UNIT-2

Waste:
Definition: Waste refers to any substance or object that is discarded, abandoned, or considered to be no longer
useful. It can include materials generated from human activities, industrial processes, or natural sources that are no
longer needed and are destined for disposal.

Waste Characterization:
Definition: Waste characterization is the process of identifying and quantifying the physical, chemical, and biological
properties of waste materials. This information is crucial for determining appropriate waste management and disposal
strategies.

Key Components:
1.Physical Properties: Include characteristics such as size, volume, density, and moisture content.
2.Chemical Properties: Include the composition of the waste in terms of hazardous and non-hazardous components.
3.Biological Properties: Include the presence of microorganisms and potential for biological activity.

Purpose:
•To ensure safe handling, transportation, and disposal of waste.
•To identify potential hazards and environmental impacts.
•To determine appropriate treatment and disposal methods.
Types of Waste:
1.Municipal Solid Waste (MSW):
1. Description: Household waste generated from daily activities.
2. Examples: Food waste, packaging, paper, plastics, textiles, and non-hazardous household items.

2.Industrial Waste:
1. Description: Generated by industrial processes and manufacturing.
2. Examples: Manufacturing by-products, process residues, and wastewater.

3.Hazardous Waste:
1. Description: Poses a threat to human health or the environment due to its toxicity, reactivity, flammability, or other
characteristics.
2. Examples: Chemicals, batteries, electronic waste, and certain medical waste.

4.Construction and Demolition (C&D) Waste:

1. Description: Generated during construction, renovation, or demolition activities.
2. Examples: Concrete, wood, metal, bricks, and other construction materials.

5.Biomedical or Healthcare Waste:

1. Description: Waste generated from healthcare facilities.
2. Examples: Used syringes, medical equipment, and biological waste.

6.Agricultural Waste:
1. Description: Waste produced from agricultural activities.
2. Examples: Crop residues, animal manure, and agricultural chemicals.

7.Radioactive Waste:
1. Description: Contains radioactive materials.
Sources of Waste Generation:
1.Residential Sources:
1. Description: Waste generated by households in the course of daily living.
2. Examples: Kitchen waste, packaging materials, old furniture, and appliances.
2.Commercial Sources:
1. Description: Waste generated by businesses and commercial establishments.
2. Examples: Office paper, packaging, obsolete equipment, and retail waste.
3.Industrial Sources:
1. Description: Waste produced by industrial processes.
2. Examples: Manufacturing by-products, process residues, and industrial packaging.
4.Construction and Demolition Sites:
1. Description: Waste generated during construction, renovation, or demolition activities.
2. Examples: Concrete debris, wood, metal, and other construction materials.
5.Institutional Sources:
1. Description: Waste generated by institutions such as schools, hospitals, and government offices.
2. Examples: Office waste, educational materials, and healthcare waste.
6.Agricultural Sources:
1. Description: Waste produced in farming and agricultural practices.
2. Examples: Crop residues, animal manure, and agricultural packaging.
7.Healthcare Facilities:
1. Description: Waste generated by healthcare and medical facilities.
2. Examples: Used medical supplies, contaminated materials, and pharmaceutical waste.
8.Electronic and Electrical Equipment Sources:
1. Description: Waste from discarded electronic devices.
2. Examples: Old computers, mobile phones, and electronic appliances.
9.Mining and Extractive Industries:
1. Description: Waste generated during mining and extraction processes.
2. Examples: Tailings, mine waste, and processing residues.
QUANTITY OF WASTE

4 December 2023 5
Waste disposal on land involves various practices and poses environmental and health risks if not managed properly. Here's an
overview of some common land-based waste disposal practices and associated concerns:
1.Wastewater Discharge (Industrial/TPPs):
1. Concerns: Industrial and thermal power plant (TPP) wastewater may contain pollutants such as heavy metals, chemicals,
and nutrients. Discharging untreated or inadequately treated wastewater can contaminate soil and water sources, impacting
ecosystems and human health.
2.Spillage (Petroleum Godowns):
1. Concerns: Spillage from petroleum godowns can result in soil and groundwater contamination. Hydrocarbons and other toxic
substances in spilled oil can have adverse effects on the environment, including damage to plant and animal life.
3.Illegal Dumping:
1. Concerns: Unauthorized disposal of various types of waste, including household, industrial, and hazardous waste, can lead
to pollution and degradation of land and water resources. Illegal dumping poses serious environmental and health risks.
4.Industrial Accidents:
1. Concerns: Accidents in industrial facilities can result in the release of hazardous materials into the environment. Spills or
leaks can contaminate soil and water, posing immediate dangers to nearby communities and ecosystems.
5.Long-term Storage over Land:
1. Concerns: Prolonged storage of waste on land can lead to leachate formation, where contaminants from the waste may
seep into the soil and groundwater. This can result in long-term environmental damage and pose risks to human health.
6.Disposal of Ash, Slag, etc.:
1. Concerns: Improper disposal of industrial by-products like ash and slag can contribute to land degradation. Some by-
products may contain heavy metals and other pollutants, posing risks to ecosystems and groundwater quality.
7.Mine-Tailings and Heaps:
1. Concerns: Improper disposal of mine tailings and heaps can lead to soil erosion, surface water contamination, and habitat
destruction. Mining activities often generate waste materials with high concentrations of metals and chemicals.
8.Other Industrial Operations:
1. Concerns: Various industrial operations may generate solid or liquid waste that, if not managed properly, can contribute to
pollution. The nature of the waste depends on the specific industry but may include chemicals, heavy metals, and other
contaminants.
Contaminants in soil can have various impacts depending on their nature. Here's a breakdown of different types of soil contaminants
and their associated concerns:

