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GROUNDWATER QUALITY:
A CASE STUDY OF AMUWO ODOFIN LOCAL
GOVERNMENT AREA
BY
AKWARA NOREDIA
000402032
Being a project submitted to
The department of Civil and Environmental Engineering
Faculty of Engineering
University of Lagos
In partial fulfilment of Requirements for the award of the degree
of Bachelor of Science in Civil Engineering
September 2006
TABLE OF CONTENTS
Certification
Dedication
Acknowledgements
Abstract
CHAPTER ONE: Introduction
1.0 Introduction
1.1 Background to the Study
1.2. Description of case study area
1.3. Importance of the Project
CHAPTER TWO: Literature Review
2.1 Groundwater
2.2 Groundwater quality from deep wells
2.3 Groundwater contamination
2.3.1 Domestic/Municipal sources of groundwater
contaminants
2.4 Effect of Urban Development on groundwater
- 2.4.1 Relationship between Municipal landfills and
Groundwater pollution
2.5 Water supply system in Amuwo Odofin LGA
2.6 Saltwater intrusion in deltaic terrains
2.6 Water quality standards
2.7 The geology of the case study area
- 2.7.1 Hydrogeology
CHAPTER THREE: Methodology
3.1 Methodology
- 3.1.1. Meetings with the local government officers
- 3.1.2. Survey carried out in case study area
- 3.1.3. Field Investigation
3.2 Sources of Data
3.3 Parameters
3.4 Field Study
3.5 Laboratory Analysis
CHAPTER FOUR: Discussion of Results
4.1 Descriptions of Location
4.2 Discussion of Physio-chemical parameters
4.3 Discussion of results
4.4. Groundwater Remediation
-4.4.1 Programs of activities for Groundwater Remediation
-4.4.2 Groundwater remediation from Point sources
CHAPTER FIVE: Conclusion and Recommendation
5.1 Conclusion
5.2 Protection/Prevention of Groundwater pollution
5.3 Recommendation
REFERENCES
APPENDICES
CERTIFICATION
This is to certify that this project “GROUNDWATER QUALITY AND
REMEDIATION OF GROUNDWATER POLLUTION: A CASE STUDY OF
AMUWO ODOFIN LOCAL GOVERNMENT AREA” was carried out by
AKWARA NOREDIA and supervised by DR. E.O LONGE
Student: AKWARA NOREDIA
Signature:…………………………….
Date:………………………………….
Supervisor: DR. E.O. LONGE Head of Department: PROF. SALAU
Signature:…………………... Signature……………………………
Date:………………………… Date:…………………………………
DEDICATION
This project is dedicated to the Loving Father, in whom I repose all trust.
And to the memory of Emmanuel O. Akwara
ACKNOWLEDGEMENT
To the Akwara family. Thanks for the support you gave me.
ABSTRACT
Groundwater pollution is a growing problem in most countries.
CHAPTER ONE:
INTRODUCTION
1.1 Background to the Study
The quality of water available to a community is closely related to the health
issues of the community. An important factor in the growth of a community is
its accessibility to potable water. In many countries of the world including
Nigeria, groundwater constitutes the main source of drinking water. But in
recent decades, the groundwater quality has very much deteriorated due to rapid
industrialization and human mismanagement. The sources of water in Lagos
state are from surface water and groundwater. Since 1910 to date, the main
concern of the authorities managing water supply to Lagos has always been
how to increase the supply of potable water due to the ever increasing
population of Lagos as a commercial nerve centre of the nation's economy. The
population of Lagos is growing rapidly daily with more people settling down
than moving out and the effect of this large scale growth is felt on the
environment. At present, Lagos has a population of about 15 million.
In the past, surface water was the main source of water supply for domestic and
industrial use. Awareness of the large store of the water underground led to the
implementation of water supply units based totally on groundwater.
Groundwater is of major importance to civilization; because it is the largest
reserve of drinkable water in regions where humans can live. Now, water
resources in Lagos state for domestic, industrial and commercial uses, are
becoming scarce as a result of pollution of water bodies by wastewater, which
contains inorganic compounds, bacteria, etc. The effects of on-lot sewage
disposal systems in densely populated areas surface runoff from developed
areas, industrial site contamination are some of the problems facing
groundwater quality in Lagos state.
In Amuwo Odofin and Festac, the population housing is divided into three
types:
o Blocks of three bedroom family units (flats)
o Semi-detachable houses
o Fully-detached houses and privately built homes
Most of the households depend on dug wells and boreholes for their
water supply. The problem lies in ensuring that the community gets clean,
potable water. Pollution can cause problems with the taste, odour and colour in
water. Many of the chemicals that enter the water with runoff and seepage are,
even in minute amounts, toxic to human health and can alter ecosystems by
destroying fish, wildlife and plants. Heavy metals, pesticides, chlorinated
hydrocarbons are typical examples.
The majority of the community wells and boreholes are provided for by the
individuals using it.
1.2. Description of case study area
Amuwo Odofin local government area is situated in Lagos state, the most
populous state in Nigeria. The population of Amuwo Odofin LGA is estimated
to be over 270,000 persons and over 80% of this value obtains their water from
private wells and boreholes. In more developed countries, community water
supply systems are checked by professional staffs that are required by law to
ensure that water supplied to these homes is safe for drinking, but in Nigeria,
that is not the case. It has now become the responsibility of the users of the well
to keep their water free from health hazards. Safe water cannot be taken for
granted.
There have been cases of physiochemical pollution of private well water. This
has been the case since the local government does not provide water to the area
and households have been left to source for their own water supply, taking
whatever is available, giving rise to either no water treatment or over-treatment
of the water due to lack of knowledge.
The placement of wells and boreholes for domestic use is very important as its
proximity to septic tanks can lead to contamination from the tanks. The
construction of wells is also important. An improperly constructed well could
lead to contamination at the surface of the well or ground. Wells in Festac town
are susceptible to this, as they are of hand dug, ring construction type, going
down 3 or 4 rings to the ground surface.
Amuwo Odofin local government area is a mostly residential area with about
35% of the area given to small businesses and small-scale, privately owned
industries. The case study area comprises of two major sections:
- Amuwo Odofin, Raji Rasaki Estate, Jakande Estate and their environs
- Festival town, also known as Festac, which is divided into old Festac and
Festac Phase II.
