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U N I V E R S I T Y O F N A I R O B I
S C H O O L O F E N G I N E E R I N G
DEPARTMENT OF ENVIRONMENTAL AND BIOSYTEMS ENGINEERING
FEB 540: ENGINEERING DESIGN PROJECTFEB 540: ENGINEERING DESIGN
PROJECT
FEB 540: ENGINEERING DESIGN PROJE
PROJECT TITLE
DESIGN OF A RAW WATER TREATMENT PLANT
CASE STUDY:MOSIABANO DAM NYANSIONGO WARD, BORABU CONSTITUENCY
NAME: NYAKUNDI BRENDA KWAMBOKA
REGISTRATION NUMBER: F21/1978/2013
SUPERVISOR: MR. J.O AGULLO
A design projectsubmitted in partial fulfilment of the requirement for the Award of the
Bachelor of Science Degree in Bio-systems Engineering at the University of Nairobi.
JUNE 2018
i
FEB 540: ENGINEERING DESIGN PROJECT
2017/2018 ACADEMIC YEAR
DECLARATION
I, Nyakundi Brenda Kwamboka, hereby declare that this projectis my original and with
sincerity and to the best of my knowledge, it has not been presented for any degree award at
any other higher institution of learning.
Signature …………………………………………
Date …………………………………………
Nyakundi Brenda Kwamboka
F21/1978/2013
This project report has been submitted for examination with my approval as the supervisor.
Signature………………………………………...
Date ………………………………………..
Mr. J. O Agullo
i
DEDICATION
This research proposal is dedicated to my family especially my father Thomas Nyakundi who
has been a great motivation in my academic journey.
ii
ACKNOWLEDGEMENT
This research study is a result of support from several sources; first I would like to give praise
and honor to the Almighty God for giving me sufficient grace and power to write this project.
I would also like to thank my supervisor Mr. Januarius Agullo whose comments and advice
were very useful to me, my family for the encouragement and moral support as well as to my
friends for their encouragement and support too. May God bless them in every way I say
thank you, they all gave me the motivation that was key to my achievements in writing
thisproposal. Lastly I would like to acknowledge the University of Nairobi for the good and
conducive learning environment during my study period, as well as the resources from the
library. Thanks a lot and God bless you.
iii
ABSTRACT
Water is a very intergral part in our daily life. It’s, dubiously a basic human need. Providing
safe and adequate quantities of the same for all remains an important undertaking throughout
the world as outlined in the Sustainable Development Goal No 6. This is equally echoed in
the Kenya Vision 2030 plan that drives the country towards political, economic and social
positive steering of the economy. This project involves the design of a gravity water supply
system.
The overall objective of this project was to design a raw water treatment system for
Mosiabano dam, at Nyansiongo Ward in Nyamira County. The specific objectives of the
study were to: Determine the water utilization/demand in the area, to evaluate the raw water
quality tests from Mosiabano Dam and to design the specifications for Mosiabano dam raw
water treatment works and related components.
The water quality tests were performed at the University of Nairobi’s civil Engineering
laboratory so as to achieve the World Health Organisation requirements. The design of the
major components of the treatment plant, mainly flocculation, sedimentation, filtration and
water storage tanks were based on design criteria (and parameters) that are recommended for
design of water treatment plants to ensure that the plants would function effectively. The
design considerations wereon dimensioning of the tanks ratios as per certain ranges to allow
for effective water treatment. Other considerations that were considered are: retention time
within the tanks and surface loading rates.
It was important to design a plant capacity that will satisfy the water demand of the
population therefore population studies were important in the design. This includes the
households, their animals as well as infrastructural facilities such as schools and hospitals.
The presence of a safe and reliable source of water is thus an essential prerequisite for the
establishment of a stable community. The presence of safe and reliable source of water is
necessary for the people of Nyansiongo and everyone.
The outcome of the projectwas determined as successful at the end of the project. They
include the design a raw water treatment system that will supply safe and clean water that
meets the demand of people in Nyansiongo Town in Nyansiongo Ward, Borabu Constituency
as well as determine the amount of water demand in the region, perform water quality tests
on the water and also determine the specifications for the raw water treatment works and
related components. There was need for an AutoCAD design for the water treatment works.
iv
TABLES OF CONTENTS
DECLARATION..............................................................................................................................i
DEDICATION.................................................................................................................................ii
ACKNOWLEDGEMENT..............................................................................................................iii
ABSTRACT...................................................................................................................................iv
TABLES OF CONTENTS..............................................................................................................v
LIST OF TABLES AND FIGURES............................................................................................viii
LIST OF ABBREVIATIONS.........................................................................................................ix
CHAPTER 1....................................................................................................................................1
INTRODUCTION...........................................................................................................................1
1.1 Introduction..........................................................................................................................1
1.2 Problem Statement...............................................................................................................2
1.2.1The Concept.............................................................................................................................2
1.2.2 Situational Analysis................................................................................................................3
1.2.3 Site Analysis...........................................................................................................................4
1.3 Justification................................................................................................................................5
1.4 Objectives..................................................................................................................................5
1.4.1 General Objectives..................................................................................................................5
1.4.2 Specific Objectives.................................................................................................................5
1.5 Project Scope.............................................................................................................................6
CHAPTER 2....................................................................................................................................7
LITERATURE REVIEW................................................................................................................7
2.1 Water sources.............................................................................................................................7
2.1.1 Ground water sources.............................................................................................................7
2.1.2 Surface water sources.............................................................................................................8
2.2 Raw Water Treatment................................................................................................................8
2.2.1 Screening................................................................................................................................9
2.2.2 Aeration..................................................................................................................................9
2.2.3 Coagulation...........................................................................................................................10
2.2.4 Flocculation..........................................................................................................................10
2.2.6 Filtration................................................................................................................................15
2.2.7 Disinfection...........................................................................................................................16
2.2.9 Corrosion control..................................................................................................................19
2.2.10 Storage................................................................................................................................19
2.3 Factors Influencing the Water Supply Capacity......................................................................20
v
2.3.1 Design period........................................................................................................................20
2.3.2 Population Projection............................................................................................................20
2.3.3 Water Demand......................................................................................................................21
2.4 Generation of Concept Design.................................................................................................24
CHAPTER 3..................................................................................................................................25
THEORETICAL CONSIDERATIONS........................................................................................25
3.1 Population Data........................................................................................................................25
3.2.1 Human Population................................................................................................................25
3.2 Water Quality Samples............................................................................................................25
3.3 Design of Water Supply Facilities...........................................................................................26
3.3.1 Water Supply Intake Structure..............................................................................................26
CHAPTER 4..................................................................................................................................29
MATERIALS AND METHODS...................................................................................................29
4.1 Introduction..............................................................................................................................29
4.2 Data collection methods...........................................................................................................29
4.2.1 Questionnaires......................................................................................................................30
4.2.2 Interviews..............................................................................................................................30
4.2.3 Government Agencies...........................................................................................................30
4.2.4 Direct Observation................................................................................................................30
4.2.5 Sample..................................................................................................................................31
4.3 Data Analysis Methods............................................................................................................31
CHAPTER FIVE...........................................................................................................................32
RESULTS AND ANALYSIS........................................................................................................32
5.1 Population Data........................................................................................................................32
5.2 Field Investigation and Data Collection..................................................................................33
5:2:1 Raw Water Quality Sampling...............................................................................................33
5.2.2 Samples Testing....................................................................................................................33
5.3 Design of water Supply Features.............................................................................................37
5.3.1 Main pipe:.............................................................................................................................37
5.3.2 Flocculation..........................................................................................................................39
5.3.3 Sedimentation Tank..............................................................................................................40
5.3.3 Filtration Tank......................................................................................................................41
5.3.4 Chlorination Tank.................................................................................................................44
5.3.5 Storage Tank Capacity..........................................................................................................44
CHAPTER 6..................................................................................................................................46
DISCUSSION................................................................................................................................46
CHAPTER 7..................................................................................................................................47
vi
CONCLUSIONS AND RECOMMENDATIONS........................................................................47
7.1 Achievement of Objectives......................................................................................................47
7.2 Conclusions..............................................................................................................................47
7.3 Recommendations....................................................................................................................47
7.4 Challenges of Study.................................................................................................................48
REFERENCES..............................................................................................................................49
APPENDIX 1....................................................................................................................................i
Operational Definition of Terms......................................................................................................i
APPENDIX 2.................................................................................................................................. ii
A Map of the Nyansiongo Area.......................................................................................................ii
APPENDIX 3................................................................................................................................. iii
APPENDIX 4..................................................................................................................................iv
Sample I Raw water Test Results (Physiochemical analysis)........................................................iv
APPENDIX 5...................................................................................................................................v
Sample I Raw water Test Results (Bacteriology analysis)..............................................................v
APPENDIX 6..................................................................................................................................vi
Sample I Raw water Test Results (Physiochemical analysis)........................................................vi
APPENDIX 7................................................................................................................................vii
Sample I Raw water Test Results (Bacteriology analysis)............................................................vii
APPENDIX 8...............................................................................................................................viii
Sample III Raw Water Test Sample Results (physiochemical analysis)......................................viii
APPENDIX 9..................................................................................................................................ix
Sample III Raw Water Test Sample Results (Bacteriology analysis)............................................ix
APPENDIX 10................................................................................................................................xi
Budget and Workplan.....................................................................................................................xi
vii
LIST OF TABLES AND FIGURES
Figure 1: the amount of time it takes to fetch water (Nyamira-County, 2015)..........................4
Figure 2: Sketches of Raw Water Treatment Plant Process (Vasna, 2015)..............................9
Figure 3: Types of Flocculation and merits (Muya, 2005)......................................................12
Figure 4: Sedimentation tanks: Types, design criteria, Merits and Demerits.........................15
Figure 5: Backwash rates in relation to effective grain size...................................................16
Figure 6: population in the Nyansiongo Area.........................................................................31
Figure 7: physiochemical analysis of Sample 1.......................................................................32
Figure 8: Bacteriology analysis of sample 1...........................................................................32
Figure 9: Physiochemical analysis of sample II......................................................................33
Figure 10: Bacteriology analysis of sample II.........................................................................34
Figure 11: Physiochemical analysis of Sample III..................................................................35
Figure 12: Bacteriology analysis of Sample III.......................................................................35
viii
LIST OF ABBREVIATIONS
SDGs Sustainable Development Goals
UN United Nations
WHO
LVSWSB
World Health Organization
Lake Victoria South Water Services Board
ix
CHAPTER 1
INTRODUCTION
1.1 Introduction
Water is a basic need for humans and nature. The water sources can be classified as improved
or unimproved based on its quality. Improved water sources refer to those that are less prone
to contamination including boreholes, piped water, protected wells as well as harvested rain
water. Unimproved water sources are those that are prone to contamination, they include:
dams, lakes, djabia (traditional rainwater storage), unprotected wells, unprotected springs,
ponds water from rivers or streams, water vendors and other sources.
