http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2928 Australia is a generally dry continent that experiences highly variable rainfall. Since colonisation urban settlements have been regularly subjected to droughts, floods and water shortages. Rapid population growth with subsequent economic growth in industry and commerce resulted in dramatic increases in demand for water. The traditional approach to urban water supply largely focused on developing external water sources to meet growing water demands. Concurrently, urban stormwater and wastewater infrastructure is designed on a philosophy of rapid conveyance to receiving environments with reliance on "dilution" in those waters to assimilate wastes. These concepts have limited the capacity of upstream environments to meet urban water demand and of receiving environments to assimilate contaminant loads. As shown in this chapter, the 'big pipe' and 'end of pipe' solutions to water management are gradually being replaced by new integrated water cycle management approaches that aim to be more sustainable and may include small scale and decentralised infrastructure for managing the urban water streams. This chapter discusses the potential for utilising roofwater, stormwater, greywater and treated wastewater to improve management of the urban water cycle. 2013-04-15T01:26:06.305Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:11128 Masters Research - Master of Philosophy (MPhil) 2012-07-26T05:47:52.426Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1685 A large number and growing proportion of both single lot residential and larger scale new developments in the Hunter Region are not serviced by a conventional reticulated sewerage system. In such cases, wastewater treatment, its possible reuse and final disposal, is on-site, where the effluent is generated. A range of geotechnical factors including the site geology, geomorphology, soils, availability and performance of geo and geosynthetic materials, along with climatic factors, have a bearing on the selection, design, sizing and performance of an on-site wastewater system which will perform adequately and meet regulatory requirements. Geotechnical skills in site and soil assessment are fundamental to and necessary for good on-site wastewater system design and to ensure that the environmental impacts associated with on-site wastewater management are minimised. The Hunter Region displays a number of challenging geological settings and soil types for wastewater management. These include perched and shallow water tables, sensitive aquifers, floodplains and coastal lake and estuary catchments. Soils include sodic, dispersive and duplex soils and high permeability sandy soils with limiting capacities for wastewater assimilation. Hydraulic and nutrient loading capacities of some of the region's soils are limiting and present a challenge to designers. An understanding of transport and assimilation of nutrients and pathogens through permeable materials is significant in understanding the potential contribution of on-site wastewater management systems to surface and groundwater contamination and the protection of those sensitive receiving bodies by appropriate design. This paper reviews the geotechnical aspects of on-site wastewater management in the Hunter Region and illustrates, with a number of case studies, both the problems commonly encountered and their possible solutions. 2012-01-30T04:40:28.316Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:5926 A wide range of models are available to assist with on-site and decentralised wastewater system planning and design. Others may be used to assist with risk assessment, operation and management. This paper will review the types of models used to date in on-site and decentralised wastewater management and will provide pointers as to the potential future use of models for improved design and management of on-site and decentralised systems in Victoria. Case studies will illustrate the use of models for qualitative and quantitative risk assessment, servicing option selection and decentralised system design and costing in Victoria. The value of models as a cost effective means of achieving these objectives will be emphasised. 2012-01-30T04:05:48.198Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:5936 Specific challenges to the provision of a sustainable wastewater service for existing towns with poorly performing on-site systems are being identified through both domestic wastewater management planning and the Victorian Government Country Town Water Supply and Sewerage Program. A key challenge is the development of economically and socially viable effluent reuse and disposal schemes for community wastewater systems that also meet regulatory requirements for the protection of human health and ecosystems.This paper presents the outcomes of a risk assessment and cost benefit analysis for a proposed community wastewater system for a small town in central Gippsland, Victoria. Preliminary modelling suggests that very limited improvement in environmental/human health performance can be expected with the provision of large storage facilities (i.e. wet weather dam) and restriction of deep drainage. Recent experiences from New Zealand support the outcomes of this assessment. Current Victorian guidelines, however, discourage deep drainage in effluent irrigation and therefore the benefits that such schemes can deliver in the future. The outcomes illustrate the need for case by case risk analysis and triple bottom line assessment of wastewater servicing options. 