environment. What could have been done after the event e.g. dredging of sediment for disposal at waste disposal sites, would have resulted in a marginal reduction in the total mass in the environment.

S. CONCLUSIONS The main conclusions can be stated as follows : Unacceptably large quantities of pesticide were released from the warehouse during the fire and residues were detected in environmentally significant concentrations at many stations . (ii) Short term observable ill-effects have been minor. (iii) Within one month of the fire, the pesticides were irreversibly dispersed through the environment. Most of the residues¡ had already passed from the water. (i)

4.5 Additional Sampling Additional samples were collected on 10th September within the irrigation dam and pump well of the Brisbane Golf Club premises. Irrigation had been temporarily suspended following the fire. The water samples were analysed and the results confirmed that residues in _water within the Brisbane Golf Club premises were no cause for concern . Despite the loss of large quantities of pesticides, downstream water users were disadvantaged for less than a month .

4.6 Overview This release of pesticides to the environment differs from the chronic and insidious releases from the use of pesticides within the community at large, in that it was a release of large volumes of a wide

6. ACKNOWLEDGEMENT The permission of the Director of Water Quality, Department of Local Government to publish this paper is gratefully acknowledged, as is the criticism of the Editorial Sub-Committee of the Water Quality Council.

REFEREN CES-SEE PAGE 37

INDEX - WATER -1983 & 1984 VOL. 10 - 1983 No.1 - MARCH Sewering of Brisbane - Some Remeniscences .. ....... . .. . . . . . . . . .. .. . F. Greenhalgh New Methods for the Determination of Sulphur Anions in Natural S. Rama Bhat, J. M. Eckhart and Wastewaters .. . .. . .. . . . . . .. . .. . ... .. . . . . and N. A. Gibson The Wastewater Industry in Queensland . . . ... . ... . . . . J . O' Connor No. 2 - JUNE A Method for Estimating Odour Concentrations Around Wastewater Treatment Plants ..... . .. . .. . ........ .. L. Koe and D. K. Brady Tenth Federal Convention - Sydney 1983 . . . . . . . . .. . ... . .. Report Hi-A WWA-tha - The Song of Convention '83 . ..... . .... . G. R. G. In-Main Oxygen Treatment of Domestic Sewage, Boulder Bay Sewerage R. Hemmings, Scheme . .. . . . .. . .. . . .. . . . . . . . .. . . .. . R. Anderson and R. Shaw

No. 3 - SEPTEMBER Alternatives to Chlorine for Water Disinfection . . ... . . ... . .. ....... . . . ... . .. . David ,Barnes Water Quality Factors in Inland Waters -An Overview , Lake Eppalock .. . .. . . .. . . . W. M . Drew No. 4 - DECEMBER Ranger Uranium Mines - Water P . J . Burgess, C. J . Gilbert Management System ..... .. . . .. . and Ranger Uranium Mines P / L Specialists Conference Darwin - 1983 . .. . . .. .. . . . . ... . .. . . Report Water and Wastewater Treatment in Victoria - An Operational Review ... . . . .. ... . .... . . . . . . . . . R. L. Povey

VOL. 11 - 1984 No. I - MARCH New South Wales Water Plan and Water Use Efficiency ... . ... ... ... . . . M . Lindner and C. Creevey Storage and Salinity Works for New South Wales in the 1980s . . .. . . . .. . .... . . . . M.A . Watts

Keeping the Murray Clean - The Role of the River Murray Commission .. . ..... . . . . . . . . ... K. E . Johnson No . 2 - JUNE Deepening Urban Wetlands: An Assessment of Water Quality in Four Wetlands on the Swan Coastal Plain, W .A . . . . . . . . ... . ... P . Newman and L. Hart The Peel-Harvey Estuarine P . B. Birch, J . 0. Gabrielson System - Review of Study Progress . . .. ~ ... . . and E . P. Hodgkin Predicted Oxygen Transfer Characteristics - Riser Pipes at Wastewater Pumping Stations . .. . ... . . . .. .. Keith Cadee Oxygen Dissolving Facilities - The K. Cadee, T . E. Long Munster Pumping Station . . .. . . .. . .. . . . . . . . . ... and R. E . Wain The Asian Institute of Technology - A Unique Organisation . . . . .. . . ... . ... .. ..... . . . . .. . T . L. Judell No. 3 - SEPTEMBER By-products of Chlorination . . .. ... . . . B. C. Nicholson, K. P . Hayes and D. B. Bursall Land Management - Key R . E. Hartley, D. J . Maschmedt to Water Quality Control ........ . ... . . and D. J . Chittleborough Disinfection of Water for Control of Amoeba . . ... . .. . . . .. ... . .. . B. S. Robinson and P . E . Christy Water Treatment for the Northern Towns of South Australia . . . . . . . . . . . . . . . . . . . . . . . R. C. Thomas No. 4 - DECEMBER Limiting Factors for Land Treatment of Cheese Factory Waste in the G. Schrale, P . C. Smith Mount Gambier Area, South Australia . .. . ..... and A. J . Emmett National Seminar - The Changing Management Needs of the Australian Water Supply and Sewerage Industry . . . .. . . .. . . ... ...... .. . . ... . .. . . .. . . Report Automatic Process Control of Large Wastewater Treatment Plants ... ..... . . . . . . . . . . . . . .. . .. K. Barr Synthetic Rubber Factory in South Africa - Effluent Treatment ... . .. . .... . .. . . . . .. . . . . I. B. Law Trends in Sewage Treatment - The Future for Victoria . . . . . . . . ... ... ... . .. . . . ..... . J. A. Crockett WATER March , 1985

23


WATER QUALITY ENHANCEMENT IN THE BURNETT RIVER M. C. Miller Water quality in the Burnett River Estuary will show dramatic improvement as a result of model studies, leading to relocation of a distillery discharge and land disposal of sugar cane plantation wastes. (pre-barrage) and verification (post-barrage) . Dissolved oxygen levels are the prime concern in the Burnett estuary (Miller 1983[a)) and the emphasis in the remainder of this paper is upon management strategies for the estuary's dissolved oxygen resources. The adopted criterion for dissolved oxygen was that levels should exceed 5 mg/ L under critical streamflow conditions as defined in the Clean Waters Act 1971-82 viz. the minimum consecutive seven days average flow with a return period of 10 years.

