Sydney Water operates its wastewater business in a ‘due diligence’ manner to eliminate or minimise any potential impact on the environment. The wastewater treatment systems are supported by a comprehensive monitoring framework to measure and assess their past performance against regulations. This report summaries the outcome of assessment on wastewater and environmental monitoring data to meet conditions within the Environment Protection Licences. At a glance, all wastewater plants and associated networks are performing to design criteria and licence compliance with continued maintenance of, or improvement in, treatment levels and recycling activities. The results from all ambient and impact monitoring programs were also satisfactory with only a few measureable impacts on the environment. Most of the past impact areas or ‘hot spots’ were eliminated because of improved treatment practices and mitigation measures. The long-term trend in environmental health showed improvement with some better than expected outcomes in beaches and waterways used for recreation. Ecosystem health has improved and nutrient enrichment in streams and rivers, where there were direct impacts from wastewater discharges or overflows in the past, has reduced.

Report structure Volume I is the executive summary of all volumes. Detailed technical assessment and outcomes of data analyses are embedded in the six other volumes. The linkage among all seven volumes of the STSIMP Interpretive Report 2010-11 is shown below:

VOLUME I VOLUME II Executive Interpretive Summary Report

VOLUME III VOLUME IV VOLUME V VOLUME VI VOLUME VII Ocean Case Study: Other Case Coastal Lagoons Appendices Sediment Long Term WQ Studies and Sanity Inspection (For Al Chapters) Program Trends in HN River Technical Analysis Report

Sydney Water - Commercial in Confidence Page | iii Table of Contents

Key information iii Report structure 3 1 Introduction 1 1.1 Background 1 1.2 Sewage Treatment System Impact Monitoring Program 1 1.3 Report objectives 3 1.4 Definition of disturbance and impact 3 2 Ocean plants 4 2.1 Wastewater discharges 4 3 Environmental assessment: oceans and beaches 5 3.1 Ocean receiving water 5 3.2 Marine benthic communities and sediment quality 5 3.3 Recreational water quality – Sydney beaches 5 3.4 Recreational water quality – Illawarra beaches 6 3.5 Shellharbour surveys 6 4 General environment: condition of rivers, estuaries and lagoons 9 4.1 Chlorophyll-a in rivers and estuaries 9 4.2 Chlorophyll-a in lagoons 9 4.3 Freshwater bugs 9 4.4 Intertidal communities 10 4.5 Recreational water quality: estuaries and harbours 10 4.6 Recreational water quality: lagoons 11 5 Inland plants 11 5.1 Wastewater discharges 11 5.2 Wastewater toxicity 11 5.3 Plant performance 12 6 Environmental assessment: Hawkesbury - Nepean River 13 6.1 Current nutrient status 13 6.2 Long-term nutrient trends 14 6.3 Freshwater bugs 15 7 Wastewater overflows and environment 16 7.1 Dry weather overflows 16 7.2 Wet weather overflows 16 7.3 The dry weather leakage program 17 8 Recycled water 19 9 References 19

Sydney Water - Commercial in Confidence Page | iv 1 Introduction

1.1 Background 1.2 Sewage Treatment System One of Sydney Water’s principal corporate Impact Monitoring Program objectives is to minimise the impact of its The impact from Sydney Water’s activities on the environment. Sydney wastewater operations on the receiving Water is supported in this capacity by a water environment is measured by a core comprehensive regulatory framework. The program called the Sewage1 Treatment wastewater operational activities of System Impact Monitoring Program Sydney Water is regulated by (Sydney Water 2010). The program is Environment Protection Licences designed to monitor direct impacts of (licences) issued by the New South Wales Sydney Water activities on ecosystem Environment Protection Authority (EPA). health or recreational water quality and to Sydney Water operates 23 wastewater monitor ambient environmental conditions systems across the Sydney, Blue at sites where Sydney Water may be a Mountains and Illawarra area (Figure 1). major contributor. The Sydney-Blue Mountains-Illawarra The program monitors a broad range of region is a major centre of economic, receiving water environments including industrial and agricultural activity. These marine, shoreline, estuarine and diverse activities all influence the freshwater riverine. The monitoring environmental health of the region and parameters were chosen based on Sydney Water’s discharge activities national guidelines for protecting the represent just one input to the complex aquatic ecosystem (ANZECC 2000) and local riverine, estuarine and ocean from current knowledge of the relationship environments. The challenge for Sydney between pollutants and ecological and Water is to identify the effects of its human health impacts. The ecological operations against the background of integrity of the aquatic environment is other diverse human activities. assessed by monitoring biological parameters such as estuarine settlement Sydney Water aims to address this organisms, biota in ocean sediments, challenge by well-designed monitoring that freshwater macroinvertebrates and algal targets key impact indicators, which are populations. Microbiological, physical and sensitive to Sydney Water’s activities. chemical parameters measure the direct impact of treated wastewater discharges and overflows from wastewater networks.