2012-01-30T04:02:29.793Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:8960 Part of a large estuary along the eastern Australian coastline (Port Stephens, NSW) used for shellfish production was closed to harvesting for over 18 months as human viruses were found in oyster tissue. Domestic wastewater systems were considered an important source of the contaminants recorded in the estuary. The local regulatory authmity (Pmi Stephens Council) required that appropriately sized sand mounds be constructed at sites where systems had been assessed as failing and also at new housing sites with severe land capability constraints due to the high groundwater levels. Two of the sand mound systems were monitored in detail since midway through 2007 tor a pe1iod of six months using a variety of soil water samplers and groundwater bores. Only some of the monitoring results are presented in this paper, but on the basis of these results, it is clear that the two sand mounds are performing effectively as a treatment system resulting in significantly reduced contaminant concentrations entering the groundwater (Whitehead and Geary 2008). There is substantial interest in the overall pertonnance ofthese systems as little research has been conducted on wastewater treatment using sand mounds. 2011-09-15T05:30:09.639Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:8915 The steady increase of urban population and the possible onset of climate change that may adversely affect the amount of water available in current water supply systems, makes the study of stormwater and rainwater harvesting and wastewater recycling a high priority. The basic proposition is that any system of water supply that can reduce the amount of water drawn from main reservoirs will be of benefit to the whole supply region especially in terms of drought security. This paper describes a versatile modelling framework which can simulate a wide variety of combinations of centralised and decentralised Integrated Urban Water Management schemes from the allotment to the estate scale. The framework combines two modelling approaches. The first, called urbanCycle, simulates water supply, stormwater and wastewater using allotments as the basic building block. Although urbanCycle can simulate processes in great detail, it assumes that the network forms a directed acyclic graph. This simplifies the connectivity logic but precludes investigation of systems with decentralized storage, feedbacks and multiple supply paths. To overcome this, a second model, based on network linear programming, is embedded in the urbanCycle framework to enable the modelling of recycling and harvesting options, as well as on-the-fly supply and demand decision making, based on objectives rather than pre-set operating rules. 2011-09-12T05:40:06.575Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:7702 Sand mounds can offer suitable treatment and land application option for constrained sites, particularly those where seperation distance to the water table is limited. Sand mound technologies, comommonly called "Wisconsin Mounds", have been extensively developed and utilised in the United States and a number of studies report on their performance. Their is a growing interest in the application of sand mounds in Australia, but to date little has been published on the performance of such mounds in Australian settings. As failing septic tanks had been contributory to viral pollution of oysters grown in an estuary, Port Stephens Council required upgrades. One option was to replace the absorption field by a sand mound and currently 58 mounds are receiving primary treated effluent and receiving secondary treated effluent in Port Stephens. This paper reports results where two of the mound systems were monitored in detail for a period of six months from mid-2007 using a variety of soil water samplers and groundwater bore. 2011-05-12T06:30:18.402Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:3085 Following an outbreak of Hepatitis A disease associated with consumption of oysters from Wallis Lake, New South Wales (NSW), Australia in 1996, the NSW Government has invested A$3.8M over the past four years (1998-2002) in a SepticSafe program to assist local government authorities (local councils) to implement systematic management of sanitation risks related to onsite wastewater management. Part of this investment was directed to the development of an integrated system of sewage risk assessment in coastal areas, particularly oyster growing areas and drinking water catchments (watersheds). An On-site Risk Assessment System (OSRAS) has been developed to bring together information held by local councils and State Government agencies. The OSRAS uses GIS layering techniques and transparent logic matrices to model the fate of sewage pollution from decentralised sewage management facilities, in relation to identified disease vectors and sensitive environmental receptors, and to generate risk "maps". The output will enable councils and State Government agencies to assess the likely scale of impact and relative risk of sewage pollution in unsewered residential areas. The