Project Report on Design of Waste Water Drainage System

Table of Contents
Abstract 2
Storm water: Term Introduction 2
Description of the project: 3
Purpose of the project 3
The area covered by the project: 3
The location of the area: 4
The size and population covered by the project: 4
The importance and land-use of the area: 4
Drainage network 5
The Project Horizon: 5
Topography of the area: 5
Flow of drainage (Gravity Drainage): 5
General description of the network: 6
Design Criteria: 7
Discharge time td: 8
Runoff coefficients: 9
Hydraulic Design: 10
Manholes distribution: 10
Kerbs and pavements allotment: 10
Calculations: 11
Runoff Flow: 11
Diameter of the pipe: 13
Distribution profile 16
Distribution table: 16
Intensity Duration Frequency (IDF) curve 17
Bibliography 18

Storm water is the water which is collected due to the rainfall, snowfall as well as melting of ice. This water gets evaporated or gets absorbed in the ground and may be get carried or flown away to the lakes, rivers, streams and other such water bodies that are nearby.
It should be ensured that there is proper disposal of the storm water that cannot be utilized for consumption. The waste water that cannot be treated or utilized should be disposed of through a sufficient and effective drainage system (Schmitt, Thomas, & Ettrich, Analysis and modeling of flooding in urban drainage systems., 2004). It also refers to handling of the accumulated and storm water in such a way that it does not possess any hazard to the locality in the future. Accumulation of the storm water also poses a huge threat of outbreak of diseases due to the dirt, germs and dangerous insects that may arise in these water. This may lead to a very bad condition and health to the people in these communities and make the entire locality disease prone. Therefore, it has to be ensured that the sewer system that is adopted is sufficient enough to save the locality from such outbreaks and contribute towards the cleanliness of the city. I am going to develop a design that will help to provide a solution to the management of the waste water problem.
Storm water: Term Introduction
Storm water drainage system refers to the system which is designed and adopted to drain the excess water from the various areas of the city and other streets that gets occupied or logged due to the improper drainage facility (Prowell, 2006).
This kind of storm drain does not create much problem in the natural landscapes like hills and forests as they get absorbed by the thick soil present there along with their absorption by the plants and the trees present there. But, these storm drain can pose a very serious problem in the urban areas where they do not get enough soil as well as plants and trees to absorb it.
It poses the two kinds of major problems for the city and they are flooding of such water on being accumulated in large quantities and the other issue is the threat of water pollution that can be created by excessive storage of these unabsorbed storm water. Accumulation of this water in the streets of the city, sidewalks on the streets, roofs of the houses and throughout the parking lots needs to be managed before it tends to create any of the problems to the surroundings and affects the health of the people in the locality. Thereby, it is important to channelize these water before it poses a threat to the environment around it (Prowell, 2006).
The demand of water for commercial and consumption purpose is also on the increase in the urban areas due to meagre amount of natural water resources available in the cities. Thus, it is observed that there is a huge scarcity of water which can be utilized for the household purposes and daily consumption in the cities. However, through proper management and channelization of the available water can provide a solution to these shortage (Walsh, Fletcher, & Ladson, 2005). This also involves proper treatment of the water that is led into the water resources like lakes, rivers and other such pure water resources. It refers to developing a system that carries the waste water out of the city without creating much problems for the people in the locality.
Description of the project:
I am going to prepare a design of a drainage system that will help to dispose the waste water from the locality. There are various things and researches that we are going to cover in our project. They are listed below along with the description of the elements related to it:
Purpose of the project
The purpose of the project is to design a sewer system for the Al Muhaisnah 3 locality in Dubai situated in United Arab Emirates (UAE).These sewer system will help to channelize the storm water that gets collected in the locality and that can generate various threats to the community in terms of their health. Floating of water in the streets and localities leads to various problems like damaging and cracking of the streets, water pollution due to the accumulation and contamination of such water and a huge amount of traffic jams. This sewer system will tend to provide proper drainage of this floating and accumulated water. This system will target to channelize the storm water that gets collected and accumulated in the city lanes, parking lots and other such areas. This will help the community to overcome the problem of water logging which persists due to heavy rainfall or any other potential consequences of water logging (Prowell, 2006). Water management is required in these community to ensure the smooth flow of operations, vehicles and people across the road within the community that will be achieved by this system of sewer water treatment. This area is largely habited by the labourers and other related camps. This labourers contribute mainly in the construction of various projects in the Al Qusais as well as the real estate projects executed to the south of the Dubai creek.
The area covered by the project:
The size of the locality that has been selected comes under Muhaisnah area which is spread around 13 sq. mms or 5 sq. miles. It has the major part of the land used for residential and habitation purposes. With an approx. population of 90000 people, this area serves to be the locality for a community that has been developed and flourished in Dubai since a long time and are involved in the construction projects (Fleming, 2000). This area is a part of the locality that is situated in the Eastern Dubai in Deira region. The region is affected by accumulation of water near the roads due to the design of sewer system that consists mainly of manholes and gutters provided along the sides of the streets in this locality.
The location of the area:
Al Muhaisnah 3 is connected to the west part by route D60 through Al Rashidiya road. It is bordered by Al Qusais, Al Twar, Mirdif and Al Mizhar. This area is a part of the locality that is situated in the Eastern Dubai in Deira region. The locality of the Al Muhaisnah 3 that has been selected comes under Muhaisnah area. Muhaisnah is further divided into four localities and they are: Madinat Muhaisnah (Muhaisnah 1); Muhaisnah 2; Muhaisnah 3and Muhaisnah 4.
The size and population covered by the project:
The community is situated to the east of Dubai and is spread over a region of 13 sq. kms or 5 sq. miles. It has a population of around 90000 people. The density of the people is only around 7000 people/ sq. km which is very large. Hence, there is a lot of space that is available for the storm water to be accumulated if not taken care of at the right time. There is a huge scope for improvement in the infrastructure due to the available land that is largely habited by the people. There is a huge space for the infrastructure amenities like roads and parking lanes that are available that need to be provided with the proper slope or design to ensure that water does not get logged in (Fleming, 2000). This area is mainly habited by the labourers from the South Asian nations that are involved in the construction projects towards the south of Dubai creek. This area was once a very famous burial ground of Dubai.
