Tool and Guideline # 11.1

Practical Tools on Solid Waste Management of Imidugudu, Small Towns and Cities :

Landfill and Composting Facilities

Rwanda Environment Management AuthorityRepublic of Rwanda

Kigali, 2010

PREFACE

In 2010, REMA prepared 11 practical technical tools intended to strengthen environmental management capacities of districts, sectors and towns. Although not intended to provide an exhaustive account of approaches and situations, these tools are part of REMA’s objective to address capacity-building needs of officers by providing practical guidelines and tools for an array of investments initiatives.

Tools and Guidelines in this series are as follows:

# TOOLS AND GUIDELINES1 Practical Tools for Sectoral Environmental Planning :

A - Building ConstructionsB - Rural RoadsC - Water SupplyD - Sanitation Systems E - ForestryF - Crop ProductionG - Animal HusbandryH - IrrigationI - Fish FarmingJ - Solid Waste Management

2 Practical Tools on Land Management - GPS, Mapping and GIS3 Practical Tools on Restoration and Conservation of Protected Wetlands4 Practical Tools on Sustainable Agriculture5 Practical Tools on Soil and Water Conservation Measures6 Practical Tools on Agroforestry7 Practical Tools of Irrigated Agriculture on Non-Protected Wetlands8 Practical Tools on Soil Productivity and Crop Production9 Practical Technical Information on Low-cost Technologies: Composting Latrines &

Rainwater Harvesting Infrastructure10 Practical Tools on Water Monitoring Methods and Instrumentation11 11.1 Practical Tools on Solid Waste Management of Imidugudu, Small Towns and Cities

: Landfill and Composting Facilities11.2 Practical Tools on Small-scale Incinerators for Biomedical Waste Management

These tools are based on the compilation of relevant subject literature, observations, experience, and advice of colleagues in REMA and other institutions. Mainstreaming gender and social issues has been addressed as cross-cutting issues under the relevant themes during the development of these tools.

The Tool and Guideline # 11.1 provides practical information on the siting and construction of landfill and composting facilities of Imidugudu, small towns and cities.

These tools could not have been produced without the dedication and cooperation of REMA editorial staff. Their work is gratefully acknowledged.

Dr. Rose MukankomejeDirector General, Rwanda Environment Management Authority

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TABLE OF CONTENT

1. INTRODUCTION.......................................................................................................................1

1.1 OVERVIEW............................................................................................................................11.2 PURPOSE...............................................................................................................................21.3 MAINSTREAMING GENDER AND SOCIAL ISSUES IN WASTE MANAGEMENT.........3

2. WASTE MANAGEMENT........................................................................................................4

2.1 CONCEPTS.............................................................................................................................42.2 WASTE STREAMS................................................................................................................5

2.2.1 Municipal..........................................................................................................................52.2.2 Biomedical waste...............................................................................................................6

3. ENVIRONMENTAL GUIDELINES.......................................................................................7

3.1 SOLID WASTE MANAGEMENT PLANS............................................................................73.2 SMALL-SCALE SANITARY LANDFILL GUIDELINE..........................................................9

3.2.1 Landfill Design..................................................................................................................9Type of Landfills...........................................................................................................................................9Operations and Processes..........................................................................................................................10Soil and Clay Liners...................................................................................................................................11Minimizing Leachate Generation...............................................................................................................12Gas Management........................................................................................................................................14Stability.......................................................................................................................................................14Landfilling Methods...................................................................................................................................14Construction Phasing.................................................................................................................................15Siting...........................................................................................................................................................16Environmental Requirements.....................................................................................................................17Private Sector Involvement........................................................................................................................17Transit and Collection Sites.......................................................................................................................17

3.2.2 Landfill Siting Criteria....................................................................................................18Minimum Acceptable Standards.................................................................................................................18

3.2.3 Landfill Operational and Performance Criterion..........................................................20Prohibited Wastes.......................................................................................................................................20General Operations....................................................................................................................................20Performance Criteria.................................................................................................................................22

3.2.4 Landfill Closure Plan......................................................................................................263.3 SMALL-SCALE COMPOSTING FACILITY GUIDELINE...................................................27

3.3.1 Composting Facility Design Criteria..............................................................................27General Principles.....................................................................................................................................27Residential Composting..............................................................................................................................30Decentralized Community Composting......................................................................................................31Composting Processes................................................................................................................................31Operating and Control Parameters...........................................................................................................36

3.3.2 Composting Facility Siting Criteria...............................................................................39Minimum Acceptable Standards.................................................................................................................39

3.3.3 Composting Facility Operational and Performance Criterion.....................................40General Principles.....................................................................................................................................40Environmental Monitoring.........................................................................................................................40

3.3.4 Approval Process.............................................................................................................42

Annex 1: References and Useful Resources............................................................................................43

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TABLES

TABLE 1 : LANDFILLING METHODS..........................................................................................................14TABLE 2 : OPERATIONAL PROBLEMS AT LANDFILLS...............................................................................21TABLE 3 : BENEFITS AND CONSTRAINTS OF COMPOSTING......................................................................29TABLE 4 : COMPARISON OF COMPOSTING PROCESSES.............................................................................35TABLE 5 : CARBON/NITROGEN RATIO OF COMPOSTABLE MATERIALS...................................................38Table 6 : Separation Distances for Composting Facilities.......................................................................39

FIGURES

FIGURE 1 : NATURAL ATTENUATION LANDFILL........................................................................................9FIGURE 2 : MODERN SANITARY LANDFILL..............................................................................................10FIGURE 3 : LANDFILL OPERATIONS AND PROCESSES...............................................................................11FIGURE 4 : LEACHATE PIPE AND LINER...................................................................................................13FIGURE 5 : LEACHATE PIPE IN GRAVEL...................................................................................................13FIGURE 6 : EXCAVATED CELL/TRENCH LANDFILL METHOD (BUND METHOD).......................................15FIGURE 7 : AREA LANDFILL METHOD......................................................................................................15FIGURE 8 : CANYON/DEPRESSION LANDFILL METHOD............................................................................15FIGURE 9 : DEVELOPMENT OF A LANDFILL..............................................................................................16FIGURE 10 : COMPLETED LANDFILL.........................................................................................................16FIGURE 11 : SECTIONAL VIEW - SANITARY LANDFILL............................................................................17FIGURE 12 : RECYCLING PRINCIPLES.......................................................................................................30FIGURE 13 : WINDROW COMPOSTING......................................................................................................33FIGURE 14 : AERATED STATIC PILE.........................................................................................................34FIGURE 15 : IN-VESSEL COMPOSTING......................................................................................................34Figure 16 : Vermicomposting..................................................................................................................36

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Definitions

"access road" means a road that leads from a public road to a waste disposal site. "aerobic" means in the presence of oxygen. "aquifer" includes any soil or rock formation that has sufficient porosity and water

yielding ability to permit the extraction or injection of water at reasonably useful rates.

"biomedical waste" means a substance that is defined as biomedical waste. "buffer zone" means land used to separate a facility from other land. "cell" means a compartment within a landfill isolated from other compartments by

appropriate cover material and of such size so as to be considered manageable in the context of total volume and the day-to-day operating concerns including garbage placement and compaction, stability of working surfaces and slopes and the operation of landfill equipment.

"composting" is the aerobic biological decomposition of organic municipal solid waste under controlled circumstances to a condition sufficiently stable for nuisance-free storage and for safe use in land application.

"cover material" means soil or other material approved for use in sealing cells in landfills.

"daily cover" means a compacted layer of at least 0.15 metre of soil or functionally equivalent depth of other cover material that is placed on all exposed solid waste at the end of each day that municipal solid waste is discharged at the landfill.

"design volume" means the maximum volume of solid waste, including cover material, to be discharged at the solid waste management facility during its active life.

"disposal" means the introduction of waste into the environment for the purpose of final burial, destruction or placement for future recovery.

"final cover" means a layer consisting of soil and, in some cases, other natural or synthetic materials that is placed on any surface of a landfill where no additional solid waste will be deposited and serves to restrict the infiltration of precipitation, to support vegetation, to control landfill gas, to restrict access by wildlife, and to promote surface drainage.

"floodplain" means a lowland area, whether dyked, flood proofed or not, which, by reasons of land elevation, is susceptible to flooding from an adjoining watercourse, lake or other body of water and for administration purposes is taken to be that area submerged by the designated flood plus freeboard.

"groundwater" means water below the ground surface in a zone of saturation. "hazardous waste" means "hazardous waste" as defined in the Hazardous Waste

Regulation. " infiltration" is the entry into the soil or solid waste of water at the soil or solid waste

surface. "intermediate cover" means a compacted layer of at least 0.30 metre of soil or

functionally equivalent depth of other cover material placed where no additional solid waste has been deposited or will be deposited within a period of 30 days.

"leachate" means any liquid and suspended materials which it contains, which has percolated through or drained from a municipal solid waste disposal facility.

"liner" means a continuous layer of synthetic material or natural clay or earth materials, placed beneath and at the sides of a landfill and intended to restrict the downward or lateral escape of waste or leachate or in some cases to restrict the upward movement of ground water into the landfill.

"open burning" means the combustion of any material or solid waste in the absence of containment and control of the combustion reaction with respect to residence time, temperature and mixing.

"putrescible" refers to organic matter which has the potential to decompose with the formation of malodorous by-products.

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"recovery" means reclaiming of recyclable components and/or energy from the post-collection solid waste stream by various methods including incineration, pyrolysis, distillation, gasification or biological conversion (including composting) and includes the collection and subsequent management of methane gas generated in the landfill.

"recycling" means the collection, transportation and processing of products separated from the municipal solid waste stream which are no longer useful in their present form and the use (including composting) of their material content in the manufacture and sale of new products. Recycling refers to source-separated wastes only, when used in the context of the 3 R s (Reduce, Reuse, and Recycle).

"reduction" means decreasing the volume, weight, and/or toxicity of discarded material and includes activities which result in greater ease or efficiency of reuse of a product or recycling of materials.

"remediation" means actions taken to remove, eliminate, limit, correct, counteract or mitigate the negative effects on human health or the environment of a release or threatened release of one or more contaminants into the environment.

"reuse" means the repeated use of a product in the same form but not necessarily for the same purpose.

"salvaging" means the removal of material from a solid waste facility under the control of the facility owner or operator.

"scavenging" means the uncontrolled removal of material from a solid waste facility. "sewage" means effluent from a municipal sewerage system. "solid waste facility" refers to a facility designed, constructed and operated for the

collection, processing, transferring or disposal of the solid waste stream or components thereof, including but not limited to, transfer stations, material recycling facilities, composting facilities and disposal facilities.

"Solid waste stream" means the aggregate of all solid waste components, and also the process through which they move from point of generation to ultimate disposal.

"surface water" means lakes, wetlands, ponds, streams and springs, rivers, marshes within the territorial limits of Rwanda and all other perennial or ephemeral bodies of water, natural or artificial, but excludes groundwater or leachate collection channels or works.

"vector" means a carrier that is capable of transmitting a pathogen from one organism to another and includes, but is not limited to, flies and other insects, rodents and birds.

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Practical Tools on Solid Waste Management of Imidugudu, Small Towns and Cities:Landfill and Composting Facilities

1. INTRODUCTION

1.1 OVERVIEWThe solid waste management guideline covers household waste for resettlements (imidugudu), small towns and cites. The District environmental officers and Sector officers, communities, CBOs, associations, private companies and health officers and advisers need to understand various waste collection, treatment and disposal methods so that they can use the best methods for their specific conditions.

Waste disposal facilities remain inadequate in resettlements (imidugudu), small towns and cities throughout Rwanda. In rural areas, organic waste is composted and mixed in fields; other types of waste are re-used or buried. In urban areas, the local administration usually manages solid waste collection and disposes waste in open dumpsites.

Provisions for urban environmental management are currently addressed under the Environmental Policy for Rwanda and the Environment Law. The Environment Law contains key provisions that have implications for urban planning and development, including solid waste management. The main institutions responsible for the implementation of the Environmental Policy and the Environment Law are REMA, the MINIRENA, MINISANTE, and the MININFRA. As part of the decentralisation process, local authorities are responsible for domestic solid waste management.

Improvements in solid waste management have occurred since 2005, with the introduction of municipal by-laws prohibiting the dumping of household waste outside individual private property. While solid waste collection has significantly improved, there are health risks to garbage collectors, who are mostly women. Poor solid waste disposal poses significant safety and health risks, particularly of groundwater contamination.

Photo 1 : CBO waste collection

Typically, households register for solid waste management services with a local, community-based organisations (CBOs), associations and private companies. These organizations are licensed by municipal authorities to provide waste collection services for a designated area. In some instances, the local administration or a private contractor is responsible for waste

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collection in commercial areas, but also in residential areas if there is no CBOs, associations or private companies involved. Associations, private companies and CBOs appeared to operate in a number of urban centres. Some CBOs are operated by women associations.

