Conference Papers | 2000 Conference Papers
BASED RECLAIMED WATER RE-USE - ISSUES AND CHALLENGES
EXPERIENCED AT TATURA
Vanessa Hebard Environmental
Goulburn Valley Water
Gavan Keir Wastewater
Treatment Plant Supervisor,
Goulburn Valley Water
early 1994, the newly formed Goulburn Valley Water inherited
Tatura's sewerage reticulation system and wastewater
treatment plant (WWTP). The extremely poor condition
of the sewerage system, and the insufficient treatment
of waste by the WWTP instigated a seven million dollar
the commissioning of the upgrade in October 1999, emergency
discharges to Mosquito Depression were often required
due to both insufficient irrigation area and winter
storage. The upgrade was aimed at enabling zero discharge
from the WWTP through the construction of a winter storage,
and increased land for irrigation.
challenge adopted by the Authority was to provide a
long-term means of managing a wastewater load equivalent
to a city of 200,000 people, in an environmentally sustainable
way. This challenge involved developing treatment technologies
appropriate to high strength waste, implementing appropriate
trade waste agreements and initiating long-term reclaimed
water reuse agreements with farmers adjacent to the
waste management facility.
paper discusses the operational problems experienced,
and issues confronted by the Authority in the development
and management of long term wastewater re-use practices.
zero discharge, trade waste, wastewater treatment, high
rate anaerobic lagoon, third party wastewater re-user,
Tatura WWTP is located in the Goulburn Valley 20 kilometres
west of Shepparton. Tatura is in an irrigation region
where water is supplied from the Goulburn River through
a channel system to many fruit and tomato growers, and
dairy and beef farms. The network of industries in the
Goulburn Broken Catchment are recognised as one of the
nations "food bowl" centres, providing some 25% of Victoria's
rural output. These primary producers supply three major
industries in Tatura including Tatura Milk Industries,
Unilever (Rosella) and Snow Brand.
the economic benefits have provided substantial value
to the region, it has also caused detrimental effects
on our environment. Rivers were regulated to provide
water for irrigation, trees were cleared for agricultural
production, and floodplains were used as drains. This
has consequently contributed to rising groundwater tables,
salinity problems and accelerated eutrophication of
Tatura Wastewater Treatment Plant
Rodney Water Board and Shepparton Water Board amalgamated
in 1994, the newly formed Goulburn Valley Water took
ownership of the rundown and undersized Tatura treatment
complex. Since that time, significant improvements in
the wastewater treatment and disposal systems have taken
Tatura WWTP provides wastewater treatment services for
the urban and industrial areas of Tatura. The local
community comprises around 3,000 people, but due to
industry, the waste load treated at the Tatura WWTP
is equivalent to that produced from a residential population
of 200,000 people. The hydraulic load on the WWTP is
approximately 1200 megalitres (ML) of wastewater annually,
of which 70% is derived from industry and 30% from domestic
1: Site Layout of Tatura Wastewater Treatment Complex
quality and treatment
Originally, the Tatura WWTP was designed to treat a
much smaller hydraulic load. The plant was originally
configured as an aerated lagoon system, followed by
evaporation lagoons. Over the years as the town's industries
expanded, it became evident that the plant did not have
sufficient capacity to treat or dispose of the wastewater.
The Plant became massively overloaded causing poor treatment
of waste and constant generation of foul odours (principally
quality from industry had also been poor, causing corrosion
and deterioration of sewage pumps and associated works
in the wastewater conveyance system.
Offsite discharges to the Mosquito Depression during
winter were often required due to insufficient winter
storage capacity. In extremely wet years, temporary
storage capacity was made through the construction of
a bund around a treelot where the wastewater would be
stored before ultimately being discharged to the drain.
This method of disposal is unacceptable, especially
when watertable levels in the region are already high.
drain used during discharges flows through the township
of Tatura. The outlet of this drain enters the Mosquito
Depression, which eventually ends up in the Murray River.
This method of discharge presented a very poor and undesirable
visual image to the public.
quality and treatment
The Plant upgrade aimed at providing a long term, cost
effective means of treating the waste. The three aerated
lagoons that previously provided primary treatment were
covered with a reinforced poly propylene (RPP) cover
and converted to High Rate Anaerobic Lagoon (HRAL) reactors.
