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CIVN7068
By Himkaar D. Singh
University of the Witwatersrand
24/08/2015
Diepsloot Surface Water
Technical Report
Abstract
Diepsloot is facing major surface water drainage problems. A trial section in Diepsloot
was chosen for a roads design with grass paving blocks and sub-surface drains. The
grass paving blocks add to visual appeal and reduce the runoff coefficient. The grass
paving blocks have the potential to reduce runoff by 50%.
Diepsloot Surface Water Technical Report
By Himkaar D. Singh ii
Contents
PART 1 PROBLEM DEFINITION 1
1.1 Introduction 1
1.2 Current Issues 2
PART 2 LITERATURE REVIEW 5
2.1 Sustainable Urban Drainage Systems 5
Permeable Paving 5
Rainwater Harvesting 10
Swales 12
2.2 Proposal 14
Design 14
Discussion 14
Limitations 18
Areas for Future Research 18
PART 3 CONCEPT DESIGN 19
3.1 Locality 19
3.2 Design 21
3.3 Calculations 21
3.4 Conclusion 22
3.5 Appendices A
Appendix A: Locality A
Appendix B: Paving Block Specifications C
Appendix C: Drainage Calculations F
Appendix D: Layout and Drainage Plans M
3.6 Bibliography I
1
Part 1 Problem Definition
1.1 Introduction Diepsloot is a high population density informal settlement on the outskirts of Johannesburg.
It is zoned as “Region A” in the (2012/16) Johannesburg Integrated Development Plan (IDP).
The IDP highlights Diepsloot as a high priority development area in the Joburg 2040 strategy.
As part of the IDP’s goals, “the City of Johannesburg has commissioned a study to upgrade
the storm water system in Diepsloot, using conventional engineering strategies. The vast
cost associated with this plan throws into question whether this is the most effective
approach. Current thinking around the world points to more sustainable strategies that
combine the provision of social amenities and visual enhancement while meeting the
pragmatic need of surface water management” (Fitchett, 2015) . The purpose of this report
is to identify and design a storm water management intervention that will alleviate
Joburg 2040 Outcomes
Outcome 1: Improved quality of life and development-driven resilience for all
Outcome 2: Provide a resilient, liveable, sustainable urban environment –
underpinned by infrastructure supportive of low-carbon economy
Outcome 3: An inclusive, job intensive, resilient and competitive economy
Outcome 4: A leading metropolitan government that pro-actively contributed
to and builds a sustainable , socially inclusive, locally integrated and globally
competitive Gauteng City Region (GCR)
Source: (City of Johannesburg, 2015)
Image: www.candychang.com
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 2
Diepsloot’s surface water issues. The focus is on a ‘structural’ intervention, which is
expected to be supported with a ‘non-structural’ intervention.
1.2 Current Issues Diepsloot is facing unregulated population growth that is putting strain on the already
inadequate infrastructure. The issues related to surface water include:
Insufficient storm water infrastructure
Litter entering and blocking storm water pipes
Children playing near dirty, standing water
People discarding their dirty water into the street
Burst water pipes flooding streets
Erosion of gravel roads during storms - gullies are forming in some places
Lack of vegetation and permeable surfaces
Poor access for emergency vehicles
Lack of open space in-between dwellings
Inconvenient surfaces for cars and pedestrians
There are some asphalt surfaced roads that are in good condition, but where
drainage is a problem the roads are damaged and are in need of maintenance
Mostly impermeable surfaces
Image: (Skuy, 2013)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 3
Erosion forming gullies
Image: (Fitchett, 2015)
Blocked sewer pipe spilling over
Image: (Dube, 2015)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 4
Road in good condition
Image: (Diepsloot Online, 2015)
Grey water discharged onto street
Image: (Honorine, 2008)
5
Part 2 Literature Review
2.1 Sustainable Urban Drainage Systems There is a large variety of Sustainable Urban Drainage Systems (SUDS) that have been
proven to reduce the negative impacts of flood events. Each has its own characteristics and
needs to be studied for the particular application. After a cursory analysis, it was decided
that permeable paving rainwater harvesting and swales may be the best solutions for
Diepsloot’s surface water issues – so they will be investigated further. Other solutions
include green roofs, wetlands and detention storage.
Permeable Paving
Permeable paving is a system of paving that allows water to infiltrate through the paving
blocks (porous block) or through gaps in-between blocks (permeable surface) (Diyagama, et
al., 2004). These systems are growing in popularity because “these systems have been
shown to be very successful in protecting both water quality of small and vulnerable
streams, and in reducing peak flood flows” (Interpave, 2010). Permeable paving aims to
increase infiltration into sub-bases that are designed to receive water, or to store storm
water for slow release (Concrete Manufacturers Association, 2010).
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 6
Porous block paving demonstration
Image: (Harrison, 2011)
Kikuyu Grass block paving in a parking lot
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 7
The subsurface system under the paving blocks can can either consist of permeable
layerworks that allow infiltration into the natural ground water system, or consist of a
drainage system that slowly channels the water to a larger stormwater network.
Porous block paving
Permeable surface paving
Images: (Diyagama, et al., 2004)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 8
The major drawback for permeable pavements as a solution to Diepsloot’s surface water
problem is that they require significant design considerations. There are, however,
numerous design guidelines (such as that by Diyagama, et al. (2004)) for permeable paving.
Subjects to consider in the design:
Objectives and use (traffic and stormwater)
Permeable paving types
Structural layer works design
Infiltration rates
Water quality objectives
Construction techniques
Maintenance
Benefits
Providing a structural pavement while allowing rainwater to infiltrate into the
pavement construction for temporary storage
Playing an important part in removing a wide range of pollutants from water
passing through
Allowing treated water to infiltrate to the ground, be harvested for re-use or
released to a water course, the next management stage or other drainage
system
Suitable for a wide variety of residential, commercial and industrial
applications
Optimising land use by combining two functions in one construction:
structural paving combined with the storage and attenuation of surface water
Handling rainwater from roof drainage and impervious pavements as well as
the permeable paving itself
Source: (Concrete Manufacturers Association, 2010)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 9
Case Study
Source: (Concrete Manufacturers Association, 2010)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 10
Rainwater Harvesting
Rainwater harvesting is mainly used to aid drinking water supply, but also has a use as a
storm water management technique. Rainwater harvesting has many definitions depending
on purpose and type of storage but the definition accepted in this report, is that mentioned
by Lasage & Verburg (2015); “Water harvesting includes all small scale schemes for
concentrating, storing and collecting surface run-off water in different mediums, for
domestic or agricultural uses.” Water harvesting in informal settlements is usually achieved
through a guttering system that channels water from a roof to a storage tank.
During a storm, harvesting the rainwater effectively attenuates the runoff from roofs, to a
rate that the water is later released by humans. Although the individual effect of rainwater
harvesting on flood peak may be small, the combined effect of many houses harvesting
water can significantly reduce the flood peak. This means that for rainwater harvesting to
have a large impact on flood peak, it needs to be applied on a large scale. A great benefit of
rainwater harvesting, especially in a low income community, is the ability to use the water
when and how one desires.
In an informal settlement rainwater harvesting may not be practical because dwellings tend
to be constructed of inferior materials and poor building practices. The guttering system
may pose a risk to structural stability if not designed properly. Since each dwelling is
different, individual harvesting designs will be needed – which may not be practical. An
issue of concern in informal settlements is open space, so it may be difficult to allocate
space to storage tanks. Rather than storing the water in a tank, there does exist the
possibility of using rainwater harvesting to recharge ground water aquifers – but from Civil
Concepts’s (2010) geology investigation, it was found that some sands are collapsible so it
may be high risk to introduce water into the ground.
Gutter directing water from a roof to a storage tank
Image: (Rainharvest, 2010)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 11
Rainwater harvesting is usually labour intensive to construct, and capital expensive at the
construction phase. A study by Lasage & Verburg (2015) showed that water harvesting costs
approximately US$ 1 per m3 to US$ 9 per m3 (2009) for small structures, and “for smaller
structures, less technical knowledge is needed, the initial investment cost is smaller, and the
governance is less complex than in the case of larger structures.”