The collected waste is directly transported to dump sites in vehicles. In some areas, waste is brought to transfer areas to sort and recycle the organic waste into compost and briquettes, in other areas, much of organic waste is taken from a collection point and used in generating biogas, significantly reducing the amount of waste in the environment. While there are efforts to recycle, waste recovery rates in Rwanda are still relatively low.

Photo 2 : Recycling

The use of associations, private companies and CBOs is considered to be a success and a significant improvement for dealing with solid waste in urban areas. However, solid waste is dumped in open locations with simple management techniques that are likely to cause both environmental and health impacts.

There is generally a high level of awareness in the health sector regarding the problems associated with hazardous healthcare waste, mostly due to the potential infection of HIV from poor waste disposal. Some hospitals have a dedicated incinerator and also receive some waste from smaller medical centres. All district hospitals and smaller medical centres are required to incinerate their hazardous healthcare waste. As health facilities improve in regional centres, there will likely be an increase in the amount of hazardous healthcare waste. Therefore, suitable policy frameworks and financial resources need to be considered for improving healthcare waste management.

The major environmental and health concerns associated with inadequate solid waste management relate to the spontaneous combustion of waste and the escape of leachate from dump sites. In many open disposal areas, fires can burn and smoulder over a prolonged period thereby releasing methane, carbon monoxide, nitrogen oxide, sulphur oxide and dioxins into the atmosphere. The main problem, however, is leachate and it’s potential for ground and surface water contamination. Leachate is the liquid that drains from a landfill site; its chemical properties are determined by waste composition.

1.2 PURPOSE

This technical guideline provides provides practical information on the siting and construction of landfill and composting facilities of Imidugudu, small towns and cities.

Although not intended to provide an exhaustive account of approaches and situations, this tool is intended to address capacity-building needs of officers by providing information on solid

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waste management. This tool can be used as field guides or as checklists of elements for discussion during training and during implementation of soil waste management initiatives.

This document was produced to address REMA’s proposed policy action to strengthen the resource capacity of environmental and related institutions at national and district level for environmental assessment, policy analysis, monitoring, and enforcement.

1.3 MAINSTREAMING GENDER AND SOCIAL ISSUES IN WASTE MANAGEMENT

Solid waste management practice has been largely focused on the technical issues of waste disposal with little or no attention paid to the social and economic aspects of households. Solid waste management services forms the core of municipal services and cannot be sustained without community cooperation and participation in all operations. The designed system should be user friendly and sustainable. To this end, efforts are needed to assess the profiles communities as each one is unique and so are the needs, aspirations and challenges. The understanding of the demographic characteristics of communities within the local authorities’ operational area is vital for the delivery of accessible, affordable, relevant, acceptable and effective services.

Women form the larger proportion of society and constitute the most vulnerable population groups to inappropriate service system designs in particular, solid waste collection systems. One of the shortcomings of solid waste collection systems is their male bias regardless of the fact that women constitute the majority of the service recipients. Waste is not a neutral concept but should be understood within the cultural context realising that within the same society, same household, men and women and children may have differing perceptions and views about what is regarded as waste. For this reason it is essential to define what constitutes waste and could be put out for collection with the ultimate aim of final disposal in a responsible manner. Knowledge of what households regard as waste is important for planning solid waste management.

Collection, binning and disposal of garbage from the house are seen as a task of women. Women are supposed to keep the house clean and dealing with solid waste is considered their responsibility. Garbage is dirty and working with garbage has a low and negative status; unless it becomes professionalised and provides good income. In domestic situations most men will not handle garbage (bringing it to the container) as this will affect their status. As some cultures ascribe a lower status to women than men, it is seen as ‘natural’ for women to handle garbage. Thus women and children are most exposed to garbage and the health hazards related to impractical (and unhygienic) behaviour, improper equipment and for them inadequate services. Some types of work related to recycling are done mostly by women at home, such as composting and productively using biodegradable waste, whereas in the collection and recycling of other resources, such as paper and plastics and scavenging of solid waste dumps, both sexes participate.

All the above calls for the designing of appropriate solid waste systems that are equitable and affordable by all sectors of the population especially those that were historically disadvantaged. Consumer participation in decisions on service provision is essential in order to build a mutual trust between the service providers and the service recipients.

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2. WASTE MANAGEMENT

2.1 CONCEPTS

There are a number of widely-used concepts about waste management:

Waste hierarchy - The waste hierarchy refers to the "3 Rs" reduce, reuse and recycle, which classify waste management strategies according to their desirability in terms of waste minimization. The waste hierarchy remains the cornerstone of most waste minimization strategies. The aim of the waste hierarchy is to extract the maximum practical benefits from products and to generate the minimum amount of waste.

Polluter pays principle - the Polluter Pays Principle is a principle where the polluting party pays for the impact caused to the environment. With respect to waste management, this generally refers to the requirement for a waste generator to pay for appropriate disposal of the waste.

Education and awareness in the area of waste and waste management is increasingly important. The next figure provides information on the integrated waste management hierarchy.

Reduction is the preferred method of waste management since it prevents the generation of waste in the first place. Reduction includes minimizing the production of wastes during any step in the creation or use of a product. For example, source reduction includes backyard composting of food scraps because this method of management keeps these wastes out of the waste stream. Reuse follows source reduction in the waste management hierarchy. Items normally discarded as waste—such as appliances, furniture, glass jars, and bottles—can be reused as originally intended or as new products. Reusing items by repairing them or selling them also reduces waste. Reusing, when possible, is preferable to recycling because the item does not need to be reprocessed before it can be used again. Both source reduction and reuse decrease resource use, protecting the environment. Source reduction and reuse also reduce the

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dependency on traditional methods of waste management, such as landfilling, which often face capacity and regulatory restrictions and incur high environmental and economic costs.

Recycling (including composting), the process by which materials otherwise destined for disposal are collected, processed, and remanufactured, follows source reduction and reuse in the waste management hierarchy. Recycling and composting can reduce the depletion of landfill space, save energy and natural resources, provide useful products, and provide economic benefits. Disposal management methods, including resource recovery (or waste-to-energy) and landfilling are near the bottom of the hierarchy. Resource recovery is preferred to landfilling since the method reduces the bulk of municipal waste and can provide the added benefit of energy production.

2.2 WASTE STREAMS

2.2.1 Municipal

Waste management is the collection, transport, processing, recycling or disposal, and monitoring of waste materials. The term usually relates to materials produced by human activity, and is generally undertaken to reduce their effect on health, the environment or aesthetics. Waste management is also carried out to recover resources from it. Waste management can involve solid, liquid, and gaseous substances, with different methods and fields of expertise for each. Waste management practices differ for rural, small town, urban or industrial producers.

Waste reduction methods: An important method of waste management is the prevention of waste material being created, also known as waste reduction. Methods of avoidance include reuse of second-hand products and repairing broken items instead of buying new.

Recycling: Items that are usually composed of a single type of material are relatively easy to recycle into new products i.e. paper and plastics. The recycling of complex products (such as computers and electronic equipment) is more difficult, due to the additional dismantling and separation required.

Composting: Waste materials that are organic in nature, such as plant material, food scraps, and paper products, can be recycled using biological composting and digestion processes to decompose the organic matter. The resulting organic material is then recycled as mulch or compost for agricultural. There are large varieties of composting and digestion methods and technologies varying in complexity from simple home compost heaps, to industrial-scale enclosed-vessel digestion of mixed domestic waste. Methods of biological decomposition are differentiated as being aerobic or anaerobic methods, though hybrids of the two methods also exist.

Landfill: Disposing of waste in a landfill involves burying the waste. A properly-designed and well-managed landfill can be a hygienic and relatively inexpensive method of disposing of waste materials. However, poorly-designed or poorly-managed landfills can create a number of adverse environmental impacts such as wind-blown litter, attraction of vermin, and generation of liquid leachate. Another common byproduct of landfills is gas (mostly composed of methane and carbon dioxide), which is produced as organic waste breaks down anaerobically. This gas can create odor problems, kill surface vegetation, and is a greenhouse gas. Design characteristics of a modern landfill include methods to contain leachate such as clay lining material. Deposited waste is normally compacted to increase its density and stability, and covered to prevent attracting vermin (such as mice or rats). Many landfills also have landfill gas extraction systems installed to extract the

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landfill gas. Gas is pumped out of the landfill using perforated pipes and flared off or burnt in a gas engine to generate electricity.

Incineration: Incineration is a disposal method that involves combustion of waste material. Incineration and other high temperature waste treatment systems are sometimes described as "thermal treatment". Incinerators convert waste materials into heat, gas, steam, and ash. Incineration is carried out both on a small scale by individuals and on a large scale by industry. It is used to dispose of solid, liquid and gaseous waste. It is recognized as a practical method of disposing of certain hazardous waste materials (such as biological medical waste). Incineration is a controversial method of waste disposal, due to issues such as emission of gaseous pollutants.

Waste handling and transport: Domestic waste collection services are often provided by local CBOs, associations or private companies.

2.2.2 Biomedical waste

Biomedical waste consists of solids, liquids, sharps, and laboratory waste that are potentially infectious or dangerous. It must be properly managed to protect the general public, specifically healthcare and sanitation workers who are regularly exposed to biomedical waste as an occupational hazard. Biomedical waste differs from other types of hazardous waste, such as industrial waste, in that it comes from biological sources or is used in the diagnosis, prevention, or treatment of diseases. Common producers of biomedical waste include hospitals, health clinics, nursing homes, medical research laboratories, and offices of physicians, dentists, and veterinarians. The following is a list of materials that are generally considered biomedical waste:

Solids: Catheters and tubes, disposable gowns and masks, disposable tools, such as some scalpels and surgical staplers, medical gloves, surgical sutures and staples, and wound dressings;

Liquids: blood, body fluids and tissues, cell, organ, and tissue cultures; Sharps: blades, razors, scalpel blades, needles, and syringes; Laboratory waste: animal carcasses, hazardous chemicals.

Management:Sorting of medical wastes in hospital: At the site where it is generated, biomedical waste is placed in specially-labelled bags and containers for removal by biomedical waste transporters. Other forms of waste should not be mixed with biomedical waste as different rules apply to the treatment of different types of waste. Biomedical waste is treated by any or a combination of the following methods: incineration or steam, chemical, or microwave sterilization. Any tools or equipment that come into contact with potentially infectious material and are not disposable or designed for single-use are sterilized in an autoclave. Household biomedical waste usually consists of needles and syringes from drugs administered at home. Disposing of these materials with regular household garbage puts waste collectors at risk for injury and infection, especially from sharps items. Programs should be in place for the disposal of household biomedical waste.

Biomedical waste treatment facilities are licensed by the local governing body which maintains laws regarding the operation of these facilities.

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3. ENVIRONMENTAL GUIDELINES

3.1 SOLID WASTE MANAGEMENT PLANS

Solid Waste Management Plans are a requirement of the Rwanda Act on Solid Waste Regulations. Solid Waste Management Plans encourage owners and operators of waste disposal facilities to consider their options carefully while preparing detailed plans for the future of the site. Good planning at the local level will contribute to better planning and management at the territorial government level, and that will benefit all Rwandans. Once a plan is approved by the Rwanda government, it can be put into effect and solid waste can then be disposed of in accordance with its provisions.

Content

Solid Waste Management Plans must cover a ten-year period, and must comply with Rwanda’s Solid Waste Regulations.

Factors to Consider

In addition to the legislated requirements, the following are suggestions of factors to consider when drawing up your plan:

Environmental Factors

land - consider ground pollution: ensure the volume of solid waste stream is minimized through reuse, recycling, and recovery; residue should always be minimal;

water - consider surface and ground water sampling and monitoring requirements; air - no-burn operations help minimize air pollution; consider increasing composting

activities to minimize methane accumulations that result from decomposition; and wildlife - ensure minimal conflicts; prevent access by domestic and wild animals to

avoid strewn litter, cumulative poisoning and danger to the public.

Social Factors

aesthetics - ensure windblown litter is controlled and minimized; adjacent land use - consider noxious odours and an adequate buffer zone; conflicting land uses - consider potential conflicts with nearby private and

government land owners; public consultation - identify method and results (if applicable) of public

consultation on issues that affect the community.

Economic Factors

financial capital – estimation of construction solid waste infrastructure, transportation and collection methods;

revenue – estimation of revenue form collection.

Legal Factors

compliance - ensure all plans comply with current legislation and the necessary

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permits are in place as required by the Rwanda Solid Waste Regulations.

Additional Suggestions

The following suggestions will help you prepare a good Solid Waste Management Plan:

Include a legal description of the site, including a map referencing current and future areas;

Use maps for all plan requirements that relate to geography; When determining the capacity of the existing facility, consider the population

served, including industries; the types and approximate annual volume of waste; and the approximate volume of storage available;

When determining sites for new facilities, consider the soil conditions and topography; environmental impacts (surface and ground water, plant and wildlife); social impacts; economic impacts; and potential conflicts with other land owners and land uses.

