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Sydney Water Annual Report 2009
Sustainability indicators: Contributing to clean beaches, oceans, rivers and harbours
 
Improvement in water quality and ecosystem health in inland waterways and Sydney beaches.
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In this section:

 

 
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Sewage treatment system discharges
Performance: Treated wastewater discharge loads remained within system licence limits.

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Indicator: Total mass of phosphorus and nitrogen discharged to streams/rivers from inland sewage treatment plants

In 2008–09, Sydney Water’s inland sewage treatment plants (STPs) discharged 7.4 tonnes of phosphorus and 333 tonnes of nitrogen to streams and rivers in the lower Hawkesbury-Nepean catchment. These loads were within the limits permitted under licences issued by the Department of Environment, Climate Change and Water (DECCW).

Diffuse sources, such as agricultural runoff, contribute an estimated 352 tonnes of phosphorus and 2,229 tonnes of nitrogen to the lower Hawkesbury-Nepean each year. Studies indicate this may comprise 70-80% of the total phosphorus and nitrogen loads in the catchment. 1Point sources, such as inland STPs, contribute the remainder.

Sydney Water’s inland STPs provide tertiary treatment to remove phosphorus and nitrogen to very low levels. DECCW licences specify concentration limits for phosphorus, nitrogen and other pollutants (including chlorine and metals). In 2008–09, discharges from inland STPs met DECCW licence requirements for concentrations of phosphorus and nitrogen.

In 2008–09, all but two median phosphorus and nitrogen concentrations were less than 0.1 milligram a litre (mg/L) and less than 10 mg/L, respectively.

The amount of nitrogen discharged was the lowest since records began. The largest amounts of nitrogen came from Winmalee, Quakers Hill and St Marys STPs, while the largest amounts of phosphorus came from Winmalee, Penrith and Quakers Hill.

Nutrient loads are influenced by population growth, wet weather events and the treatment capacity of STPs. In wet weather, wastewater inflows can exceed the capacity of STPs and bypass some treatment processes, which is permitted under DECCW licence conditions.

Because less rain fell in 2008–09 than in recent years, stormwater flows to STPs were reduced, with a corresponding reduction in nitrogen and phosphorus loads discharged to receiving waters.

The dry weather mass of phosphorus and nitrogen discharged to inland streams and rivers has remained low since 2002–03, when Sydney Water began a major upgrade of its STPs and also started to decommission poorly performing STPs. There was a slight increase in the phosphorus load discharged to the environment during dry weather in 2008–09 compared to recent years. This increase is attributed to the important structural repairs at Winmalee STP. The work is expected to be completed in late 2010 and the STP continues to meet its DECCW licence requirements.

Sydney Water’s new Wallacia STP discharges far less phosphorus and nitrogen to the environment than the Warragamba STP, which it replaced in 2006. Wallacia STP discharged eight kilograms (kg) of phosphorus and 807 kg of nitrogen in 2008–09 compared to 292 kg a year of phosphorus and 3,815 kg a year of nitrogen from Warragamba STP. These figures represent reductions of 97% and 79% in load from this catchment respectively.

Further improvements have resulted from the pre-commissioning of the West Camden STP upgrade and the stage two amplification of Rouse Hill STP, commissioned in March 2009. Although the plants were not at full capacity for the entire year, nitrogen loads discharged from the plants fell 47% and 30% respectively and phosphorus loads fell 44% and 70% respectively compared to 2007–08.The decommissioning of Blackheath STP in June 2008 and Mount Victoria STP in August 2008 further reduced nitrogen and phosphorus loads.

The Western Sydney Replacement Flows Project, Sydney’s largest recycled water project, will also reduce nutrient loads in inland waterways. This project will connect the Penrith and Quakers Hill STPs to a new, advanced plant at St Marys where wastewater will be further treated. The highly treated recycled water will be released into the Hawkesbury-Nepean River below Penrith Weir from early 2010.