1. INTRODUCTION The Burnett River is located approximately 370 km north of Brisbane and has the third largest catchment of rivers on the east coast of Queensland. Water quality in the Burnett River estuary has frequently been poor and has limited the estuary's beneficial uses and numerous fish kills have occurred over the years. The Water Quality Council of Queensland, concerned about the adverse impact of the estuary's water quality on current beneficial uses and seeking to define the determinants of water quality and appropriate measures to restore it has undertaken a water quality study having three principal components: • an assessment of estuarine water quality; • development of mathematical models to quantify the various determinants of water quality; and • an investigation of alternative wastewater disposal strategies to improve existing water quality using the mathemati"cal models for the predictions. Two previous papers (Miller 1983 a, b) have reported on the first two components of the investigation, this paper describes the third.

M. C. Miller

3.1 The 1970 Representative Condition The 1970 Representative Condition is summarised by the water quality measurements from the 29th October, 1970. Steady-state conditions pertained approximately at this time as there had been no flow over Bingera Weir since April 22nd. Representative pollutant loads from the four major point source discharges are summarised in Table I, and the dissolved oxygen profile is shown in Figure 2.

2. DESCRIPTION OF STUDY AREA

3.2 The 1980 Representative Condition

The study area of the investigation, shown in Figure I, was confined to the part of the Burnett River catchment downstream of Bingera Weir which is located at AMTD* 42.4 km. This section of the river was tidal until construction of the Burnett tidal barrage at AMTD 25 .9 km in 1975-76. The barrage, with a current storage capacity of 27 000 ML, is a major element in the Bundaberg Irrigation Scheme. This scheme has been developed to ensure stability of sugar cane production in the lower Burnett region through assured supply of surface waters for irrigation. This harnessing of surface water affects the amount of freshwater flowing into the estuary and periods of up to seven months zero freshwater inflow have been recorded. The estuary receives effluent from four major discharges licensed under the Clean Waters Act 1971-82. These discharges, shown in Figure I, are the Bundaberg Distillery, Millaquin Sugar Mill and Refinery, and the Mill bank and East Bunda berg sewage treatment plants. Two new sewage treatment plants at North Bundaberg and Avoca Branyan have been commissioned recently. These plants discharge to the Burnett estuary at AMTD's 11.0 km and 22.0 km respectively and at present have only small connected populations . Other beneficial uses of the estuary include active and passive recreation, commercial fishing, navigation, drainage of urban and rural stormwater, provision of cooling water and maintenance of an estuarine ecosystem .

The 1980 Representative Condition is summarised by the water quality measurements from the 16th October 1980. Similar hydrologic conditions to those in October 1970 existed at this time and this facilitated comparisons between the two quality regimes. Representative pollutant loads from the major discharges are summarised in Table 2, and comparison with Table I indicates a significant reduction in carbonaceous BOD from the sugar mill and , refinery, the carbonaceous BOD load being reduced by 40%. The relevant DO profile is shown in Figure 2.

4. RECEIVING WATER QUALIT~ ENHANCEMENT The dissolved oxygen profiles representative of 1970 and 1980 shown in Figure 2 indicate clearly that enhancement measures were necessary to avoid continuance of reduced beneficial uses and poor water quality . Two approaches were investigated: (i) reducing pollutants discharged to the receiving water; and (ii) downstream relocation of effluent outfalls to reaches of the estuary with greater assimilative capacity. These investigations are described below together with the results of the implemented enhancement measures. TABLE 1. REPRESENTATIVE DATA ON POINT SOURCE DISCHARGES TO THE BURNETT RIVER IN OCTOBER, 1970 Discharge Data

3. ESTUARINE WATER QUALITY REGIMES Water quality has been monitored in the Burnett River since 1966 and with this data it was possible to examine changes in receiving water quality over time, for example, due to changes in pollutant loads discharged and tidal flows. Two water quality states provide a good basis for illustrating the receiving water ,quality changes that have occurred over time and for comparison with predicted water quality following implementation of water quality enhancement measures . These two regimes are described briefly below as the 1970 and 1980 Representative Conditions. Both are representative of steady-state conditions for zero freshwater inflow at the head of the estuary and were used in model calibration

Estimated Average Loads Source Millbank S.T.P. East Bundaberg S.T.P. Millaquin Complex Mill Refinery Waste Pond Bundaberg Distillery

Flow (m'ld)

Carbonaceous Nitrogenous BOD (kgl d) BOD (kgl d)

D.O. (kgl d)

I 590

101

288

8.7

4 500

158

514

20.3

33 ooo• II 000* 545 (net) 454

4 2 2 10

250t 450t 260't 500

0 0 0 2 076

0 0 0 0

• Returned flow i.e. no net flow contributed. Net increase in load.

t

Mathew Miller is an Executive Engineer with the Water Quality Section, Queensland Department of Local Government. 28

WATER March, 1985

• AMTD is Adopted Middle Thread Distance from the estuary mouth.