______1 Sewage was a traditional term used by Sydney Water and others. It is now replaced by ‘wastewater’ to include all types of used water being treated by the Sydney Water’s wastewater treatment facilities and also to reflect changes to the new Operating Licence

Laboratory chemical analysis of collected water quality samples

Sydney Water - Commercial in Confidence Page | 1

Note: Gerringong/Gerroa system is included for completeness. It is owned by Sydney Water but operated by Veolia Water

Figure 1 Location of Sydney Water’s Wastewater Treatment facilities

Sydney Water - Commercial in Confidence Page | 2

1.3 Report objectives 1.4 Definition of disturbance and This report, the STSIMP Interpretive impact Report 2010-11, is the first combined interpretive report covering a number of Sydney Water’s definition has been previously separated investigations. The derived from the scientific literature and ultimate purpose of combining the the ANZECC (2000) guidelines. The interpretation of multiple studies is to release of a contaminant into water that is provide a ‘weight of evidence’ approach to of sufficient quantity to cause a identify Sydney Water’s environmental measurable chemical change is called a impacts over and above the other impacts ‘disturbance’. This includes natural events of urbanisation. like floods. A ‘disturbance’, natural or man-made, that is of sufficient size to This is one of Sydney Water’s yearly cause a measurable ecological change reports to meet the Condition M10.5 and (in any direction) is called an ‘impact’. M10.6 of Sydney Water’s licences. In general, data collected between July 2010 and June 2011 was used to assess the current year’s performance. However, historical data collected up to 10 or more years back (where available) were also used to assess the long-term trends. More specifically the report aims to fulfil the following objectives: • assess yearly wastewater discharge quantity and quality data to licence limits

• determine long-term trends in wastewater pollutant concentrations and Staff discussing statistical analysis of the loads in relation to improvement works monitoring data

• report on water quality conditions and ecosystem health status at various monitoring catchments

• present case studies on rigorous assessment of wastewater and environmental monitoring data with set objectives. a a a a a

Sydney Water - Commercial in Confidence Page | 3

2 Ocean plants

2.1 Wastewater discharges Ocean plants (Figure 1) discharge treated the establishment of Sydney’s three wastewater into receiving waters where deepwater ocean outfalls (OEH 2008). dilution negates any toxicity, as evidenced During 2010-11, Sydney Water’s ocean by ecological monitoring results of the plants discharged a total of 430,021 ML of Ocean Sediments Program. This program treated wastewater into the ocean. This is monitors bottom dwelling invertebrates 91% of total treated wastewater near the three deepwater ocean outfalls discharged by all plants operated by (Bondi, Malabar, and North Head). No Sydney Water. The remaining 9% is measurable impact was detected in the discharged to inland rivers. marine benthos communities from these discharges. The Office of the Environment All median and 90th percentile oil and and Heritage (OEH) indicates that water grease and total suspended solids results quality since 1989 at Sydney's beaches is for ocean plants were within the licence now 98% cleaner due to initiatives such as compliance limits. Similarly, the licence limit for toxicity testing was met at all ocean plants in 2010-11.

Historic image (1989) of a sewage plume discharged from a cliff face outfall, now discharged to the Deepwater Ocean Outfalls

Sydney Water - Commercial in Confidence Page | 4

3 Environmental assessment: oceans and beaches 3.1 Ocean receiving water In oceans the water quality conditions are benthos communities adjacent to these predicted from effluent quality data and discharges. dilution factors determined by hydraulic Statistical trends of the 2010-11 analysis modelling of effluent plume dispersion. were very similar to results from previous The modelled plume dilutions for all three assessment years of 1999, 2002, 2005 deepwater ocean outfalls (North Head, and 2008. These analyses also indicated Bondi and Malabar) indicates that dilutions that the deepwater ocean outfalls had no were variable and tended to range from measurable impact on ecosystem health 100:1 through to 1,000:1 in 2010-11. and did not alter sediment quality. For all three plants, the average levels of Thus long-term results of the program measured contaminants in the effluents at show that the deepwater ocean outfalls the lowest dilution factor of 100:1 are are performing as designed. They have below ANZECC (2000) guidelines which contributed to improving water quality at are set to protect aquatic communities. Sydney beaches (OEH 2008).

