Analysis Of The Mare Chicose Landfill Environmental Sciences Essay

The purpose of this research was to have an overview of how a landfill is being managed. To be more knowledgeable of the techniques that is being put in practice for a good management. In addition, to identify the negative effects of landfill to workers, the population and environments.

A site visit at Mare Chicose Landfill was conducted for that purpose. With the help of an Engineer the details were being explained and thus help in the refi nining of our checklist

From the results, two important points were found: Landfill Gas and leachate pond which are major factors which need more attention to avoid negative effects.

A Landfill which is not properly managed causes a lot of problems to the health, contamination of ground water, odours, and many health effects.

1.1 Objective of the research

A site visit was conducted at Mare Chicose Landfill, in order to have an overview of how a landfill is managed.

The purpose of the visit consists of identifying the hazards of the landfill present with evaluation and calculation of the risks.

Furthermore, the control measures that are being adopted and to determine if the measures are adequate.

2. Literature Review

2.1 Definition of waste

According to Taylor and Allen (1) any material which is of no further use can be regarded as waste. Human activities produced wastes materials. Waste management philosophies outlined that most wastes can be reused or recycled. Waste can be classified into solid, liquid, gaseous. Sources of solid wastes include residential, commercial, institutional, construction and demolition, municipal wastes, treatment plant sites, industrial, agricultural (Tchobanoglous 1993). With the increase in population rate during the last decades, the generation of waste has accelerated, due to industrialization and urbanization and furthermore, with the developments of technology and science also (Cardinali Richard, 2001). Increase in standard of living has given rise to waste generation and efficient and effective control measures need to be implemented so as not to deteriorate the health of people and the environment (Khalil Nadeem, Khan Mubashra, 2009). It has been a great concern and much attention has been given internationally on this issue. Each country has different waste hierarchy and options due to different geography, cultures, environment among others. (Pitt Michael, 2005). According to a recent study carried out in UK (reported in Recycling World, October 2000) Austria, Netherlands, Sweden, Germany growth in recovery and recycling exceeds the growth in waste. Followed by Denmark and Switzerland but in the slow lane are France, UK, and Norway where there use of landfill has increased. (Cardinali Richard, 2001).

2.2 Integrated Solid Waste Management and Waste Hierarchy

Therefore in the light of these growing concerns many professionals have proposed theories and solutions as to how the pollution can be minimized (Halawani et al.1993).Also, in an attempt to reduce the final volumes of wastes and to have sufficient funds for waste management the recycling process and recovery material can be used to get funds for waste management; whereby, the Integrated Solid Waste Management (ISWM) comes into the picture. Integrated Solid Waste Management (ISWM) is a framework that helps us to understand waste management and most importantly how to reduce wastes.

(1):http://www.Taylor and Allen

Therefore, it proposes a Waste Management Hierarchy for the best solution that put waste management options in order of sustainability, from the most favoured option to the least desired one. (Shown in figure 1).The Waste Management Hierarchy is a list of approaches to managing waste, arranged in order of preferability. The Environmental Protection Acts of most Australian States treats the Waste Hierarchy as a core principle and the UK Environment Agency supports the Waste Hierarchy as a general guide to selecting the best option for dealing with waste. However, despite the fact that it is widely used throughout the developed world, some critics have questioned the effectiveness of the model is actually implemented. For instance, in Australia implementation of the hierarchy has been patchy, with most effort to date focused on recycling and composting (Gertsakis and Lewis, 2003).

Figure 1: Sustainability and The Waste Management Hierarchy (adapted from J.Gertsakis and H Lewis, 2003)

Also in an attempt to reduce waste, the chairman of the US Senate Environment and Public Works committee, suggest that manufacturers must take full responsibility of their products from the whole life cycle of the products and when it becomes waste also thus reducing the burdens on the municipalities (Cardinali, 2001).