Rainwater harvesting faces legislative, institutional and financial challenges but also offer
opportunities for goverrnment programmes and Non Governmental Organisations (Kahinda
& Taigbenu, 2011).
Rainwater harvesting forms part of a sustainable household
Image: (Kalebaila, 2013)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 12
Swales
A swale is a basin of vegetation that holds storm water for an extended period of time so
that contaminants can be removed (Harris, et al., n.d.). Swales offer flood attenuation while
providing visual enhancement – so much so that they are increasingly being adopted in
residential areas. A guide to using swales in informal settlements has been created by
Harris, et al. (n.d.) from studying the informal settlement of Langrug.
A detailed study of the hydraulic performance of swales found that swales can eliminate
runoff for low rainfalls events and significantly reduce flow magnitudes for high rainfall
events (Davis, et al., 2011).
Runoff from roads is usually contaminated with pollutants from vehicles using the roads.
Contaminants can originate from sources such as oil leaks from vehicles and normal wear
from braking. Swales have been found to significantly improve runoff quality through
filtration and sedimentation – a study on the performance of grass swales for improving
water quality from highway runoff showed that suspended solids, nitrogenous compounds
[found in soaps], phosphorus and heavy metals were significantly treated by swales (Stagge,
et al., 2012).
“…it is recommended that grassed swales should be constructed with a relatively wide, flat
bottom to promote slow and even flow rates and to avoid channelization, erosion, and high
Attractive swale in a residential area
Image: (MidtownAtlanta, 2015)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 13
velocities” (Wyoming Department of Environmental Quality, 2013), so it may be difficult to
construct in an informal settlement with scarcity of open space. The Wyoming Department
of Environmental Quality highlights the following advantages and limitations of swales:
Advantages
Effective for removing sediment and other particulate pollutants
Can reduce peak runoff volume and velocity
Promotes infiltration and can provide ground water recharge
Useful for treating runoff from highways and other roadways due to their
linear structure; good retrofit option for existing drainage ditches
Less expensive to build than traditional curb and gutter systems
Good pre-treatment option when used in conjunction with other BMPs
Do not cause warming of downstream waters and therefore, are a good
option for areas with cold water streams
Limitations
Individual swales can only treat runoff from a small drainage area of 5 acres or
less
Require higher maintenance than curb and gutter systems
Use in highly developed areas is fairly limited due to space constraints
Not recommended for use in drainage areas with high sediment loads or with
high levels of contaminants due to potential clogging or potential ground
water contamination
If used in arid or cold climates, adjustments and increased maintenance must
be made to ensure effectiveness
Do not seem to be effective at removing bacteria
Improperly designed or installed swales may not effectively remove pollutants
Vegetation must be maintained for swales to properly function
Concern for creating potential breeding habitat for mosquitos with wet swales
(Wyoming Department of Environmental Quality, 2013)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 14
2.2 Proposal
Design
The main objectives of the design are to visually enhance living spaces with vegetation,
while providing sustainable storm water management.
It is proposed to surface the main access roads with grass paving blocks. The main access
roads will contain sub-soil drains in their centres, or wherever suits the existing terrain best.
The alleys will be lined with grass paving blocks and will not usually have sub-soil drains. The
design is not a standard specification to be applied everywhere – but rather a concept to
guide the design of each area. A detailed design can be done if survey information is
available, but it is encouraged to do the construction by ‘eye’ according to the principles.
The design will be tailored so that it can easily be compared to Civil Concepts’s (2010)
conventional storm water network design.
Discussion
It can be assumed that the majority of residents have experienced a storm water event and
have identified the areas around their dwellings for storm water concern. They have already
modified their property to drain the water to the nearest open spaces, which are the streets
Image: (German Embassy Pretoria, 2015)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 15
and alleys in-between dwellings. The people have already done the work of draining their
properties, so this can be considered a ‘construction step’. It can be assumed that this
construction step is complete, so the focus should be to manage the water in the streets
and alleys.
Special consideration should be given to residents who were not able to drain the water
from their properties – in some cases, the dwellings receive the brunt of the upstream flow
and undermining of the surface slabs is occurring. In this case, simply protecting the slabs
will not work. It will be necessary to reduce the flow upstream of the dwelling by reducing
runoff upstream. This means that, where possible, the storm water management plan
should be implemented from upstream areas towards downstream areas.
Since dwellings have been modified to drain storm water into the streets, without preparing
the streets to receive this water, erosion is occurring and gullies are forming. This can be
used as an advantage because the erosion has exposed the more stable material, so
construction can occur without needing as much earthworks. Additionally, a conventional
road design would drain the water to the sides of the road using a cambered road – but
since the road in the settlement is not a high class road - the water does not necessarily
need to be drained on the sides. Thus, a reverse camber can be created by using the natural
form of the gullies to drain the water towards the centre of the streets. Permeable paving in
the centre of the street will drain the water into a sub-soil drain that aligns with the centre
of the street, and forms a pipe network.
Typical cambered road
Image: (Rawlings, 2013)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 16
The alleys will be lined with grass paving blocks that will increase infiltration and slow down
runoff towards the streets. The alleys may be too small to need sub-surface drains, but
consideration will be given where necessary. Any spaces in-between dwellings should be
paved with grass paving blocks.
The existing storm water pipe network has been found to be insufficient in capacity and
efficiency due to unplanned growth in population and blockages from rubbish. It may
therefore be more effective to manage surface water with a new system that does not
necessarily tie into the existing network.
It is not favourable to build a pipe network underneath people’s dwellings, or even at the
edge of the dwelling, because it is difficult to construct and maintain - so the somewhat
open space of the streets is the most convenient location for constructing a pipe network.
The open space will allow for easier maintenance and monitoring, and make the storm
water system visible so that residents are mindful of it (littering has been found to be a
major cause of blockages).
Apart from being a competent surface on which to travel, roads can serve another
important purpose - they can act as channels to direct storm water to where it is desired,
while preventing erosion of the in-situ material. The roads will be cambered and graded in
such a way that the water always flows towards a drain.
The grass serves the purpose of facilitating infiltration and slowing down runoff. The grass
will also trap and filter sediments and pollutants.
This solution does not require highly skilled workers and is labour intensive. The paving
blocks are placed by hand and the grass is planted by hand. The sub-soil drains are also
constructed by hand. No heavy machinery should be needed since the intention of the
design is to use the existing terrain as an advantage. Heavy vehicles may be needed to bring
the construction materials to site.
The grass should be planted in a season that will allow their root system to develop before
traffic is allowed on them. People should be encouraged to use their ‘grey’ water to water
the grass in winter.
The sub-soil drains will be placed under the middle of roads to drain any excess water that
does not infiltrate. The drains will not be open to the surface so litter will not be able to
enter the system. The drains will not be designed in this phase of the concept, but a typical
drain will be given.
The ‘core’ of the grass system should be planted slightly below the surface of the blocks so
that it is protected from vehicle damage.
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 17
Grass core below block surface
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 18
Limitations
There are several limitations to using grass block paving in Diepsloot:
There is a potential for root rot for prolonged periods of rain
There is a possibility of blocks uplifting or rocking if drainage is not adequate
Roots have the potential to grow underneath the blocks and cause uplift
In low traffic roads, the grass may need to be trimmed
If upstream storm water is not managed, high flows can undermine the blocks and
cause instability
Most of the construction materials may have to be bought and brought to site
Areas for Future Research
The following research opportunities exist:
Optimizing block orientation for best infiltration
Anchoring techniques for blocks to avoid layer works
Long term study on health of grass
Best species of grass to use
Uplifting of block
19
Part 3 Concept Design
3.1 Locality A trial area in Catchment 2 (Civil Concepts (Pty) Ltd, 2010), Appendix A, has been chosen
and can be seen in the images below. The storm water network in the trial area, which was
proposed by Civil Concepts, is simple enough to compare to a new design, and easy to
construct as an experimental section. The trial area is a closed-off residential area, and has
gravel roads that are approximately 6m wide, so it will be easy to assess the performance of
the grass under traffic load.