South

Ocean

Pacific

HEADS

Note Distances shown along rive r are A.M.T.D.'s

I

I

\

Elliot

-'-

4km

r---,_

Figur~ 1. Study area of investigation.

4.1 Predicted Effects of a Reduction in Pollutant Loads Discharged The pollutant loads discharged to the estuary in I 984 were almost identical to the 1980 loads summarised in Table 2. The distillery load accounts for nearly 90% of the total carbonaceous BOD load currently discharged and this was the obvious starting point in any attempts to effect significant reductions in pollutant load discharged to the estuary and thereby improve existing water quality. In any case, the other discharges were meeting their discharge licence conditions and reductions in their loads were not likely to improve significantly existing water quality. A one dimensional dynamic model was developed for this study. The calibration and verification process is described elsewhere (Miller 1983, b). The model was used to simulate changes in dissolved oxygen

Sc ale

1 : 100 000

from the 1980 Representative Condition resulting from various percentage removals of carbonaceous BOD from the distillery effluent (dunder) . The results are summarised in Figures 3 and 4. From these figures it is clear that: (i) marked improvements in minimum dissolved oxygen levels are achieved with as little as 500Jo reduction in distillery load, but to meet the desirable level of 5 mg/ L, gi'len the continuance of the other discharges at current licence conditions, discharge of dunder at the present location would have to cease. (ii) if all discharge points, except the distillery, stopped discharging effluent to the Burnett River, it would still be necessary to remove (for example by incineration, land disposal or biological treatment) 800Jo of the existing carbonaceous BOD load from the distillery to meet a 5 mg/ L dissolved oxygen criterion; and WATER March, 1985

29


13 --- - -11 11

-

·-

·-

19 80 REPRESENTATIVE

CONOlllON

1970 REPRESENTATIVE

CONDITION

4.2 Predicted Effects of Outfall Relocation

19 80 WITHOUT PRESENC E OF TIDAL BARRAGE

•• • • • • • • ••

The model was also used to predict the effects of downstream relqcation of the distillery outfall under conditions of continuous discharge and discharge for four hours on the ebb tide only. The results of these predictions .are presented in Figure 5 which shows that: (i) downstream relocation of the distillery outfall to AMTD 2.0 km for continuous discharge or AMTD 4.0 km for ebb tide discharge will result in receiving water quality which meets the adop ted criterion of 5 mg/ L. (ii) there is no significant difference between continuou s and ebb tide di scharges for o ut fall location s upstream of approximately AMTD 7 .0 km since this approximates the tidal excursion at this point.

1984 REPRESENTAT IV E CONOITION

10

z

~

,..

TIDAL BARRAG E

8

B INGERA WE1R

-- - ------ ·-- -- ~

><

0 0

~ ~

~

6

s

0

Effect of relout.on of d1st dt ery discharge

Effect of 11np l emen tation of ( t un 'w ahr s Act be t we en 1970 and 1980

10

Efftct of co nstruc ti on of t i dal barr age

12

16

H.

18

20

22

24

26

28

30

32

34

36

38

40

42

44

A .M T .O. ! KM)

Figure 2. Burnett River -

comparative DO profiles changes from 1970 to 1980.

· (iii) for the estimated ultimate population loadings at the sewage treatment plants, including the two new plants at North Bundaberg and Avoca Branyan, to achieve a minimum DO of 5 mg/ L would require improvement in the effluent quality of all discharges and significant reduction of the distillery load . Relaxation of the adopted Dissolved Oxygen criterion of 5 mg/ L would permit lesser load reductions , but such actions were not considered appropriate for this receiving water without investigation of the alternative enhancement approach, the downstream relocation of outfalls .

:; ~

Tidal B arrage

100•1. Satura t 10n ~

1--c:::...::-::- - -

- ---- ---

10

12

14

16

18

22

24

26

28

30

32

34

36

38

40

42

44

(k m)

comparative DO profiles, reduced distillery loads.

TABLE 2. DATA ON POINT SOURCE DISCHARGES TO THE BURNETT RIVER IN OCTOBER, 1980

% Oi s titl ery Lo ad Onl y

% Disti l l ery L o ad + Mi ll + Re f inery+ S.T. P.s (198 0 l

Discharge Data

% Ois t ill ery

Lo ad + Mi ll+ Ref i ne r y + S .T. P. s ( Inclu d in g Nor t h Bu n dabe r g + Av o ca Branyan ) At Ultim ate Popu l a t i on s

Estimated A verage Loads Source Millbank S.T .P . East Bundaberg S.T .P . Millaquin Complex

"'e

Mill Refinery} Bundaberg Distillery

6 6

Flow (m' l d)

Carbonaceous Nitrogenous BOD (kgl d) BOD (kg/ d)

2 100

136

8 000

200

10

ooo• 165

1 020t 10 500

431 731

D.O. (kgl d) 15.2 44.0

0

0

754

0

• Returned flo w i. e. no net flow contributed . Net increase in load .

t

:c

:::,

4.3 Adopted Enhancement Measures

:c X

""

:c

Oe f i c , t Due t o Sed i me n t Oxyg en Oema nd Onl y (Po s t - B arr a ge l

20

40

60

¾ REDUCT I ON IN

LOAD

Figure 4. Burnett River 30

20

A . H.T . 0 .

