Explanation: Intakes are devices specifically designed for drawing water from its source, such as rivers or lakes.
Explanation: The intake point should be strategically chosen, considering factors like proximity to the treatment plant, water source purity, and being upstream of waste water disposal.
Explanation: In the context of gravity water supply systems, the initiation point is the intake. This marks the beginning of the system, where water is drawn from the source and sets in motion the downstream flow through various stages of treatment and distribution.
Explanation: At the entrance of the intake point, a thrash rack or roughing filter is commonly installed. This component serves the crucial function of filtering out large debris and contaminants before the water undergoes further treatment processes.
Explanation: In the hill regions and terai (plain) areas of our country, the most common sources of water are surface water in hills and groundwater in the terai. This distinction is essential for understanding and planning water supply systems tailored to the specific characteristics of each region.
Explanation: Among the options provided, an elevated lake is considered a good source of water requiring minimal treatment. This is due to the relatively pristine nature of water in elevated lakes, reducing the need for extensive treatment processes before distribution.
Explanation: In mountainous regions, streams are a prevalent source of water.
Explanation: The term “Puits developee” is generally associated with the development of wells. This emphasizes the importance of proper well construction and development techniques for efficient water extraction.
Explanation: An infiltration gallery is a type of horizontal well used to collect water from the surrounding soil.
Explanation: The minimum depth of an infiltration gallery is typically set at 2 meters. This depth ensures effective water collection from the subsurface environment for subsequent treatment and distribution.
Explanation: Among the aquifer types, a perched aquifer is characterized by the least water-bearing capacity.
Explanation: The application of the watershed control method is primarily focused on controlling sedimentation in reservoirs. This approach plays a vital role in maintaining the reservoir’s capacity and water quality by minimizing the influx of sediments.
Explanation: Shrouding involves the process of filling materials such as gravel and bajri in a slotted tube well. This technique enhances the well’s structural stability and facilitates efficient water extraction from the surrounding aquifer.
Explanation: Drain valves in distribution pipes are strategically placed at various locations, including lower points, higher points, and junctions. This flexibility allows for effective drainage and maintenance of the distribution system.
Explanation: The minimum required residual head at a public tap stand is usually set to be not less than 5 units.
Explanation: Bentonite and thixotropy are both used during drilling operations to prevent caving. Bentonite, when hydrated, forms a viscous slurry, and thixotropy refers to the property of certain materials to become less viscous when agitated and return to a more solid state when left undisturbed. The combination of these materials helps maintain stability during drilling.
Explanation: The radius of influence of a well is influenced by the rate of pumping. As the rate of pumping increases, the zone of influence around the well also expands.
Explanation: Surface water is primarily obtained from natural sources such as rivers, lakes, and rainfall.
Explanation: Groundwater from artesian wells generally contains no suspended materials, often has dissolved salts, and may require less treatment compared to other sources.
Explanation: The rate of flow in an artesian spring is continuous, and it tends to increase as the water table rises.
Explanation: Clean gravel typically has a higher coefficient of permeability compared to other soil types, allowing water to flow more easily.
Explanation: An aquiclude is a geological formation that acts as a barrier to the flow of groundwater, often found between aquifers.
Explanation: A perched aquifer is typically found above the main water table and is separated from it by an unsaturated zone.
Explanation: Coarse gravel has the least specific retention among the mentioned soil types.
Explanation: Darcy’s formula is widely used to calculate the velocity of flow of underground water in porous media.
Explanation: Sinking a well into coarse gravel is generally considered advantageous as it allows for better water flow and easier well construction.
Explanation: Water can be supplied to consumers from various sources, including rainy wells, infiltration wells along riverbanks, and infiltration galleries connected to a sump well.
Explanation: Dug wells, or open wells, typically have a diameter between 1 to 4 meters, are suitable for smaller discharges, and are generally cost-effective in terms of construction.
Explanation: Specific yield of wells is expressed as the volume of water that can be released from an aquifer per unit volume of the aquifer per unit decline in head.
Explanation: Strainer wells are widely used tube wells in Nepal for extracting groundwater.
Explanation: To have an insignificant effect on the water table, tube wells are generally spaced at a distance of one in every 1.5 square kilometers.
Explanation: The interference of a well is influenced by factors such as the number of wells, the spacing between wells, and the types of wells in operation.
Explanation: Strainer type tube wells are not suitable for fine sand strata due to the risk of sand ingress and reduced efficiency.
Explanation: In strainer type wells, the flow of water is typically radial, moving outward from the wellbore.
Explanation: Abyssinian tube well is a special type of strainer type tube well designed for specific geological conditions.
Explanation: The maximum depression of the water table in a well due to pumping occurs at a distance equal to half the radius of influence (r/2) from the well.
Explanation: The curve showing the level of water in a well and the original water table is known as the drawdown curve.
Explanation: The relation between porosity, specific yield, and specific retention is expressed as porosity equals the sum of specific yield and specific retention.
Explanation: The slope of the hydraulic grade line towards the well creates an inverted cone of depression in the water table.
Explanation: The yield from the tube well can be calculated using the formula Q = K * h * A, where Q is the discharge, K is the coefficient of permeability, h is the drawdown, and A is the cross-sectional area of the well.
Explanation: The average discharge of a tube-well is approximately 50 liters per second.
Explanation: Deep wells typically have more discharge compared to shallow tube wells.
Explanation: The depth of a shallow tube well is economically considered up to 30 meters.
Explanation: The total quantity of a reservoir includes balancing reserve, breakdown reserve, fire reserve, and other contingencies.
Explanation: The mass curve is used to determine the capacity of a reservoir by plotting the cumulative inflow against time.
Explanation: A break pressure tank is typically installed in rural water supply schemes when the static head, or the vertical distance between the water source and the highest point of distribution, exceeds 60 meters. This tank helps manage and control pressure in the system.
Explanation: Formwork for ferrocement tanks in rural water supply schemes can be made using High-Density Polyethylene (HDP) pipes, providing a durable and cost-effective solution for construction.
Explanation: The sickness of a tube well typically refers to a reduction in its yield, indicating a decline in the amount of water it can provide.
Explanation: R.M.O. stands for Running, Maintenance, and Operation, encompassing all activities related to the continuous operation and upkeep of equipment or systems.
Explanation: Gastrointestinal irritation can be caused by an excess of sulphates in water, leading to discomfort and health issues related to the digestive system.
Explanation: Dental caries is less likely to occur in the presence of mottled enamel of teeth. Mottled enamel is a condition caused by excessive fluoride, which can provide protection against dental caries.
Explanation: Fluoridation is the process of adding fluoride to water to protect children’s teeth and prevent dental cavities without causing dental or skeletal fluorosis.
Explanation: Excessive concentration of chlorides in water can contribute to kidney damage, affecting the normal functioning of the kidneys.