For more information on Sydney Water’s sewage treatment system licences, please see the DECCW website and public register at www.environment.nsw.gov.au/licensing/index.htm

1Department of Environment, Climate Change and Water 2009, Draft Lower Hawkesbury-Nepean Nutrient Management Strategy, Department of Environment, Climate Change and Water, Sydney, (citing Davis et al 1998).

Total mass of phosphorus discharged to streams/rivers from inland sewage treatment plants

Note: In 2008–09, Sydney Water adopted a revised methodology to improve the accuracy of dry and wet weather load calculations and amended previously reported numbers accordingly.

 

Total mass of nitrogen discharged to streams/rivers from inland sewage treatment plants

Note: In 2008–09, Sydney Water adopted a revised methodology to improve the accuracy of dry and wet weather load calculations and amended previously reported numbers accordingly.

 

Indicator: Total mass of suspended solids and grease discharged from ocean sewage treatment plants

The total mass of suspended solids discharged from ocean sewage treatment plants (STPs) in 2008–09 was 52,473 tonnes. The total amount of grease discharged was 10,368 tonnes.

Approximately 75% of Sydney’s sewage is treated at the North Head, Bondi and Malabar ocean STPs and discharged through their deepwater outfalls. These STPs contributed about 99% of the suspended solids and grease loads discharged in 2008–09. This year’s loads were well within the limits permitted under Department of Environment, Climate Change and Water (DECCW) licences, and there is no evidence of any significant environmental impacts from these discharges.

Suspended solids and grease loads discharged from ocean STPs have remained relatively constant since the late 1990s. Loads are influenced by population growth and wet weather events. High average rainfall and wet weather events in 2006–07 and 2007–08 resulted in high discharge loads. This is because wastewater inflows can exceed the capacity of STPs in wet weather and bypass some treatment processes. This is permitted under DECCW licence conditions. A decrease in average annual rainfall led to reduced loads discharged to the ocean in 2008–09.

Over the past three years, Sydney Water has focused on maintaining the performance and reliability of STPs and increasing their capacity to serve a growing population. Dry weather loads of suspended solids and grease have been maintained and show a slight decrease in recent years.

There are currently no upgrades planned to further reduce loads of suspended solids and grease discharged from ocean plants. For more information on STP upgrades, please see Sydney Water’s website www.sydneywater.com.au/MajorProjects

Total mass of suspended solids discharged to streams/rivers from ocean sewage treatment plants

Note: In 2008–09, Sydney Water adopted a revised methodology to improve the accuracy of dry and wet weather load calculations and amended previously reported numbers accordingly.

Total mass of grease discharged to streams/rivers from ocean sewage treatment plants

Note: In 2008–09, Sydney Water adopted a revised methodology to improve the accuracy of dry and wet weather load calculations and amended previously reported numbers accordingly.

 

Indicator: Total volume of controlled sewage overflows that occur in dry weather and in wet weather, expressed as a percentage of total treated wastewater discharged to the environment

In 2008–09, 462,371 million litres of effluent volume were discharged to the environment. Controlled sewage overflows in dry weather equalled less than 0.001% of the total effluent discharged and wet weather overflows equalled less than 1.1% of the total effluent discharged.

The total volume of dry weather controlled sewage overflows has remained low since 2005–06, at less than 0.001% of the total volume of sewage discharged to the environment. The total volume of wet weather controlled sewage overflows also remains low when compared to the total volume discharged to the environment. The variation in recent years is explained by the variation in rainfall from 2005–06 to 2008–09.

In 2008–09, the Wet Weather SewerFix Program focused on works in the middle Georges River, Blackwattle Bay, lower North Shore and Northern Beaches catchments. This work involves essential improvements to pipes, storage facilities and designed overflow structures. The program concentrates on areas of high environmental and recreational value in Sydney’s north, south-west and inner-west.

Sydney Water’s 2005–10 Dry Weather Choke Management Strategy continues to improve long-term system performance and reduce sewage overflows to waterways.