Raw water is water in its natural state or untreated water; it consists water from the
ground, infiltration wells water, and water from lakes and rivers, generally, water from
unimproved sources. Without treatment, raw water can be used for farming, construction or
cleaning purposes but not for domestic purposes such as drinking and cooking. In designing
the raw water treatment plant, factors such as the plant downtime, maintenance costs and if
the product (water) is fit for use have to be taken into account.
Sustainable Development Goal (SDGs) 6 is to ensure access to water and clean sanitation to
the entire population by 2030, the proportion of people in the world without access to
sustainable safe drinking water and basic sanitation is halved as agreed during 25 to 27
September 2015 New York Summit. In order to do this, it is necessary to provide access to
safe drinking water. This can be done through design and construction of various water
supply/distribution systems in the urban and rural areas, which deliver water safely free from
contamination e.g. piped water (AMCW, 2015).
In Kenya Vision 2030 under the social pillar, improved access to safe water and sanitation is
one of the priority targets. The 2030 vision for water and sanitation is to ensure that improved
water and sanitation are available and accessible to all. The goal for 2012 is to increase both
access to safe water and sanitation in both rural and urban areas beyond present levels. The
United Nations Human Settlement Programme (UN-Habitat) defines adequate water supply
as ‘a supply of water that is safe, sufficient, regular, convenient and available at an affordable
price. This design proposal targets to achieve the Kenya Vision 2030 goal which includes
improving water supply to citizens (WHO, 2016).
According to Kenya National Bureau of Statistics, 53% of the water sources in Kenya are
improved while 47 % is unimproved sources. The figures however indicate that in rural areas,
1
only 44% of the water sources are improved, 56% are unimproved, meaning, more people in
rural areas use water from unprotected sources. Nyansiongo Town, situated in Nyansiongo
Ward, Borabu Sub-County and Nyamira County is an upcoming market center. This has led
to mushrooming of people into the region as it has administrative roles as it is the
headquarters of the Borabu Sub-county. There is a thirsty demand for clean water services
since there is no piped water in the region as people depend on harvested rain water as well as
untreated sprigs for domestic use. This poses a health hazard as the people get prone to water-
borne diseases such as Typhoid(AMCW, 2015).
A raw water treatment system is a made up of several individual technologies that address
your specific raw water treatment needs. Treating raw water is rarely a static process, and a
raw water treatment system that is engineered to accommodate fluctuations in treatment
needs will go a long way in avoiding costly replacements/upgrades down the line.
A raw water treatment system should be efficient and well-designed to handle the seasonal
variations in turbidity and flow such as during the long rains and short rains, variations in
water chemistry needs and required chemical volumes adjustments. The system depends on
the quality of water being drawn from in relation to the quality of water needed, but in
general, a basic raw water treatment system typically includes some type of chemical feed to
help facilitate the flocculation or coagulation of any unsuspended solids, clarifier to settle out
the larger solids, filtration to remove the smaller particles and a control panel (depending on
the level of automated operation needed). Depending on the needs of your plant and process,
these standard components are usually adequate, however, if your plant requires a system that
provides a bit more customization, there might be some features or technologies you will
need to add on
1.2 Problem Statement
1.2.1The Concept
Monitoring Programme’s 2012 report, access to safe water supplies throughout Kenya is 59%
and access to improved sanitation is 32%. There is still an unmet need in rural and urban
areas for both water and sanitation. In a bid to counter problems like rural to urban migration,
social amenities including access to clean, and safe tap drinking water should provide to rural
areas too. However over the past years, Nyansiongo Town has grown immensely in
population. This has brought up the need for better infrastructure and social amenities like
schools, hospitals and market centres to cater for the large population (WHO, 2016).
2
The water supply in the area needs to be upgraded to meet the ever increasing demand from
both the domestic and industrial use. The area is currently supplied with water from streams
and also through rain harvesting. This presents a challenge because the underground water is
not adequately treated to meet the required WHO drinking water standards. The water from
the streams is majorly from un-improved sources which makes it more prone to pollution
from the rainwater and so it does not meet the recommended Drinking Water Quality
Standards for Kenya. This poses as a health risk to the users. There was therefore need to
source out another water source that would be reliable and provide safe water for
consumption (WHO, 2016).
1.2.2 Situational Analysis
Nyamira County is generally not a water scarce country, as it is located on the Kisii
Highlands with a fair Distribution of rainfall throughout the year. The county has 7
permanent rivers, 1,945 shallow wells, over 3,301 unprotected springs, 2,521 protected
springs and 694 dams. In 2009, 4403 households which reflects just 3.4% had access to
portable water as per the Population and House Census. Approximately, the nearest water
points are located within 0-4km from the households. Mostly it’s the women and girls who
fetch water from streams and water points denying them an opportunity to engage in more
constructive economic activities such as studying. Only 3.4% of the people have access to
piped water, on average, 7.8 % of households take approximately 1min-4min to fetch water,
5-14 minutes is taken by 2.4%, almost half the population(49.2%) take between 15-29 min,
30.5% of the population take 30-59 minutes while 13.4% take more than an hour to fetch
water. This majorly happens during the drier months moreso to the people who stay up the
hilly considering the terrain in Kisii land (Nyamira-County, 2015).
In-order to enhance progress in other sectors, it’s critical to improve and protect the county
water sources. It’s important to equally improve the agricultural subsector to stop over
relying on rain-fed agriculture by harnessing water hence increasing land under irrigation.
Primarily, the region depends on its natural base. Increasing access to sustainable water is a
priority of the government within the existing policy framework. Some of the main
challenges facing improvement of access to water resources include: inadequate funds, the
planting of blue gum trees at riverbanks and springs and lack of local ownership for the
projects.
3
There has been concerns about water in Nyamira County, a move that has facilitated the
building of Itibo dam at 5Billion Kenyan shillings so as to supply water for the people at
Nyamira Town though this cuts out other developing towns such as Nyansiongo (Ongwae,
2017). This happened at the awaken of the longer droughts experienced with fewer rains due
to climate change across the country. The Lake Victoria South Water Services Board
(LVSWSB) has noted out several wetlands for improvement that shall lead to proper
increased water generations and therefore NB: only 3.4% of the population have access to
piped water.
Time taken to fetch water (minutes) 1-4 5-14 15-29 30-59 Over 60
Population percentage 7.8 2.2 49.3 30.5 13.4
NB: only 3.4% of the population have access to piped water.
Figure 1: the amount of time it takes to fetch water(Nyamira-County, 2015)
1.2.3 Site Analysis
Location
Nyamira County one of the forty seven counties in Kenya located in the western side of
Kenya. It has three major towns which include, Nyansiongo, Nyamira and
Keroka.Nyansiongo town is located along the Kisii-Nairobi Highway and it serves many
purposes amongst, administrative unit as it is theheadquarters of the Borabu Subcounty and
Borabu District, as well as hosting Nyansiongo Tea Factory. It stands at an altitude of 1500
meters ASL and has a warm moderate climate. Its coordinates are 35 0.9’ East and 0 0.45’
South (226201.9 Easting, 3877156.7 Northings).The region equally has one permanent river,
Kijauri River-that is all seasoned and some other streams. The water from Mosiabano dam is
used by the Nyansiongo Tea Factory for cleaning purposes now that tea processing is majorly
a dry process.
Soil conditions
The soil in the area is mainly red acidic volcanic soils (Nitosols)which are deep, fertile and
well drained; that are good for agriculture but expensive when it comes to road construction
and maintenance.From reconnaissance survey, it’s swampy in the area along Mosiabano dam
and so the soils around the dam are clay soils, (Nyamira County Annual Development Plan
2014/2015, 2015)
4
Climate
Nyansiongo receives on average 1200mm - 2100mm of rainfall per annum. The region has no
distinct dry spell separating the long and short rains that start in December to June and July to
November respectively. The average normal temperature is 19.40, which is an average of
maxima and minima of 28.70C during the day and 10.10C at night, which isfavorable for both
agricultural and animal farming.The temperature averages 16.1 °C, (Nyamira County Annual
Development Plan 2014/2015, 2015).
Site Conditions
From the assessment of the area during the reconnaissance survey, it was found out that the
road leading to the dam is a murram road. Roads are of importance in ensuring smooth flow
of farm inputs, farm produce of the farmers and the management of the Mosiabano Dam.
The land where the dam is located is owned by the Kenyan Government. Most of the land use
in the area is farming. There are residential places around as well as the Tea Factory that
majorly uses the water for the dam for cleaning purposes.The main economic activities of the
neighboring community is farming. There is equally a tea Factory, and administrative units a
few meters from the dam, a region that has grown from just being a market centre, to the
headquarters of Borabu Distric and Borabu Sub County. Despite these eminent positive
reflections of the town and rise in status to a District, this town has no comprehensive raw
water treatment, distribution, and sewerage connection or sewer treatment plant so far.
