EVALUATING THE ENVIRONMENTAL BENEFITS OF NEW WASTEWATER SCHEMES ON SYDNEY S OUTSKIRTS

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1 EVALUATING THE ENVIRONMENTAL BENEFITS OF NEW WASTEWATER SCHEMES ON SYDNEY S OUTSKIRTS Shafiqul Hassan and Cathy O Rourke Sydney Water, Sydney, NSW, Australia ABSTRACT Since 2003, Sydney Water has constructed 17 new wastewater schemes in villages previously reliant on on-site sewage management systems. The environmental benefits of the new schemes were assessed by collecting water quality data from potentially impacted watercourses before and after commissioning. Pre-commissioning data demonstrated some evidence of pollution from on-site systems. Extremely high levels of ammonia nitrogen and bacteria and sewage odours were the key indicators of sewage contamination. There were a number of challenges encountered, including inconsistencies in monitoring program design and low or no flow at some monitoring sites. Despite this, the post-commissioning data for most of the completed schemes provides sufficient evidence of water quality improvement in the immediate vicinity of the villages. Monitoring methods improved over the years to identify the benefits of new schemes more effectively. INTRODUCTION Traditional on-site sewage management systems are common at the outskirts of greater Sydney and in regional New South Wales (NSW). The NSW Government s Priority Sewerage Program (PSP) commenced in 1997 as an initiative to provide improved wastewater services to unsewered urban areas on a priority basis. Priority areas were originally selected based on an assessment by the NSW Environment Protection Authority (EPA) and Department of Health (Sydney Water 2001). Provision of a reticulated system to areas with a high environmental ranking was considered to provide an opportunity for significant environmental improvement and reduction in human health risks (NSW Government 1996). Highly ranked areas typically consisted of areas within a drinking water catchment, recreational areas (including primary contact) or areas surrounded by sensitive environments (NSW Government 1996). Since 2003, Sydney Water has completed 17 new wastewater schemes as part of the PSP (Figure 1) and connected 33 villages and over 11,000 properties to its wastewater network. The next scheme to connect two more villages is due to be delivered by mid-2015, bringing the total to 18 schemes. The key environmental objectives of the PSP are to provide an improved wastewater service that provides for environmental improvement, reduces risks to public health and improves public amenity. The overall objective of this paper is to evaluate the achievement of these objectives by analysing the water quality data before and after commissioning of the schemes. A case study of the Glossodia, Freemans Reach and Wilberforce Scheme is included to provide more detail on a typical water quality monitoring program and monitoring outcomes. Details about the monitoring challenges encountered and improvements made over the years are also provided. METHODOLOGY Monitoring programs Water quality monitoring programs have been implemented for 16 out of the 18 planned and completed PSP schemes. The monitoring programs have complemented the environmental impact assessments prepared for each scheme. The monitoring results have been used to inform Sydney Water s benefit realisation reviews. The water quality monitoring programs focused on assessing the conditions before and after commissioning of each wastewater scheme. Sydney Water targeted locations where the on-site sewage management systems might be impacting the local stormwater drainage lines, creeks or rivers. Where possible, reference sites upstream of the villages were also chosen for comparison with impact sites. Pre-commissioning data was collected for 16 schemes. Post-commissioning monitoring commences when at least 80% of properties within the scheme service area have connected. At January 2015, this has been completed for 10 schemes (Figure 1).