Total volume of controlled sewage overflows discharged to the environment

 

2005–06

2006–07

2007–08

2008–09

Total volume of dry weather controlled sewage overflows expressed as a percentage of total sewage effluent discharged to the environment

<0.001%

<0.001%

<0.001%

<0.001%

Total volume of wet weather controlled sewage overflows expressed as a percentage of total sewage effluent discharged to the environment

0.86%

6.4%

3.8%

1.1%

 

Indicator: Percentage of sewerage subsystems meeting DECCW overflows to waterways targets

Sydney Water measures the performance of its sewerage subsystems to comply with the Department of Environment, Climate Change and Water (DECCW) Pollution Reduction Program (PRP) targets. The aim is to achieve 100% compliance by 2010.

In 2008–09, 99% of sewerage subsystems met the target, an improvement on the 97% result in the previous year. Sydney Water’s 2005–10 Dry Weather Choke Management Strategy is continuing to ensure long-term system performance. In 2008–09, more than $34 million were spent on cleaning, repairing and relining wastewater pipes.

Sewers that have overflowed to waterways are inspected and repaired to minimise the risk of a repeat overflow. In areas where a sewer blockage could result in an overflow reaching a waterway, sewers are inspected and maintained and, if necessary, repaired to prevent overflows.

 

Indicator: Volume of treated wastewater discharged to the environment from inland and ocean sewage treatment plants

The volume of treated wastewater discharged to the environment from ocean and inland sewage treatment plants (STPs) in 2008–09 was 403,201 million and 59,171 million litres respectively. This volume includes flows discharged in wet and dry weather but does not include treated wastewater used in recycled water schemes. It also does not include the 2,938 million litres of treated wastewater discharged during some periods of wet weather from the three Georges River STPs. Flows from these plants are normally transferred to Malabar STP, but in extreme wet weather the storm flows discharge to inland waters.

Changes in the volumes of treated wastewater discharged to the environment from STPs predominantly reflect rainfall patterns. Stormwater runoff enters sewer pipes and increases the volume of wastewater flowing to the STPs. Less rain fell in 2008–09 than in recent years and this is reflected in the lower volume of treated wastewater discharged from STPs.

Other factors that affect the amount of water discharged from STPs are population growth, new sewerage services (such as those connected through the Priority Sewerage Program), water restrictions and Water Wise Rules, pipe repairs, the capacity of storm flow retention basins, and new recycled water schemes.

Volumes discharged to the environment in dry conditions continued to fall due to water restrictions, demand management programs such as water efficiency initiatives, and the increasing use of recycled water.

Volume of treated waste water discharged to streams/rivers from inland and ocean sewage treatment plants

Trend in annual rainfall patterns in inland and ocean sewage treatment plant catchments

Indicator: Wastewater reused or otherwise prevented from entering waterways

Wastewater from sewage treatment plants (STPs) can be recycled in residential, industrial or irrigation schemes. This is known as off-site reuse.

Treated wastewater is progressively replacing drinking water in cleaning, washing, housekeeping, cooling and other treatment processes at STPs. This is known as on-site reuse. The recycled wastewater used at STPs is not included in the reported volume of wastewater prevented from entering waterways.

About 9,893 million litres of wastewater was prevented from entering waterways in 2008–09 through off-site reuse (non-Sydney Water premises), compared to 9,246 million litres the previous year. This 7% increase was achieved mainly because stage two of the Wollongong Recycled Water Scheme came online in April 2009. The scheme supplies recycled water to the Port Kembla Coal Terminal and Wollongong Golf Club.

For more information about Sydney Water’s recycling schemes, see the Water Conservation and Recycling Implementation Report 2008–09 and www.sydneywater.com.au.

Wastewater prevented from entering waterways 2005–06 to 2008–09

 

2005–06

2006–07

2007–08

2008–09

Volume of wastewater prevented from entering waterways (million litres)

3,473

7,777

9,246

9,893

 

 

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Breaches of statutory instruments
Performance: Two Tier 3 penalty notices were issued under the Protection of the Environment Operations Act 1997 to Sydney Water and a contractor. Neither incident resulted in significant environmental harm.