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 20
Proposed trial area
(Google Earth Image, 2010)
Proposed trial area
Image: Drawing No. SMP/ DIEP / 2 / 005 (Civil Concepts (Pty) Ltd, 2010)
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 21
3.2 Design Roads will be created using grass paving blocks that slope in the direction of the existing
ground. The roads will have enough camber (2%) and grade (1%) to ensure that water drains
towards an intended location (CSIR, 2005). Earthworks will be needed where the slope
cannot be achieved with the natural ground slope.
Any open space between dwellings will also be lined with grass paving blocks, and will be
graded to drain excess water into the roads.
Layout and drainage plans have been created to illustrate how the concept would be laid
out. The drawings can be found in Appendix D.
The blocks that are forming the roads will have sufficient sub-bases and bases – the layer
works requirements need to be assessed on site. Blocks that will not receive vehicle traffic,
may not need layer works. These blocks should just be ‘hammered’ into the ground.
The paving blocks will be Technicrete Armorflex or similar. The interlocking design of these
blocks will be beneficial in poor earthworks conditions. The specifications of the paving
blocks can be seen in Appendix B. These blocks cost approximately R200/m2.
The drains will consist of a perforated pipe in a trench surrounded by gravel. Technical
Recommendations for Highways 15 (1994) should be used as a guideline for construction of
the sub-surface drains.
3.3 Calculations Runoff calculations were done to predict the reduction in runoff that grass paving blocks
would provide.
Typical sub-surface drain illustration
Image: (Schneider Construction, n.d.)
Comment [HS1]: Brochure
Diepsloot Surface Water Technical Report
By Himkaar D. Singh 22
The hydrology calculations were done according to the SANRAL Drainage Manual 6th Edition.
The Rational Method was used since the catchment meets the recommended criteria –
catchments smaller than 15km2, and sufficient available data.
The pipes were assumed to slope at a minimum recommended value of 1% to prevent
sedimentation.
The catchments were assumed to be mainly classified as residential and streets. A typical
urban runoff coefficient for residential areas would be 0.50 to 0.70. It was assumed that by
placing permeable paving in the spaces in-between dwellings, the coefficient would be 0.70.
A typical urban street runoff coefficient would be 0.70 to 0.95. It was assumed that by
placing permeable paving in the streets the coefficient would be 0.70. Therefore, the urban
C2 coefficient is 0.67.
A summary of the results can be seen in Table 1. The spreadsheets used for calculating the
peak flow in each pipe can be found in Appendix C.
Table 1: Predicted Reduction in Runoff
Pipe Q5 without grass paving
blocks (m3/s)
Q5 with grass paving
blocks (m3/s)
Reduction %
R5_3 - R5_2 0.058 0.031 47
R5_2 - R5_1 0.122 0.064 47
R5_1 - NS5 0.590 0.128 78
R6_2 - R6_1 0.106 0.062 42
R6_1 - NS6 0.214 0.104 51
R8_1 - NS8 0.143 0.099 31
The grass paving blocks decreased the runoff coefficient and consequently reduced the
runoff by an average of 50%.
3.4 Conclusion Diepsloot is facing major surface water drainage problems. A trial section in Diepsloot was
chosen for a roads design with grass paving blocks and sub-surface drains. The grass paving
blocks add to visual appeal and reduce the runoff coefficient. The grass paving blocks have
the potential to reduce runoff by 50%.
A
3.5 Appendices
Appendix A: Locality
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NETWORK 4B
NETWORK 4A
NETWORK 2A
NETWORK 4C
NETWORK 4D
NETWORK 2B
NETWORK 6A
NETWORK 8A
NETWORK 9B
NETWORK 9A
NETWORK 10F
NETWORK 10B
NETWORK 10A
NETWORK 10C
NETWORK 10D
NETWORK 10E
DIE
PS
LOO
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UKHOZI
GH
AN
DI
DUBATSELE
GRIFFITH MXENGE
HADIFELE
AMATOLA
JUK
SKEI
RIV
ERSEBADISHO
PARK MANKAHLANA
RIVERBANK
KH
OW
A
ANDR
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SOLOMON THEKISO PLAATJIE
SIKHOSANA
CATCHMENT 10
CATCHMENT 4
CATCHMENT 2
CATCHMENT 8
CATCHMENT 9
CATCHMENT 6
DNS3
DNS32D3_15
DNS32_1
D3_4
D9_1
DNS4
D4_15
D3_15_1
DNS2
D9_3
D1_1
D9_4
D3_4_1
D4_5
D4_2
D9_3_1
D9_2
D8_1
D8_4_1
D4_18
D8_6_1 D8_8_1
D4_3_1
D10_3
D9_4_1
D3_118
D11_3
D5_1
D3_59
D3_109
D3_3
D4_21
D3_115
D4_14
D3_113
D4_16
D4_9_1
D4_7
D6_2
D6_3
D10_5
D14_19_1
D4_10
D14_17_1D14_15_1
D11_1
D14_13_1
D3_83_1
D4_52_1
D14_11_1
D3_21_1
D3_108
D4_11
D3_23_1
D7_1_1
D8_12_1
D3_12_1
D3_25_1
D10_1
D8_14_1
D3_27_1
D8_11
D8_2_1
D3_10_1
D10_6