1.4. Aims of the project
The aim of this project is to obtain the exact level of contamination of
groundwater resources in Amuwo Odofin local government area. Other
objectives of this project are:
1. To identify the characteristics of each groundwater sample, by
ascertaining the amount of compounds and elements that explains its
contamination.
2. To identify environmental and health hazards posed to the community
due to contaminated groundwater.
3. To identify the characteristics of each groundwater sample, by
ascertaining the amount of compounds and elements that explains its
contamination.
4. To determine anthropogenic activities affecting the quality of
groundwater in the area.
5. To determine areas of greatest educational need towards the inhabitants
of Amuwo Odofin LGA.
6. To propose solutions which shall include corrective measures to guard
against groundwater contamination and efficient methods for water
treatment and distribution in the case study area.
7. To identify different models for groundwater pollution abatement and
study borehole techniques, prevention and remediation.
8. To determine homeowner, and attitudes towards groundwater, that might
affect groundwater quality.
9. To propose solutions which shall include corrective measures to guard
against groundwater contamination and efficient methods for water
treatment and distribution in the case study area.
1.5. Importance of the Project
The offices of the local government in Amuwo Odofin have no information
gathered on the groundwater quality of the area. Knowledge of the diverse ways
by which groundwater pollution occurs will lead to proper awareness of the
need to protect it and comprehension on how to prevent it. Reduction in the
intensity of pollution accordingly reduces the cost of water treatment so as to
meet the required standards of quality for its many uses and also reduce health
risks. There is a need to understand the hydrogeology of the area, to know the
constituents of the groundwater in the area and understand how human
activities affect the quality of groundwater. This is an important objective in
improving the overall health of the inhabitants of the case study area. Also
information gathered on the water quality will affect urban planning and
distribution of financial resources towards all water treatment plants in the
zone.
1.6. Scope of the Project
The scope is limited to Amuwo Odofin local government area, parameters
being general constituents of groundwater pollution, covering domestic and
some industrial pollutants.
CHAPTER TWO:
LITERATURE REVIEW
2.1. Groundwater
Groundwater can be defined as water that has percolated from the surface that is
stored underground in pore spaces in soils and sands; and cracks in rocks. Very
deep-lying groundwater can remain undisturbed for thousands or millions of
years. Most groundwater lies at shallower depths, however, and plays a slow
but steady part in the hydrological cycle. Worldwide, groundwater accounts for
about one per cent of the Earth's water, or about 100 times more than the total
volume of all lakes and rivers.
Groundwater is usually cleaner than surface water due to the fact that certain
contaminants in the water are filtered off by the different soil strata it passes
through before reaching the water stored underground. Groundwater can be
tapped from aquifers by the use of wells and boreholes. Groundwater
contamination occurs as a result of either direct or indirect human activities or
indirectly through alteration of the ground which water passes through. Sewage
is a very common type of groundwater pollution.
2.2. Groundwater Quality from deep wells
It has been observed that deep-well sources satisfy municipal water quality
factors of safety, appearance, taste, temperature and odours. Well-water
contains large concentrations of iron, manganese and hard water. Shallow wells
recharged by a nearby water source may have quality characteristics similar to
deep wells or may relate more closely to the watercourse quality. A sand
aquifer adjacent to a river may act as an effective filter for removal of organic
matter and as a heat exchanger for levelling out temperature changes of the
recharge water seeping into it.
Ground water in the majority of properly constructed drilled wells is bacteria
free. To ensure protection from any health risk, it is important for the public to
understand something about micro organisms and how they might impact health
of any community. The occurrence of bacteria in water is common, treatable,
and in most cases, preventable. The ideal situation is to have no bacteria in
drinking water, although most bacteria in well water are harmless and pose little
health risk.
2.3. Groundwater Contamination
Groundwater contamination is the degradation of natural water quality as a
result of human activities, and pollution occurs when contaminant concentration
levels restrict the potential use of groundwater. There is a difference between
well contamination and aquifer contamination. If a bacterial water quality
problem is detected, it could be occurring in the water system, the well or (less
likely), and the aquifer. There are several indicators and indicator organisms,
bacteria, pathogenic organisms and inorganic constituents which can pollute
water. Pollution is not always visible. In groundwater, which is the most
important source of water supply in many countries, pollution is difficult to
discern. But the effect of pollution is always severe whether immediately or
over a long period.
There are three sources of groundwater contamination and they are:
Point Sources: These may include industrial waste landfills, sanitary
landfills, sewage lagoons and leachates and mining waste dumpsites. Point
sources in this country come from most waste management facilities of any
kind. They are concentrated point sources.
Non-point sources: These include urban runoff; and aerial application of
pesticides and herbicides, and other agricultural practices.
Natural Processes of Mineralization: Underground water is in contact with
soil formations and dissolves minerals and salts. The water quality of
groundwater depends on the mineral rock formation. (Venugopaln &
Tanwar, 1981)
From the above, sources of groundwater pollution may be grouped as
follows:
- Domestic/ Municipal wastes: Refuse, sewage disposal systems,
garbage.
- Industrial sources: Mining activities, underground tanks and pipeline
leakages, liquid chemical leakages, used water, rain infiltrating
through industrial waste disposals.
- Agricultural sources: Irrigation, fertilizers, animal wastes, pesticides
and feedlots.
- Saltwater intrusion
- Surface runoff (Fried,1987)
Pollutants can be divided into chemical, physical and microbiological
pollutants. Chemical pollutants can be divided into non-persistent (degradable)
and persistent (pollutants which degrade slowly). Persistent pollution is the
most rapidly growing type of pollution and includes substances that degrade
very slowly or cannot be broken down at all; they may remain in the aquatic
environment for years or longer periods of time.
Persistent pollutants include some pesticides (e.g. DDT, dieldrin), some
leachate components from landfill sites, petroleum and petroleum products,
PCBs, dioxins, polyaromatic hydrocarbons (PAHs), radionuclides, metals such
as lead, mercury, and cadmium. The damage they cause is either irreversible or
reparable only over decades or centuries.
Non persistent pollutants include domestic sewage, fertilisers and some
industrial wastes. These compounds can be broken down by chemical reactions
or by natural bacteria into simple, non-polluting substances such as carbon
dioxide and nitrogen. However if the pollution load is high, this development
can lead to low oxygen levels; fortunately this damage can be reversible.
