Water Supply Management Quiz

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Questions and Answers

What is the primary factor that dictates the final selection of a water source?

Feasibility studies encompassing all relevant factors (correct)

Environmental impact assessment

Preliminary cost analysis and budget

Water hardness levels.

When considering the use of an existing water supply, what critical aspect must be evaluated when increasing water withdrawal?

The current water hardness levels.

The source's ability to meet needs during drought periods and how increase affects water quality. (correct)

The overall cost of increasing the water withdrawal.

The impact of water quality on nearby wildlife.

In addition to the current needs of a development what factor must an investigation consider if a nearby water system could be used?

The maintenance schedule of the water system.

Future needs of the system and its reliability. (correct)

The system's historical water usage.

The quality of water provided by system.

What is a key consideration when a new development is considering using or expanding an existing water supply?

Comparing the economics of using the existing supply versus other alternatives. Signup and view all the answers

What should be observed when assessing a potential water supply's suitability for treatment?

Guidelines for raw water supply for producing acceptable finished water with conventional treatment. Signup and view all the answers

What should be considered when evaluating alternative water supply sources?

Purchase options, development of ground and surface sources, or both. Signup and view all the answers

Which factors are considered in a feasibility study for water source selection?

Engineering, economic, energy and environmental factors. Signup and view all the answers

Apart from capacity and reliability what else should be investigated thoroughly about existing water supply works for upgrade?

The potential for usage with or without enlargements. Signup and view all the answers

What is the primary purpose of the infiltration index?

To estimate the average loss rate such that excess rainfall equals direct runoff. Signup and view all the answers

Which of the following best describes a 'supply line' in a water supply system?

The pipeline from a water source to a treatment works or distribution system. Signup and view all the answers

What do 'feeder mains' primarily constitute in a water distribution system?

The principal pipelines that supply the distribution network. Signup and view all the answers

In terms of water supply systems, what are 'supply works' primarily associated with?

The development of a source, such as dams and wells. Signup and view all the answers

Which term defines the entire infrastructure required for the collection, treatment, and distribution of water?

Water Works Signup and view all the answers

What does the 'distribution system' primarily consist of?

Pipes and appurtenances for delivering water to users. Signup and view all the answers

What is the 'treatment works' primarily responsible for?

Removing impurities from the raw water source Signup and view all the answers

What does a 'service line' connect in a water distribution system?

A distribution main to a building served. Signup and view all the answers

Which of the following is NOT a primary benefit of well development?

Reducing the need for future well maintenance Signup and view all the answers

In a naturally developed well what is the primary mechanism for creating a highly permeable zone?

Removal of finer materials from the formation by pumping Signup and view all the answers

What is the purpose of artificial filter packing in well development?

To create a highly porous material around the screen Signup and view all the answers

Why is development necessary after drilling using methods that utilize drilling fluids?

To form a mud cake and increase the density of the formation around the hole Signup and view all the answers

What does the 'skin effect' refer to in well development?

The increased density of the formation around the hole caused by drilling Signup and view all the answers

How does mechanical surging aid in well development?

By using a plunger to create rapid water movement in the well Signup and view all the answers

What is the main mechanism of action in air surging for well development?

Injection of air below the water level causing an outward surge of water Signup and view all the answers

What is the limitation of using over-pumping as the sole method of well development?

It seldom brings the best results when used alone Signup and view all the answers

What is a primary factor causing seasonal variations in mineral quality in streams?

Variations in stream flow Signup and view all the answers

Why is strict watershed control often impractical for water supplies from streams?

Control over upstream influences is hard to achieve Signup and view all the answers

What is a key focus of a control and surveillance program for impounding reservoirs?

Protecting the quality of raw water Signup and view all the answers

What should be rigorously controlled at reservoirs used solely for water supply?

Recreational usage of the reservoir and shoreline Signup and view all the answers

What is a critical item to investigate when evaluating surface water resources?

Sanitary survey findings Signup and view all the answers

Besides other factors, surface water sources must meet which requirements for contaminant levels or provide filtration?

Fecal coliform and turbidity Signup and view all the answers

When developing a water supply system, which factor is important in addition to topographic maps and hydrologic data?

Geological data to determine the ability to hold water Signup and view all the answers

What is an important consideration in a surface water investigation regarding legal aspects?

The state water laws, rules, and regulations Signup and view all the answers

What range of inlet velocities is generally recommended to prevent ice clogging of water intakes?

