LEVELLING

Levelling is a process of determining the height of one level relative to another. It is used in surveying to establish the elevation of a point relative to a datum, or to establish a point at a given elevation relative to a datum

 Waste transfer station Prepared by Dr.Anand Rejilin

A waste transfer station is a light industrial facility where municipal solid waste is temporarily staged in the course of its eventual journey to the landfill or waste-to-energy facility. Typical activities at the waste transfer station involved the unloading of garbage trucks, pre-screening, and removal of inappropriate items such as automobile batteries, compacting, and then reloading onto larger vehicles, including trucks, trains, and barges to their final destination.

 

 

 

 

 

Benefits of Transfer Stations

The transfer station is a key component of cost-effective solid waste transportation. By transferring the waste from local collection vehicles onto larger trailers or other transport modes such as barge and rail, the cost of transportation to distant disposal sites can be significantly reduced, freeing collection-specific vehicles and crews to devote their time to actual collection activities.

 

SOLID WASTE MANAGEMENT

Solid waste management is a term that is used to refer to the process of collecting and treating solid wastes. It also offers solutions for recycling items that do not belong to garbage or trash. As long as people have been living in settlements and residential areas, garbage or solid waste has been an issue. Waste management is all about how solid waste can be changed and used as a valuable resource.

Solid waste management should be embraced by each and every household, including the business owners across the world. Industrialization has brought a lot of good things and bad things as well. One of the adverse effects of industrialization is the creation of solid waste.

Categories of Waste

Organic waste: Kitchen waste, waste from food preparation, vegetables, flowers, leaves, fruits, and market places.

Combustibles: Paper, wood, dried leaves, packaging for relief items etc. that are highly organic and having low moisture content.

Non-combustibles: Metal, Tins, Cans, bottles, stones, etc.

Toxic waste: Old medicines, paints, chemicals, bulbs, spray cans, fertilizer and pesticide containers, batteries, shoe polish.

Recyclables: Paper, glass, metals, plastics.

Ashes or Dust: Residue from fires that are used for cooking.

Construction waste: Rubble, roofing, broken concrete etc.

Hazardous waste: Oil, battery acid, medical waste, industrial waste, hospital waste.

Dead animals: Carcasses of dead livestock or other animals.

Bulky waste: Tree branches, tires etc.

Soiled waste: Hospital waste such as cloth soiled with blood and other body fluids.

 

Various Sources of Solid Waste

Every day, tonnes of solid waste are disposed of at various landfill sites. This waste comes from homes, offices, industries and various other agricultural related activities.These landfill sites produce foul smell if waste is not stored and treated properly. It can pollute the surrounding air and can seriously affect the health of humans, wildlife and our environment. The following are major sources of solid waste:

 

1. Residential

Residences and homes where people live are some of the major sources of solid waste. The garbage from these places include food wastes, plastics, paper, glass, leather, cardboard, metals, yard wastes, ashes, and special wastes like bulky household items such as electronics, tires, batteries, old mattresses, and used oil.

2. Industrial

Industries are known to be one of the biggest contributors to solid waste. They include light and heavy manufacturing industries, construction sites, fabrication plants, canning plants, power and chemical plants. These industries produce solid waste in the form of housekeeping wastes, food wastes, packaging wastes, ashes, construction and demolition materials, special wastes, medical wastes as well as other hazardous wastes.

3. Commercial

Commercial facilities and buildings are yet another source of solid waste today. Commercial buildings and facilities, in this case, refer to hotels, markets, restaurants, godowns, stores and office buildings. Some of the solid wastes generated from these places include plastics, food wastes, metals, paper, glass, wood, cardboard materials, special wastes and other hazardous wastes.

4. Institutional

The institutional centers like schools, colleges, prisons, military barracks and other government centers also produce solid waste. Some of the common solid wastes obtained from these places include glass, rubber waste, plastics, food wastes, wood, paper, metals, cardboard materials, electronics as well as various hazardous wastes.

5. Construction and Demolition Areas

Construction and demolition sites also contribute to the solid waste problem. Construction sites include new construction sites for buildings and roads, road repair sites, building renovation sites and building demolition sites. Some of the solid wastes produced in these places include steel materials, concrete, wood, plastics, rubber, copper wires, dirt and glass.

 6. Municipal Services

The urban centers also contribute immensely to the solid waste crisis in most countries today. Some of the solid waste brought about by the municipal services include street cleaning, wastes from parks and beaches, wastewater treatment plants, landscaping wastes and wastes from recreational areas, including sludge.

 7. Treatment Plants and Sites

Heavy and light manufacturing plants also produce solid waste. They include refineries, power plants, processing plants, mineral extraction plants and chemical plants. Among the wastes produced by these plants, there are industrial process wastes, unwanted specification products, plastics, metal parts, just to mention a few.