OSRAS is currently being trialed in the Hawkesbury Lower Nepean catchment, covering 20 Local Government Areas in the Sydney hinterland with approximately 50,000 on-site wastewater management systems. The large scale pilot study involves the development of a data management system, data integrity review, application of the OSRAS methodology to the Hawkesbury Lower Nepean catchment, consultation with local councils and State Government agencies and field validation, prior to the release of the OSRAS for use in other areas of coastal NSW. 2010-09-14T23:11:34.633Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:6223 A system of falling droplets was investigated for the application of wastewater aeration as it was hypothesised that the system would not be adversely affected by elevated mixed liquor suspended solids. The concept was trialled using a device able to create droplets of different diameters, where the liquid is pumped to a height and allowed to fall through air as droplets. Oxygen transfer into the falling droplets was determined by using de-oxygenated feed water and measuring the dissolved oxygen concentration of samples collected at various fall heights. The influence of droplet diameter on mass transfer was also investigated by using four different droplet size settings. The results were compared with a theoretical model and the droplet diameters produced from both fresh water and brewery waste sludge were measured to determine the effect of a feed liquid containing suspended solids and an organic fraction. The results demonstrated that greater oxygen transfer occurs with larger fall heights however the rate of transfer is greatest at the beginning of the fall. The experimentation and modelling showed oxygen transfer per volume to be higher with smaller droplets. Analysis of the droplet diameters produced with both fresh water and brewery waste water at 10,000 mg/L indicated that the droplet size produced by a liquid containing a live culture and relatively high suspended solids was smaller than the droplet size produced by fresh water. The higher surface area to volume ratio of a smaller droplet results in more efficient mass transfer in the system and indicates that the system can achieve an alpha factor around 1.1. The advantage of the system of falling droplets applied to wastewater treatment is that the system is not negatively impacted by increased suspended solids in the liquor and therefore is able to provide consistent aeration at around 1.35 kg/kWh oxygen transfer efficiency. 2010-05-11T04:20:02.877Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:6168 Part of a large estuary along the eastern Australian coastline (150 kilometres north of Sydney, NSW) used for shellfish production was closed to harvesting for over 18 months. Monitoring in 2005 showed human viral contamination of oyster tissue and surveys of drainage channels and the estuary indicated regular exceedances of standards set for shellfish growing waters, particularly following heavy rainfall. The contamination was attributed to urban runoff, agricultural wastes and failing on-site wastewater systems. In particular there were significant land capability constraints to the on-site dispersal of treated wastewater due to the high groundwater tables and permeable sandy soils. For this reason, and because human viruses were recorded in the shellfish, domestic wastewater systems were considered an important source of the contaminants recorded in the estuary. As part of the current estuary remediation program, the local regulatory authority (Port Stephens Council) required that appropriately sized sand mounds be constructed at sites where systems had been assessed as failing and also at new housing sites with severe land capability constraints due to the high groundwater levels. Two of the sand mound systems have been monitored in detail since midway through 2007 for a period of six months using a variety of soil water samplers and groundwater bores. Water use has been monitored at each property along with a suite of wastewater contaminants in each septic tank, the vadose zone and shallow groundwater. Only some of the monitoring results are presented in this paper, but on the basis of these results, it is clear that the two sand mounds are performing effectively as a treatment system resulting in significantly reduced contaminant concentrations entering the groundwater. There is substantial interest in the overall performance of these systems as little research has been conducted in Australia on wastewater treatment using sand mounds. 2010-05-07T05:30:03.155Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2685 This study presents the impact of including decentralised rainwater harvesting, water efficient appliances and wastewater reuse strategies in analysis of the operation of regional water supply systems. These strategies provide significant reduction in regional water demand, improvement in regional water security, decreases in greenhouse gas emissions and economic benefits. A compelling case has been made for the inclusion of decentralised water management options in analysis of regional water systems. This is a contrast to the normal practice of uncritical dismissal of decentralised options prior to detailed systems analysis. The results indicate that adoption of 3 kL rainwater tanks for hot water and laundry uses, water efficient appliances and estate scale wastewater reuse for outdoor and toilet uses for all new housing, and 3 kL tanks for laundry, toilet and outdoor uses with water efficient appliances at a rate of 1% per annum to existing houses may be optimum. 