Both the developed and developing countries have experienced accidents due to releases of hazardous wastes(UNEP,1994,FEPA,1991:Shaw,1992)At the international level, the awareness regarding waste began in 1992 with the Rio Conference, where efficient handling of waste was priority of the Agenda 21.The Johannesburg World Summit on Sustainable Development in 2002 focused on initiatives to accelerate the shift to sustainable consumption and production and the reduction of resource degradation, pollution and waste by giving priority to waste reduction recycling, reuse followed by the safe disposal of waste .Therefore, as a measure of precaution it is in the best interest for most countries to make landfill as the last resort and option.

2.3 Overview of Landfills

Landfill is the cheapest method for disposal of waste: it is immensely used by many countries. Solid wastes, is any unwanted or discarded solid item. Municipal Solid Waste comes from homes, businesses and other urban areas. But the heavy dependency on the landfill has led to filling up of most landfill sites. Example in America before 1988, 80% of MSW were disposed of in landfills. By 2009 four or five landfills in operation will be full and the cost of a new one cost approximately $90 million (Anonymous, 1992). According to Dr. W.L. Rathje, a “garbologist” at the University of Arizona, he gave this shocking testimony to the scale of modern landfills at a governmental hearing, quoting that:

“I was told that the largest monument ever built by a New World civilization was the Temple of the Sun, built in Mexico about 2000 years ago. It occupied thirty million cubic feet. I can still remember my shock when my students told me that A San Francisco landfill, made up of two mounds compiled since 1977 solely out of cover dirt and the MSW from three cities, held seventy million cubic feet, a total of nearly five Sun Temples. Landfills are clearly the largest refuse heaps in the world.”

Since land is a scarce resource, therefore the European union has sensitized many countries on the need to use sustainable methods .In this context therefore, the waste hierarchy (consisting of waste minimization, reuse, recovery; recovery such as energy recovery from incineration and finally disposal to landfill) and the BPEO (Best Practicable Environmental Option) are widely encourage to be used. Even though the amount of waste has diminished still the amounts of waste disposed of to landfill have increased (Pitt Michael, 2005).

2.31 Zero landfill

Zero waste is a philosophy that promotes the redesign of resource life cycles so that all products are reused. Any wastes sent to landfills are minimal. Zero waste is not only about recycling but also avoiding landfills and preventing from waste production itself. The paradox is that the proportion of waste going into landfill may decrease but the volumes of Municipal solid waste are increasing ant that too in excess of 3 percent yearly for many developed nations (Douglas, 1992). The concept of zero landfill can never be achieved fully because there will be still a minimum of waste generated therefore landfill will always continue to exist.

2.32 Landfill Management:

After being landfilled the waste decomposes into chemical and biological processes normally taking more than 50 years. But during the degradation process the solid waste generates 0.2 m3 of contaminated wastewater known as leachate, which in turn depending on the climate (amount of rainfall) and types of waste its colour varies from black to brown .Rainfall plays a very important role in creating leachates. Factors affecting leachates are: age, precipitation, seasonal weather variation, waste types and composition. Leachate include several parameters such as COD,BOD5, organic carbon, ammonia nitrogen , chlorides, iron manganese, phenols and AOX but little or no phosphorus.(2).Therefore pretreatment of leachate is vital. Treatment of leachate constitutes of: Leachate chanelling: Combined treatment with domestic sewage, Recycling, Biological treatment: aerobic or anaerobic, chemical precipitation: to remove high strength of ammonium nitrogen. CW (constructed wetland) is, however, a relatively new approach to eliminating environmental pollution, based on purification of waste waters with halophytes planted in an artificial wetland and employing the self-cleaning ability of ecosystems for its biological treatment process. Presently, some hundred CWs are in operation in Europe (Bulc et al., 1998)

Capping:

Once cell is filled to maximum of waste, it is covered to prevent the entry of precipitation (rainfall) and the escape of gas, odour and introduction of further leachate. Moreover, can place soil over the capping or covering for a better protection. Two types of sealing liner: polymeric geomembranes and geosynthetic clay liners. Caps should include a drainage layer above and a gas collection layer between the caps lining system.