Figure 3. Burnett River -

(D Q) Q)

81ng era Weir

8

WATER March, 1985

80

CA RBONAC EOUS

100

On the basis of these predictions and of consideration of other factors including costs and problems with effluent treatability and nonestuarine disposal options, it was concluded that the optimal disposal strategy was a combination of land disposal on sugar cane plantations, wherever practicable, and estuarine disposal through a relocated distillery outfall at AMTD 4.3 km , with ebb tide release of the effluent . This disposal strategy was implemented in early July 1984. Because of the high strength of the dunder, a diffuser was required as part of the new outfall to achieve an initial dilution of 100 to I.

B.0.0 .

FRO M DI STILL ERY

predicted maximum DO deficits.

4.4 Receiving Water Responses Figure 6 summarises receiving water monitoring results before and after outfall relocation.


-10

I

-'

I CONTI NUOUS

a,

E

>-

"' <t ::,

Subsequently some lowering of DO levels occurred due to further intermittent discharges of dunder after the 5th June. The post-relocation data for the 10th and 17th July clearly validates model predictions. The minimum DO level observed in the estuary was 5.4 mg/ Land this was located in the vicinity of the remaining major discharges. viz the Millaquin Sugar Mill and Refinery and the East Bundaberg sewage treatment plant. The post-relocation levels observed between the new outfall and the mouth are higher than those predicted by the model because model predictions were made assuming estuarine discharge of all dunder whereas a large percentage of dunder was disposed of on land in this period. For comparative purposes, the 1984 Representative Condition is also shown in Figure 2. This predicted profile assumes estuarine discharge of all dunder under identical hydrologic conditions to the 1970 and 1980 Representative Conditions . It is apparent that relocation of the distillery outfall has made a significant contribution to water quality enhancement in the Burnett Estuary.

I

DIS CH ARGE I

a

.....

V,

u.J

6

z

--- ---w.a.11a--- --- ---¡ ---ADOPTED

----

-' u.J

c.:; 4 -' 0

OBJECTIVE

............

D

z

~

2

...............

,..............

l:

~

0 0

4

10

12

14

16

A.M.T.D. OF DISTILLERY DISCHARGE

10

I

IEBB-TIDE DIS CHARGE I a,

E 8

>-

"'::,<t ~ 6

-

z

-- ------ ---

w.a.

¡-.....----....

ADOPTED

-

u::: 4 > u.J

.......

-'

ci ci 2

OBJECT IVE

............. r--,...__ -...........

z l:

~

0 0

4

6

8

10

12

14

16

A .M.T. D. OF DISTILLERY DISCHARGE

Figure 5. Burnett River - effect of relocation downstream of distillery discharge.

~

5. DISCUSSION In this investigation, the emphasis has been upon improving the dissolved oxygen regime through control of point source discharges . The levels of nutrients, rates of primary production and the importance of non-point source pollutants have not been considered explicitly, since their importance was overshadowed by the more apparent problems with the dissolved oxygen regime . The remedial actions resulting from this study may need to be extended to include nutrient removal from discharges if problems related to this aspect become more prominent. In any case, the proposed strategies to improve the dissolved oxygen regime were the first and most important step to improving water quality in the Burnett River. The adopted strategy for water quality enhancement, which combines land disposal and estuarine disposal when land disposal is not practicable, has a number of advantages. In general estuarine disposal will only be necessary in the wet season from January to March each year. At this time the estuary's assimilative capacity will be greater due to the higher freshwater inflows, water quality should accordingly be better than that depicted in Figure 2. Another advantage of the adopted strategy will be reduced fertilizer costs for sugar cane farmers with access to the effluent.

6. CONCLUSIONS

.

The principal conclusions from this phase of the investigation were: (i) the pollutant load di scharged to the estuary in organic wastes was clearly greater than its assimilative capacity; The pre-diversion results were measured following a significant period of zero freshwater inflow but are not all indicative of the ex- (ii) because of the dominance of the organic load from the distillery, requiring higher quality effluents froJi other discharges was isting water quality regime at that time because of discontinuous unlikely to significantly improve existing water quality; disc harges of dunder. The minimum DO level recorded on the 25th (iii) water quality enhancement by reducing pollutant loads dischargMay was less than I mg/ L and was located adjacent to the distillery ed to the estuary was not a feasible strategy; discharge . Discharge of dunder was temporarily stopped on that day (iv) investigations into alternative measures to enhance existing water to allow DO levels to recover, so that by the 5th June, a minimum quality , using mathematical models, indicated that downstream level of 3 mg/ L existed in the estuary. relocation of the major point source discharge from the Bundaberg Distillery would result in - 11 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - , achievement of a 5 mg/ L minimum dissolved oxygen criterion; BURNETT TIDAL BARRAGE -' 10 Before Outfall Relocation (v) the appropriate effluent disposal "'E to AMTO 4 . 3 km strategy for the distillery discharge is a z 0 25 5 . 84 (Mi(la q uinl combination of land disposal with u.J CJ estuarine disposal when land disposal is 5 . 6 .84 >x not practicable. 0 21 . 6 84 Following adoption of the new effluent 0 u.J disposal strategy receiving water quality as > _, reflected by dissolved oxygen levels , has imAfter Outfal l Relocation 0 V) to AMTO 4. 3 km V) proved dramatically and levels now exceed 5 0 mg/ L throughout the estuary . 10 . 7. 8 4 ( L WI 17 .7 .84 ( HW I

8. ACKNOWLEDGEMENT 0 .___,____._ _.__.__.,___.___._....____.__ _.__..__.,___,___._....____.__.,___,__~__..____._ _.___, 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 0

The permission of Mr. H. F. Desmond, Director of Water Quality, to publish this paper is gratefully acknowledged.