1.3 Justification
The main water sources of Nyansiongo town are springs rainwater harvesting which are not
sustainable throughout the year. Mosiabano dam, located at the outskirts of Nyansiongo
Town, is a probable source of water to its neighborhood but it’s not safe for consumption due
to its untreated nature and lack of a treatment plant. If the raw water treatment system is
done, then water distribution system design is done, there will be improved health, improved
quality water for domestic use, improved time spent in studies and other economic benefiting
activities in the region and beyond among the residents of Nyansiongo Town. The treatment
works will be sited in a place such that it will be at a higher region therefore supplying water
by gravity to the area of demand. This will eliminate the need for the extra cost of pumping
of water to the region. It shall also help the country in realization of a part of Vision 2030 as
well as the Sustainable Development Goals.
5
1.4 Objectives
1.4.1 General Objectives
The overall objective of this project will be to design a raw water treatment system at
Mosiabano dam, at Nyansiongo Ward in Nyamira County.
1.4.2 Specific Objectives
The specific objectives of the study are to:
1. Determine the water utilization/demand in Nyansiongo area.
2. Evaluate raw water quality from Mosiabano Dam.
3. Determine the specifications for Mosiabano dam raw water treatment works and
related components
1.5 Project Scope
This project will mainly deal with design of the raw water intake pipes and treatment process,
which includes planning, designing and construction, but the ‘project is limited to the design
of the raw water treatment plant at Mosiabano dam in Nyansiongo Ward, Borabu
Constituency, Nyamira County. The project will determine the actual water demand of the
Nyansiongo Town, size of the raw pipes from the reservoir to intake treatment works, test on
the quality of water from Mosiabano Dam, design of a raw water treatment works as well as
drawing of the treatment works with AUTOCAD.
6
CHAPTER 2
LITERATURE REVIEW
2.1 Water sources
All sources of freshwater always originate from rainfall. Rainfall is slightly acidic due to
dissolution of carbon dioxide in the atmosphere. As surface run off, it gathers considerable
amounts of soil particles mineral matters and organic matter, microorganisms, etc. When
surface runoff infiltrates into subsoil level it forms ground water. As the ground level water
increases due to varying land formations, it oozes out as springs. Perennial springs are the
fountain heads of surface water bodies such as streams, rivers and lakes. Therefore, water can
broadly be classified into two, ground water and surface water
2.1.1 Ground water sources
These are the sources that tap their water from ground aquifers in the underground rocks or
strata. The aquifers are water yielding rocks normally in between two impervious rocks or an
impervious and pervious rock. The aquifers are actually water reservoirs which retain water
that has trickled through the pervious or impervious rocks formation commonly termed as
water table.
Water tables that are formed in between impervious rocks are in most cases deep and are
permanent water sources while those that form between pervious and impervious rocks are
shallow and are seasonal water suppliers. The ground water sources include:
Springs
Springs are naturally occurring water source that emerge from the ground. They mainly occur
in hilly, mountainous areas and river valleys. The two types of springs include:
a.) Gravity springs: Occur where ground water emerges at the surface because an impervious
layer prevents it from seeping downwards. This happened when an unconfined aquifer
emerges into the open. It occurs on sloping ground. The flow depends on the water table.
b.) Artesian springs: Occurs where ground water emerges at the surface after confinement.
The flow is very nearly constant.
Wells
Water well is an excavation created in the ground to access water in the aquifers. They
greatly vary in depth depending on the water table. The diameter of such excavations
determines whether it is a borehole or a well; wells have larger diameters than boreholes. It
7
can be excavated by digging, driving, boring or drilling to the water table. The wells can
either be:
a.) Shallow wells: Manual digging can be used to excavate wells to reach the aquifer. Their
diameters are large enough to accommodate well diggers with their tools. They can be dug up
to a depth of 20-30m usually in loose soils by hand.
b.) Deep wells: These are normally excavated by drilling or by driving methods. The depth
normally ranges from 6 -180m deep depending on the level of the water table.
2.1.2 Surface water sources
Surface water refers to from the lakes, reservoirs, rivers and streams. These water bodies are
formed of water from direct rain, runoffs, and springs. A runoff is the part of rain water that
does not infiltrate the ground or evaporate. It flows by gravity into the water body from the
surrounding land. The total land area that contributes surface runoff to a river or lake is called
a watershed, drainage basin, or catchment area.
The volume of water available for municipal supply depends mostly on the amount of
rainfall. It also depends on the size of the watershed, the slope of the ground, the type of soil
and vegetation, and the type of land use.
The surface water sources are easily susceptible to contamination due to careless human’s
behavior of littering, contamination by animals as well as environmental effects such as
winds that blow up dirt onto the surfaces and flash floods. That’s why it’s very important to
treat the water from surface sources so that they can be deem fit for use by the human beings.
2.2 Raw Water Treatment.
Natural surface waters contain inorganic and organic particles. Inorganic particles such as
clay, silt, and mineral oxides, typically enter surface water by natural erosion processes.
Organic particles may include viruses, bacteria, algae, protozoan cysts and oocyst, as well as
detritus litter that have fallen into the water source. Conventional water treatment is a multi-
phased process. The phases consist of raw water intake, optional pretreatment, flash mixing,
coagulation, flocculation, sedimentation, filtration, disinfection, corrosion control, and
laboratory analysis. These phases are common to all conventional treatment facilities.
8
Figure 2: Sketches of Raw Water Treatment Plant Process(Vasna, 2015)
2.2.1 Screening
Floating debris such as woods, leaves, aquatic plants and others are screened at the intake.
After screening, the denser suspended matters are removed by allowing water to pass through
chamber where it settles down to the bottom. The basin screens out large debris and settles
out sand and silt. Surface water will initially pass through screens to ensure that large debris
does not damage pumps and other equipment. The water may be dosed with chlorine or other
chemicals to remove potential odours, to kill algae, or to control zebra mussels [Punmia et al,
2009].
2.2.2 Aeration
Raw water pumped from the intake is mixed with air at the aerator. The aeration process
provides oxygen from atmosphere for the oxidation of dissolved iron and manganese to their
9
insoluble form thus enables their removal. The process also helps in the removal of taste and
odour.
2.2.3 Coagulation
Involves the addition of a chemical coagulant or coagulants for the purpose of conditioning
the suspended, colloidal, and dissolved substance for subsequent processing by flocculation
or to create conditions that will allow for the subsequent removal of particulate and dissolved
matter. It involves the addition of compounds such as aluminium sulphate (alum) and iron
salts, organic polymers and sometimes lime and carbon dioxide. Raw water will contain
small particles, known as colloids. These colloids produce a cloudy appearance known as
turbidity. Turbidity can shield micro-organisms from disinfection. This process causes small
particles to stick to one another, forming larger particles. The water is mixed at high speed
while alum is added to chemically combine with contaminants and neutralize the electrical
charges. This allows the impurities to begin coagulating, or forming small particles that can
more easily be removed [Twort et al, 2004].
2.2.4 Flocculation
Refers to the aggregation of destabilized particles (particles from which the electrical surface
charge has been reduced) and precipitation products formed by the addition of coagulants
into larger particles known as flocculants particles or, more commonly, ‘‘floc.’’ The
aggregated floc can then be removed by gravity sedimentation and/or filtration. The purpose
of flocculation is to produce particles, by means of aggregation, that can be removed by
subsequent particle separation procedures such as gravity sedimentation and/or filtration. The
two general types of flocculation can be identified: (1) Micro-flocculation (also known as
perikinetic flocculation) in which particle aggregation is brought about by the random
thermal motion of fluid molecules (known as Brownian motion and (2) Macro-flocculation
(also known as orthokinetic flocculation) in which particle aggregation is brought about by
inducing velocity gradients and gentle mixing in the fluid containing the particles. Mixing for
flocculation generally lasts for 20 to 40 min [Crittenden et al, 2012].
10
Table 1: Types of Flocculation and merits
Comparison to basic approaches to flocculation
Process issue Horizontal shaft with
paddles
Vertical shaft
turbines
Hydraulic
flocculation
Type of floc
produced
Head loss
Operational
flexibility
Capital cost
Construction
difficulty
Maintainance effort
Compartmentalizatio
n
Large and fluffy
None
Good, limited to low
G
Moderate to high
Moderate
Moderate
Moderate
compartmentalization
Small to medium,
dense
None
Excellent
Moderate
Easy to moderate
Low to moderate
Excellent
compartmentalizatio
n
Very large and fluffy
0.05-0.15m
Moderate to poor
Low to moderate
Easy to moderate
Low to moderate
Excellent
compartmentalizatio
n
Advantages Produces large floc.
Reliable.
No head loss.
One shaft for several
mixers.
No head loss.
Very flexible and
reliable
Highest energy input
potential
Flocculators can be
maintained without
shutdown.
Simple and effective.
Easy, low cost
maintainace.
No moving parts.
Can produce very
large flocs.
Little flexibility.
Disadvantages Compartmentalizatio
n more difficult.
Replacement and
maintainance require
Difficult to specify
proper impellers and
reliable gear drives
Little flexibility
11
shutdown.
Shaft breakage on
start up because of
high initial torque.
Figure 3: Types of Flocculation and merits(Muya, 2005)
2.2.5 Sedimentation
If turbid waters are placed into a large quiescent basin and left over time, the suspended
material can settle to the bottom of the basin. Particles settle out of solution because they are
large enough to settle out by gravitational forces. This process is called sedimentation. Most
raw surface waters contain mineral and organic particles. Mineral particles usually have
densities ranging from 2000 to 3000 kg/m3 and will settle out readily by gravity, whereas
organic particles with densities of 1010 to 1100 kg/m3 may require a long time to settle by
gravity. Depending on their density, suspended particles larger than 1μm can be removed by
sedimentation [Howe et al, 2012].
The simplest form of sedimentation basin is a large, open structure where the water can flow
through quiescently. As water flows through the basin, particles settle to the bottom, where
they form a sludge layer that is pushed by mechanical scrapers to a collection trough and
removed.