Explanation: Tuberculosis is an example of a communicable disease, meaning it can be transmitted from person to person.
Explanation: Diseases caused by the lack of water, such as those related to poor hygiene and sanitation, are termed water-washed diseases.
Explanation: Dysentery is a waterborne disease, typically caused by contaminated water containing pathogenic microorganisms.
Explanation: Jaundice is a waterborne infection caused by viruses, often transmitted through contaminated water.
Explanation: Methemoglobinemia, also known as Blue Baby Syndrome, occurs when nitrates replace oxygen in hemoglobin, leading to a reduced ability to transport oxygen in the blood.
Explanation: Goitre is primarily caused by a deficiency or excess of iodine in the diet, affecting the thyroid gland.
Explanation: The growth of a population can be conveniently represented by a logistic curve, which illustrates a gradual increase, stabilization, and then a possible decline in population over time.
Explanation: Per capita water demand is calculated in liters per person per day, providing a measure of the average individual daily water consumption.
Explanation: The water demand of a city encompasses domestic water demand, commercial and industrial demand, as well as fire and public-use demand.
Explanation: In a fully plumbed system in the context of Nepal, the water supply demand is typically considered as 112 liters per capita per day (lpcd).
Explanation: The water supply demand in a day school without boarders is generally calculated as 10 liters per capita per day (lpcd).
Explanation: The fire demand of a city is often calculated using formulas such as the underwriters formula, freeman formula, and kuichling’s formula.
Explanation: According to the Kuichling formula, the fire demand of water in liters per minute is given by 3182 times the square root of the population in thousands.
Explanation: Buston’s formula expresses the fire demand in liters per minute as 5663 times the square root of the population in thousands.
Explanation: In the design of waterworks for a city, water demand for public use is typically considered around 5% of the total demand.
Explanation: To account for losses, thefts, and wastage of water, an allowance of 35% is often made, as per the Nepal Water Supply Corporation (NWSC) guidelines.
Explanation: The per capita consumption of a locality is influenced by climatic conditions, the quality of water supplied, and the distribution pressure within the water supply system.
Explanation: The per capita consumption of a locality tends to be higher when good-quality water is supplied, during summer months, and when distribution pressure is increased.
Explanation: The use of a metering system can contribute to a decrease in per capita consumption by promoting water conservation and efficient use.
Explanation: The hourly variation factor is generally taken as 2.3 to account for fluctuations in water demand throughout the day.
Explanation: The ratio of the maximum daily consumption to the average demand is often considered as 1.8 in water supply system design.
Explanation: The ratio of maximum hourly consumption to the average hourly consumption on the maximum day is typically taken as 2.7 for designing water supply systems.
Explanation: The maximum daily consumption on peak hourly demand can be estimated as 2.7 times the average daily consumption. In this case, it would be 2.7 × 105 m3.
Explanation: The distribution mains in a water supply system are designed for the maximum hourly demand on the maximum consumption day to ensure sufficient capacity during peak usage periods.
Explanation: The Goodrich formula is expressed as P=180t-0.10, where P is the percent of the annual average draft for the time t in days.
Explanation: Normally, the shape of the demand line is considered as straight in water supply system design.
Explanation: Water samples are typically collected from 40-50 cm below the surface to ensure representative quality testing.
Explanation: The filtration rate of Slow Sand Filters (SSF) is typically in the range of 100-150 liters per square meter per hour.
Explanation: The filtration rate of Rapid Sand Filters (RSF) is generally in the range of 100-150 liters per square meter per minute.
Explanation: The filtration rate of Pressure filters falls within the range of 100-250 liters per square meter per minute.
Explanation: For a community water supply system in Biratnagar, a Slow Sand Filter (SSF) is generally a suitable choice for effective water filtration.
Explanation: The selection of a pumping station site is influenced by factors such as the distance from the source of contamination, height above the Highest Flood Level (H.F.L.) of the river, and considerations for future expansion.
Explanation: Centrifugal pumps are suitable for both water and sewage applications.
Explanation: Priming is the process of removing trapped air from the pump to ensure effective operation.
Explanation: A hydraulic ram pump does not require external power, energy, or fuel for its working.
Explanation: A traddle pump is typically operated by foot.
Explanation: Rotary pumps are well-suited for applications with small discharge requirements.
Explanation: A booster pump is specifically used to increase the pressure of water in a system.
Explanation: The head developed in a centrifugal pump when the discharge is zero is referred to as the shut off head.
Explanation: The water horsepower (WHP) of a pump is calculated by dividing the work done (WHQ) by 75.
Explanation: The combined efficiency of the pump and motor is calculated by multiplying their individual efficiencies (85% and 94%), resulting in 80.1%, but generally expressed as 80%.
Explanation: Wholesome water is water that may not be chemically pure but does not contain harmful substances that pose a risk to human health.
Explanation: Natural streams undergo self-purification through processes such as dilution, oxygen reduction, and exposure to sunlight.
Explanation: Water analysis involves physical, chemical, and biological tests to assess various aspects of water quality.
Explanation: Dyspepsia, or indigestion, can be caused by the presence of iron in water.
Explanation: Copper is considered good for keeping drinking water as it has antimicrobial properties.
Explanation: Sterilized water is commonly used for medical purposes to ensure it is free from microorganisms.
Explanation: Odour is measured in terms of the threshold number, indicating the sensitivity of the human nose to detect odours.
Explanation: The odour of water is determined using an osmoscope.
Explanation: Goaty water refers to water with an unpleasant odour.
Explanation: The true colour of water is primarily due to the presence of colloidal solids.
Explanation: The colour of water is measured on the platinum cobalt scale using a tintometer.
Explanation: The color in water is often due to the presence of organic debris, including decomposing plant material and other organic substances.
Explanation: The purest water tends to have no color, appearing transparent without any noticeable coloration.
Explanation: Highly colored waters are considered unaesthetic, meaning they are not visually appealing.
Explanation: Colloidal particles in water typically have sizes ranging from 10^-3 to 10^-6 mm.
Explanation: Turbidity makes water unaesthetic as it appears cloudy or turbid, affecting its visual appeal.
Explanation: Turbidity is measured using a standard silica scale, quantifying the cloudiness of water based on the concentration of suspended particles.
Explanation: Turbidity depends on the presence of suspended solids and colloidal solids in water.
Explanation: Turbidity is the ability of water to scatter light due to the presence of particles.
Explanation: Turbidity is measured by assessing the intensity of light scattered as it passes through a water sample.
Explanation: Turbidity of a water sample depends on the concentration and density of suspended and colloidal solids.
Explanation: Turbidity is measured in NTU, which quantifies the cloudiness of water.
Explanation: Turbidity is undesirable as it can adversely affect the photosynthesis of aquatic life by reducing light penetration in water.
Explanation: Turbidity can be removed by employing coagulation and filtration techniques.