2 Figure 1: Location of PSP villages delivered by Sydney Water Monitoring generally included field measurements of common physico-chemical variables such as temperature, dissolved oxygen, ph, conductivity and turbidity along with field observations on sewage odours and the visual and aesthetic conditions. Samples were also collected for laboratory analysis of ammonia nitrogen, oxidised nitrogen, total nitrogen, total phosphorus, faecal coliforms and Enterococci. Only dry weather samples were taken for three of the earlier schemes. It was expected that the impact from on-site systems would be more clear in dry weather conditions when rainfall and the resultant stormwater run-off are minimal. For later schemes, both wet and dry weather samples were taken. Not all water quality variables listed above were monitored for all schemes. Ammonia nitrogen (a key indicator of sewage pollution) was not monitored for three earlier schemes: Bundeena and Maianbar, Jamberoo and Coalcliff, Stanwell Tops, Stanwell Parks and Otford. Enterococci was not monitored for the Mulgoa, Wallacia and Silverdale Scheme. Some schemes had insufficient number of impact or reference sites due to local access constraints or the topographic conditions. Some impact sites or upstream reference sites (creek/river) were also impacted by other local factors such as upstream unsewered villages, intensive agricultural practices or other unknown pollution sources. The design of the monitoring programs, especially for the early schemes, has varied resulting in some difficulties in evaluating and comparing the water quality results. Key variations across the monitoring programs include: The duration and frequency of sampling was different for each scheme and was governed by scheme planning and construction deadlines. Monitoring periods ranged from one week pre and two weeks post-commissioning for the Jamberoo Scheme, to three years postcommissioning for the Bundeena and Maianbar Scheme. The monitoring season varied for each scheme and also between pre and postcommissioning periods.

3 Data selection As a result of the variations across the monitoring programs, not all data collected could be used for the analysis. Wet weather samples were not collected for all schemes and therefore only dry weather data is analysed in this paper. Due to insufficient flow or stagnant water conditions, limited or no monitoring data was collected from some sites. As a result, the analysis is restricted to: pre-commissioning water quality data from 106 of 132 planned sites, including 82 impact and 24 reference sites post-commissioning data from 65 of 84 planned sites, including 48 impact and 17 reference sites. Data analysis Five water quality variables which are expected to be more directly related to pollution from on-site sewage management system are analysed in this paper. These are ammonia nitrogen, total nitrogen, total phosphorus, faecal coliforms and Enterococci. Statistical analysis was carried out for each site by the paired t-test (SAS 9.4) to determine any significant change (p<0.05) in water quality after commissioning. Monitoring results were compared with the sitespecific and national guidelines. Firstly, the sites were grouped into impact and reference sites, and then into drainage line, creek and river sites. Conclusions were drawn for each of these across all schemes. The ANZECC (2000) guideline for the protection of aquatic ecosystems was used for ammonia nitrogen. For bacteria (faecal coliforms and Enterococci), the primary and secondary contact recreation guidelines (ANZECC 2000) were used for river and creek/drainage line sites, respectively. For nutrients (total nitrogen and total phosphorus), guideline values were based on land use or catchment type (HRC 1998). For example, urban stream guidelines were used for drainage line and creek sites and estuarine guidelines were used for saline or semi-saline sites. Because of the large number of monitoring sites and therefore results, an integrated water quality status was developed for each site and monitoring period. The integrated water quality status provides a basis for analysing the results and determining the overall trends in water quality from before and after commissioning. This was firstly based on percent samples within the guideline for each variable and site. Then the average percentage of all variables was regarded as the integrated water quality status of that site, which is expressed in percent. RESULTS AND DISCUSSION Pre-commissioning results The pre-commissioning monitoring data demonstrated some evidence of pollution from onsite sewage management systems. Very high levels of ammonia nitrogen and bacteria along with sewage odour were the key indicators of sewage contamination from on-site systems. The maximum levels recorded for ammonia nitrogen and faecal coliforms at each impact site is shown in Figure 2 and Figure 3, respectively. Ammonia nitrogen reached above 1 mg/l (an initial level of concern for sewage contamination) at one or more sites in 10 