Leachate pond affect groundwater if leakage. More polluted groundwater will be discharged into streams wetlands and lakes.

2.33 Landfill Gas and Flaring

It is formed from the biodegradation of wastes. It normally occurs at elevated temperatures and eventually it will be saturated with water vapour. The major components of LFG are methane and carbon dioxide. Methane is an odourless gas and travelling away from sites can cause landfills fires when combines with air in certain proportions.

Three processes by which landfill gas occurs;

Bacterial decomposition, volatilization, and chemical reactions.

The volume of landfill gas produced at a site depends on these factors: waste composition, age of refuse, presence of oxygen in the landfill, moisture content, and temperature.

Source (2): http:www.scitopics.com

Figure 2: Typical Gas Composition at an engineered Landfill Site. (Adapted from Environment Agency November 2002)

The purpose of landfill gas flaring is to dispose of the flammable constituents safely and furthermore to avoid negative effects caused by odours,

Care must be taken in the management of LFG so as to;

Reduce impact on air quality; Gas does not spread beyond the perimeter of the site, to avoid landfill fires, to permit energy recovery and also to avoid odour and health risks.

2.34 Important points to be considered in the design of a landfill and facilities required inside the landfill are:

Nature and quantities of waste, water control, operational and restoration requirements, construction effects must be considered ,risk assessment, protection of soil and water, leachate management, gas control and Environmental nuisances. Moreover, the access of the landfill, the opening hours, types of wastes accepted should be marked and displayed at the entrance. In addition to that provision of an office plus the first aid area, bathing and toilet facilities, lockers, mess rooms, waste reception area ,store, parking area and a wheel clearer is essential for preventing mud from being carried out on the public road lastly the provision of adequate water supply in case of fire.

2.35 Health effects on Landfilling

Landfills should be the last resorts due to the scarcity of lands and many health problems encountered through it. There is a large body of literature on the potential adverse health effects of different waste management options. Example in a research done by (Saffron Lisa, 2003) it has been found that 220 papers have been published about the health effects from landfill sites. Many studies have been made on human populations about the hazards to health from landfill sites (Pitt Michael, 2005) but 101 are based on health impacts of landfill sites and 23 about health impacts of contaminated drinking water. Six papers discovered the evidence linking health effects with landfill sites. (Vrijheid M, 2000), revealed that health problems associated include respiratory symptoms, irritation of the skin, nose and eyes, gastrointestinal problems, fatigue, headaches. Environmental (Vrijheid M, 2000).These studies was conducted in order to look for a link between landfill sites and the following health outcomes: Reproductive outcomes(31studies),Cancer(29), psychosocial impacts(19), health problem not specified in abstract(14),mortality(5), injuries poisoning(2).Also EPA, revealed that many problems which occurred are because of the poor management of landfills. Most often theses problems are long term and include possible contamination of the groundwater and surface water regimes, among others. According to recent research, it was found that women who live near landfill sites has an elevated risk of having a baby with congenital malformations and also suffers from stress, fatigues, headaches, eye infections or irritations, coughs, stuffy noise, dry throat, and nausea and spontaneous abortions.(www://bmj.com).Also the other health impacts associated according to another research done by an international journal (Saffron lisa et al. ,2003) revealed that there is an increased risk of contracting cancer and also it contribute to global warming and loss of biodiversity as well and the depletion of non-renewable resources. In addition, mentioned was made in this journal that people living near and far off the sites contracts nearly same types of health problems. Each people immune systems are different; one can be more resistant while the others can be less. Research on Landfill site in Nant-y-Gwyddon revealed that an increase rate in congenital abnormalities in residents near the site, but it has been challenged by (Roberts et al: 2000).They were also suffering from stress, fatigues, headaches, eye infections or irritation, coughs, stuffy nose, dry throat and nausea and spontaneous abortions. Also the birth prevalence of gastoschisis seems to be increasing internally and nationally. The main weakness of the studies about landfill health effects is the complete lack of exposure data. Where the hazards from landfill sites have been identified, as is the case in the National Priorities List sites in the USA, it is possible to estimate exposure using the EPA Human Exposure Model (Wolfinger, 1989). The results of this type of analysis are uncertain and are based on risky assumptions. These remain estimates, not data. Most often theses problems are long term and include possible contamination of the groundwater and surface water regimes, odour, noise and visual nuisances (EPA). In an international journal (Saffron lisa,2003) revealed that there is an increased risk of contracting cancer and also it contribute to global warming and loss of biodiversity as well and the depletion of non-renewable resources, mentioned was made in this journal that people living near and far off the sites contracts nearly same types of health problems. Each people immune systems are different; one can be more resistant while the others can be less.