75 mm to 150 mm per second Signup and view all the answers

What is a significant hazard associated with northern lakes that requires specific design considerations for water intakes?

Frazil and anchor ice Signup and view all the answers

Which material is preferred for cold-climate inlet construction due to its effect on ice formation?

Nonferrous materials Signup and view all the answers

What specific structural requirement is crucial for river intakes in areas prone to ice problems?

Resistance to the thrust of ice jams Signup and view all the answers

Besides the thrust of ice jams, what is another important consideration for the opening depth of river intakes in cold climates?

To avoid slush ice Signup and view all the answers

What type of stream presents significant intake problems due to its dynamic nature?

Meandering streams in deep alluviums Signup and view all the answers

What is a common technique used to manage ice issues at some northern lake intakes?

Steam heating Signup and view all the answers

What is the primary function of the intake structure's design considering bed-load deposits?

To prevent clogging Signup and view all the answers

What is the recommended minimum casing size for a well using a 6-inch diameter pump, based on the provided text?

8 inches Signup and view all the answers

Where should a new well be ideally located in relation to the test pumping well (PW) and observation well (W1)?

Close to the test pumping well (PW) and observation well (W1). Signup and view all the answers

What is the primary purpose of adding chlorine to the water, according to the text?

To disinfect the water. Signup and view all the answers

What does 'suction head' refer to in the context of pump selection?

The vertical distance from the ground(pump level) to the lowest water elevation in the well, which in this case, is the top of the screen. Signup and view all the answers

What is the 'discharge head'?

The difference in elevation from the pump to the water level in the storage tank, plus the required pressure. Signup and view all the answers

What elements are considered when calculating the 'friction head'?

Both head loss in the pipe and loss in fittings. Signup and view all the answers

According to the provided document, what is the last step in the design process before choosing specific pumps and motor drives?

Reviewing manufacturer's literature and consulting with their representatives. Signup and view all the answers

What does the 'Total Dynamic Head' (TDH) represent in the context of the text?

The sum of the suction head, discharge head, friction head, and velocity head. Signup and view all the answers

Study Notes

Bong County Technical College Information

Location: Gbarnga City, Bong County
Department: Engineering
Course Title: Water supply and environmental Engineering
Lecturer: Eng. Cooper B. Saysay
Qualifications: BSc, MSc in Civil Engineering
Email: [email protected]
Phone numbers: +231-770-299-886/+231-880-538-294

Hydrology - Sources of Water

Rain water
Surface water
Ground water
Water from reclamation

Water Supply Systems

Primary objective: To take water from the best available source and subject it to processing to ensure good physical quality; free from unpleasant taste, odour and containing nothing detrimental to health. This involves additions to, subtractions from, or chemical changes to raw water.
Units: Collection works, Transmission works, Purification works, and Distribution works (diagrammatic representation in Fig. 1.4)

The Water Cycle

Hydrology: Science dealing with the occurrence, distribution and movement of water on Earth (atmosphere and below the surface)
Water exists: as vapour in the atmosphere, water on the surface, snow or ice on the surface, and ground water filling the voids within a geologic stratum.
Water cycle processes: Evaporation, Transpiration, Precipitation, Run-off

Computation of Average Rainfall

Methods for calculating average precipitation from multiple rain gauge stations in a basin: Arithmetic average, Thiessen polygon, and Isohyetal methods
Arithmetic average method: Simplest method of calculating average rainfall; calculate by summing all recorded rainfall values at various stations and dividing by the total number of recording stations
Thiessen polygon method: More common method of weighting rain gauge observations which is more accurate than the arithmetic average method. Steps:
Connect adjacent rain gauge stations with straight lines.
Construct bisectors of these lines
The polygon formed by these perpendicular bisectors will be closer to the station than to any other
Multiply each area by the rain gauge value
Find the total area
Compute the average precipitation following formula
Isohyetal method: More accurate. Contour lines representing equal amounts of rainfall within an area are drawn through relevant records. Then calculate the area encompassed by each contour line to estimate average rainfall.

Infiltration

Definition: Movement of water through the soil surface to into the soil.
Infiltration capacity: Maximum rate of water entry into the soil.
Infiltration rate: Rate at which water enters the soil.
Infiltration indices: Two types: Average infiltration rate (W-index) & index (k) calculated by using W = (P-R)/t
Calculation for an index of average infiltration rate, W: where P = total rainfall in cm, R = total run-off in cm, and t = duration of run-off in hours.