AMTD ( km )

Figure 6. Burnett River - comparative DO profiles 1984. Relocation of distillery effluent discharge from AMTD 16.0 to AMTD 4.3.

REFERENCES-SEE PA GE 3 7 WATER March, 1985

31


The Mandalay Water Supply Project R. M. Lehmann Mandalay, capital of Burma, now with a deficient water supply system will, within three years, be fully reticulated and have augmented supply from underground sources. R. M. Lehmann

SUMMARY The present water supply scheme of the City of Mandalay in Burma is inadequate and services portion only of the city. The existing supply is untreated and distributed via open wells and in many cases badly corroded pipework. Water related diseases are prevalent and in the last five years the city has suffered two major fire outbreaks which have raged unchecked as a result of an inadequate fire fighting supply. The projected water supply scheme when complete will provide a significant improvement in water supply service to the whole of Mandalay city. The project was commenced in September 1983 and predesign work is currently underway. An immediate improvement programme has also been implemented and tenders are about to be called for a number of items of equipment to enable upgrading of the existing system. Completion of the project is scheduled for 1988.

INTRODUCTION The Mandalay Water Supply Project involves the provision of a water supply service to the City of Mandalay, the second largest city in Burma with a present population of 512 000 persons of whom some 400Jo are currently served by a reticulated water supply service. Design of the new water supply scheme is being carried out by three Australian Consultants in collaboration: Coffey & Partners Pty Ltd, Sinclair Knight & Partners Pty Ltd and Scott & Furphy Engineers Pty Ltd. This joint association is referred to as the 'Consultant' in this paper. The scheme will involve the construction of 20 tubewells, two large reservoirs, two elevated reservoirs, a booster pumping station and over 300 km of pipework at a total estimated cost of US$33 million.

MANDALAY CITY The city is located on the banks of the Irrawaddy River, approximately 620 km north of the capital Rangoon (Figure 1) , and is about 80 metres above sea level and generally flat except for Mandalay Hill which rises 236 metres above the surrounding countryside. The city is rural in character, with very few buildings above three storeys in height, most are of one or two storeys and of timber, bamboo and thatch or brick construction. The city is built around the Royal Palace which was constructed in the mid 1800s and is surrounded by a moat, currently a source of water for part of the city. It is estimated that the present population of 512 000 persons will increase to 760 000 by the year 2000. Over recent years the city has experienced two major fires. An outbreak in 1981 is reputed to have destroyed 6000 houses, while in 1984 a fire destroyed an estimated 4000 houses. As a result of these two fires the authorities have expressed considerable concern about the need for the new water supply system to provide a continuous and adequate water supply during a fire emergency .

THE EXISTING SCHEME The existing public water supply scheme supplies only a portion of Mandalay's population via two systems; the moat system which supplies water by gravity pipe flow and the tubewell system consisting of a number of tubewells pumping into elevated tanks, either directly or via a booster pump. From the tanks water is gravitated by pipe lines. The total population served by the two systems has been estimated as 185 000 persons. The palace moat system has a capacity of approximately 1600 ML and is fed, via irrigation channels which carry water from the Chaung Magyi River diverted some 37 km to the north-north-east of Mandalay.

Roderick Lehmann is an Associate Director with Consultants Sinclair Knight and Partners Pty Ltd, in Brisbane, Queensland. 34 WATER March, 1985

Figure 1. Locality plan.

A dam is now under construction approximately 3 km upstream of the weir. No accurate estimate of yield is available for the moat supply system but it is probably of the order of 5 ML/d. The tubewell system consists of nine active tubewells which provide an intermittent supply utilising air lift pumps . The pumps are of low efficiency and cause rapid pressure fluctuations in the wells leading to the pumping of sand with consequent degradation of the well. The estimated yield of the tubewell system is approximately 2.5 ML/d. The existing pipe distribution system consists of 80 km of cast iron and steel mains of which a considerable length is thought to be highly corroded and unsuitable for incorporation into a new 'pressure' system. Service tappings have generally been made in galvanised iron pipe and are in many cases badly corroded and would be unable to withstand any significant pressure. As a consequence, it is considered that it 'would be undesirable to utilise the existing pipework in a new 'high pressure' system. In addition to the abovementioned public water supply system there are some 1500 private wells throughout the city. Part of the consultants' brief was to provide an upgrading of the supply capacity of existing works which has involved a detailed review of existing tubewells, tanks, pipes and valves. A large number of ex-


isting leakage points have been identified and a repair programme has been initiated. In addition it is proposed to redevelop a number of tubewells, install several new wells and install new vertical turbine pumps and screens to increase the available supply from the well" system to about 9 ML/ d. A leakage detection programme was proposed for the pipe system, but following the fire of March, 1984, significant further damage occurred to the system and service connections with reduction in the extent of practicable rehabilitation work .