2010-04-27T06:33:35.557Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2679 The contamination of estuaries in many cases is often attributed to agricultural and urban runoff, as well as failing on-site wastewater systems. The evidence for off-site environmental impacts from large numbers of failing wastewater systems is generally ad-hoc and sparse. Data collected are often ambiguous because the currently used faecal indicators cannot be used on their own to distinguish between human and agriculturally derived faecal matter. In addition, there is difficulty in identifying direct linkages between failing systems and widespread contamination due to effluent dilution, tidal influences and the complex hydraulic connections between surface and groundwaters in estuarine catchments. Part of the Tilligerry Creek estuary along the NSW coastline was closed to shellfish harvesting in mid 2005 as monitoring by SafeFoods NSW had shown human enteric viral contamination of oyster tissues on a number of occasions. The affected part of the estuary remains closed as surveys of drainage channels have regularly detected high numbers of faecal coliform bacteria, particularly following rainfall. In 2006 further investigations were undertaken to distinguish contaminant contributions from various sources (including on-site wastewater systems) in the catchment. Rainfall, drain levels, groundwater levels and water samples were continuously monitored in an unsewered subdivision to determine its contribution to contamination in the estuary. Water samples at three surface drains and a number of groundwater bores were collected and analysed during low flow and wet weather conditions in order to establish firstly, whether there was still contamination in surface and groundwaters, and secondly, if the contaminants were present, whether they had the potential to reach the estuary and be present in estuarine waters. Faecal sterols along with other chemical and microbiological indicators were used to distinguish sources of contamination in the samples collected. These investigations did not indicate that on-site wastewater systems were contributing to contamination in the estuary and that the majority of faecal contaminants found were from agricultural runoff and domestic animals. 2010-04-27T06:33:33.778Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2684 Over the past decade, approaches to improve urban water cycle management have included water-saving devices inside the home, the use of rainwater tanks, reuse of treated wastewater and water sensitive urban design (WSUD) principles to manage stormwater runoff. When several integrated water cycle management (IWCM options are implemented in unison at an allotment-scale, various levels of mains water savings, wastewater flow reductions and stormwater runoff reductions can be obtained. However, few studies in the literature have evaluated the impacts of implementing wastewater options for a non-sewered area already using rainwater tanks and onsite septic systems discharging to the environment. These scenarios are typical of peri-urban communities existing near sensitive coastal/estuarine environments. This investigation primarily reports on wastewater reuse options being introduced to a non-sewered area already using rainwater tanks and onsite septic systems. The PURRS (Probabilistic Urban Rainwater and wastewater Reuse Simulator) (Coombes, 2002) model was utilised to continuously simulate demand management (water saving devices) and the performance of rainwater harvesting and wastewater reuse to explore the reductions in rainwater tank demand, wastewater discharges and stormwater runoff that occur at an allotment-scale. This study highlights how the introduction of wastewater reuse in the study area significantly decreases wastewater flows from the allotment, increases stormwater runoff volumes from the allotment and reduces the efficacy of existing rainwater harvesting systems at the allotment-scale. Significant variations in the efficacy of rainwater harvesting were observed when increasing levels of wastewater reuse were simulated, highlighting the importance of maximising use from the rainwater tank to optimise rainwater harvesting potential, particularly in moderate to high rainfall areas. This is an important insight into the fundamental paradigm of integrated water cycle management. 