Chapter 1 - Introduction

Purpose and scope: Introduction to selecting water sources and determining water requirements.
Applicability: Guidelines applicable to the selection of water sources and planning and designing water supply systems.
References: Many professional references available.
Definitions:
Water works: All construction related to the collection, transportation, pumping, treatment, storage, and distribution of water
Supply works: Dams, impounding reservoirs, intake structures, pumping stations, wells.
Supply line: Pipeline extending from the supply source to the treatment works or distribution system.
Treatment works: All basins, filters, buildings and equipment
Distribution system: A network of pipes used to distribute water for domestic, industrial and fire fighting purposes
Feeder mains: The main distribution pipes
Distribution mains: Pipelines which form part of the distribution system
Service line: Pipeline extending to the building served by the distribution system.
Effective population: Number of residents + an allowance for nonresident personnel
Capacity factor: Multiplier applied to effective population to account for population increase, variation in water demand and uncertainties about actual water requirements
Required daily demand: Total daily water requirement, calculated by multiplying design population by appropriate per capita values
Peak domestic demand: The major factor considered for system design; maximum day demand (2.5 the daily required demand) or fire flow plus 50% of daily demand
Fire flow: The required amount of water per minute at a given pressure to battle fire at a specific point.
Fire demand: Required flow rate to fight fires
Rated Capacity: Maximum amount of water that can be passed through the system under given conditions.

Chapter 2 - Water Requirements

Domestic requirements: Illustrative per-capita water allowances provided in Table 2-1.
Fire Flow requirements: The system must be capable of fulfilling the specified fire flow and any other demands that cannot be reduced during a fire period at the required residual pressure and for the required duration.
Irrigation: Allowances include water for limited watering or planted/grassed areas but not major lawn or other irrigation uses.

Chapter 3 - Capacity of Water Supply System

Capacity factors: Table 3-1 presents capacity factors based on different population ranges.
Use of Capacity Factor: Capacity factors are applied in water supply projects.
System design capacity: Design elements of the water supply system will be based on the population's design population

Chapter 4 - Water Supply Sources

General: Water supplies may be obtained from different sources, by expansion of existing systems or by purchase
Use of existing Systems: Determine the existing capacity and reliability to use the system's possible arrangements with or without enlargement.
Other water systems: Investigating water supply systems nearby if the proposed development is near it

Chapter 5 - Ground Water Supplies

General: Ground water: Subsurface water that fills the saturated zone.
Economy: Ground water supplies are often more economical than surface water if the aquifer yield is adequate.
Water Quality Evaluation: Steps involved in determining the quality of available water
Well Hydraulics:
Definitions: Static water level, pumping level, drawdown, cone of depression, radius of influence
Permeability, hydraulic conductivity
Discharge formulas (equations): For water table and artesian wells.
Determination of water values.
Aquifer testing: Methods for determining aquifer characteristics, such as pumping tests.

Chapter 6 - Surface Water Supplies

Surface water sources: Streams, lakes, and impounding reservoirs, generally found in eastern half of the US.

Chapter 7 - Intakes

General: Intake is the structure used for taking water from natural bodies of water.
Capacity and reliability: Intake must have sufficient water and be reliable in all conditions over the expected life.
Ice problems: Ice may clog or damage intake structures.
Intake location: Various considerations, like streams, meandering streams, bends, depth and water quality factors.

Chapter 8 - Raw Water Pumping Facilities

Pumping station arrangements: Arrangement of raw water pumping stations based on local needs and requirements for water.
Pumping protection: Safety considerations regarding the pumping equipment or facilities in flood or debris-prone locations
Structural and ventilation considerations: Pump station building design and ventilation system requirements
Pumping Equipment: Providing of adequate pumping equipment based on water treatment plant and the rated capacity
Ground water sources: Methods considered based on need/application

Chapter 9 - Water System Design Procedure

General: Coordination of water supply system planning, and design in a large project.
Selection of materials and equipment: Appropriate materials and equipment used in the system; prohibition of certain materials.
Restrictions: Lead, copper, and asbestos. Prohibitions on materials.
Energy conservation: Considering energy requirements when deciding on water sources or system design

Appendix (e.g., B) - Sample well design

Site situation/selection
Size the well
Location
Water quality
Pump selection
Construction/additional details

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Description

Test your knowledge on the critical factors involved in selecting and evaluating water sources for development. This quiz covers essential considerations such as feasibility studies, supply line definitions, and treatment suitability. Enhance your understanding of water supply management best practices.