This document summarizes a student project presentation on assessing stormwater runoff quality in Nakuru City, Kenya. The student, Murigi Peter Njoroge, studied pollutant levels in runoff from the market, garage, and industrial areas of Nakuru. Methods like atomic absorption spectrometry and chemical oxygen demand tests were used to measure total suspended solids, total phosphorus, chemical oxygen demand, lead, zinc, and other parameters. Results showed high levels of these pollutants in stormwater runoff. The project aims to determine pollutant concentrations and recommend management practices to the municipal council, based on deviations from effluent standards.

1. EGERTON UNIVERSITY
FACULTY OF ENGINEERING AND TECHNOLOGY
Department of Civil and Environmental Engineering
FINAL YEAR PROJECT PRESENTATION
TITLE:
STORM WATER RUNOFF QUALITY ASSESSMENT IN URBAN AREAS-
CASE STUDY NAKURU CITY
BY:
MURIGI PETER NJOROGE B12/40044/07
COURSE:
BSC. WATER AND ENVIRONMENTAL ENGINEERING
DATE:
22/05/2012
PROJECT SUPERVISOR:
PROF TUITOEK
EGERTON UNIVERSITY
FACULTY OF ENGINEERING AND TECHNOLOGY
Department of Civil and Environmental Engineering
FINAL YEAR PROJECT PRESENTATION
TITLE:
STORM WATER RUNOFF QUALITY ASSESSMENT IN URBAN AREAS-
CASE STUDY NAKURU CITY
BY:
MURIGI PETER NJOROGE B12/40044/07
COURSE:
BSC. WATER AND ENVIRONMENTAL ENGINEERING
DATE:
22/05/2012
PROJECT SUPERVISOR:
PROF TUITOEK

2. ABSTRACT
 According to recent global survey, Nakuru is the fastest growing town in East and Central
Africa.
 In spite of National Environmental Management Authority (NEMA) policies and other
regulations on pollution control being in place, the municipal council of Nakuru has
been lagging behind in enforcement of such laws and policies on proper environmental
management practices.
 Particularly pollution from stormwater runoff has been greatly ignored as it is directly
discharged without treatment to Lake Nakuru and thus the need for this study to
highlight the extent of this pollution.
 The objective of this study was to determine pollutants contained in runoff and their
concentrations from runoff samples collected in various sampling points in Nakuru:
market , garage and industrial area.
 Various methods were used in achieving the objectives such as A.A.S for analysis of
metals, TP, open reflux method for COD and filtration for TSS.
 The results showed high average levels of the parameters mentioned above i.e.TSS(1167
mg/l) ,TP(2.43 mg/l), COD (207.57mg/l),Pb( 0.0283mg/l), Zn( 1.278mg/l).
 The objective of this project was thus to determine the pollutants contained in
stormwater runoff and their concentrations.
 The study further aimed at making recommendations on proper stormwater runoff
pollution control to the municipal council of Nakuru, based on the observed deviation of
parameter values from KEBS effluent discharge standards.
 According to recent global survey, Nakuru is the fastest growing town in East and Central
Africa.
 In spite of National Environmental Management Authority (NEMA) policies and other
regulations on pollution control being in place, the municipal council of Nakuru has
been lagging behind in enforcement of such laws and policies on proper environmental
management practices.
 Particularly pollution from stormwater runoff has been greatly ignored as it is directly
discharged without treatment to Lake Nakuru and thus the need for this study to
highlight the extent of this pollution.
 The objective of this study was to determine pollutants contained in runoff and their
concentrations from runoff samples collected in various sampling points in Nakuru:
market , garage and industrial area.
 Various methods were used in achieving the objectives such as A.A.S for analysis of
metals, TP, open reflux method for COD and filtration for TSS.
 The results showed high average levels of the parameters mentioned above i.e.TSS(1167
mg/l) ,TP(2.43 mg/l), COD (207.57mg/l),Pb( 0.0283mg/l), Zn( 1.278mg/l).
 The objective of this project was thus to determine the pollutants contained in
stormwater runoff and their concentrations.
 The study further aimed at making recommendations on proper stormwater runoff
pollution control to the municipal council of Nakuru, based on the observed deviation of
parameter values from KEBS effluent discharge standards.

3. CHAPTER ONE
INTRODUCTION
Storm water runoff occurs when precipitation from rain flows over the
ground. Impervious surfaces like driveways, sidewalks, and streets
preventing storm water runoff from naturally infiltrating into the
ground. It picks up debris, chemicals, dirt, and other pollutants and
flow into a storm sewer system or directly to a lake, stream, river,
wetland, or coastal water. Anything that enters a storm sewer system
is discharged untreated into the water bodies we use for swimming,
fishing and providing drinking water.
The main reason why urban storm water remains such an important
contributor to water pollution is the fact that in most areas, storm
water receives no treatment before entering water bodies.
INTRODUCTION
Storm water runoff occurs when precipitation from rain flows over the
ground. Impervious surfaces like driveways, sidewalks, and streets
preventing storm water runoff from naturally infiltrating into the
ground. It picks up debris, chemicals, dirt, and other pollutants and
flow into a storm sewer system or directly to a lake, stream, river,
wetland, or coastal water. Anything that enters a storm sewer system
is discharged untreated into the water bodies we use for swimming,
fishing and providing drinking water.
The main reason why urban storm water remains such an important
contributor to water pollution is the fact that in most areas, storm
water receives no treatment before entering water bodies.