The HRAL's trap the gas under the covers and transport
it via a pipe system to a flare where it is burnt (and
the gas is converted from methane to carbon dioxide,
reducing greenhouse emissions). This has eliminated
bad odour problems, whilst potential also exists for
co-generation of electricity using this gas from the
the aerators which were originally located on the primary
lagoons, were relocated to the lagoons immediately downstream
of the HRAL's. This was to assist in the conversion
of effluent from the HRAL's to an aerobic state as quickly
as possible and avoid odour generation from this now
facultative area. An additional facultative lagoon was
built and provision made for future installation of
an aerator. Effluent distribution can now be achieved
via two alternative routes (refer to figure 1). Firstly,
effluent can proceed from the HRAL's to the aerated
lagoons, to the new facultative lagoon then to lagoon
18. The second option allows waste to pass through the
HRAL's, to the aerated lagoons and via lagoons 7, 8,
9, 17 and 18 before it is used for irrigation.
HRAL's have provided more than 90% removal of Chemical
Oxygen Demand (COD) from the raw waste, despite increases
in organic loading from industry. This efficiency means
that the aerators have been rarely required, providing
significant savings in power consumption. This has allowed
for a vast improvement in water quality in the final
irrigation storage lagoon.
March 1994, the Authority has been working with Industry
to improve the standard of trade waste discharges. This
has resulted in the application of new Trade Waste Agreements
for the two major industries in town. To assist each
company, Goulburn Valley Water offered to part fund
(50%) the cost of a waste management audit of each industry.
These independent audits have assisted industry to minimise
generation of waste, and will provide pre-treatment
of the residual waste.
Authority will also be extending their charging parameters
for major trade waste companies and will now incorporate
charges for total nitrogen, total phosphorus, sodium
and organic loadings. Reducing salt loads entering the
plant is aimed at assisting the sustainability of irrigation
With an increasing focus by Regulatory Authorities such
as the Environment Protection Authority and the Murray
Darling Basin Commission on reducing discharges to surface
waters, the Authority gave preference to a move to 100%
1998, a 360 ML winter storage lagoon was built and 100
hectares of land was acquired and developed for irrigation.
This increased the irrigation area to approximately
120 hectares which includes the existing 20 ha of treelots.
Conductivity (EC) levels in the final effluent were
relatively high after the construction of the winter
storage and were predicted to increase from around 2,500S/cm
to 3,500S/cm. EPA guidelines suggest that reclaimed
water of this nature could cause significant risk to
the environment and/or the crop being grown. To achieve
a sustainable outcome, the Authority needed to shandy
the wastewater with channel water to achieve an EC of
no more than 1000 S/cm (preferably 800 S/cm).
effluent quality during the 1999/2000 irrigation season
averaged 3,000 S/cm. The dilution required to reduce
salt loads to acceptable levels would mean that a shandy
ratio of approximately 1:3 (1 part wastewater to 3 parts
channel water, assuming that channel water averages
approximately 200 S/cm) would be required. High salt
levels consequently increased the total volume of water
to be managed by the Authority which led to the development
of long-term reclaimed water re-use agreements with
four dairy farmers adjacent to the waste management
the farmers to have enough water for shandying, Goulburn
Valley Water provides each farmer with a Bulk Water
Entitlement of Goulburn Murray Water (channel water)
equal to the quantities of reclaimed water taken, which
effectively increases the farmer's water rights.
Management and sustainability issues
Third party wastewater re-use
To use the reclaimed water for irrigation on dairy farms
required approval from EPA, Victorian Dairy Industry
Authority (VDIA) and Tatura Milk Industries and each
of these bodies provided the Authority with specific
requirements to be met for the project to proceed. Individual
site management plans were developed for each dairy
farm to ensure that the requirements specified above
were met. These site management plans consisted of detailed
descriptions of the site (the location of each farm,
farm layout, soil type, groundwater status), reclaimed
water quality, land use practices, on-farm water management
(eg annual water usage, farm storage availability and
drainage details), current soil status, management skills
required and environmental monitoring responsibilities.
Consultations with the farmers allowed all of the information
to be collated, and submitted to EPA for approval.
addition, the VDIA had requirements for reclaimed water
use on dairy farms, which complimented EPA requirements.
The VDIA based their program on the principles of Hazard
Analysis Critical Control Point (HACCP), to ensure that
reclaimed water users do not affect food safety, in
so far as milk and dairy products are concerned. To
satisfy the VDIA requirements, annual on-site farm audits
will take place to make sure that specific farm records
and farm management practices are being adhered to.
of such requirements include:
must not be allowed to graze for 5 days on pasture
following irrigation with reclaimed water.
water is not allowed to be used to supply stock drinking
troughs, or used in milking sheds or for equipment
is required around farm storages/channels where reclaimed
water is being used
E.coli levels exceed a median of 1,000orgs/100ml,
or a notification level of 5,000orgs/100ml, the use
of reclaimed water is to cease until levels improve.