Figure3: Components of landfill (adapted from Department of Environmental Conservation New York)

The above figure shows the components and how the landfill has been design considering the different layers from the top to the bottom. In order to promote rainfall run-off away from the landfill a 24-inch thick barrier protection layer composition of soil and overlying 6 inches of vegetation topsoil serve to prevent the underlying geomembrane. To avoid again infiltration of rainfall a 60 mm geomenbrane along with the underlying low permeability clay layer are placed, thus this is done to avoid generation of additional leachate. Sand or gravel together with pipe lines are being placed so as to collect landfill gasses generated by decomposition waste. It is then followed by the waste mass, where all the waste is stock till decomposition. It is obvious that waste which contains water generate leachate therefore a primary leachate collection with pipe in place, so as to prevent the contamination of deep water sources a 60mm thick geomembrane underlines the leachate collection system and on the bottom of landfill syrong textile component to make a composite liner. However, another secondary leachate collection pipe is present after structural fill to avoid completely the leachate underground contamination. The final is a plastic geomembrane is to protect again the soil and the deep water sources. This design serves to protect the environment from contaminants which may be present in the municipal solid waste. The landfill siting plan, which prevents the siting of landfills in environmentally sensitive areas, as well as on-site environmental monitoring systems, which monitor for any sign of groundwater contamination and for landfill gas, provide additional safeguard.

2.36 Specifically Engineered Landfill (Basel Convention UNEP)

At the start of the project, proper planning shall be carried out considering that the landfill would not cause harm either to people or environment. Therefore high standard of controlling measures shall be put in place and establish control procedures which would monitor and even anticipate what to do after all cells have been filled. Hazardous waste must be disposed off before reaching the landfill and it can be done by either incineration or physio chemical processors.

2.37 Health and safety aspects associated with solid waste management

All activities in solid waste management involve risk. From the place of collection to the final stage in landfill risk is directly associated. However, we need to quantify the risk and identify the main hazard which may cause harm to people thus having a direct impact on the business. Risk which exists and is liable to cause damage to our health safety and even welfare and can be categorized in the following context: – Disease, injuries and accident

Disease -Illnesses which comprise of infectious disease, allergies, respiratory damage and even cancer. Some disease is derived from direct injections of infectious micro-organisms, others involve infection through contamination of the food chain, whereby animals or other vectors have ingested infectious micro-organisms

Injuries – joint and spinal damage, fractures, puncture wounds, damage to eyes and ears and other part of the body

Accidents- slides from unstable disposal piles, cave-ins of disposal site surfaces, fires, explosions, being caught in processing equipment, and being run over by mobile equipment

The workers are greatly exposed to the various risk at the landfill are specially, those who get involves in the segagation process. This practice is good for the recycling processes but its health consequence is beard up by workers. Those workers are exposed to fecal matters, saturated toxic materials, bottle with chemical residues, metals containers with residues pesticides and solvents, needle and bandages from hospital, battery containing heavy metals, not to forget the pollution caused by the mechanical vehicles which is inhale by the workers. Moving into more details the occupational illnesses and health consequences which cause tremendous nuisance to the workers exposed in a landfill are:-

The risk of vibration from heavy vehicles cause damage to the back and joint also the lifting of waste fill containers can damage our spine in the long run and if over- exposed very detrimental in the short run

From our respiratory ingestion of particulates bio-aerosol, and volatile organic are penetrated in our system through our routes of entry

Infection are being caused from direct contact with contamination material, dog and rodent bites, or eating of waste fed animals

Wounds punctured or bruised can contribute or cause health problems like tetanus, hepatitis, and HIV infections.