3.3 Recreational water quality – Sydney beaches Sydney Water has been reporting beach water quality based on indicator bacteria (faecal coliform and also Enterococci from 1993 onwards) derived from the OEH Beachwatch program, which began in 1989. In 2009 new water quality indicators were introduced aligning Australia with internationally accepted guidelines using Enterococci and sanitary inspection Confirming the taxonomic name of an ocean bottom dwelling worm category data (NHMRC 2008). This is the second year of assessment 3.2 Marine benthic communities under the new guidelines to determine and sediment quality beach suitability grades. In general, there was little change between the two years of The Ocean Sediments Program assesses assessment, with 35 of the 36 ocean the potential impact of discharges from the beaches graded as Good or Very Good in three deepwater ocean outfall plants 2009-10 and 2010-11. The one Very Poor (Malabar, Bondi and North Head) on the performing beach was Malabar. marine environment. To improve Malabar Beach, a $2 million Detailed statistical analysis indicated the project has been jointly funded by Sydney discharges from the deepwater ocean Water, Randwick Council, the OEH and outfalls did not alter the ecological the NSW Environmental Trust's Urban community of the marine benthos or Sustainability Program. This program will sediment quality. That is, no measurable relocate the Council’s stormwater outlet to impact was detected in the marine the cliff face away from the beach.

Sydney Water - Commercial in Confidence Page | 5

A south coast beach

3.4 Recreational water quality – from the Shellharbour plant that discharges into the near shore ocean Illawarra beaches environment. This is the second year of assessment In 2002, surveys of the rocky intertidal under the new guidelines derived from the community recorded an apparent OEH Beachwatch program. In general measurable impact along 50 metre of the there was little change between the two shoreline at the outfall site of Shellharbour years of assessment, with 17 of the 18 plant (EP Consulting 2003). beaches graded as Good or Very Good in 2009-10, and 19 out of 20 beaches graded In contrast, the current surveys which as Good or Very Good during 2010-11 identified the taxonomic composition for (Figure 2). 2008, 2009 and 2010 indicate the outfall site was no longer dominated by green The beach at the mouth of Lake Illawarra macroalgae and has a number of similarly (Entrance Lagoon Beach) has ongoing low abundant taxa to that of a control location. levels of bacterial contamination and is Thus, 2008 to 2010 monitoring data currently being investigated by local suggests upgrade works at the authorities with Sydney Water’s Shellharbour plant (end 2002 to early assistance. 2003; 2005 to 2006) were successful. The community structure was relatively stable 3.5 Shellharbour surveys in the last three years following the upgrade of the plant. Monitoring of rocky-intertidal communities under the shoreline outfall program assesses the potential ecological impact

Sydney Water - Commercial in Confidence Page | 6

Very good and Good Fair Poor, Very poor and Follow up

Figure 2 Beach suitability grades at Illawarra Beaches

Sydney Water - Commercial in Confidence Page | 7

Historic image (2001) of an unhealthy rock platform impacted by Shellharbour plant prior to upgrade