1.Acidic Contaminants:
1. Heaving: Acidic contaminants can contribute to soil heaving, causing the soil to expand and contract, leading to structural
instability.
2. M.O. (Microorganisms): Some microorganisms are sensitive to changes in soil pH, and acidity can affect microbial activity.
3. Permeability: Acidification can alter soil permeability, impacting water movement and nutrient availability.
2.Alkaline Contaminants:
1. Heaving: Alkaline contaminants may lead to soil heaving, affecting soil structure and stability.
2. M.O. (Microorganisms): Microbial activity in alkaline soils may be inhibited, affecting nutrient cycling and organic matter
decomposition.
3. Permeability: Alkalinity can influence soil permeability, affecting water retention and drainage.
3.Inorganic Contaminants:
1. Toxicity: Heavy metals and other inorganic contaminants can be toxic to plants, animals, and humans.
2. M.O. (Microorganisms): Inorganic contaminants can impact microbial communities, affecting nutrient cycling and soil health.
3. Fertility: Some inorganic contaminants may negatively impact soil fertility by interfering with nutrient availability.
4.Organic Contaminants:
1. Permeability: Organic contaminants can affect soil permeability, altering water movement and drainage.
2. Toxicity: Certain organic compounds can be toxic to plants, animals, and microorganisms.
5.Non-Aqueous Phase Liquids (NAPLs):
1. Concerns: NAPLs, including petroleum hydrocarbons, can persist in the soil, posing long-term contamination risks.
2. Effects on Permeability: NAPLs can reduce soil permeability, affecting water movement and nutrient transport.
6.Others (Emerging Contaminants/POPs etc.):
1. Emerging Contaminants: These may include pharmaceuticals, personal care products, and other emerging pollutants with
potential ecological and human health impacts.
2. Persistent Organic Pollutants (POPs): These long-lived organic compounds can accumulate in soil and organisms,
causing environmental and health concerns.
The presence of trace organics in soil can indeed lead to a range of detrimental effects on soil properties and
functions. Here's a breakdown of how trace organics can impact soil:

1.Decrease Microbial Population:

1. Mechanism: Some trace organics, particularly certain pesticides and industrial chemicals, can be toxic to soil
microorganisms.
2. Consequence: Reduction in microbial populations can hinder essential soil processes such as organic matter
decomposition, nutrient cycling, and the formation of beneficial soil microbial communities.
2.Reduced Aggregation of Soil Particles:
1. Mechanism: Trace organics can interfere with soil structure and stability, leading to the breakdown of soil
aggregates.
2. Consequence: Loss of soil structure can result in increased erosion, reduced water infiltration, and
compromised soil fertility.
3.Reduced Porosity, Water Holding Capacity:
1. Mechanism: Trace organics may alter soil structure, leading to reduced pore space.
2. Consequence: Decreased porosity and water-holding capacity can limit the availability of water to plants,
affecting plant growth and overall ecosystem health.
4.Reduced Permeability and Hydraulic Conductivity:
1. Mechanism: Trace organics can clog soil pores and interfere with water movement.
2. Consequence: Reduced permeability and hydraulic conductivity can contribute to waterlogging, surface runoff,
and increased susceptibility to soil erosion.
5.Increased Interlayer Swelling:
1. Mechanism: Certain trace organics may affect the mineral structure of soil, leading to increased interlayer
swelling in clay minerals.
2. Consequence: Swelling can alter soil properties and complicate water movement, affecting plant root growth
6.Reduced Void Ratio:
1. Mechanism: Trace organics may contribute to soil compaction, reducing the void ratio.
2. Consequence: Compaction can restrict root growth, limit water infiltration, and impede the movement of gases
in the soil.
7.Induced Toxicity:
1. Mechanism: Some trace organics are toxic to plants and may accumulate in plant tissues.
2. Consequence: Toxicity can lead to reduced plant growth, impaired reproductive success, and overall
ecosystem disturbance.
8.Groundwater Contamination:
1. Mechanism: Leaching of trace organics through the soil profile can contaminate groundwater.
2. Consequence: Groundwater contamination poses risks to human health and the environment, as
contaminated groundwater may be used for drinking water or affect aquatic ecosystems.
SITING CRITERIA:

Adequate land area and volume to provide sanitary landfill capacity to meet projected needs for at least 10 years For siting purposes, land area
requirements shall be estimated based on the landfill cell area required (typically for a depth of 10-25 meters, About 2-4 hectares for the
receiving area, 2-4 hectares for the leachate treatment and/or evaporation ponds, and additional 10% Land for a landscaped buffer zone.

1. None of the areas within the landfill boundaries should be part of the 10-year groundwater recharge area for existing or pending water
supply development.
2. No private or public drinking, irrigation, or livestock water supply wells within 500 meters downgradient of the landfill.
3. No environmentally significant wetlands of important biodiversity or reproductive value are present within the potential area of the landfill
cell development.
4. No known environmentally rare or endangered species breeding areas or protected living areas are present within the site boundaries (2 kms
away).
5. No significant protected forests are within 500 meters of the landfill cell development area.
6. No major lines of electrical transmission or other infrastructure (i.e., gas, sewer, water lines) are crossing the landfill (500 meters away).
7. No residential development within 250 meters from the perimeter of the proposed landfill cell development.
8. No visibility of the proposed landfill cell development area from residential neighborhoods within 1 km. If residents live within 1 km of the
site, landscaping and protective berms would need to be incorporated into the design.
9. No perennial stream within 300 meters downgradient of the proposed landfill cell development.
10. No fault lines or significantly fractured geologic structure within 500 meters of the perimeter of the proposed landfill cell development.
11. No siting within 3 km of a turbojet airport and 1.6 km of a piston-type airport. For sites located more than 3 km and less than 8 km from the
nearest turbojet airport no consideration is to be given unless the aviation authority has provided written permission.
12. No siting within a floodplain subject to 10-year floods.
• Avoid siting within 1 km of socio-politically sensitive sites where public acceptance might be unlikely.
• Arrangements (monitoring wells) for regular monitoring of groundwater level and its quality.
• Collection/flaring of gases generated.
• Proper treatment of leachate.
• Proper fencing to avoid entry of stray dogs, cattle etc.
• Strictly restricted unauthorized entry.
• Monitoring of top cover to check for subsidence and leakage.
• Natural depression
• Barren or imfertile land
• Impervious underlying stratum
• Sufficient availability of soil/clay
• Should not be placed on a seismic zone/fault
• Should not lie enroute to natural drainage
• Site accessible within 30 minutes travel time
• Preferably an existing network of road/rail
• Groundwater table atleast 1.5 metres below the base of landfill
Leachate:
Definition: Leachate is a liquid that has percolated through a substance, such as soil or waste, and has extracted
dissolved or suspended materials from it.