Frequent head and nausea are caused from anoxic condition where disposal sites have high methane, CO2 and carbon monoxide.

The consequences of burning metals arise the risk of lead poisoning.(Sandra Cointreau,2006)

2.38 The need for risk assessment in a landfill

Risk assessment is important in a landfill as it contributes in the planning process. Strategic goals are being evaluated based on the risk assessment carried out. The identification of hazards is essential so as to mitigate the various risks present in the landfill. Engineering and administrative control would be based on the risk assessment done and this show the gravity or severity of the hazard present in the landfill. This is done in order to mitigate the negative impact on environment. Risk assessment in a landfill would comprise of undergoing to find ways how to control or even reduce the deterioration of ecological system, As the analysis of two major areas: Adverse health and environmental effects of exposure to hazardous chemical and failure of complex technological system.

The risk assessment of a landfill should take place well in advance before it is in operation and this analysis would identify the various problem which may crop up and predict or design ways how to mitigate risk and find appropriate control measure. Nevertheless, the ecological risk assessment and the engineering risk assessment must be combining under one main component which is the environmental risk assessment.

Developing the risk assessment we should know:-

What are types of waste we are dealing are they harmful?

We must know who are exposed to those hazards(people, animals, aquatic life etc)

(3)To what extent it is affecting environment (magnitude, frequency)?

(4)Is there the need to provide corrective measures?

Risk assessment involvement in the landfill would be a continuous process and it shall be carried out even after its closure. So, this evaluation exercise predicts and illustrates preventive measures for the environment. (TE Butt, 2008)

3 METHODOLOGY:

HEALTH AND SAFETY TOUR AT MARE CHICOSE SANITARY LANDFILL

3.1 OBJECTIVE

A site visit was organized on 29/09/10 at Mare Chicose sanitary landfill. The purpose of the visit was to see the geographical location of the landfill, understand the management operations, vehicular movement control, and plant installations requirements and identify the hazards with evaluation of the risks present in the landfill. A checklist was formerly prepared prior to the visit on the hazards. Most of the work was adopted from Hobart City Council/Environmental aspects register (3)

3.2 OBSERVATIONS

The Mare Chicose sanitary landfill is the only engineered landfill of Mauritius and it covers an area of about 32 hectares of land. It is operational since November 2007 and is managed by sotravic ltee. The sanitary landfill has been constructed with a designed capacity of about 20,000 tons of solid waste. It was scheduled during design stage to receive about 300 tons of waste daily but actually receive 1200 ton per day. The five cells of the landfill as at to date are full. The construction of a 6th cell is under construction to respond to the increasing demand of waste disposal which include municipal waste, textile waste, tyres and papers.

At the construction phase, precautionary measures have been taken not to contaminate underground water table. The bed is protected by a layer of high density polyethylene impermeable membrane followed by 400g/m2 three layers of non woven geotextile. Above it follows a thick layer of aggregates of size 32mm which is finally covered by another layer of 1.5mm geotextile. In between are located leachate pipes whose functions are to collect the liquid leachate to a leachate pond. In the design of the main pipes for leachate, the annual rainfall factor has been considered so that the accumulated rainfall on the bed is properly disposed off. Management of leachate is very important to ensure that there is no run out in drains and neighboring fields and cause environmental concern. Leachate also produce odour which is reduced with use of synthetic cover made of biodegradable plastic on top of the solid waste.

(3): source http://www.risk assessement landfill

The depth of the landfill is usually 4m. However the solid wastes are piled up to a height of 25 to 50m above ground level and are protected again on top with another layers of geotextile membranes, aggregates, sub soil and top soil which prevents infiltration of rain water in the disposed waste. Most of the disposed wastes in the landfill are organic and the settlement of the waste in the present cells will be about 6 metre over 15 years.

