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TABLE OF CONTENT
TITLE PAGE
CERTIFICATION
TABLE OF CONTENTS PAGE ACKNOWLEDGEMENT i LIST OF FIQURES ii
SUMMARYa
1.0 MY EDUCATION TRAINING INTRODUCTION 1
1.1 Industrial training 1
1.2 Final year project 2
1.2.1 Design of counterfort earth retaining wall 2
1.2.2 Preliminary design 2
1.2.3 Bearing pressure analysis 3
1.2.4 Stability analysis 5
1.2.4.1 Check for overturning 5
1.2.4.2 Check for sliding 5
1.2.5 Final design and detailing 5
2.0 WORKING EXPERIENCE WITH ANBEEZ SERVICES LTDTHE PROJECT AREA
7
2.1 Location 72.1 Climate 72.3 Regional Geology 72.4 Vegetation 8
2.5 Population 8
2.6 Socio-economy 8
2.7 Topography 9
2.8 Rainfall 9
2.9 Access 9
3.0 EXISTING WATER SUPPLY SITUATION IN THE AREA 14
3.1 Water Sources 14
3.1.1 Rain Water 14
3.1.2 Surface Water 14
3.1.3 Ground Water 14
3.2 Water Uses 14
3.3 Water Source Contamination 15
4.0 PLANNING AND DESIGN - DATA COLLECTION 164.1 General 16
(a)
4.2 Methodology 16
4.2.1 Population Data 16
4.2.2 Water Quality Data 18
4.2.3 Meteorological And Hydrological Data 19
4.2.4 Surveying and Mapping 20
5.0 POPULATION ESTIMATION AND WATER REQUIREMENTS 21
5.1 General 21
5.2 Design Period 21
5.3 Population Estimation 21
5.4 Determination of Water Demand 22
6.0 WATER SUPPLY SYSTEMS – SELECTION AND DESIGN 23
6.1 Treatment Selection and Design 23
6.2 Quality Consideration and Choice of Source 23
6.3 Treatment Process 23
7.0 DESIGN SYNTHESIS OF WATER SUPPLY SYSTEMS 24
7.1 General 24
7.2 Development of Engineering Design of the Water Supply System 27
7.3 Design Criteria and Calculations 33
7.3.1 Selection and sizing of Pumping Equipment 34
7.3.2 Pump Controls and Instrumentation 3
6.7.1 Aluminium Sulphate 33
8.0 CHEMICAL DOSING SYSTEM 38
8.1 Aluminium Sulphate 38
8.2 HTH Powder Sulphate 38
8.3 Lime 38
8.4 Chemical Dosages 38
9.0 ELECTRICAL POWER REQUIREMENTS 39
10.0 CONCLUSIONS AND RECOMMENDATIONS 41
(b)
EXECUTIVE SUMMARY
In the process of executing this design project, the Consultant, carried out extensive field investigations and topographical surveys culminating in the final synthesis and design of the Etono Ikun Biakpan Water Scheme Project.
The highlights of this design report are as follows:
(a) Project Area
The project area consists of four major population centres, namely Etono-1,
Ikun, Biakpan and Etono-2. The total population of the area is projected from
1991 National Census to be 25,000 at present and this is expected to grow to
59,000 by 2034 (25 year’s time) at a growth rate of 2.8% per annum.
(b) Economy of the Area
The economy of the area is agrarian in nature, with yam farms, rubber
production, palm oil production and fishing. There are no industrial activities
in the area. Commercial activities exist but lack of good roads restricts
activities to a few months in the year.
(c) Access to Project Area
Access to the area is difficult due to the condition of the roads. There are two
main routes. One is from Akpet Central through an asphalted road up to
Okurike village on the eastern bank of the Cross River. From Okurike, the
Cross River has to be crossed by boat operated by the local people. The other
route is circuitous via Ikot Ekpene-Uyo-Bende-Ohafia and is the only route
through which motor traffic can get into the area.
(d) Existing Water Supply Facilities
There are presently no operational water supply facilities in the area.
However, a 25m3 overhead tank as found at Etono-1 but the associated
borehole(s) was not in use as at the time of site investigations on this project.
(e) Water Demand
The four towns served by the project are classified as semi-urban areas.
Accordingly a water consumption rate of 60 litres/capita/day as used in
estimating the water demand for the area in according with the National Water
Supply and Sanitation Policy as set out by the Federal Ministry of Water
Resources in 2000. Projected calculations indicate that present day (2009)
water demand for the area stands at about 1800m3/day and this is expected to
increase to 3500m3/day in 2034 (25 years’ time).
(f) Water Sources
(a)
Surface water was identified as the best option for sourcing of water for the
project. Two rivers, Cross River and Obana River, were chosen as sources of
raw water.
(g) Treatment Process
In consideration of the quality of water found, the following treatment process
was chosen for the design:
StorageCoagulationFlocculationSedimentationFiltrationDisinfection
(h) Location of Treatment Plants
The population of the project area was found to be concentrated in two axes
with Etono-1 and Ikun situated close to the bank of Cross River while Biakpan
and Etono-2 are close together at about 15 km away from Cross River. This
informed the decision to locate two separate water supply schemes of
capacities 2000m3/day for Etono-1 and Ikun, and 1500m3/day for Biakpan
and Etono-2. These are located near Etono-1 and Biakpan respectively. The
plants were designed on the basis of 12 hour operation
(i) Power Supply
There is no public power supply in the area; as such, the plants shall operate
using diesel generator sets. Three generator sets are to be provided, two
(200KVA and 100KVA) in Etono-1 and one (100KVA) in Biakpan plant.
(b)
2.0 THE PROJECT AREA
2.1 Location
The Biakpan, Ikun, Etono Mini Water Scheme in Biase Local Government Area of
Cross River State is proposed to supply potable water to the aforementioned
communities within the Local Government Area. The Towns of Etono 1 and Ikun are
communities located close to the bank of Cross River while Biakpan with its
neighbouring community of Etono 2 are located about twelve kilometres away from
the Cross River bank. The project area lies approximately between longitudes E7.925
to E8.033 and latitudes N5.580 and E5.650 as shown in Figure 2.3.
2.2 Climate
The project area has the typical tropical humid climate characterised by distinct wet
and dry seasons. These distinct climate seasons are created by the regular movements
of a zone of surface discontinuity between the Maritime – Atlantic air masses and dry
– Sahara air masses. The rainy season in the project area begins about February and
continues throughout October.