Leachate Generation in Landfills:

1.Rainfall and Infiltration:
1. Rainwater infiltrates through the waste layers in a landfill.
2. As it percolates through the waste, it picks up dissolved and suspended materials.
2.Decomposition of Organic Waste:
1. Organic waste in landfills undergoes anaerobic decomposition.
2. Decomposition by microorganisms releases liquids (leachate) as byproducts.
3.Chemical Reactions:
1. Chemical reactions between waste components and water contribute to leachate generation.
2. These reactions may involve both organic and inorganic waste materials.

Concerns:
1.Environmental Contamination:
1. Leachate can contain various contaminants, including heavy metals, organic compounds, and pathogens.
2. If not properly managed, leachate can contaminate soil, groundwater, and surface water.
2.Landfill Stability:
1. Accumulation of leachate can affect the stability and structural integrity of landfill liners and base systems.
3.Odor and Aesthetics:
1. Leachate can produce unpleasant odors, impacting the surrounding environment and community aesthetics.
Leachate Management:
1.Collection Systems:
1. Landfills are equipped with leachate collection systems, including pipes and drainage layers.
2. Collected leachate is directed to treatment facilities or properly managed.
2.Treatment:
1. Leachate treatment involves processes such as biological treatment, chemical precipitation, and activated
carbon adsorption.
2. The treated leachate is then discharged according to regulatory standards.
3.Prevention:
1. Proper landfill design, liner systems, and waste management practices aim to minimize leachate generation.
Gas Generation:
Definition: Gas generation in the context of waste management refers to the production of gases, often in landfills, as
a result of waste decomposition.

Gas Generation in Landfills:

1.Anaerobic Decomposition:
1. In the absence of oxygen (anaerobic conditions), organic waste undergoes decomposition.
2. Methane (CH₄) is a significant gas produced during anaerobic decomposition.
2.Microbial Activity:
1. Microorganisms, particularly methanogenic bacteria, play a crucial role in generating methane.
2. They break down organic matter in the waste, producing methane as a metabolic byproduct.
3.Other Gases:
1. Besides methane, landfills can produce carbon dioxide (CO₂), volatile organic compounds (VOCs), and trace
amounts of other gases.

Concerns:
1.Greenhouse Gas Emissions:
1. Methane is a potent greenhouse gas, contributing to global warming.
2. Effective gas management is crucial to mitigate environmental impacts.
2.Odor Issues:
1. Landfill gases can produce unpleasant odors, affecting the surrounding environment and nearby communities.
3.Safety Concerns:
1. Methane is flammable, posing safety risks if not properly managed.
2. Landfills typically incorporate gas collection and control systems to address safety concerns.
Gas Management:
1.Collection Systems:
1. Landfills implement gas collection systems, including vertical and horizontal wells.
2. Collected gas is often used for energy recovery or flared to reduce environmental impact.
2.Flaring:
1. Flaring involves burning off collected landfill gas to convert methane into less harmful carbon dioxide.
2. Flaring is a common practice to mitigate greenhouse gas emissions.
3.Energy Recovery:
1. Collected methane can be used as a renewable energy source for electricity generation or other industrial
processes.
4.Monitoring:
1. Regular monitoring of gas composition, flow rates, and migration helps assess landfill gas management
effectiveness.
Proper gas management in landfills is essential to minimize environmental and safety risks, harness energy potential,
and comply with regulations. It requires a combination of engineering controls, monitoring, and utilization strategies.
Waste containment:
Waste containment refers to the methods and systems used to manage and control the disposal of various types of
waste to prevent contamination of the environment. When it comes to contaminated soil, treatment methods are
employed to remediate or mitigate the contaminants present.

Waste Containment for Contaminated Soil:

1.Containment Systems:
1. Landfills: Contaminated soil may be disposed of in specially designed landfills with liners and barriers to
prevent the leaching of contaminants into the surrounding environment.
2. Capping: Once soil is deposited, it's often capped with impermeable materials to prevent rainwater infiltration
and reduce the risk of contaminants spreading.

2.Engineering Controls:
1. Barriers and Liners: Utilizing engineered barriers like clay liners, geotextiles, or synthetic liners to isolate
contaminated soil from the surrounding environment.
2. Leachate Collection Systems: Installing systems to collect and treat leachate generated by the contaminated
soil to prevent it from spreading.

3.Monitoring:
1. Regular monitoring of the containment site is crucial to detect any potential leaks or breaches in the
containment system. This includes groundwater monitoring, gas monitoring, and surface water monitoring.