4. STATEMENT OF THE PROBLEM
Storm water runoff is designated as a
leading impairment source for estuaries and
the third largest pollution source for lakes
and rivers. Yet, it has remained the most
ignored source of pollution by many
municipals in the world.
Storm water runoff is designated as a
leading impairment source for estuaries and
the third largest pollution source for lakes
and rivers. Yet, it has remained the most
ignored source of pollution by many
municipals in the world.

5. JUSTIFICATION
 Due to increasing areas of impervious surfaces as roads,
parking lots, and rooftops in urbanized locations, a greater
fraction of precipitation cannot infiltrate into the soil and
becomes runoff, mobilizing deposited pollutants. It contains
suspended solids (SS), heavy metals, phosphorus (P), nitrates,
and other harmful pollutants.
 Increases in the variety and concentrations of pollutants
mobilized in the runoff deleteriously impact water quality and
the viability of surrounding ecosystems, in addition to
increasing subsequent water treatment costs. Therefore the
need for analysis of contaminants in runoff as a pre requisite
for recommendation of better water management practices.
 Due to increasing areas of impervious surfaces as roads,
parking lots, and rooftops in urbanized locations, a greater
fraction of precipitation cannot infiltrate into the soil and
becomes runoff, mobilizing deposited pollutants. It contains
suspended solids (SS), heavy metals, phosphorus (P), nitrates,
and other harmful pollutants.
 Increases in the variety and concentrations of pollutants
mobilized in the runoff deleteriously impact water quality and
the viability of surrounding ecosystems, in addition to
increasing subsequent water treatment costs. Therefore the
need for analysis of contaminants in runoff as a pre requisite
for recommendation of better water management practices.

6. GENERAL OBJECTIVE
To determine pollutants contained in storm
water runoff of paved surfaces in Nakuru
town.
To determine pollutants contained in storm
water runoff of paved surfaces in Nakuru
town.

7. SPECIFIC OBJECTIVES
 To determine the amount of
COD, TSS, TP, Pb, Fe, Zn, Mn contained in storm
water runoff.
 To determine whether the concentrations of the
above parameters in runoff exceed the effluent
discharge standards.
 To propose best stormwater runoff management
practices based on the results obtained.
 To determine the amount of
COD, TSS, TP, Pb, Fe, Zn, Mn contained in storm
water runoff.
 To determine whether the concentrations of the
above parameters in runoff exceed the effluent
discharge standards.
 To propose best stormwater runoff management
practices based on the results obtained.

8. HYPOTHESIS
Storm water runoff in Nakuru town
contributes to water pollution in Lake
Nakuru and other adjacent water bodies.
Storm water runoff in Nakuru town
contributes to water pollution in Lake
Nakuru and other adjacent water bodies.

9. LITERATURE REVIEW
The impacts of storm water pollution
The storm water pollution problem has two main
components:
 The increased volume and velocity of surface
runoff.
 The concentration of pollutants in the runoff.
The impacts of storm water pollution
The storm water pollution problem has two main
components:
 The increased volume and velocity of surface
runoff.
 The concentration of pollutants in the runoff.

10. Components of Storm water Pollution
1] Increased Volume And Velocity due to The Impervious Cover Factor
a)Types of Impervious Cover
Some impervious cover, such as exposed rock or hardpan soil, is natural. Land
development, however, greatly increases it. Human-made impervious cover comes
in three varieties: rooftop imperviousness from buildings and other structures;
transport imperviousness from roadways, parking lots, and other transportation-
related facilities; and impaired pervious surfaces, also known as urban soils, which
are natural surfaces that become compacted or otherwise altered and less pervious
through human action.
b) Imperviousness Thresholds
As the amount of impervious surface in a watershed increases, infiltration and
evapotranspiration both drop substantially. As a result, more water, having nowhere
else to go, runs off the surface picking up pollutants from activities occurring on the
impervious surfaces.
1] Increased Volume And Velocity due to The Impervious Cover Factor
a)Types of Impervious Cover
Some impervious cover, such as exposed rock or hardpan soil, is natural. Land
development, however, greatly increases it. Human-made impervious cover comes
in three varieties: rooftop imperviousness from buildings and other structures;
transport imperviousness from roadways, parking lots, and other transportation-
related facilities; and impaired pervious surfaces, also known as urban soils, which
are natural surfaces that become compacted or otherwise altered and less pervious
through human action.
b) Imperviousness Thresholds
As the amount of impervious surface in a watershed increases, infiltration and
evapotranspiration both drop substantially. As a result, more water, having nowhere
else to go, runs off the surface picking up pollutants from activities occurring on the
impervious surfaces.