The importance and land-use of the area:
The area is residential of the working class and hence needs to be taken care of because it poses the threat of improper accumulation of the water resources in the lanes, parking lots and other such areas which are near to the houses where people stay. Hence, it is of utmost importance to channelize this water to avoid the health hazards that may arise due to the pollution created by the storm water (Bryan, 1972). The proper execution of the system developed for the evacuation and management of storm water into the nearby disposal source creates cleanliness on the streets and ensures a healthy environment to live in for the community. It also helps to eradicate the water that has been released or accumulated by the industries that occupy a very small portion of this locality (VanWoert, Rowe, Andresen, Rugh, & Fernandez, 2005). The people living in the area are mostly from the labourers section and hence special measurements and precautions are required to ensure the cleanliness in the locality. It also involves involving them in the process by obtaining the accurate and precise design that would be favourable for them too. These area serves to be extremely dense and hence has to be taken special care.
Drainage network
The Project Horizon:
The area is designed for approximately 35-40 years because in the future if the horizon is needed to be enlarged it will require further modifications and maintenance. The area is mostly residential and it is divided to 8 major blocks on the basis of the streets as we can see in the picture. The community has human habitation spread in large numbers over a small area and hence provides a limited opportunity to utilize the space for the construction of the system (Walsh, Fletcher, & Ladson, 2005). The area which is to be considered is shown in the image. The direction of the Sewer system is taken as ranging from the elevation in the east towards the lower areas in the west. The area is split on the basis of the lanes and the directions are provided as per the streets in the locality. The regions towards the east are to be at higher inclination and hence the network is to be started from the east.
Topography of the area:
This area has a drainage with pumps and has man holes along the pavements with kerbs for the drainage of the water through the surface of the road. It has a slope from 90-85. The flow of the water will depend on the gravity and the direction of the water that flows in through the surface. This, therefore, will support the flow of water starting from the point shown in the map on the right extreme down corner. The area is divided at various places by the changes in the lanes and street and it has man holes created to absorb the surface water that is being accumulated on the surface along these roads. The topography of the area has exactly seven contour lines and the first top contour line has an elevation of 90 m and the last one on the bottom has an elevation of 85 m. Along with the design of the man holes, there has to be proper design which ensures that sufficient number of kerb, that is, stone edging or pavement created at the corner of the roads and parking lanes to ensure that the water level does not rise above a particular level and does gets carried away in a systematic and smooth way (Walsh, Fletcher, & Ladson, 2005). The construction of kerbs and stone pavements should be followed by appropriate gutters and grills at the side of the road to carry the flow from the side of the road that does not get carried in the man holes.
Flow of drainage (Gravity Drainage):
The path which is selected for the sewer system is such that it will provide enough scope for the water to flow across the surface by virtue of its gravity from an elevation to a reduced height. This is obtained by proper channelization of the route through which the storm water will flow. This type of drainage helps to use the force of gravity to ensure smooth flow of the storm water to the disposal or other resources through the city roads without much external pressure or pumps required (Schmitt, Thomas, & Ettrich, Analysis and modeling of flooding in urban drainage systems., 2004). The use of pumps will be limited because the water will seep through the gutters at the corner and the man holes present at the centre. The force of gravity will be utilized by beginning from a point or a junction at the east corner of the locality and gradually moving up in the west direction. It has few changes in the direction which involve moving down the street and going across the lane across the community. The drainage system takes the advantage of the geographical slopes that are observed in these region to be considered (Archdeacon, 2005). The west side gradually opens to the sea coast after a long interval of time.
General description of the network:
The route which is to be created for the storm water to flow through the road is along the 8 streets as shown in the figure. The route consists of specific lines and track that is to be followed as observed in the figure. There are various junction points developed throughout the network. It is at these junctions that the route will take a turn or change its course from the system (Schmitt, Thomas, & Ettrich, Analysis and modeling of flooding in urban drainage systems., 2004). So, special care needs to be taken while designing and developing these junctions as there are maximum chances of water getting logged at such corners or it may also tend to change its direction which is also not desirable. Hence, proper care needs to be taken at this places which have the maximum scope of error or distortion of the storm water (Adams & Papa, 2000).
The drainage system is designed to take in any rate of flow in the area starting from the east towards the west throughout the 8 blocks. This water is then graduated towards the inclination in the west direction. It is also observed that proper track and path of this water is specified so as to avoid the jamming on the roads and places which are having high value from tourist point of view.
The design and the channelizing of the pipes through the sewer system is made such that they tend to face least number of obstacles over the surface while carrying the storm water to its disposal or desired place (Mays, 2001). There has also been terms that are to be taken care of while developing the design of the sewer system so as to make sure that it does not affect the working and flow of operations in this region. The lines that are to be provided are designed and developed after considering the topography of the region as discussed earlier. The points that are at a greater height from the sea level, that is, which are at an elevation are first determined. It is then followed by deriving its course for the flow of the water through the pipes. It involves considering the points that are gradually towards the west and are comparatively at a lower height from the sea level as compared to the points in the east (Schmitt, Thomas, & Ettrich, Analysis and modeling of flooding in urban drainage systems., 2004).
The construction of kerbs along the pavements is also to be made in such a way that it provides sufficient space for the utilization of roads and the lanes for other purposes. Thus, it must be made sure that optimum utilization of space is carried out. This will not only help in saving space but also provide a scope and setup for infrastructural facilities and other recreational activities. The tourism can also be worked upon for the saved region and contribute towards its increase that would ultimately benefit the people living in the locality.

