Any substance which can no longer be utilized again by the proprietor and which is discarded at the end can be termed as waste. (R. Taylor and A. Allen). Solid waste include garbage, sewage sludge, ashes, discarded metal, trash on any solid or semi solid material resulting from domestic, industrial, commercial, agricultural operations or from community activities.
Managing solid waste disposal has been of great concern from the time when people start to live together in large permanent settlements.(T. JANAKIRAM and K. SRIDEVI 2010) Therefore if waste is not disposed off properly and safely, it may pose health problems and pollute the environment. (Zhu et al., 2008). Solid waste management involves every single activity which reduces the health and environmental impacts of solid wastes produced by household sectors, commercial, industrial, healthcare sectors, agricultural activities. (R.Kapoor 2010). It is an undeniable fact that the boosting population and economic development is resulting in an alarming increase in municipal waste generation rates. (Yongping Li1 and Gordon H. Huang 2007).
There exist many processes that take place to enhance the waste management system. According to Yongping and Gordon the main processes are waste collection, transportation, treatment, and disposal and these processes are carefully revised by the decision makers.( Yongping Li1 and Gordon H. Huang 2007 adopted by Wilson 1985)). Furthermore studies from several profound literature reviews reveal that the types of collection techniques to be used, service level to be offered and adopted and various types of waste processing system also play a significant role for the betterment of the waste management system.
An integrated MSW management system includes numerous waste-management amenities to meet the overall demand, to process, treat and dispose waste. These facilities comprise of transfer-stations, landfills, incinerations, composting and recycling. The daily waste-generation quantities, facility capacities and waste collection and treatment cost, as well as their interrelationships are uncertain. (Yongping Li1 and Gordon H. Huang 2007, Yongping Li and Guohe Huang 2009). Such uncertainties differ in different time period and exit in multilayer and multi-objective system component which affect waste collection. Moreover these uncertainties amplify since many activities and system components are connected with economic penalties for e.g the policies, procedures or law being violated. As the trend of uncertainties keep on increasing, it becomes difficult to meet the overall solid waste disposal demand due to insufficient capacities of waste-management. (Yongping Li1 and Gordon H. Huang 2007). According to Yongping and Guohe an effective planning effort can as a catalyst for sustainable socioeconomic development throughout the globe though the idea of planning effectively seems complex. (Yongping Li and Guohe Huang 2009)
Poor solid waste management practices do not create a good impression on the foreign investors and tourists. This lessen investment and revenues from these sources. (R. Kapoor 2009). Mismanagement and non-availability of good waste collection and disposal facilities also lead to psychological stress and fear of health risks (R. Kapoor 2009 adopted from Petts and Eduljee, 1994; Becker, 2001). This explains why in many countries the Government extensively recognises the importance of sorting the problem of municipal solid waste and seeks ways to stem the adverse effect.
Collection, transfer and transportation of solid waste
Waste collection is the process from which waste is being collected from the sources to the treatment plant, transfer station or final disposal point. Garbage trucks collect waste from house to house, or at kerbs side collection. The waste are either left in the waste containers or recycling bins that are aftermath being collected by the waste collectors using the waste collecting machine. Most of the waste are being collected by municipal lorries and garbage trucks and are being disposed to dumping area in large capacity lorries. The semi mechanised waste collection method is used in places where large vehicles cannot enter narrow lanes.(S. Lotfi et al 2007). When the municipal lorries or garbage trucks arrive at the transfer station, they tip the collected refuse on a tipping floor where the large capacity trucks transport the refuse to the landfill for final disposal.( Harold J Yaffe 2001).
Since collection and transportation of municipal solid waste incur lot money, the waste management calls for improvement. The size of the lorries and trucks, the distance travelled and the path must be well considered. Deviation of the engine power demand, different amounts of fuel consumption and emissions depend on the engine performance, efficiency and also by the road slope. Thus these factors need to be taken into consideration in waste collection and transportation (from by Tavares et al. (2008)
Fuel consumption during waste collection and transportation is subjective by the travelled distance, the actual operation conditions of a given vehicle, type of the driving situation, the vehicle load and the road gradient.(Gilberto Tavares et al 2008 adopted from Ntziachristos and Samaras (2000)
It is essential to account effect of the vehicle load and road gradient for heavy vehicles. Therefore, and because of their large masses, the power employed during the driving is the crucial factor for the fuel consumption (by Gilberto Tavares et al 2008)
Seeking a place for waste disposal is a difficult problem as it includes an extensive planning and consideration about the selection of disposal location, environmental constraints, ground water protection, land use and transportation and also it must include the different views of the public. (by Richason and Jonson 1988, Van Zeeand Lee 1989)
A transfer station is a provisional deposition of solid waste. Transfer stations serve as places where local waste collection vehicles deposit their waste before loading them into larger vehicles. These larger vehicles in turn transport the waste to for final disposal in an incinerator, for recycling or landfill.