Table 1: List of possible groundwater pollutants and pollution
indicators
Total dissolved solids
C O D ( chemical oxygen
demand)
B O D ( biological oxygen
demand)
Carbon (organically linked)
Hydrogen (organically linked)
Nitrogen
Detergents
Phenols
Oxygen
Sulphates (SO2-4)
H2S
Nitrates (NO3-)
Nitrites (NO2)
Ammonium (NH4)
Arsenic
SiO2
Conductivity
Free CO2
Bicarbonates (HCO3)
Iron (Fe2+ And Fe3+)
Manganese
Sodium
Potassium
Calcium
Magnesium
Total Hardness
Chloride
Fluoride
Phosphate (HPO4)
Zinc
Lead
Copper
Temperature
pH
Redox potential
(Source: Fried, 1987)
2.3.1. Domestic/Municipal sources of Groundwater contaminants
Anthropogenic activities have been established as having impacts on ground
water. The most likely sources of groundwater contamination in the case study
area are from domestic/ municipal wastes and natural mineralization processes.
From information gathered through testing by private water purification and
supply companies in the local government area, it has been observed that the
groundwater has these impurities:
- a high iron (Fe2+ and Fe3+ ions) content
- Pathogenic organisms like Shigella (bacteria), Giardia lamblia (protozoa)
and Cryptosporidium.
- Indicators and indicator organisms like Escherichia coli (E. coli)
- A moderately acidic pH number, varying in areas from 6.1 to 6.8
- An degree of salinity present in the water
Exact values of these have not been determined. After tests carried out during
the course of this study, more pollutants and impurities will be added to these
and their precise amounts in the groundwater of the study area will be
determined. Certain pollutants like Volatile Organic Compounds (VOCs) are
not commonly found in non-industrial areas.
Festac town was designed with a central sewer system, but the efficiency of this
has depreciated with age and lack of maintenance and as a result, septic tanks
are the main form of domestic sewage treatment in the case study area. In other
parts of Amuwo Odofin LGA, septic tanks are the only form of domestic
sewage treatment. This scenario has led to the presence of faecal coliforms and
higher microbial loads in the surface waters and groundwater of the area. In
rainy seasons, starting from midway March to September, with the heavy rains
usually experienced in the area, cases of the septic tanks of private homes
overflowing has been known. There is a landfill located in 7 th avenue and this
is a point source of groundwater contamination.
Where the subsurface geology permits rapid downward movement of water
from the surface, or where the ground water sources are tapped near the surface,
aquifers may be vulnerable to pollution. Shallow dug wells, or drilled wells in
which the well casing is not properly grouted (sealed), are particularly
susceptible to contamination.
2.4. Effect of Urban Development on Groundwater
With urban development comes increased dependence on groundwater and
more amounts of water being consumed daily. Lagos state’s per capita demand
is listed as 120 to 150l.c.d. In areas where groundwater is the only source of
water, town development placed unfavourable changes in groundwater. Bujwid
(1981) presented a paper which stated that these changes usually found
expression in the increase of some nitrogen compounds, trace elements and
bacteriological contamination.
In Amuwo Odofin LGA, while precise values of population have not been
ascertained, it is generally held that the amenities planned for by the housing
authorities are inadequate for the use of the current inhabitants. Over-population
is a known problem. With the increase in the population, and lack of
governmental forecast, several private wells and boreholes were sunk.
Currently, the local government is not aware of how many exist in the area.
Privately owned homes have either a well or borehole each, while the flats
make use of a minimum of two (2) wells and three boreholes. More boreholes
are being constructed monthly as more people move into the area.
It has become difficult to also control solid waste disposal in the area. Private
sector participation has come in to undertake this task, as the internal squabbles
between the state and federal government as to under whose jurisdiction Festac
town fell under had affected the release of funds in the past.
2.4.1. Relationship between Municipal landfills and groundwater pollution
A sanitary landfill is a method of solid waste disposal that should function
without creating a nuisance or hazard to public health or to the environment.
Landfills can also be classified as hazardous (toxic) or as municipal by the types
of waste accepted. Over the last 30 years a number of problems have been
recognized at landfill sites, including contamination of nearby surface waters
and underlying groundwater by landfill leachates. Municipal landfills have
impacted groundwater resources especially hydro-geological environments
where impacts are expected to be greatest, for example where the water table is
shallow, where groundwater is of good quality and flow is rapid.
2.5 Water Supply system in Amuwo Odofin LGA
Festac town was constructed in 1977-78. It was a planned urban development
by the federal government of Nigeria. For the first ten (10) years of its
existence, water was supplied to its inhabitants by the state water board.
Amuwo Odofin LGA is still on the water grid. Of recent, the local government
has erratic supply of water. Though Amuwo Odofin LGA is bordered by water
bodies (the canal), it is generally assumed that the surface water is very
polluted; consequently, groundwater is preferred and many residents have
decided to get their water supply from privately constructed shallow wells and
boreholes. “The definition of shallow or deep water well will vary with the
hydro geological conditions considered to be the standard with the area”
(Clarke, 1996). For this project, Shallow wells refer to water wells not more
than 70m deep, which must be completed with steel casings and screens
(Obiora and Onwuka, 2005). The type of wells constructed in Festac and
Amuwo Odofin are of the Hand dugs variety and these are “more vulnerable to
pollution than a drilled borehole” (Clarke, 1996). The wells in Festac town
range from depths of 4m to 8m, while wells in Amuwo Odofin go as down
90m. Boreholes in the area are of almost the same depth as wells (some are
drilled deeper to reach a cleaner source of water). The wells are of concrete ring
type, with a natural layer of sand at the bottom. Wells generally improve with
age, although they need to be maintained and checked annually for breaks in the
casing that might lead to contamination of the water well.
2.5. Saltwater Intrusion in Deltaic terrains
Saltwater intrusion is defined as the introduction, accumulation, or formation of
saline water in a water of lesser salinity. It is one of the most common problems
in coastal aquifers, i.e. the induced flow of salt water into fresh water aquifers
caused by groundwater development. The intrusion of seawater into coastal
aquifers is a widespread phenomenon that increasingly causes the problem of
groundwater salinity. In places where groundwater is being pumped from
aquifers that are in hydraulic connection with the sea, the induced gradients
may cause the migration of salt-water from the sea toward the well. The key to
controlling this problem is to maintain the proper balance between water being
pumped from the aquifer and the amount of water recharging it. Constant
monitoring of the salt-water interface is necessary in determining proper control
measures.