11. c) Increased Volume of Runoff
 The effect of impervious surfaces on the volume of storm water
runoff can be dramatic. For example, a 1-inch rainstorm on a 1-acre
natural meadow would typically produce 218 cubic feet of
runoff, enough to fill a standard size office to a depth of about 2 feet.
 The same storm over a 1-acre paved parking lot would produce
3,450 cubic feet of runoff, nearly 16 times more than the natural
meadow, and enough to fill three standard size offices completely.
On a larger scale, the effect is even greater.
d) Greater Stream and Runoff Velocity During
Storm Events
 Unlike grassy meadows or forests, hard, impervious cover, such
as parking lots and rooftops, offers little resistance to water flowing
downhill, allowing it to travel faster along these surfaces.
 The increased velocity and delivery rate greatly magnifies the
erosive power of water as it flows across the land surface and once it
enters a stream.
c) Increased Volume of Runoff
 The effect of impervious surfaces on the volume of storm water
runoff can be dramatic. For example, a 1-inch rainstorm on a 1-acre
natural meadow would typically produce 218 cubic feet of
runoff, enough to fill a standard size office to a depth of about 2 feet.
 The same storm over a 1-acre paved parking lot would produce
3,450 cubic feet of runoff, nearly 16 times more than the natural
meadow, and enough to fill three standard size offices completely.
On a larger scale, the effect is even greater.
d) Greater Stream and Runoff Velocity During
Storm Events
 Unlike grassy meadows or forests, hard, impervious cover, such
as parking lots and rooftops, offers little resistance to water flowing
downhill, allowing it to travel faster along these surfaces.
 The increased velocity and delivery rate greatly magnifies the
erosive power of water as it flows across the land surface and once it
enters a stream.

12. e) Increased Peak Discharges
 Greater peak flows lead to increased
flooding, channel erosion and
widening, sediment deposition, bank
cutting, and general habitat loss.
f) Reduced Stream Base Flow
 Because impervious cover reduces infiltration
and forces storm water to run off the land
immediately, it also typically reduces the
amount of groundwater available to recharge
streams when there is no rain.
e) Increased Peak Discharges
 Greater peak flows lead to increased
flooding, channel erosion and
widening, sediment deposition, bank
cutting, and general habitat loss.
f) Reduced Stream Base Flow
 Because impervious cover reduces infiltration
and forces storm water to run off the land
immediately, it also typically reduces the
amount of groundwater available to recharge
streams when there is no rain.

13. g) Decreased Natural Storm water Purification
Functions
 Channelizing, diking, and levying
disconnect a river from its floodplain and
reduce its ability to modify floods naturally.
 Eliminating the natural drainage ways
reduces flow storage and detention and soil
moisture maintenance and can increase
overall flooding and erosion.
g) Decreased Natural Storm water Purification
Functions
 Channelizing, diking, and levying
disconnect a river from its floodplain and
reduce its ability to modify floods naturally.
 Eliminating the natural drainage ways
reduces flow storage and detention and soil
moisture maintenance and can increase
overall flooding and erosion.

14. Categories of Principal Contaminants in Stormwater
Category Examples
2] Increased Deposition Of Pollutants
The second aspect of urbanization that contributes to urban
storm water pollution is the increased discharge of
pollutants. As human activity increases in a given area, the
amount of waste material deposited on the land and in
drainage systems increases. The principal contaminants of
concern for storm water fall into seven categories.
Category Examples
Metals zinc, cadmium, copper, chromium, arsenic, lead
Organic chemicals pesticides, oil, gasoline, grease
Pathogens viruses, bacteria, protozoa
Nutrients nitrogen, phosphorus
Biochemical oxygen demand (BOD) grass clippings, fallen leaves, hydrocarbons, human, and animal waste
Sediment sand, soil, and silt
Salts sodium chloride, calcium chloride

15. Contributors of stormwater pollution
a) Vehicle Use
b) Roads and Parking Lots
c) Home Landscaping and Public Grounds
Maintenance
d) Construction Sites
e) Illicit Sanitary Connections to Storm Sewers From
Homes and Businesses
f) Septic Systems
g) Illicit Industrial Connections to Storm Sewers
h) Uncovered Materials Stored Outside
i) Landfills
j) Pets and Domestic Animals
a) Vehicle Use
b) Roads and Parking Lots
c) Home Landscaping and Public Grounds
Maintenance
d) Construction Sites
e) Illicit Sanitary Connections to Storm Sewers From
Homes and Businesses
f) Septic Systems
g) Illicit Industrial Connections to Storm Sewers
h) Uncovered Materials Stored Outside
i) Landfills
j) Pets and Domestic Animals