2010-04-27T06:33:25.779Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2716 Part of a large estuary along the eastern Australian coastline (150 kms north of Sydney, NSW) used for shellfish production has been closed to harvesting for over 18 months. Monitoring has shown viral contamination of oyster tissue on a number of occasions and surveys of drainage channels and the estuary indicate regular exceedances of bacterial standards set for shellfish growing waters, particularly following heavy rainfall. The contamination has been attributed to urban runoff, agricultural wastes and possibly failing on-site wastewater systems. Investigations have been undertaken to distinguish and estimate contributions from various sources of fecal contamination in this part of the estuary, and whether individual on-site wastewater systems can be linked to the recorded surface and groundwater contamination. Fecal biomarkers such as sterol compounds (e.g. coprostanol), along with microbiological indicators, have been used to determine the sources of the contamination. Hydrological investigations involving both surface and groundwater monitoring have also been completed to determine likely hydraulic pathways between the wastewater systems and the estuary. Apart from an isolated illegal on-site wastewater discharge, the principal sources of contamination appear to relate to other landuse activities within the watershed, principally from herbivores. 2010-04-27T06:14:36.072Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2717 Using the Probabilistic Urban Rainfall and wastewater Reuse Simulator (PURRS), this study investigates the variability produced in mains water savings, wastewater flows and stormwater runoff at the allotment scale. Continuous simulation of rainwater harvesting and wastewater systems was performed with different water demands and roof areas on 600 m² allotments in Auckland, Adelaide, Brisbane, Melbourne and Sydney. Results indicate that there is plenty of water available at the allotment scale. For a variety of integrated water cycle management options (IWCM) options, a range of solutions can be obtained for an array of water demands (persons per household) and roof areas. Climatic regimes governing rainfall depth/distribution and water demand distribution are also shown to influence the magnitude of the IWCM options evaluated. This study highlights the benefits of a range of allotment scale IWCM options that result from different climate regimes, water demands and roof areas. The significance of results is that when rainwater tanks and/or wastewater systems are introduced at the allotment scale, there is plenty of water available for all uses. However, the extents of benefits are dependent on climate regime and water demand. In addition, the implications for catchment water resource management are highlighted in the context of perceived water shortages in the future. 2010-04-27T06:14:26.563Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1767 The effect of effluent composition on the efficiency of hydroxide precipitation of Cd(II),using both lime and magnesia as precipitants, has been modelled by the solubility domain approach in order to provide wastewater effluent treatment limits, and has been experimentally validated. Common anionic species such as Cl−, SO4 2− and CO3 2− have been treated. Solubility domain calculations were based on those phases that were found to determine metal solubility or systems representing the upper and lower limits of potential effluent chemical compositions. The isolated phases were found to resemble their mineralized counterparts, although in several cases exhibited a lower degree of structural order. Experimentally determined Cd(II) solubilities were generally encompassed within the calculated solubility domains, indicating that solubility domain predictions provide effluent treatment quality assurance ranges for the hydroxide precipitation process. The formation of gypsum(CaSO4·2H2O) and calcite (CaCO3) at higher SO4 2− and CO3 2− concentrations as secondary precipitates using lime as the precipitant, and the hydroxy-sulfate Mg2(OH)2SO4·xH2O, nesquehonite(MgCO3·4H2O), hydromagnesite Mg5(OH)2(CO3)4·4H2O] and brucite [Mg(OH)2] when employing magnesia was shown to have little effect on the observed residual Cd(II)solubility, although Mg(OH)2 did promote β-Cd(OH)2 formation in the Mg2+-containing Cd(II)/Cl− and Cd(II)/SO4 2− systems. 2010-04-27T06:10:32.938Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1726 On-site wastewater management system design and performance is significant in assessing landslide risk in areas with potential for slope instability. Much of the development in Pittwater, NSW, local government area is on steep coastal land which has a history of slope instability. Concern over cases of poorly performing or failing on-site wastewater systems and the recognition that these and newly designed systems could be contributory to slope instability has been a factor in Pittwater Council, NSW, requiring that landslide risk assessment be undertaken for new and amended on-site wastewater management systems in potentially unstable areas. This paper describes the wastewater management system design and landslide risk assessment undertaken at Pittwater Youth Hostel in accordance with the Australian Geomechanics Society's Geotechnical Risk Management procedure to comply with the Pittwater Policy. The work completed illustrates both necessary and effective interaction of the wastewater and geotechnical professions to achieve a successful outcome for the client. It is likely that this professional interaction will be increasingly common along the NSW coast and elsewhere. Keywords Landslide risk assessment; On-site wastewater management system design; professional interaction 2010-04-27T06:09:58.113Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2916 Geotechnical aspects of domestic on-site effluent systems (septic tanks) and their impact on groundwaters are discussed and the limited relevant literature is reviewed. While there are