A landfill is a site for the disposal of solid waste material. Landfill is the most common, simplest, cheapest and cost effective methods of waste disposal (Barrett and Lawler, 1995). Solid waste from transfer station is being dumped into the landfills. In many low income countries, almost all of their generated waste is landfilled.
Health and Safety Hazard with waste management
The process of waste management which comprises of collection, processing and disposal of waste have both an impact on both the health of the public and the environment. Waste may be inherently hazardous to health due to its complexity and of various mixture characteristics.
As a matter of fact due to its impending health effects inherent in the waste and the associated with their management, it has been an issue of a vast body of research.
From 1992 to 1997 the occupational fatality rate in the United State was 46 out of every 100,000 refuse collectors and this demonstrate that waste collection is a deadly occupation as it is 10 is times higher when compared with all other workers( Drudi D, 1999 adapted from Hermando R. Perez et al, 2006). The mortality rate of drivers and helpers employing in the collection of Municipal Waste are found to be an average of 90 out of every 100,000 workers each year ( Englehart et al, 2000 adapted from Hermano R. Perez et al, 2006). Adding to the high numbers of associating mortality due to waste collection, there is a also a considerable rate of non- fatal injuries experienced in waste collection such as back injure (17, 9%), Knee injury ( 12, 3%), hand injury (12,3 %) and foot injury(11,4 %). (Evens et al, 1998, adapted from Hermando R. Perez et al, 2006)
In the studies of Municipal waste management a broad range of organic dust has been found and this have a negative impact on the respiratory conditions to those exposed and researchers have found that those workers engaged in the handling of waste account for a higher risk of developing various form of respiratory problems when compared with the whole population (Rutner- press C, 1976).
From the Danish ROAD database an analysis has shown that the risk of developing gastrointestinal problem is higher with refuse collectors out of the Danish workforce population (Poulsel et al, 1995, adapted from Hermando R. Perez et al, 2006). In another study, 1747 waste collectors and 1111 individuals as controls were taken to show the effect of their occupation on their digestive system. The result demonstrates that the waste collectors have a higher occurrence rate for nausea and diarrhea than the control (Ivens et al, 1997 adapted from Hermando R Perez et al, 2006).
Safron et al, 2003 of the Centre for Research in Environmental system, Pollution and Remediation of the University of West England, Bristol, UK have conducted a research which aims to show an objective assessment of the epidemiological evidence from the public health relating in the waste management process. In their study they arrived to the conclusion that most of the epidemiological studies that have been linking waste management and health conditions are based on weak or non-existent exposures data. Hence this demonstrates that those studies which have been made were rarely based on quantitative environmental measurement and on the individual at the time of exposure.
Jean Overview of transfer station
H&S hazard associated with transfer station
The causal health and safety risk factors in a waste transfer station include prohibited or unauthorized waste materials, fire, odors, disease, vectors, noise, dust, and litter. Waste Pickers and collectors are considered poor as they are unable to eke out the bare minimum for their survival. They earn their living by selling collected waste from the solid waste transfer station for recycling at low prices. (YUJIRO HAYAMI*, A. K. DIKSHIT, & S. N. MISHRA October 2004). On doing so, they endure risks of being bitten from animals and vectors such as dogs and rats. They are also exposed to noisy environment. Moreover they are exposed to noxious substances, faecal matter, body parts, used syringes and other detrimental materials found in the waste. Besides pickers suffer from ergonomic problems mainly musculoskeletal disorders (MSDs) due to the heavy manual handling and awkward postures(Anne Scheinberg Justine Anschütz 2006 adapted from van Eerd 1996; Simpson-Hebert et al. 2005) amd to noise problem.