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Indicator: Total number of prosecutions and notices (including penalty notices) issued to Sydney Water and its contractors under the Protection of the Environment Operations Act 1997

Sydney Water has never been convicted of a Tier 1 offence under the Protection of the Environment Operations Act 1997 (POEO Act). It has had two Tier 2 convictions, in March and July 2000.

During 2008–09, Sydney Water received one Tier 3 penalty notice (PN) under the POEO Act, and one Tier 3 PN was issued to a Sydney Water contractor.

The PN issued to Sydney Water was for a water pollution incident at Malabar sewage treatment plant (STP) on 11 June 2008. A defective valve at Malabar STP caused an uncontrolled flow of sewage sludge into the stormwater system flowing to Malabar Beach. Sydney Water has now installed monitoring devices to help prevent a similar incident reoccurring.

On 23 April 2009, Botany Council issued a Tier 3 PN to contractor Thomas & Coffey after trucks tracked spoil from construction work at the Daceyville depot onto Gardeners Road at Botany. Remediation included a street sweeper to clean up the affected part of Gardeners Road and the installation of a grate to remove spoil from trucks before they enter public roads.

Contractors are required to report penalty notices to Sydney Water staff, who enter the information into the online incident recording system. Sydney Water aims to maintain its high standard of environmental performance and avoid offences under the POEO Act through the continued implementation of its ISO 14001-certified Environmental Management System.

Total number of prosecutions and notices (including penalty notices) issued to Sydney Water under the Protection of the Environment Operations Act 1997

 

1999
–00

2000
–01

2001
–02

2002
–03

2003
–04

2004
–05

2005
–06

2006
–07

2007
–08

2008
–09

Tier 1

0

0

0

0

0

0

0

0

0

0

Tier 2

1

1

0

0

0

0

0

0

0

0

Tier 3

0

3

1

0

1

2

3

2

0

1

Note: Tier 1 offences are the most serious and include waste disposal, leaks, spills and the emission of ozone-depleting substances. Tier 2 offences are all other offences under the Act and its regulation. Tier 3 offences are those Tier 2 offences that may be dealt with by way of a penalty notice, which is an on-the-spot minor fine.

Total number of prosecutions and notices (including penalty notices) under the Protection of the Environment Operations Act 1997 issued to contractors engaged by Sydney Water

2005–06

2006–07

2007–08

2008–09

0

0

1

1

 

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Environmental performance monitoring
Performance: Long-term results show considerable improvement in water quality and ecosystem health in inland waterways and Sydney beaches.

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Indicator: Ecosystems impacted downstream of Sydney Water’s inland sewage treatment plant (STP) discharges

This indicator measures the impact of inland STPs on freshwater and estuarine environments.

Macroinvertebrate monitoring

Sydney Water monitors freshwater macroinvertebrate diversity and abundance both upstream and downstream of STP discharges. Macroinvertebrates are sampled twice each year, in autumn and spring, to monitor receiving waters in the Blue Mountains, Nepean River, South Creek, Cattai Creek, Berowra Creek and the lower Hawkesbury River.

Variable weather conditions and pollution can affect the ecosystem health of waterways. Heavy rain can wash away macroinvertebrates and drier conditions can cause creek pools to dry out. Pollution from surface runoff can compromise ecosystem health. Pollutants are carried in water from hard surfaces such as roofs, gutters, roads, paths and car parks.

In 2008–09, ecosystem health was maintained downstream of STPs for 10 out of the 12 commissioned inland STPs. West Camden STP discharges into Matahil Creek affected the localised stream health, but this impact was not evident in the Nepean River, into which Matahil Creek flows.

Similarly, discharges from Winmalee STP into a tributary of the Nepean River affected the localised ecosystem health. However, three kilometres downstream, ecosystem health had recovered to levels observed in the Nepean River.

Wastewater discharges in the Blue Mountains have improved considerably over the past 20 years. Flows from 10 STPs have been transferred to either Winmalee or Penrith STPs under Sydney Water’s Blue Mountains and Upper Blue Mountains sewerage schemes.