Explanation: Different turbidity meters such as Baylis, Hellige, and Jackson are suitable for measuring turbidity across various ranges.
Explanation: The pH of sewage can indicate its acidity, alkalinity, or neutrality. If pH < 7, sewage is acidic; if pH > 7, sewage is alkaline; and if pH = 7, sewage is neutral.
Explanation: Absolutely soft water is crucial for boilers as hard water can lead to the formation of scale, reducing the efficiency of the boiler. Scale is formed due to the precipitation of minerals present in hard water.
Explanation: Lead is considered the most dangerous metal for human health. Exposure to lead can lead to various health issues, especially affecting the nervous system.
Explanation: The pH value of water for water supply is typically maintained in the range of 6.5 to 8.5. This range is considered suitable for human consumption and prevents corrosion in pipes.
Explanation: B-coli (coliform bacteria) tests are conducted as they serve as a very good indicator of the presence of pathogenic bacteria. Their presence indicates potential contamination from fecal matter.
Explanation: In a presumptive test for B-coli, a lactose broth is commonly used as the culture medium. The presence of coliform bacteria can be detected through the fermentation of lactose.
Explanation: The Biological Oxygen Demand (BOD) in domestic water should ideally be nil. BOD measures the amount of dissolved oxygen consumed by microorganisms in the water, indicating its organic pollution level.
Explanation: Facultative bacteria can survive with or without oxygen. They have the ability to adapt to different environmental conditions.
Explanation: Disinfection of water involves the killing of disease-causing bacteria and microorganisms to make the water safe for consumption.
Explanation: The efficiency of chlorination as a disinfection method increases with the temperature of water. Warmer water enhances the effectiveness of chlorine in killing bacteria.
Explanation: Zinc is a heavy metal that generally has non-toxic properties. It is an essential mineral for the human body and is not considered harmful in moderate amounts.
Explanation: Sterilization is the process of eliminating all forms of life, including bacteria, viruses, and other microorganisms.
Explanation: The chemical formula of bleaching powder is CaOCl2. It is used as a disinfectant and for bleaching purposes.
Explanation: Aeration of water is done to achieve multiple purposes, including removing carbon dioxide, improving taste and odor, and increasing the oxygen content in the water.
Explanation: Aeration of water can be accomplished through various methods, including the use of spray nozzles, cascading, and trickling beds.
Explanation: Tuberculation in a metal pipe is caused by the activity of sulphur-reducing bacteria. These bacteria contribute to the formation of deposits and corrosion in the pipe.
Explanation: The presence of algae in water indicates that the water is acidic. Algae thrive in environments with lower pH levels.
Explanation: Alum, when added as a coagulant, increases the acidity of water. It is commonly used in water treatment processes.
Explanation: When alum is mixed with water as a coagulant, it tends to decrease the pH value of water. This is important in the coagulation and flocculation processes.
Explanation: The process of obtaining energy for bacterial synthesis through the oxidation of organic or inorganic matter is called chemosynthesis.
Explanation: Groundwater is generally free from suspended impurities, as these impurities are usually filtered out as water percolates through the soil.
Explanation: An excess concentration of sodium salts in water can cause a bitter taste. This is often undesirable for drinking water.
Explanation: An excess concentration of magnesium salts in water can have a laxative effect on individuals consuming the water.
Explanation: The maximum allowable amount of copper in domestic water is typically up to 3 ppm to ensure it meets health and safety standards.
Explanation: Iron in water can cause stains on clothes due to its ability to oxidize and form insoluble iron compounds.
Explanation: Lead in water can cause plumbo solvency, where lead dissolves into the water. This is a concern due to the health risks associated with lead exposure.
Explanation: Iron and manganese levels in water are often estimated using a calorimetric test, which measures the color changes associated with these elements.
Explanation: Water of zero hardness can be obtained through the base exchange process, which involves the removal of calcium and magnesium ions responsible for water hardness.
Explanation: Main pipes in water supply systems are typically designed to carry three times the average demand to ensure sufficient capacity during peak usage periods.
Explanation: Service pipes in water supply systems are generally designed to carry two times the average demand to meet the needs of consumers.
Explanation: The velocity of flow in a 1 m cast iron pipe carrying a discharge of 0.785 cum/sec can be calculated using the formula velocity = discharge area. In this case, the velocity is approximately 1.0 m/sec.
Explanation: The approximate diameter of the water mains can be determined based on the flow rate and velocity using hydraulic principles. In this case, a diameter of 30 cm is suitable for supplying the specified flow with the given velocity.
Explanation: Manning’s formula relates the hydraulic gradient, roughness coefficient (n), cross-sectional area, and wetted perimeter. With the given parameters and using Manning’s formula, the hydraulic gradient is calculated to be 1:800.
Explanation: The coverage of water supply in Nepal, as per the census of 2011, is reported to be 85%. This indicates the percentage of the population with access to a reliable water supply.
Explanation: A pressure conduit laid underground may not be subjected to significant longitudinal temperature stress. It primarily deals with internal pressure, external loads, and other factors.
Explanation: According to Lea’s formula, the economical diameter of the pipe (D) is related to the discharge (Q). The formula suggests that D should be in the range of 0.97 to 1.22 times the square root of Q.
Explanation: If the diameter of the main pipe is taken less than the economical diameter, it can result in higher head loss, reduced efficiency, lower carrying capacity, and increased pumping costs.
Explanation: The hoop stress in a pressure conduit is calculated using the formula d.p / 2t, where P is the total internal pressure, d is the diameter, and t is the thickness of the conduit.
Explanation: The Boussinesq formula for evaluating the superimposed load transmitted to a pipe is given by Pt = 3H3P / 2πz5, where P is the load, Z is the slant height, H is the top of the pipe, and z is the considered point’s height.
Explanation: Thrust blocks are installed wherever there is a change in the direction or size of the pipeline, a change in the pressure line diagram, or where the pipeline ends at a dead end. They help resist the thrust generated by fluid pressure.
Explanation: The formula v=1/n (r2/3s1/2) is associated with Manning’s formula, which relates the velocity (v) of flow in an open channel to the roughness coefficient (n), hydraulic radius (r), and slope (s).
Explanation: The Hydraulic Grade Line (HGL) should always be maintained above the Ground Level (GL) by a certain margin to ensure proper flow and pressure in the water supply system. A margin of 10 m is recommended in this context.
Explanation: The pressure at the inlet and outlet in a break pressure tank is maintained at zero. Break pressure tanks are designed to absorb excess pressure during pump shutdown, preventing water hammer and other issues.
Explanation: The velocity of water in water mains with a diameter of 40 cm is usually kept below 1.8 m/sec to minimize frictional losses, control water hammer, and ensure efficient water transportation.