16. CURRENT RESEARCH CONDUCTED ON
STORMWATER RUNOFF
A) Nationwide Urban Runoff Program (NURP) research
 In 1978, the U.S. Environmental Protection Agency (EPA) initiated the
Nationwide Urban Runoff Program (NURP) to quantify the characteristics of
urban runoff, assess the impacts of urban runoff on the water quality of
receiving waters, and examine the effectiveness of control practices in
removing pollutants found in urban runoff. An average of 28 storms for each of
the 81 representative outfalls in 28 metropolitan areas was monitored from
1978 to 1983 (U.S. EPA, 1999b).
 Ten pollutants, including
TSS, BOD, COD, TP, SP, TKN, nitrate/nitrite, Total Cu, total Pb, and total
Zn, will be selected being monitored by NURP. The water quality of untreated
urban runoff and domestic wastewater was compared and summarized in Table
1 (U.S. EPA, 1999b).
 It also showed the loadings of pollutants from urban runoff can be much
higher than the ones from treated domestic wastewater.
A) Nationwide Urban Runoff Program (NURP) research
 In 1978, the U.S. Environmental Protection Agency (EPA) initiated the
Nationwide Urban Runoff Program (NURP) to quantify the characteristics of
urban runoff, assess the impacts of urban runoff on the water quality of
receiving waters, and examine the effectiveness of control practices in
removing pollutants found in urban runoff. An average of 28 storms for each of
the 81 representative outfalls in 28 metropolitan areas was monitored from
1978 to 1983 (U.S. EPA, 1999b).
 Ten pollutants, including
TSS, BOD, COD, TP, SP, TKN, nitrate/nitrite, Total Cu, total Pb, and total
Zn, will be selected being monitored by NURP. The water quality of untreated
urban runoff and domestic wastewater was compared and summarized in Table
1 (U.S. EPA, 1999b).
 It also showed the loadings of pollutants from urban runoff can be much
higher than the ones from treated domestic wastewater.

17. Comparison of Water Quality Parameters in Urban Runoff with
domestic Wastewater(U.S.EPA.1999b)

18. B) Quality Of Storm Water Runoff From Urbanized Houston
Metropolitan Area (Min Chu, P.E.)
 During the years 1992 and 1993, the City of Houston the City of Pasadena conducted
representative storm water sampling from a total of 15 sites located in the urbanized Houston
metropolitan area. The storm water sampling effort was in response to the U. S.
Environmental Protection Agency (EPA) storm water NPDES permitting requirements for the
following four land-use categories:
• Single-family residential.
• Multi-family residential.
• Commercial.
• Industrial.
 Three different sites from each land-use category were chosen for representative sampling
purposes. Three additional sites where drainage areas were primarily undeveloped also were
selected to establish baseline water quality conditions.
 The primary purpose of the sampling was to determine the event mean concentrations (EMC)
of storm water runoff from each of the five unique land use categories. The EMCs were
subsequently used to estimate annual pollutant loads from each major watershed.
 For representative sampling, the storm should have a volume greater than 0.1 inch, should be
preceded by at least 72 hours of dry weather, and should not vary by more than 50 percent
from the average rainfall volume and duration, where feasible.
 During the years 1992 and 1993, the City of Houston the City of Pasadena conducted
representative storm water sampling from a total of 15 sites located in the urbanized Houston
metropolitan area. The storm water sampling effort was in response to the U. S.
Environmental Protection Agency (EPA) storm water NPDES permitting requirements for the
following four land-use categories:
• Single-family residential.
• Multi-family residential.
• Commercial.
• Industrial.
 Three different sites from each land-use category were chosen for representative sampling
purposes. Three additional sites where drainage areas were primarily undeveloped also were
selected to establish baseline water quality conditions.
 The primary purpose of the sampling was to determine the event mean concentrations (EMC)
of storm water runoff from each of the five unique land use categories. The EMCs were
subsequently used to estimate annual pollutant loads from each major watershed.
 For representative sampling, the storm should have a volume greater than 0.1 inch, should be
preceded by at least 72 hours of dry weather, and should not vary by more than 50 percent
from the average rainfall volume and duration, where feasible.

20. RESEARCH METHODOLOGY
Apparatus
 Spectrophotometer(AAS-S11).
 UV 200-RS Photometer.
 In relation to A.A.S, this device is used for the qualitative and
quantitative determination of chemical elements employing the
absorption of optical radiation in free atoms in gaseous state. In order
to analyse a sample for its atomic constituents it has to be atomized.
The most commonly used atomizer is the air-acetylene flame at a
temperature of 23000C. This technique relates the measured
absorbance with the analyte concentration using Beer-Lambert Law.
(www.wikipedia.org/wiki/Spectrophotometer)
 Test tubes and beakers
 Cathode lamp
 Oven
 Filter papers
Apparatus
 Spectrophotometer(AAS-S11).
 UV 200-RS Photometer.
 In relation to A.A.S, this device is used for the qualitative and
quantitative determination of chemical elements employing the
absorption of optical radiation in free atoms in gaseous state. In order
to analyse a sample for its atomic constituents it has to be atomized.
The most commonly used atomizer is the air-acetylene flame at a
temperature of 23000C. This technique relates the measured
absorbance with the analyte concentration using Beer-Lambert Law.
(www.wikipedia.org/wiki/Spectrophotometer)
 Test tubes and beakers
 Cathode lamp
 Oven
 Filter papers