TABLE 3. DESIGN DEMANDS (iq3 / d) Demand Average Day Demand Maximum Day Demand Peak Hour Demand

Area Special High Risk Area High Risk Area Other

POPULATION AND WATER DEMANDS It has been estimated the population of Mandalay will increase to 620 000 persons by 1993 and to 760 000 by the year 2000. The city is divided into four townships and 56 wards and population estimates were prepared for each ward and used as the basis for forecasting water demands which have been estimated for the following classes of consumption: domestic • public tap • garden service (single tap in garden) • fully plumbed service • industrial and institutional • unaccounted for water. Estimates for population served by the public tap, garden service and fully plumbed service have been made from an assessment of the socio-economic level of each ward. - 'Mandalay Water Supply .Feasibility Studies Final Report for Asian Development Bank with UNDP by C. Lotti & Associati.' This has been done by reviewing the average tax paid in each ward, the town planning policy and the average value of new houses constructed in each ward. Each ward has been assessed to have low (L), medium (M), or high (H) socioeconomic level, which may change with time. Table 1 gives the percentage of population served by each type of service for each socioeconomic level. The water demand for each type of service has been calculated using the criteria shown in Table 2. TABLE 1. TYPE OF SERVICE AS PERCENTAGE OF POPULATION SERVED STAGE 1 Year 1993 Socio-Economic Level

Public Tap

Garden

L M

60 40 10

36 51 63

H

STAGE 2 Year 2000 Full Public Plumbed Tap

Garden

Fu lly Plumbed

40 20

51

9

9

64

27

5

57

16 38

4

STAGE 2 Year 2000

83 000 109 000 144 000

125 000 165 000 220 000

Fire Flow (L i s) 480 240 80

dalay are shown in Table 3. For assessment of fire demands, mains have been sized so as to prevent drawdown of residual head in the system below 3 metres under fire flow and during peak hour demand. Fire flow has been assessed according to risk areas as follows: Special high risk areas include mainly the commercial, the more densely populated and the high risk industrial areas . The high risk areas include the more densely populated areas.

THE NEW WATER SOURCE A number of investigations have been carried out by various consultants over the years to determine a suitable source of water supply for Mandalay. Early investigations discounted groundwater as source, because of its hardness, in favour of surface sources. During the feasibility study for the water supply scheme, the Italian Consultant, C. Lotti & Associati, recommended that the supply to the city initially be obtained from groundwater. A hydrogeological investigation of the groundwater system indicated that adequate quantities of good quality water would be available from aquifiers below the left bank of the Irrawaddy River and within the city area. Two aquifiers were identified; an upper and a lower aquifier 70 to 100 metres below the surface, separated by some 10 to 30 m thickness of clay. The upper aquifier is overlain by a clay layer of varying thickness. Further investigation work has recently been carried out by the consultants which has confirmed that adequate quantities of groundwater are available to meet design demands up to the year 1993 and probably to the year 2000. It is proposed to tap the lower aquifier because it offers generally a lower hardness (less than 100 mg/ L CaCo3 hardness) and because there is less likelihood of contamination from surface pollutants. It is expected that the water will be of good quality and only require treatment by chlorination which will be by chlorine gas.

THE PROPOSED SCHEME

TABLE 2. A VERA GE DAY DEMAND (Lpcd) Type of Service

STAGE 1 Year 1993

STAGE 2 Year 2000

Public Tap Garden Service

45 L 100 M 120 H 130 180

45 115 135 145 190

Fully Plumbed Service

STAGE 1 Year 1993

The consultant has considered the impact on the proposed scheme of increasing the average day demand for public taps from 45 Lpcd to 60 Lpcd at 1993 and 90 Lpcd at 2000. The review was requested by the authorities following a review of existing water usage patterns at public wells. Industrial and institutional demands have been assessed from actual demands or where no information is available, on an area basis. Unaccounted for water has been assessed as 25% of the total daily demand . Estimates of existing leakage indicate values significantly higher then 25%, however, it is considered that the completion of the new works , and the disuse of the existing system will enable this target to be achieved. Maximum day demands have been calculated assuming a peaking factor of 1.33 for domestic and industrial and institutional demands (applied to average day demand). Peak hour demands have been calculated assuming a peaking factor of 2.0 for domestic demands and 1.33 for industrial and institutional demands (applied to average day demand). Based on the above criteria the total estimated demands for Man-

General The proposed water supply scheme will draw water from 20 tubewells to a depth of some 130 m , adjacent to the Irrawaddy River. These will deliver water to a 25 ML raw water reservoir located adjacent to a booster pumping station. The water will be chlorinated prior to entering the storage. The booster pumping station will be the main source of supply to the distribution system and will deliver approximately 90 per cent of the total demand under peak hour conditions. A balancing reservoir on Mandalay Hill will provide some reserve storage for the system for fire demand and in the event of pump shutdown or failure. It is proposed this reservoir be 25 ML capacity, providing a reserve storage of 22 per cent of the 1993 maximum day demand. In addition to the Mandalay Hill reservoir, two small elevated reservoirs will be provided in the southern areas of the city to minimise pressure variations in these areas. Residual pressures in the system will vary from 10 m to 45 m. Major supply and distribution mains will provide a supply to the whole of the city area. An important feature considered in the design of the new works is standardisation and duplication of components. Wherever possible, variations in capacity, size, etc . have been minimised and multiple units provided to enable back up facilities in the event of failure of one unit, and reduction in spare parts requirements. In their preliminary investigations for the Feasibility Studies, Lotti reviewed various alternative schemes involving both pumping systems and gravity systems. Economic comparisons of the alternative systems indicated the pumping system to be the more economic, probably asresult of the location of the only suitable site for a reservoir, viz WATER March, 1985

35


Mandalay Hill, being on the northern extremity of the city. A gravity supply from this site, would require large pipe sizes to ensure an adequate supply to the southern extremities. The pumping system offered the advantage of the pumping station being located near the centroid of demand.

similar. All reservoirs will be roofed. The reinforced concrete reservoirs will be rectangular in shape with cantilever wl'tlls. The 25 ML raw water reservoir will be constructed with a dividing wall to enable one section to be taken out of service for maintenance without disrupting the supply. All reservoirs will be designed for seismic loadings .