A healthy rock platform community

Sydney Water - Commercial in Confidence Page | 8

4 General environment: condition of rivers, estuaries and lagoons

4.1 Chlorophyll-a in rivers and Lagoon. The remaining two sites, the estuaries mouth of Narrabeen Lagoon and Wattamolla Lagoon were both rated as Chlorophyll-a, an indicator of planktonic Very Good. algal biomass was measured at 17 sites of Port Jackson, Botany/Georges River and Port Hacking (refer to sections 6.1 and 6.2 for the Hawkesbury-Nepean River sites). In general, the levels were Good to Very Good at sites closer to the mouth of each estuary. Port Hacking is a well flushed estuary and this is reflected in consistently low concentrations of chlorophyll-a. In Sydney Harbour, the outer harbour area is well flushed by low nutrient, sea water and this is reflected by low Collecting freshwater bugs (macroinvertebrates) chlorophyll-a levels. The inner harbour, becomes progressively more eutrophic, as indicated by higher chlorophyll-a 4.3 Freshwater bugs concentrations, with increasing distance from the mouth of the estuary. The lower Four test sites were monitored with the salinity reaches of Lane Cove River and macroinvertebrate indicator to assess the Parramatta River have consistently high general condition of stream health. Three concentrations of chlorophyll-a resulting of these sites are in urban areas and just in Poor water quality rating for these upstream of estuarine limits of the sites. Parramatta River, Lane Cove River and Georges River. The fourth site is about Botany Bay and the Georges River have a 5 km further up in the Georges River. similar pattern to Sydney Harbour with the well flushed, saltwater sites in Botany Bay Reference sites were also monitored having low chlorophyll-a concentrations. around Sydney to define the level of The lower salinity reaches in the Cooks natural variation in bug communities of River and the Georges River having bushland streams without urban or rural consistently elevated concentrations of influences on water quality. chlorophyll-a. The direct connection of impervious surfaces, such as roofs, gutters, roads, 4.2 Chlorophyll-a in lagoons paths and car parks, to a stream allows The lagoons have variable results for small rainfall events to produce surface chlorophyll-a ranging from Poor water runoff that cause frequent disturbance to quality ratings through to Very Good. The the stream through regular delivery of two worst locations are Upper Manly water and pollutants. As such, a Lagoon and Curl Curl Lagoon with a Poor background level of impairment in water and Fair rating respectively. quality is an expected result when monitoring streams in urban areas. There were three lagoon sites that had a Good rating; the mouth of Manly Lagoon, Results indicated the range of stream Dee Why Lagoon and upper Narrabeen health in 2010-11 was similar to those

Sydney Water - Commercial in Confidence Page | 9

recorded from 1995 to 2010. The 4.5 Recreational water quality: degraded stream health of the test sites estuaries and harbours reflected the water quality status, which was mildly to moderately impaired since This is the second year of assessment monitoring commenced in 1995. under the new guidelines derived from the OEH Harbourwatch program. The potential influence of wastewater overflows in these results cannot be Over 50 sites were measured for bathing separated from the influence of suitability which is an indirect measure of stormwater at these sites at the bottom of wastewater network performance. These catchments. sites covered Pittwater, Sydney Harbour, Botany Bay, lower Georges River and Port Hacking. 4.4 Intertidal communities In general, there has been little change in Monitoring of rocky-intertidal communities recreational water quality over the last two on relatively wave sheltered sites years. In 2009-10, 34 of the 54 estuarine assesses the general environmental and harbour beaches were graded as condition of Sydney’s estuaries. Good or Very Good, compared to 38 of 55 beaches graded as Good to Very Good in Natural bushland reference sites typically 2010-11. had a community structure dominated by oysters and snails. Test sites disturbed by wastewater tended to be dominated by barnacles and green algae. Analysis suggested that 18 of the 26 sites measured have a healthy intertidal community and that seven sites were mildly disturbed and that one site was moderately disturbed. An impacted location did not have a similar combination of organisms when compared to the ‘National Park’ reference locations. Some of these sites were adjacent to wastewater overflow areas while others were impacted by other human activities. Analysis of long-term estuarine ecosystem health data (1998 to 2010) suggested that seven sites have shown marked improvement through time. Of the seven sites that have improved during the study period, five were adjacent to areas of Sydney Water remediation. These sites were Rushcutters Bay, Long Bay (Tunks Park), Lower Lane Cove River, Muddy A survey of an intertidal rock platform community Creek (mouth of Cooks River) and Hawthorn Canal entering Iron Cove Bay. Timing of the response in rocky intertidal communities at these five sites appeared to coincide with adjacent Sydney Water remediation.