21. Chemicals Used
 Acetylene gas
 Mercury sulphate
 Dichromate
 Conc. Sulphuric acid
 Ferroin indicator
 Potassium hydrogen Phosphate (KH2PO4)
 Potassium Sulphate (K2SO4)
 Phenolphthalein indicator
 Sodium hydroxide
 Isopropanol
 Acetylene gas
 Mercury sulphate
 Dichromate
 Conc. Sulphuric acid
 Ferroin indicator
 Potassium hydrogen Phosphate (KH2PO4)
 Potassium Sulphate (K2SO4)
 Phenolphthalein indicator
 Sodium hydroxide
 Isopropanol

22. Analytical Methods
Heavy metals (Pb, Mn, Fe, and Zn)
Analysis (Willard et al, 1986)
 Pb were analyzed on the atomic absorption spectrophotometer. Pb
standards of 0,1.0,2.0, 3.0 and 4.0mg/l were prepared from 1000 mg/L .
 A cathode lamp were used at a known wavelength (nm), band pass
(nm) and lamp current of milliamps, as shown below. To analyze,
samples were acidified using acetylene gas, filtered, and then analyzed
on an AAS-S11 Photometer.
 Similar test were carried out on Mn, Fe, and Zn and concentration
curves drawn using the graph of concentration against absorbance the
concentration were got using the formula:
 Y=mx
 Where y-concentration in mg/l
 M-gradient
 X-absorption
Heavy metals (Pb, Mn, Fe, and Zn)
Analysis (Willard et al, 1986)
 Pb were analyzed on the atomic absorption spectrophotometer. Pb
standards of 0,1.0,2.0, 3.0 and 4.0mg/l were prepared from 1000 mg/L .
 A cathode lamp were used at a known wavelength (nm), band pass
(nm) and lamp current of milliamps, as shown below. To analyze,
samples were acidified using acetylene gas, filtered, and then analyzed
on an AAS-S11 Photometer.
 Similar test were carried out on Mn, Fe, and Zn and concentration
curves drawn using the graph of concentration against absorbance the
concentration were got using the formula:
 Y=mx
 Where y-concentration in mg/l
 M-gradient
 X-absorption

23. Chemical oxygen demand Analysis (Willard et
al, 1986)
 A sample from each source, of 50cc was put into a quick-fit flask.
A standard solution of distilled water was prepared alongside.
The quick fit flasks were then placed on a heating mantle. To
each, 1g of Mercury (II) Sulphate and 5cc of dichromate were
added to digest the sample. 75ml of conc. sulphuric acid were
added. Condensers were then connected on the fit-in flasks.
 The samples were refluxed for 2hrs and left to cool then 3 drops
of ferroin indicator were added to determine the endpoint
during titration.
 Titration were done using FAS of molarity as 0.284M. The
endpoints of the titrations were recorded as follows
 COD= ((A-B)/vol of sample)*molarity*8000
 A-endpoint of blank sample in ml
 B-endpoint of sample in ml
 A sample from each source, of 50cc was put into a quick-fit flask.
A standard solution of distilled water was prepared alongside.
The quick fit flasks were then placed on a heating mantle. To
each, 1g of Mercury (II) Sulphate and 5cc of dichromate were
added to digest the sample. 75ml of conc. sulphuric acid were
added. Condensers were then connected on the fit-in flasks.
 The samples were refluxed for 2hrs and left to cool then 3 drops
of ferroin indicator were added to determine the endpoint
during titration.
 Titration were done using FAS of molarity as 0.284M. The
endpoints of the titrations were recorded as follows
 COD= ((A-B)/vol of sample)*molarity*8000
 A-endpoint of blank sample in ml
 B-endpoint of sample in ml

24. Total suspended solids analysis (Sharma B
K, 2004)
 A filter paper were weighed and recorded as
(B) in grams ,then three samples 100ml were
filtered through the filter papers then dried
at 105o c for 2hrs. After drying weight were
recorded as (A) in grams.
 Tss=(B-A/vol of sample in ml)*1000
 A filter paper were weighed and recorded as
(B) in grams ,then three samples 100ml were
filtered through the filter papers then dried
at 105o c for 2hrs. After drying weight were
recorded as (A) in grams.
 Tss=(B-A/vol of sample in ml)*1000