Noise
The main sources of noise from a transfer station are due to the heavy vehicles traffic and the operation of heavy-duty facility equipment (by Nil-Bin Chang et al 1996). Offsite traffic noise near transfer station's neighborhood is also considered as a source of noise. Waste transfer stations make use of stationary solid waste compactors or engine-driven tamping equipment which multiply the effect of noise. Equipment noise comprises of engines, backup alarms (beepers), hydraulic power units, equipment buckets, blades banging and scraping on concrete and steel surfaces. Furthermore the unloading of waste onto a tipping floor, pit, steel drop box, or trailer can also generate considerable noise depending on the type of waste, fall distance, and surface. Sometimes the intensity of noise is so high that this cause employees, waste pickers and customers not to hear instructions or warnings or the noise from a forthcoming hazard.
Air Emissions
Air emissions at transfer stations result from dusty exhaust. Mobile equipment such as trucks and loaders, driving on unpaved or dusty surfaces, and cleanup operations such as street sweeping generate wastes delivered to the transfer station. Tipping areas have localized air quality problems that amount to a safety and health hazard. Activities carried out there produce clouds of airborne 'bugs' and dusts which are inhaled through the lungs causing permanent damage to breathing.
According to Krystal J. Godri et al (april 2010), high exposure to ambient particulate matter (PM) lead to cardiorespiratory problem due to the dust laden atmosphere and the heavy- duty diesel vehicles transporting the waste. However the latter and his friends could not prove whether the health problems are simply due to the densely inhabited community which also contributes extensively to amplify the PM exposures or whether from the toxicity of PM generated from WTS-related.
Vectors
Vectors such as rodents, insects, rats and scavenging birds have the potential to spread diseases. Waste present and stored for extensive periods of time in the transfer station serve as food sources for the vectors. (BHR CIVIC GROUP 2009). Exposure to rat urine poses a high risks to the health of people working in the waste transfer station.
Traffic
Traffic poses a significant offsite environmental impact related with larger waste transfer stations. Although rural stations normally receive less vehicle movements the routes are affected by the large vehicle traffic. (United State environmental protection agency). There exist high risks of overturning due to overloading of lorries coming for waste disposal to transfer station. Overloading of waste also lead to potentially cause people to fall from the trucks or lorries since the waste is slippery.
Water Quality
When runoff contacts waste, it is considered potentially contaminated and is known as "leachate." Most transfer stations send some amount of waste water to sewer systems. In addition to leachate, waste water from daily cleaning of the waste handling areas and the facility's restrooms and support areas typically are discharged to the sewer.
Garbage
In many developing countries, waste collectors collect waste from the street and deposit the waste in transfer stations where waste pickers seek food or recycling materials. According to C. Alvarado-Esquivel1 et al (2008) Toxoplasma gondii infection is significantly higher among waste pickers and collectors in the Durango City of Mexico than other populations due to high exposure to contaminated garbage and poor hygiene practices. However there is no information available in his study about the epidemiology of Toxoplasma gondii inflection in people exposed to municipal waste.
Falls
Accident due to falling from height is another potential hazard that exit in a transfer station. Standing and walking on loads to either sheet or trim the load can cause the worker to fall, slip or trip in the load.
Ergonomics
The waste transfer station is also accountable for major manual handling injury due to improper body position, repetitive motion, and repeated or continuous exertion of force contribute to injuries. (from waste industry health and safety-HSE). Handling of heavy waste and repetitive tasks lead to musculoskeletal disorders. These further multiply the health and safety risks to which waste pickers and employees working at the waste transfer station.
R.A of health and safety hazard
Risk has been defined as the likelihood that a particular event will lead to an adverse outcome - most commonly, the ultimate consequence of a risk is death (Ritter, 1981; Wilson, 1984). In this context, it is not appropriate to limit the definition of risk to either probability or magnitude of the ensuing consequences of the risk. For a more complete definition, the product of the probability and magnitude of the consequence of the risk is often preferred. The NRC (1975) has developed a model that simulates the particular environment being examined and studied, whereby it computes the outcomes and their frequencies as per the model's outputs.
The above definitions aim at providing a brief overview of the term "risk", which leads to the formulation of definitions and understanding of the risk assessment. The most universal and simplistic formula accepted formula for risk computation uses the multiplication of frequency or rate of occurrence and the level of impact, to give the level of risk. A simple way of overlapping the likelihood and the consequences of hazards is by using a risk assessment matrix (Government of South Australia, Department of Education and Children's Services, Health&Safety Services, June 2006; Government of South Australia, Department of Education and Children's Services, September 2008). This is often used as a format in which the risk assessment process is easily readable and observations are noted and compiled.