D13_17_2
D3_85
D14_10_2
D3_87
D3_8_1
D10_4
D3_29_1 D3_31_1
D8_10_3
D6_4
D10_3_1
D6_1_1
D3_33_1
D5_2
D4_4_1
D8_13
D4_34
D4_22_1D4_24_1
D3_6_1
D5_3
D10_7
D8_15
D3_83
D4_8
D4_24_4
D3_111
D3_5
D8_12_4
D4_23
D2_2
D2_4
D4_56
D4_9_3
D4_51
D3_35_1
D4_53
D2_1
D4_1
D3_20
D3_5_1
D2_6
D12_1
D2_5
D4_57
D3_89
D2_3
D3_116
D3_30
D3_106
D6_1
D3_9
D3_7
D12_3
D3_107
D3_34
D3_32
D4_35_1 D12_5
D4_55_1
D3_28
D8_3
D3_26
D8_7D8_5
D3_13
D3_24
D3_11
D8_14_2
D12_9
D3_22
D14_10_1
D4_20
D8_9
D4_4_2
D12_11
D4_9_4
D11_1_1
D7_2
D12_7
D10_1_1
D4_17
D4_36
D13_17_1
D11_2_1
D3_19
D12_15
D3_114
D12_6_1
D4_6
D12_2_1
D8_10_1
D14_21_1
D4_13D8_12_3D8_10_4
D12_13
D12_1_1
D10_2_1
D4_24_2 D12_4_1
D12_8_1
D12_12_1
D4_38D4_25_1
D4_37_1
D12_10_1
D3_36
D12_14_1
NS1
NS2
NS7
NS3
NS5
NS6
NS8
NS4
NS9
NS10
NS11
NS12
NS13
R1_1
R2_6
R2_5
R2_4
R2_3
R2_2
R2_1
R3_3 R3_4
R3_5
R3_2
R6_4
R7_1
R7_2
R8_9R8_8R8_6R8_5R8_4
R8_2
R4_3
R4_5
R4_4
R4_2
R4_7
R4_8
R4_9
R8_1
R6_2
R5_1
R5_2
R5_3
R4_1
R9_3
R9_4
R9_2
R9_1
R10_3
R3_34
R3_31
R3_28
R3_21
R3_10
R3_19
R3_14
R4_57
R4_56R4_55R4_54R4_51
R3_15
R3_83
R3_84R3_85
R3_86
R3_88 R3_89
R8_15R8_14
R8_13R8_12
R8_11
R4_10
R4_14
R10_4
R10_5
R10_6
R10_7
R11_1
R11_3
R12_3R12_5R12_7
R4_15
R4_18
R4_19R4_21
R4_22R4_23
R4_24
R4_16
R4_9_1
R3_5_1
R3_6_1
R3_8_1
R7_1_1
R3_109R3_108
R3_107
R3_106
R3_111
R3_112
R3_113
R3_115R3_118
R3_117
R3_116
R8_8_1R8_6_1R8_4_1R8_2_1
R3_4_1
R4_9_2R4_9_3
R4_4_1
R4_4_2
R9_3_1
R9_4_1
R13_17
R4_56_1
R3_33_1R3_31_1
R3_27_1R3_25_1
R3_23_1R3_21_1
R3_10_1
R3_12_1
R4_52_1
R3_83_1
R8_14_2
R8_14_1
R8_12_4
R8_12_2
R8_12_1
R8_10_2
R8_10_1
R10_3_1
R4_22_1
R4_24_4
R4_35_1
R14_10_2
R13_17_1
R13_17_2
SAPPHIRE
GIR
AFF
E
ADELAIDE TAMBO
MBUYISA MAKHUBU
MU
VH
AN
GO
SHA
RK
DA
VID
BO
PAP
E
BA
KO
NE
MM
UTL
A
RO
BE
RT
SO
BU
KW
E
VAD
ZIM
U
BH
EKA
NI
BH
EKA
NI
MA
KH
ULO
NG
PU
MA
CLO
SE
PU
MA
CLO
SE
RAYMOND MHLABA
KO
KE
TS
OK
OK
ET
S
CA
MEL
CLO
SE
CA
MEL
CLO
SE
JULY
NK
OSI
BO
SELE
TE
AK
RU
TH
MO
MPA
TI
VUSE
LELA
MA
RTI
NLU
THE
RK
ING
DANM
OHAPIDAN
MOHAPI
GETRUDE SHOP
WA
GA
WA
GLANGALIBALELE JAB
UK
HA
NY
PE
TAT
EAERN
VU
KU
ZE
N
AC
EN
TS
OE
L
R3_6
R3_7
R3_8
R3_9
R6_3
R8_7
R8_3
R6_1
R3_R3_33
R3_32R3_30R3_29
R3_27R3_26R3_25
R3_24R3_23R3_22
R3_11
R3_12
R3_13
R3_59
R3_20
R4_53R4_52
R3_87
R8_10
R4_11
R4_13
R10_2R10_1
R11_2
R12_1R12_2
R12_4R12_6R12_8R12_9
R4_20
R4_34R4_35
R4_36
R4_37
R4_38
R3_114R3_119
R4_3_1
R4_9_4
R12_10R12_11R12_12R12_13R12_14R12_15
R
R3_29_1
R4_55_1
R8_12_3
R8_10_4
R8_10_3
R10_2_1
R10_1_1
R11_1_1
R11_2_1
R12_1_1
R12_2_1R12_4_1
R12_6_1
R12_8_1R4_24_2
R4_24_1
R4_37_1
²
REV. DATE DESCRIPTION
TOWNSHIP
PROJECT
JRA STORMWATERMASTER PLANNING
PART 2 : NETWORK MODELING
CLIENT
PO BOX 1227 TEL: (012) 365 1414PRETORIA FAX: (012) 365 1192E-MAIL [email protected]
CONSULTING CIVIL &STRUCTURAL ENGINEERS
W STANDER
W STANDER
DRAWING No.
DRAINAGE BASIN
SCALE DESIGNED
DRAWN
CHECKED
SMP / DIEP / 2 / 005
A21C_H
DIEPSLOOT
1 : 2 500B PIETERSE
NOTES:
1. RUN-OFF CALCULATION PERFORMED WITH HYDROSIM COMPUTER PROGRAM, USING THE FOLLOWING CONSTANTS:
a) RETURN PERIOD: - MAJOR SYSTEM : 25 YR - MINOR SYSTEM : 5 YR
b) MAP = 571 mm
c) % IMPERVIOUSNESS: - DENSE RESIDENTIAL : 50% - PUBLIC SPACES : 10% - OPEN FIELD : 0%
LEGEND
MAIN CATCHMENTS
SUB-CATCHMENTS
! STORMWATER NODES
!H NATURAL STREAM NODES
STORMWATER ROUTES
RIVERS
DRAINAGE DIRECTION
1 IN 50yr FLOODLINE
1 IN 100yr FLOODLINE
CONTINUES ON PLAN SMP/DIEP/2/003
CONTINUES ON PLAN SMP/DIEP/2/007
CO
NT
INU
ES
ON
PL
AN
S
MP
/DIE
P/2/00
6
Diepsloot Surface Water Technical Report
By Himkaar D. Singh C
Appendix B: Paving Block Specifications
Diepsloot Surface Water Technical Report
By Himkaar D. Singh F
Appendix C: Drainage Calculations
CIVN7068 - DIEPSLOOT Himkaar Singh
PIPE R5_3 - R5_2 DATE 24-Aug-15
PHSICAL CHARACTERISTICS RURAL (a) URBAN (b) LAKES (g)
SIZE OF CATCHMENT A = 0.00216 km2
0 1 0
LONGEST WATER COURSE LOVERLAND = 0.070 km LWATERCOURSE = 0.000 km
AVERAGE SLOPE SOVERLAND = 0.0714 m / m SWATERCOURSE = 1.000 m / m
HMAX = m H0.85L = 0.000 m
HMIN = m H0.10L = 0.000 m
DOLOMITIC = 0.0 %
LAWNS & PARKS 0
INDUSTRIAL AREAS 0
CITY/RESIDENTIAL 70
STREETS 30
0 0 0 TOTAL 100
RAINFALL
TC
0.110 HOURS CLEAN SOIL 0.1
(0.87L2/1000SAV)
0.385= 0.000 HOURS PAVED AREA 0.02
0.110 HOURS SPARSE GRASS 0.3
5 yrs MODERATE 0.4
RAINFALL 551 mm THICK BUSH 0.8
4
M 58
R 20
5 25 r = 0.1
15.4 26.5 Ft= 0.55
139.9 240.0
AREA REDUCTION 1.0 1.0
139.9 240.0
Ch = 0.000
Cd = 0.000
5 25 Cp = 0.000
0.00 0.00
0.67 0.67
0.00 0.00 CLAWNS&PARKS = 0.000
0.67 0.67 CINDUSTRIAL = 0.000
CRESIDENTIAL = 0.490
CSTREETS = 0.180
5 25
0.06 0.10
0.03 0.07
RECOMMENDED VALUES OF RUN-OFF FACTOR C
600 600-900 900
0.01 0.03 0.05 0.05-0.10
0.06 0.08 0.11 0.15-0.20
0.12 0.16 0.20 0.13-0.17