4.Regulatory Compliance:
1. Adhering to strict regulations and guidelines set by environmental agencies to ensure proper containment and
management of contaminated soil.
Treatment of Contaminated Soil:
The treatment of contaminated soil involves various methods, and different contaminants may require specific
approaches. Here's an overview of treatment methods categorized into extraction, immobilization, detoxification, and
physical, chemical, electrical, thermal, and biological methods:

Extraction Methods:
1.Soil Washing:
1. Description: Involves the use of water or other solvents to remove contaminants from the soil.
2. Applicability: Effective for soil contaminated with heavy metals, certain organic pollutants, and water-soluble
contaminants.
2.Solvent Extraction:
1. Description: Uses organic solvents to dissolve and extract contaminants from the soil.
2. Applicability: Suitable for organic contaminants such as petroleum hydrocarbons.

Immobilization Methods:
3.Solidification/Stabilization:
3. Description: Involves adding materials to the contaminated soil to reduce the mobility of contaminants and
prevent their migration.
4. Applicability: Useful for heavy metals and certain organic contaminants.
4.Chemical Fixation:
3. Description: Chemical additives are used to bind contaminants, reducing their mobility and bioavailability.
4. Applicability: Commonly used for metals like lead and cadmium.
Detoxification Methods:
5.Chemical Oxidation/Reduction:
5. Description: Chemical reactions are employed to transform contaminants into less harmful forms.
6. Applicability: Useful for treating organic contaminants, such as chlorinated solvents.
6.Bioremediation:
5. Description: Utilizes microorganisms to degrade or transform contaminants into non-toxic substances.
6. Applicability: Effective for a wide range of organic contaminants, including petroleum hydrocarbons.

Physical Methods:
7.Thermal Desorption:
7. Description: Involves heating the contaminated soil to vaporize and separate volatile contaminants.
8. Applicability: Suitable for organic contaminants with low boiling points.
8.Soil Vapor Extraction (SVE):
7. Description: Air or steam is injected into the soil to vaporize and extract volatile contaminants.
8. Applicability: Effective for volatile organic compounds (VOCs).

Chemical Methods:
9.Chemical Dechlorination:
9. Description: Specific chemicals are used to break down chlorinated compounds.
10.Applicability: Useful for treating soils contaminated with chlorinated solvents.
10.Fenton's Reagent Treatment:
9. Description: Hydrogen peroxide and iron catalysts are used to create reactive oxygen species that degrade
contaminants.
10.Applicability: Effective for treating various organic contaminants.
Electrical Methods:
11.Electrokinetic Remediation:
11.Description: Applies a direct electric current to the soil to mobilize and transport contaminants.
12.Applicability: Useful for heavy metals and certain organic contaminants.

Thermal Methods:
12.Incineration:
12.Description: Involves the combustion of contaminated soil at high temperatures to destroy organic
contaminants.
13.Applicability: Effective for a wide range of organic pollutants.
UNIT-3,4
Landfills
Landfills are low-lying areas that are used for the disposal of waste materials. Landfills are one of the oldest method of
waste disposal. In this process, the waste is dumped in the low-lying areas, lying outer to the city. Landfills can be
used for the disposal of household waste, construction waste, etc. A layer of soil is added after every layer of the
garbage. Once the process is done the area is declared unfit for residential purposes.

Classification Types of waste

I Hazardous waste
II Designated waste (nonhazardous waste)
III Municipal solid waste (MSW)
Construction of the landfill
Landfills work by going through a thorough process of evaluation first in order to determine where to put them and its
lifetime operation. The criteria are as follows;
1. Area of land
The section of land for setting up the landfill needs to be large as not only is the actual landfill supposed to be sizable
to pack enough waste, but also requires a lot of space for supporting structures that will be discussed further
on. Environmental impact study also has to be done on the land before construction begins.

2. Composition of the bottom of the pit

The bottom of the pit needs to be as watertight as possible. This means that the bottom of the pit should be compacted
tightly or the bedrock should not have cracks in it to prevent water from the pit leaking into ground water.

3. Surface flow of water

The flow of water from rain should also be studied in a bid to develop strategies to prevent runoff water from the landfill
from making its way to rivers as well as the ground table. This means, landfills cannot be constructed near rivers and
lakes and they require drainage systems to manage their surface water run-off.

4. Environmental impact assessment

This is to evaluate the damage that the project will have on the surrounding region as well as drawing up plans for
contingencies that will help solve problems that the landfill might cause. The systems set up here are supposed to
ensure the environment does not suffer too greatly while cushioning against any forms of accidents.

5. Historical and archaeological value of the site

Historical and archaeological valuation of the site has to be done to ensure the landfill site does not disturb land that is
significant in any way either historically for the local people or on the basis of archaeological importance that would be
How Landfill Works?
Once these requirements are established, the landfill creation process can begins and this shows exactly how the landfill works.
Landfills may differ in operations, structure and how they are designed, but the following are the typical structures involved.

1. Bottom Liner system

The Bottom Liner System is the section ensuring that the trash and leachate does not drain into the ground water or sip out of the
landfill and make its way to other water sources or pollute the soil. The liner is usually a durable and puncture resistant m aterial such
as polyvinylchloride about a tenth of an inch (approximately 3 millimetres) thick.

2. The Cells
This is where the actual trash gets placed. As space is a precious commodity for landfills, there is a need to be very careful with how
it is packed. Cells are created to allow for the allocation of specific space resources while guaranteeing optimal usage of the given
land for the landfill. The packing process is especially rigorous, requiring that each cell be filled then compacted using heavy
machinery to ensure maximum use of space. The resulting trash is usually packed till it becomes airtight.
Examples of cell dimensions have them placed at 15 by 15 by 4 meters. At the top of each cell, they are packed with about 6 inches
of compacted soil to ensure the cell remains airtight, preventing insect and other pest penetration into the landfill.

3. Storm Water Drainage System

This is the system maintaining the dryness of the landfill by preventing water from seeping into the system. It directs surface runoff
away from the landfill as well as ensuring water does not find way into rivers untreated.