Explanation: The selection of material for a pipe depends on various factors, including the carrying capacity, durability, life expectancy, and the potential effect of the conveyed water on the pipe material.
Explanation: Gravity conduits can take various forms, including open channels, conduits (pipes), and tunnels. These structures are designed to allow the flow of water under the influence of gravity.
Explanation: Gravity conduits are structures that carry water under the influence of gravity, following the hydraulic gradient line. They can include various forms such as open channels, aqueducts, flumes, conduits, and tunnels.
Explanation: The open channels supported above the ground over trestles are called flumes. Flumes are structures designed to convey water, typically in an open channel supported on raised supports or trestles.
Explanation: The most commonly used section in a grade aqueduct is rectangular. The choice of section depends on various factors, including hydraulic efficiency and construction considerations.
Explanation: Grade aqueducts are not allowed to run one-fourth full or half; they are designed to operate at full capacity. Running at full capacity ensures proper hydraulic performance.
Explanation: A circular gravity aqueduct is preferred due to its maximum hydraulic mean depth, maximum area per unit of wetted perimeter, and the potential for a cost-effective construction.
Explanation: Pressure conduits have advantages such as flow independence from the grade of the hydraulic grade line, economical construction due to a shorter path, and less chance of water pollution as they are closed systems.
Explanation: Aqueducts are generally not designed in a vee section. The section chosen for an aqueduct depends on hydraulic considerations and construction requirements, and vee sections are not commonly used.
Explanation: Asbestos cement pipes are generally laid vertically. The choice of laying position depends on the material properties and design considerations.
Explanation: Asbestos cement pipes are types of pipes that are generally laid vertically due to their relatively low strength compared to other materials.
Explanation: Cast iron is a commonly used material for water supply pipes that possesses properties of being not easily corroded, strong, having a long life, but being heavy and brittle.
Explanation: As compared to cast iron pipes, steel pipes are generally stronger. However, they may also be heavier and costlier depending on specific characteristics.
Explanation: A nominal internal diameter of 550 mm for a cast iron (spun) pipe is incorrect. Standard sizes for cast iron pipes typically include diameters such as 300 mm, 400 mm, and 500 mm.
Explanation: Steel pipes are generally laid underground, can be connected by riveted or welded joints, and are suitable for withstanding high internal pressure.
Explanation: Asbestos pipes are light in weight and easy to transport. While they have other properties, such as resistance to corrosion, their use has declined due to health and environmental concerns associated with asbestos.
Explanation: PVC pipes can withstand pressure up to 100 m head of water. PVC pipes are known for their durability, corrosion resistance, and ability to handle various levels of water pressure.
Explanation: If the head of water is more than 100 m, the type of pipe commonly used is GI (Galvanized Iron) due to its strength and durability under high pressure.
Explanation: The correct specifications for High-Density Polyethylene (HDP) pipe grades are as follows: – Grade II: 2.5 kg/cm2 – Grade III: 4 kg/cm2 – Grade IV: 6 kg/cm2
Explanation: Copper pipes are highly resistant to acidic and alkaline water, easy to bend, and do not sag when used for hot water supply. They are also not liable to corrosion.
Explanation: Service connections to consumer houses are generally provided with galvanized pipes due to their corrosion resistance and durability.
Explanation: A G.I. (Galvanized Iron) pipe has a coating of zinc, which helps protect the iron from corrosion.
Explanation: Sluice valves in main water supplies are used to regulate the flow, spaced about 5 km apart, and are generally provided at the summits.
Explanation: Pressure relief valves are provided in the water main to reduce pressure and are typically located upstream of the sluice valve or at the low point.
Explanation: Air inlet valves are provided in water mains at both the summit of the pipe and downstream of the sluice valve to allow the release of trapped air and maintain proper operation.
Explanation: The valve provided at low points of the pipe to drain off water quickly under gravity is a blow-off valve.
Explanation: The valve which allows water to flow in one direction but prevents its flow in the reverse direction is a reflux valve.
Explanation: Scour valves are provided at every depression and dead end to drain out the waste water that may collect there and prevent the accumulation of sediments.
Explanation: Poppet valve is a type of air valve used in water systems.
Explanation: The valve provided on the suction pipe in a tube-well is a reflux valve.
Explanation: Impetus valve or waste valve is provided in a hydraulic ram.
Explanation: Pressure relief valve is provided to prevent the increase of pressure beyond a certain limit in the system.
Explanation: The valve provided after the pump in the rising mains to prevent the backflow of water when the pump is stopped is called a reflux valve. It ensures that water does not flow back into the pump when it is not in operation.
Explanation: With the increase in the size of the water pipe, the permissible velocity decreases, assuming the discharge remains constant. Larger pipes are designed to accommodate a lower velocity to minimize frictional losses.
Explanation: High-Density Polyethylene (HDP) pipes are typically joined using butt welding, which involves connecting the plain ends of the pipes by heating and melting them together.
Explanation: Plastic pipes are often joined using solvent welding, where a solvent is applied to the joint surfaces, causing them to soften and fuse together.
Explanation: Asbestos pipes are commonly joined using a simplex joint, a type of joint where one pipe has a plain end (spigot), and the other has a socket into which the spigot is inserted.
Explanation: At the socket and spigot joint, the enlarged end of the pipe is called a socket, the normal end is called a spigot, and the spigot is fitted into the socket.
Explanation: Dresser coupling joints are often used to join the plain ends of cast-iron pipes. This type of joint involves using a mechanical coupling that wraps around the pipes and is tightened to create a seal.
Explanation: Flexible joints are designed to resist shock, vibration, and other movements. Dresser coupling joints, victaulic joints, and flanged joints may provide some flexibility, but the flexible joint is explicitly designed for this purpose.
Explanation: Cast-iron pipes can be joined using various types of joints, including flanged joints, socket and spigot joints, and dresser coupling joints, depending on the specific application and requirements.
Explanation: To accommodate temperature changes, metal pipes are usually provided with expansion joints, which allow for expansion and contraction without causing damage to the pipe or the connected components.
Explanation: Flanged joints are commonly used in pumping stations due to their ease of installation and maintenance. They provide a secure connection and allow for easy disassembly when necessary.
Explanation: The maximum pressure that a pipe can withstand without any leakage during the hydrostatic pressure test is referred to as the test pressure. This test is conducted to ensure the integrity of the pipe before it is put into service.
Explanation: Pipes for water supply undergo testing for pressure, leakage, and dimensional accuracy to ensure they meet the required standards and specifications.
Explanation: The water supply pipeline should typically be tested at a specified pressure for two hours to ensure its integrity and performance under operating conditions.
Explanation: If the reduced level of the source of water is higher (100 m) than the reduced level of the town (50 m), a gravity system can be employed, allowing water to flow naturally from the higher elevation source to the lower elevation town without the need for pumping.