out of the 13 schemes where it was monitored (Figure 2). It reached above 10 mg/l and 50 mg/l at one or more sites at seven and two schemes, respectively. The maximum densities of faecal coliforms reached above 1,000 organisms/100ml, (secondary contact guideline for recreational use of waterways) at one or more sites in 15 out of 16 schemes monitored (Figure 3). It reached above 100,000 (organisms/100ml) at one or more sites in 11 out of 16 schemes monitored. Among the 82 impact monitoring sites, about one third (27 sites) indicated sewage related pollution based on a gross comparison of odours, ammonia nitrogen and bacteria data. Eighty nine percent (24 sites) of these sites were drainage line sites and the remaining 11% (3 sites) were creek sites. At a scheme level, the pre-commissioning data for 11 out of 16 schemes (about two thirds) had one or more sites with some evidence of contamination from on-site systems. Among the five schemes where no sewage related pollution was detected, three had some constraints in monitoring program design or topographic conditions. There was only one impact site (creek) monitored for the Oaks, Oakdale and Belimbla Park Scheme. There were no drainage line sites monitored for the Jamberoo scheme and the monitoring period was too short, only two sampling events within a week. The mountainous topography of Hawkesbury Heights and Yellow Rock areas allows rapid movement of water through their drainage systems, making detection of pollution more difficult. The pre-commissioning monitoring program for two of the more recent schemes (West Hoxton and Galston and Glenorie) was more successful in identifying sewage contamination from on-site systems. This is because of better designed monitoring programs and methods. Field based ammonia tests and field notes on sewage odours corresponded well with the high ammonia nitrogen and bacteria results for multiple sites of these schemes. Three sewage contaminated sites were identified at Galston and Glenorie with extreme

4 levels of ammonia nitrogen, bacteria and also sewage odour on many sampling occasions. At two other sites, there were also evidences of possible sewage contamination. At West Hoxton, there was strong indication of sewage pollution at two drainage line sites which were located at downstream drainage points of this small urban village. Two other upstream drainage line sites also suggested some level of sewage contamination. (Figure 1) across the Hawkesbury River. The scheme was delivered in 2012 and connected more than 1600 properties to Sydney Water s existing wastewater network. The stormwater drainage systems of these villages are connected to Howes Creek, Currency Creek and a couple of other minor tributaries before joining with the Hawkesbury River (Figure 4). The Howes and Currency Creeks catchments are predominantly rural, with some urban and residential development. The water quality within these creeks is also governed by other upstream peri-urban areas and intensive agricultural activities such as poultry farms, livestock grazing and horse studs, market gardens, orchards and turf farms. Eight monitoring sites were selected in total, including five drainage line sites, two creek sites and one upstream reference site on Currency Creek (N392) (Figure 4). No monitoring site was selected in the Hawkesbury River. It was expected that it would be difficult to separate many other upstream or local catchment factors contributing to the overall water quality of the river. Figure 2: Pre-commissioning maximum ammonia nitrogen at all impact monitoring sites (13 schemes) Figure 4: Monitoring sites and servicing areas of Glossodia, Freemans Reach and Wilberforce Figure 3: Pre-commissioning maximum faecal coliforms at all impact monitoring sites (16 schemes) Case study: Glossodia, Freemans Reach and Wilberforce A case study of the Glossodia, Freemans Reach and Wilberforce Wastewater Scheme is included in this paper to provide more detail on a typical monitoring program and monitoring outcomes. This scheme provides a good representative example, in that many of the difficulties encountered and mixture of results were also encountered during other monitoring programs. Glossodia, Freemans Reach and Wilberforce is located about 60 km north west of Sydney The pre-commissioning monitoring collected and analysed weekly water quality samples for 13 weeks between June and September The post-commissioning monitoring was conducted at a fortnightly interval between September 2013 and March 2014, with a total of 13 sampling trips. The drainage line site at Freemans Reach (N3901) could not be monitored because of dry conditions during both pre and post-commissioning periods. Pre-commissioning data for two of the three drainage line sites in Wilberforce showed some evidence of sewage contamination from the on-site systems. There were strong sewage odours at Kings Road (N3401), Wilberforce on multiple occasions during sampling. These events were also accompanied by high ammonia nitrogen and