It should be noted that methane gas is produced in dangerous concentration at bottom as a byproduct during decomposition of the waste in anaerobic condition. This gas has a green house effect and is managed through a flaring system: the gas is captured by aspiration from bottom of the landfill through a 460mm diameter slotted pipe to prevent its direct migration into the air. Methane is collected in a gas flare plant which has a capacity of 1500 m3 of gas per hour. It receives the gas through gas well chambers which are located on top of the capping. One gas well chambers cover a radius of 40m of the capped landfill. The captured methane gas is either used to produce electricity or is released into the atmosphere as carbon dioxide after the flaring process.

The following analysis is done on monthly basis to prevent environmental problem: ,Leachate, Surface water for storm water monitoring, Underground water table and boreholes, air monitoring through gas analyser for CH4, CO2, and O2 (every three month), noise ,dust.

The following health and safety measures have been taken at the landfill:

The 50 workers posted are vaccinated against Tetanus and Hepatitis at intervals of six months.

Regular health surveillance/medical checkup by a medical practitioner.

Protective equipment provided: Earmuff, rubber boot, respiratory mask and eye goggle.

All loaders/compacters in use are air conditioned and the machines are designed such that there is no risk of overturning.

The landfill is a restricted area and access is authorized only with permission from Ministry of Local Government.

All staff are trained in fire safety and first aid

No work normally done inside waste- breathing apparatus is used if required.

No radioactive waste, acids and medical waste are accepted. All liquid waste are directed to St Martin.

All electronic waste are disposed off in separate concrete basin known as encapsulation.

All asbestos are received only in sealed bags and disposed off deep in trenches and properly backfilled.

A risk assessment was carried out during the health and safety tour at the sanitary landfill. The hazards identified have been evaluated in terms of its likelihood that a problem may occur and the damage it might cause. The consequences or potential severity of injury or damage, measured on a scale has also been assessed and a risk score given by multiplying the likelihood scale with the severity scale.

The risk assessment carried out is quantitative and has been adapted from the five steps to risk assessment from the Health and Safety Executive. The steps are as follows:

STEP ONE- Identifying the hazards

STEP TWO – Determine the risk or decide who might be harmed.

STEP THREE – Evaluate if the risk is tolerable.

STEP FOUR – Record the findings and prepare risk control plan.

STEP FIVE – Review the assessment if there is change in any work procedure/equipment.

3.3 RISK ASSESSMENT AT MARE CHICOSE

For the purpose of this project, the following definition has been considered:

HAZARD

Hazard is defined as a source of inherent potential to cause harm or damage or injury.

RISK

Risk is defined as the likelihood/probability of the harm or damage or injury occurring.

The risk assessment was carried out to evaluate the environmental and occupational hazards present on the landfill to determine the level of action required to reduce the risks to an acceptable level. When evaluating the risks imposed by the hazard, we have considered both the likelihood and severity of the event happening.

LIKELIHOOD

This is defined as the chance of an event actually occurring. When making an assessment of likelihood, we established which of the following categories most closely describes the likelihood of the hazardous event occurring:

Very Likely — Could happen frequently

Likely — Could happen occasionally

Unlikely — Could happen, but only rarely

Very Unlikely — Could happen but probably never will

SEVERITY

Severity is defined as a measure of the expected consequence should an accident occur. When assessing the consequences of an accident, the most severe category one could reasonably expect to result from that accident has been selected. The severity is categorized as follows: –

Major injuries – irreversible injury and Death

Moderate injuries – a serious injury or damage to health requiring extended time off work to effect best recovery.

Minor injuries – a reversible injury or damage to health needing several days away from work to recover. Recovery would be full and permanent.

Insignificant Injuries-require first aid only and may need the remainder of the work period or shift off before being able to return to work. Requires no action to control.When making the risk assessment, all aspects of likelihood and severity has been taken into consideration. The interrelated parameters of likelihood and severity has been defined as risk score and any score of 9 and above is rated as unacceptable or of significant risk requiring immediate action with implementation of important control measures.