Wentworth Falls, North Katoomba and South Katoomba STPs were monitored for six to eight years after they were decommissioned in the mid 1990s, establishing the baseline for observed ecosystem recovery.

Monitoring in 2008–09 showed that ecosystem health in Hat Hill Creek continued to be affected after Blackheath STP was decommissioned in June 2008. In autumn 2009, the downstream ecosystem health of Hat Hill Creek had improved, but full recovery is expected to take another 12 months.

Toxicity testing

The toxicity of treated wastewater from inland STPs is tested using the sensitive indicator organism Ceriodaphnia dubia (freshwater flea). Testing began in 1998 and developed into a monthly program. The Department of Environment and Climate Change (now the Department of Environment, Climate Change and Water) included toxicity testing as a condition of inland STP licences in 2004.

In 2008–09, all inland STPs met the toxicity licence limits. In the past five years, there have been 874 toxicity tests done on effluent from inland STPs. Of these, 21 samples were positive for a potential toxicity effect.

Many of the positive tests were associated with high chlorine disinfection. Improved control measures have been introduced at the STPs, such as increased automation and online monitoring of chlorination and dechlorination.

Indicator: Ecosystem impacts of deepwater ocean discharges

Sydney Water has regularly monitored offshore marine sediments since before Sydney’s deepwater ocean outfalls were commissioned in the early 1990s. An ongoing monitoring program assesses how the deepwater ocean outfalls perform over the longer term. The program includes monitoring the toxicity of treated wastewater and the characteristics of ocean sediment. The Department of Environment, Climate Change and Water (DECCW) requires Sydney Water to carry out the tests as part of its environmental protection licences for ocean sewage treatment systems.

Ocean sediment monitoring

The Ocean Sediment Program is a three-year cyclical program that assesses the impact of discharges from the three deepwater ocean outfall STPs (Malabar, Bondi and North Head) on the marine environment.

The first year of the Ocean Sediment Program is the assessment year. Benthic macrofauna (small animals that live on the ocean floor) in sediment samples from all sites are identified and counted. The sediment quality (including metals, organic compounds, nutrients and physical parameters) is also analysed.

In the second and third years – the surveillance years – sediment samples at the Malabar deepwater ocean outfall are measured for benthic macrofauna, total organic carbon, and particle size distribution. If the results show the outfall is affecting the benthic macrofauna or sediment quality, samples are then analysed from the North Head and Bondi sites.

In the current cycle, 2008 was an assessment year. The 2008 results indicate that the deepwater ocean outfalls had no significant impact on ecosystem health.

The long-term results of the program show that the deepwater ocean outfalls are performing well and have improved the water quality at Sydney beaches.

A full interpretation of the results from the three-year cycle was reported in the 2008 Sydney Water Ocean Sediment Report to the Department of Environment and Climate Change (now DECCW) in December 2008.

Toxicity testing

Toxicity of treated wastewater from ocean STPs is tested using the sensitive indicator organism Heliocidaris tuberculata (sea urchin). DECCW sets licence limits for toxicity.

Since 2003–04, 421 toxicity tests have been conducted for ocean STPs. Of these, only seven showed a potentially toxic effect. In 2008–09, all ocean STP tests met the toxicity licence limits, with no evidence of toxicity-related effects from the treated wastewater released.

 

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Trade waste agreements
Performance: The mass of heavy metals discharged to the sewer remained within total limits specified in trade waste consents for the various catchments.

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Indicator: Total mass of heavy metals received under trade waste agreements with Sydney Water

The mass of heavy metals discharged to the sewer in 2008–09 was within total limits specified in trade waste consents for the various catchments. The discharged amounts were acceptable for the continued production of biosolids for use in agriculture, recycled water for urban and industrial reuse, and treated wastewater that meets discharge licence criteria.

Heavy metal discharges have generally decreased since 1995–96, with the exception of a temporary increase in 2005–06. This increase was due to a change in Sydney Water’s audit sampling procedure, which led to the identification of metals that were present as contaminants or minor constituents of industrial processes. Discharges from many of these processes have since been reduced.