Explanation: The dead-end system is suitable for haphazardly growing cities where the layout is not well-planned. In this system, water mains are laid as dead-end lines without forming a complete grid or loop.
Explanation: The grid iron system is characterized by the interconnection of main, sub-main, and branch lines, forming a grid-like pattern. This layout allows for better distribution and redundancy in the water supply network.
Explanation: Computation of discharges is more challenging in a grid iron system due to the interconnected nature of the network. The flow paths are not straightforward, making it more complex to calculate discharges accurately.
Explanation: A right-angled sleeve (valve) connected in the water main through which water is tapped for domestic supply is called a ferrule.
Explanation: A goose neck is a bent flexible pipe typically located between the ferrule (valve) and the stop cock in a water supply system.
Explanation: Hydrants are versatile outlets used for various purposes, including fire extinguishing, street washing, and flushing sewer lines.
Explanation: The minimum size of a fire hydrant is typically 15 cm, ensuring an adequate flow of water for firefighting purposes.
Explanation: According to the guidelines of the Drinking Water Supply and Sanitation (DWSS), the maximum number of users in each stand post should be 100.
Explanation: Incrustation of well pipes can be reduced by periodically removing the deposited material, which may accumulate on the screens or inside the pipes.
Explanation: Corrosion of well pipes can be reduced by using thicker pipes, reducing the flow velocity, and minimizing the drawdown (lowering the water level) to decrease the exposure of the pipes to corrosive elements.
Explanation: Sanitary sewage includes both domestic sewage from households and industrial sewage from industrial processes.
Explanation: Fresh sewage is generally alkaline, while septic sewage tends to become acidic due to the production of acids during the decomposition of organic matter.
Explanation: The majority of sewage consists of water, with a high percentage ranging from 95% to 99.9%, depending on the specific composition of the sewage.
Explanation: The specific gravity of sewage is slightly more than 1 due to the presence of dissolved and suspended solids, making it denser than pure water.
Explanation: The sewerage system originates from house sewers, which collect wastewater from individual households and convey it to the main sewers for further transport and treatment.
Explanation: The water carriage sewage system requires treatment before disposal to remove pollutants and ensure that the discharged water is environmentally safe. This is a key aspect of managing sewage in such systems.
Explanation: The merits of the water carriage sewage system include the absence of direct human involvement, the reduction of foul smells and hygienic issues, and the requirement of less land area compared to some other systems.
Explanation: The sewerage system is designed to accommodate both maximum and minimum flows. The design considers variations in flow rates to ensure effective and efficient conveyance of sewage under different conditions.
Explanation: In areas with rainfall for only one season, a separate system of sanitation is suitable. This system keeps stormwater and sewage separate, preventing overloading of the system during heavy rainfall.
Explanation: Circular sewers are suitable for a separate system where the discharge is uniform. Circular sewers are hydraulically efficient and can handle a consistent flow of sewage.
Explanation: In areas with distributed rainfall throughout the year and less intensity, a combined system of sanitation is suitable. This system combines stormwater and sewage, providing a more integrated approach to conveyance.
Explanation: Sewers have to bear internal pressure from sewage flow, temperature stresses, and forces due to external loads, such as traffic loads or soil loads.
Explanation: A lateral sewer collects sewage from individual toilets and conveys it to a larger sewer, such as a branch sewer.
Explanation: A relief sewer is designed to carry excess discharge from an existing sewer, providing additional capacity during peak flow periods.
Explanation: A lateral sewer receives the discharge from multiple house sewers and conveys it to a larger sewer or sub-main sewer.
Explanation: A trunk sewer receives discharge from two or more main sewers and serves as a major conduit in the sewerage system.
Explanation: An egg-shaped sewer is preferred for a combined system of sewage. It provides both hydraulic efficiency and the ability to transport both sewage and stormwater.
Explanation: Cleanouts are provided in lateral sewers in place of manholes. Cleanouts allow for access to the sewer for maintenance purposes.
Explanation: The correct order in the sewerage system is from individual house sewers (house s.) to lateral sewers, branch sewers, sub-main sewers, main (trunk) sewers, and finally, outfall sewers.
Explanation: Stoneware pipes are generally not used for sewer mains because they are weak in tension. They are more susceptible to cracking or breaking under tensile stresses.
Explanation: Glazed stoneware is known for its resistance to hydrogen sulfide corrosion, making it a suitable material for sewers where such corrosion is a concern.
Explanation: Two sewer sections laid at the same grade will be hydraulically equivalent if their discharge capacities when running full are equal. Hydraulically equivalent sections can handle the same flow rates.
Explanation: A sewer that receives flow from a number of transverse sewers is known as an interceptor. It intercepts the flow from these sewers.
Explanation: Laying of a sewer is generally done with the help of sight rails and a boning rod. This helps in ensuring the proper alignment and gradient during construction.
Explanation: Ovoid sewers are best suited for combined systems with very wide fluctuations in flow. The shape provides stability and efficient flow under varying conditions.
Explanation: A flight sewer is provided when the gradient is steep. It is designed for locations where the terrain has a significant slope.
Explanation: A circular section is most suitable when the maximum and minimum flow ratio is not significant. It offers efficient flow characteristics and is well-suited for a constant flow.
Explanation: The most suitable section of sewer in a separate sewage system is a circular section. It provides hydraulic efficiency and is well-suited for constant flows.
Explanation: An egg-shaped section is suitable for both combined and separate sewage systems. It combines stability and self-cleansing characteristics.
Explanation: The trunk and outfall type of sewer usually has a horse-shoe shape. This shape provides stability and efficient flow in large sewer conduits.
Explanation: A circular section of sewer has the advantages of having the least perimeter for a given area, offering the least opportunities for deposits, and being more suitable when the discharge is approximately constant.
Explanation: A circular section for a sewer is preferred only up to a diameter of 30 cm. Beyond this diameter, other shapes may be more practical and cost-effective.
Explanation: An egg-shaped section of sewer is chosen because it provides self-cleansing velocity at low discharge rates. It is economical and stable, making it suitable for various flow conditions.
Explanation: In an egg-shaped sewer section, the maximum discharge occurs when the depth of flow is approximately 0.95 times the total depth (d).
Explanation: When more than two sewers join in a manhole, their tops should be at the same level for proper flow conditions and maintenance access.
Explanation: For separate and partially separate systems, the suitable pattern of collection is the perpendicular pattern. This involves the collection of sewage in a perpendicular manner from various lateral sewers.
Explanation: The pattern of sanitation most suitable for a sloppy area is the zone pattern. This involves dividing the area into zones for effective sewage collection and transport.
Explanation: Sewer pipes carry sewage as gravity conduits, should resist wear and tear due to abrasion, and are designed for generating self-cleaning velocities at different discharge rates.
Explanation: The minimum diameter of a sewer pipe is typically considered to be 15 cm. This ensures that the pipe has sufficient capacity for the flow of sewage.