VISIT TO MARE CHICOSE SANITARY LANDFILL SITE

(Risk Assessment carried out on 29/09/10)

LIKELIHOOD: 1=Very unlikely 2=unlikely 3=likely 4=very likely.

SEVERITY: 1=Insignificant 2=Minor 3=Moderate 4= Major.

Any risk score of 9 or above is of significant risk and requires immediate attention.

SN

SECTION VISITED

HAZARD IDENTIFIED

CONTROL MEASURES

LIKELIHOOD X

SEVERITY=

RISK SCORE

FURTHER ACTION REQUIRED

IMPLEMENTATION BY

WHOM & WHEN

1

MAIN ACCESS TO LANDFILL

Vehicular movement creating noise and vibration

Site located is located away from the nearest inhabitants and access road wide enough to permit vehicle to move freely

3×2 = 6

NONE

Wind-blown litter

Scavenging lorries covered with tarpaulin

3X1 = 3

NONE

MAIN GATE

Public safety

1) Restricted area to public and premise controlled by security guards.

2) Safety signs displayed at main gate prohibits access to unauthorized persons.

3) Permission to authorized visitors to be sought from Ministry of Local Government.

2×2 = 4

NONE

ADMINISTRATIVE OFFICE

Authorized visitors exposed to health hazards from landfill immediate environment

1) All visitors should report to the reception and are provided with protective equipment before gaining access to landfill.

2) Safety sign for use of ear, respiratory, eye and foot protection are displayed.

3X2 = 6

NONE

Fire hazards due to presence of combustible waste and airborne gas in contact with any source of ignition.

1) Fire alarms, fire extinguishers, smoke detectors installed.

2) Exit, directional signs and assembly point clearly demarcated and all personnel are trained in use of fire extinguishers.

3) Premise is covered by a fire certificate and a fire drill is performed on a yearly basis.

4)Premise is a ‘no smoking area’.

3X2 = 6

NONE

WEIGHBRIDGE

Risk of vehicular collision

Separate corridor provided for Way in and Way out which are clearly demarcated.

3X2= 6

NONE

GAS FLARING

Methane gas in dangerous concentration at bottom.

Provision of gas well chambers on capping top and captured gas directed to a flaring tower which prevents its migration on air

Permit to work system in use in case of entry to bottom.

3X4 =12

The aspirator used should be regularly inspected otherwise an important release 150000 m3 of gas may occur

Close air monitoring of gas each month.

(By SOTRAVIC)

LEACHATE POND

Environment problem in case of leakage to neighboring drains and fields

1)Maximum leachate are collected through pipes and disposed properly to leachate pond and disposed off to Roche Bois.

2)The leachate is contained in a HDC plastic membrane at bottom of the pond which prevents contamination of the water table.

3X3 =9

Regular analysis of ground and surface water

Monitoring

every three month basis

(By SOTRAVIC)

Contact with leachate causing health hazard such as skin infection and respiratory and odor problem

All workers are vaccinated for tetanus and hepatitis every three month.

Medical check up every six month by a medical practitioner.

3X2 = 6

NONE

ACCESS ROAD ALONG THE LANDFILL

Risk of collision of vehicles

The speed limit controlled to a maximum of 20 km per hours.

2X2=4

NONE

TIPPING AREA

Risk of overtuning of the scavenging lorry during unloading of the waste

Stop block provided to limit the reversing action of the lorry when unloading.

2X2=4

NONE

TOP OF LANDFILL

Settlement of waste

Waste is densely compacted by a waste compactor BOMAG

1X2 = 2

NONE

Overturning of the compaction vehicle

Use of specially designed landfill compactor with large size roller instead of tyres which ensures its stability.

2X2 = 4

NONE

HAZARDOUS WASTE DISPOSAL

Environmental and Health hazards.