To help describe the physical and natural environment of potential new sites, and to develop strategies and actions to help protect that environment, consider employing a qualified professional who can identify potential ecological impacts.

When developing waste segregation strategies, include descriptions of the types and quantities of solid waste accepted and banned; an estimate of the percentage of the solid waste stream managed through reuse, reduction, recycling and recovery, and the amount of residual waste; land, equipment and labour involved; operational problems; and environmental, social, and economic impacts.

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3.2 SMALL-SCALE SANITARY LANDFILL GUIDELINE

3.2.1 Landfill Design

Sanitary landfill is the most cost-effective system of solid waste disposal for most urban areas. Composting of solid waste costs 2-3 times more than sanitary landfill, and incineration costs 5-10 times more. A sanitary landfill is a contained and engineered bioreactor and attenuation structure, designed to encourage anaerobic biodegradation and consolidation of compacted refuse materials within confining layers of compacted soil. At a proper sanitary landfill, there are no nuisance impacts of constant burning, smoke, flies, windblown litter, and unsightly rubbish heaps. Refuse in a proper sanitary landfill is not directly exposed to rainfall, surface runoff or groundwater.

Type of LandfillsThe next two figures provide the key components of 2 types of landfills, the natural attenuation landfill and the modern sanitary landfill. The natural attenuation landfill is used for the disposal of residual solid wastes in the surface soils of the earth. The “modern sanitary landfill” refers as an engineered facility for the disposal of municipal solid wastes designed and operated to minimize public health and environmental impact.

Figure 1 : Natural Attenuation Landfill

The following criteria apply to "natural control" landfills which do not rely on leachate containment/collection/disposal systems:

The bottom-most solid waste cell is to be 1.2 metres above the seasonal high water table. Greater or lesser separation depths may be approved based on soil permeability and the leachate renovation capability of the soil.

There is to be at least a 2 metres thick layer of low permeability soil with a hydraulic conductivity of 1 x 10-6 cm/s or less (i.e. silt or clay), below each of the bottom-most waste cells. Lesser thicknesses or no layer of low permeability soil may be approved based on the potential for leachate generation and the unsaturated depth, permeability and leachate renovation capability of the existing soil.

Sanitary landfills located in arid areas, where there is minimal potential for leachate generation, may have more relaxed design requirements than those located in wet areas. In these areas of lower impact potential, impermeable lining of the landfill may be unnecessary. Instead, measures to enhance natural attenuation by soil's adsorption, precipitation, filtration, and ion exchange capacities need to be considered.

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Figure 2 : Modern Sanitary Landfill

The following criteria apply to "modern" landfills which have leachate containment, collection and disposal systems:

The minimum liner specification for leachate containment systems is a 1 metre thick, compacted soil liner with a hydraulic conductivity of 1 x 10-7 cm/s or less. Minimum bottom slopes of the liner are to be 2 % on controlling slopes and 0.5 % on the remaining slopes. Natural, in- situ or low permeability soils which provide the same level of leachate containment are acceptable equivalents.

Minimum specifications for leachate collection systems are a 0.3 metre thick sand drainage layer having a hydraulic conductivity of 1 x 10-2 cm/s or greater. Synthetic drainage nets which provide an equivalent hydraulic conductivity are an acceptable alternative.

If there is any concern for the precipitation of leachate constituents causing a plugging problem, the leachate collection system is to be designed to prevent such precipitation from occurring. The drainage layer is to be designed with appropriate grades and collection piping so that the leachate hydraulic head on the liner does not exceed 0.3 metre at any time.

Operations and Processes

Sanitary landfill design needs to provide for daily cover of fresh refuse, incorporate mitigative measures to manage leachate and gas produced within the landfill cells, provide for a final soil and vegetative cover, and establish an environmental monitoring system of up gradient and down gradient groundwater monitoring wells and surface water sampling locations. Typically the daily cover material is soil; however, tarps or inert materials (i.e., construction debris or compost residuals) could be used.

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Figure 3 : Landfill Operations and Processes

A sanitary landfill is a step by step construction activity involving daily layering, compacting, soil covering of refuse into cells (Bund method), and routing surface runoff away from waste cells.

The space wherein the refuse would be placed should not be subject to seasonally high groundwater levels or to periodic flooding. The site preparation and landfilling operation must be designed to minimize contact of surface runoff and percolating rainwater with the refuse. This requires diversion of up gradient surface drainage away from the landfill operational area, sloping of the cells to avoid ponding of waters on top of them, and compaction of refuse and daily soil cover as each cell is being constructed so that infiltration potential is minimized.

Soil and Clay Liners

Soil liners are used in single liner systems. To serve adequately as a liner, a soil must have a low permeability (with a hydraulic conductivity less than 1 x 10-7 cm/s) when compacted under field conditions. After compaction, the liner should be able to support the overlying materials. The liner material should be able to withstand the construction equipment. Finally, a soil liner material should suffer no significant loss in permeability or strength when exposed to waste or leachate from the waste. A soil that is deficient in particular characteristic may be rendered suitable by blending it with another soil or with a soil additive. An example is the addition of bentonite cement to decrease permeability. Ideally, the compaction and permeability characteristics of the selected soil liner material should be determined by laboratory tests, so as to provide necessary information regarding the interrelationship between moisture content, density, compactive effort, and permeability.

Of the available materials, well-compacted clay soil is one of the most commonly used. A clay liner usually is constructed as a membrane up to 1 m thick. To function as a liner, the clay membrane must be kept moist. If sufficient clay is not available locally, natural clay additives (e.g. montmorillonite) may be disked into it to form an effective liner. The use of additives requires evaluation to determine optimum types and amounts. If it meets the necessary specifications, the native soil at the site would best satisfy cost and convenience considerations. Otherwise, a suitable soil must be imported. Obviously, transport cost

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becomes an important consideration when off-site material is used. In most cases, a haul of any distance would be impractical. The liner material, whether excavated locally or imported, usually is stored as a borrow pile established at the site.

The liner is installed by spread evenly over the site the liner material (soil or clay). The soil can be broken up and homogenized manually to facilitate compaction. If soil additives are used, they are applied evenly over the site and then are thoroughly mixed into the soil. The liner may be constructed in sections or in one piece. With a small site, the liner may be constructed in one piece over the entire area to be landfilled. Sectional (segmented) installation probably would be more suitable with large sites. In such operations, portions of the liner are built in stages. It is important that the sections (segments) be installed such that no break occurs between them. This can be done by bevelling or step-cutting the edge of a section as soon as it is installed so that the succeeding section can be tied in with the previously installed section. Because the necessary degree of compaction is dependent upon a proper moisture content, any required addition of moisture should be made prior to placement of the liner material. Care should be taken to distribute the moisture uniformly throughout the soil. This is done by allowing adequate equilibration time after the moisture addition. The time may require days or even weeks if the soil is very dry or certain additives are used.

Practices followed and equipment used in earthwork construction (compactors) are suitable for compacting a liner. The success of the compaction effort depends upon the individual liner layers being properly tied together. Tying together the layers can be accomplished by scarifying the surface of the last installed layer prior to adding the next one and ensuring that the moisture contents of adjacent layers are similar. If sidewall slopes are not very steep, they can be compacted in layers continuous with the bottom liner layers. Steeply sloped sidewalls may have to be compacted in horizontal layers because compaction equipment cannot operate on steep slopes. Tying together is especially important for steep sidewalls, because separation between layers can serve as pathways for the migration of leachate through the liner.

Soil used for lining, interim cover, and final cover should be wetted with water to reach optimum moisture (about 50%) so that good compaction can be obtained. Final soil cover needs to be sloped (2-3%) to avoid ponding of waters on top of the refuse filled area and to minimize infiltration. Grass is planted in the final soil cover to limit erosion.

Minimizing Leachate Generation

Leachate generation is derived only from a limited quantity of infiltration which reaches the waste deposit and captures the by-products of waste biodegradation. While little leachate is generated in a sanitary landfill compared to an open dump, leachate concentrations are much higher -- organics are higher by a factor of more than 10 -- and thus leachate needs to be properly treated.

At sites where potentially usable groundwater exists in unconfined layers, any rain and surface runoff waters which percolate through the refuse and become contaminated leachate need to be collected. The leachate collection system typically consists of a network of perforated plastic pipe within a gravel bed which is placed over the landfill liner. The perforations holes need to be small enough that the encasement stones do not enter the pipes.

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Figure 4 : Leachate Pipe and Liner

Figure 5 : Leachate Pipe in Gravel

Leachate pipes need to be selected to withstand the compression forces of the waste deposit and equipment operating at the landfill. Slopes of the pipe should never transition from a steeper upstream slope to a shallower downstream slope; otherwise sediment could collect at the transition point and lead to clogging. The landfill liner and the leachate collection network need to be properly sloped (about 2% slope) to enable gravity flow of contaminated waters to treatment ponds.

For most sites, the landfill liner would typically consist of relatively impermeable clay soil placed in thin layers (of about 25 cm in depth) at optimum moisture content and compacted with a roller. Good compaction of the base material is essential, to avoid uneven settling of the overlying leachate collection pipe network. Sites with clay soil liner may require the leachate collection pipes to be placed at close intervals to optimize the capture of most leachate.

Leachate treatment is typically accomplished through a series of lagoons. The lagoons are commonly designed to encourage a first phase of anaerobic decomposition, followed by facultative or aerobic decomposition. To the extent possible, full evaporation in a final storage lagoon is desirable so that no discharge of treated effluent is necessary. If full evaporation is not possible, recirculation of treated effluent back to the landfill (on the completed areas of fill), irrigation of the buffer zone of trees and bushes, discharge to a sewage treatment plant, or tanker haul to a sewage treatment plant is recommended. Discharge to surface water is acceptable only if the effluent is treated and/or diluted to a level wherein there would be no significant adverse impact on the water quality requirements of the receiving water.

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Gas Management

In addition to leachate management, landfill gas management is a critical component of sanitary landfill design. During peak periods of anaerobic decomposition, the landfill gas reaches methane concentrations of about 50%. Minimum requirements are that the landfill gases be properly ventilated to avoid build-up to potentially explosive levels and migration laterally from the site. For purposes of controlling green house gases, however, it is strongly recommended that landfills that will have a depth of over 10 meters be designed for gas recovery and use. However, for small scale landfills, gas recovery may not be required (depth of less than 4 meters of waste).

Emission reduction funds may be available to cover the full costs of landfill gas recovery, through “carbon finance”. If there is no plan to flare or recover the gas, the gas ventilation may be designed as follows: (1) during site preparation the landfill side slopes are lined with impermeable clay to curtail lateral migration of the gases and then lined with coarse rock or gravel to allow gases to escape to the atmosphere; and (2) rock-filled, wire mesh wrapped, vertical wells of about 1 m diameter are created during landfill (about every 0.1 hectare).

If flaring or recovery are anticipated, gas vents may be implemented as follows: (1) during land-filling, using horizontally or vertically installed perforated plastic pipe (about 15 cm diameter) packed in gravel, with enclosure and capping of this pipe and gravel in a larger closed pipe from the point just below the ground surface; or (2) upon completion of a specific area of the landfill, by drilling a borehole and installing a perforated pipe within gravel packing.

Stability

Side slopes of the landfill should not be more than 2.5:1 (horizontal:vertical), otherwise erosion and loss of soil cover could occur. In seismically active areas or on poor soils, slopes of 5:1 or greater could be required. It is important that soil cover exist even on the side slopes of the landfill cells, as well as on the lateral surface. Without good soil cover, air will be able to enter freely. At the interface of the air with the underground landfill gas, underground fires, once started, could more readily persist. When there are underground fires, cavities within the solid waste will develop and the surface of the landfill may collapse. Serious accidents have been known to occur in such circumstances.

Landfilling Methods

The next Table provides explanation on landfill types and methods.

Table 1 : Landfilling Methods

Methods Type of wastesExcavated cell/trench

- Adequate depth of cover material is available- Far from water table

Area -Where terrain is unsuitable for excavation of cells- High ground water conditions

Canyon /depression

- Canyons, ravines, dry barrow pits and quarries- Depends on availability of adequate material to cover the individual lifts and final cover

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Figure 6 : Excavated Cell/trench Landfill Method (Bund method)

Figure 7 : Area Landfill Method

Figure 8 : Canyon/depression Landfill Method

Construction Phasing

Construction of a sanitary landfill occurs in zones, over the life of the site. Typically each zone provides a capacity for about 1 years of solid waste. At the start of construction, the access road, entrance gate, fencing, water supply and Zone I refuse cell area are constructed.

