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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INTERNET SOURCES

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

NSF Consumer Information Well Water.htm

Public Information pamphlet-Bacteria and well water: American

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)