Tubewells

DISTRIBUTION

The tubewells will be distributed over a length of 3.5 km along the Irawaddy River and just to the east of the bund wall on the western side of the city. The wells will have 400 mm casing for the upper 35 m with 300 mm casing below. A 300 mm stainless steel screen will be located at the lower aquifer level. In Stage I of the project, 20 identical tubewell pumps will be provided, three of these being standby. The pumps will be multistage vertical water lubricated turbine units. All will normally be electrically driven but 10 will be provided with electrical-diesel dual drives permitting diesel operation during periods of no power. The pumps will be specified for Stage 2 duty 96 Lis and 53 m head with the requirement that Stage I duty (75 Lis to 41 m head) can be met by the removal of the top impeller. They will operate over a range of duty points depending on the pipeline characteristics, an adjustable rate of flow valve will be provided for each pump to limit the maximum delivery from any one pump to 120 Lis . This'will be necessary in the event of pump drawdown being less than anticipated, or when only one or two pumps are operating and the frictional head loss in the transmission main is very small .

The distribution system will service the whole of the city area, and supply the reservoirs. Main sizes will vary from 100 mm to 900 mm. The total length of mains to be provided exceeds 300 km. Mains will be ductile iron or mild steel. It is estimated that 40 000 service connections will be required which will probably be made using tapping bands although the possibility of direct tappings was still under investigation at the time of writing this paper. Tappings of mains larger than 300 mm will not be permitted. Polyethylene pipe will be used for service pipes. All properties will be metered and tenders will be invited for both multi jet and positive displacement meters but, multi jet meters will probably be used because of their lower cost. In the poorer areas where a large proportion of the population will not be able to afford a private connection, public taps will be provided consisting of a series of taps attached to a brick superstructure supported on a concrete slab.

Booster Pumps The booster pumps will be located in a pumping station building adjacent to the raw water storage which will also house an operations room, switch room, water laboratory, workshops, store and office and ablution block. Four pump units will be provided at Stage I, three electrically driven and one by diesel and provision will be made for an additional three units for Stage 2, one diesel and two electric. All pumps will be identical. The diesel driven units will operate through a right angle gear drive and will be used during periods of no power. TM pumps will be vertical spindle, radially spit, single stage double suction units operating at 980 rpm. The vertical configuration was selected to minimise suction head problems and to permit motor installation above flood level. With this configuration and to place the pumps below the bottom water level in the raw water reservoir installation is in a well. Double suction type pumps were selected for ease of installation and maintenance because of better operating performance over the nominated range of flows . The duty point of the pumps will be 530 Lis at 46 m head. Four electrically driven pumps operating in parallel will achieve the Stage 2 duty point, two pumps will meet Stage I requirements . With the diesel drive units operating two units only will be required to achieve the Stage 2 duty point, as the pumps will operate at the higher speed of 1200 rpm. Figure 2 shows typical curves for the booster pumps.

Reservoirs Four reservoirs will be constructed, two of 25 ML capacity in reinforced concrete and two of 0.5 ML capacity in prefabricated steel or

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Figure 2. Booster pump cones. 36 WATER March, 1985

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Power and Controls The tubewell pumps will be driven by 380 V electric motors and the booster pumps by 11 kV. The 11 kV motors have been selected for the booster pumps to simplify cabling and reduce the need for a transformer. The electrical supply system to the booster pumping station will require upgrading and the Electric Power.Corporation (EPC) proposes an underground 33 kV supply for the major portion of the selected route. For control, a semi automatic system is proposed with operators of pumps having direct control of all pumps switching operations. Tubewell and booster pump operation will be controlled manually according to the inflow and outflow at the station and reservoir levels. The usual automatic protective devices will be provided for all pumps. A telemetry system will be installed but its main function will be to monitor performance rather than to control systems. Wherever possible, control instrumentation will be standardised .

SANITATION STUDY As part of the Consultant's brief, a Sanitation Master Plan is to be prepared . The City is presently unsewered and the disposal of sewage is by septic tanks, pit latrines and a bucke system which will be phased out as soon as possible. The one small piped sewerage system in the city services the hospital. The drainage of stormwater from Mandalay City is currently by a system of six main drains which collect water from smaller open drains constructed on either side of most roads. Many of the road drains in the commercial areas are lined but elsewhere are unlined. A number of areas within the City flood during heavy rains in the wet season. Except for a small area, the flow of main drains is to the southern boundaries. During the wet season storm water runoff is stored in Tetthe Inn until it can be released to the river when the water level falls in the dry season. Due to the impermeable nature of the surface soils and high groundwater table much of the seepage from septic tanks and pit latrines finds its way into the open drains. Preparation of the Sanitation Master Plan is now underway, however a number of elements of work have been identified as part of an overall master plan. These elements include: • improving existing drains by clearing and lining and the construction of drains where required • establishment of a public health education programme • establishment of a solid waste disposal improvement programme • development of improved standard designs for septic tanks and pit latrines and the progressive upgrading of existing facilities to improved designs • providing oxidation ponds to treat industrial discharges and drainage from major drainage areas • continuation of upgrading of the drainage system by lining drains and covering collector drains and main drains • progressively connecting septic tank effluent pipes direct to drains • ultimately constructing a piped sewerage system


The ultimate achievement of a piped sewerage system may take many years but the Master Plan will set out the progressive staging of work necessary to achieve that goal.