4. Leachate Collection System

This system collects leachate that eventually seeps from the landfill. While trash put into the landfill is usually checked for liquids and
rejected if it’s too wet, the system still generates enough liquid referred to as leachate. This liquid contains large concentrations of
hazardous materials that have dissolved in it from the landfill trash over time.
It is therefore very dangerous to have it pool anywhere unmanaged or drain off into water sources. As such, the system collects the
leachate and drains it out of the landfill into a collection region where it is processed just like sewage and released safely back into
the natural water ways.
5. Methane Collection System
Due to the airtight nature of the packing process, only anaerobic bacteria can survive in the landfill. These are the
bacteria that do not need oxygen to survive. The bacteria break down the materials found within the landfill and
produce mostly two by-products, methane and carbon dioxide.
Methane is highly flammable; therefore, letting it collect within the landfill is a dangerous option given that it might be
densely packed and eventually becomes explosive. For this reason, the methane collection systems either collects the
gas and use and/or sell it as a fuel source or burn it on site to reduce its concentration inside the landfill.

6. Covering or Cap
The covering cap is the last bit of material placed daily on the landfill to cover the cells. It is usually a polythene
material covered in a thick layer of soil that later has trees and shrubs grown on it once the landfill is completely filled
to prevent erosion. The covering is done to prevent exposure of the waste to the air, pests, and to aid on the
management of bad smell.
Effects of Landfill on the Environment
Landfills can have very adverse effects on the environment, especially when improperly constructed. The major concerns include:
1. Leaching
Leachate is the water contained in the trash that usually seeps out over time. While management during construction ensures the
trash ending up in landfills is relatively dry, some liquid is inherent within the trash and thus drains out over time. This leachate has in
it dissolved organic and non-organic material and minerals. It is also usually acidic. This can cause horrendous changes in the pH
levels of the soil around the landfill as well as change its chemical composition.

2. Methane as a greenhouse gas

Methane gas, as previously discussed, is extremely volatile and could easily cause problems. However, its biggest contribution to
the environmental problem is that, it is a greenhouse gas. In this view, methane gas could contribute to the global warming. The
situation is even made worse by the possible human errors that could contribute to problems such as accidental release of the gas
due to negligence.

3. Other gases similarly cause air pollution and health problems to humans
Some other gases also tend to be produced in the landfills especially when ammonia and bleach mix. These gases can cause health
problems and reduce the quality of life because of the bad smell. Besides, it can be particularly dangerous because of the tendency
of converting landfills into recreational parks at the end of their lifecycle.

4. Potential fire hazard

Another huge concern is the potential fire hazard that landfills pose. Poor construction of landfills could leave enough room in the
structure for air to make its way in. The produced methane gas could then easily mix with the air and ignite to start a fire. The trash
within the landfill could then burn, heating to very high temperature as it burns due to its construction, the same way an oven burns,
with all the compacted material above and below it. Such an occurrence could make the fires very hard to put out. Furthermore, the
fire could cause the leachate to spread when attempts are made to put out the fire.
5. Soil erosion and dust
During the construction of landfills, a lot of soil is disturbed that leads to increased dust in the air. Also, the dust could rise after the
completion of the project if shrubs and plants are not planted appropriately on top of the cap. Moreover, soil erosion could occur
Landfill Operation:
1) Design and construction
The design and construction process involves site infrastructure i.e., the position of the buildings, roads and facilities that are necessary to the
efficient running of the site and site engineering i.e. the basic engineering works needed to shape the site for the reception of wastes and to meet
the technical requirements of the working plan.

(i) Site infrastructure:

• The size, type and number of buildings required at a landfill depend on factors such as the level of waste input, the expected life of the site
and environmental factors.
• Depending on the size and complexity of the landfill, buildings range from single portable cabins to big complexes.
• All landfill sites need to control and keep records of vehicles entering and leaving the site and have a weighbridge to record waste input data
which can be analysed by a site control office.
• Note that at small sites, the site control office can be accommodated at the site itself.

(ii) Earthworks:
• Various features of landfill operations may require substantial earthworks, and therefore, the working plan must include earthworks to be
carried out before wastes can be deposited.
• Details about earthworks gain significance, if artificial liners are to be installed, which involves grading the base and sides of the site and the
formation of embankments.
• Material may also have to be placed in stockpiles for later use at the site.
• The cell method of operation requires the construction of cell walls.
• At some sites, it may be necessary to construct earth banks around the site perimeter to screen the landfill operations from the public.
• Trees or shrubs may then be planted on the banks to enhance the screening effect.
• The construction of roads leading to disposal sites also involves earthworks.
(iii) Lining landfill sites:
• Where the use of a liner is envisaged, the suitability of a site for lining should be evaluated at the site investigation stage. However, they
should not be installed, until the site has been properly prepared.
• The area to be lined should be free of objects likely to cause physical damage to the liner such as vegetation and hard rocks.
• If synthetic liner materials are used, a binding layer of suitable finegrained material should be laid to support the liner.
• However, if the supporting layer consists of low permeable material (e.g., clay), the synthetic liner must be placed on top of this layer.
• A layer of similar fine-grained material with the thickness of 25 – 30 cm should also be laid above the liner to protect it from subsequent
mechanical and environmental damage.
• During the early phase of operation, particular care should be taken to ensure that the traffic does not damage the liner.
• Monitoring the quality of groundwater close to the site is necessary to get the feedback on the performance of a liner.

(iv) Leachate and landfill gas management:

• The basic elements of the leachate collection system (i.e. drain pipes, drainage layers, collection pipes, sumps etc.) must be installed
immediately above the liner, before any waste is deposited.
• Particular care must also be taken to prevent the drain and collection pipes from settling.
• During landfill operations, waste cells are covered with soil to avoid additional contact between waste and the environment.
• The soil layers have to be sufficiently permeable to allow downward leachate transport.
• Landfill gas is not extracted before completion which includes construction of final cover of the waste body.
• Extraction wells (diameter 0.3 to 1.0 m) may be constructed during or after operation.

