Landfills can be regarded as a particular type of contaminated land that has a potential to directly and indirectly pollute all of the four main spheres of the environment which are the lithosphere, atmosphere, hydrosphere and eventually adversely impact the biosphere. Therefore, environmental risk assessment of a landfill has to be more integrated and holistic by virtue of its nature of being a multidimensional pollutant source. Despite this, although various risk assessment approaches have been adopted for landfill waste disposal sites, there are still wide-ranging knowledge gaps and limitations which need to be addressed. One important knowledge gap and limitation of current risk assessment approaches is the inability to fully identify, categorise and aggregate all individual risks from all combinations of hazards, pathways and targets/receptors (e.g. water, air, soil and biota) in connection to a certain landfill leachate and yet at any stage of the landfill cycle. So such an approach is required that could not only integrate all possible characteristics of varying scenarios but also contain the ability to establish an overall risk picture, irrespective of the lifecycle stage of the landfill (e.g. planning stage/pre-operation, in-operation or post-operation/closed). One such

Despite landfills having the potential to pollute the environment both during their operation and long after they have ceased to receive waste, they remain a dominant waste management option, particularly in the UK. In order to combat the environmental pollution caused by landfills, risk analysis is increasingly being employed through computer models. However, for a risk analysis process to be successful, its foundation has to be well established through a baseline study. This paper aims to identify knowledge gaps in software packages regarding environmental risk assessments in general, and especially those that have been developed specifically for landfills and landfill leachate. The research establishes that there is no holistic computer model for the baseline study of landfills, which risk assessors can use to conduct risk analyses specifically for landfill leachate. This paper also describes a number of factors and features that should be added to the baseline study system in order to render it more integrated -thereby enhancing quantitative risk analysis, and subsequently environmental risk management.Keywords: baseline study; preliminary investigation; computer models; software packages; landfill leachate; risk analysis; risk assessment; waste disposal sites. BACKGROUNDThe advent of the industrial revolution led to the expansion of human populations and urban living, which in turn drove increasing economic growth at national and global levels. Unfortunately, this increasing prosperity resulted in ever-greater quantities of waste being generated. There is a link between economic growth and waste and this link is still evident today as industrial, commercial, and domestic waste streams. Waste is the inescapable outcome of the activities which 3 characterise human society; indeed in one sense it is an indicator of the health of modern economy (Tromans and Stiles, 2004). A most recent evidence of strong and directly proportional relationship between economic growth and waste generation is the deceleration impact of the current economic downturn on the amount of waste. Statistics in the USA alone indicate that waste generation had always been escalating until 2007, when the downturn struck. In the years following 2007 the generation of waste has reduced (EPA, 2010). The same has been the case in the UK in various sectors (MBD Ltd., 2011).There are two main issues regarding waste. One is the amount of waste that is generated, and the second is how it is dealt with or managed -where landfilling still is the most predominant waste management option (among others that include re-use, recycling, composting, and incineration). Regardless of the economic downturn impact, due to increasing environmental legislation and socio-environmental pressures, overall reduction has been noticed on both fronts of waste -that is, in the generation of waste as well as in the amount of waste that is landfilled in various regions, states and countries. However, this is not the case everywhere around the world.Furthermore, the ...