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Figure 9 : Development of a Landfill

Figure 10 : Completed Landfill

Refuse cell development always begin from the lowest elevation of each zone. Leachate treatment facilities to handle flows generated at the peak period over the life of the site are constructed from the onset, usually at the lowest elevation of the site so that leachates from all areas can flow to them by gravity. As the capacity of the Zone I refuse cell area nears its complete utilization, the Zone II refuse cell area needs to be prepared (i.e., with base grading and compaction, lining, leachate collection networks, gas ventilation systems, etc). And so on, over the life of the site, until each Zone of the landfill is completed.

For landfill gas recovery (for purposes of energy production), the complete cover of the waste deposit would be necessary, so that gas does not escape and air does not enter and thus dilute the gas composition. Gas is recovered actively, through vacuum pumping to preserve the methane content.

Siting

Each sanitary landfill is uniquely designed to conform to the soil, geologic, topographic, and water resource conditions of the site. To minimize the costs of operating a sanitary landfill, the first and most critical step is proper siting in a location which enables economic operations and cost-effective environmental protection. Also, proper siting is essential to minimizing the cost of refuse collection. The following site selection criteria are provided as guidance.

A proposed landfill site can be selected even though it does not meet each of the screening criteria. Engineering design can mitigate inadequate site conditions -- but at a cost. When selecting a site which does not meet all of the screening criteria, possible engineering

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solutions which would bring the site into conformance with the intent of the unmet criteria shall be incorporated in the design.

Figure 11 : Sectional View - Sanitary Landfill

Environmental Requirements

Solid waste components which involve new sanitary landfills require detail environmental studies under the Organic Law. The following activities are typically required to be accomplished prior to project appraisal: (1) documentation that site selection has been conducted to address the type of siting criteria listed below; (2) an environmental report to describe the site selected, outline potential environmental impacts of sanitary landfill at the site, and propose mitigative measures; (3) public education and local consultations with residents in the vicinity of the proposed sanitary landfill, including an open forum where all interested parties have an opportunity to express their opinions concerning site selection; (4) compensation and resettlement action plans for affected parties; and (5) conceptual design and budgetary costing of the sanitary landfill, including mitigative measures identified in the environmental report and responsive to the local consultations.

Private Sector Involvement

Sanitary landfill is a public good, because benefits of environmentally sound disposal are derived collectively. Nevertheless, private sector involvement, if properly arranged, can increase the likelihood that landfill design and operation specifications will be followed. Ideally, the landfill would be designed, built, owned and operated by a private identity or NGO under a concession agreement. If government decides to build and own the facility, a private identity such as NGOs could provide operation if tipping fees are well established.

Transit and Collection Sites

Waste transfer stations are facilities where municipal solid waste is unloaded from collection vehicles and briefly held while it is reloaded onto larger vehicles for shipment to landfills. These could be located, for example, in the neighbourhood of a market. There is need to have these transit site in case the wastes cannot be directly transported to the landfill site. They can also reduce the total number of vehicular trips traveling to and from the disposal site. Although waste transfer stations help reduce the impacts of trucks traveling to and from the disposal site, they can cause an increase in traffic in the immediate area where they are

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located. If not properly sited, designed and operated they can cause problems for residents living near them.

3.2.2 Landfill Siting Criteria

Minimum Acceptable Standards

These are specific minimal acceptable standards to be used in the siting of the landfill. - Adequate land area and volume to provide sanitary landfill capacity to meet projected

needs for at least 5 years, so that costly investments in access roads, drainage, fencing, and weighing equipment are justifiable. For siting purposes, land area requirements shall be estimated based on the landfill cell area required (typically for a depth of 10 meters; a final solid waste density of 800-1,000 kg/cubic meter, and a minimum soil to refuse ratio of 1: 6), as well as about 2 hectares for the receiving area, 2 hectares for the leachate treatment and/or evaporation ponds, and additional 10% land for a landscaped buffer zone.

- Preferably, a site accessible within 30 minutes travel time is to be sought because of the need to avoid adversely affecting the productivity of collection equipment. At distances greater than 30 minutes travel or collection operations may not be economically viable.

- Accessible from a public road which has an adequate width, slope, visibility and construction to accommodate the projected traffic. To minimize landfill development costs, the requirement for new access road construction generally should be less than 2 km for small landfills serving secondary cities.

- A gently sloped topography, preferably amenable to development of sanitary landfill by the cell (Bund method), with slopes which minimize the need for earthmoving to obtain the correct leachate drainage slope of about 2%.

- Groundwater's seasonally high table level (i.e., 10 year high) is at least 1.5 meters below the proposed base of any excavation or site preparation to enable landfill cell development. A minimum depth of 1 meter of relatively impermeable soils above the groundwater's seasonable high level exists (preferably, less than 10-7 cm/s permeability when undisturbed). If this criterion is not met, use of impermeable clay may be required to protect groundwater quality.

- Availability on-site of suitable soil cover material to meet the needs for intermediate (minimum of 30 cm depth) and final cover (minimum of 60 cm depth), as well as bund construction (for the cell method of landfill). Preferably, the site would have adequate soil to also meet daily cover needs (usually a minimum of 15 cm depth of soil). However, daily cover needs can be alternatively met by using removable tarps, other relatively inert materials (i.e., compost residuals), or by removing the previously laid daily soil cover at the start of each day for reuse at the end of the same day. For purposes of siting, assume that at least 0.5 cubic meter of daily, intermediate, and final compacted soil cover is needed for every 3 cubic meters of compacted refuse. In areas with highly organic wastes and warm climates, compacted refuse (after one year of natural consolidation and decomposition within warm and wet climates) achieves a density of 800-1000 kg/cubic meter.

- None of the areas within the landfill boundaries are part of the 10-year groundwater recharge area for existing or pending water supply development.

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- No private or public drinking, irrigation, or livestock water supply wells within 500 meters down gradient of the landfill boundaries, unless alternative water supply sources are readily and economically available and the owner(s) gives written consent to the potential risk of well abandonment.

- No environmentally significant wetlands of important biodiversity or reproductive value are present within the potential area of the landfill cell development.

- No known environmentally rare or endangered species breeding areas or protected living areas are present within the site boundaries. If this criterion is not met, alternative habitats of comparable quality for relocation of the species would need to be available.

- No significant protected forests are within 500 meters of the landfill cell development area.

- No open areas of high winds.

- No major lines of electrical transmission or other infrastructure (i.e., gas, sewer, water lines) are crossing the landfill cell development area.

- No underlying limestone, carbonate, fissured or other porous rock formations which would be incompetent as barriers to leachate and gas migration, where the formations are more than 1.5 meter in thickness and present as the uppermost geologic unit above sensitive groundwater.

- No underlying underground mines which could be adversely affected by surface activities of landfilling, or minable resources which could be rendered less accessible by landfilling, unless the owner(s) gives explicit consent.

- No residential development within 250 meters from the perimeter of the proposed landfill cell development.

- No visibility of the proposed landfill cell development area from residential neighbourhoods within 1 km. If residents live within 1 km of the site, landscaping and protective beams would need to be incorporated into the design to minimize visibility of operations. Curving of the access road is recommended to avoid visibility of the active portions of the landfill from the main road.

- No perennial stream within 300 meters down gradient of the proposed landfill cell development, unless diversion, culverting or channelling is economically and environmentally feasible to protect the stream from potential contamination.

- No significant seismic risk within the region of the landfill which could cause destruction of drains or other civil works, or require unnecessarily costly engineering measures, otherwise side slopes may need to be adjusted to be gentler than the maximum of 2.5:1.

- No fault lines or significantly fractured geologic structure within 500 meters of the perimeter of the proposed landfill cell development which would allow unpredictable movement of gas or leachate.

- No siting within 3 km of an airport. Aviation authority should provided written permission stating that it considers the location as not threatening to air safety.

- No siting within a floodplain subject to 10-year floods and, if within areas subject to a 100-year flood, must be amenable to an economic design which would eliminate the potential for washout.

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- Avoid siting within 1 km of socio-politically sensitive sites where public acceptance might be unlikely (i.e., memorial sites, churches, schools) and avoid access roads which would pass by such culturally sensitive sites.

3.2.3 Landfill Operational and Performance Criterion

Prohibited Wastes

The disposal of the following wastes with the rest of the municipal solid waste is prohibited: Hazardous Wastes other than those specifically authorized in the Hazardous Waste

Regulation; Bulk liquids and sludge which contain free liquid; Liquid or semisolid wastes including septage and sewage treatment sludge; Automobiles, white goods, other large metallic objects and tires (except in the case of

where recycling options are available; and Biomedical waste.

General Operations

There is no sensible reason to design and prepare for a better-engineered landfill if, subsequently, it is not operated in a better way than an open dump. There are two "classic" requirements of a sanitary landfill:

Wastes should be deposited and compacted in thin layers to no greater than about 2 m in depth.

Each day the surface of the newly deposited waste should be covered with approximately 10 cm of soil (or similar material).

The introduction of these requirements should be within the capabilities of most imidugudu, small towns and cities. A good standard of waste placement is the foundation for a better managed landfill. Safe and well-organized placement of waste distinguishes a controlled landfill operation from an open dump. Even the best designed and prepared landfill site will have many operational and environmental problems if it is operated badly.

A competent landfill manager should be based on site full-time and have enough delegated authority to get things done. A disposal plan should be used to guide the operation of the site. In brief, the plan should provide a detailed explanation of the following:

Where waste is going to be placed during each phase of the site's lifetime? What site preparations and engineering are required during the site lifetime? How to deal with environmental nuisances (e.g., birds, litter, vermin, fires, gas, and

leachate)? What equipment, materials, and staff are needed to run the site? (e.g. wheelbarrows,

boots, gloves, etc.) What documentation and administration is need? What monitoring will be undertaken? When and how each part of the site will be completed and restored?

The operational period of a landfill is the longest single stage in a site's lifetime. During this time senior management attention will be required on several occasions to resolve problems and issues beyond the capabilities of the landfill manager based at the landfill. Potential operational problems may be minimized by giving careful consideration to two key management decisions:

Who should operate the landfill? i.e. CBOs, association or private companies Has enough money been made available to finance operations at the landfill? The

operation of a better-managed landfill will in almost all situations cost more than open dumping.

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A wide range of operational problems can occur at landfills as suggested in the next table.

Table 2 : Operational Problems at LandfillsPROBLEMS SOURCE/CAUSESLeachate Pollutants that escape to contaminate surface or groundwaterFires Due to self-ignition or mixing of incompatible substances; rupture of drums

containing oxidizing substancesDust From wastes or from dry soil surfacesOdours and gases (chiefly methane and carbon dioxide)

From wastes and their decomposition

Handling hazards Due to hazardous wastes being acceptedAlso a problem if scavengers have access to the site

Vermin Rats, birds, flies, and other vectors breeding, living or feeding on any food wastes brought onto sites and spreading disease and nuisance to off-site areas

Litter and wind-blown rubbish (e.g., plastic and paper

Often a problem on access roads as well as the site itself

Visual intrusion Due to height of cellsNoise Due to waste transportationRunoff of sediment-laden or polluted water

Due to bad cell covers

Uneven settling or consolidation Due to soluble or putrescible wastes, or containers rupturing under pressure

To minimize or prevent these problems, the waste manager should be given resources to achieve the routine operational procedures listed below:

o Waste should be compacted into thin layers, each up to 300 mm in depth, and, in turn, these layers should be built-up into a total thickness of about 2 m. This improves the density of the waste and reduces the likelihood of voids and bridges within the waste that could cause instability and settlement problems in the future. The daily working area for waste placement should be kept as small as possible, say, no more than 0.1 hectare, at most sites.

o Compacted waste should be covered with up to 10 cm of soil or similar material at the end of each working day. This measure reduces the infestation of waste by flies and other insects.

o No biodegradable waste should be deposited in surface water. This practice contaminates the water and could become a source of water pollution.

o Open burning of waste should not be permitted. If a fire is detected it should be extinguished quickly.

o Inspections for vermin should be frequent and measures taken to prevent infestations. Vermin (i.e., rodents, other animals, flies, and birds) are a health risk. They should not be tolerated in excessive numbers anywhere.

o Litter should be collected regularly from around the site.

o Drainage ditches should be kept free of blockages.

o Site access roads should be regularly inspected and repaired.

o A record should be kept of all waste deliveries to the site.

o Environmental monitoring should be performed routinely and records kept at the site as evidence of the impact that the site has (or does not have) on the

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environment. Environmental monitoring can take many forms, ranging from relatively simple observations to very complex sampling and chemical analysis. The amount of environmental monitoring that is realistic to undertake has to be determined according to each landfill, the equipment available, and the existing environmental conditions in the locality. There are two main reasons for taking water quality samples. The first is to safeguard the environment and public health. The second reason for water quality monitoring is to provide information to the landfill manager on the composition of the leachate within the landfill. This is useful to demonstrate or disprove, that landfill leachate caused an off-site pollution problem, and to indicate the state of waste decomposition conditions within the deposited waste.

o The public should be excluded from the site for their own safety. Scavenging should be discouraged. Where, for social, economic, or other reasons, this is not a realistic possibility, areas away from the working area for waste placement should be provided to contain and minimize the disturbance from scavenging activities.