The larger suspended particles (floc) formed in the flocculation basin settle to the bottom of
the basin. Inclined plates are used to speed the settling. Clear water is skimmed off the top of
the basin. A well-designed inlet permits water from the flocculation basin to enter directly
into the sedimentation basin without channels or pipelines.
A diffuser wall is one of the most effective and practical flow distribution methods used at
the basin inlet when the flocculation basin is directly attached to the sedimentation basin. A
diffuser wall is simply a wall with many small holes strategically placed to uniformly
redistribute the flow of water.
For uniform distribution of raw water the openings should be spaced close to each other less
than 0.5m apart, and their diameter not less than 50mm. The draw-off should be made over at
least 25% of the length of a horizontal tank. The effluent water should leave the tanks over a
weir whose level is adjustable about 30mm or through a submerged perforated pipe. The total
12
length of the weir in meters should be at least 0.1 x A where A is the surface area of the
sedimentation tank in square meters. When filtration succeeds flocculation the outlet velocity
from the sedimentation tank should not exceed 0.4 m/s in order not to destroy residual flocs
[Water Design Manual Kenya, 2005].
The ratio length/width should be between 3:1 and 6:1 and the effective water depth should be
at least 2m. There should be an additional volume of 25% to allow for sludge accumulation.
The tank floor should slope gently (2-3%) towards a pocket placed at 1/4 to 1/3 of the length
of the tank from the inlet side [Water Design Manual Kenya, 2005].
The basic design criteria to be considered for the horizontal-flow settling zone are (1) surface
loading rate, (2) effective water depth, (3) detention time, (4) horizontal-flow velocity, and
(5) minimum length-to-width ratio.
13
Table 2: Sedimentation tanks: Types, design criteria, Merits and Demerits
TYPICAL
APPLICATION
DESIGN CRITERIA MERITS DEMERITS
Rectangular Basin(horizontal flows)
Municipal and
industrial works.
Suited to large capacity
plants.
Surface loading: 1.25-
2.5m/h
Water depth:3-5m
Detention time 1.5-4h
Minimum length to
width ratio 4:1 to 5:1
Weir loading <9-
13m2/h
More tolerance to
shock loads.
Predictable
performance under
most conditions.
Easy operations and
low maintainace costs.
Easily adapted for high
rate settler modules.
Subject to density flow
creation in basin.
Requires careful design
of inlet and outlet
structures.
Requires separate
flocculation facilities.
Upflow ( Radial Flow)
Small to midsize
municipal and
industrial water T
works.
Suited where rate and
raw water quality flow
is constant.
Surface loading: 1.25-
1.88m/h
Water depth:3-5m
Settling time 1-3h
Weir loading 170
m3/m.d
Economic Compact
Geometry.
Easy sludge removal.
High clarification
Efficiency.
Problems of flow short
circuiting.
Less tolerance to shock
loads.
Need for more careful
operations.
Limitation of more
practical size.
May require separate
flocculation facilities.
Solid Contact Clarifiers
Water Softening.
Flocculation-
Flocculation time
20min.
Surface loading: 2.1-
Good softening and
turbidity removal.
Sensitive to shock
loads and changes in
flow rate.
14
sedimentation
treatment of raw water
that has constant
quality and rate of
flow.
Plants treating raw
water with low solid
concentration.
3.1 m/h
Detention time 1.5-4h
.
Weir loading 175-350
m3/ m.d
Up flow velocity
<10mm/min
Flocculation and
clarification in one unit.
Compact and economic
design.
Sensitive to
temperature changes.
Plant operation
dependent on single
mixing motor.
Higher maintainace
cost and greater
operational skill
required.
Figure 4: Sedimentation tanks: Types, design criteria, Merits and Demerits
2.2.6 Filtration
The water is then filtered through layers of fine, granulated materials — either sand, or sand
and coal, depending on the treatment plant. As smaller, suspended particles are removed,
turbidity diminishes and clear water emerges. Removing as much suspended particles as
possible is very important for the operation of a treatment facility. Not only will the water
appear clean to the consumer, but removing suspended particles eliminates the possibility of
dangerous bacteria being protected from the disinfection process.
The most common type of filtration process is known as the rapid sand filtration. Although
there are various types of various sand filters, most operate using the same general principles.
These filters normally contain layers of anthracite, sand, and/or gravel. The tiny pore spaces
in the filter "media" trap the suspended particles. Most matter which has not settled in the
flocculation tank is entrapped by the filter media. Activated carbon may also be used to
remove taste and odour problems. The quality of the water, as it leaves the filtration process
can be determined by its turbidity. High turbidity may indicate that the filters require
cleaning.
Filters are cleaned on a regular basis (usually 1-4 days depending on the facility) by a process
known as backwashing. During this process the normal water flow is shut off and fully
treated water is pumped up, backwards, through the filter media to remove the entrapped
matter. The backwash water will be further treated to remove the solids or routed to the
sanitary sewer [Punmia et al, 2009].
15
Design details for final filters succeeding sedimentation (Muya, 2005)
Each filter unit should have individual inlet that can be closed for servicing and
backwashing. It should be such that flushing and velocities 0.4 m/s does not occur.
Backwashing: The backwash rates depend on grain size of filter media and should be
in with table below.
Table 3: Backwash rates in relation to effective grain size
Effective grain size of filter, mm Backwash rates m3/m2h
0.5 25
0.6 30
0.7 40
0.8 50
0.9 60
1.0 70
Figure 5: Backwash rates in relation to effective grain size
Backwash outlet system should be designed to a minimum backwash rate of
50m3/m2h despite calculation rate being lower.
For calculation, the amount of water for backwashing is assumed to be for a period of
8minutes.
2.2.7 Disinfection
This is an essential element of the overall strategy for providing water that is safe to drink.
Providing water free from pathogenic organisms is accomplished using several
complementary strategies:
(1) Selecting a water source that is free from microbiological contamination.
(2) Protecting surface water sources to minimize microbiological contamination.
(3) Treating water to remove microorganisms or eliminate their pathogenicity.
(4) Preventing recontamination of water as it is delivered to customers through the
distribution system
16
Surface waters, however, virtually always contain pathogenic organisms and must be
disinfected. Many different types of microorganisms can be present in surface water, but for
purposes of disinfection they can be grouped in broad classes that include viruses, bacteria,
and protozoa.
Five disinfection agents are commonly used in drinking water treatment today: (1) free
chlorine, (2) combined chlorine (chlorine combined with ammonia, also known as
chloramines), (3) chlorine dioxide, (4) ozone, and (5) ultraviolet (U.V) light. The first four
are chemical oxidants, whereas UV light involves the use of electromagnetic radiation [Dr
B.C Punmia et al, 2009].
Designing a disinfection system includes three primary activities:
(1) Selecting a suitable disinfectant and dose.
(2) Designing a system to inject or introduce the disinfectant into the water.
(3) Designing contactors that provide a sufficient amount of time for the disinfectant
reactions to take place.
Currently, there is no single disinfectant which satisfies all the above mentioned criteria.
Even chlorine once considered to be free of any adverse health effect has shown its
limitation. Disinfectant doses depend on whether the disinfectant is being used for
inactivation, residual maintenance, or both. When chemical disinfectants are added to water,
some of the chemical will be consumed during rapid oxidation of reduced compounds in the
water; this consumption is known as the initial demand. Once the initial demand has been
satisfied, additional chemical addition leads to a residual concentration in the water.
To protect against any bacteria, viruses and other microbes that might remain, disinfectant is
added before the water flows into underground reservoirs throughout the distribution system
and into your home or business. Denver Water carefully monitors the amount of disinfectant
added to maintain quality of the water at the farthest reaches of the system. Fluoride occurs
naturally in our water but also is added to treated water. [Howe et al, 2012]
1. Chlorination
17
It’s the process of adding of chlorine and chlorine compounds in water is called chlorination.
Chlorine is commercially available in three forms: liquid, powder and liquefied compressed
gas. Chlorine in its various forms is widely used to disinfect drinking water. This is attributed
to its cost, ease in application and adaptability to different environment. The majoradvantage
of chlorination is the residual chlorine in the distribution network and storage, which provides
protection against recontamination and microbial after growth.
On addition of chlorine to pure water, it produces hypochlorous acid (HOCL) and
hypochlorite ion (OCL-), which are the actual disinfecting agents. The reaction depends on
pH and temperature of the water. The disinfecting capacity is retained in HOCL, and it is
regarded to be greater than OCL-. It has been shown that HOCL kills 80 – 100 times more
E.coli than OCL-.
Cl2 + H2O -> HOCl + H+ + Cl-
Depending on the pH value; underchloric acid partly expires to hypochlorite ions:
Cl2 + 2H2O -> HOCl + H3O + Cl-
HOCl + H2O -> H3O+ + OCl-
2. Ozonation
Ozonation is the method of diffusing ozone, an allotropic form of oxygen into the water for
the purpose of disinfection. The inherent instability of ozone to decompose back to oxygen
necessitates its production on site for immediate use. It is produced by passing an electric
discharge of high voltage alternating current through the dry air. In the generation process, a
power voltage of 4-20 kilovolts is applied to dielectric plates about 6mm apart or to
concentric tubes through which clean, dry oxygen rich gas is blown. The amount produced
may be up to 30 mg/m3 of the blown air. The generation process, the need of skilled
manpower for operation and maintenance leads to higher cost. These disadvantages hinder its
adoption in developing countries.
Ozone is also used for taste and odour control, colour removal and oxidation of iron and
manganese and organic removal. When using ozone as a disinfectant the recommended
dosage is 0.2 – 1.5 mg/L.
Ozonation as a disinfectant has the following benefits: -
• Highly effective disinfectant in destroying pathogenic bacteria and viruses.
18
• More effective in disinfecting water containing ammonia than chlorine.
Ozone’s ability to decompose organic matter may cause problems in the network due to
increasing volume of bio-assimilable compounds, unless the degradation products are
removed or an additional disinfectant with a long term effect is used [Practice Manual for
Water Supply Services in Kenya, 2005].
