WSE3701
Water and Sanitation Engineering III
Assessment 2 (Project) Answers
Year 2025
,TABLE OF CONTENTS
1.0 INTRODUCTION .................................................................................................. 4
2.0 STUDY AREA ...................................................................................................... 6
3.0 LITERATURE REVIEW ....................................................................................... 7
3.1 General features of sewerage systems ............................................................. 9
3.2 Design procedure ............................................................................................ 10
3.3 Location of sewers .......................................................................................... 11
3.4 Sewer depths .................................................................................................. 13
3.5 Minimum Size of Sewers................................................................................. 13
3.6 House Connections ......................................................................................... 13
3.7 Determination of depth of connection from a contour plan .............................. 14
3.8 Manholes ........................................................................................................ 16
3.9 Sewage flows .................................................................................................. 16
3.9.1 Average Dry Weather Flow (ADWF) ......................................................... 16
3.9.2 Peak factors .............................................................................................. 18
3.10 Estimating flows and choosing pipe sizes ..................................................... 18
3.11 Design formulae ............................................................................................ 19
3.11.1 Colebrook – White formula ..................................................................... 19
3.11.2 Manning’s formula .................................................................................. 20
3.11.3 Scobey formula ....................................................................................... 20
3.11.4 Strickler formula ...................................................................................... 20
3.11.5 Discharge................................................................................................ 21
3.12 Design Materials: Pipes and Joints ............................................................... 21
3.12.1 Glazed earthenware (clay) pipes ............................................................ 21
3.12.2 Concrete pipes........................................................................................ 22
, 3.12.3 Asbestos cement pipes .............................................................................. 22
3.12.4 Steel pipes .............................................................................................. 23
3.12.5 PVC pipes ............................................................................................... 23
4.0 DESIGN CALCULATIONS, SIMULATIONS AND SPECIFICATIONS .............. 24
4.1 Population projection ...................................................................................... 24
4.2 Applicable Water Demand .............................................................................. 25
4.3 Water Demand ................................................................................................ 25
4.4 Average Dry Weather Flow and Peak Wet Weather Flow............................... 25
4.5 Pipe Sizing ...................................................................................................... 26
4.5.1 Sizing of Sub-main sewer lines ................................................................. 26
4.5.2 Sizing of trunk sewers ............................................................................... 26
4.6 Computation of Part Full Flow ......................................................................... 27
5.0 RESULTS .......................................................................................................... 28
6.0 CONCLUSIONS ................................................................................................. 33
7.0 REFERENCES ................................................................................................... 34
, 1.0 INTRODUCTION
Wastewater engineering is that branch of environmental engineering in which the
basic principles of science and engineering are applied to solving the issues
associated with the treatment and reuse of wastewater. The ultimate goal of
wastewater engineering is the protection of public health in a manner commensurate
with environment, economic, social and political concerns. To protect public health and
the environment, it is necessary to have knowledge of
1. constituents of concern in wastewater
2. impacts of these constituents when waste is dispersed into the environment
3. the transformation and long- term fate of these constituents in treatment
processes
4. treatment methods that can be used to remove or modify the constituents found
in wastewater and
5. methods for beneficial use or disposal of solids generated by the treatment
systems.1
Population rise in South Africa has led to extension of some already existing
communities. In Rustenburg the average number of people per stand is six and the
population of the town has been growing of late.
The sewerage of Rustenburg extension has not yet been designed and it is the main
focus of this project. Generally, sewers are designed to follow the slope of the ground.
Sewage refers to the liquid itself, which is composed of excretion (with flush water)
and sullage. Sullage is wastewater from bathing, washing clothes, kitchen etc., and is
sometimes called “greywater” while the water from the water closet is referred to as
“blackwater”.