Explanation: The maximum diameter of a sewer pipe should preferably be 300 cm. Beyond this diameter, other considerations may come into play, and alternative solutions may be explored.
Explanation: The self-cleaning velocity normally adopted for a sewer is less than 1 m/sec. This ensures that the sewage flow is sufficient to prevent deposition of solids within the sewer.
Explanation: The ratio of the maximum to average sewage flow for mains up to 1 m in diameter is usually 2.0. This ratio helps in designing the sewer to accommodate peak flows.
Explanation: The gradient to be provided for sewers depends upon various factors, including the diameter of the sewer, the discharge, and the material of the sewer pipe.
Explanation: The gradient of a sewer is given in the direction of the natural slope of the ground. This helps in achieving proper drainage and flow within the sewer.
Explanation: As the diameter of the sewer increases, the self-cleaning velocity decreases. Larger sewers require lower velocities to maintain self-cleaning characteristics.
Explanation: For a 150mm diameter sewer, the gradient required to generate self-cleaning velocity is typically 1 in 100.
Explanation: When the limiting non-scouring velocity is 5 m/sec, the type of sewer generally used is a glazed brick sewer. This type of sewer can withstand higher velocities without scouring.
Explanation: The highest non-scouring velocity in a sewer may be allowed in a glazed brick sewer. Glazed brick sewers have a smooth surface that resists scouring.
Explanation: Non-scouring velocity in a concrete sewer is typically caused by a velocity range of 2.5 to 3.5 m/sec.
Explanation: The design discharge for the separate sewer system is taken equal to 6 times the dry weather flow. This accounts for peak flows and ensures adequate capacity in the sewer system.
Explanation: The design discharge for the combined system is taken equal to rainfall + 2× dry weather flow. This accounts for both the direct rainfall and the dry weather flow in the sewer system.
Explanation: The velocity of flow in a sewer does not depend on the length of the sewer. It depends on factors such as the grade of the sewer, hydraulic mean depth, and roughness of the sewer.
Explanation: Where it is not possible to obtain self-cleansing velocities for sewers, flush tanks are provided with the minimum available head of 5-7 m. This head is used to flush the sewer and prevent deposition of solids.
Explanation: In Chezy’s formula v=c√ms, the Chezy’s constant (c) depends upon the size of the sewer, shape of the sewer, and roughness of the sewer.
Explanation: In a circular sewer, if the depth of flow is 0.2 times the full depth, the nominal gradient is doubled to ensure adequate flow velocity.
Explanation: If D is the diameter of the upper circular portion of a standard egg-shaped section, the overall depth is 1.5D.
Explanation: Manholes on sewer lines are provided for periodic cleaning, providing air for oxidation, and removal of part of sewerage. They serve multiple purposes in the sewer system.
Explanation: A manhole is generally provided at each bend in a sewer line. This facilitates inspection, cleaning, and maintenance of the sewer system.
Explanation: The main function of a manhole is the cleaning of the sewer. It provides access for maintenance activities, including cleaning and inspection.
Explanation: The working chamber of a manhole, along the direction of flow, should have a minimum length of 1.2 m for a depth more than 0.8 m. This ensures sufficient space for maintenance activities.
Explanation: A manhole of such depth that an access shaft is required in addition to the working chamber is called a deep manhole. This is typically deeper than the standard manhole and may require additional access for maintenance.
Explanation: A manhole is said to be shallow if its depth is less than 0.7-0.9 m. Shallow manholes are relatively shallower than standard manholes.
Explanation: A manhole is said to be medium if its depth is between 0.9-1.5 m. Medium manholes fall within this depth range.
Explanation: A manhole is said to be deep if its depth is more than 1.5 m. Deep manholes are deeper than standard manholes and may require additional access.
Explanation: An inspection arm is provided in a drop manhole. This feature facilitates inspection and maintenance of the sewer system.
Explanation: When the fall in elevation is greater than 60 cm, the manhole provided is called a drop manhole. Drop manholes are used to accommodate the steep change in elevation in the sewer line.
Explanation: Drop manholes are typically provided on sewers in hilly towns where there is a significant change in elevation. They help manage the steep slopes and provide access for maintenance.
Explanation: Before entering a manhole, a candle is lowered into the manhole to detect toxic gases. If the flame extinguishes or behaves abnormally, it indicates the presence of harmful gases.
Explanation: A lamp hole is helpful in illuminating the sewer line. It provides light for better visibility and inspection of the sewer.
Explanation: A cleanout is a structure constructed to remove obstacles in the sewer. It provides access for cleaning and removing debris from the sewer line.
Explanation: Flush air inlets are sometimes called ventilated lamp holes. They serve to allow air into the sewer system and prevent siphonage.
Explanation: A flushing tank is a structure constructed where self-cleaning velocity is not developed to prevent choking. It helps in flushing the sewer line to remove deposits.
Explanation: The capacity of a flushing cistern for water closets is typically in the range of 10-15 liters. This provides sufficient water for effective flushing.
Explanation: The minimum height of a flushing cistern is typically around 2 meters. This height allows for effective flushing of the water closet.
Explanation: The object of a cowl is to prevent nest building. It is a protective cover that helps keep birds and other animals from building nests in the sewer vent pipes.
Explanation: Treatment of sewage for small estates and colonies is often done by oxidation ditch systems. These systems use aerobic bacteria action for sewage treatment.
Explanation: Sewage is treated by aerobic bacteria action in oxidation ponds. These ponds facilitate the natural treatment of sewage through biological processes.
Explanation: The gases given out of the septic tank include carbon dioxide (CO2), hydrogen sulfide (H2S), and methane.
Explanation: The gas most commonly associated with septic wastewater is hydrogen sulfide (H2S). It is known for its foul smell.
Explanation: From the septic tank, the effluents are discharged into a soak pit. The soak pit allows for further filtration and absorption of the treated effluents into the soil.
Explanation: The detention time in a septic tank is typically in the range of 22 to 24 hours. This allows sufficient time for the process of sedimentation and anaerobic digestion of organic matter.
Explanation: A septic tank is a watertight tank where sedimentation and anaerobic digestion of organic matter take place. The tank is designed to separate solids from wastewater and facilitate the decomposition of organic matter by anaerobic bacteria.
Explanation: Septic tanks are best suited for scattered residences, particularly in areas where centralized sewage treatment may not be feasible. They provide on-site treatment of sewage for individual households.
Explanation: Septic tank effluent typically contains fine organic solids with a high Biochemical Oxygen Demand (BOD). It is not clear and sparkling, and it requires further treatment before being discharged.
Explanation: The inlet and outlet pipes of the septic tank are bent downward. This design helps prevent the disturbance of settled solids and scum during the inflow and outflow of wastewater.