2.3 Regional Geology
The Cross River State is covered by the following geomorphical units: lower delta
plain, alluvial plain of the cross river, coastal plains, escarpment and hills – Obudu
and Oban hills.
The main geological formations in the project area are (FDLAR, 1985):
a) The coastal beach: This is primarily sand occurring in the southernmost part of
Akwa Ibom, along Ibeno and James town areas. The coastal sands are located
within the lower Delta plain.
b) The mangrove swamps: They occur along the network of creeks along the
coast in the vicinity of the estuary of Cross River, Imo and Qua Iboe River.
c) The river alluvium: This is located within the river plains – along the Cross
River, Qua Iboe and Imo River estuaries.
d) The coastal plain sands: Between the Cross & Imo Rivers where the coastal
plain exists, the underlying geological material consists of the coastal plain
sands. These tertiary sand deposits have different textures which range from
coarse to fine sands.
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e) Sandstone and Shales: These occur immediately north of the coastal plain
sands, at certain locations, the sandstone and shales are underlain by massive
deposits of limestone which are exploited by the cement industry.
f) The acid crystalline rocks: These occur extensively mainly in the northern part
of the Cross River State. The rocks are essentially metamorphic and igneous,
composed of granite,
g) Gneisses, schists, quartz, quartzites, undifferentiated basalt etc. Outcrops of
these rocks are very common in Akamkpa Local Government Area of Cross
River State.
2.4 Vegetation
The original vegetation of the project area has been greatly modified by human
activities. The vegetation zones from south – north in the project area are in the order:
mangrove, deltaic swamp forest, moist evergreen forest, and sub-mountainous forest
in the high Obudu plateau. Biakpan and the other communities in the project area lie
within the moist evergreen forest in the middle western part of the state with
evergreen vegetation.
2.5 Population
The population distribution of the area ranged from sparse to dense among the villages and scattered settlements. Most households are made up of a man, a wife and many children. Most of the inhabitants are Christians, although a few traditional worshippers were observed.
From the interview granted by one of the village elders he said their population is about 35,000 people. Data obtained from the national Population Commission indicate that the population of the area was about 18000 in 1991. This figure when projected using a population growth rate of 2.8% (as recommended by an official of the Population Commission) shows a present (2009) population of about 30,000 people. However, the project area, like most parts of the South South Zone of Nigeria, normally experience unprecedented migration of people into it during festive periods like Christmas, Easter, New Yam festivities etc.
Population growth rate of the project area is assumed to be typical of that in any other
Nigerian rural community. It should, however, be noted that population growth will
increase immediately when the water scheme is completed and this trend is expected
to continue for some time before it stabilizes to follow the normal pattern.
2.6 Socio-economy
The principal occupation of the people in these areas is farming. The primary crops
farmed are crops such as yams, cassava, beans, melon, plantain and vegetables. There
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is rubber plantation in this area too. Timbering is another activity that is taking place
in the nearby forest which generates a lot of economic activities.
Harvesting of palm nuts and subsequent production of palm oil is also prevalent in the area. There are some traders who trade on mostly food items. However, movement of people and goods is seriously impeded due to the absence of good motorable roads. As a matter of fact, the road between Etono 1 and Biakpan is impassable during the rainy season.
2.7 Topography
Topography of the project area is essentially undulating terrain with poor natural drainage system. Seasonal rivulets and small streams constitute the dendritic drainage pattern of the area, interconnecting pockets of swampy areas that generally drain into Cross River that eventually empties into south-eastern corner of the Atlantic Ocean.
2.8 Rainfall
Rainfall plays an important part in any water supply assessment and evaluation. In the project area, there is adequate rainfall throughout the year. The annual maximum rainfall in the area records as high as 1800mm. This provides a constant runoff to the stream channels, keeping then actively surcharged. There is however a great variability in monthly rainfall having its peaks between the months of July and September.
2.9 Access
Access to the project area is in poor condition. The access roads are neither tarred nor graded and also very rugged. The four main communities of Etono 1, Ikun, Biakpan and Etono 2 can be accessed through either Akpet Central off the Calabar–Ikom highway or through Ikot Ekpene – Odoro Ikpe – Bende – Ohafia – Asaga then to Biakpan or Ikun. It is to be noted that this latter route goes through neighbouring states of Akwa Ibom and Abia and is the only route through which vehicular traffic can access the area by land.
The road from Akpet Central is tarred but terminates at Okurike Village on the eastern bank of Cross River. To get to Etono-1 on the western bank requires crossing by local river transport. Thus, movement of construction materials through this route to the project area would prove difficult. This leaves only the alternative option of access through a labyrinthine route for the movement of construction materials and equipment through Ohafia in Abia State as stated earlier.
(3)
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Fig. 2.2: Map of Biase Local Government Area of Cross River State
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Figure 2.3: Project Area Layout Map
(6)
3.0 EXISTING WATER SOURCES AND SUPPLY SITUATION IN THE AREA
3.1 WATER SOURCES
The existing water supply sources for the inhabitants of the project area comprises
mainly of rain, streams and ground water.
3.1.1 Rain Water
As a common practice in the southern and coastal areas, there is a great reliance on
rainwater sources, firstly because there is an abundance of rain in its due season, and
secondly the rains spread nearly throughout the year. This provides a source for rain
water harvesting using drums, plastic containers and basins. The rain water source
helps to reduce the labour in trekking in search for water from the streams and rivers.
3.1.2 Surface Water
Other sources of dependable water are the streams and rivers in the area. Fortunately
the people of Etono and Ikun get their surface water source from Cross River and
other locations in the community. But unfortunately, the existing water sources are
fetched by trekking long distances to and from the streams with consequent loss of
time that is needed for other activities. Moreover, the amount of water taken to the
house is grossly inadequate for home uses.
The streams are slow moving thereby harbouring pathogenic organisms that constitute
source of all sorts of diseases which are causing a lot of health hazard to the people
living in these communities.
3.1.3 Ground Water:
There had been government intervention water projects in the area at Etono
(motorised borehole with elevated tank) and hand-operated borehole pumps at
Biakpan but these have long ceased to work. This means that the inhabitants have
reverted to traditional sources of water which are mainly based on ground water.
3.2 Water Uses
Essentially, the communities make use of the available water for domestic activities
such as drinking, cooking, bathing, washing, etc while agriculturally it is being used
for irrigation farming, processing of cassava and palm oil among other things. The
amount of water used for agricultural purpose in the area is very low since most of the
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agricultural activities depend on rain fed irrigation. Water is needed mostly in the
domestic gardens. Despite the fact that these people reside in areas with high amount
of rainfall, the potential for high water use is hampered by lack of adequate storage.