Sydney Water - Commercial in Confidence Page | 10

4.6 Recreational water quality: lagoons Lagoons are infrequently open to the sea population growth. The Hawkesbury- and poorly flushed. They accumulate Nepean Wastewater Strategy has brought catchment runoff which includes bacterial about these reductions in dry weather indicators and tend to fail bacterial loads of nitrogen and phosphorus. Under assessments. This is not an unexpected this strategy, a program of major upgrades trend, as has been observed by OEH of inland plants occurred. throughout NSW. In 2010-11, 238 tonnes of nitrogen and 6.6 The OEH states ‘The microbial water tonnes of phosphorus were discharged to quality in coastal lagoons/lakes is often streams and rivers from inland plants. dependent on whether the entrance to the These loads were within the limits water body is open or closed to the ocean’ permitted under licences. (OEH 2011). This general observation applies to the 5.2 Wastewater toxicity four lagoons in the Sydney metropolitan area (Narrabeen, Dee Why, Curl Curl and Toxicity testing was introduced in the late Manly) as well as the reference lagoon nineties for inland plants. The purpose of (Wattamolla) in the Royal National Park, these tests was to identify how toxic the south of Sydney. All of these would be treated wastewater was in order to regarded as having Poor water quality determine strategies to improve the during periods of sand bar closure despite quality. Monthly testing was introduced in one being in a bush catchment. 2005 as a licence requirement using the Water Flea (Ceriodaphnia). Clear improvements have been observed in Narrabeen Lagoon since 2004, The upgrades that reduced nutrient levels however, the catchment changes also led to a reduction in wastewater responsible for these improvements are toxicity so that freshwater unknown. (macroinvertebrate) communities were not impacted in the Hawkesbury-Nepean River. 5 Inland plants In 1998 to 1999 tests of treated wastewater were toxic 74% of the time (Bailey et al. 2000; SETAC 2008). By 5.1 Wastewater discharges comparison, tests of treated wastewater The total volume of treated wastewater were toxic about 2% of the time for discharged to rivers has decreased by samples taken between 2004 and 2011. about 34% when compared to the last The licence limit for toxicity was met at all 10 years from 63,625 ML in 2001-02 to inland plants in 2010-11. 41,782 ML in 2010-11 despite population growth. This is primarily due to recycling initiatives, the largest being the St Marys Advanced Water Recycling Plant. Penrith, St Marys and Quakers Hill plants now discharge 82%, 51% and 36% lower volumes of treated wastewater into Boundary, South and Eastern Creeks respectively. Since 2000-01 there has been a 61% decrease in nitrogen loads and a 63% reduction in phosphorus loads, despite

Sydney Water - Commercial in Confidence Page | 11

Warragamba River near the Wallacia plant

Table 1 Nutrient removal at inland tertiary treatment plants (July 2005 to August 2011) Tertiary Treatment Plants

Percentage Total Total Ammonia Removal Nitrogen Phosphorus Reference stream in a national park Picton 99.5% 92.0% 99.0%

West 5.3 Plant performance Camden 99.2% 91.1% 98.8%

The inland plants in some cases Wallacia 99.8% 90.7% 99.6% discharge to small streams where their flow is predominantly highly treated Winmalee 98.6% 91.3% 97.7% effluent. Penrith At all fifteen inland plants 96% to 99% of 98.1% 88.2% 98.7% the ammonia is removed (Table 1). North Ammonia is a known toxicant to aquatic Richmond 99.3% 93.8% 99.5% life above certain concentrations and Richmond 99.6% 90.5% 99.3% nitrogenous compounds can turn into ammonia. Similarly, all plants remove Quakers Hill 99.8% 96.4% 99.4% between 77% and 97% of the nitrogen (Table 1). Phosphorus in freshwater can St Marys 99.7% 89.2% 99.8% also stimulate algal growth. Phosphorus removal for all the plants ranges from 96% Riverstone 99.9% 91.1% 99.8% to greater than 99% (Table 1). Castle Hill 99.4% 88.9% 99.8%

