Cara Beal | Griffith University (original) (raw)

Papers by Cara Beal

Sustainable Production and Consumption, 2016

On-Site Wastewater Treatment X, 21-24 March 2004, 2000

ABSTRACT Septic tank - soil absorption systems (SAS) are the most common form of onsite disposal ... more ABSTRACT Septic tank - soil absorption systems (SAS) are the most common form of onsite disposal technology in Australia (approximately 225,000 in Queensland alone). Hydraulic failure of SAS is often reported. However, there is still a lack of substantiated knowledge on the key processes of SAS in Australian soils. The onsite wastewater industry seems to have an empirical approach to the design of absorption systems, not withstanding the best available advice contained within AS/NZS 1547:2000 - a standard for onsite wastewater management jointly developed by Australia and New Zealand. In this paper, we describe the hydrology and biogeochemistry of soil absorption trenches from basic soil physics principles. The hydraulic behaviour of SAS and role of the biological layer (biomat) is discussed. We also show, using simple numerical modelling, how the interaction of biomat resistance with soil hydraulic properties determines long-term acceptance rate (LTAR). Our findings are similar to Bouma (1975), in that a two to three order of magnitude variation in saturated soil hydraulic conductivity collapses to a one order of magnitude variation in LTAR.

Resources Conservation and Recycling, May 31, 2012

Carragher, BJ., Stewart, RA., Beal, CD., (2012) Quantifying the influence of residential water ap... more Carragher, BJ., Stewart, RA., Beal, CD., (2012) Quantifying the influence of residential water appliance 1 efficiency on average day diurnal demand patterns at an end use level: A precursor to optimised water service 2 infrastructure planning. Resources Conservation and Recycling 62,[81][82][83][84][85][86][87][88][89][90] 3 4

A methodology for the estimation of household potable water saving due to internally plumbed rain... more A methodology for the estimation of household potable water saving due to internally plumbed rainwater tanks (IPT) is presented in this paper. The methodology is based on a pairwise comparison of household water billing data between homes with IPT and without rainwater tanks (No Tank). These savings were compared with estimations using measured end use data and rainwater demand predictions using the Rainwater TANK model. The paper describes the application of this methodology to a case study in the south-east Queensland (SEQ) region of Australia. There was a significant reduction in mains water consumption for IPT properties in all regions studied in SEQ. Water reductions from mains supplies varied markedly across regions with mean values ranging from 20 to 95 kL/hh/y with an average mean of 50 kL/hh/y. Median water consumption values, ranged in mains water reductions from 28 to 52 kL/hh/y, with an average median of 40 kL/hh/y. Considering both measures an average water saving between 40 and 50 kL/hh/y can be expected from internally plumbed rainwater tanks. Water restrictions appear to have a strong influence on estimated reductions in mains water use. In regions where water restrictions were severe, water consumption was less varied between No Tank and IPT homes with a consequent reduction in estimated savings observed. Recommendations for further work include a survey to capture confounding factors that could not be fully controlled in the desktop study and a controlled pairwise experiment to monitor water consumption from raintanks.

Water (Australia)

Essentially, there are two overarching demand management strategies employed to achieve efficient... more Essentially, there are two overarching demand management strategies employed to achieve efficient water consumption in the residential sector. These are: targeting water use behaviour change ("mind") and promoting the use of water-efficient technologies ("machine"). Using detailed water end-use data and qualitative methods, this paper describes the role that each of these strategies has played over the last few years, using data from 250 residential properties located in the south-east corner of Queensland.

This paper presents results from a 'census' of the status of on-site wastewater treatment... more This paper presents results from a 'census' of the status of on-site wastewater treatment systems (OWTS) management practices in the SEQ region as part of the Healthy Waterways initiative. The current number of on-site systems is estimated to be 127,000 with septic systems accounting for 80%. Key management issues were highlighted during the project, notably the frequency of greywater failure and inappropriate greywater discharge. Septic system failures were reported mainly in the newer combined septic systems that receive 100% of household water compared with the split blackwater systems that receive about 20%. Aerated systems were inadequately maintained. However, to date, no "smoking guns" of poor water quality from non-sewered catchments have been clearly identified. A clear outcome of this survey was the need for all SEQ Local Authorities to audit every on-site system. Predictions and assessment of catchment water quality risks from on-site systems would be gr...

The mechanisms governing hydraulic failure of septic tank soil absorption systems (SAS) are not... more The mechanisms governing hydraulic failure of septic tank soil absorption systems (SAS) are not well understood. The low permeable biomat zone that develops on the infiltrative surface is a key component of the hydraulic and treatment performance of a SAS. In this study, the hydrology of SAS, including biomat development, the role of soil texture and key effluent flow pathways, was investigated. A survey of 19 councils in south-east Queensland was undertaken to obtain data on aspects of SAS management, and to identify the number and type of SAS failure rates. A survey of this nature had not been carried out in Queensland before, and it illustrated the importance of field inspections of every non-sewered allotment to achieve meaningful compilation of data. The number of on-site systems (in 2003) was estimated to be 127,000 with septic systems accounting for approximately 80%. Over 75% of SAS were split systems (separate greywater/blackwater treatment). A common SAS failure was surc...