Design Criteria:
The design of the sewer system is to be made by considering various parameters and elements that tend to affect the development of the project. Designing elements are to be defined and at the same time determined for a specific set of variables (Mays, 2001). We are going to observe and go through variables that are essential in the construction of the design of the waste water drainage system. These parameters are explained and derived below:
Discharge time t_d:
It refers to the time that is required by the flow to get across the pipe through different point of time. The estimation and the figures that are used here are taken as per the Municipality specifications and the norms that are mentioned and followed by them. The number of years that is to be considered is ranging from 2 years to 100 years considering the feasibility of the project with respect to the flow and the rate of flow. In the table shown below, we have obtained the relationship between the rates of flow of storm water at different Return period (T) for a given discharge time duration given byt_d.

The results that are obtained from the table show that the flow rate depends on the area and intensity of the storm water that is flowing through it. The duration or the Return period (T) is independent of the material of the pipe but depends on the area of the pipe through which it flows. This can be obtained by calculating the discharge across the pipes for a specific amount of time. The flow of the pipes is measured and obtained at an interval of few years. The amount of the flow that gets fluctuated is to be observed from the table (Adams & Papa, 2000). The table also provides guidelines on the discharge that will be obtained by a specific dimension of pipe over a period of years. The discharge is to be measured at regular intervals of time to ensure that proper drainage from time to time in the locality. The run- off coefficients of these pipes are to be taken into consideration to develop the pipes design in details.

Runoff coefficients:

It refers to the surface friction factors that the different material possess. The co – efficient of the run off tend to determine the intensity and smoothness of the flow of the water across it.
The run off coefficients also tend to help to make an estimation of the life of the pipe that would be able to sustain the flow of sewer across it for a particular period of time. The coefficients help to understand the friction that the pipes will undergo when the sewer water drain flows through it (Schmitt, Thomas, & Ettrich, Analysis and modeling of flooding in urban drainage systems, 2004).
The coefficients value also tend to provide the calculation with an edge to carry the necessary steps and analysis to design the pipe for the project purpose on the basis of the strength of the materials that are shown in the table below. The run off coefficients of various substances are shown in the table and the type of land is also mentioned.