5 bacteria levels. The drainage line site at Duke Street, Wilberforce (N3402) also had sewage odours and elevated levels of ammonia nitrogen, nutrients and bacteria. The post-commissioning results and statistical analysis confirmed an environmental improvement at both these sites with no sewage odours and reduced levels of all pollutants including ammonia nitrogen (Figure 5). other schemes, in that greater improvements were observed at local drainage sites closer to the source of pollution. Two of the monitoring sites, at Spinks Road, Glossodia (N4001) and at the corner of Clergy Road and Poidevin Lane, Wilberforce (N3403) were always dry during post-commissioning. For this reason, no samples could be collected during postcommissioning monitoring, even though samples were consistently collected and analysed in the precommissioning period. Recorded qualitative observations show that these sites had low flow and occasionally moderate flow during the precommissioning period. The fact that no samples could be taken during post-commissioning monitoring makes it difficult to draw conclusions about the benefits of changing the wastewater management practices based on specific water quality results. However, the fact that these sites were always dry upon sampling may indicate an improvement in itself. It suggests that there may be less leakages or spilling of unauthorised sewage to stormwater during dry conditions, particularly given that rainfall was similar in the two periods. Without continuous quantitative data on flow rates in these stormwater lines the assumption of an improvement is hard to verify (Sydney Water 2014). The trends in dry weather ammonia nitrogen, total nitrogen, total phosphorus, faecal coliforms and Enterococci levels are shown in Figure 5. Statistical analysis confirmed that at one drainage line site of Wilberforce (N3401) all five variables improved significantly (p<0.05) after the commissioning of the scheme. At drainage site N3402, four out of five variables improved significantly (p<0.05). The pre-commissioning water quality at the three creek sites (N391, N392 and N321) was much better in comparison to drainage line sites as expected. The trends were mixed as determined by statistical test (p<0.05) with some further improvements in ammonia nitrogen and nutrient variables and a significant deterioration in faecal coliform and Enterococci at one site (N391). Overall, the results showed evidence of significant water quality improvements at two drainage sites in Wilberforce. This indicated that the wastewater scheme has resulted in environmental benefits in the immediate vicinity of the Wilberforce village. Insufficient data at some sites, including Freemans Reach, meant that an assessment of impacts could not be undertaken. Results at the creek sites (including the reference site) were mixed, which likely reflects other catchment influences. The results of this monitoring program was similar to Blue site code=reference site; Filled box= pre-commissioning, empty box=post-commissioning, The boxes graph the 25 th percentile values, mean (dot), median (line), and 75 th percentile values. The whiskers pointed to 10 th (bottom line) and 90 th percentile values (top line). The number of observations at the bottom of each box. Figure 5: Spatial and temporal trends in water quality at Glossodia, Freemans Reach and Wilberforce

6 Summary of outcomes: all schemes The water quality was generally poor at all monitoring sites and it frequently exceeded the guideline limits. The integrated water quality status improved at many impact sites after commissioning (Figure 6). Greater improvements were seen more locally, at drainage line sites closer to the source of pollution from on-site systems. The water quality status was relatively better at reference sites compared to impact sites as expected but postcommissioning results varied due to other factors related with those sites. showing no evidence of sewage contamination before or after commissioning. It is therefore more likely that the deterioration was due to other factors (for example upstream pollution sources). Of the sites monitored, most improved were sites at Bundeena, Maianbar, Stanwell Tops, Silverdale, Brooklyn, Wilberforce and Appin. There were one or more local drainage sites at these villages with extremely high levels of ammonia nitrogen and bacteria before commissioning. These contaminant levels decreased markedly following the commissioning of schemes. There were also some sites and villages where pre-commissioning water quality was relatively better and little or no further improvement was detected during postcommissioning (Coalcliff and Hawkesbury Heights). Figure 6: Average integrated water quality status based on percent samples and water quality variables within the guidelines (top=impact sites, bottom=reference sites) There was a generalised improvement across the board in key water quality variables related to sewage pollution. The maximum ammonia nitrogen concentration and faecal coliform densities decreased at