 8. Agriculture

Crop farms, orchards, dairies, vineyards and feedlots are also sources of solid wastes. Among the wastes they produce are agricultural wastes, spoiled food, pesticide containers and other hazardous materials.

 9. Biomedical

This refers to hospitals and biomedical equipment and chemical manufacturing firms. In hospitals, there are different types of solid wastes produced. Some of these solid wastes include syringes, bandages, used gloves, drugs, paper, plastics, food wastes and chemicals. All these require proper disposal or else they will cause a huge problem for the environment and the people in these facilities.

 

Effects of Poor Solid Waste Management

1. Litter Surroundings

Due to improper waste disposal systems, particularly by municipal waste management teams, wastes heap up and become a menace. While people clean their homes and places of work, they litter their surroundings, which affect the environment and the community.

2. Impact on Human Health

Improper waste disposal can affect the health of the population living nearby the polluted area or landfills. The health of waste disposal workers and other employees involved with these landfill facilities are also at a greater risk. Exposure to wastes that handled improperly can cause skin irritations, respiratory problems, blood infections, growth problems, and even reproductive issues.

 3. Disease-causing Pests

This type of dumping of waste materials forces biodegradable materials to rot and decompose under improper, unhygienic and uncontrolled conditions. After a few days of decomposition, a foul smell is produced, and it becomes a breeding ground for different types of disease-causing insects as well as infectious organisms. On top of that, it also spoils the aesthetic value of the area.

 4. Environmental Problems

Solid wastes from industries are a source of toxic metals, hazardous wastes, and chemicals. When released to the environment, the solid wastes can cause biological and physicochemical problems to the environment that may affect or alter the productivity of the soils in that particular area.

 5. Soil and Groundwater Pollution

Toxic materials and chemicals may seep into the soil and pollute the groundwater. During the process of collecting solid waste, hazardous wastes usually mix with ordinary garbage and other flammable wastes making the disposal process even harder and risky.

 6. Emission of Toxic Gases

When hazardous wastes like pesticides, batteries containing lead, mercury or zinc, cleaning solvents, radioactive materials, e-waste and plastics mixed up with paper and other non-toxic scraps are burned they produce dioxins, furans, polychlorinated biphenyls, and other gases. These toxic gases have the potential of causing various diseases, including cancer.

 7. Impact on Land and Aquatic Animals

Our carelessness with our waste and garbage also affects animals, and they suffer the effects of pollution caused by improperly disposed of wastes and rubbish. Consuming Styrofoam and cigarette butts have been known to cause deaths in marine animals. Animals are also at risk of poisoning while consuming grasses near contaminated areas or landfills as the toxins seep into the soil.

 

Methods of Solid Waste Management

There are different methods of solid waste management. The following are some of the recognized methods:

1. Sanitary Landfill

This is the most popular solid waste disposal method used today. Garbage is basically spread out in thin layers, compressed and covered with soil or plastic foam.

Modern landfills are designed in such a way that the bottom of the landfill is covered with an impervious liner, which is usually made of several layers of thick plastic and sand. This liner protects the groundwater from being contaminated because of leaching or percolation.

When the landfill is full, it is covered with layers of sand, clay, topsoil and gravel to prevent seepage of water.

Advantage: If landfills are managed efficiently, it is an ensured sanitary waste disposal method.

Constraint: It requires a reasonably large area.

 

2. Incineration

This method involves the burning of solid wastes at high temperatures until the wastes are turned into ashes. Incinerators are made in such a way that they do not give off extreme amounts of heat when burning solid wastes. Incinerators that recycle heat energy through furnace and boiler are called waste-to-energy plants. These waste-to-energy systems are more expensive to set up and operate compared to plain incinerators because they require special equipment and controls, highly skilled technical personnel, and auxiliary fuel systems. This method of solid waste management can be done by individuals, municipalities and even institutions. The good thing about this method is the fact that it reduces the volume of waste up to 20 or 30% of the original volume.

Advantage: The volume of combustible waste is reduced considerably by burning waste. In the case of off-site pits, it is an appropriate method to minimize scavenging.

Constraint: It can cause smoke or fire hazard and also emits gaseous pollutants.

 

3. Recovery and Recycling

Recycling or recovery of resources is the process of taking useful but discarded items for the next use. Plastic bags, tins, glass and containers are often recycled automatically since, in many situations, they are likely to be scarce commodities. Traditionally, these items are processed and cleaned before they are recycled. The process aims at reducing energy loss, consumption of new material and reduction of landfills. The most developed countries follow a strong tradition of recycling to lower volumes of waste.

Advantage: Recycling is environmentally friendly.