The increased use of groundwater causes the salt-water interface to move inland
and closer to the ground surface. In the past, many communities coming across
salt-water intrusion problems simply set up new production wells further inland.
This only complicated the problem. Saltwater intrusion refers to surface water
contamination while saltwater encroachment refers to the contamination of
ground water. The processes involved in these intrusions can result from natural
phenomena or human-influenced activities, particularly dredging, and may
assume a variety of specific forms. The concern about saltwater intrusion arises
from the environmental damage or water use impairment that may result
because of the presence of salts in ground or surface waters. Excessive salt
concentrations can render water unfit for consumption by humans and animals
as well as impair the growth of plants. Agricultural and industrial uses of water
can also be impaired by high salinity levels. When no freshwater is available,
slightly saline waters may be viewed as having acceptable quality for some
purposes.
There are a number of possible effects of saltwater contamination, as indicated
by the following:
- Enhancement of the toxicity of other toxic chemicals dissolved in water may occur.
- Saturation levels of dissolved oxygen decrease with increasing salinity,
thus potentially accentuating poor dissolved oxygen conditions in
streams.
- Permeability of soils being altered, thus altering aquifer recharge
conditions.
- Large costs may be incurred in the treatment of saline water in order to
make it usable.
- Increasing salinity may force the use of alternate sources of water which,
in turn, may have adverse consequences.
Exhaustive urban, industrial and agricultural activity relies heavily on
exploitation of groundwater resources, and in recent years, this reliance has led
to increasing levels of salinity in groundwater systems. There has been a
reported case of saltwater intrusion in Festac in recent years, but it was not well
documented.
2.6. Water quality standards
Water quality standards vary according to each country, with the WHO setting
the international standards for water quality. According to Cohn et al, these
standards stretch from aesthetic quality (taste, odour, turbidity, hardness and
colour) to Health aspects (ranging from disease agents to organic and inorganic
contaminants).
Table 2: WHO Standards for quality of water
Physical WHO standard
P E Turbidity (ppm)ColourTaste and Odour
5 25 5 50 Unobjectionable
Chemical
pH 7-8.5 < 6.5 or> 9.2
Total Solids (mg/l) 500 1500
Total Hardness (as CaCO3) (mg/l)
-- --
Calcium (as Ca) (mg/l) 75 200
Magnesium (mg/l) 50 150
Iron (as Fe) (mg/l) 0.3 1.0
Manganese (mg/l) 0.1 0.5
Copper (as Cu) (mg/l) 1.0 1.5
Zinc (mg/l) 5.0 15.0
Chlorides (as Cl) (mg/l) 200 600
Sulphate (as SO4) (mg/l) 200 400
Phenolic substances 0.001 0.002
(mg/l)
Fluorides (mg/l) 0.5 1.0 to 1.5
Nitrates (mg/l) -- 50 to 100
Arsenic -- 0.2
Lead -- 0.1
Cyanides -- 0.01
Radio-activity (as Alfa
Emmitter (µc/ml)
-- 10-9
Bacteriological
Five 10ml portions Not more than 10% of all portions examined shall show presence of coliform bacteria. MPN≤ 1 per 100ml. No two consecutive samples shall have the presence of coliform bacteria
P= Permissible E= Excessive
Source: J.P. Sanjaygadhvi
Table 3: Federal Ministry of the Environment, Nigeria: Standards for
Groundwater Quality
PARAMETER FMEnv StandardTurbidity (NTU) NS
*Color (Pt-Co)7.00
*pH 6 - 9Temperature (oC) NS*Total Dissolved Solids (TDS) (mg/l)
2000
*Total Suspended Solids (TSS) (mg/l)
30.0
Total Solids (TS) (mg/l) 20-30.0Conductivity (S/cm) NSDissolved Oxygen (DO) (mg/l) NS*Biological Oxygen Demand (BOD) (mg/l)
NS
*Chemical Oxygen Demand (COD) (mg/l)
NS
Total Alkalinity (mgCaCO3/l) NS
Bicarbonate Alkalinity (mgCaCO3/l) NSCalcium (Ca2+)(mg/l) NSMagnesium (Mg2+) (mg/l) NSTotal Hardness (Ca2++ Mg2+) (mg/l) NSChloride (Cl-) (mg/l) 600.00Nitrate (NO3
-) (mg/l) 20Sulphate (SO4
2-) (mg/l) 500Phosphate (PO4
3-) (mg/l) 5.00Potassium (mg/l) NSSodium (mg/l) NSIron (Fe) (mg/l) 20Nickel (mg/l) Less than 1Lead (mg/l) Less than 1Manganese (mg/l) 5.00*Oil and Grease (mg/l) 10.00*Coliform (cfu/100ml) 400
2.7. The Geology of the case study area
The geologic conditions of a site must be determined to assess groundwater
vulnerability. For example, layers of gravel above the groundwater area do not
offer much protection against percolation or leaching. Layers of sands and silts
do much to filter percolating water, depending on grain size distribution. A
layer of clay generates an effective filter for many chemicals. A steep slope in
the geology of an area increases the potential for surface runoff and the
subsequent movement of chemicals to other vulnerable areas.
Water and wetlands cover over 40% of the total land area within Lagos
state. A considerable part of the state area is made up of lagoons and creeks.
Lagos state is naturally made up of depositional landform, which include;
wetlands, barrier islands, beaches, low-lying tidal flats and estuaries. The land
surface in the state generally slopes gently downwards from north (Ikorodu) to
the south (Victoria Island, Apapa and Badagry).
The entire area of Amuwo Odofin local government area is sand-filled,
overlying a swampy ground. It is part of the Quartenary deltaic plain sands, the
Benin formation (Obiora & Onwuka, 2005) and it “provides a ready answer to
the groundwater problems, giving rise to high yielding boreholes” (Offodile,
2002). Festac town is part of the Quaternary deposit of the south-western part of
Lagos state. It consists of deep basal sand proved from about 40m depth.
Following the basal sand is a series of soft deposit of peat (an organic soil), soft
clays and variegated materials (Meshida, 2005).
The depth to groundwater at a specific location is important because the soil
between the surface and groundwater acts as a filter. Less soil means more
leaching, less adsorption and less degradation.