Rouse Hill 99.5% 86.7% 99.5%

Hornsby Heights 99.6% 81.3% 98.4%

West Hornsby 99.9% 92.7% 99.4%

Brooklyn 95.9% 76.8% 96.2%

Sydney Water - Commercial in Confidence Page | 12

6 Environmental assessment: Hawkesbury - Nepean River

6.1 Current nutrient status The nutrient status was assessed at 18 sites in the Hawkesbury-Nepean River and it’s tributaries based on nutrients, chlorophyll-a and a range of other physico-chemical variables. There was evidence of nutrient enrichment at the majority of the sites. Some improvement was also noticed at some sites during 2010-11 in comparison to past years. The nutrient status improved from ‘Poor’ to ‘Fair’ at two Upper Nepean River sites. The nutrient status was generally ‘Fair’ to ‘Good’ with less algal problems in the Nepean River at Penrith to the Hawkesbury River at Freemans Reach. There have also been improvements at three out of five sites, where the ratings were ‘Poor’ during 2010-11. As usual, sites in the lower Hawkesbury river section between Wilberforce and River water quality sampling Leets Vale had the worst nutrient status in comparison to any other site of the river. The nutrient status remained ‘Poor’ at all four main stream river sites plus two tributary sites of South and Cattai Creeks. The estuarine section of Berowra Creek was slightly better where the nutrient status at one site improved to ‘Fair’ from ‘Poor’ and the other remained ‘Poor’.

Sydney Water - Commercial in Confidence Page | 13

6.2 Long-term nutrient trends Over the last 20 years, Sydney Water has treated wastewater discharges were implemented a series of improved mostly met by 2003 (Figure 3). wastewater strategies to reduce the In the lower Hawkesbury River, nutrient nutrient loads from its inland plants to the loads (total nitrogen and phosphorus) from greater Hawkesbury-Nepean River Sydney Water’s wastewater discharges system. decreased by about 60 to 90% in the past The overall nutrient loads to the 17 years due to improved treatment Hawkesbury-Nepean River have processes and production of recycled decreased significantly because of water. In the same period, total nitrogen improved wastewater treatment processes and phosphorus concentrations in the and the relocation and decommissioning receiving water were reduced by about 40 of plants by Sydney Water. Trend to 60% and dissolved inorganic nitrogen analyses on nutrient load data showed by more than 80%. However, that total nitrogen load declined chlorophyll-a, only had a 25% decrease significantly by 67% and total phosphorus between 1994 and 2011. load by 92% between 1994 and 2011. The . target phosphorus concentrations in

Figure 3 Long term trend in total phosphorus loads

Sydney Water - Commercial in Confidence Page | 14

6.3 Freshwater bugs Typically, Sydney Water’s monitoring of A localised positive recovery in stream treated wastewater discharges is health was recorded in Boundary Creek, conducted upstream and downstream of below the Penrith plant where the the discharge pipe. This is done to St Marys Advanced Water Recycling Plant determine if stream health was altered by now discharges. Stream health of this treated wastewater discharges from creek is now at the same level as that of plants. the Nepean River. Assessment of data from 2010–11 against that collected between 1995 and 2010 placed site pairs into two categories. Either stream health at the downstream site was maintained within the range recorded for the upstream site or the downstream site differed from this range. Highly treated wastewater discharges from active plants (Castle Hill, Hornsby Heights, West Hornsby, Penrith Quakers Hill, Riverstone, Rouse Hill, North Richmond, St Marys, Wallacia, West Camden, and Winmalee) had no measurable impact on ecological communities in the Hawkesbury-Nepean River. West Camden Caddis Fly larvae - a sensitive river/stream freshwater bug (macroinvertebrate) and Winmalee discharge to small streams and their ecological communities were impacted. However, there were no impacts on the ecological communities in the downstream Nepean River.

Sydney Water - Commercial in Confidence Page | 15

7 Wastewater overflows and environment

Wastewater overflows occur in dry and 7.2 Wet weather overflows wet weather conditions in Sydney Water’s wastewater treatment systems. Overflow To meet the licence requirements for frequency and volume varies from system wastewater systems, Sydney Water has to system. developed hydraulic sewer models. These models allow a direct comparison of Dry weather overflows are predominantly system performance against a benchmark due to blockages caused by tree roots and model based on historical data. wastewater pipe breakages, while wet weather overflows are normally due to Fifteen wastewater systems (Bombo, infiltration of stormwater through breaks, Cronulla, Hornsby Heights, North Head, combined systems and illegal connections North Richmond, Penrith, Richmond, exceeding the system’s capacity. Riverstone, Shellharbour, St Marys, Wallacia, Warriewood, West Camden, 7.1 Dry weather overflows West Hornsby, Port Kembla, and Winmalee) complied to all conditions of Eight wastewater systems draining to the wet weather overflows during 2010-11. ocean plants were responsible for a total overflow volume of 11.1 ML in 2010-11. Six systems did not complied to either full Within the two largest systems draining to or partial conditions on wet weather Malabar and North Head, were overflows (Bondi, Castle Hill, Quakers Hill, responsible for the largest number of Malabar, Rouse Hill and Wollongong). overflows each year. Between 2003 and 2007, the number of overflow events from ocean systems ranged from 762 to 1279 per year. Following the drought, in 2008 normal rainfall had resumed and the number/volume of overflows decreased to 587 per year. During periods of drought the roots of plants often infiltrate wastewater pipes seeking water, eventually blocking them and breaking the pipes resulting in subsequent overflows.