Hydraulic Design:
The most affectively factor in the project is the velocity of water in the pipes that depend mostly in the slope of the pipe used. The minimum range is 1.55m/s and the maximum is 2.95m/s. the hydraulic design of the structure tends to provide with the strength and reliability of the design and calculation in terms of the life of the pipes. The hydraulic design helps in better understanding of the features that are to be considered while designing the sewer drain. It also involves developing elements and parameters that will help to ensure that the project will be able to sustain the different hurdles and obstacles that are offered by the nature (Harremoves & Rauch, 1996). The effectiveness of the hydraulic design will provide the confirmation of the life and safety of the project and thereby, of the people in contact with it. The characteristic feature of the hydraulic design id the strength which the material will offer when it is performing a task.
Manholes distribution:
It is observed that approximately minimum value of a manhole spacing is of 150mm to 200mm and the maximum is around 1300mm. The manhole space varies depending on the slope from north to south and from west to east. The selection of the sites and location for construction of man holes needs to be made by considering parameters that are related to the area, locality, density and design of the road pavements above the surface (Peterson & Wicks, 2006) . It also helps to determine the path through which the pipelines will be crossing across the man holes and serve as a guide to provide them the course. The design of the man holes should utilize optimum availability of free surface on its side and this will ensure that timely drain of water along the roadside is done.
Kerbs and pavements allotment:
The kerbs are gutter like structures made along the pavements of the road at the corner along its surface. The construction of the kerbs along the corners of the roads should be made such that it can take sufficient amount of water through it and this would thereby reduce the load on the sewer pipe. The alignment of the pavements should be made such that it is in the direction of the slope that is existing in the region (Peterson & Wicks, 2006). Hence, hardly, any force or external device will be required to drain the water along the surface. The allocation of space and its utilization on the road surface is made such that it does destroy the look of the infrastructure above and at the same time helps to drain the storm water efficiently throughout the surface. Pavements are also utilized for other purposes like stalls and open shops. Hence, optimum utilization of the pavements is required while developing the design of kerbs along the streets. This also involves developing a design that will ensure maximum flow of water to be carried through the drainage system across the street.
There are various variables that are to be determined during the design and analysis of the storm drain project. They are as follows:
Runoff Flow:
The measure of the flow of water or any other liquid while it is running or flowing is termed as the run off flow. The run off is measured in terms of m^3/hr and the unit is same as that of any other flow of liquid along a surface. The run off is measured by the following way (Peterson & Wicks, 2006):

Rational method is used to calculate the runoff flow; which is
Q=The water flow rate (m^3/hr) C=Runoff coefficient
I=Rainfall intensity (mm/hr) A=Drainage area (m^2)

There are eight main blocks through which the flow is carried out. Here, we are going to observe the flow calculations of lines 1, 3, 4 and 7 during the discharge across the surface. The areas of the pipes A is determined and taken accordingly.
Runoff across the Line 1A:

C_1=0.4 I_1=0.045m/hr A_1=14500m^2


Runoff across the Line 3A:

C_3=0.4 I_3=0.065m/hr A_3=5300m^2


Runoff across the Line 4A:

C_4=0.4 I_4=0.063m/hr A_4=5400m^2


Runoff across the Line 7A:

C_7=0.4 I_7=0.063m/hr A_7=6800m^2

Q_7=0.4×0.063×6900+1190+1037.4=2771 m^3/hr
Here for the proper and precise estimation of the run off, we are going to measure it twice for the same pipes to ensure that any kind of error is not made in making the dimension of the pipe.
Runoff across the Line 1B:

C_1=0.4 I_1=0.055m/hr A_1=14500m^2


Runoff across the Line 3B:

C_3=0.4 I_3=0.070m/hr A_3=5300m^2


Runoff across the Line 4B:

C_4=0.4 I_4=0.068m/hr A_4=5400m^2


Runoff across the Line 7B:

C_7=0.4 I_7=0.063m/hr A_7=6800m^2

Q_7=0.4×0.063×6900+1290+1037.4=2781 m^3/hr

From the above calculations, we get the estimation about the flow that is the discharge through the pipes.
Diameter of the pipe:
The diameter of the pipe through which the storm water is going to flow is to be determined and this is done by the following formula (Harremoves & Rauch, 1996):
D=〖((Q×4×n×4^(2/3))/(π×S^(0.5) ))〗^(3/8)