0.22 0.26 0.30 0.25-0.35
0.03 0.04 0.05 0.30-0.50
0.06 0.08 0.10 0.50-0.70
0.12 0.16 0.20
0.21 0.26 0.30
0.50-0.80
0.60-0.90
0.03 0.04 0.05
0.07 0.11 0.15
0.17 0.21 0.25 0.70-0.95
0.26 0.28 0.30 0.50-0.70
0.70-0.95
25 5 1.00
0.7 0.55
0.01 0.03 0.17
0.06 0.06 0.50
0.12 0.12 0.70
0.22 0.21 0.60
0.03 DESIGN NOTES
0.07 The point rainfall was calculated using the Modified Hershfield equation
0.17
0.26
DRAINAGE CALCULATIONS
PROJECT: CALCULATED BY:
FOR DESIGN OF:
AREA DISTRIBUTION FACTORS a+b+g=1
ELEVATIONS
VLEI'S AND PANS VERY PERMEABLE THICK BUSH AND PLANTATION
FLAT AREAS PERMEABLE LIGHT BUSH AND FARM-LANDS
RURAL URBAN
SURFACE SLOPE % PERMEABILITY % VEGETATION % USE %
VALUES OF r
TC (OVERLAND FLOW) = 0.604 ( rL/S0.5
)0.467
=
HILLY SEMI-PERMEABLE GRASS-LANDS
STEEP AREAS IMPERMEABLE NO VEGETATION
TC (WATERCOURSE) =
RETURN PERIOD =
MEAN ANNUAL =
BASIN NUMBER
RETURN PERIOD (YEARS)
TOTAL TOTAL TOTAL
RURAL C1 (Ch+Cd+Cp)
URBAN C2 URBAN C2
LAKES C3
COMBINED C=aC1+bC2+gC3
PEAK FLOW
POINT RAINFALL (mm)
POINT INTENSITY (mm/HOUR)
AVERAGE INTENSITY (mm/HOUR) RURAL C1
RUN-OFF FACTOR
RETURN PERIOD T (YEARS)
RETURN PERIOD T (YEARS)
PEAK FLOW Q = CiA/3.6 (m3/s)
ADJUSTED PEAK (m3/s) (Ft x Q)
RURAL C1 URBAN C2
COMPONENT CLASSIFICATIONMEAN AVERAGE RAINFALL (mm)
USE FACTOR
SLOPE ChHILLY (10 TO 30%) HEAVY SOIL, FLAT (<2%)
STEEP AREAS (>30%) HEAVY SOIL, STEEP (>7%)
RESIDENTIAL AREAS
LAWNS
SURFACEVLEI'S AND PANS (<3%) SANDY, FLAT (<2%)
FLAT AREAS ( 3 TO 10%) SANDY, STEEP (>7%)
LIGHT INDUSTRY
HEAVY INDUSTRY
VEGETATIONTHICK BUSH AND PLANTATION
LIGHT BUSH AND FARM-LANDS BUSINESS
PERMEABILITYVERY PERMEABLE HOUSES
PERMEABLE FLATS
CdSEMI-PERMEABLE
IMPERMEABLE INDUSTRY
RETURN PERIOD (YEARS) MAXIMUM FLOOD
ADJUSTMENT FACTOR Ft
VLEI'S AND PANS (<3%) = VERY PERMEABLE = LAWNS =
CpGRASS-LANDS CITY CENTRE
NO VEGETATION SUBURBAN
STREETS
NO VEGETATION =
STEEP AREAS (>30%) = IMPERMEABLE = STREETS =
THICK BUSH AND PLANTATION =
LIGHT BUSH AND FARM-LANDS =
GRASS-LANDS =
FLAT AREAS ( 3 TO 10%) = PERMEABLE = INDUSTRY =
HILLY (10 TO 30%) = SEMI-PERMEABLE = RESIDENTIAL AREAS =
CIVN7068 - DIEPSLOOT Himkaar Singh
PIPE R5_2 - R5_1 DATE 24-Aug-15
PHSICAL CHARACTERISTICS RURAL (a) URBAN (b) LAKES (g)
SIZE OF CATCHMENT A = 0.005118 km2
0 1 0
LONGEST WATER COURSE LOVERLAND = 0.124 km LWATERCOURSE = 0.061 km
AVERAGE SLOPE SOVERLAND = 0.0645 m / m SWATERCOURSE = 1.000 m / m
HMAX = m H0.85L = 0.000 m
HMIN = m H0.10L = 0.000 m
DOLOMITIC = 0.0 %
LAWNS & PARKS 0
INDUSTRIAL AREAS 0
CITY/RESIDENTIAL 70
STREETS 30
0 0 0 TOTAL 100
RAINFALL
TC
0.147 HOURS CLEAN SOIL 0.1
(0.87L2/1000SAV)
0.385= 0.008 HOURS PAVED AREA 0.02
0.155 HOURS SPARSE GRASS 0.3
5 yrs MODERATE 0.4
RAINFALL 551 mm THICK BUSH 0.8
4
M 58
R 20
5 25 r = 0.1
19.0 32.6 Ft= 0.55
122.4 209.9
AREA REDUCTION 1.0 1.0
122.4 209.9
Ch = 0.000
Cd = 0.000
5 25 Cp = 0.000
0.00 0.00
0.67 0.67
0.00 0.00 CLAWNS&PARKS = 0.000
0.67 0.67 CINDUSTRIAL = 0.000
CRESIDENTIAL = 0.490
CSTREETS = 0.180
5 25
0.12 0.20
0.06 0.14
RECOMMENDED VALUES OF RUN-OFF FACTOR C
600 600-900 900
0.01 0.03 0.05 0.05-0.10
0.06 0.08 0.11 0.15-0.20
0.12 0.16 0.20 0.13-0.17
0.22 0.26 0.30 0.25-0.35
0.03 0.04 0.05 0.30-0.50
0.06 0.08 0.10 0.50-0.70
0.12 0.16 0.20
0.21 0.26 0.30
0.50-0.80
0.60-0.90
0.03 0.04 0.05
0.07 0.11 0.15
0.17 0.21 0.25 0.70-0.95
0.26 0.28 0.30 0.50-0.70
0.70-0.95
25 5 1.00
0.7 0.55
0.01 0.03 0.17
0.06 0.06 0.50
0.12 0.12 0.70
0.22 0.21 0.60
0.03 DESIGN NOTES
0.07 The point rainfall was calculated using the Modified Hershfield equation
0.17
0.26NO VEGETATION =
STEEP AREAS (>30%) = IMPERMEABLE = STREETS =
LIGHT BUSH AND FARM-LANDS =
GRASS-LANDS =
FLAT AREAS ( 3 TO 10%) = PERMEABLE = INDUSTRY =
HILLY (10 TO 30%) = SEMI-PERMEABLE = RESIDENTIAL AREAS =
RETURN PERIOD (YEARS) MAXIMUM FLOOD
ADJUSTMENT FACTOR Ft
VLEI'S AND PANS (<3%) = VERY PERMEABLE = LAWNS =
CpGRASS-LANDS CITY CENTRE
NO VEGETATION SUBURBAN
STREETS
LIGHT INDUSTRY
HEAVY INDUSTRY
VEGETATIONTHICK BUSH AND PLANTATION
LIGHT BUSH AND FARM-LANDS BUSINESS
PERMEABILITYVERY PERMEABLE HOUSES
PERMEABLE FLATS
CdSEMI-PERMEABLE
IMPERMEABLE INDUSTRY
SLOPE ChHILLY (10 TO 30%) HEAVY SOIL, FLAT (<2%)
STEEP AREAS (>30%) HEAVY SOIL, STEEP (>7%)
RESIDENTIAL AREAS
LAWNS
SURFACEVLEI'S AND PANS (<3%) SANDY, FLAT (<2%)
FLAT AREAS ( 3 TO 10%) SANDY, STEEP (>7%)
COMPONENT CLASSIFICATIONMEAN AVERAGE RAINFALL (mm)
USE FACTOR
COMBINED C=aC1+bC2+gC3
PEAK FLOW
RETURN PERIOD T (YEARS)
PEAK FLOW Q = CiA/3.6 (m3/s)
ADJUSTED PEAK (m3/s) (Ft x Q)
RURAL C1
AVERAGE INTENSITY (mm/HOUR) RURAL C1
STEEP AREAS IMPERMEABLE NO VEGETATION
TOTAL TOTAL TOTAL
URBAN C2
VERY PERMEABLE THICK BUSH AND PLANTATION
HILLY SEMI-PERMEABLE GRASS-LANDS