many sites after commissioning especially where the pre-commissioning levels were extremely high (Figure 7). The monitoring results indicated improved water quality at many impact sites after commissioning of new wastewater schemes. Statistical analysis confirmed that the level of ammonia nitrogen, total nitrogen, total phosphorus, faecal coliform and Enteroccocci was significantly lower (p<0.05) at many sites following commissioning. Significant improvements in water quality were observed at more than 60% of impact monitoring sites (30 out of 48). The water quality was steady or somewhat deteriorated at the remaining sites (Figure 8). The water quality also deteriorated significantly at some impact and reference sites (13 sites) across most of the schemes. One common characteristic of these sites was that pollutant levels were generally low Figure 7: Comparison on pre and postcommissioning level of maximum ammonia nitrogen and faecal coliforms

7 100% 80% Oaks, Oakdale & Belimbla Park (2003) Hawkesbury Heights & Yellow Rock (2010) Glossodia, Freemans Reach & Wilberforce (2012) Percent variables improved 60% 40% 20% 0% -20% -40% -60% -80% -100% Bundeena & Maianbar (2003) Jamberoo (2005) Mulgoa, Coalcliff, Stanwell Wallacia Tops, Stanwell Park &Silverdale & Oatford (2005) (2006) Schemes and sites Brooklyn & Dangar Island (2008) Agnes Banks & Londonderry (2010) Appin (2012) (100% means all key variables improved, -25% means 25% variables deteriorated, 0% means all variables stable or 50% improved and 50% deteriorated and so on) Figure 8: Significant trends (p<0.05) in water quality variables at all 65 monitoring sites; impact sites in bright blue and reference sites in dark blue. Improvements in monitoring program design Sydney Water has progressively improved monitoring strategies and sampling techniques to better detect the underlying environmental impact from on-site sewage management systems (if any). For example, in later schemes monitoring data was also collected during wet weather, when there is potential for overflows and contaminated runoff from poorly performing on-site systems. As a result of the progressive improvements, the best sampling design and monitoring data was captured for the most recent program implemented for the Galston and Glenorie Wastewater Scheme. Extensive desktop research and field inspections were carried out before selecting monitoring sites for this scheme to capture the probable hot spots with sewage pollution. Two types of sites were selected initially: (i) routine sites: sample collection would occur under all conditions, these were at strategic locations within the drainage system or creeks; (ii) drive by sites: where monitoring was conducted only when sewage odour was detected and/or high ammonia nitrogen was detected by the field test kit. In addition, more importance was given to qualitative field data collection such as sewage odours, stream flows, weeds or presence of any other visual pollutants to support the data analysis. CONCLUSION Sewage odours, high levels of ammonia nitrogen and bacteria were commonly observed at water quality monitoring sites where on-site systems were used during pre-commissioning monitoring. The post-commissioning monitoring results showed improvements in key nutrients, ammonia nitrogen and bacteria levels at many drainage line sites and also at some creek sites located close to the source of pollution from onsite systems. Improvements were greater at villages where higher levels of pollution from onsite systems were detected during precommissioning. Despite some limitations associated with consistency in monitoring program design and low or no flow at some sites, the data for most of the completed schemes provided sufficient evidence of local improvement in the immediate vicinity of the villages serviced under the PSP. The monitoring programs have provided useful learnings since The design of the programs has improved to more effectively evaluate the environmental benefits of the new wastewater schemes. ACKNOWLEDGMENT We acknowledge the personnel involved in designing and implementing some of these earlier monitoring programs. We are grateful to many field staff for their extensive efforts to collect samples over many years and laboratory staff for analysing these samples.

8 REFERENCES ANZECC Australian and New Zealand Water Quality Guidelines for Fresh and Marine Waters, Australian and New Zealand Environment and Conservation Council. HRC Independent Inquiry into the Hawkesbury-Nepean River System. Final Report. Healthy Rivers Commission of NSW, Australia. NSW Government Village Wastewater Management Program, NSW Government, NSW. New South Wales Parliament Legislative Assembly - Committee on Environment and Regulation 2012 Inquiry into the regulation of domestic wastewater, NSW Government, Sydney. Sydney Water Memorandum Extension of the Priority Sewerage Program, Sydney Water, Sydney. Sydney Water Glossodia, Freemans Reach and Wilberforce Wastewater Scheme, Water Quality Report. Sydney Water, May 2014.