25. Total Phosphorous (Sharma B K, 2004)
Preparation of standard solution
 Phosphate buffer solution (pH 3.4) was prepared by dissolving 5.04 g of disodium hydrogen
phosphate and 3.01 g of potassium Dihydrogen phosphate in water and made upto 1000 mL.
Stock solution (1 mg/1 mL)
 100 mg of the sample stormwater was accurately weighed and transferred into 100 mL
volumetric standard flask and added phosphate buffer and made up to
100 mL with phosphate buffer.
Bromothymol blue solution
 50 mg of bromothymol blue was dissolved in 4 mL of 0.02 M NaOH and 20 mL of ethanol
(95%). After solution is effected, sufficient water was added and made upto 100 mL.
Absorption spectra for drug in bromothymol blue
 From the stock solution, 10 mL was taken and added with 1 mL of bromothymol blue and it
was diluted with 500 mL of phosphate buffer to make the concentration 200 g/mL. The
absorbance of the solution was measured with a wavelength of 880 nm in a UV 200-RS spectrophotometer.
 A representative sample from each standard and sample were analysed and results tabulated then
concentration curves (A graph of concentration against absorbance) were used to compute results using the
formula below).
Y=mx
Where y-concentration in mg/l
M-gradient
X-absorption
Preparation of standard solution
 Phosphate buffer solution (pH 3.4) was prepared by dissolving 5.04 g of disodium hydrogen
phosphate and 3.01 g of potassium Dihydrogen phosphate in water and made upto 1000 mL.
Stock solution (1 mg/1 mL)
 100 mg of the sample stormwater was accurately weighed and transferred into 100 mL
volumetric standard flask and added phosphate buffer and made up to
100 mL with phosphate buffer.
Bromothymol blue solution
 50 mg of bromothymol blue was dissolved in 4 mL of 0.02 M NaOH and 20 mL of ethanol
(95%). After solution is effected, sufficient water was added and made upto 100 mL.
Absorption spectra for drug in bromothymol blue
 From the stock solution, 10 mL was taken and added with 1 mL of bromothymol blue and it
was diluted with 500 mL of phosphate buffer to make the concentration 200 g/mL. The
absorbance of the solution was measured with a wavelength of 880 nm in a UV 200-RS spectrophotometer.
 A representative sample from each standard and sample were analysed and results tabulated then
concentration curves (A graph of concentration against absorbance) were used to compute results using the
formula below).
Y=mx
Where y-concentration in mg/l
M-gradient
X-absorption

26. Data collection
Selection of suitable sites
 Various sites were located according to susceptibility to occurrence of
pollutants.
 A total of three monitoring sites were selected within the Nakuru town
to represent the range of paved conditions and different types of
pollution concentration and variation. These sites were: a fuel
station, market place and industrial area.
Collection of samples
 Grab sampling were conducted from a storm event that produced a
discharge that were preceded by at least 72 hours of dry weather.
Collection were done during the first hour of downpour to ensure that
the first flush of runoff were taken as the representative sample.
 The water quality samples were collected at the edge of pavements as it
is a collection point, to represent untreated runoff.
Selection of suitable sites
 Various sites were located according to susceptibility to occurrence of
pollutants.
 A total of three monitoring sites were selected within the Nakuru town
to represent the range of paved conditions and different types of
pollution concentration and variation. These sites were: a fuel
station, market place and industrial area.
Collection of samples
 Grab sampling were conducted from a storm event that produced a
discharge that were preceded by at least 72 hours of dry weather.
Collection were done during the first hour of downpour to ensure that
the first flush of runoff were taken as the representative sample.
 The water quality samples were collected at the edge of pavements as it
is a collection point, to represent untreated runoff.

27. Site Map

28. RESULTS AND ANALYSIS
The sample collected (composite sample
from the 3 sampling points) was a control
sample to identify the presence of the
selected parameters if they were present in
the sampling points selected. Results
showed their levels as below:
The sample collected (composite sample
from the 3 sampling points) was a control
sample to identify the presence of the
selected parameters if they were present in
the sampling points selected. Results
showed their levels as below:

29. Element
Stormwater
concentration(mg/L)
effluent discharge
standards
TSS 1167 30
TP 2.43 2
COD 207.57 50
Pb 0.0283 0.01
Fe 2.077 3
Zn 1.278 0.5
Mn 3.122 10
Table 1 Results for composite sample
COMPOSITE SAMPLE ANALYSIS
10000
Comparison between concetrations with effluent discharge
standards
0.01
0.1
1
10
100
1000
10000
TSS TP COD Pb Fe Zn Mn
Concentration(mg/L)
Element
Stormwater
concentration(mg/L)
effluent discharge
standards
Figure 1 Comparison between concentrations with effluent discharge standards
Most parameters proved positive and were above effluent discharge standards as shown
in the graph above.