Each year, a large number of businesses change ownership, relocate, change processes or cease trading. This changes the number of trade waste consents issued for each of the reported metals. As the Sydney region has a relatively small manufacturing base, these year-to-year changes can have a large effect on the volumes of trade wastewater and mass of metals discharged to the system. In 2007–08, the volume of trade wastewater discharged was about 16,052 million litres, compared to about 15,558 million litres in 2008–09. The lower volume was due to a reduction in the number of trade waste customers.

Heavy metals discharged to the sewer in 2008–09 showed:

  • a continued decline in cadmium and chromium discharged due to their elimination from the metal finishing industry, and removal by tanker to treatment facilities and other waste disposal sites
  • an increase in cobalt discharged, which is directly attributable to a sample from one large powder coater
  • an increase in copper discharged, largely from the electroplating industry
  • an increase in iron discharged, largely due to an increased discharge from one chemical manufacturer
  • a decrease in lead, attributable to a reduced discharge from a customer that processes wet cell batteries
  • a decrease in manganese as a result of reduced discharge from the liquid waste treatment industry
  • a decrease in mercury, attributable to reduced discharge by one large chemical manufacturer
  • a slight increase in molybdenum, attributable to discharge from the powder coating industry
  • a continuing decline in nickel discharged due to factory closures and reduced use within the metal finishing and edible oil industries, there have also been related reductions in the tankered waste treatment industry
  • a small increase in silver, attributable to discharge from the photographic processing industry
  • a decrease in tin due to a reduced discharge from one large analytical laboratory
  • a decrease in zinc due to a reduction in the mass discharged from one phosphate industry customer and one liquid waste treatment customer.

There have been no trade waste consents granted for the discharge of uranium since 1995. Sydney Water continues to audit trade waste dischargers for uranium, but no significant sources have been detected.

Total mass of heavy metals received under trade waste agreements with Sydney Water

Metal (kg/day)

1998
–99

1999
–00

2000
–01

2001
–02

2002
–03

2003
–04

2004
–05

2005
–06

2006
–07

2007
–08

2008
–09

Cadmium

0.1920

0.1310

0.0850

0.0670

0.0330

0.0070

0.0220

0.0480

0.0460

0.0300

0.0140

Chromium

2.6850

2.9570

2.0150

3.0170

1.7310

1.6030

1.1210

1.7400

0.8540

0.6060

0.5040

Cobalt

0.0002

0.0020

0.0015

0.0022

0.0038

0.0005

0.0005

0.0039

0.0075

0.0360

0.0690

Copper

3.6400

4.1100

3.3610

3.4450

3.1450

4.5930

2.0920

1.7560

1.5980

2.1640

3.3870

Iron

28.2000

52.0700

32.5700

26.7800

27.6100

38.5300

39.0500

56.5900

69.7200

51.2300

62.4900

Lead

1.8940

0.9580

0.4650

0.5040

0.3510

0.3510

0.2270

0.1840

0.2030

0.2050

0.1400

Manganese

0.6060

1.3830

0.8600

0.7060

0.6740

0.5910

0.5710

0.7740

0.9650

1.0870

0.6530

Mercury

0.0530

0.0245

0.0164

0.0270

0.0124

0.0058

0.0037

0.0017

0.0059

0.0066

0.0030

Molybdenum

1.4260

0.6050

0.0490

0.0200

0.0320

0.0110

0.0030

0.0100

0.0020

0.0004

0.0001

Nickel

3.2850

4.7300

4.4090

4.9890

3.6040

2.5550

2.2510

2.3980

1.8440

1.4820

1.1480

Silver

0.3030

0.3410

1.5770

2.0580

0.8520

0.3150

0.4600

0.6200

0.1720

0.1040

0.1140

Tin

0.3460

0.3530

0.2650

0.1440

0.1530

0.1310

0.1100

0.0520

0.2000

0.3220

0.1320

Uranium

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

Zinc

8.9100

10.5500

8.2600

10.7000

12.1400

11.0500

9.4000

11.6700

12.0500

12.1900

11.0800