Phil Hughes (2009) gives two options for going about the risk assessment process- there are two form of risk assessment which may be used separately or combined to give an optimal end-result. Quantitative risk assessments involve evaluating the risk by denoting the probability of the occurrence of that particular risk and combining it with the potential severity or nature of the consequences, which is finally given a numerical value. On the other hand, the qualitative risk assessment relies on personal perception and judgement, and is usually denoted by categories such as high, medium or low, often in the form of a risk assessment matrix compartmentalized in terms of risks, consequences, likelihood, amongst others.
In a study undertaken for the publication of his book, Vincent T. Covello proposes a generic definition he has adopted, wherein the risk assessment would be characterized by a stepwise procedure aimed at describing and quantifying the exposure to risks, be it directly or indirectly, involving harmful products, events, activities and processes. This definition encompasses the health and safety aspects and converges the risk aspect to the potential harmful health, safety and environmental effects as well as the ambiguous nature of the risk related to is probability of occurrence, frequency, duration, intensity, size or magnitude. However, there is much divergence in the approach to risk assessment - while some researchers and authors lay emphasis on the fact that risk assessment should be a separate and integral process in itself, others might view the process of risk assessment as a component of the risk analysis. Indeed, in his book, Vincent T. Covello specifies that the risk analysis consists of three basic steps, namely, hazard identification, risk assessment, and risk evaluation. The risk assessment itself consists of four levels: release assessment, exposure assessment, consequence assessment, and risk estimation.
Method of risk assessment
There are various risk assessment methods that may be used in different contexts and types of organizational settings. However, all risk assessment methods have several steps in common as stated by Bruce W. Main. An identification of the existing and potential hazards is first carried out, the different levels of risk are then assessed, then the means and methods of reducing the risks are devised and implemented, and finally, the computations of risks are presented and documented in an acceptable format. Bruce W. Main further explains that the identification of hazards is the most fundamental part of the risk assessment process since it the determination of all the existing and potential hazards is the only way to provide a complete assessment of all risks involved - missing any hazard during this process will mean that the risk assessment will be incomplete, leaving room for existing hazards and risks combining to form accident-prone settings. The computation of risks by allocating risk levels or scores is known as a "Risk Scoring System", whereby risks are assessed depending on several factors; the risk scoring systems selected may differ and may range from qualitative, semi-quantitative and quantitative. Thus, the appropriate one for the particular organizational setting must be identified, based on the various factors involved and the extent to which they are quantifiable. According to Bruce W. Main, there is a divergence of risk assessment methods, which one should not get confused by and consequently detract from the original aim. According to him, the generic term "risk assessment" may refer to the precise steps involved in determining and calculating a risk level and assigning a risk score, while it may also be a nonspecific term to describe the overall process, or to refer to any method that assesses risks.
D.W. North (1995) explains the term risk assessment as being the categorization of risks in terms of the probability and severity of the aftermath of a particular risk when it has not been controlled or eliminated. This calls for a mathematical and scientific analysis of specific hazards and their risks with quantifiable results that will enable, as well as facilitate judgement in the analysis of risks. He states that although some of the data and information might not be available at some point, the assessors must take into consideration all the elements that have been gathered and which pertain to the risks involved but must eventually rely on their own perceptions. The perception of risk as been addressed in some researches (Paul Slovic, 1987). The critical determination of judgmental probabilities is, according to D.W. North (1995) most accurately carried out by going through a stepwise assessment of the risk probabilities for each hazard. As he proposes, the different levels or degrees of severity pertaining to the repercussions of a dangerous occurrence or disaster, as it may be, must be classified so that the assessor may easily determine which hazards have the most serious impacts. However, he states that these risk assessments provide no easy means of discerning the hazards in all respects, and unless the identification of hazards is complete, the risk assessment results and conclusions may still prove to be lacking.