BASIN NUMBER
POINT INTENSITY (mm/HOUR)
VALUES OF r
TC (OVERLAND FLOW) = 0.604 ( rL/S0.5
)0.467
=
FLAT AREAS PERMEABLE LIGHT BUSH AND FARM-LANDS
RETURN PERIOD (YEARS)
POINT RAINFALL (mm)
DRAINAGE CALCULATIONS
FOR DESIGN OF:
PROJECT:
THICK BUSH AND PLANTATION =
CALCULATED BY:
AREA DISTRIBUTION FACTORS a+b+g=1
ELEVATIONS
RURAL URBAN
SURFACE SLOPE % PERMEABILITY % VEGETATION %
RUN-OFF FACTOR
RETURN PERIOD T (YEARS)
RURAL C1 (Ch+Cd+Cp)
URBAN C2 URBAN C2
LAKES C3
TC (WATERCOURSE) =
RETURN PERIOD =
MEAN ANNUAL =
USE %
VLEI'S AND PANS
CIVN7068 - DIEPSLOOT Himkaar Singh
PIPE R5_1 - NS5 DATE 24-Aug-15
PHSICAL CHARACTERISTICS RURAL (a) URBAN (b) LAKES (g)
SIZE OF CATCHMENT A = 0.01113 km2
0 1 0
LONGEST WATER COURSE LOVERLAND = 0.185 km LWATERCOURSE = 0.193 km
AVERAGE SLOPE SOVERLAND = 0.0866 m / m SWATERCOURSE = 1.000 m / m
HMAX = m H0.85L = 0.000 m
HMIN = m H0.10L = 0.000 m
DOLOMITIC = 0.0 %
LAWNS & PARKS 0
INDUSTRIAL AREAS 0
CITY/RESIDENTIAL 70
STREETS 30
0 0 0 TOTAL 100
RAINFALL
TC
0.166 HOURS CLEAN SOIL 0.1
(0.87L2/1000SAV)
0.385= 0.019 HOURS PAVED AREA 0.02
0.185 HOURS SPARSE GRASS 0.3
5 yrs MODERATE 0.4
RAINFALL 551 mm THICK BUSH 0.8
4
M 58
R 20
5 25 r = 0.1
20.8 35.7 Ft= 0.55
112.6 193.2
AREA REDUCTION 1.0 1.0
112.6 193.2
Ch = 0.000
Cd = 0.000
5 25 Cp = 0.000
0.00 0.00
0.67 0.67
0.00 0.00 CLAWNS&PARKS = 0.000
0.67 0.67 CINDUSTRIAL = 0.000
CRESIDENTIAL = 0.490
CSTREETS = 0.180
5 25
0.23 0.40
0.13 0.28
RECOMMENDED VALUES OF RUN-OFF FACTOR C
600 600-900 900
0.01 0.03 0.05 0.05-0.10
0.06 0.08 0.11 0.15-0.20
0.12 0.16 0.20 0.13-0.17
0.22 0.26 0.30 0.25-0.35
0.03 0.04 0.05 0.30-0.50
0.06 0.08 0.10 0.50-0.70
0.12 0.16 0.20
0.21 0.26 0.30
0.50-0.80
0.60-0.90
0.03 0.04 0.05
0.07 0.11 0.15
0.17 0.21 0.25 0.70-0.95
0.26 0.28 0.30 0.50-0.70
0.70-0.95
25 5 1.00
0.7 0.55
0.01 0.03 0.17
0.06 0.06 0.50
0.12 0.12 0.70
0.22 0.21 0.60
0.03 DESIGN NOTES
0.07 The point rainfall was calculated using the Modified Hershfield equation
0.17
0.26
DRAINAGE CALCULATIONS
PROJECT: CALCULATED BY:
FOR DESIGN OF:
AREA DISTRIBUTION FACTORS a+b+g=1
ELEVATIONS
VLEI'S AND PANS VERY PERMEABLE THICK BUSH AND PLANTATION
FLAT AREAS PERMEABLE LIGHT BUSH AND FARM-LANDS
RURAL URBAN
SURFACE SLOPE % PERMEABILITY % VEGETATION % USE %
VALUES OF r
TC (OVERLAND FLOW) = 0.604 ( rL/S0.5
)0.467
=
HILLY SEMI-PERMEABLE GRASS-LANDS
STEEP AREAS IMPERMEABLE NO VEGETATION
TC (WATERCOURSE) =
RETURN PERIOD =
MEAN ANNUAL =
BASIN NUMBER
RETURN PERIOD (YEARS)
TOTAL TOTAL TOTAL
RURAL C1 (Ch+Cd+Cp)
URBAN C2 URBAN C2
LAKES C3
COMBINED C=aC1+bC2+gC3
PEAK FLOW
POINT RAINFALL (mm)
POINT INTENSITY (mm/HOUR)
AVERAGE INTENSITY (mm/HOUR) RURAL C1
RUN-OFF FACTOR
RETURN PERIOD T (YEARS)
RETURN PERIOD T (YEARS)
PEAK FLOW Q = CiA/3.6 (m3/s)
ADJUSTED PEAK (m3/s) (Ft x Q)
RURAL C1 URBAN C2
COMPONENT CLASSIFICATIONMEAN AVERAGE RAINFALL (mm)
USE FACTOR
SLOPE ChHILLY (10 TO 30%) HEAVY SOIL, FLAT (<2%)
STEEP AREAS (>30%) HEAVY SOIL, STEEP (>7%)
RESIDENTIAL AREAS
LAWNS
SURFACEVLEI'S AND PANS (<3%) SANDY, FLAT (<2%)
FLAT AREAS ( 3 TO 10%) SANDY, STEEP (>7%)
LIGHT INDUSTRY
HEAVY INDUSTRY
VEGETATIONTHICK BUSH AND PLANTATION
LIGHT BUSH AND FARM-LANDS BUSINESS
PERMEABILITYVERY PERMEABLE HOUSES
PERMEABLE FLATS
CdSEMI-PERMEABLE
IMPERMEABLE INDUSTRY
RETURN PERIOD (YEARS) MAXIMUM FLOOD
ADJUSTMENT FACTOR Ft
VLEI'S AND PANS (<3%) = VERY PERMEABLE = LAWNS =
CpGRASS-LANDS CITY CENTRE
NO VEGETATION SUBURBAN
STREETS
NO VEGETATION =
STEEP AREAS (>30%) = IMPERMEABLE = STREETS =
THICK BUSH AND PLANTATION =
LIGHT BUSH AND FARM-LANDS =
GRASS-LANDS =
FLAT AREAS ( 3 TO 10%) = PERMEABLE = INDUSTRY =
HILLY (10 TO 30%) = SEMI-PERMEABLE = RESIDENTIAL AREAS =
CIVN7068 - DIEPSLOOT Himkaar Singh
PPIE R6_2 - R6_1 DATE 24-Aug-15
PHSICAL CHARACTERISTICS RURAL (a) URBAN (b) LAKES (g)
SIZE OF CATCHMENT A = 0.005222 km2
0 1 0
LONGEST WATER COURSE LOVERLAND = 0.179 km LWATERCOURSE = 0.000 km
AVERAGE SLOPE SOVERLAND = 0.0616 m / m SWATERCOURSE = 1.000 m / m
HMAX = m H0.85L = 0.000 m
HMIN = m H0.10L = 0.000 m
DOLOMITIC = 0.0 %
LAWNS & PARKS 0
INDUSTRIAL AREAS 0
CITY/RESIDENTIAL 70
STREETS 30
0 0 0 TOTAL 100
RAINFALL
TC
0.177 HOURS CLEAN SOIL 0.1
(0.87L2/1000SAV)
0.385= 0.000 HOURS PAVED AREA 0.02
0.177 HOURS SPARSE GRASS 0.3
5 yrs MODERATE 0.4
RAINFALL 551 mm THICK BUSH 0.8
4
M 58
R 20
5 25 r = 0.1
20.3 34.9 Ft= 0.55
115.1 197.4
AREA REDUCTION 1.0 1.0
115.1 197.4
Ch = 0.000
Cd = 0.000
5 25 Cp = 0.000
0.00 0.00
0.67 0.67
0.00 0.00 CLAWNS&PARKS = 0.000
0.67 0.67 CINDUSTRIAL = 0.000
CRESIDENTIAL = 0.490
CSTREETS = 0.180
5 25
0.11 0.19
0.06 0.13
RECOMMENDED VALUES OF RUN-OFF FACTOR C
600 600-900 900
0.01 0.03 0.05 0.05-0.10