Constraint: It is expensive to set up, and in most emergencies, there is limited potential.

 

4. Composting

Due to a lack of adequate space for landfills, biodegradable yard waste is allowed to decompose in a medium designed for the purpose. Only biodegradable waste materials are used in composting. It is a biological process in which micro-organisms, specifically fungi and bacteria, convert degradable organic waste into substances like humus. This finished product, which looks like soil, is high in carbon and nitrogen. Good quality environmentally friendly manure is formed from the compost that is an excellent medium for growing plants and can be used for agricultural purposes.

Advantage: Composting is environmentally friendly as well as beneficial for crops.

Constraint: It requires intensive management and experienced personnel for large scale operation.

 

5. Pyrolysis

This is a method of solid waste management whereby solid wastes are chemically decomposed by heat without the presence of oxygen. It usually occurs under pressure and at temperatures of up to band small quantities of liquid.

Advantage: This will keep the environment clean and reduce health and settlement problems.

Constraint: The systems that destroy chlorinated organic molecules by heat may create incomplete combustion products, including dioxins and furans. These compounds are highly toxic in the parts per trillion ranges. The residue it generates may be hazardous wastes, requiring proper treatment, storage, and disposal.

MASS MOVEMENT by Mr. Charles Dyson

Mass movement, also called Mass Wasting, bulk movements of soil and rock debris down slopes in response to the pull of gravity, or the rapid or gradual sinking of the Earth’s ground surface in a predominantly vertical direction. Formerly, the term mass wasting referred to a variety of processes by which large masses of crustal materials are moved by gravity from one place to another. More recently, the term mass movement has been substituted to include mass wasting processes and the sinking of confined areas of the Earth’s ground surface. Mass movements on slopes and sinking mass movements are often aided by water and the significance of both types is the part each plays in the alteration of landforms.

 volcanoes by Mr. Charles Dyson

Types of Volcanoes & Eruptions

 

Volcanic Fields

Volcanic fields, such as Auckland and Northland, are where small eruptions occur over a wide geographic area, and are spaced over long periods of time (thousands of years). Each eruption builds a new single new volcano, which does not erupt again. Mount Eden and Rangitoto Island are examples in Auckland.

Cone Volcanoes

Cone volcanoes (also called composite cone or stratovolcanoes) such as Ruapehu, Taranaki / Egmont and Ngauruhoe, are characterised by a succession of small-moderate eruptions from one location. The products from the successive eruptions over thousands of years build the cones.

Caldera Volcanoes

Caldera volcanoes, such as Taupo and Okataina (which includes Mt Tarawera), have a history of infrequent but moderate-large eruptions. The caldera forming eruptions create super craters 10-25 km in diameter and deposit cubic kilometres of ash and pumice.

Types of eruptions

Multiple types of eruptions can occur at each of New Zealand’s volcanoes - the eruption type can vary minute to minute. The style of eruption depends on a number of factors, including the magma chemistry and content, temperature, viscosity (how runny the magma is), volume and how much water and gas is in it, the presence of groundwater, and the plumbing of the volcano. For information on volcanic hazards which can be produced by our volcanoes.

Hydrothermal eruption

An eruption driven by the heat in a hydrothermal systems. Hydrothermal eruptions pulverise surrounding rocks and can produce ash, but do not include magma. These are typically very small eruptions

Phreatic eruption

An eruption driven by the heat from magma interacting with water. The water can be from groundwater, hydrothermal systems, surface runoff, a lake or the sea. Phreatic eruptions pulverise surrounding rocks and can produce ash, but do not include new magma.

Phreatomagmatic eruption

An eruption resulting from the interaction of new magma or lava with water and can be very explosive. The water can be from groundwater, hydrothermal systems, surface runoff, a lake or the sea.

Lava

Lava is molten rock erupted at the ground surface. When molten rock is beneath the ground, it is called magma.

·        Lava flows are the effusive (non-explosive) outpourings of lava, and usually flow slower than walking pace. Lava flow types include a’a, blocky and pahoehoe.

·        Lava fountains are a fountain of runny lava fragments from a vent or line of vents (a fissure). They can form spatter piles, and if the fragments accumulate fast enough, they can form lava flows.

·        Lava domes are mounds that form when viscous lava is erupted slowly and piles up over the vent, rather than moving away as a lava flow. They are generally caused by viscous, thick, sticky lava that has lost most of its gas. They can range in volume from a few cubic metres to cubic kilometres.

Strombolian and Hawaiian eruptions

These are the least violent types of explosive eruptions. Hawaiian eruptions have fire fountains and lava flows, whereas Strombolian eruptions have explosions causing a shower of lava fragments.