(v) Landfill capping:

• Capping is required to control and minimise leachate generation (by minimising water ingress into the landfill) and facilitate landfill gas control
or collection (by installing a low permeability cap over the whole site).
• A cap may consist of natural (e.g. clay) or synthetic (e.g., poly-ethylene) material with thickness of at least 1 m.
• An uneven settlement of the waste may be a major cause of cap failure.
• Designs for capping should therefore include consideration of leachate and landfill gas collection wells or vents.
• For the cap to remain effective, it must be protected from agricultural machinery, drying and cracking, plant root penetration, burrowing
animals and erosion.
2) Operation
To secure public acceptability, landfill operations require careful planning and determination of the extent of environmental effects. The basic
factor influencing the planning of site operations is the nature and quantity of incoming wastes.
The various aspects of this include the following:

(i) Methods of filling:

1. Excavated cell/trench method
2. Area method
3. Cell method
4. Canyon/Depression Method

(ii) Refuse placement:

• The working space should be sufficiently extensive to permit vehicles to move and unload quickly and safely without impeding refuse
spreading and allow easy operation of the site equipment.
• Depositing waste in thin layers and using a compactor enables a high waste density to be achieved.
• Each progressive layer should not be more than 30 cm thick.
• The number of passes by a machine over the waste determines the level of compaction.

(iii) Covering of waste:

• At the end of each working day, all exposed surfaces including the flanks and working space should be covered with a suitable inert material to
a depth of at least 15 cm.
• This daily cover is considered essential, as it minimises windblown litter and helps reduce odours.
• Cover material may be obtained from on-site excavations or inert waste materials coming to the site.
• Pulverised fuel ash or sewage sludge can also be used for this purpose.
(iv) Site equipment and workforce orientation:
• The equipment most commonly used on landfill sites includes steel wheeled compactors, tracked dozers, loaders, earthmovers and hydraulic
excavators.
• Scrapers are used for excavating and moving cover materials.
• In addition to appropriate equipment, proper training must be ensured for the workforce.
• They should be competent, and adequately supervised; training should include site safety and first aid.
• Since a landfill site may pose dangers to both site operators and users, it is necessary to lay down emergency plans and test them from time to
time
3) Monitoring
Landfill represents a complex process of transforming polluting wastes into environmentally acceptable deposits. Because of the complexity of
these processes and their potential environmental effects, it is imperative to monitor and confirm that the landfill works, as expected. A
monitoring scheme, for example, is required for collecting detailed information on the development of leachate and landfill gas within and
beyond a landfill. The scheme should be site specific, drawn at the site investigation stage and implemented.
Monitoring is generally done for the following:

(i) Leachate/gas:
• Monitoring of leachate/gas plays a vital role in the management of landfills.
• Data on the volume of leachate/gas and their composition are essential for proper control of leachate/gas generation and its treatment.
Knowledge of the chemical composition of leachate/gas is also required to confirm that attenuation processes within the landfill are
proceeding as expected.
• Various systems for monitoring the leachate level are in use, and are mostly based on pipes installed prior to land filling.
• Note that small bore perforated plastic pipes are relatively cheaper and easier to install, but have the disadvantage of getting damaged faster
during infilling.
• Placing pipes within a column or tyres may, however, offer some protection.

(ii) Groundwater:
• A continued groundwater-monitoring programme for confirming the integrity of the liner system is essential.
• At an early stage of site preparation, therefore, a number of monitoring boreholes need to be provided around the site.
• However, the location, design and number of boreholes depend on the size of the landfill, proximity to an aquifer, geology ofthe site and
types of wastes deposited.
• Installation of a double liner system can make the monitoring exercise more accurate and easier to perform.
• Water should be regularly flushed through the secondary leachate collection system.
• In case this water is polluted, the primary leachate barrier will be damaged, and if repair is not considered possible, the leachate collected
must be transported to the leachate treatment facility.
Single-Liner Systems:

• Single liners consist of a clay liner, a geosynthetic clay liner, or a geomembrane.

• Single liners are sometimes used in landfills designed to hold construction and demolition debris.
• Construction and demolition debris results from building and demolition activities and includes concrete, asphalt, shingles, wood, bricks, and
glass.
• These landfills are not constructed to contain paint, liquid tar, municipal garbage, or treated lumber; consequently, single-liner systems are
usually adequate to protect the environment.
• It is cheaper to dispose of construction materials in a Construction and demolition debris landfill than in a municipal solid waste landfill
because Construction and demolition debris landfills use only a single liner and are therefore cheaper to build and maintain than other
landfills
Composite-Liner Systems:

• A composite liner consists of a geomembrane in combination with a clay liner.

• Composite-liner systems are more effective at limiting leachate migration into the subsoil than either a clay liner or a single
geomembrane layer.
• Composite liners are required in municipal solid waste (MSW) landfills.
• Municipal solid waste landfills contain waste collected from residential, commercial, and industrial sources.
• These landfills may also accept Construction and demolition debris, but not hazardous waste.
• The minimum requirement for MSW landfills is a composite liner.
• Frequently, landfill designers and operators will install a double liner system in MSW landfills to provide additional monitoring
capabilities for the environment and the community
Double-Liner Systems:

• A double liner consists of either two single liners, two composite liners, or a single and a composite liner.
• The upper (primary) liner usually functions to collect the leachate, while the lower (secondary) liner acts as a leak-detection system and
backup to the primary liner.
• Double-liner systems are used in some municipal solid waste landfills and in all hazardous waste landfills.
• Hazardous waste landfills (also referred to as secure landfills) are constructed for the disposal of wastes that once were ignitable, corrosive,
reactive, toxic.
• These wastes can have an adverse effect on human health and the environment, if improperly managed.
• Hazardous wastes are produced by industrial, commercial, and agricultural activities.
• Hazardous wastes must be disposed of in hazardous waste landfills.
• Hazardous waste landfills must have a double liner system with a leachate collection system above the primary composite liner and a leak
detection system above the secondary composite liner
UNIT-5
Detection of Subsurface Contamination:

1. **Groundwater Monitoring:**
- **Description:** Installation of monitoring wells to regularly sample and analyze groundwater for contaminants.
- **Methods:** Sampling and laboratory analysis of groundwater, often with the use of specific monitoring wells.