ABSTRACT Prosperous cities must be able to respond to future pressures from increasing population... more ABSTRACT Prosperous cities must be able to respond to future pressures from increasing populations, climate variability and climate change while maintaining adequate water services for residents and businesses. Based on dwindling water supplies (due to droughts and changing rainfall patterns) and projected increasing demands, the management of water resources has become a major concern for residential consumers, industry and all levels of government. Many water constrained cities have recently embraced a combination of initiatives to reduce demand (e.g. installing efficient appliances and undertaking water recycling) and have begun increasing sources of supply through the installation of rainwater tanks and the construction of desalination plants. Such changes to water supply sources and patterns of demand mean smarter approaches to urban water management are required to achieve a sustainable water future; the era of urban water planning that is highly focussed on how to build and supply water has passed. The ever-changing water supply system demands adaptive and innovative management fed by robust information. Currently, governments and public utilities are investing significant funds in the development and implementation of water strategies in order to ensure future water demands are met. Demand management strategies include water restrictions, rebate programs for water efficient devices, water efficiency labelling, water conservation or education programs and pressure and leakage management (Inman and Jeffrey 2006). Source substitution or ‘fit-for-use’ water involves replacing specified potable end-uses, such as toilet flushing and irrigation, with recycled, grey or storm water. Water savings achievable from such programs are calculated through a variety of assumptions but, once in place, limited consideration is given to determining the actual water savings associated with these strategies. The potential of the aforementioned diversified demand management strategies depends on their scale of implementation (Figure 1). The size of the ‘bubble’ in Figure 1 represents a measure of relative savings potential at the relevant scale (either smaller or larger), with more than half of these measures depending on intelligent metering technology to achieve or effectively monitor their potential. For example, to implement time-of-use or drought pricing, a real-time signal on water use is needed for consumers and utilities. Intelligent meters, which can discern end-uses, can also play an important role in detecting leaks in existing dwellings (Britton et al. 2008).

We are at the dawn of a new era of widespread intelligent water metering delivering live consumpt... more We are at the dawn of a new era of widespread intelligent water metering delivering live consumption data to utilities and consumers in developed nations. As with most new technologies, intelligent metering will follow a type of hype cycle, where initial excitement and great expectation on its benefits is weighed down by disappointment and disillusionment from early adoptions and then strategic enlightenment will prevail and ultimately productive strategic implementation. Fortunately, the conservative nature of the water industry and the challenges of intelligent metering implementation have meant that the excitement never reached fever pitch and the sensible path to strategic enlightenment is being progressed, albeit very slowly. While the large multi-national metering and software companies have created a range of products and software systems for utilities to automatically collect, store and present reports on customer and citywide water consumption data, a plethora of informatic...

Water efficient appliances are proven measures of reducing householders' peak water demand on... more Water efficient appliances are proven measures of reducing householders' peak water demand on cities' mains water supply network and consequently provide benefits to the water provider, in terms of augmentation deferrals and reduced sized infrastructure. However, while acknowledged in the literature, the actual benefits have not been thoroughly investigated and quantified. The paper aims to demonstrate how the installation of water efficient appliances would affect the design of the water supply network. Using an updated methodology incorporating end-use data from smart water meter, peak day water demand profiles were developed for the baseline scenario (Scenario A), representing the typical building code mandated for new dwellings constructed in the region of Queensland, Australia, and for households fitted with higher efficiency water appliances (Scenario B). Hydraulic model runs were conducted for both scenarios over various planning horizons to determine the scheduling o...

Septic systems have a mixed reputation both with the Australian public and regulatory authorities... more Septic systems have a mixed reputation both with the Australian public and regulatory authorities. There is a general belief that they are an outdated and substandard means of on-site wastewater treatment. In this paper we explore the evidence for the sustainability of on-site systems using contamination of surface and groundwaters as primary criteria. Overall we show that despite consistent reports of a high (e.g. ≥20%) incidence of failing septic trenches, evidence for off-site impacts ranges from sparse to ambiguous at best. To help fill in experimental data gaps we discuss modelling results reported by both ourselves and others, that place contaminant exports (in particular N, P and faecal coliforms) in the context of likely export loads from existing land uses and increasing urbanisation.

Energy and Buildings, 2014

Residential water heaters in Brisbane, Australia: thinking beyond technology selection to e... more 2014) Residential water heaters in Brisbane, Australia: thinking beyond technology selection to enhance energy efficiency and level of service. Energy & Buildings, 82,[222][223][224][225][226][227][228][229][230][231][232][233][234][235][236] http://dx.

Resources, Conservation and Recycling, 2015

sa (A.A. Makki); 20 r.stewart@griffith.edu.au (R.A. Stewart); 21 c.beal@griffith.edu.au (C.D. Bea... more sa (A.A. Makki); 20 r.stewart@griffith.edu.au (R.A. Stewart); 21 c.beal@griffith.edu.au (C.D. Beal); 65 determinants, drivers and predictors of water end-use consumption, and outlines the key 66 implications of the research to enhanced urban water planning and policy design. 67 68 Keywords: water end use consumption; water micro-components; smart meters; water 69 demand forecasting; water demand management 70 71 72 73 130 2012; Willis 2011; Willis et al. 2011b, 2013). Moreover, such detailed knowledge about 131 water consumption can improve understanding of the key determinants of each end use to 132 form the basis of water consumption predictions and the development of improved demand 133 forecasting models (Blokker et al. 2010; Stewart et al. 2010). The development of such 134 forecasting models at an end-use scale is vital, but essential micro-component level models 135 created from detailed empirical water end-use events data registries (i.e. micro-level bottom-136 up models) (Kenney et al. 2008; Willis et al. 2009c) are currently lacking. Improved 137

Theory and Practice, 2013