2.7.1. Hydrogeology
Lagos state falls into Deltaic terrains. The hydrogeology of the case study area
can be simplified into four layers.
- A short layer of fairly clean water
- A layer of ionic water, to about 95m
- Brackish water, from 120m to a depth of about 200m
- Another layer of ionic water
Below 200m to 220m can be found freshwater. Information on the subsurface
distribution of beds of various aquiferous properties has to be gotten form
boreholes, since geophysical methods yield ambiguous results because of the
presence of brackish or saline water in deltaic terrains (Mandel & Shiftan)
CHAPTER THREE:
METHODOLOGY
3.1. Methodology
The project programme was executed in four stages:
1. Meetings with the local government officers, notably the Sanitation
officer, the heads of Engineering department and Water Corporation,
Festac/Amuwo Odofin district.
2. Surveys conducted in the case study area.
3. Field Investigation.
4. Laboratory analysis of physio-chemical and microbiological parameters.
3.1.1. Meetings with the local government officers
The offices of the local government are located at 22 rd, Festac town.
Information gathered from the local government included
- population estimate of Amuwo Odofin LGA
- information on the water quality of Amuwo Odofin LGA
- State laws or federal laws governing water quality standards.
- Any water treatment projects executed in the case study area.
3.1.2. Surveys carried out in the case study area
A questionnaire was circulated to the people living in the areas from which each
sample site was located. In the Appendices is a sample of the questionnaire.
3.1.3. Field Investigation
Ten samples from the case study area were collected from water wells whose
depths ranged from 4m to 9m.
The distribution of the wells for sampling is given as:
Five (5) in Jakande estate, Amuwo Odofin, and its environs (towards
Maza Maza and the Mile 2 service lanes), Raji Rasaki estate, Lakeside
LSDPC estate, Waterside, Amuwo Odofin, and its environs ( after the
canal)
Three (3) located in Festac town, from wells in 1st avenue to 7th avenue.
Two (2) located in Festac town extension, i.e. Festac phase II, 4th avenue
and 6th avenue, over the canal.
Table 4 presents the summary of well characteristics.
T able 4: Descriptions at Sample site
SAMPLE NO. LOCATION OF PRESENT PRESENCE/
WELL STATE OF USE TYPE OF WELL-HEAD
SP 1 7TH Avenue, A1 close, Festac
Well used for washing, bathing and general cleaning
None
SP 2 311 rd, Festac Well used for washing, bathing and general cleaning
Yes, metal but rusted through
SP 3 Mile two estate, Amuwo Odofin (Jakande)
Well used for washing, bathing and general cleaning
none
SP 4 Festac extension, Amuwo Odofin, Alaba expressway
Well used for washing, bathing and general cleaning. Consumed by mallams
Yes. Made of concrete, partially covering well. well located at ground level
SP 5 Catholic church, Maria rd, Amuwo Odofin layout
Used now mostly for construction purposes
none
SP 6 Patience Olukayode street, Lakeview est., Amuwo Odofin
Well used for washing, bathing and general cleaning
None. well carved out of ground, no lining
SP 7 Engr. Uchendu street, ICAN, Amuwo Odofin
Well used for washing, bathing and general cleaning. Consumed by shanty-dwellers nearby
none
SP 8 4TH Avenue, Festac extension
Used by Car wash and Mechanics nearby, also supplies shanties close by
none
SP 9 3rd avenue, F1 close, Festac
Used for general cleaning
none
SP 10 6th avenue, Festac town extension
Used by a pure water manufacturing company
yes
Untreated water samples taken directly from each well were analyzed for
bacteria, trace metals, and general water potability. The study period fell in June
2006, which is in the rainy season, during which waste interference and
leaching are greatly enhanced.
For the purpose of this project, the following were used to collect water samples
for laboratory analysis and for on-site testing:
- 20, 2ml plastic containers
- 10 laboratory bottles
- temperature, conductivity and pH meter
3.2. SOURCES OF DATA
This was gathered from analysis of water samples taken directly from wells in
the area, maps and questionnaires distributed to residents. Primary sources of
data were questionnaires and observations while secondary sources were
reviews of past work, journals and past projects.
3.3. PARAMETERS
The parameters to be tested for in the water samples are listed below:
1.Chloride
2.Colour (Pt-Co)
3.Nitrate
4. Iron
5.Fluoride
6.pH
7.Biochemical Oxygen Demand (BOD)
8.Chemical Oxygen Demand (COD)
9.Dissolved Oxygen (DO)
10. Total Dissolved Solids (TDS)
11. Total Suspended Solids (TSS)
12. Phosphate
13. Sulphate
14. Bicarbonate
15. Alkalinity
16. Magnesium
17. Potassium
18. Lead
19. Cadmium
20. Calcium
21. Total Hardness of water
22. Faecal Coliform bacteria
3.4. FIELD STUDY
The conductivity, pH values and temperatures of the samples were recorded in-
situ. Since water temperature will adjust to its surroundings with time, it is
important that the sample be tested as soon as possible after collection. The
thermometer was left in the sample for two minutes before a reading was taken.
Temperature ranges will vary depending on location and time of day.
The concentration of the above listed minerals, trace metals and metals will be
used to determine the quality of groundwater. The last parameter is to estimate
the amount of Coliform bacteria present that are indicator organisms used to
indicate the presence of viruses and other pathogenic organisms. Sampling for
this parameter was done using sterilized containers, which were transferred,
with the samples in them, to the laboratory as soon as possible. Sample bottles
were rinsed with the groundwater being sampled before filling. This was done
as part of quality control measures.
3.5 LABORATORY ANALYSIS
The water samples were taken to three laboratories; Triple E Systems
Associates Ltd., the laboratories of the Department of Microbiology and the
Department of Chemistry, Faculty of Science, University of Lagos, to be
analyzed and statistical analysis of the results will be carried out from both
these data.
The samples collected for use in testing for heavy metals were preserved with
2ml concentrated sulphuric acid, H2SO4., at 4oC in the laboratory refrigerator.
pH, temperature, TDS and TSS were determined in-situ using a Hanna combo
pH & EC meter on-site. Dissolved Oxygen (DO) and Biological oxygen
demand (BOD) were measured using Azide modification method, with the
addition of H2SO4 acid. The Chemical Oxygen demand level was measured
using the Open Reflux and titrimetric methods, using Potassium Dichromate
and H2SO4. The level of Bicarbonates was determined with titration. Chloride,
Sulphate, Nitrate, Fluoride and Phosphate were all determined using a portable
Hach UV spectrophotometer, the wavelength of the anions being measured
ranging from 70-488nm, with titrant FAS (Ferrous Aluminium Sulphates).