Explanation: The detention time for the detritus tank is typically in the range of 3 to 4 minutes. This short detention time allows for the settling of heavier particles.
Explanation: Ecosanitation is a type of sanitation in which urine and solid waste are separated. It involves the separate collection and treatment of urine and feces to achieve sustainable and resource-efficient sanitation.
Explanation: Grit is inert matter with a specific gravity greater than 2.65. It typically consists of sand, gravel, or other heavy particles that settle in wastewater treatment processes.
Explanation: A grit chamber has a relatively short detention period, typically in the range of 45 seconds to 90 seconds. This allows for the settling of grit before the wastewater continues its flow.
Explanation: The velocity of flow through a grit chamber is typically in the range of 15 to 45 cm/sec. This velocity helps in the settling of heavier particles.
Explanation: Grit obtained in a grit chamber, often composed of sand and other heavy particles, can be used as a substitute for sand in construction activities.
Explanation: ‘Mass action’ during sedimentation refers to the settling of a particle along with the neighboring particle. This property contributes to the formation of floc and settling in sedimentation tanks.
Explanation: The main differences between a septic tank and an Imhoff tank are that in an Imhoff tank, digestion takes place in a separate compartment, and it is suitable for serving a larger population.
Explanation: The working conditions in Imhoff tanks involve anaerobic digestion in the lower compartment and aerobic conditions in the upper compartment. This allows for the separation and treatment of sludge and effluent.
Explanation: An Imhoff tank is a two-storey sedimentation tank. It consists of an upper compartment for sedimentation and an lower compartment for anaerobic digestion of sludge.
Explanation: Clarigesters are circular imhoff double storage tanks without bottom hoppers. These tanks are designed for the separation and treatment of sewage, with an upper clarifying compartment and a lower sludge digestion compartment.
Explanation: Digesters are used for the anaerobic digestion of sludge under optimum conditions. This process helps in the stabilization and reduction of organic matter in the sludge.
Explanation: Salvaging refers to the extraction of valuable or essential components from waste materials, contributing to recycling and resource recovery.
Explanation: The pipe used to carry discharge from sanitary fittings like bathrooms and kitchens is called the waste pipe. It conveys wastewater to the sewage system.
Explanation: During the water test of a sewer, an allowance of 2 liters per centimeter of diameter per kilometer of sewer line may be allowed for a period of 30 minutes. This test checks for leakages in the sewer system.
Explanation: The smoke test is a common method for testing house sewers. It involves introducing smoke into the sewer system to detect any leaks or openings in the pipes.
Explanation: The odd statement is “sewage is received in a wet well” because wet wells are typically associated with pump stations in wastewater systems, not with the reception of raw sewage.
Explanation: The three cycles of decomposition of sewage are the carbon cycle, sulfur cycle, and nitrogen cycle. These cycles involve the transformation of organic and inorganic substances in sewage.
Explanation: An inverted siphon is typically associated with storm sewers. It is designed to carry stormwater or wastewater across a depression or obstacle using a pipe that is lower in the middle than at the ends.
Explanation: An inverted siphon is made of three pipes. This configuration allows the conveyance of wastewater or stormwater across a low point while preventing siphonic action and maintaining flow.
Explanation: An inverted siphon is referred to as both a depressed sewer and a sag sewer. It is designed to allow the conveyance of flow through a depressed section or sag without creating a siphoning effect.
Explanation: A garbage dumping home is a place where garbage is kept temporarily before being further processed or disposed of. It is not necessarily the final disposal site.
Explanation: The standard Biological Oxygen Demand (BOD) at 20°C is expressed in terms of the oxygen consumed over a 5-day period. This parameter is commonly used to assess the organic strength of wastewater.
Explanation: Letache refers to the settling and compaction of waste in a landfill. It is observed in landfill sites where solid waste undergoes natural processes of degradation and compaction over time.
Explanation: All of the abbreviations are correct
Explanation: During the decomposition of sewage, various gases are produced. Methane is the predominant gas, constituting around 65 to 70% of the gases produced. Carbon dioxide (CO2) is also generated, comprising about 30% of the gases. Nitrogen is present in smaller quantities, around 0.05%. Therefore, all the options (methane, CO2, and nitrogen) are correct.
Explanation: The capacity of Guheswari Sewage Treatment Plant (STP) is 12.1 Mld (Million Liters per Day). STPs are designed to treat and process sewage and wastewater.
Explanation: In the one-pipe system of plumbing, there are two vertical pipes. This system is a type of plumbing configuration used in buildings for the drainage of wastewater.
Explanation: In the two-pipe system of plumbing, there are four vertical pipes. This system is used for the separate conveyance of soil and waste pipes in plumbing installations.
Explanation: In the single-stack system of plumbing, there is one vertical pipe. This system is commonly used in buildings for the drainage of both soil and waste.
Explanation: In the partially ventilated single-stack system of plumbing, there are two vertical pipes. This system allows for separate ventilation of soil and waste pipes.
Explanation: A Nahni trap is typically made of cast iron. It is a type of trap used in plumbing to prevent foul gases from entering the building while allowing the flow of wastewater.
Explanation: The color of septic sewage is often described as blue. This color may result from the presence of certain chemicals or reactions during the decomposition of organic matter.
Explanation: Any trap is intended to trap foul gases with the provision of a water seal. The water seal prevents the entry of foul gases from the sewer into the building by trapping water in the trap.
Explanation: The interception trap is the last trap provided in a house drainage system. It is designed to intercept and prevent the passage of solids and debris while allowing the flow of wastewater.
Explanation: S-Traps have parallel legs. The configuration of the trap resembles the letter “S” with two vertical legs.
Explanation: P-Traps have perpendicular legs. The configuration of the trap resembles the letter “P” with a horizontal inlet and a vertical outlet.
Explanation: Q-Traps have curved legs. The configuration of the trap resembles the letter “Q” with a curved outlet.
Explanation: The BOD (Biochemical Oxygen Demand) of the sewage is calculated based on the oxygen depletion after 5 days of incubation. If the depletion is 5 PPM, then the BOD is calculated as 5% of the initial concentration. Therefore, the BOD of the sewage is 200 PPM (5% of 2.5%).
Explanation: The relative stability of sewage is calculated as the ratio of the remaining stability after incubation to the initial stability. If the period of incubation is 15 days, the relative stability is calculated as (15/15) x 100%, which is 100%.
Explanation: The relative stability is calculated as the ratio of the remaining stability after incubation to the initial stability. If the period of incubation at 37°C is 15 days, the relative stability is (15/15) x 100%, which is 100%. Therefore, the correct answer is 99.9%, as there is a 0.1% reduction in stability.
Explanation: The dilution factor is calculated as the total volume of the diluted sample divided by the volume of the original sample. In this case, the dilution factor is 250 ml / 10 ml = 25.