3.3 Water Source Contamination
A major concern in the area which may affect water quality is the risk posed by open
defecation on river and stream banks. Runoffs from precipitation on their way to the
stream channel do carry along these faeces into the stream thus contaminating it. The
practice poses a serious health risk to the people, although many of them may not be
aware of this danger.
Another source of contamination of surface water is the practice of fermentation of
cassava and other agricultural products in the rivers and streams.
Groundwater, though not very viable in the area due to the geologic form is also open
to faecal contamination
(8)
4.0 PLANNING AND DESIGN DATA COLLECTION AND FIELD INVESTIGATIONS
4.1 GENERAL
The success of any water supply scheme depends on the use of reliable existing data
over a length of time. The collection of data is complemented by investigations
carried out during such an exercise. A good field investigation does not only help in
making the best choice of the source of water for the scheme but it also ensures that
the design of such a scheme is built on a strong database to prove the required
stability, durability and efficiency.
4.2 METHODOLOGY
Thorough and conscientious field investigation and data collection were carried out to
provide suitable database for designing a technically feasible scheme. In the course of
collecting data for use in this project data were collected using, personal interview,
documentary, and observation methods. These methods though rigorous, helped to
ease the data collection process and ensured the accuracy of the data collected. The
data collected include:
(i) Population data(ii) Rainfall data(iii) Metrological data(iv) Hydrological data(v) Geological data
4.2.1 Population Data
The 1991 Census population data for the major communities of Etono-1, Ikun,
Biakpan and Etono-2 were obtained from the Calabar office of the National
Population Commission. The 2006 census figures were said to be unavailable since
they were not yet officially released. The official of the Population Commission
recommended that a population growth rate of 2.8% should be used for population
projection calculations for the area.
The population data for the whole of Biase Local Government Area was collected are
shown in Fig. 4.1. The relevant figures for the project communities were then
extracted and used for calculating population projections as shown in Fig. 4.2
(9)
Fig. 4.1: 1991 Census Figures for Biase Local Government Area
(10)
S/No Community
Population
1991 2009 2014 2019 2024 2029 2034
-18 0 5 10 15 20 25
1 Etono1 4,148 6,818 7,828 8,987 10,318 11,846 13,600
2 Ikun 6,104 10,034 11,520 13,225 15,184 17,432 20,013
3 Biakpan 6,179 10,157 11,661 13,388 15,370 17,646 20,259
4 Etono2 1,533 2,520 2,893 3,321 3,813 4,378 5,026
TOTAL 17,964 29,529 33,902 38,921 44,685 51,302 58,898Data Source: National Population Commission/1991 Census FiguresPopulation Growth Index is 2.8% as recommended by NPC official.
Fig. 4.2: Projected Population Figures for Project Communities
4.2.2 Water Quality Sampling Data
Water samples were taken from identified surface water sources on Cross River and
Obana Stream and sent for laboratory analysis at the Enugu State Water Corporation
Water Analysis Laboratory. A detailed chemical analysis of the water sample
covering the three perspectives of physical, chemical and bacteriological aspects was
carried out and the results are given below Tables 4.3 and 4.4.
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Fig 4.3: Laboratory Test Results for Water Sample from Cross River
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Fig 4.4: Laboratory Test Results for Water Sample from Obana River
(13)
4.2.3 Meteorological and Hydrological Data
4.2.3.1 Rainfall data
The major centres for rainfall data are those at Umudike and the Nimet Office in
Calabar.
The mean monthly Rainfall data and number of rainy days for the
area is given in table 4.5 below. This forms the basis for
establishing the hydrological potential of streams and rivers in the
area.
MonthNumber of Rainy
DaysMean Rainfall (mm)
Jan 2 41Feb 3 63Mar 9 122Apr 11 185May 13 236Jun 14 207Jul 15 317
Aug 14 272Sep 14 232Oct 13 254Nov 0 112Dec 2 41
ANNUAL 116 2,243
Table 4.5: Thirty-Year Mean Monthly Rainfall and Number of Rainy Days
The data on the meteorology of the area are summarised in the table below.
MonthMean Monthly Temperature
(0C)
Mean Daily Relative
Humidity (%)
Mean monthly Rainfall
(mm)
Mean Monthly
Evaporation (Class A Pan)
(mm)
Mean Monthly Potential Evapo-
transpiration (mm)
Jan 27.4 81 41 153 126Feb. 29.0 80 63 159 147Mar 29.2 82 122 170 147Apr 29.4 82 185 164 143May 28.0 83 236 161 141Jun 26.9 83 267 124 116Jul 26.2 87 317 121 107
Aug 26.7 87 272 125 110Sep. 26.8 87 333 125 113Oct. 27.1 85 254 144 123Nov. 27.6 84 112 145 136Dec. 27.9 81 41 155 137
ANNUAL
27.68 84 2,243 1756 1546
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Table 4.6: Meteorological Data For The Project Area
4.2.3.2 Hydrological Data
These include the stage-discharge data .from the hydrological state-discharge records
of Cross River (Table 4.7), collected from records, it was observed that the yearly
flow of the river is sufficient to maintain the demand by Project communities.
Month Stage (m)Discharge (cu.m/sec)
23.07.74 7.71 3072
26.07.74 7.13 2556
12.11.74 6.10 1716
28.12.74 3.31 369
18.03.75 2.45 169
11.08.75 7.96 3320
17.11.75 5.04 967
12.03.76 3.23 426
26.08.76 9.17 3787
23.09.76 8.65 4165
28.09.76 8.73 4122
ANNUAL 81.20 205.98
SOURCE: Inland Waterways, Lokoja
Table 4.7 Mean Monthly Stage-Discharge Measurements At Ikun Beach
The maximum recorded stage at Ikun Beach can be seen to be 9.17m.
4.2.4 Surveying and Mapping
Surveying and map work is critical for achieving proper design of water treatment
facilities because they constitute the basis for subsequent design activities which
include the Identification of suitable locations for the several components of the water
supply system with regards to space, elevation and desirable physical characteristics
of the landscape. The activities carried out under this project in this regard include
the following:
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(a) Collection of existing maps of the area: Items collected included the
topographic maps, administrative map of Biase Local Government Area,
satellite pictures and administrative map of Cross River. From these maps
several salient geographical features of the area such as access roads,
settlements, hills, rivers and streams were ascertained. In particular, the
satellite pictures and topographic maps were used to identify locations for
suitable high grounds for the water treatment plant sites prior to actual field
survey and investigation activities.