Levels of heavy metals such as cadmium and iron, and cations such as sodium
and magnesium were measured using Atomic Absorption Spectrometer of
graphite furnace and flame, hydride system.
The determination of Total and Thermo-tolerant (faecal) coliform in each
sample was done using the Spread Plate technique. Appropriate dilutions of the
samples were plated out on MacConkey agar plates for the isolation and
enumeration of total and thermo-tolerant (faecal) coliforms. A sterile glass rod
shaped like a bent iron (hockey stick) was used to spread the inoculum on the
surface of the agar plates. The plates were made in duplicates. The temperature
of incubation was 370oC for total coliforms and 44oC for thermo-tolerant
(faecal) coliforms. Colonies appear on the medium as pink or red, usually
circular and convex in shape.
CHAPTER FOUR:
DATA ANALYSIS AND DISCUSSION OF RESULTS
4.1. Data Analysis using Questionnaire
From 50 questionnaires distributed throughout the study area, data gathered
over a vast group of residents, the following was realised:
1. Residents in general had little or no knowledge as to how to protect
groundwater or their wells.
2. There are very few wells constructed in the study area which comply
with the standards given by the FME and the wells are dilapidated
3. Most of the wells in the study area have no well head as protection and
have not been maintained since its construction.
Table 5: Summary of Physical parameters
Parameter Min Max St. Dev. WHO
standard
Colour, Pt-co 10 155 44.295723
pH 5.45 7.73 0.637747
Temperature (0C) 27.8 30.6 0.900617
Conductivity (mS/cm) 163 790 198.5134
TSS (ppm) 6 192 62.75703
T able 6: Atomic Absorption Spectrophotometer readings for Magnesium
levels
Concentration
Mean SD RSD (%)
SP 1 48.102 1.7993 3.7
SP 2 29.444 3.0172 10.2
SP 3 43.177 0.5287 1.2
SP 4 41.132 0.1337 0.3
SP 5 66.552 0.0894 0.1
SP 6 31.340 0.0681 0.2
SP 7 27.308 0.0597 0.2
SP 8 30.971 0.2685 0.9
SP 9 28.861 0.0202 0.1
SP 10 0.73 0.00536 0.1
4.2. Discussion of the Physio-chemical parameters and Microbiological
parameter
Temperature: Temperature is an important parameter in its affect on the
solubility of oxygen in water and the sensitivity of organisms to toxic wastes,
parasites, and diseases. Colder water can hold more dissolved oxygen.
Significant increases in water temperature are caused by industrial discharges of
warm water, by reduction of water flow where dams are operating or soil
erosion. Temperature ranged from 27.8oC to 30.6oC, with SP 7 having the
lowest value and SP 9 having the highest value.
pH: The acidic and basic properties or the pH of water can affect plants and
animals. pH ranges between 1-14, with 7 being neutral. Readings below 7
indicate acidic conditions, above 7 indicate basic conditions. According to the
Federal Ministry of the Environment, only SP 6 is not safe within the limit.
Dissolved Oxygen (DO): DO is a measure of the amount of oxygen freely
available in water. DO levels change over time and are affected by temperature
and other environmental factors. Percent saturation is the percent of the
potential capacity of the water to hold oxygen that is present.
Biochemical Oxygen Demand (BOD): Biochemical oxygen demand is the
measure of the amount of oxygen used to break down organic matter in the
water. High levels of BOD mean high nutrient levels in the groundwater.
Unpolluted, natural waters will have a BOD of 5mg/L or less. BOD values for
the samples ranged from between 0.2 to 1.2mg/l.
Suspended Solids: Suspended solids are an important part of water quality.
High suspended solids can make water unusable in many ways. Pesticides and
bacteria can attach to the suspended solids making it more readily transported.
This is not usually expected to be high in groundwater, since water stored in the
aquifer will have passed through ssoil strata which would have acted as a
filtering medium.
Total Dissolved Solids (TDS): The total dissolved solids test measures the
amount of particles that are dissolved in water. TDS values are higher in
groundwater than in surface water. High levels in drinking water may cause
objectionable tastes and have laxative effects. The quantity of TDS in a body of
water depends on several factors which may include the type of soil and rock
the water passes through and human activities. The major dissolved substances
found in water that can cause the above problems are the positively charged
ions of sodium, calcium, magnesium, potassium and iron and the negatively
charged ions of chloride, bicarbonate, carbonate and sulphate. All samples fell
below the WHO/FME standard of less than 1000mg/l.
Alkalinity: Alkalinity is a measure of the quantity of compounds that shift the
pH to the alkaline side of neutrality (above 7) or it is a measure of the capacity
of water to neutralize acids. Alkalinity is important because it buffers pH
changes that occur naturally during photosynthetic cycles, water exchanges and
the addition of acids to water. Raising the alkalinity almost always raises the
pH. If the alkalinity of water is too high, the water can be cloudy. Too high
alkalinity raises the pH level.
Iron: The high value of iron in the groundwater samples is expected, as it has
noted in previous research that the groundwater of Lagos state in general have
high iron content. The amount of iron in water affects the appearance of water,
giving it a metallic taste. High concentrations of iron form reddish-brown ferric
hydroxide sediments, coatings, and stains. Values gotten from the laboratory
analysis of the water samples show that all are in excess of acceptable limits of
iron levels. SP 1 had an exceedingly high iron concentration of 15.353mg/l.
Cadmium: Cadmium can be found in very low concentrations in most rocks, as
well as petroleum and coal and often in combination with zinc. Geologic
deposits of cadmium can serve as sources to groundwater and surface water,
especially when in contact with soft, acidic waters. It is considered a possible
human carcinogenic substance. Cadmium may enter groundwater as a result of
landfill leachates or various industrial applications. Cadmium levels in the
samples were high, higher than the maximum permitted level according to
WHO standards. The possible source of cadmium in the study area may be the
landfill in Festac town, as the sample well (SP 1) with the highest value is
located around the vicinity of the landfill.