30. COMPARATIVE SAMPLING RESULTS
These samples were taken at 3 different sites to investigate the variation of concentration in the selected sites.
MARKET
Element Stormwater concentration(mg/L) effluent discharge standards
TSS 900 30
TP 0.305 2
COD 224 50
Pb 0.02 0.01
Fe 1.15 3
Zn 1.4 0.5
Mn 1.58 10
Table 2 Results for market sample
Mn 1.58 10
0.01
0.1
1
10
100
TSS TP COD Pb Fe Zn Mn
Concentration(mg/L)
Element
Comparison between Market concetration with effluent discharge
standards
Stormwater
concentration(mg/L)
effluent discharge standards
Figure 2 Comparison between concentrations with effluent discharge
standards

31. GARAGE
Elemen
t
Stormwater
concentration(mg/L)
effluent discharge
standards
TSS 1700 30
TP 1.92 2
COD 344.96 50
Pb 0.025 0.01
Fe 4.55 3
Zn 1.68 0.5
Mn 2.36 10
Table 3 Results for market sample
Comparison between garage concetrations with
effluent discharge standards
0.01
0.1
1
10
100
1000
10000
TSS TP COD Pb Fe Zn Mn
Concentration(mg/L)
Element
Comparison between garage concetrations with
effluent discharge standards
Stormwater
concentration(mg/L)
effluent discharge
standards
Figure 3 Comparison between concentrations with effluent discharge
standards

32. INDUSTRIAL AREA
Element Stormwater concentration(mg/L) effluent discharge standards
TSS 900 30
TP 2.33 2
COD 53.76 50
Pb 0.04 0.01
Fe 0.53 3
Zn 0.755 0.5
Mn 5.4275 10
Table 4 Results for market sample
Comparison between industrial area concetrations with effluent
discharge standards
Figure 4 Comparison between concentrations with effluent discharge
standards
0.01
0.1
1
10
100
TSS TP COD Pb Fe Zn Mn
Concentration(mg/L)
Element
Comparison between industrial area concetrations with effluent
discharge standards
Stormwater
concentration(mg/L)
effluent discharge standards

33. COMPARISON WITH EFFLUENT STANDARDS
Element
Stormwater concentration(mg/L)
Effluent discharge
standards
Industrial Area Market Garage Average
TSS 900 900 1700 1167 30
TP 2.33 0.305 1.92 2.43 2
COD 53.76 224 344.96 207.57 50
Pb 0.04 0.02 0.025 0.0283 0.01
Fe 0.53 1.15 4.55 2.077 3
Zn 0.755 1.4 1.68 1.278 0.5
Mn 5.4275 1.58 2.36 3.122 10
Table 5 Results for market sample
0.01
Comparison Between Average and Effluent Discharge Standards
Figure 5 Comparison between concentrations with effluent discharge
standards
0.1
1
10
100
1000
10000
TSS TP COD Pb Fe Zn Mn
Stormwaterconcentration(mg/L)
Element
Stormwater concentration(mg/L)
Average
Effluent discharge standards

34. DISCUSSION
Market
 The considerable amount of Pb, Zn, Mn and Fe at the
market was attributed to worn-out galvanised
rooftops, gutters which had been washed by stormwater. A
significant amount of these may have been contributed by
outdoor storage of scrap metals.
 Poorly managed construction sites were a major source of
T.S.S at the market area. Phosphorus content was well
within the safety region of emission.
 Residual food wastes from cans/bottles, anti-freeze and
emulsified oils contributed a significant amount of COD.
Market
 The considerable amount of Pb, Zn, Mn and Fe at the
market was attributed to worn-out galvanised
rooftops, gutters which had been washed by stormwater. A
significant amount of these may have been contributed by
outdoor storage of scrap metals.
 Poorly managed construction sites were a major source of
T.S.S at the market area. Phosphorus content was well
within the safety region of emission.
 Residual food wastes from cans/bottles, anti-freeze and
emulsified oils contributed a significant amount of COD.

35. Garage
 Amounts of Pb and Zinc were significantly above the KEBS
effluent emission standards, largely due to excessive vehicle
exhausts, worn-out brake linings, tyre and engine wear.
Lead was mainly from petroleum products and lubricants.
 TSS value was also quite high compared to the
standards, due to car wash activities. The sample contained
filterable particles of dust and traces of metallic elements.
 Total phosphorous was found to be high in carwash than
other points; this was due to detergents used in the car
washing.
 Discarded automotive batteries in the garage area also
contributed significantly to the presence of Pb and Zn in
the sample.
 Amounts of Pb and Zinc were significantly above the KEBS
effluent emission standards, largely due to excessive vehicle
exhausts, worn-out brake linings, tyre and engine wear.
Lead was mainly from petroleum products and lubricants.
 TSS value was also quite high compared to the
standards, due to car wash activities. The sample contained
filterable particles of dust and traces of metallic elements.
 Total phosphorous was found to be high in carwash than
other points; this was due to detergents used in the car
washing.
 Discarded automotive batteries in the garage area also
contributed significantly to the presence of Pb and Zn in
the sample.

36. Industrial Area
 Assemblage of metal parts, air
emissions, smelter, paints were notable major
causative source of presence of higher-than-standard
values of Zn and Pb.
 The high TSS value could be attributed to poor storage
and disposal of waste residues, causing them to be
washed away into the stormwater drain whenever
there is a downpour.
 Assemblage of metal parts, air
emissions, smelter, paints were notable major
causative source of presence of higher-than-standard
values of Zn and Pb.
 The high TSS value could be attributed to poor storage
and disposal of waste residues, causing them to be
washed away into the stormwater drain whenever
there is a downpour.