E.coli levels be between 1000orgs/100ml and 5,000orgs/100ml
then farmers are to increase their stock withholding
to 20 days rather than 5 days.
High groundwater tables are a local problem in the Shepparton
Irrigation Region (SIR). Groundwater levels at Tatura
WWTP and surrounding properties are approximately 1
to 2 metres below the natural surface and range between
2,000 and 9,000S/cm, effecting some existing tree plantations.
To minimise the effect that the Tatura WWTP may have
on the groundwater, the Authority installed a groundwater
interception scheme on the southeastern corner of the
plant. Any water collected is pumped back into the evaporation
lagoons (lagoon numbers 10,11,12 and 13).
extensive network of groundwater monitoring bores was
also installed at the time of the upgrade. Monitoring
for potential contaminants, salt and groundwater level
is now part of the Authority's environmental management
addition, 8,000 native trees and shrubs were planted
at the completion of the upgrade. It is anticipated
that they will act as a windbreak, and as natural groundwater
pumps (providing they are not effected by saline groundwater).
and sodicity of soil
The constituents of wastewater that can threaten sustainability
are pathogens, heavy metals, toxic organic substances,
boron, sodium, nutrients (particularly nitrogen and
phosphorus) and salts. From these the last three provide
the greatest potential limits to sustaining wastewater
irrigation. The rest pose few problems for wastewater
in the Goulburn Valley. Irrigation that moves beyond
the rootzone can add to groundwater and induce salinity
and water logging (Surapaneni et al 1998).
research trials at Shepparton and Mooroopna WWTP's,
Goulburn Valley Water has recognised that wastewater
irrigation can lead to soil degradation via salinity,
sodicity and water logging. Annual soil monitoring on
all properties irrigated with reclaimed water is now
part of the Authority's routine monitoring. Baseline
soil samples that were taken before reclaimed water
was used for irrigation suggest that some of the soil
by Australian definition is already sodic (Exchangeable
Sodium Percentage, ESP>6). Likewise, some soil electrical
conductivity results exhibited levels of >0.16dS/m (soils
with <0.16dS/m are defined as low in salinity). Careful
long-term monitoring and management by the Authority
will be crucial.
show that applications of Gypsum improve internal drainage
by offsetting the increasing sodicity in the soil. This
was assessed at the initial baseline sampling and will
be assessed at each subsequent sampling period, to determine
are issues associated with farms under continuous cultivation
and increased soil sodicity. The combination of sodic
irrigation water and cultivation may create hard-setting,
impermeable soils. Care will have to be taken to ensure
that reclaimed water re-use does not increase soil sodicity.
Any changes in soil characteristics will be detected
through annual soil sampling and managed appropriately.
As the reclaimed water is diluted to a ratio of 1:3,
nutrient loading on the site is not likely to be an
issue, in fact, additional nutrients will need to be
added to maintain plant requirements. Table 1 presents
nutrient loads (in kilograms) to land during the 1999/2000
on average wastewater quality data for Total Nitrogen
and Total Phosphorus, shandied levels reduce nutrient
concentrations to 8mg/l and 3mg/l respectively. If farmers
were irrigating paddocks at 8ML/ha/yr, calculations
indicate that loads would equal 64kgN/ha/yr and 24kgP/ha/yr.
Rye/Clover pastures have requirements of 220kgN/ha/yr
salt and nutrient loads in Table 1 were calculated utilising
monthly irrigation volumes and monthly nutrient concentrations
of the final effluent quality. Due to commissioning
delays last season, it is expected that the volume of
reclaimed water used, and the area of land irrigated
will increase next irrigation season.
1: Total Salt and nutrient loads (kg) to land - 1999/2000
Environmental monitoring responsibilities
At Tatura WWTP, comprehensive wastewater tests are completed
monthly, and during irrigation both E.coli (bacteria)
and field tests are performed weekly. It is the responsibility
of the Authority to cease supply of irrigation water
if E.coli levels exceed regulatory limits.
water users must also keep records of the Electrical
Conductivity of the water they have applied during each
irrigation (shandied EC value) dates irrigated, areas
irrigated and dates stock were put back on irrigated
described, annual soil monitoring and a coordinated
groundwater monitoring program is underway.
The Authority anticipated operational problems on commissioning
the WWTP's irrigation system. In most cases the problems
were minor and could be overcome by operational staff.