3. Ultra-violet Radiation
The UV rays are part of the electromagnetic spectrum between x-rays and visible light. The
most common source of UV radiation is the coated mercury low pressure lamp. This type of
lamp is mostly used in existing UV plants for disinfection purposes. To achieve the
maximum efficiency the lamps must be kept clean so that the organisms are exposed to the
full intensity of the UV light.
Disinfection is accomplished when the water is exposed to the UV light source. For effective
disinfection, the water must be without turbidity or colour and free from organic colloids that
might form deposits on the tubes or obstruct the passage of light. Also the depth of water
must be shallow.
Because the UV radiation leaves no residual, the disinfection has to be complimented either
with chlorine or chlorine dioxide. The shortcomings coupled with the hardware problems
make UV unfeasible in developing countries [Practice Manual for Water Supply Services in
Kenya, 2005].
2.2.9 Corrosion control
pH is maintained by adding high pH substances to decrease corrosion in the distribution
system and the plumbing in your home or business. Corrosion inhibitors such as calcium are
added to increase the service life of the piping throughout the distribution system [Practice
Manual for Water Supply Services in Kenya, 2005].
2.2.10 Storage
Treated water from the retention tank will be collected and kept in a clean dark tank to
prevent the growth of algae the tank si small in size and makes sure that the water is safe for
domestic use. Residual chlorine is used or more chlorine is added. This is to act as a
disinfectant according to safety regulations. Fluoride may be added to enhance dental health.
In addition, Lime and carbon dioxide may be added to make the water less corrosive to home
plumbing systems [Punmia et al, 2009].
19
2.3 Factors Influencing the Water Supply Capacity
The major objective of water supply system is to supply adequate water for a town which is
adequate water for domestic, commercial, industrial and livestock use. Therefore a selected
for a suitable should be selected and the other alternative should be studied and compared
technically and also from economic point of view. The design population, period, topography
of the area and construction cost of transmission lines should be considered in details.
2.3.1 Design period
Design period is also called the design life. It is the number of years in future for which the
given facility is available to meet the demand. Design period is provided because it is very
difficult or impossible to provide frequent extension. It is also cheaper to provide a single
large unit rather to construct a number of small units. The design period is the length of time
it is estimated that the facility will be able to meet the demand that is the design capacity.
Buildings, other structures, and pipelines are assumed to have a useful life of 50 years or
more. See appendix VI for design period table.
2.3.2 Population Projection.
Population projections are estimates of the population for future dates. For the water supply
system population should be estimated based on latest census in this case will be 2009.
Design of water supply and sanitation scheme is based on the projected population of a
particular city, estimated for the design period. Any underestimated value will make system
inadequate for the purpose intended; similarly overestimated value will make it costly.
Changes in the population of the city over the years occur, and the system should be designed
taking into account the population at the end of the design period.
Factors affecting changes in population are: -
• Increase due to births.
• Decrease due to deaths.
• Increase/decrease due to migration.
• Increase due to annexation.
The present and past population record for the city can be obtained from the census
population records. After collecting these population figures, the population at the end of
20
design period is predicted using various methods as suitable for that city considering the
growth pattern followed by the city.
a) Linear Increase
It implies that there is a constant amount of increase per unit of time. A straight line is used to
project population growth. This method is suitable for large and old cities with considerable
development. If it is used for small, average or comparatively new cities, it will give lower
population estimate than actual value. It is expressed as:
Pt=P0+bt…………………...Eq 1
Where: P0 – initial population at present.
Pt – population after t years
b – Annual amount of population change
b) Geometric Increase
According to this method, it is assumed that the rate of increase of population growth in
communityis proportional to the present population. In this method the percentage increase in
population fromdecade to decade is assumed to remain constant. Geometric mean increase is
used to find out thefuture increment in population. Since this method gives higher values, it
should be applied for anew industrial town at the beginning of development for only few
years.
Pn=P0 (1+r )n………………..Eq 2
Where: Pn- population after n years.
Po- Population at the present.
R- Annual population growth rate.
c) Exponential Increase Method
The method is based on the assumption that percentage growth rate is constant i.e.
dPdt
=kP ; lnP=ln P0+kt………………Eq 3
The method however must be used with caution, as it may produce results that are too large
for rapidly growing cities in comparatively short time. This would apply to cities with an
unlimited scope of expansion [Source].
2.3.3 Water Demand
Water demand varies for the different uses. These can be classified as follows:
i. Domestic or Residential demand
21
This includes water used required in private building for drinking, bathing, gardening,
sanitary purpose etc. it is influenced by population density and service type (depends on
whether an individual is connected or not).
ii. Industrial demand
It represents the water demand of industries which earlier exist or are likely to be started in
future. Water used for industrial purposes may be incorporated into products or used for
processing, washing, cooling, sanitation, or maintenance. Industries are categorized into bar,
shops, restaurants, large enterprises, military camps etc.
iii. Commercial demand
This is the water requirement for institutions, hotels, schools, health facilities, colleges and
offices. It should be anticipated that the future increase in commercial activity would be
directly related to the growth of population.
iv. Fire demand
In populated or industrial areas, fires generally breakout and may lead to damage. For control
that situation requires sufficient quantity of water which is the fire demand.
v. Livestock demand
Includes water associated with the production of meat, milk, poultry, eggs, and wool. The
kind of stock includes dairy cows and heifers, beef cattle and calves, sheep and lambs, goats,
hogs and pigs, and poultry. Poultry includes chickens, turkeys, ducks, geese, pheasants, and
pigeons. (Hutson et al, 2004). Usually estimating water livestock demand the following
conversion factor is used: 1 grade cow; 3 indigenous cows; 15 sheep or goat and 100
chickens are equivalent to one livestock unit (LU).
2.3.4 Losses
Every water supply has a portion of ‘” unaccounted for” water which includes:
Consumer wastages, leakages and wastage from consumer premises.
Distribution losses, leakages from mains, service pipes and service connections,
valves, hydrants and wash outs.
Metering and other losses, unauthorized and unrecorded connections.
Treatment works usage and overflow at reservoirs.
22
Water demand projections should normally be made for the “initial”, the “future” and the
“ultimate” year. The “initial” year is the year when the supply is expected to be taken into
operation that may be assumed to be 0-5 years from the date of the commencement of the
preliminary design. The “future” is 10 years and the “ultimate” year 20 years from the initial
year. Once the initial, future and ultimate years have been determined for a project they
should not normally be changed during the design period. However phasing of the
implementation will often become a financial necessity and the possibilities of phasing
should therefore be examined using the initial and future demand projections. (Water Design
Manual, 2005 Kenya).
23
2.4 Generation of Concept Design
24
Problem Identification
Lack of supply of clean, safe and reliable water
Change in Weather and climatic part
Problem analysis
Desk study carried out to understand the problem fully and identify possible causes
Solution Development
Several water supply methods were studied in great depth to identify the best method to be used. The selected method was chosen based on
Economical Viability Social acceptability Technical feasibility
CHAPTER 3
THEORETICAL CONSIDERATIONS
3.1 Population Data
3.2.1 Human Population
After collecting these population figures, the population at the end of design period is
predicted using various methods as suitable for that city considering the growth pattern
followed by the city.
a) Geometric Increase
Based on the hypothesis that rate of change of population is proportional to the population.
According to this method, it is assumed that the rate of increase of population growth in
community is proportional to the present population. In this method the percentage increase
in population from decade to decade is assumed to remain constant. Geometric mean increase
is used to find out the future increment in population. Since this method gives higher values,
it should be applied for a new industrial town at the beginning of development for only few
years.
Pn=P0 (1+r )n………………..Eq 2
Where: Pn- population after n years.
Po- Population at the present.
R- Annual population growth rate.
The values of demand will be used together with the projected population to generate the
quantity of water demand as shown below. The quantity of water demanded is obtained from
the formula:
Wa ter Demand=per capitademand x population
3.2 Water Quality Samples
The criteria used for determining the frequency of sampling in the guidelines (Water Services
Regulatory Board) include:
1. Source of the water - whether ground or surface water;
2. Volume produced and Population served;
3. Number of tests to be conducted – both bacteriological and physiochemical
25
Identification of strategic sampling points within the distribution system is important in
ensuring that these are representative of the entire system and at the same time ensuring that
particular problem areas are identified.
In selecting sampling points, the following general selection criteria should be taken into
consideration:
a) Samples taken have to be representative of the different sources from which water is
obtained by the consumers or enters the system
b) Sampling points should include the most unfavorable sources or places in the supply
system, particularly points of possible contamination such as unprotected sources,
loops, reservoirs, low-pressure zones, ends of the system etc.
c) Sampling points should be uniformly distributed throughout a network.
3.3 Design of Water Supply Facilities
3.3.1 Water Supply Intake Structure
a. Trunk Main Pipe Size
Volume flow, Q = volume(m3)/Time(sec)
Elevation at the raw water intake, H1
Elevation at the treatment water works site, H2
Change in elevation, ∆H= H1-H2
Distance between the intake and the T works, (total length of the pipe), L
Pipe roughness coefficient=150 from the Hazel Wiliiams Chart
Using Hazen-Williams equation (majorly used in determination of friction losses) to obtain
pipe diameter, D
∆ H =10.7 L ×Q1.852
C1.852× D4.87
The head loss can be verified by using Darcy Weisbach equation:H f =fLV 2
D× 2g
Where:
Hf = head loss (m)
26
f = friction factor
L = length of pipe work (m)
d = inner diameter of pipe work (m)
v = velocity of fluid (m/s)
g = acceleration due to gravity (m/s²)
b. Flocculation Tank Calculations
The general design criteria for a basic rectangular flocculation tank are as follows:
Energy input: Gt=10,000 to 100,000,
t =5x104 s average,
G=30 s-1 average, 10-70 range
DT: 20-30 minutes at Qmax. (Design Time)
Depth: 10-15’
Stages: 3-4 common, 2-6 range
The energy level is the G value or velocity gradient as defined by Camp: G = [P /V]2
The number of particle contacts is: N = n1n2(G/6)(d1 + d2)3
N is the number of contacts between n1 and n2 particles.
c. Sedimentation tank
Detention period: for plain sedimentation: 3 to 4 h, and for coagulated sedimentation: 2 to 2.5
h.