(b) Field reconnaissance visit: A team consisting of engineers, hydrologist and
surveyors visited the site several times to corroborate the findings from items
collected above. Meetings were held with the chiefs of Biakpan and Etono-2
as well as general discussions with ordinary inhabitants of the area. At the end
of these trips, suitable locations were identified as follows:
(I) Raw water sources on Cross River and Obana Stream near Biakpan
(ii) High grounds near Etono-1 and Biakpan for siting of Water Treatment
Plants.
(c) Topographical Survey: A team of surveyors was sent to site to carry out
detailed topographic survey in the identified locations in December 2008 and
February 2009. Modern survey equipment including Real-Time GPS Promark
3 Survey Equipment and hand-held GPS Instruments were deployed for the
exercise.
From the data obtained, site layout maps, contour maps and profile drawings
of the project area were produced. The acquired data were analysed with
computer softwares including special applications developed in-house by
Vibro Engineering Company Ltd to generate layout and contour maps as well
as profiles. Maps, drawings and data produced are presented in the
appendices.
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5. POPULATION ESTIMATION AND WATER REQUIREMENTS
5.1. General
The design of any efficient water treatment plant requires the knowledge of the
amount of water required by the community. This involves obtaining information as
to the number of people that will be served, and their per capita water consumption
together with the data on the domestic, industrial, commercial, agricultural, public,
social, institutional and fire-fighting water consumptions.
It is also important that any water supply scheme should be planned to serve the
present as well as the future needs of the community. Therefore future population
must be assessed by projections while designing the water supply scheme to last for a
given period of time (called the design period). This requires foresight and judgment.
5.2 DESIGN PERIOD
Prior to the construction of any project a decision has to be made as to the life span of
the project for which it will serve the community. Design period therefore, is the
number of years from the date of design to the estimated date when condition of
design will be reached. The problem then is how to forecast accordingly, as
accurately as possible, the population at the stipulated time in future based on the
chosen design period.
For the purpose of this project, the design period will be taken as 25 years, and the
scheme is expected to take off in 2010.
5.3 POPULATION ESTIMATION
Several methods of population estimation are available but in this project the
compound formula for population projection is used. The formula is given as
where,
Pn is the future (projected) population for the year n
Po is the present population
r is the population growth rate (in %)
n is the number of years from the base year
The population data collected from the National Population Commission are as shown
in the 1991 column of Fig. 4.1. Using the recommended population growth rate is
2.8% per annum, the projected population for the project communities were
calculated using the above formula and the results are as shown in Fig. 4.2. The
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calculation results indicate that the present population of the project area is about
30,000 and this is expected to double to about 59,000 by 2034 (in 25 years’ time).
5.4 DETERMINATION OF WATER DEMAND
Water demand represents the total quantity in equivalent of litres per capita per day
(1pcd) of water demanded for domestic, social, public, commercial, institutional,
agricultural, industrial and fire-fighting purposes excluding losses due to theft,
leakages and wastes where possible. It includes water required for drinking, bathing,
washing, cooking, laundering, flushing of toilet and gardening purposes.
The water demand rates as recommended in the National Water Supply and Sanitation
Policy are as shown in the following table:
CategoryWater Demand
(lpcd)
Rural Areas 30
Semi-Urban Areas 60
Urban Areas 120
Fig. 5.1: Categories of Water Consumption
The four main settlements in the project area fall under the semi-urban category and
hence we shall use the water demand rates of 60 lpcd for our design calculations.
Accordingly, Table 5.1 has been derived from Table 4.2 showing the projected water
demand requirements for the project during the design period of 25 years.
The selected value for per capita demand of 60 litres/capita/day is slightly higher than
the WHO requirement of 40 litres/capita/day for rural communities. It is however
envisaged that with the provision of potable water the per capita consumption per day
will be increased.
The projected water demand details cover a twenty-five-year design period (i.e. 2009
to 2034) in increment of five years for the entire project area. As shown in the table,
the total average daily demand for the entire project area is about 1800 m3/day in 2009
and this is expected to rise to 3500m3/day in the year 2034.
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S/No Town CategoryDemand
Rate (lpcd) YEAR 2009 2014 2019 2024 2029 2034
1 Etono-1 Semi-Urban 60 Population 6,818 7,828 8,987 10,318 11,846 13,600
Water Demand (m3/day)
409 470 539 619 711 816
2 Ikun Semi-Urban 60 Population 10,034 11,520 13,225 15,184 17,432 20,013
Water Demand (m3/day)
602 691 794 911 1,046 1,201
3 Biakpan Semi-Urban 60 Population 10,157 11,661 13,388 15,370 17,646 20,259
Water Demand (m3/day)
609 700 803 922 1,059 1,216
4 Etono-2 Semi-Urban 60 Population 2,520 2,893 3,321 3,813 4,378 5,026
Water Demand (m3/day)
151 174 199 229 263 302
TOTAL
Population 29,529 33,902 38,921 44,685 51,302 58,898
Water Demand (m3/day)
1,772 2,034 2,335 2,681 3,078 3,534
Fig 5.2: Water Demand Calculations
19
6.0 WATER SUPPLY SYSTEM SELECTION AND DESIGN
6.1 Treatment Process Selection and Description
In the selection of the treatment process, certain criteria had to be examined. These
include:
(i) Water Quality Criteria
(ii) Source Criteria
(iii) Treatment process itself, and
(iv) Construction materials.
6.2 Quality Consideration and Choice of Source
When a choice has to be made between various sources, the quality of the raw water
(hence the extent of treatment required) as well as the adequacy and reliability of the
sources, from a quantitative point of view, together with the potentiality for expansion
in the future must be considered (WHO standard, 1971).
The choice of a source requiring a minimum amount of treatment must always be
regarded as being preferable to the installation of sophisticated purification plant, in
addition to the cost of provision of a scheme. Considering the various sources
available for the purpose of this project, the a river and stream in the area being of
perennial nature were chosen as the surface water supply source.
From the water sample analyses results (Tables 4.3 & 4.4), it was apparent that the
physical, chemical and bacteriological characteristics of the samples do not deviate
greatly from the maximum permissible level published in WHO standard for drinking
water. Therefore, the treatment process of the surface water source shall be
coagulation, flocculation, sedimentation and disinfection.
6.3 Treatment Process
Given the surface water quality of the area, it is proposed that the treatment system
should be able to handle the iron content in the water. In addition, to protect the
consumers from water based and water borne diseases, the treatment system should be
able to handle the bacteriological aspects as well. In this respect the following
treatment process is proposed for adoption and design.