Explanation: The Biochemical Oxygen Demand (BOD) is calculated as the difference between the initial and final dissolved oxygen concentrations. In this case, BOD = 9 PPM – 4 PPM = 5 PPM. Since the sample is diluted by a factor of 200 ml / 4 ppm = 50, the final BOD is 5 PPM x 50 = 250 PPM.
Explanation: The BOD₅ is calculated as the difference between the initial and final dissolved oxygen concentrations in the diluted sample. BOD₅ = 9 mg/l – 5 mg/l = 4 mg/l.
Explanation: The initial BOD (BOD₀) is calculated as the product of the dilution factor and the BOD₅. BOD₀ = 500 mg/l × (2 ml / 200 ml) = 5 mg/l. Since the D.O. content after 5 days is found to be 5 mg/l, the initial D.O. content of the diluted sample is 5 mg/l × 2 = 10 mg/l.
Explanation: The depth of a shallow tube well, considering economic factors, is typically recommended not to exceed 30 meters.
Explanation: The presence of hydrogen sulfide in water can cause acidity. Hydrogen sulfide is a gas that can dissolve in water and contribute to its acidity.
Explanation: pH is a measure of the acidity or alkalinity of a solution and is a symbol for the concentration of hydrogen ions (H⁺) in the solution.
Explanation: A complete water supply system includes the entire arrangement from the source of water to its distribution to the end-users.
Explanation: Aerobic bacteria are microorganisms that require free oxygen for their survival and growth.
Explanation: GI (Galvanized Iron) pipes are commonly used in house plumbing for conveying water.
Explanation: The diameter of pipes in bathrooms and lavatories in domestic water supply is typically around 12 mm.
Explanation: The designation of GI pipes is based on their internal diameter.
Explanation: The time of concentration for a watershed depends on various factors, including the slope of the catchment, intensity of rainfall, and nature of the soil.
Explanation: Water for domestic consumption should be hygienically safe, ensuring it is free from contaminants and safe for human consumption.
Explanation: The factors to be considered for the source of water supply include the quantity and quality of available water, elevation of the water sources, and the general terrain of the area. All these factors play a crucial role in determining the feasibility and efficiency of a water supply source.
Explanation: The daily per capita water demand is calculated by dividing the total water requirement by the population and then by the number of days in a year. For this city, the calculation would be: (19,710,000 cubic meters / 0.2 million people) / 365 days ≈ 270 liters.
Explanation: The sedimentation process in water treatment is primarily effective in removing suspended solids. It allows these particles to settle down, resulting in clearer water.
Explanation: A sanitary sewer is designed to operate at approximately 2/3 full under normal conditions. This ensures that there is enough capacity to handle peak flows without causing sewer overflows.
Explanation: Harmful bacteria that can cause diseases are commonly referred to as pathogens. These include various disease-causing microorganisms.
Explanation: Physical characteristics of sewage include turbidity (cloudiness), color, and odor. These factors are important indicators of the quality and composition of sewage.
Explanation: The quantity of flushing water required for a pour-flush water seal latrine typically ranges from 3.0 to 4.0 litres.
Explanation: Sewers are designed for the self-cleaning velocity, which is usually associated with the maximum flow conditions. This helps prevent sediment deposition in the sewer.
Explanation: The baffle wall in a septic tank is a honeycomb inner wall that helps in directing the flow and improving the efficiency of the treatment process.
Explanation: A cesspool is an underground structure in the form of a tank that admits sewerage from an intercepting chamber for temporary storage or treatment.
Explanation: A water supply system is considered continuous when it provides water for 24 hours. This ensures uninterrupted access to water for the consumers.
Explanation: The intermittent water supply system has advantages such as the ability to carry out repairs during non-supply hours, reduced chances of water wastage, and the use of a lesser quantity of water.
Explanation: A septic tank is designed for the oxygen-free sedimentation and disposal of sewage under anaerobic conditions. It facilitates the separation and digestion of solids in the absence of oxygen.
Explanation: A break pressure tank in a water supply system is incorporated to release the pressure generated in the pipe. It helps regulate and manage the pressure within the system.
Explanation: High-Density Polyethylene (HDPE) pipes are widely used for rural water supply in Nepal. These pipes are known for their durability and flexibility, making them suitable for various applications in water supply systems.
Explanation: The SODIS method, or Solar Water Disinfection, is a process of using solar energy to disinfect water. It involves exposing water-filled transparent containers to sunlight, which helps in deactivating pathogenic microorganisms.
Explanation: Bir Dhara scheme is the oldest waterworks in Nepal. It has historical significance in providing water supply.
Explanation: A union is a fitting used to join GI pipes coming from both sides. It allows for easy disconnection of pipes for maintenance or repairs.
Explanation: A water security plan is prepared to ensure the quality of water storage and its varied uses for different purposes. It involves strategies for long-term risk minimization and community participation.
Explanation: The term “septic” refers to the anaerobic bacterial environment that develops in a septic tank during the treatment of sewage.
Explanation: Running an induction motor pump under significantly low voltage continually can lead to overheating and damage, eventually causing the motor to burn out.
Explanation: The peak water consumption hours, as recommended by the Department of Water Supply and Sewerage (DWSS), are typically from 5.00-7.00 hours when water demand is high.
Explanation: Slow sand filters are efficient in removing bacteria from raw water, and their effectiveness can be up to 99% in removing bacterial contaminants.
Explanation: Dengue is considered a water-related disease as it is primarily transmitted by Aedes mosquitoes breeding in stagnant water.
Explanation: Alum is the most commonly used coagulant in water treatment processes to promote the aggregation and settling of impurities.
Explanation: Boiling water can remove hardness if it is due to calcium bicarbonate. The heat causes the bicarbonate to decompose, precipitating the hardness minerals.
Explanation: Darcy’s law is the most commonly used non-empirical formula to determine the velocity of the flow of underground water.
Explanation: The minimum water flow in a tap stand is typically 0.25 liters per second (lps) to ensure an adequate supply for users.
Explanation: Manholes in a sewer system should be installed at all intersections, changes in grade, size, and alignment to facilitate maintenance and inspection.
Explanation: The most suitable excreta disposal unit for human excreta is a privy pit, which provides a simple and sanitary means of waste disposal.
Explanation: The flow in sewers is typically minimum during the night when water use is reduced.
Explanation: For a sewer with a diameter of 150 mm, a gradient of 1 in 100 is generally required to generate a self-cleaning velocity.
Explanation: A high-level alarm is a device that warns when the liquid in a system is above the pump level, helping to prevent overflow and potential damage.
Explanation: The sewage in an inverted siphon will flow under pressure conditions. The design of the inverted siphon allows sewage to be transported under an elevated obstacle using pressure.
Explanation: An anti-siphonage pipe is connected to the top of a PWC (Public Water Closet) to prevent backflow and siphonage of contaminated water into the water supply system.