Velocity of flow: Not greater than 30 cm/min (horizontal flow).
Tank dimensions: L:B = 3 to 5:1. Generally L= 30 m (common) maximum 100 m. Breadth=
6 m to 10 m. Circular: Diameter not greater than 60 m. generally 20 to 40 m.
Depth 2.5 to 5.0 m (3 m).
27
Surface Overflow Rate: For plain sedimentation 12000 to 18000 L/d/m2 tank area; for
thoroughly flocculated water 24000 to 30000 L/d/m2 tank area.
Slopes: Rectangular 1% towards inlet and circular 8%
d. Chlorination Tank
Using a chlorine dose of 2mg/l; (which conforms to the WHO water standards which requires
that 2-3mg/l of chlorine should be added in order to gain satisfactory disinfection and residual
concentration)
e. Storage Tank Capacity
The required total storage capacity of a reservoir capacity is the summation of: balancing,
breakdown and fire reserve. The balancing reserve can be estimated from data of hourly
consumption of water for the town. Due to the unavailability of this data, the storage capacity
is assumed to be 1/8 of the total daily water demand i.e. the storage water tank will be able to
store 1/8 of the quantity of water processed at the treatment plant per day.
28
CHAPTER 4
MATERIALS AND METHODS
4.1 Introduction
In establishing the water utilization/demand in the area various data like population data,
livestock data, use of water data, need for water data, water samples-industrial and
institutional data was required. This data was obtained from Kenya National Bureau of
Statistics. Household Questionnaires, Interviews, water samples will be used.
Raw water samples was taken to University of Nairobi-Civil Engineering Department water
laboratories for analysis. The results was compared against the required standards.
In order to obtain the other objectives like the specifications for the raw water treatment
works and related components, it was important to design the Coagulation, Flocculation,
Sedimentation tanks, Filtration, back wash and disinfection storage tanks based on the water
demand of the area in year’s projection plus the criteria set standards in Kenya. There was
equally need to use AutoCAD design drawings for the design capacity for the project. It
involved use of AutoCAD software, Google earth, Google Maps and Laptop computer.
Different data were needed for the design of a raw water treatment system in Nyansiongo
area. Methods of data collection had to be established beforehand to ensure the process will
efficient. Once the data was collected it was analyzed to produce an outcome that satisfies the
objective of the report. The data collected include:
a) Population of the area.
b) Land use.
c) Topographical data.
d) Existing water supply.
e) Information on water consumption per capita in the area.
f) Water samples.
In order to obtain this data various data collection methods were used as shown below.
4.2 Data collection methods
Various methods were employed to collect data needed for the design of the system. Both
primary and secondary data were needed.These include:
a) Questionnaires.
b) Interviews.
29
c) Literature review.
d) Government agencies.
e) Direct observation.
f) Samples.
4.2.1 Questionnaires
Questionnaires were prepared to aid with the collection of data. The questionnaires were
given to the relevant parties. In order to obtain an overview of water use in the area, the
questionnaire was handed to the community for a brief description on how they use the water.
With regards to the existing water supply, it was necessary to involve Gusii Water and
Sewerage Company with the use of questionnaires to obtain information on their existing
system.
4.2.2 Interviews
In addition to questionnaires, face to face interviews were also conducted. The interviews
were done to collect data on the challenges facing the existing supply of water and the
sources available for people in the area. These interviews were carried out with the members
living in the project area.
Information on the proposed source was also be required. The current population of the town
and the change of boundaries in the area over the past ten years information were obtained
from an interview conducted with the technical manager at Nyansiongo Tea Factory having
been the active users of the water from the dam as well as the local chief of the area.
Information on the change of boundaries was necessary in order to estimate the population
growth rate in the area.
4.2.3 Government Agencies
In order to collect topographical data, a map from the Google Earth was obtained for the area.
This map had information on the roads, contours, rivers, all the natural and man-made
features which were necessary for the design of the system.
4.2.4 Direct Observation
Direct observation for information on settlement and land use was necessary because of the
rate at which the town is growing. This was especially needed for the land site location for
the treatment plant.
30
Some problems associated with water problems could also be observed firsthand hand. These
included polluted water sources and broken down borehole pumps.
4.2.5 Sample
Water samples were taken from a water intake point identified. The three samples were taken
at very different river water depth, for example, sample one at 0.2m; Sample two at 0.8m and
Sample three at 1.4m below water surface.
4.3 Data Analysis Methods
This involves qualitative and quantitative analysis. The data collected by use of various
instruments was first be edited to get the relevant information. The edited data was coded for
easy classification in order to facilitate tabulation. The tabulated data was then be analyzed
by calculating the design capacities of the raw water treatment tank. Presentation of data was
to be in form of a report, calculations as well as AutoCAD drawings. Descriptive data was
provided in form of explanatory notes.
31
CHAPTER FIVE
RESULTS AND ANALYSIS
5.1 Population Data
The computation of the present and the future population is based on the geometric increase
methodPn=P0 (1+r )n . Growth rates for the area have been derived from the census conducted
in the country every 10 years. However the population to be served is primarily the
Nyansiongo Town and the outskirts.
Household: households includes all commercial and private residential areas within
Nyansiongo Town.
Livestock: they include all the domestic animals that are reared by the residents in
Nyansiongo Town majorly cows, goats, sheep and poultry.
Learninginstitutions: there are three major institutions in Nyansiongo Town, they include
primary schools such as Gesibei Primary School, Menyenya Primary School, high schools
including Menyenya high school as well as tertiary education institutions e.g. Borabu
Computer College.
Industries: The one major industry in Nyansiongo is the Nyansiongo Tea Factory. We also
have banking industry such as the Borabu Sacco and hotels e.g Borabu Inn
CommercialBuildings: they include the shops and supermarkets located within the town
center as well as the bars and cafés
NB: The growth rate of the Nyansiongo Town is assumed to be 1.83% (Nyamira-County,
2015) and the growth is projected linearly i.e. an increase in the household population leads
to an increase in the livestock at the same magnitude and that equally leads to an increase in
the number of students in schools by the same magnitude.
My area of projection is about 20% of the Nyansiongo Ward.
PARAMETER PER TOTAL +20%
32
POPULATION
CAPITA
DEMAND
WATER
DEMAND
ALLOWANCE
1999 2009 2019 2029
HOUSEHOLD 1700 3241 3886 4658 60 279480 335376
LIVESTOCK 400 900 1079 1293 50 64650 77580
COMMERCIAL
BUILDINGS
10 50 56 63 100 6300 7560
LEARNING
INSTITUTIONS
900 1500 1798 2155 25 53875 64650
INDUSTRIES 50 80 96 115 500 11500 13800
TOTAL 498966l/d
Figure 6: population in the Nyansiongo Area
498966l/d=0.01m3/s
5.2 Field Investigation and Data Collection
5:2:1Raw Water Quality Sampling
Raw water samples were collected from three different points at the Mosiabano Dam. The
samples were taken for testing to the University of Nairobi, department of civil engineering
and public health in Nairobi, Kenya. The samples ha to be carried in cool boxes to ensure that
they were uncontaminated and also had to be taken to the lab in not more than 6 hours so that
the biological components of the sample quality could not be affected i.e. die.
5.2.2 Samples Testing
1. Sample 1
The outstanding factor from physiochemicalwater quality test is the high level concentration
of iron ions (Fe+). In the bacteriology examination of water, the E.Coli (44oc) was determined
as nil making the water safe for domestic use. In the bacteriology, also the coliform
organisms and the plate/colony/total viable was determined (37oc). Results are attached on
appendix V and VI.
33
PARAMETER RESULT RECOMMENDED REMARK
pH 6.5 6-9 Complied
Apparent color 15.0 15 Complied
True color 10.0 15 Complied
Conductivityµ/S/CM mg/l 300.0 2000 Complied
Turbidity F.T.U mg/l 2.0 5 Complied
Calcium hardness CaCo3 mg/l 78.0 250 Complied
Total Hardness CaCo3 mg/l 210.0 500 Complied
Total Alkalinity CaCo3 mg/l 190.0 500 Complied
Carbonate Alkalinity mg/l 0.0 Complied
Iron mg/l 0.8 0.3 Failed
Fluorides mg/l 0.0 1.5 Complied
Sulphates mg/l 0.0 400 Complied
Dissolved oxygen p.p.m 4.8 2min Complied
Nitrates mg/l 0.8 10 Complied
Nitrites mg/l 0 10 Complied
Chlorides mg/l 80 250 Complied
Total coliform/100ml - Complied
Total Feacal Coliform/100ml - Complied
Dissolved solids mg/l 300 Complied
Suspended solids mg/l 50 Complied
Total solids mg/l 350 1500 Complied
Figure 7: physiochemical analysis of Sample 1
MICROBIOLOGICAL ACTIVITY REQUIREMENT
PARAMETER RESULTS RECOMMENDED REMARK
Plate/colony/Total Viable at 370c 35 100 Complied
MPN of coliform organism 15 Absent
MPN of Ecoli Nil Absent Complied
Figure 8: Bacteriology analysis of sample 1
34
2. Sample 2
In the physiochemical analysis, outstanding factor from water quality test is the high level of
iron ions Fe+. In the bacteriology examination of water, the E.coli (44oc) was determined as
nil making the water safe for domestic use. In the bacteriology, also the coliform organisms
and the plate/colony/total viable was determined (37oc). Results are attached on appendix VII
and VIII.