0.06 0.08 0.11 0.15-0.20
0.12 0.16 0.20 0.13-0.17
0.22 0.26 0.30 0.25-0.35
0.03 0.04 0.05 0.30-0.50
0.06 0.08 0.10 0.50-0.70
0.12 0.16 0.20
0.21 0.26 0.30
0.50-0.80
0.60-0.90
0.03 0.04 0.05
0.07 0.11 0.15
0.17 0.21 0.25 0.70-0.95
0.26 0.28 0.30 0.50-0.70
0.70-0.95
25 5 1.00
0.7 0.55
0.01 0.03 0.17
0.06 0.06 0.50
0.12 0.12 0.70
0.22 0.21 0.60
0.03 DESIGN NOTES
0.07 The point rainfall was calculated using the Modified Hershfield equation
0.17
0.26
DRAINAGE CALCULATIONS
PROJECT: CALCULATED BY:
FOR DESIGN OF:
AREA DISTRIBUTION FACTORS a+b+g=1
ELEVATIONS
VLEI'S AND PANS VERY PERMEABLE THICK BUSH AND PLANTATION
FLAT AREAS PERMEABLE LIGHT BUSH AND FARM-LANDS
RURAL URBAN
SURFACE SLOPE % PERMEABILITY % VEGETATION % USE %
VALUES OF r
TC (OVERLAND FLOW) = 0.604 ( rL/S0.5
)0.467
=
HILLY SEMI-PERMEABLE GRASS-LANDS
STEEP AREAS IMPERMEABLE NO VEGETATION
TC (WATERCOURSE) =
RETURN PERIOD =
MEAN ANNUAL =
BASIN NUMBER
RETURN PERIOD (YEARS)
TOTAL TOTAL TOTAL
RURAL C1 (Ch+Cd+Cp)
URBAN C2 URBAN C2
LAKES C3
COMBINED C=aC1+bC2+gC3
PEAK FLOW
POINT RAINFALL (mm)
POINT INTENSITY (mm/HOUR)
AVERAGE INTENSITY (mm/HOUR) RURAL C1
RUN-OFF FACTOR
RETURN PERIOD T (YEARS)
RETURN PERIOD T (YEARS)
PEAK FLOW Q = CiA/3.6 (m3/s)
ADJUSTED PEAK (m3/s) (Ft x Q)
RURAL C1 URBAN C2
COMPONENT CLASSIFICATIONMEAN AVERAGE RAINFALL (mm)
USE FACTOR
SLOPE ChHILLY (10 TO 30%) HEAVY SOIL, FLAT (<2%)
STEEP AREAS (>30%) HEAVY SOIL, STEEP (>7%)
RESIDENTIAL AREAS
LAWNS
SURFACEVLEI'S AND PANS (<3%) SANDY, FLAT (<2%)
FLAT AREAS ( 3 TO 10%) SANDY, STEEP (>7%)
LIGHT INDUSTRY
HEAVY INDUSTRY
VEGETATIONTHICK BUSH AND PLANTATION
LIGHT BUSH AND FARM-LANDS BUSINESS
PERMEABILITYVERY PERMEABLE HOUSES
PERMEABLE FLATS
CdSEMI-PERMEABLE
IMPERMEABLE INDUSTRY
RETURN PERIOD (YEARS) MAXIMUM FLOOD
ADJUSTMENT FACTOR Ft
VLEI'S AND PANS (<3%) = VERY PERMEABLE = LAWNS =
CpGRASS-LANDS CITY CENTRE
NO VEGETATION SUBURBAN
STREETS
NO VEGETATION =
STEEP AREAS (>30%) = IMPERMEABLE = STREETS =
THICK BUSH AND PLANTATION =
LIGHT BUSH AND FARM-LANDS =
GRASS-LANDS =
FLAT AREAS ( 3 TO 10%) = PERMEABLE = INDUSTRY =
HILLY (10 TO 30%) = SEMI-PERMEABLE = RESIDENTIAL AREAS =
CIVN7068 - DIEPSLOOT Himkaar Singh
PPIE R6_2 - NS6 DATE 24-Aug-15
PHSICAL CHARACTERISTICS RURAL (a) URBAN (b) LAKES (g)
SIZE OF CATCHMENT A = 0.009288 km2
0 1 0
LONGEST WATER COURSE LOVERLAND = 0.220 km LWATERCOURSE = 0.044 km
AVERAGE SLOPE SOVERLAND = 0.0682 m / m SWATERCOURSE = 1.000 m / m
HMAX = m H0.85L = 0.000 m
HMIN = m H0.10L = 0.000 m
DOLOMITIC = 0.0 %
LAWNS & PARKS 0
INDUSTRIAL AREAS 0
CITY/RESIDENTIAL 70
STREETS 30
0 0 0 TOTAL 100
RAINFALL
TC
0.190 HOURS CLEAN SOIL 0.1
(0.87L2/1000SAV)
0.385= 0.006 HOURS PAVED AREA 0.02
0.196 HOURS SPARSE GRASS 0.3
5 yrs MODERATE 0.4
RAINFALL 551 mm THICK BUSH 0.8
4
M 58
R 20
5 25 r = 0.1
21.4 36.7 Ft= 0.55
109.2 187.3
AREA REDUCTION 1.0 1.0
109.2 187.3
Ch = 0.000
Cd = 0.000
5 25 Cp = 0.000
0.00 0.00
0.67 0.67
0.00 0.00 CLAWNS&PARKS = 0.000
0.67 0.67 CINDUSTRIAL = 0.000
CRESIDENTIAL = 0.490
CSTREETS = 0.180
5 25
0.19 0.32
0.10 0.23
RECOMMENDED VALUES OF RUN-OFF FACTOR C
600 600-900 900
0.01 0.03 0.05 0.05-0.10
0.06 0.08 0.11 0.15-0.20
0.12 0.16 0.20 0.13-0.17
0.22 0.26 0.30 0.25-0.35
0.03 0.04 0.05 0.30-0.50
0.06 0.08 0.10 0.50-0.70
0.12 0.16 0.20
0.21 0.26 0.30
0.50-0.80
0.60-0.90
0.03 0.04 0.05
0.07 0.11 0.15
0.17 0.21 0.25 0.70-0.95
0.26 0.28 0.30 0.50-0.70
0.70-0.95
25 5 1.00
0.7 0.55
0.01 0.03 0.17
0.06 0.06 0.50
0.12 0.12 0.70
0.22 0.21 0.60
0.03 DESIGN NOTES
0.07 The point rainfall was calculated using the Modified Hershfield equation
0.17
0.26
DRAINAGE CALCULATIONS
PROJECT: CALCULATED BY:
FOR DESIGN OF:
AREA DISTRIBUTION FACTORS a+b+g=1
ELEVATIONS
VLEI'S AND PANS VERY PERMEABLE THICK BUSH AND PLANTATION
FLAT AREAS PERMEABLE LIGHT BUSH AND FARM-LANDS
RURAL URBAN
SURFACE SLOPE % PERMEABILITY % VEGETATION % USE %
VALUES OF r
TC (OVERLAND FLOW) = 0.604 ( rL/S0.5
)0.467
=
HILLY SEMI-PERMEABLE GRASS-LANDS
STEEP AREAS IMPERMEABLE NO VEGETATION
TC (WATERCOURSE) =
RETURN PERIOD =
MEAN ANNUAL =
BASIN NUMBER
RETURN PERIOD (YEARS)
TOTAL TOTAL TOTAL
RURAL C1 (Ch+Cd+Cp)
URBAN C2 URBAN C2
LAKES C3
COMBINED C=aC1+bC2+gC3
PEAK FLOW
POINT RAINFALL (mm)
POINT INTENSITY (mm/HOUR)
AVERAGE INTENSITY (mm/HOUR) RURAL C1
RUN-OFF FACTOR
RETURN PERIOD T (YEARS)
RETURN PERIOD T (YEARS)
PEAK FLOW Q = CiA/3.6 (m3/s)
ADJUSTED PEAK (m3/s) (Ft x Q)
RURAL C1 URBAN C2
COMPONENT CLASSIFICATIONMEAN AVERAGE RAINFALL (mm)
USE FACTOR
SLOPE ChHILLY (10 TO 30%) HEAVY SOIL, FLAT (<2%)
STEEP AREAS (>30%) HEAVY SOIL, STEEP (>7%)
RESIDENTIAL AREAS
LAWNS
SURFACEVLEI'S AND PANS (<3%) SANDY, FLAT (<2%)
FLAT AREAS ( 3 TO 10%) SANDY, STEEP (>7%)