The minimum level of staffing will vary depending on the quantity of waste received at a site and the method of landfilling in operation.

Performance Criteria

The specific approaches and methods to be employed at the landfill for each of these activities should be included in the site disposal plan written during the design phase of the site. The daily operations at a managed landfill fall into three general groups of activities:

1) Waste reception

Access control: The first step in controlling the way waste is brought to the landfill, and the types of waste disposal, is to control the access to the site.

Records: A landfill should have a gatehouse and office in which a gate keeper records the details of each load: the type of waste, its source (location), and an approximation of the quantity of waste being carried.

2) Waste deposition

Waste placement and compaction: The careful placement of waste is an essential aspect to a better standard of landfill operation. Landfills will use compactors to ensure that all waste is well crushed and compacted to give the best possible filling density. This approach reduces the quantity of air remaining in the deposited wastes (which can lead to accelerated decomposition, strong odour, the propagation of surface fires, and water pollution). The waste will be spread in a thin layer (no more than 300 mm deep). The thin layers of waste are crushed by the weight of the compacter machine. Not all waste will be small items which are easily compacted. Most landfills will receive some "bulky" items. To avoid creating large voids within the landfill, it is important that larger items, such as old furniture, animal baskets and cages, and packaging boxes and containers, are crushed by the landfill equipment before compacting and spreading into thin layers. Tires are relatively resistant to being crushed and preferably should be cut up before placement. Noxious and potentially infectious items such as animal carcasses, animal and fish wastes, condemned food, permitted healthcare wastes, and waste oils and liquids, should be covered immediate after placement at the bottom of working face. Alternatively, such waste should be deposited and covered in excavated trenches in parts of the landfill

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previously filled with wastes. Both approaches also require scavenging to be controlled to avoid these waste materials from being dug up.

Application of soil cover: As noted earlier, it is common to cover waste regularly (often daily) with soil, up to a depth of 10 cm. Where sites have a shortage of soil, they will inevitably use less cover material. Waste may be left waste uncovered for more than one day and a thinner layer of soil covering may be spread when cover is applied. The application of some soil cover is generally regarded as an important aspect of operating a better-managed landfill site. The spreading of soil cover can be carried out manually. The daily soil cover can come from soil-like wastes that are stockpiled at the site, or excavated from on site or a nearby borrow area. To avoid creating perched leachate water tables within the body of the waste, with consequent risks of slope instability or leachate breakout (springs) through the sides of the landfill, daily cover soils that are of low permeability should be scraped off or at least scarified immediately before being covered with further layers of waste. This will allow better vertical movement of leachate through the underlying waste.

Intermediate and final covers and cell construction: Several earthmoving operations have to be periodically undertaken at a landfill. On areas of the landfill that have been partially completed, but where further waste placement will not recommence for several weeks or months, "intermediate" soil cover should be spread. This is typically a thicker layer of daily cover, between 25 and 50 cm, which acts as a partial seal to restrict most surface and rain water movement down into the wastes, and prevents accidental exposure of the waste to sites workers and pests. Intermediate cover can be spread by mechanical equipment or manually, and should, preferably, have a gentle slope (at least a 1 in 50 gradient; i.e., 2% slope) away from landfill areas. As parts of the landfill are filled to their final, pre-planned elevation, a final cover (or cap) should be placed over the waste. This provides the long-term seal to isolate the waste from surface water entry and prevents release of odours and leachate.

Mechanical landfill equipment: Important investment decisions on the type of landfill

equipment are needed. Several factors influence the number and type of equipment the manager should obtain. The basic functions served by landfill mechanical equipment are functions related to soil (excavation, handling, compaction), functions related to wastes (handling, compaction) and support functions. Depending on the type and size of the operation, the same piece of equipment may be used for more than one of the three functions. Versatility and ease of handling are essential considerations in the selection of equipment likely to be used for more than a single purpose. The need for excavation, handling, and compaction of soils used as liner and cover material should be considered when choosing landfill equipment. Procedures and equipment to achieve these tasks differ only slightly from those used in other earth-moving operations. The waste-related functions served by equipment include spreading and compaction. Achieving good waste compaction has many short- and long-term effects on the operation of the landfill and the rate and extent of waste settlement, and is an important factor in maximizing the overall capacity of the landfill. Landfill equipment must be rugged because operational conditions for equipment used on a landfill are tough. The costs associated with the operation and maintenance of the mobile equipment used in landfills account for a major portion of total operational costs.

3) General site maintenance and control

Surface water management: The prevention of water entering landfilled waste is a continuing requirement throughout the operation of a better-managed landfill. Surface water, which might enter the landfill from outside the site, should be intercepted by

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perimeter drainage ditches (also known as storm water cut-off drains). Temporary drainage ditches in unused parts of the landfill, especially if located in a quarry or similar place, may be used to stop "clean" rainwater from moving laterally across the site and coming into contact with waste. Routine operational requirements include inspecting, cleaning, and maintaining the existing surface drainage channels. This usually requires manual labour. It is essential after seasonal effects such as vegetation die-off, or strong winds blowing dust and debris. If such materials accumulate in the channels, they could cause blockages and overflowing when the next severe rain occurs. Drainage channels should cleared a minimum every six months and more frequently where seasonal heavy rainfalls occur more regularly.

Fire control: Open fires should not be allowed on a well-managed landfill. If a fire breaks out, it should be extinguished as quickly as possible to prevent it travelling deeper into the deposited waste. The most common technique, at sites where leachate minimization is to be practiced, is to excavate a trench around the burning area of waste to isolate it from the remainder of the site, and then the burning waste is smothered with sand or soil. Only in exceptional circumstances should water be used. Appropriate sources of water might be nearby rivers or lakes, on-site lagoons retaining collected rainwater, or even surface leachate ponds. In extreme circumstances, city fire tenders may be used. An alternative technique to extinguish shallow fires is to dig a "firing hole" where the burning waste can be exposed to the air, to either burn out rapidly or be smothered with sand.

Pest control: Pests (e.g., birds, vermin, larger animals, and flies) are a large nuisance to workers and the surrounding inhabitants to a landfill. They are a potential public health risk that could be avoided. The abundance of pests around an open dump is a clear indication that poor waste management is being practiced.

Litter control: A landfill is not well managed if paper (litter) or other lightweight material is blowing around the site. Litter is a highly visible sign of poor control of the waste being deposited. It is also one of the simplest forms of pollution to contain. Litter should be cleaned manually at least once per day, at the end of each day, by landfill workers.

Leachate control and monitoring: The minimum that should be achieved at a managed landfill operation is to keep clean surface and groundwater separated from the waste. The construction of interception ditches, water collection ponds, and soil walls are all intended to achieve this. Leachate is created from water already present in the waste, or entering from outside, moving through the deposited waste. Rainwater and poorly controlled groundwater are the two main sources of water entering deposited waste. Surface entry can be restricted by effective surface water diversion, having only a small working face open to the atmosphere, and through the use of daily soil cover. Leachate contains extracted contaminants from the decomposing waste. The polluting potential from this leachate depend on several factors including the quantity of free liquid not absorbed into waste, concentrations of pollutants in the leachate, rate at which leachate can leave the site, proximity of leachate beneath the site coming into contact with drinking water supplies, and ability of environmental, physical, chemical and biological processes to reduce the concentrations of pollutants before they come into contact with water supplies. Every landfill produces a unique combination of pollutant concentrations which also vary over time. Even at the minimum standard of landfill operation described in this Guide, some leachate monitoring will be necessary. There is no universal approach to managing leachate. If the site has been designed to allow some seepage of leachate into the underlying strata, no collection or treatment of leachate is needed. Groundwater should still be monitored to check that the leachate concentrations are

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continuing to be diluted and are acceptable. At least as frequently as every six months, monitoring should be conducted by analyzing samples taken from borehole(s) located down gradient of the site.

Gas control and monitoring: One feature of a better-managed landfill operation is that more of the waste will decompose anaerobically, i.e., in the absence of air (oxygen). In open dumps most waste is burnt or decomposes in the presence of air (aerobic decomposition). The presence of air leads to worsening odours and a more polluting leachate. Anaerobic decomposition ultimately leads to the production of landfill gas (a mixture of carbon dioxide and methane gas, as well as traces of other gases). This gas has to be monitored and controlled whenever there is a potential risk of accumulations of flammable concentrations in the site or from landfill gas migrating off-site. The generation of landfill gas should be considered as inevitable. The natural tendency of landfill gas is to migrate upwards, from those areas where waste is placed, eventually dispersing into the atmosphere. In sites where upward migration of the landfill gas is restricted, it will begin to travel laterally, and, depending on the local geology, perhaps even migrate off-site. Wherever possible, landfill gas vented through vertical pipes should be ignited to oxidize the methane to the less potent greenhouse gas (carbon dioxide). The minimum monitoring requirement for landfill gas should be to check for the presence or absence of landfill gas in wells, under buildings, and in underground ducts and chambers.

Record-keeping: An integral part of site operation and maintenance is the formal keeping of records for both quality control and management purposes. There are, broadly, five classes of records that a landfill manager should establish. Even with a minimum standard of operation, an attempt should be made to keep records in each of the classes: equipment maintenance; daily operation; environmental monitoring; and financial revenues and expenditures.

Accommodating on-site scavenging (informal recycling): Scavenging on landfill sites should be actively discouraged, since it is disruptive to safe and well-managed landfill operations. However, where on-site scavenging cannot be completely prevented, operational decisions have to be made about its control. The key to managing the problem is gaining the agreement of the scavengers to restrict their activities to areas and times which suit the operators of the landfill. The minimum approach is to separate scavengers away from the landfill working face. Unfortunately, such a spatial separation requires subsequent transfer to the landfill working face the residue that remains after scavenging. If the scavenging area is kept relatively close to the working face, transfer of residue to the working face may be done quickly. Such an arrangement would demand that the scavenging area be movable. The two sites must not be so close as to promote mutual interference between scavengers and landfill machinery. Alternatively, a permanent scavenging area could be located some distance from the working face. In this case, the remaining residue would need to be picked up and transported to the working face. A fixed scavenging area would be neither feasible nor advisable for a small disposal site. A permanent site for scavenging may take on many of the characteristics of a simple transfer station. Waste could be deposited onto a platform and after sorting, the rejects would be loaded into a site vehicle and carried to the working face. Scavenging may be done in a fixed area and may also be sheltered from the elements (wind, rain, etc.). The operation itself should be kept orderly and controlled closely, and abuses discouraged. A storage area for recovered materials should also be included in the layout of a permanent site. Efficiency of recovery may be improved by including a certain amount of mechanization (e.g., conveyor belts and screens). This alternative would also allow for the provision of sanitary facilities and a better working environment for the scavengers.

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Protective clothing: The health and safety of the work force may be enhanced by providing staff with personal protective clothing. Each worker at the landfill should be issued i.e. overalls, working boots, gloves, dust mask, goggles and hard hats. Staff should be made personally, and possibly financially, responsible for the safekeeping of their personal equipment. They should be required to keep their safety equipment clean and serviceable. Every member of staff should receive training on the work they are expected to undertake. It is poor management to expect new staff to know how to work safely and efficiently, or to hope they can achieve this by guesswork or copying others.

3.2.4 Landfill Closure Plan

A closure plan for sanitary landfills will specify at least the following: Anticipated total waste volumes and tonnage, and life of the landfill (i.e. closure

date); A topographic plan showing the final elevation contours of the landfill and surface

water diversion and drainage controls; Design of the final cover including the thickness and permeability of barrier layers

and drainage layers, and information on topsoil, vegetative cover and erosion prevention controls;

Procedures for notifying the public about the closure and about alternative waste disposal facilities;

Rodent and nuisance wildlife control procedures; Proposed end use of the property after closure; A plan for monitoring groundwater, surface water and landfill gas, erosion and

settlement for the post closure period; A plan and accompanying design for the collection, storage and treatment/use of

landfill gas; A plan for operation of any required pollution abatement engineering works such as

leachate collection and treatment systems. An estimated cost to carry out closure and post-closure activities.

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3.3 SMALL-SCALE COMPOSTING FACILITY GUIDELINE

In areas where compost is a marketable product and the market is willing and able to cover the additional cost (i.e., above the cost of sanitary landfill) of producing compost, composting should be conducted at the sanitary landfill site. If composting shares the landfill site, the investment for access, fencing, gate control, water supply, electricity, and equipment can be shared -- thus lowering the production cost of compost to potentially affordable levels.