2. **Soil Sampling and Analysis:**

- **Description:** Collection of soil samples from various depths for laboratory analysis to identify and quantify contaminants.
- **Methods:** Core sampling, grab sampling, and analysis of soil samples for specific pollutants.

3. **Geophysical Surveys:**
- **Description:** Use of geophysical methods (e.g., electromagnetic surveys, ground-penetrating radar) to identify subsurface
anomalies.
- **Methods:** Non-invasive techniques to map subsurface features and potential contaminant plumes.

4. **Remote Sensing:**
- **Description:** Use of satellite or aerial imagery to detect surface indications of subsurface contamination.
- **Methods:** Analysis of spectral patterns to identify changes in vegetation, soil color, or surface characteristics.

5. **Borehole Logging:**
- **Description:** Sending probes or sensors down boreholes to measure physical properties of subsurface materials.
- **Methods:** Logging tools measure parameters like electrical conductivity, gamma radiation, and acoustic properties.
Control of Subsurface Contamination:

1. **Hydraulic Containment:**
- **Description:** Creating a hydraulic barrier to control the movement of contaminated groundwater.
- **Methods:** Pumping and treating contaminated groundwater, installing extraction wells, and controlling flow directions.

2. **Permeable Reactive Barriers (PRBs):**

- **Description:** Installation of reactive materials (e.g., zero-valent iron) in the subsurface to intercept and treat contaminant
plumes.
- **Methods:** Contaminated groundwater passes through the reactive barrier, promoting chemical reactions that immobilize
or degrade contaminants.

3. **Source Control:**
- **Description:** Implementing measures to contain or remove the source of contamination.
- **Methods:** Excavation and removal of contaminated soil, installation of physical barriers, and containment measures to
prevent further spread.

4. **Groundwater Pump and Treat:**

- **Description:** Extracting contaminated groundwater, treating it above ground, and then discharging or re-injecting the
treated water.
- **Methods:** Use of extraction wells, treatment systems (e.g., activated carbon, air stripping), and reinjection or discharge.

5. **Vapor Intrusion Mitigation:**

- **Description:** Preventing the migration of volatile contaminants from the subsurface into buildings.
- **Methods:** Installation of vapor barriers, ventilation systems, and soil depressurization systems.
Remediation of Subsurface Contamination:

1. **Excavation and Disposal:**

- **Definition:** Excavation involves digging up contaminated soil, and disposal refers to transporting and depositing the soil in a designated
area.
- **Working:** Heavy machinery like excavators is used to dig up contaminated soil, which is then loaded onto trucks and transported to
disposal sites such as landfills or treatment facilities.
- **Advantages:** Quick removal of visibly contaminated soil, applicable to a wide range of contaminants.
- **Disadvantages:** High costs, site disruption, potential for spreading contaminants during excavation, and primarily addresses surface
contamination.

2. **Soil Vapour Extraction:**

- **Definition:** Soil Vapor Extraction (SVE) removes volatile contaminants from the soil by applying a vacuum to extract vapors.
- **Working:** Vacuum pumps pull air through the soil, capturing volatile contaminants, which are then treated or processed.
- **Advantages:** Effective for volatile organic compounds (VOCs), relatively non-intrusive, and can be applied in situ (on-site).
- **Disadvantages:** Limited effectiveness for non-volatile contaminants, may not address deeper contamination, and requires energy-
intensive equipment.

3. **Thermal Desorption:**
- **Definition:** Thermal desorption uses heat to vaporize and separate contaminants from the soil, which are then collected and treated.
- **Working:** Contaminated soil is heated to release contaminants as vapor, and the vapor is then condensed and treated separately.
- **Advantages:** Effective for a wide range of contaminants, including volatile and semi-volatile compounds.
- **Disadvantages:** High energy requirements, potential for air emissions, and can be expensive.
4. **Vitrification:**
- **Definition:** Vitrification involves melting contaminated soil to create a glass-like substance, immobilizing contaminants within the glass
matrix.
- **Working:** Contaminated soil is heated to high temperatures, turning it into molten liquid, which is then cooled to form a solid glass-like
material.
- **Advantages:** Immobilizes contaminants, reduces leaching, and applicable to various contaminants.
- **Disadvantages:** High energy requirements, expensive, and may produce hazardous byproducts during the vitrification process.

5. **Soil Washing:**
- **Definition:** Soil washing uses physical or chemical processes to remove contaminants from soil particles.
- **Working:** Soil is mechanically or chemically treated to separate contaminants from the soil particles, and then the clean soil is returned to
the site.
- **Advantages:** Effective for removing a variety of contaminants, less disruptive than excavation.
- **Disadvantages:** Generation of secondary waste, may not be suitable for certain contaminants, and costs associated with treatment
processes.