few Australian case studies, the early stages of an ongoing study at Dodges Ferry, Tasmania, show a connection between shallow aquifer quality, number of residences and domestic on-site wastewater disposal practices. Of 26 groundwater samples analysed, a number fail to meet established criteria for potable use. Most samples were highly or very highly saline. This renders them unpalatable and has an adverse impact on vegetation if the water is used for irrigation. Several samples had pH less than 6.0 and those taken from shallow wells were discoloured by leached soil organic matter. Elevated nitrate levels, an indicator of contamination by sewage effluents, were found at nine locations and these were usually associated with small clusters of residences. One very high sample was clearly contaminated by effluent from an adjacent on-site wastewater disposal system. One odorous, black organic seep was found at the foot of the dunes backing a bathing beach and this gives cause for concern that failing on-site wastewater disposal systems are contributory to reduced bathing water quality. Faecal coliforms and Escherichia coli were not found, even in samples with the highest nitrate concentrations, suggesting that residence time has been sufficient for bacterial die-off. Contamination of shallow aquifers is greatest where there is a high density of residences with small lots. 2010-04-27T06:09:02.111Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:139 The AUSRIVAS modelling package is the most sophisticated rapid biological assessment technique available for assessing the health of Australian rivers. Macroinvertebrate samples are collected, and the observed taxa are compared to those expected to be present if the site was in pristine condition. However, the method relies on only a single sample collected from each site to be assessed. Multiple macroinvertebrate samples were collected from sites upstream and downstream of four wastewater treatment plants in the lower Hunter Valley, New South Wales, Australia, to assess the impacts of effluent discharge on creek health, and to investigate the implications of the within-site variability of AUSRIVAS outputs for impact assessment. Preliminary data demonstrate that the AUSRIVAS model can produce a range of outputs for a single site, and that this variability is then amplified creating greater uncertainty when sites are compared to quantify the actual ecological; impact of each wastewater treatment plant. 2010-04-27T06:00:33.430Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:355 The effect of effluent composition on the efficiency of hydroxide precipitation of Cd(II), using both lime and magnesia as precipitants, has been modelled by the solubility domain approach in order to provide wastewater effluent treatment limits, and has been experimentally validated. Common anionic species such as Cl-, SO42- and CO32- have been treated. Solubility domain calculations were based on those phases that were found to determine metal solubility for systems representing the upper and lower limits of potential effluent chemical compositions. The isolated phases were found to resemble their mineralized counterparts, although in several cases exhibited a lower degree of structural order. Experimentally determined Cd(II) solubilities were generally encompassed within the calculated solubility domains, indicating that solubility domain predictions provide effluent treatment quality assurance ranges for the hydroxide precipitation process. The formation of gypsum (CaSO4 center dot 2H(2)O) and calcite (CaCO3) at higher SO42- and CO32- concentrations as secondary precipitates using lime as the precipitant, and the hydroxy-sulfate Mg-2(OH)(2)SO4 center dot xH(2)O, nesquehonite (MgCO3 center dot 4H(2)O), hydromagnesite [Mg-5(OH)(2)(CO3)(4) center dot 4H(2)O] and brucite [Mg(OH)2] when employing magnesia was shown to have little effect on the observed residual Cd(II) solubility, although Mg(OH)(2) did promote beta-Cd(OH)(2) formation in the Mg2+-containing Cd(II)/Cl- and Cd(II)/SO42- systems. 2010-04-27T05:47:01.920Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:638 On-site wastewater management system design and performance is significant in assessing landslide risk in areas with potential for slope instability. Much of the development in Pittwater, NSW, local government area is on steep coastal land which has a history of slope instability. Concern over cases of poorly performing or failing on-site wastewater systems and the recognition that these and newly designed systems could be contributory to slope instability has been a factor in Pittwater Council, NSW, requiring that landslide risk assessment be undertaken for new and amended on-site wastewater management systems in potentially unstable areas. This paper describes the wastewater management system design and landslide risk assessment undertaken at Pittwater Youth Hostel in accordance with the Australian Geomechanics Society ' s Geotechnical Risk Management procedure to comply with the Pittwater Policy. The work completed illustrates both necessary and effective interaction of the wastewater and geotechnical professions to achieve a successful outcome for the client. It is likely that this professional interaction will be increasingly common along the NSW coast and elsewhere. 2010-04-27T05:37:53.836Z ]]>