LIGHT INDUSTRY
HEAVY INDUSTRY
VEGETATIONTHICK BUSH AND PLANTATION
LIGHT BUSH AND FARM-LANDS BUSINESS
PERMEABILITYVERY PERMEABLE HOUSES
PERMEABLE FLATS
CdSEMI-PERMEABLE
IMPERMEABLE INDUSTRY
RETURN PERIOD (YEARS) MAXIMUM FLOOD
ADJUSTMENT FACTOR Ft
VLEI'S AND PANS (<3%) = VERY PERMEABLE = LAWNS =
CpGRASS-LANDS CITY CENTRE
NO VEGETATION SUBURBAN
STREETS
NO VEGETATION =
STEEP AREAS (>30%) = IMPERMEABLE = STREETS =
THICK BUSH AND PLANTATION =
LIGHT BUSH AND FARM-LANDS =
GRASS-LANDS =
FLAT AREAS ( 3 TO 10%) = PERMEABLE = INDUSTRY =
HILLY (10 TO 30%) = SEMI-PERMEABLE = RESIDENTIAL AREAS =
CIVN7068 - DIEPSLOOT Himkaar Singh
PPIE R8_1 - NS8 DATE 24-Aug-15
PHSICAL CHARACTERISTICS RURAL (a) URBAN (b) LAKES (g)
SIZE OF CATCHMENT A = 0.009361 km2
0 1 0
LONGEST WATER COURSE LOVERLAND = 0.247 km LWATERCOURSE = 0.000 km
AVERAGE SLOPE SOVERLAND = 0.0486 m / m SWATERCOURSE = 1.000 m / m
HMAX = m H0.85L = 0.000 m
HMIN = m H0.10L = 0.000 m
DOLOMITIC = 0.0 %
LAWNS & PARKS 0
INDUSTRIAL AREAS 0
CITY/RESIDENTIAL 70
STREETS 30
0 0 0 TOTAL 100
RAINFALL
TC
0.217 HOURS CLEAN SOIL 0.1
(0.87L2/1000SAV)
0.385= 0.000 HOURS PAVED AREA 0.02
0.217 HOURS SPARSE GRASS 0.3
5 yrs MODERATE 0.4
RAINFALL 551 mm THICK BUSH 0.8
4
M 58
R 20
5 25 r = 0.1
22.5 38.6 Ft= 0.55
103.5 177.5
AREA REDUCTION 1.0 1.0
103.5 177.5
Ch = 0.000
Cd = 0.000
5 25 Cp = 0.000
0.00 0.00
0.67 0.67
0.00 0.00 CLAWNS&PARKS = 0.000
0.67 0.67 CINDUSTRIAL = 0.000
CRESIDENTIAL = 0.490
CSTREETS = 0.180
5 25
0.18 0.31
0.10 0.22
RECOMMENDED VALUES OF RUN-OFF FACTOR C
600 600-900 900
0.01 0.03 0.05 0.05-0.10
0.06 0.08 0.11 0.15-0.20
0.12 0.16 0.20 0.13-0.17
0.22 0.26 0.30 0.25-0.35
0.03 0.04 0.05 0.30-0.50
0.06 0.08 0.10 0.50-0.70
0.12 0.16 0.20
0.21 0.26 0.30
0.50-0.80
0.60-0.90
0.03 0.04 0.05
0.07 0.11 0.15
0.17 0.21 0.25 0.70-0.95
0.26 0.28 0.30 0.50-0.70
0.70-0.95
25 5 1.00
0.7 0.55
0.01 0.03 0.17
0.06 0.06 0.50
0.12 0.12 0.70
0.22 0.21 0.60
0.03 DESIGN NOTES
0.07 The point rainfall was calculated using the Modified Hershfield equation
0.17
0.26
DRAINAGE CALCULATIONS
PROJECT: CALCULATED BY:
FOR DESIGN OF:
AREA DISTRIBUTION FACTORS a+b+g=1
ELEVATIONS
VLEI'S AND PANS VERY PERMEABLE THICK BUSH AND PLANTATION
FLAT AREAS PERMEABLE LIGHT BUSH AND FARM-LANDS
RURAL URBAN
SURFACE SLOPE % PERMEABILITY % VEGETATION % USE %
VALUES OF r
TC (OVERLAND FLOW) = 0.604 ( rL/S0.5
)0.467
=
HILLY SEMI-PERMEABLE GRASS-LANDS
STEEP AREAS IMPERMEABLE NO VEGETATION
TC (WATERCOURSE) =
RETURN PERIOD =
MEAN ANNUAL =
BASIN NUMBER
RETURN PERIOD (YEARS)
TOTAL TOTAL TOTAL
RURAL C1 (Ch+Cd+Cp)
URBAN C2 URBAN C2
LAKES C3
COMBINED C=aC1+bC2+gC3
PEAK FLOW
POINT RAINFALL (mm)
POINT INTENSITY (mm/HOUR)
AVERAGE INTENSITY (mm/HOUR) RURAL C1
RUN-OFF FACTOR
RETURN PERIOD T (YEARS)
RETURN PERIOD T (YEARS)
PEAK FLOW Q = CiA/3.6 (m3/s)
ADJUSTED PEAK (m3/s) (Ft x Q)
RURAL C1 URBAN C2
COMPONENT CLASSIFICATIONMEAN AVERAGE RAINFALL (mm)
USE FACTOR
SLOPE ChHILLY (10 TO 30%) HEAVY SOIL, FLAT (<2%)
STEEP AREAS (>30%) HEAVY SOIL, STEEP (>7%)
RESIDENTIAL AREAS
LAWNS
SURFACEVLEI'S AND PANS (<3%) SANDY, FLAT (<2%)
FLAT AREAS ( 3 TO 10%) SANDY, STEEP (>7%)
LIGHT INDUSTRY
HEAVY INDUSTRY
VEGETATIONTHICK BUSH AND PLANTATION
LIGHT BUSH AND FARM-LANDS BUSINESS
PERMEABILITYVERY PERMEABLE HOUSES
PERMEABLE FLATS
CdSEMI-PERMEABLE
IMPERMEABLE INDUSTRY
RETURN PERIOD (YEARS) MAXIMUM FLOOD
ADJUSTMENT FACTOR Ft
VLEI'S AND PANS (<3%) = VERY PERMEABLE = LAWNS =
CpGRASS-LANDS CITY CENTRE
NO VEGETATION SUBURBAN
STREETS
NO VEGETATION =
STEEP AREAS (>30%) = IMPERMEABLE = STREETS =
THICK BUSH AND PLANTATION =
LIGHT BUSH AND FARM-LANDS =
GRASS-LANDS =
FLAT AREAS ( 3 TO 10%) = PERMEABLE = INDUSTRY =
HILLY (10 TO 30%) = SEMI-PERMEABLE = RESIDENTIAL AREAS =
Diepsloot Surface Water Technical Report
By Himkaar D. Singh M
Appendix D: Layout and Drainage Plans
STREETS TO BE PERMEABLE PAVING
SPACE IN-BETWEEN DWELLINGS TO BE PERMEABLE PAVIN
SUB-SURFACE DRAINS
DIEPSLOOT STORM WATER DESIGN
2124-Aug-2015
H. SINGH
H. SINGH
1:500CIVN7068 - C00124-Aug-15 PRELIMINARY ISSUE
CIVN7068 - C001ROADS ANDSTORMWATER
DIEPSLOOT STORM WATER -NETWORK 2A - PAVING LAYOUT
P0
R5_3
R5_2
R5-1
R6_2
R6_1
R8_1
D8_1A=9361m²
D6_2A=5222m²
D5_3A=2160m²
D5_2A=2959m²
D5_1A=6012m²
D6_1_1A=3666m²
D6_1A=400m²
Q5=0.03m³/s
Q5=0.06m³/s
Q5=0.13m³/s
Q5=0.10m³/s
Q5=0.1m³/s
Q5=0.06m³/s
NS5
NS6SUB
SURFACEDRAIN
CATCHMENT BOUNDARY
DIEPSLOOT STORM WATER DESIGN
2224-Aug-2015
H. SINGH
H. SINGH
1:500CIVN7068 - C00224-Aug-15 PRELIMINARY ISSUE
CIVN7068 - C001ROADS ANDSTORMWATER
DIEPSLOOT STORM WATER -NETWORK 2A - CATCHMENTANALYSIS P0
I
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Image on cover page obtained from (Dini, 2010)