In most areas, up to 30 to 50% of wastes to the sanitary landfill are from sources which have wastes of good quality for composting, such as wastes from purely residential neighbourhoods, and wastes from special generators such as markets, restaurants, and slaughterhouses. If the compost operation shares the same facility as the sanitary landfill, the gate keeper could divert only the loads with appropriate quality of wastes to the composting operation. Rejects and residuals from the composting process could be readily discharged to the sanitary landfill. And, finally, if rainy season conditions inhibit the ease of composting, the operation can be conducted during dry seasons only. Location of composting at the sanitary landfill thus optimizes quality control of the product, flexibility for the operation, and cost minimization.

The aim of these guidelines is to provide some basic information on the composting process as well as to offer guidelines relating to the siting and operation of composting facilities in Rwanda. These guidelines will help ensure that compost can be produced without adversely affecting human and animal health, food production and the natural environment. The objectives of these guidelines are:

1. To allow for the evaluation of composting operations while ensuring that the environment is protected.

2. To bring composting operations into conformity with the provisions and recommendations of these Guidelines so that environmentally undesirable practices will be avoided.

3. To assist individuals involved in composting operations to comply with the conditions and recommendations of these Guidelines by avoiding unacceptable environmental conditions which could lead to disputes concerning pollution.

3.3.1 Composting Facility Design Criteria

General Principles

This guideline permits and encourages innovative, effective and better solutions for environmental management of composting. Composting is the controlled biological decomposition or treatment of an organic part of a material to a condition sufficiently stable for nuisance-free storage, and for safe and beneficial use in land applications. Composting is a natural process which provides several benefits: the process can be inexpensive; it addresses over 50 % of a small town's waste stream; it enhances related recycling and incineration activities; and it can produce a beneficial end product with unlimited marketing potential. It simply recycles organic material back to the topsoil from where it is mined through typical agricultural practices.

Composting has been used for hundreds of years to convert organic waste to a rich, humus-like soil amendment used in agriculture and horticulture. Composting speeds up the natural decomposition processes to break down waste. In order for this to occur the micro-organisms need the proper amounts of air, water and nutrients. During the decomposition process organic matter is returned to simple chemical compounds which plants can use. Heat, water vapour, and carbon dioxide are released during the process. The heat release also causes the

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destruction of harmful pathogens and weed seeds in compost. Successful composting depends primarily on adequate temperature and moisture control, oxygen supply and nutrients to feed the microbial populations. Potential raw materials for composting include the compostable fraction of municipal solid waste, yard, garden and leaf wastes, agricultural crop residues and animal manures, fish waste, food processing wastes, forest products and paper product wastes and other biodegradable wastes from industry and other sectors. The primary objective of composting is to recover and recycle a valuable resource in an economic and environmentally acceptable manner.

The quality of the compost produced depends upon controlling the type of waste composted to minimize potential contaminants such as heavy metals and hazardous organic material. These control measures may include picking out potential problem materials prior to the composting process, excluding industrial sludge and source separation of organic material. It is important to maintain quality control over the compost. The quality of the compost produced will affect marketability of the material and has the potential to impact on the environment.

Composting is a cornerstone of sustainable development, yet it is often neglected within integrated municipal solid waste management programs. However, composting can only be part of municipal solid waste programs if adequate recognition is given to the need and costs associated with proper waste disposal; nothing is cheaper than not collecting solid waste.Composting is obviously not a panacea to today's vexing waste management problems; but it should be an important component within most integrated municipal waste management strategies.

This guideline views the role of composting from the perspective of a municipal solid waste manager; an equally relevant perspective would be that of the agriculture sector. Composting is one of the simplest ways to prevent emissions of methane because the organic fraction of the waste stream is diverted from landfill. While composting does release carbon dioxide, it is currently considered to be a neutral process since the removal of carbon dioxide from the atmosphere by photosynthesis to produce organic matter is also not considered. Landfill leachate is created when water percolates through the waste and biological and chemical constituents from the waste are brought into solution. Depending on the landfill design and prevailing weather conditions, composting may not significantly reduce the quantity of landfill leachate, but it will improve the quality of the leachate. This is achieved by reducing the concentrations of biochemical oxygen demand (BOD) and phenols produced as a by-product from the decomposition of leaves and metals mobilized by the formation of carbonic acid from the decomposing organics. Composting may also produce leachate, potentially high in BOD and phenols, which should not be discharged into water bodies. Collecting and re-circulating the leachate into active compost piles will mitigate any environmental impacts while at the same time enhance the compost process (the composting process is usually a net-water user).

Organic matter constitutes a significant portion of municipal solid waste. Diversion of organic materials from landfilling extends the life of the landfill by reducing the amount of waste to be disposed. Odours are produced when conditions inside the compost pile become anaerobic through a lack of oxygen. A well operated composting facility should produce minimal objectionable odours.

The final compost product can be beneficially used as a soil amendment. Recycling organic matter back into agricultural applications improves overall soil conditions by: developing and maintaining soil structure and improving physical properties, decreasing susceptibility to erosion, encouraging microbial activity and providing potentially available plant nutrients. The effects of chemical fertilizers compared to compost are often misunderstood. The main difference between the two is that the nutrients contained in the chemical fertilizer are used

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rapidly but incompletely, whereas the nutrients supplied by the compost are used slowly and stored in the soil over an extended period. Chemical fertilizers are generally preferred over compost because they are easy to handle, store, and apply. However, a synergistic relationship exists between compost and chemical fertilizers, and greater fertilizer efficiency can be established through the use of compost in conjunction with chemical fertilizers. The application of compost to agricultural soils may also help to suppress certain plant pathogens and reduce the incidence of disease.

Over 50 % of an average municipal solid waste stream could be readily composted. Composting is a relatively simple process; the compost operator helps nature take its natural course. Composting is highly compatible with other types of recycling. Diverting organic material helps to increase the recovery rate of recyclable materials, while at the same time, recycling programs for glass and plastics, which are common compost contaminants, improve the quality of the finished compost.

Table 3 : Benefits and Constraints of Composting

Benefits of Composting Constraints of Composting Increases overall waste diversion from final

disposal, especially since as much as 50% of the waste stream is compostable.

Enhances recycling, landfill and incineration operations by removing organic matter from the waste stream.

Produces a valuable soil amendment-integral to sustainable agriculture.

Promotes environmentally sound practices, such as the reduction of methane generation at landfills.

Enhances the effectiveness of fertilizer application.

Can reduce waste transportation requirements.

Flexible for implementation at different levels, from household efforts to centralized facilities in small towns.

Can be started with very little capital and operating costs.

The climate in Rwanda is optimum for composting.

Provides an excellent opportunity to improve a town’s overall waste collection program.

Can integrate existing informal sectors involved in the collection, separation and recycling of wastes.

Inadequate attention to the biological process requirements.

Over-emphasis placed on mechanized processes rather than labour intensive operations.

Lack of vision and marketing plans for the final compost product.

Poor feed stock which yields poor quality finished compost, for example heavy metal contamination.

Poor accounting practices which neglect that the economics of composting rely on externalities such as reduced soil erosion, water contamination, climate change, and avoided disposal costs.

Difficulties in securing finances since the revenue generated from the sale of compost will rarely cover processing, transportation and application costs. "Subsidies" may be required to maintain programs.

Sensible preoccupation by municipal authorities to first concentrate on providing adequate waste collection.

Inadequate pathogen and weed seed suppression nuisance potential, such as odours and rats.

Poor integration with the agricultural community.

Land requirements are often minimal, but can be a constraint, especially in Rwanda.

All organic matter will eventually decompose; however, some materials are more suitable for composting than others. The raw materials which are most appropriate for composting include:

Vegetable and fruit waste; Farm waste such as coconut husks and sugar cane waste; Crop residues such as banana skins, corn stalks and husks; Yard waste such as leaves; Grass and trimmings; sawdust; bark;

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Household kitchen waste; and Human excreta and animal manure.

All of these organic materials are readily found in municipal solid waste generated in small towns and rural areas.

Figure 12 : Recycling Principles

Animal waste, such as carcasses and fish scraps, can be used as well but they are more likely to attract unwanted vermin and generate odours. Other organic matter such as wood, bones, green coconut shells, paper and leather decompose very slowly and hinder the composting process. Composting occurs whenever there is sufficient oxygen, water and ambient temperatures. Designing a composting system usually involves optimization between: transportation, land, labour, and capital costs, feedstock, and markets. There is never one "right answer" but rather several possible options. For example, combinations of community and large-scale composting facilities should be encouraged to reduce municipal costs.

Residential Composting

Household composting can be a simple way to manage kitchen and garden wastes. This type of composting effectively reduces waste quantities for collection, thereby improving efficiency and reducing operating costs. Residential composting should be promoted when a significant number of homes have individual or collective yards or gardens and there is sufficient space. Composting units can be made out of locally available materials such as wood, bamboo, clay bricks, wire mesh, etc. The design and operation of the composters should not attract rodents, insects, or other scavenging animals. Keeping large quantities of meat, fish and fatty food out of the composter is the best way to keep pests away from the unit. Public health officials may discourage household composting because of perceived health risks, however, this concern can be overcome through public awareness programs, providing subsidies for basic composting units, and promoting education on compost processes, e.g. how to minimize the presence of rodents and flies.

Decentralized Community Composting

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Decentralized composting at a neighbourhood or community scale provides small groups a way to compost at a relatively low cost. Households, commercial establishments (e.g., small markets or shops), and institutions (e.g., government buildings, schools) in an area generating between five and 50 tonnes of organic waste per day can compost on vacant land, beside community gardens , or in public parks. Local governments can support the project through public education, providing land for the facility, assisting with start-up costs, transporting and disposing of rejects to local landfills, and using the final compost in public parks. To ensure that the composting operation is environmentally and socially acceptable, the following requirements are suggested: The site be accessible to all individuals who want to use it; The site be clearly designated with signs which all users and non-users can understand; The site has approval from all surrounding land users; The site has adequate controls to prevent it from becoming an area for local dumping; The site has appropriate soil and drainage to accommodate the leachate.

Even though organic decomposition is a natural process, health and safety issues exist for workers and neighbouring residents that need to be addressed. Establishing compost standards and taking precautions in the facility design and operations should assist in the mitigation of any negative health and safety impacts.

The establishment of a successful composting facility hinges on making the right choices to optimise environmental and economic factors, before capital is spent. Compost production facilities may exist for a variety of purposes, for example: The supply of soil amendments or fertilisers; The diversion of waste from landfill, for land regeneration or landfill cover; and The treatment of waste to reduce the cost of disposal or to reduce pathogens.

The selection of the composting technology depends on: The purpose of the facility; Market requirements and product quality; The availability and nature of the wastes; How easily particular wastes respond to the biological process; The siting options available, and; The production capacity of the facility.These factors must considered by a compost facility operator to select an appropriate combination of siting and technology.

All activities associated with the composting operation need careful selection, design and control to avoid environmental impact. Activities to be considered include: Transport; Raw material or feedstock storage and control; Materials handling; Screening, sorting, blending, mixing; Curing, storage, loading, dispatch; Disposal of residual waste.

Composting Processes

Essentially there are three basic steps to composting. The raw material is prepared, the composting process takes place and then the final product is graded and prepared for sale. There are four basic kinds of process technologies: windrow; static pile (forced aeration); in-vessel; and vermicomposting.

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The main difference between the systems is the way aeration of the material is accomplished. There are various methods of aeration including agitation, injection and a combination of the two. Agitation can be accomplished by turning, tumbling or stirring. Air injection, or forced aeration, is accomplished by forcing or drawing air through the composting mass. Injection often is used in combination with agitation. Individual in-vessel compost systems may depend entirely on agitation or injection, or may use them in combination.

Of the composting technologies, the turned windrow and forced aeration methods are usually classified as "open" systems as typically they are not contained in a structure. Both of these systems use elongated piles, referred to as windrows, to manage the composting material. In-vessel composting systems can be categorized as an "enclosed" system as the compost is mixed mechanically in a structure. Many of these systems use a vessel to accomplish the mechanical mixing of the compost and the other stages occur in windrows. Such combinations can be referred to as hybrid systems.

Windrow Composting

Windrow composting is a simple and versatile method where organic matter is built into large piles and physically turned on a regular basis. Regular turning of the windrows helps oxygenate the pile; breaks up particles to increase surface area; improves the porosity to prevent settling and compaction; and allows trapped heat, water vapour, and gases to escape. A turning schedule should be established based on the rate of decomposition, moisture content, porosity of the material, and the desired composting time (often a function of land availability). The frequency of turning the windrow should be adjusted as the rate of decomposition decreases with time. Manual labour is used for windrows of a smaller scale when the additional cost and use of machinery is not feasible. The porosity of the raw material affects the air flow within the windrow. Dense materials, such as manure, require smaller windrows to minimize anaerobic zones, whereas more porous and lighter materials, such as leaves, can be built into larger windrows. A balance needs to be achieved between proper aeration and temperature requirements since small windrows tend to dissipate heat quickly and may not reach adequate temperatures to kill pathogens and weed seeds.