StorageCoagulationFlocculationSedimentationFiltrationDisinfection
In this process the storage tank is to allow for initial equalisation of flow through the
treatment plant to be met before going into coagulation and flocculation units.
20
The coagulation will help to increase flocs density, which through the process of
flocculation with appropriate velocity gradient selected will enhance flocs density
settled in the sedimentation tank.
The sedimentation process is designed to allow for a reasonable retention time for
settling to take place, from where clarified flow will pass to rapid sand filtration unit.
The filtration unit will ensure that short circuit flocs do not pass into the clear water
tank.
Subject to the final water quality parameters analysed, there is need to incorporate
aeration unit in the treatment layout
As a means of dealing with the bacteriological aspect of water, a filtration unit will be
adopted, the sizing of which will based on the throughput flows and filter system
design criteria.
Disinfection of the filtered water will be needed to protect treated water from harmful
bacteria.
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7.0 DESIGN SYNTHESIS OF WATER SUPPLY SYSTEMS
7.1 General
Analysis of data gathered from site has revealed several features of the project area
which must be considered in the synthesis of the engineering design of this project.
The following are some of the important funding:
(a) The main population centres in the project area are Etono-1, Ikun, Biakpan
and Etono 2 and area spread geographically over a wide area except for
Biakpan and Etono 2 which are adjoining each other. The other towns of Ikun
and Etono-1 are separated by considerable distances as shown in Table 7.1
below:
From ToRoad
Distance Km
Direct Distance
(km)
Biakpan Ikun 17.5 8.0
Biakpan Etono-1 10.5 12.5
Etono-1 Ikun 8.5 6.2
Biakpan Etono 2 0.8 0.8
Fig 7.1 – Geographical Spread of Project Towns
(b) The roads linking the various communities in the project area are just ordinary
earth roads that are in very poor state. The 10.5 km road between Etono-1 and
Biakpan can be particularly bad during the rainy season when it becomes
impassable to vehicular traffic. Sections of this road are also prone to heavy
flooding during the rainy season.
The road between Etono and Ikun appears to be not as bad as the Biakpan –
Etono road.
(c) Both Ikun and Etono-1 are located closer to the bank of Cross River and have
depended on the river for sourcing of water for domestic use for ages.
Biakpan and Etono-2 are however located a considerable distance away from
the Cross River. They presently depend mainly on streams and rain water for
their needs. Some of the streams are seasonal but one of them, Obana River,
is perennial and is the main source of water for the people during the dry
season.
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(d) Cross River is prone to annual flooding during the rainy season which lasts
from early May to early December. Site measurements and observations
indicate that the fluctuation in the level of the river ranges from about 5m to
13m above sea level – about 8m amplitude. This is illustrated in Fig 7.2
below which shows the ground profile along the road from Etono-1 to Etono
Beach. The water level (at its lowest) shown in this drawing was taken in the
month of February 2009 and the local people affirmed that was the lowest
level and would remain so until the rains come again when the level would
rise again. At the low water level, people can wade across to the other side of
the river. Sand bars abound all over the river bed at this period and the water
course is constrained to meander among them. Fortunately, it was found
that the water course runs by the river bank at Etono-1 Beach where the
bank is firm in a clayey formation - a situation which is considered ideal
for the siting of a raw water intake structure since the problems of
sanding/silting problems would be minimized.
Fig. 7.2: Longitudinal Profile of Road to Etono Beach
Illustrating Flood Level Variations on Cross River
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(e) It was found out from satellite pictures that a high ground exists close to the
Ikun junction on Etono-1/Biakpan road. Subsequent field topographical survey
confirmed this fact. Similarly, a high ground was located about 1.5km south
of Biakpan between Obana River and Biakpan town which could serve as the
site of a water treatment plant.
7.2 Development of Engineering Design of the Water Supply System
From the results of analysis of data obtained from site investigations/and topographic
survey, the following conclusion have been drawn:
(i) The geological formation of the project area does not offer conducive environment for sustained ground water exploitation for water supply purposes.
(ii) Cross River offers a veritable alternative source of surface water for water supply purposes to the project area. However, since the river is subject to great variations in flood levels during the rainy season the design of intake structures for water abstraction would require careful attention to ensure that such structures are accessible and functional all year round.
(iii) Biakpan and Etono-2 communities are located a considerable distance away from the Cross River and higher elevation and it would require pumping facilities and over 12.5 km of pipeline to transport treated water. From the Cross River bank to Biakpan and Etono-2.
(iv) Obana River, which is perennial, was identified about three kilometres south of Biakpan as being capable of meeting the design water demands of both Biakpan and Etono-2 which is approximately 1500 m3/day (see Table 5.2). Laboratory tests have indicated relatively high turbidity and bacteriological count compared with results of samples from Cross River, a result which is consistent with the slow flowing nature of the river as observed on site in the month of February. The adoption of Obana River as water source would greatly reduce the operational costs of pumping water all the way from Cross River.
(v) A convenient hill lies between Obana River and Biakpan in which to locate a water treatment plant. The level difference between hilltop and Biakpan is about 30m and is adequate head to supply water by gravity to the consumers below without the need for elevated tank in the towns.
(vi) Public power supply is not available in the project area and the plant would operate solely on generators.
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(vii) Access to the project area by road is only possible through Ohafia in Abia State. Therefore, the arrangements for bringing construction materials to site must be given proper consideration by contractors.
Detailed scrutiny of the above findings and subsequent calculations have led to the consideration of the following alternative configurations for siting water treatment plants under this project, thus:
Alternative 1
In Alternative 1, only one water treatment plant will be constructed to supply water to all the four communities benefitting from this project. This plant with a total design capacity of 3500m3/day (25-year period) will be sited along Etono-1-Ikun Rd some 2.2 km away from Etono-1 and will comprise of the following main components:
River Intake Works on bank of Cross River in the vicinity of Etono Beach. Raw water will be abstracted and pumped to the Water Treatment Plant.
250mm diameter Raw Water Transmission Line from the Intake Works to the Water Treatment Pant
Water Treatment Plant comprising of the following main components:(i) Aerator(ii) Flocculation/Clarifier(iii) Rapid Gravity Sand Filter(iv) Pump House(v) Underground Storage Tank(vi) Chemical Building(vii) Administration Building(viii) Staff Houses(ix) Gate House(x) Generator House
Power Supply Facilities consisting of two generator houses; one at the River Intake Works and the other at the Water Treatment Plant.