As Božo Nikolić and colleague (2009) have mentioned, although there is no one bad risk assessment method, it is nevertheless true that some models of risk assessment are preferable to others. It is a matter of stating the risk assessment method chosen right from the start to avoid complications and ambiguity. The method proposed by Božo Nikolić and colleague (2009) ensures that the risk assessment surveys carried out produce quantifiable values, even for qualitative information - Risk Assessment Acts (Nikolic & Laban, 2008). A stratification of steps is proposed while ensuring that the first and basic issues of general survey of the organization, its processes and activities carried out, the categories of persons involved, and other such aspects, are all covered. Based upon the hierarchy of controls, the recognition and identification of the different hazards and their potential impacts is the key to starting the process. The risk assessment is then carried out, while taking into consideration the various hazards and their effects if not controlled. The means and measures for the elimination, reduction and proactive prevention strategies must be implemented. Once the above steps have been carried out, there is a need for a risk reassessment which will see to the hazards that have not been eliminated after the first attempt to control them. There must be a conclusion from the steps already implemented and the status of the resulting situation until a deeper set of means and measures is further dealt with to reach or maintain the desired risk levels as thought to be acceptable.
Such a risk assessment will ensure a proper and detailed means of evaluating the existing risks, their potential impacts and aftereffects, while enabling the assessor to determine and suggest control measures to minimize the level of risk as deemed appropriate in such a case. The risk assessment method chosen should combine the description of hazards and their effects, the weaknesses of the existing procedures in place, the different stakeholders, and a system of risk classification or categorization. Božo Nikolić and colleague (2009) propose two techniques and approaches for the risk assessment, whereby the first consists of using an already established method comprising of tables and quantitative figures of the variables to be considered during the risk assessment, such as the likelihood of occurrence (P), the frequency of exposure to the hazard (F), the degree of possible harm (H), and the number of persons exposed to the hazard (N).
Such a technique encompasses the different workplaces and is thus applicable to any work system or setting
It defines four categories of risk levels, which can be altered depending on the user's objectives and the applicability of the risk levels; negligible, low but significant, high, unacceptable. Then, risk is computed and mathematically calculated from the following formula:
R = P * F * H * N
The second approach attempts to form a matrix of risk by combination or multiplication of probability and consequence. Probability is created as a matrix of safety assessment and frequency.
Referring to Manahan (2005), Michaela Bobeck (June 2010) examines the effects on occupational safety and health aspects of solid waste, whereby the pervasiveness and spread of polluting factors are based on the characteristics and individual, as well as combined, properties of the wastes and the environmental settings of waste disposal. The process of degradation of organic matter in solid waste disposed of, and transiting through waste transfer stations is an issue that demands the attention of all in the aim of limiting the associated risks. Another aspect which should not be forgotten is the contamination of nearby water resources or underground water when stormwater carries away leachate and other contaminants that are exposed in open air at the transfer station. Soil pollution, air pollution, and vectors or rodents using the transfer station as breeding grounds must also be taken into consideration. Thus, the risk assessment conducted should also take into consideration all these factors in their individual settings for an unbiased and valid result.
Daniela Bleck (2010) identified some aspects of the activities of waste transfer stations in which the handling of mixed wastes containing a major percentage of ashes and organic materials would lead to health risks, related to the exposure to airborne organic dusts via inhalation. Moreover, it is evident that the exposure to hazardous substances that may not easily be classified due to their components that are often difficult to segregate and analyze, is ever-present. Other problematic areas include the various musculoskeletal disorders that arise due to inappropriate and poor techniques of manual handling of heavy loads, as well as other factors that cause unnecessary forces on the muscular and skeletal system. Daniela Bleck (2010) proposes that there are means of assessing health risks during lifting operations by using the Key Indicator Method by BAuA (2001). This method involves recording and allocating scores or ratings to specific risk factors that have been identified. Depending on the frequency of lifting operations or the rate of lifting tasks, the time spent holding the load, as well as the carrying distance, time rating points are then allocated to the risk factors that have been identified.
Then, rating points are assigned for the particular weight of loads being handled during lifting, holding, and carrying activities, including the body posture adopted by the workers throughout the tasks. Then the overall working conditions and work settings are analyzed and conclusions based upon the whole observations are compiled. The time rating points are computed and multiplied with the results obtained to produce a risk score; this risk score is then stratified in a range starting from one to four, wherein will lie the different risk levels that are noted for the risk assessment.
In every workplace, the hazards and risks present must be controlled so as to allow the minimum level of risk in an aim to have a zero accident scheme; this is the very baseline of all health and safety programmes in all workplaces. The determination of the effectiveness and acceptability of level of risks must be done by a proper risk assessment since these are the most useful evaluation tools. The conclusions of the risk assessment will be based upon individual susceptibility, albeit the quantified and stratified levels of risk. There has not been much detailed research done on the risk assessment carried out at waste transfer stations, and the few case studies are limited to specific aspects, rather than a global perspective.
Objectives