Lead: According to the FME values, all the groundwater samples had permitted
levels of groundwater. But according to WHO standards, the level of lead in the
samples was high. Lead is a relatively minor element in the earth’s crust but is
widely distributed in uncontaminated sedimentary rocks and soil (WHO, 1987).
High concentrations of lead result from atmospheric input originating from its
use in leaded petrol or from smelting operations.
Chloride: The presence of chloride where it does not occur naturally indicates
possible water pollution. Other sources of chloride are septic tank effluent,
animal waste, and potash fertilizer (KCl). The normal range for groundwater is
35-125mg/L. At concentrations greater than 250 to 400mg/l the water will have
a salty taste. High concentrations are corrosive to most metals. The chloride
levels for SP1-10 are within permitted zones.
Nitrates: Nitrate is one of the major anions in groundwater but concentrations
can be greatly elevated due to leaching of nitrogen from animal waste, private
septic systems, wastewater, flooded sewers, polluted storm water runoff,
fertilizers, agricultural runoff, and decaying plants. The presence of nitrate in
well water also depends on the geology of the land. Nitrate values for all
samples were within safe limits.
Potassium: Potassium was noticed in the wells at concentrations ranging from
16.958 to 62.681 mg/l. High concentrations of the element are attributed to
diffusion of volatile substances from surface runoff, garbage and industrial
effluent discharges; these being characteristic of highly urbanised areas.
Calcium: Calcium, as well as magnesium, is causes of hardness in water. When
present in concentrations from 25 to 50mg/l this is considered normal for
natural groundwater. Values of all samples taken fall below WHO limits.
Magnesium: Magnesium is a relatively abundant element in the earth’s crust,
hence, a common constituent of natural water. Magnesium concentrations as
reads from the results in Table 6 range between 0.73 mg/l and 66.552mg/l. SP
10 shows the lowest concentration while SP 5 shows the maximum
concentration of magnesium. The concentrations of magnesium in all samples
fall below the maximum permissible value of 150mg/l.
Phosphates: According to the FME, levels above 5mg/l are considered
characteristic of poor water quality. SP1 to 10 all fall well below excess levels
of phosphate in groundwater.
Fluoride: Fluoride occurs naturally in most soils and water. Excessive amounts
of fluoride may cause crippling skeletal fluorosis, a serious bone disorder. Four
of the samples, SP 2, 4, 5 and 6, had levels of fluoride higher than the
acceptable standards of WHO, which state that levels above 1.5 g/l are
unacceptable.
Sulphate: Sulphate is a naturally occurring anion. Industries and utilities that
burn coal release sulphur compounds into the atmosphere to become a part of
the acid rain problem. Dissolved sulphate is derived from the dissolution of
gypsum or the oxidation of sulphide minerals. At concentrations exceeding 500-
600mg/l, it imparts a bitter taste and may cause laxative effects in some
individuals. WHO and FME approved standard for level of sulphates in
groundwater is 500mg/l. All levels of sulphate in the samples are within
approved limits.
Faecal Coliform: Faecal coliform are bacteria that are found in the intestines of
all animals. Faecal coliform bacteria may occur in ambient water as a result of
the overflow of domestic sewage or non-point sources of human and animal
waste. Runoff and excess soil moisture carry contaminants into shallow
groundwater sources or through well defects. Coliform bacteria are most likely
to be found during periods of wet weather when the soil is warm. The presence
of faecal coliform is used as an indicator that there could be pathogenic bacteria
in the water. No faecal coliform should be present in drinking water. The limit
for swimming is 200 colonies per 100 ml of water. The presence of faecal
coliform indicates contamination from septic systems and the unsanitary mode
of waste disposal, such as defecation in streams. From the results of the water
samples, there is a high level of faecal coliform in the groundwater of the area,
though not high enough to be endangering to human lives.
4.3. DISCUSSION OF RESULTS
Residents of the local government are well aware that their water is polluted;
consequently, few people drink the water, although it is used for other domestic
purposes. Runoff and excess soil moisture carry contaminants into shallow
groundwater sources or through well defects. An open well without a well head
is always potentially dangerous since the ground around it may slope towards
the well allowing rain and spillage to wash into it. The use of unsanitary
buckets and devices for collecting water also aids in contaminating the well.
The WHO has no definite range for conductivity. However, a value of
400µs/cm was provided as a guide.
The lack of a waste disposal system may be affecting the quality of
groundwater in the area. Apart from proximity to waste disposal systems, a
complex mix of interdependent factors such as the physical characteristics of
rock formations, mode of construction and maintenance of wells are likely to
affect groundwater quality at a given location. In individuals genetically
susceptible to hemochromatosis, excessive amounts of iron accumulated in the
body results in liver, pancreas and heart failure and dysfunction after long-time
high exposures. It was observed during sampling that when clear water was first
drawn, upon exposure to air, had brown particles due an iron precipitation;
settle at the bottom of the container. In areas around the Amuwo canal,
residents complained of salty or brackish water; soapy smell. TDS, chloride,
sodium and sulphate pollution was present in this area.
Other possible sources of groundwater contamination are failed septic tank
systems which in most cases are located very close to well sources. Faecal
contamination, in the study area, is by septic tanks and sewage plants. Indicator
organisms such as coliform bacteria are used as pointers of recent faecal
contamination due to their relatively short life span in the aquatic environment
but they can be used as indicators of health risk (FEPA 1999). Coliforms are
more resistant than many pathogenic bacteria; therefore their absence in water
is a good indication of water safety. Unfortunately, there is a substantial
presence of coliform bacteria in the groundwater of Amuwo Odofin LGA.
Some pathogens often survive conventional water chlorination, and expensive
filtration may be required to remove them.
4.4. Groundwater Remediation
Groundwater remediation aims to reduce contaminant concentrations to below
the threshold standard for the intended use. Groundwater Remediation is always
complicated. Eldho (2002) states that prevention of groundwater pollution is not
only better but also much cheaper than remediation and repair. According to
D’Antonio et al, (1991), strategies for groundwater remediation are dependent
upon a number of factors that include the source of pollution (point or non-
point), length of release, site characteristics (such as soil thickness and type,
depth to groundwater), physical properties of the contaminant, potential flow
paths and receptors, health and environmental risks posed by the contaminant,
and the resources available to address the problem. In developed countries,
remediation of non-point sources, such as urban or agricultural storm water
runoff, may be possible through programs to minimize generation of
contaminants. Aquifer protection techniques include implementation of best
management practices during construction and operation, such as sediment
control during construction, grass buffers around dolines, roughing filters on
open ponds. For the restoration of the contaminated aquifers, remediation
efforts are used at the contaminated source and plume to eliminate and extract
the contaminants. The remediation of contaminated aquifers is very complex, as
the process of movement of contaminants through the porous media is quite
complex. The groundwater pollution remediation can be carried out either by
onsite techniques or in-situ methodologies. Even though, in the recent times,
many in-situ remediation methods have been developed, most of the
remediation works are still done on-site by pump and treat method. But the
pump and treat method is not very efficient and economic.