150mm dia Clear Water Rising Mains to Etono-1 (approx. 2.1 km long)
150mm dia Clear Water Rising Mains to Ikun (approx. 6.5 km long)
150mm dia Clear Water Rising Mains to Biakpan and Etono-2 (approx 11 km long)
Four (4 No) Overhead Storage/Distribution Tanks, one in each of the project towns of Etono-1, Ikun, Biakpan and Etono-2.
It should be noted that this alternative requires pumping of treated water from the water treatment plant through the rising mains to the overhead tanks in each project town.
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Alternative 2
Under this alternative, two separate water treatment plants are to be implemented; one near Etono-1 at the same location as in Alternative 1 as described above and the other at Biakpan.
The main advantages of this alternative include:
(a) Elimination of capital cost of providing pumping facilities including associated pipeline to transport water from Cross River to Biakpan and Etono-2.
(b) Elimination of maintenance and running costs of pumping equipment and pipeline referred to in (a) above. This aspect also includes elimination of possible vandalisation of the pipeline that would run through thick forest vegetation and poorly maintained road.
(c) The effects of breakdowns during operation will only affect a section of the project area.
The main components of the water supply facilities shall be as follows:
Alternative 2a
A water supply system shall be sited in the same locations as described i Alternative 1 but with a reduced capacity of 2000 m3/day. This plant shall supply water to Etono-1 and Ikun communities, and consists of the following components:
(i) River Intake Works about 2.2 km from the bank of Cross River from which raw water will be pumped to the water treatment plant.
(ii) 200mm dia Raw Water Pipeline 2.2 km long from the River intake works to the water treatment plant.
(iii) Water Treatment Plant of capacity 2000 m3/day with components as in the water treatment plant described in Alternative 1 above.
(iv) 100m3 Elevated Tank 9m high shall be provided to serve as storage/distribution tank to Etono-1 and Ikun by gravity. Thus, there will be no need for overhead tanks in those communities.
(v) 150 dia gravity pipeline to Etono-1 about 2.2km long
(vi) 150 dia gravity pipeline to Ikun x 6.5 km long.
(vii) Power Supply Facilities consisting of two generator houses; one at the River Intake Works and the other at the Water Treatment Plant
Alternative 2b
A second water supply facility of 1500m3/day capacity shall be built at Biakpan to supply water to Biakpan and Etono-2 communities. It consists of a River Intake Works on the bank of Obana River and a water treatment plant located about midway between Obana River and Biakpan Town.
The components of this plant are as in Alternative 2a except that there will no overhead distribution tank at the water treatment plant since the elevation at the plant has enough head to supply water by gravity to Biakpan and Etono-2. However, a
26
service water overhead tank of 25m3 capacity will be required for process, office and residential needs.
Thus, the main components of this system are as follows:
150mm dia Raw Water Transmission about 1.2km long Water Treatment Plant consisting of
o Aeratoro Flocculation/Clarifiero Rapid Gravity Sand Filtero Pump Houseo Service Water Elevated Tanko Underground Tanko One Generator House located at the Water Treatment Plant. Unlike the
plant at Etono, only one generator house is recommended with power extended to the River Intake Works via overhead power cables.
o Chemical Buildingo Administration Buildingo Staff House
150mm dia Gravity Distribution pipeline to Biakpan with a 100mm dia branch pipeline about 600m long to Etono-2.
S/N ComponentElevation
(m) asl1. Cross River Intake Works 3.002. Water Treatment Plant 31.0003. Etono 1 22.0004. Ikun 26.5005. Biakpan 28.8006. Etono-2 25.200
Fig 7.3: Relative Levels of Locations in Project Area
After due consideration of the various conditions and factors, it was decided that
Alternative 2 in which two separate plants are to be built offers the best option for
construction, operation and maintenance. The process diagrams for the two plants to
be located at Etono-1 and Biakpan are shown indigos 7.3 and 7.4.
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28
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7.3 Design Criteria and Calculations
From the population and water demand data shown in Fig. 5.2, we have constructed
Tables 7.5 and 7.6 to obtain the design data for the two designated water supply
systems, namely Etono1 Plant and Biakpan Plant. These tables reveal that the present
water demand for Etono-1 Plant is about 1000m3/day and is expected to double to
2000m3/day in 2034 (25 year’s time). For the Biakpan Plant, the corresponding
demands are about 800m3/day in 2009 and 1500m3/day in 2034.
A design period of 25 years is to be adopted for this project; hence all subsequent
calculations shall use the water demand of 2000m3/day for the Etono-1 Plant while
1500m3/day shall be used for the Biakpan Plant.
S/No Town YEAR 2009 2014 2019 2024 2029 2034
1 Etono 1 Population 6,818 7,828 8,987 10,318 11,846 13,600 Water Demand
(m3/day)409 470 539 619 711 816
2 Ikun Population 10,034 11,520 13,225 15,184 17,432 20,013
Water Demand (m3/day)
602 691 794 911 1,046 1,201
TOTALPopulation 16,852 19,348 22,212 25,502 29,278 33,613
Water Demand (m3/day)
1,011 1,161 1,333 1,530 1,757 2,017
Fig 7.6: Population and Water Demand for Etono-1 Plant
S/No TownYEAR
2009 2014 2019 2024 2029 20341 Biakpan
Population 10,157 11,661 13,388 15,370 17,646 20,2
59 Water Demand
(m3/day)609 700 803 922 1,059 1,216
2 Etono 2 Population 2,520 2,893 3,321 3,813 4,378 5,026
Water Demand (m3/day)
151 174 199 229 263 302
TOTALPopulation 12,677 14,554 16,709 19,183 22,024 25,285
Water Demand (m3/day)
761 873 1,003 1,151 1,321 1,517
Fig 7.7: Population and Water Demand for Biakpan Plant
In realisation of the fact that public power supply is not available in the project area,
the plants shall have to depend solely on diesel powered generator. With this in mind,
it is recommended that the design of the plants should be based on 12 hours operating
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period during which time enough water should be produced and stored in reservoirs.
The resulting base data for the two plants can therefore be summarised as follows:
Parameter Etono Plant Biakpan Plant
Design Capacity (m3/day) 2000 1500
Operating Period (hrs/day) 12 12
Design Flow Rate (m3/hr)
(l/sec)
166.67
46.30
125.00
34.72
Fig. 7.8: Basic Plant Design Parameters
In sizing the various component parts/structures of the plants, numerous calculations
were carried out with particular reference to criteria and considerations contained in
relevant British Standards and the American Water Works Association Codes.