6. **Stabilization/Solidification:**
- **Definition:** Stabilization/Solidification involves adding substances to the soil to stabilize or solidify contaminants, preventing their
migration.
- **Working:** Various additives (e.g., cement) are mixed with the contaminated soil to create a stable or solid mass.
- **Advantages:** Reduces mobility of contaminants, applicable to a variety of contaminants.
- **Disadvantages:** May not be suitable for all contaminants, potential for long-term effectiveness concerns, and the need for careful mixing
to achieve desired results.
7. **Electrokinetic Remediation:**
- **Definition:** Electrokinetic remediation uses electrical fields to move contaminants in soil towards electrodes for extraction or treatment.
- **Working:** Electrodes are placed in the soil, and an electric field is applied to drive contaminants towards the electrodes for subsequent
extraction or treatment.
- **Advantages:** Can be applied in situ, effective for certain types of contaminants.
- **Disadvantages:** Energy-intensive, limited to specific soil types and contaminants, and may require monitoring to prevent unintended
consequences.

8. **Bioremediation:**
- **Definition:** Bioremediation employs microorganisms to break down or transform contaminants into less harmful substances.
- **Working:** Microorganisms are introduced to the contaminated area, and environmental conditions are optimized to enhance microbial
activity, facilitating the breakdown of contaminants.
- **Advantages:** Environmentally friendly, applicable to a variety of contaminants, and cost-effective.
- **Disadvantages:** Requires specific conditions for optimal performance, may take longer than other methods, and effectiveness depends on
the type of contaminants and microbial activity.

9. **Phytoremediation:**
- **Definition:** Phytoremediation involves the use of plants to absorb, accumulate, or transform contaminants from the soil.
- **Working:** Plants with hyperaccumulating abilities are planted in contaminated soil, and they absorb and concentrate contaminants in their
tissues.
- **Advantages:** Sustainable, aesthetically pleasing, and applicable to various contaminants.
- **Disadvantages:** Can be slow, may require long-term monitoring, and effectiveness depends on plant species and contaminant types. may
be required.

Each approach has its advantages and limitations, and the choice depends on factors such as the type and extent of contamination, site
characteristics, regulatory requirements, and cost considerations. Site-specific assessments and ongoing monitoring are crucial for the successful
implementation of these strategies.
Barrier Systems:

1. **Landfill Liners:**
- **Description:** Impermeable liners (e.g., clay, geomembranes) are used in landfills to prevent leachate migration into surrounding soil and
groundwater.
- **Purpose:** To contain and isolate hazardous waste from the environment.

2. **Capping Systems:**
- **Description:** Caps, often consisting of clay, geomembranes, and vegetation, are placed over contaminated areas to prevent exposure and
control water infiltration.
- **Purpose:** Minimize water infiltration, control gas emissions, and reduce human and ecological exposure.

3. **Slurry Walls:**
- **Description:** Vertical barriers made of impermeable materials (e.g., clay, cement-bentonite) installed in the ground to contain the spread
of contaminants.
- **Purpose:** Prevent lateral migration of contaminants in soil and groundwater.

4. **Grout Curtains:**
- **Description:** Injection of impermeable materials (grout) into the subsurface to create a barrier against the movement of contaminants.
- **Purpose:** Restrict the flow of contaminants by filling voids and fractures in the subsurface.

5. **Sheet Piles:**
- **Description:** Interlocking sheets of steel or other materials driven into the ground to create a barrier against the spread of contaminants.
- **Purpose:** Used as vertical barriers to prevent the lateral movement of contaminants.
Reclamation Techniques:

1. **Phytoremediation:**
- **Description:** The use of plants to absorb, accumulate, and sometimes transform contaminants in the soil.
- **Purpose:** Extract or immobilize contaminants, often used in conjunction with other remediation methods.

2. **Bioremediation:**
- **Description:** The use of microorganisms to break down or transform contaminants into less harmful substances.
- **Purpose:** Accelerate the natural degradation of contaminants in soil and groundwater.

3. **Soil Washing:**
- **Description:** Physical or chemical processes to remove contaminants from soil particles.
- **Purpose:** Separate and concentrate contaminants, reducing the overall volume of contaminated soil.

4. **In Situ Chemical Oxidation (ISCO):**

- **Description:** Injection of chemical oxidants (e.g., hydrogen peroxide, ozone) into the subsurface to break down
contaminants.
- **Purpose:** Enhance the degradation of organic contaminants in situ.

5. **In Situ Chemical Reduction (ISCR):**

- **Description:** Injection of chemical reducing agents (e.g., zero-valent iron) to transform and immobilize contaminants.
- **Purpose:** Reduce the toxicity and mobility of certain contaminants in situ.
6. **Electrokinetic Remediation:**
- **Description:** Application of electrical fields to move contaminants in soil towards electrodes for extraction or treatment.
- **Purpose:** Enhance the removal of contaminants, especially ions and metals.

7. **Natural Attenuation:**
- **Description:** Relying on natural processes (e.g., microbial degradation, dilution) to reduce contaminant concentrations
over time.
- **Purpose:** Allow natural processes to mitigate contamination without direct human intervention.

8. **Land Reclamation and Restoration:**

- **Description:** Transforming contaminated land into functional ecosystems or other beneficial uses.
- **Purpose:** Restore the ecological balance, support biodiversity, and create sustainable land use.

9. **Pump and Treat:**

- **Description:** Extracting contaminated groundwater, treating it to remove contaminants, and then returning the treated
water or disposing of it safely.
- **Purpose:** Prevent the migration of contaminated groundwater and reduce the risk of exposure.

10. **Soil Vapor Extraction (SVE):**

- **Description:** Extracting volatile contaminants from the soil through a vacuum.
- **Purpose:** Remove volatile organic compounds (VOCs) from the soil, reducing their potential migration.

These barrier systems and reclamation techniques are often used in combination, and the selection depends on the specific
characteristics of the contaminated site, the types of contaminants present, and regulatory requirements. Site assessments and
ongoing monitoring are critical for the successful implementation of these strategies.