R. A. CRASWELL, R. SADLER & G. Jt. SHAW CONTINUED FROM PAGE 23

PROJECT MANAGEMENT Management of the project is being handled by the Project Management Office (PMO) which has been drawn from various government departments but principally from the Mandalay City Development Committee (MCDC) . The PMO has overall responsibility for the completion of the project and the setting up of a suitable management structure for the long term administration of the scheme. The Consultant reports directly to the PMO on all aspects of the scheme. The Consultant's responsibilities for the project include: • preparation of designs and supervision of immediate improvement works • preparation of designs for all civil, mechanical and electrical works • preparation of procurement schedule, detail bid documents and specifications for materials and equipment and assisting in evaluation of bid documents and awarding of contracts • assistance in the supervision of construction work • supervision of mechanical and electrical contracts The structural design of buildings and reinforced concrete structures will be carried out by Construction Corporation . In order to assist the Consultant in the execution of his work and to _provide training to local engineers/technicians a number of counterpart staff have been assigned to the Consultant .

CONSTRUCTION WORK Construction work has been scheduled to span a three year period, 1985 to 1987. Construction work will be carried out by the Construction Corporation but contracts will be called for supply of various items including : drilling rig; construction equipment; pipes, valves and fittings; water meters; pumps and associated pipework and valves and electrical equipment; prefabricated steelwork for elevated reservoirs, booster pumping station building and other miscellaneous structures. Procurement procedures will follow ADB guidelines and because of the value of contract packages, most tenders will be called by international competitive bidding . Only a few items, eg leakage detection equipment and excavation equipment, are expected to be purchased under international shopping procedures.

FINANCIAL ASPECTS The total budget for the project approximates US$33 m which includes some US$22 m foreign exchange purchases. Funding for the project is: from the Asian Development Bank US$15 m, the OPEC Fund US$7 m, with the remainder being funded by the National Bank. The conditions of the ADB loan require that the project be financially viable. Economic studies by Lotti have shown that the project is financially viable with the recommended tariff structure shown in Table 4, that is, it will meet operating expenses and pay the debt services and, at the end of the design period have a cash balance permitting further upgrading of the system. TABLE 4. SUGGESTED TARIFFS Service Public taps Domestic-Garden Connection -Fully Plumbed

US$ Per 1000 Cubic Metres 1993

2000

41.25 81.25 121.25

91.25 182.50 273.75

The recommended tariff structure will involve a family allocating only 2 to 3 per cent of its total income to meet water cltarges. Water charges will be calculated on a water use basis and consequently meters will be installed for all consumers . Charges for puQtic taps have yet to be decided but will probably be property based or ori a minimum assumed consumption level.

ACKNOWLEDGEMENT This project is the outcome of a joint effort by engineers and technical officers of the three Consultants to whom the author expresses his appreciation. Special thanks are offered to the Team Leader for the project, Mr. John Gildea for his assistance and to the Mandalay City Development Committee Project Management Team which is working closely with the Consultant on the project.

REFERENCES A. S. 1719- 1981. Recommended Common Names for Pesticides . Standards Association of Australia . A. S. 2031-1978 . Selection of Containers and Preservation of Water Samples for Chemical and Microbiological Analysis. Part I -Chemical Standards Association of Australia. BRIDGES, W. R., KALLMAN, B. J. and ANDREWS, A . K. (1963). Persistence of DDT and its metabolites in a farm pond. Trans. Am. Fish Soc. 92 421-427 . BROWN, A . W. A. (1978). 'Ecology of Pesticides' John Wiley & Sons, New York . CROKER, R. A ., and WILSON , A . J . (1965) . Kinetics and Effects of DDT in a tidal marsh ditch . Trans. Am. Fish. Soc. 94 152-159. HILL, D. W . and McCARTY, P . L. (1967). Anaerobic degradation of selected chlorinated hydrocarbon pesticides. Jour. Water Poll. Cont. Fed. 39 1259-1277. HURLBERT, S. H ., MULLA, M. S. , KEITH, J. 0 . , WESTLAKE, W. E. and DUESCH, M. E. (1970) . Biological effects and persistence of dursban in freshwater ponds. Jour. Econ. Entomol. 63 43-52. HURWOOD (1973). Report on a monitoring programme of DDT contamination in a Brisbane watercourse. I. S. Hurwood, Department of Primary Industries. Unpublished. PUMICESTONE PASSAGE STUDY (1982). Pumicestone Passage Water Quality and Land Use Study Volume 2 - Water Quality and Circulation in the Passage . Report of the Inter-Departmental Committee, April, I 982. RICHARDSON, E. M. and EPSTEIN, E. (1971) . Retention of three insecticides on different soil particles suspended in water. Proc. Soil. Sci. m. 35 884-887.

M. C. MILLER CONTINUED FROM PAGE 31 7. REFERENCES MILLER, M . C. (1983, a) . Water quality of the Lower Burnett River - a case study of the effects of a tidal barrage of estuarine water quality. Water Research Foundation of Australia August 1983 Symposium 'Water Resources of the Burnett Region 1967 to 1983 and Beyond', p. 148. ' MILLER, M. C. (1983, b). The effects of a tidal barrage on estuarine water quality. Hydrology and Water Resources Symposium Hobart, 1983. Institution of Engineers Australia.

AUSTRALIAN WATER & WASTEWATER ASSOCIATION

MEMBERSHIP Membership is in four categories: qualifications suitable for • Member membership in the Inst. of Engineers (Aust.) or other suitable professional bodies ($25 p.a.). • Associates - experience in the water and/or wastewater industry ($25 p.a.). • Student ($5 p.a.). • Sustaining Member - an organisation involved in the Industry wishing to sustain activities of the Association ($100 p.a. plus State levies where applicable). Application forms and further Information are available from Branch Secretaries, see page 1. WATER March, 1985

37

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Water Journal March 1985  

Water Journal March 1985