Sewerage is the system of sewer pipes collecting sewerage away from residential
areas to a sewage treatment plant. The reticulation may also comprise lift stations or
pumping stations and other ancillaries such as oil and grit traps. The objective of a
1
Wastewater Engineering: Treatment and Resource Recovery, 5th Edition, Metcalf & Eddy, Inc., George
Tchobanoglous, H. Stensel, Ryujiro Tsuchihashi and Franklin Burton, 2014
Water and Sanitation Engineering III
Assessment 2 (Project) Answers
Year 2025
,TABLE OF CONTENTS
1.0 INTRODUCTION .................................................................................................. 4
2.0 STUDY AREA ...................................................................................................... 6
3.0 LITERATURE REVIEW ....................................................................................... 7
3.1 General features of sewerage systems ............................................................. 9
3.2 Design procedure ............................................................................................ 10
3.3 Location of sewers .......................................................................................... 11
3.4 Sewer depths .................................................................................................. 13
3.5 Minimum Size of Sewers................................................................................. 13
3.6 House Connections ......................................................................................... 13
3.7 Determination of depth of connection from a contour plan .............................. 14
3.8 Manholes ........................................................................................................ 16
3.9 Sewage flows .................................................................................................. 16
3.9.1 Average Dry Weather Flow (ADWF) ......................................................... 16
3.9.2 Peak factors .............................................................................................. 18
3.10 Estimating flows and choosing pipe sizes ..................................................... 18
3.11 Design formulae ............................................................................................ 19
3.11.1 Colebrook – White formula ..................................................................... 19
3.11.2 Manning’s formula .................................................................................. 20
3.11.3 Scobey formula ....................................................................................... 20
3.11.4 Strickler formula ...................................................................................... 20
3.11.5 Discharge................................................................................................ 21
3.12 Design Materials: Pipes and Joints ............................................................... 21
3.12.1 Glazed earthenware (clay) pipes ............................................................ 21
3.12.2 Concrete pipes........................................................................................ 22
, 3.12.3 Asbestos cement pipes .............................................................................. 22
3.12.4 Steel pipes .............................................................................................. 23
3.12.5 PVC pipes ............................................................................................... 23
4.0 DESIGN CALCULATIONS, SIMULATIONS AND SPECIFICATIONS .............. 24
4.1 Population projection ...................................................................................... 24
4.2 Applicable Water Demand .............................................................................. 25
4.3 Water Demand ................................................................................................ 25
4.4 Average Dry Weather Flow and Peak Wet Weather Flow............................... 25
4.5 Pipe Sizing ...................................................................................................... 26
4.5.1 Sizing of Sub-main sewer lines ................................................................. 26
4.5.2 Sizing of trunk sewers ............................................................................... 26
4.6 Computation of Part Full Flow ......................................................................... 27
5.0 RESULTS .......................................................................................................... 28
6.0 CONCLUSIONS ................................................................................................. 33
7.0 REFERENCES ................................................................................................... 34
, 1.0 INTRODUCTION
Wastewater engineering is that branch of environmental engineering in which the
basic principles of science and engineering are applied to solving the issues
associated with the treatment and reuse of wastewater. The ultimate goal of
wastewater engineering is the protection of public health in a manner commensurate
with environment, economic, social and political concerns. To protect public health and
the environment, it is necessary to have knowledge of
1. constituents of concern in wastewater
2. impacts of these constituents when waste is dispersed into the environment
3. the transformation and long- term fate of these constituents in treatment
processes
4. treatment methods that can be used to remove or modify the constituents found
in wastewater and
5. methods for beneficial use or disposal of solids generated by the treatment
systems.1
Population rise in South Africa has led to extension of some already existing
communities. In Rustenburg the average number of people per stand is six and the
population of the town has been growing of late.
The sewerage of Rustenburg extension has not yet been designed and it is the main
focus of this project. Generally, sewers are designed to follow the slope of the ground.
Sewage refers to the liquid itself, which is composed of excretion (with flush water)
and sullage. Sullage is wastewater from bathing, washing clothes, kitchen etc., and is
sometimes called “greywater” while the water from the water closet is referred to as
“blackwater”.
Sewerage is the system of sewer pipes collecting sewerage away from residential
areas to a sewage treatment plant. The reticulation may also comprise lift stations or
pumping stations and other ancillaries such as oil and grit traps. The objective of a
1
Wastewater Engineering: Treatment and Resource Recovery, 5th Edition, Metcalf & Eddy, Inc., George
Tchobanoglous, H. Stensel, Ryujiro Tsuchihashi and Franklin Burton, 2014