Typical calculations relate to the following:
(i) Sizing of pipelines and channels to ensure that they have adequate capacities
for the design flows.
(ii) Sizing of chambers and various structures to provide space or volume required
to accommodate equipment, water and/or circulation of personnel.
(iii) Sizing of pumping equipment and determination of hydraulic/electrical loads.
(iv) Determination of chemical dosing rates and consumption data.
7.3.1 Selection and Sizing of Pumping Equipment
Pumps are essential components of any system where fluids are to be transported
from one level to a higher level. The parameters required for specifying a pump
include the flow rate (Q) and the total head (THD). A third parameter is the power
(P) which is dependent on both Q and H for a given liquid.
The flow rate of a plant or system is usually known while the total head which is a
function of two variables (static head difference, Hs and friction head losses, Hf) have
to be derived. The following relationship applies:
THD = Hs + Hf.............................................................(1)
Hs is obtained from field survey or measurement of the level difference between the
pump suction and the level at the pipe discharge end. The friction head loss in the
pipeline, on the other hand, is a function of the velocity of the fluid in the pipeline.
Various methods are available for calculating friction losses in pipes, but the method
used in this design is known as the Hazen William’s Formula and is given by the
expression,
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................................................................(2)
where V = velocity (m/sec)
C = Hazen William's Coefficient (taken as 140 for DI pipe)
D = pipe diameter (m)
L = Length of pipeline (m)
It can thus be seen from expression (2) above that the friction loss is a function of
three variables; velocity, Hazen William’s Coefficient and diameter of pipe.
C is a constant which is depends on the pipe material and its age.
The diameter, D, is derived from a rule of thumb (based on research findings) which
states that the velocity in the pipe of a pumped system should not exceed 2m/sec. It
can be demonstrated that friction losses increase to unacceptable values for velocities
exceeding this threshold.
Thus, the minimum pipe diameter, D, required to pass a flow, Q, at a velocity of
2m/sec is given by the expression:
................................................................(3)
Where D = pipe diameter (mm)
Q = flow rate (l/sec)
The velocity, V, in the pipe is given by the following expression:
...................................................................(4)
where V = velocity (m/sec)
Q = flow (l/sec)
D = pipe diameter (mm)
Equations (1) to (4) above form the basis for sizing of pumping equipment and require
that the following data be known:
Length, diameter and type/age of material of pipeline
Flow rate of fluid
Levels at Pump Suction and Pipe End
The above equations were used in the design to size pipelines and pumps of this
project and the results obtained are summarised below:
32
ParameterRaw Water
PumpsClear Water
Pumps
Flow Rate (l/sec) 46.30 14.00
Pipe Diameter mm) 200
Pipe Length (m) 2200 59
Level at Pump Suction (m) 4.000
Level at Pipe Discharge End (m) 33.000
Static Head, Hs (m) 29 9
Friction Head, Hf (m) 22.32 1.83
Total Head (m) 51.32 10.83
Motor Power (kw) 37 2.5
Fig 7.9: Pump Sizing Calculations for Etono Plant
ParameterRaw Water
PumpsClear Water
Pumps
Flow Rate (l/sec) 34.72
Pipe Diameter mm) 150
Pipe Length (m) 1200
Level at Pump Suction (m) 16.000
Level at Pipe Discharge End (m) 53.000
Static Head, Hs (m) 37.00
Friction Head, Hf (m) 27.78
Total Head (m) 64.78
Motor Power (kw) 35
Fig 7.10: Pump Sizing Calculations for Biakpan Plant
The calculations for pumps shown in the tables above are for transporting of the total
design flow of each plant. For operational reasons, it is however expedient to split the
flow of the Raw Water Pumps for each plant and deploy two pumps because the need
for the total design flow will not be required until the year 2034 (i.e. in 25 year’s time.
With reference to Tables 7.5 and 7.6, it will be further observed that half of the design
flow rate would meet water demand for the first ten years or more. It is therefore
expedient to use smaller pumps with attendant reduction in the size of associated
power requirements resulting in less switchgear rating.
The Clear water Pumps for Etono plant are quite small and need not be split. They
are designed to fill the 100m3 overhead tanks within two hours.
Therefore, the following configurations are recommended:
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Not
App
lica
ble
as F
low
is b
y G
ravi
ty
Etono Plant Biakpan Plant
Raw water Pumps
Clear Water Pumps
Raw water Pumps
Clear water Pumps
Qty2 No (1 duty , 1 Standby)
2 No (1 duty , 1 Standby)
2 No (1 duty , 1 Standby)
-
Pump Rating25 l/sec at 36m head
14 l/sec at 12m head
17.5 /sec at 45m head
-
Power rating 14 kw 2.5 12.5Kw -
Fig 7.11: Configuration of Pumps
7.3.2 Pump Controls and Instrumentation
Generally pumps shall be provided in pairs with one on duty and the other on standby.
Thus, each pump set shall have associated motor control panel with the following
facilities:
(i) Low level electrode shall be installed in the pump sump and interfaced with
the motor control circuits to protect the duty pump against dry run.
(ii) Pressure switch shall be installed on the pump discharge header which will act
to stop the duty pump when there is low flow in the pipeline. This situation is
anticipated where an operator at the water treatment plant shuts the valve of
the raw water pipe at the inlet works without informing the attendant at the
Raw Water Pumping Station.
(iii) Pressure gauges (range 0 to 5 bars) fitted with gauge cocks shall be installed
on the pump discharge pipes.
(iv) An flow meter shall be installed on the raw water pipeline for monitoring of
the output from the pumping station.
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8.0 CHEMICAL DOSING SYSTEM
Provisions shall been made for chemical dosing in the Water Treatment Plant using
Aluminium Sulphate, Chlorine (in the form of HTH solution) and Lime. The water
samples were taken in February in the dry season when the turbidity is naturally
expected to be at its minimum value. In spite of this, the results from Obana River,
which is the source of raw water to Biakpan Plant, showed a high level of turbidity. It
is also expected that the turbidity in both Cross River and Obana River would increase
greatly during the rainy season. Therefore it is recommended that Alum dosing
equipment should be rated to cope with maximum turbidity.