PARAMETER RESULT RECOMMENDED REMARK
pH 6.63 6-9 Complied
Apparent color 15.0 15 Complied
True color 10.0 15 Complied
Conductivityµ/S/CM mg/l 316.0 2000 Complied
Turbidity F.T.U mg/l 2.5 5 Complied
Calcium hardness CaCo3 mg/l 78.0 250 Complied
Total Hardness CaCo3 mg/l 200.0 500 Complied
Total Alkalinity CaCo3 mg/l 170.0 500 Complied
Carbonate Alkalinity mg/l 0.0 Complied
Iron mg/l 0.6 0.3 Failed
Fluorides mg/l 0.0 1.5 Complied
Sulphates mg/l 2.0 400 Complied
Dissolved oxygen p.p.m 4.5 2 min Complied
Nitrates mg/l 0.8 10 Complied
Nitrites mg/l 0 10 Complied
Chlorides mg/l 64 250 Complied
Total coliform/100ml - Complied
Total Feacal Coliform/100ml - Complied
Dissolved solids mg/l 310 Complied
Suspended solids mg/l 30 Complied
Total solids mg/l 340 1500 Complied
Figure 9: Physiochemical analysis of sample II
35
MICROBIOLOGICAL ACTIVITY REQUIREMENT
PARAMETER RESULTS RECOMMENDED REMARK
Plate/colony/Total Viable at 370c 25 100 Complied
MPN of coliform organism 18 Absent
MPN of Ecoli Nil Absent Complied
Figure 10: Bacteriology analysis of sample II
3. Sample 3
In the physiochemical analysis, outstanding factor from water quality test is the high level of
iron ions Fe+. In the bacteriology examination of water, the E.coli (44oc) was determined as
nil making the water safe for domestic use. In the bacteriology, also the coliform organisms
and the plate/colony/total viable was determined (37oc). Results are attached on appendix IX
and X.
PARAMETER RESULT RECOMMENDED REMARK
pH 6.64 6-9 Complied
Apparent color 15.0 15 Complied
True color 10.0 15 Complied
Conductivityµ/S/CM mg/l 300.0 2000 Complied
Turbidity F.T.U mg/l 2.0 5 Complied
Calcium hardness CaCo3 mg/l 75.0 250 Complied
Total Hardness CaCo3 mg/l 200.0 500 Complied
Total Alkalinity CaCo3 mg/l 180.0 500 Complied
Carbonate Alkalinity mg/l 0.0 Complied
Iron mg/l 0.8 0.3 Failed
Fluorides mg/l 0.0 1.5 Complied
Sulphates mg/l 0.0 400 Complied
Dissolved oxygen p.p.m 4.0 2 min Complied
Nitrates mg/l 1.0 10 Complied
Nitrites mg/l 0 10 Complied
Chlorides mg/l 36 250 Complied
Total coliform/100ml - Complied
Total Feacal Coliform/100ml - Complied
Dissolved solids mg/l 350 Complied
36
Suspended solids mg/l 50 Complied
Total solids mg/l 400 1500 Complied
Figure 11: Physiochemical analysis of Sample III
MICROBIOLOGICAL ACTIVITY REQUIREMENT
PARAMETER RESULTS RECOMMENDED REMARK
Plate/colony/Total Viable at 370c 25 100 Complied
MPN of coliform organism 10 50
MPN of Ecoli Nil Absent Complied
Figure 12: Bacteriology analysis of Sample III
5.3 Design of water Supply Features
The water intake from the dam is designed for the ultimate demand of supplying the residents
of Nyansiongo Ward water at the rate of 0.01m3/s as per 2029 in regard to the Kenyas Vision
2030.
5.3.1 Main pipe:
Volume flow, Q = 498.966m3/day =0.01m3/s
Elevation at the raw water intake, H1= 1575
Elevation at the treatment water works siteH2=1550
Change in elevation= ∆H= H1-H2 =1575-1550= 25
Distance between the intake and the works, (total length of the pipe), L=300
Pipe roughness coefficient=150 from the Hazel Williams Chart
Using Hazen-Williams equation (majorly used in determination of friction losses) to obtain
pipe diameter, D
∆ H=10.7 L ×Q1.852
C1.852× D 4.87 =
D=0.125m/125mm
Q=VA; A=π r2 = (3.142*1252)/4 = 0.01m2
Q=VA: V=1m/s
37
Determination of head loss due to friction in the pipes in the pipes:
Reynolds number:
Re=velocity∗diameter
viscocity
Re=0.01∗0.125
10−6
Re=1.25*105 therefore flow istabular
The value of coefficient of fluid friction was determined from the value of Relative
roughness, and the Reynolds number, Re from the moody diagram:
Re=1.25*105
¥=4.0*10-3
Coefficient of fluid friction=3.5*10-2
The head loss can be verified by using Darcy Weisbach equation:H f =fLV 2
D× 2g
Where:
Hf = head loss (m)
f = friction factor
L = length of pipe work (m) 700
d = inner diameter of pipe work (m)
v = velocity of fluid (m/s)
g = acceleration due to gravity (m/s²)
H f =3.5∗10−2∗700∗12
0.125× 2∗9.81= 10m
Since Hf2<∆H), Adopt the Head of 25m
5.3.2 Flocculation
Design flow = 498.966m3/day=0.01m3/s
38
Design retention time = 25 minutes
Using 3 compartments in series with values of G=50s-1, 30s-1 and 10s-1 in the first, second and
third compartments respectively:
Average G =50+30+10
3=30 s−1
GT value = 30s-1 × 45 × 60s = 81000 (since GT value is between 50,000- 100,000 the
detention time is considered satisfactory).
Basin volume, V = Flow, Q × detention time =468.966
24 ×3600×30 ×60=18 m3 taking width of
entire basin as 4m,
Top area = 18 ⁄ 4= 4.5m2
Assume compartments of square profile and let L represent the compartment width and
depth:
3L × L = 18m2
L = 2.1m
Width=2.1m
Total length of the basin = 3L = 3 × 2.1m = 6.3m
Total volume of the basin, V = ﴾6.3 × 2.1 × 15 ﴿ m3 = 198.45m3
Flocculation will be achieved by use of sinuous baffled channels which does not involve
mechanical moving parts. In this case the required mixing intensity is provided by the energy
dissipated due to the losses at the 180o bends of the baffles. The head loss over the total
channel will range from 0.3 – 1.0m. The loss of head is computed as 2-3.5 times the velocity
head for each 180o bend (half cycle turn) for round the end type.
The floor of the flocculator unit will have a 3.5% slope towards the outlet in order to maintain
a constant water depth.
5.3.3 Sedimentation Tank
Detention period: for plain sedimentation: 3 to 4 h, and for coagulated sedimentation: 2 to
2.5h.
39
Velocity of flow: Not greater than 30 cm/min (horizontal flow)/0.005m/s.
Tank dimensions: L: B = 3 to 5:1. Generally L= 30 m (common) maximum 100 m. Breadth=
6 m to 10 m. Circular: Diameter not greater than 60 m. generally 20 to 40 m.
Depth 2.5 to 5.0 m (3 m).
Surface Overflow Rate: For plain sedimentation 12000 to 18000 L/d/m2 tank area; for
thoroughly flocculated water 24000 to 30000 L/d/m2 tank area.
Slopes: Rectangular 1% towards inlet and circular 8%.
NB: One sedimentation tank is enough for use because of the general quantity of water
desired. Select the rectangular model because long rectangular basins are hydraulically more
stable, and flow control for large volumes is easier with this configuration. Taking a length to
width ratio of 4 (lying within acceptable limits), and using a length of 30m (such that width is
7.5m). The height is taken as 4m as it lies within the acceptable limits of 2.5m to 5m.
Surface Loading Rate = Q
Area=2.23 m3/m2 day
Weir Overflow Rate =Q
wier Length= 16.63m³/m day
Retention time=volume
flow /day=1.9 hours
The detention time for sedimentation tanks ranges between 1.2 – 4 hours, thus the value
calculated above of 1.9 hours is acceptable. It should have a slope of about 1% towards the
inlet as per the required engineering design to maximum and effective settling.
Dimensions of sedimentation tanks: 30m × 7.5m ×4
40
5.3.3 Filtration Tank
Rapid Sand filters
Net filtered water = (498.966m³/24hrs) = 21m³/hr.
Backwashing=2%
Backwashing time: 30 min
Total filtered water = Q/Day= 21.23m3/ h
Time
Let the rate of filtration be 1m3 / h / m2 of bed.
Area of filter =Total Filtered water x 1
rate of filtration = 21,23m2
Provide one unit. L/B = 1.3; 1.3B2 = 21.23
B = 4.04m; L = 4.04 x 1.3 = 5.25 m
Area of filter: 4.04*5.25
Estimated depth of sand:
Q × d³ ×hL= Bi × 29323
Where: Q = filtration rate in m³/m²/hr.;
d = sand size in mm;
H = total head loss in metres;
L = depth of sand bed metres;
Bi = breakthrough index (its value ranges between 0.0004 to 0.006 depending on the
response to coagulation and the degree of pre-treatment in the filter)
41
Layer Depth Size
Topmost 15 2-6
Intermediate 15 6-12
intermediate 15 12-20
Bottom 15 20-50
NB: Thickness of the gravel bed is 45-60m
The exact depth of the gravel can be estimated by:
L=2.54*K*log d (gravel size in mm)
Depth of sand = 32cm.
Underdrainage system:
Total area of holes = 0.2 to 0.5% of bed area.
Assume 0.2% of bed area = 5
100 x 21.23 = 1.06m2
Area of lateral = 2 (Area of holes of lateral)
Area of manifold = 2 (Area of laterals)
So, area of manifold = 4 x area of holes =4.24m2.
Diameter of manifold= (4∗manifold area
π¿^1/2 = 2.32m
Assume c/c of lateral = 30 cm. Total numbers = 7.5/ 0.3 = 25 on either side.
Length of lateral = length
2−diameter
2 = 0.86m.