It is not expected that the problems experienced will
persist in further irrigation seasons.
enable zero discharge to surface waters from the WWTP,
Goulburn Valley Water now rely on formal agreements
between four off-site users to use their allocated amount
of reclaimed water annually. Despite the variations
in seasons, each third party re-user must take their
annual allocation so that lagoon storages can run at
to the agreement were made in the first irrigation season
(1999/2000) because the upgrade was still in the final
stages. The Authority had problems installing pumps
and pipe work, hence a late start to the season was
made. Table 2 emphasizes the shortfall in water usage
by the dairy farmers.
2 : Reclaimed water re-users allocations and the amount
of reclaimed water used in the 1999/2000 irrigation
Lagoon water balance models indicate that there will
be enough storage capacity to cater for the additional
water over the forthcoming winter period. Operational
problems may still arise in late winter however, if
heavy rains occur.
Apart from the late start to irrigation with reclaimed
water due to construction, less water than anticipated
was taken due to the dry season. The channel water allocations
to each farmer was reduced due to the low water levels
in the catchment storages meaning each farmer needed
to develop a very accurate water budget to ensure that
they did not run out of water. This conservative approach
actually reduced the volume of reclaimed water used
even though the year was so dry.
newly lasered WWTP property also utilised less reclaimed
water than anticipated. Run-off from the irrigation
bays is collected and returned to a recirculation dam
for re-use. In some instances this run-off water also
needed to be shandied with channel water for further
irrigation due to its high salt load. Consequently,
less reclaimed water was being used.
pump supplying reclaimed water for irrigation from the
winter storage was oversized and its inability to adequately
throttle the flow rate caused difficulties in shandying
to the correct ratio. To rectify this problem, a smaller
temporary pump was installed so that the correct volume
of wastewater could be delivered for mixing with channel
were also encountered with turtles being sucked into
pumps from the winter storage causing restriction of
flows and often blocking the system. If the problem
was not attended to quickly enough pumps were at risk
of being seriously damaged. All the while fresh water
was being used, exhausting the resource for shandying
farmers' experiences to date
The expansion of the WWTP, which created greater availability
of water for irrigation, came at the right time for
the four dairy farmers who have experienced three consecutive
receiving the water for the first time, farmers were
a little apprehensive towards making sure that they
could achieve the right EC mix, and that the water would
not pose a threat to their livestock. Each farmer was
issued with an EC meter and a record book for recording
their irrigations and relevant details.
farmer had some problems initially with mixing channel
water and wastewater. This was quickly overcome by mixing
the water in the farm channel (rather than the re-use
sump) like the other 3 farmers.
farmers commented on how much their pasture growth rates
improved in paddocks where reclaimed water was used,
and how much greener the pastures were.
farmers decided to laser paddocks to accommodate more
irrigation next season, which was justified by their
increase in available water, and the increased value
of the farm due to the security of water supplies.
date, the Authority has received extremely positive
feedback from all off-site re-users. Close contact is
kept with the farmers and next irrigation season they
will be more experienced with the watering operations.
newly constructed High Rate Anaerobic Lagoons (HRAL)
now provide very efficient primary treatment with the
balance of the organic load removed in the aerobic lagoons.
Effluent is stored in new irrigation storages for re-use
new winter storages eliminates the need for annual discharges
off-site to surface waters, and minimises risks of toxic
cyanobacteria blooms in our waterways. The reclaimed
water is utilised by local farmers, reducing their fresh
water and fertiliser requirements.
date, small problems with pumps and shandying on the
WWTP site have been overcome, and experience gained
from the 1999/2000 irrigation season will be employed
in subsequent irrigation seasons.
users are extremely happy with their new water supply,
and look forward to next season when they will be able
to utilise their full reclaimed water allocations. The
additional nutrient supplied in the reclaimed water
may reduce overall fertiliser needs.
issues such as salinity, sodicity and high groundwater
tables have been acknowledged by the Authority and careful
monitoring of the effects of reclaimed water on the
environment will be crucial for the long-term sustainability
of the site.
The authors wish to acknowledge Laurie Merritt, Jack
Kennedy and Werner Laing (third party re-users), George
Wall and Peter Donlon for their assistance in completing
Protection Authority (2000) Environmental guidelines
for the use of reclaimed water - Best practice environmental
management series, publication 464, Environment
Protection Authority, Melbourne, Victoria. Draft.
A, Small, DR, Donlon, PJ, Burrow, DP, and Olsson, KA
(1998) Wastewater irrigation in Goulburn Valley -
issues and challenges, Institute of Sustainable
Irrigated Agriculture, Tatura, Victoria.
Dairy Industry Authority (1999) Reclaimed water on dairy
farms - general information and requirements for users,
Victorian Dairy Industry Authority, Richmond, Melbourne