8.1 Aluminium Sulphate
Aluminium sulphate shall be made up as a 30% solution in two tanks, operating as 1
duty and 1 standby. Each tank shall be equipped with mixers. Each tank is sized to
provide approximately 12 hours dosing time at the maximum Alum dosing rate
8.2 HTH Powder
Chlorine in the form of HTH powder shall be dosed at two separate points in the
Treatment Plant viz: at the Raw Water Inlet Chamber and at the inlet weir to the clear
water underground. Two PVC tanks (operating as 1 duty and one standby) shall be
provided for the mixing and dosing of HTH. Each tank is sized to provide
approximately 12 hours dosing time at the maximum HTH dosing rate. Each tank is
to be equipped with a vertical mixer.
Two dosing pumps, operating 1 duty and 1 standby, shall be provided
8.3 Lime
Lime slurry is made up in two lime slurry tanks equipped with mixers, operating 1
duty and 1 standby. The dosing pipe work shall be arranged such that both pre-lime
dosing at the inlet chamber of the treatment plant and post-lime dosing at the inlet
weir to the underground tanks can be achieved using two dosing pumps operating one
duty 1 standby. Each tank is sized to provide approximately 12 hours at the
maximum lime dose rate.
8.4 Chemical Dosages
The design of dosing equipments was based o the following dosage rates
Pre-chlorine 6 mg/l
Pre-lime 15 mg/l
Alum 50 mg/l
Post-lime 15 mg/l
Post-chlorine 6 mg/l
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Calculation for chemical dosing is based on the following formula.
Pump Dosing rate is given by
...........................................................................(8.1)
Where R = Pump dosing rate (litres/hr)
Q = System Flow rate (m3/hr)
d = dosage (mg/l)
C = Concentration of chemical solution (%)
ChemicalDosage (mg/l)
Concentration %
Dosing Rate (l/hr)
ConsumptionDaily (kg)
Monthly (tonne)
Yearly (tonne)
Alum 50 30 278 100.0 3.00 36.50
Lime 15 15 168 30.0 0.90 10.95
HTH 6 20 50 17.1 0.51 6.26
Fig 8.1: Chemical Requirements for Etono Plant
ChemicalDosage (mg/l)
Concentration %
Dosing Rate (l/hr)
ConsumptionDaily (kg)
Monthly (tonne)
Yearly (tonne)
Alum 50 30 208 75.0 2.25 27.38
Lime 15 15 125 22.5 0.68 8.21
HTH 6 20 38 1.9 0.39 4.69
Fig 8.2: Chemical Requirements for Biakpan Plant
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9.0 ELECTRICAL POWER REQUIREMENTS
The project area is not covered by the National Power Grid System. Therefore, the
water supply schemes of this project have to provide their own power using diesel
generators.
Power is required for the following services:
(a) Raw water pumps
(b) Clear Water Pumps
(c) Backwash Pumps
(d) Air Blowers
(e) Dosing Pumps
(f) Lighting and Small Power in Buildings
(g) External Lighting
It is envisaged that the plants will not operate in the night. Therefore, external
lighting shall be required mainly for security reasons.
Two generator houses have been provided for the Etono Plant, one at the River Intake
Works and the other at the Water Treatment Plant. The Generator House at the Intake
Works is located about 230m away from the intake chamber which is on the bank on
Cross River. This is to locate the building away from the maximum flood plain.
Thus, there is need to provide the power lines (overhead aluminium conductors) for
about 250m to feed power to the submersible pumps installed in the Intake Chamber.
Biakpan Plant supplies clear water to consumers by gravity and therefore no clear
water pumps are needed except for a small pump for filling the service water tank.
For cost and security reasons, it was considered not necessary to provide a separate
pump house for the Intake works at Obana River. Instead, only one power house is
provided at the Water Treatment Plant and power shall be supplied via overhead
power cables to the submersible pumps at the intake chamber.
The estimated power ratings for the generators required in the project as follows:
Etono Plant Biakpan Plant
Intake Works 100KVA -
Water Treatment Plant 200 KVA 150KVA
Fig. 9.1: Generator Requirements
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10 CONCLUSIONS AND RECOMMENDATIONS
The highlights of this design report are as follows:
(j) Project Area
The project area consists of four major population centres, namely Etono-1,
Ikun, Biakpan and Etono-2. The total population of the area is projected from
1991 National Census to be 25,000 at present and this is expected to grow to
59,000 by 2034 (25 year’s time) at a growth rate of 2.8% per annum.
(k) Economy of the Area
The economy of the area is agrarian in nature, with yam farms, rubber
production, palm oil production and fishing. There are no industrial activities
in the area. Commercial activities exist but lack of good roads restricts
activities to a few months in the year.
(l) Access to Project Area
Access to the area is difficult due to the condition of the roads. There are two
main routes. One is from Akpet Central through an asphalted road up to
Okurike village on the eastern bank of the Cross River. From Okurike, the
Cross River has to be crossed by boat operated by the local people. The other
route is circuitous via Ikot Ekpene-Uyo-Bende-Ohafia and is the only route
through which motor traffic can get into the area.
(m) Existing Water Supply Facilities
There are presently no operational water supply facilities in the area.
However, a 25m3 overhead tank as found at Etono-1 but the associated
borehole(s) was not in use as at the time of site investigations on this project.
(n) Water Demand
The four towns served by the project are classified as semi-urban areas.
Accordingly a water consumption rate of 60 litres/capita/day as used in
estimating the water demand for the area in according with the National Water
Supply and Sanitation Policy as set out by the Federal Ministry of Water
Resources in 2000. Projected calculations indicate that present day (2009)
water demand for the area stands at about 1800m3/day and this is expected to
increase to 3500m3/day in 2034 (25 years’ time).
(o) Water Sources
Surface water was identified as the best option for sourcing of water for the
project. Two rivers, Cross River and Obana River, were chosen as sources of
raw water.
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(p) Treatment Process
In consideration of the quality of water found, the following treatment process
was chosen for the design:
StorageCoagulationFlocculationSedimentationFiltrationDisinfection
(q) Location of Treatment Plants
The population of the project area was found to be concentrated in two axes
with Etono-1 and Ikun situated close to the bank of Cross River while Biakpan
and Etono-2 are close together at about 15 km away from Cross River. This
informed the decision to locate two separate water supply schemes of
capacities 2000m3/day for Etono-1 and Ikun, and 1500m3/day for Biakpan
and Etono-2. These are located near Etono-1 and Biakpan respectively. The
plants were designed on the basis of 12 hour operation
(r) Power Supply
There is no public power supply in the area; as such, the plants shall operate
using diesel generator sets. Three generator sets are to be provided, two
(200KVA and 100KVA) in Etono-1 and one (100KVA) in Biakpan plant.
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PHOTOLOG
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DRAWINGS
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