42
C.S. area of lateral = 2 x area of perforations per lateral. Take dia of holes = 13 mm
Number of holes=bed area
area of the holes = 80
Number of holes per lateral = 80/50=2
Area of perforations per lateral = 13 x p (1.3)2 /4 = 17.24 cm2
Spacing of holes = length of lateral/number of holes per lateral =0.43m.
C.S. area of lateral = 2 x area of perforations per lateral = 2 x 17.24 = 34.5 cm2.
\ Diameter of lateral = (4 x 34.5/p)1/2 = 6.63 cm
Check: Length of lateral < 60 d = 60 x 6.63 = 3.98 m. l = 2.545 m (Hence acceptable).
Rising washwater velocity in bed = 50 cm/min.
Washwater discharge per bed = (0.5/60) x 4.04 x 5.25 = 0.18 m3s-1.
Velocity of flow through lateral = 0.36 = 0.36 x 10 4 = 2.08 m/s (ok)
Total lateral area 50 x 34.5
Manifold velocity = 0.36 = 1.04 m/s < 2.25 m/s (ok)
0.345
Washwater gutter
Discharge of washwater per bed = 0.36 m3/s. Size of bed = 4.04*5.25m.
Assume 3 troughs lengthwise= 1.4m c/c.
Discharge of each trough = Q/3 = 0.18/3 = 0.06 m3/s.
Q =1.71 x b x h3/2
Assume b =0.3, h=24m≠25cm
43
= 25 + (free board) 5 cm = 30cm; slope 1 in 40
Clear water reservoir for backwashing
For 4 h filter capacity, Capacity of tank = 4 x 1000 x 4.04 x 5.25 x 2 = 170 m3
1000
Assume depth d = 5 m. Surface area = 170/5 = 34m2
L/B = 2; 2B2 = 345; B = 13 m & L = 26 m.
Dia of inlet pipe coming from two filter = 50 cm.
Velocity <0.6 m/s. Diameter of washwater pipe to overhead tank = 67.5 cm.
Air compressor unit = 1000 l of air/ min/ m2 bed area.
For 5 min, air required = 1000 x 5 x 7.5 x 5.77 x 2 = 4.32 m3 of air.
5.3.4 Retaining Tank
Using a chlorine dose of 2mg/l; (which conforms to the WHO water standards which requires
that 2-3mg/l of chlorine should be added in order to gain satisfactory disinfection and residual
concentration)
Approximate amount required in 1 day = ﴾498.966× 3× 10-3 ≈﴿ 1.5kg/day
Assuming amonth has 30.4 days, the amount of chlorine required per day is 45.6kg≠50kgs.
Balancing tank: Minimum retention time = 30min
Q=0.01m3/s
V=QT=18m3
5.3.5 Storage Tank Capacity
The required total storage capacity of a reservoir capacity is the summation of: balancing,
breakdown and fire reserve. The balancing reserve can be estimated from data of hourly
consumption of water for the town. Due to the unavailability of this data, the storage capacity
44
is assumed to be 1/8 of the total daily water demand i.e. the storage water tank will be able to
store 1/8 of the quantity of water processed at the treatment plant per day.
Volume of the tank = 498.966
8=62.37 m3
Assuming the tank is a circular tank with a total height of 5.4m {including a free board of
0.4m}
Total surface area of the tank = 62.37
5=12.5 m2
Area=π r2Then radius becomes 2m
45
CHAPTER 6
DISCUSSION
The objective of this project was to design a raw water treatment plant at Mosiabano Dam.
This was determined by finding the projective population of the area by 2029 (In line with
Kenya’s Vision 2030manifesto). The per capita demand of water for different livestock,
institutions, commercial shops, industries as well as household were determined using the
geometric increase.
The raw water tests were conducted at the University of Nairobi Civil Engineering
Department, the Laboratory for Public Health. Both the physiochemical properties and the
bacteriological properties were determined. The water was determined to be slightly acidic
probably due to the acidic loam soils in the region (though it was lying within the KEBS
recommended standards) as well as with high levels of iron ions also due to the iron in the
soils in the region. The bacteriological analysis was found to be lying within the
recommended standards. The ecoli was performed at 440c because that’s the temperature at
which the bacteria thrives and is responsible for diseases such as diarrhea. The Plate count
and the coliform experiments were performed at 370c. the excess iron can be removed from
the water through
The information extracted from the water demand was used to design the features for the dam
from the intake pipe, flocculation chamber, the sedimentation chamber, the filtration tank as
well as the chlorination and storage tanks.
46
CHAPTER 7
CONCLUSIONS AND RECOMMENDATIONS
7.1 Achievement of Objectives
Specific Objective 1: Obtained human population, livestock and number of institutions of the
area and other data which I used to obtain the water utilization demand of the area.
Specific Objective 2: The Water Quality Test performed at the University Public Health
Laboratory helped determine the raw water quality.
Specific Objective 3: With water utilization need of the area determined, the specifications
for the raw water treatment works and related components could easily be determined. By
sharing of walls between some tanks/basins and also allows for water conveyance by gravity
in turn contributes to reduced construction costs and minimizing the pumping costs
respectively thus reduced water cost to the contractor and end users.
7.2 Conclusions
This project design procedure for the raw water treatment plant gives a clear step by step
procedure on how to determine the components of the raw water plant using the demand in
the area. This was to ensure that the overall objective of the design was optimally realized.
Through the design project, the water demand of the area was established, the water quality
determined and the specifications of the raw water treatment plant determined.
7.3 Recommendations
1. An EIA be conducted before the projected is carried out to identify the Environmental
impact of the project.
2. Design of other civil works like: office/ laboratory building, grade 9 staff housing, guard
housing, motor control centres for power supply, sluice drying chambers be incorporated at
or near the proposed site in order to provide a wholesome water treatment plant and a
distribution system of the area.
3. A water distribution system should be designed for easy access for it is use by humans and
animals.
4. A sewerage system design for the area should be done. This would reduce the amount of
pollution that goes into the rivers in the area.
47
7.4 Challenges of Study
Lack of a coolbox to carry the water samples to the lab for testing that could end up affecting
the quality of the samples.
Lack of sufficient funds on time to do pre-visit and visits to various data and sample
collection thus times working behind schedule.
Impossibility of supplying the water totally via gravity due to the terrain in the region, the
area is hilly.
48
REFERENCES
AMCW, A. M. (2015). http://wsp.org/sites/wsp.org/files/publications/CSO-Kenya.pdf.
Brooks, V. A. (2015). Understanding Water Treatment Processes. Tech Directions.
https://www.google.com/search?
q=raw+water+treatment+plant&rlz=1C1CHBD_enKE770KE771&source=lnms&tb
m=isch&sa=X&ved=0ahUKEwiVsoOttavZAhXK1xQKHejlAkMQ_AUICigB&biw=1
366&bih=595#imgrc=KsXY5dEmJ2EFZM:. (n.d.).
Muya, F. S. (2005). Water Design Manual Kenya.
( 2015). Nyamira County Annual Development Plan 2014/2015. Nyamira County.
Nyamira-County. (2015). Nyamira County Annual Developmen plan 2015/2015. Nyamira:
County Government of Nyamira.
Ongwae, S. (2017, October 12). Nyamira Residents Give Nod to Sh5b Water Project.
Standard Media Group.
Vasna, A. G. (2015). https://www.google.com/search?
q=raw+water+treatment+plant&rlz=1C1CHBD_enKE770KE771&source=lnms&tb
m=isch&sa=X&ved=0ahUKEwiVsoOttavZAhXK1xQKHejlAkMQ_AUICigB&biw=1
366&bih=595#imgrc=KsXY5dEmJ2EFZM:.
WHO, W. H. (2016). Global Health Observatory Data. Use of Improved Sanitation Facilities.
49
APPENDIX 1
Operational Definition of Terms
Jabia: Unimproved traditional storage
Raw water: water in its natural state or untreated water; it consists water from the
ground, infiltration wells water, and water from lakes and rivers, generally, water from
unimproved sources.
SDGs: are a collection of 17 global goals set by the United Nations. The broad goals are
interrelated though each has its own targets to achieve. They cover a broad range of economic
and social concerns of its member states.
Kenya Vision 2030: is the national long-term development policy that aims to transform the
country into a newly industrializing, middle-income country providing a high quality of life
to all its citizens by 2030 in a clean and secure environment. The Vision comprises of three
key pillars: Economic; Social; and Political.
World Health Organization: a specialized agency of the United Nations that is concerned
with international public health and it’s a member of the United Nations Development Group.
i
APPENDIX 2
A Map of the Nyansiongo Area
ii
APPENDIX 3
Bill of Quantities
ITEM QUANTITY COST/UNIT TOTAL
PIPES (PVC) 1000 200 200,000
LABOUR 400 300 120,000
CEMENT 100 bags 800 80,000
BALLAST 5 Lorries 30,000 200,000
SAND 5 Lorries 30,000 200,000
WATER QUALITY
TESTS
20000 20,000
TOTAL 820,000
iii
APPENDIX 4
Sample I Raw water Test Results (Physiochemical analysis)
iv
APPENDIX 5
Sample I Raw water Test Results (Bacteriology analysis)
v
APPENDIX 6
Sample I Raw water Test Results (Physiochemical analysis)
vi
APPENDIX 7
Sample I Raw water Test Results (Bacteriology analysis)
vii
APPENDIX 8
Sample III Raw Water Test Sample Results (physiochemical analysis)
viii
APPENDIX 9
Sample III Raw Water Test Sample Results (Bacteriology analysis)
ix
x
APPENDIX 10
Budget and Workplan
Budget
ITEM COST( KSH)
Transport 3,000
Communication and Research 800
Printing and Binding 2,200
Data Collection 2,000
Miscellaneous 2,000
TOTAL 10,000
Work Plan
Project Concept Note
Project Proposal
Project Preparation
Data collection
Data Analysis and Design
Report Writing
Nov-17 Jan-18 Mar-18 Apr-18 Jun-18 Jul-18
Chart Title
xi