D=Diameter in (m) n=coeffiecient of roughness
S=Slope (m/m) Q=water flow (m^3/s)

Diameter of the pipe in Line 1A:
Q_1= 0.085m^3/s n = 0.023 S_1= 0.006
D_1=〖((Q×4×n×4^(2/3))/(π×S^0.5 ))〗^(3/8)= 〖((0.085 × 4 × 0.023 × 4^(2/3))/(π × 〖0.006〗^0.5 ) )〗^(3/8)=0.380m

Selected pipe size=0.40m=400mm

Diameter of the pipe in Line 3A:

Q_3=(0.325m^3)/s n = 0.014 S_3= 0.0023
D_3=〖((Q×4×n×4^(2/3))/(π×S^0.5 ))〗^(3/8)= 〖((0.325 × 4 × 0.014 × 4^(2/3))/(π × 〖0.0023〗^0.5 ) )〗^(3/8)=0.68m

Selected pipe size=0.70m=700mm

Diameter of the pipe in Line 4A:

Q_4=(0.325m^3)/s n = 0.014 S_4= 0.0023
D_4=〖((Q×4×n×4^(2/3))/(π×S^0.5 ))〗^(3/8)= 〖((0.325 × 4 × 0.014 × 4^(2/3))/(π × 〖0.0023〗^0.5 ) )〗^(3/8)=0.68m

Selected pipe size=0.70m=700mm

Diameter of the pipe in Line 7A:

Q_7= 0.70m^3/s n = 0.013 S_7= 0.0025
D_7=〖((Q×4×n×4^(2/3))/(π×S^0.5 ))〗^(3/8)= 〖((070 × 4 × 0.013 × 4^(2/3))/(π × 〖0.0025〗^0.5 ) )〗^(3/8)=0.98m
Selected pipe size=1m=1000mm

Here, to avoid any kind of error we will be calculating diameter of the pipe twice.
Diameter of the pipe in Line 1B:
Q_1= 0.102m^3/s n = 0.013 S_1= 0.005
D_1=〖((Q×4×n×4^(2/3))/(π×S^0.5 ))〗^(3/8)= 〖((0.102 × 4 × 0.013 × 4^(2/3))/(π × 〖0.005〗^0.5 ) )〗^(3/8)=0.388m

Selected pipe size=0.4m=400mm

Diameter of the pipe in Line 3B:

Q_3=(0.325m^3)/s n = 0.018 S_3= 0.0028
D_3=〖((Q×4×n×4^(2/3))/(π×S^0.5 ))〗^(3/8)= 〖((0.325 × 4 × 0.014 × 4^(2/3))/(π × 〖0.0023〗^0.5 ) )〗^(3/8)=0.67m

Selected pipe size=0.70m=700mm

Diameter of the pipe in Line 4B:

Q_4=(0.325m^3)/s n = 0.015 S_4= 0.0025
D_4=〖((Q×4×n×4^(2/3))/(π×S^0.5 ))〗^(3/8)= 〖((0.325 × 4 × 0.014 × 4^(2/3))/(π × 〖0.0023〗^0.5 ) )〗^(3/8)=0.69m

Selected pipe size=0.70m=700mm
Diameter of the pipe in Line 7A:

Q_7= 0.70m^3/s n = 0.012 S_7= 0.0026
D_7=((Q×4×n×4^(2/3))/(π×S^0.5 ))^(3/8)= ((070 × 4 × 0.013 × 4^(2/3))/(π × 〖0.0025〗^0.5 ) )^(3/8)=0.975m
Selected pipe size=1m=1000mm

The runoff for the pipes considered and their diameters thus obtained help to provide the estimation and design of the sewer pipe that would be required for the storm drain along the surface following the slope.

Distribution profile

Distribution table:
The run offs that is the flow of the waste water and the estimated sizes of the pipes along with the selected sizes of the pipes are calculated for all the 8 streets that we have considered.
The calculations are tabulated as shown below:


Name of the street Flow (Q)
(m3/hr) Pipe Size
Calculated (mm) Pipe size
Selected (mm)
1 34 B street 352.2 388 400
2 9 B street 690.4 448 450
3 30 A street 1219 680 700
4 5th street 1390 690 700
5 24th street 2580 880 900
6 18th street 2652 935 950
7 9 A street 2771 980 1000
8 A 15 street 2980 995 1000
Intensity Duration Frequency (IDF) curve
This is the frequency intensity that is measured against the duration of the rainfall and is observed for a period of 15 years. The main focus of this relationship is to observe the intensity of rainfall within a particular region and at the same time also focus on the side effects that it produces on the storm water drain system.

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Posted on

March 9, 2018

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