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Figure 13 : Windrow Composting

The Passively Aerated Windrows method is very similar to windrow composting except that turning is not required for aeration. Air is supplied to the organic material through perforated pipes embedded in the pile. The chimney effect is created by the warm gases rising out of the windrow causes air to flow through the pipes. A porous base is built out of peat, compost, straw, or grass . The organic material is thoroughly mixed before being place on top of the base to ensure proper air distribution and prevent uneven composting. A covering of peat or compost is layered on top of the material to provide insulation, prevent flies from breeding, and reduce moisture losses and odour emissions. Vertical and horizontal bamboo poles can provide aeration to the decomposing organic material. A cover of clay mixed with straw is placed on top of the pile to prevent heat and moisture losses. When the clay dries, air ducts are created within the pile by removing the bamboo.

Aerated Static Pile

The aerated static pile method combines techniques from passive aerated windrows with more advanced technology. This method also builds the material into a pile on top of a porous base and then covers it with a layer of peat or compost, but it also uses a blower and pipe network to force air through the material. Bulking agents and amendments are used to create good structure and maintain porosity. Pile heights can vary from 1.5 to 2.5 meters depending on the aeration system used. Good initial mixing of the organics is required to prevent air channeling and anaerobic areas in the pile. The aeration system is usually operated by a programmed timer or a temperature sensor which can adjust the airflow rates to produce the desired temperature profile. Timers tend to be a simple way to regulate the air flows, but they do not maintain optimum process temperatures. Temperature sensors are better for controlling the composting system; however this method requires greater airflow rates, larger blowers, higher costs and an overall more sophisticated control system.

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Figure 14 : Aerated Static Pile

In-Vessel Composting

In-vessel composting occurs inside an enclosed container or vessel and relies on various methods of aeration and mechanical turning to control the process. These mechanical systems are designed to minimize odours and process time by controlling air flow, temperature, and oxygen concentration. In-vessel composting systems can be divided into two major categories: plug flow and dynamic. A plug flow system operates on the first-in, first-out principle, whereas a dynamic system mixes the material mechanically throughout the process. Bin composting and silos are representative of plug flow systems, while rectangular agitated beds and rotating drums which are characteristic of dynamic systems.

Figure 15 : In-Vessel Composting

The windrow system is the simplest to implement and operate, but the high temperatures are associated with some nitrogen loss. The temperatures could be better controlled by increasing the turning frequency, requiring more manual labour. The covered pile system is the best form of non-mechanized process control, however using clay as a covering layer increases the steps

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to build the system. The forced aeration static pile system is suitable for dealing with large quantities of waste but had the disadvantage of requiring a power supply. Even though all of the systems produced good quality compost in three to four weeks, the windrow method is the most appropriate for small scale process due to its overall simplicity. The most appropriate composting system has to be selected based on its technological feasibility, economic costs, and social and environmental impacts.

Composting is site specific. The next table compares the main technological differences among the previously described composting processes.

Table 4 : Comparison of Composting ProcessesITEM WINDROW AERATED STATIC

PILE IN-VESSEL WITH FORCED AERATION

Capital costs Generally low Generally low Generally high systems, can become high in large systems

Operating costs Generally low High (in sludge systems) Generally low where bulking agents are used

Land requirements High High Low, can increase if windrow drying or curing is required

Control of air Limited unless forced aeration is used

Complete Complete

Operational control Turning frequency, amendment, or compost recycle addition

Airflow rate Airflow rate, agitation (dynamic), amendment, or compost recycle addition

Sensitivity to cold or wet weather

Sensitive unless in housing

Demonstrated in cold and wet climates

Demonstrated in cold wet climates

Control of odours Depends on feedstock, potential large area source

May be a large area source but can controlled

Potentially good

Potential operating problems

Susceptible to adverse weather

Control of air supply is critical, potential channelling or short circuiting of air supply

Potential for short circuiting of air supply (plug flow), system may be mechanically complex

Vermicomposting

Vermicomposting, also known as vermiculture, is a simple technology using the natural digestion process of earthworms to break down organic material. From the moment it hatches, a worm can consume daily its body weight in organic matter such as vegetables, fruit, leaves, grass, meat, fish, sludge, cardboard, and paper. The waste is continuously turned and mixed as the worms burrow through the medium. Worms multiply fast; under optimum conditions eight worms can produce 1,500 new worms within six months. Worm castings contain high concentrations of nitrates, potassium, calcium, phosphorous, and magnesium and can be applied instead of chemical fertilizers in some agricultural practices. Castings also contain many worm eggs which continue to enrich the soil when it is applied. The actual worms are also high in protein and are often sold as fish bait or used to supplement animal feed. Worms can be housed in any ventilated container with a lid providing drainage holes or a layer of gravel at the bottom to allow the removal of liquid created in the process. Even though vermiculture is a relatively basic operation, some problems can arise with the most common complaints being: process is relatively slow, difficult to remove the castings, presence of fruit flies in the warmer months, and need to maintain the temperature between 13 and 25°C to enhance worm activity. It was also reported that heavy metal accumulation can occur in earthworm tissue, and pathogens may survive in the worm castings since high process temperatures are not achieved to kill pathogenic microorganisms. Source separating the organic material from the waste stream before being fed to the worms can reduce the heavy metal contamination.

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Figure 16 : Vermicomposting

The Vermicomposting is also a suitable technology for Rwanda, especially at the household and community level in rural or urban centers, because it does not require sophisticated machinery, high capital investment, continuous process monitoring, or extensive administrative support. Source separating the organic matter from other household wastes should reduce heavy metal accumulations in the worms. Caution should also be exercised when using the worm castings because pathogens may have survived the decomposition process.

Operating and Control Parameters

In order to better understand the description of the operating and control parameters, a brief explanation of the composting process is included here. There are two stages to the biological activity associated with composting. The first stage is the active stage in which there is a high rate of biological activity taking place. The temperature of the compost mass will increase to 60 degrees Celsius. During this time the readily biodegradable material is decomposed to less readily degradable components. As this occurs the temperature of the mass drops because of a slowing of microbial activity. This second stage is known as curing or the maturation stage and ends when the material reaches the required degree of stability. Hence, an important consideration in the evaluation of a compost system is the fact that the compost process is finished only upon completion of the curing stage.

Time Requirements

The compost process is complete when the original organic material cannot be identified and the compost has a fresh earthy smell. At this point, the mass has been stabilized to a point where it can be stored without causing nuisances and can be used without inhibiting plant growth. The curing interval is particularly important because it must be long enough for the composting material to have reached the final level of stability. The length of time required to complete the composting process will depend upon the nature of the waste and the system employed. For example, yard debris, including grass clippings and leaves with the proper

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balance between the nutrients of carbon and nitrogen (C/N), composting can be accomplished in four to eight weeks. Leaves without the proper C/N ratio can take two to three years to compost. Municipal solid waste can take eight to 24 weeks. Animal manure and assorted food processing wastes (that have been appropriately bulked) can take six to eighteen weeks to produce compost.

Temperature Requirements

Unless there is an obvious problem no effort is required to ensure the adequate temperature is achieved. The pile reaches the highest temperature, between 55 to 60 degrees Celsius, when the degree of microbial activity is greatest. The temperature of the pile will rise quickly as this is the most active stage of microbial activity, which is referred to as the thermophilic stage. Eventually the microbial activity decreases and the temperature cools. This return to ambient temperature is referred to as the mesophyllic stage. Typically the highest temperature is achieved in the first 10 days of the composting process and then gradually returns to the initial temperature over a period of six to eight weeks depending upon the nature of the material. If the temperature of the pile is too high, microbial activity will be impaired and efforts may have to be taken to lower the temperature depending upon the type of system being used. The usual approach is to increase the rate and extent of aeration. If the temperature rises too slowly or there is no temperature rise then not enough microbial activity is taking place. The attainment and maintenance of thermophilic temperatures for a time period is required for weed and pathogen control. If the temperature rise is inadequate the reason may be an operational or other problem.

Moisture Requirements

Ideally the moisture content should be between 45 and 55 %. If the moisture content of the mass is 8 % or lower, microbial activity will cease. Too much moisture prevents air from being supplied to the microbes. For this reason it is necessary to add bulking agents such as wood chips, straw, or leaves to wastes that have a high moisture rate such as fresh manure.

Oxygen Requirements

Although composting can occur without oxygen (anaerobic systems), composting systems which use oxygen (aerobic systems) are considered more efficient, reliable and can tolerate sudden changes in environmental conditions. Aerobic systems are less likely to cause nuisance conditions such as objectionable odours. If the composting mass is producing foul odours, then this could be an indication that there is not enough oxygen present in the pile. A slow temperature rise during the active stage of the composting process or an unexpected drop in temperature in later stages is another indication that the pile needs better mixing to provide additional oxygen to the pile. Other signs include the slowing in the breakdown of the organic matter and the absence of expected physical changes in the composting mass. In practice the rate of aeration should be determined by experimenting with the waste to be composted. If aeration is achieved by turning then how often the turning occurs becomes the important consideration in trying to supply enough oxygen. With composting systems which used forced aeration the rate and volume of throughput air is the primary factor to be considered. While it is possible to accelerate composting by adding pure oxygen to the input air stream it is unlikely that the benefits would out-weigh the cost of such an approach.

Nutritional Requirements

The organisms which create the compost, like all living things, need moisture, air and a source of nutrients. The most important nutrients to supply the microbes in a compost mass are carbon and nitrogen. Other nutrients including cobalt, manganese, magnesium and copper should also be present but in smaller amounts. Calcium can also be important to ensure that

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the pile can resist changes in acidity (pH). Nitrogen is probably the only nutrient which needs to be added to ensure that a suitable carbon/nitrogen ratio is achieved. The nutrients must be present in a form that the microbes can use or digest. Some substances will be very resistant to breakdown by the composting process even under ideal conditions. These can include wood, straw and paper as well as feathers and shellfish. Experience has shown that, with the exception of carbon and nitrogen, most organic wastes contain nutrients in the amounts and ratios required for composting. The ideal carbon/nitrogen ratio is 25 to 30 parts carbon to one part nitrogen. The composting process becomes increasingly slower as the ratio rises beyond this range. The carbon/nitrogen ratios for a number of organic materials are shown in the next table

Table 5 : Carbon/Nitrogen Ratio of Compostable MaterialsCompostable material Carbon/Nitrogen RationChicken manure 10Cattle manure 20Manure with straw 25-30Green Plants 7Hay 15Leaves 45Straw 100Peat 30-50Wood shavings 100-150Sawdust 100-500Paper/cardboard 200-500Garden Waste 20-60Kitchen scarps 12-20Domestic waste 30-40Sewage sludge 11

Particle Size

In theory, the smaller the particle size, the more rapid is the rate of decomposition. However, below a minimum size this does not hold true as the air space provided by the particles supplies oxygen for the composting process. For material which is rigid, such as wood chips, the optimum size is from 5 to 7.5 centimetres. The maximum size for green plant material such as food wastes, fruit and lawn clippings should be no less than 5 centimetres and the maximum size can be as large as 15 centimetres.

Mixing Requirements

To ensure decomposition occurs uniformly throughout the composting mass, it is important to ensure proper mixing takes place. Mixing ensures that all compost material is exposed to conditions which will destroy pathogens. For aerobic composting, it renews the oxygen supply in the spaces between particles necessary for composting to occur. Mixing also helps reduce excess moisture from the composting mass.

Acidity (pH)

Usually the pH level drops to about 5 as soon as composting conditions have been established. This initial drop is soon followed by a gradual rise that continues until a level of approximately 8.5 is reached. It is unnecessary, therefore, to add lime to the process. The one possible exception may be in the composting of fruit waste in which case the initial drop may be slightly lower. Adding lime can, however, improve the physical condition of the composting mass by improving the porosity and texture of the pile.

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3.3.2 Composting Facility Siting Criteria

Minimum Acceptable Standards

Precautions to mitigate environmental and public health effects can be implemented in the design and siting phases of the composting project. The following criteria are typical for a Decentralized Community Composting Facility: Separation distances are necessary in order to minimize potential environmental conflicts

between non-compatible land uses, to minimize odour related problems and to ensure the integrity of groundwater systems.

To provide a basic level of protection from odour, dust and noise, a composting facility should not be located within a minimum buffer distance from designated residential areas or other sensitive land uses. The buffer protects the amenity of the area from accidental emissions which may occur due to equipment failure, accidents and abnormal weather conditions. The buffer distance is measured from whichever activity capable of emitting odour or other nuisance is nearest a sensitive land use.

Siting should also consider the need to protect sensitive water resources. Unless adequate protection of surface and ground waters can be demonstrated, a composting facility should not be sited near surface waters, on a flood plain or in a proclaimed potable water supply catchment. The site should be at least 100 meters from surface water.