Vulcanian eruptions

Vulcanian eruptions are small to moderate explosive eruptions, lasting seconds to minutes. Ash columns can be up to 20 km in height, and lava blocks and bombs may be ejected from the vent.

Subplinian and Plinian eruptions

Eruptions with a high rate of magma discharge, sustained for minutes to hours. They form a tall, convective eruption column of a mixture of gas and rock particles, and can cause wide dispersion of ash. Subplinian eruption columns are up to 20 km high, and are relatively unsteady, whereas Plinian eruptions have 20 to 35 km tall columns which may collapse to form pyroclastic density currents (PDC’s). Very rare Ultraplinian eruptions are even larger and have a higher magma discharge rate than Plinian eruptions.

Volcanoes and types of volcanic eruptions

Environmental impact of modern agriculture by Dr.S.Charles Ruskin Kumar

 Stress and Strain

Stress

Stress is the ratio of applied force F to a cross section area - defined as "force per unit area".

                                                          

• 
  tensile stress - stress that tends to stretch or lengthen the material - acts normal to the stressed area
• compressive stress - stress that tends to compress or shorten the material - acts normal to the stressed area
• shearing stress - stress that tends to shear the material - acts in plane to the stressed area at right-angles to compressive or tensile stress

Tensile or Compressive Stress - Normal Stress

Tensile or compressive stress normal to the plane is usually denoted "normal stress" or "direct stress" and can be expressed as

σ = F_n / A                                    

where

σ = normal stress (Pa (N/m²), psi (lb_f/in²))

F_n = normal force acting perpendicular to the area (N, lb_f)

A = area (m², in²)

• a kip is an imperial unit of force - it equals 1000 lb_f (pounds-force)
• 1 kip = 4448.2216 Newtons (N) = 4.4482216 kilo Newtons (kN)

A normal force acts perpendicular to area and is developed whenever external loads tends to push or pull the two segments of a body.

Shear Stress

Stress parallel to a plane is usually denoted as "shear stress" and can be expressed as

τ = F_p / A                              

where

τ = shear stress (Pa (N/m²), psi (lb_f/in²))

F_p = shear force in the plane of the area (N, lb_f)

A = area (m², in²)

A shear force lies in the plane of an area and is developed when external loads tend to cause the two segments of a body to slide over one another.

Strain (Deformation)

Strain is defined as "deformation of a solid due to stress". 

• Normal strain - elongation or contraction of a line segment
• Shear strain - change in angle between two line segments originally perpendicular

Normal strain and can be expressed as

ε = dl / l_o

   = σ / E                             

where

dl = change of length (m, in)

l_o = initial length (m, in)

ε = strain - unit-less

E = Youngs Modulus (Modulus of Elasticity) (Pa , (N/m²), psi (lb_f/in²))

• Young's modulus can be used to predict the elongation or compression of an object when exposed to a force

Note that strain is a dimensionless unit since it is the ratio of two lengths. But it also common practice to state it as the ratio of two length units - like m/m or in/in.

• Poisson's ratio is the ratio of relative contraction strain

Strain Energy

Stressing an object stores energy in it. For an axial load the energy stored can be expressed as

U = 1/2 F_n dl

where

U = deformation energy (J (N m), ft lb)

 

Deflection 

Deflection is the degree to which a structural element is displaced under a load (due to its deformation). It may refer to an angle or a distance. The deflection distance of a member under a load can be calculated by integrating the function that mathematically describes the slope of the deflected shape of the member under that load. Standard formulas exist for the deflection of common beam configurations and load cases at discrete locations. Otherwise methods such as virtual work, direct integration, Castigliano's method, Macaulay's method or the direct stiffness method are used. The deflection of beam elements is usually calculated on the basis of the Euler–Bernoulli beam equation while that of a plate or shell element is calculated using plate or shell theory. An example of the use of deflection in this context is in building construction. Architects and engineers select materials for various applications.

The deformation of a beam

The deformation of a beam is usually expressed in terms of its deflection from its original unloaded position. The deflection is measured from the original neutral surface of the beam to the neutral surface of the deformed beam

Thermal Stress and strain

Thermal stress is mechanical stress created by any change in temperature of a material. These stresses can lead to fracturing or plastic deformation depending on the other variables of heating, which include material types and constraints.[1] Temperature gradients, thermal expansion or contraction and thermal shocks are things that can lead to thermal stress. This type of stress is highly dependent on the thermal expansion coefficient which varies from material to material. In general, the greater the temperature change, the higher the level of stress that can occur. Thermal shock can result from a rapid change in temperature, resulting in cracking or shattering.

 

Thermal strains are strains that develop when a material is heated or cooled, they can be the bane of an engineer’s existence if they are not considered Materials that fit perfectly at one temperature can rupture or fall out when their environmental temperature changes.