Liquid waste including acids, radioactive and medical waste are not accepted.

Asbestos are buried deep in sealed bags.

Electronic waste disposed in separate concrete basin.

3X2 =6

NONE

Results and Discussions

Access Road

The sanitary landfill is located about one kilometer from the nearest inhabitants. The access road can accommodate all scavenging Lorries which have not yet gain access inside the landfill and are wide enough for easy vehicular movement. The noise and vibration caused is within tolerable limit. No air blown litter observed all along the access road because every lorry stationed in queue has their solid waste properly covered with tarpaulin. The risk accessed is therefore minimal.

Main gate

Adequate health and safety signs were conspicuously displayed at the gate to restrict access to public. The security guards permit entry to visitors with permission from Ministry of Local Government and who should report directly to the reception. The risk of injury is very low.

Administrative Office

All visitors and personnel are provided with protective equipment and are informed of the dangers which they are being protected. Smoking is strictly prohibited due to presence of airborne landfill gases in small quantities. All fire safety precautions are observed by the staff and visitors. The fire safety installation is tested on regular basis and a fire certificate is in force for the premises. The risk of fire is therefore acceptable with a risk score of 6 and no further action is required.

Weighbridge

Pedestrians do not have access to the weighbridge. Separate corridor is provided for way in and out of the vehicle and this arrangement is clearly demarcated. The risk of accident is reduced as pedestrians and vehicular movement has different approaches.

Gas Flaring

The landfill gas such as methane and carbon dioxide are present in dangerous concentration at bottom of the landfill as a result of decomposition of waste in anaerobic conditions. These gases are pumped out from the bottom using perforated pipes and flared off to a gas flaring tower of capacity of 15000 m3 whereby it is processed and released as carbon dioxide. An in built aspirator fitted on the flaring tower ensures that a continuous flow of the methane gas is extracted and directed to the flaring plant. If the aspirator fails in its function methane gas will migrate directly to the air and cause greenhouse effect. Therefore, the risk level in this gas management system is rated high with a likelihood of 3 and a severity of 4. Proposed control measures in place are monthly air monitoring of the gas and regular inspection of the aspirator. The risk assessment conducted has identified the need to ensure a continuous air monitoring to detect early accidental methane gas release into the air in the flaring tower in case of the failure of the aspirator. Permit to work system is also used in case access to bottom is required to check and weld the slotted pipes.

Leachate Pond

The leachate pond situated in the sanitary landfill has the potential to contaminate the underground water table or neighboring drains in case of leakage. As a control measure, the bottom of the pond is provided with a layer of high density plastic membrane and all excess leachate are pumped out to be disposed to Roche Bois. Therefore, the need to monitor closely the ground and surface water and the atmospheric air was apparent. The risk assessment conducted has identified this potential risk and rated it as 9 which is a significant environmental concern.

Also direct contact with the leachate causes health hazard such as skin infection and odor problem. It was observed that a suitable health surveillance program is established for all workers and no further action is required.

Access Road within the Landfill

The speed of the vehicles is limited to 20 km per hour.

Tipping Area

Stop block is provided during reversing of the lorry to prevent overturning during unloading.

Solid Waste Compaction

Use of a waste compactor which is specially designed against risk of overturning.

Hazardous Waste Disposal

Environment and health hazard was identified if hazardous waste is not disposed properly. Management policy is not to accept liquid waste, medical waste, radioactive waste and acids. Electronic wastes are encapsulated in a separate concrete basin and no asbestos is disposed unless received in sealed bags. With above measures, the risk score is rated 6 because though it is likely that the hazardous waste are present it has little environmental and health consequences if above control measures are strictly implemented.

Conclusion

The risk assessment conducted has identified the need to ensure a continuous air monitoring to detect early accidental methane gas release into the air in the flaring tower in case of the failure of the aspirator. Also, the leachate has the potential to contaminate underground water table, drains around the site and the fields causing environment concerns. Therefore, the need to monitor closely the ground and surface water and the atmospheric air is clear.

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