Sydney Water is actively reducing the Historic image (1993) of a wet weather wastewater number and intensity of overflows through overflow in Scotts Creek, Middle Harbour; this is programs like SewerFix. This program now captured by the North-side Storage Tunnel was intensified in 2008.

Thirteen inland plant networks were responsible for a total overflow volume of 2.0 ML in 2010-11. The West Hornsby system had the highest number of overflow events and contributed to more than 50% of total dry weather overflow volume from all inland plants.

Sydney Water - Commercial in Confidence Page | 16

7.3 The dry weather leakage program The ‘Dry Weather Leakage Program’ was introduced in 2006. There are 210 sewer catchments in the Sydney region (Figure 4) which are components of the larger wastewater systems. Between 2006 and 2011 the monitoring results showed that 191 monitoring sites met the licence threshold value of 5,000cfu/100mL faecal coliforms with occasional failures of this limit. Only a small proportion of sewer catchments monitored have consistently failed the threshold and have been targeted for further investigation. Investigations include catchment walks, intensive monitoring and CCTV inspections. Remedial work on Sydney Water’s wastewater infrastructure has had a positive effect on the water quality in the stormwater system. Maintenance work at Edgecliff, Camperdown, Leichhardt, and recently at Belmore South has resulted in Staff about to conduct a safety gas test of a sewer measured improvements at the pipe prior to conducting work corresponding monitoring sites.

Sydney Water - Commercial in Confidence Page | 17

Figure 4 Sewer catchments under Sydney Waters’ control. Green catchments have been identified as requiring further work

Sydney Water - Commercial in Confidence Page | 18

8 Recycled water 9 References

Wastewater reuse is a key strategy ANZECC, 2000. Australian and New Zealand adopted by Sydney Water to conserve Water Quality Guidelines for Fresh drinking water and protect sensitive inland and Marine Waters, Australian and river environments. Details of the reuse New Zealand Environment and programs are presented in Sydney Conservation Council. Water’s Water Efficiency Report (Sydney Bailey, H.C., Krassol, R., Elphick, Water, 2011). J.A.,Mulhall, A., Hunt, P., Tedmanson, L., and Lovell, A. 2000. Whole effluent A total of 19,195 ML of wastewater from toxicity of sewage treatment plants in all inland plants was reused during the Hawkesbury-Nepean watershed, 2010-11. This was 15,238 ML higher than New South Wales, Australia, to the volume reused in 2009-10. The sharp Ceriodaphnia dubia and Selenastrum increase in the volume of reused water capricornutum. Environmental was due to the commissioning of the Toxicology and Chemistry 19:72-81. St Marys Advanced Water Recycling Plant EP Consulting, 2003. Shellharbour sewage in August 2010. treatment plant optimisation and During 2010-11 a total of 7,300 ML of amplification: Intertidal and subtidal rocky reef summer and winter survey wastewater was recycled at the tertiary for Sydney Water Corporation Final ocean plants. Wollongong plant Report. EP Consulting Group Pty Ltd contributed 97% (7,088 ML) of this volume and the remaining came from the NHMRC, 2008. National Health and Medical Liverpool and Bombo plants. Research Council. Guidelines for Managing Risks in Recreational Water. Australian Government Publication Services, ISBN

OEH, 2011. State of the Beaches 2010-11. NSW Office of Environment and Heritage.

OEH, 2008. Beachwatch Report 2008. NSW Office of Environment and Heritage.

SETAC, 2008. Improvements to Effluent Toxicity over a decade of testing. Ecotox Services Australia and Sydney Water In: 5th SETAC World Conference.

Filter section of the St Marys Advanced Water Sydney Water, 2010. Sewage Treatment Recycling Plant System Impact Monitoring Program. Sydney Water, August 2010.

Sydney Water, 2011. Water Efficiency Report 2010-11. Sydney Water.

Sydney Water - Commercial in Confidence Page | 19