Table 6 indicates the recommended separation distances. However, these may be modified, if deemed necessary by the environmental inspector, to make a project environmentally acceptable. Modifications will be based on the type of material to be composted, the composting site, operational procedures, etc.

Table 6 : Separation Distances for Composting FacilitiesNeighbouring Properties Separations Distance

Dwelling 400mCommercial building 300mIndustrial building 300mFarm 100m

Roadways: - Right of way of a local road and arterial or collector highways

50m

Watercourses: - Rivers/streams 150m- Drinking well 150m- Lakes, wetlands 300m

Buffer zones: - Minimal buffer strip between composting facility - Boundary and adjacent property 30m

The composting facility shall not be located in areas subject to flooding and where seasonal high groundwater table is less than 1 meter from the ground water table or where the minimal depth to bedrock is less than 1.5 meter.

Avoid impermeable or overly permeable soils. The composting facility shall not be located within a protected watershed or wetland as

defined by REMA. The composting facility shall be located on a surface with a slope of between 1% and 6%. Meet quality standards, such as waste sources low in toxic compounds and heavy metals,

and not extremely saline.

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Avoid densely populated neighbourhoods and areas where adjacent land users may find the operations inappropriate, such as hospitals, religious facilities, schools.

Locate in accordance with town plans and zoning regulations. Avoid locating on top of sites which have wastes beneath them, or where toxic waste has

been previously disposed. Plan sites to have buffer zones separating the facility from the surroundings, such as hills,

trees, fences. Locate downwind from residential areas to avoid possible odour complaints.

3.3.3 Composting Facility Operational and Performance Criterion

General Principles

The requirements of these Guidelines apply to all composting operations and facilities with the exception of backyard composting. An Approval must be obtained prior to the construction of a new composting facility or expansion of an existing facility and prior to any facility beginning operation. An Approval must still be obtained by presently operating composting facilities after a site evaluation by an environmental inspector.

In addition to REMA's approval, all buildings and structures related to the composting facility shall meet the conditions of all regulatory agencies responsible for adequacy of design, health, sanitary, safety and water quality requirements. Should composting operations cease, efforts must be made to ensure that no environmental damage will occur.

Composting facilities will need to comply with these criterion: The operation of the composting facility shall be properly maintained to the satisfaction

of the environmental inspector; The composting operation shall have adequate security to prevent illegal dumping and

vandalism; If the composting operation involves mixing, it shall be carried out in a location,

approved by the environmental inspector, allowing for the collection of leachate, and recycling it back into the compost pile;

Should the final composted product be considered inadequate for usage, it should be hauled to a designated disposal site.

Environmental Monitoring

The composting facility operator should ensure the environmental objectives are met by providing the best environmental safeguard measures appropriate to the specific site. These may be selected from the suggested best practice environmental measures, or better alternatives for the site may be developed or provided.

Air Quality

(a) Odour: Site management should have an effective odour control strategy in place to exercise control over, and to minimise odour from, all the odour generating sources on the site. Major potential odour sources and control measures for composting include the following.

(i) Odour from feedstock before it enters the composting process. Municipal waste should be incorporated into the composting process the day

it is delivered, as soon as possible after it is received. Water absorption into the feedstock, which restricts access of air and leads to

anaerobic conditions, should be prevented. Animal excreta and other potentially odorous wastes should be received and

maintained in a dry state to minimise anaerobic decomposition before use.

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(ii) The composting method adopted must be chosen and operated to minimise odour. Foul odours usually arise when part of a composting mass decomposes under

anaerobic conditions. Without careful design, there is a tendency for anaerobic areas to develop at some stage during the process. Odour control is generally achieved by providing sufficient fresh air to all parts of the mass to replenish the oxygen used in the process.

Prevent water logging.

(b) Other gas emissions: Large volumes of gas are generated during the composting process. Under aerobic conditions the principal gas generated is carbon dioxide. Under anaerobic conditions methane is generated. Each is formed naturally from the decomposition of biomass.

(c) Dust and bio-aerosols: The operation must be managed to avoid dust emission beyond the premises.

Suggested Measures Have an odour control strategy. Minimise storage of unprocessed feedstock. Minimise accumulation of contaminated run-off. Maintain aerobic conditions for outdoor processes. Implement appropriate handling techniques, particularly to control dust.

Water Quality

Water and land pollution must be avoided by appropriate siting, design, and management of the facility. Stormwater and leachate from composting operations may be contaminated by toxic materials, nutrients, micro-organisms, organics, salts and/or metals. These may pose a risk of adverse environmental impact on the receiving surface waters, groundwater or soil.

(a) Stormwater and leachate management: Surface waters must be protected frompollution caused by contaminated stormwater and leachate, preferably by: (i) keeping contaminated stormwater and leachate separate from clean stormwater (ii) minimising, containing and re-using contaminated stormwater and leachate so there is no discharge of contaminated wastewater from the premises and (iii) appropriately monitoring the clean stormwater stream before disposal.

(b) Groundwater protectionApplying the policy to composting, a facility operator:

Must not cause any serious or irreversible damage to the groundwater; Must protect the beneficial use of the groundwater of the area; and Must minimise the impact of facility activities on groundwater quality.

Composting activities may pose a risk to groundwater quality if leachate or contaminatedstormwater are able to permeate the soil and reach the underlying water table, polluting thegroundwater. Contamination, which may affect the beneficial uses of groundwater – such as drinking or stock watering – can occur at a distant location, during its distribution by the underground water system. It is necessary to assess this risk and/or provide measures to reduce or eliminate the risk.

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(c) Soil protection

The underlying soil may also become polluted by components of leachate percolating throughthe ground, resulting in a contaminated site. This should be avoided by using the same design considerations outlined for groundwater protection. In addition, good housekeeping practice should be observed to further protect the soil and sub-soil of the landat the operating site.

Suggested Measures Provide cut-off drains, bunding and hard standing to keep contaminated stormwater

and leachate separate from clean stormwater, and to minimise groundwater intrusion. Bund and roof the pre-storage and processing areas to prevent contamination and

reduce the volume of stormwater. Grade and drain the pre-storage an processing areas to a collection pit. Place vegetative filter strips of fully composted material around compost heaps to

absorb leachate run-off and to divert stormwater run-on. Set-up fresh compost heaps on an organic base, such as dry wood chips, or straw,

with a high water absorbency. Incorporate materials in the feedstock premix which have a high water demand. Add only the minimum amount of water needed by the compost process at any time. Provide adequate storage of contaminated leachate and stormwater. Minimise and re-use contaminated stormwater and leachate to prevent any

wastewater discharging from the premises.

3.3.4 Approval Process

An Approval will be issued for composting facilities whose premises and practices are consistent with the conditions and recommendations of these Guidelines. All composting projects are subject to inspection and review by REMA. The issuance of an Approval will be determined by a site inspection and the information given on a completed application form which is based on the following information:

Name and address of proponent.

Written description of composting methods, equipment employed and management of site.

Type and volume of waste to be composted, source of raw materials, bulking agents and leachate control methods.

Location of the proposed composting operation indicated on a 1 :12 500 scale map or equivalent sketch indicating separation distances to the following:- farms, private wells, industrial areas, residential areas, right of way of local roads,

right of way of arterial or collector highways, watercourses, commercial areas, property boundaries, watershed boundary.

- The slope of the land surrounding the proposed composting location.

The basic principles and technologies described earlier may be applied to municipal, commercial/industrial and agricultural composting operations. The characteristics of each waste type will dictate the best approach that should be taken for that material. There is no question that organic material, if properly processed can be composted. If composting is to be successful, however, siting and operating conditions must be closely followed.

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Annex 1: References and Useful Resources

REMA (2009): Rwanda State of Environment and Outlook Report, Rwanda Environment Management Authority, P.O. Box 7436 Kigali, Rwanda http://www.rema.gov.rw/soe/

CIDA, Environmental Handbook for Community Development Initiatives (2002), Second Edition of the Handbook on Environmental Assessment of Non-Governmental Organizations and Institutions Programs and Projects (1997) http://www.acdi-cida.gc.ca/acdi-cida/ACDI-CIDA.nsf/eng/JUD-47134825-NVT

USAID, Environmental Guidelines for Small-Scale Activities in Africa: Environmentally Sound Design for Planning and Implementing Development Activities, U.S. Agency for International Development, Office of Sustainable Development, Draft Version, January 2005, www.encapafrica.org.

General Auschutz, Justine 1996. Community-Based Solid Waste Management and Waste Supply Projects: Problems and Solutions Compared. Literature Survey. Urban Waste Expertise Programme, Community Participation in Waste Management, UWEP Working Document 2. May. http://www.waste.nl/redir/content/download/606/4651/file/WD02.pdf

Bernstein, J. (2004). Toolkit for Social Assessment and Public Participation in Municipal Solid Waste Management. Urban Environment Thematic Group, The World Bank, Washington, D.C. http://www.worldbank.org/urban/uswm/socialassesstoolkit.pdf

Coad, A. (1998). Solid Waste Management Directory of English-Language Publications and Organisations for Low- and Middle-Income Countries. SKAT. Switzerland. Available for purchase from http://www.skat.ch/publications/prarticle.2005-09-29.7288084326/skatpublication.2005-11-10.3524725150

Cointreau-Levine, S., and A. Coad (2000). Private Sector Participation in Municipal Solid Waste Management: Guidance Pack (5 volumes). SKAT, St. Gallen, Switzerland. http://www.worldbank.org/urban/solid_wm/erm/CWG%20folder/Guidance%20Pack%20TOC.pdf

Cointreau-Levine, Sandra (1994). Private Sector Participation in Municipal Solid Waste Services in Developing Countries: Volume 1. The Formal Sector. UNDP/UNCHS/World Bank Urban Management Programme. http://www-wds.worldbank.org/servlet/WDS_IBank_Servlet?pcont=details&eid=000009265_3970128111924

IETC/UNEP (1996). International Source Book on Environmentally Sound Technologies for Municipal solid Waste Management. International Environmental Technology Centre/United Nations Environmental Program. http://www.unep.or.jp/ietc/ESTdir/pub/MSW Johannessen, Lars Mikkel and G. Boyer (1999a). Observations of Solid Waste Landfills in Developing countries: Africa, Asia, and Latin America. World Bank, Washington, D.C. http://www.worldbank.org/urban/solid_wm/erm/CWG%20folder/uwp3.pdf Johannessen, L. M. (1999b). Guidance Note on Recuperation of Landfill Gas from Municipal Solid Waste Landfills. Urban and Local Government Working Paper Series No. 4, The World Bank, Washington, D.C. http://info.worldbank.org/etools/docs/library/128809/Johannessen%201999.pdf

Johannessen, L. M. (1999c). Guidance note on Leachate Management for Municipal Solid Waste Landfills. Urban and Local Government working Paper Series No. 5, The World Bank, Washington, D.C. http://www.worldbank.org/urban/solid_wm/erm/CWG%20folder/uwp5.pdf

Johannessen, L. M. (in press). Guidance note on Landfill Siting. Urban and Local Government Working Paper Series, The World Bank, Washington, D.C.

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Johannessen, L. M., M. Dijkman, C. Bartone, D. Hanrahan, G. Boyer and C. Chandra (2000). Health Care Waste Management Guidance Note. HNP Discussion Paper, Human Development Network, World Bank, Washington, D. C. http://siteresources.worldbank.org/HEALTHNUTRITIONANDPOPULATION/Resources/281627-1095698140167/Johannssen-HealthCare-whole.pdf

Privatization of Municipal Services in East Africa: A Governance Approach to Human Settlements Management. Published by United Nations Centre for Human Settlements (Habitat), with support from the Ford Foundation, Office for Eastern Africa. Nairobi, Kenya. http://www.chs.ubc.ca/archives/?q=node/933

Rushbrook, P.E., and M.P. Pugh (1999). Solid Waste Landfills in Middle and Lower-income Countries: A Technical Guide to Planning, Design and Operation. World Bank/SDC/WHO/SKAT. http://www-wds.worldbank.org/servlet/WDSContentServer/WDSP/IB/2002/12/06/000094946_02112104104987/Rendered/PDF/multi0page.pdf Schübeler, Peter, in collaboration with Karl Wehrle and Jürg Christen of SKAT (1996). Conceptual Framework for MSWM in Low-Income Countries. UNDP/UNCHS (Habitat)/World Bank/SDC Collaborative Programme on MSWM. http://www.worldbank.org/urban/solid_wm/erm/CWG%20folder/conceptualframework.pdf

Thurgood, M., ed. (1999). Decision-maker's Guide to Solid Waste Landfills: Summary. Transport, Water and Urban Development Department, The World Bank, Washington, D.C. http://www-wds.worldbank.org/servlet/WDSContentServer/WDSP/IB/2000/02/23/000178830_98111703545138/Rendered/ PDF/multi_page.pdf

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