4.4.1. Programs of activities for Groundwater Remediation
Groundwater remediation activities are addressed by different activities
programs, depending if the contaminated groundwater is treated in place or
extracted just before treatment. Non-discharge groundwater remediation
systems are groundwater treatment systems that extract and treat contaminated
groundwater. These include closed-loop groundwater remediation systems and
typically use infiltration galleries or injection wells. Groundwater remediation
systems that introduce substances directly into the subsurface are underground
injection wells, which are regulated by the Underground Injection Control
Program. Soil remediation is often a component of groundwater remediation
strategies.
4.4.2. Groundwater remediation from Point sources
Generally, point sources such as industrial effluents are best remediated as close
to the source as possible to minimize the volume of water (and soil) to be
treated and decrease remediation time.
CHAPTER FIVE:
CONCLUSION AND RECOMMENDATION
5.1. Conclusion
It can be seen that the source of pollution in the case study is from individual
sanitation methods. Residents of the study area are well aware that the
groundwater in the area is polluted, but are not sure as to the exact extent.
Consequently, other water sources are depended on for household consumption
and well water is used mostly for cleaning and washing of objects.
Unfortunately, households whom are not able to afford getting their water
elsewhere have to use the polluted waters drawn from the wells and boreholes.
Most of the residents rely on boreholes, which they trust will yield cleaner
water, as they assume that at a depth, the groundwater will be cleaner. But that
is not the case always; the depth required for clean water is expensive to drill
and most residents don’t. Water from one such “deep” borehole was tested for
faecal coliforms and had a value greater than what resulted from some of the
sample wells.
Close proximity of septic tanks to the septic tanks to the underground water
reservoir may lead to pollution especially when the septic tanks are poorly
constructed as shown in investigations by FEPA (1999) that suggested a
standard for correct, septic tank placement to be about 15m away from the
underground water reservoir.
5.2. Protection/Prevention of Groundwater pollution
Achieving the crucial goal of prevention of groundwater contamination may at
times be limited by the practicalities and restrictions of technology and
economics. Given these considerations, the Ministry has to execute program
specific technologies and management practices which have been demonstrated,
in other countries, to minimize ground water contamination from all sources.
The Ministry should also evaluate new technologies and management practices
for groundwater quality protection, and should strive to put them into operation
where it is demonstrated that it is practical and effective to do so.
In addition, groundwater protection plans must be developed for those actions
for which such plans are a requirement of regulation. These plans should
expansively describe precise performance requirements that, when
implemented, will make certain that the source does not adversely affect
groundwater quality. These plans should reflect any of the following:
Description of hydrogeology and groundwater quality at the site or area
Education and training of personnel and the general public as to the
efficient use and protection of groundwater quality, choosing non-
hazardous products, reducing use of some chemicals, respecting the
recycling programs of municipalities, ensuring a proper disposal of
waste
Observation programs to show the effectiveness of specific protection
practices and provisions to be made for regular inspection
Performance-based practices directed toward preventing releases, spills,
or leaks to ground water
Use and value of the groundwater resource
Reasonable recordkeeping requirements
5.3. Recommendations
The following recommendations are made:
1. The Federal Housing Authority of Amuwo Odofin LGA should enforce
building regulations in regards to the construction of septic tanks and
water wells
2. There should be more awareness as to the maintenance of water supply
structures such as wells.
3. A Central Sewage system, comprising of drains, pipes and a sewage
treatment plant, should be constructed to provide for the local
government.
4. Residents should be educated as to the protection of their wells and water
supply. This should be adopted by all local governments in the state
5. That the Federal Ministry of the Environment should evolve and
supervise sound water quality monitoring programmes for the country.
Obviously prevention is the only regulation method for those chemicals which
cannot be removed by water treatment methods from entering the water system.
Education actually will be of the greatest aid in groundwater pollution
remediation.
High quality ground water is important for human consumption, industry and
agriculture. Ground water can be vulnerable to the impact of human activities.
Ground water pollution is not inevitable; careful management, strong protective
measures, and restoration of polluted water is possible through the coordinated
efforts of state and local government, industrial, commercial, and agricultural
interests, and the public.
In those cases where complete prevention of contamination is not possible due
to demographics and the practicalities of technology and economics, the Federal
Ministry of the Environment should consider the use and value of the resource
in establishing protection measures.
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Basics of Groundwater:
www.groundwater.com/groundwater basics.html
Deep Draft Water Quality Monitoring
Procedure:friends@chicagoriver.org
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www.gpu.htm
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Ground water trust.htm
Rhode Island Department of Health: www.health.ri.gov
APPENDICES
QUESTIONNAIRE ON QUALITY OF GROUNDWATER IN AMUWO ODOFIN LGA
1. What is your current address……………………………………………………………………………………………….
2. What is the source of your domestic water? Well water Borehole
3. What is the age of your source of water supply (well or borehole)?0-5 years 5-10 years 10-15 years More
5. Would you describe the water as having any of the followingTaste
Odour
Colour
6. Has there been any case of any septic tank leaking into your water supply?Yes No
7. Is your water salty to taste?
Yes No
8. Do you protect your source of water supply?Yes No
8. What do you do use protect your water supply source? A well covering Other methods
9. When you fetch your water, is there a brown substance that settles down in
the water after some time?Yes No
To be answered by field sampler
Is there a well head………………
Depth of well………………………..
Presence and Description of Filter media in the well……………………………………………………………………………………………………………
Colour of water………………………………..
Temperature of water (in oC)…………………….
Proximity to Septic tank/other source of sewage disposal unit……………………………………………………………..
Fig. 1: Calcium graph, with slope 0.02009, from Atomic Absorption Spectrophotometer (AAS)
Recommended