37. CONCLUSION
 The assessment was a success as the respective objectives
were achieved i.e. most parameters tested were above the
maximum permissible limit as per effluent discharge
standards in the third schedule.
 The three sampling points showed variation of pollutant
concentration and thus highlighted the sources of
pollution in runoff.
 Results showed that runoff has a variety of pollutants;
TSS, TP, COD, Zn, Pb, Mn and Fe. These pollutants pose
danger to our water resources and therefore treatment is
necessary in order to conserve our water resources.
CHAPTER FIVE
 The assessment was a success as the respective objectives
were achieved i.e. most parameters tested were above the
maximum permissible limit as per effluent discharge
standards in the third schedule.
 The three sampling points showed variation of pollutant
concentration and thus highlighted the sources of
pollution in runoff.
 Results showed that runoff has a variety of pollutants;
TSS, TP, COD, Zn, Pb, Mn and Fe. These pollutants pose
danger to our water resources and therefore treatment is
necessary in order to conserve our water resources.

38. RECOMMENDATIONS
 Source controls- this involves regulation of the amount and rate of
runoff from impervious areas i.e. good drainage systems
 Treatment control approaches– these are designed to remove
pollutants from the runoff i.e. bio retention systems.
A common collector runoff system, fitted with proper treatment
system and filtration mechanism, ought to be put in place so as to
achieve significant control against downstream pollution, mainly by
huge TSS and COD values other than Zn and Pb.
 Pollution prevention practices–These serve to keep chemicals
away from rainfall and/or runoff e.g. collection and better disposal
of litter. The industries, notably maize millers, Pesticide
producers, Agricultural machinery assembly lines e.t.c, in Nakuru
town, ought to be vetted by the municipal sanitary department to
curtail possibilities of continuous discharge of uncontrolled and
illegal untreated effluents into the stormwater drain.
 Source controls- this involves regulation of the amount and rate of
runoff from impervious areas i.e. good drainage systems
 Treatment control approaches– these are designed to remove
pollutants from the runoff i.e. bio retention systems.
A common collector runoff system, fitted with proper treatment
system and filtration mechanism, ought to be put in place so as to
achieve significant control against downstream pollution, mainly by
huge TSS and COD values other than Zn and Pb.
 Pollution prevention practices–These serve to keep chemicals
away from rainfall and/or runoff e.g. collection and better disposal
of litter. The industries, notably maize millers, Pesticide
producers, Agricultural machinery assembly lines e.t.c, in Nakuru
town, ought to be vetted by the municipal sanitary department to
curtail possibilities of continuous discharge of uncontrolled and
illegal untreated effluents into the stormwater drain.

39. REFERENCES
Allen P. Davis, Ph.D., P.E. ,2003, Standards for Effluent Discharge Regulations
General Notice No.44.of 2003, Department of Civil and Environmental
Engineering, University of Maryland College Park, MD 20742.
Kenya Environmental Management and Co-Ordination (Waste Management) Regulations,
2006
Klein, Richard, D., 1979.Urbanization and Stream Quality Impairment," Water Resources
Bulletin.
NRDC's (Natural Resources Defense Council),1999, online newsletter
Min Chu, P.E. ,1993, Quality of Storm Water Runoff from Urbanized Houston
Metropolitan Area, Turner Collie & Braden Inc., USA
Schueler, T. R, 1995. Site Planning for Urban Stream Protection, Metropolitan
Washington Council of Governments.
www.georgiastormwater.com
www.wikipedia.org/wiki/Spectrophotometer
Allen P. Davis, Ph.D., P.E. ,2003, Standards for Effluent Discharge Regulations
General Notice No.44.of 2003, Department of Civil and Environmental
Engineering, University of Maryland College Park, MD 20742.
Kenya Environmental Management and Co-Ordination (Waste Management) Regulations,
2006
Klein, Richard, D., 1979.Urbanization and Stream Quality Impairment," Water Resources
Bulletin.
NRDC's (Natural Resources Defense Council),1999, online newsletter
Min Chu, P.E. ,1993, Quality of Storm Water Runoff from Urbanized Houston
Metropolitan Area, Turner Collie & Braden Inc., USA
Schueler, T. R, 1995. Site Planning for Urban Stream Protection, Metropolitan
Washington Council of Governments.
www.georgiastormwater.com
www.wikipedia.org/wiki/Spectrophotometer

40. APPENDICES
Picture 1: Sampling point-Nakuru Market
Pictures

41. Picture 2: Weighing Balance

42. Picture 5 & 6: AAS-S11 Spectrophotometer and its Gas
cylinders

43. Picture 7: Carrying out COD test

44. LET’S MAKE NAKURU TOWN
AND AFRICA A TIDIER PLACE
TO LIVE IN!
THANK YOU FOR YOUR
ATTENTION!
LET’S MAKE NAKURU TOWN
AND AFRICA A TIDIER PLACE
TO LIVE IN!
THANK YOU FOR YOUR
ATTENTION!